1 /* -*- Mode: C; tab-width: 4 -*-
2  *
3  * Copyright (c) 2002-2006 Apple Computer, Inc. All rights reserved.
4  *
5  * Licensed under the Apache License, Version 2.0 (the "License");
6  * you may not use this file except in compliance with the License.
7  * You may obtain a copy of the License at
8  *
9  *     http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  *
17  * This code is completely 100% portable C. It does not depend on any external header files
18  * from outside the mDNS project -- all the types it expects to find are defined right here.
19  *
20  * The previous point is very important: This file does not depend on any external
21  * header files. It should compile on *any* platform that has a C compiler, without
22  * making *any* assumptions about availability of so-called "standard" C functions,
23  * routines, or types (which may or may not be present on any given platform).
24 
25  * Formatting notes:
26  * This code follows the "Whitesmiths style" C indentation rules. Plenty of discussion
27  * on C indentation can be found on the web, such as <http://www.kafejo.com/komp/1tbs.htm>,
28  * but for the sake of brevity here I will say just this: Curly braces are not syntactially
29  * part of an "if" statement; they are the beginning and ending markers of a compound statement;
30  * therefore common sense dictates that if they are part of a compound statement then they
31  * should be indented to the same level as everything else in that compound statement.
32  * Indenting curly braces at the same level as the "if" implies that curly braces are
33  * part of the "if", which is false. (This is as misleading as people who write "char* x,y;"
34  * thinking that variables x and y are both of type "char*" -- and anyone who doesn't
35  * understand why variable y is not of type "char*" just proves the point that poor code
36  * layout leads people to unfortunate misunderstandings about how the C language really works.)
37  */
38 
39 #include "DNSCommon.h"                  // Defines general DNS untility routines
40 #include "uDNS.h"						// Defines entry points into unicast-specific routines
41 
42 // Disable certain benign warnings with Microsoft compilers
43 #if(defined(_MSC_VER))
44 	// Disable "conditional expression is constant" warning for debug macros.
45 	// Otherwise, this generates warnings for the perfectly natural construct "while(1)"
46 	// If someone knows a variant way of writing "while(1)" that doesn't generate warning messages, please let us know
47 	#pragma warning(disable:4127)
48 
49 	// Disable "assignment within conditional expression".
50 	// Other compilers understand the convention that if you place the assignment expression within an extra pair
51 	// of parentheses, this signals to the compiler that you really intended an assignment and no warning is necessary.
52 	// The Microsoft compiler doesn't understand this convention, so in the absense of any other way to signal
53 	// to the compiler that the assignment is intentional, we have to just turn this warning off completely.
54 	#pragma warning(disable:4706)
55 #endif
56 
57 #if APPLE_OSX_mDNSResponder
58 
59 #include <WebFilterDNS/WebFilterDNS.h>
60 
61 #if ! NO_WCF
62 WCFConnection *WCFConnectionNew(void) __attribute__((weak_import));
63 void WCFConnectionDealloc(WCFConnection* c) __attribute__((weak_import));
64 
65 // Do we really need to define a macro for "if"?
66 #define CHECK_WCF_FUNCTION(X) if (X)
67 #endif // ! NO_WCF
68 
69 #else
70 
71 #define NO_WCF 1
72 #endif // APPLE_OSX_mDNSResponder
73 
74 // Forward declarations
75 mDNSlocal void BeginSleepProcessing(mDNS *const m);
76 mDNSlocal void RetrySPSRegistrations(mDNS *const m);
77 mDNSlocal void SendWakeup(mDNS *const m, mDNSInterfaceID InterfaceID, mDNSEthAddr *EthAddr, mDNSOpaque48 *password);
78 mDNSlocal mDNSBool CacheRecordRmvEventsForQuestion(mDNS *const m, DNSQuestion *q);
79 mDNSlocal mDNSBool LocalRecordRmvEventsForQuestion(mDNS *const m, DNSQuestion *q);
80 mDNSlocal void mDNS_PurgeBeforeResolve(mDNS *const m, DNSQuestion *q);
81 
82 // ***************************************************************************
83 #if COMPILER_LIKES_PRAGMA_MARK
84 #pragma mark - Program Constants
85 #endif
86 
87 #define NO_HINFO 1
88 
89 
90 // Any records bigger than this are considered 'large' records
91 #define SmallRecordLimit 1024
92 
93 #define kMaxUpdateCredits 10
94 #define kUpdateCreditRefreshInterval (mDNSPlatformOneSecond * 6)
95 
96 mDNSexport const char *const mDNS_DomainTypeNames[] =
97 	{
98 	 "b._dns-sd._udp.",		// Browse
99 	"db._dns-sd._udp.",		// Default Browse
100 	"lb._dns-sd._udp.",		// Automatic Browse
101 	 "r._dns-sd._udp.",		// Registration
102 	"dr._dns-sd._udp."		// Default Registration
103 	};
104 
105 #ifdef UNICAST_DISABLED
106 #define uDNS_IsActiveQuery(q, u) mDNSfalse
107 #endif
108 
109 // ***************************************************************************
110 #if COMPILER_LIKES_PRAGMA_MARK
111 #pragma mark -
112 #pragma mark - General Utility Functions
113 #endif
114 
115 // If there is a authoritative LocalOnly record that answers questions of type A, AAAA and CNAME
116 // this returns true. Main use is to handle /etc/hosts records.
117 #define LORecordAnswersAddressType(rr) ((rr)->ARType == AuthRecordLocalOnly && \
118 									(rr)->resrec.RecordType & kDNSRecordTypeUniqueMask && \
119 									((rr)->resrec.rrtype == kDNSType_A || (rr)->resrec.rrtype == kDNSType_AAAA || \
120 									(rr)->resrec.rrtype == kDNSType_CNAME))
121 
122 #define FollowCNAME(q, rr, AddRecord)	(AddRecord && (q)->qtype != kDNSType_CNAME && \
123 										(rr)->RecordType != kDNSRecordTypePacketNegative && \
124 										(rr)->rrtype == kDNSType_CNAME)
125 
SetNextQueryStopTime(mDNS * const m,const DNSQuestion * const q)126 mDNSlocal void SetNextQueryStopTime(mDNS *const m, const DNSQuestion *const q)
127 	{
128 	if (m->mDNS_busy != m->mDNS_reentrancy+1)
129 		LogMsg("SetNextQueryTime: Lock not held! mDNS_busy (%ld) mDNS_reentrancy (%ld)", m->mDNS_busy, m->mDNS_reentrancy);
130 
131 #if ForceAlerts
132 	if (m->mDNS_busy != m->mDNS_reentrancy+1) *(long*)0 = 0;
133 #endif
134 
135 	if (m->NextScheduledStopTime - q->StopTime > 0)
136 		m->NextScheduledStopTime = q->StopTime;
137 	}
138 
SetNextQueryTime(mDNS * const m,const DNSQuestion * const q)139 mDNSexport void SetNextQueryTime(mDNS *const m, const DNSQuestion *const q)
140 	{
141 	if (m->mDNS_busy != m->mDNS_reentrancy+1)
142 		LogMsg("SetNextQueryTime: Lock not held! mDNS_busy (%ld) mDNS_reentrancy (%ld)", m->mDNS_busy, m->mDNS_reentrancy);
143 
144 #if ForceAlerts
145 	if (m->mDNS_busy != m->mDNS_reentrancy+1) *(long*)0 = 0;
146 #endif
147 
148 	if (ActiveQuestion(q))
149 		{
150 		// Depending on whether this is a multicast or unicast question we want to set either:
151 		// m->NextScheduledQuery = NextQSendTime(q) or
152 		// m->NextuDNSEvent      = NextQSendTime(q)
153 		mDNSs32 *const timer = mDNSOpaque16IsZero(q->TargetQID) ? &m->NextScheduledQuery : &m->NextuDNSEvent;
154 		if (*timer - NextQSendTime(q) > 0)
155 			*timer = NextQSendTime(q);
156 		}
157 	}
158 
ReleaseAuthEntity(AuthHash * r,AuthEntity * e)159 mDNSlocal void ReleaseAuthEntity(AuthHash *r, AuthEntity *e)
160 	{
161 #if APPLE_OSX_mDNSResponder && MACOSX_MDNS_MALLOC_DEBUGGING >= 1
162 	unsigned int i;
163 	for (i=0; i<sizeof(*e); i++) ((char*)e)[i] = 0xFF;
164 #endif
165 	e->next = r->rrauth_free;
166 	r->rrauth_free = e;
167 	r->rrauth_totalused--;
168 	}
169 
ReleaseAuthGroup(AuthHash * r,AuthGroup ** cp)170 mDNSlocal void ReleaseAuthGroup(AuthHash *r, AuthGroup **cp)
171 	{
172 	AuthEntity *e = (AuthEntity *)(*cp);
173 	LogMsg("ReleaseAuthGroup:  Releasing AuthGroup %##s", (*cp)->name->c);
174 	if ((*cp)->rrauth_tail != &(*cp)->members)
175 		LogMsg("ERROR: (*cp)->members == mDNSNULL but (*cp)->rrauth_tail != &(*cp)->members)");
176 	if ((*cp)->name != (domainname*)((*cp)->namestorage)) mDNSPlatformMemFree((*cp)->name);
177 	(*cp)->name = mDNSNULL;
178 	*cp = (*cp)->next;			// Cut record from list
179 	ReleaseAuthEntity(r, e);
180 	}
181 
GetAuthEntity(AuthHash * r,const AuthGroup * const PreserveAG)182 mDNSlocal AuthEntity *GetAuthEntity(AuthHash *r, const AuthGroup *const PreserveAG)
183 	{
184 	AuthEntity *e = mDNSNULL;
185 
186 	if (r->rrauth_lock) { LogMsg("GetFreeCacheRR ERROR! Cache already locked!"); return(mDNSNULL); }
187 	r->rrauth_lock = 1;
188 
189 	if (!r->rrauth_free)
190 		{
191 		// We allocate just one AuthEntity at a time because we need to be able
192 		// free them all individually which normally happens when we parse /etc/hosts into
193 		// AuthHash where we add the "new" entries and discard (free) the already added
194 		// entries. If we allocate as chunks, we can't free them individually.
195 		AuthEntity *storage = mDNSPlatformMemAllocate(sizeof(AuthEntity));
196 		storage->next = mDNSNULL;
197 		r->rrauth_free = storage;
198 		}
199 
200 	// If we still have no free records, recycle all the records we can.
201 	// Enumerating the entire auth is moderately expensive, so when we do it, we reclaim all the records we can in one pass.
202 	if (!r->rrauth_free)
203 		{
204 		mDNSu32 oldtotalused = r->rrauth_totalused;
205 		mDNSu32 slot;
206 		for (slot = 0; slot < AUTH_HASH_SLOTS; slot++)
207 			{
208 			AuthGroup **cp = &r->rrauth_hash[slot];
209 			while (*cp)
210 				{
211 				if ((*cp)->members || (*cp)==PreserveAG) cp=&(*cp)->next;
212 				else ReleaseAuthGroup(r, cp);
213 				}
214 			}
215 		LogInfo("GetAuthEntity: Recycled %d records to reduce auth cache from %d to %d",
216 			oldtotalused - r->rrauth_totalused, oldtotalused, r->rrauth_totalused);
217 		}
218 
219 	if (r->rrauth_free)	// If there are records in the free list, take one
220 		{
221 		e = r->rrauth_free;
222 		r->rrauth_free = e->next;
223 		if (++r->rrauth_totalused >= r->rrauth_report)
224 			{
225 			LogInfo("RR Auth now using %ld objects", r->rrauth_totalused);
226 			if      (r->rrauth_report <  100) r->rrauth_report += 10;
227 			else if (r->rrauth_report < 1000) r->rrauth_report += 100;
228 			else                               r->rrauth_report += 1000;
229 			}
230 		mDNSPlatformMemZero(e, sizeof(*e));
231 		}
232 
233 	r->rrauth_lock = 0;
234 
235 	return(e);
236 	}
237 
AuthGroupForName(AuthHash * r,const mDNSu32 slot,const mDNSu32 namehash,const domainname * const name)238 mDNSexport AuthGroup *AuthGroupForName(AuthHash *r, const mDNSu32 slot, const mDNSu32 namehash, const domainname *const name)
239 	{
240 	AuthGroup *ag;
241 	for (ag = r->rrauth_hash[slot]; ag; ag=ag->next)
242 		if (ag->namehash == namehash && SameDomainName(ag->name, name))
243 			break;
244 	return(ag);
245 	}
246 
AuthGroupForRecord(AuthHash * r,const mDNSu32 slot,const ResourceRecord * const rr)247 mDNSexport AuthGroup *AuthGroupForRecord(AuthHash *r, const mDNSu32 slot, const ResourceRecord *const rr)
248 	{
249 	return(AuthGroupForName(r, slot, rr->namehash, rr->name));
250 	}
251 
GetAuthGroup(AuthHash * r,const mDNSu32 slot,const ResourceRecord * const rr)252 mDNSlocal AuthGroup *GetAuthGroup(AuthHash *r, const mDNSu32 slot, const ResourceRecord *const rr)
253 	{
254 	mDNSu16 namelen = DomainNameLength(rr->name);
255 	AuthGroup *ag = (AuthGroup*)GetAuthEntity(r, mDNSNULL);
256 	if (!ag) { LogMsg("GetAuthGroup: Failed to allocate memory for %##s", rr->name->c); return(mDNSNULL); }
257 	ag->next         = r->rrauth_hash[slot];
258 	ag->namehash     = rr->namehash;
259 	ag->members      = mDNSNULL;
260 	ag->rrauth_tail  = &ag->members;
261 	ag->name         = (domainname*)ag->namestorage;
262 	ag->NewLocalOnlyRecords = mDNSNULL;
263 	if (namelen > InlineCacheGroupNameSize) ag->name = mDNSPlatformMemAllocate(namelen);
264 	if (!ag->name)
265 		{
266 		LogMsg("GetAuthGroup: Failed to allocate name storage for %##s", rr->name->c);
267 		ReleaseAuthEntity(r, (AuthEntity*)ag);
268 		return(mDNSNULL);
269 		}
270 	AssignDomainName(ag->name, rr->name);
271 
272 	if (AuthGroupForRecord(r, slot, rr)) LogMsg("GetAuthGroup: Already have AuthGroup for %##s", rr->name->c);
273 	r->rrauth_hash[slot] = ag;
274 	if (AuthGroupForRecord(r, slot, rr) != ag) LogMsg("GetAuthGroup: Not finding AuthGroup for %##s", rr->name->c);
275 
276 	return(ag);
277 	}
278 
279 // Returns the AuthGroup in which the AuthRecord was inserted
InsertAuthRecord(mDNS * const m,AuthHash * r,AuthRecord * rr)280 mDNSexport AuthGroup *InsertAuthRecord(mDNS *const m, AuthHash *r, AuthRecord *rr)
281 	{
282 	AuthGroup *ag;
283 	const mDNSu32 slot = AuthHashSlot(rr->resrec.name);
284 	ag = AuthGroupForRecord(r, slot, &rr->resrec);
285 	if (!ag) ag = GetAuthGroup(r, slot, &rr->resrec);	// If we don't have a AuthGroup for this name, make one now
286 	if (ag)
287 		{
288 		LogInfo("InsertAuthRecord: inserting auth record %s from table", ARDisplayString(m, rr));
289 		*(ag->rrauth_tail) = rr;				// Append this record to tail of cache slot list
290 		ag->rrauth_tail = &(rr->next);			// Advance tail pointer
291 		}
292 	return ag;
293 	}
294 
RemoveAuthRecord(mDNS * const m,AuthHash * r,AuthRecord * rr)295 mDNSexport AuthGroup *RemoveAuthRecord(mDNS *const m, AuthHash *r, AuthRecord *rr)
296 	{
297 	AuthGroup *a;
298 	AuthGroup **ag = &a;
299 	AuthRecord **rp;
300 	const mDNSu32 slot = AuthHashSlot(rr->resrec.name);
301 
302 	a = AuthGroupForRecord(r, slot, &rr->resrec);
303 	if (!a) { LogMsg("RemoveAuthRecord: ERROR!! AuthGroup not found for %s", ARDisplayString(m, rr)); return mDNSNULL; }
304 	rp = &(*ag)->members;
305 	while (*rp)
306 		{
307 		if (*rp != rr)
308 			rp=&(*rp)->next;
309 		else
310 			{
311 			// We don't break here, so that we can set the tail below without tracking "prev" pointers
312 
313 			LogInfo("RemoveAuthRecord: removing auth record %s from table", ARDisplayString(m, rr));
314 			*rp = (*rp)->next;			// Cut record from list
315 			}
316 		}
317 	// TBD: If there are no more members, release authgroup ?
318 	(*ag)->rrauth_tail = rp;
319 	return a;
320 	}
321 
CacheGroupForName(const mDNS * const m,const mDNSu32 slot,const mDNSu32 namehash,const domainname * const name)322 mDNSexport CacheGroup *CacheGroupForName(const mDNS *const m, const mDNSu32 slot, const mDNSu32 namehash, const domainname *const name)
323 	{
324 	CacheGroup *cg;
325 	for (cg = m->rrcache_hash[slot]; cg; cg=cg->next)
326 		if (cg->namehash == namehash && SameDomainName(cg->name, name))
327 			break;
328 	return(cg);
329 	}
330 
CacheGroupForRecord(const mDNS * const m,const mDNSu32 slot,const ResourceRecord * const rr)331 mDNSlocal CacheGroup *CacheGroupForRecord(const mDNS *const m, const mDNSu32 slot, const ResourceRecord *const rr)
332 	{
333 	return(CacheGroupForName(m, slot, rr->namehash, rr->name));
334 	}
335 
mDNS_AddressIsLocalSubnet(mDNS * const m,const mDNSInterfaceID InterfaceID,const mDNSAddr * addr)336 mDNSexport mDNSBool mDNS_AddressIsLocalSubnet(mDNS *const m, const mDNSInterfaceID InterfaceID, const mDNSAddr *addr)
337 	{
338 	NetworkInterfaceInfo *intf;
339 
340 	if (addr->type == mDNSAddrType_IPv4)
341 		{
342 		// Normally we resist touching the NotAnInteger fields, but here we're doing tricky bitwise masking so we make an exception
343 		if (mDNSv4AddressIsLinkLocal(&addr->ip.v4)) return(mDNStrue);
344 		for (intf = m->HostInterfaces; intf; intf = intf->next)
345 			if (intf->ip.type == addr->type && intf->InterfaceID == InterfaceID && intf->McastTxRx)
346 				if (((intf->ip.ip.v4.NotAnInteger ^ addr->ip.v4.NotAnInteger) & intf->mask.ip.v4.NotAnInteger) == 0)
347 					return(mDNStrue);
348 		}
349 
350 	if (addr->type == mDNSAddrType_IPv6)
351 		{
352 		if (mDNSv6AddressIsLinkLocal(&addr->ip.v6)) return(mDNStrue);
353 		for (intf = m->HostInterfaces; intf; intf = intf->next)
354 			if (intf->ip.type == addr->type && intf->InterfaceID == InterfaceID && intf->McastTxRx)
355 				if ((((intf->ip.ip.v6.l[0] ^ addr->ip.v6.l[0]) & intf->mask.ip.v6.l[0]) == 0) &&
356 					(((intf->ip.ip.v6.l[1] ^ addr->ip.v6.l[1]) & intf->mask.ip.v6.l[1]) == 0) &&
357 					(((intf->ip.ip.v6.l[2] ^ addr->ip.v6.l[2]) & intf->mask.ip.v6.l[2]) == 0) &&
358 					(((intf->ip.ip.v6.l[3] ^ addr->ip.v6.l[3]) & intf->mask.ip.v6.l[3]) == 0))
359 						return(mDNStrue);
360 		}
361 
362 	return(mDNSfalse);
363 	}
364 
FirstInterfaceForID(mDNS * const m,const mDNSInterfaceID InterfaceID)365 mDNSlocal NetworkInterfaceInfo *FirstInterfaceForID(mDNS *const m, const mDNSInterfaceID InterfaceID)
366 	{
367 	NetworkInterfaceInfo *intf = m->HostInterfaces;
368 	while (intf && intf->InterfaceID != InterfaceID) intf = intf->next;
369 	return(intf);
370 	}
371 
InterfaceNameForID(mDNS * const m,const mDNSInterfaceID InterfaceID)372 mDNSexport char *InterfaceNameForID(mDNS *const m, const mDNSInterfaceID InterfaceID)
373 	{
374 	NetworkInterfaceInfo *intf = FirstInterfaceForID(m, InterfaceID);
375 	return(intf ? intf->ifname : mDNSNULL);
376 	}
377 
378 // Caller should hold the lock
GenerateNegativeResponse(mDNS * const m)379 mDNSlocal void GenerateNegativeResponse(mDNS *const m)
380 	{
381 	DNSQuestion *q;
382 	if (!m->CurrentQuestion) { LogMsg("GenerateNegativeResponse: ERROR!! CurrentQuestion not set"); return; }
383 	q = m->CurrentQuestion;
384 	LogInfo("GenerateNegativeResponse: Generating negative response for question %##s (%s)", q->qname.c, DNSTypeName(q->qtype));
385 
386 	MakeNegativeCacheRecord(m, &m->rec.r, &q->qname, q->qnamehash, q->qtype, q->qclass, 60, mDNSInterface_Any, mDNSNULL);
387 	AnswerCurrentQuestionWithResourceRecord(m, &m->rec.r, QC_addnocache);
388 	if (m->CurrentQuestion == q) { q->ThisQInterval = 0; }				// Deactivate this question
389 	// Don't touch the question after this
390 	m->rec.r.resrec.RecordType = 0;		// Clear RecordType to show we're not still using it
391 	}
392 
AnswerQuestionByFollowingCNAME(mDNS * const m,DNSQuestion * q,ResourceRecord * rr)393 mDNSlocal void AnswerQuestionByFollowingCNAME(mDNS *const m, DNSQuestion *q, ResourceRecord *rr)
394 	{
395 	const mDNSBool selfref = SameDomainName(&q->qname, &rr->rdata->u.name);
396 	if (q->CNAMEReferrals >= 10 || selfref)
397 		LogMsg("AnswerQuestionByFollowingCNAME: %p %##s (%s) NOT following CNAME referral %d%s for %s",
398 			q, q->qname.c, DNSTypeName(q->qtype), q->CNAMEReferrals, selfref ? " (Self-Referential)" : "", RRDisplayString(m, rr));
399 	else
400 		{
401 		const mDNSu32 c = q->CNAMEReferrals + 1;		// Stash a copy of the new q->CNAMEReferrals value
402 
403 		// The SameDomainName check above is to ignore bogus CNAME records that point right back at
404 		// themselves. Without that check we can get into a case where we have two duplicate questions,
405 		// A and B, and when we stop question A, UpdateQuestionDuplicates copies the value of CNAMEReferrals
406 		// from A to B, and then A is re-appended to the end of the list as a duplicate of B (because
407 		// the target name is still the same), and then when we stop question B, UpdateQuestionDuplicates
408 		// copies the B's value of CNAMEReferrals back to A, and we end up not incrementing CNAMEReferrals
409 		// for either of them. This is not a problem for CNAME loops of two or more records because in
410 		// those cases the newly re-appended question A has a different target name and therefore cannot be
411 		// a duplicate of any other question ('B') which was itself a duplicate of the previous question A.
412 
413 		// Right now we just stop and re-use the existing query. If we really wanted to be 100% perfect,
414 		// and track CNAMEs coming and going, we should really create a subordinate query here,
415 		// which we would subsequently cancel and retract if the CNAME referral record were removed.
416 		// In reality this is such a corner case we'll ignore it until someone actually needs it.
417 
418 		LogInfo("AnswerQuestionByFollowingCNAME: %p %##s (%s) following CNAME referral %d for %s",
419 			q, q->qname.c, DNSTypeName(q->qtype), q->CNAMEReferrals, RRDisplayString(m, rr));
420 
421 		mDNS_StopQuery_internal(m, q);								// Stop old query
422 		AssignDomainName(&q->qname, &rr->rdata->u.name);			// Update qname
423 		q->qnamehash = DomainNameHashValue(&q->qname);				// and namehash
424 		// If a unicast query results in a CNAME that points to a .local, we need to re-try
425 		// this as unicast. Setting the mDNSInterface_Unicast tells mDNS_StartQuery_internal
426 		// to try this as unicast query even though it is a .local name
427 		if (!mDNSOpaque16IsZero(q->TargetQID) && IsLocalDomain(&q->qname))
428 			{
429 			LogInfo("AnswerQuestionByFollowingCNAME: Resolving a .local CNAME %p %##s (%s) Record %s",
430 				q, q->qname.c, DNSTypeName(q->qtype), RRDisplayString(m, rr));
431 			q->InterfaceID = mDNSInterface_Unicast;
432 			}
433 		mDNS_StartQuery_internal(m, q);								// start new query
434 		// Record how many times we've done this. We need to do this *after* mDNS_StartQuery_internal,
435 		// because mDNS_StartQuery_internal re-initializes CNAMEReferrals to zero
436 		q->CNAMEReferrals = c;
437 		}
438 	}
439 
440 // For a single given DNSQuestion pointed to by CurrentQuestion, deliver an add/remove result for the single given AuthRecord
441 // Note: All the callers should use the m->CurrentQuestion to see if the question is still valid or not
AnswerLocalQuestionWithLocalAuthRecord(mDNS * const m,AuthRecord * rr,QC_result AddRecord)442 mDNSlocal void AnswerLocalQuestionWithLocalAuthRecord(mDNS *const m, AuthRecord *rr, QC_result AddRecord)
443 	{
444 	DNSQuestion *q = m->CurrentQuestion;
445 	mDNSBool followcname;
446 
447 	if (!q)
448 		{
449 		LogMsg("AnswerLocalQuestionWithLocalAuthRecord: ERROR!! CurrentQuestion NULL while answering with %s", ARDisplayString(m, rr));
450 		return;
451 		}
452 
453 	followcname = FollowCNAME(q, &rr->resrec, AddRecord);
454 
455 	// We should not be delivering results for record types Unregistered, Deregistering, and (unverified) Unique
456 	if (!(rr->resrec.RecordType & kDNSRecordTypeActiveMask))
457 		{
458 		LogMsg("AnswerLocalQuestionWithLocalAuthRecord: *NOT* delivering %s event for local record type %X %s",
459 			AddRecord ? "Add" : "Rmv", rr->resrec.RecordType, ARDisplayString(m, rr));
460 		return;
461 		}
462 
463 	// Indicate that we've given at least one positive answer for this record, so we should be prepared to send a goodbye for it
464 	if (AddRecord) rr->AnsweredLocalQ = mDNStrue;
465 	mDNS_DropLockBeforeCallback();		// Allow client to legally make mDNS API calls from the callback
466 	if (q->QuestionCallback && !q->NoAnswer)
467 		{
468 		q->CurrentAnswers += AddRecord ? 1 : -1;
469  		if (LORecordAnswersAddressType(rr))
470 			{
471 			if (!followcname || q->ReturnIntermed)
472 				{
473 				// Don't send this packet on the wire as we answered from /etc/hosts
474 				q->ThisQInterval = 0;
475 				q->LOAddressAnswers += AddRecord ? 1 : -1;
476 				q->QuestionCallback(m, q, &rr->resrec, AddRecord);
477 				}
478 			mDNS_ReclaimLockAfterCallback();	// Decrement mDNS_reentrancy to block mDNS API calls again
479 			// The callback above could have caused the question to stop. Detect that
480 			// using m->CurrentQuestion
481 			if (followcname && m->CurrentQuestion == q)
482 				AnswerQuestionByFollowingCNAME(m, q, &rr->resrec);
483 			return;
484 			}
485 		else
486 			q->QuestionCallback(m, q, &rr->resrec, AddRecord);
487 		}
488 	mDNS_ReclaimLockAfterCallback();	// Decrement mDNS_reentrancy to block mDNS API calls again
489 	}
490 
AnswerInterfaceAnyQuestionsWithLocalAuthRecord(mDNS * const m,AuthRecord * rr,QC_result AddRecord)491 mDNSlocal void AnswerInterfaceAnyQuestionsWithLocalAuthRecord(mDNS *const m, AuthRecord *rr, QC_result AddRecord)
492  	{
493  	if (m->CurrentQuestion)
494  		LogMsg("AnswerInterfaceAnyQuestionsWithLocalAuthRecord: ERROR m->CurrentQuestion already set: %##s (%s)",
495  			m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
496  	m->CurrentQuestion = m->Questions;
497  	while (m->CurrentQuestion && m->CurrentQuestion != m->NewQuestions)
498  		{
499 		mDNSBool answered;
500  		DNSQuestion *q = m->CurrentQuestion;
501 		if (RRAny(rr))
502 			answered = ResourceRecordAnswersQuestion(&rr->resrec, q);
503 		else
504 			answered = LocalOnlyRecordAnswersQuestion(rr, q);
505  		if (answered)
506  			AnswerLocalQuestionWithLocalAuthRecord(m, rr, AddRecord);		// MUST NOT dereference q again
507 		if (m->CurrentQuestion == q)	// If m->CurrentQuestion was not auto-advanced, do it ourselves now
508 			m->CurrentQuestion = q->next;
509  		}
510  	m->CurrentQuestion = mDNSNULL;
511  	}
512 
513 // When a new local AuthRecord is created or deleted, AnswerAllLocalQuestionsWithLocalAuthRecord()
514 // delivers the appropriate add/remove events to listening questions:
515 // 1. It runs though all our LocalOnlyQuestions delivering answers as appropriate,
516 //    stopping if it reaches a NewLocalOnlyQuestion -- brand-new questions are handled by AnswerNewLocalOnlyQuestion().
517 // 2. If the AuthRecord is marked mDNSInterface_LocalOnly or mDNSInterface_P2P, then it also runs though
518 //    our main question list, delivering answers to mDNSInterface_Any questions as appropriate,
519 //    stopping if it reaches a NewQuestion -- brand-new questions are handled by AnswerNewQuestion().
520 //
521 // AnswerAllLocalQuestionsWithLocalAuthRecord is used by the m->NewLocalRecords loop in mDNS_Execute(),
522 // and by mDNS_Deregister_internal()
523 
AnswerAllLocalQuestionsWithLocalAuthRecord(mDNS * const m,AuthRecord * rr,QC_result AddRecord)524 mDNSlocal void AnswerAllLocalQuestionsWithLocalAuthRecord(mDNS *const m, AuthRecord *rr, QC_result AddRecord)
525 	{
526 	if (m->CurrentQuestion)
527 		LogMsg("AnswerAllLocalQuestionsWithLocalAuthRecord ERROR m->CurrentQuestion already set: %##s (%s)",
528 			m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
529 
530 	m->CurrentQuestion = m->LocalOnlyQuestions;
531 	while (m->CurrentQuestion && m->CurrentQuestion != m->NewLocalOnlyQuestions)
532 		{
533 		mDNSBool answered;
534 		DNSQuestion *q = m->CurrentQuestion;
535 		// We are called with both LocalOnly/P2P record or a regular AuthRecord
536 		if (RRAny(rr))
537 			answered = ResourceRecordAnswersQuestion(&rr->resrec, q);
538 		else
539 			answered = LocalOnlyRecordAnswersQuestion(rr, q);
540 		if (answered)
541 			AnswerLocalQuestionWithLocalAuthRecord(m, rr, AddRecord);			// MUST NOT dereference q again
542 		if (m->CurrentQuestion == q)	// If m->CurrentQuestion was not auto-advanced, do it ourselves now
543 			m->CurrentQuestion = q->next;
544 		}
545 
546 	m->CurrentQuestion = mDNSNULL;
547 
548 	// If this AuthRecord is marked LocalOnly or P2P, then we want to deliver it to all local 'mDNSInterface_Any' questions
549 	if (rr->ARType == AuthRecordLocalOnly || rr->ARType == AuthRecordP2P)
550 		AnswerInterfaceAnyQuestionsWithLocalAuthRecord(m, rr, AddRecord);
551 
552 	}
553 
554 // ***************************************************************************
555 #if COMPILER_LIKES_PRAGMA_MARK
556 #pragma mark -
557 #pragma mark - Resource Record Utility Functions
558 #endif
559 
560 #define RRTypeIsAddressType(T) ((T) == kDNSType_A || (T) == kDNSType_AAAA)
561 
562 #define ResourceRecordIsValidAnswer(RR) ( ((RR)->             resrec.RecordType & kDNSRecordTypeActiveMask)  && \
563 		((RR)->Additional1 == mDNSNULL || ((RR)->Additional1->resrec.RecordType & kDNSRecordTypeActiveMask)) && \
564 		((RR)->Additional2 == mDNSNULL || ((RR)->Additional2->resrec.RecordType & kDNSRecordTypeActiveMask)) && \
565 		((RR)->DependentOn == mDNSNULL || ((RR)->DependentOn->resrec.RecordType & kDNSRecordTypeActiveMask))  )
566 
567 #define ResourceRecordIsValidInterfaceAnswer(RR, INTID) \
568 	(ResourceRecordIsValidAnswer(RR) && \
569 	((RR)->resrec.InterfaceID == mDNSInterface_Any || (RR)->resrec.InterfaceID == (INTID)))
570 
571 #define DefaultProbeCountForTypeUnique ((mDNSu8)3)
572 #define DefaultProbeCountForRecordType(X)      ((X) == kDNSRecordTypeUnique ? DefaultProbeCountForTypeUnique : (mDNSu8)0)
573 
574 #define InitialAnnounceCount ((mDNSu8)8)
575 
576 // For goodbye packets we set the count to 3, and for wakeups we set it to 18
577 // (which will be up to 15 wakeup attempts over the course of 30 seconds,
578 // and then if the machine fails to wake, 3 goodbye packets).
579 #define GoodbyeCount ((mDNSu8)3)
580 #define WakeupCount ((mDNSu8)18)
581 
582 // Number of wakeups we send if WakeOnResolve is set in the question
583 #define InitialWakeOnResolveCount ((mDNSu8)3)
584 
585 // Note that the announce intervals use exponential backoff, doubling each time. The probe intervals do not.
586 // This means that because the announce interval is doubled after sending the first packet, the first
587 // observed on-the-wire inter-packet interval between announcements is actually one second.
588 // The half-second value here may be thought of as a conceptual (non-existent) half-second delay *before* the first packet is sent.
589 #define DefaultProbeIntervalForTypeUnique (mDNSPlatformOneSecond/4)
590 #define DefaultAnnounceIntervalForTypeShared (mDNSPlatformOneSecond/2)
591 #define DefaultAnnounceIntervalForTypeUnique (mDNSPlatformOneSecond/2)
592 
593 #define DefaultAPIntervalForRecordType(X)  ((X) & kDNSRecordTypeActiveSharedMask ? DefaultAnnounceIntervalForTypeShared : \
594 											(X) & kDNSRecordTypeUnique           ? DefaultProbeIntervalForTypeUnique    : \
595 											(X) & kDNSRecordTypeActiveUniqueMask ? DefaultAnnounceIntervalForTypeUnique : 0)
596 
597 #define TimeToAnnounceThisRecord(RR,time) ((RR)->AnnounceCount && (time) - ((RR)->LastAPTime + (RR)->ThisAPInterval) >= 0)
598 #define TimeToSendThisRecord(RR,time) ((TimeToAnnounceThisRecord(RR,time) || (RR)->ImmedAnswer) && ResourceRecordIsValidAnswer(RR))
599 #define TicksTTL(RR) ((mDNSs32)(RR)->resrec.rroriginalttl * mDNSPlatformOneSecond)
600 #define RRExpireTime(RR) ((RR)->TimeRcvd + TicksTTL(RR))
601 
602 #define MaxUnansweredQueries 4
603 
604 // SameResourceRecordSignature returns true if two resources records have the same name, type, and class, and may be sent
605 // (or were received) on the same interface (i.e. if *both* records specify an interface, then it has to match).
606 // TTL and rdata may differ.
607 // This is used for cache flush management:
608 // When sending a unique record, all other records matching "SameResourceRecordSignature" must also be sent
609 // When receiving a unique record, all old cache records matching "SameResourceRecordSignature" are flushed
610 
611 // SameResourceRecordNameClassInterface is functionally the same as SameResourceRecordSignature, except rrtype does not have to match
612 
613 #define SameResourceRecordSignature(A,B) (A)->resrec.rrtype == (B)->resrec.rrtype && SameResourceRecordNameClassInterface((A),(B))
614 
SameResourceRecordNameClassInterface(const AuthRecord * const r1,const AuthRecord * const r2)615 mDNSlocal mDNSBool SameResourceRecordNameClassInterface(const AuthRecord *const r1, const AuthRecord *const r2)
616 	{
617 	if (!r1) { LogMsg("SameResourceRecordSignature ERROR: r1 is NULL"); return(mDNSfalse); }
618 	if (!r2) { LogMsg("SameResourceRecordSignature ERROR: r2 is NULL"); return(mDNSfalse); }
619 	if (r1->resrec.InterfaceID &&
620 		r2->resrec.InterfaceID &&
621 		r1->resrec.InterfaceID != r2->resrec.InterfaceID) return(mDNSfalse);
622 	return(mDNSBool)(
623 		r1->resrec.rrclass  == r2->resrec.rrclass &&
624 		r1->resrec.namehash == r2->resrec.namehash &&
625 		SameDomainName(r1->resrec.name, r2->resrec.name));
626 	}
627 
628 // PacketRRMatchesSignature behaves as SameResourceRecordSignature, except that types may differ if our
629 // authoratative record is unique (as opposed to shared). For unique records, we are supposed to have
630 // complete ownership of *all* types for this name, so *any* record type with the same name is a conflict.
631 // In addition, when probing we send our questions with the wildcard type kDNSQType_ANY,
632 // so a response of any type should match, even if it is not actually the type the client plans to use.
633 
634 // For now, to make it easier to avoid false conflicts, we treat SPS Proxy records like shared records,
635 // and require the rrtypes to match for the rdata to be considered potentially conflicting
PacketRRMatchesSignature(const CacheRecord * const pktrr,const AuthRecord * const authrr)636 mDNSlocal mDNSBool PacketRRMatchesSignature(const CacheRecord *const pktrr, const AuthRecord *const authrr)
637 	{
638 	if (!pktrr)  { LogMsg("PacketRRMatchesSignature ERROR: pktrr is NULL"); return(mDNSfalse); }
639 	if (!authrr) { LogMsg("PacketRRMatchesSignature ERROR: authrr is NULL"); return(mDNSfalse); }
640 	if (pktrr->resrec.InterfaceID &&
641 		authrr->resrec.InterfaceID &&
642 		pktrr->resrec.InterfaceID != authrr->resrec.InterfaceID) return(mDNSfalse);
643 	if (!(authrr->resrec.RecordType & kDNSRecordTypeUniqueMask) || authrr->WakeUp.HMAC.l[0])
644 		if (pktrr->resrec.rrtype != authrr->resrec.rrtype) return(mDNSfalse);
645 	return(mDNSBool)(
646 		pktrr->resrec.rrclass == authrr->resrec.rrclass &&
647 		pktrr->resrec.namehash == authrr->resrec.namehash &&
648 		SameDomainName(pktrr->resrec.name, authrr->resrec.name));
649 	}
650 
651 // CacheRecord *ka is the CacheRecord from the known answer list in the query.
652 // This is the information that the requester believes to be correct.
653 // AuthRecord *rr is the answer we are proposing to give, if not suppressed.
654 // This is the information that we believe to be correct.
655 // We've already determined that we plan to give this answer on this interface
656 // (either the record is non-specific, or it is specific to this interface)
657 // so now we just need to check the name, type, class, rdata and TTL.
ShouldSuppressKnownAnswer(const CacheRecord * const ka,const AuthRecord * const rr)658 mDNSlocal mDNSBool ShouldSuppressKnownAnswer(const CacheRecord *const ka, const AuthRecord *const rr)
659 	{
660 	// If RR signature is different, or data is different, then don't suppress our answer
661 	if (!IdenticalResourceRecord(&ka->resrec, &rr->resrec)) return(mDNSfalse);
662 
663 	// If the requester's indicated TTL is less than half the real TTL,
664 	// we need to give our answer before the requester's copy expires.
665 	// If the requester's indicated TTL is at least half the real TTL,
666 	// then we can suppress our answer this time.
667 	// If the requester's indicated TTL is greater than the TTL we believe,
668 	// then that's okay, and we don't need to do anything about it.
669 	// (If two responders on the network are offering the same information,
670 	// that's okay, and if they are offering the information with different TTLs,
671 	// the one offering the lower TTL should defer to the one offering the higher TTL.)
672 	return(mDNSBool)(ka->resrec.rroriginalttl >= rr->resrec.rroriginalttl / 2);
673 	}
674 
SetNextAnnounceProbeTime(mDNS * const m,const AuthRecord * const rr)675 mDNSlocal void SetNextAnnounceProbeTime(mDNS *const m, const AuthRecord *const rr)
676 	{
677 	if (rr->resrec.RecordType == kDNSRecordTypeUnique)
678 		{
679 		if ((rr->LastAPTime + rr->ThisAPInterval) - m->timenow > mDNSPlatformOneSecond * 10)
680 			{
681 			LogMsg("SetNextAnnounceProbeTime: ProbeCount %d Next in %d %s", rr->ProbeCount, (rr->LastAPTime + rr->ThisAPInterval) - m->timenow, ARDisplayString(m, rr));
682 			LogMsg("SetNextAnnounceProbeTime: m->SuppressProbes %d m->timenow %d diff %d", m->SuppressProbes, m->timenow, m->SuppressProbes - m->timenow);
683 			}
684 		if (m->NextScheduledProbe - (rr->LastAPTime + rr->ThisAPInterval) >= 0)
685 			m->NextScheduledProbe = (rr->LastAPTime + rr->ThisAPInterval);
686 		// Some defensive code:
687 		// If (rr->LastAPTime + rr->ThisAPInterval) happens to be far in the past, we don't want to allow
688 		// NextScheduledProbe to be set excessively in the past, because that can cause bad things to happen.
689 		// See: <rdar://problem/7795434> mDNS: Sometimes advertising stops working and record interval is set to zero
690 		if (m->NextScheduledProbe - m->timenow < 0)
691 			m->NextScheduledProbe = m->timenow;
692 		}
693 	else if (rr->AnnounceCount && (ResourceRecordIsValidAnswer(rr) || rr->resrec.RecordType == kDNSRecordTypeDeregistering))
694 		{
695 		if (m->NextScheduledResponse - (rr->LastAPTime + rr->ThisAPInterval) >= 0)
696 			m->NextScheduledResponse = (rr->LastAPTime + rr->ThisAPInterval);
697 		}
698 	}
699 
InitializeLastAPTime(mDNS * const m,AuthRecord * const rr)700 mDNSlocal void InitializeLastAPTime(mDNS *const m, AuthRecord *const rr)
701 	{
702 	// For reverse-mapping Sleep Proxy PTR records, probe interval is one second
703 	rr->ThisAPInterval = rr->AddressProxy.type ? mDNSPlatformOneSecond : DefaultAPIntervalForRecordType(rr->resrec.RecordType);
704 
705 	// * If this is a record type that's going to probe, then we use the m->SuppressProbes time.
706 	// * Otherwise, if it's not going to probe, but m->SuppressProbes is set because we have other
707 	//   records that are going to probe, then we delay its first announcement so that it will
708 	//   go out synchronized with the first announcement for the other records that *are* probing.
709 	//   This is a minor performance tweak that helps keep groups of related records synchronized together.
710 	//   The addition of "interval / 2" is to make sure that, in the event that any of the probes are
711 	//   delayed by a few milliseconds, this announcement does not inadvertently go out *before* the probing is complete.
712 	//   When the probing is complete and those records begin to announce, these records will also be picked up and accelerated,
713 	//   because they will meet the criterion of being at least half-way to their scheduled announcement time.
714 	// * If it's not going to probe and m->SuppressProbes is not already set then we should announce immediately.
715 
716 	if (rr->ProbeCount)
717 		{
718 		// If we have no probe suppression time set, or it is in the past, set it now
719 		if (m->SuppressProbes == 0 || m->SuppressProbes - m->timenow < 0)
720 			{
721 			// To allow us to aggregate probes when a group of services are registered together,
722 			// the first probe is delayed 1/4 second. This means the common-case behaviour is:
723 			// 1/4 second wait; probe
724 			// 1/4 second wait; probe
725 			// 1/4 second wait; probe
726 			// 1/4 second wait; announce (i.e. service is normally announced exactly one second after being registered)
727 			m->SuppressProbes = NonZeroTime(m->timenow + DefaultProbeIntervalForTypeUnique/2 + mDNSRandom(DefaultProbeIntervalForTypeUnique/2));
728 
729 			// If we already have a *probe* scheduled to go out sooner, then use that time to get better aggregation
730 			if (m->SuppressProbes - m->NextScheduledProbe >= 0)
731 				m->SuppressProbes = NonZeroTime(m->NextScheduledProbe);
732 			if (m->SuppressProbes - m->timenow < 0)		// Make sure we don't set m->SuppressProbes excessively in the past
733 				m->SuppressProbes = m->timenow;
734 
735 			// If we already have a *query* scheduled to go out sooner, then use that time to get better aggregation
736 			if (m->SuppressProbes - m->NextScheduledQuery >= 0)
737 				m->SuppressProbes = NonZeroTime(m->NextScheduledQuery);
738 			if (m->SuppressProbes - m->timenow < 0)		// Make sure we don't set m->SuppressProbes excessively in the past
739 				m->SuppressProbes = m->timenow;
740 
741 			// except... don't expect to be able to send before the m->SuppressSending timer fires
742 			if (m->SuppressSending && m->SuppressProbes - m->SuppressSending < 0)
743 				m->SuppressProbes = NonZeroTime(m->SuppressSending);
744 
745 			if (m->SuppressProbes - m->timenow > mDNSPlatformOneSecond * 8)
746 				{
747 				LogMsg("InitializeLastAPTime ERROR m->SuppressProbes %d m->NextScheduledProbe %d m->NextScheduledQuery %d m->SuppressSending %d %d",
748 					m->SuppressProbes     - m->timenow,
749 					m->NextScheduledProbe - m->timenow,
750 					m->NextScheduledQuery - m->timenow,
751 					m->SuppressSending,
752 					m->SuppressSending    - m->timenow);
753 				m->SuppressProbes = NonZeroTime(m->timenow + DefaultProbeIntervalForTypeUnique/2 + mDNSRandom(DefaultProbeIntervalForTypeUnique/2));
754 				}
755 			}
756 		rr->LastAPTime = m->SuppressProbes - rr->ThisAPInterval;
757 		}
758 	else if (m->SuppressProbes && m->SuppressProbes - m->timenow >= 0)
759 		rr->LastAPTime = m->SuppressProbes - rr->ThisAPInterval + DefaultProbeIntervalForTypeUnique * DefaultProbeCountForTypeUnique + rr->ThisAPInterval / 2;
760 	else
761 		rr->LastAPTime = m->timenow - rr->ThisAPInterval;
762 
763 	// For reverse-mapping Sleep Proxy PTR records we don't want to start probing instantly -- we
764 	// wait one second to give the client a chance to go to sleep, and then start our ARP/NDP probing.
765 	// After three probes one second apart with no answer, we conclude the client is now sleeping
766 	// and we can begin broadcasting our announcements to take over ownership of that IP address.
767 	// If we don't wait for the client to go to sleep, then when the client sees our ARP Announcements there's a risk
768 	// (depending on the OS and networking stack it's using) that it might interpret it as a conflict and change its IP address.
769 	if (rr->AddressProxy.type) rr->LastAPTime = m->timenow;
770 
771 	// Unsolicited Neighbor Advertisements (RFC 2461 Section 7.2.6) give us fast address cache updating,
772 	// but some older IPv6 clients get confused by them, so for now we don't send them. Without Unsolicited
773 	// Neighbor Advertisements we have to rely on Neighbor Unreachability Detection instead, which is slower.
774 	// Given this, we'll do our best to wake for existing IPv6 connections, but we don't want to encourage
775 	// new ones for sleeping clients, so we'll we send deletions for our SPS clients' AAAA records.
776 	if (m->KnownBugs & mDNS_KnownBug_LimitedIPv6)
777 		if (rr->WakeUp.HMAC.l[0] && rr->resrec.rrtype == kDNSType_AAAA)
778 			rr->LastAPTime = m->timenow - rr->ThisAPInterval + mDNSPlatformOneSecond * 10;
779 
780 	// Set LastMCTime to now, to inhibit multicast responses
781 	// (no need to send additional multicast responses when we're announcing anyway)
782 	rr->LastMCTime      = m->timenow;
783 	rr->LastMCInterface = mDNSInterfaceMark;
784 
785 	SetNextAnnounceProbeTime(m, rr);
786 	}
787 
SetUnicastTargetToHostName(mDNS * const m,AuthRecord * rr)788 mDNSlocal const domainname *SetUnicastTargetToHostName(mDNS *const m, AuthRecord *rr)
789 	{
790 	const domainname *target;
791 	if (rr->AutoTarget)
792 		{
793 		// For autotunnel services pointing at our IPv6 ULA we don't need or want a NAT mapping, but for all other
794 		// advertised services referencing our uDNS hostname, we want NAT mappings automatically created as appropriate,
795 		// with the port number in our advertised SRV record automatically tracking the external mapped port.
796 		DomainAuthInfo *AuthInfo = GetAuthInfoForName_internal(m, rr->resrec.name);
797 		if (!AuthInfo || !AuthInfo->AutoTunnel) rr->AutoTarget = Target_AutoHostAndNATMAP;
798 		}
799 
800 	target = GetServiceTarget(m, rr);
801 	if (!target || target->c[0] == 0)
802 		{
803 		// defer registration until we've got a target
804 		LogInfo("SetUnicastTargetToHostName No target for %s", ARDisplayString(m, rr));
805 		rr->state = regState_NoTarget;
806 		return mDNSNULL;
807 		}
808 	else
809 		{
810 		LogInfo("SetUnicastTargetToHostName target %##s for resource record %s", target->c, ARDisplayString(m,rr));
811 		return target;
812 		}
813 	}
814 
815 // Right now this only applies to mDNS (.local) services where the target host is always m->MulticastHostname
816 // Eventually we should unify this with GetServiceTarget() in uDNS.c
SetTargetToHostName(mDNS * const m,AuthRecord * const rr)817 mDNSlocal void SetTargetToHostName(mDNS *const m, AuthRecord *const rr)
818 	{
819 	domainname *const target = GetRRDomainNameTarget(&rr->resrec);
820 	const domainname *newname = &m->MulticastHostname;
821 
822 	if (!target) LogInfo("SetTargetToHostName: Don't know how to set the target of rrtype %s", DNSTypeName(rr->resrec.rrtype));
823 
824 	if (!(rr->ForceMCast || rr->ARType == AuthRecordLocalOnly || rr->ARType == AuthRecordP2P || IsLocalDomain(&rr->namestorage)))
825 		{
826 		const domainname *const n = SetUnicastTargetToHostName(m, rr);
827 		if (n) newname = n;
828 		else { target->c[0] = 0; SetNewRData(&rr->resrec, mDNSNULL, 0); return; }
829 		}
830 
831 	if (target && SameDomainName(target, newname))
832 		debugf("SetTargetToHostName: Target of %##s is already %##s", rr->resrec.name->c, target->c);
833 
834 	if (target && !SameDomainName(target, newname))
835 		{
836 		AssignDomainName(target, newname);
837 		SetNewRData(&rr->resrec, mDNSNULL, 0);		// Update rdlength, rdestimate, rdatahash
838 
839 		// If we're in the middle of probing this record, we need to start again,
840 		// because changing its rdata may change the outcome of the tie-breaker.
841 		// (If the record type is kDNSRecordTypeUnique (unconfirmed unique) then DefaultProbeCountForRecordType is non-zero.)
842 		rr->ProbeCount     = DefaultProbeCountForRecordType(rr->resrec.RecordType);
843 
844 		// If we've announced this record, we really should send a goodbye packet for the old rdata before
845 		// changing to the new rdata. However, in practice, we only do SetTargetToHostName for unique records,
846 		// so when we announce them we'll set the kDNSClass_UniqueRRSet and clear any stale data that way.
847 		if (rr->RequireGoodbye && rr->resrec.RecordType == kDNSRecordTypeShared)
848 			debugf("Have announced shared record %##s (%s) at least once: should have sent a goodbye packet before updating",
849 				rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype));
850 
851 		rr->AnnounceCount  = InitialAnnounceCount;
852 		rr->RequireGoodbye = mDNSfalse;
853 		InitializeLastAPTime(m, rr);
854 		}
855 	}
856 
AcknowledgeRecord(mDNS * const m,AuthRecord * const rr)857 mDNSlocal void AcknowledgeRecord(mDNS *const m, AuthRecord *const rr)
858 	{
859 	if (rr->RecordCallback)
860 		{
861 		// CAUTION: MUST NOT do anything more with rr after calling rr->Callback(), because the client's callback function
862 		// is allowed to do anything, including starting/stopping queries, registering/deregistering records, etc.
863 		rr->Acknowledged = mDNStrue;
864 		mDNS_DropLockBeforeCallback();		// Allow client to legally make mDNS API calls from the callback
865 		rr->RecordCallback(m, rr, mStatus_NoError);
866 		mDNS_ReclaimLockAfterCallback();	// Decrement mDNS_reentrancy to block mDNS API calls again
867 		}
868 	}
869 
ActivateUnicastRegistration(mDNS * const m,AuthRecord * const rr)870 mDNSexport void ActivateUnicastRegistration(mDNS *const m, AuthRecord *const rr)
871 	{
872 	// Make sure that we don't activate the SRV record and associated service records, if it is in
873 	// NoTarget state. First time when a service is being instantiated, SRV record may be in NoTarget state.
874 	// We should not activate any of the other reords (PTR, TXT) that are part of the service. When
875 	// the target becomes available, the records will be reregistered.
876 	if (rr->resrec.rrtype != kDNSType_SRV)
877 		{
878 		AuthRecord *srvRR = mDNSNULL;
879 		if (rr->resrec.rrtype == kDNSType_PTR)
880 			srvRR = rr->Additional1;
881 		else if (rr->resrec.rrtype == kDNSType_TXT)
882 			srvRR = rr->DependentOn;
883 		if (srvRR)
884 			{
885 			if (srvRR->resrec.rrtype != kDNSType_SRV)
886 				{
887 				LogMsg("ActivateUnicastRegistration: ERROR!! Resource record %s wrong, expecting SRV type", ARDisplayString(m, srvRR));
888 				}
889 			else
890 				{
891 				LogInfo("ActivateUnicastRegistration: Found Service Record %s in state %d for %##s (%s)",
892 					ARDisplayString(m, srvRR), srvRR->state, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype));
893 				rr->state = srvRR->state;
894 				}
895 			}
896 		}
897 
898 	if (rr->state == regState_NoTarget)
899 		{
900 		LogInfo("ActivateUnicastRegistration record %s in regState_NoTarget, not activating", ARDisplayString(m, rr));
901 		return;
902 		}
903 	// When we wake up from sleep, we call ActivateUnicastRegistration. It is possible that just before we went to sleep,
904 	// the service/record was being deregistered. In that case, we should not try to register again. For the cases where
905 	// the records are deregistered due to e.g., no target for the SRV record, we would have returned from above if it
906 	// was already in NoTarget state. If it was in the process of deregistration but did not complete fully before we went
907 	// to sleep, then it is okay to start in Pending state as we will go back to NoTarget state if we don't have a target.
908 	if (rr->resrec.RecordType == kDNSRecordTypeDeregistering)
909 		{
910 		LogInfo("ActivateUnicastRegistration: Resource record %s, current state %d, moving to DeregPending", ARDisplayString(m, rr), rr->state);
911 		rr->state = regState_DeregPending;
912 		}
913 	else
914 		{
915 		LogInfo("ActivateUnicastRegistration: Resource record %s, current state %d, moving to Pending", ARDisplayString(m, rr), rr->state);
916 		rr->state = regState_Pending;
917 		}
918 	rr->ProbeCount     = 0;
919 	rr->AnnounceCount  = 0;
920 	rr->ThisAPInterval = INIT_RECORD_REG_INTERVAL;
921 	rr->LastAPTime     = m->timenow - rr->ThisAPInterval;
922 	rr->expire         = 0;	// Forget about all the leases, start fresh
923 	rr->uselease       = mDNStrue;
924 	rr->updateid       = zeroID;
925 	rr->SRVChanged     = mDNSfalse;
926 	rr->updateError    = mStatus_NoError;
927 	// RestartRecordGetZoneData calls this function whenever a new interface gets registered with core.
928 	// The records might already be registered with the server and hence could have NAT state.
929 	if (rr->NATinfo.clientContext)
930 		{
931 		mDNS_StopNATOperation_internal(m, &rr->NATinfo);
932 		rr->NATinfo.clientContext = mDNSNULL;
933 		}
934 	if (rr->nta) { CancelGetZoneData(m, rr->nta); rr->nta = mDNSNULL; }
935 	if (rr->tcp) { DisposeTCPConn(rr->tcp);       rr->tcp = mDNSNULL; }
936 	if (m->NextuDNSEvent - (rr->LastAPTime + rr->ThisAPInterval) >= 0)
937 		m->NextuDNSEvent = (rr->LastAPTime + rr->ThisAPInterval);
938 	}
939 
940 // Two records qualify to be local duplicates if:
941 // (a) the RecordTypes are the same, or
942 // (b) one is Unique and the other Verified
943 // (c) either is in the process of deregistering
944 #define RecordLDT(A,B) ((A)->resrec.RecordType == (B)->resrec.RecordType || \
945 	((A)->resrec.RecordType | (B)->resrec.RecordType) == (kDNSRecordTypeUnique | kDNSRecordTypeVerified) || \
946 	((A)->resrec.RecordType == kDNSRecordTypeDeregistering || (B)->resrec.RecordType == kDNSRecordTypeDeregistering))
947 
948 #define RecordIsLocalDuplicate(A,B) \
949 	((A)->resrec.InterfaceID == (B)->resrec.InterfaceID && RecordLDT((A),(B)) && IdenticalResourceRecord(&(A)->resrec, &(B)->resrec))
950 
CheckAuthIdenticalRecord(AuthHash * r,AuthRecord * rr)951 mDNSlocal AuthRecord *CheckAuthIdenticalRecord(AuthHash *r, AuthRecord *rr)
952 	{
953 	AuthGroup *a;
954 	AuthGroup **ag = &a;
955 	AuthRecord **rp;
956 	const mDNSu32 slot = AuthHashSlot(rr->resrec.name);
957 
958 	a = AuthGroupForRecord(r, slot, &rr->resrec);
959 	if (!a) return mDNSNULL;
960 	rp = &(*ag)->members;
961 	while (*rp)
962 		{
963 		if (!RecordIsLocalDuplicate(*rp, rr))
964 			rp=&(*rp)->next;
965 		else
966 			{
967 			if ((*rp)->resrec.RecordType == kDNSRecordTypeDeregistering)
968 				{
969 				(*rp)->AnnounceCount = 0;
970 				rp=&(*rp)->next;
971 				}
972 			else return *rp;
973 			}
974 		}
975 	return (mDNSNULL);
976 	}
977 
CheckAuthRecordConflict(AuthHash * r,AuthRecord * rr)978 mDNSlocal mDNSBool CheckAuthRecordConflict(AuthHash *r, AuthRecord *rr)
979 	{
980 	AuthGroup *a;
981 	AuthGroup **ag = &a;
982 	AuthRecord **rp;
983 	const mDNSu32 slot = AuthHashSlot(rr->resrec.name);
984 
985 	a = AuthGroupForRecord(r, slot, &rr->resrec);
986 	if (!a) return mDNSfalse;
987 	rp = &(*ag)->members;
988 	while (*rp)
989 		{
990 		const AuthRecord *s1 = rr->RRSet ? rr->RRSet : rr;
991 		const AuthRecord *s2 = (*rp)->RRSet ? (*rp)->RRSet : *rp;
992 		if (s1 != s2 && SameResourceRecordSignature((*rp), rr) && !IdenticalSameNameRecord(&(*rp)->resrec, &rr->resrec))
993 			return mDNStrue;
994 		else
995 			rp=&(*rp)->next;
996 		}
997 	return (mDNSfalse);
998 	}
999 
1000 // checks to see if "rr" is already present
CheckAuthSameRecord(AuthHash * r,AuthRecord * rr)1001 mDNSlocal AuthRecord *CheckAuthSameRecord(AuthHash *r, AuthRecord *rr)
1002 	{
1003 	AuthGroup *a;
1004 	AuthGroup **ag = &a;
1005 	AuthRecord **rp;
1006 	const mDNSu32 slot = AuthHashSlot(rr->resrec.name);
1007 
1008 	a = AuthGroupForRecord(r, slot, &rr->resrec);
1009 	if (!a) return mDNSNULL;
1010 	rp = &(*ag)->members;
1011 	while (*rp)
1012 		{
1013 		if (*rp != rr)
1014 			rp=&(*rp)->next;
1015 		else
1016 			{
1017 			return *rp;
1018 			}
1019 		}
1020 	return (mDNSNULL);
1021 	}
1022 
1023 // Exported so uDNS.c can call this
mDNS_Register_internal(mDNS * const m,AuthRecord * const rr)1024 mDNSexport mStatus mDNS_Register_internal(mDNS *const m, AuthRecord *const rr)
1025 	{
1026 	domainname *target = GetRRDomainNameTarget(&rr->resrec);
1027 	AuthRecord *r;
1028 	AuthRecord **p = &m->ResourceRecords;
1029 	AuthRecord **d = &m->DuplicateRecords;
1030 
1031 	if ((mDNSs32)rr->resrec.rroriginalttl <= 0)
1032 		{ LogMsg("mDNS_Register_internal: TTL %X should be 1 - 0x7FFFFFFF %s", rr->resrec.rroriginalttl, ARDisplayString(m, rr)); return(mStatus_BadParamErr); }
1033 
1034 	if (!rr->resrec.RecordType)
1035 		{ LogMsg("mDNS_Register_internal: RecordType must be non-zero %s", ARDisplayString(m, rr)); return(mStatus_BadParamErr); }
1036 
1037 	if (m->ShutdownTime)
1038 		{ LogMsg("mDNS_Register_internal: Shutting down, can't register %s", ARDisplayString(m, rr)); return(mStatus_ServiceNotRunning); }
1039 
1040 	if (m->DivertMulticastAdvertisements && !AuthRecord_uDNS(rr))
1041 		{
1042 		mDNSInterfaceID previousID = rr->resrec.InterfaceID;
1043 		if (rr->resrec.InterfaceID == mDNSInterface_Any || rr->resrec.InterfaceID == mDNSInterface_P2P)
1044 			{
1045 			rr->resrec.InterfaceID = mDNSInterface_LocalOnly;
1046 			rr->ARType = AuthRecordLocalOnly;
1047 			}
1048 		if (rr->resrec.InterfaceID != mDNSInterface_LocalOnly)
1049 			{
1050 			NetworkInterfaceInfo *intf = FirstInterfaceForID(m, rr->resrec.InterfaceID);
1051 			if (intf && !intf->Advertise){ rr->resrec.InterfaceID = mDNSInterface_LocalOnly; rr->ARType = AuthRecordLocalOnly; }
1052 			}
1053 		if (rr->resrec.InterfaceID != previousID)
1054 			LogInfo("mDNS_Register_internal: Diverting record to local-only %s", ARDisplayString(m, rr));
1055 		}
1056 
1057 	if (RRLocalOnly(rr))
1058 		{
1059 		if (CheckAuthSameRecord(&m->rrauth, rr))
1060 			{
1061 			LogMsg("mDNS_Register_internal: ERROR!! Tried to register LocalOnly AuthRecord %p %##s (%s) that's already in the list",
1062 				rr, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype));
1063 			return(mStatus_AlreadyRegistered);
1064 			}
1065 		}
1066 	else
1067 		{
1068 		while (*p && *p != rr) p=&(*p)->next;
1069 		if (*p)
1070 			{
1071 			LogMsg("mDNS_Register_internal: ERROR!! Tried to register AuthRecord %p %##s (%s) that's already in the list",
1072 				rr, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype));
1073 			return(mStatus_AlreadyRegistered);
1074 			}
1075 		}
1076 
1077 	while (*d && *d != rr) d=&(*d)->next;
1078 	if (*d)
1079 		{
1080 		LogMsg("mDNS_Register_internal: ERROR!! Tried to register AuthRecord %p %##s (%s) that's already in the Duplicate list",
1081 				rr, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype));
1082 		return(mStatus_AlreadyRegistered);
1083 		}
1084 
1085 	if (rr->DependentOn)
1086 		{
1087 		if (rr->resrec.RecordType == kDNSRecordTypeUnique)
1088 			rr->resrec.RecordType =  kDNSRecordTypeVerified;
1089 		else
1090 			{
1091 			LogMsg("mDNS_Register_internal: ERROR! %##s (%s): rr->DependentOn && RecordType != kDNSRecordTypeUnique",
1092 				rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype));
1093 			return(mStatus_Invalid);
1094 			}
1095 		if (!(rr->DependentOn->resrec.RecordType & (kDNSRecordTypeUnique | kDNSRecordTypeVerified | kDNSRecordTypeKnownUnique)))
1096 			{
1097 			LogMsg("mDNS_Register_internal: ERROR! %##s (%s): rr->DependentOn->RecordType bad type %X",
1098 				rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype), rr->DependentOn->resrec.RecordType);
1099 			return(mStatus_Invalid);
1100 			}
1101 		}
1102 
1103 	// If this resource record is referencing a specific interface, make sure it exists.
1104 	// Skip checks for LocalOnly and P2P as they are not valid InterfaceIDs. Also, for scoped
1105 	// entries in /etc/hosts skip that check as that interface may not be valid at this time.
1106 	if (rr->resrec.InterfaceID && rr->ARType != AuthRecordLocalOnly && rr->ARType != AuthRecordP2P)
1107 		{
1108 		NetworkInterfaceInfo *intf = FirstInterfaceForID(m, rr->resrec.InterfaceID);
1109 		if (!intf)
1110 			{
1111 			debugf("mDNS_Register_internal: Bogus InterfaceID %p in resource record", rr->resrec.InterfaceID);
1112 			return(mStatus_BadReferenceErr);
1113 			}
1114 		}
1115 
1116 	rr->next = mDNSNULL;
1117 
1118 	// Field Group 1: The actual information pertaining to this resource record
1119 	// Set up by client prior to call
1120 
1121 	// Field Group 2: Persistent metadata for Authoritative Records
1122 //	rr->Additional1       = set to mDNSNULL  in mDNS_SetupResourceRecord; may be overridden by client
1123 //	rr->Additional2       = set to mDNSNULL  in mDNS_SetupResourceRecord; may be overridden by client
1124 //	rr->DependentOn       = set to mDNSNULL  in mDNS_SetupResourceRecord; may be overridden by client
1125 //	rr->RRSet             = set to mDNSNULL  in mDNS_SetupResourceRecord; may be overridden by client
1126 //	rr->Callback          = already set      in mDNS_SetupResourceRecord
1127 //	rr->Context           = already set      in mDNS_SetupResourceRecord
1128 //	rr->RecordType        = already set      in mDNS_SetupResourceRecord
1129 //	rr->HostTarget        = set to mDNSfalse in mDNS_SetupResourceRecord; may be overridden by client
1130 //	rr->AllowRemoteQuery  = set to mDNSfalse in mDNS_SetupResourceRecord; may be overridden by client
1131 	// Make sure target is not uninitialized data, or we may crash writing debugging log messages
1132 	if (rr->AutoTarget && target) target->c[0] = 0;
1133 
1134 	// Field Group 3: Transient state for Authoritative Records
1135 	rr->Acknowledged      = mDNSfalse;
1136 	rr->ProbeCount        = DefaultProbeCountForRecordType(rr->resrec.RecordType);
1137 	rr->AnnounceCount     = InitialAnnounceCount;
1138 	rr->RequireGoodbye    = mDNSfalse;
1139 	rr->AnsweredLocalQ    = mDNSfalse;
1140 	rr->IncludeInProbe    = mDNSfalse;
1141 	rr->ImmedUnicast      = mDNSfalse;
1142 	rr->SendNSECNow       = mDNSNULL;
1143 	rr->ImmedAnswer       = mDNSNULL;
1144 	rr->ImmedAdditional   = mDNSNULL;
1145 	rr->SendRNow          = mDNSNULL;
1146 	rr->v4Requester       = zerov4Addr;
1147 	rr->v6Requester       = zerov6Addr;
1148 	rr->NextResponse      = mDNSNULL;
1149 	rr->NR_AnswerTo       = mDNSNULL;
1150 	rr->NR_AdditionalTo   = mDNSNULL;
1151 	if (!rr->AutoTarget) InitializeLastAPTime(m, rr);
1152 //	rr->LastAPTime        = Set for us in InitializeLastAPTime()
1153 //	rr->LastMCTime        = Set for us in InitializeLastAPTime()
1154 //	rr->LastMCInterface   = Set for us in InitializeLastAPTime()
1155 	rr->NewRData          = mDNSNULL;
1156 	rr->newrdlength       = 0;
1157 	rr->UpdateCallback    = mDNSNULL;
1158 	rr->UpdateCredits     = kMaxUpdateCredits;
1159 	rr->NextUpdateCredit  = 0;
1160 	rr->UpdateBlocked     = 0;
1161 
1162 	// For records we're holding as proxy (except reverse-mapping PTR records) two announcements is sufficient
1163 	if (rr->WakeUp.HMAC.l[0] && !rr->AddressProxy.type) rr->AnnounceCount = 2;
1164 
1165 	// Field Group 4: Transient uDNS state for Authoritative Records
1166 	rr->state             = regState_Zero;
1167 	rr->uselease          = 0;
1168 	rr->expire            = 0;
1169 	rr->Private           = 0;
1170 	rr->updateid          = zeroID;
1171 	rr->zone              = rr->resrec.name;
1172 	rr->nta               = mDNSNULL;
1173 	rr->tcp               = mDNSNULL;
1174 	rr->OrigRData         = 0;
1175 	rr->OrigRDLen         = 0;
1176 	rr->InFlightRData     = 0;
1177 	rr->InFlightRDLen     = 0;
1178 	rr->QueuedRData       = 0;
1179 	rr->QueuedRDLen       = 0;
1180 	//mDNSPlatformMemZero(&rr->NATinfo, sizeof(rr->NATinfo));
1181 	// We should be recording the actual internal port for this service record here. Once we initiate our NAT mapping
1182 	// request we'll subsequently overwrite srv.port with the allocated external NAT port -- potentially multiple
1183 	// times with different values if the external NAT port changes during the lifetime of the service registration.
1184 	//if (rr->resrec.rrtype == kDNSType_SRV) rr->NATinfo.IntPort = rr->resrec.rdata->u.srv.port;
1185 
1186 //	rr->resrec.interface         = already set in mDNS_SetupResourceRecord
1187 //	rr->resrec.name->c           = MUST be set by client
1188 //	rr->resrec.rrtype            = already set in mDNS_SetupResourceRecord
1189 //	rr->resrec.rrclass           = already set in mDNS_SetupResourceRecord
1190 //	rr->resrec.rroriginalttl     = already set in mDNS_SetupResourceRecord
1191 //	rr->resrec.rdata             = MUST be set by client, unless record type is CNAME or PTR and rr->HostTarget is set
1192 
1193 	// BIND named (name daemon) doesn't allow TXT records with zero-length rdata. This is strictly speaking correct,
1194 	// since RFC 1035 specifies a TXT record as "One or more <character-string>s", not "Zero or more <character-string>s".
1195 	// Since some legacy apps try to create zero-length TXT records, we'll silently correct it here.
1196 	if (rr->resrec.rrtype == kDNSType_TXT && rr->resrec.rdlength == 0) { rr->resrec.rdlength = 1; rr->resrec.rdata->u.txt.c[0] = 0; }
1197 
1198 	if (rr->AutoTarget)
1199 		{
1200 		SetTargetToHostName(m, rr);	// Also sets rdlength and rdestimate for us, and calls InitializeLastAPTime();
1201 #ifndef UNICAST_DISABLED
1202 		// If we have no target record yet, SetTargetToHostName will set rr->state == regState_NoTarget
1203 		// In this case we leave the record half-formed in the list, and later we'll remove it from the list and re-add it properly.
1204 		if (rr->state == regState_NoTarget)
1205 			{
1206 			// Initialize the target so that we don't crash while logging etc.
1207 			domainname *tar = GetRRDomainNameTarget(&rr->resrec);
1208 			if (tar) tar->c[0] = 0;
1209 			LogInfo("mDNS_Register_internal: record %s in NoTarget state", ARDisplayString(m, rr));
1210 			}
1211 #endif
1212 		}
1213 	else
1214 		{
1215 		rr->resrec.rdlength   = GetRDLength(&rr->resrec, mDNSfalse);
1216 		rr->resrec.rdestimate = GetRDLength(&rr->resrec, mDNStrue);
1217 		}
1218 
1219 	if (!ValidateDomainName(rr->resrec.name))
1220 		{ LogMsg("Attempt to register record with invalid name: %s", ARDisplayString(m, rr)); return(mStatus_Invalid); }
1221 
1222 	// Don't do this until *after* we've set rr->resrec.rdlength
1223 	if (!ValidateRData(rr->resrec.rrtype, rr->resrec.rdlength, rr->resrec.rdata))
1224 		{ LogMsg("Attempt to register record with invalid rdata: %s", ARDisplayString(m, rr)); return(mStatus_Invalid); }
1225 
1226 	rr->resrec.namehash   = DomainNameHashValue(rr->resrec.name);
1227 	rr->resrec.rdatahash  = target ? DomainNameHashValue(target) : RDataHashValue(&rr->resrec);
1228 
1229 	if (RRLocalOnly(rr))
1230 		{
1231 		// If this is supposed to be unique, make sure we don't have any name conflicts.
1232 		// If we found a conflict, we may still want to insert the record in the list but mark it appropriately
1233 		// (kDNSRecordTypeDeregistering) so that we deliver RMV events to the application. But this causes more
1234 		// complications and not clear whether there are any benefits. See rdar:9304275 for details.
1235 		// Hence, just bail out.
1236 		if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask)
1237 			{
1238 			if (CheckAuthRecordConflict(&m->rrauth, rr))
1239 				{
1240 				LogInfo("mDNS_Register_internal: Name conflict %s (%p), InterfaceID %p", ARDisplayString(m, rr), rr, rr->resrec.InterfaceID);
1241 				return mStatus_NameConflict;
1242 				}
1243 			}
1244 		}
1245 
1246 	// For uDNS records, we don't support duplicate checks at this time.
1247 #ifndef UNICAST_DISABLED
1248 	if (AuthRecord_uDNS(rr))
1249 		{
1250 		if (!m->NewLocalRecords) m->NewLocalRecords = rr;
1251 		// When we called SetTargetToHostName, it may have caused mDNS_Register_internal to be re-entered, appending new
1252 		// records to the list, so we now need to update p to advance to the new end to the list before appending our new record.
1253 		// Note that for AutoTunnel this should never happen, but this check makes the code future-proof.
1254 		while (*p) p=&(*p)->next;
1255 		*p = rr;
1256 		if (rr->resrec.RecordType == kDNSRecordTypeUnique) rr->resrec.RecordType = kDNSRecordTypeVerified;
1257 		rr->ProbeCount    = 0;
1258 		rr->AnnounceCount = 0;
1259 		if (rr->state != regState_NoTarget) ActivateUnicastRegistration(m, rr);
1260 		return(mStatus_NoError);			// <--- Note: For unicast records, code currently bails out at this point
1261 		}
1262 #endif
1263 
1264 	// Now that we've finished building our new record, make sure it's not identical to one we already have
1265 	if (RRLocalOnly(rr))
1266 		{
1267 		rr->ProbeCount    = 0;
1268 		rr->AnnounceCount = 0;
1269 		r = CheckAuthIdenticalRecord(&m->rrauth, rr);
1270 		}
1271 	else
1272 		{
1273 		for (r = m->ResourceRecords; r; r=r->next)
1274 			if (RecordIsLocalDuplicate(r, rr))
1275 				{
1276 				if (r->resrec.RecordType == kDNSRecordTypeDeregistering) r->AnnounceCount = 0;
1277 				else break;
1278 				}
1279 		}
1280 
1281 	if (r)
1282 		{
1283 		debugf("mDNS_Register_internal:Adding to duplicate list %s", ARDisplayString(m,rr));
1284 		*d = rr;
1285 		// If the previous copy of this record is already verified unique,
1286 		// then indicate that we should move this record promptly to kDNSRecordTypeUnique state.
1287 		// Setting ProbeCount to zero will cause SendQueries() to advance this record to
1288 		// kDNSRecordTypeVerified state and call the client callback at the next appropriate time.
1289 		if (rr->resrec.RecordType == kDNSRecordTypeUnique && r->resrec.RecordType == kDNSRecordTypeVerified)
1290 			rr->ProbeCount = 0;
1291 		}
1292 	else
1293 		{
1294 		debugf("mDNS_Register_internal: Adding to active record list %s", ARDisplayString(m,rr));
1295 		if (RRLocalOnly(rr))
1296 			{
1297 			AuthGroup *ag;
1298 			ag = InsertAuthRecord(m, &m->rrauth, rr);
1299 			if (ag && !ag->NewLocalOnlyRecords) {
1300 				m->NewLocalOnlyRecords = mDNStrue;
1301 				ag->NewLocalOnlyRecords = rr;
1302 			}
1303 			// No probing for LocalOnly records, Acknowledge them right away
1304 			if (rr->resrec.RecordType == kDNSRecordTypeUnique) rr->resrec.RecordType = kDNSRecordTypeVerified;
1305 			AcknowledgeRecord(m, rr);
1306 			return(mStatus_NoError);
1307 			}
1308 		else
1309 			{
1310 			if (!m->NewLocalRecords) m->NewLocalRecords = rr;
1311 			*p = rr;
1312 			}
1313 		}
1314 
1315 	if (!AuthRecord_uDNS(rr))	// This check is superfluous, given that for unicast records we (currently) bail out above
1316 		{
1317 		// For records that are not going to probe, acknowledge them right away
1318 		if (rr->resrec.RecordType != kDNSRecordTypeUnique && rr->resrec.RecordType != kDNSRecordTypeDeregistering)
1319 			AcknowledgeRecord(m, rr);
1320 
1321 		// Adding a record may affect whether or not we should sleep
1322 		mDNS_UpdateAllowSleep(m);
1323 		}
1324 
1325 	return(mStatus_NoError);
1326 	}
1327 
RecordProbeFailure(mDNS * const m,const AuthRecord * const rr)1328 mDNSlocal void RecordProbeFailure(mDNS *const m, const AuthRecord *const rr)
1329 	{
1330 	m->ProbeFailTime = m->timenow;
1331 	m->NumFailedProbes++;
1332 	// If we've had fifteen or more probe failures, rate-limit to one every five seconds.
1333 	// If a bunch of hosts have all been configured with the same name, then they'll all
1334 	// conflict and run through the same series of names: name-2, name-3, name-4, etc.,
1335 	// up to name-10. After that they'll start adding random increments in the range 1-100,
1336 	// so they're more likely to branch out in the available namespace and settle on a set of
1337 	// unique names quickly. If after five more tries the host is still conflicting, then we
1338 	// may have a serious problem, so we start rate-limiting so we don't melt down the network.
1339 	if (m->NumFailedProbes >= 15)
1340 		{
1341 		m->SuppressProbes = NonZeroTime(m->timenow + mDNSPlatformOneSecond * 5);
1342 		LogMsg("Excessive name conflicts (%lu) for %##s (%s); rate limiting in effect",
1343 			m->NumFailedProbes, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype));
1344 		}
1345 	}
1346 
CompleteRDataUpdate(mDNS * const m,AuthRecord * const rr)1347 mDNSlocal void CompleteRDataUpdate(mDNS *const m, AuthRecord *const rr)
1348 	{
1349 	RData *OldRData = rr->resrec.rdata;
1350 	mDNSu16 OldRDLen = rr->resrec.rdlength;
1351 	SetNewRData(&rr->resrec, rr->NewRData, rr->newrdlength);	// Update our rdata
1352 	rr->NewRData = mDNSNULL;									// Clear the NewRData pointer ...
1353 	if (rr->UpdateCallback)
1354 		rr->UpdateCallback(m, rr, OldRData, OldRDLen);			// ... and let the client know
1355 	}
1356 
1357 // Note: mDNS_Deregister_internal can call a user callback, which may change the record list and/or question list.
1358 // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this.
1359 // Exported so uDNS.c can call this
mDNS_Deregister_internal(mDNS * const m,AuthRecord * const rr,mDNS_Dereg_type drt)1360 mDNSexport mStatus mDNS_Deregister_internal(mDNS *const m, AuthRecord *const rr, mDNS_Dereg_type drt)
1361 	{
1362 	AuthRecord *r2;
1363 	mDNSu8 RecordType = rr->resrec.RecordType;
1364 	AuthRecord **p = &m->ResourceRecords;	// Find this record in our list of active records
1365 	mDNSBool dupList = mDNSfalse;
1366 
1367 	if (RRLocalOnly(rr))
1368 		{
1369 		AuthGroup *a;
1370 		AuthGroup **ag = &a;
1371 		AuthRecord **rp;
1372 		const mDNSu32 slot = AuthHashSlot(rr->resrec.name);
1373 
1374 		a = AuthGroupForRecord(&m->rrauth, slot, &rr->resrec);
1375 		if (!a) return mDNSfalse;
1376 		rp = &(*ag)->members;
1377 		while (*rp && *rp != rr) rp=&(*rp)->next;
1378 		p = rp;
1379 		}
1380 	else
1381 		{
1382 		while (*p && *p != rr) p=&(*p)->next;
1383 		}
1384 
1385 	if (*p)
1386 		{
1387 		// We found our record on the main list. See if there are any duplicates that need special handling.
1388 		if (drt == mDNS_Dereg_conflict)		// If this was a conflict, see that all duplicates get the same treatment
1389 			{
1390 			// Scan for duplicates of rr, and mark them for deregistration at the end of this routine, after we've finished
1391 			// deregistering rr. We need to do this scan *before* we give the client the chance to free and reuse the rr memory.
1392 			for (r2 = m->DuplicateRecords; r2; r2=r2->next) if (RecordIsLocalDuplicate(r2, rr)) r2->ProbeCount = 0xFF;
1393 			}
1394 		else
1395 			{
1396 			// Before we delete the record (and potentially send a goodbye packet)
1397 			// first see if we have a record on the duplicate list ready to take over from it.
1398 			AuthRecord **d = &m->DuplicateRecords;
1399 			while (*d && !RecordIsLocalDuplicate(*d, rr)) d=&(*d)->next;
1400 			if (*d)
1401 				{
1402 				AuthRecord *dup = *d;
1403 				debugf("mDNS_Register_internal: Duplicate record %p taking over from %p %##s (%s)",
1404 					dup, rr, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype));
1405 				*d        = dup->next;		// Cut replacement record from DuplicateRecords list
1406 				if (RRLocalOnly(rr))
1407 					{
1408 					dup->next = mDNSNULL;
1409 					if (!InsertAuthRecord(m, &m->rrauth, dup)) LogMsg("mDNS_Deregister_internal: ERROR!! cannot insert %s", ARDisplayString(m, dup));
1410 					}
1411 				else
1412 					{
1413 					dup->next = rr->next;		// And then...
1414 					rr->next  = dup;			// ... splice it in right after the record we're about to delete
1415 					}
1416 				dup->resrec.RecordType        = rr->resrec.RecordType;
1417 				dup->ProbeCount      = rr->ProbeCount;
1418 				dup->AnnounceCount   = rr->AnnounceCount;
1419 				dup->RequireGoodbye  = rr->RequireGoodbye;
1420 				dup->AnsweredLocalQ  = rr->AnsweredLocalQ;
1421 				dup->ImmedAnswer     = rr->ImmedAnswer;
1422 				dup->ImmedUnicast    = rr->ImmedUnicast;
1423 				dup->ImmedAdditional = rr->ImmedAdditional;
1424 				dup->v4Requester     = rr->v4Requester;
1425 				dup->v6Requester     = rr->v6Requester;
1426 				dup->ThisAPInterval  = rr->ThisAPInterval;
1427 				dup->LastAPTime      = rr->LastAPTime;
1428 				dup->LastMCTime      = rr->LastMCTime;
1429 				dup->LastMCInterface = rr->LastMCInterface;
1430 				dup->Private         = rr->Private;
1431 				dup->state           = rr->state;
1432 				rr->RequireGoodbye = mDNSfalse;
1433 				rr->AnsweredLocalQ = mDNSfalse;
1434 				}
1435 			}
1436 		}
1437 	else
1438 		{
1439 		// We didn't find our record on the main list; try the DuplicateRecords list instead.
1440 		p = &m->DuplicateRecords;
1441 		while (*p && *p != rr) p=&(*p)->next;
1442 		// If we found our record on the duplicate list, then make sure we don't send a goodbye for it
1443 		if (*p) { rr->RequireGoodbye = mDNSfalse; dupList = mDNStrue; }
1444 		if (*p) debugf("mDNS_Deregister_internal: Deleting DuplicateRecord %p %##s (%s)",
1445 			rr, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype));
1446 		}
1447 
1448 	if (!*p)
1449 		{
1450 		// No need to log an error message if we already know this is a potentially repeated deregistration
1451 		if (drt != mDNS_Dereg_repeat)
1452 			LogMsg("mDNS_Deregister_internal: Record %p not found in list %s", rr, ARDisplayString(m,rr));
1453 		return(mStatus_BadReferenceErr);
1454 		}
1455 
1456 	// If this is a shared record and we've announced it at least once,
1457 	// we need to retract that announcement before we delete the record
1458 
1459 	// If this is a record (including mDNSInterface_LocalOnly records) for which we've given local-only answers then
1460 	// it's tempting to just do "AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNSfalse)" here, but that would not not be safe.
1461 	// The AnswerAllLocalQuestionsWithLocalAuthRecord routine walks the question list invoking client callbacks, using the "m->CurrentQuestion"
1462 	// mechanism to cope with the client callback modifying the question list while that's happening.
1463 	// However, mDNS_Deregister could have been called from a client callback (e.g. from the domain enumeration callback FoundDomain)
1464 	// which means that the "m->CurrentQuestion" mechanism is already in use to protect that list, so we can't use it twice.
1465 	// More generally, if we invoke callbacks from within a client callback, then those callbacks could deregister other
1466 	// records, thereby invoking yet more callbacks, without limit.
1467 	// The solution is to defer delivering the "Remove" events until mDNS_Execute time, just like we do for sending
1468 	// actual goodbye packets.
1469 
1470 #ifndef UNICAST_DISABLED
1471 	if (AuthRecord_uDNS(rr))
1472 		{
1473 		if (rr->RequireGoodbye)
1474 			{
1475 			if (rr->tcp) { DisposeTCPConn(rr->tcp); rr->tcp = mDNSNULL; }
1476 			rr->resrec.RecordType    = kDNSRecordTypeDeregistering;
1477 			m->LocalRemoveEvents     = mDNStrue;
1478 			uDNS_DeregisterRecord(m, rr);
1479 			// At this point unconditionally we bail out
1480 			// Either uDNS_DeregisterRecord will have completed synchronously, and called CompleteDeregistration,
1481 			// which calls us back here with RequireGoodbye set to false, or it will have initiated the deregistration
1482 			// process and will complete asynchronously. Either way we don't need to do anything more here.
1483 			return(mStatus_NoError);
1484 			}
1485 		// Sometimes the records don't complete proper deregistration i.e., don't wait for a response
1486 		// from the server. In that case, if the records have been part of a group update, clear the
1487 		// state here. Some recors e.g., AutoTunnel gets reused without ever being completely initialized
1488 		rr->updateid = zeroID;
1489 
1490 		// We defer cleaning up NAT state only after sending goodbyes. This is important because
1491 		// RecordRegistrationGotZoneData guards against creating NAT state if clientContext is non-NULL.
1492 		// This happens today when we turn on/off interface where we get multiple network transitions
1493 		// and RestartRecordGetZoneData triggers re-registration of the resource records even though
1494 		// they may be in Registered state which causes NAT information to be setup multiple times. Defering
1495 		// the cleanup here keeps clientContext non-NULL and hence prevents that. Note that cleaning up
1496 		// NAT state here takes care of the case where we did not send goodbyes at all.
1497 		if (rr->NATinfo.clientContext)
1498 			{
1499 			mDNS_StopNATOperation_internal(m, &rr->NATinfo);
1500 			rr->NATinfo.clientContext = mDNSNULL;
1501 			}
1502 		if (rr->nta) { CancelGetZoneData(m, rr->nta); rr->nta = mDNSNULL; }
1503 		if (rr->tcp) { DisposeTCPConn(rr->tcp);       rr->tcp = mDNSNULL; }
1504 		}
1505 #endif // UNICAST_DISABLED
1506 
1507 	if      (RecordType == kDNSRecordTypeUnregistered)
1508 		LogMsg("mDNS_Deregister_internal: %s already marked kDNSRecordTypeUnregistered", ARDisplayString(m, rr));
1509 	else if (RecordType == kDNSRecordTypeDeregistering)
1510 		{
1511 		LogMsg("mDNS_Deregister_internal: %s already marked kDNSRecordTypeDeregistering", ARDisplayString(m, rr));
1512 		return(mStatus_BadReferenceErr);
1513 		}
1514 
1515 	// <rdar://problem/7457925> Local-only questions don't get remove events for unique records
1516 	// We may want to consider changing this code so that we generate local-only question "rmv"
1517 	// events (and maybe goodbye packets too) for unique records as well as for shared records
1518 	// Note: If we change the logic for this "if" statement, need to ensure that the code in
1519 	// CompleteDeregistration() sets the appropriate state variables to gaurantee that "else"
1520 	// clause will execute here and the record will be cut from the list.
1521 	if (rr->WakeUp.HMAC.l[0] ||
1522 		(RecordType == kDNSRecordTypeShared && (rr->RequireGoodbye || rr->AnsweredLocalQ)))
1523 		{
1524 		verbosedebugf("mDNS_Deregister_internal: Starting deregistration for %s", ARDisplayString(m, rr));
1525 		rr->resrec.RecordType    = kDNSRecordTypeDeregistering;
1526 		rr->resrec.rroriginalttl = 0;
1527 		rr->AnnounceCount        = rr->WakeUp.HMAC.l[0] ? WakeupCount : (drt == mDNS_Dereg_rapid) ? 1 : GoodbyeCount;
1528 		rr->ThisAPInterval       = mDNSPlatformOneSecond * 2;
1529 		rr->LastAPTime           = m->timenow - rr->ThisAPInterval;
1530 		m->LocalRemoveEvents     = mDNStrue;
1531 		if (m->NextScheduledResponse - (m->timenow + mDNSPlatformOneSecond/10) >= 0)
1532 			m->NextScheduledResponse = (m->timenow + mDNSPlatformOneSecond/10);
1533 		}
1534 	else
1535 		{
1536 		if (!dupList && RRLocalOnly(rr))
1537 			{
1538 			AuthGroup *ag = RemoveAuthRecord(m, &m->rrauth, rr);
1539 			if (ag->NewLocalOnlyRecords == rr) ag->NewLocalOnlyRecords = rr->next;
1540 			}
1541 		else
1542 			{
1543 			*p = rr->next;					// Cut this record from the list
1544 			if (m->NewLocalRecords == rr) m->NewLocalRecords = rr->next;
1545 			}
1546 		// If someone is about to look at this, bump the pointer forward
1547 		if (m->CurrentRecord   == rr) m->CurrentRecord   = rr->next;
1548 		rr->next = mDNSNULL;
1549 
1550 		// Should we generate local remove events here?
1551 		// i.e. something like:
1552 		// if (rr->AnsweredLocalQ) { AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNSfalse); rr->AnsweredLocalQ = mDNSfalse; }
1553 
1554 		verbosedebugf("mDNS_Deregister_internal: Deleting record for %s", ARDisplayString(m, rr));
1555 		rr->resrec.RecordType = kDNSRecordTypeUnregistered;
1556 
1557 		if ((drt == mDNS_Dereg_conflict || drt == mDNS_Dereg_repeat) && RecordType == kDNSRecordTypeShared)
1558 			debugf("mDNS_Deregister_internal: Cannot have a conflict on a shared record! %##s (%s)",
1559 				rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype));
1560 
1561 		// If we have an update queued up which never executed, give the client a chance to free that memory
1562 		if (rr->NewRData) CompleteRDataUpdate(m, rr);	// Update our rdata, clear the NewRData pointer, and return memory to the client
1563 
1564 
1565 		// CAUTION: MUST NOT do anything more with rr after calling rr->Callback(), because the client's callback function
1566 		// is allowed to do anything, including starting/stopping queries, registering/deregistering records, etc.
1567 		// In this case the likely client action to the mStatus_MemFree message is to free the memory,
1568 		// so any attempt to touch rr after this is likely to lead to a crash.
1569 		if (drt != mDNS_Dereg_conflict)
1570 			{
1571 			mDNS_DropLockBeforeCallback();		// Allow client to legally make mDNS API calls from the callback
1572 			LogInfo("mDNS_Deregister_internal: mStatus_MemFree for %s", ARDisplayString(m, rr));
1573 			if (rr->RecordCallback)
1574 				rr->RecordCallback(m, rr, mStatus_MemFree);			// MUST NOT touch rr after this
1575 			mDNS_ReclaimLockAfterCallback();	// Decrement mDNS_reentrancy to block mDNS API calls again
1576 			}
1577 		else
1578 			{
1579 			RecordProbeFailure(m, rr);
1580 			mDNS_DropLockBeforeCallback();		// Allow client to legally make mDNS API calls from the callback
1581 			if (rr->RecordCallback)
1582 				rr->RecordCallback(m, rr, mStatus_NameConflict);	// MUST NOT touch rr after this
1583 			mDNS_ReclaimLockAfterCallback();	// Decrement mDNS_reentrancy to block mDNS API calls again
1584 			// Now that we've finished deregistering rr, check our DuplicateRecords list for any that we marked previously.
1585 			// Note that with all the client callbacks going on, by the time we get here all the
1586 			// records we marked may have been explicitly deregistered by the client anyway.
1587 			r2 = m->DuplicateRecords;
1588 			while (r2)
1589 				{
1590 				if (r2->ProbeCount != 0xFF) r2 = r2->next;
1591 				else { mDNS_Deregister_internal(m, r2, mDNS_Dereg_conflict); r2 = m->DuplicateRecords; }
1592 				}
1593 			}
1594 		}
1595 	mDNS_UpdateAllowSleep(m);
1596 	return(mStatus_NoError);
1597 	}
1598 
1599 // ***************************************************************************
1600 #if COMPILER_LIKES_PRAGMA_MARK
1601 #pragma mark -
1602 #pragma mark - Packet Sending Functions
1603 #endif
1604 
AddRecordToResponseList(AuthRecord *** nrpp,AuthRecord * rr,AuthRecord * add)1605 mDNSlocal void AddRecordToResponseList(AuthRecord ***nrpp, AuthRecord *rr, AuthRecord *add)
1606 	{
1607 	if (rr->NextResponse == mDNSNULL && *nrpp != &rr->NextResponse)
1608 		{
1609 		**nrpp = rr;
1610 		// NR_AdditionalTo must point to a record with NR_AnswerTo set (and not NR_AdditionalTo)
1611 		// If 'add' does not meet this requirement, then follow its NR_AdditionalTo pointer to a record that does
1612 		// The referenced record will definitely be acceptable (by recursive application of this rule)
1613 		if (add && add->NR_AdditionalTo) add = add->NR_AdditionalTo;
1614 		rr->NR_AdditionalTo = add;
1615 		*nrpp = &rr->NextResponse;
1616 		}
1617 	debugf("AddRecordToResponseList: %##s (%s) already in list", rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype));
1618 	}
1619 
AddAdditionalsToResponseList(mDNS * const m,AuthRecord * ResponseRecords,AuthRecord *** nrpp,const mDNSInterfaceID InterfaceID)1620 mDNSlocal void AddAdditionalsToResponseList(mDNS *const m, AuthRecord *ResponseRecords, AuthRecord ***nrpp, const mDNSInterfaceID InterfaceID)
1621 	{
1622 	AuthRecord  *rr, *rr2;
1623 	for (rr=ResponseRecords; rr; rr=rr->NextResponse)			// For each record we plan to put
1624 		{
1625 		// (Note: This is an "if", not a "while". If we add a record, we'll find it again
1626 		// later in the "for" loop, and we will follow further "additional" links then.)
1627 		if (rr->Additional1 && ResourceRecordIsValidInterfaceAnswer(rr->Additional1, InterfaceID))
1628 			AddRecordToResponseList(nrpp, rr->Additional1, rr);
1629 
1630 		if (rr->Additional2 && ResourceRecordIsValidInterfaceAnswer(rr->Additional2, InterfaceID))
1631 			AddRecordToResponseList(nrpp, rr->Additional2, rr);
1632 
1633 		// For SRV records, automatically add the Address record(s) for the target host
1634 		if (rr->resrec.rrtype == kDNSType_SRV)
1635 			{
1636 			for (rr2=m->ResourceRecords; rr2; rr2=rr2->next)					// Scan list of resource records
1637 				if (RRTypeIsAddressType(rr2->resrec.rrtype) &&					// For all address records (A/AAAA) ...
1638 					ResourceRecordIsValidInterfaceAnswer(rr2, InterfaceID) &&	// ... which are valid for answer ...
1639 					rr->resrec.rdatahash == rr2->resrec.namehash &&			// ... whose name is the name of the SRV target
1640 					SameDomainName(&rr->resrec.rdata->u.srv.target, rr2->resrec.name))
1641 					AddRecordToResponseList(nrpp, rr2, rr);
1642 			}
1643 		else if (RRTypeIsAddressType(rr->resrec.rrtype))	// For A or AAAA, put counterpart as additional
1644 			{
1645 			for (rr2=m->ResourceRecords; rr2; rr2=rr2->next)					// Scan list of resource records
1646 				if (RRTypeIsAddressType(rr2->resrec.rrtype) &&					// For all address records (A/AAAA) ...
1647 					ResourceRecordIsValidInterfaceAnswer(rr2, InterfaceID) &&	// ... which are valid for answer ...
1648 					rr->resrec.namehash == rr2->resrec.namehash &&				// ... and have the same name
1649 					SameDomainName(rr->resrec.name, rr2->resrec.name))
1650 					AddRecordToResponseList(nrpp, rr2, rr);
1651 			}
1652 		else if (rr->resrec.rrtype == kDNSType_PTR)			// For service PTR, see if we want to add DeviceInfo record
1653 			{
1654 			if (ResourceRecordIsValidInterfaceAnswer(&m->DeviceInfo, InterfaceID) &&
1655 				SameDomainLabel(rr->resrec.rdata->u.name.c, m->DeviceInfo.resrec.name->c))
1656 				AddRecordToResponseList(nrpp, &m->DeviceInfo, rr);
1657 			}
1658 		}
1659 	}
1660 
SendDelayedUnicastResponse(mDNS * const m,const mDNSAddr * const dest,const mDNSInterfaceID InterfaceID)1661 mDNSlocal void SendDelayedUnicastResponse(mDNS *const m, const mDNSAddr *const dest, const mDNSInterfaceID InterfaceID)
1662 	{
1663 	AuthRecord *rr;
1664 	AuthRecord  *ResponseRecords = mDNSNULL;
1665 	AuthRecord **nrp             = &ResponseRecords;
1666 	NetworkInterfaceInfo *intf = FirstInterfaceForID(m, InterfaceID);
1667 
1668 	// Make a list of all our records that need to be unicast to this destination
1669 	for (rr = m->ResourceRecords; rr; rr=rr->next)
1670 		{
1671 		// If we find we can no longer unicast this answer, clear ImmedUnicast
1672 		if (rr->ImmedAnswer == mDNSInterfaceMark               ||
1673 			mDNSSameIPv4Address(rr->v4Requester, onesIPv4Addr) ||
1674 			mDNSSameIPv6Address(rr->v6Requester, onesIPv6Addr)  )
1675 			rr->ImmedUnicast = mDNSfalse;
1676 
1677 		if (rr->ImmedUnicast && rr->ImmedAnswer == InterfaceID)
1678 			{
1679 			if ((dest->type == mDNSAddrType_IPv4 && mDNSSameIPv4Address(rr->v4Requester, dest->ip.v4)) ||
1680 				(dest->type == mDNSAddrType_IPv6 && mDNSSameIPv6Address(rr->v6Requester, dest->ip.v6)))
1681 				{
1682 				rr->ImmedAnswer  = mDNSNULL;				// Clear the state fields
1683 				rr->ImmedUnicast = mDNSfalse;
1684 				rr->v4Requester  = zerov4Addr;
1685 				rr->v6Requester  = zerov6Addr;
1686 
1687 				// Only sent records registered for P2P over P2P interfaces
1688 				if (intf && !mDNSPlatformValidRecordForInterface(rr, intf))
1689 					{
1690 					LogInfo("SendDelayedUnicastResponse: Not sending %s, on %s", ARDisplayString(m, rr), InterfaceNameForID(m, InterfaceID));
1691 					continue;
1692 					}
1693 
1694 				if (rr->NextResponse == mDNSNULL && nrp != &rr->NextResponse)	// rr->NR_AnswerTo
1695 					{ rr->NR_AnswerTo = (mDNSu8*)~0; *nrp = rr; nrp = &rr->NextResponse; }
1696 				}
1697 			}
1698 		}
1699 
1700 	AddAdditionalsToResponseList(m, ResponseRecords, &nrp, InterfaceID);
1701 
1702 	while (ResponseRecords)
1703 		{
1704 		mDNSu8 *responseptr = m->omsg.data;
1705 		mDNSu8 *newptr;
1706 		InitializeDNSMessage(&m->omsg.h, zeroID, ResponseFlags);
1707 
1708 		// Put answers in the packet
1709 		while (ResponseRecords && ResponseRecords->NR_AnswerTo)
1710 			{
1711 			rr = ResponseRecords;
1712 			if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask)
1713 				rr->resrec.rrclass |= kDNSClass_UniqueRRSet;		// Temporarily set the cache flush bit so PutResourceRecord will set it
1714 			newptr = PutResourceRecord(&m->omsg, responseptr, &m->omsg.h.numAnswers, &rr->resrec);
1715 			rr->resrec.rrclass &= ~kDNSClass_UniqueRRSet;			// Make sure to clear cache flush bit back to normal state
1716 			if (!newptr && m->omsg.h.numAnswers) break;	// If packet full, send it now
1717 			if (newptr) responseptr = newptr;
1718 			ResponseRecords = rr->NextResponse;
1719 			rr->NextResponse    = mDNSNULL;
1720 			rr->NR_AnswerTo     = mDNSNULL;
1721 			rr->NR_AdditionalTo = mDNSNULL;
1722 			rr->RequireGoodbye  = mDNStrue;
1723 			}
1724 
1725 		// Add additionals, if there's space
1726 		while (ResponseRecords && !ResponseRecords->NR_AnswerTo)
1727 			{
1728 			rr = ResponseRecords;
1729 			if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask)
1730 				rr->resrec.rrclass |= kDNSClass_UniqueRRSet;		// Temporarily set the cache flush bit so PutResourceRecord will set it
1731 			newptr = PutResourceRecord(&m->omsg, responseptr, &m->omsg.h.numAdditionals, &rr->resrec);
1732 			rr->resrec.rrclass &= ~kDNSClass_UniqueRRSet;			// Make sure to clear cache flush bit back to normal state
1733 
1734 			if (newptr) responseptr = newptr;
1735 			if (newptr && m->omsg.h.numAnswers) rr->RequireGoodbye = mDNStrue;
1736 			else if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask) rr->ImmedAnswer = mDNSInterfaceMark;
1737 			ResponseRecords = rr->NextResponse;
1738 			rr->NextResponse    = mDNSNULL;
1739 			rr->NR_AnswerTo     = mDNSNULL;
1740 			rr->NR_AdditionalTo = mDNSNULL;
1741 			}
1742 
1743 		if (m->omsg.h.numAnswers)
1744 			mDNSSendDNSMessage(m, &m->omsg, responseptr, InterfaceID, mDNSNULL, dest, MulticastDNSPort, mDNSNULL, mDNSNULL);
1745 		}
1746 	}
1747 
1748 // CompleteDeregistration guarantees that on exit the record will have been cut from the m->ResourceRecords list
1749 // and the client's mStatus_MemFree callback will have been invoked
CompleteDeregistration(mDNS * const m,AuthRecord * rr)1750 mDNSexport void CompleteDeregistration(mDNS *const m, AuthRecord *rr)
1751 	{
1752 	LogInfo("CompleteDeregistration: called for Resource record %s", ARDisplayString(m, rr));
1753 	// Clearing rr->RequireGoodbye signals mDNS_Deregister_internal() that
1754 	// it should go ahead and immediately dispose of this registration
1755 	rr->resrec.RecordType = kDNSRecordTypeShared;
1756 	rr->RequireGoodbye    = mDNSfalse;
1757 	rr->WakeUp.HMAC       = zeroEthAddr;
1758 	if (rr->AnsweredLocalQ) { AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNSfalse); rr->AnsweredLocalQ = mDNSfalse; }
1759 	mDNS_Deregister_internal(m, rr, mDNS_Dereg_normal);		// Don't touch rr after this
1760 	}
1761 
1762 // DiscardDeregistrations is used on shutdown and sleep to discard (forcibly and immediately)
1763 // any deregistering records that remain in the m->ResourceRecords list.
1764 // DiscardDeregistrations calls mDNS_Deregister_internal which can call a user callback,
1765 // which may change the record list and/or question list.
1766 // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this.
DiscardDeregistrations(mDNS * const m)1767 mDNSlocal void DiscardDeregistrations(mDNS *const m)
1768 	{
1769 	if (m->CurrentRecord)
1770 		LogMsg("DiscardDeregistrations ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord));
1771 	m->CurrentRecord = m->ResourceRecords;
1772 
1773 	while (m->CurrentRecord)
1774 		{
1775 		AuthRecord *rr = m->CurrentRecord;
1776 		if (!AuthRecord_uDNS(rr) && rr->resrec.RecordType == kDNSRecordTypeDeregistering)
1777 			CompleteDeregistration(m, rr);		// Don't touch rr after this
1778 		else
1779 			m->CurrentRecord = rr->next;
1780 		}
1781 	}
1782 
GetLabelDecimalValue(const mDNSu8 * const src,mDNSu8 * dst)1783 mDNSlocal mStatus GetLabelDecimalValue(const mDNSu8 *const src, mDNSu8 *dst)
1784 	{
1785 	int i, val = 0;
1786 	if (src[0] < 1 || src[0] > 3) return(mStatus_Invalid);
1787 	for (i=1; i<=src[0]; i++)
1788 		{
1789 		if (src[i] < '0' || src[i] > '9') return(mStatus_Invalid);
1790 		val = val * 10 + src[i] - '0';
1791 		}
1792 	if (val > 255) return(mStatus_Invalid);
1793 	*dst = (mDNSu8)val;
1794 	return(mStatus_NoError);
1795 	}
1796 
GetIPv4FromName(mDNSAddr * const a,const domainname * const name)1797 mDNSlocal mStatus GetIPv4FromName(mDNSAddr *const a, const domainname *const name)
1798 	{
1799 	int skip = CountLabels(name) - 6;
1800 	if (skip < 0) { LogMsg("GetIPFromName: Need six labels in IPv4 reverse mapping name %##s", name); return mStatus_Invalid; }
1801 	if (GetLabelDecimalValue(SkipLeadingLabels(name, skip+3)->c, &a->ip.v4.b[0]) ||
1802 		GetLabelDecimalValue(SkipLeadingLabels(name, skip+2)->c, &a->ip.v4.b[1]) ||
1803 		GetLabelDecimalValue(SkipLeadingLabels(name, skip+1)->c, &a->ip.v4.b[2]) ||
1804 		GetLabelDecimalValue(SkipLeadingLabels(name, skip+0)->c, &a->ip.v4.b[3])) return mStatus_Invalid;
1805 	a->type = mDNSAddrType_IPv4;
1806 	return(mStatus_NoError);
1807 	}
1808 
1809 #define HexVal(X) ( ((X) >= '0' && (X) <= '9') ? ((X) - '0'     ) :   \
1810 					((X) >= 'A' && (X) <= 'F') ? ((X) - 'A' + 10) :   \
1811 					((X) >= 'a' && (X) <= 'f') ? ((X) - 'a' + 10) : -1)
1812 
GetIPv6FromName(mDNSAddr * const a,const domainname * const name)1813 mDNSlocal mStatus GetIPv6FromName(mDNSAddr *const a, const domainname *const name)
1814 	{
1815 	int i, h, l;
1816 	const domainname *n;
1817 
1818 	int skip = CountLabels(name) - 34;
1819 	if (skip < 0) { LogMsg("GetIPFromName: Need 34 labels in IPv6 reverse mapping name %##s", name); return mStatus_Invalid; }
1820 
1821 	n = SkipLeadingLabels(name, skip);
1822 	for (i=0; i<16; i++)
1823 		{
1824 		if (n->c[0] != 1) return mStatus_Invalid;
1825 		l = HexVal(n->c[1]);
1826 		n = (const domainname *)(n->c + 2);
1827 
1828 		if (n->c[0] != 1) return mStatus_Invalid;
1829 		h = HexVal(n->c[1]);
1830 		n = (const domainname *)(n->c + 2);
1831 
1832 		if (l<0 || h<0) return mStatus_Invalid;
1833 		a->ip.v6.b[15-i] = (mDNSu8)((h << 4) | l);
1834 		}
1835 
1836 	a->type = mDNSAddrType_IPv6;
1837 	return(mStatus_NoError);
1838 	}
1839 
ReverseMapDomainType(const domainname * const name)1840 mDNSlocal mDNSs32 ReverseMapDomainType(const domainname *const name)
1841 	{
1842 	int skip = CountLabels(name) - 2;
1843 	if (skip >= 0)
1844 		{
1845 		const domainname *suffix = SkipLeadingLabels(name, skip);
1846 		if (SameDomainName(suffix, (const domainname*)"\x7" "in-addr" "\x4" "arpa")) return mDNSAddrType_IPv4;
1847 		if (SameDomainName(suffix, (const domainname*)"\x3" "ip6"     "\x4" "arpa")) return mDNSAddrType_IPv6;
1848 		}
1849 	return(mDNSAddrType_None);
1850 	}
1851 
SendARP(mDNS * const m,const mDNSu8 op,const AuthRecord * const rr,const mDNSv4Addr * const spa,const mDNSEthAddr * const tha,const mDNSv4Addr * const tpa,const mDNSEthAddr * const dst)1852 mDNSlocal void SendARP(mDNS *const m, const mDNSu8 op, const AuthRecord *const rr,
1853 	const mDNSv4Addr *const spa, const mDNSEthAddr *const tha, const mDNSv4Addr *const tpa, const mDNSEthAddr *const dst)
1854 	{
1855 	int i;
1856 	mDNSu8 *ptr = m->omsg.data;
1857 	NetworkInterfaceInfo *intf = FirstInterfaceForID(m, rr->resrec.InterfaceID);
1858 	if (!intf) { LogMsg("SendARP: No interface with InterfaceID %p found %s", rr->resrec.InterfaceID, ARDisplayString(m,rr)); return; }
1859 
1860 	// 0x00 Destination address
1861 	for (i=0; i<6; i++) *ptr++ = dst->b[i];
1862 
1863 	// 0x06 Source address (Note: Since we don't currently set the BIOCSHDRCMPLT option, BPF will fill in the real interface address for us)
1864 	for (i=0; i<6; i++) *ptr++ = intf->MAC.b[0];
1865 
1866 	// 0x0C ARP Ethertype (0x0806)
1867 	*ptr++ = 0x08; *ptr++ = 0x06;
1868 
1869 	// 0x0E ARP header
1870 	*ptr++ = 0x00; *ptr++ = 0x01;	// Hardware address space; Ethernet = 1
1871 	*ptr++ = 0x08; *ptr++ = 0x00;	// Protocol address space; IP = 0x0800
1872 	*ptr++ = 6;						// Hardware address length
1873 	*ptr++ = 4;						// Protocol address length
1874 	*ptr++ = 0x00; *ptr++ = op;		// opcode; Request = 1, Response = 2
1875 
1876 	// 0x16 Sender hardware address (our MAC address)
1877 	for (i=0; i<6; i++) *ptr++ = intf->MAC.b[i];
1878 
1879 	// 0x1C Sender protocol address
1880 	for (i=0; i<4; i++) *ptr++ = spa->b[i];
1881 
1882 	// 0x20 Target hardware address
1883 	for (i=0; i<6; i++) *ptr++ = tha->b[i];
1884 
1885 	// 0x26 Target protocol address
1886 	for (i=0; i<4; i++) *ptr++ = tpa->b[i];
1887 
1888 	// 0x2A Total ARP Packet length 42 bytes
1889 	mDNSPlatformSendRawPacket(m->omsg.data, ptr, rr->resrec.InterfaceID);
1890 	}
1891 
CheckSum(const void * const data,mDNSs32 length,mDNSu32 sum)1892 mDNSlocal mDNSu16 CheckSum(const void *const data, mDNSs32 length, mDNSu32 sum)
1893 	{
1894 	const mDNSu16 *ptr = data;
1895 	while (length > 0) { length -= 2; sum += *ptr++; }
1896 	sum = (sum & 0xFFFF) + (sum >> 16);
1897 	sum = (sum & 0xFFFF) + (sum >> 16);
1898 	return(sum != 0xFFFF ? sum : 0);
1899 	}
1900 
IPv6CheckSum(const mDNSv6Addr * const src,const mDNSv6Addr * const dst,const mDNSu8 protocol,const void * const data,const mDNSu32 length)1901 mDNSlocal mDNSu16 IPv6CheckSum(const mDNSv6Addr *const src, const mDNSv6Addr *const dst, const mDNSu8 protocol, const void *const data, const mDNSu32 length)
1902 	{
1903 	IPv6PseudoHeader ph;
1904 	ph.src = *src;
1905 	ph.dst = *dst;
1906 	ph.len.b[0] = length >> 24;
1907 	ph.len.b[1] = length >> 16;
1908 	ph.len.b[2] = length >> 8;
1909 	ph.len.b[3] = length;
1910 	ph.pro.b[0] = 0;
1911 	ph.pro.b[1] = 0;
1912 	ph.pro.b[2] = 0;
1913 	ph.pro.b[3] = protocol;
1914 	return CheckSum(&ph, sizeof(ph), CheckSum(data, length, 0));
1915 	}
1916 
SendNDP(mDNS * const m,const mDNSu8 op,const mDNSu8 flags,const AuthRecord * const rr,const mDNSv6Addr * const spa,const mDNSEthAddr * const tha,const mDNSv6Addr * const tpa,const mDNSEthAddr * const dst)1917 mDNSlocal void SendNDP(mDNS *const m, const mDNSu8 op, const mDNSu8 flags, const AuthRecord *const rr,
1918 	const mDNSv6Addr *const spa, const mDNSEthAddr *const tha, const mDNSv6Addr *const tpa, const mDNSEthAddr *const dst)
1919 	{
1920 	int i;
1921 	mDNSOpaque16 checksum;
1922 	mDNSu8 *ptr = m->omsg.data;
1923 	// Some recipient hosts seem to ignore Neighbor Solicitations if the IPv6-layer destination address is not the
1924 	// appropriate IPv6 solicited node multicast address, so we use that IPv6-layer destination address, even though
1925 	// at the Ethernet-layer we unicast the packet to the intended target, to avoid wasting network bandwidth.
1926 	const mDNSv6Addr mc = { { 0xFF,0x02,0x00,0x00, 0,0,0,0, 0,0,0,1, 0xFF,tpa->b[0xD],tpa->b[0xE],tpa->b[0xF] } };
1927 	const mDNSv6Addr *const v6dst = (op == NDP_Sol) ? &mc : tpa;
1928 	NetworkInterfaceInfo *intf = FirstInterfaceForID(m, rr->resrec.InterfaceID);
1929 	if (!intf) { LogMsg("SendNDP: No interface with InterfaceID %p found %s", rr->resrec.InterfaceID, ARDisplayString(m,rr)); return; }
1930 
1931 	// 0x00 Destination address
1932 	for (i=0; i<6; i++) *ptr++ = dst->b[i];
1933 	// Right now we only send Neighbor Solicitations to verify whether the host we're proxying for has gone to sleep yet.
1934 	// Since we know who we're looking for, we send it via Ethernet-layer unicast, rather than bothering every host on the
1935 	// link with a pointless link-layer multicast.
1936 	// Should we want to send traditional Neighbor Solicitations in the future, where we really don't know in advance what
1937 	// Ethernet-layer address we're looking for, we'll need to send to the appropriate Ethernet-layer multicast address:
1938 	// *ptr++ = 0x33;
1939 	// *ptr++ = 0x33;
1940 	// *ptr++ = 0xFF;
1941 	// *ptr++ = tpa->b[0xD];
1942 	// *ptr++ = tpa->b[0xE];
1943 	// *ptr++ = tpa->b[0xF];
1944 
1945 	// 0x06 Source address (Note: Since we don't currently set the BIOCSHDRCMPLT option, BPF will fill in the real interface address for us)
1946 	for (i=0; i<6; i++) *ptr++ = (tha ? *tha : intf->MAC).b[i];
1947 
1948 	// 0x0C IPv6 Ethertype (0x86DD)
1949 	*ptr++ = 0x86; *ptr++ = 0xDD;
1950 
1951 	// 0x0E IPv6 header
1952 	*ptr++ = 0x60; *ptr++ = 0x00; *ptr++ = 0x00; *ptr++ = 0x00;		// Version, Traffic Class, Flow Label
1953 	*ptr++ = 0x00; *ptr++ = 0x20;									// Length
1954 	*ptr++ = 0x3A;													// Protocol == ICMPv6
1955 	*ptr++ = 0xFF;													// Hop Limit
1956 
1957 	// 0x16 Sender IPv6 address
1958 	for (i=0; i<16; i++) *ptr++ = spa->b[i];
1959 
1960 	// 0x26 Destination IPv6 address
1961 	for (i=0; i<16; i++) *ptr++ = v6dst->b[i];
1962 
1963 	// 0x36 NDP header
1964 	*ptr++ = op;					// 0x87 == Neighbor Solicitation, 0x88 == Neighbor Advertisement
1965 	*ptr++ = 0x00;					// Code
1966 	*ptr++ = 0x00; *ptr++ = 0x00;	// Checksum placeholder (0x38, 0x39)
1967 	*ptr++ = flags;
1968 	*ptr++ = 0x00; *ptr++ = 0x00; *ptr++ = 0x00;
1969 
1970 	if (op == NDP_Sol)	// Neighbor Solicitation. The NDP "target" is the address we seek.
1971 		{
1972 		// 0x3E NDP target.
1973 		for (i=0; i<16; i++) *ptr++ = tpa->b[i];
1974 		// 0x4E Source Link-layer Address
1975 		// <http://www.ietf.org/rfc/rfc2461.txt>
1976 		// MUST NOT be included when the source IP address is the unspecified address.
1977 		// Otherwise, on link layers that have addresses this option MUST be included
1978 		// in multicast solicitations and SHOULD be included in unicast solicitations.
1979 		if (!mDNSIPv6AddressIsZero(*spa))
1980 			{
1981 			*ptr++ = NDP_SrcLL;	// Option Type 1 == Source Link-layer Address
1982 			*ptr++ = 0x01;		// Option length 1 (in units of 8 octets)
1983 			for (i=0; i<6; i++) *ptr++ = (tha ? *tha : intf->MAC).b[i];
1984 			}
1985 		}
1986 	else			// Neighbor Advertisement. The NDP "target" is the address we're giving information about.
1987 		{
1988 		// 0x3E NDP target.
1989 		for (i=0; i<16; i++) *ptr++ = spa->b[i];
1990 		// 0x4E Target Link-layer Address
1991 		*ptr++ = NDP_TgtLL;	// Option Type 2 == Target Link-layer Address
1992 		*ptr++ = 0x01;		// Option length 1 (in units of 8 octets)
1993 		for (i=0; i<6; i++) *ptr++ = (tha ? *tha : intf->MAC).b[i];
1994 		}
1995 
1996 	// 0x4E or 0x56 Total NDP Packet length 78 or 86 bytes
1997 	m->omsg.data[0x13] = ptr - &m->omsg.data[0x36];		// Compute actual length
1998 	checksum.NotAnInteger = ~IPv6CheckSum(spa, v6dst, 0x3A, &m->omsg.data[0x36], m->omsg.data[0x13]);
1999 	m->omsg.data[0x38] = checksum.b[0];
2000 	m->omsg.data[0x39] = checksum.b[1];
2001 
2002 	mDNSPlatformSendRawPacket(m->omsg.data, ptr, rr->resrec.InterfaceID);
2003 	}
2004 
SetupOwnerOpt(const mDNS * const m,const NetworkInterfaceInfo * const intf,rdataOPT * const owner)2005 mDNSlocal void SetupOwnerOpt(const mDNS *const m, const NetworkInterfaceInfo *const intf, rdataOPT *const owner)
2006 	{
2007 	owner->u.owner.vers     = 0;
2008 	owner->u.owner.seq      = m->SleepSeqNum;
2009 	owner->u.owner.HMAC     = m->PrimaryMAC;
2010 	owner->u.owner.IMAC     = intf->MAC;
2011 	owner->u.owner.password = zeroEthAddr;
2012 
2013 	// Don't try to compute the optlen until *after* we've set up the data fields
2014 	// Right now the DNSOpt_Owner_Space macro does not depend on the owner->u.owner being set up correctly, but in the future it might
2015 	owner->opt              = kDNSOpt_Owner;
2016 	owner->optlen           = DNSOpt_Owner_Space(&m->PrimaryMAC, &intf->MAC) - 4;
2017 	}
2018 
GrantUpdateCredit(AuthRecord * rr)2019 mDNSlocal void GrantUpdateCredit(AuthRecord *rr)
2020 	{
2021 	if (++rr->UpdateCredits >= kMaxUpdateCredits) rr->NextUpdateCredit = 0;
2022 	else rr->NextUpdateCredit = NonZeroTime(rr->NextUpdateCredit + kUpdateCreditRefreshInterval);
2023 	}
2024 
2025 // Note about acceleration of announcements to facilitate automatic coalescing of
2026 // multiple independent threads of announcements into a single synchronized thread:
2027 // The announcements in the packet may be at different stages of maturity;
2028 // One-second interval, two-second interval, four-second interval, and so on.
2029 // After we've put in all the announcements that are due, we then consider
2030 // whether there are other nearly-due announcements that are worth accelerating.
2031 // To be eligible for acceleration, a record MUST NOT be older (further along
2032 // its timeline) than the most mature record we've already put in the packet.
2033 // In other words, younger records can have their timelines accelerated to catch up
2034 // with their elder bretheren; this narrows the age gap and helps them eventually get in sync.
2035 // Older records cannot have their timelines accelerated; this would just widen
2036 // the gap between them and their younger bretheren and get them even more out of sync.
2037 
2038 // Note: SendResponses calls mDNS_Deregister_internal which can call a user callback, which may change
2039 // the record list and/or question list.
2040 // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this.
SendResponses(mDNS * const m)2041 mDNSlocal void SendResponses(mDNS *const m)
2042 	{
2043 	int pktcount = 0;
2044 	AuthRecord *rr, *r2;
2045 	mDNSs32 maxExistingAnnounceInterval = 0;
2046 	const NetworkInterfaceInfo *intf = GetFirstActiveInterface(m->HostInterfaces);
2047 
2048 	m->NextScheduledResponse = m->timenow + 0x78000000;
2049 
2050 	if (m->SleepState == SleepState_Transferring) RetrySPSRegistrations(m);
2051 
2052 	for (rr = m->ResourceRecords; rr; rr=rr->next)
2053 		if (rr->ImmedUnicast)
2054 			{
2055 			mDNSAddr v4 = { mDNSAddrType_IPv4, {{{0}}} };
2056 			mDNSAddr v6 = { mDNSAddrType_IPv6, {{{0}}} };
2057 			v4.ip.v4 = rr->v4Requester;
2058 			v6.ip.v6 = rr->v6Requester;
2059 			if (!mDNSIPv4AddressIsZero(rr->v4Requester)) SendDelayedUnicastResponse(m, &v4, rr->ImmedAnswer);
2060 			if (!mDNSIPv6AddressIsZero(rr->v6Requester)) SendDelayedUnicastResponse(m, &v6, rr->ImmedAnswer);
2061 			if (rr->ImmedUnicast)
2062 				{
2063 				LogMsg("SendResponses: ERROR: rr->ImmedUnicast still set: %s", ARDisplayString(m, rr));
2064 				rr->ImmedUnicast = mDNSfalse;
2065 				}
2066 			}
2067 
2068 	// ***
2069 	// *** 1. Setup: Set the SendRNow and ImmedAnswer fields to indicate which interface(s) the records need to be sent on
2070 	// ***
2071 
2072 	// Run through our list of records, and decide which ones we're going to announce on all interfaces
2073 	for (rr = m->ResourceRecords; rr; rr=rr->next)
2074 		{
2075 		while (rr->NextUpdateCredit && m->timenow - rr->NextUpdateCredit >= 0) GrantUpdateCredit(rr);
2076 		if (TimeToAnnounceThisRecord(rr, m->timenow))
2077 			{
2078 			if (rr->resrec.RecordType == kDNSRecordTypeDeregistering)
2079 				{
2080 				if (!rr->WakeUp.HMAC.l[0])
2081 					{
2082 					if (rr->AnnounceCount) rr->ImmedAnswer = mDNSInterfaceMark;		// Send goodbye packet on all interfaces
2083 					}
2084 				else
2085 					{
2086 					LogSPS("SendResponses: Sending wakeup %2d for %.6a %s", rr->AnnounceCount-3, &rr->WakeUp.IMAC, ARDisplayString(m, rr));
2087 					SendWakeup(m, rr->resrec.InterfaceID, &rr->WakeUp.IMAC, &rr->WakeUp.password);
2088 					for (r2 = rr; r2; r2=r2->next)
2089 						if (r2->AnnounceCount && r2->resrec.InterfaceID == rr->resrec.InterfaceID && mDNSSameEthAddress(&r2->WakeUp.IMAC, &rr->WakeUp.IMAC))
2090 							{
2091 							// For now we only want to send a single Unsolicited Neighbor Advertisement restoring the address to the original
2092 							// owner, because these packets can cause some IPv6 stacks to falsely conclude that there's an address conflict.
2093 							if (r2->AddressProxy.type == mDNSAddrType_IPv6 && r2->AnnounceCount == WakeupCount)
2094 								{
2095 								LogSPS("NDP Announcement %2d Releasing traffic for H-MAC %.6a I-MAC %.6a %s",
2096 									r2->AnnounceCount-3, &r2->WakeUp.HMAC, &r2->WakeUp.IMAC, ARDisplayString(m,r2));
2097 								SendNDP(m, NDP_Adv, NDP_Override, r2, &r2->AddressProxy.ip.v6, &r2->WakeUp.IMAC, &AllHosts_v6, &AllHosts_v6_Eth);
2098 								}
2099 							r2->LastAPTime = m->timenow;
2100 							// After 15 wakeups without success (maybe host has left the network) send three goodbyes instead
2101 							if (--r2->AnnounceCount <= GoodbyeCount) r2->WakeUp.HMAC = zeroEthAddr;
2102 							}
2103 					}
2104 				}
2105 			else if (ResourceRecordIsValidAnswer(rr))
2106 				{
2107 				if (rr->AddressProxy.type)
2108 					{
2109 					rr->AnnounceCount--;
2110 					rr->ThisAPInterval *= 2;
2111 					rr->LastAPTime = m->timenow;
2112 					if (rr->AddressProxy.type == mDNSAddrType_IPv4)
2113 						{
2114 						LogSPS("ARP Announcement %2d Capturing traffic for H-MAC %.6a I-MAC %.6a %s",
2115 							rr->AnnounceCount, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, ARDisplayString(m,rr));
2116 						SendARP(m, 1, rr, &rr->AddressProxy.ip.v4, &zeroEthAddr, &rr->AddressProxy.ip.v4, &onesEthAddr);
2117 						}
2118 					else if (rr->AddressProxy.type == mDNSAddrType_IPv6)
2119 						{
2120 						LogSPS("NDP Announcement %2d Capturing traffic for H-MAC %.6a I-MAC %.6a %s",
2121 							rr->AnnounceCount, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, ARDisplayString(m,rr));
2122 						SendNDP(m, NDP_Adv, NDP_Override, rr, &rr->AddressProxy.ip.v6, mDNSNULL, &AllHosts_v6, &AllHosts_v6_Eth);
2123 						}
2124 					}
2125 				else
2126 					{
2127 					rr->ImmedAnswer = mDNSInterfaceMark;		// Send on all interfaces
2128 					if (maxExistingAnnounceInterval < rr->ThisAPInterval)
2129 						maxExistingAnnounceInterval = rr->ThisAPInterval;
2130 					if (rr->UpdateBlocked) rr->UpdateBlocked = 0;
2131 					}
2132 				}
2133 			}
2134 		}
2135 
2136 	// Any interface-specific records we're going to send are marked as being sent on all appropriate interfaces (which is just one)
2137 	// Eligible records that are more than half-way to their announcement time are accelerated
2138 	for (rr = m->ResourceRecords; rr; rr=rr->next)
2139 		if ((rr->resrec.InterfaceID && rr->ImmedAnswer) ||
2140 			(rr->ThisAPInterval <= maxExistingAnnounceInterval &&
2141 			TimeToAnnounceThisRecord(rr, m->timenow + rr->ThisAPInterval/2) &&
2142 			!rr->AddressProxy.type && 					// Don't include ARP Annoucements when considering which records to accelerate
2143 			ResourceRecordIsValidAnswer(rr)))
2144 			rr->ImmedAnswer = mDNSInterfaceMark;		// Send on all interfaces
2145 
2146 	// When sending SRV records (particularly when announcing a new service) automatically add related Address record(s) as additionals
2147 	// Note: Currently all address records are interface-specific, so it's safe to set ImmedAdditional to their InterfaceID,
2148 	// which will be non-null. If by some chance there is an address record that's not interface-specific (should never happen)
2149 	// then all that means is that it won't get sent -- which would not be the end of the world.
2150 	for (rr = m->ResourceRecords; rr; rr=rr->next)
2151 		{
2152 		if (rr->ImmedAnswer && rr->resrec.rrtype == kDNSType_SRV)
2153 			for (r2=m->ResourceRecords; r2; r2=r2->next)				// Scan list of resource records
2154 				if (RRTypeIsAddressType(r2->resrec.rrtype) &&			// For all address records (A/AAAA) ...
2155 					ResourceRecordIsValidAnswer(r2) &&					// ... which are valid for answer ...
2156 					rr->LastMCTime - r2->LastMCTime >= 0 &&				// ... which we have not sent recently ...
2157 					rr->resrec.rdatahash == r2->resrec.namehash &&		// ... whose name is the name of the SRV target
2158 					SameDomainName(&rr->resrec.rdata->u.srv.target, r2->resrec.name) &&
2159 					(rr->ImmedAnswer == mDNSInterfaceMark || rr->ImmedAnswer == r2->resrec.InterfaceID))
2160 					r2->ImmedAdditional = r2->resrec.InterfaceID;		// ... then mark this address record for sending too
2161 		// We also make sure we send the DeviceInfo TXT record too, if necessary
2162 		// We check for RecordType == kDNSRecordTypeShared because we don't want to tag the
2163 		// DeviceInfo TXT record onto a goodbye packet (RecordType == kDNSRecordTypeDeregistering).
2164 		if (rr->ImmedAnswer && rr->resrec.RecordType == kDNSRecordTypeShared && rr->resrec.rrtype == kDNSType_PTR)
2165 			if (ResourceRecordIsValidAnswer(&m->DeviceInfo) && SameDomainLabel(rr->resrec.rdata->u.name.c, m->DeviceInfo.resrec.name->c))
2166 				{
2167 				if (!m->DeviceInfo.ImmedAnswer) m->DeviceInfo.ImmedAnswer = rr->ImmedAnswer;
2168 				else                            m->DeviceInfo.ImmedAnswer = mDNSInterfaceMark;
2169 				}
2170 		}
2171 
2172 	// If there's a record which is supposed to be unique that we're going to send, then make sure that we give
2173 	// the whole RRSet as an atomic unit. That means that if we have any other records with the same name/type/class
2174 	// then we need to mark them for sending too. Otherwise, if we set the kDNSClass_UniqueRRSet bit on a
2175 	// record, then other RRSet members that have not been sent recently will get flushed out of client caches.
2176 	// -- If a record is marked to be sent on a certain interface, make sure the whole set is marked to be sent on that interface
2177 	// -- If any record is marked to be sent on all interfaces, make sure the whole set is marked to be sent on all interfaces
2178 	for (rr = m->ResourceRecords; rr; rr=rr->next)
2179 		if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask)
2180 			{
2181 			if (rr->ImmedAnswer)			// If we're sending this as answer, see that its whole RRSet is similarly marked
2182 				{
2183 				for (r2 = m->ResourceRecords; r2; r2=r2->next)
2184 					if (ResourceRecordIsValidAnswer(r2))
2185 						if (r2->ImmedAnswer != mDNSInterfaceMark &&
2186 							r2->ImmedAnswer != rr->ImmedAnswer && SameResourceRecordSignature(r2, rr))
2187 							r2->ImmedAnswer = !r2->ImmedAnswer ? rr->ImmedAnswer : mDNSInterfaceMark;
2188 				}
2189 			else if (rr->ImmedAdditional)	// If we're sending this as additional, see that its whole RRSet is similarly marked
2190 				{
2191 				for (r2 = m->ResourceRecords; r2; r2=r2->next)
2192 					if (ResourceRecordIsValidAnswer(r2))
2193 						if (r2->ImmedAdditional != rr->ImmedAdditional && SameResourceRecordSignature(r2, rr))
2194 							r2->ImmedAdditional = rr->ImmedAdditional;
2195 				}
2196 			}
2197 
2198 	// Now set SendRNow state appropriately
2199 	for (rr = m->ResourceRecords; rr; rr=rr->next)
2200 		{
2201 		if (rr->ImmedAnswer == mDNSInterfaceMark)		// Sending this record on all appropriate interfaces
2202 			{
2203 			rr->SendRNow = !intf ? mDNSNULL : (rr->resrec.InterfaceID) ? rr->resrec.InterfaceID : intf->InterfaceID;
2204 			rr->ImmedAdditional = mDNSNULL;				// No need to send as additional if sending as answer
2205 			rr->LastMCTime      = m->timenow;
2206 			rr->LastMCInterface = rr->ImmedAnswer;
2207 			// If we're announcing this record, and it's at least half-way to its ordained time, then consider this announcement done
2208 			if (TimeToAnnounceThisRecord(rr, m->timenow + rr->ThisAPInterval/2))
2209 				{
2210 				rr->AnnounceCount--;
2211 				if (rr->resrec.RecordType != kDNSRecordTypeDeregistering)
2212 					rr->ThisAPInterval *= 2;
2213 				rr->LastAPTime = m->timenow;
2214 				debugf("Announcing %##s (%s) %d", rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype), rr->AnnounceCount);
2215 				}
2216 			}
2217 		else if (rr->ImmedAnswer)						// Else, just respond to a single query on single interface:
2218 			{
2219 			rr->SendRNow        = rr->ImmedAnswer;		// Just respond on that interface
2220 			rr->ImmedAdditional = mDNSNULL;				// No need to send as additional too
2221 			rr->LastMCTime      = m->timenow;
2222 			rr->LastMCInterface = rr->ImmedAnswer;
2223 			}
2224 		SetNextAnnounceProbeTime(m, rr);
2225 		//if (rr->SendRNow) LogMsg("%-15.4a %s", &rr->v4Requester, ARDisplayString(m, rr));
2226 		}
2227 
2228 	// ***
2229 	// *** 2. Loop through interface list, sending records as appropriate
2230 	// ***
2231 
2232 	while (intf)
2233 		{
2234 		const int OwnerRecordSpace = (m->AnnounceOwner && intf->MAC.l[0]) ? DNSOpt_Header_Space + DNSOpt_Owner_Space(&m->PrimaryMAC, &intf->MAC) : 0;
2235 		int numDereg    = 0;
2236 		int numAnnounce = 0;
2237 		int numAnswer   = 0;
2238 		mDNSu8 *responseptr = m->omsg.data;
2239 		mDNSu8 *newptr;
2240 		InitializeDNSMessage(&m->omsg.h, zeroID, ResponseFlags);
2241 
2242 		// First Pass. Look for:
2243 		// 1. Deregistering records that need to send their goodbye packet
2244 		// 2. Updated records that need to retract their old data
2245 		// 3. Answers and announcements we need to send
2246 		for (rr = m->ResourceRecords; rr; rr=rr->next)
2247 			{
2248 
2249 			// Skip this interface if the record InterfaceID is *Any and the record is not
2250 			// appropriate for the interface type.
2251 			if ((rr->SendRNow == intf->InterfaceID) &&
2252 				((rr->resrec.InterfaceID == mDNSInterface_Any) && !mDNSPlatformValidRecordForInterface(rr, intf)))
2253 				{
2254 					LogInfo("SendResponses: Not sending %s, on %s", ARDisplayString(m, rr), InterfaceNameForID(m, rr->SendRNow));
2255 					rr->SendRNow = GetNextActiveInterfaceID(intf);
2256 				}
2257 			else if (rr->SendRNow == intf->InterfaceID)
2258 				{
2259 				RData  *OldRData    = rr->resrec.rdata;
2260 				mDNSu16 oldrdlength = rr->resrec.rdlength;
2261 				mDNSu8 active = (mDNSu8)
2262 					(rr->resrec.RecordType != kDNSRecordTypeDeregistering &&
2263 					(m->SleepState != SleepState_Sleeping || intf->SPSAddr[0].type || intf->SPSAddr[1].type || intf->SPSAddr[2].type));
2264 				newptr = mDNSNULL;
2265 				if (rr->NewRData && active)
2266 					{
2267 					// See if we should send a courtesy "goodbye" for the old data before we replace it.
2268 					if (ResourceRecordIsValidAnswer(rr) && rr->resrec.RecordType == kDNSRecordTypeShared && rr->RequireGoodbye)
2269 						{
2270 						newptr = PutRR_OS_TTL(responseptr, &m->omsg.h.numAnswers, &rr->resrec, 0);
2271 						if (newptr) { responseptr = newptr; numDereg++; rr->RequireGoodbye = mDNSfalse; }
2272 						else continue; // If this packet is already too full to hold the goodbye for this record, skip it for now and we'll retry later
2273 						}
2274 					SetNewRData(&rr->resrec, rr->NewRData, rr->newrdlength);
2275 					}
2276 
2277 				if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask)
2278 					rr->resrec.rrclass |= kDNSClass_UniqueRRSet;		// Temporarily set the cache flush bit so PutResourceRecord will set it
2279 				newptr = PutRR_OS_TTL(responseptr, &m->omsg.h.numAnswers, &rr->resrec, active ? rr->resrec.rroriginalttl : 0);
2280 				rr->resrec.rrclass &= ~kDNSClass_UniqueRRSet;			// Make sure to clear cache flush bit back to normal state
2281 				if (newptr)
2282 					{
2283 					responseptr = newptr;
2284 					rr->RequireGoodbye = active;
2285 					if (rr->resrec.RecordType == kDNSRecordTypeDeregistering) numDereg++;
2286 					else if (rr->LastAPTime == m->timenow) numAnnounce++; else numAnswer++;
2287 					}
2288 
2289 				if (rr->NewRData && active)
2290 					SetNewRData(&rr->resrec, OldRData, oldrdlength);
2291 
2292 				// The first time through (pktcount==0), if this record is verified unique
2293 				// (i.e. typically A, AAAA, SRV, TXT and reverse-mapping PTR), set the flag to add an NSEC too.
2294 				if (!pktcount && active && (rr->resrec.RecordType & kDNSRecordTypeActiveUniqueMask) && !rr->SendNSECNow)
2295 					rr->SendNSECNow = mDNSInterfaceMark;
2296 
2297 				if (newptr)		// If succeeded in sending, advance to next interface
2298 					{
2299 					// If sending on all interfaces, go to next interface; else we're finished now
2300 					if (rr->ImmedAnswer == mDNSInterfaceMark && rr->resrec.InterfaceID == mDNSInterface_Any)
2301 						rr->SendRNow = GetNextActiveInterfaceID(intf);
2302 					else
2303 						rr->SendRNow = mDNSNULL;
2304 					}
2305 				}
2306 			}
2307 
2308 		// Second Pass. Add additional records, if there's space.
2309 		newptr = responseptr;
2310 		for (rr = m->ResourceRecords; rr; rr=rr->next)
2311 			if (rr->ImmedAdditional == intf->InterfaceID)
2312 				if (ResourceRecordIsValidAnswer(rr))
2313 					{
2314 					// If we have at least one answer already in the packet, then plan to add additionals too
2315 					mDNSBool SendAdditional = (m->omsg.h.numAnswers > 0);
2316 
2317 					// If we're not planning to send any additionals, but this record is a unique one, then
2318 					// make sure we haven't already sent any other members of its RRSet -- if we have, then they
2319 					// will have had the cache flush bit set, so now we need to finish the job and send the rest.
2320 					if (!SendAdditional && (rr->resrec.RecordType & kDNSRecordTypeUniqueMask))
2321 						{
2322 						const AuthRecord *a;
2323 						for (a = m->ResourceRecords; a; a=a->next)
2324 							if (a->LastMCTime      == m->timenow &&
2325 								a->LastMCInterface == intf->InterfaceID &&
2326 								SameResourceRecordSignature(a, rr)) { SendAdditional = mDNStrue; break; }
2327 						}
2328 					if (!SendAdditional)					// If we don't want to send this after all,
2329 						rr->ImmedAdditional = mDNSNULL;		// then cancel its ImmedAdditional field
2330 					else if (newptr)						// Else, try to add it if we can
2331 						{
2332 						// The first time through (pktcount==0), if this record is verified unique
2333 						// (i.e. typically A, AAAA, SRV, TXT and reverse-mapping PTR), set the flag to add an NSEC too.
2334 						if (!pktcount && (rr->resrec.RecordType & kDNSRecordTypeActiveUniqueMask) && !rr->SendNSECNow)
2335 							rr->SendNSECNow = mDNSInterfaceMark;
2336 
2337 						if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask)
2338 							rr->resrec.rrclass |= kDNSClass_UniqueRRSet;	// Temporarily set the cache flush bit so PutResourceRecord will set it
2339 						newptr = PutRR_OS(newptr, &m->omsg.h.numAdditionals, &rr->resrec);
2340 						rr->resrec.rrclass &= ~kDNSClass_UniqueRRSet;		// Make sure to clear cache flush bit back to normal state
2341 						if (newptr)
2342 							{
2343 							responseptr = newptr;
2344 							rr->ImmedAdditional = mDNSNULL;
2345 							rr->RequireGoodbye = mDNStrue;
2346 							// If we successfully put this additional record in the packet, we record LastMCTime & LastMCInterface.
2347 							// This matters particularly in the case where we have more than one IPv6 (or IPv4) address, because otherwise,
2348 							// when we see our own multicast with the cache flush bit set, if we haven't set LastMCTime, then we'll get
2349 							// all concerned and re-announce our record again to make sure it doesn't get flushed from peer caches.
2350 							rr->LastMCTime      = m->timenow;
2351 							rr->LastMCInterface = intf->InterfaceID;
2352 							}
2353 						}
2354 					}
2355 
2356 		// Third Pass. Add NSEC records, if there's space.
2357 		// When we're generating an NSEC record in response to a specify query for that type
2358 		// (recognized by rr->SendNSECNow == intf->InterfaceID) we should really put the NSEC in the Answer Section,
2359 		// not Additional Section, but for now it's easier to handle both cases in this Additional Section loop here.
2360 		for (rr = m->ResourceRecords; rr; rr=rr->next)
2361 			if (rr->SendNSECNow == mDNSInterfaceMark || rr->SendNSECNow == intf->InterfaceID)
2362 				{
2363 				AuthRecord nsec;
2364 				mDNS_SetupResourceRecord(&nsec, mDNSNULL, mDNSInterface_Any, kDNSType_NSEC, rr->resrec.rroriginalttl, kDNSRecordTypeUnique, AuthRecordAny, mDNSNULL, mDNSNULL);
2365 				nsec.resrec.rrclass |= kDNSClass_UniqueRRSet;
2366 				AssignDomainName(&nsec.namestorage, rr->resrec.name);
2367 				mDNSPlatformMemZero(nsec.rdatastorage.u.nsec.bitmap, sizeof(nsec.rdatastorage.u.nsec.bitmap));
2368 				for (r2 = m->ResourceRecords; r2; r2=r2->next)
2369 					if (ResourceRecordIsValidAnswer(r2) && SameResourceRecordNameClassInterface(r2, rr))
2370 						{
2371 						if (r2->resrec.rrtype >= kDNSQType_ANY) { LogMsg("Can't create NSEC for record %s", ARDisplayString(m, r2)); break; }
2372 						else nsec.rdatastorage.u.nsec.bitmap[r2->resrec.rrtype >> 3] |= 128 >> (r2->resrec.rrtype & 7);
2373 						}
2374 				newptr = responseptr;
2375 				if (!r2)	// If we successfully built our NSEC record, add it to the packet now
2376 					{
2377 					newptr = PutRR_OS(responseptr, &m->omsg.h.numAdditionals, &nsec.resrec);
2378 					if (newptr) responseptr = newptr;
2379 					}
2380 
2381 				// If we successfully put the NSEC record, clear the SendNSECNow flag
2382 				// If we consider this NSEC optional, then we unconditionally clear the SendNSECNow flag, even if we fail to put this additional record
2383 				if (newptr || rr->SendNSECNow == mDNSInterfaceMark)
2384 					{
2385 					rr->SendNSECNow = mDNSNULL;
2386 					// Run through remainder of list clearing SendNSECNow flag for all other records which would generate the same NSEC
2387 					for (r2 = rr->next; r2; r2=r2->next)
2388 						if (SameResourceRecordNameClassInterface(r2, rr))
2389 							if (r2->SendNSECNow == mDNSInterfaceMark || r2->SendNSECNow == intf->InterfaceID)
2390 								r2->SendNSECNow = mDNSNULL;
2391 					}
2392 				}
2393 
2394 		if (m->omsg.h.numAnswers || m->omsg.h.numAdditionals)
2395 			{
2396 			// If we have data to send, add OWNER option if necessary, then send packet
2397 
2398 			if (OwnerRecordSpace)
2399 				{
2400 				AuthRecord opt;
2401 				mDNS_SetupResourceRecord(&opt, mDNSNULL, mDNSInterface_Any, kDNSType_OPT, kStandardTTL, kDNSRecordTypeKnownUnique, AuthRecordAny, mDNSNULL, mDNSNULL);
2402 				opt.resrec.rrclass    = NormalMaxDNSMessageData;
2403 				opt.resrec.rdlength   = sizeof(rdataOPT);	// One option in this OPT record
2404 				opt.resrec.rdestimate = sizeof(rdataOPT);
2405 				SetupOwnerOpt(m, intf, &opt.resrec.rdata->u.opt[0]);
2406 				newptr = PutResourceRecord(&m->omsg, responseptr, &m->omsg.h.numAdditionals, &opt.resrec);
2407 				if (newptr) { responseptr = newptr; LogSPS("SendResponses put   %s", ARDisplayString(m, &opt)); }
2408 				else if (m->omsg.h.numAnswers + m->omsg.h.numAuthorities + m->omsg.h.numAdditionals == 1)
2409 					LogSPS("SendResponses: No space in packet for Owner OPT record (%d/%d/%d/%d) %s",
2410 						m->omsg.h.numQuestions, m->omsg.h.numAnswers, m->omsg.h.numAuthorities, m->omsg.h.numAdditionals, ARDisplayString(m, &opt));
2411 				else
2412 					LogMsg("SendResponses: How did we fail to have space for Owner OPT record (%d/%d/%d/%d) %s",
2413 						m->omsg.h.numQuestions, m->omsg.h.numAnswers, m->omsg.h.numAuthorities, m->omsg.h.numAdditionals, ARDisplayString(m, &opt));
2414 				}
2415 
2416 			debugf("SendResponses: Sending %d Deregistration%s, %d Announcement%s, %d Answer%s, %d Additional%s on %p",
2417 				numDereg,                 numDereg                 == 1 ? "" : "s",
2418 				numAnnounce,              numAnnounce              == 1 ? "" : "s",
2419 				numAnswer,                numAnswer                == 1 ? "" : "s",
2420 				m->omsg.h.numAdditionals, m->omsg.h.numAdditionals == 1 ? "" : "s", intf->InterfaceID);
2421 
2422 			if (intf->IPv4Available) mDNSSendDNSMessage(m, &m->omsg, responseptr, intf->InterfaceID, mDNSNULL, &AllDNSLinkGroup_v4, MulticastDNSPort, mDNSNULL, mDNSNULL);
2423 			if (intf->IPv6Available) mDNSSendDNSMessage(m, &m->omsg, responseptr, intf->InterfaceID, mDNSNULL, &AllDNSLinkGroup_v6, MulticastDNSPort, mDNSNULL, mDNSNULL);
2424 			if (!m->SuppressSending) m->SuppressSending = NonZeroTime(m->timenow + (mDNSPlatformOneSecond+9)/10);
2425 			if (++pktcount >= 1000) { LogMsg("SendResponses exceeded loop limit %d: giving up", pktcount); break; }
2426 			// There might be more things to send on this interface, so go around one more time and try again.
2427 			}
2428 		else	// Nothing more to send on this interface; go to next
2429 			{
2430 			const NetworkInterfaceInfo *next = GetFirstActiveInterface(intf->next);
2431 			#if MDNS_DEBUGMSGS && 0
2432 			const char *const msg = next ? "SendResponses: Nothing more on %p; moving to %p" : "SendResponses: Nothing more on %p";
2433 			debugf(msg, intf, next);
2434 			#endif
2435 			intf = next;
2436 			pktcount = 0;		// When we move to a new interface, reset packet count back to zero -- NSEC generation logic uses it
2437 			}
2438 		}
2439 
2440 	// ***
2441 	// *** 3. Cleanup: Now that everything is sent, call client callback functions, and reset state variables
2442 	// ***
2443 
2444 	if (m->CurrentRecord)
2445 		LogMsg("SendResponses ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord));
2446 	m->CurrentRecord = m->ResourceRecords;
2447 	while (m->CurrentRecord)
2448 		{
2449 		rr = m->CurrentRecord;
2450 		m->CurrentRecord = rr->next;
2451 
2452 		if (rr->SendRNow)
2453 			{
2454 			if (rr->ARType != AuthRecordLocalOnly && rr->ARType != AuthRecordP2P)
2455 				LogMsg("SendResponses: No active interface %p to send: %p %02X %s", rr->SendRNow, rr->resrec.InterfaceID, rr->resrec.RecordType, ARDisplayString(m, rr));
2456 			rr->SendRNow = mDNSNULL;
2457 			}
2458 
2459 		if (rr->ImmedAnswer || rr->resrec.RecordType == kDNSRecordTypeDeregistering)
2460 			{
2461 			if (rr->NewRData) CompleteRDataUpdate(m, rr);	// Update our rdata, clear the NewRData pointer, and return memory to the client
2462 
2463 			if (rr->resrec.RecordType == kDNSRecordTypeDeregistering && rr->AnnounceCount == 0)
2464 				{
2465 				// For Unicast, when we get the response from the server, we will call CompleteDeregistration
2466 				if (!AuthRecord_uDNS(rr)) CompleteDeregistration(m, rr);		// Don't touch rr after this
2467 				}
2468 			else
2469 				{
2470 				rr->ImmedAnswer  = mDNSNULL;
2471 				rr->ImmedUnicast = mDNSfalse;
2472 				rr->v4Requester  = zerov4Addr;
2473 				rr->v6Requester  = zerov6Addr;
2474 				}
2475 			}
2476 		}
2477 	verbosedebugf("SendResponses: Next in %ld ticks", m->NextScheduledResponse - m->timenow);
2478 	}
2479 
2480 // Calling CheckCacheExpiration() is an expensive operation because it has to look at the entire cache,
2481 // so we want to be lazy about how frequently we do it.
2482 // 1. If a cache record is currently referenced by *no* active questions,
2483 //    then we don't mind expiring it up to a minute late (who will know?)
2484 // 2. Else, if a cache record is due for some of its final expiration queries,
2485 //    we'll allow them to be late by up to 2% of the TTL
2486 // 3. Else, if a cache record has completed all its final expiration queries without success,
2487 //    and is expiring, and had an original TTL more than ten seconds, we'll allow it to be one second late
2488 // 4. Else, it is expiring and had an original TTL of ten seconds or less (includes explicit goodbye packets),
2489 //    so allow at most 1/10 second lateness
2490 // 5. For records with rroriginalttl set to zero, that means we really want to delete them immediately
2491 //    (we have a new record with DelayDelivery set, waiting for the old record to go away before we can notify clients).
2492 #define CacheCheckGracePeriod(RR) (                                                   \
2493 	((RR)->CRActiveQuestion == mDNSNULL            ) ? (60 * mDNSPlatformOneSecond) : \
2494 	((RR)->UnansweredQueries < MaxUnansweredQueries) ? (TicksTTL(rr)/50)            : \
2495 	((RR)->resrec.rroriginalttl > 10               ) ? (mDNSPlatformOneSecond)      : \
2496 	((RR)->resrec.rroriginalttl > 0                ) ? (mDNSPlatformOneSecond/10)   : 0)
2497 
2498 #define NextCacheCheckEvent(RR) ((RR)->NextRequiredQuery + CacheCheckGracePeriod(RR))
2499 
ScheduleNextCacheCheckTime(mDNS * const m,const mDNSu32 slot,const mDNSs32 event)2500 mDNSexport void ScheduleNextCacheCheckTime(mDNS *const m, const mDNSu32 slot, const mDNSs32 event)
2501 	{
2502 	if (m->rrcache_nextcheck[slot] - event > 0)
2503 		m->rrcache_nextcheck[slot] = event;
2504 	if (m->NextCacheCheck          - event > 0)
2505 		m->NextCacheCheck          = event;
2506 	}
2507 
2508 // Note: MUST call SetNextCacheCheckTimeForRecord any time we change:
2509 // rr->TimeRcvd
2510 // rr->resrec.rroriginalttl
2511 // rr->UnansweredQueries
2512 // rr->CRActiveQuestion
SetNextCacheCheckTimeForRecord(mDNS * const m,CacheRecord * const rr)2513 mDNSlocal void SetNextCacheCheckTimeForRecord(mDNS *const m, CacheRecord *const rr)
2514 	{
2515 	rr->NextRequiredQuery = RRExpireTime(rr);
2516 
2517 	// If we have an active question, then see if we want to schedule a refresher query for this record.
2518 	// Usually we expect to do four queries, at 80-82%, 85-87%, 90-92% and then 95-97% of the TTL.
2519 	if (rr->CRActiveQuestion && rr->UnansweredQueries < MaxUnansweredQueries)
2520 		{
2521 		rr->NextRequiredQuery -= TicksTTL(rr)/20 * (MaxUnansweredQueries - rr->UnansweredQueries);
2522 		rr->NextRequiredQuery += mDNSRandom((mDNSu32)TicksTTL(rr)/50);
2523 		verbosedebugf("SetNextCacheCheckTimeForRecord: NextRequiredQuery in %ld sec CacheCheckGracePeriod %d ticks for %s",
2524 			(rr->NextRequiredQuery - m->timenow) / mDNSPlatformOneSecond, CacheCheckGracePeriod(rr), CRDisplayString(m,rr));
2525 		}
2526 
2527 	ScheduleNextCacheCheckTime(m, HashSlot(rr->resrec.name), NextCacheCheckEvent(rr));
2528 	}
2529 
2530 #define kMinimumReconfirmTime                     ((mDNSu32)mDNSPlatformOneSecond *  5)
2531 #define kDefaultReconfirmTimeForWake              ((mDNSu32)mDNSPlatformOneSecond *  5)
2532 #define kDefaultReconfirmTimeForNoAnswer          ((mDNSu32)mDNSPlatformOneSecond *  5)
2533 #define kDefaultReconfirmTimeForFlappingInterface ((mDNSu32)mDNSPlatformOneSecond * 30)
2534 
mDNS_Reconfirm_internal(mDNS * const m,CacheRecord * const rr,mDNSu32 interval)2535 mDNSlocal mStatus mDNS_Reconfirm_internal(mDNS *const m, CacheRecord *const rr, mDNSu32 interval)
2536 	{
2537 	if (interval < kMinimumReconfirmTime)
2538 		interval = kMinimumReconfirmTime;
2539 	if (interval > 0x10000000)	// Make sure interval doesn't overflow when we multiply by four below
2540 		interval = 0x10000000;
2541 
2542 	// If the expected expiration time for this record is more than interval+33%, then accelerate its expiration
2543 	if (RRExpireTime(rr) - m->timenow > (mDNSs32)((interval * 4) / 3))
2544 		{
2545 		// Add a 33% random amount to the interval, to avoid synchronization between multiple hosts
2546 		// For all the reconfirmations in a given batch, we want to use the same random value
2547 		// so that the reconfirmation questions can be grouped into a single query packet
2548 		if (!m->RandomReconfirmDelay) m->RandomReconfirmDelay = 1 + mDNSRandom(0x3FFFFFFF);
2549 		interval += m->RandomReconfirmDelay % ((interval/3) + 1);
2550 		rr->TimeRcvd          = m->timenow - (mDNSs32)interval * 3;
2551 		rr->resrec.rroriginalttl     = (interval * 4 + mDNSPlatformOneSecond - 1) / mDNSPlatformOneSecond;
2552 		SetNextCacheCheckTimeForRecord(m, rr);
2553 		}
2554 	debugf("mDNS_Reconfirm_internal:%6ld ticks to go for %s %p",
2555 		RRExpireTime(rr) - m->timenow, CRDisplayString(m, rr), rr->CRActiveQuestion);
2556 	return(mStatus_NoError);
2557 	}
2558 
2559 #define MaxQuestionInterval         (3600 * mDNSPlatformOneSecond)
2560 
2561 // BuildQuestion puts a question into a DNS Query packet and if successful, updates the value of queryptr.
2562 // It also appends to the list of known answer records that need to be included,
2563 // and updates the forcast for the size of the known answer section.
BuildQuestion(mDNS * const m,DNSMessage * query,mDNSu8 ** queryptr,DNSQuestion * q,CacheRecord *** kalistptrptr,mDNSu32 * answerforecast)2564 mDNSlocal mDNSBool BuildQuestion(mDNS *const m, DNSMessage *query, mDNSu8 **queryptr, DNSQuestion *q,
2565 	CacheRecord ***kalistptrptr, mDNSu32 *answerforecast)
2566 	{
2567 	mDNSBool ucast = (q->LargeAnswers || q->RequestUnicast) && m->CanReceiveUnicastOn5353;
2568 	mDNSu16 ucbit = (mDNSu16)(ucast ? kDNSQClass_UnicastResponse : 0);
2569 	const mDNSu8 *const limit = query->data + NormalMaxDNSMessageData;
2570 	mDNSu8 *newptr = putQuestion(query, *queryptr, limit - *answerforecast, &q->qname, q->qtype, (mDNSu16)(q->qclass | ucbit));
2571 	if (!newptr)
2572 		{
2573 		debugf("BuildQuestion: No more space in this packet for question %##s (%s)", q->qname.c, DNSTypeName(q->qtype));
2574 		return(mDNSfalse);
2575 		}
2576 	else
2577 		{
2578 		mDNSu32 forecast = *answerforecast;
2579 		const mDNSu32 slot = HashSlot(&q->qname);
2580 		const CacheGroup *const cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname);
2581 		CacheRecord *rr;
2582 		CacheRecord **ka = *kalistptrptr;	// Make a working copy of the pointer we're going to update
2583 
2584 		for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next)				// If we have a resource record in our cache,
2585 			if (rr->resrec.InterfaceID == q->SendQNow &&					// received on this interface
2586 				!(rr->resrec.RecordType & kDNSRecordTypeUniqueMask) &&		// which is a shared (i.e. not unique) record type
2587 				rr->NextInKAList == mDNSNULL && ka != &rr->NextInKAList &&	// which is not already in the known answer list
2588 				rr->resrec.rdlength <= SmallRecordLimit &&					// which is small enough to sensibly fit in the packet
2589 				SameNameRecordAnswersQuestion(&rr->resrec, q) &&			// which answers our question
2590 				rr->TimeRcvd + TicksTTL(rr)/2 - m->timenow >				// and its half-way-to-expiry time is at least 1 second away
2591 												mDNSPlatformOneSecond)		// (also ensures we never include goodbye records with TTL=1)
2592 				{
2593 				// We don't want to include unique records in the Known Answer section. The Known Answer section
2594 				// is intended to suppress floods of shared-record replies from many other devices on the network.
2595 				// That concept really does not apply to unique records, and indeed if we do send a query for
2596 				// which we have a unique record already in our cache, then including that unique record as a
2597 				// Known Answer, so as to suppress the only answer we were expecting to get, makes little sense.
2598 
2599 				*ka = rr;	// Link this record into our known answer chain
2600 				ka = &rr->NextInKAList;
2601 				// We forecast: compressed name (2) type (2) class (2) TTL (4) rdlength (2) rdata (n)
2602 				forecast += 12 + rr->resrec.rdestimate;
2603 				// If we're trying to put more than one question in this packet, and it doesn't fit
2604 				// then undo that last question and try again next time
2605 				if (query->h.numQuestions > 1 && newptr + forecast >= limit)
2606 					{
2607 					debugf("BuildQuestion: Retracting question %##s (%s) new forecast total %d",
2608 						q->qname.c, DNSTypeName(q->qtype), newptr + forecast - query->data);
2609 					query->h.numQuestions--;
2610 					ka = *kalistptrptr;		// Go back to where we started and retract these answer records
2611 					while (*ka) { CacheRecord *c = *ka; *ka = mDNSNULL; ka = &c->NextInKAList; }
2612 					return(mDNSfalse);		// Return false, so we'll try again in the next packet
2613 					}
2614 				}
2615 
2616 		// Success! Update our state pointers, increment UnansweredQueries as appropriate, and return
2617 		*queryptr        = newptr;				// Update the packet pointer
2618 		*answerforecast  = forecast;			// Update the forecast
2619 		*kalistptrptr    = ka;					// Update the known answer list pointer
2620 		if (ucast) q->ExpectUnicastResp = NonZeroTime(m->timenow);
2621 
2622 		for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next)				// For every resource record in our cache,
2623 			if (rr->resrec.InterfaceID == q->SendQNow &&					// received on this interface
2624 				rr->NextInKAList == mDNSNULL && ka != &rr->NextInKAList &&	// which is not in the known answer list
2625 				SameNameRecordAnswersQuestion(&rr->resrec, q))				// which answers our question
2626 					{
2627 					rr->UnansweredQueries++;								// indicate that we're expecting a response
2628 					rr->LastUnansweredTime = m->timenow;
2629 					SetNextCacheCheckTimeForRecord(m, rr);
2630 					}
2631 
2632 		return(mDNStrue);
2633 		}
2634 	}
2635 
2636 // When we have a query looking for a specified name, but there appear to be no answers with
2637 // that name, ReconfirmAntecedents() is called with depth=0 to start the reconfirmation process
2638 // for any records in our cache that reference the given name (e.g. PTR and SRV records).
2639 // For any such cache record we find, we also recursively call ReconfirmAntecedents() for *its* name.
2640 // We increment depth each time we recurse, to guard against possible infinite loops, with a limit of 5.
2641 // A typical reconfirmation scenario might go like this:
2642 // Depth 0: Name "myhost.local" has no address records
2643 // Depth 1: SRV "My Service._example._tcp.local." refers to "myhost.local"; may be stale
2644 // Depth 2: PTR "_example._tcp.local." refers to "My Service"; may be stale
2645 // Depth 3: PTR "_services._dns-sd._udp.local." refers to "_example._tcp.local."; may be stale
2646 // Currently depths 4 and 5 are not expected to occur; if we did get to depth 5 we'd reconfim any records we
2647 // found referring to the given name, but not recursively descend any further reconfirm *their* antecedents.
ReconfirmAntecedents(mDNS * const m,const domainname * const name,const mDNSu32 namehash,const int depth)2648 mDNSlocal void ReconfirmAntecedents(mDNS *const m, const domainname *const name, const mDNSu32 namehash, const int depth)
2649 	{
2650 	mDNSu32 slot;
2651 	CacheGroup *cg;
2652 	CacheRecord *cr;
2653 	debugf("ReconfirmAntecedents (depth=%d) for %##s", depth, name->c);
2654 	FORALL_CACHERECORDS(slot, cg, cr)
2655 		{
2656 		domainname *crtarget = GetRRDomainNameTarget(&cr->resrec);
2657 		if (crtarget && cr->resrec.rdatahash == namehash && SameDomainName(crtarget, name))
2658 			{
2659 			LogInfo("ReconfirmAntecedents: Reconfirming (depth=%d) %s", depth, CRDisplayString(m, cr));
2660 			mDNS_Reconfirm_internal(m, cr, kDefaultReconfirmTimeForNoAnswer);
2661 			if (depth < 5) ReconfirmAntecedents(m, cr->resrec.name, cr->resrec.namehash, depth+1);
2662 			}
2663 		}
2664 	}
2665 
2666 // If we get no answer for a AAAA query, then before doing an automatic implicit ReconfirmAntecedents
2667 // we check if we have an address record for the same name. If we do have an IPv4 address for a given
2668 // name but not an IPv6 address, that's okay (it just means the device doesn't do IPv6) so the failure
2669 // to get a AAAA response is not grounds to doubt the PTR/SRV chain that lead us to that name.
CacheHasAddressTypeForName(mDNS * const m,const domainname * const name,const mDNSu32 namehash)2670 mDNSlocal const CacheRecord *CacheHasAddressTypeForName(mDNS *const m, const domainname *const name, const mDNSu32 namehash)
2671 	{
2672 	CacheGroup *const cg = CacheGroupForName(m, HashSlot(name), namehash, name);
2673 	const CacheRecord *cr = cg ? cg->members : mDNSNULL;
2674 	while (cr && !RRTypeIsAddressType(cr->resrec.rrtype)) cr=cr->next;
2675 	return(cr);
2676 	}
2677 
FindSPSInCache1(mDNS * const m,const DNSQuestion * const q,const CacheRecord * const c0,const CacheRecord * const c1)2678 mDNSlocal const CacheRecord *FindSPSInCache1(mDNS *const m, const DNSQuestion *const q, const CacheRecord *const c0, const CacheRecord *const c1)
2679 	{
2680 	CacheGroup *const cg = CacheGroupForName(m, HashSlot(&q->qname), q->qnamehash, &q->qname);
2681 	const CacheRecord *cr, *bestcr = mDNSNULL;
2682 	mDNSu32 bestmetric = 1000000;
2683 	for (cr = cg ? cg->members : mDNSNULL; cr; cr=cr->next)
2684 		if (cr->resrec.rrtype == kDNSType_PTR && cr->resrec.rdlength >= 6)						// If record is PTR type, with long enough name,
2685 			if (cr != c0 && cr != c1)															// that's not one we've seen before,
2686 				if (SameNameRecordAnswersQuestion(&cr->resrec, q))								// and answers our browse query,
2687 					if (!IdenticalSameNameRecord(&cr->resrec, &m->SPSRecords.RR_PTR.resrec))	// and is not our own advertised service...
2688 						{
2689 						mDNSu32 metric = SPSMetric(cr->resrec.rdata->u.name.c);
2690 						if (bestmetric > metric) { bestmetric = metric; bestcr = cr; }
2691 						}
2692 	return(bestcr);
2693 	}
2694 
2695 // Finds the three best Sleep Proxies we currently have in our cache
FindSPSInCache(mDNS * const m,const DNSQuestion * const q,const CacheRecord * sps[3])2696 mDNSexport void FindSPSInCache(mDNS *const m, const DNSQuestion *const q, const CacheRecord *sps[3])
2697 	{
2698 	sps[0] =                      FindSPSInCache1(m, q, mDNSNULL, mDNSNULL);
2699 	sps[1] = !sps[0] ? mDNSNULL : FindSPSInCache1(m, q, sps[0],   mDNSNULL);
2700 	sps[2] = !sps[1] ? mDNSNULL : FindSPSInCache1(m, q, sps[0],   sps[1]);
2701 	}
2702 
2703 // Only DupSuppressInfos newer than the specified 'time' are allowed to remain active
ExpireDupSuppressInfo(DupSuppressInfo ds[DupSuppressInfoSize],mDNSs32 time)2704 mDNSlocal void ExpireDupSuppressInfo(DupSuppressInfo ds[DupSuppressInfoSize], mDNSs32 time)
2705 	{
2706 	int i;
2707 	for (i=0; i<DupSuppressInfoSize; i++) if (ds[i].Time - time < 0) ds[i].InterfaceID = mDNSNULL;
2708 	}
2709 
ExpireDupSuppressInfoOnInterface(DupSuppressInfo ds[DupSuppressInfoSize],mDNSs32 time,mDNSInterfaceID InterfaceID)2710 mDNSlocal void ExpireDupSuppressInfoOnInterface(DupSuppressInfo ds[DupSuppressInfoSize], mDNSs32 time, mDNSInterfaceID InterfaceID)
2711 	{
2712 	int i;
2713 	for (i=0; i<DupSuppressInfoSize; i++) if (ds[i].InterfaceID == InterfaceID && ds[i].Time - time < 0) ds[i].InterfaceID = mDNSNULL;
2714 	}
2715 
SuppressOnThisInterface(const DupSuppressInfo ds[DupSuppressInfoSize],const NetworkInterfaceInfo * const intf)2716 mDNSlocal mDNSBool SuppressOnThisInterface(const DupSuppressInfo ds[DupSuppressInfoSize], const NetworkInterfaceInfo * const intf)
2717 	{
2718 	int i;
2719 	mDNSBool v4 = !intf->IPv4Available;		// If this interface doesn't do v4, we don't need to find a v4 duplicate of this query
2720 	mDNSBool v6 = !intf->IPv6Available;		// If this interface doesn't do v6, we don't need to find a v6 duplicate of this query
2721 	for (i=0; i<DupSuppressInfoSize; i++)
2722 		if (ds[i].InterfaceID == intf->InterfaceID)
2723 			{
2724 			if      (ds[i].Type == mDNSAddrType_IPv4) v4 = mDNStrue;
2725 			else if (ds[i].Type == mDNSAddrType_IPv6) v6 = mDNStrue;
2726 			if (v4 && v6) return(mDNStrue);
2727 			}
2728 	return(mDNSfalse);
2729 	}
2730 
RecordDupSuppressInfo(DupSuppressInfo ds[DupSuppressInfoSize],mDNSs32 Time,mDNSInterfaceID InterfaceID,mDNSs32 Type)2731 mDNSlocal int RecordDupSuppressInfo(DupSuppressInfo ds[DupSuppressInfoSize], mDNSs32 Time, mDNSInterfaceID InterfaceID, mDNSs32 Type)
2732 	{
2733 	int i, j;
2734 
2735 	// See if we have this one in our list somewhere already
2736 	for (i=0; i<DupSuppressInfoSize; i++) if (ds[i].InterfaceID == InterfaceID && ds[i].Type == Type) break;
2737 
2738 	// If not, find a slot we can re-use
2739 	if (i >= DupSuppressInfoSize)
2740 		{
2741 		i = 0;
2742 		for (j=1; j<DupSuppressInfoSize && ds[i].InterfaceID; j++)
2743 			if (!ds[j].InterfaceID || ds[j].Time - ds[i].Time < 0)
2744 				i = j;
2745 		}
2746 
2747 	// Record the info about this query we saw
2748 	ds[i].Time        = Time;
2749 	ds[i].InterfaceID = InterfaceID;
2750 	ds[i].Type        = Type;
2751 
2752 	return(i);
2753 	}
2754 
mDNSSendWakeOnResolve(mDNS * const m,DNSQuestion * q)2755 mDNSlocal void mDNSSendWakeOnResolve(mDNS *const m, DNSQuestion *q)
2756 	{
2757 	int len, i, cnt;
2758 	mDNSInterfaceID InterfaceID = q->InterfaceID;
2759 	domainname *d = &q->qname;
2760 
2761 	// We can't send magic packets without knowing which interface to send it on.
2762 	if (InterfaceID == mDNSInterface_Any || InterfaceID == mDNSInterface_LocalOnly || InterfaceID == mDNSInterface_P2P)
2763 		{
2764 		LogMsg("mDNSSendWakeOnResolve: ERROR!! Invalid InterfaceID %p for question %##s", InterfaceID, q->qname.c);
2765 		return;
2766 		}
2767 
2768 	// Split MAC@IPAddress and pass them separately
2769 	len = d->c[0];
2770 	i = 1;
2771 	cnt = 0;
2772 	for (i = 1; i < len; i++)
2773 		{
2774 		if (d->c[i] == '@')
2775 			{
2776 			char EthAddr[18];	// ethernet adddress : 12 bytes + 5 ":" + 1 NULL byte
2777 			char IPAddr[47];    // Max IP address len: 46 bytes (IPv6) + 1 NULL byte
2778 			if (cnt != 5)
2779 				{
2780 				LogMsg("mDNSSendWakeOnResolve: ERROR!! Malformed Ethernet address %##s, cnt %d", q->qname.c, cnt);
2781 				return;
2782 				}
2783 			if ((i - 1) > (int) (sizeof(EthAddr) - 1))
2784 				{
2785 				LogMsg("mDNSSendWakeOnResolve: ERROR!! Malformed Ethernet address %##s, length %d", q->qname.c, i - 1);
2786 				return;
2787 				}
2788 			if ((len - i) > (int)(sizeof(IPAddr) - 1))
2789 				{
2790 				LogMsg("mDNSSendWakeOnResolve: ERROR!! Malformed IP address %##s, length %d", q->qname.c, len - i);
2791 				return;
2792 				}
2793 			mDNSPlatformMemCopy(EthAddr, &d->c[1], i - 1);
2794 			EthAddr[i - 1] = 0;
2795 			mDNSPlatformMemCopy(IPAddr, &d->c[i + 1], len - i);
2796 			IPAddr[len - i] = 0;
2797 			mDNSPlatformSendWakeupPacket(m, InterfaceID, EthAddr, IPAddr, InitialWakeOnResolveCount - q->WakeOnResolveCount);
2798 			return;
2799 			}
2800 		else if (d->c[i] == ':')
2801 			cnt++;
2802 		}
2803 	LogMsg("mDNSSendWakeOnResolve: ERROR!! Malformed WakeOnResolve name %##s", q->qname.c);
2804 	}
2805 
2806 
AccelerateThisQuery(mDNS * const m,DNSQuestion * q)2807 mDNSlocal mDNSBool AccelerateThisQuery(mDNS *const m, DNSQuestion *q)
2808 	{
2809 	// If more than 90% of the way to the query time, we should unconditionally accelerate it
2810 	if (TimeToSendThisQuestion(q, m->timenow + q->ThisQInterval/10))
2811 		return(mDNStrue);
2812 
2813 	// If half-way to next scheduled query time, only accelerate if it will add less than 512 bytes to the packet
2814 	if (TimeToSendThisQuestion(q, m->timenow + q->ThisQInterval/2))
2815 		{
2816 		// We forecast: qname (n) type (2) class (2)
2817 		mDNSu32 forecast = (mDNSu32)DomainNameLength(&q->qname) + 4;
2818 		const mDNSu32 slot = HashSlot(&q->qname);
2819 		const CacheGroup *const cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname);
2820 		const CacheRecord *rr;
2821 		for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next)				// If we have a resource record in our cache,
2822 			if (rr->resrec.rdlength <= SmallRecordLimit &&					// which is small enough to sensibly fit in the packet
2823 				SameNameRecordAnswersQuestion(&rr->resrec, q) &&			// which answers our question
2824 				rr->TimeRcvd + TicksTTL(rr)/2 - m->timenow >= 0 &&			// and it is less than half-way to expiry
2825 				rr->NextRequiredQuery - (m->timenow + q->ThisQInterval) > 0)// and we'll ask at least once again before NextRequiredQuery
2826 				{
2827 				// We forecast: compressed name (2) type (2) class (2) TTL (4) rdlength (2) rdata (n)
2828 				forecast += 12 + rr->resrec.rdestimate;
2829 				if (forecast >= 512) return(mDNSfalse);	// If this would add 512 bytes or more to the packet, don't accelerate
2830 				}
2831 		return(mDNStrue);
2832 		}
2833 
2834 	return(mDNSfalse);
2835 	}
2836 
2837 // How Standard Queries are generated:
2838 // 1. The Question Section contains the question
2839 // 2. The Additional Section contains answers we already know, to suppress duplicate responses
2840 
2841 // How Probe Queries are generated:
2842 // 1. The Question Section contains queries for the name we intend to use, with QType=ANY because
2843 // if some other host is already using *any* records with this name, we want to know about it.
2844 // 2. The Authority Section contains the proposed values we intend to use for one or more
2845 // of our records with that name (analogous to the Update section of DNS Update packets)
2846 // because if some other host is probing at the same time, we each want to know what the other is
2847 // planning, in order to apply the tie-breaking rule to see who gets to use the name and who doesn't.
2848 
SendQueries(mDNS * const m)2849 mDNSlocal void SendQueries(mDNS *const m)
2850 	{
2851 	mDNSu32 slot;
2852 	CacheGroup *cg;
2853 	CacheRecord *cr;
2854 	AuthRecord *ar;
2855 	int pktcount = 0;
2856 	DNSQuestion *q;
2857 	// For explanation of maxExistingQuestionInterval logic, see comments for maxExistingAnnounceInterval
2858 	mDNSs32 maxExistingQuestionInterval = 0;
2859 	const NetworkInterfaceInfo *intf = GetFirstActiveInterface(m->HostInterfaces);
2860 	CacheRecord *KnownAnswerList = mDNSNULL;
2861 
2862 	// 1. If time for a query, work out what we need to do
2863 
2864 	// We're expecting to send a query anyway, so see if any expiring cache records are close enough
2865 	// to their NextRequiredQuery to be worth batching them together with this one
2866 	FORALL_CACHERECORDS(slot, cg, cr)
2867 		if (cr->CRActiveQuestion && cr->UnansweredQueries < MaxUnansweredQueries)
2868 			if (m->timenow + TicksTTL(cr)/50 - cr->NextRequiredQuery >= 0)
2869 				{
2870 				debugf("Sending %d%% cache expiration query for %s", 80 + 5 * cr->UnansweredQueries, CRDisplayString(m, cr));
2871 				q = cr->CRActiveQuestion;
2872 				ExpireDupSuppressInfoOnInterface(q->DupSuppress, m->timenow - TicksTTL(cr)/20, cr->resrec.InterfaceID);
2873 				// For uDNS queries (TargetQID non-zero) we adjust LastQTime,
2874 				// and bump UnansweredQueries so that we don't spin trying to send the same cache expiration query repeatedly
2875 				if      (q->Target.type)                        q->SendQNow = mDNSInterfaceMark;	// If targeted query, mark it
2876 				else if (!mDNSOpaque16IsZero(q->TargetQID))     { q->LastQTime = m->timenow - q->ThisQInterval; cr->UnansweredQueries++; }
2877 				else if (q->SendQNow == mDNSNULL)               q->SendQNow = cr->resrec.InterfaceID;
2878 				else if (q->SendQNow != cr->resrec.InterfaceID) q->SendQNow = mDNSInterfaceMark;
2879 				}
2880 
2881 	// Scan our list of questions to see which:
2882 	//     *WideArea*  queries need to be sent
2883 	//     *unicast*   queries need to be sent
2884 	//     *multicast* queries we're definitely going to send
2885 	if (m->CurrentQuestion)
2886 		LogMsg("SendQueries ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
2887 	m->CurrentQuestion = m->Questions;
2888 	while (m->CurrentQuestion && m->CurrentQuestion != m->NewQuestions)
2889 		{
2890 		q = m->CurrentQuestion;
2891 		if (q->Target.type && (q->SendQNow || TimeToSendThisQuestion(q, m->timenow)))
2892 			{
2893 			mDNSu8       *qptr        = m->omsg.data;
2894 			const mDNSu8 *const limit = m->omsg.data + sizeof(m->omsg.data);
2895 
2896 			// If we fail to get a new on-demand socket (should only happen cases of the most extreme resource exhaustion), we'll try again next time
2897 			if (!q->LocalSocket) q->LocalSocket = mDNSPlatformUDPSocket(m, zeroIPPort);
2898 			if (q->LocalSocket)
2899 				{
2900 				InitializeDNSMessage(&m->omsg.h, q->TargetQID, QueryFlags);
2901 				qptr = putQuestion(&m->omsg, qptr, limit, &q->qname, q->qtype, q->qclass);
2902 				mDNSSendDNSMessage(m, &m->omsg, qptr, mDNSInterface_Any, q->LocalSocket, &q->Target, q->TargetPort, mDNSNULL, mDNSNULL);
2903 				q->ThisQInterval    *= QuestionIntervalStep;
2904 				}
2905 			if (q->ThisQInterval > MaxQuestionInterval)
2906 				q->ThisQInterval = MaxQuestionInterval;
2907 			q->LastQTime         = m->timenow;
2908 			q->LastQTxTime       = m->timenow;
2909 			q->RecentAnswerPkts  = 0;
2910 			q->SendQNow          = mDNSNULL;
2911 			q->ExpectUnicastResp = NonZeroTime(m->timenow);
2912 			}
2913 		else if (mDNSOpaque16IsZero(q->TargetQID) && !q->Target.type && TimeToSendThisQuestion(q, m->timenow))
2914 			{
2915 			//LogInfo("Time to send %##s (%s) %d", q->qname.c, DNSTypeName(q->qtype), m->timenow - NextQSendTime(q));
2916 			q->SendQNow = mDNSInterfaceMark;		// Mark this question for sending on all interfaces
2917 			if (maxExistingQuestionInterval < q->ThisQInterval)
2918 				maxExistingQuestionInterval = q->ThisQInterval;
2919 			}
2920 		// If m->CurrentQuestion wasn't modified out from under us, advance it now
2921 		// We can't do this at the start of the loop because uDNS_CheckCurrentQuestion() depends on having
2922 		// m->CurrentQuestion point to the right question
2923 		if (q == m->CurrentQuestion) m->CurrentQuestion = m->CurrentQuestion->next;
2924 		}
2925 	while (m->CurrentQuestion)
2926 		{
2927 		LogInfo("SendQueries question loop 1: Skipping NewQuestion %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
2928 		m->CurrentQuestion = m->CurrentQuestion->next;
2929 		}
2930 	m->CurrentQuestion = mDNSNULL;
2931 
2932 	// Scan our list of questions
2933 	// (a) to see if there are any more that are worth accelerating, and
2934 	// (b) to update the state variables for *all* the questions we're going to send
2935 	// Note: Don't set NextScheduledQuery until here, because uDNS_CheckCurrentQuestion in the loop above can add new questions to the list,
2936 	// which causes NextScheduledQuery to get (incorrectly) set to m->timenow. Setting it here is the right place, because the very
2937 	// next thing we do is scan the list and call SetNextQueryTime() for every question we find, so we know we end up with the right value.
2938 	m->NextScheduledQuery = m->timenow + 0x78000000;
2939 	for (q = m->Questions; q && q != m->NewQuestions; q=q->next)
2940 		{
2941 		if (mDNSOpaque16IsZero(q->TargetQID) && (q->SendQNow ||
2942 			(!q->Target.type && ActiveQuestion(q) && q->ThisQInterval <= maxExistingQuestionInterval && AccelerateThisQuery(m,q))))
2943 			{
2944 			// If at least halfway to next query time, advance to next interval
2945 			// If less than halfway to next query time, then
2946 			// treat this as logically a repeat of the last transmission, without advancing the interval
2947 			if (m->timenow - (q->LastQTime + (q->ThisQInterval/2)) >= 0)
2948 				{
2949 				//LogInfo("Accelerating %##s (%s) %d", q->qname.c, DNSTypeName(q->qtype), m->timenow - NextQSendTime(q));
2950 				q->SendQNow = mDNSInterfaceMark;	// Mark this question for sending on all interfaces
2951 				debugf("SendQueries: %##s (%s) next interval %d seconds RequestUnicast = %d",
2952 					q->qname.c, DNSTypeName(q->qtype), q->ThisQInterval / InitialQuestionInterval, q->RequestUnicast);
2953 				q->ThisQInterval *= QuestionIntervalStep;
2954 				if (q->ThisQInterval > MaxQuestionInterval)
2955 					q->ThisQInterval = MaxQuestionInterval;
2956 				else if (q->CurrentAnswers == 0 && q->ThisQInterval == InitialQuestionInterval * QuestionIntervalStep3 && !q->RequestUnicast &&
2957 						!(RRTypeIsAddressType(q->qtype) && CacheHasAddressTypeForName(m, &q->qname, q->qnamehash)))
2958 					{
2959 					// Generally don't need to log this.
2960 					// It's not especially noteworthy if a query finds no results -- this usually happens for domain
2961 					// enumeration queries in the LL subdomain (e.g. "db._dns-sd._udp.0.0.254.169.in-addr.arpa")
2962 					// and when there simply happen to be no instances of the service the client is looking
2963 					// for (e.g. iTunes is set to look for RAOP devices, and the current network has none).
2964 					debugf("SendQueries: Zero current answers for %##s (%s); will reconfirm antecedents",
2965 						q->qname.c, DNSTypeName(q->qtype));
2966 					// Sending third query, and no answers yet; time to begin doubting the source
2967 					ReconfirmAntecedents(m, &q->qname, q->qnamehash, 0);
2968 					}
2969 				}
2970 
2971 			// Mark for sending. (If no active interfaces, then don't even try.)
2972 			q->SendOnAll = (q->SendQNow == mDNSInterfaceMark);
2973 			if (q->SendOnAll)
2974 				{
2975 				q->SendQNow  = !intf ? mDNSNULL : (q->InterfaceID) ? q->InterfaceID : intf->InterfaceID;
2976 				q->LastQTime = m->timenow;
2977 				}
2978 
2979 			// If we recorded a duplicate suppression for this question less than half an interval ago,
2980 			// then we consider it recent enough that we don't need to do an identical query ourselves.
2981 			ExpireDupSuppressInfo(q->DupSuppress, m->timenow - q->ThisQInterval/2);
2982 
2983 			q->LastQTxTime      = m->timenow;
2984 			q->RecentAnswerPkts = 0;
2985 			if (q->RequestUnicast) q->RequestUnicast--;
2986 			}
2987 		// For all questions (not just the ones we're sending) check what the next scheduled event will be
2988 		// We don't need to consider NewQuestions here because for those we'll set m->NextScheduledQuery in AnswerNewQuestion
2989 		SetNextQueryTime(m,q);
2990 		}
2991 
2992 	// 2. Scan our authoritative RR list to see what probes we might need to send
2993 
2994 	m->NextScheduledProbe = m->timenow + 0x78000000;
2995 
2996 	if (m->CurrentRecord)
2997 		LogMsg("SendQueries ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord));
2998 	m->CurrentRecord = m->ResourceRecords;
2999 	while (m->CurrentRecord)
3000 		{
3001 		ar = m->CurrentRecord;
3002 		m->CurrentRecord = ar->next;
3003 		if (!AuthRecord_uDNS(ar) && ar->resrec.RecordType == kDNSRecordTypeUnique)	// For all records that are still probing...
3004 			{
3005 			// 1. If it's not reached its probe time, just make sure we update m->NextScheduledProbe correctly
3006 			if (m->timenow - (ar->LastAPTime + ar->ThisAPInterval) < 0)
3007 				{
3008 				SetNextAnnounceProbeTime(m, ar);
3009 				}
3010 			// 2. else, if it has reached its probe time, mark it for sending and then update m->NextScheduledProbe correctly
3011 			else if (ar->ProbeCount)
3012 				{
3013 				if (ar->AddressProxy.type == mDNSAddrType_IPv4)
3014 					{
3015 					LogSPS("SendQueries ARP Probe %d %s %s", ar->ProbeCount, InterfaceNameForID(m, ar->resrec.InterfaceID), ARDisplayString(m,ar));
3016 					SendARP(m, 1, ar, &zerov4Addr, &zeroEthAddr, &ar->AddressProxy.ip.v4, &ar->WakeUp.IMAC);
3017 					}
3018 				else if (ar->AddressProxy.type == mDNSAddrType_IPv6)
3019 					{
3020 					LogSPS("SendQueries NDP Probe %d %s %s", ar->ProbeCount, InterfaceNameForID(m, ar->resrec.InterfaceID), ARDisplayString(m,ar));
3021 					// IPv6 source = zero
3022 					// No target hardware address
3023 					// IPv6 target address is address we're probing
3024 					// Ethernet destination address is Ethernet interface address of the Sleep Proxy client we're probing
3025 					SendNDP(m, NDP_Sol, 0, ar, &zerov6Addr, mDNSNULL, &ar->AddressProxy.ip.v6, &ar->WakeUp.IMAC);
3026 					}
3027 				// Mark for sending. (If no active interfaces, then don't even try.)
3028 				ar->SendRNow   = (!intf || ar->WakeUp.HMAC.l[0]) ? mDNSNULL : ar->resrec.InterfaceID ? ar->resrec.InterfaceID : intf->InterfaceID;
3029 				ar->LastAPTime = m->timenow;
3030 				// When we have a late conflict that resets a record to probing state we use a special marker value greater
3031 				// than DefaultProbeCountForTypeUnique. Here we detect that state and reset ar->ProbeCount back to the right value.
3032 				if (ar->ProbeCount > DefaultProbeCountForTypeUnique)
3033 					ar->ProbeCount = DefaultProbeCountForTypeUnique;
3034 				ar->ProbeCount--;
3035 				SetNextAnnounceProbeTime(m, ar);
3036 				if (ar->ProbeCount == 0)
3037 					{
3038 					// If this is the last probe for this record, then see if we have any matching records
3039 					// on our duplicate list which should similarly have their ProbeCount cleared to zero...
3040 					AuthRecord *r2;
3041 					for (r2 = m->DuplicateRecords; r2; r2=r2->next)
3042 						if (r2->resrec.RecordType == kDNSRecordTypeUnique && RecordIsLocalDuplicate(r2, ar))
3043 							r2->ProbeCount = 0;
3044 					// ... then acknowledge this record to the client.
3045 					// We do this optimistically, just as we're about to send the third probe.
3046 					// This helps clients that both advertise and browse, and want to filter themselves
3047 					// from the browse results list, because it helps ensure that the registration
3048 					// confirmation will be delivered 1/4 second *before* the browse "add" event.
3049 					// A potential downside is that we could deliver a registration confirmation and then find out
3050 					// moments later that there's a name conflict, but applications have to be prepared to handle
3051 					// late conflicts anyway (e.g. on connection of network cable, etc.), so this is nothing new.
3052 					if (!ar->Acknowledged) AcknowledgeRecord(m, ar);
3053 					}
3054 				}
3055 			// else, if it has now finished probing, move it to state Verified,
3056 			// and update m->NextScheduledResponse so it will be announced
3057 			else
3058 				{
3059 				if (!ar->Acknowledged) AcknowledgeRecord(m, ar);	// Defensive, just in case it got missed somehow
3060 				ar->resrec.RecordType     = kDNSRecordTypeVerified;
3061 				ar->ThisAPInterval = DefaultAnnounceIntervalForTypeUnique;
3062 				ar->LastAPTime     = m->timenow - DefaultAnnounceIntervalForTypeUnique;
3063 				SetNextAnnounceProbeTime(m, ar);
3064 				}
3065 			}
3066 		}
3067 	m->CurrentRecord = m->DuplicateRecords;
3068 	while (m->CurrentRecord)
3069 		{
3070 		ar = m->CurrentRecord;
3071 		m->CurrentRecord = ar->next;
3072 		if (ar->resrec.RecordType == kDNSRecordTypeUnique && ar->ProbeCount == 0 && !ar->Acknowledged)
3073 			AcknowledgeRecord(m, ar);
3074 		}
3075 
3076 	// 3. Now we know which queries and probes we're sending,
3077 	// go through our interface list sending the appropriate queries on each interface
3078 	while (intf)
3079 		{
3080 		const int OwnerRecordSpace = (m->AnnounceOwner && intf->MAC.l[0]) ? DNSOpt_Header_Space + DNSOpt_Owner_Space(&m->PrimaryMAC, &intf->MAC) : 0;
3081 		mDNSu8 *queryptr = m->omsg.data;
3082 		InitializeDNSMessage(&m->omsg.h, zeroID, QueryFlags);
3083 		if (KnownAnswerList) verbosedebugf("SendQueries:   KnownAnswerList set... Will continue from previous packet");
3084 		if (!KnownAnswerList)
3085 			{
3086 			// Start a new known-answer list
3087 			CacheRecord **kalistptr = &KnownAnswerList;
3088 			mDNSu32 answerforecast = OwnerRecordSpace;		// We start by assuming we'll need at least enough space to put the Owner Option
3089 
3090 			// Put query questions in this packet
3091 			for (q = m->Questions; q && q != m->NewQuestions; q=q->next)
3092 				{
3093 				if (mDNSOpaque16IsZero(q->TargetQID) && (q->SendQNow == intf->InterfaceID))
3094 					{
3095 					debugf("SendQueries: %s question for %##s (%s) at %d forecast total %d",
3096 						SuppressOnThisInterface(q->DupSuppress, intf) ? "Suppressing" : "Putting    ",
3097 						q->qname.c, DNSTypeName(q->qtype), queryptr - m->omsg.data, queryptr + answerforecast - m->omsg.data);
3098 
3099 					// If we're suppressing this question, or we successfully put it, update its SendQNow state
3100 					if (SuppressOnThisInterface(q->DupSuppress, intf) ||
3101 						BuildQuestion(m, &m->omsg, &queryptr, q, &kalistptr, &answerforecast))
3102 						{
3103 						q->SendQNow = (q->InterfaceID || !q->SendOnAll) ? mDNSNULL : GetNextActiveInterfaceID(intf);
3104 						if (q->WakeOnResolveCount)
3105 							{
3106 							mDNSSendWakeOnResolve(m, q);
3107 							q->WakeOnResolveCount--;
3108 							}
3109 						}
3110 					}
3111 				}
3112 
3113 			// Put probe questions in this packet
3114 			for (ar = m->ResourceRecords; ar; ar=ar->next)
3115 				if (ar->SendRNow == intf->InterfaceID)
3116 					{
3117 					mDNSBool ucast = (ar->ProbeCount >= DefaultProbeCountForTypeUnique-1) && m->CanReceiveUnicastOn5353;
3118 					mDNSu16 ucbit = (mDNSu16)(ucast ? kDNSQClass_UnicastResponse : 0);
3119 					const mDNSu8 *const limit = m->omsg.data + (m->omsg.h.numQuestions ? NormalMaxDNSMessageData : AbsoluteMaxDNSMessageData);
3120 					// We forecast: compressed name (2) type (2) class (2) TTL (4) rdlength (2) rdata (n)
3121 					mDNSu32 forecast = answerforecast + 12 + ar->resrec.rdestimate;
3122 					mDNSu8 *newptr = putQuestion(&m->omsg, queryptr, limit - forecast, ar->resrec.name, kDNSQType_ANY, (mDNSu16)(ar->resrec.rrclass | ucbit));
3123 					if (newptr)
3124 						{
3125 						queryptr       = newptr;
3126 						answerforecast = forecast;
3127 						ar->SendRNow = (ar->resrec.InterfaceID) ? mDNSNULL : GetNextActiveInterfaceID(intf);
3128 						ar->IncludeInProbe = mDNStrue;
3129 						verbosedebugf("SendQueries:   Put Question %##s (%s) probecount %d",
3130 							ar->resrec.name->c, DNSTypeName(ar->resrec.rrtype), ar->ProbeCount);
3131 						}
3132 					}
3133 			}
3134 
3135 		// Put our known answer list (either new one from this question or questions, or remainder of old one from last time)
3136 		while (KnownAnswerList)
3137 			{
3138 			CacheRecord *ka = KnownAnswerList;
3139 			mDNSu32 SecsSinceRcvd = ((mDNSu32)(m->timenow - ka->TimeRcvd)) / mDNSPlatformOneSecond;
3140 			mDNSu8 *newptr = PutResourceRecordTTLWithLimit(&m->omsg, queryptr, &m->omsg.h.numAnswers,
3141 				&ka->resrec, ka->resrec.rroriginalttl - SecsSinceRcvd, m->omsg.data + NormalMaxDNSMessageData - OwnerRecordSpace);
3142 			if (newptr)
3143 				{
3144 				verbosedebugf("SendQueries:   Put %##s (%s) at %d - %d",
3145 					ka->resrec.name->c, DNSTypeName(ka->resrec.rrtype), queryptr - m->omsg.data, newptr - m->omsg.data);
3146 				queryptr = newptr;
3147 				KnownAnswerList = ka->NextInKAList;
3148 				ka->NextInKAList = mDNSNULL;
3149 				}
3150 			else
3151 				{
3152 				// If we ran out of space and we have more than one question in the packet, that's an error --
3153 				// we shouldn't have put more than one question if there was a risk of us running out of space.
3154 				if (m->omsg.h.numQuestions > 1)
3155 					LogMsg("SendQueries:   Put %d answers; No more space for known answers", m->omsg.h.numAnswers);
3156 				m->omsg.h.flags.b[0] |= kDNSFlag0_TC;
3157 				break;
3158 				}
3159 			}
3160 
3161 		for (ar = m->ResourceRecords; ar; ar=ar->next)
3162 			if (ar->IncludeInProbe)
3163 				{
3164 				mDNSu8 *newptr = PutResourceRecord(&m->omsg, queryptr, &m->omsg.h.numAuthorities, &ar->resrec);
3165 				ar->IncludeInProbe = mDNSfalse;
3166 				if (newptr) queryptr = newptr;
3167 				else LogMsg("SendQueries:   How did we fail to have space for the Update record %s", ARDisplayString(m,ar));
3168 				}
3169 
3170 		if (queryptr > m->omsg.data)
3171 			{
3172 			if (OwnerRecordSpace)
3173 				{
3174 				AuthRecord opt;
3175 				mDNS_SetupResourceRecord(&opt, mDNSNULL, mDNSInterface_Any, kDNSType_OPT, kStandardTTL, kDNSRecordTypeKnownUnique, AuthRecordAny, mDNSNULL, mDNSNULL);
3176 				opt.resrec.rrclass    = NormalMaxDNSMessageData;
3177 				opt.resrec.rdlength   = sizeof(rdataOPT);	// One option in this OPT record
3178 				opt.resrec.rdestimate = sizeof(rdataOPT);
3179 				SetupOwnerOpt(m, intf, &opt.resrec.rdata->u.opt[0]);
3180 				LogSPS("SendQueries putting %s", ARDisplayString(m, &opt));
3181 				queryptr = PutResourceRecordTTLWithLimit(&m->omsg, queryptr, &m->omsg.h.numAdditionals,
3182 					&opt.resrec, opt.resrec.rroriginalttl, m->omsg.data + AbsoluteMaxDNSMessageData);
3183 				if (!queryptr)
3184 					LogMsg("SendQueries: How did we fail to have space for the OPT record (%d/%d/%d/%d) %s",
3185 						m->omsg.h.numQuestions, m->omsg.h.numAnswers, m->omsg.h.numAuthorities, m->omsg.h.numAdditionals, ARDisplayString(m, &opt));
3186 				if (queryptr > m->omsg.data + NormalMaxDNSMessageData)
3187 					if (m->omsg.h.numQuestions != 1 || m->omsg.h.numAnswers != 0 || m->omsg.h.numAuthorities != 1 || m->omsg.h.numAdditionals != 1)
3188 						LogMsg("SendQueries: Why did we generate oversized packet with OPT record %p %p %p (%d/%d/%d/%d) %s",
3189 							m->omsg.data, m->omsg.data + NormalMaxDNSMessageData, queryptr,
3190 							m->omsg.h.numQuestions, m->omsg.h.numAnswers, m->omsg.h.numAuthorities, m->omsg.h.numAdditionals, ARDisplayString(m, &opt));
3191 				}
3192 
3193 			if ((m->omsg.h.flags.b[0] & kDNSFlag0_TC) && m->omsg.h.numQuestions > 1)
3194 				LogMsg("SendQueries: Should not have more than one question (%d) in a truncated packet", m->omsg.h.numQuestions);
3195 			debugf("SendQueries:   Sending %d Question%s %d Answer%s %d Update%s on %p",
3196 				m->omsg.h.numQuestions,   m->omsg.h.numQuestions   == 1 ? "" : "s",
3197 				m->omsg.h.numAnswers,     m->omsg.h.numAnswers     == 1 ? "" : "s",
3198 				m->omsg.h.numAuthorities, m->omsg.h.numAuthorities == 1 ? "" : "s", intf->InterfaceID);
3199 			if (intf->IPv4Available) mDNSSendDNSMessage(m, &m->omsg, queryptr, intf->InterfaceID, mDNSNULL, &AllDNSLinkGroup_v4, MulticastDNSPort, mDNSNULL, mDNSNULL);
3200 			if (intf->IPv6Available) mDNSSendDNSMessage(m, &m->omsg, queryptr, intf->InterfaceID, mDNSNULL, &AllDNSLinkGroup_v6, MulticastDNSPort, mDNSNULL, mDNSNULL);
3201 			if (!m->SuppressSending) m->SuppressSending = NonZeroTime(m->timenow + (mDNSPlatformOneSecond+9)/10);
3202 			if (++pktcount >= 1000)
3203 				{ LogMsg("SendQueries exceeded loop limit %d: giving up", pktcount); break; }
3204 			// There might be more records left in the known answer list, or more questions to send
3205 			// on this interface, so go around one more time and try again.
3206 			}
3207 		else	// Nothing more to send on this interface; go to next
3208 			{
3209 			const NetworkInterfaceInfo *next = GetFirstActiveInterface(intf->next);
3210 			#if MDNS_DEBUGMSGS && 0
3211 			const char *const msg = next ? "SendQueries:   Nothing more on %p; moving to %p" : "SendQueries:   Nothing more on %p";
3212 			debugf(msg, intf, next);
3213 			#endif
3214 			intf = next;
3215 			}
3216 		}
3217 
3218 	// 4. Final housekeeping
3219 
3220 	// 4a. Debugging check: Make sure we announced all our records
3221 	for (ar = m->ResourceRecords; ar; ar=ar->next)
3222 		if (ar->SendRNow)
3223 			{
3224 			if (ar->ARType != AuthRecordLocalOnly && ar->ARType != AuthRecordP2P)
3225 				LogMsg("SendQueries: No active interface %p to send probe: %p %s", ar->SendRNow, ar->resrec.InterfaceID, ARDisplayString(m, ar));
3226 			ar->SendRNow = mDNSNULL;
3227 			}
3228 
3229 	// 4b. When we have lingering cache records that we're keeping around for a few seconds in the hope
3230 	// that their interface which went away might come back again, the logic will want to send queries
3231 	// for those records, but we can't because their interface isn't here any more, so to keep the
3232 	// state machine ticking over we just pretend we did so.
3233 	// If the interface does not come back in time, the cache record will expire naturally
3234 	FORALL_CACHERECORDS(slot, cg, cr)
3235 		if (cr->CRActiveQuestion && cr->UnansweredQueries < MaxUnansweredQueries)
3236 			if (m->timenow + TicksTTL(cr)/50 - cr->NextRequiredQuery >= 0)
3237 				{
3238 				cr->UnansweredQueries++;
3239 				cr->CRActiveQuestion->SendQNow = mDNSNULL;
3240 				SetNextCacheCheckTimeForRecord(m, cr);
3241 				}
3242 
3243 	// 4c. Debugging check: Make sure we sent all our planned questions
3244 	// Do this AFTER the lingering cache records check above, because that will prevent spurious warnings for questions
3245 	// we legitimately couldn't send because the interface is no longer available
3246 	for (q = m->Questions; q; q=q->next)
3247 		if (q->SendQNow)
3248 			{
3249 			DNSQuestion *x;
3250 			for (x = m->NewQuestions; x; x=x->next) if (x == q) break;	// Check if this question is a NewQuestion
3251 			LogMsg("SendQueries: No active interface %p to send %s question: %p %##s (%s)", q->SendQNow, x ? "new" : "old", q->InterfaceID, q->qname.c, DNSTypeName(q->qtype));
3252 			q->SendQNow = mDNSNULL;
3253 			}
3254 	}
3255 
SendWakeup(mDNS * const m,mDNSInterfaceID InterfaceID,mDNSEthAddr * EthAddr,mDNSOpaque48 * password)3256 mDNSlocal void SendWakeup(mDNS *const m, mDNSInterfaceID InterfaceID, mDNSEthAddr *EthAddr, mDNSOpaque48 *password)
3257 	{
3258 	int i, j;
3259 	mDNSu8 *ptr = m->omsg.data;
3260 	NetworkInterfaceInfo *intf = FirstInterfaceForID(m, InterfaceID);
3261 	if (!intf) { LogMsg("SendARP: No interface with InterfaceID %p found", InterfaceID); return; }
3262 
3263 	// 0x00 Destination address
3264 	for (i=0; i<6; i++) *ptr++ = EthAddr->b[i];
3265 
3266 	// 0x06 Source address (Note: Since we don't currently set the BIOCSHDRCMPLT option, BPF will fill in the real interface address for us)
3267 	for (i=0; i<6; i++) *ptr++ = intf->MAC.b[0];
3268 
3269 	// 0x0C Ethertype (0x0842)
3270 	*ptr++ = 0x08;
3271 	*ptr++ = 0x42;
3272 
3273 	// 0x0E Wakeup sync sequence
3274 	for (i=0; i<6; i++) *ptr++ = 0xFF;
3275 
3276 	// 0x14 Wakeup data
3277 	for (j=0; j<16; j++) for (i=0; i<6; i++) *ptr++ = EthAddr->b[i];
3278 
3279 	// 0x74 Password
3280 	for (i=0; i<6; i++) *ptr++ = password->b[i];
3281 
3282 	mDNSPlatformSendRawPacket(m->omsg.data, ptr, InterfaceID);
3283 
3284 	// For Ethernet switches that don't flood-foward packets with unknown unicast destination MAC addresses,
3285 	// broadcast is the only reliable way to get a wakeup packet to the intended target machine.
3286 	// For 802.11 WPA networks, where a sleeping target machine may have missed a broadcast/multicast
3287 	// key rotation, unicast is the only way to get a wakeup packet to the intended target machine.
3288 	// So, we send one of each, unicast first, then broadcast second.
3289 	for (i=0; i<6; i++) m->omsg.data[i] = 0xFF;
3290 	mDNSPlatformSendRawPacket(m->omsg.data, ptr, InterfaceID);
3291 	}
3292 
3293 // ***************************************************************************
3294 #if COMPILER_LIKES_PRAGMA_MARK
3295 #pragma mark -
3296 #pragma mark - RR List Management & Task Management
3297 #endif
3298 
3299 // Note: AnswerCurrentQuestionWithResourceRecord can call a user callback, which may change the record list and/or question list.
3300 // Any code walking either list must use the m->CurrentQuestion (and possibly m->CurrentRecord) mechanism to protect against this.
3301 // In fact, to enforce this, the routine will *only* answer the question currently pointed to by m->CurrentQuestion,
3302 // which will be auto-advanced (possibly to NULL) if the client callback cancels the question.
AnswerCurrentQuestionWithResourceRecord(mDNS * const m,CacheRecord * const rr,const QC_result AddRecord)3303 mDNSexport void AnswerCurrentQuestionWithResourceRecord(mDNS *const m, CacheRecord *const rr, const QC_result AddRecord)
3304 	{
3305 	DNSQuestion *const q = m->CurrentQuestion;
3306 	mDNSBool followcname = FollowCNAME(q, &rr->resrec, AddRecord);
3307 
3308 	verbosedebugf("AnswerCurrentQuestionWithResourceRecord:%4lu %s TTL %d %s",
3309 		q->CurrentAnswers, AddRecord ? "Add" : "Rmv", rr->resrec.rroriginalttl, CRDisplayString(m, rr));
3310 
3311 	// Normally we don't send out the unicast query if we have answered using our local only auth records e.g., /etc/hosts.
3312 	// But if the query for "A" record has a local answer but query for "AAAA" record has no local answer, we might
3313 	// send the AAAA query out which will come back with CNAME and will also answer the "A" query. To prevent that,
3314 	// we check to see if that query already has a unique local answer.
3315 	if (q->LOAddressAnswers)
3316 		{
3317 		LogInfo("AnswerCurrentQuestionWithResourceRecord: Question %p %##s (%s) not answering with record %s due to "
3318 			"LOAddressAnswers %d", q, q->qname.c, DNSTypeName(q->qtype), ARDisplayString(m, rr),
3319 			q->LOAddressAnswers);
3320 		return;
3321 		}
3322 
3323 	if (QuerySuppressed(q))
3324 		{
3325 		// If the query is suppressed, then we don't want to answer from the cache. But if this query is
3326 		// supposed to time out, we still want to callback the clients. We do this only for TimeoutQuestions
3327 		// that are timing out, which we know are answered with Negative cache record when timing out.
3328 		if (!q->TimeoutQuestion || rr->resrec.RecordType != kDNSRecordTypePacketNegative || (m->timenow - q->StopTime < 0))
3329 			return;
3330 		}
3331 
3332 	// Note: Use caution here. In the case of records with rr->DelayDelivery set, AnswerCurrentQuestionWithResourceRecord(... mDNStrue)
3333 	// may be called twice, once when the record is received, and again when it's time to notify local clients.
3334 	// If any counters or similar are added here, care must be taken to ensure that they are not double-incremented by this.
3335 
3336 	rr->LastUsed = m->timenow;
3337 	if (AddRecord == QC_add && !q->DuplicateOf && rr->CRActiveQuestion != q)
3338 		{
3339 		if (!rr->CRActiveQuestion) m->rrcache_active++;	// If not previously active, increment rrcache_active count
3340 		debugf("AnswerCurrentQuestionWithResourceRecord: Updating CRActiveQuestion from %p to %p for cache record %s, CurrentAnswer %d",
3341 			rr->CRActiveQuestion, q, CRDisplayString(m,rr), q->CurrentAnswers);
3342 		rr->CRActiveQuestion = q;						// We know q is non-null
3343 		SetNextCacheCheckTimeForRecord(m, rr);
3344 		}
3345 
3346 	// If this is:
3347 	// (a) a no-cache add, where we've already done at least one 'QM' query, or
3348 	// (b) a normal add, where we have at least one unique-type answer,
3349 	// then there's no need to keep polling the network.
3350 	// (If we have an answer in the cache, then we'll automatically ask again in time to stop it expiring.)
3351 	// We do this for mDNS questions and uDNS one-shot questions, but not for
3352 	// uDNS LongLived questions, because that would mess up our LLQ lease renewal timing.
3353 	if ((AddRecord == QC_addnocache && !q->RequestUnicast) ||
3354 		(AddRecord == QC_add && (q->ExpectUnique || (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask))))
3355 		if (ActiveQuestion(q) && (mDNSOpaque16IsZero(q->TargetQID) || !q->LongLived))
3356 			{
3357 			q->LastQTime        = m->timenow;
3358 			q->LastQTxTime      = m->timenow;
3359 			q->RecentAnswerPkts = 0;
3360 			q->ThisQInterval    = MaxQuestionInterval;
3361 			q->RequestUnicast   = mDNSfalse;
3362 			debugf("AnswerCurrentQuestionWithResourceRecord: Set MaxQuestionInterval for %##s (%s)", q->qname.c, DNSTypeName(q->qtype));
3363 			}
3364 
3365 	if (rr->DelayDelivery) return;		// We'll come back later when CacheRecordDeferredAdd() calls us
3366 
3367 	// Only deliver negative answers if client has explicitly requested them
3368 	if (rr->resrec.RecordType == kDNSRecordTypePacketNegative || (q->qtype != kDNSType_NSEC && RRAssertsNonexistence(&rr->resrec, q->qtype)))
3369 		if (!AddRecord || !q->ReturnIntermed) return;
3370 
3371 	// For CNAME results to non-CNAME questions, only inform the client if they explicitly requested that
3372 	if (q->QuestionCallback && !q->NoAnswer && (!followcname || q->ReturnIntermed))
3373 		{
3374 		mDNS_DropLockBeforeCallback();		// Allow client (and us) to legally make mDNS API calls
3375 		if (q->qtype != kDNSType_NSEC && RRAssertsNonexistence(&rr->resrec, q->qtype))
3376 			{
3377 			CacheRecord neg;
3378 			MakeNegativeCacheRecord(m, &neg, &q->qname, q->qnamehash, q->qtype, q->qclass, 1, rr->resrec.InterfaceID, q->qDNSServer);
3379 			q->QuestionCallback(m, q, &neg.resrec, AddRecord);
3380 			}
3381 		else
3382 			q->QuestionCallback(m, q, &rr->resrec, AddRecord);
3383 		mDNS_ReclaimLockAfterCallback();	// Decrement mDNS_reentrancy to block mDNS API calls again
3384 		}
3385 	// Note: Proceed with caution here because client callback function is allowed to do anything,
3386 	// including starting/stopping queries, registering/deregistering records, etc.
3387 
3388 	if (followcname && m->CurrentQuestion == q)
3389 		AnswerQuestionByFollowingCNAME(m, q, &rr->resrec);
3390 	}
3391 
3392 // New Questions are answered through AnswerNewQuestion. But there may not have been any
3393 // matching cache records for the questions when it is called. There are two possibilities.
3394 //
3395 // 1) There are no cache records
3396 // 2) There are cache records but the DNSServers between question and cache record don't match.
3397 //
3398 // In the case of (1), where there are no cache records and later we add them when we get a response,
3399 // CacheRecordAdd/CacheRecordDeferredAdd will take care of adding the cache and delivering the ADD
3400 // events to the application. If we already have a cache entry, then no ADD events are delivered
3401 // unless the RDATA has changed
3402 //
3403 // In the case of (2) where we had the cache records and did not answer because of the DNSServer mismatch,
3404 // we need to answer them whenever we change the DNSServer.  But we can't do it at the instant the DNSServer
3405 // changes because when we do the callback, the question can get deleted and the calling function would not
3406 // know how to handle it. So, we run this function from mDNS_Execute to handle DNSServer changes on the
3407 // question
3408 
AnswerQuestionsForDNSServerChanges(mDNS * const m)3409 mDNSlocal void AnswerQuestionsForDNSServerChanges(mDNS *const m)
3410 	{
3411 	DNSQuestion *q;
3412 	DNSQuestion *qnext;
3413 	CacheRecord *rr;
3414 	mDNSu32 slot;
3415 	CacheGroup *cg;
3416 
3417 	if (m->CurrentQuestion)
3418 		LogMsg("AnswerQuestionsForDNSServerChanges: ERROR m->CurrentQuestion already set: %##s (%s)",
3419 				m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
3420 
3421 	for (q = m->Questions; q && q != m->NewQuestions; q = qnext)
3422 		{
3423 		qnext = q->next;
3424 
3425 		// multicast or DNSServers did not change.
3426 		if (mDNSOpaque16IsZero(q->TargetQID)) continue;
3427 		if (!q->deliverAddEvents) continue;
3428 
3429 		// We are going to look through the cache for this question since it changed
3430 		// its DNSserver last time. Reset it so that we don't call them again. Calling
3431 		// them again will deliver duplicate events to the application
3432 		q->deliverAddEvents = mDNSfalse;
3433 		if (QuerySuppressed(q)) continue;
3434 		m->CurrentQuestion = q;
3435 		slot = HashSlot(&q->qname);
3436 		cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname);
3437 		for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next)
3438 			{
3439 			if (SameNameRecordAnswersQuestion(&rr->resrec, q))
3440 				{
3441 				LogInfo("AnswerQuestionsForDNSServerChanges: Calling AnswerCurrentQuestionWithResourceRecord for question %p %##s using resource record %s",
3442 					q, q->qname.c, CRDisplayString(m, rr));
3443 				// When this question penalizes a DNS server and has no more DNS servers to pick, we normally
3444 				// deliver a negative cache response and suspend the question for 60 seconds (see uDNS_CheckCurrentQuestion).
3445 				// But sometimes we may already find the negative cache entry and deliver that here as the process
3446 				// of changing DNS servers. When the cache entry is about to expire, we will resend the question and
3447 				// that time, we need to make sure that we have a valid DNS server. Otherwise, we will deliver
3448 				// a negative cache response without trying the server.
3449 				if (!q->qDNSServer && !q->DuplicateOf && rr->resrec.RecordType == kDNSRecordTypePacketNegative)
3450 					{
3451 					DNSQuestion *qptr;
3452 					SetValidDNSServers(m, q);
3453 					q->qDNSServer = GetServerForQuestion(m, q);
3454 					for (qptr = q->next ; qptr; qptr = qptr->next)
3455 						if (qptr->DuplicateOf == q) { qptr->validDNSServers = q->validDNSServers; qptr->qDNSServer = q->qDNSServer; }
3456 					}
3457 				q->CurrentAnswers++;
3458 				if (rr->resrec.rdlength > SmallRecordLimit) q->LargeAnswers++;
3459 				if (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) q->UniqueAnswers++;
3460 				AnswerCurrentQuestionWithResourceRecord(m, rr, QC_add);
3461 				if (m->CurrentQuestion != q) break;		// If callback deleted q, then we're finished here
3462 				}
3463 			}
3464 		}
3465 		m->CurrentQuestion = mDNSNULL;
3466 	}
3467 
CacheRecordDeferredAdd(mDNS * const m,CacheRecord * rr)3468 mDNSlocal void CacheRecordDeferredAdd(mDNS *const m, CacheRecord *rr)
3469 	{
3470 	rr->DelayDelivery = 0;
3471 	if (m->CurrentQuestion)
3472 		LogMsg("CacheRecordDeferredAdd ERROR m->CurrentQuestion already set: %##s (%s)",
3473 			m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
3474 	m->CurrentQuestion = m->Questions;
3475 	while (m->CurrentQuestion && m->CurrentQuestion != m->NewQuestions)
3476 		{
3477 		DNSQuestion *q = m->CurrentQuestion;
3478 		if (ResourceRecordAnswersQuestion(&rr->resrec, q))
3479 			AnswerCurrentQuestionWithResourceRecord(m, rr, QC_add);
3480 		if (m->CurrentQuestion == q)	// If m->CurrentQuestion was not auto-advanced, do it ourselves now
3481 			m->CurrentQuestion = q->next;
3482 		}
3483 	m->CurrentQuestion = mDNSNULL;
3484 	}
3485 
CheckForSoonToExpireRecords(mDNS * const m,const domainname * const name,const mDNSu32 namehash,const mDNSu32 slot)3486 mDNSlocal mDNSs32 CheckForSoonToExpireRecords(mDNS *const m, const domainname *const name, const mDNSu32 namehash, const mDNSu32 slot)
3487 	{
3488 	const mDNSs32 threshhold = m->timenow + mDNSPlatformOneSecond;	// See if there are any records expiring within one second
3489 	const mDNSs32 start      = m->timenow - 0x10000000;
3490 	mDNSs32 delay = start;
3491 	CacheGroup *cg = CacheGroupForName(m, slot, namehash, name);
3492 	const CacheRecord *rr;
3493 	for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next)
3494 		if (threshhold - RRExpireTime(rr) >= 0)		// If we have records about to expire within a second
3495 			if (delay - RRExpireTime(rr) < 0)		// then delay until after they've been deleted
3496 				delay = RRExpireTime(rr);
3497 	if (delay - start > 0) return(NonZeroTime(delay));
3498 	else return(0);
3499 	}
3500 
3501 // CacheRecordAdd is only called from CreateNewCacheEntry, *never* directly as a result of a client API call.
3502 // If new questions are created as a result of invoking client callbacks, they will be added to
3503 // the end of the question list, and m->NewQuestions will be set to indicate the first new question.
3504 // rr is a new CacheRecord just received into our cache
3505 // (kDNSRecordTypePacketAns/PacketAnsUnique/PacketAdd/PacketAddUnique).
3506 // Note: CacheRecordAdd calls AnswerCurrentQuestionWithResourceRecord which can call a user callback,
3507 // which may change the record list and/or question list.
3508 // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this.
CacheRecordAdd(mDNS * const m,CacheRecord * rr)3509 mDNSlocal void CacheRecordAdd(mDNS *const m, CacheRecord *rr)
3510 	{
3511 	DNSQuestion *q;
3512 
3513 	// We stop when we get to NewQuestions -- if we increment their CurrentAnswers/LargeAnswers/UniqueAnswers
3514 	// counters here we'll end up double-incrementing them when we do it again in AnswerNewQuestion().
3515 	for (q = m->Questions; q && q != m->NewQuestions; q=q->next)
3516 		{
3517 		if (ResourceRecordAnswersQuestion(&rr->resrec, q))
3518 			{
3519 			// If this question is one that's actively sending queries, and it's received ten answers within one
3520 			// second of sending the last query packet, then that indicates some radical network topology change,
3521 			// so reset its exponential backoff back to the start. We must be at least at the eight-second interval
3522 			// to do this. If we're at the four-second interval, or less, there's not much benefit accelerating
3523 			// because we will anyway send another query within a few seconds. The first reset query is sent out
3524 			// randomized over the next four seconds to reduce possible synchronization between machines.
3525 			if (q->LastAnswerPktNum != m->PktNum)
3526 				{
3527 				q->LastAnswerPktNum = m->PktNum;
3528 				if (mDNSOpaque16IsZero(q->TargetQID) && ActiveQuestion(q) && ++q->RecentAnswerPkts >= 10 &&
3529 					q->ThisQInterval > InitialQuestionInterval * QuestionIntervalStep3 && m->timenow - q->LastQTxTime < mDNSPlatformOneSecond)
3530 					{
3531 					LogMsg("CacheRecordAdd: %##s (%s) got immediate answer burst (%d); restarting exponential backoff sequence (%d)",
3532 						q->qname.c, DNSTypeName(q->qtype), q->RecentAnswerPkts, q->ThisQInterval);
3533 					q->LastQTime      = m->timenow - InitialQuestionInterval + (mDNSs32)mDNSRandom((mDNSu32)mDNSPlatformOneSecond*4);
3534 					q->ThisQInterval  = InitialQuestionInterval;
3535 					SetNextQueryTime(m,q);
3536 					}
3537 				}
3538 			verbosedebugf("CacheRecordAdd %p %##s (%s) %lu %#a:%d question %p", rr, rr->resrec.name->c,
3539 				DNSTypeName(rr->resrec.rrtype), rr->resrec.rroriginalttl, rr->resrec.rDNSServer ?
3540 				&rr->resrec.rDNSServer->addr : mDNSNULL, mDNSVal16(rr->resrec.rDNSServer ?
3541 				rr->resrec.rDNSServer->port : zeroIPPort), q);
3542 			q->CurrentAnswers++;
3543 			q->unansweredQueries = 0;
3544 			if (rr->resrec.rdlength > SmallRecordLimit) q->LargeAnswers++;
3545 			if (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) q->UniqueAnswers++;
3546 			if (q->CurrentAnswers > 4000)
3547 				{
3548 				static int msgcount = 0;
3549 				if (msgcount++ < 10)
3550 					LogMsg("CacheRecordAdd: %##s (%s) has %d answers; shedding records to resist DOS attack",
3551 						q->qname.c, DNSTypeName(q->qtype), q->CurrentAnswers);
3552 				rr->resrec.rroriginalttl = 0;
3553 				rr->UnansweredQueries = MaxUnansweredQueries;
3554 				}
3555 			}
3556 		}
3557 
3558 	if (!rr->DelayDelivery)
3559 		{
3560 		if (m->CurrentQuestion)
3561 			LogMsg("CacheRecordAdd ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
3562 		m->CurrentQuestion = m->Questions;
3563 		while (m->CurrentQuestion && m->CurrentQuestion != m->NewQuestions)
3564 			{
3565 			q = m->CurrentQuestion;
3566 			if (ResourceRecordAnswersQuestion(&rr->resrec, q))
3567 				AnswerCurrentQuestionWithResourceRecord(m, rr, QC_add);
3568 			if (m->CurrentQuestion == q)	// If m->CurrentQuestion was not auto-advanced, do it ourselves now
3569 				m->CurrentQuestion = q->next;
3570 			}
3571 		m->CurrentQuestion = mDNSNULL;
3572 		}
3573 
3574 	SetNextCacheCheckTimeForRecord(m, rr);
3575 	}
3576 
3577 // NoCacheAnswer is only called from mDNSCoreReceiveResponse, *never* directly as a result of a client API call.
3578 // If new questions are created as a result of invoking client callbacks, they will be added to
3579 // the end of the question list, and m->NewQuestions will be set to indicate the first new question.
3580 // rr is a new CacheRecord just received from the wire (kDNSRecordTypePacketAns/AnsUnique/Add/AddUnique)
3581 // but we don't have any place to cache it. We'll deliver question 'add' events now, but we won't have any
3582 // way to deliver 'remove' events in future, nor will we be able to include this in known-answer lists,
3583 // so we immediately bump ThisQInterval up to MaxQuestionInterval to avoid pounding the network.
3584 // Note: NoCacheAnswer calls AnswerCurrentQuestionWithResourceRecord which can call a user callback,
3585 // which may change the record list and/or question list.
3586 // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this.
NoCacheAnswer(mDNS * const m,CacheRecord * rr)3587 mDNSlocal void NoCacheAnswer(mDNS *const m, CacheRecord *rr)
3588 	{
3589 	LogMsg("No cache space: Delivering non-cached result for %##s", m->rec.r.resrec.name->c);
3590 	if (m->CurrentQuestion)
3591 		LogMsg("NoCacheAnswer ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
3592 	m->CurrentQuestion = m->Questions;
3593 	// We do this for *all* questions, not stopping when we get to m->NewQuestions,
3594 	// since we're not caching the record and we'll get no opportunity to do this later
3595 	while (m->CurrentQuestion)
3596 		{
3597 		DNSQuestion *q = m->CurrentQuestion;
3598 		if (ResourceRecordAnswersQuestion(&rr->resrec, q))
3599 			AnswerCurrentQuestionWithResourceRecord(m, rr, QC_addnocache);	// QC_addnocache means "don't expect remove events for this"
3600 		if (m->CurrentQuestion == q)	// If m->CurrentQuestion was not auto-advanced, do it ourselves now
3601 			m->CurrentQuestion = q->next;
3602 		}
3603 	m->CurrentQuestion = mDNSNULL;
3604 	}
3605 
3606 // CacheRecordRmv is only called from CheckCacheExpiration, which is called from mDNS_Execute.
3607 // Note that CacheRecordRmv is *only* called for records that are referenced by at least one active question.
3608 // If new questions are created as a result of invoking client callbacks, they will be added to
3609 // the end of the question list, and m->NewQuestions will be set to indicate the first new question.
3610 // rr is an existing cache CacheRecord that just expired and is being deleted
3611 // (kDNSRecordTypePacketAns/PacketAnsUnique/PacketAdd/PacketAddUnique).
3612 // Note: CacheRecordRmv calls AnswerCurrentQuestionWithResourceRecord which can call a user callback,
3613 // which may change the record list and/or question list.
3614 // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this.
CacheRecordRmv(mDNS * const m,CacheRecord * rr)3615 mDNSlocal void CacheRecordRmv(mDNS *const m, CacheRecord *rr)
3616 	{
3617 	if (m->CurrentQuestion)
3618 		LogMsg("CacheRecordRmv ERROR m->CurrentQuestion already set: %##s (%s)",
3619 			m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
3620 	m->CurrentQuestion = m->Questions;
3621 
3622 	// We stop when we get to NewQuestions -- for new questions their CurrentAnswers/LargeAnswers/UniqueAnswers counters
3623 	// will all still be zero because we haven't yet gone through the cache counting how many answers we have for them.
3624 	while (m->CurrentQuestion && m->CurrentQuestion != m->NewQuestions)
3625 		{
3626 		DNSQuestion *q = m->CurrentQuestion;
3627 		// When a question enters suppressed state, we generate RMV events and generate a negative
3628 		// response. A cache may be present that answers this question e.g., cache entry generated
3629 		// before the question became suppressed. We need to skip the suppressed questions here as
3630 		// the RMV event has already been generated.
3631 		if (!QuerySuppressed(q) && ResourceRecordAnswersQuestion(&rr->resrec, q))
3632 			{
3633 			verbosedebugf("CacheRecordRmv %p %s", rr, CRDisplayString(m, rr));
3634 			q->FlappingInterface1 = mDNSNULL;
3635 			q->FlappingInterface2 = mDNSNULL;
3636 
3637 			// When a question changes DNS server, it is marked with deliverAddEvents if we find any
3638 			// cache entry corresponding to the new DNS server. Before we deliver the ADD event, the
3639 			// cache entry may be removed in which case CurrentAnswers can be zero.
3640 			if (q->deliverAddEvents && !q->CurrentAnswers)
3641 				{
3642 				LogInfo("CacheRecordRmv: Question %p %##s (%s) deliverAddEvents set, DNSServer %#a:%d",
3643 					q, q->qname.c, DNSTypeName(q->qtype), q->qDNSServer ? &q->qDNSServer->addr : mDNSNULL,
3644 					mDNSVal16(q->qDNSServer ? q->qDNSServer->port : zeroIPPort));
3645 				m->CurrentQuestion = q->next;
3646 				continue;
3647 				}
3648 			if (q->CurrentAnswers == 0)
3649 				LogMsg("CacheRecordRmv ERROR!!: How can CurrentAnswers already be zero for %p %##s (%s) DNSServer %#a:%d",
3650 					q, q->qname.c, DNSTypeName(q->qtype), q->qDNSServer ? &q->qDNSServer->addr : mDNSNULL,
3651 					mDNSVal16(q->qDNSServer ? q->qDNSServer->port : zeroIPPort));
3652 			else
3653 				{
3654 				q->CurrentAnswers--;
3655 				if (rr->resrec.rdlength > SmallRecordLimit) q->LargeAnswers--;
3656 				if (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) q->UniqueAnswers--;
3657 				}
3658 			if (rr->resrec.rdata->MaxRDLength) // Never generate "remove" events for negative results
3659 				{
3660 				if (q->CurrentAnswers == 0)
3661 					{
3662 					LogInfo("CacheRecordRmv: Last answer for %##s (%s) expired from cache; will reconfirm antecedents",
3663 						q->qname.c, DNSTypeName(q->qtype));
3664 					ReconfirmAntecedents(m, &q->qname, q->qnamehash, 0);
3665 					}
3666 				AnswerCurrentQuestionWithResourceRecord(m, rr, QC_rmv);
3667 				}
3668 			}
3669 		if (m->CurrentQuestion == q)	// If m->CurrentQuestion was not auto-advanced, do it ourselves now
3670 			m->CurrentQuestion = q->next;
3671 		}
3672 	m->CurrentQuestion = mDNSNULL;
3673 	}
3674 
ReleaseCacheEntity(mDNS * const m,CacheEntity * e)3675 mDNSlocal void ReleaseCacheEntity(mDNS *const m, CacheEntity *e)
3676 	{
3677 #if APPLE_OSX_mDNSResponder && MACOSX_MDNS_MALLOC_DEBUGGING >= 1
3678 	unsigned int i;
3679 	for (i=0; i<sizeof(*e); i++) ((char*)e)[i] = 0xFF;
3680 #endif
3681 	e->next = m->rrcache_free;
3682 	m->rrcache_free = e;
3683 	m->rrcache_totalused--;
3684 	}
3685 
ReleaseCacheGroup(mDNS * const m,CacheGroup ** cp)3686 mDNSlocal void ReleaseCacheGroup(mDNS *const m, CacheGroup **cp)
3687 	{
3688 	CacheEntity *e = (CacheEntity *)(*cp);
3689 	//LogMsg("ReleaseCacheGroup:  Releasing CacheGroup for %p, %##s", (*cp)->name->c, (*cp)->name->c);
3690 	if ((*cp)->rrcache_tail != &(*cp)->members)
3691 		LogMsg("ERROR: (*cp)->members == mDNSNULL but (*cp)->rrcache_tail != &(*cp)->members)");
3692 	//if ((*cp)->name != (domainname*)((*cp)->namestorage))
3693 	//	LogMsg("ReleaseCacheGroup: %##s, %p %p", (*cp)->name->c, (*cp)->name, (domainname*)((*cp)->namestorage));
3694 	if ((*cp)->name != (domainname*)((*cp)->namestorage)) mDNSPlatformMemFree((*cp)->name);
3695 	(*cp)->name = mDNSNULL;
3696 	*cp = (*cp)->next;			// Cut record from list
3697 	ReleaseCacheEntity(m, e);
3698 	}
3699 
ReleaseCacheRecord(mDNS * const m,CacheRecord * r)3700 mDNSlocal void ReleaseCacheRecord(mDNS *const m, CacheRecord *r)
3701 	{
3702 	//LogMsg("ReleaseCacheRecord: Releasing %s", CRDisplayString(m, r));
3703 	if (r->resrec.rdata && r->resrec.rdata != (RData*)&r->smallrdatastorage) mDNSPlatformMemFree(r->resrec.rdata);
3704 	r->resrec.rdata = mDNSNULL;
3705 	ReleaseCacheEntity(m, (CacheEntity *)r);
3706 	}
3707 
3708 // Note: We want to be careful that we deliver all the CacheRecordRmv calls before delivering
3709 // CacheRecordDeferredAdd calls. The in-order nature of the cache lists ensures that all
3710 // callbacks for old records are delivered before callbacks for newer records.
CheckCacheExpiration(mDNS * const m,const mDNSu32 slot,CacheGroup * const cg)3711 mDNSlocal void CheckCacheExpiration(mDNS *const m, const mDNSu32 slot, CacheGroup *const cg)
3712 	{
3713 	CacheRecord **rp = &cg->members;
3714 
3715 	if (m->lock_rrcache) { LogMsg("CheckCacheExpiration ERROR! Cache already locked!"); return; }
3716 	m->lock_rrcache = 1;
3717 
3718 	while (*rp)
3719 		{
3720 		CacheRecord *const rr = *rp;
3721 		mDNSs32 event = RRExpireTime(rr);
3722 		if (m->timenow - event >= 0)	// If expired, delete it
3723 			{
3724 			*rp = rr->next;				// Cut it from the list
3725 			verbosedebugf("CheckCacheExpiration: Deleting%7d %7d %p %s",
3726 				m->timenow - rr->TimeRcvd, rr->resrec.rroriginalttl, rr->CRActiveQuestion, CRDisplayString(m, rr));
3727 			if (rr->CRActiveQuestion)	// If this record has one or more active questions, tell them it's going away
3728 				{
3729 				DNSQuestion *q = rr->CRActiveQuestion;
3730 				// When a cache record is about to expire, we expect to do four queries at 80-82%, 85-87%, 90-92% and
3731 				// then 95-97% of the TTL. If the DNS server does not respond, then we will remove the cache entry
3732 				// before we pick a new DNS server. As the question interval is set to MaxQuestionInterval, we may
3733 				// not send out a query anytime soon. Hence, we need to reset the question interval. If this is
3734 				// a normal deferred ADD case, then AnswerCurrentQuestionWithResourceRecord will reset it to
3735 				// MaxQuestionInterval. If we have inactive questions referring to negative cache entries,
3736 				// don't ressurect them as they will deliver duplicate "No such Record" ADD events
3737 				if (!mDNSOpaque16IsZero(q->TargetQID) && !q->LongLived && ActiveQuestion(q))
3738 					{
3739 					q->ThisQInterval = InitialQuestionInterval;
3740 					q->LastQTime     = m->timenow - q->ThisQInterval;
3741 					SetNextQueryTime(m, q);
3742 					}
3743 				CacheRecordRmv(m, rr);
3744 				m->rrcache_active--;
3745 				}
3746 			ReleaseCacheRecord(m, rr);
3747 			}
3748 		else							// else, not expired; see if we need to query
3749 			{
3750 			// If waiting to delay delivery, do nothing until then
3751 			if (rr->DelayDelivery && rr->DelayDelivery - m->timenow > 0)
3752 				event = rr->DelayDelivery;
3753 			else
3754 				{
3755 				if (rr->DelayDelivery) CacheRecordDeferredAdd(m, rr);
3756 				if (rr->CRActiveQuestion && rr->UnansweredQueries < MaxUnansweredQueries)
3757 					{
3758 					if (m->timenow - rr->NextRequiredQuery < 0)		// If not yet time for next query
3759 						event = NextCacheCheckEvent(rr);			// then just record when we want the next query
3760 					else											// else trigger our question to go out now
3761 						{
3762 						// Set NextScheduledQuery to timenow so that SendQueries() will run.
3763 						// SendQueries() will see that we have records close to expiration, and send FEQs for them.
3764 						m->NextScheduledQuery = m->timenow;
3765 						// After sending the query we'll increment UnansweredQueries and call SetNextCacheCheckTimeForRecord(),
3766 						// which will correctly update m->NextCacheCheck for us.
3767 						event = m->timenow + 0x3FFFFFFF;
3768 						}
3769 					}
3770 				}
3771 			verbosedebugf("CheckCacheExpiration:%6d %5d %s",
3772 				(event - m->timenow) / mDNSPlatformOneSecond, CacheCheckGracePeriod(rr), CRDisplayString(m, rr));
3773 			if (m->rrcache_nextcheck[slot] - event > 0)
3774 				m->rrcache_nextcheck[slot] = event;
3775 			rp = &rr->next;
3776 			}
3777 		}
3778 	if (cg->rrcache_tail != rp) verbosedebugf("CheckCacheExpiration: Updating CacheGroup tail from %p to %p", cg->rrcache_tail, rp);
3779 	cg->rrcache_tail = rp;
3780 	m->lock_rrcache = 0;
3781 	}
3782 
AnswerNewQuestion(mDNS * const m)3783 mDNSlocal void AnswerNewQuestion(mDNS *const m)
3784 	{
3785 	mDNSBool ShouldQueryImmediately = mDNStrue;
3786 	DNSQuestion *const q = m->NewQuestions;		// Grab the question we're going to answer
3787 	mDNSu32 slot = HashSlot(&q->qname);
3788 	CacheGroup *const cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname);
3789 	AuthRecord *lr;
3790 	AuthGroup *ag;
3791 	mDNSBool AnsweredFromCache = mDNSfalse;
3792 
3793 	verbosedebugf("AnswerNewQuestion: Answering %##s (%s)", q->qname.c, DNSTypeName(q->qtype));
3794 
3795 	if (cg) CheckCacheExpiration(m, slot, cg);
3796 	if (m->NewQuestions != q) { LogInfo("AnswerNewQuestion: Question deleted while doing CheckCacheExpiration"); goto exit; }
3797 	m->NewQuestions = q->next;
3798 	// Advance NewQuestions to the next *after* calling CheckCacheExpiration, because if we advance it first
3799 	// then CheckCacheExpiration may give this question add/remove callbacks, and it's not yet ready for that.
3800 	//
3801 	// Also, CheckCacheExpiration() calls CacheRecordDeferredAdd() and CacheRecordRmv(), which invoke
3802 	// client callbacks, which may delete their own or any other question. Our mechanism for detecting
3803 	// whether our current m->NewQuestions question got deleted by one of these callbacks is to store the
3804 	// value of m->NewQuestions in 'q' before calling CheckCacheExpiration(), and then verify afterwards
3805 	// that they're still the same. If m->NewQuestions has changed (because mDNS_StopQuery_internal
3806 	// advanced it), that means the question was deleted, so we no longer need to worry about answering
3807 	// it (and indeed 'q' is now a dangling pointer, so dereferencing it at all would be bad, and the
3808 	// values we computed for slot and cg are now stale and relate to a question that no longer exists).
3809 	//
3810 	// We can't use the usual m->CurrentQuestion mechanism for this because  CacheRecordDeferredAdd() and
3811 	// CacheRecordRmv() both use that themselves when walking the list of (non-new) questions generating callbacks.
3812 	// Fortunately mDNS_StopQuery_internal auto-advances both m->CurrentQuestion *AND* m->NewQuestions when
3813 	// deleting a question, so luckily we have an easy alternative way of detecting if our question got deleted.
3814 
3815 	if (m->lock_rrcache) LogMsg("AnswerNewQuestion ERROR! Cache already locked!");
3816 	// This should be safe, because calling the client's question callback may cause the
3817 	// question list to be modified, but should not ever cause the rrcache list to be modified.
3818 	// If the client's question callback deletes the question, then m->CurrentQuestion will
3819 	// be advanced, and we'll exit out of the loop
3820 	m->lock_rrcache = 1;
3821 	if (m->CurrentQuestion)
3822 		LogMsg("AnswerNewQuestion ERROR m->CurrentQuestion already set: %##s (%s)",
3823 			m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
3824 	m->CurrentQuestion = q;		// Indicate which question we're answering, so we'll know if it gets deleted
3825 
3826 	if (q->NoAnswer == NoAnswer_Fail)
3827 		{
3828 		LogMsg("AnswerNewQuestion: NoAnswer_Fail %##s (%s)", q->qname.c, DNSTypeName(q->qtype));
3829 		MakeNegativeCacheRecord(m, &m->rec.r, &q->qname, q->qnamehash, q->qtype, q->qclass, 60, mDNSInterface_Any, q->qDNSServer);
3830 		q->NoAnswer = NoAnswer_Normal;		// Temporarily turn off answer suppression
3831 		AnswerCurrentQuestionWithResourceRecord(m, &m->rec.r, QC_addnocache);
3832 		// Don't touch the question if it has been stopped already
3833 		if (m->CurrentQuestion == q) q->NoAnswer = NoAnswer_Fail;		// Restore NoAnswer state
3834 		m->rec.r.resrec.RecordType = 0;		// Clear RecordType to show we're not still using it
3835 		}
3836 	if (m->CurrentQuestion != q) { LogInfo("AnswerNewQuestion: Question deleted while generating NoAnswer_Fail response"); goto exit; }
3837 
3838 	// See if we want to tell it about LocalOnly records
3839 	if (m->CurrentRecord)
3840 		LogMsg("AnswerNewQuestion ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord));
3841 	slot = AuthHashSlot(&q->qname);
3842 	ag = AuthGroupForName(&m->rrauth, slot, q->qnamehash, &q->qname);
3843 	if (ag)
3844 		{
3845 		m->CurrentRecord = ag->members;
3846 		while (m->CurrentRecord && m->CurrentRecord != ag->NewLocalOnlyRecords)
3847 			{
3848 			AuthRecord *rr = m->CurrentRecord;
3849 			m->CurrentRecord = rr->next;
3850 			//
3851 			// If the question is mDNSInterface_LocalOnly, all records local to the machine should be used
3852 			// to answer the query. This is handled in AnswerNewLocalOnlyQuestion.
3853 			//
3854 			// We handle mDNSInterface_Any and scoped questions here. See LocalOnlyRecordAnswersQuestion for more
3855 			// details on how we handle this case. For P2P we just handle "Interface_Any" questions. For LocalOnly
3856 			// we handle both mDNSInterface_Any and scoped questions.
3857 
3858 			if (rr->ARType == AuthRecordLocalOnly || (rr->ARType == AuthRecordP2P && q->InterfaceID == mDNSInterface_Any))
3859 				if (LocalOnlyRecordAnswersQuestion(rr, q))
3860 					{
3861 					AnswerLocalQuestionWithLocalAuthRecord(m, rr, mDNStrue);
3862 					if (m->CurrentQuestion != q) break;		// If callback deleted q, then we're finished here
3863 					}
3864 			}
3865 		}
3866 	m->CurrentRecord = mDNSNULL;
3867 
3868 	if (m->CurrentQuestion != q) { LogInfo("AnswerNewQuestion: Question deleted while while giving LocalOnly record answers"); goto exit; }
3869 
3870 	if (q->LOAddressAnswers)
3871 		{
3872 		LogInfo("AnswerNewQuestion: Question %p %##s (%s) answered using local auth records LOAddressAnswers %d",
3873 			q, q->qname.c, DNSTypeName(q->qtype), q->LOAddressAnswers);
3874 		goto exit;
3875 		}
3876 
3877 	// Before we go check the cache and ship this query on the wire, we have to be sure that there are
3878 	// no local records that could possibly answer this question. As we did not check the NewLocalRecords, we
3879 	// need to just peek at them to see whether it will answer this question. If it would answer, pretend
3880 	// that we answered. AnswerAllLocalQuestionsWithLocalAuthRecord will answer shortly. This happens normally
3881 	// when we add new /etc/hosts entries and restart the question. It is a new question and also a new record.
3882 	if (ag)
3883 		{
3884 		lr = ag->NewLocalOnlyRecords;
3885 		while (lr)
3886 			{
3887 			if (LORecordAnswersAddressType(lr) && LocalOnlyRecordAnswersQuestion(lr, q))
3888 				{
3889 				LogInfo("AnswerNewQuestion: Question %p %##s (%s) will be answered using new local auth records "
3890 					" LOAddressAnswers %d", q, q->qname.c, DNSTypeName(q->qtype), q->LOAddressAnswers);
3891 				goto exit;
3892 				}
3893 			lr = lr->next;
3894 			}
3895 		}
3896 
3897 
3898 	// If we are not supposed to answer this question, generate a negative response.
3899 	// Temporarily suspend the SuppressQuery so that AnswerCurrentQuestionWithResourceRecord can answer the question
3900 	if (QuerySuppressed(q)) { q->SuppressQuery = mDNSfalse; GenerateNegativeResponse(m); q->SuppressQuery = mDNStrue; }
3901 	else
3902 		{
3903 		CacheRecord *rr;
3904 		for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next)
3905 			if (SameNameRecordAnswersQuestion(&rr->resrec, q))
3906 				{
3907 				// SecsSinceRcvd is whole number of elapsed seconds, rounded down
3908 				mDNSu32 SecsSinceRcvd = ((mDNSu32)(m->timenow - rr->TimeRcvd)) / mDNSPlatformOneSecond;
3909 				if (rr->resrec.rroriginalttl <= SecsSinceRcvd)
3910 					{
3911 					LogMsg("AnswerNewQuestion: How is rr->resrec.rroriginalttl %lu <= SecsSinceRcvd %lu for %s %d %d",
3912 						rr->resrec.rroriginalttl, SecsSinceRcvd, CRDisplayString(m, rr), m->timenow, rr->TimeRcvd);
3913 					continue;	// Go to next one in loop
3914 					}
3915 
3916 				// If this record set is marked unique, then that means we can reasonably assume we have the whole set
3917 				// -- we don't need to rush out on the network and query immediately to see if there are more answers out there
3918 				if ((rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) || (q->ExpectUnique))
3919 					ShouldQueryImmediately = mDNSfalse;
3920 				q->CurrentAnswers++;
3921 				if (rr->resrec.rdlength > SmallRecordLimit) q->LargeAnswers++;
3922 				if (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) q->UniqueAnswers++;
3923 				AnsweredFromCache = mDNStrue;
3924 				AnswerCurrentQuestionWithResourceRecord(m, rr, QC_add);
3925 				if (m->CurrentQuestion != q) break;		// If callback deleted q, then we're finished here
3926 				}
3927 			else if (RRTypeIsAddressType(rr->resrec.rrtype) && RRTypeIsAddressType(q->qtype))
3928 				ShouldQueryImmediately = mDNSfalse;
3929 		}
3930 	// We don't use LogInfo for this "Question deleted" message because it happens so routinely that
3931 	// it's not remotely remarkable, and therefore unlikely to be of much help tracking down bugs.
3932 	if (m->CurrentQuestion != q) { debugf("AnswerNewQuestion: Question deleted while giving cache answers"); goto exit; }
3933 
3934 	// Neither a local record nor a cache entry could answer this question. If this question need to be retried
3935 	// with search domains, generate a negative response which will now retry after appending search domains.
3936 	// If the query was suppressed above, we already generated a negative response. When it gets unsuppressed,
3937 	// we will retry with search domains.
3938 	if (!QuerySuppressed(q) && !AnsweredFromCache && q->RetryWithSearchDomains)
3939 		{
3940 		LogInfo("AnswerNewQuestion: Generating response for retrying with search domains %##s (%s)", q->qname.c, DNSTypeName(q->qtype));
3941 		GenerateNegativeResponse(m);
3942 		}
3943 
3944 	if (m->CurrentQuestion != q) { debugf("AnswerNewQuestion: Question deleted while giving negative answer"); goto exit; }
3945 
3946 	// Note: When a query gets suppressed or retried with search domains, we de-activate the question.
3947 	// Hence we don't execute the following block of code for those cases.
3948 	if (ShouldQueryImmediately && ActiveQuestion(q))
3949 		{
3950 		debugf("AnswerNewQuestion: ShouldQueryImmediately %##s (%s)", q->qname.c, DNSTypeName(q->qtype));
3951 		q->ThisQInterval  = InitialQuestionInterval;
3952 		q->LastQTime      = m->timenow - q->ThisQInterval;
3953 		if (mDNSOpaque16IsZero(q->TargetQID))		// For mDNS, spread packets to avoid a burst of simultaneous queries
3954 			{
3955 			// Compute random delay in the range 1-6 seconds, then divide by 50 to get 20-120ms
3956 			if (!m->RandomQueryDelay)
3957 				m->RandomQueryDelay = (mDNSPlatformOneSecond + mDNSRandom(mDNSPlatformOneSecond*5) - 1) / 50 + 1;
3958 			q->LastQTime += m->RandomQueryDelay;
3959 			}
3960 		}
3961 
3962 	// IN ALL CASES make sure that m->NextScheduledQuery is set appropriately.
3963 	// In cases where m->NewQuestions->DelayAnswering is set, we may have delayed generating our
3964 	// answers for this question until *after* its scheduled transmission time, in which case
3965 	// m->NextScheduledQuery may now be set to 'never', and in that case -- even though we're *not* doing
3966 	// ShouldQueryImmediately -- we still need to make sure we set m->NextScheduledQuery correctly.
3967 	SetNextQueryTime(m,q);
3968 
3969 exit:
3970 	m->CurrentQuestion = mDNSNULL;
3971 	m->lock_rrcache = 0;
3972 	}
3973 
3974 // When a NewLocalOnlyQuestion is created, AnswerNewLocalOnlyQuestion runs though our ResourceRecords delivering any
3975 // appropriate answers, stopping if it reaches a NewLocalOnlyRecord -- these will be handled by AnswerAllLocalQuestionsWithLocalAuthRecord
AnswerNewLocalOnlyQuestion(mDNS * const m)3976 mDNSlocal void AnswerNewLocalOnlyQuestion(mDNS *const m)
3977 	{
3978 	mDNSu32 slot;
3979 	AuthGroup *ag;
3980 	DNSQuestion *q = m->NewLocalOnlyQuestions;		// Grab the question we're going to answer
3981 	m->NewLocalOnlyQuestions = q->next;				// Advance NewLocalOnlyQuestions to the next (if any)
3982 
3983 	debugf("AnswerNewLocalOnlyQuestion: Answering %##s (%s)", q->qname.c, DNSTypeName(q->qtype));
3984 
3985 	if (m->CurrentQuestion)
3986 		LogMsg("AnswerNewLocalOnlyQuestion ERROR m->CurrentQuestion already set: %##s (%s)",
3987 			m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
3988 	m->CurrentQuestion = q;		// Indicate which question we're answering, so we'll know if it gets deleted
3989 
3990 	if (m->CurrentRecord)
3991 		LogMsg("AnswerNewLocalOnlyQuestion ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord));
3992 
3993 	// 1. First walk the LocalOnly records answering the LocalOnly question
3994 	// 2. As LocalOnly questions should also be answered by any other Auth records local to the machine,
3995 	//    walk the ResourceRecords list delivering the answers
3996 	slot = AuthHashSlot(&q->qname);
3997 	ag = AuthGroupForName(&m->rrauth, slot, q->qnamehash, &q->qname);
3998 	if (ag)
3999 		{
4000 		m->CurrentRecord = ag->members;
4001 		while (m->CurrentRecord && m->CurrentRecord != ag->NewLocalOnlyRecords)
4002 			{
4003 			AuthRecord *rr = m->CurrentRecord;
4004 			m->CurrentRecord = rr->next;
4005 			if (LocalOnlyRecordAnswersQuestion(rr, q))
4006 				{
4007 				AnswerLocalQuestionWithLocalAuthRecord(m, rr, mDNStrue);
4008 				if (m->CurrentQuestion != q) break;		// If callback deleted q, then we're finished here
4009 				}
4010 			}
4011 		}
4012 
4013 	if (m->CurrentQuestion == q)
4014 		{
4015 		m->CurrentRecord = m->ResourceRecords;
4016 
4017 		while (m->CurrentRecord && m->CurrentRecord != m->NewLocalRecords)
4018 			{
4019 			AuthRecord *rr = m->CurrentRecord;
4020 			m->CurrentRecord = rr->next;
4021 			if (ResourceRecordAnswersQuestion(&rr->resrec, q))
4022 				{
4023 				AnswerLocalQuestionWithLocalAuthRecord(m, rr, mDNStrue);
4024 				if (m->CurrentQuestion != q) break;		// If callback deleted q, then we're finished here
4025 				}
4026 			}
4027 		}
4028 
4029 	m->CurrentQuestion = mDNSNULL;
4030 	m->CurrentRecord   = mDNSNULL;
4031 	}
4032 
GetCacheEntity(mDNS * const m,const CacheGroup * const PreserveCG)4033 mDNSlocal CacheEntity *GetCacheEntity(mDNS *const m, const CacheGroup *const PreserveCG)
4034 	{
4035 	CacheEntity *e = mDNSNULL;
4036 
4037 	if (m->lock_rrcache) { LogMsg("GetFreeCacheRR ERROR! Cache already locked!"); return(mDNSNULL); }
4038 	m->lock_rrcache = 1;
4039 
4040 	// If we have no free records, ask the client layer to give us some more memory
4041 	if (!m->rrcache_free && m->MainCallback)
4042 		{
4043 		if (m->rrcache_totalused != m->rrcache_size)
4044 			LogMsg("GetFreeCacheRR: count mismatch: m->rrcache_totalused %lu != m->rrcache_size %lu",
4045 				m->rrcache_totalused, m->rrcache_size);
4046 
4047 		// We don't want to be vulnerable to a malicious attacker flooding us with an infinite
4048 		// number of bogus records so that we keep growing our cache until the machine runs out of memory.
4049 		// To guard against this, if our cache grows above 512kB (approx 3168 records at 164 bytes each),
4050 		// and we're actively using less than 1/32 of that cache, then we purge all the unused records
4051 		// and recycle them, instead of allocating more memory.
4052 		if (m->rrcache_size > 5000 && m->rrcache_size / 32 > m->rrcache_active)
4053 			LogInfo("Possible denial-of-service attack in progress: m->rrcache_size %lu; m->rrcache_active %lu",
4054 				m->rrcache_size, m->rrcache_active);
4055 		else
4056 			{
4057 			mDNS_DropLockBeforeCallback();		// Allow client to legally make mDNS API calls from the callback
4058 			m->MainCallback(m, mStatus_GrowCache);
4059 			mDNS_ReclaimLockAfterCallback();	// Decrement mDNS_reentrancy to block mDNS API calls again
4060 			}
4061 		}
4062 
4063 	// If we still have no free records, recycle all the records we can.
4064 	// Enumerating the entire cache is moderately expensive, so when we do it, we reclaim all the records we can in one pass.
4065 	if (!m->rrcache_free)
4066 		{
4067 		mDNSu32 oldtotalused = m->rrcache_totalused;
4068 		mDNSu32 slot;
4069 		for (slot = 0; slot < CACHE_HASH_SLOTS; slot++)
4070 			{
4071 			CacheGroup **cp = &m->rrcache_hash[slot];
4072 			while (*cp)
4073 				{
4074 				CacheRecord **rp = &(*cp)->members;
4075 				while (*rp)
4076 					{
4077 					// Records that answer still-active questions are not candidates for recycling
4078 					// Records that are currently linked into the CacheFlushRecords list may not be recycled, or we'll crash
4079 					if ((*rp)->CRActiveQuestion || (*rp)->NextInCFList)
4080 						rp=&(*rp)->next;
4081 					else
4082 						{
4083 						CacheRecord *rr = *rp;
4084 						*rp = (*rp)->next;			// Cut record from list
4085 						ReleaseCacheRecord(m, rr);
4086 						}
4087 					}
4088 				if ((*cp)->rrcache_tail != rp)
4089 					verbosedebugf("GetFreeCacheRR: Updating rrcache_tail[%lu] from %p to %p", slot, (*cp)->rrcache_tail, rp);
4090 				(*cp)->rrcache_tail = rp;
4091 				if ((*cp)->members || (*cp)==PreserveCG) cp=&(*cp)->next;
4092 				else ReleaseCacheGroup(m, cp);
4093 				}
4094 			}
4095 		LogInfo("GetCacheEntity recycled %d records to reduce cache from %d to %d",
4096 			oldtotalused - m->rrcache_totalused, oldtotalused, m->rrcache_totalused);
4097 		}
4098 
4099 	if (m->rrcache_free)	// If there are records in the free list, take one
4100 		{
4101 		e = m->rrcache_free;
4102 		m->rrcache_free = e->next;
4103 		if (++m->rrcache_totalused >= m->rrcache_report)
4104 			{
4105 			LogInfo("RR Cache now using %ld objects", m->rrcache_totalused);
4106 			if      (m->rrcache_report <  100) m->rrcache_report += 10;
4107 			else if (m->rrcache_report < 1000) m->rrcache_report += 100;
4108 			else                               m->rrcache_report += 1000;
4109 			}
4110 		mDNSPlatformMemZero(e, sizeof(*e));
4111 		}
4112 
4113 	m->lock_rrcache = 0;
4114 
4115 	return(e);
4116 	}
4117 
GetCacheRecord(mDNS * const m,CacheGroup * cg,mDNSu16 RDLength)4118 mDNSlocal CacheRecord *GetCacheRecord(mDNS *const m, CacheGroup *cg, mDNSu16 RDLength)
4119 	{
4120 	CacheRecord *r = (CacheRecord *)GetCacheEntity(m, cg);
4121 	if (r)
4122 		{
4123 		r->resrec.rdata = (RData*)&r->smallrdatastorage;	// By default, assume we're usually going to be using local storage
4124 		if (RDLength > InlineCacheRDSize)			// If RDLength is too big, allocate extra storage
4125 			{
4126 			r->resrec.rdata = (RData*)mDNSPlatformMemAllocate(sizeofRDataHeader + RDLength);
4127 			if (r->resrec.rdata) r->resrec.rdata->MaxRDLength = r->resrec.rdlength = RDLength;
4128 			else { ReleaseCacheEntity(m, (CacheEntity*)r); r = mDNSNULL; }
4129 			}
4130 		}
4131 	return(r);
4132 	}
4133 
GetCacheGroup(mDNS * const m,const mDNSu32 slot,const ResourceRecord * const rr)4134 mDNSlocal CacheGroup *GetCacheGroup(mDNS *const m, const mDNSu32 slot, const ResourceRecord *const rr)
4135 	{
4136 	mDNSu16 namelen = DomainNameLength(rr->name);
4137 	CacheGroup *cg = (CacheGroup*)GetCacheEntity(m, mDNSNULL);
4138 	if (!cg) { LogMsg("GetCacheGroup: Failed to allocate memory for %##s", rr->name->c); return(mDNSNULL); }
4139 	cg->next         = m->rrcache_hash[slot];
4140 	cg->namehash     = rr->namehash;
4141 	cg->members      = mDNSNULL;
4142 	cg->rrcache_tail = &cg->members;
4143 	cg->name         = (domainname*)cg->namestorage;
4144 	//LogMsg("GetCacheGroup: %-10s %d-byte cache name %##s",
4145 	//	(namelen > InlineCacheGroupNameSize) ? "Allocating" : "Inline", namelen, rr->name->c);
4146 	if (namelen > InlineCacheGroupNameSize) cg->name = mDNSPlatformMemAllocate(namelen);
4147 	if (!cg->name)
4148 		{
4149 		LogMsg("GetCacheGroup: Failed to allocate name storage for %##s", rr->name->c);
4150 		ReleaseCacheEntity(m, (CacheEntity*)cg);
4151 		return(mDNSNULL);
4152 		}
4153 	AssignDomainName(cg->name, rr->name);
4154 
4155 	if (CacheGroupForRecord(m, slot, rr)) LogMsg("GetCacheGroup: Already have CacheGroup for %##s", rr->name->c);
4156 	m->rrcache_hash[slot] = cg;
4157 	if (CacheGroupForRecord(m, slot, rr) != cg) LogMsg("GetCacheGroup: Not finding CacheGroup for %##s", rr->name->c);
4158 
4159 	return(cg);
4160 	}
4161 
mDNS_PurgeCacheResourceRecord(mDNS * const m,CacheRecord * rr)4162 mDNSexport void mDNS_PurgeCacheResourceRecord(mDNS *const m, CacheRecord *rr)
4163 	{
4164 	if (m->mDNS_busy != m->mDNS_reentrancy+1)
4165 		LogMsg("mDNS_PurgeCacheResourceRecord: Lock not held! mDNS_busy (%ld) mDNS_reentrancy (%ld)", m->mDNS_busy, m->mDNS_reentrancy);
4166 	// Make sure we mark this record as thoroughly expired -- we don't ever want to give
4167 	// a positive answer using an expired record (e.g. from an interface that has gone away).
4168 	// We don't want to clear CRActiveQuestion here, because that would leave the record subject to
4169 	// summary deletion without giving the proper callback to any questions that are monitoring it.
4170 	// By setting UnansweredQueries to MaxUnansweredQueries we ensure it won't trigger any further expiration queries.
4171 	rr->TimeRcvd          = m->timenow - mDNSPlatformOneSecond * 60;
4172 	rr->UnansweredQueries = MaxUnansweredQueries;
4173 	rr->resrec.rroriginalttl     = 0;
4174 	SetNextCacheCheckTimeForRecord(m, rr);
4175 	}
4176 
mDNS_TimeNow(const mDNS * const m)4177 mDNSexport mDNSs32 mDNS_TimeNow(const mDNS *const m)
4178 	{
4179 	mDNSs32 time;
4180 	mDNSPlatformLock(m);
4181 	if (m->mDNS_busy)
4182 		{
4183 		LogMsg("mDNS_TimeNow called while holding mDNS lock. This is incorrect. Code protected by lock should just use m->timenow.");
4184 		if (!m->timenow) LogMsg("mDNS_TimeNow: m->mDNS_busy is %ld but m->timenow not set", m->mDNS_busy);
4185 		}
4186 
4187 	if (m->timenow) time = m->timenow;
4188 	else            time = mDNS_TimeNow_NoLock(m);
4189 	mDNSPlatformUnlock(m);
4190 	return(time);
4191 	}
4192 
4193 // To avoid pointless CPU thrash, we use SetSPSProxyListChanged(X) to record the last interface that
4194 // had its Sleep Proxy client list change, and defer to actual BPF reconfiguration to mDNS_Execute().
4195 // (GetNextScheduledEvent() returns "now" when m->SPSProxyListChanged is set)
4196 #define SetSPSProxyListChanged(X) do { \
4197 	if (m->SPSProxyListChanged && m->SPSProxyListChanged != (X)) mDNSPlatformUpdateProxyList(m, m->SPSProxyListChanged); \
4198 	m->SPSProxyListChanged = (X); } while(0)
4199 
4200 // Called from mDNS_Execute() to expire stale proxy records
CheckProxyRecords(mDNS * const m,AuthRecord * list)4201 mDNSlocal void CheckProxyRecords(mDNS *const m, AuthRecord *list)
4202 	{
4203 	m->CurrentRecord = list;
4204 	while (m->CurrentRecord)
4205 		{
4206 		AuthRecord *rr = m->CurrentRecord;
4207 		if (rr->resrec.RecordType != kDNSRecordTypeDeregistering && rr->WakeUp.HMAC.l[0])
4208 			{
4209 			// If m->SPSSocket is NULL that means we're not acting as a sleep proxy any more,
4210 			// so we need to cease proxying for *all* records we may have, expired or not.
4211 			if (m->SPSSocket && m->timenow - rr->TimeExpire < 0)	// If proxy record not expired yet, update m->NextScheduledSPS
4212 				{
4213 				if (m->NextScheduledSPS - rr->TimeExpire > 0)
4214 					m->NextScheduledSPS = rr->TimeExpire;
4215 				}
4216 			else													// else proxy record expired, so remove it
4217 				{
4218 				LogSPS("CheckProxyRecords: Removing %d H-MAC %.6a I-MAC %.6a %d %s",
4219 					m->ProxyRecords, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, rr->WakeUp.seq, ARDisplayString(m, rr));
4220 				SetSPSProxyListChanged(rr->resrec.InterfaceID);
4221 				mDNS_Deregister_internal(m, rr, mDNS_Dereg_normal);
4222 				// Don't touch rr after this -- memory may have been free'd
4223 				}
4224 			}
4225 		// Mustn't advance m->CurrentRecord until *after* mDNS_Deregister_internal, because
4226 		// new records could have been added to the end of the list as a result of that call.
4227 		if (m->CurrentRecord == rr) // If m->CurrentRecord was not advanced for us, do it now
4228 			m->CurrentRecord = rr->next;
4229 		}
4230 	}
4231 
CheckRmvEventsForLocalRecords(mDNS * const m)4232 mDNSlocal void CheckRmvEventsForLocalRecords(mDNS *const m)
4233 	{
4234 	while (m->CurrentRecord)
4235 		{
4236 		AuthRecord *rr = m->CurrentRecord;
4237 		if (rr->AnsweredLocalQ && rr->resrec.RecordType == kDNSRecordTypeDeregistering)
4238 			{
4239 			debugf("CheckRmvEventsForLocalRecords: Generating local RMV events for %s", ARDisplayString(m, rr));
4240 			rr->resrec.RecordType = kDNSRecordTypeShared;
4241 			AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNSfalse);
4242 			if (m->CurrentRecord == rr)	// If rr still exists in list, restore its state now
4243 				{
4244 				rr->resrec.RecordType = kDNSRecordTypeDeregistering;
4245 				rr->AnsweredLocalQ = mDNSfalse;
4246 				// SendResponses normally calls CompleteDeregistration after sending goodbyes.
4247 				// For LocalOnly records, we don't do that and hence we need to do that here.
4248 				if (RRLocalOnly(rr)) CompleteDeregistration(m, rr);
4249 				}
4250 			}
4251 		if (m->CurrentRecord == rr)		// If m->CurrentRecord was not auto-advanced, do it ourselves now
4252 			m->CurrentRecord = rr->next;
4253 		}
4254 	}
4255 
TimeoutQuestions(mDNS * const m)4256 mDNSlocal void TimeoutQuestions(mDNS *const m)
4257 	{
4258 	m->NextScheduledStopTime = m->timenow + 0x3FFFFFFF;
4259 	if (m->CurrentQuestion)
4260 		LogMsg("TimeoutQuestions ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c,
4261 			DNSTypeName(m->CurrentQuestion->qtype));
4262 	m->CurrentQuestion = m->Questions;
4263 	while (m->CurrentQuestion)
4264 		{
4265 		DNSQuestion *const q = m->CurrentQuestion;
4266 		if (q->StopTime)
4267 			{
4268 			if (m->timenow - q->StopTime >= 0)
4269 				{
4270 				LogInfo("TimeoutQuestions: question %##s timed out, time %d", q->qname.c, m->timenow - q->StopTime);
4271 				GenerateNegativeResponse(m);
4272 				if (m->CurrentQuestion == q) q->StopTime = 0;
4273 				}
4274 			else
4275 				{
4276 				if (m->NextScheduledStopTime - q->StopTime > 0)
4277 					m->NextScheduledStopTime = q->StopTime;
4278 				}
4279 			}
4280 		// If m->CurrentQuestion wasn't modified out from under us, advance it now
4281 		// We can't do this at the start of the loop because GenerateNegativeResponse
4282 		// depends on having m->CurrentQuestion point to the right question
4283 		if (m->CurrentQuestion == q)
4284 			m->CurrentQuestion = q->next;
4285 		}
4286 	m->CurrentQuestion = mDNSNULL;
4287 	}
4288 
mDNS_Execute(mDNS * const m)4289 mDNSexport mDNSs32 mDNS_Execute(mDNS *const m)
4290 	{
4291 	mDNS_Lock(m);	// Must grab lock before trying to read m->timenow
4292 
4293 	if (m->timenow - m->NextScheduledEvent >= 0)
4294 		{
4295 		int i;
4296 		AuthRecord *head, *tail;
4297 		mDNSu32 slot;
4298 		AuthGroup *ag;
4299 
4300 		verbosedebugf("mDNS_Execute");
4301 
4302 		if (m->CurrentQuestion)
4303 			LogMsg("mDNS_Execute: ERROR m->CurrentQuestion already set: %##s (%s)",
4304 				m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
4305 
4306 		if (m->CurrentRecord)
4307 			LogMsg("mDNS_Execute: ERROR m->CurrentRecord already set: %s", ARDisplayString(m, m->CurrentRecord));
4308 
4309 		// 1. If we're past the probe suppression time, we can clear it
4310 		if (m->SuppressProbes && m->timenow - m->SuppressProbes >= 0) m->SuppressProbes = 0;
4311 
4312 		// 2. If it's been more than ten seconds since the last probe failure, we can clear the counter
4313 		if (m->NumFailedProbes && m->timenow - m->ProbeFailTime >= mDNSPlatformOneSecond * 10) m->NumFailedProbes = 0;
4314 
4315 		// 3. Purge our cache of stale old records
4316 		if (m->rrcache_size && m->timenow - m->NextCacheCheck >= 0)
4317 			{
4318 			mDNSu32 numchecked = 0;
4319 			m->NextCacheCheck = m->timenow + 0x3FFFFFFF;
4320 			for (slot = 0; slot < CACHE_HASH_SLOTS; slot++)
4321 				{
4322 				if (m->timenow - m->rrcache_nextcheck[slot] >= 0)
4323 					{
4324 					CacheGroup **cp = &m->rrcache_hash[slot];
4325 					m->rrcache_nextcheck[slot] = m->timenow + 0x3FFFFFFF;
4326 					while (*cp)
4327 						{
4328 						debugf("m->NextCacheCheck %4d Slot %3d %##s", numchecked, slot, *cp ? (*cp)->name : (domainname*)"\x04NULL");
4329 						numchecked++;
4330 						CheckCacheExpiration(m, slot, *cp);
4331 						if ((*cp)->members) cp=&(*cp)->next;
4332 						else ReleaseCacheGroup(m, cp);
4333 						}
4334 					}
4335 				// Even if we didn't need to actually check this slot yet, still need to
4336 				// factor its nextcheck time into our overall NextCacheCheck value
4337 				if (m->NextCacheCheck - m->rrcache_nextcheck[slot] > 0)
4338 					m->NextCacheCheck = m->rrcache_nextcheck[slot];
4339 				}
4340 			debugf("m->NextCacheCheck %4d checked, next in %d", numchecked, m->NextCacheCheck - m->timenow);
4341 			}
4342 
4343 		if (m->timenow - m->NextScheduledSPS >= 0)
4344 			{
4345 			m->NextScheduledSPS = m->timenow + 0x3FFFFFFF;
4346 			CheckProxyRecords(m, m->DuplicateRecords);	// Clear m->DuplicateRecords first, then m->ResourceRecords
4347 			CheckProxyRecords(m, m->ResourceRecords);
4348 			}
4349 
4350 		SetSPSProxyListChanged(mDNSNULL);		// Perform any deferred BPF reconfiguration now
4351 
4352 		// Clear AnnounceOwner if necessary. (Do this *before* SendQueries() and SendResponses().)
4353 		if (m->AnnounceOwner && m->timenow - m->AnnounceOwner >= 0) m->AnnounceOwner = 0;
4354 
4355 		if (m->DelaySleep && m->timenow - m->DelaySleep >= 0)
4356 			{
4357 			m->DelaySleep = 0;
4358 			if (m->SleepState == SleepState_Transferring)
4359 				{
4360 				LogSPS("Re-sleep delay passed; now checking for Sleep Proxy Servers");
4361 				BeginSleepProcessing(m);
4362 				}
4363 			}
4364 
4365 		// 4. See if we can answer any of our new local questions from the cache
4366 		for (i=0; m->NewQuestions && i<1000; i++)
4367 			{
4368 			if (m->NewQuestions->DelayAnswering && m->timenow - m->NewQuestions->DelayAnswering < 0) break;
4369 			AnswerNewQuestion(m);
4370 			}
4371 		if (i >= 1000) LogMsg("mDNS_Execute: AnswerNewQuestion exceeded loop limit");
4372 
4373 		// Make sure we deliver *all* local RMV events, and clear the corresponding rr->AnsweredLocalQ flags, *before*
4374 		// we begin generating *any* new ADD events in the m->NewLocalOnlyQuestions and m->NewLocalRecords loops below.
4375 		for (i=0; i<1000 && m->LocalRemoveEvents; i++)
4376 			{
4377 			m->LocalRemoveEvents = mDNSfalse;
4378 			m->CurrentRecord = m->ResourceRecords;
4379 			CheckRmvEventsForLocalRecords(m);
4380 			// Walk the LocalOnly records and deliver the RMV events
4381 			for (slot = 0; slot < AUTH_HASH_SLOTS; slot++)
4382 				for (ag = m->rrauth.rrauth_hash[slot]; ag; ag = ag->next)
4383 					{
4384 					m->CurrentRecord = ag->members;
4385 					if (m->CurrentRecord) CheckRmvEventsForLocalRecords(m);
4386 					}
4387 			}
4388 
4389 		if (i >= 1000) LogMsg("mDNS_Execute: m->LocalRemoveEvents exceeded loop limit");
4390 
4391 		for (i=0; m->NewLocalOnlyQuestions && i<1000; i++) AnswerNewLocalOnlyQuestion(m);
4392 		if (i >= 1000) LogMsg("mDNS_Execute: AnswerNewLocalOnlyQuestion exceeded loop limit");
4393 
4394 		head = tail = mDNSNULL;
4395 		for (i=0; i<1000 && m->NewLocalRecords && m->NewLocalRecords != head; i++)
4396 			{
4397 			AuthRecord *rr = m->NewLocalRecords;
4398 			m->NewLocalRecords = m->NewLocalRecords->next;
4399 			if (LocalRecordReady(rr))
4400 				{
4401 				debugf("mDNS_Execute: Delivering Add event with LocalAuthRecord %s", ARDisplayString(m, rr));
4402 				AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNStrue);
4403 				}
4404 			else if (!rr->next)
4405 				{
4406 				// If we have just one record that is not ready, we don't have to unlink and
4407 				// reinsert. As the NewLocalRecords will be NULL for this case, the loop will
4408 				// terminate and set the NewLocalRecords to rr.
4409 				debugf("mDNS_Execute: Just one LocalAuthRecord %s, breaking out of the loop early", ARDisplayString(m, rr));
4410 				if (head != mDNSNULL || m->NewLocalRecords != mDNSNULL)
4411 					LogMsg("mDNS_Execute: ERROR!!: head %p, NewLocalRecords %p", head, m->NewLocalRecords);
4412 
4413 				head = rr;
4414 				}
4415 			else
4416 				{
4417 				AuthRecord **p = &m->ResourceRecords;	// Find this record in our list of active records
4418 				debugf("mDNS_Execute: Skipping LocalAuthRecord %s", ARDisplayString(m, rr));
4419 				// if this is the first record we are skipping, move to the end of the list.
4420 				// if we have already skipped records before, append it at the end.
4421 				while (*p && *p != rr) p=&(*p)->next;
4422 				if (*p) *p = rr->next;					// Cut this record from the list
4423 				else { LogMsg("mDNS_Execute: ERROR!! Cannot find record %s in ResourceRecords list", ARDisplayString(m, rr)); break; }
4424 				if (!head)
4425 					{
4426 					while (*p) p=&(*p)->next;
4427 					*p = rr;
4428 					head = tail = rr;
4429 					}
4430 				else
4431 					{
4432 					tail->next = rr;
4433 					tail = rr;
4434 					}
4435 				rr->next = mDNSNULL;
4436 				}
4437 			}
4438 		m->NewLocalRecords = head;
4439 		// debugf("mDNS_Execute: Setting NewLocalRecords to %s", (head ? ARDisplayString(m, head) : "NULL"));
4440 
4441 		if (i >= 1000) LogMsg("mDNS_Execute: m->NewLocalRecords exceeded loop limit");
4442 
4443 		// Check to see if we have any new LocalOnly/P2P records to examine for delivering
4444 		// to our local questions
4445 		if (m->NewLocalOnlyRecords)
4446 			{
4447 			m->NewLocalOnlyRecords = mDNSfalse;
4448 			for (slot = 0; slot < AUTH_HASH_SLOTS; slot++)
4449 				for (ag = m->rrauth.rrauth_hash[slot]; ag; ag = ag->next)
4450 					{
4451 					for (i=0; i<100 && ag->NewLocalOnlyRecords; i++)
4452 						{
4453 						AuthRecord *rr = ag->NewLocalOnlyRecords;
4454 						ag->NewLocalOnlyRecords = ag->NewLocalOnlyRecords->next;
4455 						// LocalOnly records should always be ready as they never probe
4456 						if (LocalRecordReady(rr))
4457 							{
4458 							debugf("mDNS_Execute: Delivering Add event with LocalAuthRecord %s", ARDisplayString(m, rr));
4459 							AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNStrue);
4460 							}
4461 						else LogMsg("mDNS_Execute: LocalOnlyRecord %s not ready", ARDisplayString(m, rr));
4462 						}
4463 					// We limit about 100 per AuthGroup that can be serviced at a time
4464 					if (i >= 100) LogMsg("mDNS_Execute: ag->NewLocalOnlyRecords exceeded loop limit");
4465 					}
4466 			}
4467 
4468 		// 5. Some questions may have picked a new DNS server and the cache may answer these questions now.
4469 		AnswerQuestionsForDNSServerChanges(m);
4470 
4471 		// 6. See what packets we need to send
4472 		if (m->mDNSPlatformStatus != mStatus_NoError || (m->SleepState == SleepState_Sleeping))
4473 			DiscardDeregistrations(m);
4474 		if (m->mDNSPlatformStatus == mStatus_NoError && (m->SuppressSending == 0 || m->timenow - m->SuppressSending >= 0))
4475 			{
4476 			// If the platform code is ready, and we're not suppressing packet generation right now
4477 			// then send our responses, probes, and questions.
4478 			// We check the cache first, because there might be records close to expiring that trigger questions to refresh them.
4479 			// We send queries next, because there might be final-stage probes that complete their probing here, causing
4480 			// them to advance to announcing state, and we want those to be included in any announcements we send out.
4481 			// Finally, we send responses, including the previously mentioned records that just completed probing.
4482 			m->SuppressSending = 0;
4483 
4484 			// 7. Send Query packets. This may cause some probing records to advance to announcing state
4485 			if (m->timenow - m->NextScheduledQuery >= 0 || m->timenow - m->NextScheduledProbe >= 0) SendQueries(m);
4486 			if (m->timenow - m->NextScheduledQuery >= 0)
4487 				{
4488 				DNSQuestion *q;
4489 				LogMsg("mDNS_Execute: SendQueries didn't send all its queries (%d - %d = %d) will try again in one second",
4490 					m->timenow, m->NextScheduledQuery, m->timenow - m->NextScheduledQuery);
4491 				m->NextScheduledQuery = m->timenow + mDNSPlatformOneSecond;
4492 				for (q = m->Questions; q && q != m->NewQuestions; q=q->next)
4493 					if (ActiveQuestion(q) && m->timenow - NextQSendTime(q) >= 0)
4494 						LogMsg("mDNS_Execute: SendQueries didn't send %##s (%s)", q->qname.c, DNSTypeName(q->qtype));
4495 				}
4496 			if (m->timenow - m->NextScheduledProbe >= 0)
4497 				{
4498 				LogMsg("mDNS_Execute: SendQueries didn't send all its probes (%d - %d = %d) will try again in one second",
4499 					m->timenow, m->NextScheduledProbe, m->timenow - m->NextScheduledProbe);
4500 				m->NextScheduledProbe = m->timenow + mDNSPlatformOneSecond;
4501 				}
4502 
4503 			// 8. Send Response packets, including probing records just advanced to announcing state
4504 			if (m->timenow - m->NextScheduledResponse >= 0) SendResponses(m);
4505 			if (m->timenow - m->NextScheduledResponse >= 0)
4506 				{
4507 				LogMsg("mDNS_Execute: SendResponses didn't send all its responses; will try again in one second");
4508 				m->NextScheduledResponse = m->timenow + mDNSPlatformOneSecond;
4509 				}
4510 			}
4511 
4512 		// Clear RandomDelay values, ready to pick a new different value next time
4513 		m->RandomQueryDelay     = 0;
4514 		m->RandomReconfirmDelay = 0;
4515 
4516 		if (m->NextScheduledStopTime && m->timenow - m->NextScheduledStopTime >= 0) TimeoutQuestions(m);
4517 #ifndef UNICAST_DISABLED
4518 		if (m->NextSRVUpdate && m->timenow - m->NextSRVUpdate >= 0) UpdateAllSRVRecords(m);
4519 		if (m->timenow - m->NextScheduledNATOp >= 0) CheckNATMappings(m);
4520 		if (m->timenow - m->NextuDNSEvent >= 0) uDNS_Tasks(m);
4521 #endif
4522 		}
4523 
4524 	// Note about multi-threaded systems:
4525 	// On a multi-threaded system, some other thread could run right after the mDNS_Unlock(),
4526 	// performing mDNS API operations that change our next scheduled event time.
4527 	//
4528 	// On multi-threaded systems (like the current Windows implementation) that have a single main thread
4529 	// calling mDNS_Execute() (and other threads allowed to call mDNS API routines) it is the responsibility
4530 	// of the mDNSPlatformUnlock() routine to signal some kind of stateful condition variable that will
4531 	// signal whatever blocking primitive the main thread is using, so that it will wake up and execute one
4532 	// more iteration of its loop, and immediately call mDNS_Execute() again. The signal has to be stateful
4533 	// in the sense that if the main thread has not yet entered its blocking primitive, then as soon as it
4534 	// does, the state of the signal will be noticed, causing the blocking primitive to return immediately
4535 	// without blocking. This avoids the race condition between the signal from the other thread arriving
4536 	// just *before* or just *after* the main thread enters the blocking primitive.
4537 	//
4538 	// On multi-threaded systems (like the current Mac OS 9 implementation) that are entirely timer-driven,
4539 	// with no main mDNS_Execute() thread, it is the responsibility of the mDNSPlatformUnlock() routine to
4540 	// set the timer according to the m->NextScheduledEvent value, and then when the timer fires, the timer
4541 	// callback function should call mDNS_Execute() (and ignore the return value, which may already be stale
4542 	// by the time it gets to the timer callback function).
4543 
4544 	mDNS_Unlock(m);		// Calling mDNS_Unlock is what gives m->NextScheduledEvent its new value
4545 	return(m->NextScheduledEvent);
4546 	}
4547 
SuspendLLQs(mDNS * m)4548 mDNSlocal void SuspendLLQs(mDNS *m)
4549 	{
4550 	DNSQuestion *q;
4551 	for (q = m->Questions; q; q = q->next)
4552 		if (ActiveQuestion(q) && !mDNSOpaque16IsZero(q->TargetQID) && q->LongLived && q->state == LLQ_Established)
4553 			{ q->ReqLease = 0; sendLLQRefresh(m, q); }
4554 	}
4555 
QuestionHasLocalAnswers(mDNS * const m,DNSQuestion * q)4556 mDNSlocal mDNSBool QuestionHasLocalAnswers(mDNS *const m, DNSQuestion *q)
4557 	{
4558 	AuthRecord *rr;
4559 	mDNSu32 slot;
4560 	AuthGroup *ag;
4561 
4562 	slot = AuthHashSlot(&q->qname);
4563 	ag = AuthGroupForName(&m->rrauth, slot, q->qnamehash, &q->qname);
4564 	if (ag)
4565 		{
4566 		for (rr = ag->members; rr; rr=rr->next)
4567 			// Filter the /etc/hosts records - LocalOnly, Unique, A/AAAA/CNAME
4568 			if (LORecordAnswersAddressType(rr) && LocalOnlyRecordAnswersQuestion(rr, q))
4569 				{
4570 				LogInfo("QuestionHasLocalAnswers: Question %p %##s (%s) has local answer %s", q, q->qname.c, DNSTypeName(q->qtype), ARDisplayString(m, rr));
4571 				return mDNStrue;
4572 				}
4573 		}
4574 	return mDNSfalse;
4575 	}
4576 
4577 // ActivateUnicastQuery() is called from three places:
4578 // 1. When a new question is created
4579 // 2. On wake from sleep
4580 // 3. When the DNS configuration changes
4581 // In case 1 we don't want to mess with our established ThisQInterval and LastQTime (ScheduleImmediately is false)
4582 // In cases 2 and 3 we do want to cause the question to be resent immediately (ScheduleImmediately is true)
ActivateUnicastQuery(mDNS * const m,DNSQuestion * const question,mDNSBool ScheduleImmediately)4583 mDNSlocal void ActivateUnicastQuery(mDNS *const m, DNSQuestion *const question, mDNSBool ScheduleImmediately)
4584 	{
4585 	// For now this AutoTunnel stuff is specific to Mac OS X.
4586 	// In the future, if there's demand, we may see if we can abstract it out cleanly into the platform layer
4587 #if APPLE_OSX_mDNSResponder
4588 	// Even though BTMM client tunnels are only useful for AAAA queries, we need to treat v4 and v6 queries equally.
4589 	// Otherwise we can get the situation where the A query completes really fast (with an NXDOMAIN result) and the
4590 	// caller then gives up waiting for the AAAA result while we're still in the process of setting up the tunnel.
4591 	// To level the playing field, we block both A and AAAA queries while tunnel setup is in progress, and then
4592 	// returns results for both at the same time. If we are looking for the _autotunnel6 record, then skip this logic
4593 	// as this would trigger looking up _autotunnel6._autotunnel6 and end up failing the original query.
4594 
4595 	if (RRTypeIsAddressType(question->qtype) && PrivateQuery(question) &&
4596 		!SameDomainLabel(question->qname.c, (const mDNSu8 *)"\x0c_autotunnel6")&& question->QuestionCallback != AutoTunnelCallback)
4597 		{
4598 		question->NoAnswer = NoAnswer_Suspended;
4599 		AddNewClientTunnel(m, question);
4600 		return;
4601 		}
4602 #endif // APPLE_OSX_mDNSResponder
4603 
4604 	if (!question->DuplicateOf)
4605 		{
4606 		debugf("ActivateUnicastQuery: %##s %s%s%s",
4607 			question->qname.c, DNSTypeName(question->qtype), PrivateQuery(question) ? " (Private)" : "", ScheduleImmediately ? " ScheduleImmediately" : "");
4608 		question->CNAMEReferrals = 0;
4609 		if (question->nta) { CancelGetZoneData(m, question->nta); question->nta = mDNSNULL; }
4610 		if (question->LongLived)
4611 			{
4612 			question->state = LLQ_InitialRequest;
4613 			question->id = zeroOpaque64;
4614 			question->servPort = zeroIPPort;
4615 			if (question->tcp) { DisposeTCPConn(question->tcp); question->tcp = mDNSNULL; }
4616 			}
4617 		// If the question has local answers, then we don't want answers from outside
4618 		if (ScheduleImmediately && !QuestionHasLocalAnswers(m, question))
4619 			{
4620 			question->ThisQInterval = InitialQuestionInterval;
4621 			question->LastQTime     = m->timenow - question->ThisQInterval;
4622 			SetNextQueryTime(m, question);
4623 			}
4624 		}
4625 	}
4626 
4627 // Caller should hold the lock
mDNSCoreRestartAddressQueries(mDNS * const m,mDNSBool SearchDomainsChanged,FlushCache flushCacheRecords,CallbackBeforeStartQuery BeforeStartCallback,void * context)4628 mDNSexport void mDNSCoreRestartAddressQueries(mDNS *const m, mDNSBool SearchDomainsChanged, FlushCache flushCacheRecords,
4629 	CallbackBeforeStartQuery BeforeStartCallback, void *context)
4630 	{
4631 	DNSQuestion *q;
4632 	DNSQuestion *restart = mDNSNULL;
4633 
4634 	if (!m->mDNS_busy) LogMsg("mDNSCoreRestartAddressQueries: ERROR!! Lock not held");
4635 
4636 	// 1. Flush the cache records
4637 	if (flushCacheRecords) flushCacheRecords(m);
4638 
4639 	// 2. Even though we may have purged the cache records above, before it can generate RMV event
4640 	// we are going to stop the question. Hence we need to deliver the RMV event before we
4641 	// stop the question.
4642 	//
4643 	// CurrentQuestion is used by RmvEventsForQuestion below. While delivering RMV events, the
4644 	// application callback can potentially stop the current question (detected by CurrentQuestion) or
4645 	// *any* other question which could be the next one that we may process here. RestartQuestion
4646 	// points to the "next" question which will be automatically advanced in mDNS_StopQuery_internal
4647 	// if the "next" question is stopped while the CurrentQuestion is stopped
4648 
4649 	if (m->RestartQuestion)
4650 		LogMsg("mDNSCoreRestartAddressQueries: ERROR!! m->RestartQuestion already set: %##s (%s)",
4651 			m->RestartQuestion->qname.c, DNSTypeName(m->RestartQuestion->qtype));
4652 
4653 	m->RestartQuestion = m->Questions;
4654 	while (m->RestartQuestion)
4655 		{
4656 		q = m->RestartQuestion;
4657 		m->RestartQuestion = q->next;
4658 		// GetZoneData questions are referenced by other questions (original query that started the GetZoneData
4659 		// question)  through their "nta" pointer. Normally when the original query stops, it stops the
4660 		// GetZoneData question and also frees the memory (See CancelGetZoneData). If we stop the GetZoneData
4661 		// question followed by the original query that refers to this GetZoneData question, we will end up
4662 		// freeing the GetZoneData question and then start the "freed" question at the end.
4663 
4664 		if (IsGetZoneDataQuestion(q))
4665 			{
4666 			DNSQuestion *refq = q->next;
4667 			LogInfo("mDNSCoreRestartAddressQueries: Skipping GetZoneDataQuestion %p %##s (%s)", q, q->qname.c, DNSTypeName(q->qtype));
4668 			// debug stuff, we just try to find the referencing question and don't do much with it
4669 			while (refq)
4670 				{
4671 				if (q == &refq->nta->question)
4672 					{
4673 					LogInfo("mDNSCoreRestartAddressQueries: Question %p %##s (%s) referring to GetZoneDataQuestion %p, not stopping", refq, refq->qname.c, DNSTypeName(refq->qtype), q);
4674 					}
4675 				refq = refq->next;
4676 				}
4677 			continue;
4678 			}
4679 
4680 		// This function is called when /etc/hosts changes and that could affect A, AAAA and CNAME queries
4681 		if (q->qtype != kDNSType_A && q->qtype != kDNSType_AAAA && q->qtype != kDNSType_CNAME) continue;
4682 
4683 		// If the search domains did not change, then we restart all the queries. Otherwise, only
4684 		// for queries for which we "might" have appended search domains ("might" because we may
4685 		// find results before we apply search domains even though AppendSearchDomains is set to 1)
4686 		if (!SearchDomainsChanged || q->AppendSearchDomains)
4687 			{
4688 			// NOTE: CacheRecordRmvEventsForQuestion will not generate RMV events for queries that have non-zero
4689 			// LOAddressAnswers. Hence it is important that we call CacheRecordRmvEventsForQuestion before
4690 			// LocalRecordRmvEventsForQuestion (which decrements LOAddressAnswers). Let us say that
4691 			// /etc/hosts has an A Record for web.apple.com. Any queries for web.apple.com will be answered locally.
4692 			// But this can't prevent a CNAME/AAAA query to not to be sent on the wire. When it is sent on the wire,
4693 			// it could create cache entries. When we are restarting queries, we can't deliver the cache RMV events
4694 			// for the original query using these cache entries as ADDs were never delivered using these cache
4695 			// entries and hence this order is needed.
4696 
4697 			// If the query is suppressed, the RMV events won't be delivered
4698 			if (!CacheRecordRmvEventsForQuestion(m, q)) { LogInfo("mDNSCoreRestartAddressQueries: Question deleted while delivering Cache Record RMV events"); continue; }
4699 
4700 			// SuppressQuery status does not affect questions that are answered using local records
4701 			if (!LocalRecordRmvEventsForQuestion(m, q)) { LogInfo("mDNSCoreRestartAddressQueries: Question deleted while delivering Local Record RMV events"); continue; }
4702 
4703 			LogInfo("mDNSCoreRestartAddressQueries: Stop question %p %##s (%s), AppendSearchDomains %d, qnameOrig %p", q,
4704 				q->qname.c, DNSTypeName(q->qtype), q->AppendSearchDomains, q->qnameOrig);
4705 			mDNS_StopQuery_internal(m, q);
4706 			// Reset state so that it looks like it was in the beginning i.e it should look at /etc/hosts, cache
4707 			// and then search domains should be appended. At the beginning, qnameOrig was NULL.
4708 			if (q->qnameOrig)
4709 				{
4710 				LogInfo("mDNSCoreRestartAddressQueries: qnameOrig %##s", q->qnameOrig);
4711 				AssignDomainName(&q->qname, q->qnameOrig);
4712 				mDNSPlatformMemFree(q->qnameOrig);
4713 				q->qnameOrig = mDNSNULL;
4714 				q->RetryWithSearchDomains = ApplySearchDomainsFirst(q) ? 1 : 0;
4715 				}
4716 			q->SearchListIndex = 0;
4717 			q->next = restart;
4718 			restart = q;
4719 			}
4720 		}
4721 
4722 	// 3. Callback before we start the query
4723 	if (BeforeStartCallback) BeforeStartCallback(m, context);
4724 
4725 	// 4. Restart all the stopped queries
4726 	while (restart)
4727 		{
4728 		q = restart;
4729 		restart = restart->next;
4730 		q->next = mDNSNULL;
4731 		LogInfo("mDNSCoreRestartAddressQueries: Start question %p %##s (%s)", q, q->qname.c, DNSTypeName(q->qtype));
4732 		mDNS_StartQuery_internal(m, q);
4733 		}
4734 	}
4735 
mDNSCoreRestartQueries(mDNS * const m)4736 mDNSexport void mDNSCoreRestartQueries(mDNS *const m)
4737 	{
4738 	DNSQuestion *q;
4739 
4740 #ifndef UNICAST_DISABLED
4741 	// Retrigger all our uDNS questions
4742 	if (m->CurrentQuestion)
4743 		LogMsg("mDNSCoreRestartQueries: ERROR m->CurrentQuestion already set: %##s (%s)",
4744 			m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
4745 	m->CurrentQuestion = m->Questions;
4746 	while (m->CurrentQuestion)
4747 		{
4748 		q = m->CurrentQuestion;
4749 		m->CurrentQuestion = m->CurrentQuestion->next;
4750 		if (!mDNSOpaque16IsZero(q->TargetQID) && ActiveQuestion(q)) ActivateUnicastQuery(m, q, mDNStrue);
4751 		}
4752 #endif
4753 
4754 	// Retrigger all our mDNS questions
4755 	for (q = m->Questions; q; q=q->next)				// Scan our list of questions
4756 		if (mDNSOpaque16IsZero(q->TargetQID) && ActiveQuestion(q))
4757 			{
4758 			q->ThisQInterval    = InitialQuestionInterval;	// MUST be > zero for an active question
4759 			q->RequestUnicast   = 2;						// Set to 2 because is decremented once *before* we check it
4760 			q->LastQTime        = m->timenow - q->ThisQInterval;
4761 			q->RecentAnswerPkts = 0;
4762 			ExpireDupSuppressInfo(q->DupSuppress, m->timenow);
4763 			m->NextScheduledQuery = m->timenow;
4764 			}
4765 	}
4766 
4767 // ***************************************************************************
4768 #if COMPILER_LIKES_PRAGMA_MARK
4769 #pragma mark -
4770 #pragma mark - Power Management (Sleep/Wake)
4771 #endif
4772 
mDNS_UpdateAllowSleep(mDNS * const m)4773 mDNSexport void mDNS_UpdateAllowSleep(mDNS *const m)
4774 	{
4775 #ifndef IDLESLEEPCONTROL_DISABLED
4776 	mDNSBool allowSleep = mDNStrue;
4777 	char     reason[128];
4778 
4779 	reason[0] = 0;
4780 
4781 	if (m->SystemSleepOnlyIfWakeOnLAN)
4782 		{
4783 		// Don't sleep if we are a proxy for any services
4784 		if (m->ProxyRecords)
4785 			{
4786 			allowSleep = mDNSfalse;
4787 			mDNS_snprintf(reason, sizeof(reason), "sleep proxy for %d records", m->ProxyRecords);
4788 			LogInfo("Sleep disabled because we are proxying %d records", m->ProxyRecords);
4789 			}
4790 
4791 		if (allowSleep && mDNSCoreHaveAdvertisedMulticastServices(m))
4792 			{
4793 			// Scan the list of active interfaces
4794 			NetworkInterfaceInfo *intf;
4795 			for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next))
4796 				{
4797 				if (intf->McastTxRx && !intf->Loopback)
4798 					{
4799 					// Disallow sleep if this interface doesn't support NetWake
4800 					if (!intf->NetWake)
4801 						{
4802 						allowSleep = mDNSfalse;
4803 						mDNS_snprintf(reason, sizeof(reason), "%s does not support NetWake", intf->ifname);
4804 						LogInfo("Sleep disabled because %s does not support NetWake", intf->ifname);
4805 						break;
4806 						}
4807 
4808 					// Disallow sleep if there is no sleep proxy server
4809 					if (FindSPSInCache1(m, &intf->NetWakeBrowse, mDNSNULL, mDNSNULL) == mDNSNULL)
4810 						{
4811 						allowSleep = mDNSfalse;
4812 						mDNS_snprintf(reason, sizeof(reason), "%s does not support NetWake", intf->ifname);
4813 						LogInfo("Sleep disabled because %s has no sleep proxy", intf->ifname);
4814 						break;
4815 						}
4816 					}
4817 				}
4818 			}
4819 		}
4820 
4821 	// Call the platform code to enable/disable sleep
4822 	mDNSPlatformSetAllowSleep(m, allowSleep, reason);
4823 #endif /* !defined(IDLESLEEPCONTROL_DISABLED) */
4824 	}
4825 
SendSPSRegistrationForOwner(mDNS * const m,NetworkInterfaceInfo * const intf,const mDNSOpaque16 id,const OwnerOptData * const owner)4826 mDNSlocal void SendSPSRegistrationForOwner(mDNS *const m, NetworkInterfaceInfo *const intf, const mDNSOpaque16 id, const OwnerOptData *const owner)
4827 	{
4828 	const int optspace = DNSOpt_Header_Space + DNSOpt_LeaseData_Space + DNSOpt_Owner_Space(&m->PrimaryMAC, &intf->MAC);
4829 	const int sps = intf->NextSPSAttempt / 3;
4830 	AuthRecord *rr;
4831 
4832 	if (!intf->SPSAddr[sps].type)
4833 		{
4834 		intf->NextSPSAttemptTime = m->timenow + mDNSPlatformOneSecond;
4835 		if (m->NextScheduledSPRetry - intf->NextSPSAttemptTime > 0)
4836 			m->NextScheduledSPRetry = intf->NextSPSAttemptTime;
4837 		LogSPS("SendSPSRegistration: %s SPS %d (%d) %##s not yet resolved", intf->ifname, intf->NextSPSAttempt, sps, intf->NetWakeResolve[sps].qname.c);
4838 		goto exit;
4839 		}
4840 
4841 	// Mark our mDNS records (not unicast records) for transfer to SPS
4842 	if (mDNSOpaque16IsZero(id))
4843 		for (rr = m->ResourceRecords; rr; rr=rr->next)
4844 			if (rr->resrec.RecordType > kDNSRecordTypeDeregistering)
4845 				if (rr->resrec.InterfaceID == intf->InterfaceID || (!rr->resrec.InterfaceID && (rr->ForceMCast || IsLocalDomain(rr->resrec.name))))
4846 					if (mDNSPlatformMemSame(owner, &rr->WakeUp, sizeof(*owner)))
4847 						rr->SendRNow = mDNSInterfaceMark;	// mark it now
4848 
4849 	while (1)
4850 		{
4851 		mDNSu8 *p = m->omsg.data;
4852 		// To comply with RFC 2782, PutResourceRecord suppresses name compression for SRV records in unicast updates.
4853 		// For now we follow that same logic for SPS registrations too.
4854 		// If we decide to compress SRV records in SPS registrations in the future, we can achieve that by creating our
4855 		// initial DNSMessage with h.flags set to zero, and then update it to UpdateReqFlags right before sending the packet.
4856 		InitializeDNSMessage(&m->omsg.h, mDNSOpaque16IsZero(id) ? mDNS_NewMessageID(m) : id, UpdateReqFlags);
4857 
4858 		for (rr = m->ResourceRecords; rr; rr=rr->next)
4859 			if (rr->SendRNow || (!mDNSOpaque16IsZero(id) && !AuthRecord_uDNS(rr) && mDNSSameOpaque16(rr->updateid, id) && m->timenow - (rr->LastAPTime + rr->ThisAPInterval) >= 0))
4860 				if (mDNSPlatformMemSame(owner, &rr->WakeUp, sizeof(*owner)))
4861 					{
4862 					mDNSu8 *newptr;
4863 					const mDNSu8 *const limit = m->omsg.data + (m->omsg.h.mDNS_numUpdates ? NormalMaxDNSMessageData : AbsoluteMaxDNSMessageData) - optspace;
4864 					if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask)
4865 						rr->resrec.rrclass |= kDNSClass_UniqueRRSet;	// Temporarily set the 'unique' bit so PutResourceRecord will set it
4866 					newptr = PutResourceRecordTTLWithLimit(&m->omsg, p, &m->omsg.h.mDNS_numUpdates, &rr->resrec, rr->resrec.rroriginalttl, limit);
4867 					rr->resrec.rrclass &= ~kDNSClass_UniqueRRSet;		// Make sure to clear 'unique' bit back to normal state
4868 					if (!newptr)
4869 						LogSPS("SendSPSRegistration put %s FAILED %d/%d %s", intf->ifname, p - m->omsg.data, limit - m->omsg.data, ARDisplayString(m, rr));
4870 					else
4871 						{
4872 						LogSPS("SendSPSRegistration put %s %s", intf->ifname, ARDisplayString(m, rr));
4873 						rr->SendRNow       = mDNSNULL;
4874 						rr->ThisAPInterval = mDNSPlatformOneSecond;
4875 						rr->LastAPTime     = m->timenow;
4876 						rr->updateid       = m->omsg.h.id;
4877 						if (m->NextScheduledResponse - (rr->LastAPTime + rr->ThisAPInterval) >= 0)
4878 							m->NextScheduledResponse = (rr->LastAPTime + rr->ThisAPInterval);
4879 						p = newptr;
4880 						}
4881 					}
4882 
4883 		if (!m->omsg.h.mDNS_numUpdates) break;
4884 		else
4885 			{
4886 			AuthRecord opt;
4887 			mDNS_SetupResourceRecord(&opt, mDNSNULL, mDNSInterface_Any, kDNSType_OPT, kStandardTTL, kDNSRecordTypeKnownUnique, AuthRecordAny, mDNSNULL, mDNSNULL);
4888 			opt.resrec.rrclass    = NormalMaxDNSMessageData;
4889 			opt.resrec.rdlength   = sizeof(rdataOPT) * 2;	// Two options in this OPT record
4890 			opt.resrec.rdestimate = sizeof(rdataOPT) * 2;
4891 			opt.resrec.rdata->u.opt[0].opt           = kDNSOpt_Lease;
4892 			opt.resrec.rdata->u.opt[0].optlen        = DNSOpt_LeaseData_Space - 4;
4893 			opt.resrec.rdata->u.opt[0].u.updatelease = DEFAULT_UPDATE_LEASE;
4894 			if (!owner->HMAC.l[0])											// If no owner data,
4895 				SetupOwnerOpt(m, intf, &opt.resrec.rdata->u.opt[1]);		// use our own interface information
4896 			else															// otherwise, use the owner data we were given
4897 				{
4898 				opt.resrec.rdata->u.opt[1].u.owner = *owner;
4899 				opt.resrec.rdata->u.opt[1].opt     = kDNSOpt_Owner;
4900 				opt.resrec.rdata->u.opt[1].optlen  = DNSOpt_Owner_Space(&owner->HMAC, &owner->IMAC) - 4;
4901 				}
4902 			LogSPS("SendSPSRegistration put %s %s", intf->ifname, ARDisplayString(m, &opt));
4903 			p = PutResourceRecordTTLWithLimit(&m->omsg, p, &m->omsg.h.numAdditionals, &opt.resrec, opt.resrec.rroriginalttl, m->omsg.data + AbsoluteMaxDNSMessageData);
4904 			if (!p)
4905 				LogMsg("SendSPSRegistration: Failed to put OPT record (%d updates) %s", m->omsg.h.mDNS_numUpdates, ARDisplayString(m, &opt));
4906 			else
4907 				{
4908 				mStatus err;
4909 
4910 				LogSPS("SendSPSRegistration: Sending Update %s %d (%d) id %5d with %d records %d bytes to %#a:%d", intf->ifname, intf->NextSPSAttempt, sps,
4911 					mDNSVal16(m->omsg.h.id), m->omsg.h.mDNS_numUpdates, p - m->omsg.data, &intf->SPSAddr[sps], mDNSVal16(intf->SPSPort[sps]));
4912 				// if (intf->NextSPSAttempt < 5) m->omsg.h.flags = zeroID;	// For simulating packet loss
4913 				err = mDNSSendDNSMessage(m, &m->omsg, p, intf->InterfaceID, mDNSNULL, &intf->SPSAddr[sps], intf->SPSPort[sps], mDNSNULL, mDNSNULL);
4914 				if (err) LogSPS("SendSPSRegistration: mDNSSendDNSMessage err %d", err);
4915 				if (err && intf->SPSAddr[sps].type == mDNSAddrType_IPv6 && intf->NetWakeResolve[sps].ThisQInterval == -1)
4916 					{
4917 					LogSPS("SendSPSRegistration %d %##s failed to send to IPv6 address; will try IPv4 instead", sps, intf->NetWakeResolve[sps].qname.c);
4918 					intf->NetWakeResolve[sps].qtype = kDNSType_A;
4919 					mDNS_StartQuery_internal(m, &intf->NetWakeResolve[sps]);
4920 					return;
4921 					}
4922 				}
4923 			}
4924 		}
4925 
4926 	intf->NextSPSAttemptTime = m->timenow + mDNSPlatformOneSecond * 10;		// If successful, update NextSPSAttemptTime
4927 
4928 exit:
4929 	if (mDNSOpaque16IsZero(id) && intf->NextSPSAttempt < 8) intf->NextSPSAttempt++;
4930 	}
4931 
RecordIsFirstOccurrenceOfOwner(mDNS * const m,const AuthRecord * const rr)4932 mDNSlocal mDNSBool RecordIsFirstOccurrenceOfOwner(mDNS *const m, const AuthRecord *const rr)
4933 	{
4934 	AuthRecord *ar;
4935 	for (ar = m->ResourceRecords; ar && ar != rr; ar=ar->next)
4936 		if (mDNSPlatformMemSame(&rr->WakeUp, &ar->WakeUp, sizeof(rr->WakeUp))) return mDNSfalse;
4937 	return mDNStrue;
4938 	}
4939 
SendSPSRegistration(mDNS * const m,NetworkInterfaceInfo * const intf,const mDNSOpaque16 id)4940 mDNSlocal void SendSPSRegistration(mDNS *const m, NetworkInterfaceInfo *const intf, const mDNSOpaque16 id)
4941 	{
4942 	AuthRecord *ar;
4943 	OwnerOptData owner = zeroOwner;
4944 
4945 	SendSPSRegistrationForOwner(m, intf, id, &owner);
4946 
4947 	for (ar = m->ResourceRecords; ar; ar=ar->next)
4948 		{
4949 		if (!mDNSPlatformMemSame(&owner, &ar->WakeUp, sizeof(owner)) && RecordIsFirstOccurrenceOfOwner(m, ar))
4950 			{
4951 			owner = ar->WakeUp;
4952 			SendSPSRegistrationForOwner(m, intf, id, &owner);
4953 			}
4954 		}
4955 	}
4956 
4957 // RetrySPSRegistrations is called from SendResponses, with the lock held
RetrySPSRegistrations(mDNS * const m)4958 mDNSlocal void RetrySPSRegistrations(mDNS *const m)
4959 	{
4960 	AuthRecord *rr;
4961 	NetworkInterfaceInfo *intf;
4962 
4963 	// First make sure none of our interfaces' NextSPSAttemptTimes are inadvertently set to m->timenow + mDNSPlatformOneSecond * 10
4964 	for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next))
4965 		if (intf->NextSPSAttempt && intf->NextSPSAttemptTime == m->timenow + mDNSPlatformOneSecond * 10)
4966 			intf->NextSPSAttemptTime++;
4967 
4968 	// Retry any record registrations that are due
4969 	for (rr = m->ResourceRecords; rr; rr=rr->next)
4970 		if (!AuthRecord_uDNS(rr) && !mDNSOpaque16IsZero(rr->updateid) && m->timenow - (rr->LastAPTime + rr->ThisAPInterval) >= 0)
4971 			for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next))
4972 				if (!rr->resrec.InterfaceID || rr->resrec.InterfaceID == intf->InterfaceID)
4973 					{
4974 					LogSPS("RetrySPSRegistrations: %s", ARDisplayString(m, rr));
4975 					SendSPSRegistration(m, intf, rr->updateid);
4976 					}
4977 
4978 	// For interfaces where we did an SPS registration attempt, increment intf->NextSPSAttempt
4979 	for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next))
4980 		if (intf->NextSPSAttempt && intf->NextSPSAttemptTime == m->timenow + mDNSPlatformOneSecond * 10 && intf->NextSPSAttempt < 8)
4981 			intf->NextSPSAttempt++;
4982 	}
4983 
NetWakeResolve(mDNS * const m,DNSQuestion * question,const ResourceRecord * const answer,QC_result AddRecord)4984 mDNSlocal void NetWakeResolve(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord)
4985 	{
4986 	NetworkInterfaceInfo *intf = (NetworkInterfaceInfo *)question->QuestionContext;
4987 	int sps = (int)(question - intf->NetWakeResolve);
4988 	(void)m;			// Unused
4989 	LogSPS("NetWakeResolve: SPS: %d Add: %d %s", sps, AddRecord, RRDisplayString(m, answer));
4990 
4991 	if (!AddRecord) return;												// Don't care about REMOVE events
4992 	if (answer->rrtype != question->qtype) return;						// Don't care about CNAMEs
4993 
4994 	// if (answer->rrtype == kDNSType_AAAA && sps == 0) return;	// To test failing to resolve sleep proxy's address
4995 
4996 	if (answer->rrtype == kDNSType_SRV)
4997 		{
4998 		// 1. Got the SRV record; now look up the target host's IPv6 link-local address
4999 		mDNS_StopQuery(m, question);
5000 		intf->SPSPort[sps] = answer->rdata->u.srv.port;
5001 		AssignDomainName(&question->qname, &answer->rdata->u.srv.target);
5002 		question->qtype = kDNSType_AAAA;
5003 		mDNS_StartQuery(m, question);
5004 		}
5005 	else if (answer->rrtype == kDNSType_AAAA && answer->rdlength == sizeof(mDNSv6Addr) && mDNSv6AddressIsLinkLocal(&answer->rdata->u.ipv6))
5006 		{
5007 		// 2. Got the target host's IPv6 link-local address; record address and initiate an SPS registration if appropriate
5008 		mDNS_StopQuery(m, question);
5009 		question->ThisQInterval = -1;
5010 		intf->SPSAddr[sps].type = mDNSAddrType_IPv6;
5011 		intf->SPSAddr[sps].ip.v6 = answer->rdata->u.ipv6;
5012 		mDNS_Lock(m);
5013 		if (sps == intf->NextSPSAttempt/3) SendSPSRegistration(m, intf, zeroID);	// If we're ready for this result, use it now
5014 		mDNS_Unlock(m);
5015 		}
5016 	else if (answer->rrtype == kDNSType_AAAA && answer->rdlength == 0)
5017 		{
5018 		// 3. Got negative response -- target host apparently has IPv6 disabled -- so try looking up the target host's IPv4 address(es) instead
5019 		mDNS_StopQuery(m, question);
5020 		LogSPS("NetWakeResolve: SPS %d %##s has no IPv6 address, will try IPv4 instead", sps, question->qname.c);
5021 		question->qtype = kDNSType_A;
5022 		mDNS_StartQuery(m, question);
5023 		}
5024 	else if (answer->rrtype == kDNSType_A && answer->rdlength == sizeof(mDNSv4Addr))
5025 		{
5026 		// 4. Got an IPv4 address for the target host; record address and initiate an SPS registration if appropriate
5027 		mDNS_StopQuery(m, question);
5028 		question->ThisQInterval = -1;
5029 		intf->SPSAddr[sps].type = mDNSAddrType_IPv4;
5030 		intf->SPSAddr[sps].ip.v4 = answer->rdata->u.ipv4;
5031 		mDNS_Lock(m);
5032 		if (sps == intf->NextSPSAttempt/3) SendSPSRegistration(m, intf, zeroID);	// If we're ready for this result, use it now
5033 		mDNS_Unlock(m);
5034 		}
5035 	}
5036 
mDNSCoreHaveAdvertisedMulticastServices(mDNS * const m)5037 mDNSexport mDNSBool mDNSCoreHaveAdvertisedMulticastServices(mDNS *const m)
5038 	{
5039 	AuthRecord *rr;
5040 	for (rr = m->ResourceRecords; rr; rr=rr->next)
5041 		if (rr->resrec.rrtype == kDNSType_SRV && !AuthRecord_uDNS(rr) && !mDNSSameIPPort(rr->resrec.rdata->u.srv.port, DiscardPort))
5042 			return mDNStrue;
5043 	return mDNSfalse;
5044 	}
5045 
SendSleepGoodbyes(mDNS * const m)5046 mDNSlocal void SendSleepGoodbyes(mDNS *const m)
5047 	{
5048 	AuthRecord *rr;
5049 	m->SleepState = SleepState_Sleeping;
5050 
5051 #ifndef UNICAST_DISABLED
5052 	SleepRecordRegistrations(m);	// If we have no SPS, need to deregister our uDNS records
5053 #endif /* UNICAST_DISABLED */
5054 
5055 	// Mark all the records we need to deregister and send them
5056 	for (rr = m->ResourceRecords; rr; rr=rr->next)
5057 		if (rr->resrec.RecordType == kDNSRecordTypeShared && rr->RequireGoodbye)
5058 			rr->ImmedAnswer = mDNSInterfaceMark;
5059 	SendResponses(m);
5060 	}
5061 
5062 // BeginSleepProcessing is called, with the lock held, from either mDNS_Execute or mDNSCoreMachineSleep
BeginSleepProcessing(mDNS * const m)5063 mDNSlocal void BeginSleepProcessing(mDNS *const m)
5064 	{
5065 	mDNSBool SendGoodbyes = mDNStrue;
5066 	const CacheRecord *sps[3] = { mDNSNULL };
5067 
5068 	m->NextScheduledSPRetry = m->timenow;
5069 
5070 	if      (!m->SystemWakeOnLANEnabled)                  LogSPS("BeginSleepProcessing: m->SystemWakeOnLANEnabled is false");
5071 	else if (!mDNSCoreHaveAdvertisedMulticastServices(m)) LogSPS("BeginSleepProcessing: No advertised services");
5072 	else	// If we have at least one advertised service
5073 		{
5074 		NetworkInterfaceInfo *intf;
5075 		for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next))
5076 			{
5077 			if (!intf->NetWake) LogSPS("BeginSleepProcessing: %-6s not capable of magic packet wakeup", intf->ifname);
5078 #if APPLE_OSX_mDNSResponder
5079 			else if (ActivateLocalProxy(m, intf->ifname) == mStatus_NoError)
5080 				{
5081 				SendGoodbyes = mDNSfalse;
5082 				LogSPS("BeginSleepProcessing: %-6s using local proxy", intf->ifname);
5083 				// This will leave m->SleepState set to SleepState_Transferring,
5084 				// which is okay because with no outstanding resolves, or updates in flight,
5085 				// mDNSCoreReadyForSleep() will conclude correctly that all the updates have already completed
5086 				}
5087 #endif // APPLE_OSX_mDNSResponder
5088 			else
5089 				{
5090 				FindSPSInCache(m, &intf->NetWakeBrowse, sps);
5091 				if (!sps[0]) LogSPS("BeginSleepProcessing: %-6s %#a No Sleep Proxy Server found (Next Browse Q in %d, interval %d)",
5092 					intf->ifname, &intf->ip, NextQSendTime(&intf->NetWakeBrowse) - m->timenow, intf->NetWakeBrowse.ThisQInterval);
5093 				else
5094 					{
5095 					int i;
5096 					SendGoodbyes = mDNSfalse;
5097 					intf->NextSPSAttempt = 0;
5098 					intf->NextSPSAttemptTime = m->timenow + mDNSPlatformOneSecond;
5099 					// Don't need to set m->NextScheduledSPRetry here because we already set "m->NextScheduledSPRetry = m->timenow" above
5100 					for (i=0; i<3; i++)
5101 						{
5102 #if ForceAlerts
5103 						if (intf->SPSAddr[i].type)
5104 							{ LogMsg("BeginSleepProcessing: %s %d intf->SPSAddr[i].type %d", intf->ifname, i, intf->SPSAddr[i].type); *(long*)0 = 0; }
5105 						if (intf->NetWakeResolve[i].ThisQInterval >= 0)
5106 							{ LogMsg("BeginSleepProcessing: %s %d intf->NetWakeResolve[i].ThisQInterval %d", intf->ifname, i, intf->NetWakeResolve[i].ThisQInterval); *(long*)0 = 0; }
5107 #endif
5108 						intf->SPSAddr[i].type = mDNSAddrType_None;
5109 						if (intf->NetWakeResolve[i].ThisQInterval >= 0) mDNS_StopQuery(m, &intf->NetWakeResolve[i]);
5110 						intf->NetWakeResolve[i].ThisQInterval = -1;
5111 						if (sps[i])
5112 							{
5113 							LogSPS("BeginSleepProcessing: %-6s Found Sleep Proxy Server %d TTL %d %s", intf->ifname, i, sps[i]->resrec.rroriginalttl, CRDisplayString(m, sps[i]));
5114 							mDNS_SetupQuestion(&intf->NetWakeResolve[i], intf->InterfaceID, &sps[i]->resrec.rdata->u.name, kDNSType_SRV, NetWakeResolve, intf);
5115 							intf->NetWakeResolve[i].ReturnIntermed = mDNStrue;
5116 							mDNS_StartQuery_internal(m, &intf->NetWakeResolve[i]);
5117 							}
5118 						}
5119 					}
5120 				}
5121 			}
5122 		}
5123 
5124 	if (SendGoodbyes)	// If we didn't find even one Sleep Proxy
5125 		{
5126 		LogSPS("BeginSleepProcessing: Not registering with Sleep Proxy Server");
5127 		SendSleepGoodbyes(m);
5128 		}
5129 	}
5130 
5131 // Call mDNSCoreMachineSleep(m, mDNStrue) when the machine is about to go to sleep.
5132 // Call mDNSCoreMachineSleep(m, mDNSfalse) when the machine is has just woken up.
5133 // Normally, the platform support layer below mDNSCore should call this, not the client layer above.
mDNSCoreMachineSleep(mDNS * const m,mDNSBool sleep)5134 mDNSexport void mDNSCoreMachineSleep(mDNS *const m, mDNSBool sleep)
5135 	{
5136 	AuthRecord *rr;
5137 
5138 	LogSPS("%s (old state %d) at %ld", sleep ? "Sleeping" : "Waking", m->SleepState, m->timenow);
5139 
5140 	if (sleep && !m->SleepState)		// Going to sleep
5141 		{
5142 		mDNS_Lock(m);
5143 		// If we're going to sleep, need to stop advertising that we're a Sleep Proxy Server
5144 		if (m->SPSSocket)
5145 			{
5146 			mDNSu8 oldstate = m->SPSState;
5147 			mDNS_DropLockBeforeCallback();		// mDNS_DeregisterService expects to be called without the lock held, so we emulate that here
5148 			m->SPSState = 2;
5149 			if (oldstate == 1) mDNS_DeregisterService(m, &m->SPSRecords);
5150 			mDNS_ReclaimLockAfterCallback();
5151 			}
5152 
5153 		m->SleepState = SleepState_Transferring;
5154 		if (m->SystemWakeOnLANEnabled && m->DelaySleep)
5155 			{
5156 			// If we just woke up moments ago, allow ten seconds for networking to stabilize before going back to sleep
5157 			LogSPS("mDNSCoreMachineSleep: Re-sleeping immediately after waking; will delay for %d ticks", m->DelaySleep - m->timenow);
5158 			m->SleepLimit = NonZeroTime(m->DelaySleep + mDNSPlatformOneSecond * 10);
5159 			}
5160 		else
5161 			{
5162 			m->DelaySleep = 0;
5163 			m->SleepLimit = NonZeroTime(m->timenow + mDNSPlatformOneSecond * 10);
5164 			BeginSleepProcessing(m);
5165 			}
5166 
5167 #ifndef UNICAST_DISABLED
5168 		SuspendLLQs(m);
5169 #endif
5170 		mDNS_Unlock(m);
5171 		// RemoveAutoTunnel6Record needs to be called outside the lock, as it grabs the lock also.
5172 #if APPLE_OSX_mDNSResponder
5173 		RemoveAutoTunnel6Record(m);
5174 #endif
5175 		LogSPS("mDNSCoreMachineSleep: m->SleepState %d (%s) seq %d", m->SleepState,
5176 			m->SleepState == SleepState_Transferring ? "Transferring" :
5177 			m->SleepState == SleepState_Sleeping     ? "Sleeping"     : "?", m->SleepSeqNum);
5178 		}
5179 	else if (!sleep)		// Waking up
5180 		{
5181 		mDNSu32 slot;
5182 		CacheGroup *cg;
5183 		CacheRecord *cr;
5184 		NetworkInterfaceInfo *intf;
5185 
5186 		mDNS_Lock(m);
5187 		// Reset SleepLimit back to 0 now that we're awake again.
5188 		m->SleepLimit = 0;
5189 
5190 		// If we were previously sleeping, but now we're not, increment m->SleepSeqNum to indicate that we're entering a new period of wakefulness
5191 		if (m->SleepState != SleepState_Awake)
5192 			{
5193 			m->SleepState = SleepState_Awake;
5194 			m->SleepSeqNum++;
5195 			// If the machine wakes and then immediately tries to sleep again (e.g. a maintenance wake)
5196 			// then we enforce a minimum delay of 16 seconds before we begin sleep processing.
5197 			// This is to allow time for the Ethernet link to come up, DHCP to get an address, mDNS to issue queries, etc.,
5198 			// before we make our determination of whether there's a Sleep Proxy out there we should register with.
5199 			m->DelaySleep = NonZeroTime(m->timenow + mDNSPlatformOneSecond * 16);
5200 			}
5201 
5202 		if (m->SPSState == 3)
5203 			{
5204 			m->SPSState = 0;
5205 			mDNSCoreBeSleepProxyServer_internal(m, m->SPSType, m->SPSPortability, m->SPSMarginalPower, m->SPSTotalPower);
5206 			}
5207 
5208 		// In case we gave up waiting and went to sleep before we got an ack from the Sleep Proxy,
5209 		// on wake we go through our record list and clear updateid back to zero
5210 		for (rr = m->ResourceRecords; rr; rr=rr->next) rr->updateid = zeroID;
5211 
5212 		// ... and the same for NextSPSAttempt
5213 		for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next)) intf->NextSPSAttempt = -1;
5214 
5215 		// Restart unicast and multicast queries
5216 		mDNSCoreRestartQueries(m);
5217 
5218 		// and reactivtate service registrations
5219 		m->NextSRVUpdate = NonZeroTime(m->timenow + mDNSPlatformOneSecond);
5220 		LogInfo("mDNSCoreMachineSleep waking: NextSRVUpdate in %d %d", m->NextSRVUpdate - m->timenow, m->timenow);
5221 
5222 		// 2. Re-validate our cache records
5223 		FORALL_CACHERECORDS(slot, cg, cr)
5224 			mDNS_Reconfirm_internal(m, cr, kDefaultReconfirmTimeForWake);
5225 
5226 		// 3. Retrigger probing and announcing for all our authoritative records
5227 		for (rr = m->ResourceRecords; rr; rr=rr->next)
5228 			if (AuthRecord_uDNS(rr))
5229 				{
5230 				ActivateUnicastRegistration(m, rr);
5231 				}
5232 			else
5233 				{
5234 				if (rr->resrec.RecordType == kDNSRecordTypeVerified && !rr->DependentOn) rr->resrec.RecordType = kDNSRecordTypeUnique;
5235 				rr->ProbeCount     = DefaultProbeCountForRecordType(rr->resrec.RecordType);
5236 				rr->AnnounceCount  = InitialAnnounceCount;
5237 				rr->SendNSECNow    = mDNSNULL;
5238 				InitializeLastAPTime(m, rr);
5239 				}
5240 
5241 		// 4. Refresh NAT mappings
5242 		// We don't want to have to assume that all hardware can necessarily keep accurate
5243 		// track of passage of time while asleep, so on wake we refresh our NAT mappings
5244 		// We typically wake up with no interfaces active, so there's no need to rush to try to find our external address.
5245 		// When we get a network configuration change, mDNSMacOSXNetworkChanged calls uDNS_SetupDNSConfig, which calls
5246 		// mDNS_SetPrimaryInterfaceInfo, which then sets m->retryGetAddr to immediately request our external address from the NAT gateway.
5247 		m->retryIntervalGetAddr = NATMAP_INIT_RETRY;
5248 		m->retryGetAddr         = m->timenow + mDNSPlatformOneSecond * 5;
5249 		LogInfo("mDNSCoreMachineSleep: retryGetAddr in %d %d", m->retryGetAddr - m->timenow, m->timenow);
5250 		RecreateNATMappings(m);
5251 		mDNS_Unlock(m);
5252 		}
5253 	}
5254 
mDNSCoreReadyForSleep(mDNS * m,mDNSs32 now)5255 mDNSexport mDNSBool mDNSCoreReadyForSleep(mDNS *m, mDNSs32 now)
5256 	{
5257 	DNSQuestion *q;
5258 	AuthRecord *rr;
5259 	NetworkInterfaceInfo *intf;
5260 
5261 	mDNS_Lock(m);
5262 
5263 	if (m->DelaySleep) goto notready;
5264 
5265 	// If we've not hit the sleep limit time, and it's not time for our next retry, we can skip these checks
5266 	if (m->SleepLimit - now > 0 && m->NextScheduledSPRetry - now > 0) goto notready;
5267 
5268 	m->NextScheduledSPRetry = now + 0x40000000UL;
5269 
5270 	// See if we might need to retransmit any lost Sleep Proxy Registrations
5271 	for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next))
5272 		if (intf->NextSPSAttempt >= 0)
5273 			{
5274 			if (now - intf->NextSPSAttemptTime >= 0)
5275 				{
5276 				LogSPS("mDNSCoreReadyForSleep: retrying for %s SPS %d try %d",
5277 					intf->ifname, intf->NextSPSAttempt/3, intf->NextSPSAttempt);
5278 				SendSPSRegistration(m, intf, zeroID);
5279 				// Don't need to "goto notready" here, because if we do still have record registrations
5280 				// that have not been acknowledged yet, we'll catch that in the record list scan below.
5281 				}
5282 			else
5283 				if (m->NextScheduledSPRetry - intf->NextSPSAttemptTime > 0)
5284 					m->NextScheduledSPRetry = intf->NextSPSAttemptTime;
5285 			}
5286 
5287 	// Scan list of interfaces, and see if we're still waiting for any sleep proxy resolves to complete
5288 	for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next))
5289 		{
5290 		int sps = (intf->NextSPSAttempt == 0) ? 0 : (intf->NextSPSAttempt-1)/3;
5291 		if (intf->NetWakeResolve[sps].ThisQInterval >= 0)
5292 			{
5293 			LogSPS("mDNSCoreReadyForSleep: waiting for SPS Resolve %s %##s (%s)",
5294 				intf->ifname, intf->NetWakeResolve[sps].qname.c, DNSTypeName(intf->NetWakeResolve[sps].qtype));
5295 			goto spsnotready;
5296 			}
5297 		}
5298 
5299 	// Scan list of registered records
5300 	for (rr = m->ResourceRecords; rr; rr = rr->next)
5301 		if (!AuthRecord_uDNS(rr))
5302 			if (!mDNSOpaque16IsZero(rr->updateid))
5303 				{ LogSPS("mDNSCoreReadyForSleep: waiting for SPS Update ID %d %s", mDNSVal16(rr->updateid), ARDisplayString(m,rr)); goto spsnotready; }
5304 
5305 	// Scan list of private LLQs, and make sure they've all completed their handshake with the server
5306 	for (q = m->Questions; q; q = q->next)
5307 		if (!mDNSOpaque16IsZero(q->TargetQID) && q->LongLived && q->ReqLease == 0 && q->tcp)
5308 			{
5309 			LogSPS("mDNSCoreReadyForSleep: waiting for LLQ %##s (%s)", q->qname.c, DNSTypeName(q->qtype));
5310 			goto notready;
5311 			}
5312 
5313 	// Scan list of registered records
5314 	for (rr = m->ResourceRecords; rr; rr = rr->next)
5315 		if (AuthRecord_uDNS(rr))
5316 			{
5317 			if (rr->state == regState_Refresh && rr->tcp)
5318 				{ LogSPS("mDNSCoreReadyForSleep: waiting for Record Update ID %d %s", mDNSVal16(rr->updateid), ARDisplayString(m,rr)); goto notready; }
5319 			#if APPLE_OSX_mDNSResponder
5320 			if (!RecordReadyForSleep(m, rr)) { LogSPS("mDNSCoreReadyForSleep: waiting for %s", ARDisplayString(m, rr)); goto notready; }
5321 			#endif
5322 			}
5323 
5324 	mDNS_Unlock(m);
5325 	return mDNStrue;
5326 
5327 spsnotready:
5328 
5329 	// If we failed to complete sleep proxy registration within ten seconds, we give up on that
5330 	// and allow up to ten seconds more to complete wide-area deregistration instead
5331 	if (now - m->SleepLimit >= 0)
5332 		{
5333 		LogMsg("Failed to register with SPS, now sending goodbyes");
5334 
5335 		for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next))
5336 			if (intf->NetWakeBrowse.ThisQInterval >= 0)
5337 				{
5338 				LogSPS("ReadyForSleep mDNS_DeactivateNetWake %s %##s (%s)",
5339 					intf->ifname, intf->NetWakeResolve[0].qname.c, DNSTypeName(intf->NetWakeResolve[0].qtype));
5340 				mDNS_DeactivateNetWake_internal(m, intf);
5341 				}
5342 
5343 		for (rr = m->ResourceRecords; rr; rr = rr->next)
5344 			if (!AuthRecord_uDNS(rr))
5345 				if (!mDNSOpaque16IsZero(rr->updateid))
5346 					{
5347 					LogSPS("ReadyForSleep clearing updateid for %s", ARDisplayString(m, rr));
5348 					rr->updateid = zeroID;
5349 					}
5350 
5351 		// We'd really like to allow up to ten seconds more here,
5352 		// but if we don't respond to the sleep notification within 30 seconds
5353 		// we'll be put back to sleep forcibly without the chance to schedule the next maintenance wake.
5354 		// Right now we wait 16 sec after wake for all the interfaces to come up, then we wait up to 10 seconds
5355 		// more for SPS resolves and record registrations to complete, which puts us at 26 seconds.
5356 		// If we allow just one more second to send our goodbyes, that puts us at 27 seconds.
5357 		m->SleepLimit = now + mDNSPlatformOneSecond * 1;
5358 
5359 		SendSleepGoodbyes(m);
5360 		}
5361 
5362 notready:
5363 	mDNS_Unlock(m);
5364 	return mDNSfalse;
5365 	}
5366 
mDNSCoreIntervalToNextWake(mDNS * const m,mDNSs32 now)5367 mDNSexport mDNSs32 mDNSCoreIntervalToNextWake(mDNS *const m, mDNSs32 now)
5368 	{
5369 	AuthRecord *ar;
5370 
5371 	// Even when we have no wake-on-LAN-capable interfaces, or we failed to find a sleep proxy, or we have other
5372 	// failure scenarios, we still want to wake up in at most 120 minutes, to see if the network environment has changed.
5373 	// E.g. we might wake up and find no wireless network because the base station got rebooted just at that moment,
5374 	// and if that happens we don't want to just give up and go back to sleep and never try again.
5375 	mDNSs32 e = now + (120 * 60 * mDNSPlatformOneSecond);		// Sleep for at most 120 minutes
5376 
5377 	NATTraversalInfo *nat;
5378 	for (nat = m->NATTraversals; nat; nat=nat->next)
5379 		if (nat->Protocol && nat->ExpiryTime && nat->ExpiryTime - now > mDNSPlatformOneSecond*4)
5380 			{
5381 			mDNSs32 t = nat->ExpiryTime - (nat->ExpiryTime - now) / 10;		// Wake up when 90% of the way to the expiry time
5382 			if (e - t > 0) e = t;
5383 			LogSPS("ComputeWakeTime: %p %s Int %5d Ext %5d Err %d Retry %5d Interval %5d Expire %5d Wake %5d",
5384 				nat, nat->Protocol == NATOp_MapTCP ? "TCP" : "UDP",
5385 				mDNSVal16(nat->IntPort), mDNSVal16(nat->ExternalPort), nat->Result,
5386 				nat->retryPortMap ? (nat->retryPortMap - now) / mDNSPlatformOneSecond : 0,
5387 				nat->retryInterval / mDNSPlatformOneSecond,
5388 				nat->ExpiryTime ? (nat->ExpiryTime - now) / mDNSPlatformOneSecond : 0,
5389 				(t - now) / mDNSPlatformOneSecond);
5390 			}
5391 
5392 	// This loop checks both the time we need to renew wide-area registrations,
5393 	// and the time we need to renew Sleep Proxy registrations
5394 	for (ar = m->ResourceRecords; ar; ar = ar->next)
5395 		if (ar->expire && ar->expire - now > mDNSPlatformOneSecond*4)
5396 			{
5397 			mDNSs32 t = ar->expire - (ar->expire - now) / 10;		// Wake up when 90% of the way to the expiry time
5398 			if (e - t > 0) e = t;
5399 			LogSPS("ComputeWakeTime: %p Int %7d Next %7d Expire %7d Wake %7d %s",
5400 				ar, ar->ThisAPInterval / mDNSPlatformOneSecond,
5401 				(ar->LastAPTime + ar->ThisAPInterval - now) / mDNSPlatformOneSecond,
5402 				ar->expire ? (ar->expire - now) / mDNSPlatformOneSecond : 0,
5403 				(t - now) / mDNSPlatformOneSecond, ARDisplayString(m, ar));
5404 			}
5405 
5406 	return(e - now);
5407 	}
5408 
5409 // ***************************************************************************
5410 #if COMPILER_LIKES_PRAGMA_MARK
5411 #pragma mark -
5412 #pragma mark - Packet Reception Functions
5413 #endif
5414 
5415 #define MustSendRecord(RR) ((RR)->NR_AnswerTo || (RR)->NR_AdditionalTo)
5416 
GenerateUnicastResponse(const DNSMessage * const query,const mDNSu8 * const end,const mDNSInterfaceID InterfaceID,mDNSBool LegacyQuery,DNSMessage * const response,AuthRecord * ResponseRecords)5417 mDNSlocal mDNSu8 *GenerateUnicastResponse(const DNSMessage *const query, const mDNSu8 *const end,
5418 	const mDNSInterfaceID InterfaceID, mDNSBool LegacyQuery, DNSMessage *const response, AuthRecord *ResponseRecords)
5419 	{
5420 	mDNSu8          *responseptr     = response->data;
5421 	const mDNSu8    *const limit     = response->data + sizeof(response->data);
5422 	const mDNSu8    *ptr             = query->data;
5423 	AuthRecord  *rr;
5424 	mDNSu32          maxttl = 0x70000000;
5425 	int i;
5426 
5427 	// Initialize the response fields so we can answer the questions
5428 	InitializeDNSMessage(&response->h, query->h.id, ResponseFlags);
5429 
5430 	// ***
5431 	// *** 1. Write out the list of questions we are actually going to answer with this packet
5432 	// ***
5433 	if (LegacyQuery)
5434 		{
5435 		maxttl = kStaticCacheTTL;
5436 		for (i=0; i<query->h.numQuestions; i++)						// For each question...
5437 			{
5438 			DNSQuestion q;
5439 			ptr = getQuestion(query, ptr, end, InterfaceID, &q);	// get the question...
5440 			if (!ptr) return(mDNSNULL);
5441 
5442 			for (rr=ResponseRecords; rr; rr=rr->NextResponse)		// and search our list of proposed answers
5443 				{
5444 				if (rr->NR_AnswerTo == ptr)							// If we're going to generate a record answering this question
5445 					{												// then put the question in the question section
5446 					responseptr = putQuestion(response, responseptr, limit, &q.qname, q.qtype, q.qclass);
5447 					if (!responseptr) { debugf("GenerateUnicastResponse: Ran out of space for questions!"); return(mDNSNULL); }
5448 					break;		// break out of the ResponseRecords loop, and go on to the next question
5449 					}
5450 				}
5451 			}
5452 
5453 		if (response->h.numQuestions == 0) { LogMsg("GenerateUnicastResponse: ERROR! Why no questions?"); return(mDNSNULL); }
5454 		}
5455 
5456 	// ***
5457 	// *** 2. Write Answers
5458 	// ***
5459 	for (rr=ResponseRecords; rr; rr=rr->NextResponse)
5460 		if (rr->NR_AnswerTo)
5461 			{
5462 			mDNSu8 *p = PutResourceRecordTTL(response, responseptr, &response->h.numAnswers, &rr->resrec,
5463 				maxttl < rr->resrec.rroriginalttl ? maxttl : rr->resrec.rroriginalttl);
5464 			if (p) responseptr = p;
5465 			else { debugf("GenerateUnicastResponse: Ran out of space for answers!"); response->h.flags.b[0] |= kDNSFlag0_TC; }
5466 			}
5467 
5468 	// ***
5469 	// *** 3. Write Additionals
5470 	// ***
5471 	for (rr=ResponseRecords; rr; rr=rr->NextResponse)
5472 		if (rr->NR_AdditionalTo && !rr->NR_AnswerTo)
5473 			{
5474 			mDNSu8 *p = PutResourceRecordTTL(response, responseptr, &response->h.numAdditionals, &rr->resrec,
5475 				maxttl < rr->resrec.rroriginalttl ? maxttl : rr->resrec.rroriginalttl);
5476 			if (p) responseptr = p;
5477 			else debugf("GenerateUnicastResponse: No more space for additionals");
5478 			}
5479 
5480 	return(responseptr);
5481 	}
5482 
5483 // AuthRecord *our is our Resource Record
5484 // CacheRecord *pkt is the Resource Record from the response packet we've witnessed on the network
5485 // Returns 0 if there is no conflict
5486 // Returns +1 if there was a conflict and we won
5487 // Returns -1 if there was a conflict and we lost and have to rename
CompareRData(const AuthRecord * const our,const CacheRecord * const pkt)5488 mDNSlocal int CompareRData(const AuthRecord *const our, const CacheRecord *const pkt)
5489 	{
5490 	mDNSu8 ourdata[256], *ourptr = ourdata, *ourend;
5491 	mDNSu8 pktdata[256], *pktptr = pktdata, *pktend;
5492 	if (!our) { LogMsg("CompareRData ERROR: our is NULL"); return(+1); }
5493 	if (!pkt) { LogMsg("CompareRData ERROR: pkt is NULL"); return(+1); }
5494 
5495 	ourend = putRData(mDNSNULL, ourdata, ourdata + sizeof(ourdata), &our->resrec);
5496 	pktend = putRData(mDNSNULL, pktdata, pktdata + sizeof(pktdata), &pkt->resrec);
5497 	while (ourptr < ourend && pktptr < pktend && *ourptr == *pktptr) { ourptr++; pktptr++; }
5498 	if (ourptr >= ourend && pktptr >= pktend) return(0);			// If data identical, not a conflict
5499 
5500 	if (ourptr >= ourend) return(-1);								// Our data ran out first; We lost
5501 	if (pktptr >= pktend) return(+1);								// Packet data ran out first; We won
5502 	if (*pktptr > *ourptr) return(-1);								// Our data is numerically lower; We lost
5503 	if (*pktptr < *ourptr) return(+1);								// Packet data is numerically lower; We won
5504 
5505 	LogMsg("CompareRData ERROR: Invalid state");
5506 	return(-1);
5507 	}
5508 
5509 // See if we have an authoritative record that's identical to this packet record,
5510 // whose canonical DependentOn record is the specified master record.
5511 // The DependentOn pointer is typically used for the TXT record of service registrations
5512 // It indicates that there is no inherent conflict detection for the TXT record
5513 // -- it depends on the SRV record to resolve name conflicts
5514 // If we find any identical ResourceRecords in our authoritative list, then follow their DependentOn
5515 // pointer chain (if any) to make sure we reach the canonical DependentOn record
5516 // If the record has no DependentOn, then just return that record's pointer
5517 // Returns NULL if we don't have any local RRs that are identical to the one from the packet
MatchDependentOn(const mDNS * const m,const CacheRecord * const pktrr,const AuthRecord * const master)5518 mDNSlocal mDNSBool MatchDependentOn(const mDNS *const m, const CacheRecord *const pktrr, const AuthRecord *const master)
5519 	{
5520 	const AuthRecord *r1;
5521 	for (r1 = m->ResourceRecords; r1; r1=r1->next)
5522 		{
5523 		if (IdenticalResourceRecord(&r1->resrec, &pktrr->resrec))
5524 			{
5525 			const AuthRecord *r2 = r1;
5526 			while (r2->DependentOn) r2 = r2->DependentOn;
5527 			if (r2 == master) return(mDNStrue);
5528 			}
5529 		}
5530 	for (r1 = m->DuplicateRecords; r1; r1=r1->next)
5531 		{
5532 		if (IdenticalResourceRecord(&r1->resrec, &pktrr->resrec))
5533 			{
5534 			const AuthRecord *r2 = r1;
5535 			while (r2->DependentOn) r2 = r2->DependentOn;
5536 			if (r2 == master) return(mDNStrue);
5537 			}
5538 		}
5539 	return(mDNSfalse);
5540 	}
5541 
5542 // Find the canonical RRSet pointer for this RR received in a packet.
5543 // If we find any identical AuthRecord in our authoritative list, then follow its RRSet
5544 // pointers (if any) to make sure we return the canonical member of this name/type/class
5545 // Returns NULL if we don't have any local RRs that are identical to the one from the packet
FindRRSet(const mDNS * const m,const CacheRecord * const pktrr)5546 mDNSlocal const AuthRecord *FindRRSet(const mDNS *const m, const CacheRecord *const pktrr)
5547 	{
5548 	const AuthRecord *rr;
5549 	for (rr = m->ResourceRecords; rr; rr=rr->next)
5550 		{
5551 		if (IdenticalResourceRecord(&rr->resrec, &pktrr->resrec))
5552 			{
5553 			while (rr->RRSet && rr != rr->RRSet) rr = rr->RRSet;
5554 			return(rr);
5555 			}
5556 		}
5557 	return(mDNSNULL);
5558 	}
5559 
5560 // PacketRRConflict is called when we've received an RR (pktrr) which has the same name
5561 // as one of our records (our) but different rdata.
5562 // 1. If our record is not a type that's supposed to be unique, we don't care.
5563 // 2a. If our record is marked as dependent on some other record for conflict detection, ignore this one.
5564 // 2b. If the packet rr exactly matches one of our other RRs, and *that* record's DependentOn pointer
5565 //     points to our record, ignore this conflict (e.g. the packet record matches one of our
5566 //     TXT records, and that record is marked as dependent on 'our', its SRV record).
5567 // 3. If we have some *other* RR that exactly matches the one from the packet, and that record and our record
5568 //    are members of the same RRSet, then this is not a conflict.
PacketRRConflict(const mDNS * const m,const AuthRecord * const our,const CacheRecord * const pktrr)5569 mDNSlocal mDNSBool PacketRRConflict(const mDNS *const m, const AuthRecord *const our, const CacheRecord *const pktrr)
5570 	{
5571 	// If not supposed to be unique, not a conflict
5572 	if (!(our->resrec.RecordType & kDNSRecordTypeUniqueMask)) return(mDNSfalse);
5573 
5574 	// If a dependent record, not a conflict
5575 	if (our->DependentOn || MatchDependentOn(m, pktrr, our)) return(mDNSfalse);
5576 	else
5577 		{
5578 		// If the pktrr matches a member of ourset, not a conflict
5579 		const AuthRecord *ourset = our->RRSet ? our->RRSet : our;
5580 		const AuthRecord *pktset = FindRRSet(m, pktrr);
5581 		if (pktset == ourset) return(mDNSfalse);
5582 
5583 		// For records we're proxying, where we don't know the full
5584 		// relationship between the records, having any matching record
5585 		// in our AuthRecords list is sufficient evidence of non-conflict
5586 		if (our->WakeUp.HMAC.l[0] && pktset) return(mDNSfalse);
5587 		}
5588 
5589 	// Okay, this is a conflict
5590 	return(mDNStrue);
5591 	}
5592 
5593 // Note: ResolveSimultaneousProbe calls mDNS_Deregister_internal which can call a user callback, which may change
5594 // the record list and/or question list.
5595 // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this.
ResolveSimultaneousProbe(mDNS * const m,const DNSMessage * const query,const mDNSu8 * const end,DNSQuestion * q,AuthRecord * our)5596 mDNSlocal void ResolveSimultaneousProbe(mDNS *const m, const DNSMessage *const query, const mDNSu8 *const end,
5597 	DNSQuestion *q, AuthRecord *our)
5598 	{
5599 	int i;
5600 	const mDNSu8 *ptr = LocateAuthorities(query, end);
5601 	mDNSBool FoundUpdate = mDNSfalse;
5602 
5603 	for (i = 0; i < query->h.numAuthorities; i++)
5604 		{
5605 		ptr = GetLargeResourceRecord(m, query, ptr, end, q->InterfaceID, kDNSRecordTypePacketAuth, &m->rec);
5606 		if (!ptr) break;
5607 		if (m->rec.r.resrec.RecordType != kDNSRecordTypePacketNegative && ResourceRecordAnswersQuestion(&m->rec.r.resrec, q))
5608 			{
5609 			FoundUpdate = mDNStrue;
5610 			if (PacketRRConflict(m, our, &m->rec.r))
5611 				{
5612 				int result          = (int)our->resrec.rrclass - (int)m->rec.r.resrec.rrclass;
5613 				if (!result) result = (int)our->resrec.rrtype  - (int)m->rec.r.resrec.rrtype;
5614 				if (!result) result = CompareRData(our, &m->rec.r);
5615 				if (result)
5616 					{
5617 					const char *const msg = (result < 0) ? "lost:" : (result > 0) ? "won: " : "tie: ";
5618 					LogMsg("ResolveSimultaneousProbe: %p Pkt Record:        %08lX %s", q->InterfaceID, m->rec.r.resrec.rdatahash, CRDisplayString(m, &m->rec.r));
5619 					LogMsg("ResolveSimultaneousProbe: %p Our Record %d %s %08lX %s", our->resrec.InterfaceID, our->ProbeCount, msg, our->resrec.rdatahash, ARDisplayString(m, our));
5620 					}
5621 				// If we lost the tie-break for simultaneous probes, we don't immediately give up, because we might be seeing stale packets on the network.
5622 				// Instead we pause for one second, to give the other host (if real) a chance to establish its name, and then try probing again.
5623 				// If there really is another live host out there with the same name, it will answer our probes and we'll then rename.
5624 				if (result < 0)
5625 					{
5626 					m->SuppressProbes   = NonZeroTime(m->timenow + mDNSPlatformOneSecond);
5627 					our->ProbeCount     = DefaultProbeCountForTypeUnique;
5628 					our->AnnounceCount  = InitialAnnounceCount;
5629 					InitializeLastAPTime(m, our);
5630 					goto exit;
5631 					}
5632 				}
5633 #if 0
5634 			else
5635 				{
5636 				LogMsg("ResolveSimultaneousProbe: %p Pkt Record:        %08lX %s", q->InterfaceID, m->rec.r.resrec.rdatahash, CRDisplayString(m, &m->rec.r));
5637 				LogMsg("ResolveSimultaneousProbe: %p Our Record %d ign:  %08lX %s", our->resrec.InterfaceID, our->ProbeCount, our->resrec.rdatahash, ARDisplayString(m, our));
5638 				}
5639 #endif
5640 			}
5641 		m->rec.r.resrec.RecordType = 0;		// Clear RecordType to show we're not still using it
5642 		}
5643 	if (!FoundUpdate)
5644 		LogInfo("ResolveSimultaneousProbe: %##s (%s): No Update Record found", our->resrec.name->c, DNSTypeName(our->resrec.rrtype));
5645 exit:
5646 	m->rec.r.resrec.RecordType = 0;		// Clear RecordType to show we're not still using it
5647 	}
5648 
FindIdenticalRecordInCache(const mDNS * const m,const ResourceRecord * const pktrr)5649 mDNSlocal CacheRecord *FindIdenticalRecordInCache(const mDNS *const m, const ResourceRecord *const pktrr)
5650 	{
5651 	mDNSu32 slot = HashSlot(pktrr->name);
5652 	CacheGroup *cg = CacheGroupForRecord(m, slot, pktrr);
5653 	CacheRecord *rr;
5654 	mDNSBool match;
5655 	for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next)
5656 		{
5657 		match = !pktrr->InterfaceID ? pktrr->rDNSServer == rr->resrec.rDNSServer : pktrr->InterfaceID == rr->resrec.InterfaceID;
5658 		if (match && IdenticalSameNameRecord(pktrr, &rr->resrec)) break;
5659 		}
5660 	return(rr);
5661 	}
5662 
5663 // Called from mDNSCoreReceiveUpdate when we get a sleep proxy registration request,
5664 // to check our lists and discard any stale duplicates of this record we already have
ClearIdenticalProxyRecords(mDNS * const m,const OwnerOptData * const owner,AuthRecord * const thelist)5665 mDNSlocal void ClearIdenticalProxyRecords(mDNS *const m, const OwnerOptData *const owner, AuthRecord *const thelist)
5666 	{
5667 	if (m->CurrentRecord)
5668 		LogMsg("ClearIdenticalProxyRecords ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord));
5669 	m->CurrentRecord = thelist;
5670 	while (m->CurrentRecord)
5671 		{
5672 		AuthRecord *const rr = m->CurrentRecord;
5673 		if (m->rec.r.resrec.InterfaceID == rr->resrec.InterfaceID && mDNSSameEthAddress(&owner->HMAC, &rr->WakeUp.HMAC))
5674 			if (IdenticalResourceRecord(&rr->resrec, &m->rec.r.resrec))
5675 				{
5676 				LogSPS("ClearIdenticalProxyRecords: Removing %3d H-MAC %.6a I-MAC %.6a %d %d %s",
5677 					m->ProxyRecords, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, rr->WakeUp.seq, owner->seq, ARDisplayString(m, rr));
5678 				rr->WakeUp.HMAC = zeroEthAddr;	// Clear HMAC so that mDNS_Deregister_internal doesn't waste packets trying to wake this host
5679 				rr->RequireGoodbye = mDNSfalse;	// and we don't want to send goodbye for it
5680 				mDNS_Deregister_internal(m, rr, mDNS_Dereg_normal);
5681 				SetSPSProxyListChanged(m->rec.r.resrec.InterfaceID);
5682 				}
5683 		// Mustn't advance m->CurrentRecord until *after* mDNS_Deregister_internal, because
5684 		// new records could have been added to the end of the list as a result of that call.
5685 		if (m->CurrentRecord == rr) // If m->CurrentRecord was not advanced for us, do it now
5686 			m->CurrentRecord = rr->next;
5687 		}
5688 	}
5689 
5690 // Called from ProcessQuery when we get an mDNS packet with an owner record in it
ClearProxyRecords(mDNS * const m,const OwnerOptData * const owner,AuthRecord * const thelist)5691 mDNSlocal void ClearProxyRecords(mDNS *const m, const OwnerOptData *const owner, AuthRecord *const thelist)
5692 	{
5693 	if (m->CurrentRecord)
5694 		LogMsg("ClearProxyRecords ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord));
5695 	m->CurrentRecord = thelist;
5696 	while (m->CurrentRecord)
5697 		{
5698 		AuthRecord *const rr = m->CurrentRecord;
5699 		if (m->rec.r.resrec.InterfaceID == rr->resrec.InterfaceID && mDNSSameEthAddress(&owner->HMAC, &rr->WakeUp.HMAC))
5700 			if (owner->seq != rr->WakeUp.seq || m->timenow - rr->TimeRcvd > mDNSPlatformOneSecond * 60)
5701 				{
5702 				if (rr->AddressProxy.type == mDNSAddrType_IPv6)
5703 					{
5704 					// We don't do this here because we know that the host is waking up at this point, so we don't send
5705 					// Unsolicited Neighbor Advertisements -- even Neighbor Advertisements agreeing with what the host should be
5706 					// saying itself -- because it can cause some IPv6 stacks to falsely conclude that there's an address conflict.
5707 					#if MDNS_USE_Unsolicited_Neighbor_Advertisements
5708 					LogSPS("NDP Announcement -- Releasing traffic for H-MAC %.6a I-MAC %.6a %s",
5709 						&rr->WakeUp.HMAC, &rr->WakeUp.IMAC, ARDisplayString(m,rr));
5710 					SendNDP(m, NDP_Adv, NDP_Override, rr, &rr->AddressProxy.ip.v6, &rr->WakeUp.IMAC, &AllHosts_v6, &AllHosts_v6_Eth);
5711 					#endif
5712 					}
5713 				LogSPS("ClearProxyRecords: Removing %3d AC %2d %02X H-MAC %.6a I-MAC %.6a %d %d %s",
5714 					m->ProxyRecords, rr->AnnounceCount, rr->resrec.RecordType,
5715 					&rr->WakeUp.HMAC, &rr->WakeUp.IMAC, rr->WakeUp.seq, owner->seq, ARDisplayString(m, rr));
5716 				if (rr->resrec.RecordType == kDNSRecordTypeDeregistering) rr->resrec.RecordType = kDNSRecordTypeShared;
5717 				rr->WakeUp.HMAC = zeroEthAddr;	// Clear HMAC so that mDNS_Deregister_internal doesn't waste packets trying to wake this host
5718 				rr->RequireGoodbye = mDNSfalse;	// and we don't want to send goodbye for it, since real host is now back and functional
5719 				mDNS_Deregister_internal(m, rr, mDNS_Dereg_normal);
5720 				SetSPSProxyListChanged(m->rec.r.resrec.InterfaceID);
5721 				}
5722 		// Mustn't advance m->CurrentRecord until *after* mDNS_Deregister_internal, because
5723 		// new records could have been added to the end of the list as a result of that call.
5724 		if (m->CurrentRecord == rr) // If m->CurrentRecord was not advanced for us, do it now
5725 			m->CurrentRecord = rr->next;
5726 		}
5727 	}
5728 
5729 // ProcessQuery examines a received query to see if we have any answers to give
ProcessQuery(mDNS * const m,const DNSMessage * const query,const mDNSu8 * const end,const mDNSAddr * srcaddr,const mDNSInterfaceID InterfaceID,mDNSBool LegacyQuery,mDNSBool QueryWasMulticast,mDNSBool QueryWasLocalUnicast,DNSMessage * const response)5730 mDNSlocal mDNSu8 *ProcessQuery(mDNS *const m, const DNSMessage *const query, const mDNSu8 *const end,
5731 	const mDNSAddr *srcaddr, const mDNSInterfaceID InterfaceID, mDNSBool LegacyQuery, mDNSBool QueryWasMulticast,
5732 	mDNSBool QueryWasLocalUnicast, DNSMessage *const response)
5733 	{
5734 	mDNSBool      FromLocalSubnet    = srcaddr && mDNS_AddressIsLocalSubnet(m, InterfaceID, srcaddr);
5735 	AuthRecord   *ResponseRecords    = mDNSNULL;
5736 	AuthRecord  **nrp                = &ResponseRecords;
5737 	CacheRecord  *ExpectedAnswers    = mDNSNULL;			// Records in our cache we expect to see updated
5738 	CacheRecord **eap                = &ExpectedAnswers;
5739 	DNSQuestion  *DupQuestions       = mDNSNULL;			// Our questions that are identical to questions in this packet
5740 	DNSQuestion **dqp                = &DupQuestions;
5741 	mDNSs32       delayresponse      = 0;
5742 	mDNSBool      SendLegacyResponse = mDNSfalse;
5743 	const mDNSu8 *ptr;
5744 	mDNSu8       *responseptr        = mDNSNULL;
5745 	AuthRecord   *rr;
5746 	int i;
5747 
5748 	// ***
5749 	// *** 1. Look in Additional Section for an OPT record
5750 	// ***
5751 	ptr = LocateOptRR(query, end, DNSOpt_OwnerData_ID_Space);
5752 	if (ptr)
5753 		{
5754 		ptr = GetLargeResourceRecord(m, query, ptr, end, InterfaceID, kDNSRecordTypePacketAdd, &m->rec);
5755 		if (ptr && m->rec.r.resrec.RecordType != kDNSRecordTypePacketNegative && m->rec.r.resrec.rrtype == kDNSType_OPT)
5756 			{
5757 			const rdataOPT *opt;
5758 			const rdataOPT *const e = (const rdataOPT *)&m->rec.r.resrec.rdata->u.data[m->rec.r.resrec.rdlength];
5759 			// Find owner sub-option(s). We verify that the MAC is non-zero, otherwise we could inadvertently
5760 			// delete all our own AuthRecords (which are identified by having zero MAC tags on them).
5761 			for (opt = &m->rec.r.resrec.rdata->u.opt[0]; opt < e; opt++)
5762 				if (opt->opt == kDNSOpt_Owner && opt->u.owner.vers == 0 && opt->u.owner.HMAC.l[0])
5763 					{
5764 					ClearProxyRecords(m, &opt->u.owner, m->DuplicateRecords);
5765 					ClearProxyRecords(m, &opt->u.owner, m->ResourceRecords);
5766 					}
5767 			}
5768 		m->rec.r.resrec.RecordType = 0;		// Clear RecordType to show we're not still using it
5769 		}
5770 
5771 	// ***
5772 	// *** 2. Parse Question Section and mark potential answers
5773 	// ***
5774 	ptr = query->data;
5775 	for (i=0; i<query->h.numQuestions; i++)						// For each question...
5776 		{
5777 		mDNSBool QuestionNeedsMulticastResponse;
5778 		int NumAnswersForThisQuestion = 0;
5779 		AuthRecord *NSECAnswer = mDNSNULL;
5780 		DNSQuestion pktq, *q;
5781 		ptr = getQuestion(query, ptr, end, InterfaceID, &pktq);	// get the question...
5782 		if (!ptr) goto exit;
5783 
5784 		// The only queries that *need* a multicast response are:
5785 		// * Queries sent via multicast
5786 		// * from port 5353
5787 		// * that don't have the kDNSQClass_UnicastResponse bit set
5788 		// These queries need multicast responses because other clients will:
5789 		// * suppress their own identical questions when they see these questions, and
5790 		// * expire their cache records if they don't see the expected responses
5791 		// For other queries, we may still choose to send the occasional multicast response anyway,
5792 		// to keep our neighbours caches warm, and for ongoing conflict detection.
5793 		QuestionNeedsMulticastResponse = QueryWasMulticast && !LegacyQuery && !(pktq.qclass & kDNSQClass_UnicastResponse);
5794 		// Clear the UnicastResponse flag -- don't want to confuse the rest of the code that follows later
5795 		pktq.qclass &= ~kDNSQClass_UnicastResponse;
5796 
5797 		// Note: We use the m->CurrentRecord mechanism here because calling ResolveSimultaneousProbe
5798 		// can result in user callbacks which may change the record list and/or question list.
5799 		// Also note: we just mark potential answer records here, without trying to build the
5800 		// "ResponseRecords" list, because we don't want to risk user callbacks deleting records
5801 		// from that list while we're in the middle of trying to build it.
5802 		if (m->CurrentRecord)
5803 			LogMsg("ProcessQuery ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord));
5804 		m->CurrentRecord = m->ResourceRecords;
5805 		while (m->CurrentRecord)
5806 			{
5807 			rr = m->CurrentRecord;
5808 			m->CurrentRecord = rr->next;
5809 			if (AnyTypeRecordAnswersQuestion(&rr->resrec, &pktq) && (QueryWasMulticast || QueryWasLocalUnicast || rr->AllowRemoteQuery))
5810 				{
5811 				if (RRTypeAnswersQuestionType(&rr->resrec, pktq.qtype))
5812 					{
5813 					if (rr->resrec.RecordType == kDNSRecordTypeUnique)
5814 						ResolveSimultaneousProbe(m, query, end, &pktq, rr);
5815 					else if (ResourceRecordIsValidAnswer(rr))
5816 						{
5817 						NumAnswersForThisQuestion++;
5818 						// Note: We should check here if this is a probe-type query, and if so, generate an immediate
5819 						// unicast answer back to the source, because timeliness in answering probes is important.
5820 
5821 						// Notes:
5822 						// NR_AnswerTo pointing into query packet means "answer via immediate legacy unicast" (may *also* choose to multicast)
5823 						// NR_AnswerTo == (mDNSu8*)~1             means "answer via delayed unicast" (to modern querier; may promote to multicast instead)
5824 						// NR_AnswerTo == (mDNSu8*)~0             means "definitely answer via multicast" (can't downgrade to unicast later)
5825 						// If we're not multicasting this record because the kDNSQClass_UnicastResponse bit was set,
5826 						// but the multicast querier is not on a matching subnet (e.g. because of overlaid subnets on one link)
5827 						// then we'll multicast it anyway (if we unicast, the receiver will ignore it because it has an apparently non-local source)
5828 						if (QuestionNeedsMulticastResponse || (!FromLocalSubnet && QueryWasMulticast && !LegacyQuery))
5829 							{
5830 							// We only mark this question for sending if it is at least one second since the last time we multicast it
5831 							// on this interface. If it is more than a second, or LastMCInterface is different, then we may multicast it.
5832 							// This is to guard against the case where someone blasts us with queries as fast as they can.
5833 							if (m->timenow - (rr->LastMCTime + mDNSPlatformOneSecond) >= 0 ||
5834 								(rr->LastMCInterface != mDNSInterfaceMark && rr->LastMCInterface != InterfaceID))
5835 								rr->NR_AnswerTo = (mDNSu8*)~0;
5836 							}
5837 						else if (!rr->NR_AnswerTo) rr->NR_AnswerTo = LegacyQuery ? ptr : (mDNSu8*)~1;
5838 						}
5839 					}
5840 				else if ((rr->resrec.RecordType & kDNSRecordTypeActiveUniqueMask) && ResourceRecordIsValidAnswer(rr))
5841 					{
5842 					// If we don't have any answers for this question, but we do own another record with the same name,
5843 					// then we'll want to mark it to generate an NSEC record on this interface
5844 					if (!NSECAnswer) NSECAnswer = rr;
5845 					}
5846 				}
5847 			}
5848 
5849 		if (NumAnswersForThisQuestion == 0 && NSECAnswer)
5850 			{
5851 			NumAnswersForThisQuestion++;
5852 			NSECAnswer->SendNSECNow = InterfaceID;
5853 			m->NextScheduledResponse = m->timenow;
5854 			}
5855 
5856 		// If we couldn't answer this question, someone else might be able to,
5857 		// so use random delay on response to reduce collisions
5858 		if (NumAnswersForThisQuestion == 0) delayresponse = mDNSPlatformOneSecond;	// Divided by 50 = 20ms
5859 
5860 #if ENABLE_MULTI_PACKET_QUERY_SNOOPING
5861 		if (QuestionNeedsMulticastResponse)
5862 #else
5863 		// We only do the following accelerated cache expiration and duplicate question suppression processing
5864 		// for non-truncated multicast queries with multicast responses.
5865 		// For any query generating a unicast response we don't do this because we can't assume we will see the response.
5866 		// For truncated queries we don't do this because a response we're expecting might be suppressed by a subsequent
5867 		// known-answer packet, and when there's packet loss we can't safely assume we'll receive *all* known-answer packets.
5868 		if (QuestionNeedsMulticastResponse && !(query->h.flags.b[0] & kDNSFlag0_TC))
5869 #endif
5870 			{
5871 			const mDNSu32 slot = HashSlot(&pktq.qname);
5872 			CacheGroup *cg = CacheGroupForName(m, slot, pktq.qnamehash, &pktq.qname);
5873 			CacheRecord *cr;
5874 
5875 			// Make a list indicating which of our own cache records we expect to see updated as a result of this query
5876 			// Note: Records larger than 1K are not habitually multicast, so don't expect those to be updated
5877 #if ENABLE_MULTI_PACKET_QUERY_SNOOPING
5878 			if (!(query->h.flags.b[0] & kDNSFlag0_TC))
5879 #endif
5880 				for (cr = cg ? cg->members : mDNSNULL; cr; cr=cr->next)
5881 					if (SameNameRecordAnswersQuestion(&cr->resrec, &pktq) && cr->resrec.rdlength <= SmallRecordLimit)
5882 						if (!cr->NextInKAList && eap != &cr->NextInKAList)
5883 							{
5884 							*eap = cr;
5885 							eap = &cr->NextInKAList;
5886 #if ENABLE_MULTI_PACKET_QUERY_SNOOPING
5887 							if (cr->MPUnansweredQ == 0 || m->timenow - cr->MPLastUnansweredQT >= mDNSPlatformOneSecond)
5888 								{
5889 								// Although MPUnansweredQ is only really used for multi-packet query processing,
5890 								// we increment it for both single-packet and multi-packet queries, so that it stays in sync
5891 								// with the MPUnansweredKA value, which by necessity is incremented for both query types.
5892 								cr->MPUnansweredQ++;
5893 								cr->MPLastUnansweredQT = m->timenow;
5894 								cr->MPExpectingKA = mDNStrue;
5895 								}
5896 #endif
5897 							}
5898 
5899 			// Check if this question is the same as any of mine.
5900 			// We only do this for non-truncated queries. Right now it would be too complicated to try
5901 			// to keep track of duplicate suppression state between multiple packets, especially when we
5902 			// can't guarantee to receive all of the Known Answer packets that go with a particular query.
5903 #if ENABLE_MULTI_PACKET_QUERY_SNOOPING
5904 			if (!(query->h.flags.b[0] & kDNSFlag0_TC))
5905 #endif
5906 				for (q = m->Questions; q; q=q->next)
5907 					if (!q->Target.type && ActiveQuestion(q) && m->timenow - q->LastQTxTime > mDNSPlatformOneSecond / 4)
5908 						if (!q->InterfaceID || q->InterfaceID == InterfaceID)
5909 							if (q->NextInDQList == mDNSNULL && dqp != &q->NextInDQList)
5910 								if (q->qtype == pktq.qtype &&
5911 									q->qclass == pktq.qclass &&
5912 									q->qnamehash == pktq.qnamehash && SameDomainName(&q->qname, &pktq.qname))
5913 									{ *dqp = q; dqp = &q->NextInDQList; }
5914 			}
5915 		}
5916 
5917 	// ***
5918 	// *** 3. Now we can safely build the list of marked answers
5919 	// ***
5920 	for (rr = m->ResourceRecords; rr; rr=rr->next)				// Now build our list of potential answers
5921 		if (rr->NR_AnswerTo)									// If we marked the record...
5922 			AddRecordToResponseList(&nrp, rr, mDNSNULL);		// ... add it to the list
5923 
5924 	// ***
5925 	// *** 4. Add additional records
5926 	// ***
5927 	AddAdditionalsToResponseList(m, ResponseRecords, &nrp, InterfaceID);
5928 
5929 	// ***
5930 	// *** 5. Parse Answer Section and cancel any records disallowed by Known-Answer list
5931 	// ***
5932 	for (i=0; i<query->h.numAnswers; i++)						// For each record in the query's answer section...
5933 		{
5934 		// Get the record...
5935 		CacheRecord *ourcacherr;
5936 		ptr = GetLargeResourceRecord(m, query, ptr, end, InterfaceID, kDNSRecordTypePacketAns, &m->rec);
5937 		if (!ptr) goto exit;
5938 		if (m->rec.r.resrec.RecordType != kDNSRecordTypePacketNegative)
5939 			{
5940 			// See if this Known-Answer suppresses any of our currently planned answers
5941 			for (rr=ResponseRecords; rr; rr=rr->NextResponse)
5942 				if (MustSendRecord(rr) && ShouldSuppressKnownAnswer(&m->rec.r, rr))
5943 					{ rr->NR_AnswerTo = mDNSNULL; rr->NR_AdditionalTo = mDNSNULL; }
5944 
5945 			// See if this Known-Answer suppresses any previously scheduled answers (for multi-packet KA suppression)
5946 			for (rr=m->ResourceRecords; rr; rr=rr->next)
5947 				{
5948 				// If we're planning to send this answer on this interface, and only on this interface, then allow KA suppression
5949 				if (rr->ImmedAnswer == InterfaceID && ShouldSuppressKnownAnswer(&m->rec.r, rr))
5950 					{
5951 					if (srcaddr->type == mDNSAddrType_IPv4)
5952 						{
5953 						if (mDNSSameIPv4Address(rr->v4Requester, srcaddr->ip.v4)) rr->v4Requester = zerov4Addr;
5954 						}
5955 					else if (srcaddr->type == mDNSAddrType_IPv6)
5956 						{
5957 						if (mDNSSameIPv6Address(rr->v6Requester, srcaddr->ip.v6)) rr->v6Requester = zerov6Addr;
5958 						}
5959 					if (mDNSIPv4AddressIsZero(rr->v4Requester) && mDNSIPv6AddressIsZero(rr->v6Requester))
5960 						{
5961 						rr->ImmedAnswer  = mDNSNULL;
5962 						rr->ImmedUnicast = mDNSfalse;
5963 	#if MDNS_LOG_ANSWER_SUPPRESSION_TIMES
5964 						LogMsg("Suppressed after%4d: %s", m->timenow - rr->ImmedAnswerMarkTime, ARDisplayString(m, rr));
5965 	#endif
5966 						}
5967 					}
5968 				}
5969 
5970 			ourcacherr = FindIdenticalRecordInCache(m, &m->rec.r.resrec);
5971 
5972 	#if ENABLE_MULTI_PACKET_QUERY_SNOOPING
5973 			// See if this Known-Answer suppresses any answers we were expecting for our cache records. We do this always,
5974 			// even if the TC bit is not set (the TC bit will *not* be set in the *last* packet of a multi-packet KA list).
5975 			if (ourcacherr && ourcacherr->MPExpectingKA && m->timenow - ourcacherr->MPLastUnansweredQT < mDNSPlatformOneSecond)
5976 				{
5977 				ourcacherr->MPUnansweredKA++;
5978 				ourcacherr->MPExpectingKA = mDNSfalse;
5979 				}
5980 	#endif
5981 
5982 			// Having built our ExpectedAnswers list from the questions in this packet, we then remove
5983 			// any records that are suppressed by the Known Answer list in this packet.
5984 			eap = &ExpectedAnswers;
5985 			while (*eap)
5986 				{
5987 				CacheRecord *cr = *eap;
5988 				if (cr->resrec.InterfaceID == InterfaceID && IdenticalResourceRecord(&m->rec.r.resrec, &cr->resrec))
5989 					{ *eap = cr->NextInKAList; cr->NextInKAList = mDNSNULL; }
5990 				else eap = &cr->NextInKAList;
5991 				}
5992 
5993 			// See if this Known-Answer is a surprise to us. If so, we shouldn't suppress our own query.
5994 			if (!ourcacherr)
5995 				{
5996 				dqp = &DupQuestions;
5997 				while (*dqp)
5998 					{
5999 					DNSQuestion *q = *dqp;
6000 					if (ResourceRecordAnswersQuestion(&m->rec.r.resrec, q))
6001 						{ *dqp = q->NextInDQList; q->NextInDQList = mDNSNULL; }
6002 					else dqp = &q->NextInDQList;
6003 					}
6004 				}
6005 			}
6006 		m->rec.r.resrec.RecordType = 0;		// Clear RecordType to show we're not still using it
6007 		}
6008 
6009 	// ***
6010 	// *** 6. Cancel any additionals that were added because of now-deleted records
6011 	// ***
6012 	for (rr=ResponseRecords; rr; rr=rr->NextResponse)
6013 		if (rr->NR_AdditionalTo && !MustSendRecord(rr->NR_AdditionalTo))
6014 			{ rr->NR_AnswerTo = mDNSNULL; rr->NR_AdditionalTo = mDNSNULL; }
6015 
6016 	// ***
6017 	// *** 7. Mark the send flags on the records we plan to send
6018 	// ***
6019 	for (rr=ResponseRecords; rr; rr=rr->NextResponse)
6020 		{
6021 		if (rr->NR_AnswerTo)
6022 			{
6023 			mDNSBool SendMulticastResponse = mDNSfalse;		// Send modern multicast response
6024 			mDNSBool SendUnicastResponse   = mDNSfalse;		// Send modern unicast response (not legacy unicast response)
6025 
6026 			// If it's been a while since we multicast this, then send a multicast response for conflict detection, etc.
6027 			if (m->timenow - (rr->LastMCTime + TicksTTL(rr)/4) >= 0)
6028 				{
6029 				SendMulticastResponse = mDNStrue;
6030 				// If this record was marked for modern (delayed) unicast response, then mark it as promoted to
6031 				// multicast response instead (don't want to end up ALSO setting SendUnicastResponse in the check below).
6032 				// If this record was marked for legacy unicast response, then we mustn't change the NR_AnswerTo value.
6033 				if (rr->NR_AnswerTo == (mDNSu8*)~1) rr->NR_AnswerTo = (mDNSu8*)~0;
6034 				}
6035 
6036 			// If the client insists on a multicast response, then we'd better send one
6037 			if      (rr->NR_AnswerTo == (mDNSu8*)~0) SendMulticastResponse = mDNStrue;
6038 			else if (rr->NR_AnswerTo == (mDNSu8*)~1) SendUnicastResponse   = mDNStrue;
6039 			else if (rr->NR_AnswerTo)                SendLegacyResponse    = mDNStrue;
6040 
6041 			if (SendMulticastResponse || SendUnicastResponse)
6042 				{
6043 #if MDNS_LOG_ANSWER_SUPPRESSION_TIMES
6044 				rr->ImmedAnswerMarkTime = m->timenow;
6045 #endif
6046 				m->NextScheduledResponse = m->timenow;
6047 				// If we're already planning to send this on another interface, just send it on all interfaces
6048 				if (rr->ImmedAnswer && rr->ImmedAnswer != InterfaceID)
6049 					rr->ImmedAnswer = mDNSInterfaceMark;
6050 				else
6051 					{
6052 					rr->ImmedAnswer = InterfaceID;			// Record interface to send it on
6053 					if (SendUnicastResponse) rr->ImmedUnicast = mDNStrue;
6054 					if (srcaddr->type == mDNSAddrType_IPv4)
6055 						{
6056 						if      (mDNSIPv4AddressIsZero(rr->v4Requester))                rr->v4Requester = srcaddr->ip.v4;
6057 						else if (!mDNSSameIPv4Address(rr->v4Requester, srcaddr->ip.v4)) rr->v4Requester = onesIPv4Addr;
6058 						}
6059 					else if (srcaddr->type == mDNSAddrType_IPv6)
6060 						{
6061 						if      (mDNSIPv6AddressIsZero(rr->v6Requester))                rr->v6Requester = srcaddr->ip.v6;
6062 						else if (!mDNSSameIPv6Address(rr->v6Requester, srcaddr->ip.v6)) rr->v6Requester = onesIPv6Addr;
6063 						}
6064 					}
6065 				}
6066 			// If TC flag is set, it means we should expect that additional known answers may be coming in another packet,
6067 			// so we allow roughly half a second before deciding to reply (we've observed inter-packet delays of 100-200ms on 802.11)
6068 			// else, if record is a shared one, spread responses over 100ms to avoid implosion of simultaneous responses
6069 			// else, for a simple unique record reply, we can reply immediately; no need for delay
6070 			if      (query->h.flags.b[0] & kDNSFlag0_TC)            delayresponse = mDNSPlatformOneSecond * 20;	// Divided by 50 = 400ms
6071 			else if (rr->resrec.RecordType == kDNSRecordTypeShared) delayresponse = mDNSPlatformOneSecond;		// Divided by 50 = 20ms
6072 			}
6073 		else if (rr->NR_AdditionalTo && rr->NR_AdditionalTo->NR_AnswerTo == (mDNSu8*)~0)
6074 			{
6075 			// Since additional records are an optimization anyway, we only ever send them on one interface at a time
6076 			// If two clients on different interfaces do queries that invoke the same optional additional answer,
6077 			// then the earlier client is out of luck
6078 			rr->ImmedAdditional = InterfaceID;
6079 			// No need to set m->NextScheduledResponse here
6080 			// We'll send these additional records when we send them, or not, as the case may be
6081 			}
6082 		}
6083 
6084 	// ***
6085 	// *** 8. If we think other machines are likely to answer these questions, set our packet suppression timer
6086 	// ***
6087 	if (delayresponse && (!m->SuppressSending || (m->SuppressSending - m->timenow) < (delayresponse + 49) / 50))
6088 		{
6089 #if MDNS_LOG_ANSWER_SUPPRESSION_TIMES
6090 		mDNSs32 oldss = m->SuppressSending;
6091 		if (oldss && delayresponse)
6092 			LogMsg("Current SuppressSending delay%5ld; require%5ld", m->SuppressSending - m->timenow, (delayresponse + 49) / 50);
6093 #endif
6094 		// Pick a random delay:
6095 		// We start with the base delay chosen above (typically either 1 second or 20 seconds),
6096 		// and add a random value in the range 0-5 seconds (making 1-6 seconds or 20-25 seconds).
6097 		// This is an integer value, with resolution determined by the platform clock rate.
6098 		// We then divide that by 50 to get the delay value in ticks. We defer the division until last
6099 		// to get better results on platforms with coarse clock granularity (e.g. ten ticks per second).
6100 		// The +49 before dividing is to ensure we round up, not down, to ensure that even
6101 		// on platforms where the native clock rate is less than fifty ticks per second,
6102 		// we still guarantee that the final calculated delay is at least one platform tick.
6103 		// We want to make sure we don't ever allow the delay to be zero ticks,
6104 		// because if that happens we'll fail the Bonjour Conformance Test.
6105 		// Our final computed delay is 20-120ms for normal delayed replies,
6106 		// or 400-500ms in the case of multi-packet known-answer lists.
6107 		m->SuppressSending = m->timenow + (delayresponse + (mDNSs32)mDNSRandom((mDNSu32)mDNSPlatformOneSecond*5) + 49) / 50;
6108 		if (m->SuppressSending == 0) m->SuppressSending = 1;
6109 #if MDNS_LOG_ANSWER_SUPPRESSION_TIMES
6110 		if (oldss && delayresponse)
6111 			LogMsg("Set     SuppressSending to   %5ld", m->SuppressSending - m->timenow);
6112 #endif
6113 		}
6114 
6115 	// ***
6116 	// *** 9. If query is from a legacy client, or from a new client requesting a unicast reply, then generate a unicast response too
6117 	// ***
6118 	if (SendLegacyResponse)
6119 		responseptr = GenerateUnicastResponse(query, end, InterfaceID, LegacyQuery, response, ResponseRecords);
6120 
6121 exit:
6122 	m->rec.r.resrec.RecordType = 0;		// Clear RecordType to show we're not still using it
6123 
6124 	// ***
6125 	// *** 10. Finally, clear our link chains ready for use next time
6126 	// ***
6127 	while (ResponseRecords)
6128 		{
6129 		rr = ResponseRecords;
6130 		ResponseRecords = rr->NextResponse;
6131 		rr->NextResponse    = mDNSNULL;
6132 		rr->NR_AnswerTo     = mDNSNULL;
6133 		rr->NR_AdditionalTo = mDNSNULL;
6134 		}
6135 
6136 	while (ExpectedAnswers)
6137 		{
6138 		CacheRecord *cr = ExpectedAnswers;
6139 		ExpectedAnswers = cr->NextInKAList;
6140 		cr->NextInKAList = mDNSNULL;
6141 
6142 		// For non-truncated queries, we can definitively say that we should expect
6143 		// to be seeing a response for any records still left in the ExpectedAnswers list
6144 		if (!(query->h.flags.b[0] & kDNSFlag0_TC))
6145 			if (cr->UnansweredQueries == 0 || m->timenow - cr->LastUnansweredTime >= mDNSPlatformOneSecond)
6146 				{
6147 				cr->UnansweredQueries++;
6148 				cr->LastUnansweredTime = m->timenow;
6149 #if ENABLE_MULTI_PACKET_QUERY_SNOOPING
6150 				if (cr->UnansweredQueries > 1)
6151 					debugf("ProcessQuery: (!TC) UAQ %lu MPQ %lu MPKA %lu %s",
6152 						cr->UnansweredQueries, cr->MPUnansweredQ, cr->MPUnansweredKA, CRDisplayString(m, cr));
6153 #endif
6154 				SetNextCacheCheckTimeForRecord(m, cr);
6155 				}
6156 
6157 		// If we've seen multiple unanswered queries for this record,
6158 		// then mark it to expire in five seconds if we don't get a response by then.
6159 		if (cr->UnansweredQueries >= MaxUnansweredQueries)
6160 			{
6161 #if ENABLE_MULTI_PACKET_QUERY_SNOOPING
6162 			// Only show debugging message if this record was not about to expire anyway
6163 			if (RRExpireTime(cr) - m->timenow > 4 * mDNSPlatformOneSecond)
6164 				debugf("ProcessQuery: (Max) UAQ %lu MPQ %lu MPKA %lu mDNS_Reconfirm() for %s",
6165 					cr->UnansweredQueries, cr->MPUnansweredQ, cr->MPUnansweredKA, CRDisplayString(m, cr));
6166 #endif
6167 			mDNS_Reconfirm_internal(m, cr, kDefaultReconfirmTimeForNoAnswer);
6168 			}
6169 #if ENABLE_MULTI_PACKET_QUERY_SNOOPING
6170 		// Make a guess, based on the multi-packet query / known answer counts, whether we think we
6171 		// should have seen an answer for this. (We multiply MPQ by 4 and MPKA by 5, to allow for
6172 		// possible packet loss of up to 20% of the additional KA packets.)
6173 		else if (cr->MPUnansweredQ * 4 > cr->MPUnansweredKA * 5 + 8)
6174 			{
6175 			// We want to do this conservatively.
6176 			// If there are so many machines on the network that they have to use multi-packet known-answer lists,
6177 			// then we don't want them to all hit the network simultaneously with their final expiration queries.
6178 			// By setting the record to expire in four minutes, we achieve two things:
6179 			// (a) the 90-95% final expiration queries will be less bunched together
6180 			// (b) we allow some time for us to witness enough other failed queries that we don't have to do our own
6181 			mDNSu32 remain = (mDNSu32)(RRExpireTime(cr) - m->timenow) / 4;
6182 			if (remain > 240 * (mDNSu32)mDNSPlatformOneSecond)
6183 				remain = 240 * (mDNSu32)mDNSPlatformOneSecond;
6184 
6185 			// Only show debugging message if this record was not about to expire anyway
6186 			if (RRExpireTime(cr) - m->timenow > 4 * mDNSPlatformOneSecond)
6187 				debugf("ProcessQuery: (MPQ) UAQ %lu MPQ %lu MPKA %lu mDNS_Reconfirm() for %s",
6188 					cr->UnansweredQueries, cr->MPUnansweredQ, cr->MPUnansweredKA, CRDisplayString(m, cr));
6189 
6190 			if (remain <= 60 * (mDNSu32)mDNSPlatformOneSecond)
6191 				cr->UnansweredQueries++;	// Treat this as equivalent to one definite unanswered query
6192 			cr->MPUnansweredQ  = 0;			// Clear MPQ/MPKA statistics
6193 			cr->MPUnansweredKA = 0;
6194 			cr->MPExpectingKA  = mDNSfalse;
6195 
6196 			if (remain < kDefaultReconfirmTimeForNoAnswer)
6197 				remain = kDefaultReconfirmTimeForNoAnswer;
6198 			mDNS_Reconfirm_internal(m, cr, remain);
6199 			}
6200 #endif
6201 		}
6202 
6203 	while (DupQuestions)
6204 		{
6205 		DNSQuestion *q = DupQuestions;
6206 		DupQuestions = q->NextInDQList;
6207 		q->NextInDQList = mDNSNULL;
6208 		i = RecordDupSuppressInfo(q->DupSuppress, m->timenow, InterfaceID, srcaddr->type);
6209 		debugf("ProcessQuery: Recorded DSI for %##s (%s) on %p/%s %d", q->qname.c, DNSTypeName(q->qtype), InterfaceID,
6210 			srcaddr->type == mDNSAddrType_IPv4 ? "v4" : "v6", i);
6211 		}
6212 
6213 	return(responseptr);
6214 	}
6215 
mDNSCoreReceiveQuery(mDNS * const m,const DNSMessage * const msg,const mDNSu8 * const end,const mDNSAddr * srcaddr,const mDNSIPPort srcport,const mDNSAddr * dstaddr,mDNSIPPort dstport,const mDNSInterfaceID InterfaceID)6216 mDNSlocal void mDNSCoreReceiveQuery(mDNS *const m, const DNSMessage *const msg, const mDNSu8 *const end,
6217 	const mDNSAddr *srcaddr, const mDNSIPPort srcport, const mDNSAddr *dstaddr, mDNSIPPort dstport,
6218 	const mDNSInterfaceID InterfaceID)
6219 	{
6220 	mDNSu8    *responseend = mDNSNULL;
6221 	mDNSBool   QueryWasLocalUnicast = srcaddr && dstaddr &&
6222 		!mDNSAddrIsDNSMulticast(dstaddr) && mDNS_AddressIsLocalSubnet(m, InterfaceID, srcaddr);
6223 
6224 	if (!InterfaceID && dstaddr && mDNSAddrIsDNSMulticast(dstaddr))
6225 		{
6226 		LogMsg("Ignoring Query from %#-15a:%-5d to %#-15a:%-5d on 0x%p with "
6227 			"%2d Question%s %2d Answer%s %2d Authorit%s %2d Additional%s %d bytes (Multicast, but no InterfaceID)",
6228 			srcaddr, mDNSVal16(srcport), dstaddr, mDNSVal16(dstport), InterfaceID,
6229 			msg->h.numQuestions,   msg->h.numQuestions   == 1 ? ", "   : "s,",
6230 			msg->h.numAnswers,     msg->h.numAnswers     == 1 ? ", "   : "s,",
6231 			msg->h.numAuthorities, msg->h.numAuthorities == 1 ? "y,  " : "ies,",
6232 			msg->h.numAdditionals, msg->h.numAdditionals == 1 ? " "    : "s", end - msg->data);
6233 		return;
6234 		}
6235 
6236 	verbosedebugf("Received Query from %#-15a:%-5d to %#-15a:%-5d on 0x%p with "
6237 		"%2d Question%s %2d Answer%s %2d Authorit%s %2d Additional%s %d bytes",
6238 		srcaddr, mDNSVal16(srcport), dstaddr, mDNSVal16(dstport), InterfaceID,
6239 		msg->h.numQuestions,   msg->h.numQuestions   == 1 ? ", "   : "s,",
6240 		msg->h.numAnswers,     msg->h.numAnswers     == 1 ? ", "   : "s,",
6241 		msg->h.numAuthorities, msg->h.numAuthorities == 1 ? "y,  " : "ies,",
6242 		msg->h.numAdditionals, msg->h.numAdditionals == 1 ? " "    : "s", end - msg->data);
6243 
6244 	responseend = ProcessQuery(m, msg, end, srcaddr, InterfaceID,
6245 		!mDNSSameIPPort(srcport, MulticastDNSPort), mDNSAddrIsDNSMulticast(dstaddr), QueryWasLocalUnicast, &m->omsg);
6246 
6247 	if (responseend)	// If responseend is non-null, that means we built a unicast response packet
6248 		{
6249 		debugf("Unicast Response: %d Question%s, %d Answer%s, %d Additional%s to %#-15a:%d on %p/%ld",
6250 			m->omsg.h.numQuestions,   m->omsg.h.numQuestions   == 1 ? "" : "s",
6251 			m->omsg.h.numAnswers,     m->omsg.h.numAnswers     == 1 ? "" : "s",
6252 			m->omsg.h.numAdditionals, m->omsg.h.numAdditionals == 1 ? "" : "s",
6253 			srcaddr, mDNSVal16(srcport), InterfaceID, srcaddr->type);
6254 		mDNSSendDNSMessage(m, &m->omsg, responseend, InterfaceID, mDNSNULL, srcaddr, srcport, mDNSNULL, mDNSNULL);
6255 		}
6256 	}
6257 
6258 #if 0
6259 mDNSlocal mDNSBool TrustedSource(const mDNS *const m, const mDNSAddr *const srcaddr)
6260 	{
6261 	DNSServer *s;
6262 	(void)m; // Unused
6263 	(void)srcaddr; // Unused
6264 	for (s = m->DNSServers; s; s = s->next)
6265 		if (mDNSSameAddress(srcaddr, &s->addr)) return(mDNStrue);
6266 	return(mDNSfalse);
6267 	}
6268 #endif
6269 
6270 struct UDPSocket_struct
6271 	{
6272 	mDNSIPPort port; // MUST BE FIRST FIELD -- mDNSCoreReceive expects every UDPSocket_struct to begin with mDNSIPPort port
6273 	};
6274 
ExpectingUnicastResponseForQuestion(const mDNS * const m,const mDNSIPPort port,const mDNSOpaque16 id,const DNSQuestion * const question,mDNSBool tcp)6275 mDNSlocal DNSQuestion *ExpectingUnicastResponseForQuestion(const mDNS *const m, const mDNSIPPort port, const mDNSOpaque16 id, const DNSQuestion *const question, mDNSBool tcp)
6276 	{
6277 	DNSQuestion *q;
6278 	for (q = m->Questions; q; q=q->next)
6279 		{
6280 		if (!tcp && !q->LocalSocket) continue;
6281 		if (mDNSSameIPPort(tcp ? q->tcpSrcPort : q->LocalSocket->port, port)     &&
6282 			mDNSSameOpaque16(q->TargetQID,         id)       &&
6283 			q->qtype                  == question->qtype     &&
6284 			q->qclass                 == question->qclass    &&
6285 			q->qnamehash              == question->qnamehash &&
6286 			SameDomainName(&q->qname, &question->qname))
6287 			return(q);
6288 		}
6289 	return(mDNSNULL);
6290 	}
6291 
6292 // This function is called when we receive a unicast response. This could be the case of a unicast response from the
6293 // DNS server or a response to the QU query. Hence, the cache record's InterfaceId can be both NULL or non-NULL (QU case)
ExpectingUnicastResponseForRecord(mDNS * const m,const mDNSAddr * const srcaddr,const mDNSBool SrcLocal,const mDNSIPPort port,const mDNSOpaque16 id,const CacheRecord * const rr,mDNSBool tcp)6294 mDNSlocal DNSQuestion *ExpectingUnicastResponseForRecord(mDNS *const m,
6295 	const mDNSAddr *const srcaddr, const mDNSBool SrcLocal, const mDNSIPPort port, const mDNSOpaque16 id, const CacheRecord *const rr, mDNSBool tcp)
6296 	{
6297 	DNSQuestion *q;
6298 	(void)id;
6299 	(void)srcaddr;
6300 
6301 	for (q = m->Questions; q; q=q->next)
6302 		{
6303 		if (!q->DuplicateOf && ResourceRecordAnswersUnicastResponse(&rr->resrec, q))
6304 			{
6305 			if (!mDNSOpaque16IsZero(q->TargetQID))
6306 				{
6307 				debugf("ExpectingUnicastResponseForRecord msg->h.id %d q->TargetQID %d for %s", mDNSVal16(id), mDNSVal16(q->TargetQID), CRDisplayString(m, rr));
6308 
6309 				if (mDNSSameOpaque16(q->TargetQID, id))
6310 					{
6311 					mDNSIPPort srcp;
6312 					if (!tcp)
6313 						{
6314 						srcp = q->LocalSocket ? q->LocalSocket->port : zeroIPPort;
6315 						}
6316 					else
6317 						{
6318 						srcp = q->tcpSrcPort;
6319 						}
6320 					if (mDNSSameIPPort(srcp, port)) return(q);
6321 
6322 				//	if (mDNSSameAddress(srcaddr, &q->Target))                   return(mDNStrue);
6323 				//	if (q->LongLived && mDNSSameAddress(srcaddr, &q->servAddr)) return(mDNStrue); Shouldn't need this now that we have LLQType checking
6324 				//	if (TrustedSource(m, srcaddr))                              return(mDNStrue);
6325 					LogInfo("WARNING: Ignoring suspect uDNS response for %##s (%s) [q->Target %#a:%d] from %#a:%d %s",
6326 						q->qname.c, DNSTypeName(q->qtype), &q->Target, mDNSVal16(srcp), srcaddr, mDNSVal16(port), CRDisplayString(m, rr));
6327 					return(mDNSNULL);
6328 					}
6329 				}
6330 			else
6331 				{
6332 				if (SrcLocal && q->ExpectUnicastResp && (mDNSu32)(m->timenow - q->ExpectUnicastResp) < (mDNSu32)(mDNSPlatformOneSecond*2))
6333 					return(q);
6334 				}
6335 			}
6336 		}
6337 	return(mDNSNULL);
6338 	}
6339 
6340 // Certain data types need more space for in-memory storage than their in-packet rdlength would imply
6341 // Currently this applies only to rdata types containing more than one domainname,
6342 // or types where the domainname is not the last item in the structure.
6343 // In addition, NSEC currently requires less space for in-memory storage than its in-packet representation.
GetRDLengthMem(const ResourceRecord * const rr)6344 mDNSlocal mDNSu16 GetRDLengthMem(const ResourceRecord *const rr)
6345 	{
6346 	switch (rr->rrtype)
6347 		{
6348 		case kDNSType_SOA: return sizeof(rdataSOA);
6349 		case kDNSType_RP:  return sizeof(rdataRP);
6350 		case kDNSType_PX:  return sizeof(rdataPX);
6351 		case kDNSType_NSEC:return sizeof(rdataNSEC);
6352 		default:           return rr->rdlength;
6353 		}
6354 	}
6355 
CreateNewCacheEntry(mDNS * const m,const mDNSu32 slot,CacheGroup * cg,mDNSs32 delay)6356 mDNSexport CacheRecord *CreateNewCacheEntry(mDNS *const m, const mDNSu32 slot, CacheGroup *cg, mDNSs32 delay)
6357 	{
6358 	CacheRecord *rr = mDNSNULL;
6359 	mDNSu16 RDLength = GetRDLengthMem(&m->rec.r.resrec);
6360 
6361 	if (!m->rec.r.resrec.InterfaceID) debugf("CreateNewCacheEntry %s", CRDisplayString(m, &m->rec.r));
6362 
6363 	//if (RDLength > InlineCacheRDSize)
6364 	//	LogInfo("Rdata len %4d > InlineCacheRDSize %d %s", RDLength, InlineCacheRDSize, CRDisplayString(m, &m->rec.r));
6365 
6366 	if (!cg) cg = GetCacheGroup(m, slot, &m->rec.r.resrec);	// If we don't have a CacheGroup for this name, make one now
6367 	if (cg)  rr = GetCacheRecord(m, cg, RDLength);	// Make a cache record, being careful not to recycle cg
6368 	if (!rr) NoCacheAnswer(m, &m->rec.r);
6369 	else
6370 		{
6371 		RData *saveptr = rr->resrec.rdata;		// Save the rr->resrec.rdata pointer
6372 		*rr = m->rec.r;							// Block copy the CacheRecord object
6373 		rr->resrec.rdata  = saveptr;				// Restore rr->resrec.rdata after the structure assignment
6374 		rr->resrec.name   = cg->name;			// And set rr->resrec.name to point into our CacheGroup header
6375 		rr->DelayDelivery = delay;
6376 
6377 		// If this is an oversized record with external storage allocated, copy rdata to external storage
6378 		if      (rr->resrec.rdata == (RData*)&rr->smallrdatastorage && RDLength > InlineCacheRDSize)
6379 			LogMsg("rr->resrec.rdata == &rr->rdatastorage but length > InlineCacheRDSize %##s", m->rec.r.resrec.name->c);
6380 		else if (rr->resrec.rdata != (RData*)&rr->smallrdatastorage && RDLength <= InlineCacheRDSize)
6381 			LogMsg("rr->resrec.rdata != &rr->rdatastorage but length <= InlineCacheRDSize %##s", m->rec.r.resrec.name->c);
6382 		if (RDLength > InlineCacheRDSize)
6383 			mDNSPlatformMemCopy(rr->resrec.rdata, m->rec.r.resrec.rdata, sizeofRDataHeader + RDLength);
6384 
6385 		rr->next = mDNSNULL;					// Clear 'next' pointer
6386 		*(cg->rrcache_tail) = rr;				// Append this record to tail of cache slot list
6387 		cg->rrcache_tail = &(rr->next);			// Advance tail pointer
6388 
6389 		CacheRecordAdd(m, rr);	// CacheRecordAdd calls SetNextCacheCheckTimeForRecord(m, rr); for us
6390 		}
6391 	return(rr);
6392 	}
6393 
RefreshCacheRecord(mDNS * const m,CacheRecord * rr,mDNSu32 ttl)6394 mDNSlocal void RefreshCacheRecord(mDNS *const m, CacheRecord *rr, mDNSu32 ttl)
6395 	{
6396 	rr->TimeRcvd             = m->timenow;
6397 	rr->resrec.rroriginalttl = ttl;
6398 	rr->UnansweredQueries = 0;
6399 #if ENABLE_MULTI_PACKET_QUERY_SNOOPING
6400 	rr->MPUnansweredQ     = 0;
6401 	rr->MPUnansweredKA    = 0;
6402 	rr->MPExpectingKA     = mDNSfalse;
6403 #endif
6404 	SetNextCacheCheckTimeForRecord(m, rr);
6405 	}
6406 
GrantCacheExtensions(mDNS * const m,DNSQuestion * q,mDNSu32 lease)6407 mDNSexport void GrantCacheExtensions(mDNS *const m, DNSQuestion *q, mDNSu32 lease)
6408 	{
6409 	CacheRecord *rr;
6410 	const mDNSu32 slot = HashSlot(&q->qname);
6411 	CacheGroup *cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname);
6412 	for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next)
6413 		if (rr->CRActiveQuestion == q)
6414 			{
6415 			//LogInfo("GrantCacheExtensions: new lease %d / %s", lease, CRDisplayString(m, rr));
6416 			RefreshCacheRecord(m, rr, lease);
6417 			}
6418 	}
6419 
GetEffectiveTTL(const uDNS_LLQType LLQType,mDNSu32 ttl)6420 mDNSlocal mDNSu32 GetEffectiveTTL(const uDNS_LLQType LLQType, mDNSu32 ttl)		// TTL in seconds
6421 	{
6422 	if      (LLQType == uDNS_LLQ_Entire) ttl = kLLQ_DefLease;
6423 	else if (LLQType == uDNS_LLQ_Events)
6424 		{
6425 		// If the TTL is -1 for uDNS LLQ event packet, that means "remove"
6426 		if (ttl == 0xFFFFFFFF) ttl = 0;
6427 		else                   ttl = kLLQ_DefLease;
6428 		}
6429 	else	// else not LLQ (standard uDNS response)
6430 		{
6431 		// The TTL is already capped to a maximum value in GetLargeResourceRecord, but just to be extra safe we
6432 		// also do this check here to make sure we can't get overflow below when we add a quarter to the TTL
6433 		if (ttl > 0x60000000UL / mDNSPlatformOneSecond) ttl = 0x60000000UL / mDNSPlatformOneSecond;
6434 
6435 		// Adjustment factor to avoid race condition:
6436 		// Suppose real record as TTL of 3600, and our local caching server has held it for 3500 seconds, so it returns an aged TTL of 100.
6437 		// If we do our normal refresh at 80% of the TTL, our local caching server will return 20 seconds, so we'll do another
6438 		// 80% refresh after 16 seconds, and then the server will return 4 seconds, and so on, in the fashion of Zeno's paradox.
6439 		// To avoid this, we extend the record's effective TTL to give it a little extra grace period.
6440 		// We adjust the 100 second TTL to 126. This means that when we do our 80% query at 101 seconds,
6441 		// the cached copy at our local caching server will already have expired, so the server will be forced
6442 		// to fetch a fresh copy from the authoritative server, and then return a fresh record with the full TTL of 3600 seconds.
6443 		ttl += ttl/4 + 2;
6444 
6445 		// For mDNS, TTL zero means "delete this record"
6446 		// For uDNS, TTL zero means: this data is true at this moment, but don't cache it.
6447 		// For the sake of network efficiency, we impose a minimum effective TTL of 15 seconds.
6448 		// This means that we'll do our 80, 85, 90, 95% queries at 12.00, 12.75, 13.50, 14.25 seconds
6449 		// respectively, and then if we get no response, delete the record from the cache at 15 seconds.
6450 		// This gives the server up to three seconds to respond between when we send our 80% query at 12 seconds
6451 		// and when we delete the record at 15 seconds. Allowing cache lifetimes less than 15 seconds would
6452 		// (with the current code) result in the server having even less than three seconds to respond
6453 		// before we deleted the record and reported a "remove" event to any active questions.
6454 		// Furthermore, with the current code, if we were to allow a TTL of less than 2 seconds
6455 		// then things really break (e.g. we end up making a negative cache entry).
6456 		// In the future we may want to revisit this and consider properly supporting non-cached (TTL=0) uDNS answers.
6457 		if (ttl < 15) ttl = 15;
6458 		}
6459 
6460 	return ttl;
6461 	}
6462 
6463 // Note: mDNSCoreReceiveResponse calls mDNS_Deregister_internal which can call a user callback, which may change
6464 // the record list and/or question list.
6465 // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this.
6466 // InterfaceID non-NULL tells us the interface this multicast response was received on
6467 // InterfaceID NULL tells us this was a unicast response
6468 // dstaddr NULL tells us we received this over an outgoing TCP connection we made
mDNSCoreReceiveResponse(mDNS * const m,const DNSMessage * const response,const mDNSu8 * end,const mDNSAddr * srcaddr,const mDNSIPPort srcport,const mDNSAddr * dstaddr,mDNSIPPort dstport,const mDNSInterfaceID InterfaceID)6469 mDNSlocal void mDNSCoreReceiveResponse(mDNS *const m,
6470 	const DNSMessage *const response, const mDNSu8 *end,
6471 	const mDNSAddr *srcaddr, const mDNSIPPort srcport, const mDNSAddr *dstaddr, mDNSIPPort dstport,
6472 	const mDNSInterfaceID InterfaceID)
6473 	{
6474 	int i;
6475 	mDNSBool ResponseMCast    = dstaddr && mDNSAddrIsDNSMulticast(dstaddr);
6476 	mDNSBool ResponseSrcLocal = !srcaddr || mDNS_AddressIsLocalSubnet(m, InterfaceID, srcaddr);
6477 	DNSQuestion *llqMatch = mDNSNULL;
6478 	uDNS_LLQType LLQType      = uDNS_recvLLQResponse(m, response, end, srcaddr, srcport, &llqMatch);
6479 
6480 	// "(CacheRecord*)1" is a special (non-zero) end-of-list marker
6481 	// We use this non-zero marker so that records in our CacheFlushRecords list will always have NextInCFList
6482 	// set non-zero, and that tells GetCacheEntity() that they're not, at this moment, eligible for recycling.
6483 	CacheRecord *CacheFlushRecords = (CacheRecord*)1;
6484 	CacheRecord **cfp = &CacheFlushRecords;
6485 
6486 	// All records in a DNS response packet are treated as equally valid statements of truth. If we want
6487 	// to guard against spoof responses, then the only credible protection against that is cryptographic
6488 	// security, e.g. DNSSEC., not worring about which section in the spoof packet contained the record
6489 	int firstauthority  =                   response->h.numAnswers;
6490 	int firstadditional = firstauthority  + response->h.numAuthorities;
6491 	int totalrecords    = firstadditional + response->h.numAdditionals;
6492 	const mDNSu8 *ptr   = response->data;
6493 	DNSServer *uDNSServer = mDNSNULL;
6494 
6495 	debugf("Received Response from %#-15a addressed to %#-15a on %p with "
6496 		"%2d Question%s %2d Answer%s %2d Authorit%s %2d Additional%s %d bytes LLQType %d",
6497 		srcaddr, dstaddr, InterfaceID,
6498 		response->h.numQuestions,   response->h.numQuestions   == 1 ? ", "   : "s,",
6499 		response->h.numAnswers,     response->h.numAnswers     == 1 ? ", "   : "s,",
6500 		response->h.numAuthorities, response->h.numAuthorities == 1 ? "y,  " : "ies,",
6501 		response->h.numAdditionals, response->h.numAdditionals == 1 ? " "    : "s", end - response->data, LLQType);
6502 
6503 	// According to RFC 2181 <http://www.ietf.org/rfc/rfc2181.txt>
6504 	//    When a DNS client receives a reply with TC
6505 	//    set, it should ignore that response, and query again, using a
6506 	//    mechanism, such as a TCP connection, that will permit larger replies.
6507 	// It feels wrong to be throwing away data after the network went to all the trouble of delivering it to us, but
6508 	// delivering some records of the RRSet first and then the remainder a couple of milliseconds later was causing
6509 	// failures in our Microsoft Active Directory client, which expects to get the entire set of answers at once.
6510 	// <rdar://problem/6690034> Can't bind to Active Directory
6511 	// In addition, if the client immediately canceled its query after getting the initial partial response, then we'll
6512 	// abort our TCP connection, and not complete the operation, and end up with an incomplete RRSet in our cache.
6513 	// Next time there's a query for this RRSet we'll see answers in our cache, and assume we have the whole RRSet already,
6514 	// and not even do the TCP query.
6515 	// Accordingly, if we get a uDNS reply with kDNSFlag0_TC set, we bail out and wait for the TCP response containing the entire RRSet.
6516 	if (!InterfaceID && (response->h.flags.b[0] & kDNSFlag0_TC)) return;
6517 
6518 	if (LLQType == uDNS_LLQ_Ignore) return;
6519 
6520 	// 1. We ignore questions (if any) in mDNS response packets
6521 	// 2. If this is an LLQ response, we handle it much the same
6522 	// 3. If we get a uDNS UDP response with the TC (truncated) bit set, then we can't treat this
6523 	//    answer as being the authoritative complete RRSet, and respond by deleting all other
6524 	//    matching cache records that don't appear in this packet.
6525 	// Otherwise, this is a authoritative uDNS answer, so arrange for any stale records to be purged
6526 	if (ResponseMCast || LLQType == uDNS_LLQ_Events || (response->h.flags.b[0] & kDNSFlag0_TC))
6527 		ptr = LocateAnswers(response, end);
6528 	// Otherwise, for one-shot queries, any answers in our cache that are not also contained
6529 	// in this response packet are immediately deemed to be invalid.
6530 	else
6531 		{
6532 		mDNSu8 rcode = (mDNSu8)(response->h.flags.b[1] & kDNSFlag1_RC_Mask);
6533 		mDNSBool failure = !(rcode == kDNSFlag1_RC_NoErr || rcode == kDNSFlag1_RC_NXDomain || rcode == kDNSFlag1_RC_NotAuth);
6534 		mDNSBool returnEarly = mDNSfalse;
6535 		// We could possibly combine this with the similar loop at the end of this function --
6536 		// instead of tagging cache records here and then rescuing them if we find them in the answer section,
6537 		// we could instead use the "m->PktNum" mechanism to tag each cache record with the packet number in
6538 		// which it was received (or refreshed), and then at the end if we find any cache records which
6539 		// answer questions in this packet's question section, but which aren't tagged with this packet's
6540 		// packet number, then we deduce they are old and delete them
6541 		for (i = 0; i < response->h.numQuestions && ptr && ptr < end; i++)
6542 			{
6543 			DNSQuestion q, *qptr = mDNSNULL;
6544 			ptr = getQuestion(response, ptr, end, InterfaceID, &q);
6545 			if (ptr && (qptr = ExpectingUnicastResponseForQuestion(m, dstport, response->h.id, &q, !dstaddr)))
6546 				{
6547 				if (!failure)
6548 					{
6549 					CacheRecord *rr;
6550 					const mDNSu32 slot = HashSlot(&q.qname);
6551 					CacheGroup *cg = CacheGroupForName(m, slot, q.qnamehash, &q.qname);
6552 					for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next)
6553 						if (SameNameRecordAnswersQuestion(&rr->resrec, qptr))
6554 							{
6555 							debugf("uDNS marking %p %##s (%s) %p %s", q.InterfaceID, q.qname.c, DNSTypeName(q.qtype),
6556 								rr->resrec.InterfaceID, CRDisplayString(m, rr));
6557 							// Don't want to disturb rroriginalttl here, because code below might need it for the exponential backoff doubling algorithm
6558 							rr->TimeRcvd          = m->timenow - TicksTTL(rr) - 1;
6559 							rr->UnansweredQueries = MaxUnansweredQueries;
6560 							}
6561 					}
6562 				else
6563 					{
6564 					if (qptr)
6565 						{
6566 						LogInfo("mDNSCoreReceiveResponse: Server %p responded with code %d to query %##s (%s)", qptr->qDNSServer, rcode, q.qname.c, DNSTypeName(q.qtype));
6567 						PenalizeDNSServer(m, qptr);
6568 						}
6569 					returnEarly = mDNStrue;
6570 					}
6571 				}
6572 			}
6573 		if (returnEarly)
6574 			{
6575 			LogInfo("Ignoring %2d Answer%s %2d Authorit%s %2d Additional%s",
6576 				response->h.numAnswers,     response->h.numAnswers     == 1 ? ", " : "s,",
6577 				response->h.numAuthorities, response->h.numAuthorities == 1 ? "y,  " : "ies,",
6578 				response->h.numAdditionals, response->h.numAdditionals == 1 ? "" : "s");
6579 			// not goto exit because we won't have any CacheFlushRecords and we do not want to
6580 			// generate negative cache entries (we want to query the next server)
6581 			return;
6582 			}
6583 		}
6584 
6585 	for (i = 0; i < totalrecords && ptr && ptr < end; i++)
6586 		{
6587 		// All responses sent via LL multicast are acceptable for caching
6588 		// All responses received over our outbound TCP connections are acceptable for caching
6589 		mDNSBool AcceptableResponse = ResponseMCast || !dstaddr || LLQType;
6590 		// (Note that just because we are willing to cache something, that doesn't necessarily make it a trustworthy answer
6591 		// to any specific question -- any code reading records from the cache needs to make that determination for itself.)
6592 
6593 		const mDNSu8 RecordType =
6594 			(i < firstauthority ) ? (mDNSu8)kDNSRecordTypePacketAns  :
6595 			(i < firstadditional) ? (mDNSu8)kDNSRecordTypePacketAuth : (mDNSu8)kDNSRecordTypePacketAdd;
6596 		ptr = GetLargeResourceRecord(m, response, ptr, end, InterfaceID, RecordType, &m->rec);
6597 		if (!ptr) goto exit;		// Break out of the loop and clean up our CacheFlushRecords list before exiting
6598 		if (m->rec.r.resrec.RecordType == kDNSRecordTypePacketNegative) { m->rec.r.resrec.RecordType = 0; continue; }
6599 
6600 		// Don't want to cache OPT or TSIG pseudo-RRs
6601 		if (m->rec.r.resrec.rrtype == kDNSType_TSIG) { m->rec.r.resrec.RecordType = 0; continue; }
6602 		if (m->rec.r.resrec.rrtype == kDNSType_OPT)
6603 			{
6604 			const rdataOPT *opt;
6605 			const rdataOPT *const e = (const rdataOPT *)&m->rec.r.resrec.rdata->u.data[m->rec.r.resrec.rdlength];
6606 			// Find owner sub-option(s). We verify that the MAC is non-zero, otherwise we could inadvertently
6607 			// delete all our own AuthRecords (which are identified by having zero MAC tags on them).
6608 			for (opt = &m->rec.r.resrec.rdata->u.opt[0]; opt < e; opt++)
6609 				if (opt->opt == kDNSOpt_Owner && opt->u.owner.vers == 0 && opt->u.owner.HMAC.l[0])
6610 					{
6611 					ClearProxyRecords(m, &opt->u.owner, m->DuplicateRecords);
6612 					ClearProxyRecords(m, &opt->u.owner, m->ResourceRecords);
6613 					}
6614 			m->rec.r.resrec.RecordType = 0;
6615 			continue;
6616 			}
6617 
6618 		// if a CNAME record points to itself, then don't add it to the cache
6619 		if ((m->rec.r.resrec.rrtype == kDNSType_CNAME) && SameDomainName(m->rec.r.resrec.name, &m->rec.r.resrec.rdata->u.name))
6620 			{
6621 			LogInfo("mDNSCoreReceiveResponse: CNAME loop domain name %##s", m->rec.r.resrec.name->c);
6622 			m->rec.r.resrec.RecordType = 0;
6623 			continue;
6624 			}
6625 
6626 		// When we receive uDNS LLQ responses, we assume a long cache lifetime --
6627 		// In the case of active LLQs, we'll get remove events when the records actually do go away
6628 		// In the case of polling LLQs, we assume the record remains valid until the next poll
6629 		if (!mDNSOpaque16IsZero(response->h.id))
6630 			m->rec.r.resrec.rroriginalttl = GetEffectiveTTL(LLQType, m->rec.r.resrec.rroriginalttl);
6631 
6632 		// If response was not sent via LL multicast,
6633 		// then see if it answers a recent query of ours, which would also make it acceptable for caching.
6634 		if (!ResponseMCast)
6635 			{
6636 			if (LLQType)
6637 				{
6638 				// For Long Lived queries that are both sent over UDP and Private TCP, LLQType is set.
6639 				// Even though it is AcceptableResponse, we need a matching DNSServer pointer for the
6640 				// queries to get ADD/RMV events. To lookup the question, we can't use
6641 				// ExpectingUnicastResponseForRecord as the port numbers don't match. uDNS_recvLLQRespose
6642 				// has already matched the question using the 64 bit Id in the packet and we use that here.
6643 
6644 				if (llqMatch != mDNSNULL) m->rec.r.resrec.rDNSServer = uDNSServer = llqMatch->qDNSServer;
6645 				}
6646 			else if (!AcceptableResponse || !dstaddr)
6647 				{
6648 				// For responses that come over TCP (Responses that can't fit within UDP) or TLS (Private queries
6649 				// that are not long lived e.g., AAAA lookup in a Private domain), it is indicated by !dstaddr.
6650 				// Even though it is AcceptableResponse, we still need a DNSServer pointer for the resource records that
6651 				// we create.
6652 
6653 				DNSQuestion *q = ExpectingUnicastResponseForRecord(m, srcaddr, ResponseSrcLocal, dstport, response->h.id, &m->rec.r, !dstaddr);
6654 
6655 				// Intialize the DNS server on the resource record which will now filter what questions we answer with
6656 				// this record.
6657 				//
6658 				// We could potentially lookup the DNS server based on the source address, but that may not work always
6659 				// and that's why ExpectingUnicastResponseForRecord does not try to verify whether the response came
6660 				// from the DNS server that queried. We follow the same logic here. If we can find a matching quetion based
6661 				// on the "id" and "source port", then this response answers the question and assume the response
6662 				// came from the same DNS server that we sent the query to.
6663 
6664 				if (q != mDNSNULL)
6665 					{
6666 					AcceptableResponse = mDNStrue;
6667 					if (!InterfaceID)
6668 						{
6669 						debugf("mDNSCoreReceiveResponse: InterfaceID %p %##s (%s)", q->InterfaceID, q->qname.c, DNSTypeName(q->qtype));
6670 						m->rec.r.resrec.rDNSServer = uDNSServer = q->qDNSServer;
6671 						}
6672 					}
6673 				else
6674 					{
6675 					// If we can't find a matching question, we need to see whether we have seen records earlier that matched
6676 					// the question. The code below does that. So, make this record unacceptable for now
6677 					if (!InterfaceID)
6678 						{
6679 						debugf("mDNSCoreReceiveResponse: Can't find question for record name %##s", m->rec.r.resrec.name->c);
6680 						AcceptableResponse = mDNSfalse;
6681 						}
6682 					}
6683 				}
6684 			}
6685 
6686 		// 1. Check that this packet resource record does not conflict with any of ours
6687 		if (mDNSOpaque16IsZero(response->h.id) && m->rec.r.resrec.rrtype != kDNSType_NSEC)
6688 			{
6689 			if (m->CurrentRecord)
6690 				LogMsg("mDNSCoreReceiveResponse ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord));
6691 			m->CurrentRecord = m->ResourceRecords;
6692 			while (m->CurrentRecord)
6693 				{
6694 				AuthRecord *rr = m->CurrentRecord;
6695 				m->CurrentRecord = rr->next;
6696 				// We accept all multicast responses, and unicast responses resulting from queries we issued
6697 				// For other unicast responses, this code accepts them only for responses with an
6698 				// (apparently) local source address that pertain to a record of our own that's in probing state
6699 				if (!AcceptableResponse && !(ResponseSrcLocal && rr->resrec.RecordType == kDNSRecordTypeUnique)) continue;
6700 
6701 				if (PacketRRMatchesSignature(&m->rec.r, rr))		// If interface, name, type (if shared record) and class match...
6702 					{
6703 					// ... check to see if type and rdata are identical
6704 					if (IdenticalSameNameRecord(&m->rec.r.resrec, &rr->resrec))
6705 						{
6706 						// If the RR in the packet is identical to ours, just check they're not trying to lower the TTL on us
6707 						if (m->rec.r.resrec.rroriginalttl >= rr->resrec.rroriginalttl/2 || m->SleepState)
6708 							{
6709 							// If we were planning to send on this -- and only this -- interface, then we don't need to any more
6710 							if      (rr->ImmedAnswer == InterfaceID) { rr->ImmedAnswer = mDNSNULL; rr->ImmedUnicast = mDNSfalse; }
6711 							}
6712 						else
6713 							{
6714 							if      (rr->ImmedAnswer == mDNSNULL)    { rr->ImmedAnswer = InterfaceID;       m->NextScheduledResponse = m->timenow; }
6715 							else if (rr->ImmedAnswer != InterfaceID) { rr->ImmedAnswer = mDNSInterfaceMark; m->NextScheduledResponse = m->timenow; }
6716 							}
6717 						}
6718 					// else, the packet RR has different type or different rdata -- check to see if this is a conflict
6719 					else if (m->rec.r.resrec.rroriginalttl > 0 && PacketRRConflict(m, rr, &m->rec.r))
6720 						{
6721 						LogInfo("mDNSCoreReceiveResponse: Pkt Record: %08lX %s", m->rec.r.resrec.rdatahash, CRDisplayString(m, &m->rec.r));
6722 						LogInfo("mDNSCoreReceiveResponse: Our Record: %08lX %s", rr->     resrec.rdatahash, ARDisplayString(m, rr));
6723 
6724 						// If this record is marked DependentOn another record for conflict detection purposes,
6725 						// then *that* record has to be bumped back to probing state to resolve the conflict
6726 						if (rr->DependentOn)
6727 							{
6728 							while (rr->DependentOn) rr = rr->DependentOn;
6729 							LogInfo("mDNSCoreReceiveResponse: Dep Record: %08lX %s", rr->     resrec.rdatahash, ARDisplayString(m, rr));
6730 							}
6731 
6732 						// If we've just whacked this record's ProbeCount, don't need to do it again
6733 						if (rr->ProbeCount > DefaultProbeCountForTypeUnique)
6734 							LogInfo("mDNSCoreReceiveResponse: Already reset to Probing: %s", ARDisplayString(m, rr));
6735 						else if (rr->ProbeCount == DefaultProbeCountForTypeUnique)
6736 							LogMsg("mDNSCoreReceiveResponse: Ignoring response received before we even began probing: %s", ARDisplayString(m, rr));
6737 						else
6738 							{
6739 							LogMsg("mDNSCoreReceiveResponse: Received from %#a:%d %s", srcaddr, mDNSVal16(srcport), CRDisplayString(m, &m->rec.r));
6740 							// If we'd previously verified this record, put it back to probing state and try again
6741 							if (rr->resrec.RecordType == kDNSRecordTypeVerified)
6742 								{
6743 								LogMsg("mDNSCoreReceiveResponse: Resetting to Probing: %s", ARDisplayString(m, rr));
6744 								rr->resrec.RecordType     = kDNSRecordTypeUnique;
6745 								// We set ProbeCount to one more than the usual value so we know we've already touched this record.
6746 								// This is because our single probe for "example-name.local" could yield a response with (say) two A records and
6747 								// three AAAA records in it, and we don't want to call RecordProbeFailure() five times and count that as five conflicts.
6748 								// This special value is recognised and reset to DefaultProbeCountForTypeUnique in SendQueries().
6749 								rr->ProbeCount     = DefaultProbeCountForTypeUnique + 1;
6750 								rr->AnnounceCount  = InitialAnnounceCount;
6751 								InitializeLastAPTime(m, rr);
6752 								RecordProbeFailure(m, rr);	// Repeated late conflicts also cause us to back off to the slower probing rate
6753 								}
6754 							// If we're probing for this record, we just failed
6755 							else if (rr->resrec.RecordType == kDNSRecordTypeUnique)
6756 								{
6757 								LogMsg("mDNSCoreReceiveResponse: ProbeCount %d; will deregister %s", rr->ProbeCount, ARDisplayString(m, rr));
6758 								mDNS_Deregister_internal(m, rr, mDNS_Dereg_conflict);
6759 								}
6760 							// We assumed this record must be unique, but we were wrong. (e.g. There are two mDNSResponders on the
6761 							// same machine giving different answers for the reverse mapping record, or there are two machines on the
6762 							// network using the same IP address.) This is simply a misconfiguration, and there's nothing we can do
6763 							// to fix it -- e.g. it's not our job to be trying to change the machine's IP address. We just discard our
6764 							// record to avoid continued conflicts (as we do for a conflict on our Unique records) and get on with life.
6765 							else if (rr->resrec.RecordType == kDNSRecordTypeKnownUnique)
6766 								{
6767 								LogMsg("mDNSCoreReceiveResponse: Unexpected conflict discarding %s", ARDisplayString(m, rr));
6768 								mDNS_Deregister_internal(m, rr, mDNS_Dereg_conflict);
6769 								}
6770 							else
6771 								LogMsg("mDNSCoreReceiveResponse: Unexpected record type %X %s", rr->resrec.RecordType, ARDisplayString(m, rr));
6772 							}
6773 						}
6774 					// Else, matching signature, different type or rdata, but not a considered a conflict.
6775 					// If the packet record has the cache-flush bit set, then we check to see if we
6776 					// have any record(s) of the same type that we should re-assert to rescue them
6777 					// (see note about "multi-homing and bridged networks" at the end of this function).
6778 					else if (m->rec.r.resrec.rrtype == rr->resrec.rrtype)
6779 						if ((m->rec.r.resrec.RecordType & kDNSRecordTypePacketUniqueMask) && m->timenow - rr->LastMCTime > mDNSPlatformOneSecond/2)
6780 							{ rr->ImmedAnswer = mDNSInterfaceMark; m->NextScheduledResponse = m->timenow; }
6781 					}
6782 				}
6783 			}
6784 
6785 		if (!AcceptableResponse)
6786 			{
6787 			const CacheRecord *cr;
6788 			for (cr = CacheFlushRecords; cr != (CacheRecord*)1; cr = cr->NextInCFList)
6789 				{
6790 				domainname *target = GetRRDomainNameTarget(&cr->resrec);
6791 				// When we issue a query for A record, the response might contain both a CNAME and A records. Only the CNAME would
6792 				// match the question and we already created a cache entry in the previous pass of this loop. Now when we process
6793 				// the A record, it does not match the question because the record name here is the CNAME. Hence we try to
6794 				// match with the previous records to make it an AcceptableResponse. We have to be careful about setting the
6795 				// DNSServer value that we got in the previous pass. This can happen for other record types like SRV also.
6796 
6797 				if (target && cr->resrec.rdatahash == m->rec.r.resrec.namehash && SameDomainName(target, m->rec.r.resrec.name))
6798 					{
6799 					debugf("mDNSCoreReceiveResponse: Found a matching entry for %##s in the CacheFlushRecords", m->rec.r.resrec.name->c);
6800 					AcceptableResponse = mDNStrue;
6801 					m->rec.r.resrec.rDNSServer = uDNSServer;
6802 					break;
6803 					}
6804 				}
6805 			}
6806 
6807 		// 2. See if we want to add this packet resource record to our cache
6808 		// We only try to cache answers if we have a cache to put them in
6809 		// Also, we ignore any apparent attempts at cache poisoning unicast to us that do not answer any outstanding active query
6810 		if (!AcceptableResponse) LogInfo("mDNSCoreReceiveResponse ignoring %s", CRDisplayString(m, &m->rec.r));
6811 		if (m->rrcache_size && AcceptableResponse)
6812 			{
6813 			const mDNSu32 slot = HashSlot(m->rec.r.resrec.name);
6814 			CacheGroup *cg = CacheGroupForRecord(m, slot, &m->rec.r.resrec);
6815 			CacheRecord *rr;
6816 
6817 			// 2a. Check if this packet resource record is already in our cache
6818 			for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next)
6819 				{
6820 				mDNSBool match = !InterfaceID ? m->rec.r.resrec.rDNSServer == rr->resrec.rDNSServer : rr->resrec.InterfaceID == InterfaceID;
6821 				// If we found this exact resource record, refresh its TTL
6822 				if (match && IdenticalSameNameRecord(&m->rec.r.resrec, &rr->resrec))
6823 					{
6824 					if (m->rec.r.resrec.rdlength > InlineCacheRDSize)
6825 						verbosedebugf("Found record size %5d interface %p already in cache: %s",
6826 							m->rec.r.resrec.rdlength, InterfaceID, CRDisplayString(m, &m->rec.r));
6827 
6828 					if (m->rec.r.resrec.RecordType & kDNSRecordTypePacketUniqueMask)
6829 						{
6830 						// If this packet record has the kDNSClass_UniqueRRSet flag set, then add it to our cache flushing list
6831 						if (rr->NextInCFList == mDNSNULL && cfp != &rr->NextInCFList && LLQType != uDNS_LLQ_Events)
6832 							{ *cfp = rr; cfp = &rr->NextInCFList; *cfp = (CacheRecord*)1; }
6833 
6834 						// If this packet record is marked unique, and our previous cached copy was not, then fix it
6835 						if (!(rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask))
6836 							{
6837 							DNSQuestion *q;
6838 							for (q = m->Questions; q; q=q->next) if (ResourceRecordAnswersQuestion(&rr->resrec, q)) q->UniqueAnswers++;
6839 							rr->resrec.RecordType = m->rec.r.resrec.RecordType;
6840 							}
6841 						}
6842 
6843 					if (!SameRDataBody(&m->rec.r.resrec, &rr->resrec.rdata->u, SameDomainNameCS))
6844 						{
6845 						// If the rdata of the packet record differs in name capitalization from the record in our cache
6846 						// then mDNSPlatformMemSame will detect this. In this case, throw the old record away, so that clients get
6847 						// a 'remove' event for the record with the old capitalization, and then an 'add' event for the new one.
6848 						// <rdar://problem/4015377> mDNS -F returns the same domain multiple times with different casing
6849 						rr->resrec.rroriginalttl = 0;
6850 						rr->TimeRcvd = m->timenow;
6851 						rr->UnansweredQueries = MaxUnansweredQueries;
6852 						SetNextCacheCheckTimeForRecord(m, rr);
6853 						LogInfo("Discarding due to domainname case change old: %s", CRDisplayString(m,rr));
6854 						LogInfo("Discarding due to domainname case change new: %s", CRDisplayString(m,&m->rec.r));
6855 						LogInfo("Discarding due to domainname case change in %d slot %3d in %d %d",
6856 							NextCacheCheckEvent(rr) - m->timenow, slot, m->rrcache_nextcheck[slot] - m->timenow, m->NextCacheCheck - m->timenow);
6857 						// DO NOT break out here -- we want to continue as if we never found it
6858 						}
6859 					else if (m->rec.r.resrec.rroriginalttl > 0)
6860 						{
6861 						DNSQuestion *q;
6862 						//if (rr->resrec.rroriginalttl == 0) LogMsg("uDNS rescuing %s", CRDisplayString(m, rr));
6863 						RefreshCacheRecord(m, rr, m->rec.r.resrec.rroriginalttl);
6864 
6865 						// We have to reset the question interval to MaxQuestionInterval so that we don't keep
6866 						// polling the network once we get a valid response back. For the first time when a new
6867 						// cache entry is created, AnswerCurrentQuestionWithResourceRecord does that.
6868 						// Subsequently, if we reissue questions from within the mDNSResponder e.g., DNS server
6869 						// configuration changed, without flushing the cache, we reset the question interval here.
6870 						// Currently, we do this for for both multicast and unicast questions as long as the record
6871 						// type is unique. For unicast, resource record is always unique and for multicast it is
6872 						// true for records like A etc. but not for PTR.
6873 						if (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask)
6874 							{
6875 							for (q = m->Questions; q; q=q->next)
6876 								{
6877 								if (!q->DuplicateOf && !q->LongLived &&
6878 									ActiveQuestion(q) && ResourceRecordAnswersQuestion(&rr->resrec, q))
6879 									{
6880 									q->LastQTime        = m->timenow;
6881 									q->LastQTxTime      = m->timenow;
6882 									q->RecentAnswerPkts = 0;
6883 									q->ThisQInterval    = MaxQuestionInterval;
6884 									q->RequestUnicast   = mDNSfalse;
6885 									q->unansweredQueries = 0;
6886 									debugf("mDNSCoreReceiveResponse: Set MaxQuestionInterval for %p %##s (%s)", q, q->qname.c, DNSTypeName(q->qtype));
6887 									break;		// Why break here? Aren't there other questions we might want to look at?-- SC July 2010
6888 									}
6889 								}
6890 							}
6891 						break;
6892 						}
6893 					else
6894 						{
6895 						// If the packet TTL is zero, that means we're deleting this record.
6896 						// To give other hosts on the network a chance to protest, we push the deletion
6897 						// out one second into the future. Also, we set UnansweredQueries to MaxUnansweredQueries.
6898 						// Otherwise, we'll do final queries for this record at 80% and 90% of its apparent
6899 						// lifetime (800ms and 900ms from now) which is a pointless waste of network bandwidth.
6900 						// If record's current expiry time is more than a second from now, we set it to expire in one second.
6901 						// If the record is already going to expire in less than one second anyway, we leave it alone --
6902 						// we don't want to let the goodbye packet *extend* the record's lifetime in our cache.
6903 						debugf("DE for %s", CRDisplayString(m, rr));
6904 						if (RRExpireTime(rr) - m->timenow > mDNSPlatformOneSecond)
6905 							{
6906 							rr->resrec.rroriginalttl = 1;
6907 							rr->TimeRcvd = m->timenow;
6908 							rr->UnansweredQueries = MaxUnansweredQueries;
6909 							SetNextCacheCheckTimeForRecord(m, rr);
6910 							}
6911 						break;
6912 						}
6913 					}
6914 				}
6915 
6916 			// If packet resource record not in our cache, add it now
6917 			// (unless it is just a deletion of a record we never had, in which case we don't care)
6918 			if (!rr && m->rec.r.resrec.rroriginalttl > 0)
6919 				{
6920 				const mDNSBool AddToCFList = (m->rec.r.resrec.RecordType & kDNSRecordTypePacketUniqueMask) && (LLQType != uDNS_LLQ_Events);
6921 				const mDNSs32 delay = AddToCFList ? NonZeroTime(m->timenow + mDNSPlatformOneSecond) :
6922 					CheckForSoonToExpireRecords(m, m->rec.r.resrec.name, m->rec.r.resrec.namehash, slot);
6923 				// If unique, assume we may have to delay delivery of this 'add' event.
6924 				// Below, where we walk the CacheFlushRecords list, we either call CacheRecordDeferredAdd()
6925 				// to immediately to generate answer callbacks, or we call ScheduleNextCacheCheckTime()
6926 				// to schedule an mDNS_Execute task at the appropriate time.
6927 				rr = CreateNewCacheEntry(m, slot, cg, delay);
6928 				if (rr)
6929 					{
6930 					if (AddToCFList) { *cfp = rr; cfp = &rr->NextInCFList; *cfp = (CacheRecord*)1; }
6931 					else if (rr->DelayDelivery) ScheduleNextCacheCheckTime(m, slot, rr->DelayDelivery);
6932 					}
6933 				}
6934 			}
6935 		m->rec.r.resrec.RecordType = 0;		// Clear RecordType to show we're not still using it
6936 		}
6937 
6938 exit:
6939 	m->rec.r.resrec.RecordType = 0;		// Clear RecordType to show we're not still using it
6940 
6941 	// If we've just received one or more records with their cache flush bits set,
6942 	// then scan that cache slot to see if there are any old stale records we need to flush
6943 	while (CacheFlushRecords != (CacheRecord*)1)
6944 		{
6945 		CacheRecord *r1 = CacheFlushRecords, *r2;
6946 		const mDNSu32 slot = HashSlot(r1->resrec.name);
6947 		const CacheGroup *cg = CacheGroupForRecord(m, slot, &r1->resrec);
6948 		CacheFlushRecords = CacheFlushRecords->NextInCFList;
6949 		r1->NextInCFList = mDNSNULL;
6950 
6951 		// Look for records in the cache with the same signature as this new one with the cache flush
6952 		// bit set, and either (a) if they're fresh, just make sure the whole RRSet has the same TTL
6953 		// (as required by DNS semantics) or (b) if they're old, mark them for deletion in one second.
6954 		// We make these TTL adjustments *only* for records that still have *more* than one second
6955 		// remaining to live. Otherwise, a record that we tagged for deletion half a second ago
6956 		// (and now has half a second remaining) could inadvertently get its life extended, by either
6957 		// (a) if we got an explicit goodbye packet half a second ago, the record would be considered
6958 		// "fresh" and would be incorrectly resurrected back to the same TTL as the rest of the RRSet,
6959 		// or (b) otherwise, the record would not be fully resurrected, but would be reset to expire
6960 		// in one second, thereby inadvertently delaying its actual expiration, instead of hastening it.
6961 		// If this were to happen repeatedly, the record's expiration could be deferred indefinitely.
6962 		// To avoid this, we need to ensure that the cache flushing operation will only act to
6963 		// *decrease* a record's remaining lifetime, never *increase* it.
6964 		for (r2 = cg ? cg->members : mDNSNULL; r2; r2=r2->next)
6965 			// For Unicast (null InterfaceID) the DNSservers should also match
6966 			if ((r1->resrec.InterfaceID == r2->resrec.InterfaceID) &&
6967 				(r1->resrec.InterfaceID || (r1->resrec.rDNSServer == r2->resrec.rDNSServer)) &&
6968 				r1->resrec.rrtype      == r2->resrec.rrtype &&
6969 				r1->resrec.rrclass     == r2->resrec.rrclass)
6970 				{
6971 				// If record is recent, just ensure the whole RRSet has the same TTL (as required by DNS semantics)
6972 				// else, if record is old, mark it to be flushed
6973 				if (m->timenow - r2->TimeRcvd < mDNSPlatformOneSecond && RRExpireTime(r2) - m->timenow > mDNSPlatformOneSecond)
6974 					{
6975 					// If we find mismatched TTLs in an RRSet, correct them.
6976 					// We only do this for records with a TTL of 2 or higher. It's possible to have a
6977 					// goodbye announcement with the cache flush bit set (or a case-change on record rdata,
6978 					// which we treat as a goodbye followed by an addition) and in that case it would be
6979 					// inappropriate to synchronize all the other records to a TTL of 0 (or 1).
6980 					// We suppress the message for the specific case of correcting from 240 to 60 for type TXT,
6981 					// because certain early Bonjour devices are known to have this specific mismatch, and
6982 					// there's no point filling syslog with messages about something we already know about.
6983 					// We also don't log this for uDNS responses, since a caching name server is obliged
6984 					// to give us an aged TTL to correct for how long it has held the record,
6985 					// so our received TTLs are expected to vary in that case
6986 					if (r2->resrec.rroriginalttl != r1->resrec.rroriginalttl && r1->resrec.rroriginalttl > 1)
6987 						{
6988 						if (!(r2->resrec.rroriginalttl == 240 && r1->resrec.rroriginalttl == 60 && r2->resrec.rrtype == kDNSType_TXT) &&
6989 							mDNSOpaque16IsZero(response->h.id))
6990 							LogInfo("Correcting TTL from %4d to %4d for %s",
6991 								r2->resrec.rroriginalttl, r1->resrec.rroriginalttl, CRDisplayString(m, r2));
6992 						r2->resrec.rroriginalttl = r1->resrec.rroriginalttl;
6993 						}
6994 					r2->TimeRcvd = m->timenow;
6995 					}
6996 				else				// else, if record is old, mark it to be flushed
6997 					{
6998 					verbosedebugf("Cache flush new %p age %d expire in %d %s", r1, m->timenow - r1->TimeRcvd, RRExpireTime(r1) - m->timenow, CRDisplayString(m, r1));
6999 					verbosedebugf("Cache flush old %p age %d expire in %d %s", r2, m->timenow - r2->TimeRcvd, RRExpireTime(r2) - m->timenow, CRDisplayString(m, r2));
7000 					// We set stale records to expire in one second.
7001 					// This gives the owner a chance to rescue it if necessary.
7002 					// This is important in the case of multi-homing and bridged networks:
7003 					//   Suppose host X is on Ethernet. X then connects to an AirPort base station, which happens to be
7004 					//   bridged onto the same Ethernet. When X announces its AirPort IP address with the cache-flush bit
7005 					//   set, the AirPort packet will be bridged onto the Ethernet, and all other hosts on the Ethernet
7006 					//   will promptly delete their cached copies of the (still valid) Ethernet IP address record.
7007 					//   By delaying the deletion by one second, we give X a change to notice that this bridging has
7008 					//   happened, and re-announce its Ethernet IP address to rescue it from deletion from all our caches.
7009 
7010 					// We set UnansweredQueries to MaxUnansweredQueries to avoid expensive and unnecessary
7011 					// final expiration queries for this record.
7012 
7013 					// If a record is deleted twice, first with an explicit DE record, then a second time by virtue of the cache
7014 					// flush bit on the new record replacing it, then we allow the record to be deleted immediately, without the usual
7015 					// one-second grace period. This improves responsiveness for mDNS_Update(), as used for things like iChat status updates.
7016 					// <rdar://problem/5636422> Updating TXT records is too slow
7017 					// We check for "rroriginalttl == 1" because we want to include records tagged by the "packet TTL is zero" check above,
7018 					// which sets rroriginalttl to 1, but not records tagged by the rdata case-change check, which sets rroriginalttl to 0.
7019 					if (r2->TimeRcvd == m->timenow && r2->resrec.rroriginalttl == 1 && r2->UnansweredQueries == MaxUnansweredQueries)
7020 						{
7021 						LogInfo("Cache flush for DE record %s", CRDisplayString(m, r2));
7022 						r2->resrec.rroriginalttl = 0;
7023 						}
7024 					else if (RRExpireTime(r2) - m->timenow > mDNSPlatformOneSecond)
7025 						{
7026 						// We only set a record to expire in one second if it currently has *more* than a second to live
7027 						// If it's already due to expire in a second or less, we just leave it alone
7028 						r2->resrec.rroriginalttl = 1;
7029 						r2->UnansweredQueries = MaxUnansweredQueries;
7030 						r2->TimeRcvd = m->timenow - 1;
7031 						// We use (m->timenow - 1) instead of m->timenow, because we use that to identify records
7032 						// that we marked for deletion via an explicit DE record
7033 						}
7034 					}
7035 				SetNextCacheCheckTimeForRecord(m, r2);
7036 				}
7037 
7038 		if (r1->DelayDelivery)	// If we were planning to delay delivery of this record, see if we still need to
7039 			{
7040 			r1->DelayDelivery = CheckForSoonToExpireRecords(m, r1->resrec.name, r1->resrec.namehash, slot);
7041 			// If no longer delaying, deliver answer now, else schedule delivery for the appropriate time
7042 			if (!r1->DelayDelivery) CacheRecordDeferredAdd(m, r1);
7043 			else ScheduleNextCacheCheckTime(m, slot, r1->DelayDelivery);
7044 			}
7045 		}
7046 
7047 	// See if we need to generate negative cache entries for unanswered unicast questions
7048 	ptr = response->data;
7049 	for (i = 0; i < response->h.numQuestions && ptr && ptr < end; i++)
7050 		{
7051 		DNSQuestion q;
7052 		DNSQuestion *qptr = mDNSNULL;
7053 		ptr = getQuestion(response, ptr, end, InterfaceID, &q);
7054 		if (ptr && (qptr = ExpectingUnicastResponseForQuestion(m, dstport, response->h.id, &q, !dstaddr)))
7055 			{
7056 			CacheRecord *rr, *neg = mDNSNULL;
7057 			mDNSu32 slot = HashSlot(&q.qname);
7058 			CacheGroup *cg = CacheGroupForName(m, slot, q.qnamehash, &q.qname);
7059 			for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next)
7060 				if (SameNameRecordAnswersQuestion(&rr->resrec, qptr))
7061 					{
7062 					// 1. If we got a fresh answer to this query, then don't need to generate a negative entry
7063 					if (RRExpireTime(rr) - m->timenow > 0) break;
7064 					// 2. If we already had a negative entry, keep track of it so we can resurrect it instead of creating a new one
7065 					if (rr->resrec.RecordType == kDNSRecordTypePacketNegative) neg = rr;
7066 					}
7067 			// When we're doing parallel unicast and multicast queries for dot-local names (for supporting Microsoft
7068 			// Active Directory sites) we don't want to waste memory making negative cache entries for all the unicast answers.
7069 			// Otherwise we just fill up our cache with negative entries for just about every single multicast name we ever look up
7070 			// (since the Microsoft Active Directory server is going to assert that pretty much every single multicast name doesn't exist).
7071 			// This is not only a waste of memory, but there's also the problem of those negative entries confusing us later -- e.g. we
7072 			// suppress sending our mDNS query packet because we think we already have a valid (negative) answer to that query in our cache.
7073 			// The one exception is that we *DO* want to make a negative cache entry for "local. SOA", for the (common) case where we're
7074 			// *not* on a Microsoft Active Directory network, and there is no authoritative server for "local". Note that this is not
7075 			// in conflict with the mDNS spec, because that spec says, "Multicast DNS Zones have no SOA record," so it's okay to cache
7076 			// negative answers for "local. SOA" from a uDNS server, because the mDNS spec already says that such records do not exist :-)
7077 			if (!InterfaceID && q.qtype != kDNSType_SOA && IsLocalDomain(&q.qname))
7078 				{
7079 				// If we did not find a positive answer and we can append search domains to this question,
7080 				// generate a negative response (without creating a cache entry) to append search domains.
7081 				if (qptr->AppendSearchDomains && !rr)
7082 					{
7083 					LogInfo("mDNSCoreReceiveResponse: Generate negative response for %##s (%s)", q.qname.c, DNSTypeName(q.qtype));
7084 					m->CurrentQuestion = qptr;
7085 					GenerateNegativeResponse(m);
7086 					m->CurrentQuestion = mDNSNULL;
7087 					}
7088 				else LogInfo("mDNSCoreReceiveResponse: Skipping check to see if we need to generate a negative cache entry for %##s (%s)", q.qname.c, DNSTypeName(q.qtype));
7089 				}
7090 			else
7091 				{
7092 				if (!rr)
7093 					{
7094 					// We start off assuming a negative caching TTL of 60 seconds
7095 					// but then look to see if we can find an SOA authority record to tell us a better value we should be using
7096 					mDNSu32 negttl = 60;
7097 					int repeat = 0;
7098 					const domainname *name = &q.qname;
7099 					mDNSu32           hash = q.qnamehash;
7100 
7101 					// Special case for our special Microsoft Active Directory "local SOA" check.
7102 					// Some cheap home gateways don't include an SOA record in the authority section when
7103 					// they send negative responses, so we don't know how long to cache the negative result.
7104 					// Because we don't want to keep hitting the root name servers with our query to find
7105 					// if we're on a network using Microsoft Active Directory using "local" as a private
7106 					// internal top-level domain, we make sure to cache the negative result for at least one day.
7107 					if (q.qtype == kDNSType_SOA && SameDomainName(&q.qname, &localdomain)) negttl = 60 * 60 * 24;
7108 
7109 					// If we're going to make (or update) a negative entry, then look for the appropriate TTL from the SOA record
7110 					if (response->h.numAuthorities && (ptr = LocateAuthorities(response, end)) != mDNSNULL)
7111 						{
7112 						ptr = GetLargeResourceRecord(m, response, ptr, end, InterfaceID, kDNSRecordTypePacketAuth, &m->rec);
7113 						if (ptr && m->rec.r.resrec.RecordType != kDNSRecordTypePacketNegative && m->rec.r.resrec.rrtype == kDNSType_SOA)
7114 							{
7115 							const rdataSOA *const soa = (const rdataSOA *)m->rec.r.resrec.rdata->u.data;
7116 							mDNSu32 ttl_s = soa->min;
7117 							// We use the lesser of the SOA.MIN field and the SOA record's TTL, *except*
7118 							// for the SOA record for ".", where the record is reported as non-cacheable
7119 							// (TTL zero) for some reason, so in this case we just take the SOA record's TTL as-is
7120 							if (ttl_s > m->rec.r.resrec.rroriginalttl && m->rec.r.resrec.name->c[0])
7121 								ttl_s = m->rec.r.resrec.rroriginalttl;
7122 							if (negttl < ttl_s) negttl = ttl_s;
7123 
7124 							// Special check for SOA queries: If we queried for a.b.c.d.com, and got no answer,
7125 							// with an Authority Section SOA record for d.com, then this is a hint that the authority
7126 							// is d.com, and consequently SOA records b.c.d.com and c.d.com don't exist either.
7127 							// To do this we set the repeat count so the while loop below will make a series of negative cache entries for us
7128 							if (q.qtype == kDNSType_SOA)
7129 								{
7130 								int qcount = CountLabels(&q.qname);
7131 								int scount = CountLabels(m->rec.r.resrec.name);
7132 								if (qcount - 1 > scount)
7133 									if (SameDomainName(SkipLeadingLabels(&q.qname, qcount - scount), m->rec.r.resrec.name))
7134 										repeat = qcount - 1 - scount;
7135 								}
7136 							}
7137 						m->rec.r.resrec.RecordType = 0;		// Clear RecordType to show we're not still using it
7138 						}
7139 
7140 					// If we already had a negative entry in the cache, then we double our existing negative TTL. This is to avoid
7141 					// the case where the record doesn't exist (e.g. particularly for things like our lb._dns-sd._udp.<domain> query),
7142 					// and the server returns no SOA record (or an SOA record with a small MIN TTL) so we assume a TTL
7143 					// of 60 seconds, and we end up polling the server every minute for a record that doesn't exist.
7144 					// With this fix in place, when this happens, we double the effective TTL each time (up to one hour),
7145 					// so that we back off our polling rate and don't keep hitting the server continually.
7146 					if (neg)
7147 						{
7148 						if (negttl < neg->resrec.rroriginalttl * 2)
7149 							negttl = neg->resrec.rroriginalttl * 2;
7150 						if (negttl > 3600)
7151 							negttl = 3600;
7152 						}
7153 
7154 					negttl = GetEffectiveTTL(LLQType, negttl);	// Add 25% grace period if necessary
7155 
7156 					// If we already had a negative cache entry just update it, else make one or more new negative cache entries
7157 					if (neg)
7158 						{
7159 						debugf("Renewing negative TTL from %d to %d %s", neg->resrec.rroriginalttl, negttl, CRDisplayString(m, neg));
7160 						RefreshCacheRecord(m, neg, negttl);
7161 						}
7162 					else while (1)
7163 						{
7164 						debugf("mDNSCoreReceiveResponse making negative cache entry TTL %d for %##s (%s)", negttl, name->c, DNSTypeName(q.qtype));
7165 						MakeNegativeCacheRecord(m, &m->rec.r, name, hash, q.qtype, q.qclass, negttl, mDNSInterface_Any, qptr->qDNSServer);
7166 						CreateNewCacheEntry(m, slot, cg, 0);	// We never need any delivery delay for these generated negative cache records
7167 						m->rec.r.resrec.RecordType = 0;		// Clear RecordType to show we're not still using it
7168 						if (!repeat) break;
7169 						repeat--;
7170 						name = (const domainname *)(name->c + 1 + name->c[0]);
7171 						hash = DomainNameHashValue(name);
7172 						slot = HashSlot(name);
7173 						cg   = CacheGroupForName(m, slot, hash, name);
7174 						}
7175 					}
7176 				}
7177 			}
7178 		}
7179 	}
7180 
7181 // ScheduleWakeup causes all proxy records with WakeUp.HMAC matching mDNSEthAddr 'e' to be deregistered, causing
7182 // multiple wakeup magic packets to be sent if appropriate, and all records to be ultimately freed after a few seconds.
7183 // ScheduleWakeup is called on mDNS record conflicts, ARP conflicts, NDP conflicts, or reception of trigger traffic
7184 // that warrants waking the sleeping host.
7185 // ScheduleWakeup must be called with the lock held (ScheduleWakeupForList uses mDNS_Deregister_internal)
7186 
ScheduleWakeupForList(mDNS * const m,mDNSInterfaceID InterfaceID,mDNSEthAddr * e,AuthRecord * const thelist)7187 mDNSlocal void ScheduleWakeupForList(mDNS *const m, mDNSInterfaceID InterfaceID, mDNSEthAddr *e, AuthRecord *const thelist)
7188 	{
7189 	// We don't need to use the m->CurrentRecord mechanism here because the target HMAC is nonzero,
7190 	// so all we're doing is marking the record to generate a few wakeup packets
7191 	AuthRecord *rr;
7192 	if (!e->l[0]) { LogMsg("ScheduleWakeupForList ERROR: Target HMAC is zero"); return; }
7193 	for (rr = thelist; rr; rr = rr->next)
7194 		if (rr->resrec.InterfaceID == InterfaceID && rr->resrec.RecordType != kDNSRecordTypeDeregistering && mDNSSameEthAddress(&rr->WakeUp.HMAC, e))
7195 			{
7196 			LogInfo("ScheduleWakeupForList: Scheduling wakeup packets for %s", ARDisplayString(m, rr));
7197 			mDNS_Deregister_internal(m, rr, mDNS_Dereg_normal);
7198 			}
7199 	}
7200 
ScheduleWakeup(mDNS * const m,mDNSInterfaceID InterfaceID,mDNSEthAddr * e)7201 mDNSlocal void ScheduleWakeup(mDNS *const m, mDNSInterfaceID InterfaceID, mDNSEthAddr *e)
7202 	{
7203 	if (!e->l[0]) { LogMsg("ScheduleWakeup ERROR: Target HMAC is zero"); return; }
7204 	ScheduleWakeupForList(m, InterfaceID, e, m->DuplicateRecords);
7205 	ScheduleWakeupForList(m, InterfaceID, e, m->ResourceRecords);
7206 	}
7207 
SPSRecordCallback(mDNS * const m,AuthRecord * const ar,mStatus result)7208 mDNSlocal void SPSRecordCallback(mDNS *const m, AuthRecord *const ar, mStatus result)
7209 	{
7210 	if (result && result != mStatus_MemFree)
7211 		LogInfo("SPS Callback %d %s", result, ARDisplayString(m, ar));
7212 
7213 	if (result == mStatus_NameConflict)
7214 		{
7215 		mDNS_Lock(m);
7216 		LogMsg("%-7s Conflicting mDNS -- waking %.6a %s", InterfaceNameForID(m, ar->resrec.InterfaceID), &ar->WakeUp.HMAC, ARDisplayString(m, ar));
7217 		if (ar->WakeUp.HMAC.l[0])
7218 			{
7219 			SendWakeup(m, ar->resrec.InterfaceID, &ar->WakeUp.IMAC, &ar->WakeUp.password);	// Send one wakeup magic packet
7220 			ScheduleWakeup(m, ar->resrec.InterfaceID, &ar->WakeUp.HMAC);					// Schedule all other records with the same owner to be woken
7221 			}
7222 		mDNS_Unlock(m);
7223 		}
7224 
7225 	if (result == mStatus_NameConflict || result == mStatus_MemFree)
7226 		{
7227 		m->ProxyRecords--;
7228 		mDNSPlatformMemFree(ar);
7229 		mDNS_UpdateAllowSleep(m);
7230 		}
7231 	}
7232 
mDNSCoreReceiveUpdate(mDNS * const m,const DNSMessage * const msg,const mDNSu8 * end,const mDNSAddr * srcaddr,const mDNSIPPort srcport,const mDNSAddr * dstaddr,mDNSIPPort dstport,const mDNSInterfaceID InterfaceID)7233 mDNSlocal void mDNSCoreReceiveUpdate(mDNS *const m,
7234 	const DNSMessage *const msg, const mDNSu8 *end,
7235 	const mDNSAddr *srcaddr, const mDNSIPPort srcport, const mDNSAddr *dstaddr, mDNSIPPort dstport,
7236 	const mDNSInterfaceID InterfaceID)
7237 	{
7238 	int i;
7239 	AuthRecord opt;
7240 	mDNSu8 *p = m->omsg.data;
7241 	OwnerOptData owner = zeroOwner;		// Need to zero this, so we'll know if this Update packet was missing its Owner option
7242 	mDNSu32 updatelease = 0;
7243 	const mDNSu8 *ptr;
7244 
7245 	LogSPS("Received Update from %#-15a:%-5d to %#-15a:%-5d on 0x%p with "
7246 		"%2d Question%s %2d Answer%s %2d Authorit%s %2d Additional%s %d bytes",
7247 		srcaddr, mDNSVal16(srcport), dstaddr, mDNSVal16(dstport), InterfaceID,
7248 		msg->h.numQuestions,   msg->h.numQuestions   == 1 ? ", "   : "s,",
7249 		msg->h.numAnswers,     msg->h.numAnswers     == 1 ? ", "   : "s,",
7250 		msg->h.numAuthorities, msg->h.numAuthorities == 1 ? "y,  " : "ies,",
7251 		msg->h.numAdditionals, msg->h.numAdditionals == 1 ? " "    : "s", end - msg->data);
7252 
7253 	if (!InterfaceID || !m->SPSSocket || !mDNSSameIPPort(dstport, m->SPSSocket->port)) return;
7254 
7255 	if (mDNS_PacketLoggingEnabled)
7256 		DumpPacket(m, mStatus_NoError, mDNSfalse, "UDP", srcaddr, srcport, dstaddr, dstport, msg, end);
7257 
7258 	ptr = LocateOptRR(msg, end, DNSOpt_LeaseData_Space + DNSOpt_OwnerData_ID_Space);
7259 	if (ptr)
7260 		{
7261 		ptr = GetLargeResourceRecord(m, msg, ptr, end, 0, kDNSRecordTypePacketAdd, &m->rec);
7262 		if (ptr && m->rec.r.resrec.RecordType != kDNSRecordTypePacketNegative && m->rec.r.resrec.rrtype == kDNSType_OPT)
7263 			{
7264 			const rdataOPT *o;
7265 			const rdataOPT *const e = (const rdataOPT *)&m->rec.r.resrec.rdata->u.data[m->rec.r.resrec.rdlength];
7266 			for (o = &m->rec.r.resrec.rdata->u.opt[0]; o < e; o++)
7267 				{
7268 				if      (o->opt == kDNSOpt_Lease)                         updatelease = o->u.updatelease;
7269 				else if (o->opt == kDNSOpt_Owner && o->u.owner.vers == 0) owner       = o->u.owner;
7270 				}
7271 			}
7272 		m->rec.r.resrec.RecordType = 0;		// Clear RecordType to show we're not still using it
7273 		}
7274 
7275 	InitializeDNSMessage(&m->omsg.h, msg->h.id, UpdateRespFlags);
7276 
7277 	if (!updatelease || !owner.HMAC.l[0])
7278 		{
7279 		static int msgs = 0;
7280 		if (msgs < 100)
7281 			{
7282 			msgs++;
7283 			LogMsg("Refusing sleep proxy registration from %#a:%d:%s%s", srcaddr, mDNSVal16(srcport),
7284 				!updatelease ? " No lease" : "", !owner.HMAC.l[0] ? " No owner" : "");
7285 			}
7286 		m->omsg.h.flags.b[1] |= kDNSFlag1_RC_FormErr;
7287 		}
7288 	else if (m->ProxyRecords + msg->h.mDNS_numUpdates > MAX_PROXY_RECORDS)
7289 		{
7290 		static int msgs = 0;
7291 		if (msgs < 100)
7292 			{
7293 			msgs++;
7294 			LogMsg("Refusing sleep proxy registration from %#a:%d: Too many records %d + %d = %d > %d", srcaddr, mDNSVal16(srcport),
7295 				m->ProxyRecords, msg->h.mDNS_numUpdates, m->ProxyRecords + msg->h.mDNS_numUpdates, MAX_PROXY_RECORDS);
7296 			}
7297 		m->omsg.h.flags.b[1] |= kDNSFlag1_RC_Refused;
7298 		}
7299 	else
7300 		{
7301 		LogSPS("Received Update for H-MAC %.6a I-MAC %.6a Password %.6a seq %d", &owner.HMAC, &owner.IMAC, &owner.password, owner.seq);
7302 
7303 		if (updatelease > 24 * 60 * 60)
7304 			updatelease = 24 * 60 * 60;
7305 
7306 		if (updatelease > 0x40000000UL / mDNSPlatformOneSecond)
7307 			updatelease = 0x40000000UL / mDNSPlatformOneSecond;
7308 
7309 		ptr = LocateAuthorities(msg, end);
7310 		for (i = 0; i < msg->h.mDNS_numUpdates && ptr && ptr < end; i++)
7311 			{
7312 			ptr = GetLargeResourceRecord(m, msg, ptr, end, InterfaceID, kDNSRecordTypePacketAuth, &m->rec);
7313 			if (ptr && m->rec.r.resrec.RecordType != kDNSRecordTypePacketNegative)
7314 				{
7315 				mDNSu16 RDLengthMem = GetRDLengthMem(&m->rec.r.resrec);
7316 				AuthRecord *ar = mDNSPlatformMemAllocate(sizeof(AuthRecord) - sizeof(RDataBody) + RDLengthMem);
7317 				if (!ar) { m->omsg.h.flags.b[1] |= kDNSFlag1_RC_Refused; break; }
7318 				else
7319 					{
7320 					mDNSu8 RecordType = m->rec.r.resrec.RecordType & kDNSRecordTypePacketUniqueMask ? kDNSRecordTypeUnique : kDNSRecordTypeShared;
7321 					m->rec.r.resrec.rrclass &= ~kDNSClass_UniqueRRSet;
7322 					ClearIdenticalProxyRecords(m, &owner, m->DuplicateRecords);	// Make sure we don't have any old stale duplicates of this record
7323 					ClearIdenticalProxyRecords(m, &owner, m->ResourceRecords);
7324 					mDNS_SetupResourceRecord(ar, mDNSNULL, InterfaceID, m->rec.r.resrec.rrtype, m->rec.r.resrec.rroriginalttl, RecordType, AuthRecordAny, SPSRecordCallback, ar);
7325 					AssignDomainName(&ar->namestorage, m->rec.r.resrec.name);
7326 					ar->resrec.rdlength = GetRDLength(&m->rec.r.resrec, mDNSfalse);
7327 					ar->resrec.rdata->MaxRDLength = RDLengthMem;
7328 					mDNSPlatformMemCopy(ar->resrec.rdata->u.data, m->rec.r.resrec.rdata->u.data, RDLengthMem);
7329 					ar->ForceMCast = mDNStrue;
7330 					ar->WakeUp     = owner;
7331 					if (m->rec.r.resrec.rrtype == kDNSType_PTR)
7332 						{
7333 						mDNSs32 t = ReverseMapDomainType(m->rec.r.resrec.name);
7334 						if      (t == mDNSAddrType_IPv4) GetIPv4FromName(&ar->AddressProxy, m->rec.r.resrec.name);
7335 						else if (t == mDNSAddrType_IPv6) GetIPv6FromName(&ar->AddressProxy, m->rec.r.resrec.name);
7336 						debugf("mDNSCoreReceiveUpdate: PTR %d %d %#a %s", t, ar->AddressProxy.type, &ar->AddressProxy, ARDisplayString(m, ar));
7337 						if (ar->AddressProxy.type) SetSPSProxyListChanged(InterfaceID);
7338 						}
7339 					ar->TimeRcvd   = m->timenow;
7340 					ar->TimeExpire = m->timenow + updatelease * mDNSPlatformOneSecond;
7341 					if (m->NextScheduledSPS - ar->TimeExpire > 0)
7342 						m->NextScheduledSPS = ar->TimeExpire;
7343 					mDNS_Register_internal(m, ar);
7344 					// Unsolicited Neighbor Advertisements (RFC 2461 Section 7.2.6) give us fast address cache updating,
7345 					// but some older IPv6 clients get confused by them, so for now we don't send them. Without Unsolicited
7346 					// Neighbor Advertisements we have to rely on Neighbor Unreachability Detection instead, which is slower.
7347 					// Given this, we'll do our best to wake for existing IPv6 connections, but we don't want to encourage
7348 					// new ones for sleeping clients, so we'll we send deletions for our SPS clients' AAAA records.
7349 					if (m->KnownBugs & mDNS_KnownBug_LimitedIPv6)
7350 						if (ar->resrec.rrtype == kDNSType_AAAA) ar->resrec.rroriginalttl = 0;
7351 					m->ProxyRecords++;
7352 					mDNS_UpdateAllowSleep(m);
7353 					LogSPS("SPS Registered %4d %X %s", m->ProxyRecords, RecordType, ARDisplayString(m,ar));
7354 					}
7355 				}
7356 			m->rec.r.resrec.RecordType = 0;		// Clear RecordType to show we're not still using it
7357 			}
7358 
7359 		if (m->omsg.h.flags.b[1] & kDNSFlag1_RC_Mask)
7360 			{
7361 			LogMsg("Refusing sleep proxy registration from %#a:%d: Out of memory", srcaddr, mDNSVal16(srcport));
7362 			ClearProxyRecords(m, &owner, m->DuplicateRecords);
7363 			ClearProxyRecords(m, &owner, m->ResourceRecords);
7364 			}
7365 		else
7366 			{
7367 			mDNS_SetupResourceRecord(&opt, mDNSNULL, mDNSInterface_Any, kDNSType_OPT, kStandardTTL, kDNSRecordTypeKnownUnique, AuthRecordAny, mDNSNULL, mDNSNULL);
7368 			opt.resrec.rrclass    = NormalMaxDNSMessageData;
7369 			opt.resrec.rdlength   = sizeof(rdataOPT);	// One option in this OPT record
7370 			opt.resrec.rdestimate = sizeof(rdataOPT);
7371 			opt.resrec.rdata->u.opt[0].opt           = kDNSOpt_Lease;
7372 			opt.resrec.rdata->u.opt[0].u.updatelease = updatelease;
7373 			p = PutResourceRecordTTLWithLimit(&m->omsg, p, &m->omsg.h.numAdditionals, &opt.resrec, opt.resrec.rroriginalttl, m->omsg.data + AbsoluteMaxDNSMessageData);
7374 			}
7375 		}
7376 
7377 	if (p) mDNSSendDNSMessage(m, &m->omsg, p, InterfaceID, m->SPSSocket, srcaddr, srcport, mDNSNULL, mDNSNULL);
7378 	}
7379 
mDNSCoreReceiveUpdateR(mDNS * const m,const DNSMessage * const msg,const mDNSu8 * end,const mDNSInterfaceID InterfaceID)7380 mDNSlocal void mDNSCoreReceiveUpdateR(mDNS *const m, const DNSMessage *const msg, const mDNSu8 *end, const mDNSInterfaceID InterfaceID)
7381 	{
7382 	if (InterfaceID)
7383 		{
7384 		mDNSu32 updatelease = 60 * 60;		// If SPS fails to indicate lease time, assume one hour
7385 		const mDNSu8 *ptr = LocateOptRR(msg, end, DNSOpt_LeaseData_Space);
7386 		if (ptr)
7387 			{
7388 			ptr = GetLargeResourceRecord(m, msg, ptr, end, 0, kDNSRecordTypePacketAdd, &m->rec);
7389 			if (ptr && m->rec.r.resrec.RecordType != kDNSRecordTypePacketNegative && m->rec.r.resrec.rrtype == kDNSType_OPT)
7390 				{
7391 				const rdataOPT *o;
7392 				const rdataOPT *const e = (const rdataOPT *)&m->rec.r.resrec.rdata->u.data[m->rec.r.resrec.rdlength];
7393 				for (o = &m->rec.r.resrec.rdata->u.opt[0]; o < e; o++)
7394 					if (o->opt == kDNSOpt_Lease)
7395 						{
7396 						updatelease = o->u.updatelease;
7397 						LogSPS("Sleep Proxy granted lease time %4d seconds", updatelease);
7398 						}
7399 				}
7400 			m->rec.r.resrec.RecordType = 0;		// Clear RecordType to show we're not still using it
7401 			}
7402 
7403 		if (m->CurrentRecord)
7404 			LogMsg("mDNSCoreReceiveUpdateR ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord));
7405 		m->CurrentRecord = m->ResourceRecords;
7406 		while (m->CurrentRecord)
7407 			{
7408 			AuthRecord *const rr = m->CurrentRecord;
7409 			if (rr->resrec.InterfaceID == InterfaceID || (!rr->resrec.InterfaceID && (rr->ForceMCast || IsLocalDomain(rr->resrec.name))))
7410 				if (mDNSSameOpaque16(rr->updateid, msg->h.id))
7411 					{
7412 					rr->updateid = zeroID;
7413 					rr->expire   = NonZeroTime(m->timenow + updatelease * mDNSPlatformOneSecond);
7414 					LogSPS("Sleep Proxy %s record %5d %s", rr->WakeUp.HMAC.l[0] ? "transferred" : "registered", updatelease, ARDisplayString(m,rr));
7415 					if (rr->WakeUp.HMAC.l[0])
7416 						{
7417 						rr->WakeUp.HMAC = zeroEthAddr;	// Clear HMAC so that mDNS_Deregister_internal doesn't waste packets trying to wake this host
7418 						rr->RequireGoodbye = mDNSfalse;	// and we don't want to send goodbye for it
7419 						mDNS_Deregister_internal(m, rr, mDNS_Dereg_normal);
7420 						}
7421 					}
7422 			// Mustn't advance m->CurrentRecord until *after* mDNS_Deregister_internal, because
7423 			// new records could have been added to the end of the list as a result of that call.
7424 			if (m->CurrentRecord == rr) // If m->CurrentRecord was not advanced for us, do it now
7425 				m->CurrentRecord = rr->next;
7426 			}
7427 		}
7428 	// If we were waiting to go to sleep, then this SPS registration or wide-area record deletion
7429 	// may have been the thing we were waiting for, so schedule another check to see if we can sleep now.
7430 	if (m->SleepLimit) m->NextScheduledSPRetry = m->timenow;
7431 	}
7432 
MakeNegativeCacheRecord(mDNS * const m,CacheRecord * const cr,const domainname * const name,const mDNSu32 namehash,const mDNSu16 rrtype,const mDNSu16 rrclass,mDNSu32 ttl_seconds,mDNSInterfaceID InterfaceID,DNSServer * dnsserver)7433 mDNSexport void MakeNegativeCacheRecord(mDNS *const m, CacheRecord *const cr,
7434 	const domainname *const name, const mDNSu32 namehash, const mDNSu16 rrtype, const mDNSu16 rrclass, mDNSu32 ttl_seconds, mDNSInterfaceID InterfaceID, DNSServer *dnsserver)
7435 	{
7436 	if (cr == &m->rec.r && m->rec.r.resrec.RecordType)
7437 		{
7438 		LogMsg("MakeNegativeCacheRecord: m->rec appears to be already in use for %s", CRDisplayString(m, &m->rec.r));
7439 #if ForceAlerts
7440 		*(long*)0 = 0;
7441 #endif
7442 		}
7443 
7444 	// Create empty resource record
7445 	cr->resrec.RecordType    = kDNSRecordTypePacketNegative;
7446 	cr->resrec.InterfaceID   = InterfaceID;
7447 	cr->resrec.rDNSServer	 = dnsserver;
7448 	cr->resrec.name          = name;	// Will be updated to point to cg->name when we call CreateNewCacheEntry
7449 	cr->resrec.rrtype        = rrtype;
7450 	cr->resrec.rrclass       = rrclass;
7451 	cr->resrec.rroriginalttl = ttl_seconds;
7452 	cr->resrec.rdlength      = 0;
7453 	cr->resrec.rdestimate    = 0;
7454 	cr->resrec.namehash      = namehash;
7455 	cr->resrec.rdatahash     = 0;
7456 	cr->resrec.rdata = (RData*)&cr->smallrdatastorage;
7457 	cr->resrec.rdata->MaxRDLength = 0;
7458 
7459 	cr->NextInKAList       = mDNSNULL;
7460 	cr->TimeRcvd           = m->timenow;
7461 	cr->DelayDelivery      = 0;
7462 	cr->NextRequiredQuery  = m->timenow;
7463 	cr->LastUsed           = m->timenow;
7464 	cr->CRActiveQuestion   = mDNSNULL;
7465 	cr->UnansweredQueries  = 0;
7466 	cr->LastUnansweredTime = 0;
7467 #if ENABLE_MULTI_PACKET_QUERY_SNOOPING
7468 	cr->MPUnansweredQ      = 0;
7469 	cr->MPLastUnansweredQT = 0;
7470 	cr->MPUnansweredKA     = 0;
7471 	cr->MPExpectingKA      = mDNSfalse;
7472 #endif
7473 	cr->NextInCFList       = mDNSNULL;
7474 	}
7475 
mDNSCoreReceive(mDNS * const m,void * const pkt,const mDNSu8 * const end,const mDNSAddr * const srcaddr,const mDNSIPPort srcport,const mDNSAddr * dstaddr,const mDNSIPPort dstport,const mDNSInterfaceID InterfaceID)7476 mDNSexport void mDNSCoreReceive(mDNS *const m, void *const pkt, const mDNSu8 *const end,
7477 	const mDNSAddr *const srcaddr, const mDNSIPPort srcport, const mDNSAddr *dstaddr, const mDNSIPPort dstport,
7478 	const mDNSInterfaceID InterfaceID)
7479 	{
7480 	mDNSInterfaceID ifid = InterfaceID;
7481 	DNSMessage  *msg  = (DNSMessage *)pkt;
7482 	const mDNSu8 StdQ = kDNSFlag0_QR_Query    | kDNSFlag0_OP_StdQuery;
7483 	const mDNSu8 StdR = kDNSFlag0_QR_Response | kDNSFlag0_OP_StdQuery;
7484 	const mDNSu8 UpdQ = kDNSFlag0_QR_Query    | kDNSFlag0_OP_Update;
7485 	const mDNSu8 UpdR = kDNSFlag0_QR_Response | kDNSFlag0_OP_Update;
7486 	mDNSu8 QR_OP;
7487 	mDNSu8 *ptr = mDNSNULL;
7488 	mDNSBool TLS = (dstaddr == (mDNSAddr *)1);	// For debug logs: dstaddr = 0 means TCP; dstaddr = 1 means TLS
7489 	if (TLS) dstaddr = mDNSNULL;
7490 
7491 #ifndef UNICAST_DISABLED
7492 	if (mDNSSameAddress(srcaddr, &m->Router))
7493 		{
7494 #ifdef _LEGACY_NAT_TRAVERSAL_
7495 		if (mDNSSameIPPort(srcport, SSDPPort) || (m->SSDPSocket && mDNSSameIPPort(dstport, m->SSDPSocket->port)))
7496 			{
7497 			mDNS_Lock(m);
7498 			LNT_ConfigureRouterInfo(m, InterfaceID, pkt, (mDNSu16)(end - (mDNSu8 *)pkt));
7499 			mDNS_Unlock(m);
7500 			return;
7501 			}
7502 #endif
7503 		if (mDNSSameIPPort(srcport, NATPMPPort))
7504 			{
7505 			mDNS_Lock(m);
7506 			uDNS_ReceiveNATPMPPacket(m, InterfaceID, pkt, (mDNSu16)(end - (mDNSu8 *)pkt));
7507 			mDNS_Unlock(m);
7508 			return;
7509 			}
7510 		}
7511 #ifdef _LEGACY_NAT_TRAVERSAL_
7512 	else if (m->SSDPSocket && mDNSSameIPPort(dstport, m->SSDPSocket->port)) { debugf("Ignoring SSDP response from %#a:%d", srcaddr, mDNSVal16(srcport)); return; }
7513 #endif
7514 
7515 #endif
7516 	if ((unsigned)(end - (mDNSu8 *)pkt) < sizeof(DNSMessageHeader))
7517 		{
7518 		LogMsg("DNS Message from %#a:%d to %#a:%d length %d too short", srcaddr, mDNSVal16(srcport), dstaddr, mDNSVal16(dstport), end - (mDNSu8 *)pkt);
7519 		return;
7520 		}
7521 	QR_OP = (mDNSu8)(msg->h.flags.b[0] & kDNSFlag0_QROP_Mask);
7522 	// Read the integer parts which are in IETF byte-order (MSB first, LSB second)
7523 	ptr = (mDNSu8 *)&msg->h.numQuestions;
7524 	msg->h.numQuestions   = (mDNSu16)((mDNSu16)ptr[0] << 8 | ptr[1]);
7525 	msg->h.numAnswers     = (mDNSu16)((mDNSu16)ptr[2] << 8 | ptr[3]);
7526 	msg->h.numAuthorities = (mDNSu16)((mDNSu16)ptr[4] << 8 | ptr[5]);
7527 	msg->h.numAdditionals = (mDNSu16)((mDNSu16)ptr[6] << 8 | ptr[7]);
7528 
7529 	if (!m) { LogMsg("mDNSCoreReceive ERROR m is NULL"); return; }
7530 
7531 	// We use zero addresses and all-ones addresses at various places in the code to indicate special values like "no address"
7532 	// If we accept and try to process a packet with zero or all-ones source address, that could really mess things up
7533 	if (srcaddr && !mDNSAddressIsValid(srcaddr)) { debugf("mDNSCoreReceive ignoring packet from %#a", srcaddr); return; }
7534 
7535 	mDNS_Lock(m);
7536 	m->PktNum++;
7537 #ifndef UNICAST_DISABLED
7538 	if (!dstaddr || (!mDNSAddressIsAllDNSLinkGroup(dstaddr) && (QR_OP == StdR || QR_OP == UpdR)))
7539 		if (!mDNSOpaque16IsZero(msg->h.id)) // uDNS_ReceiveMsg only needs to get real uDNS responses, not "QU" mDNS responses
7540 			{
7541 			ifid = mDNSInterface_Any;
7542 			if (mDNS_PacketLoggingEnabled)
7543 				DumpPacket(m, mStatus_NoError, mDNSfalse, TLS ? "TLS" : !dstaddr ? "TCP" : "UDP", srcaddr, srcport, dstaddr, dstport, msg, end);
7544 			uDNS_ReceiveMsg(m, msg, end, srcaddr, srcport);
7545 			// Note: mDNSCore also needs to get access to received unicast responses
7546 			}
7547 #endif
7548 	if      (QR_OP == StdQ) mDNSCoreReceiveQuery   (m, msg, end, srcaddr, srcport, dstaddr, dstport, ifid);
7549 	else if (QR_OP == StdR) mDNSCoreReceiveResponse(m, msg, end, srcaddr, srcport, dstaddr, dstport, ifid);
7550 	else if (QR_OP == UpdQ) mDNSCoreReceiveUpdate  (m, msg, end, srcaddr, srcport, dstaddr, dstport, InterfaceID);
7551 	else if (QR_OP == UpdR) mDNSCoreReceiveUpdateR (m, msg, end,                                     InterfaceID);
7552 	else
7553 		{
7554 		LogMsg("Unknown DNS packet type %02X%02X from %#-15a:%-5d to %#-15a:%-5d length %d on %p (ignored)",
7555 			msg->h.flags.b[0], msg->h.flags.b[1], srcaddr, mDNSVal16(srcport), dstaddr, mDNSVal16(dstport), end - (mDNSu8 *)pkt, InterfaceID);
7556 		if (mDNS_LoggingEnabled)
7557 			{
7558 			int i = 0;
7559 			while (i<end - (mDNSu8 *)pkt)
7560 				{
7561 				char buffer[128];
7562 				char *p = buffer + mDNS_snprintf(buffer, sizeof(buffer), "%04X", i);
7563 				do if (i<end - (mDNSu8 *)pkt) p += mDNS_snprintf(p, sizeof(buffer), " %02X", ((mDNSu8 *)pkt)[i]); while (++i & 15);
7564 				LogInfo("%s", buffer);
7565 				}
7566 			}
7567 		}
7568 	// Packet reception often causes a change to the task list:
7569 	// 1. Inbound queries can cause us to need to send responses
7570 	// 2. Conflicing response packets received from other hosts can cause us to need to send defensive responses
7571 	// 3. Other hosts announcing deletion of shared records can cause us to need to re-assert those records
7572 	// 4. Response packets that answer questions may cause our client to issue new questions
7573 	mDNS_Unlock(m);
7574 	}
7575 
7576 // ***************************************************************************
7577 #if COMPILER_LIKES_PRAGMA_MARK
7578 #pragma mark -
7579 #pragma mark - Searcher Functions
7580 #endif
7581 
7582 // Targets are considered the same if both queries are untargeted, or
7583 // if both are targeted to the same address+port
7584 // (If Target address is zero, TargetPort is undefined)
7585 #define SameQTarget(A,B) (((A)->Target.type == mDNSAddrType_None && (B)->Target.type == mDNSAddrType_None) || \
7586 	(mDNSSameAddress(&(A)->Target, &(B)->Target) && mDNSSameIPPort((A)->TargetPort, (B)->TargetPort)))
7587 
7588 // Note: We explicitly disallow making a public query be a duplicate of a private one. This is to avoid the
7589 // circular deadlock where a client does a query for something like "dns-sd -Q _dns-query-tls._tcp.company.com SRV"
7590 // and we have a key for company.com, so we try to locate the private query server for company.com, which necessarily entails
7591 // doing a standard DNS query for the _dns-query-tls._tcp SRV record for company.com. If we make the latter (public) query
7592 // a duplicate of the former (private) query, then it will block forever waiting for an answer that will never come.
7593 //
7594 // We keep SuppressUnusable questions separate so that we can return a quick response to them and not get blocked behind
7595 // the queries that are not marked SuppressUnusable. But if the query is not suppressed, they are treated the same as
7596 // non-SuppressUnusable questions. This should be fine as the goal of SuppressUnusable is to return quickly only if it
7597 // is suppressed. If it is not suppressed, we do try all the DNS servers for valid answers like any other question.
7598 // The main reason for this design is that cache entries point to a *single* question and that question is responsible
7599 // for keeping the cache fresh as long as it is active. Having multiple active question for a single cache entry
7600 // breaks this design principle.
7601 
7602 // If IsLLQ(Q) is true, it means the question is both:
7603 // (a) long-lived and
7604 // (b) being performed by a unicast DNS long-lived query (either full LLQ, or polling)
7605 // for multicast questions, we don't want to treat LongLived as anything special
7606 #define IsLLQ(Q) ((Q)->LongLived && !mDNSOpaque16IsZero((Q)->TargetQID))
7607 
FindDuplicateQuestion(const mDNS * const m,const DNSQuestion * const question)7608 mDNSlocal DNSQuestion *FindDuplicateQuestion(const mDNS *const m, const DNSQuestion *const question)
7609 	{
7610 	DNSQuestion *q;
7611 	// Note: A question can only be marked as a duplicate of one that occurs *earlier* in the list.
7612 	// This prevents circular references, where two questions are each marked as a duplicate of the other.
7613 	// Accordingly, we break out of the loop when we get to 'question', because there's no point searching
7614 	// further in the list.
7615 	for (q = m->Questions; q && q != question; q=q->next)		// Scan our list for another question
7616 		if (q->InterfaceID == question->InterfaceID &&			// with the same InterfaceID,
7617 			SameQTarget(q, question)                &&			// and same unicast/multicast target settings
7618 			q->qtype      == question->qtype        &&			// type,
7619 			q->qclass     == question->qclass       &&			// class,
7620 			IsLLQ(q)      == IsLLQ(question)        &&			// and long-lived status matches
7621 			(!q->AuthInfo || question->AuthInfo)    &&			// to avoid deadlock, don't make public query dup of a private one
7622 			(q->SuppressQuery == question->SuppressQuery) &&	// Questions that are suppressed/not suppressed
7623 			q->qnamehash  == question->qnamehash    &&
7624 			SameDomainName(&q->qname, &question->qname))		// and name
7625 			return(q);
7626 	return(mDNSNULL);
7627 	}
7628 
7629 // This is called after a question is deleted, in case other identical questions were being suppressed as duplicates
UpdateQuestionDuplicates(mDNS * const m,DNSQuestion * const question)7630 mDNSlocal void UpdateQuestionDuplicates(mDNS *const m, DNSQuestion *const question)
7631 	{
7632 	DNSQuestion *q;
7633 	DNSQuestion *first = mDNSNULL;
7634 
7635 	// This is referring to some other question as duplicate. No other question can refer to this
7636 	// question as a duplicate.
7637 	if (question->DuplicateOf)
7638 		{
7639 		LogInfo("UpdateQuestionDuplicates: question %p %##s (%s) duplicate of %p %##s (%s)",
7640 			question, question->qname.c, DNSTypeName(question->qtype),
7641 			question->DuplicateOf, question->DuplicateOf->qname.c, DNSTypeName(question->DuplicateOf->qtype));
7642 		return;
7643 		}
7644 
7645 	for (q = m->Questions; q; q=q->next)		// Scan our list of questions
7646 		if (q->DuplicateOf == question)			// To see if any questions were referencing this as their duplicate
7647 			{
7648 			q->DuplicateOf = first;
7649 			if (!first)
7650 				{
7651 				first = q;
7652 				// If q used to be a duplicate, but now is not,
7653 				// then inherit the state from the question that's going away
7654 				q->LastQTime         = question->LastQTime;
7655 				q->ThisQInterval     = question->ThisQInterval;
7656 				q->ExpectUnicastResp = question->ExpectUnicastResp;
7657 				q->LastAnswerPktNum  = question->LastAnswerPktNum;
7658 				q->RecentAnswerPkts  = question->RecentAnswerPkts;
7659 				q->RequestUnicast    = question->RequestUnicast;
7660 				q->LastQTxTime       = question->LastQTxTime;
7661 				q->CNAMEReferrals    = question->CNAMEReferrals;
7662 				q->nta               = question->nta;
7663 				q->servAddr          = question->servAddr;
7664 				q->servPort          = question->servPort;
7665 				q->qDNSServer        = question->qDNSServer;
7666 				q->validDNSServers   = question->validDNSServers;
7667 				q->unansweredQueries = question->unansweredQueries;
7668 				q->noServerResponse  = question->noServerResponse;
7669 				q->triedAllServersOnce = question->triedAllServersOnce;
7670 
7671 				q->TargetQID         = question->TargetQID;
7672 				q->LocalSocket       = question->LocalSocket;
7673 
7674 				q->state             = question->state;
7675 			//	q->tcp               = question->tcp;
7676 				q->ReqLease          = question->ReqLease;
7677 				q->expire            = question->expire;
7678 				q->ntries            = question->ntries;
7679 				q->id                = question->id;
7680 
7681 				question->LocalSocket = mDNSNULL;
7682 				question->nta        = mDNSNULL;	// If we've got a GetZoneData in progress, transfer it to the newly active question
7683 			//	question->tcp        = mDNSNULL;
7684 
7685 				if (q->LocalSocket)
7686 					debugf("UpdateQuestionDuplicates transferred LocalSocket pointer for %##s (%s)", q->qname.c, DNSTypeName(q->qtype));
7687 
7688 				if (q->nta)
7689 					{
7690 					LogInfo("UpdateQuestionDuplicates transferred nta pointer for %##s (%s)", q->qname.c, DNSTypeName(q->qtype));
7691 					q->nta->ZoneDataContext = q;
7692 					}
7693 
7694 				// Need to work out how to safely transfer this state too -- appropriate context pointers need to be updated or the code will crash
7695 				if (question->tcp) LogInfo("UpdateQuestionDuplicates did not transfer tcp pointer");
7696 
7697 				if (question->state == LLQ_Established)
7698 					{
7699 					LogInfo("UpdateQuestionDuplicates transferred LLQ state for %##s (%s)", q->qname.c, DNSTypeName(q->qtype));
7700 					question->state = 0;	// Must zero question->state, or mDNS_StopQuery_internal will clean up and cancel our LLQ from the server
7701 					}
7702 
7703 				SetNextQueryTime(m,q);
7704 				}
7705 			}
7706 	}
7707 
mDNS_AddMcastResolver(mDNS * const m,const domainname * d,const mDNSInterfaceID interface,mDNSu32 timeout)7708 mDNSexport McastResolver *mDNS_AddMcastResolver(mDNS *const m, const domainname *d, const mDNSInterfaceID interface, mDNSu32 timeout)
7709 	{
7710 	McastResolver **p = &m->McastResolvers;
7711 	McastResolver *tmp = mDNSNULL;
7712 
7713 	if (!d) d = (const domainname *)"";
7714 
7715 	LogInfo("mDNS_AddMcastResolver: Adding %##s, InterfaceID %p, timeout %u", d->c, interface, timeout);
7716 
7717 	if (m->mDNS_busy != m->mDNS_reentrancy+1)
7718 		LogMsg("mDNS_AddMcastResolver: Lock not held! mDNS_busy (%ld) mDNS_reentrancy (%ld)", m->mDNS_busy, m->mDNS_reentrancy);
7719 
7720 	while (*p)	// Check if we already have this {interface, domain} tuple registered
7721 		{
7722 		if ((*p)->interface == interface && SameDomainName(&(*p)->domain, d))
7723 			{
7724 			if (!((*p)->flags & DNSServer_FlagDelete)) LogMsg("Note: Mcast Resolver domain %##s (%p) registered more than once", d->c, interface);
7725 			(*p)->flags &= ~DNSServer_FlagDelete;
7726 			tmp = *p;
7727 			*p = tmp->next;
7728 			tmp->next = mDNSNULL;
7729 			}
7730 		else
7731 			p=&(*p)->next;
7732 		}
7733 
7734 	if (tmp) *p = tmp; // move to end of list, to ensure ordering from platform layer
7735 	else
7736 		{
7737 		// allocate, add to list
7738 		*p = mDNSPlatformMemAllocate(sizeof(**p));
7739 		if (!*p) LogMsg("mDNS_AddMcastResolver: ERROR!! - malloc");
7740 		else
7741 			{
7742 			(*p)->interface = interface;
7743 			(*p)->flags     = DNSServer_FlagNew;
7744 			(*p)->timeout   = timeout;
7745 			AssignDomainName(&(*p)->domain, d);
7746 			(*p)->next = mDNSNULL;
7747 			}
7748 		}
7749 	return(*p);
7750 	}
7751 
PenaltyTimeForServer(mDNS * m,DNSServer * server)7752 mDNSinline mDNSs32 PenaltyTimeForServer(mDNS *m, DNSServer *server)
7753 	{
7754 	mDNSs32 ptime = 0;
7755 	if (server->penaltyTime != 0)
7756 		{
7757 		ptime = server->penaltyTime - m->timenow;
7758 		if (ptime < 0)
7759 			{
7760 			// This should always be a positive value between 0 and DNSSERVER_PENALTY_TIME
7761 			// If it does not get reset in ResetDNSServerPenalties for some reason, we do it
7762 			// here
7763 			LogMsg("PenaltyTimeForServer: PenaltyTime negative %d, (server penaltyTime %d, timenow %d) resetting the penalty",
7764 				ptime, server->penaltyTime, m->timenow);
7765 			server->penaltyTime = 0;
7766 			ptime = 0;
7767 			}
7768 		}
7769 	return ptime;
7770 	}
7771 
7772 //Checks to see whether the newname is a better match for the name, given the best one we have
7773 //seen so far (given in bestcount).
7774 //Returns -1 if the newname is not a better match
7775 //Returns 0 if the newname is the same as the old match
7776 //Returns 1 if the newname is a better match
BetterMatchForName(const domainname * name,int namecount,const domainname * newname,int newcount,int bestcount)7777 mDNSlocal int BetterMatchForName(const domainname *name, int namecount, const domainname *newname, int newcount,
7778 	int bestcount)
7779 	{
7780 	// If the name contains fewer labels than the new server's domain or the new name
7781 	// contains fewer labels than the current best, then it can't possibly be a better match
7782 	if (namecount < newcount || newcount < bestcount) return -1;
7783 
7784 	// If there is no match, return -1 and the caller will skip this newname for
7785 	// selection
7786 	//
7787 	// If we find a match and the number of labels is the same as bestcount, then
7788 	// we return 0 so that the caller can do additional logic to pick one of
7789 	// the best based on some other factors e.g., penaltyTime
7790 	//
7791 	// If we find a match and the number of labels is more than bestcount, then we
7792 	// return 1 so that the caller can pick this over the old one.
7793 	//
7794 	// Note: newcount can either be equal or greater than bestcount beause of the
7795 	// check above.
7796 
7797 	if (SameDomainName(SkipLeadingLabels(name, namecount - newcount), newname))
7798 		return bestcount == newcount ? 0 : 1;
7799 	else
7800 		return -1;
7801 	}
7802 
7803 // Normally, we have McastResolvers for .local, in-addr.arpa and ip6.arpa. But there
7804 // can be queries that can forced to multicast (ForceMCast) even though they don't end in these
7805 // names. In that case, we give a default timeout of 5 seconds
7806 #define DEFAULT_MCAST_TIMEOUT	5
GetTimeoutForMcastQuestion(mDNS * m,DNSQuestion * question)7807 mDNSlocal mDNSu32 GetTimeoutForMcastQuestion(mDNS *m, DNSQuestion *question)
7808 	{
7809 	McastResolver *curmatch = mDNSNULL;
7810 	int bestmatchlen = -1, namecount = CountLabels(&question->qname);
7811 	McastResolver *curr;
7812 	int bettermatch, currcount;
7813 	for (curr = m->McastResolvers; curr; curr = curr->next)
7814 		{
7815 		currcount = CountLabels(&curr->domain);
7816 		bettermatch = BetterMatchForName(&question->qname, namecount, &curr->domain, currcount, bestmatchlen);
7817 		// Take the first best match. If there are multiple equally good matches (bettermatch = 0), we take
7818 		// the timeout value from the first one
7819 		if (bettermatch == 1)
7820 			{
7821 			curmatch = curr;
7822 			bestmatchlen = currcount;
7823 			}
7824 		}
7825 	LogInfo("GetTimeoutForMcastQuestion: question %##s curmatch %p, Timeout %d", question->qname.c, curmatch,
7826 		curmatch ? curmatch->timeout : DEFAULT_MCAST_TIMEOUT);
7827 	return ( curmatch ? curmatch->timeout : DEFAULT_MCAST_TIMEOUT);
7828 	}
7829 
7830 // Sets all the Valid DNS servers for a question
SetValidDNSServers(mDNS * m,DNSQuestion * question)7831 mDNSexport mDNSu32 SetValidDNSServers(mDNS *m, DNSQuestion *question)
7832 	{
7833 	DNSServer *curmatch = mDNSNULL;
7834 	int bestmatchlen = -1, namecount = CountLabels(&question->qname);
7835 	DNSServer *curr;
7836 	int bettermatch, currcount;
7837 	int index = 0;
7838 	mDNSu32 timeout = 0;
7839 
7840 	question->validDNSServers = zeroOpaque64;
7841 	for (curr = m->DNSServers; curr; curr = curr->next)
7842 		{
7843 		debugf("SetValidDNSServers: Parsing DNS server Address %#a (Domain %##s), Scope: %d", &curr->addr, curr->domain.c, curr->scoped);
7844 		// skip servers that will soon be deleted
7845 		if (curr->flags & DNSServer_FlagDelete)
7846 			{ debugf("SetValidDNSServers: Delete set for index %d, DNS server %#a (Domain %##s), scoped %d", index, &curr->addr, curr->domain.c, curr->scoped); continue; }
7847 
7848 		// This happens normally when you unplug the interface where we reset the interfaceID to mDNSInterface_Any for all
7849 		// the DNS servers whose scope match the interfaceID. Few seconds later, we also receive the updated DNS configuration.
7850 		// But any questions that has mDNSInterface_Any scope that are started/restarted before we receive the update
7851 		// (e.g., CheckSuppressUnusableQuestions is called when interfaces are deregistered with the core) should not
7852 		// match the scoped entries by mistake.
7853 		//
7854 		// Note: DNS configuration change will help pick the new dns servers but currently it does not affect the timeout
7855 
7856 		if (curr->scoped && curr->interface == mDNSInterface_Any)
7857 			{ debugf("SetValidDNSServers: Scoped DNS server %#a (Domain %##s) with Interface Any", &curr->addr, curr->domain.c); continue; }
7858 
7859 		currcount = CountLabels(&curr->domain);
7860 		if ((!curr->scoped && (!question->InterfaceID || (question->InterfaceID == mDNSInterface_Unicast))) || (curr->interface == question->InterfaceID))
7861 			{
7862 			bettermatch = BetterMatchForName(&question->qname, namecount, &curr->domain, currcount, bestmatchlen);
7863 
7864 			// If we found a better match (bettermatch == 1) then clear all the bits
7865 			// corresponding to the old DNSServers that we have may set before and start fresh.
7866 			// If we find an equal match, then include that DNSServer also by setting the corresponding
7867 			// bit
7868 			if ((bettermatch == 1) || (bettermatch == 0))
7869 				{
7870 				curmatch = curr;
7871 				bestmatchlen = currcount;
7872 				if (bettermatch) { debugf("SetValidDNSServers: Resetting all the bits"); question->validDNSServers = zeroOpaque64; timeout = 0; }
7873 				debugf("SetValidDNSServers: question %##s Setting the bit for DNS server Address %#a (Domain %##s), Scoped:%d index %d,"
7874 					" Timeout %d, interface %p", question->qname.c, &curr->addr, curr->domain.c, curr->scoped, index, curr->timeout,
7875 					curr->interface);
7876 				timeout += curr->timeout;
7877 				bit_set_opaque64(question->validDNSServers, index);
7878 				}
7879 			}
7880 		index++;
7881 		}
7882 	question->noServerResponse = 0;
7883 
7884 	debugf("SetValidDNSServers: ValidDNSServer bits  0x%x%x for question %p %##s (%s)",
7885 		question->validDNSServers.l[1], question->validDNSServers.l[0], question, question->qname.c, DNSTypeName(question->qtype));
7886 	// If there are no matching resolvers, then use the default value to timeout
7887 	return (timeout ? timeout : DEFAULT_UDNS_TIMEOUT);
7888 	}
7889 
7890 // Get the Best server that matches a name. If you find penalized servers, look for the one
7891 // that will come out of the penalty box soon
GetBestServer(mDNS * m,const domainname * name,mDNSInterfaceID InterfaceID,mDNSOpaque64 validBits,int * selected,mDNSBool nameMatch)7892 mDNSlocal DNSServer *GetBestServer(mDNS *m, const domainname *name, mDNSInterfaceID InterfaceID, mDNSOpaque64 validBits, int *selected, mDNSBool nameMatch)
7893 	{
7894 	DNSServer *curmatch = mDNSNULL;
7895 	int bestmatchlen = -1, namecount = name ? CountLabels(name) : 0;
7896 	DNSServer *curr;
7897 	mDNSs32 bestPenaltyTime, currPenaltyTime;
7898 	int bettermatch, currcount;
7899 	int index = 0;
7900 	int currindex = -1;
7901 
7902 	debugf("GetBestServer: ValidDNSServer bits  0x%x%x", validBits.l[1], validBits.l[0]);
7903 	bestPenaltyTime = DNSSERVER_PENALTY_TIME + 1;
7904 	for (curr = m->DNSServers; curr; curr = curr->next)
7905 		{
7906 		// skip servers that will soon be deleted
7907 		if (curr->flags & DNSServer_FlagDelete)
7908 			{ debugf("GetBestServer: Delete set for index %d, DNS server %#a (Domain %##s), scoped %d", index, &curr->addr, curr->domain.c, curr->scoped); continue; }
7909 
7910 		// Check if this is a valid DNSServer
7911 		if (!bit_get_opaque64(validBits, index)) { debugf("GetBestServer: continuing for index %d", index); index++; continue; }
7912 
7913 		currcount = CountLabels(&curr->domain);
7914 		currPenaltyTime = PenaltyTimeForServer(m, curr);
7915 
7916 		debugf("GetBestServer: Address %#a (Domain %##s), PenaltyTime(abs) %d, PenaltyTime(rel) %d",
7917 			&curr->addr, curr->domain.c, curr->penaltyTime, currPenaltyTime);
7918 
7919 		// If there are multiple best servers for a given question, we will pick the first one
7920 		// if none of them are penalized. If some of them are penalized in that list, we pick
7921 		// the least penalized one. BetterMatchForName walks through all best matches and
7922 		// "currPenaltyTime < bestPenaltyTime" check lets us either pick the first best server
7923 		// in the list when there are no penalized servers and least one among them
7924 		// when there are some penalized servers
7925 		//
7926 		// Notes on InterfaceID matching:
7927 		//
7928 		// 1) A DNSServer entry may have an InterfaceID but the scoped flag may not be set. This
7929 		// is the old way of specifying an InterfaceID option for DNSServer. We recoginize these
7930 		// entries by "scoped" being false. These are like any other unscoped entries except that
7931 		// if it is picked e.g., domain match, when the packet is sent out later, the packet will
7932 		// be sent out on that interface. Theese entries can be matched by either specifying a
7933 		// zero InterfaceID or non-zero InterfaceID on the question. Specifying an InterfaceID on
7934 		// the question will cause an extra check on matching the InterfaceID on the question
7935 		// against the DNSServer.
7936 		//
7937 		// 2) A DNSServer may also have both scoped set and InterfaceID non-NULL. This
7938 		// is the new way of specifying an InterfaceID option for DNSServer. These will be considered
7939 		// only when the question has non-zero interfaceID.
7940 
7941 		if ((!curr->scoped && !InterfaceID) || (curr->interface == InterfaceID))
7942 			{
7943 
7944 			// If we know that all the names are already equally good matches, then skip calling BetterMatchForName.
7945 			// This happens when we initially walk all the DNS servers and set the validity bit on the question.
7946 			// Actually we just need PenaltyTime match, but for the sake of readability we just skip the expensive
7947 			// part and still do some redundant steps e.g., InterfaceID match
7948 
7949 			if (nameMatch) bettermatch = BetterMatchForName(name, namecount, &curr->domain, currcount, bestmatchlen);
7950 			else bettermatch = 0;
7951 
7952 			// If we found a better match (bettermatch == 1) then we don't need to
7953 			// compare penalty times. But if we found an equal match, then we compare
7954 			// the penalty times to pick a better match
7955 
7956 			if ((bettermatch == 1) || ((bettermatch == 0) && currPenaltyTime < bestPenaltyTime))
7957 				{ currindex = index; curmatch = curr; bestmatchlen = currcount; bestPenaltyTime = currPenaltyTime; }
7958 			}
7959 		index++;
7960 		}
7961 	if (selected) *selected = currindex;
7962 	return curmatch;
7963 	}
7964 
7965 // Look up a DNS Server, matching by name and InterfaceID
GetServerForName(mDNS * m,const domainname * name,mDNSInterfaceID InterfaceID)7966 mDNSexport DNSServer *GetServerForName(mDNS *m, const domainname *name, mDNSInterfaceID InterfaceID)
7967     {
7968 	DNSServer *curmatch = mDNSNULL;
7969 	char *ifname = mDNSNULL;	// for logging purposes only
7970 	mDNSOpaque64 allValid;
7971 
7972 	if ((InterfaceID == mDNSInterface_Unicast) || (InterfaceID == mDNSInterface_LocalOnly))
7973 		InterfaceID = mDNSNULL;
7974 
7975 	if (InterfaceID) ifname = InterfaceNameForID(m, InterfaceID);
7976 
7977 	// By passing in all ones, we make sure that every DNS server is considered
7978 	allValid.l[0] = allValid.l[1] = 0xFFFFFFFF;
7979 
7980 	curmatch = GetBestServer(m, name, InterfaceID, allValid, mDNSNULL, mDNStrue);
7981 
7982 	if (curmatch != mDNSNULL)
7983 		LogInfo("GetServerForName: DNS server %#a:%d (Penalty Time Left %d) (Scope %s:%p) found for name %##s", &curmatch->addr,
7984 		    mDNSVal16(curmatch->port), (curmatch->penaltyTime ? (curmatch->penaltyTime - m->timenow) : 0), ifname ? ifname : "None",
7985 		InterfaceID, name);
7986 	else
7987 		LogInfo("GetServerForName: no DNS server (Scope %s:%p) found for name %##s", ifname ? ifname : "None", InterfaceID, name);
7988 
7989 	return(curmatch);
7990 	}
7991 
7992 // Look up a DNS Server for a question within its valid DNSServer bits
GetServerForQuestion(mDNS * m,DNSQuestion * question)7993 mDNSexport DNSServer *GetServerForQuestion(mDNS *m, DNSQuestion *question)
7994     {
7995 	DNSServer *curmatch = mDNSNULL;
7996 	char *ifname = mDNSNULL;	// for logging purposes only
7997 	mDNSInterfaceID InterfaceID = question->InterfaceID;
7998 	const domainname *name = &question->qname;
7999 	int currindex;
8000 
8001 	if ((InterfaceID == mDNSInterface_Unicast) || (InterfaceID == mDNSInterface_LocalOnly))
8002 		InterfaceID = mDNSNULL;
8003 
8004 	if (InterfaceID) ifname = InterfaceNameForID(m, InterfaceID);
8005 
8006 	if (!mDNSOpaque64IsZero(&question->validDNSServers))
8007 		{
8008 		curmatch = GetBestServer(m, name, InterfaceID, question->validDNSServers, &currindex, mDNSfalse);
8009 		if (currindex != -1) bit_clr_opaque64(question->validDNSServers, currindex);
8010 		}
8011 
8012 	if (curmatch != mDNSNULL)
8013 		LogInfo("GetServerForQuestion: %p DNS server %#a:%d (Penalty Time Left %d) (Scope %s:%p) found for name %##s (%s)", question, &curmatch->addr,
8014 		    mDNSVal16(curmatch->port), (curmatch->penaltyTime ? (curmatch->penaltyTime - m->timenow) : 0), ifname ? ifname : "None",
8015 		InterfaceID, name, DNSTypeName(question->qtype));
8016 	else
8017 		LogInfo("GetServerForQuestion: %p no DNS server (Scope %s:%p) found for name %##s (%s)", question, ifname ? ifname : "None", InterfaceID, name, DNSTypeName(question->qtype));
8018 
8019 	return(curmatch);
8020 	}
8021 
8022 
8023 #define ValidQuestionTarget(Q) (((Q)->Target.type == mDNSAddrType_IPv4 || (Q)->Target.type == mDNSAddrType_IPv6) && \
8024 	(mDNSSameIPPort((Q)->TargetPort, UnicastDNSPort) || mDNSSameIPPort((Q)->TargetPort, MulticastDNSPort)))
8025 
8026 // Called in normal client context (lock not held)
LLQNATCallback(mDNS * m,NATTraversalInfo * n)8027 mDNSlocal void LLQNATCallback(mDNS *m, NATTraversalInfo *n)
8028 	{
8029 	DNSQuestion *q;
8030 	(void)n;    // Unused
8031 	mDNS_Lock(m);
8032 	LogInfo("LLQNATCallback external address:port %.4a:%u, NAT result %d", &n->ExternalAddress, mDNSVal16(n->ExternalPort), n->Result);
8033 	for (q = m->Questions; q; q=q->next)
8034 		if (ActiveQuestion(q) && !mDNSOpaque16IsZero(q->TargetQID) && q->LongLived)
8035 			startLLQHandshake(m, q);	// If ExternalPort is zero, will do StartLLQPolling instead
8036 #if APPLE_OSX_mDNSResponder
8037 	UpdateAutoTunnelDomainStatuses(m);
8038 #endif
8039 	mDNS_Unlock(m);
8040 	}
8041 
ShouldSuppressQuery(mDNS * const m,domainname * qname,mDNSu16 qtype,mDNSInterfaceID InterfaceID)8042 mDNSlocal mDNSBool ShouldSuppressQuery(mDNS *const m, domainname *qname, mDNSu16 qtype, mDNSInterfaceID InterfaceID)
8043 	{
8044 	NetworkInterfaceInfo *i;
8045 	mDNSs32 iptype;
8046 	DomainAuthInfo *AuthInfo;
8047 
8048 	if (qtype == kDNSType_A) iptype = mDNSAddrType_IPv4;
8049 	else if (qtype == kDNSType_AAAA) iptype = mDNSAddrType_IPv6;
8050 	else { LogInfo("ShouldSuppressQuery: Query not suppressed for %##s, qtype %s, not A/AAAA type", qname, DNSTypeName(qtype)); return mDNSfalse; }
8051 
8052 	// We still want the ability to be able to listen to the local services and hence
8053 	// don't fail .local requests. We always have a loopback interface which we don't
8054 	// check here.
8055 	if (InterfaceID != mDNSInterface_Unicast && IsLocalDomain(qname)) { LogInfo("ShouldSuppressQuery: Query not suppressed for %##s, qtype %s, Local question", qname, DNSTypeName(qtype)); return mDNSfalse; }
8056 
8057 	// Skip Private domains as we have special addresses to get the hosts in the Private domain
8058 	AuthInfo = GetAuthInfoForName_internal(m, qname);
8059 	if (AuthInfo && !AuthInfo->deltime && AuthInfo->AutoTunnel)
8060 		{ LogInfo("ShouldSuppressQuery: Query not suppressed for %##s, qtype %s, Private Domain", qname, DNSTypeName(qtype)); return mDNSfalse; }
8061 
8062 	// Match on Type, Address and InterfaceID
8063 	//
8064 	// Check whether we are looking for a name that ends in .local, then presence of a link-local
8065 	// address on the interface is sufficient.
8066 	for (i = m->HostInterfaces; i; i = i->next)
8067 		{
8068 		if (i->ip.type != iptype) continue;
8069 
8070 		if (!InterfaceID || (InterfaceID == mDNSInterface_LocalOnly) || (InterfaceID == mDNSInterface_P2P) ||
8071 			(InterfaceID == mDNSInterface_Unicast) || (i->InterfaceID == InterfaceID))
8072 			{
8073 			if (iptype == mDNSAddrType_IPv4 && !mDNSv4AddressIsLoopback(&i->ip.ip.v4) && !mDNSv4AddressIsLinkLocal(&i->ip.ip.v4))
8074 				{
8075 				LogInfo("ShouldSuppressQuery: Query not suppressed for %##s, qtype %s, Local Address %.4a found", qname, DNSTypeName(qtype),
8076 					&i->ip.ip.v4);
8077 				return mDNSfalse;
8078 				}
8079 			else if (iptype == mDNSAddrType_IPv6 &&
8080 				!mDNSv6AddressIsLoopback(&i->ip.ip.v6) &&
8081 				!mDNSv6AddressIsLinkLocal(&i->ip.ip.v6) &&
8082 				!mDNSSameIPv6Address(i->ip.ip.v6, m->AutoTunnelHostAddr) &&
8083 				!mDNSSameIPv6Address(i->ip.ip.v6, m->AutoTunnelRelayAddrOut))
8084 				{
8085 				LogInfo("ShouldSuppressQuery: Query not suppressed for %##s, qtype %s, Local Address %.16a found", qname, DNSTypeName(qtype),
8086 					&i->ip.ip.v6);
8087 				return mDNSfalse;
8088 				}
8089 			}
8090 		}
8091 	LogInfo("ShouldSuppressQuery: Query suppressed for %##s, qtype %s, because no matching interface found", qname, DNSTypeName(qtype));
8092 	return mDNStrue;
8093 	}
8094 
CacheRecordRmvEventsForCurrentQuestion(mDNS * const m,DNSQuestion * q)8095 mDNSlocal void CacheRecordRmvEventsForCurrentQuestion(mDNS *const m, DNSQuestion *q)
8096 	{
8097 	CacheRecord *rr;
8098 	mDNSu32 slot;
8099 	CacheGroup *cg;
8100 
8101 	slot = HashSlot(&q->qname);
8102 	cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname);
8103 	for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next)
8104 		{
8105 		// Don't deliver RMV events for negative records
8106 		if (rr->resrec.RecordType == kDNSRecordTypePacketNegative)
8107 			{
8108  			LogInfo("CacheRecordRmvEventsForCurrentQuestion: CacheRecord %s Suppressing RMV events for question %p %##s (%s), CRActiveQuestion %p, CurrentAnswers %d",
8109 				CRDisplayString(m, rr), q, q->qname.c, DNSTypeName(q->qtype), rr->CRActiveQuestion, q->CurrentAnswers);
8110 			continue;
8111 			}
8112 
8113 		if (SameNameRecordAnswersQuestion(&rr->resrec, q))
8114 			{
8115  			LogInfo("CacheRecordRmvEventsForCurrentQuestion: Calling AnswerCurrentQuestionWithResourceRecord (RMV) for question %##s using resource record %s LocalAnswers %d",
8116 				q->qname.c, CRDisplayString(m, rr), q->LOAddressAnswers);
8117 
8118 			q->CurrentAnswers--;
8119 			if (rr->resrec.rdlength > SmallRecordLimit) q->LargeAnswers--;
8120 			if (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) q->UniqueAnswers--;
8121 
8122 			if (rr->CRActiveQuestion == q)
8123 				{
8124 				DNSQuestion *qptr;
8125 				// If this was the active question for this cache entry, it was the one that was
8126 				// responsible for keeping the cache entry fresh when the cache entry was reaching
8127 				// its expiry. We need to handover the responsibility to someone else. Otherwise,
8128 				// when the cache entry is about to expire, we won't find an active question
8129 				// (pointed by CRActiveQuestion) to refresh the cache.
8130 				for (qptr = m->Questions; qptr; qptr=qptr->next)
8131  					if (qptr != q && ActiveQuestion(qptr) && ResourceRecordAnswersQuestion(&rr->resrec, qptr))
8132 						break;
8133 
8134 				if (qptr)
8135 					LogInfo("CacheRecordRmvEventsForCurrentQuestion: Updating CRActiveQuestion to %p for cache record %s, "
8136 						"Original question CurrentAnswers %d, new question CurrentAnswers %d, SuppressUnusable %d, SuppressQuery %d",
8137 						qptr, CRDisplayString(m,rr), q->CurrentAnswers, qptr->CurrentAnswers, qptr->SuppressUnusable, qptr->SuppressQuery);
8138 
8139 				rr->CRActiveQuestion = qptr;		// Question used to be active; new value may or may not be null
8140 				if (!qptr) m->rrcache_active--;	// If no longer active, decrement rrcache_active count
8141 				}
8142 			AnswerCurrentQuestionWithResourceRecord(m, rr, QC_rmv);
8143 			if (m->CurrentQuestion != q) break;		// If callback deleted q, then we're finished here
8144 			}
8145 		}
8146 	}
8147 
IsQuestionNew(mDNS * const m,DNSQuestion * question)8148 mDNSlocal mDNSBool IsQuestionNew(mDNS *const m, DNSQuestion *question)
8149 	{
8150 	DNSQuestion *q;
8151 	for (q = m->NewQuestions; q; q = q->next)
8152 		if (q == question) return mDNStrue;
8153 	return mDNSfalse;
8154 	}
8155 
LocalRecordRmvEventsForQuestion(mDNS * const m,DNSQuestion * q)8156 mDNSlocal mDNSBool LocalRecordRmvEventsForQuestion(mDNS *const m, DNSQuestion *q)
8157 	{
8158 	AuthRecord *rr;
8159 	mDNSu32 slot;
8160 	AuthGroup *ag;
8161 
8162 	if (m->CurrentQuestion)
8163 		LogMsg("LocalRecordRmvEventsForQuestion: ERROR m->CurrentQuestion already set: %##s (%s)",
8164 			m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
8165 
8166 	if (IsQuestionNew(m, q))
8167 		{
8168 		LogInfo("LocalRecordRmvEventsForQuestion: New Question %##s (%s)", q->qname.c, DNSTypeName(q->qtype));
8169 		return mDNStrue;
8170 		}
8171 	m->CurrentQuestion = q;
8172 	slot = AuthHashSlot(&q->qname);
8173 	ag = AuthGroupForName(&m->rrauth, slot, q->qnamehash, &q->qname);
8174 	if (ag)
8175 		{
8176 		for (rr = ag->members; rr; rr=rr->next)
8177 			// Filter the /etc/hosts records - LocalOnly, Unique, A/AAAA/CNAME
8178 			if (LORecordAnswersAddressType(rr) && LocalOnlyRecordAnswersQuestion(rr, q))
8179 				{
8180 				LogInfo("LocalRecordRmvEventsForQuestion: Delivering possible Rmv events with record %s",
8181 					ARDisplayString(m, rr));
8182 				if (q->CurrentAnswers <= 0 || q->LOAddressAnswers <= 0)
8183 					{
8184 					LogMsg("LocalRecordRmvEventsForQuestion: ERROR!! CurrentAnswers or LOAddressAnswers is zero %p %##s"
8185 						" (%s) CurrentAnswers %d, LOAddressAnswers %d", q, q->qname.c, DNSTypeName(q->qtype),
8186 						q->CurrentAnswers, q->LOAddressAnswers);
8187 					continue;
8188 					}
8189 				AnswerLocalQuestionWithLocalAuthRecord(m, rr, QC_rmv);		// MUST NOT dereference q again
8190 				if (m->CurrentQuestion != q) { m->CurrentQuestion = mDNSNULL; return mDNSfalse; }
8191 				}
8192 		}
8193 	m->CurrentQuestion = mDNSNULL;
8194 	return mDNStrue;
8195 	}
8196 
8197 // Returns false if the question got deleted while delivering the RMV events
8198 // The caller should handle the case
CacheRecordRmvEventsForQuestion(mDNS * const m,DNSQuestion * q)8199 mDNSlocal mDNSBool CacheRecordRmvEventsForQuestion(mDNS *const m, DNSQuestion *q)
8200 	{
8201 	if (m->CurrentQuestion)
8202 		LogMsg("CacheRecordRmvEventsForQuestion: ERROR m->CurrentQuestion already set: %##s (%s)",
8203 			m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
8204 
8205 	// If it is a new question, we have not delivered any ADD events yet. So, don't deliver RMV events.
8206 	// If this question was answered using local auth records, then you can't deliver RMVs using cache
8207 	if (!IsQuestionNew(m, q) && !q->LOAddressAnswers)
8208 		{
8209 		m->CurrentQuestion = q;
8210 		CacheRecordRmvEventsForCurrentQuestion(m, q);
8211 		if (m->CurrentQuestion != q) { m->CurrentQuestion = mDNSNULL; return mDNSfalse; }
8212 		m->CurrentQuestion = mDNSNULL;
8213 		}
8214 	else { LogInfo("CacheRecordRmvEventsForQuestion: Question %p %##s (%s) is a new question", q, q->qname.c, DNSTypeName(q->qtype)); }
8215 	return mDNStrue;
8216 	}
8217 
8218 // The caller should hold the lock
CheckSuppressUnusableQuestions(mDNS * const m)8219 mDNSexport void CheckSuppressUnusableQuestions(mDNS *const m)
8220 	{
8221 	DNSQuestion *q;
8222 	DNSQuestion *restart = mDNSNULL;
8223 
8224 	// We look through all questions including new questions. During network change events,
8225 	// we potentially restart questions here in this function that ends up as new questions,
8226 	// which may be suppressed at this instance. Before it is handled we get another network
8227 	// event that changes the status e.g., address becomes available. If we did not process
8228 	// new questions, we would never change its SuppressQuery status.
8229 	//
8230 	// CurrentQuestion is used by RmvEventsForQuestion below. While delivering RMV events, the
8231 	// application callback can potentially stop the current question (detected by CurrentQuestion) or
8232 	// *any* other question which could be the next one that we may process here. RestartQuestion
8233 	// points to the "next" question which will be automatically advanced in mDNS_StopQuery_internal
8234 	// if the "next" question is stopped while the CurrentQuestion is stopped
8235 	if (m->RestartQuestion)
8236 		LogMsg("CheckSuppressUnusableQuestions: ERROR!! m->RestartQuestion already set: %##s (%s)",
8237 			m->RestartQuestion->qname.c, DNSTypeName(m->RestartQuestion->qtype));
8238 	m->RestartQuestion = m->Questions;
8239 	while (m->RestartQuestion)
8240 		{
8241 		q = m->RestartQuestion;
8242 		m->RestartQuestion = q->next;
8243 		if (!mDNSOpaque16IsZero(q->TargetQID) && q->SuppressUnusable)
8244 			{
8245 			mDNSBool old = q->SuppressQuery;
8246 			q->SuppressQuery = ShouldSuppressQuery(m, &q->qname, q->qtype, q->InterfaceID);
8247 			if (q->SuppressQuery != old)
8248 				{
8249 				// NOTE: CacheRecordRmvEventsForQuestion will not generate RMV events for queries that have non-zero
8250 				// LOddressAnswers. Hence it is important that we call CacheRecordRmvEventsForQuestion before
8251 				// LocalRecordRmvEventsForQuestion (which decrements LOAddressAnswers)
8252 
8253   				if (q->SuppressQuery)
8254   					{
8255   					// Previously it was not suppressed, Generate RMV events for the ADDs that we might have delivered before
8256  					// followed by a negative cache response. Temporarily turn off suppression so that
8257  					// AnswerCurrentQuestionWithResourceRecord can answer the question
8258  					q->SuppressQuery = mDNSfalse;
8259  					if (!CacheRecordRmvEventsForQuestion(m, q)) { LogInfo("CheckSuppressUnusableQuestions: Question deleted while delivering RMV events"); continue; }
8260  					q->SuppressQuery = mDNStrue;
8261   					}
8262 
8263 				// SuppressUnusable does not affect questions that are answered from the local records (/etc/hosts)
8264 				// and SuppressQuery status does not mean anything for these questions. As we are going to stop the
8265 				// question below, we need to deliver the RMV events so that the ADDs that will be delivered during
8266 				// the restart will not be a duplicate ADD
8267  				if (!LocalRecordRmvEventsForQuestion(m, q)) { LogInfo("CheckSuppressUnusableQuestions: Question deleted while delivering RMV events"); continue; }
8268 
8269 				// There are two cases here.
8270 				//
8271 				// 1. Previously it was suppressed and now it is not suppressed, restart the question so
8272 				// that it will start as a new question. Note that we can't just call ActivateUnicastQuery
8273 				// because when we get the response, if we had entries in the cache already, it will not answer
8274 				// this question if the cache entry did not change. Hence, we need to restart
8275 				// the query so that it can be answered from the cache.
8276 				//
8277 				// 2. Previously it was not suppressed and now it is suppressed. We need to restart the questions
8278 				// so that we redo the duplicate checks in mDNS_StartQuery_internal. A SuppressUnusable question
8279 				// is a duplicate of non-SuppressUnusable question if it is not suppressed (SuppressQuery is false).
8280 				// A SuppressUnusable question is not a duplicate of non-SuppressUnusable question if it is suppressed
8281 				// (SuppressQuery is true). The reason for this is that when a question is suppressed, we want an
8282 				// immediate response and not want to be blocked behind a question that is querying DNS servers. When
8283 				// the question is not suppressed, we don't want two active questions sending packets on the wire.
8284 				// This affects both efficiency and also the current design where there is only one active question
8285 				// pointed to from a cache entry.
8286 				//
8287 				// We restart queries in a two step process by first calling stop and build a temporary list which we
8288 				// will restart at the end. The main reason for the two step process is to handle duplicate questions.
8289 				// If there are duplicate questions, calling stop inherits the values from another question on the list (which
8290 				// will soon become the real question) including q->ThisQInterval which might be zero if it was
8291 				// suppressed before. At the end when we have restarted all questions, none of them is active as each
8292 				// inherits from one another and we need to reactivate one of the questions here which is a little hacky.
8293 				//
8294 				// It is much cleaner and less error prone to build a list of questions and restart at the end.
8295 
8296 				LogInfo("CheckSuppressUnusableQuestions: Stop question %p %##s (%s)", q, q->qname.c, DNSTypeName(q->qtype));
8297 				mDNS_StopQuery_internal(m, q);
8298 				q->next = restart;
8299 				restart = q;
8300 				}
8301 			}
8302 		}
8303 	while (restart)
8304 		{
8305 		q = restart;
8306 		restart = restart->next;
8307 		q->next = mDNSNULL;
8308 		LogInfo("CheckSuppressUnusableQuestions: Start question %p %##s (%s)", q, q->qname.c, DNSTypeName(q->qtype));
8309 		mDNS_StartQuery_internal(m, q);
8310 		}
8311 	}
8312 
mDNS_StartQuery_internal(mDNS * const m,DNSQuestion * const question)8313 mDNSexport mStatus mDNS_StartQuery_internal(mDNS *const m, DNSQuestion *const question)
8314 	{
8315 	if (question->Target.type && !ValidQuestionTarget(question))
8316 		{
8317 		LogMsg("mDNS_StartQuery_internal: Warning! Target.type = %ld port = %u (Client forgot to initialize before calling mDNS_StartQuery? for question %##s)",
8318 			question->Target.type, mDNSVal16(question->TargetPort), question->qname.c);
8319 		question->Target.type = mDNSAddrType_None;
8320 		}
8321 
8322 	if (!question->Target.type) question->TargetPort = zeroIPPort;	// If no question->Target specified clear TargetPort
8323 
8324 	question->TargetQID =
8325 #ifndef UNICAST_DISABLED
8326 		(question->Target.type || Question_uDNS(question)) ? mDNS_NewMessageID(m) :
8327 #endif // UNICAST_DISABLED
8328 		zeroID;
8329 
8330 	debugf("mDNS_StartQuery: %##s (%s)", question->qname.c, DNSTypeName(question->qtype));
8331 
8332 	if (m->rrcache_size == 0)	// Can't do queries if we have no cache space allocated
8333 		return(mStatus_NoCache);
8334 	else
8335 		{
8336 		int i;
8337 		DNSQuestion **q;
8338 
8339 		if (!ValidateDomainName(&question->qname))
8340 			{
8341 			LogMsg("Attempt to start query with invalid qname %##s (%s)", question->qname.c, DNSTypeName(question->qtype));
8342 			return(mStatus_Invalid);
8343 			}
8344 
8345 		// Note: It important that new questions are appended at the *end* of the list, not prepended at the start
8346 		q = &m->Questions;
8347 		if (question->InterfaceID == mDNSInterface_LocalOnly || question->InterfaceID == mDNSInterface_P2P) q = &m->LocalOnlyQuestions;
8348 		while (*q && *q != question) q=&(*q)->next;
8349 
8350 		if (*q)
8351 			{
8352 			LogMsg("Error! Tried to add a question %##s (%s) %p that's already in the active list",
8353 				question->qname.c, DNSTypeName(question->qtype), question);
8354 			return(mStatus_AlreadyRegistered);
8355 			}
8356 
8357 		*q = question;
8358 
8359 		// If this question is referencing a specific interface, verify it exists
8360 		if (question->InterfaceID && question->InterfaceID != mDNSInterface_LocalOnly && question->InterfaceID != mDNSInterface_Unicast && question->InterfaceID != mDNSInterface_P2P)
8361 			{
8362 			NetworkInterfaceInfo *intf = FirstInterfaceForID(m, question->InterfaceID);
8363 			if (!intf)
8364 				LogMsg("Note: InterfaceID %p for question %##s (%s) not currently found in active interface list",
8365 					question->InterfaceID, question->qname.c, DNSTypeName(question->qtype));
8366 			}
8367 
8368 		// Note: In the case where we already have the answer to this question in our cache, that may be all the client
8369 		// wanted, and they may immediately cancel their question. In this case, sending an actual query on the wire would
8370 		// be a waste. For that reason, we schedule our first query to go out in half a second (InitialQuestionInterval).
8371 		// If AnswerNewQuestion() finds that we have *no* relevant answers currently in our cache, then it will accelerate
8372 		// that to go out immediately.
8373 		question->next              = mDNSNULL;
8374 		question->qnamehash         = DomainNameHashValue(&question->qname);	// MUST do this before FindDuplicateQuestion()
8375 		question->DelayAnswering    = CheckForSoonToExpireRecords(m, &question->qname, question->qnamehash, HashSlot(&question->qname));
8376 		question->LastQTime         = m->timenow;
8377 		question->ThisQInterval     = InitialQuestionInterval;					// MUST be > zero for an active question
8378 		question->ExpectUnicastResp = 0;
8379 		question->LastAnswerPktNum  = m->PktNum;
8380 		question->RecentAnswerPkts  = 0;
8381 		question->CurrentAnswers    = 0;
8382 		question->LargeAnswers      = 0;
8383 		question->UniqueAnswers     = 0;
8384 		question->LOAddressAnswers  = 0;
8385 		question->FlappingInterface1 = mDNSNULL;
8386 		question->FlappingInterface2 = mDNSNULL;
8387 		// Must do AuthInfo and SuppressQuery before calling FindDuplicateQuestion()
8388 		question->AuthInfo          = GetAuthInfoForQuestion(m, question);
8389 		if (question->SuppressUnusable)
8390 			question->SuppressQuery = ShouldSuppressQuery(m, &question->qname, question->qtype, question->InterfaceID);
8391 		else
8392 			question->SuppressQuery = 0;
8393 		question->DuplicateOf       = FindDuplicateQuestion(m, question);
8394 		question->NextInDQList      = mDNSNULL;
8395 		question->SendQNow          = mDNSNULL;
8396 		question->SendOnAll         = mDNSfalse;
8397 		question->RequestUnicast    = 0;
8398 		question->LastQTxTime       = m->timenow;
8399 		question->CNAMEReferrals    = 0;
8400 
8401 		// We'll create our question->LocalSocket on demand, if needed.
8402 		// We won't need one for duplicate questions, or from questions answered immediately out of the cache.
8403 		// We also don't need one for LLQs because (when we're using NAT) we want them all to share a single
8404 		// NAT mapping for receiving inbound add/remove events.
8405 		question->LocalSocket       = mDNSNULL;
8406 		question->deliverAddEvents  = mDNSfalse;
8407 		question->qDNSServer        = mDNSNULL;
8408 		question->unansweredQueries = 0;
8409 		question->nta               = mDNSNULL;
8410 		question->servAddr          = zeroAddr;
8411 		question->servPort          = zeroIPPort;
8412 		question->tcp               = mDNSNULL;
8413 		question->NoAnswer          = NoAnswer_Normal;
8414 
8415 		question->state             = LLQ_InitialRequest;
8416 		question->ReqLease          = 0;
8417 		question->expire            = 0;
8418 		question->ntries            = 0;
8419 		question->id                = zeroOpaque64;
8420 		question->validDNSServers   = zeroOpaque64;
8421 		question->triedAllServersOnce = 0;
8422 		question->noServerResponse  = 0;
8423 		question->StopTime = 0;
8424 		if (question->WakeOnResolve)
8425 			{
8426 			question->WakeOnResolveCount = InitialWakeOnResolveCount;
8427 			mDNS_PurgeBeforeResolve(m, question);
8428 			}
8429 		else
8430 			question->WakeOnResolveCount = 0;
8431 
8432 		if (question->DuplicateOf) question->AuthInfo = question->DuplicateOf->AuthInfo;
8433 
8434 		for (i=0; i<DupSuppressInfoSize; i++)
8435 			question->DupSuppress[i].InterfaceID = mDNSNULL;
8436 
8437 		debugf("mDNS_StartQuery: Question %##s (%s) Interface %p Now %d Send in %d Answer in %d (%p) %s (%p)",
8438 			question->qname.c, DNSTypeName(question->qtype), question->InterfaceID, m->timenow,
8439 			NextQSendTime(question) - m->timenow,
8440 			question->DelayAnswering ? question->DelayAnswering - m->timenow : 0,
8441 			question, question->DuplicateOf ? "duplicate of" : "not duplicate", question->DuplicateOf);
8442 
8443 		if (question->DelayAnswering)
8444 			LogInfo("mDNS_StartQuery_internal: Delaying answering for %d ticks while cache stabilizes for %##s (%s)",
8445 				question->DelayAnswering - m->timenow, question->qname.c, DNSTypeName(question->qtype));
8446 
8447 		if (question->InterfaceID == mDNSInterface_LocalOnly || question->InterfaceID == mDNSInterface_P2P)
8448 			{
8449 			if (!m->NewLocalOnlyQuestions) m->NewLocalOnlyQuestions = question;
8450 			}
8451 		else
8452 			{
8453 			if (!m->NewQuestions) m->NewQuestions = question;
8454 
8455 			// If the question's id is non-zero, then it's Wide Area
8456 			// MUST NOT do this Wide Area setup until near the end of
8457 			// mDNS_StartQuery_internal -- this code may itself issue queries (e.g. SOA,
8458 			// NS, etc.) and if we haven't finished setting up our own question and setting
8459 			// m->NewQuestions if necessary then we could end up recursively re-entering
8460 			// this routine with the question list data structures in an inconsistent state.
8461 			if (!mDNSOpaque16IsZero(question->TargetQID))
8462 				{
8463 				// Duplicate questions should have the same DNSServers so that when we find
8464 				// a matching resource record, all of them get the answers. Calling GetServerForQuestion
8465 				// for the duplicate question may get a different DNS server from the original question
8466 				mDNSu32 timeout = SetValidDNSServers(m, question);
8467 				// We set the timeout whenever mDNS_StartQuery_internal is called. This means if we have
8468 				// a networking change/search domain change that calls this function again we keep
8469 				// reinitializing the timeout value which means it may never timeout. If this becomes
8470 				// a common case in the future, we can easily fix this by adding extra state that
8471 				// indicates that we have already set the StopTime.
8472 				if (question->TimeoutQuestion)
8473 					question->StopTime = NonZeroTime(m->timenow + timeout * mDNSPlatformOneSecond);
8474 				if (question->DuplicateOf)
8475 					{
8476 					question->validDNSServers = question->DuplicateOf->validDNSServers;
8477 					question->qDNSServer = question->DuplicateOf->qDNSServer;
8478 					LogInfo("mDNS_StartQuery_internal: Duplicate question %p (%p) %##s (%s), Timeout %d, DNS Server %#a:%d",
8479 						question, question->DuplicateOf, question->qname.c, DNSTypeName(question->qtype), timeout,
8480 						question->qDNSServer ? &question->qDNSServer->addr : mDNSNULL,
8481 					    mDNSVal16(question->qDNSServer ? question->qDNSServer->port : zeroIPPort));
8482 					}
8483 				else
8484 					{
8485 					question->qDNSServer = GetServerForQuestion(m, question);
8486 					LogInfo("mDNS_StartQuery_internal: question %p %##s (%s) Timeout %d, DNS Server %#a:%d",
8487 						question, question->qname.c, DNSTypeName(question->qtype), timeout,
8488 						question->qDNSServer ? &question->qDNSServer->addr : mDNSNULL,
8489 					    mDNSVal16(question->qDNSServer ? question->qDNSServer->port : zeroIPPort));
8490 					}
8491 				ActivateUnicastQuery(m, question, mDNSfalse);
8492 
8493 				// If long-lived query, and we don't have our NAT mapping active, start it now
8494 				if (question->LongLived && !m->LLQNAT.clientContext)
8495 					{
8496 					m->LLQNAT.Protocol       = NATOp_MapUDP;
8497 					m->LLQNAT.IntPort        = m->UnicastPort4;
8498 					m->LLQNAT.RequestedPort  = m->UnicastPort4;
8499 					m->LLQNAT.clientCallback = LLQNATCallback;
8500 					m->LLQNAT.clientContext  = (void*)1; // Means LLQ NAT Traversal is active
8501 					mDNS_StartNATOperation_internal(m, &m->LLQNAT);
8502 					}
8503 
8504 #if APPLE_OSX_mDNSResponder
8505 				if (question->LongLived)
8506 					UpdateAutoTunnelDomainStatuses(m);
8507 #endif
8508 
8509 				}
8510 			else
8511 				{
8512 				if (question->TimeoutQuestion)
8513 					question->StopTime = NonZeroTime(m->timenow + GetTimeoutForMcastQuestion(m, question) * mDNSPlatformOneSecond);
8514 				}
8515 			if (question->StopTime) SetNextQueryStopTime(m, question);
8516 			SetNextQueryTime(m,question);
8517 			}
8518 
8519 		return(mStatus_NoError);
8520 		}
8521 	}
8522 
8523 // CancelGetZoneData is an internal routine (i.e. must be called with the lock already held)
CancelGetZoneData(mDNS * const m,ZoneData * nta)8524 mDNSexport void CancelGetZoneData(mDNS *const m, ZoneData *nta)
8525 	{
8526 	debugf("CancelGetZoneData %##s (%s)", nta->question.qname.c, DNSTypeName(nta->question.qtype));
8527 	// This function may be called anytime to free the zone information.The question may or may not have stopped.
8528 	// If it was already stopped, mDNS_StopQuery_internal would have set q->ThisQInterval to -1 and should not
8529 	// call it again
8530 	if (nta->question.ThisQInterval != -1)
8531 		{
8532 		mDNS_StopQuery_internal(m, &nta->question);
8533 		if (nta->question.ThisQInterval != -1)
8534 			LogMsg("CancelGetZoneData: Question %##s (%s) ThisQInterval %d not -1", nta->question.qname.c, DNSTypeName(nta->question.qtype), nta->question.ThisQInterval);
8535 		}
8536 	mDNSPlatformMemFree(nta);
8537 	}
8538 
mDNS_StopQuery_internal(mDNS * const m,DNSQuestion * const question)8539 mDNSexport mStatus mDNS_StopQuery_internal(mDNS *const m, DNSQuestion *const question)
8540 	{
8541 	const mDNSu32 slot = HashSlot(&question->qname);
8542 	CacheGroup *cg = CacheGroupForName(m, slot, question->qnamehash, &question->qname);
8543 	CacheRecord *rr;
8544 	DNSQuestion **qp = &m->Questions;
8545 
8546 	//LogInfo("mDNS_StopQuery_internal %##s (%s)", question->qname.c, DNSTypeName(question->qtype));
8547 
8548 	if (question->InterfaceID == mDNSInterface_LocalOnly || question->InterfaceID == mDNSInterface_P2P) qp = &m->LocalOnlyQuestions;
8549 	while (*qp && *qp != question) qp=&(*qp)->next;
8550 	if (*qp) *qp = (*qp)->next;
8551 	else
8552 		{
8553 #if !ForceAlerts
8554 		if (question->ThisQInterval >= 0)	// Only log error message if the query was supposed to be active
8555 #endif
8556 			LogMsg("mDNS_StopQuery_internal: Question %##s (%s) not found in active list",
8557 				question->qname.c, DNSTypeName(question->qtype));
8558 #if ForceAlerts
8559 		*(long*)0 = 0;
8560 #endif
8561 		return(mStatus_BadReferenceErr);
8562 		}
8563 
8564 	// Take care to cut question from list *before* calling UpdateQuestionDuplicates
8565 	UpdateQuestionDuplicates(m, question);
8566 	// But don't trash ThisQInterval until afterwards.
8567 	question->ThisQInterval = -1;
8568 
8569 	// If there are any cache records referencing this as their active question, then see if there is any
8570 	// other question that is also referencing them, else their CRActiveQuestion needs to get set to NULL.
8571 	for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next)
8572 		{
8573 		if (rr->CRActiveQuestion == question)
8574 			{
8575 			DNSQuestion *q;
8576 			// Checking for ActiveQuestion filters questions that are suppressed also
8577 			// as suppressed questions are not active
8578 			for (q = m->Questions; q; q=q->next)		// Scan our list of questions
8579 				if (ActiveQuestion(q) && ResourceRecordAnswersQuestion(&rr->resrec, q))
8580 					break;
8581 			if (q)
8582 				debugf("mDNS_StopQuery_internal: Updating CRActiveQuestion to %p for cache record %s, Original question CurrentAnswers %d, new question "
8583 					"CurrentAnswers %d, SuppressQuery %d", q, CRDisplayString(m,rr), question->CurrentAnswers, q->CurrentAnswers, q->SuppressQuery);
8584 			rr->CRActiveQuestion = q;		// Question used to be active; new value may or may not be null
8585 			if (!q) m->rrcache_active--;	// If no longer active, decrement rrcache_active count
8586 			}
8587 		}
8588 
8589 	// If we just deleted the question that CacheRecordAdd() or CacheRecordRmv() is about to look at,
8590 	// bump its pointer forward one question.
8591 	if (m->CurrentQuestion == question)
8592 		{
8593 		debugf("mDNS_StopQuery_internal: Just deleted the currently active question: %##s (%s)",
8594 			question->qname.c, DNSTypeName(question->qtype));
8595 		m->CurrentQuestion = question->next;
8596 		}
8597 
8598 	if (m->NewQuestions == question)
8599 		{
8600 		debugf("mDNS_StopQuery_internal: Just deleted a new question that wasn't even answered yet: %##s (%s)",
8601 			question->qname.c, DNSTypeName(question->qtype));
8602 		m->NewQuestions = question->next;
8603 		}
8604 
8605 	if (m->NewLocalOnlyQuestions == question) m->NewLocalOnlyQuestions = question->next;
8606 
8607 	if (m->RestartQuestion == question)
8608 		{
8609 		LogMsg("mDNS_StopQuery_internal: Just deleted the current restart question: %##s (%s)",
8610 			question->qname.c, DNSTypeName(question->qtype));
8611 		m->RestartQuestion = question->next;
8612 		}
8613 
8614 	// Take care not to trash question->next until *after* we've updated m->CurrentQuestion and m->NewQuestions
8615 	question->next = mDNSNULL;
8616 
8617 	// LogMsg("mDNS_StopQuery_internal: Question %##s (%s) removed", question->qname.c, DNSTypeName(question->qtype));
8618 
8619 	// And finally, cancel any associated GetZoneData operation that's still running.
8620 	// Must not do this until last, because there's a good chance the GetZoneData question is the next in the list,
8621 	// so if we delete it earlier in this routine, we could find that our "question->next" pointer above is already
8622 	// invalid before we even use it. By making sure that we update m->CurrentQuestion and m->NewQuestions if necessary
8623 	// *first*, then they're all ready to be updated a second time if necessary when we cancel our GetZoneData query.
8624 	if (question->tcp) { DisposeTCPConn(question->tcp); question->tcp = mDNSNULL; }
8625 	if (question->LocalSocket) { mDNSPlatformUDPClose(question->LocalSocket); question->LocalSocket = mDNSNULL; }
8626 	if (!mDNSOpaque16IsZero(question->TargetQID) && question->LongLived)
8627 		{
8628 		// Scan our list to see if any more wide-area LLQs remain. If not, stop our NAT Traversal.
8629 		DNSQuestion *q;
8630 		for (q = m->Questions; q; q=q->next)
8631 			if (!mDNSOpaque16IsZero(q->TargetQID) && q->LongLived) break;
8632 		if (!q)
8633 			{
8634 			if (!m->LLQNAT.clientContext)		// Should never happen, but just in case...
8635 				LogMsg("mDNS_StopQuery ERROR LLQNAT.clientContext NULL");
8636 			else
8637 				{
8638 				LogInfo("Stopping LLQNAT");
8639 				mDNS_StopNATOperation_internal(m, &m->LLQNAT);
8640 				m->LLQNAT.clientContext = mDNSNULL; // Means LLQ NAT Traversal not running
8641 				}
8642 			}
8643 
8644 		// If necessary, tell server it can delete this LLQ state
8645 		if (question->state == LLQ_Established)
8646 			{
8647 			question->ReqLease = 0;
8648 			sendLLQRefresh(m, question);
8649 			// If we need need to make a TCP connection to cancel the LLQ, that's going to take a little while.
8650 			// We clear the tcp->question backpointer so that when the TCP connection completes, it doesn't
8651 			// crash trying to access our cancelled question, but we don't cancel the TCP operation itself --
8652 			// we let that run out its natural course and complete asynchronously.
8653 			if (question->tcp)
8654 				{
8655 				question->tcp->question = mDNSNULL;
8656 				question->tcp           = mDNSNULL;
8657 				}
8658 			}
8659 #if APPLE_OSX_mDNSResponder
8660 		UpdateAutoTunnelDomainStatuses(m);
8661 #endif
8662 		}
8663 	// wait until we send the refresh above which needs the nta
8664 	if (question->nta) { CancelGetZoneData(m, question->nta); question->nta = mDNSNULL; }
8665 
8666 	return(mStatus_NoError);
8667 	}
8668 
mDNS_StartQuery(mDNS * const m,DNSQuestion * const question)8669 mDNSexport mStatus mDNS_StartQuery(mDNS *const m, DNSQuestion *const question)
8670 	{
8671 	mStatus status;
8672 	mDNS_Lock(m);
8673 	status = mDNS_StartQuery_internal(m, question);
8674 	mDNS_Unlock(m);
8675 	return(status);
8676 	}
8677 
mDNS_StopQuery(mDNS * const m,DNSQuestion * const question)8678 mDNSexport mStatus mDNS_StopQuery(mDNS *const m, DNSQuestion *const question)
8679 	{
8680 	mStatus status;
8681 	mDNS_Lock(m);
8682 	status = mDNS_StopQuery_internal(m, question);
8683 	mDNS_Unlock(m);
8684 	return(status);
8685 	}
8686 
8687 // Note that mDNS_StopQueryWithRemoves() does not currently implement the full generality of the other APIs
8688 // Specifically, question callbacks invoked as a result of this call cannot themselves make API calls.
8689 // We invoke the callback without using mDNS_DropLockBeforeCallback/mDNS_ReclaimLockAfterCallback
8690 // specifically to catch and report if the client callback does try to make API calls
mDNS_StopQueryWithRemoves(mDNS * const m,DNSQuestion * const question)8691 mDNSexport mStatus mDNS_StopQueryWithRemoves(mDNS *const m, DNSQuestion *const question)
8692 	{
8693 	mStatus status;
8694 	DNSQuestion *qq;
8695 	mDNS_Lock(m);
8696 
8697 	// Check if question is new -- don't want to give remove events for a question we haven't even answered yet
8698 	for (qq = m->NewQuestions; qq; qq=qq->next) if (qq == question) break;
8699 
8700 	status = mDNS_StopQuery_internal(m, question);
8701 	if (status == mStatus_NoError && !qq)
8702 		{
8703 		const CacheRecord *rr;
8704 		const mDNSu32 slot = HashSlot(&question->qname);
8705 		CacheGroup *const cg = CacheGroupForName(m, slot, question->qnamehash, &question->qname);
8706 		LogInfo("Generating terminal removes for %##s (%s)", question->qname.c, DNSTypeName(question->qtype));
8707 		for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next)
8708 			if (rr->resrec.RecordType != kDNSRecordTypePacketNegative && SameNameRecordAnswersQuestion(&rr->resrec, question))
8709 				{
8710 				// Don't use mDNS_DropLockBeforeCallback() here, since we don't allow API calls
8711 				if (question->QuestionCallback)
8712 					question->QuestionCallback(m, question, &rr->resrec, mDNSfalse);
8713 				}
8714 		}
8715 	mDNS_Unlock(m);
8716 	return(status);
8717 	}
8718 
mDNS_Reconfirm(mDNS * const m,CacheRecord * const cr)8719 mDNSexport mStatus mDNS_Reconfirm(mDNS *const m, CacheRecord *const cr)
8720 	{
8721 	mStatus status;
8722 	mDNS_Lock(m);
8723 	status = mDNS_Reconfirm_internal(m, cr, kDefaultReconfirmTimeForNoAnswer);
8724 	if (status == mStatus_NoError) ReconfirmAntecedents(m, cr->resrec.name, cr->resrec.namehash, 0);
8725 	mDNS_Unlock(m);
8726 	return(status);
8727 	}
8728 
mDNS_ReconfirmByValue(mDNS * const m,ResourceRecord * const rr)8729 mDNSexport mStatus mDNS_ReconfirmByValue(mDNS *const m, ResourceRecord *const rr)
8730 	{
8731 	mStatus status = mStatus_BadReferenceErr;
8732 	CacheRecord *cr;
8733 	mDNS_Lock(m);
8734 	cr = FindIdenticalRecordInCache(m, rr);
8735 	debugf("mDNS_ReconfirmByValue: %p %s", cr, RRDisplayString(m, rr));
8736 	if (cr) status = mDNS_Reconfirm_internal(m, cr, kDefaultReconfirmTimeForNoAnswer);
8737 	if (status == mStatus_NoError) ReconfirmAntecedents(m, cr->resrec.name, cr->resrec.namehash, 0);
8738 	mDNS_Unlock(m);
8739 	return(status);
8740 	}
8741 
mDNS_StartBrowse_internal(mDNS * const m,DNSQuestion * const question,const domainname * const srv,const domainname * const domain,const mDNSInterfaceID InterfaceID,mDNSBool ForceMCast,mDNSQuestionCallback * Callback,void * Context)8742 mDNSlocal mStatus mDNS_StartBrowse_internal(mDNS *const m, DNSQuestion *const question,
8743 	const domainname *const srv, const domainname *const domain,
8744 	const mDNSInterfaceID InterfaceID, mDNSBool ForceMCast, mDNSQuestionCallback *Callback, void *Context)
8745 	{
8746 	question->InterfaceID      = InterfaceID;
8747 	question->Target           = zeroAddr;
8748 	question->qtype            = kDNSType_PTR;
8749 	question->qclass           = kDNSClass_IN;
8750 	question->LongLived        = mDNStrue;
8751 	question->ExpectUnique     = mDNSfalse;
8752 	question->ForceMCast       = ForceMCast;
8753 	question->ReturnIntermed   = mDNSfalse;
8754 	question->SuppressUnusable = mDNSfalse;
8755 	question->SearchListIndex  = 0;
8756 	question->AppendSearchDomains = 0;
8757 	question->RetryWithSearchDomains = mDNSfalse;
8758 	question->TimeoutQuestion  = 0;
8759 	question->WakeOnResolve    = 0;
8760 	question->qnameOrig        = mDNSNULL;
8761 	question->QuestionCallback = Callback;
8762 	question->QuestionContext  = Context;
8763 	if (!ConstructServiceName(&question->qname, mDNSNULL, srv, domain)) return(mStatus_BadParamErr);
8764 
8765 	return(mDNS_StartQuery_internal(m, question));
8766 	}
8767 
mDNS_StartBrowse(mDNS * const m,DNSQuestion * const question,const domainname * const srv,const domainname * const domain,const mDNSInterfaceID InterfaceID,mDNSBool ForceMCast,mDNSQuestionCallback * Callback,void * Context)8768 mDNSexport mStatus mDNS_StartBrowse(mDNS *const m, DNSQuestion *const question,
8769 	const domainname *const srv, const domainname *const domain,
8770 	const mDNSInterfaceID InterfaceID, mDNSBool ForceMCast, mDNSQuestionCallback *Callback, void *Context)
8771 	{
8772 	mStatus status;
8773 	mDNS_Lock(m);
8774 	status = mDNS_StartBrowse_internal(m, question, srv, domain, InterfaceID, ForceMCast, Callback, Context);
8775 	mDNS_Unlock(m);
8776 	return(status);
8777 	}
8778 
MachineHasActiveIPv6(mDNS * const m)8779 mDNSlocal mDNSBool MachineHasActiveIPv6(mDNS *const m)
8780 	{
8781 	NetworkInterfaceInfo *intf;
8782 	for (intf = m->HostInterfaces; intf; intf = intf->next)
8783 	if (intf->ip.type == mDNSAddrType_IPv6) return(mDNStrue);
8784 	return(mDNSfalse);
8785 	}
8786 
FoundServiceInfoSRV(mDNS * const m,DNSQuestion * question,const ResourceRecord * const answer,QC_result AddRecord)8787 mDNSlocal void FoundServiceInfoSRV(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord)
8788 	{
8789 	ServiceInfoQuery *query = (ServiceInfoQuery *)question->QuestionContext;
8790 	mDNSBool PortChanged = !mDNSSameIPPort(query->info->port, answer->rdata->u.srv.port);
8791 	if (!AddRecord) return;
8792 	if (answer->rrtype != kDNSType_SRV) return;
8793 
8794 	query->info->port = answer->rdata->u.srv.port;
8795 
8796 	// If this is our first answer, then set the GotSRV flag and start the address query
8797 	if (!query->GotSRV)
8798 		{
8799 		query->GotSRV             = mDNStrue;
8800 		query->qAv4.InterfaceID   = answer->InterfaceID;
8801 		AssignDomainName(&query->qAv4.qname, &answer->rdata->u.srv.target);
8802 		query->qAv6.InterfaceID   = answer->InterfaceID;
8803 		AssignDomainName(&query->qAv6.qname, &answer->rdata->u.srv.target);
8804 		mDNS_StartQuery(m, &query->qAv4);
8805 		// Only do the AAAA query if this machine actually has IPv6 active
8806 		if (MachineHasActiveIPv6(m)) mDNS_StartQuery(m, &query->qAv6);
8807 		}
8808 	// If this is not our first answer, only re-issue the address query if the target host name has changed
8809 	else if ((query->qAv4.InterfaceID != query->qSRV.InterfaceID && query->qAv4.InterfaceID != answer->InterfaceID) ||
8810 		!SameDomainName(&query->qAv4.qname, &answer->rdata->u.srv.target))
8811 		{
8812 		mDNS_StopQuery(m, &query->qAv4);
8813 		if (query->qAv6.ThisQInterval >= 0) mDNS_StopQuery(m, &query->qAv6);
8814 		if (SameDomainName(&query->qAv4.qname, &answer->rdata->u.srv.target) && !PortChanged)
8815 			{
8816 			// If we get here, it means:
8817 			// 1. This is not our first SRV answer
8818 			// 2. The interface ID is different, but the target host and port are the same
8819 			// This implies that we're seeing the exact same SRV record on more than one interface, so we should
8820 			// make our address queries at least as broad as the original SRV query so that we catch all the answers.
8821 			query->qAv4.InterfaceID = query->qSRV.InterfaceID;	// Will be mDNSInterface_Any, or a specific interface
8822 			query->qAv6.InterfaceID = query->qSRV.InterfaceID;
8823 			}
8824 		else
8825 			{
8826 			query->qAv4.InterfaceID   = answer->InterfaceID;
8827 			AssignDomainName(&query->qAv4.qname, &answer->rdata->u.srv.target);
8828 			query->qAv6.InterfaceID   = answer->InterfaceID;
8829 			AssignDomainName(&query->qAv6.qname, &answer->rdata->u.srv.target);
8830 			}
8831 		debugf("FoundServiceInfoSRV: Restarting address queries for %##s (%s)", query->qAv4.qname.c, DNSTypeName(query->qAv4.qtype));
8832 		mDNS_StartQuery(m, &query->qAv4);
8833 		// Only do the AAAA query if this machine actually has IPv6 active
8834 		if (MachineHasActiveIPv6(m)) mDNS_StartQuery(m, &query->qAv6);
8835 		}
8836 	else if (query->ServiceInfoQueryCallback && query->GotADD && query->GotTXT && PortChanged)
8837 		{
8838 		if (++query->Answers >= 100)
8839 			debugf("**** WARNING **** Have given %lu answers for %##s (SRV) %##s %u",
8840 				query->Answers, query->qSRV.qname.c, answer->rdata->u.srv.target.c,
8841 				mDNSVal16(answer->rdata->u.srv.port));
8842 		query->ServiceInfoQueryCallback(m, query);
8843 		}
8844 	// CAUTION: MUST NOT do anything more with query after calling query->Callback(), because the client's
8845 	// callback function is allowed to do anything, including deleting this query and freeing its memory.
8846 	}
8847 
FoundServiceInfoTXT(mDNS * const m,DNSQuestion * question,const ResourceRecord * const answer,QC_result AddRecord)8848 mDNSlocal void FoundServiceInfoTXT(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord)
8849 	{
8850 	ServiceInfoQuery *query = (ServiceInfoQuery *)question->QuestionContext;
8851 	if (!AddRecord) return;
8852 	if (answer->rrtype != kDNSType_TXT) return;
8853 	if (answer->rdlength > sizeof(query->info->TXTinfo)) return;
8854 
8855 	query->GotTXT       = mDNStrue;
8856 	query->info->TXTlen = answer->rdlength;
8857 	query->info->TXTinfo[0] = 0;		// In case answer->rdlength is zero
8858 	mDNSPlatformMemCopy(query->info->TXTinfo, answer->rdata->u.txt.c, answer->rdlength);
8859 
8860 	verbosedebugf("FoundServiceInfoTXT: %##s GotADD=%d", query->info->name.c, query->GotADD);
8861 
8862 	// CAUTION: MUST NOT do anything more with query after calling query->Callback(), because the client's
8863 	// callback function is allowed to do anything, including deleting this query and freeing its memory.
8864 	if (query->ServiceInfoQueryCallback && query->GotADD)
8865 		{
8866 		if (++query->Answers >= 100)
8867 			debugf("**** WARNING **** have given %lu answers for %##s (TXT) %#s...",
8868 				query->Answers, query->qSRV.qname.c, answer->rdata->u.txt.c);
8869 		query->ServiceInfoQueryCallback(m, query);
8870 		}
8871 	}
8872 
FoundServiceInfo(mDNS * const m,DNSQuestion * question,const ResourceRecord * const answer,QC_result AddRecord)8873 mDNSlocal void FoundServiceInfo(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord)
8874 	{
8875 	ServiceInfoQuery *query = (ServiceInfoQuery *)question->QuestionContext;
8876 	//LogInfo("FoundServiceInfo %d %s", AddRecord, RRDisplayString(m, answer));
8877 	if (!AddRecord) return;
8878 
8879 	if (answer->rrtype == kDNSType_A)
8880 		{
8881 		query->info->ip.type = mDNSAddrType_IPv4;
8882 		query->info->ip.ip.v4 = answer->rdata->u.ipv4;
8883 		}
8884 	else if (answer->rrtype == kDNSType_AAAA)
8885 		{
8886 		query->info->ip.type = mDNSAddrType_IPv6;
8887 		query->info->ip.ip.v6 = answer->rdata->u.ipv6;
8888 		}
8889 	else
8890 		{
8891 		debugf("FoundServiceInfo: answer %##s type %d (%s) unexpected", answer->name->c, answer->rrtype, DNSTypeName(answer->rrtype));
8892 		return;
8893 		}
8894 
8895 	query->GotADD = mDNStrue;
8896 	query->info->InterfaceID = answer->InterfaceID;
8897 
8898 	verbosedebugf("FoundServiceInfo v%ld: %##s GotTXT=%d", query->info->ip.type, query->info->name.c, query->GotTXT);
8899 
8900 	// CAUTION: MUST NOT do anything more with query after calling query->Callback(), because the client's
8901 	// callback function is allowed to do anything, including deleting this query and freeing its memory.
8902 	if (query->ServiceInfoQueryCallback && query->GotTXT)
8903 		{
8904 		if (++query->Answers >= 100)
8905 			debugf(answer->rrtype == kDNSType_A ?
8906 				"**** WARNING **** have given %lu answers for %##s (A) %.4a" :
8907 				"**** WARNING **** have given %lu answers for %##s (AAAA) %.16a",
8908 				query->Answers, query->qSRV.qname.c, &answer->rdata->u.data);
8909 		query->ServiceInfoQueryCallback(m, query);
8910 		}
8911 	}
8912 
8913 // On entry, the client must have set the name and InterfaceID fields of the ServiceInfo structure
8914 // If the query is not interface-specific, then InterfaceID may be zero
8915 // Each time the Callback is invoked, the remainder of the fields will have been filled in
8916 // In addition, InterfaceID will be updated to give the interface identifier corresponding to that response
mDNS_StartResolveService(mDNS * const m,ServiceInfoQuery * query,ServiceInfo * info,mDNSServiceInfoQueryCallback * Callback,void * Context)8917 mDNSexport mStatus mDNS_StartResolveService(mDNS *const m,
8918 	ServiceInfoQuery *query, ServiceInfo *info, mDNSServiceInfoQueryCallback *Callback, void *Context)
8919 	{
8920 	mStatus status;
8921 	mDNS_Lock(m);
8922 
8923 	query->qSRV.ThisQInterval       = -1;		// So that mDNS_StopResolveService() knows whether to cancel this question
8924 	query->qSRV.InterfaceID         = info->InterfaceID;
8925 	query->qSRV.Target              = zeroAddr;
8926 	AssignDomainName(&query->qSRV.qname, &info->name);
8927 	query->qSRV.qtype               = kDNSType_SRV;
8928 	query->qSRV.qclass              = kDNSClass_IN;
8929 	query->qSRV.LongLived           = mDNSfalse;
8930 	query->qSRV.ExpectUnique        = mDNStrue;
8931 	query->qSRV.ForceMCast          = mDNSfalse;
8932 	query->qSRV.ReturnIntermed      = mDNSfalse;
8933 	query->qSRV.SuppressUnusable    = mDNSfalse;
8934 	query->qSRV.SearchListIndex     = 0;
8935 	query->qSRV.AppendSearchDomains = 0;
8936 	query->qSRV.RetryWithSearchDomains = mDNSfalse;
8937 	query->qSRV.TimeoutQuestion     = 0;
8938 	query->qSRV.WakeOnResolve       = 0;
8939 	query->qSRV.qnameOrig           = mDNSNULL;
8940 	query->qSRV.QuestionCallback    = FoundServiceInfoSRV;
8941 	query->qSRV.QuestionContext     = query;
8942 
8943 	query->qTXT.ThisQInterval       = -1;		// So that mDNS_StopResolveService() knows whether to cancel this question
8944 	query->qTXT.InterfaceID         = info->InterfaceID;
8945 	query->qTXT.Target              = zeroAddr;
8946 	AssignDomainName(&query->qTXT.qname, &info->name);
8947 	query->qTXT.qtype               = kDNSType_TXT;
8948 	query->qTXT.qclass              = kDNSClass_IN;
8949 	query->qTXT.LongLived           = mDNSfalse;
8950 	query->qTXT.ExpectUnique        = mDNStrue;
8951 	query->qTXT.ForceMCast          = mDNSfalse;
8952 	query->qTXT.ReturnIntermed      = mDNSfalse;
8953 	query->qTXT.SuppressUnusable    = mDNSfalse;
8954 	query->qTXT.SearchListIndex     = 0;
8955 	query->qTXT.AppendSearchDomains = 0;
8956 	query->qTXT.RetryWithSearchDomains = mDNSfalse;
8957 	query->qTXT.TimeoutQuestion     = 0;
8958 	query->qTXT.WakeOnResolve       = 0;
8959 	query->qTXT.qnameOrig           = mDNSNULL;
8960 	query->qTXT.QuestionCallback    = FoundServiceInfoTXT;
8961 	query->qTXT.QuestionContext     = query;
8962 
8963 	query->qAv4.ThisQInterval       = -1;		// So that mDNS_StopResolveService() knows whether to cancel this question
8964 	query->qAv4.InterfaceID         = info->InterfaceID;
8965 	query->qAv4.Target              = zeroAddr;
8966 	query->qAv4.qname.c[0]          = 0;
8967 	query->qAv4.qtype               = kDNSType_A;
8968 	query->qAv4.qclass              = kDNSClass_IN;
8969 	query->qAv4.LongLived           = mDNSfalse;
8970 	query->qAv4.ExpectUnique        = mDNStrue;
8971 	query->qAv4.ForceMCast          = mDNSfalse;
8972 	query->qAv4.ReturnIntermed      = mDNSfalse;
8973 	query->qAv4.SuppressUnusable    = mDNSfalse;
8974 	query->qAv4.SearchListIndex     = 0;
8975 	query->qAv4.AppendSearchDomains = 0;
8976 	query->qAv4.RetryWithSearchDomains = mDNSfalse;
8977 	query->qAv4.TimeoutQuestion     = 0;
8978 	query->qAv4.WakeOnResolve       = 0;
8979 	query->qAv4.qnameOrig           = mDNSNULL;
8980 	query->qAv4.QuestionCallback    = FoundServiceInfo;
8981 	query->qAv4.QuestionContext     = query;
8982 
8983 	query->qAv6.ThisQInterval       = -1;		// So that mDNS_StopResolveService() knows whether to cancel this question
8984 	query->qAv6.InterfaceID         = info->InterfaceID;
8985 	query->qAv6.Target              = zeroAddr;
8986 	query->qAv6.qname.c[0]          = 0;
8987 	query->qAv6.qtype               = kDNSType_AAAA;
8988 	query->qAv6.qclass              = kDNSClass_IN;
8989 	query->qAv6.LongLived           = mDNSfalse;
8990 	query->qAv6.ExpectUnique        = mDNStrue;
8991 	query->qAv6.ForceMCast          = mDNSfalse;
8992 	query->qAv6.ReturnIntermed      = mDNSfalse;
8993 	query->qAv6.SuppressUnusable    = mDNSfalse;
8994 	query->qAv6.SearchListIndex     = 0;
8995 	query->qAv6.AppendSearchDomains = 0;
8996 	query->qAv6.RetryWithSearchDomains = mDNSfalse;
8997 	query->qAv6.TimeoutQuestion     = 0;
8998 	query->qAv6.WakeOnResolve       = 0;
8999 	query->qAv6.qnameOrig           = mDNSNULL;
9000 	query->qAv6.QuestionCallback    = FoundServiceInfo;
9001 	query->qAv6.QuestionContext     = query;
9002 
9003 	query->GotSRV                   = mDNSfalse;
9004 	query->GotTXT                   = mDNSfalse;
9005 	query->GotADD                   = mDNSfalse;
9006 	query->Answers                  = 0;
9007 
9008 	query->info                     = info;
9009 	query->ServiceInfoQueryCallback = Callback;
9010 	query->ServiceInfoQueryContext  = Context;
9011 
9012 //	info->name      = Must already be set up by client
9013 //	info->interface = Must already be set up by client
9014 	info->ip        = zeroAddr;
9015 	info->port      = zeroIPPort;
9016 	info->TXTlen    = 0;
9017 
9018 	// We use mDNS_StartQuery_internal here because we're already holding the lock
9019 	status = mDNS_StartQuery_internal(m, &query->qSRV);
9020 	if (status == mStatus_NoError) status = mDNS_StartQuery_internal(m, &query->qTXT);
9021 	if (status != mStatus_NoError) mDNS_StopResolveService(m, query);
9022 
9023 	mDNS_Unlock(m);
9024 	return(status);
9025 	}
9026 
mDNS_StopResolveService(mDNS * const m,ServiceInfoQuery * q)9027 mDNSexport void    mDNS_StopResolveService (mDNS *const m, ServiceInfoQuery *q)
9028 	{
9029 	mDNS_Lock(m);
9030 	// We use mDNS_StopQuery_internal here because we're already holding the lock
9031 	if (q->qSRV.ThisQInterval >= 0) mDNS_StopQuery_internal(m, &q->qSRV);
9032 	if (q->qTXT.ThisQInterval >= 0) mDNS_StopQuery_internal(m, &q->qTXT);
9033 	if (q->qAv4.ThisQInterval >= 0) mDNS_StopQuery_internal(m, &q->qAv4);
9034 	if (q->qAv6.ThisQInterval >= 0) mDNS_StopQuery_internal(m, &q->qAv6);
9035 	mDNS_Unlock(m);
9036 	}
9037 
mDNS_GetDomains(mDNS * const m,DNSQuestion * const question,mDNS_DomainType DomainType,const domainname * dom,const mDNSInterfaceID InterfaceID,mDNSQuestionCallback * Callback,void * Context)9038 mDNSexport mStatus mDNS_GetDomains(mDNS *const m, DNSQuestion *const question, mDNS_DomainType DomainType, const domainname *dom,
9039 	const mDNSInterfaceID InterfaceID, mDNSQuestionCallback *Callback, void *Context)
9040 	{
9041 	question->InterfaceID      = InterfaceID;
9042 	question->Target           = zeroAddr;
9043 	question->qtype            = kDNSType_PTR;
9044 	question->qclass           = kDNSClass_IN;
9045 	question->LongLived        = mDNSfalse;
9046 	question->ExpectUnique     = mDNSfalse;
9047 	question->ForceMCast       = mDNSfalse;
9048 	question->ReturnIntermed   = mDNSfalse;
9049 	question->SuppressUnusable = mDNSfalse;
9050 	question->SearchListIndex  = 0;
9051 	question->AppendSearchDomains = 0;
9052 	question->RetryWithSearchDomains = mDNSfalse;
9053 	question->TimeoutQuestion  = 0;
9054 	question->WakeOnResolve    = 0;
9055 	question->qnameOrig        = mDNSNULL;
9056 	question->QuestionCallback = Callback;
9057 	question->QuestionContext  = Context;
9058 	if (DomainType > mDNS_DomainTypeMax) return(mStatus_BadParamErr);
9059 	if (!MakeDomainNameFromDNSNameString(&question->qname, mDNS_DomainTypeNames[DomainType])) return(mStatus_BadParamErr);
9060 	if (!dom) dom = &localdomain;
9061 	if (!AppendDomainName(&question->qname, dom)) return(mStatus_BadParamErr);
9062 	return(mDNS_StartQuery(m, question));
9063 	}
9064 
9065 // ***************************************************************************
9066 #if COMPILER_LIKES_PRAGMA_MARK
9067 #pragma mark -
9068 #pragma mark - Responder Functions
9069 #endif
9070 
mDNS_Register(mDNS * const m,AuthRecord * const rr)9071 mDNSexport mStatus mDNS_Register(mDNS *const m, AuthRecord *const rr)
9072 	{
9073 	mStatus status;
9074 	mDNS_Lock(m);
9075 	status = mDNS_Register_internal(m, rr);
9076 	mDNS_Unlock(m);
9077 	return(status);
9078 	}
9079 
mDNS_Update(mDNS * const m,AuthRecord * const rr,mDNSu32 newttl,const mDNSu16 newrdlength,RData * const newrdata,mDNSRecordUpdateCallback * Callback)9080 mDNSexport mStatus mDNS_Update(mDNS *const m, AuthRecord *const rr, mDNSu32 newttl,
9081 	const mDNSu16 newrdlength, RData *const newrdata, mDNSRecordUpdateCallback *Callback)
9082 	{
9083 	if (!ValidateRData(rr->resrec.rrtype, newrdlength, newrdata))
9084 		{
9085 		LogMsg("Attempt to update record with invalid rdata: %s", GetRRDisplayString_rdb(&rr->resrec, &newrdata->u, m->MsgBuffer));
9086 		return(mStatus_Invalid);
9087 		}
9088 
9089 	mDNS_Lock(m);
9090 
9091 	// If TTL is unspecified, leave TTL unchanged
9092 	if (newttl == 0) newttl = rr->resrec.rroriginalttl;
9093 
9094 	// If we already have an update queued up which has not gone through yet, give the client a chance to free that memory
9095 	if (rr->NewRData)
9096 		{
9097 		RData *n = rr->NewRData;
9098 		rr->NewRData = mDNSNULL;							// Clear the NewRData pointer ...
9099 		if (rr->UpdateCallback)
9100 			rr->UpdateCallback(m, rr, n, rr->newrdlength);	// ...and let the client free this memory, if necessary
9101 		}
9102 
9103 	rr->NewRData             = newrdata;
9104 	rr->newrdlength          = newrdlength;
9105 	rr->UpdateCallback       = Callback;
9106 
9107 #ifndef UNICAST_DISABLED
9108 	if (rr->ARType != AuthRecordLocalOnly && rr->ARType != AuthRecordP2P && !IsLocalDomain(rr->resrec.name))
9109 		{
9110 		mStatus status = uDNS_UpdateRecord(m, rr);
9111 		// The caller frees the memory on error, don't retain stale pointers
9112 		if (status != mStatus_NoError) { rr->NewRData = mDNSNULL; rr->newrdlength = 0; }
9113 		mDNS_Unlock(m);
9114 		return(status);
9115 		}
9116 #endif
9117 
9118 	if (RRLocalOnly(rr) || (rr->resrec.rroriginalttl == newttl &&
9119 		rr->resrec.rdlength == newrdlength && mDNSPlatformMemSame(rr->resrec.rdata->u.data, newrdata->u.data, newrdlength)))
9120 		CompleteRDataUpdate(m, rr);
9121 	else
9122 		{
9123 		rr->AnnounceCount = InitialAnnounceCount;
9124 		InitializeLastAPTime(m, rr);
9125 		while (rr->NextUpdateCredit && m->timenow - rr->NextUpdateCredit >= 0) GrantUpdateCredit(rr);
9126 		if (!rr->UpdateBlocked && rr->UpdateCredits) rr->UpdateCredits--;
9127 		if (!rr->NextUpdateCredit) rr->NextUpdateCredit = NonZeroTime(m->timenow + kUpdateCreditRefreshInterval);
9128 		if (rr->AnnounceCount > rr->UpdateCredits + 1) rr->AnnounceCount = (mDNSu8)(rr->UpdateCredits + 1);
9129 		if (rr->UpdateCredits <= 5)
9130 			{
9131 			mDNSu32 delay = 6 - rr->UpdateCredits;		// Delay 1 second, then 2, then 3, etc. up to 6 seconds maximum
9132 			if (!rr->UpdateBlocked) rr->UpdateBlocked = NonZeroTime(m->timenow + (mDNSs32)delay * mDNSPlatformOneSecond);
9133 			rr->ThisAPInterval *= 4;
9134 			rr->LastAPTime = rr->UpdateBlocked - rr->ThisAPInterval;
9135 			LogMsg("Excessive update rate for %##s; delaying announcement by %ld second%s",
9136 				rr->resrec.name->c, delay, delay > 1 ? "s" : "");
9137 			}
9138 		rr->resrec.rroriginalttl = newttl;
9139 		}
9140 
9141 	mDNS_Unlock(m);
9142 	return(mStatus_NoError);
9143 	}
9144 
9145 // Note: mDNS_Deregister calls mDNS_Deregister_internal which can call a user callback, which may change
9146 // the record list and/or question list.
9147 // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this.
mDNS_Deregister(mDNS * const m,AuthRecord * const rr)9148 mDNSexport mStatus mDNS_Deregister(mDNS *const m, AuthRecord *const rr)
9149 	{
9150 	mStatus status;
9151 	mDNS_Lock(m);
9152 	status = mDNS_Deregister_internal(m, rr, mDNS_Dereg_normal);
9153 	mDNS_Unlock(m);
9154 	return(status);
9155 	}
9156 
9157 // Circular reference: AdvertiseInterface references mDNS_HostNameCallback, which calls mDNS_SetFQDN, which call AdvertiseInterface
9158 mDNSlocal void mDNS_HostNameCallback(mDNS *const m, AuthRecord *const rr, mStatus result);
9159 
FindFirstAdvertisedInterface(mDNS * const m)9160 mDNSlocal NetworkInterfaceInfo *FindFirstAdvertisedInterface(mDNS *const m)
9161 	{
9162 	NetworkInterfaceInfo *intf;
9163 	for (intf = m->HostInterfaces; intf; intf = intf->next)
9164 		if (intf->Advertise) break;
9165 	return(intf);
9166 	}
9167 
AdvertiseInterface(mDNS * const m,NetworkInterfaceInfo * set)9168 mDNSlocal void AdvertiseInterface(mDNS *const m, NetworkInterfaceInfo *set)
9169 	{
9170 	char buffer[MAX_REVERSE_MAPPING_NAME];
9171 	NetworkInterfaceInfo *primary = FindFirstAdvertisedInterface(m);
9172 	if (!primary) primary = set; // If no existing advertised interface, this new NetworkInterfaceInfo becomes our new primary
9173 
9174 	// Send dynamic update for non-linklocal IPv4 Addresses
9175 	mDNS_SetupResourceRecord(&set->RR_A,     mDNSNULL, set->InterfaceID, kDNSType_A,     kHostNameTTL, kDNSRecordTypeUnique,      AuthRecordAny, mDNS_HostNameCallback, set);
9176 	mDNS_SetupResourceRecord(&set->RR_PTR,   mDNSNULL, set->InterfaceID, kDNSType_PTR,   kHostNameTTL, kDNSRecordTypeKnownUnique, AuthRecordAny, mDNSNULL, mDNSNULL);
9177 	mDNS_SetupResourceRecord(&set->RR_HINFO, mDNSNULL, set->InterfaceID, kDNSType_HINFO, kHostNameTTL, kDNSRecordTypeUnique,      AuthRecordAny, mDNSNULL, mDNSNULL);
9178 
9179 #if ANSWER_REMOTE_HOSTNAME_QUERIES
9180 	set->RR_A    .AllowRemoteQuery  = mDNStrue;
9181 	set->RR_PTR  .AllowRemoteQuery  = mDNStrue;
9182 	set->RR_HINFO.AllowRemoteQuery  = mDNStrue;
9183 #endif
9184 	// 1. Set up Address record to map from host name ("foo.local.") to IP address
9185 	// 2. Set up reverse-lookup PTR record to map from our address back to our host name
9186 	AssignDomainName(&set->RR_A.namestorage, &m->MulticastHostname);
9187 	if (set->ip.type == mDNSAddrType_IPv4)
9188 		{
9189 		set->RR_A.resrec.rrtype = kDNSType_A;
9190 		set->RR_A.resrec.rdata->u.ipv4 = set->ip.ip.v4;
9191 		// Note: This is reverse order compared to a normal dotted-decimal IP address, so we can't use our customary "%.4a" format code
9192 		mDNS_snprintf(buffer, sizeof(buffer), "%d.%d.%d.%d.in-addr.arpa.",
9193 			set->ip.ip.v4.b[3], set->ip.ip.v4.b[2], set->ip.ip.v4.b[1], set->ip.ip.v4.b[0]);
9194 		}
9195 	else if (set->ip.type == mDNSAddrType_IPv6)
9196 		{
9197 		int i;
9198 		set->RR_A.resrec.rrtype = kDNSType_AAAA;
9199 		set->RR_A.resrec.rdata->u.ipv6 = set->ip.ip.v6;
9200 		for (i = 0; i < 16; i++)
9201 			{
9202 			static const char hexValues[] = "0123456789ABCDEF";
9203 			buffer[i * 4    ] = hexValues[set->ip.ip.v6.b[15 - i] & 0x0F];
9204 			buffer[i * 4 + 1] = '.';
9205 			buffer[i * 4 + 2] = hexValues[set->ip.ip.v6.b[15 - i] >> 4];
9206 			buffer[i * 4 + 3] = '.';
9207 			}
9208 		mDNS_snprintf(&buffer[64], sizeof(buffer)-64, "ip6.arpa.");
9209 		}
9210 
9211 	MakeDomainNameFromDNSNameString(&set->RR_PTR.namestorage, buffer);
9212 	set->RR_PTR.AutoTarget = Target_AutoHost;	// Tell mDNS that the target of this PTR is to be kept in sync with our host name
9213 	set->RR_PTR.ForceMCast = mDNStrue;			// This PTR points to our dot-local name, so don't ever try to write it into a uDNS server
9214 
9215 	set->RR_A.RRSet = &primary->RR_A;			// May refer to self
9216 
9217 	mDNS_Register_internal(m, &set->RR_A);
9218 	mDNS_Register_internal(m, &set->RR_PTR);
9219 
9220 	if (!NO_HINFO && m->HIHardware.c[0] > 0 && m->HISoftware.c[0] > 0 && m->HIHardware.c[0] + m->HISoftware.c[0] <= 254)
9221 		{
9222 		mDNSu8 *p = set->RR_HINFO.resrec.rdata->u.data;
9223 		AssignDomainName(&set->RR_HINFO.namestorage, &m->MulticastHostname);
9224 		set->RR_HINFO.DependentOn = &set->RR_A;
9225 		mDNSPlatformMemCopy(p, &m->HIHardware, 1 + (mDNSu32)m->HIHardware.c[0]);
9226 		p += 1 + (int)p[0];
9227 		mDNSPlatformMemCopy(p, &m->HISoftware, 1 + (mDNSu32)m->HISoftware.c[0]);
9228 		mDNS_Register_internal(m, &set->RR_HINFO);
9229 		}
9230 	else
9231 		{
9232 		debugf("Not creating HINFO record: platform support layer provided no information");
9233 		set->RR_HINFO.resrec.RecordType = kDNSRecordTypeUnregistered;
9234 		}
9235 	}
9236 
DeadvertiseInterface(mDNS * const m,NetworkInterfaceInfo * set)9237 mDNSlocal void DeadvertiseInterface(mDNS *const m, NetworkInterfaceInfo *set)
9238 	{
9239 	NetworkInterfaceInfo *intf;
9240 
9241     // If we still have address records referring to this one, update them
9242 	NetworkInterfaceInfo *primary = FindFirstAdvertisedInterface(m);
9243 	AuthRecord *A = primary ? &primary->RR_A : mDNSNULL;
9244 	for (intf = m->HostInterfaces; intf; intf = intf->next)
9245 		if (intf->RR_A.RRSet == &set->RR_A)
9246 			intf->RR_A.RRSet = A;
9247 
9248 	// Unregister these records.
9249 	// When doing the mDNS_Exit processing, we first call DeadvertiseInterface for each interface, so by the time the platform
9250 	// support layer gets to call mDNS_DeregisterInterface, the address and PTR records have already been deregistered for it.
9251 	// Also, in the event of a name conflict, one or more of our records will have been forcibly deregistered.
9252 	// To avoid unnecessary and misleading warning messages, we check the RecordType before calling mDNS_Deregister_internal().
9253 	if (set->RR_A.    resrec.RecordType) mDNS_Deregister_internal(m, &set->RR_A,     mDNS_Dereg_normal);
9254 	if (set->RR_PTR.  resrec.RecordType) mDNS_Deregister_internal(m, &set->RR_PTR,   mDNS_Dereg_normal);
9255 	if (set->RR_HINFO.resrec.RecordType) mDNS_Deregister_internal(m, &set->RR_HINFO, mDNS_Dereg_normal);
9256 	}
9257 
mDNS_SetFQDN(mDNS * const m)9258 mDNSexport void mDNS_SetFQDN(mDNS *const m)
9259 	{
9260 	domainname newmname;
9261 	NetworkInterfaceInfo *intf;
9262 	AuthRecord *rr;
9263 	newmname.c[0] = 0;
9264 
9265 	if (!AppendDomainLabel(&newmname, &m->hostlabel))  { LogMsg("ERROR: mDNS_SetFQDN: Cannot create MulticastHostname"); return; }
9266 	if (!AppendLiteralLabelString(&newmname, "local")) { LogMsg("ERROR: mDNS_SetFQDN: Cannot create MulticastHostname"); return; }
9267 
9268 	mDNS_Lock(m);
9269 
9270 	if (SameDomainNameCS(&m->MulticastHostname, &newmname)) debugf("mDNS_SetFQDN - hostname unchanged");
9271 	else
9272 		{
9273 		AssignDomainName(&m->MulticastHostname, &newmname);
9274 
9275 		// 1. Stop advertising our address records on all interfaces
9276 		for (intf = m->HostInterfaces; intf; intf = intf->next)
9277 			if (intf->Advertise) DeadvertiseInterface(m, intf);
9278 
9279 		// 2. Start advertising our address records using the new name
9280 		for (intf = m->HostInterfaces; intf; intf = intf->next)
9281 			if (intf->Advertise) AdvertiseInterface(m, intf);
9282 		}
9283 
9284 	// 3. Make sure that any AutoTarget SRV records (and the like) get updated
9285 	for (rr = m->ResourceRecords;  rr; rr=rr->next) if (rr->AutoTarget) SetTargetToHostName(m, rr);
9286 	for (rr = m->DuplicateRecords; rr; rr=rr->next) if (rr->AutoTarget) SetTargetToHostName(m, rr);
9287 
9288 	mDNS_Unlock(m);
9289 	}
9290 
mDNS_HostNameCallback(mDNS * const m,AuthRecord * const rr,mStatus result)9291 mDNSlocal void mDNS_HostNameCallback(mDNS *const m, AuthRecord *const rr, mStatus result)
9292 	{
9293 	(void)rr;	// Unused parameter
9294 
9295 	#if MDNS_DEBUGMSGS
9296 		{
9297 		char *msg = "Unknown result";
9298 		if      (result == mStatus_NoError)      msg = "Name registered";
9299 		else if (result == mStatus_NameConflict) msg = "Name conflict";
9300 		debugf("mDNS_HostNameCallback: %##s (%s) %s (%ld)", rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype), msg, result);
9301 		}
9302 	#endif
9303 
9304 	if (result == mStatus_NoError)
9305 		{
9306 		// Notify the client that the host name is successfully registered
9307 		if (m->MainCallback)
9308 			m->MainCallback(m, mStatus_NoError);
9309 		}
9310 	else if (result == mStatus_NameConflict)
9311 		{
9312 		domainlabel oldlabel = m->hostlabel;
9313 
9314 		// 1. First give the client callback a chance to pick a new name
9315 		if (m->MainCallback)
9316 			m->MainCallback(m, mStatus_NameConflict);
9317 
9318 		// 2. If the client callback didn't do it, add (or increment) an index ourselves
9319 		// This needs to be case-INSENSITIVE compare, because we need to know that the name has been changed so as to
9320 		// remedy the conflict, and a name that differs only in capitalization will just suffer the exact same conflict again.
9321 		if (SameDomainLabel(m->hostlabel.c, oldlabel.c))
9322 			IncrementLabelSuffix(&m->hostlabel, mDNSfalse);
9323 
9324 		// 3. Generate the FQDNs from the hostlabel,
9325 		// and make sure all SRV records, etc., are updated to reference our new hostname
9326 		mDNS_SetFQDN(m);
9327 		LogMsg("Local Hostname %#s.local already in use; will try %#s.local instead", oldlabel.c, m->hostlabel.c);
9328 		}
9329 	else if (result == mStatus_MemFree)
9330 		{
9331 		// .local hostnames do not require goodbyes - we ignore the MemFree (which is sent directly by
9332 		// mDNS_Deregister_internal), and allow the caller to deallocate immediately following mDNS_DeadvertiseInterface
9333 		debugf("mDNS_HostNameCallback: MemFree (ignored)");
9334 		}
9335 	else
9336 		LogMsg("mDNS_HostNameCallback: Unknown error %d for registration of record %s", result,  rr->resrec.name->c);
9337 	}
9338 
UpdateInterfaceProtocols(mDNS * const m,NetworkInterfaceInfo * active)9339 mDNSlocal void UpdateInterfaceProtocols(mDNS *const m, NetworkInterfaceInfo *active)
9340 	{
9341 	NetworkInterfaceInfo *intf;
9342 	active->IPv4Available = mDNSfalse;
9343 	active->IPv6Available = mDNSfalse;
9344 	for (intf = m->HostInterfaces; intf; intf = intf->next)
9345 		if (intf->InterfaceID == active->InterfaceID)
9346 			{
9347 			if (intf->ip.type == mDNSAddrType_IPv4 && intf->McastTxRx) active->IPv4Available = mDNStrue;
9348 			if (intf->ip.type == mDNSAddrType_IPv6 && intf->McastTxRx) active->IPv6Available = mDNStrue;
9349 			}
9350 	}
9351 
RestartRecordGetZoneData(mDNS * const m)9352 mDNSlocal void RestartRecordGetZoneData(mDNS * const m)
9353 	{
9354 	AuthRecord *rr;
9355 	LogInfo("RestartRecordGetZoneData: ResourceRecords");
9356 	for (rr = m->ResourceRecords; rr; rr=rr->next)
9357 		if (AuthRecord_uDNS(rr) && rr->state != regState_NoTarget)
9358 			{
9359 			debugf("RestartRecordGetZoneData: StartGetZoneData for %##s", rr->resrec.name->c);
9360 			// Zero out the updateid so that if we have a pending response from the server, it won't
9361 			// be accepted as a valid response. If we accept the response, we might free the new "nta"
9362 			if (rr->nta) { rr->updateid = zeroID; CancelGetZoneData(m, rr->nta); }
9363 			rr->nta = StartGetZoneData(m, rr->resrec.name, ZoneServiceUpdate, RecordRegistrationGotZoneData, rr);
9364 			}
9365 	}
9366 
InitializeNetWakeState(mDNS * const m,NetworkInterfaceInfo * set)9367 mDNSlocal void InitializeNetWakeState(mDNS *const m, NetworkInterfaceInfo *set)
9368 	{
9369 	int i;
9370 	set->NetWakeBrowse.ThisQInterval = -1;
9371 	for (i=0; i<3; i++)
9372 		{
9373 		set->NetWakeResolve[i].ThisQInterval = -1;
9374 		set->SPSAddr[i].type = mDNSAddrType_None;
9375 		}
9376 	set->NextSPSAttempt     = -1;
9377 	set->NextSPSAttemptTime = m->timenow;
9378 	}
9379 
mDNS_ActivateNetWake_internal(mDNS * const m,NetworkInterfaceInfo * set)9380 mDNSexport void mDNS_ActivateNetWake_internal(mDNS *const m, NetworkInterfaceInfo *set)
9381 	{
9382 	NetworkInterfaceInfo *p = m->HostInterfaces;
9383 	while (p && p != set) p=p->next;
9384 	if (!p) { LogMsg("mDNS_ActivateNetWake_internal: NetworkInterfaceInfo %p not found in active list", set); return; }
9385 
9386 	if (set->InterfaceActive)
9387 		{
9388 		LogSPS("ActivateNetWake for %s (%#a)", set->ifname, &set->ip);
9389 		mDNS_StartBrowse_internal(m, &set->NetWakeBrowse, &SleepProxyServiceType, &localdomain, set->InterfaceID, mDNSfalse, m->SPSBrowseCallback, set);
9390 		}
9391 	}
9392 
mDNS_DeactivateNetWake_internal(mDNS * const m,NetworkInterfaceInfo * set)9393 mDNSexport void mDNS_DeactivateNetWake_internal(mDNS *const m, NetworkInterfaceInfo *set)
9394 	{
9395 	NetworkInterfaceInfo *p = m->HostInterfaces;
9396 	while (p && p != set) p=p->next;
9397 	if (!p) { LogMsg("mDNS_DeactivateNetWake_internal: NetworkInterfaceInfo %p not found in active list", set); return; }
9398 
9399 	if (set->NetWakeBrowse.ThisQInterval >= 0)
9400 		{
9401 		int i;
9402 		LogSPS("DeactivateNetWake for %s (%#a)", set->ifname, &set->ip);
9403 
9404 		// Stop our browse and resolve operations
9405 		mDNS_StopQuery_internal(m, &set->NetWakeBrowse);
9406 		for (i=0; i<3; i++) if (set->NetWakeResolve[i].ThisQInterval >= 0) mDNS_StopQuery_internal(m, &set->NetWakeResolve[i]);
9407 
9408 		// Make special call to the browse callback to let it know it can to remove all records for this interface
9409 		if (m->SPSBrowseCallback)
9410 			{
9411 			mDNS_DropLockBeforeCallback();		// Allow client to legally make mDNS API calls from the callback
9412 			m->SPSBrowseCallback(m, &set->NetWakeBrowse, mDNSNULL, mDNSfalse);
9413 			mDNS_ReclaimLockAfterCallback();	// Decrement mDNS_reentrancy to block mDNS API calls again
9414 			}
9415 
9416 		// Reset our variables back to initial state, so we're ready for when NetWake is turned back on
9417 		// (includes resetting NetWakeBrowse.ThisQInterval back to -1)
9418 		InitializeNetWakeState(m, set);
9419 		}
9420 	}
9421 
mDNS_RegisterInterface(mDNS * const m,NetworkInterfaceInfo * set,mDNSBool flapping)9422 mDNSexport mStatus mDNS_RegisterInterface(mDNS *const m, NetworkInterfaceInfo *set, mDNSBool flapping)
9423 	{
9424 	AuthRecord *rr;
9425 	mDNSBool FirstOfType = mDNStrue;
9426 	NetworkInterfaceInfo **p = &m->HostInterfaces;
9427 
9428 	if (!set->InterfaceID)
9429 		{ LogMsg("mDNS_RegisterInterface: Error! Tried to register a NetworkInterfaceInfo %#a with zero InterfaceID", &set->ip); return(mStatus_Invalid); }
9430 
9431 	if (!mDNSAddressIsValidNonZero(&set->mask))
9432 		{ LogMsg("mDNS_RegisterInterface: Error! Tried to register a NetworkInterfaceInfo %#a with invalid mask %#a", &set->ip, &set->mask); return(mStatus_Invalid); }
9433 
9434 	mDNS_Lock(m);
9435 
9436 	// Assume this interface will be active now, unless we find a duplicate already in the list
9437 	set->InterfaceActive = mDNStrue;
9438 	set->IPv4Available   = (mDNSu8)(set->ip.type == mDNSAddrType_IPv4 && set->McastTxRx);
9439 	set->IPv6Available   = (mDNSu8)(set->ip.type == mDNSAddrType_IPv6 && set->McastTxRx);
9440 
9441 	InitializeNetWakeState(m, set);
9442 
9443 	// Scan list to see if this InterfaceID is already represented
9444 	while (*p)
9445 		{
9446 		if (*p == set)
9447 			{
9448 			LogMsg("mDNS_RegisterInterface: Error! Tried to register a NetworkInterfaceInfo that's already in the list");
9449 			mDNS_Unlock(m);
9450 			return(mStatus_AlreadyRegistered);
9451 			}
9452 
9453 		if ((*p)->InterfaceID == set->InterfaceID)
9454 			{
9455 			// This InterfaceID already represented by a different interface in the list, so mark this instance inactive for now
9456 			set->InterfaceActive = mDNSfalse;
9457 			if (set->ip.type == (*p)->ip.type) FirstOfType = mDNSfalse;
9458 			if (set->ip.type == mDNSAddrType_IPv4 && set->McastTxRx) (*p)->IPv4Available = mDNStrue;
9459 			if (set->ip.type == mDNSAddrType_IPv6 && set->McastTxRx) (*p)->IPv6Available = mDNStrue;
9460 			}
9461 
9462 		p=&(*p)->next;
9463 		}
9464 
9465 	set->next = mDNSNULL;
9466 	*p = set;
9467 
9468 	if (set->Advertise)
9469 		AdvertiseInterface(m, set);
9470 
9471 	LogInfo("mDNS_RegisterInterface: InterfaceID %p %s (%#a) %s", set->InterfaceID, set->ifname, &set->ip,
9472 		set->InterfaceActive ?
9473 			"not represented in list; marking active and retriggering queries" :
9474 			"already represented in list; marking inactive for now");
9475 
9476 	if (set->NetWake) mDNS_ActivateNetWake_internal(m, set);
9477 
9478 	// In early versions of OS X the IPv6 address remains on an interface even when the interface is turned off,
9479 	// giving the false impression that there's an active representative of this interface when there really isn't.
9480 	// Therefore, when registering an interface, we want to re-trigger our questions and re-probe our Resource Records,
9481 	// even if we believe that we previously had an active representative of this interface.
9482 	if (set->McastTxRx && (FirstOfType || set->InterfaceActive))
9483 		{
9484 		DNSQuestion *q;
9485 		// Normally, after an interface comes up, we pause half a second before beginning probing.
9486 		// This is to guard against cases where there's rapid interface changes, where we could be confused by
9487 		// seeing packets we ourselves sent just moments ago (perhaps when this interface had a different address)
9488 		// which are then echoed back after a short delay by some Ethernet switches and some 802.11 base stations.
9489 		// We don't want to do a probe, and then see a stale echo of an announcement we ourselves sent,
9490 		// and think it's a conflicting answer to our probe.
9491 		// In the case of a flapping interface, we pause for five seconds, and reduce the announcement count to one packet.
9492 		const mDNSs32 probedelay  = flapping ? mDNSPlatformOneSecond * 5 : mDNSPlatformOneSecond / 2;
9493 		const mDNSu8  numannounce = flapping ? (mDNSu8)1                 : InitialAnnounceCount;
9494 
9495 		// Use a small amount of randomness:
9496 		// In the case of a network administrator turning on an Ethernet hub so that all the
9497 		// connected machines establish link at exactly the same time, we don't want them all
9498 		// to go and hit the network with identical queries at exactly the same moment.
9499 		// We set a random delay of up to InitialQuestionInterval (1/3 second).
9500 		// We must *never* set m->SuppressSending to more than that (or set it repeatedly in a way
9501 		// that causes mDNSResponder to remain in a prolonged state of SuppressSending, because
9502 		// suppressing packet sending for more than about 1/3 second can cause protocol correctness
9503 		// to start to break down (e.g. we don't answer probes fast enough, and get name conflicts).
9504 		// See <rdar://problem/4073853> mDNS: m->SuppressSending set too enthusiastically
9505 		if (!m->SuppressSending) m->SuppressSending = m->timenow + (mDNSs32)mDNSRandom((mDNSu32)InitialQuestionInterval);
9506 
9507 		if (flapping) LogMsg("mDNS_RegisterInterface: Frequent transitions for interface %s (%#a)", set->ifname, &set->ip);
9508 
9509 		LogInfo("mDNS_RegisterInterface: %s (%#a) probedelay %d", set->ifname, &set->ip, probedelay);
9510 		if (m->SuppressProbes == 0 ||
9511 			m->SuppressProbes - NonZeroTime(m->timenow + probedelay) < 0)
9512 			m->SuppressProbes = NonZeroTime(m->timenow + probedelay);
9513 
9514 		// Include OWNER option in packets for 60 seconds after connecting to the network. Setting
9515 		// it here also handles the wake up case as the network link comes UP after waking causing
9516 		// us to reconnect to the network. If we do this as part of the wake up code, it is possible
9517 		// that the network link comes UP after 60 seconds and we never set the OWNER option
9518 		m->AnnounceOwner = NonZeroTime(m->timenow + 60 * mDNSPlatformOneSecond);
9519 		LogInfo("mDNS_RegisterInterface: Setting AnnounceOwner");
9520 
9521 		for (q = m->Questions; q; q=q->next)								// Scan our list of questions
9522 			if (mDNSOpaque16IsZero(q->TargetQID))
9523 				if (!q->InterfaceID || q->InterfaceID == set->InterfaceID)		// If non-specific Q, or Q on this specific interface,
9524 					{															// then reactivate this question
9525 					// If flapping, delay between first and second queries is nine seconds instead of one second
9526 					mDNSBool dodelay = flapping && (q->FlappingInterface1 == set->InterfaceID || q->FlappingInterface2 == set->InterfaceID);
9527 					mDNSs32 initial  = dodelay ? InitialQuestionInterval * QuestionIntervalStep2 : InitialQuestionInterval;
9528 					mDNSs32 qdelay   = dodelay ? mDNSPlatformOneSecond * 5 : 0;
9529 					if (dodelay) LogInfo("No cache records expired for %##s (%s); okay to delay questions a little", q->qname.c, DNSTypeName(q->qtype));
9530 
9531 					if (!q->ThisQInterval || q->ThisQInterval > initial)
9532 						{
9533 						q->ThisQInterval = initial;
9534 						q->RequestUnicast = 2; // Set to 2 because is decremented once *before* we check it
9535 						}
9536 					q->LastQTime = m->timenow - q->ThisQInterval + qdelay;
9537 					q->RecentAnswerPkts = 0;
9538 					SetNextQueryTime(m,q);
9539 					}
9540 
9541 		// For all our non-specific authoritative resource records (and any dormant records specific to this interface)
9542 		// we now need them to re-probe if necessary, and then re-announce.
9543 		for (rr = m->ResourceRecords; rr; rr=rr->next)
9544 			if (!AuthRecord_uDNS(rr))
9545 				if (!rr->resrec.InterfaceID || rr->resrec.InterfaceID == set->InterfaceID)
9546 					{
9547 					if (rr->resrec.RecordType == kDNSRecordTypeVerified && !rr->DependentOn) rr->resrec.RecordType = kDNSRecordTypeUnique;
9548 					rr->ProbeCount     = DefaultProbeCountForRecordType(rr->resrec.RecordType);
9549 					if (rr->AnnounceCount < numannounce) rr->AnnounceCount  = numannounce;
9550 					rr->SendNSECNow    = mDNSNULL;
9551 					InitializeLastAPTime(m, rr);
9552 					}
9553 		}
9554 
9555 	RestartRecordGetZoneData(m);
9556 
9557 	CheckSuppressUnusableQuestions(m);
9558 
9559 	mDNS_UpdateAllowSleep(m);
9560 
9561 	mDNS_Unlock(m);
9562 	return(mStatus_NoError);
9563 	}
9564 
9565 // Note: mDNS_DeregisterInterface calls mDNS_Deregister_internal which can call a user callback, which may change
9566 // the record list and/or question list.
9567 // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this.
mDNS_DeregisterInterface(mDNS * const m,NetworkInterfaceInfo * set,mDNSBool flapping)9568 mDNSexport void mDNS_DeregisterInterface(mDNS *const m, NetworkInterfaceInfo *set, mDNSBool flapping)
9569 	{
9570 	NetworkInterfaceInfo **p = &m->HostInterfaces;
9571 	mDNSBool revalidate = mDNSfalse;
9572 
9573 	mDNS_Lock(m);
9574 
9575 	// Find this record in our list
9576 	while (*p && *p != set) p=&(*p)->next;
9577 	if (!*p) { debugf("mDNS_DeregisterInterface: NetworkInterfaceInfo not found in list"); mDNS_Unlock(m); return; }
9578 
9579 	mDNS_DeactivateNetWake_internal(m, set);
9580 
9581 	// Unlink this record from our list
9582 	*p = (*p)->next;
9583 	set->next = mDNSNULL;
9584 
9585 	if (!set->InterfaceActive)
9586 		{
9587 		// If this interface not the active member of its set, update the v4/v6Available flags for the active member
9588 		NetworkInterfaceInfo *intf;
9589 		for (intf = m->HostInterfaces; intf; intf = intf->next)
9590 			if (intf->InterfaceActive && intf->InterfaceID == set->InterfaceID)
9591 				UpdateInterfaceProtocols(m, intf);
9592 		}
9593 	else
9594 		{
9595 		NetworkInterfaceInfo *intf = FirstInterfaceForID(m, set->InterfaceID);
9596 		if (intf)
9597 			{
9598 			LogInfo("mDNS_DeregisterInterface: Another representative of InterfaceID %p %s (%#a) exists;"
9599 				" making it active", set->InterfaceID, set->ifname, &set->ip);
9600 			if (intf->InterfaceActive)
9601 				LogMsg("mDNS_DeregisterInterface: ERROR intf->InterfaceActive already set for %s (%#a)", set->ifname, &set->ip);
9602 			intf->InterfaceActive = mDNStrue;
9603 			UpdateInterfaceProtocols(m, intf);
9604 
9605 			if (intf->NetWake) mDNS_ActivateNetWake_internal(m, intf);
9606 
9607 			// See if another representative *of the same type* exists. If not, we mave have gone from
9608 			// dual-stack to v6-only (or v4-only) so we need to reconfirm which records are still valid.
9609 			for (intf = m->HostInterfaces; intf; intf = intf->next)
9610 				if (intf->InterfaceID == set->InterfaceID && intf->ip.type == set->ip.type)
9611 					break;
9612 			if (!intf) revalidate = mDNStrue;
9613 			}
9614 		else
9615 			{
9616 			mDNSu32 slot;
9617 			CacheGroup *cg;
9618 			CacheRecord *rr;
9619 			DNSQuestion *q;
9620 			DNSServer *s;
9621 
9622 			LogInfo("mDNS_DeregisterInterface: Last representative of InterfaceID %p %s (%#a) deregistered;"
9623 				" marking questions etc. dormant", set->InterfaceID, set->ifname, &set->ip);
9624 
9625 			if (set->McastTxRx && flapping)
9626 				LogMsg("DeregisterInterface: Frequent transitions for interface %s (%#a)", set->ifname, &set->ip);
9627 
9628 			// 1. Deactivate any questions specific to this interface, and tag appropriate questions
9629 			// so that mDNS_RegisterInterface() knows how swiftly it needs to reactivate them
9630 			for (q = m->Questions; q; q=q->next)
9631 				{
9632 				if (q->InterfaceID == set->InterfaceID) q->ThisQInterval = 0;
9633 				if (!q->InterfaceID || q->InterfaceID == set->InterfaceID)
9634 					{
9635 					q->FlappingInterface2 = q->FlappingInterface1;
9636 					q->FlappingInterface1 = set->InterfaceID;		// Keep history of the last two interfaces to go away
9637 					}
9638 				}
9639 
9640 			// 2. Flush any cache records received on this interface
9641 			revalidate = mDNSfalse;		// Don't revalidate if we're flushing the records
9642 			FORALL_CACHERECORDS(slot, cg, rr)
9643 				if (rr->resrec.InterfaceID == set->InterfaceID)
9644 					{
9645 					// If this interface is deemed flapping,
9646 					// postpone deleting the cache records in case the interface comes back again
9647 					if (set->McastTxRx && flapping)
9648 						{
9649 						// For a flapping interface we want these record to go away after 30 seconds
9650 						mDNS_Reconfirm_internal(m, rr, kDefaultReconfirmTimeForFlappingInterface);
9651 						// We set UnansweredQueries = MaxUnansweredQueries so we don't waste time doing any queries for them --
9652 						// if the interface does come back, any relevant questions will be reactivated anyway
9653 						rr->UnansweredQueries = MaxUnansweredQueries;
9654 						}
9655 					else
9656 						mDNS_PurgeCacheResourceRecord(m, rr);
9657 					}
9658 
9659 			// 3. Any DNS servers specific to this interface are now unusable
9660 			for (s = m->DNSServers; s; s = s->next)
9661 				if (s->interface == set->InterfaceID)
9662 					{
9663 					s->interface = mDNSInterface_Any;
9664 					s->teststate = DNSServer_Disabled;
9665 					}
9666 			}
9667 		}
9668 
9669 	// If we were advertising on this interface, deregister those address and reverse-lookup records now
9670 	if (set->Advertise) DeadvertiseInterface(m, set);
9671 
9672 	// If we have any cache records received on this interface that went away, then re-verify them.
9673 	// In some versions of OS X the IPv6 address remains on an interface even when the interface is turned off,
9674 	// giving the false impression that there's an active representative of this interface when there really isn't.
9675 	// Don't need to do this when shutting down, because *all* interfaces are about to go away
9676 	if (revalidate && !m->ShutdownTime)
9677 		{
9678 		mDNSu32 slot;
9679 		CacheGroup *cg;
9680 		CacheRecord *rr;
9681 		FORALL_CACHERECORDS(slot, cg, rr)
9682 			if (rr->resrec.InterfaceID == set->InterfaceID)
9683 				mDNS_Reconfirm_internal(m, rr, kDefaultReconfirmTimeForFlappingInterface);
9684 		}
9685 
9686 	CheckSuppressUnusableQuestions(m);
9687 
9688 	mDNS_UpdateAllowSleep(m);
9689 
9690 	mDNS_Unlock(m);
9691 	}
9692 
ServiceCallback(mDNS * const m,AuthRecord * const rr,mStatus result)9693 mDNSlocal void ServiceCallback(mDNS *const m, AuthRecord *const rr, mStatus result)
9694 	{
9695 	ServiceRecordSet *sr = (ServiceRecordSet *)rr->RecordContext;
9696 	(void)m;	// Unused parameter
9697 
9698 	#if MDNS_DEBUGMSGS
9699 		{
9700 		char *msg = "Unknown result";
9701 		if      (result == mStatus_NoError)      msg = "Name Registered";
9702 		else if (result == mStatus_NameConflict) msg = "Name Conflict";
9703 		else if (result == mStatus_MemFree)      msg = "Memory Free";
9704 		debugf("ServiceCallback: %##s (%s) %s (%d)", rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype), msg, result);
9705 		}
9706 	#endif
9707 
9708 	// Only pass on the NoError acknowledgement for the SRV record (when it finishes probing)
9709 	if (result == mStatus_NoError && rr != &sr->RR_SRV) return;
9710 
9711 	// If we got a name conflict on either SRV or TXT, forcibly deregister this service, and record that we did that
9712 	if (result == mStatus_NameConflict)
9713 		{
9714 		sr->Conflict = mDNStrue;				// Record that this service set had a conflict
9715 		mDNS_DeregisterService(m, sr);			// Unlink the records from our list
9716 		return;
9717 		}
9718 
9719 	if (result == mStatus_MemFree)
9720 		{
9721 		// If the SRV/TXT/PTR records, or the _services._dns-sd._udp record, or any of the subtype PTR records,
9722 		// are still in the process of deregistering, don't pass on the NameConflict/MemFree message until
9723 		// every record is finished cleaning up.
9724 		mDNSu32 i;
9725 		ExtraResourceRecord *e = sr->Extras;
9726 
9727 		if (sr->RR_SRV.resrec.RecordType != kDNSRecordTypeUnregistered) return;
9728 		if (sr->RR_TXT.resrec.RecordType != kDNSRecordTypeUnregistered) return;
9729 		if (sr->RR_PTR.resrec.RecordType != kDNSRecordTypeUnregistered) return;
9730 		if (sr->RR_ADV.resrec.RecordType != kDNSRecordTypeUnregistered) return;
9731 		for (i=0; i<sr->NumSubTypes; i++) if (sr->SubTypes[i].resrec.RecordType != kDNSRecordTypeUnregistered) return;
9732 
9733 		while (e)
9734 			{
9735 			if (e->r.resrec.RecordType != kDNSRecordTypeUnregistered) return;
9736 			e = e->next;
9737 			}
9738 
9739 		// If this ServiceRecordSet was forcibly deregistered, and now its memory is ready for reuse,
9740 		// then we can now report the NameConflict to the client
9741 		if (sr->Conflict) result = mStatus_NameConflict;
9742 
9743 		}
9744 
9745 	LogInfo("ServiceCallback: All records %s for %##s", (result == mStatus_MemFree ? "Unregistered": "Registered"), sr->RR_PTR.resrec.name->c);
9746 	// CAUTION: MUST NOT do anything more with sr after calling sr->Callback(), because the client's callback
9747 	// function is allowed to do anything, including deregistering this service and freeing its memory.
9748 	if (sr->ServiceCallback)
9749 		sr->ServiceCallback(m, sr, result);
9750 	}
9751 
NSSCallback(mDNS * const m,AuthRecord * const rr,mStatus result)9752 mDNSlocal void NSSCallback(mDNS *const m, AuthRecord *const rr, mStatus result)
9753 	{
9754 	ServiceRecordSet *sr = (ServiceRecordSet *)rr->RecordContext;
9755 	if (sr->ServiceCallback)
9756 		sr->ServiceCallback(m, sr, result);
9757 	}
9758 
9759 // Note:
9760 // Name is first label of domain name (any dots in the name are actual dots, not label separators)
9761 // Type is service type (e.g. "_ipp._tcp.")
9762 // Domain is fully qualified domain name (i.e. ending with a null label)
9763 // We always register a TXT, even if it is empty (so that clients are not
9764 // left waiting forever looking for a nonexistent record.)
9765 // If the host parameter is mDNSNULL or the root domain (ASCII NUL),
9766 // then the default host name (m->MulticastHostname) is automatically used
9767 // If the optional target host parameter is set, then the storage it points to must remain valid for the lifetime of the service registration
mDNS_RegisterService(mDNS * const m,ServiceRecordSet * sr,const domainlabel * const name,const domainname * const type,const domainname * const domain,const domainname * const host,mDNSIPPort port,const mDNSu8 txtinfo[],mDNSu16 txtlen,AuthRecord * SubTypes,mDNSu32 NumSubTypes,mDNSInterfaceID InterfaceID,mDNSServiceCallback Callback,void * Context,mDNSu32 flags)9768 mDNSexport mStatus mDNS_RegisterService(mDNS *const m, ServiceRecordSet *sr,
9769 	const domainlabel *const name, const domainname *const type, const domainname *const domain,
9770 	const domainname *const host, mDNSIPPort port, const mDNSu8 txtinfo[], mDNSu16 txtlen,
9771 	AuthRecord *SubTypes, mDNSu32 NumSubTypes,
9772 	mDNSInterfaceID InterfaceID, mDNSServiceCallback Callback, void *Context, mDNSu32 flags)
9773 	{
9774 	mStatus err;
9775 	mDNSu32 i;
9776 	mDNSu32 hostTTL;
9777 	AuthRecType artype;
9778 	mDNSu8 recordType = (flags & regFlagKnownUnique) ? kDNSRecordTypeKnownUnique : kDNSRecordTypeUnique;
9779 
9780 	sr->ServiceCallback = Callback;
9781 	sr->ServiceContext  = Context;
9782 	sr->Conflict        = mDNSfalse;
9783 
9784 	sr->Extras          = mDNSNULL;
9785 	sr->NumSubTypes     = NumSubTypes;
9786 	sr->SubTypes        = SubTypes;
9787 
9788 	if (InterfaceID == mDNSInterface_LocalOnly)
9789 		artype = AuthRecordLocalOnly;
9790 	else if (InterfaceID == mDNSInterface_P2P)
9791 		artype = AuthRecordP2P;
9792 	else if ((InterfaceID == mDNSInterface_Any) && (flags & regFlagIncludeP2P))
9793 		artype = AuthRecordAnyIncludeP2P;
9794 	else
9795 		artype = AuthRecordAny;
9796 
9797 	// Initialize the AuthRecord objects to sane values
9798 	// Need to initialize everything correctly *before* making the decision whether to do a RegisterNoSuchService and bail out
9799 	mDNS_SetupResourceRecord(&sr->RR_ADV, mDNSNULL, InterfaceID, kDNSType_PTR, kStandardTTL, kDNSRecordTypeAdvisory, artype, ServiceCallback, sr);
9800 	mDNS_SetupResourceRecord(&sr->RR_PTR, mDNSNULL, InterfaceID, kDNSType_PTR, kStandardTTL, kDNSRecordTypeShared,   artype, ServiceCallback, sr);
9801 
9802 	if (SameDomainName(type, (const domainname *) "\x4" "_ubd" "\x4" "_tcp"))
9803 		hostTTL = kHostNameSmallTTL;
9804 	else
9805 		hostTTL = kHostNameTTL;
9806 
9807 	mDNS_SetupResourceRecord(&sr->RR_SRV, mDNSNULL, InterfaceID, kDNSType_SRV, hostTTL, recordType, artype, ServiceCallback, sr);
9808 	mDNS_SetupResourceRecord(&sr->RR_TXT, mDNSNULL, InterfaceID, kDNSType_TXT, kStandardTTL, kDNSRecordTypeUnique, artype, ServiceCallback, sr);
9809 
9810 	// If port number is zero, that means the client is really trying to do a RegisterNoSuchService
9811 	if (mDNSIPPortIsZero(port))
9812 		return(mDNS_RegisterNoSuchService(m, &sr->RR_SRV, name, type, domain, mDNSNULL, InterfaceID, NSSCallback, sr, (flags & regFlagIncludeP2P)));
9813 
9814 	// If the client is registering an oversized TXT record,
9815 	// it is the client's responsibility to alloate a ServiceRecordSet structure that is large enough for it
9816 	if (sr->RR_TXT.resrec.rdata->MaxRDLength < txtlen)
9817 		sr->RR_TXT.resrec.rdata->MaxRDLength = txtlen;
9818 
9819 	// Set up the record names
9820 	// For now we only create an advisory record for the main type, not for subtypes
9821 	// We need to gain some operational experience before we decide if there's a need to create them for subtypes too
9822 	if (ConstructServiceName(&sr->RR_ADV.namestorage, (const domainlabel*)"\x09_services", (const domainname*)"\x07_dns-sd\x04_udp", domain) == mDNSNULL)
9823 		return(mStatus_BadParamErr);
9824 	if (ConstructServiceName(&sr->RR_PTR.namestorage, mDNSNULL, type, domain) == mDNSNULL) return(mStatus_BadParamErr);
9825 	if (ConstructServiceName(&sr->RR_SRV.namestorage, name,     type, domain) == mDNSNULL) return(mStatus_BadParamErr);
9826 	AssignDomainName(&sr->RR_TXT.namestorage, sr->RR_SRV.resrec.name);
9827 
9828 	// 1. Set up the ADV record rdata to advertise our service type
9829 	AssignDomainName(&sr->RR_ADV.resrec.rdata->u.name, sr->RR_PTR.resrec.name);
9830 
9831 	// 2. Set up the PTR record rdata to point to our service name
9832 	// We set up two additionals, so when a client asks for this PTR we automatically send the SRV and the TXT too
9833 	// Note: uDNS registration code assumes that Additional1 points to the SRV record
9834 	AssignDomainName(&sr->RR_PTR.resrec.rdata->u.name, sr->RR_SRV.resrec.name);
9835 	sr->RR_PTR.Additional1 = &sr->RR_SRV;
9836 	sr->RR_PTR.Additional2 = &sr->RR_TXT;
9837 
9838 	// 2a. Set up any subtype PTRs to point to our service name
9839 	// If the client is using subtypes, it is the client's responsibility to have
9840 	// already set the first label of the record name to the subtype being registered
9841 	for (i=0; i<NumSubTypes; i++)
9842 		{
9843 		domainname st;
9844 		AssignDomainName(&st, sr->SubTypes[i].resrec.name);
9845 		st.c[1+st.c[0]] = 0;			// Only want the first label, not the whole FQDN (particularly for mDNS_RenameAndReregisterService())
9846 		AppendDomainName(&st, type);
9847 		mDNS_SetupResourceRecord(&sr->SubTypes[i], mDNSNULL, InterfaceID, kDNSType_PTR, kStandardTTL, kDNSRecordTypeShared, artype, ServiceCallback, sr);
9848 		if (ConstructServiceName(&sr->SubTypes[i].namestorage, mDNSNULL, &st, domain) == mDNSNULL) return(mStatus_BadParamErr);
9849 		AssignDomainName(&sr->SubTypes[i].resrec.rdata->u.name, &sr->RR_SRV.namestorage);
9850 		sr->SubTypes[i].Additional1 = &sr->RR_SRV;
9851 		sr->SubTypes[i].Additional2 = &sr->RR_TXT;
9852 		}
9853 
9854 	// 3. Set up the SRV record rdata.
9855 	sr->RR_SRV.resrec.rdata->u.srv.priority = 0;
9856 	sr->RR_SRV.resrec.rdata->u.srv.weight   = 0;
9857 	sr->RR_SRV.resrec.rdata->u.srv.port     = port;
9858 
9859 	// Setting AutoTarget tells DNS that the target of this SRV is to be automatically kept in sync with our host name
9860 	if (host && host->c[0]) AssignDomainName(&sr->RR_SRV.resrec.rdata->u.srv.target, host);
9861 	else { sr->RR_SRV.AutoTarget = Target_AutoHost; sr->RR_SRV.resrec.rdata->u.srv.target.c[0] = '\0'; }
9862 
9863 	// 4. Set up the TXT record rdata,
9864 	// and set DependentOn because we're depending on the SRV record to find and resolve conflicts for us
9865 	// Note: uDNS registration code assumes that DependentOn points to the SRV record
9866 	if (txtinfo == mDNSNULL) sr->RR_TXT.resrec.rdlength = 0;
9867 	else if (txtinfo != sr->RR_TXT.resrec.rdata->u.txt.c)
9868 		{
9869 		sr->RR_TXT.resrec.rdlength = txtlen;
9870 		if (sr->RR_TXT.resrec.rdlength > sr->RR_TXT.resrec.rdata->MaxRDLength) return(mStatus_BadParamErr);
9871 		mDNSPlatformMemCopy(sr->RR_TXT.resrec.rdata->u.txt.c, txtinfo, txtlen);
9872 		}
9873 	sr->RR_TXT.DependentOn = &sr->RR_SRV;
9874 
9875 	mDNS_Lock(m);
9876 	// It is important that we register SRV first. uDNS assumes that SRV is registered first so
9877 	// that if the SRV cannot find a target, rest of the records that belong to this service
9878 	// will not be activated.
9879 	err = mDNS_Register_internal(m, &sr->RR_SRV);
9880 	// If we can't register the SRV record due to errors, bail out. It has not been inserted in
9881 	// any list and hence no need to deregister. We could probably do similar checks for other
9882 	// records below and bail out. For now, this seems to be sufficient to address rdar://9304275
9883 	if (err)
9884 		{
9885 		mDNS_Unlock(m);
9886 		return err;
9887 		}
9888 	if (!err) err = mDNS_Register_internal(m, &sr->RR_TXT);
9889 	// We register the RR_PTR last, because we want to be sure that in the event of a forced call to
9890 	// mDNS_StartExit, the RR_PTR will be the last one to be forcibly deregistered, since that is what triggers
9891 	// the mStatus_MemFree callback to ServiceCallback, which in turn passes on the mStatus_MemFree back to
9892 	// the client callback, which is then at liberty to free the ServiceRecordSet memory at will. We need to
9893 	// make sure we've deregistered all our records and done any other necessary cleanup before that happens.
9894 	if (!err) err = mDNS_Register_internal(m, &sr->RR_ADV);
9895 	for (i=0; i<NumSubTypes; i++) if (!err) err = mDNS_Register_internal(m, &sr->SubTypes[i]);
9896 	if (!err) err = mDNS_Register_internal(m, &sr->RR_PTR);
9897 
9898 	mDNS_Unlock(m);
9899 
9900 	if (err) mDNS_DeregisterService(m, sr);
9901 	return(err);
9902 	}
9903 
mDNS_AddRecordToService(mDNS * const m,ServiceRecordSet * sr,ExtraResourceRecord * extra,RData * rdata,mDNSu32 ttl,mDNSu32 includeP2P)9904 mDNSexport mStatus mDNS_AddRecordToService(mDNS *const m, ServiceRecordSet *sr,
9905 	ExtraResourceRecord *extra, RData *rdata, mDNSu32 ttl,  mDNSu32 includeP2P)
9906 	{
9907 	ExtraResourceRecord **e;
9908 	mStatus status;
9909 	AuthRecType artype;
9910 	mDNSInterfaceID InterfaceID = sr->RR_PTR.resrec.InterfaceID;
9911 
9912 	if (InterfaceID == mDNSInterface_LocalOnly)
9913 		artype = AuthRecordLocalOnly;
9914 	if (InterfaceID == mDNSInterface_P2P)
9915 		artype = AuthRecordP2P;
9916 	else if ((InterfaceID == mDNSInterface_Any) && includeP2P)
9917 		artype = AuthRecordAnyIncludeP2P;
9918 	else
9919 		artype = AuthRecordAny;
9920 
9921 	extra->next = mDNSNULL;
9922 	mDNS_SetupResourceRecord(&extra->r, rdata, sr->RR_PTR.resrec.InterfaceID,
9923 		extra->r.resrec.rrtype, ttl, kDNSRecordTypeUnique, artype, ServiceCallback, sr);
9924 	AssignDomainName(&extra->r.namestorage, sr->RR_SRV.resrec.name);
9925 
9926 	mDNS_Lock(m);
9927 	e = &sr->Extras;
9928 	while (*e) e = &(*e)->next;
9929 
9930 	if (ttl == 0) ttl = kStandardTTL;
9931 
9932 	extra->r.DependentOn = &sr->RR_SRV;
9933 
9934 	debugf("mDNS_AddRecordToService adding record to %##s %s %d",
9935 		extra->r.resrec.name->c, DNSTypeName(extra->r.resrec.rrtype), extra->r.resrec.rdlength);
9936 
9937 	status = mDNS_Register_internal(m, &extra->r);
9938 	if (status == mStatus_NoError) *e = extra;
9939 
9940 	mDNS_Unlock(m);
9941 	return(status);
9942 	}
9943 
mDNS_RemoveRecordFromService(mDNS * const m,ServiceRecordSet * sr,ExtraResourceRecord * extra,mDNSRecordCallback MemFreeCallback,void * Context)9944 mDNSexport mStatus mDNS_RemoveRecordFromService(mDNS *const m, ServiceRecordSet *sr, ExtraResourceRecord *extra,
9945 	mDNSRecordCallback MemFreeCallback, void *Context)
9946 	{
9947 	ExtraResourceRecord **e;
9948 	mStatus status;
9949 
9950 	mDNS_Lock(m);
9951 	e = &sr->Extras;
9952 	while (*e && *e != extra) e = &(*e)->next;
9953 	if (!*e)
9954 		{
9955 		debugf("mDNS_RemoveRecordFromService failed to remove record from %##s", extra->r.resrec.name->c);
9956 		status = mStatus_BadReferenceErr;
9957 		}
9958 	else
9959 		{
9960 		debugf("mDNS_RemoveRecordFromService removing record from %##s", extra->r.resrec.name->c);
9961 		extra->r.RecordCallback = MemFreeCallback;
9962 		extra->r.RecordContext  = Context;
9963 		*e = (*e)->next;
9964 		status = mDNS_Deregister_internal(m, &extra->r, mDNS_Dereg_normal);
9965 		}
9966 	mDNS_Unlock(m);
9967 	return(status);
9968 	}
9969 
mDNS_RenameAndReregisterService(mDNS * const m,ServiceRecordSet * const sr,const domainlabel * newname)9970 mDNSexport mStatus mDNS_RenameAndReregisterService(mDNS *const m, ServiceRecordSet *const sr, const domainlabel *newname)
9971 	{
9972 	// Note: Don't need to use mDNS_Lock(m) here, because this code is just using public routines
9973 	// mDNS_RegisterService() and mDNS_AddRecordToService(), which do the right locking internally.
9974 	domainlabel name1, name2;
9975 	domainname type, domain;
9976 	const domainname *host = sr->RR_SRV.AutoTarget ? mDNSNULL : &sr->RR_SRV.resrec.rdata->u.srv.target;
9977 	ExtraResourceRecord *extras = sr->Extras;
9978 	mStatus err;
9979 
9980 	DeconstructServiceName(sr->RR_SRV.resrec.name, &name1, &type, &domain);
9981 	if (!newname)
9982 		{
9983 		name2 = name1;
9984 		IncrementLabelSuffix(&name2, mDNStrue);
9985 		newname = &name2;
9986 		}
9987 
9988 	if (SameDomainName(&domain, &localdomain))
9989 		debugf("%##s service renamed from \"%#s\" to \"%#s\"", type.c, name1.c, newname->c);
9990 	else debugf("%##s service (domain %##s) renamed from \"%#s\" to \"%#s\"",type.c, domain.c, name1.c, newname->c);
9991 
9992 	err = mDNS_RegisterService(m, sr, newname, &type, &domain,
9993 		host, sr->RR_SRV.resrec.rdata->u.srv.port, sr->RR_TXT.resrec.rdata->u.txt.c, sr->RR_TXT.resrec.rdlength,
9994 		sr->SubTypes, sr->NumSubTypes,
9995 		sr->RR_PTR.resrec.InterfaceID, sr->ServiceCallback, sr->ServiceContext, 0);
9996 
9997 	// mDNS_RegisterService() just reset sr->Extras to NULL.
9998 	// Fortunately we already grabbed ourselves a copy of this pointer (above), so we can now run
9999 	// through the old list of extra records, and re-add them to our freshly created service registration
10000 	while (!err && extras)
10001 		{
10002 		ExtraResourceRecord *e = extras;
10003 		extras = extras->next;
10004 		err = mDNS_AddRecordToService(m, sr, e, e->r.resrec.rdata, e->r.resrec.rroriginalttl, 0);
10005 		}
10006 
10007 	return(err);
10008 	}
10009 
10010 // Note: mDNS_DeregisterService calls mDNS_Deregister_internal which can call a user callback,
10011 // which may change the record list and/or question list.
10012 // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this.
mDNS_DeregisterService_drt(mDNS * const m,ServiceRecordSet * sr,mDNS_Dereg_type drt)10013 mDNSexport mStatus mDNS_DeregisterService_drt(mDNS *const m, ServiceRecordSet *sr, mDNS_Dereg_type drt)
10014 	{
10015 	// If port number is zero, that means this was actually registered using mDNS_RegisterNoSuchService()
10016 	if (mDNSIPPortIsZero(sr->RR_SRV.resrec.rdata->u.srv.port)) return(mDNS_DeregisterNoSuchService(m, &sr->RR_SRV));
10017 
10018 	if (sr->RR_PTR.resrec.RecordType == kDNSRecordTypeUnregistered)
10019 		{
10020 		debugf("Service set for %##s already deregistered", sr->RR_SRV.resrec.name->c);
10021 		return(mStatus_BadReferenceErr);
10022 		}
10023 	else if (sr->RR_PTR.resrec.RecordType == kDNSRecordTypeDeregistering)
10024 		{
10025 		LogInfo("Service set for %##s already in the process of deregistering", sr->RR_SRV.resrec.name->c);
10026 		// Avoid race condition:
10027 		// If a service gets a conflict, then we set the Conflict flag to tell us to generate
10028 		// an mStatus_NameConflict message when we get the mStatus_MemFree for our PTR record.
10029 		// If the client happens to deregister the service in the middle of that process, then
10030 		// we clear the flag back to the normal state, so that we deliver a plain mStatus_MemFree
10031 		// instead of incorrectly promoting it to mStatus_NameConflict.
10032 		// This race condition is exposed particularly when the conformance test generates
10033 		// a whole batch of simultaneous conflicts across a range of services all advertised
10034 		// using the same system default name, and if we don't take this precaution then
10035 		// we end up incrementing m->nicelabel multiple times instead of just once.
10036 		// <rdar://problem/4060169> Bug when auto-renaming Computer Name after name collision
10037 		sr->Conflict = mDNSfalse;
10038 		return(mStatus_NoError);
10039 		}
10040 	else
10041 		{
10042 		mDNSu32 i;
10043 		mStatus status;
10044 		ExtraResourceRecord *e;
10045 		mDNS_Lock(m);
10046 		e = sr->Extras;
10047 
10048 		// We use mDNS_Dereg_repeat because, in the event of a collision, some or all of the
10049 		// SRV, TXT, or Extra records could have already been automatically deregistered, and that's okay
10050 		mDNS_Deregister_internal(m, &sr->RR_SRV, mDNS_Dereg_repeat);
10051 		mDNS_Deregister_internal(m, &sr->RR_TXT, mDNS_Dereg_repeat);
10052 
10053 		mDNS_Deregister_internal(m, &sr->RR_ADV, drt);
10054 
10055 		// We deregister all of the extra records, but we leave the sr->Extras list intact
10056 		// in case the client wants to do a RenameAndReregister and reinstate the registration
10057 		while (e)
10058 			{
10059 			mDNS_Deregister_internal(m, &e->r, mDNS_Dereg_repeat);
10060 			e = e->next;
10061 			}
10062 
10063 		for (i=0; i<sr->NumSubTypes; i++)
10064 			mDNS_Deregister_internal(m, &sr->SubTypes[i], drt);
10065 
10066 		status = mDNS_Deregister_internal(m, &sr->RR_PTR, drt);
10067 		mDNS_Unlock(m);
10068 		return(status);
10069 		}
10070 	}
10071 
10072 // Create a registration that asserts that no such service exists with this name.
10073 // This can be useful where there is a given function is available through several protocols.
10074 // For example, a printer called "Stuart's Printer" may implement printing via the "pdl-datastream" and "IPP"
10075 // protocols, but not via "LPR". In this case it would be prudent for the printer to assert the non-existence of an
10076 // "LPR" service called "Stuart's Printer". Without this precaution, another printer than offers only "LPR" printing
10077 // could inadvertently advertise its service under the same name "Stuart's Printer", which might be confusing for users.
mDNS_RegisterNoSuchService(mDNS * const m,AuthRecord * const rr,const domainlabel * const name,const domainname * const type,const domainname * const domain,const domainname * const host,const mDNSInterfaceID InterfaceID,mDNSRecordCallback Callback,void * Context,mDNSBool includeP2P)10078 mDNSexport mStatus mDNS_RegisterNoSuchService(mDNS *const m, AuthRecord *const rr,
10079 	const domainlabel *const name, const domainname *const type, const domainname *const domain,
10080 	const domainname *const host,
10081 	const mDNSInterfaceID InterfaceID, mDNSRecordCallback Callback, void *Context, mDNSBool includeP2P)
10082 	{
10083 	AuthRecType artype;
10084 
10085 	if (InterfaceID == mDNSInterface_LocalOnly)
10086 		artype = AuthRecordLocalOnly;
10087 	else if (InterfaceID == mDNSInterface_P2P)
10088 		artype = AuthRecordP2P;
10089 	else if ((InterfaceID == mDNSInterface_Any) && includeP2P)
10090 		artype = AuthRecordAnyIncludeP2P;
10091 	else
10092 		artype = AuthRecordAny;
10093 
10094 	mDNS_SetupResourceRecord(rr, mDNSNULL, InterfaceID, kDNSType_SRV, kHostNameTTL, kDNSRecordTypeUnique, artype, Callback, Context);
10095 	if (ConstructServiceName(&rr->namestorage, name, type, domain) == mDNSNULL) return(mStatus_BadParamErr);
10096 	rr->resrec.rdata->u.srv.priority    = 0;
10097 	rr->resrec.rdata->u.srv.weight      = 0;
10098 	rr->resrec.rdata->u.srv.port        = zeroIPPort;
10099 	if (host && host->c[0]) AssignDomainName(&rr->resrec.rdata->u.srv.target, host);
10100 	else rr->AutoTarget = Target_AutoHost;
10101 	return(mDNS_Register(m, rr));
10102 	}
10103 
mDNS_AdvertiseDomains(mDNS * const m,AuthRecord * rr,mDNS_DomainType DomainType,const mDNSInterfaceID InterfaceID,char * domname)10104 mDNSexport mStatus mDNS_AdvertiseDomains(mDNS *const m, AuthRecord *rr,
10105 	mDNS_DomainType DomainType, const mDNSInterfaceID InterfaceID, char *domname)
10106 	{
10107 	AuthRecType artype;
10108 
10109 	if (InterfaceID == mDNSInterface_LocalOnly)
10110 		artype = AuthRecordLocalOnly;
10111 	else if (InterfaceID == mDNSInterface_P2P)
10112 		artype = AuthRecordP2P;
10113 	else
10114 		artype = AuthRecordAny;
10115 	mDNS_SetupResourceRecord(rr, mDNSNULL, InterfaceID, kDNSType_PTR, kStandardTTL, kDNSRecordTypeShared, artype, mDNSNULL, mDNSNULL);
10116 	if (!MakeDomainNameFromDNSNameString(&rr->namestorage, mDNS_DomainTypeNames[DomainType])) return(mStatus_BadParamErr);
10117 	if (!MakeDomainNameFromDNSNameString(&rr->resrec.rdata->u.name, domname))                 return(mStatus_BadParamErr);
10118 	return(mDNS_Register(m, rr));
10119 	}
10120 
mDNS_IdUsedInResourceRecordsList(mDNS * const m,mDNSOpaque16 id)10121 mDNSlocal mDNSBool mDNS_IdUsedInResourceRecordsList(mDNS * const m, mDNSOpaque16 id)
10122 	{
10123 	AuthRecord *r;
10124 	for (r = m->ResourceRecords; r; r=r->next) if (mDNSSameOpaque16(id, r->updateid)) return mDNStrue;
10125 	return mDNSfalse;
10126 	}
10127 
mDNS_IdUsedInQuestionsList(mDNS * const m,mDNSOpaque16 id)10128 mDNSlocal mDNSBool mDNS_IdUsedInQuestionsList(mDNS * const m, mDNSOpaque16 id)
10129 	{
10130 	DNSQuestion *q;
10131 	for (q = m->Questions; q; q=q->next) if (mDNSSameOpaque16(id, q->TargetQID)) return mDNStrue;
10132 	return mDNSfalse;
10133 	}
10134 
mDNS_NewMessageID(mDNS * const m)10135 mDNSexport mDNSOpaque16 mDNS_NewMessageID(mDNS * const m)
10136 	{
10137 	mDNSOpaque16 id;
10138 	int i;
10139 
10140 	for (i=0; i<10; i++)
10141 		{
10142 		id = mDNSOpaque16fromIntVal(1 + (mDNSu16)mDNSRandom(0xFFFE));
10143 		if (!mDNS_IdUsedInResourceRecordsList(m, id) && !mDNS_IdUsedInQuestionsList(m, id)) break;
10144 		}
10145 
10146 	debugf("mDNS_NewMessageID: %5d", mDNSVal16(id));
10147 
10148 	return id;
10149 	}
10150 
10151 // ***************************************************************************
10152 #if COMPILER_LIKES_PRAGMA_MARK
10153 #pragma mark -
10154 #pragma mark - Sleep Proxy Server
10155 #endif
10156 
RestartARPProbing(mDNS * const m,AuthRecord * const rr)10157 mDNSlocal void RestartARPProbing(mDNS *const m, AuthRecord *const rr)
10158 	{
10159 	// If we see an ARP from a machine we think is sleeping, then either
10160 	// (i) the machine has woken, or
10161 	// (ii) it's just a stray old packet from before the machine slept
10162 	// To handle the second case, we reset ProbeCount, so we'll suppress our own answers for a while, to avoid
10163 	// generating ARP conflicts with a waking machine, and set rr->LastAPTime so we'll start probing again in 10 seconds.
10164 	// If the machine has just woken then we'll discard our records when we see the first new mDNS probe from that machine.
10165 	// If it was a stray old packet, then after 10 seconds we'll probe again and then start answering ARPs again. In this case we *do*
10166 	// need to send new ARP Announcements, because the owner's ARP broadcasts will have updated neighboring ARP caches, so we need to
10167 	// re-assert our (temporary) ownership of that IP address in order to receive subsequent packets addressed to that IPv4 address.
10168 
10169 	rr->resrec.RecordType = kDNSRecordTypeUnique;
10170 	rr->ProbeCount        = DefaultProbeCountForTypeUnique;
10171 
10172 	// If we haven't started announcing yet (and we're not already in ten-second-delay mode) the machine is probably
10173 	// still going to sleep, so we just reset rr->ProbeCount so we'll continue probing until it stops responding.
10174 	// If we *have* started announcing, the machine is probably in the process of waking back up, so in that case
10175 	// we're more cautious and we wait ten seconds before probing it again. We do this because while waking from
10176 	// sleep, some network interfaces tend to lose or delay inbound packets, and without this delay, if the waking machine
10177 	// didn't answer our three probes within three seconds then we'd announce and cause it an unnecessary address conflict.
10178 	if (rr->AnnounceCount == InitialAnnounceCount && m->timenow - rr->LastAPTime >= 0)
10179 		InitializeLastAPTime(m, rr);
10180 	else
10181 		{
10182 		rr->AnnounceCount  = InitialAnnounceCount;
10183 		rr->ThisAPInterval = mDNSPlatformOneSecond;
10184 		rr->LastAPTime     = m->timenow + mDNSPlatformOneSecond * 9;	// Send first packet at rr->LastAPTime + rr->ThisAPInterval, i.e. 10 seconds from now
10185 		SetNextAnnounceProbeTime(m, rr);
10186 		}
10187 	}
10188 
mDNSCoreReceiveRawARP(mDNS * const m,const ARP_EthIP * const arp,const mDNSInterfaceID InterfaceID)10189 mDNSlocal void mDNSCoreReceiveRawARP(mDNS *const m, const ARP_EthIP *const arp, const mDNSInterfaceID InterfaceID)
10190 	{
10191 	static const mDNSOpaque16 ARP_op_request = { { 0, 1 } };
10192 	AuthRecord *rr;
10193 	NetworkInterfaceInfo *intf = FirstInterfaceForID(m, InterfaceID);
10194 	if (!intf) return;
10195 
10196 	mDNS_Lock(m);
10197 
10198 	// Pass 1:
10199 	// Process ARP Requests and Probes (but not Announcements), and generate an ARP Reply if necessary.
10200 	// We also process ARPs from our own kernel (and 'answer' them by injecting a local ARP table entry)
10201 	// We ignore ARP Announcements here -- Announcements are not questions, they're assertions, so we don't need to answer them.
10202 	// The times we might need to react to an ARP Announcement are:
10203 	// (i) as an indication that the host in question has not gone to sleep yet (so we should delay beginning to proxy for it) or
10204 	// (ii) if it's a conflicting Announcement from another host
10205 	// -- and we check for these in Pass 2 below.
10206 	if (mDNSSameOpaque16(arp->op, ARP_op_request) && !mDNSSameIPv4Address(arp->spa, arp->tpa))
10207 		{
10208 		for (rr = m->ResourceRecords; rr; rr=rr->next)
10209 			if (rr->resrec.InterfaceID == InterfaceID && rr->resrec.RecordType != kDNSRecordTypeDeregistering &&
10210 				rr->AddressProxy.type == mDNSAddrType_IPv4 && mDNSSameIPv4Address(rr->AddressProxy.ip.v4, arp->tpa))
10211 				{
10212 				static const char msg1[] = "ARP Req from owner -- re-probing";
10213 				static const char msg2[] = "Ignoring  ARP Request from      ";
10214 				static const char msg3[] = "Creating Local ARP Cache entry  ";
10215 				static const char msg4[] = "Answering ARP Request from      ";
10216 				const char *const msg = mDNSSameEthAddress(&arp->sha, &rr->WakeUp.IMAC) ? msg1 :
10217 										(rr->AnnounceCount == InitialAnnounceCount)     ? msg2 :
10218 										mDNSSameEthAddress(&arp->sha, &intf->MAC)       ? msg3 : msg4;
10219 				LogSPS("%-7s %s %.6a %.4a for %.4a -- H-MAC %.6a I-MAC %.6a %s",
10220 					intf->ifname, msg, &arp->sha, &arp->spa, &arp->tpa, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, ARDisplayString(m, rr));
10221 				if      (msg == msg1) RestartARPProbing(m, rr);
10222 				else if (msg == msg3) mDNSPlatformSetLocalAddressCacheEntry(m, &rr->AddressProxy, &rr->WakeUp.IMAC, InterfaceID);
10223 				else if (msg == msg4) SendARP(m, 2, rr, &arp->tpa, &arp->sha, &arp->spa, &arp->sha);
10224 				}
10225 		}
10226 
10227 	// Pass 2:
10228 	// For all types of ARP packet we check the Sender IP address to make sure it doesn't conflict with any AddressProxy record we're holding.
10229 	// (Strictly speaking we're only checking Announcement/Request/Reply packets, since ARP Probes have zero Sender IP address,
10230 	// so by definition (and by design) they can never conflict with any real (i.e. non-zero) IP address).
10231 	// We ignore ARPs we sent ourselves (Sender MAC address is our MAC address) because our own proxy ARPs do not constitute a conflict that we need to handle.
10232 	// If we see an apparently conflicting ARP, we check the sender hardware address:
10233 	//   If the sender hardware address is the original owner this is benign, so we just suppress our own proxy answering for a while longer.
10234 	//   If the sender hardware address is *not* the original owner, then this is a conflict, and we need to wake the sleeping machine to handle it.
10235 	if (mDNSSameEthAddress(&arp->sha, &intf->MAC))
10236 		debugf("ARP from self for %.4a", &arp->tpa);
10237 	else
10238 		{
10239 		if (!mDNSSameIPv4Address(arp->spa, zerov4Addr))
10240 			for (rr = m->ResourceRecords; rr; rr=rr->next)
10241 				if (rr->resrec.InterfaceID == InterfaceID && rr->resrec.RecordType != kDNSRecordTypeDeregistering &&
10242 					rr->AddressProxy.type == mDNSAddrType_IPv4 && mDNSSameIPv4Address(rr->AddressProxy.ip.v4, arp->spa))
10243 					{
10244 					RestartARPProbing(m, rr);
10245 					if (mDNSSameEthAddress(&arp->sha, &rr->WakeUp.IMAC))
10246 						LogSPS("%-7s ARP %s from owner %.6a %.4a for %-15.4a -- re-starting probing for %s", intf->ifname,
10247 							mDNSSameIPv4Address(arp->spa, arp->tpa) ? "Announcement " : mDNSSameOpaque16(arp->op, ARP_op_request) ? "Request      " : "Response     ",
10248 							&arp->sha, &arp->spa, &arp->tpa, ARDisplayString(m, rr));
10249 					else
10250 						{
10251 						LogMsg("%-7s Conflicting ARP from %.6a %.4a for %.4a -- waking H-MAC %.6a I-MAC %.6a %s", intf->ifname,
10252 							&arp->sha, &arp->spa, &arp->tpa, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, ARDisplayString(m, rr));
10253 						ScheduleWakeup(m, rr->resrec.InterfaceID, &rr->WakeUp.HMAC);
10254 						}
10255 					}
10256 		}
10257 
10258 	mDNS_Unlock(m);
10259 	}
10260 
10261 /*
10262 // Option 1 is Source Link Layer Address Option
10263 // Option 2 is Target Link Layer Address Option
10264 mDNSlocal const mDNSEthAddr *GetLinkLayerAddressOption(const IPv6NDP *const ndp, const mDNSu8 *const end, mDNSu8 op)
10265 	{
10266 	const mDNSu8 *options = (mDNSu8 *)(ndp+1);
10267 	while (options < end)
10268 		{
10269 		debugf("NDP Option %02X len %2d %d", options[0], options[1], end - options);
10270 		if (options[0] == op && options[1] == 1) return (const mDNSEthAddr*)(options+2);
10271 		options += options[1] * 8;
10272 		}
10273 	return mDNSNULL;
10274 	}
10275 */
10276 
mDNSCoreReceiveRawND(mDNS * const m,const mDNSEthAddr * const sha,const mDNSv6Addr * spa,const IPv6NDP * const ndp,const mDNSu8 * const end,const mDNSInterfaceID InterfaceID)10277 mDNSlocal void mDNSCoreReceiveRawND(mDNS *const m, const mDNSEthAddr *const sha, const mDNSv6Addr *spa,
10278 	const IPv6NDP *const ndp, const mDNSu8 *const end, const mDNSInterfaceID InterfaceID)
10279 	{
10280 	AuthRecord *rr;
10281 	NetworkInterfaceInfo *intf = FirstInterfaceForID(m, InterfaceID);
10282 	if (!intf) return;
10283 
10284 	mDNS_Lock(m);
10285 
10286 	// Pass 1: Process Neighbor Solicitations, and generate a Neighbor Advertisement if necessary.
10287 	if (ndp->type == NDP_Sol)
10288 		{
10289 		//const mDNSEthAddr *const sha = GetLinkLayerAddressOption(ndp, end, NDP_SrcLL);
10290 		(void)end;
10291 		for (rr = m->ResourceRecords; rr; rr=rr->next)
10292 			if (rr->resrec.InterfaceID == InterfaceID && rr->resrec.RecordType != kDNSRecordTypeDeregistering &&
10293 				rr->AddressProxy.type == mDNSAddrType_IPv6 && mDNSSameIPv6Address(rr->AddressProxy.ip.v6, ndp->target))
10294 				{
10295 				static const char msg1[] = "NDP Req from owner -- re-probing";
10296 				static const char msg2[] = "Ignoring  NDP Request from      ";
10297 				static const char msg3[] = "Creating Local NDP Cache entry  ";
10298 				static const char msg4[] = "Answering NDP Request from      ";
10299 				static const char msg5[] = "Answering NDP Probe   from      ";
10300 				const char *const msg = sha && mDNSSameEthAddress(sha, &rr->WakeUp.IMAC) ? msg1 :
10301 										(rr->AnnounceCount == InitialAnnounceCount)      ? msg2 :
10302 										sha && mDNSSameEthAddress(sha, &intf->MAC)       ? msg3 :
10303 										spa && mDNSIPv6AddressIsZero(*spa)               ? msg4 : msg5;
10304 				LogSPS("%-7s %s %.6a %.16a for %.16a -- H-MAC %.6a I-MAC %.6a %s",
10305 					intf->ifname, msg, sha, spa, &ndp->target, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, ARDisplayString(m, rr));
10306 				if      (msg == msg1) RestartARPProbing(m, rr);
10307 				else if (msg == msg3)
10308 					{
10309 					if (!(m->KnownBugs & mDNS_KnownBug_LimitedIPv6))
10310 						mDNSPlatformSetLocalAddressCacheEntry(m, &rr->AddressProxy, &rr->WakeUp.IMAC, InterfaceID);
10311 					}
10312 				else if (msg == msg4) SendNDP(m, NDP_Adv, NDP_Solicited, rr, &ndp->target, mDNSNULL, spa,          sha             );
10313 				else if (msg == msg5) SendNDP(m, NDP_Adv, 0,             rr, &ndp->target, mDNSNULL, &AllHosts_v6, &AllHosts_v6_Eth);
10314 				}
10315 		}
10316 
10317 	// Pass 2: For all types of NDP packet we check the Sender IP address to make sure it doesn't conflict with any AddressProxy record we're holding.
10318 	if (mDNSSameEthAddress(sha, &intf->MAC))
10319 		debugf("NDP from self for %.16a", &ndp->target);
10320 	else
10321 		{
10322 		// For Neighbor Advertisements we check the Target address field, not the actual IPv6 source address.
10323 		// When a machine has both link-local and routable IPv6 addresses, it may send NDP packets making assertions
10324 		// about its routable IPv6 address, using its link-local address as the source address for all NDP packets.
10325 		// Hence it is the NDP target address we care about, not the actual packet source address.
10326 		if (ndp->type == NDP_Adv) spa = &ndp->target;
10327 		if (!mDNSSameIPv6Address(*spa, zerov6Addr))
10328 			for (rr = m->ResourceRecords; rr; rr=rr->next)
10329 				if (rr->resrec.InterfaceID == InterfaceID && rr->resrec.RecordType != kDNSRecordTypeDeregistering &&
10330 					rr->AddressProxy.type == mDNSAddrType_IPv6 && mDNSSameIPv6Address(rr->AddressProxy.ip.v6, *spa))
10331 					{
10332 					RestartARPProbing(m, rr);
10333 					if (mDNSSameEthAddress(sha, &rr->WakeUp.IMAC))
10334 						LogSPS("%-7s NDP %s from owner %.6a %.16a for %.16a -- re-starting probing for %s", intf->ifname,
10335 							ndp->type == NDP_Sol ? "Solicitation " : "Advertisement", sha, spa, &ndp->target, ARDisplayString(m, rr));
10336 					else
10337 						{
10338 						LogMsg("%-7s Conflicting NDP from %.6a %.16a for %.16a -- waking H-MAC %.6a I-MAC %.6a %s", intf->ifname,
10339 							sha, spa, &ndp->target, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, ARDisplayString(m, rr));
10340 						ScheduleWakeup(m, rr->resrec.InterfaceID, &rr->WakeUp.HMAC);
10341 						}
10342 					}
10343 		}
10344 
10345 	mDNS_Unlock(m);
10346 	}
10347 
mDNSCoreReceiveRawTransportPacket(mDNS * const m,const mDNSEthAddr * const sha,const mDNSAddr * const src,const mDNSAddr * const dst,const mDNSu8 protocol,const mDNSu8 * const p,const TransportLayerPacket * const t,const mDNSu8 * const end,const mDNSInterfaceID InterfaceID,const mDNSu16 len)10348 mDNSlocal void mDNSCoreReceiveRawTransportPacket(mDNS *const m, const mDNSEthAddr *const sha, const mDNSAddr *const src, const mDNSAddr *const dst, const mDNSu8 protocol,
10349 	const mDNSu8 *const p, const TransportLayerPacket *const t, const mDNSu8 *const end, const mDNSInterfaceID InterfaceID, const mDNSu16 len)
10350 	{
10351 	const mDNSIPPort port = (protocol == 0x06) ? t->tcp.dst : (protocol == 0x11) ? t->udp.dst : zeroIPPort;
10352 	mDNSBool wake = mDNSfalse;
10353 
10354 	switch (protocol)
10355 		{
10356 		#define XX wake ? "Received" : "Ignoring", end-p
10357 		case 0x01:	LogSPS("Ignoring %d-byte ICMP from %#a to %#a", end-p, src, dst);
10358 					break;
10359 
10360 		case 0x06:	{
10361 					#define SSH_AsNumber 22
10362 					static const mDNSIPPort SSH = { { SSH_AsNumber >> 8, SSH_AsNumber & 0xFF } };
10363 
10364 					// Plan to wake if
10365 					// (a) RST is not set, AND
10366 					// (b) packet is SYN, SYN+FIN, or plain data packet (no SYN or FIN). We won't wake for FIN alone.
10367 					wake = (!(t->tcp.flags & 4) && (t->tcp.flags & 3) != 1);
10368 
10369 					// For now, to reduce spurious wakeups, we wake only for TCP SYN,
10370 					// except for ssh connections, where we'll wake for plain data packets too
10371 					if (!mDNSSameIPPort(port, SSH) && !(t->tcp.flags & 2)) wake = mDNSfalse;
10372 
10373 					LogSPS("%s %d-byte TCP from %#a:%d to %#a:%d%s%s%s", XX,
10374 						src, mDNSVal16(t->tcp.src), dst, mDNSVal16(port),
10375 						(t->tcp.flags & 2) ? " SYN" : "",
10376 						(t->tcp.flags & 1) ? " FIN" : "",
10377 						(t->tcp.flags & 4) ? " RST" : "");
10378 					}
10379 					break;
10380 
10381 		case 0x11:	{
10382 					#define ARD_AsNumber 3283
10383 					static const mDNSIPPort ARD = { { ARD_AsNumber >> 8, ARD_AsNumber & 0xFF } };
10384 					const mDNSu16 udplen = (mDNSu16)((mDNSu16)t->bytes[4] << 8 | t->bytes[5]);		// Length *including* 8-byte UDP header
10385 					if (udplen >= sizeof(UDPHeader))
10386 						{
10387 						const mDNSu16 datalen = udplen - sizeof(UDPHeader);
10388 						wake = mDNStrue;
10389 
10390 						// For Back to My Mac UDP port 4500 (IPSEC) packets, we do some special handling
10391 						if (mDNSSameIPPort(port, IPSECPort))
10392 							{
10393 							// Specifically ignore NAT keepalive packets
10394 							if (datalen == 1 && end >= &t->bytes[9] && t->bytes[8] == 0xFF) wake = mDNSfalse;
10395 							else
10396 								{
10397 								// Skip over the Non-ESP Marker if present
10398 								const mDNSBool NonESP = (end >= &t->bytes[12] && t->bytes[8] == 0 && t->bytes[9] == 0 && t->bytes[10] == 0 && t->bytes[11] == 0);
10399 								const IKEHeader *const ike    = (IKEHeader *)(t + (NonESP ? 12 : 8));
10400 								const mDNSu16          ikelen = datalen - (NonESP ? 4 : 0);
10401 								if (ikelen >= sizeof(IKEHeader) && end >= ((mDNSu8 *)ike) + sizeof(IKEHeader))
10402 									if ((ike->Version & 0x10) == 0x10)
10403 										{
10404 										// ExchangeType ==  5 means 'Informational' <http://www.ietf.org/rfc/rfc2408.txt>
10405 										// ExchangeType == 34 means 'IKE_SA_INIT'   <http://www.iana.org/assignments/ikev2-parameters>
10406 										if (ike->ExchangeType == 5 || ike->ExchangeType == 34) wake = mDNSfalse;
10407 										LogSPS("%s %d-byte IKE ExchangeType %d", XX, ike->ExchangeType);
10408 										}
10409 								}
10410 							}
10411 
10412 						// For now, because we haven't yet worked out a clean elegant way to do this, we just special-case the
10413 						// Apple Remote Desktop port number -- we ignore all packets to UDP 3283 (the "Net Assistant" port),
10414 						// except for Apple Remote Desktop's explicit manual wakeup packet, which looks like this:
10415 						// UDP header (8 bytes)
10416 						// Payload: 13 88 00 6a 41 4e 41 20 (8 bytes) ffffffffffff (6 bytes) 16xMAC (96 bytes) = 110 bytes total
10417 						if (mDNSSameIPPort(port, ARD)) wake = (datalen >= 110 && end >= &t->bytes[10] && t->bytes[8] == 0x13 && t->bytes[9] == 0x88);
10418 
10419 						LogSPS("%s %d-byte UDP from %#a:%d to %#a:%d", XX, src, mDNSVal16(t->udp.src), dst, mDNSVal16(port));
10420 						}
10421 					}
10422 					break;
10423 
10424 		case 0x3A:	if (&t->bytes[len] <= end)
10425 						{
10426 						mDNSu16 checksum = IPv6CheckSum(&src->ip.v6, &dst->ip.v6, protocol, t->bytes, len);
10427 						if (!checksum) mDNSCoreReceiveRawND(m, sha, &src->ip.v6, &t->ndp, &t->bytes[len], InterfaceID);
10428 						else LogInfo("IPv6CheckSum bad %04X %02X%02X from %#a to %#a", checksum, t->bytes[2], t->bytes[3], src, dst);
10429 						}
10430 					break;
10431 
10432 		default:	LogSPS("Ignoring %d-byte IP packet unknown protocol %d from %#a to %#a", end-p, protocol, src, dst);
10433 					break;
10434 		}
10435 
10436 	if (wake)
10437 		{
10438 		AuthRecord *rr, *r2;
10439 
10440 		mDNS_Lock(m);
10441 		for (rr = m->ResourceRecords; rr; rr=rr->next)
10442 			if (rr->resrec.InterfaceID == InterfaceID &&
10443 				rr->resrec.RecordType != kDNSRecordTypeDeregistering &&
10444 				rr->AddressProxy.type && mDNSSameAddress(&rr->AddressProxy, dst))
10445 				{
10446 				const mDNSu8 *const tp = (protocol == 6) ? (const mDNSu8 *)"\x4_tcp" : (const mDNSu8 *)"\x4_udp";
10447 				for (r2 = m->ResourceRecords; r2; r2=r2->next)
10448 					if (r2->resrec.InterfaceID == InterfaceID && mDNSSameEthAddress(&r2->WakeUp.HMAC, &rr->WakeUp.HMAC) &&
10449 						r2->resrec.RecordType != kDNSRecordTypeDeregistering &&
10450 						r2->resrec.rrtype == kDNSType_SRV && mDNSSameIPPort(r2->resrec.rdata->u.srv.port, port) &&
10451 						SameDomainLabel(ThirdLabel(r2->resrec.name)->c, tp))
10452 						break;
10453 				if (!r2 && mDNSSameIPPort(port, IPSECPort)) r2 = rr;	// So that we wake for BTMM IPSEC packets, even without a matching SRV record
10454 				if (r2)
10455 					{
10456 					LogMsg("Waking host at %s %#a H-MAC %.6a I-MAC %.6a for %s",
10457 						InterfaceNameForID(m, rr->resrec.InterfaceID), dst, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, ARDisplayString(m, r2));
10458 					ScheduleWakeup(m, rr->resrec.InterfaceID, &rr->WakeUp.HMAC);
10459 					}
10460 				else
10461 					LogSPS("Sleeping host at %s %#a %.6a has no service on %#s %d",
10462 						InterfaceNameForID(m, rr->resrec.InterfaceID), dst, &rr->WakeUp.HMAC, tp, mDNSVal16(port));
10463 				}
10464 		mDNS_Unlock(m);
10465 		}
10466 	}
10467 
mDNSCoreReceiveRawPacket(mDNS * const m,const mDNSu8 * const p,const mDNSu8 * const end,const mDNSInterfaceID InterfaceID)10468 mDNSexport void mDNSCoreReceiveRawPacket(mDNS *const m, const mDNSu8 *const p, const mDNSu8 *const end, const mDNSInterfaceID InterfaceID)
10469 	{
10470 	static const mDNSOpaque16 Ethertype_ARP  = { { 0x08, 0x06 } };	// Ethertype 0x0806 = ARP
10471 	static const mDNSOpaque16 Ethertype_IPv4 = { { 0x08, 0x00 } };	// Ethertype 0x0800 = IPv4
10472 	static const mDNSOpaque16 Ethertype_IPv6 = { { 0x86, 0xDD } };	// Ethertype 0x86DD = IPv6
10473 	static const mDNSOpaque16 ARP_hrd_eth    = { { 0x00, 0x01 } };	// Hardware address space (Ethernet = 1)
10474 	static const mDNSOpaque16 ARP_pro_ip     = { { 0x08, 0x00 } };	// Protocol address space (IP = 0x0800)
10475 
10476 	// Note: BPF guarantees that the NETWORK LAYER header will be word aligned, not the link-layer header.
10477 	// In other words, we can safely assume that pkt below (ARP, IPv4 or IPv6) is properly word aligned,
10478 	// but if pkt is 4-byte aligned, that necessarily means that eth CANNOT also be 4-byte aligned
10479 	// since it points to a an address 14 bytes before pkt.
10480 	const EthernetHeader     *const eth = (const EthernetHeader *)p;
10481 	const NetworkLayerPacket *const pkt = (const NetworkLayerPacket *)(eth+1);
10482 	mDNSAddr src, dst;
10483 	#define RequiredCapLen(P) ((P)==0x01 ? 4 : (P)==0x06 ? 20 : (P)==0x11 ? 8 : (P)==0x3A ? 24 : 0)
10484 
10485 	// Is ARP? Length must be at least 14 + 28 = 42 bytes
10486 	if (end >= p+42 && mDNSSameOpaque16(eth->ethertype, Ethertype_ARP) && mDNSSameOpaque16(pkt->arp.hrd, ARP_hrd_eth) && mDNSSameOpaque16(pkt->arp.pro, ARP_pro_ip))
10487 		mDNSCoreReceiveRawARP(m, &pkt->arp, InterfaceID);
10488 	// Is IPv4 with zero fragmentation offset? Length must be at least 14 + 20 = 34 bytes
10489 	else if (end >= p+34 && mDNSSameOpaque16(eth->ethertype, Ethertype_IPv4) && (pkt->v4.flagsfrags.b[0] & 0x1F) == 0 && pkt->v4.flagsfrags.b[1] == 0)
10490 		{
10491 		const mDNSu8 *const trans = p + 14 + (pkt->v4.vlen & 0xF) * 4;
10492 		debugf("Got IPv4 %02X from %.4a to %.4a", pkt->v4.protocol, &pkt->v4.src, &pkt->v4.dst);
10493 		src.type = mDNSAddrType_IPv4; src.ip.v4 = pkt->v4.src;
10494 		dst.type = mDNSAddrType_IPv4; dst.ip.v4 = pkt->v4.dst;
10495 		if (end >= trans + RequiredCapLen(pkt->v4.protocol))
10496 			mDNSCoreReceiveRawTransportPacket(m, &eth->src, &src, &dst, pkt->v4.protocol, p, (TransportLayerPacket*)trans, end, InterfaceID, 0);
10497 		}
10498 	// Is IPv6? Length must be at least 14 + 28 = 42 bytes
10499 	else if (end >= p+54 && mDNSSameOpaque16(eth->ethertype, Ethertype_IPv6))
10500 		{
10501 		const mDNSu8 *const trans = p + 54;
10502 		debugf("Got IPv6  %02X from %.16a to %.16a", pkt->v6.pro, &pkt->v6.src, &pkt->v6.dst);
10503 		src.type = mDNSAddrType_IPv6; src.ip.v6 = pkt->v6.src;
10504 		dst.type = mDNSAddrType_IPv6; dst.ip.v6 = pkt->v6.dst;
10505 		if (end >= trans + RequiredCapLen(pkt->v6.pro))
10506 			mDNSCoreReceiveRawTransportPacket(m, &eth->src, &src, &dst, pkt->v6.pro, p, (TransportLayerPacket*)trans, end, InterfaceID,
10507 				(mDNSu16)pkt->bytes[4] << 8 | pkt->bytes[5]);
10508 		}
10509 	}
10510 
ConstructSleepProxyServerName(mDNS * const m,domainlabel * name)10511 mDNSlocal void ConstructSleepProxyServerName(mDNS *const m, domainlabel *name)
10512 	{
10513 	name->c[0] = (mDNSu8)mDNS_snprintf((char*)name->c+1, 62, "%d-%d-%d-%d %#s",
10514 		m->SPSType, m->SPSPortability, m->SPSMarginalPower, m->SPSTotalPower, &m->nicelabel);
10515 	}
10516 
SleepProxyServerCallback(mDNS * const m,ServiceRecordSet * const srs,mStatus result)10517 mDNSlocal void SleepProxyServerCallback(mDNS *const m, ServiceRecordSet *const srs, mStatus result)
10518 	{
10519 	if (result == mStatus_NameConflict)
10520 		mDNS_RenameAndReregisterService(m, srs, mDNSNULL);
10521 	else if (result == mStatus_MemFree)
10522 		{
10523 		if (m->SleepState)
10524 			m->SPSState = 3;
10525 		else
10526 			{
10527 			m->SPSState = (mDNSu8)(m->SPSSocket != mDNSNULL);
10528 			if (m->SPSState)
10529 				{
10530 				domainlabel name;
10531 				ConstructSleepProxyServerName(m, &name);
10532 				mDNS_RegisterService(m, srs,
10533 					&name, &SleepProxyServiceType, &localdomain,
10534 					mDNSNULL, m->SPSSocket->port,				// Host, port
10535 					(mDNSu8 *)"", 1,							// TXT data, length
10536 					mDNSNULL, 0,								// Subtypes (none)
10537 					mDNSInterface_Any,							// Interface ID
10538 					SleepProxyServerCallback, mDNSNULL, 0);		// Callback, context, flags
10539 				}
10540 			LogSPS("Sleep Proxy Server %#s %s", srs->RR_SRV.resrec.name->c, m->SPSState ? "started" : "stopped");
10541 			}
10542 		}
10543 	}
10544 
10545 // Called with lock held
mDNSCoreBeSleepProxyServer_internal(mDNS * const m,mDNSu8 sps,mDNSu8 port,mDNSu8 marginalpower,mDNSu8 totpower)10546 mDNSexport void mDNSCoreBeSleepProxyServer_internal(mDNS *const m, mDNSu8 sps, mDNSu8 port, mDNSu8 marginalpower, mDNSu8 totpower)
10547 	{
10548 	// This routine uses mDNS_DeregisterService and calls SleepProxyServerCallback, so we execute in user callback context
10549 	mDNS_DropLockBeforeCallback();
10550 
10551 	// If turning off SPS, close our socket
10552 	// (Do this first, BEFORE calling mDNS_DeregisterService below)
10553 	if (!sps && m->SPSSocket) { mDNSPlatformUDPClose(m->SPSSocket); m->SPSSocket = mDNSNULL; }
10554 
10555 	// If turning off, or changing type, deregister old name
10556 	if (m->SPSState == 1 && sps != m->SPSType)
10557 		{ m->SPSState = 2; mDNS_DeregisterService_drt(m, &m->SPSRecords, sps ? mDNS_Dereg_rapid : mDNS_Dereg_normal); }
10558 
10559 	// Record our new SPS parameters
10560 	m->SPSType          = sps;
10561 	m->SPSPortability   = port;
10562 	m->SPSMarginalPower = marginalpower;
10563 	m->SPSTotalPower    = totpower;
10564 
10565 	// If turning on, open socket and advertise service
10566 	if (sps)
10567 		{
10568 		if (!m->SPSSocket)
10569 			{
10570 			m->SPSSocket = mDNSPlatformUDPSocket(m, zeroIPPort);
10571 			if (!m->SPSSocket) { LogMsg("mDNSCoreBeSleepProxyServer: Failed to allocate SPSSocket"); goto fail; }
10572 			}
10573 		if (m->SPSState == 0) SleepProxyServerCallback(m, &m->SPSRecords, mStatus_MemFree);
10574 		}
10575 	else if (m->SPSState)
10576 		{
10577 		LogSPS("mDNSCoreBeSleepProxyServer turning off from state %d; will wake clients", m->SPSState);
10578 		m->NextScheduledSPS = m->timenow;
10579 		}
10580 fail:
10581 	mDNS_ReclaimLockAfterCallback();
10582 	}
10583 
10584 // ***************************************************************************
10585 #if COMPILER_LIKES_PRAGMA_MARK
10586 #pragma mark -
10587 #pragma mark - Startup and Shutdown
10588 #endif
10589 
mDNS_GrowCache_internal(mDNS * const m,CacheEntity * storage,mDNSu32 numrecords)10590 mDNSlocal void mDNS_GrowCache_internal(mDNS *const m, CacheEntity *storage, mDNSu32 numrecords)
10591 	{
10592 	if (storage && numrecords)
10593 		{
10594 		mDNSu32 i;
10595 		debugf("Adding cache storage for %d more records (%d bytes)", numrecords, numrecords*sizeof(CacheEntity));
10596 		for (i=0; i<numrecords; i++) storage[i].next = &storage[i+1];
10597 		storage[numrecords-1].next = m->rrcache_free;
10598 		m->rrcache_free = storage;
10599 		m->rrcache_size += numrecords;
10600 		}
10601 	}
10602 
mDNS_GrowCache(mDNS * const m,CacheEntity * storage,mDNSu32 numrecords)10603 mDNSexport void mDNS_GrowCache(mDNS *const m, CacheEntity *storage, mDNSu32 numrecords)
10604 	{
10605 	mDNS_Lock(m);
10606 	mDNS_GrowCache_internal(m, storage, numrecords);
10607 	mDNS_Unlock(m);
10608 	}
10609 
mDNS_Init(mDNS * const m,mDNS_PlatformSupport * const p,CacheEntity * rrcachestorage,mDNSu32 rrcachesize,mDNSBool AdvertiseLocalAddresses,mDNSCallback * Callback,void * Context)10610 mDNSexport mStatus mDNS_Init(mDNS *const m, mDNS_PlatformSupport *const p,
10611 	CacheEntity *rrcachestorage, mDNSu32 rrcachesize,
10612 	mDNSBool AdvertiseLocalAddresses, mDNSCallback *Callback, void *Context)
10613 	{
10614 	mDNSu32 slot;
10615 	mDNSs32 timenow;
10616 	mStatus result;
10617 
10618 	if (!rrcachestorage) rrcachesize = 0;
10619 
10620 	m->p                             = p;
10621 	m->KnownBugs                     = 0;
10622 	m->CanReceiveUnicastOn5353       = mDNSfalse; // Assume we can't receive unicasts on 5353, unless platform layer tells us otherwise
10623 	m->AdvertiseLocalAddresses       = AdvertiseLocalAddresses;
10624 	m->DivertMulticastAdvertisements = mDNSfalse;
10625 	m->mDNSPlatformStatus            = mStatus_Waiting;
10626 	m->UnicastPort4                  = zeroIPPort;
10627 	m->UnicastPort6                  = zeroIPPort;
10628 	m->PrimaryMAC                    = zeroEthAddr;
10629 	m->MainCallback                  = Callback;
10630 	m->MainContext                   = Context;
10631 	m->rec.r.resrec.RecordType       = 0;
10632 
10633 	// For debugging: To catch and report locking failures
10634 	m->mDNS_busy               = 0;
10635 	m->mDNS_reentrancy         = 0;
10636 	m->ShutdownTime            = 0;
10637 	m->lock_rrcache            = 0;
10638 	m->lock_Questions          = 0;
10639 	m->lock_Records            = 0;
10640 
10641 	// Task Scheduling variables
10642 	result = mDNSPlatformTimeInit();
10643 	if (result != mStatus_NoError) return(result);
10644 	m->timenow_adjust = (mDNSs32)mDNSRandom(0xFFFFFFFF);
10645 	timenow = mDNS_TimeNow_NoLock(m);
10646 
10647 	m->timenow                 = 0;		// MUST only be set within mDNS_Lock/mDNS_Unlock section
10648 	m->timenow_last            = timenow;
10649 	m->NextScheduledEvent      = timenow;
10650 	m->SuppressSending         = timenow;
10651 	m->NextCacheCheck          = timenow + 0x78000000;
10652 	m->NextScheduledQuery      = timenow + 0x78000000;
10653 	m->NextScheduledProbe      = timenow + 0x78000000;
10654 	m->NextScheduledResponse   = timenow + 0x78000000;
10655 	m->NextScheduledNATOp      = timenow + 0x78000000;
10656 	m->NextScheduledSPS        = timenow + 0x78000000;
10657 	m->NextScheduledStopTime   = timenow + 0x78000000;
10658 	m->RandomQueryDelay        = 0;
10659 	m->RandomReconfirmDelay    = 0;
10660 	m->PktNum                  = 0;
10661 	m->LocalRemoveEvents       = mDNSfalse;
10662 	m->SleepState              = SleepState_Awake;
10663 	m->SleepSeqNum             = 0;
10664 	m->SystemWakeOnLANEnabled  = mDNSfalse;
10665 	m->AnnounceOwner           = NonZeroTime(timenow + 60 * mDNSPlatformOneSecond);
10666 	m->DelaySleep              = 0;
10667 	m->SleepLimit              = 0;
10668 
10669 	// These fields only required for mDNS Searcher...
10670 	m->Questions               = mDNSNULL;
10671 	m->NewQuestions            = mDNSNULL;
10672 	m->CurrentQuestion         = mDNSNULL;
10673 	m->LocalOnlyQuestions      = mDNSNULL;
10674 	m->NewLocalOnlyQuestions   = mDNSNULL;
10675 	m->RestartQuestion	       = mDNSNULL;
10676 	m->rrcache_size            = 0;
10677 	m->rrcache_totalused       = 0;
10678 	m->rrcache_active          = 0;
10679 	m->rrcache_report          = 10;
10680 	m->rrcache_free            = mDNSNULL;
10681 
10682 	for (slot = 0; slot < CACHE_HASH_SLOTS; slot++)
10683 		{
10684 		m->rrcache_hash[slot]      = mDNSNULL;
10685 		m->rrcache_nextcheck[slot] = timenow + 0x78000000;;
10686 		}
10687 
10688 	mDNS_GrowCache_internal(m, rrcachestorage, rrcachesize);
10689 	m->rrauth.rrauth_free            = mDNSNULL;
10690 
10691 	for (slot = 0; slot < AUTH_HASH_SLOTS; slot++)
10692 		m->rrauth.rrauth_hash[slot] = mDNSNULL;
10693 
10694 	// Fields below only required for mDNS Responder...
10695 	m->hostlabel.c[0]          = 0;
10696 	m->nicelabel.c[0]          = 0;
10697 	m->MulticastHostname.c[0]  = 0;
10698 	m->HIHardware.c[0]         = 0;
10699 	m->HISoftware.c[0]         = 0;
10700 	m->ResourceRecords         = mDNSNULL;
10701 	m->DuplicateRecords        = mDNSNULL;
10702 	m->NewLocalRecords         = mDNSNULL;
10703 	m->NewLocalOnlyRecords     = mDNSfalse;
10704 	m->CurrentRecord           = mDNSNULL;
10705 	m->HostInterfaces          = mDNSNULL;
10706 	m->ProbeFailTime           = 0;
10707 	m->NumFailedProbes         = 0;
10708 	m->SuppressProbes          = 0;
10709 
10710 #ifndef UNICAST_DISABLED
10711 	m->NextuDNSEvent            = timenow + 0x78000000;
10712 	m->NextSRVUpdate            = timenow + 0x78000000;
10713 
10714 	m->DNSServers               = mDNSNULL;
10715 
10716 	m->Router                   = zeroAddr;
10717 	m->AdvertisedV4             = zeroAddr;
10718 	m->AdvertisedV6             = zeroAddr;
10719 
10720 	m->AuthInfoList             = mDNSNULL;
10721 
10722 	m->ReverseMap.ThisQInterval = -1;
10723 	m->StaticHostname.c[0]      = 0;
10724 	m->FQDN.c[0]                = 0;
10725 	m->Hostnames                = mDNSNULL;
10726 	m->AutoTunnelHostAddr.b[0]  = 0;
10727 	m->AutoTunnelHostAddrActive = mDNSfalse;
10728 	m->AutoTunnelLabel.c[0]     = 0;
10729 
10730 	m->StartWABQueries          = mDNSfalse;
10731 	m->RegisterAutoTunnel6      = mDNStrue;
10732 
10733 	// NAT traversal fields
10734 	m->NATTraversals            = mDNSNULL;
10735 	m->CurrentNATTraversal      = mDNSNULL;
10736 	m->retryIntervalGetAddr     = 0;	// delta between time sent and retry
10737 	m->retryGetAddr             = timenow + 0x78000000;	// absolute time when we retry
10738 	m->ExternalAddress          = zerov4Addr;
10739 
10740 	m->NATMcastRecvskt          = mDNSNULL;
10741 	m->LastNATupseconds         = 0;
10742 	m->LastNATReplyLocalTime    = timenow;
10743 	m->LastNATMapResultCode     = NATErr_None;
10744 
10745 	m->UPnPInterfaceID          = 0;
10746 	m->SSDPSocket               = mDNSNULL;
10747 	m->SSDPWANPPPConnection     = mDNSfalse;
10748 	m->UPnPRouterPort           = zeroIPPort;
10749 	m->UPnPSOAPPort             = zeroIPPort;
10750 	m->UPnPRouterURL            = mDNSNULL;
10751 	m->UPnPWANPPPConnection     = mDNSfalse;
10752 	m->UPnPSOAPURL              = mDNSNULL;
10753 	m->UPnPRouterAddressString  = mDNSNULL;
10754 	m->UPnPSOAPAddressString    = mDNSNULL;
10755 	m->SPSType                  = 0;
10756 	m->SPSPortability           = 0;
10757 	m->SPSMarginalPower         = 0;
10758 	m->SPSTotalPower            = 0;
10759 	m->SPSState                 = 0;
10760 	m->SPSProxyListChanged      = mDNSNULL;
10761 	m->SPSSocket                = mDNSNULL;
10762 	m->SPSBrowseCallback        = mDNSNULL;
10763 	m->ProxyRecords             = 0;
10764 
10765 #endif
10766 
10767 #if APPLE_OSX_mDNSResponder
10768 	m->TunnelClients            = mDNSNULL;
10769 
10770 #if ! NO_WCF
10771 	CHECK_WCF_FUNCTION(WCFConnectionNew)
10772 		{
10773 		m->WCF = WCFConnectionNew();
10774 		if (!m->WCF) { LogMsg("WCFConnectionNew failed"); return -1; }
10775 		}
10776 #endif
10777 
10778 #endif
10779 
10780 	result = mDNSPlatformInit(m);
10781 
10782 #ifndef UNICAST_DISABLED
10783 	// It's better to do this *after* the platform layer has set up the
10784 	// interface list and security credentials
10785 	uDNS_SetupDNSConfig(m);						// Get initial DNS configuration
10786 #endif
10787 
10788 	return(result);
10789 	}
10790 
mDNS_ConfigChanged(mDNS * const m)10791 mDNSexport void mDNS_ConfigChanged(mDNS *const m)
10792 	{
10793 	if (m->SPSState == 1)
10794 		{
10795 		domainlabel name, newname;
10796 		domainname type, domain;
10797 		DeconstructServiceName(m->SPSRecords.RR_SRV.resrec.name, &name, &type, &domain);
10798 		ConstructSleepProxyServerName(m, &newname);
10799 		if (!SameDomainLabelCS(name.c, newname.c))
10800 			{
10801 			LogSPS("Renaming SPS from “%#s” to “%#s”", name.c, newname.c);
10802 			// When SleepProxyServerCallback gets the mStatus_MemFree message,
10803 			// it will reregister the service under the new name
10804 			m->SPSState = 2;
10805 			mDNS_DeregisterService_drt(m, &m->SPSRecords, mDNS_Dereg_rapid);
10806 			}
10807 		}
10808 
10809 	if (m->MainCallback)
10810 		m->MainCallback(m, mStatus_ConfigChanged);
10811 	}
10812 
DynDNSHostNameCallback(mDNS * const m,AuthRecord * const rr,mStatus result)10813 mDNSlocal void DynDNSHostNameCallback(mDNS *const m, AuthRecord *const rr, mStatus result)
10814 	{
10815 	(void)m;	// unused
10816 	debugf("NameStatusCallback: result %d for registration of name %##s", result, rr->resrec.name->c);
10817 	mDNSPlatformDynDNSHostNameStatusChanged(rr->resrec.name, result);
10818 	}
10819 
PurgeOrReconfirmCacheRecord(mDNS * const m,CacheRecord * cr,const DNSServer * const ptr,mDNSBool lameduck)10820 mDNSlocal void PurgeOrReconfirmCacheRecord(mDNS *const m, CacheRecord *cr, const DNSServer * const ptr, mDNSBool lameduck)
10821 	{
10822 	mDNSBool purge = cr->resrec.RecordType == kDNSRecordTypePacketNegative ||
10823 					 cr->resrec.rrtype     == kDNSType_A ||
10824 					 cr->resrec.rrtype     == kDNSType_AAAA ||
10825 					 cr->resrec.rrtype     == kDNSType_SRV;
10826 
10827 	(void) lameduck;
10828 	(void) ptr;
10829 	debugf("PurgeOrReconfirmCacheRecord: %s cache record due to %s server %p %#a:%d (%##s): %s",
10830 		purge    ? "purging"   : "reconfirming",
10831 		lameduck ? "lame duck" : "new",
10832 		ptr, &ptr->addr, mDNSVal16(ptr->port), ptr->domain.c, CRDisplayString(m, cr));
10833 
10834 	if (purge)
10835 		{
10836 		LogInfo("PurgeorReconfirmCacheRecord: Purging Resourcerecord %s, RecordType %x", CRDisplayString(m, cr), cr->resrec.RecordType);
10837 		mDNS_PurgeCacheResourceRecord(m, cr);
10838 		}
10839 	else
10840 		{
10841 		LogInfo("PurgeorReconfirmCacheRecord: Reconfirming Resourcerecord %s, RecordType %x", CRDisplayString(m, cr), cr->resrec.RecordType);
10842 		mDNS_Reconfirm_internal(m, cr, kDefaultReconfirmTimeForNoAnswer);
10843 		}
10844 	}
10845 
mDNS_PurgeBeforeResolve(mDNS * const m,DNSQuestion * q)10846 mDNSlocal void mDNS_PurgeBeforeResolve(mDNS *const m, DNSQuestion *q)
10847 	{
10848 	const mDNSu32 slot = HashSlot(&q->qname);
10849 	CacheGroup *const cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname);
10850 	CacheRecord *rp;
10851 
10852 	for (rp = cg ? cg->members : mDNSNULL; rp; rp = rp->next)
10853 		{
10854 		if (SameNameRecordAnswersQuestion(&rp->resrec, q))
10855 			{
10856 			LogInfo("mDNS_PurgeBeforeResolve: Flushing %s", CRDisplayString(m, rp));
10857 			mDNS_PurgeCacheResourceRecord(m, rp);
10858 			}
10859 		}
10860 	}
10861 
CacheRecordResetDNSServer(mDNS * const m,DNSQuestion * q,DNSServer * new)10862 mDNSlocal void CacheRecordResetDNSServer(mDNS *const m, DNSQuestion *q, DNSServer *new)
10863 	{
10864 	const mDNSu32 slot = HashSlot(&q->qname);
10865 	CacheGroup *const cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname);
10866 	CacheRecord *rp;
10867 	mDNSBool found = mDNSfalse;
10868 	mDNSBool foundNew = mDNSfalse;
10869 	DNSServer *old = q->qDNSServer;
10870 	mDNSBool newQuestion = IsQuestionNew(m, q);
10871 	DNSQuestion *qptr;
10872 
10873 	// This function is called when the DNSServer is updated to the new question. There may already be
10874 	// some cache entries matching the old DNSServer and/or new DNSServer. There are four cases. In the
10875 	// following table, "Yes" denotes that a cache entry was found for old/new DNSServer.
10876 	//
10877 	// 					old DNSServer		new DNSServer
10878 	//
10879 	//	Case 1				Yes					Yes
10880 	//  Case 2				No					Yes
10881 	//  Case 3				Yes					No
10882 	//  Case 4				No					No
10883 	//
10884 	// Case 1: There are cache entries for both old and new DNSServer. We handle this case by simply
10885 	//		   expiring the old Cache entries, deliver a RMV event (if an ADD event was delivered before)
10886 	//		   followed by the ADD event of the cache entries corresponding to the new server. This
10887 	//		   case happens when we pick a DNSServer, issue a query and get a valid response and create
10888 	//		   cache entries after which it stops responding. Another query (non-duplicate) picks a different
10889 	//	       DNSServer and creates identical cache entries (perhaps through records in Additional records).
10890 	//		   Now if the first one expires and tries to pick the new DNSServer (the original DNSServer
10891 	//		   is not responding) we will find cache entries corresponding to both DNSServers.
10892 	//
10893 	// Case 2: There are no cache entries for the old DNSServer but there are some for the new DNSServer.
10894 	//		   This means we should deliver an ADD event. Normally ADD events are delivered by
10895 	//		   AnswerNewQuestion if it is a new question. So, we check to see if it is a new question
10896 	//		   and if so, leave it to AnswerNewQuestion to deliver it. Otherwise, we use
10897 	//		   AnswerQuestionsForDNSServerChanges to deliver the ADD event. This case happens when a
10898 	//		   question picks a DNS server for which AnswerNewQuestion could not deliver an answer even
10899 	//         though there were potential cache entries but DNSServer did not match. Now when we
10900 	//         pick a new DNSServer, those cache entries may answer this question.
10901 	//
10902 	// Case 3: There are the cache entries for the old DNSServer but none for the new. We just move
10903 	//		   the old cache entries to point to the new DNSServer and the caller is expected to
10904 	//		   do a purge or reconfirm to delete or validate the RDATA. We don't need to do anything
10905 	//		   special for delivering ADD events, as it should have been done/will be done by
10906 	//		   AnswerNewQuestion. This case happens when we picked a DNSServer, sent the query and
10907 	//		   got a response and the cache is expired now and we are reissuing the question but the
10908 	//		   original DNSServer does not respond.
10909 	//
10910 	// Case 4: There are no cache entries either for the old or for the new DNSServer. There is nothing
10911 	//		   much we can do here.
10912 	//
10913 	// Case 2 and 3 are the most common while case 4 is possible when no DNSServers are working. Case 1
10914 	// is relatively less likely to happen in practice
10915 
10916 	// Temporarily set the DNSServer to look for the matching records for the new DNSServer.
10917 	q->qDNSServer = new;
10918 	for (rp = cg ? cg->members : mDNSNULL; rp; rp = rp->next)
10919 		{
10920 		if (SameNameRecordAnswersQuestion(&rp->resrec, q))
10921 			{
10922 			LogInfo("CacheRecordResetDNSServer: Found cache record %##s for new DNSServer address: %#a", rp->resrec.name->c,
10923 				(rp->resrec.rDNSServer != mDNSNULL ?  &rp->resrec.rDNSServer->addr : mDNSNULL));
10924 			foundNew = mDNStrue;
10925 			break;
10926 			}
10927 		}
10928 	q->qDNSServer = old;
10929 
10930 	for (rp = cg ? cg->members : mDNSNULL; rp; rp = rp->next)
10931 		{
10932 		if (SameNameRecordAnswersQuestion(&rp->resrec, q))
10933 			{
10934 			// Case1
10935 			found = mDNStrue;
10936 			if (foundNew)
10937 				{
10938 				LogInfo("CacheRecordResetDNSServer: Flushing Resourcerecord %##s, before:%#a, after:%#a", rp->resrec.name->c,
10939 					(rp->resrec.rDNSServer != mDNSNULL ?  &rp->resrec.rDNSServer->addr : mDNSNULL),
10940 					(new != mDNSNULL ?  &new->addr : mDNSNULL));
10941 				mDNS_PurgeCacheResourceRecord(m, rp);
10942 				if (newQuestion)
10943 					{
10944 					// "q" is not a duplicate question. If it is a newQuestion, then the CRActiveQuestion can't be
10945 					// possibly set as it is set only when we deliver the ADD event to the question.
10946 					if (rp->CRActiveQuestion != mDNSNULL)
10947 						{
10948 						LogMsg("CacheRecordResetDNSServer: ERROR!!: CRActiveQuestion %p set, current question %p, name %##s", rp->CRActiveQuestion, q, q->qname.c);
10949 						rp->CRActiveQuestion = mDNSNULL;
10950 						}
10951 					// if this is a new question, then we never delivered an ADD yet, so don't deliver the RMV.
10952 					continue;
10953 					}
10954 				}
10955 			LogInfo("CacheRecordResetDNSServer: resetting cache record %##s DNSServer address before:%#a,"
10956 				" after:%#a, CRActiveQuestion %p", rp->resrec.name->c, (rp->resrec.rDNSServer != mDNSNULL ?
10957 				&rp->resrec.rDNSServer->addr : mDNSNULL), (new != mDNSNULL ?  &new->addr : mDNSNULL),
10958 				rp->CRActiveQuestion);
10959 			// Though we set it to the new DNS server, the caller is *assumed* to do either a purge
10960 			// or reconfirm or send out questions to the "new" server to verify whether the cached
10961 			// RDATA is valid
10962 			rp->resrec.rDNSServer = new;
10963 			}
10964 		}
10965 
10966 	// Case 1 and Case 2
10967 	if ((found && foundNew) || (!found && foundNew))
10968 		{
10969 		if (newQuestion)
10970 			LogInfo("CacheRecordResetDNSServer: deliverAddEvents not set for question %p %##s (%s)", q, q->qname.c, DNSTypeName(q->qtype));
10971 		else if (QuerySuppressed(q))
10972 			LogInfo("CacheRecordResetDNSServer: deliverAddEvents not set for suppressed question %p %##s (%s)", q, q->qname.c, DNSTypeName(q->qtype));
10973 		else
10974 			{
10975 			LogInfo("CacheRecordResetDNSServer: deliverAddEvents set for %p %##s (%s)", q, q->qname.c, DNSTypeName(q->qtype));
10976 			q->deliverAddEvents = mDNStrue;
10977 			for (qptr = q->next; qptr; qptr = qptr->next)
10978 				if (qptr->DuplicateOf == q) qptr->deliverAddEvents = mDNStrue;
10979 			}
10980 		return;
10981 		}
10982 
10983 	// Case 3 and Case 4
10984 	return;
10985 	}
10986 
DNSServerChangeForQuestion(mDNS * const m,DNSQuestion * q,DNSServer * new)10987 mDNSexport void DNSServerChangeForQuestion(mDNS *const m, DNSQuestion *q, DNSServer *new)
10988 	{
10989 	DNSQuestion *qptr;
10990 
10991 	// 1. Whenever we change the DNS server, we change the message identifier also so that response
10992 	// from the old server is not accepted as a response from the new server but only messages
10993 	// from the new server are accepted as valid responses. We do it irrespective of whether "new"
10994 	// is NULL or not. It is possible that we send two queries, no responses, pick a new DNS server
10995 	// which is NULL and now the response comes back and will try to penalize the DNS server which
10996 	// is NULL. By setting the messageID here, we will not accept that as a valid response.
10997 
10998 	q->TargetQID = mDNS_NewMessageID(m);
10999 
11000 	// 2. Move the old cache records to point them at the new DNSServer so that we can deliver the ADD/RMV events
11001 	// appropriately. At any point in time, we want all the cache records point only to one DNSServer for a given
11002 	// question. "DNSServer" here is the DNSServer object and not the DNS server itself. It is possible to
11003 	// have the same DNS server address in two objects, one scoped and another not scoped. But, the cache is per
11004 	// DNSServer object. By maintaining the question and the cache entries point to the same DNSServer
11005 	// always, the cache maintenance and delivery of ADD/RMV events becomes simpler.
11006 	//
11007 	// CacheRecordResetDNSServer should be called only once for the non-duplicate question as once the cache
11008 	// entries are moved to point to the new DNSServer, we don't need to call it for the duplicate question
11009 	// and it is wrong to call for the duplicate question as it's decision to mark deliverAddevents will be
11010 	// incorrect.
11011 
11012 	if (q->DuplicateOf)
11013 		LogMsg("DNSServerChangeForQuestion: ERROR: Called for duplicate question %##s", q->qname.c);
11014 	else
11015 		CacheRecordResetDNSServer(m, q, new);
11016 
11017 	// 3. Make sure all the duplicate questions point to the same DNSServer so that delivery
11018 	// of events for all of them are consistent. Duplicates for a question are always inserted
11019 	// after in the list.
11020 	q->qDNSServer = new;
11021 	for (qptr = q->next ; qptr; qptr = qptr->next)
11022 		{
11023 		if (qptr->DuplicateOf == q) { qptr->validDNSServers = q->validDNSServers; qptr->qDNSServer = new; }
11024 		}
11025 	}
11026 
uDNS_SetupDNSConfig(mDNS * const m)11027 mDNSexport mStatus uDNS_SetupDNSConfig(mDNS *const m)
11028 	{
11029 	mDNSu32 slot;
11030 	CacheGroup *cg;
11031 	CacheRecord *cr;
11032 
11033 	mDNSAddr     v4, v6, r;
11034 	domainname   fqdn;
11035 	DNSServer   *ptr, **p = &m->DNSServers;
11036 	const DNSServer *oldServers = m->DNSServers;
11037 	DNSQuestion *q;
11038 	McastResolver *mr, **mres = &m->McastResolvers;
11039 
11040 	debugf("uDNS_SetupDNSConfig: entry");
11041 
11042 	// Let the platform layer get the current DNS information
11043 	// The m->StartWABQueries is set when we get the first domain enumeration query (no need to hit the network
11044 	// with domain enumeration queries until we actually need that information). Even if it is not set, we still
11045 	// need to setup the search domains so that we can append them to queries that need them.
11046 
11047 	uDNS_SetupSearchDomains(m, m->StartWABQueries ? UDNS_START_WAB_QUERY : 0);
11048 
11049 	mDNS_Lock(m);
11050 
11051 	for (ptr = m->DNSServers; ptr; ptr = ptr->next)
11052 		{
11053 		ptr->penaltyTime = 0;
11054 		ptr->flags |= DNSServer_FlagDelete;
11055 		}
11056 
11057 	// We handle the mcast resolvers here itself as mDNSPlatformSetDNSConfig looks at
11058 	// mcast resolvers. Today we get both mcast and ucast configuration using the same
11059 	// API
11060 	for (mr = m->McastResolvers; mr; mr = mr->next)
11061 		mr->flags |= McastResolver_FlagDelete;
11062 
11063 	mDNSPlatformSetDNSConfig(m, mDNStrue, mDNSfalse, &fqdn, mDNSNULL, mDNSNULL);
11064 
11065 	// For now, we just delete the mcast resolvers. We don't deal with cache or
11066 	// questions here. Neither question nor cache point to mcast resolvers. Questions
11067 	// do inherit the timeout values from mcast resolvers. But we don't bother
11068 	// affecting them as they never change.
11069 	while (*mres)
11070 		{
11071 		if (((*mres)->flags & DNSServer_FlagDelete) != 0)
11072 			{
11073 			mr = *mres;
11074 			*mres = (*mres)->next;
11075 			debugf("uDNS_SetupDNSConfig: Deleting mcast resolver %##s", mr, mr->domain.c);
11076 			mDNSPlatformMemFree(mr);
11077 			}
11078 		else
11079 			{
11080 			(*mres)->flags &= ~McastResolver_FlagNew;
11081 			mres = &(*mres)->next;
11082 			}
11083 		}
11084 
11085 	// Mark the records to be flushed that match a new resolver. We need to do this before
11086 	// we walk the questions below where we change the DNSServer pointer of the cache
11087 	// record
11088 	FORALL_CACHERECORDS(slot, cg, cr)
11089 		{
11090 		if (cr->resrec.InterfaceID) continue;
11091 
11092 		// We just mark them for purge or reconfirm. We can't affect the DNSServer pointer
11093 		// here as the code below that calls CacheRecordResetDNSServer relies on this
11094 		//
11095 		// The new DNSServer may be a scoped or non-scoped one. We use the active question's
11096 		// InterfaceID for looking up the right DNS server
11097 		ptr = GetServerForName(m, cr->resrec.name, cr->CRActiveQuestion ? cr->CRActiveQuestion->InterfaceID : mDNSNULL);
11098 
11099 		// Purge or Reconfirm if this cache entry would use the new DNS server
11100 		if (ptr && (ptr != cr->resrec.rDNSServer))
11101 			{
11102 			// As the DNSServers for this cache record is not the same anymore, we don't
11103 			// want any new questions to pick this old value
11104 			if (cr->CRActiveQuestion == mDNSNULL)
11105 				{
11106 				LogInfo("uDNS_SetupDNSConfig: Purging Resourcerecord %s", CRDisplayString(m, cr));
11107 				mDNS_PurgeCacheResourceRecord(m, cr);
11108 				}
11109 			else
11110 				{
11111 				LogInfo("uDNS_SetupDNSConfig: Purging/Reconfirming Resourcerecord %s", CRDisplayString(m, cr));
11112 				PurgeOrReconfirmCacheRecord(m, cr, ptr, mDNSfalse);
11113 				}
11114 			}
11115 		}
11116 	// Update our qDNSServer pointers before we go and free the DNSServer object memory
11117 	for (q = m->Questions; q; q=q->next)
11118 		if (!mDNSOpaque16IsZero(q->TargetQID))
11119 			{
11120 			DNSServer *s, *t;
11121 			DNSQuestion *qptr;
11122 			if (q->DuplicateOf) continue;
11123 			SetValidDNSServers(m, q);
11124 			q->triedAllServersOnce = 0;
11125 			s = GetServerForQuestion(m, q);
11126 			t = q->qDNSServer;
11127 			if (t != s)
11128 				{
11129 				// If DNS Server for this question has changed, reactivate it
11130 				debugf("uDNS_SetupDNSConfig: Updating DNS Server from %p %#a:%d (%##s) to %p %#a:%d (%##s) for %##s (%s)",
11131 					t, t ? &t->addr : mDNSNULL, mDNSVal16(t ? t->port : zeroIPPort), t ? t->domain.c : (mDNSu8*)"",
11132 					s, s ? &s->addr : mDNSNULL, mDNSVal16(s ? s->port : zeroIPPort), s ? s->domain.c : (mDNSu8*)"",
11133 					q->qname.c, DNSTypeName(q->qtype));
11134 
11135 				// After we reset the DNSServer pointer on the cache records here, three things could happen:
11136 				//
11137 				// 1) The query gets sent out and when the actual response comes back later it is possible
11138 				// that the response has the same RDATA, in which case we update our cache entry.
11139 				// If the response is different, then the entry will expire and a new entry gets added.
11140 				// For the latter case to generate a RMV followed by ADD events, we need to reset the DNS
11141 				// server here to match the question and the cache record.
11142 				//
11143 				// 2) We might have marked the cache entries for purge above and for us to be able to generate the RMV
11144 				// events for the questions, the DNSServer on the question should match the Cache Record
11145 				//
11146 				// 3) We might have marked the cache entries for reconfirm above, for which we send the query out which is
11147 				// the same as the first case above.
11148 
11149 				DNSServerChangeForQuestion(m, q, s);
11150 				q->unansweredQueries = 0;
11151 				// We still need to pick a new DNSServer for the questions that have been
11152 				// suppressed, but it is wrong to activate the query as DNS server change
11153 				// could not possibly change the status of SuppressUnusable questions
11154 				if (!QuerySuppressed(q))
11155 					{
11156 					debugf("uDNS_SetupDNSConfig: Activating query %p %##s (%s)", q, q->qname.c, DNSTypeName(q->qtype));
11157 					ActivateUnicastQuery(m, q, mDNStrue);
11158 					// ActivateUnicastQuery is called for duplicate questions also as it does something
11159 					// special for AutoTunnel questions
11160 					for (qptr = q->next ; qptr; qptr = qptr->next)
11161 						{
11162 						if (qptr->DuplicateOf == q) ActivateUnicastQuery(m, qptr, mDNStrue);
11163 						}
11164 					}
11165 				}
11166 			else
11167 				{
11168 				debugf("uDNS_SetupDNSConfig: Not Updating DNS server question %p %##s (%s) DNS server %#a:%d %p %d",
11169 					q, q->qname.c, DNSTypeName(q->qtype), t ? &t->addr : mDNSNULL, mDNSVal16(t ? t->port : zeroIPPort), q->DuplicateOf, q->SuppressUnusable);
11170 				for (qptr = q->next ; qptr; qptr = qptr->next)
11171 					if (qptr->DuplicateOf == q) { qptr->validDNSServers = q->validDNSServers; qptr->qDNSServer = q->qDNSServer; }
11172 				}
11173 			}
11174 
11175 	while (*p)
11176 		{
11177 		if (((*p)->flags & DNSServer_FlagDelete) != 0)
11178 			{
11179 			// Scan our cache, looking for uDNS records that we would have queried this server for.
11180 			// We reconfirm any records that match, because in this world of split DNS, firewalls, etc.
11181 			// different DNS servers can give different answers to the same question.
11182 			ptr = *p;
11183 			FORALL_CACHERECORDS(slot, cg, cr)
11184 				{
11185 				if (cr->resrec.InterfaceID) continue;
11186 				if (cr->resrec.rDNSServer == ptr)
11187 					{
11188 					// If we don't have an active question for this cache record, neither Purge can
11189 					// generate RMV events nor Reconfirm can send queries out. Just set the DNSServer
11190 					// pointer on the record NULL so that we don't point to freed memory (We might dereference
11191 					// DNSServer pointers from resource record for logging purposes).
11192 					//
11193 					// If there is an active question, point to its DNSServer as long as it does not point to the
11194 					// freed one. We already went through the questions above and made them point at either the
11195 					// new server or NULL if there is no server and also affected the cache entries that match
11196 					// this question. Hence, whenever we hit a resource record with a DNSServer that is just
11197 					// about to be deleted, we should never have an active question. The code below just tries to
11198 					// be careful logging messages if we ever hit this case.
11199 
11200 					if (cr->CRActiveQuestion)
11201 						{
11202 						DNSQuestion *qptr = cr->CRActiveQuestion;
11203 						if (qptr->qDNSServer == mDNSNULL)
11204 							LogMsg("uDNS_SetupDNSConfig: Cache Record %s match: Active question %##s (%s) with DNSServer Address NULL, Server to be deleted %#a",
11205 								CRDisplayString(m, cr), qptr->qname.c, DNSTypeName(qptr->qtype), &ptr->addr);
11206 						else
11207 							LogMsg("uDNS_SetupDNSConfig: Cache Record %s match: Active question %##s (%s) DNSServer Address %#a, Server to be deleted %#a",
11208 								CRDisplayString(m, cr),  qptr->qname.c, DNSTypeName(qptr->qtype), &qptr->qDNSServer->addr, &ptr->addr);
11209 
11210 						if (qptr->qDNSServer == ptr)
11211 							{
11212 							qptr->validDNSServers = zeroOpaque64;
11213 							qptr->qDNSServer = mDNSNULL;
11214 							cr->resrec.rDNSServer = mDNSNULL;
11215 							}
11216 						else
11217 							{
11218 							cr->resrec.rDNSServer = qptr->qDNSServer;
11219 							}
11220 						}
11221 					else
11222 						{
11223 						LogInfo("uDNS_SetupDNSConfig: Cache Record %##s has no Active question, Record's DNSServer Address %#a, Server to be deleted %#a",
11224 							cr->resrec.name, &cr->resrec.rDNSServer->addr, &ptr->addr);
11225 						cr->resrec.rDNSServer = mDNSNULL;
11226 						}
11227 
11228 					PurgeOrReconfirmCacheRecord(m, cr, ptr, mDNStrue);
11229 					}
11230 				}
11231 			*p = (*p)->next;
11232 			debugf("uDNS_SetupDNSConfig: Deleting server %p %#a:%d (%##s)", ptr, &ptr->addr, mDNSVal16(ptr->port), ptr->domain.c);
11233 			mDNSPlatformMemFree(ptr);
11234 			NumUnicastDNSServers--;
11235 			}
11236 		else
11237 			{
11238 			(*p)->flags &= ~DNSServer_FlagNew;
11239 			p = &(*p)->next;
11240 			}
11241 		}
11242 
11243 	// If we now have no DNS servers at all and we used to have some, then immediately purge all unicast cache records (including for LLQs).
11244 	// This is important for giving prompt remove events when the user disconnects the Ethernet cable or turns off wireless.
11245 	// Otherwise, stale data lingers for 5-10 seconds, which is not the user-experience people expect from Bonjour.
11246 	// Similarly, if we now have some DNS servers and we used to have none, we want to purge any fake negative results we may have generated.
11247 	if ((m->DNSServers != mDNSNULL) != (oldServers != mDNSNULL))
11248 		{
11249 		int count = 0;
11250 		FORALL_CACHERECORDS(slot, cg, cr) if (!cr->resrec.InterfaceID) { mDNS_PurgeCacheResourceRecord(m, cr); count++; }
11251 		LogInfo("uDNS_SetupDNSConfig: %s available; purged %d unicast DNS records from cache",
11252 			m->DNSServers ? "DNS server became" : "No DNS servers", count);
11253 
11254 		// Force anything that needs to get zone data to get that information again
11255 		RestartRecordGetZoneData(m);
11256 		}
11257 
11258 	// Did our FQDN change?
11259 	if (!SameDomainName(&fqdn, &m->FQDN))
11260 		{
11261 		if (m->FQDN.c[0]) mDNS_RemoveDynDNSHostName(m, &m->FQDN);
11262 
11263 		AssignDomainName(&m->FQDN, &fqdn);
11264 
11265 		if (m->FQDN.c[0])
11266 			{
11267 			mDNSPlatformDynDNSHostNameStatusChanged(&m->FQDN, 1);
11268 			mDNS_AddDynDNSHostName(m, &m->FQDN, DynDNSHostNameCallback, mDNSNULL);
11269 			}
11270 		}
11271 
11272 	mDNS_Unlock(m);
11273 
11274 	// handle router and primary interface changes
11275 	v4 = v6 = r = zeroAddr;
11276 	v4.type = r.type = mDNSAddrType_IPv4;
11277 
11278 	if (mDNSPlatformGetPrimaryInterface(m, &v4, &v6, &r) == mStatus_NoError && !mDNSv4AddressIsLinkLocal(&v4.ip.v4))
11279 		{
11280 		mDNS_SetPrimaryInterfaceInfo(m,
11281 			!mDNSIPv4AddressIsZero(v4.ip.v4) ? &v4 : mDNSNULL,
11282 			!mDNSIPv6AddressIsZero(v6.ip.v6) ? &v6 : mDNSNULL,
11283 			!mDNSIPv4AddressIsZero(r .ip.v4) ? &r  : mDNSNULL);
11284 		}
11285 	else
11286 		{
11287 		mDNS_SetPrimaryInterfaceInfo(m, mDNSNULL, mDNSNULL, mDNSNULL);
11288 		if (m->FQDN.c[0]) mDNSPlatformDynDNSHostNameStatusChanged(&m->FQDN, 1);	// Set status to 1 to indicate temporary failure
11289 		}
11290 
11291 	debugf("uDNS_SetupDNSConfig: number of unicast DNS servers %d", NumUnicastDNSServers);
11292 	return mStatus_NoError;
11293 	}
11294 
mDNSCoreInitComplete(mDNS * const m,mStatus result)11295 mDNSexport void mDNSCoreInitComplete(mDNS *const m, mStatus result)
11296 	{
11297 	m->mDNSPlatformStatus = result;
11298 	if (m->MainCallback)
11299 		{
11300 		mDNS_Lock(m);
11301 		mDNS_DropLockBeforeCallback();		// Allow client to legally make mDNS API calls from the callback
11302 		m->MainCallback(m, mStatus_NoError);
11303 		mDNS_ReclaimLockAfterCallback();	// Decrement mDNS_reentrancy to block mDNS API calls again
11304 		mDNS_Unlock(m);
11305 		}
11306 	}
11307 
DeregLoop(mDNS * const m,AuthRecord * const start)11308 mDNSlocal void DeregLoop(mDNS *const m, AuthRecord *const start)
11309 	{
11310 	m->CurrentRecord = start;
11311 	while (m->CurrentRecord)
11312 		{
11313 		AuthRecord *rr = m->CurrentRecord;
11314 		LogInfo("DeregLoop: %s deregistration for %p %02X %s",
11315 			(rr->resrec.RecordType != kDNSRecordTypeDeregistering) ? "Initiating  " : "Accelerating",
11316 			rr, rr->resrec.RecordType, ARDisplayString(m, rr));
11317 		if (rr->resrec.RecordType != kDNSRecordTypeDeregistering)
11318 			mDNS_Deregister_internal(m, rr, mDNS_Dereg_rapid);
11319 		else if (rr->AnnounceCount > 1)
11320 			{
11321 			rr->AnnounceCount = 1;
11322 			rr->LastAPTime = m->timenow - rr->ThisAPInterval;
11323 			}
11324 		// Mustn't advance m->CurrentRecord until *after* mDNS_Deregister_internal, because
11325 		// new records could have been added to the end of the list as a result of that call.
11326 		if (m->CurrentRecord == rr) // If m->CurrentRecord was not advanced for us, do it now
11327 			m->CurrentRecord = rr->next;
11328 		}
11329 	}
11330 
mDNS_StartExit(mDNS * const m)11331 mDNSexport void mDNS_StartExit(mDNS *const m)
11332 	{
11333 	NetworkInterfaceInfo *intf;
11334 	AuthRecord *rr;
11335 
11336 	mDNS_Lock(m);
11337 
11338 	LogInfo("mDNS_StartExit");
11339 	m->ShutdownTime = NonZeroTime(m->timenow + mDNSPlatformOneSecond * 5);
11340 
11341 	mDNSCoreBeSleepProxyServer_internal(m, 0, 0, 0, 0);
11342 
11343 #if APPLE_OSX_mDNSResponder
11344 #if ! NO_WCF
11345 	CHECK_WCF_FUNCTION(WCFConnectionDealloc)
11346 		{
11347 		if (m->WCF) WCFConnectionDealloc((WCFConnection *)m->WCF);
11348 		}
11349 #endif
11350 #endif
11351 
11352 #ifndef UNICAST_DISABLED
11353 	{
11354 	SearchListElem *s;
11355 	SuspendLLQs(m);
11356 	// Don't need to do SleepRecordRegistrations() here
11357 	// because we deregister all records and services later in this routine
11358 	while (m->Hostnames) mDNS_RemoveDynDNSHostName(m, &m->Hostnames->fqdn);
11359 
11360 	// For each member of our SearchList, deregister any records it may have created, and cut them from the list.
11361 	// Otherwise they'll be forcibly deregistered for us (without being cut them from the appropriate list)
11362 	// and we may crash because the list still contains dangling pointers.
11363 	for (s = SearchList; s; s = s->next)
11364 		while (s->AuthRecs)
11365 			{
11366 			ARListElem *dereg = s->AuthRecs;
11367 			s->AuthRecs = s->AuthRecs->next;
11368 			mDNS_Deregister_internal(m, &dereg->ar, mDNS_Dereg_normal);	// Memory will be freed in the FreeARElemCallback
11369 			}
11370 	}
11371 #endif
11372 
11373 	for (intf = m->HostInterfaces; intf; intf = intf->next)
11374 		if (intf->Advertise)
11375 			DeadvertiseInterface(m, intf);
11376 
11377 	// Shut down all our active NAT Traversals
11378 	while (m->NATTraversals)
11379 		{
11380 		NATTraversalInfo *t = m->NATTraversals;
11381 		mDNS_StopNATOperation_internal(m, t);		// This will cut 't' from the list, thereby advancing m->NATTraversals in the process
11382 
11383 		// After stopping the NAT Traversal, we zero out the fields.
11384 		// This has particularly important implications for our AutoTunnel records --
11385 		// when we deregister our AutoTunnel records below, we don't want their mStatus_MemFree
11386 		// handlers to just turn around and attempt to re-register those same records.
11387 		// Clearing t->ExternalPort/t->RequestedPort will cause the mStatus_MemFree callback handlers
11388 		// to not do this.
11389 		t->ExternalAddress = zerov4Addr;
11390 		t->ExternalPort    = zeroIPPort;
11391 		t->RequestedPort   = zeroIPPort;
11392 		t->Lifetime        = 0;
11393 		t->Result          = mStatus_NoError;
11394 		}
11395 
11396 	// Make sure there are nothing but deregistering records remaining in the list
11397 	if (m->CurrentRecord)
11398 		LogMsg("mDNS_StartExit: ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord));
11399 
11400 	// We're in the process of shutting down, so queries, etc. are no longer available.
11401 	// Consequently, determining certain information, e.g. the uDNS update server's IP
11402 	// address, will not be possible.  The records on the main list are more likely to
11403 	// already contain such information, so we deregister the duplicate records first.
11404 	LogInfo("mDNS_StartExit: Deregistering duplicate resource records");
11405 	DeregLoop(m, m->DuplicateRecords);
11406 	LogInfo("mDNS_StartExit: Deregistering resource records");
11407 	DeregLoop(m, m->ResourceRecords);
11408 
11409 	// If we scheduled a response to send goodbye packets, we set NextScheduledResponse to now. Normally when deregistering records,
11410 	// we allow up to 100ms delay (to help improve record grouping) but when shutting down we don't want any such delay.
11411 	if (m->NextScheduledResponse - m->timenow < mDNSPlatformOneSecond)
11412 		{
11413 		m->NextScheduledResponse = m->timenow;
11414 		m->SuppressSending = 0;
11415 		}
11416 
11417 	if (m->ResourceRecords) LogInfo("mDNS_StartExit: Sending final record deregistrations");
11418 	else                    LogInfo("mDNS_StartExit: No deregistering records remain");
11419 
11420 	for (rr = m->DuplicateRecords; rr; rr = rr->next)
11421 		LogMsg("mDNS_StartExit: Should not still have Duplicate Records remaining: %02X %s", rr->resrec.RecordType, ARDisplayString(m, rr));
11422 
11423 	// Send responses to flush any pending deregistrations
11424 	SendResponses(m);
11425 
11426 	// If any deregistering records remain, send their deregistration announcements before we exit
11427 	if (m->mDNSPlatformStatus != mStatus_NoError) DiscardDeregistrations(m);
11428 
11429 	mDNS_Unlock(m);
11430 
11431 	LogInfo("mDNS_StartExit: done");
11432 	}
11433 
mDNS_FinalExit(mDNS * const m)11434 mDNSexport void mDNS_FinalExit(mDNS *const m)
11435 	{
11436 	mDNSu32 rrcache_active = 0;
11437 	mDNSu32 rrcache_totalused = 0;
11438 	mDNSu32 slot;
11439 	AuthRecord *rr;
11440 
11441 	LogInfo("mDNS_FinalExit: mDNSPlatformClose");
11442 	mDNSPlatformClose(m);
11443 
11444 	rrcache_totalused = m->rrcache_totalused;
11445 	for (slot = 0; slot < CACHE_HASH_SLOTS; slot++)
11446 		{
11447 		while (m->rrcache_hash[slot])
11448 			{
11449 			CacheGroup *cg = m->rrcache_hash[slot];
11450 			while (cg->members)
11451 				{
11452 				CacheRecord *cr = cg->members;
11453 				cg->members = cg->members->next;
11454 				if (cr->CRActiveQuestion) rrcache_active++;
11455 				ReleaseCacheRecord(m, cr);
11456 				}
11457 			cg->rrcache_tail = &cg->members;
11458 			ReleaseCacheGroup(m, &m->rrcache_hash[slot]);
11459 			}
11460 		}
11461 	debugf("mDNS_FinalExit: RR Cache was using %ld records, %lu active", rrcache_totalused, rrcache_active);
11462 	if (rrcache_active != m->rrcache_active)
11463 		LogMsg("*** ERROR *** rrcache_active %lu != m->rrcache_active %lu", rrcache_active, m->rrcache_active);
11464 
11465 	for (rr = m->ResourceRecords; rr; rr = rr->next)
11466 		LogMsg("mDNS_FinalExit failed to send goodbye for: %p %02X %s", rr, rr->resrec.RecordType, ARDisplayString(m, rr));
11467 
11468 	LogInfo("mDNS_FinalExit: done");
11469 	}
11470