1 /* -*- Mode: C; tab-width: 4 -*-
2  *
3  * Copyright (c) 2002-2003 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 
18 #ifndef __DNSCOMMON_H_
19 #define __DNSCOMMON_H_
20 
21 #include "mDNSEmbeddedAPI.h"
22 
23 #ifdef	__cplusplus
24 	extern "C" {
25 #endif
26 
27 //*************************************************************************************************************
28 // Macros
29 
30 // Note: The C preprocessor stringify operator ('#') makes a string from its argument, without macro expansion
31 // e.g. If "version" is #define'd to be "4", then STRINGIFY_AWE(version) will return the string "version", not "4"
32 // To expand "version" to its value before making the string, use STRINGIFY(version) instead
33 #define STRINGIFY_ARGUMENT_WITHOUT_EXPANSION(s) #s
34 #define STRINGIFY(s) STRINGIFY_ARGUMENT_WITHOUT_EXPANSION(s)
35 
36 // ***************************************************************************
37 #if COMPILER_LIKES_PRAGMA_MARK
38 #pragma mark - DNS Protocol Constants
39 #endif
40 
41 typedef enum
42 	{
43 	kDNSFlag0_QR_Mask     = 0x80,		// Query or response?
44 	kDNSFlag0_QR_Query    = 0x00,
45 	kDNSFlag0_QR_Response = 0x80,
46 
47 	kDNSFlag0_OP_Mask     = 0x78,		// Operation type
48 	kDNSFlag0_OP_StdQuery = 0x00,
49 	kDNSFlag0_OP_Iquery   = 0x08,
50 	kDNSFlag0_OP_Status   = 0x10,
51 	kDNSFlag0_OP_Unused3  = 0x18,
52 	kDNSFlag0_OP_Notify   = 0x20,
53 	kDNSFlag0_OP_Update   = 0x28,
54 
55 	kDNSFlag0_QROP_Mask   = kDNSFlag0_QR_Mask | kDNSFlag0_OP_Mask,
56 
57 	kDNSFlag0_AA          = 0x04,		// Authoritative Answer?
58 	kDNSFlag0_TC          = 0x02,		// Truncated?
59 	kDNSFlag0_RD          = 0x01,		// Recursion Desired?
60 	kDNSFlag1_RA          = 0x80,		// Recursion Available?
61 
62 	kDNSFlag1_Zero        = 0x40,		// Reserved; must be zero
63 	kDNSFlag1_AD          = 0x20,		// Authentic Data [RFC 2535]
64 	kDNSFlag1_CD          = 0x10,		// Checking Disabled [RFC 2535]
65 
66 	kDNSFlag1_RC_Mask     = 0x0F,		// Response code
67 	kDNSFlag1_RC_NoErr    = 0x00,
68 	kDNSFlag1_RC_FormErr  = 0x01,
69 	kDNSFlag1_RC_ServFail = 0x02,
70 	kDNSFlag1_RC_NXDomain = 0x03,
71 	kDNSFlag1_RC_NotImpl  = 0x04,
72 	kDNSFlag1_RC_Refused  = 0x05,
73 	kDNSFlag1_RC_YXDomain = 0x06,
74 	kDNSFlag1_RC_YXRRSet  = 0x07,
75 	kDNSFlag1_RC_NXRRSet  = 0x08,
76 	kDNSFlag1_RC_NotAuth  = 0x09,
77 	kDNSFlag1_RC_NotZone  = 0x0A
78 	} DNS_Flags;
79 
80 typedef enum
81 	{
82 	TSIG_ErrBadSig  = 16,
83 	TSIG_ErrBadKey  = 17,
84 	TSIG_ErrBadTime = 18
85 	} TSIG_ErrorCode;
86 
87 // ***************************************************************************
88 #if COMPILER_LIKES_PRAGMA_MARK
89 #pragma mark -
90 #pragma mark - General Utility Functions
91 #endif
92 
93 extern NetworkInterfaceInfo *GetFirstActiveInterface(NetworkInterfaceInfo *intf);
94 extern mDNSInterfaceID GetNextActiveInterfaceID(const NetworkInterfaceInfo *intf);
95 
96 extern mDNSu32 mDNSRandom(mDNSu32 max);		// Returns pseudo-random result from zero to max inclusive
97 
98 // ***************************************************************************
99 #if COMPILER_LIKES_PRAGMA_MARK
100 #pragma mark -
101 #pragma mark - Domain Name Utility Functions
102 #endif
103 
104 #define mDNSIsDigit(X)     ((X) >= '0' && (X) <= '9')
105 #define mDNSIsUpperCase(X) ((X) >= 'A' && (X) <= 'Z')
106 #define mDNSIsLowerCase(X) ((X) >= 'a' && (X) <= 'z')
107 #define mDNSIsLetter(X)    (mDNSIsUpperCase(X) || mDNSIsLowerCase(X))
108 
109 #define mDNSValidHostChar(X, notfirst, notlast) (mDNSIsLetter(X) || mDNSIsDigit(X) || ((notfirst) && (notlast) && (X) == '-') )
110 
111 extern mDNSu16 CompressedDomainNameLength(const domainname *const name, const domainname *parent);
112 extern int CountLabels(const domainname *d);
113 extern const domainname *SkipLeadingLabels(const domainname *d, int skip);
114 
115 extern mDNSu32 TruncateUTF8ToLength(mDNSu8 *string, mDNSu32 length, mDNSu32 max);
116 extern mDNSBool LabelContainsSuffix(const domainlabel *const name, const mDNSBool RichText);
117 extern mDNSu32 RemoveLabelSuffix(domainlabel *name, mDNSBool RichText);
118 extern void AppendLabelSuffix(domainlabel *const name, mDNSu32 val, const mDNSBool RichText);
119 #define ValidateDomainName(N) (DomainNameLength(N) <= MAX_DOMAIN_NAME)
120 
121 // ***************************************************************************
122 #if COMPILER_LIKES_PRAGMA_MARK
123 #pragma mark -
124 #pragma mark - Resource Record Utility Functions
125 #endif
126 
127 // IdenticalResourceRecord returns true if two resources records have
128 // the same name, type, class, and identical rdata (InterfaceID and TTL may differ)
129 
130 // IdenticalSameNameRecord is the same, except it skips the expensive SameDomainName() check,
131 // which is at its most expensive and least useful in cases where we know in advance that the names match
132 
133 // Note: The dominant use of IdenticalResourceRecord is from ProcessQuery(), handling known-answer lists. In this case
134 // it's common to have a whole bunch or records with exactly the same name (e.g. "_http._tcp.local") but different RDATA.
135 // The SameDomainName() check is expensive when the names match, and in this case *all* the names match, so we
136 // used to waste a lot of CPU time verifying that the names match, only then to find that the RDATA is different.
137 // We observed mDNSResponder spending 30% of its total CPU time on this single task alone.
138 // By swapping the checks so that we check the RDATA first, we can quickly detect when it's different
139 // (99% of the time) and then bail out before we waste time on the expensive SameDomainName() check.
140 
141 #define IdenticalResourceRecord(r1,r2) ( \
142 	(r1)->rrtype    == (r2)->rrtype      && \
143 	(r1)->rrclass   == (r2)->rrclass     && \
144 	(r1)->namehash  == (r2)->namehash    && \
145 	(r1)->rdlength  == (r2)->rdlength    && \
146 	(r1)->rdatahash == (r2)->rdatahash   && \
147 	SameRDataBody((r1), &(r2)->rdata->u, SameDomainName) && \
148 	SameDomainName((r1)->name, (r2)->name))
149 
150 #define IdenticalSameNameRecord(r1,r2) ( \
151 	(r1)->rrtype    == (r2)->rrtype      && \
152 	(r1)->rrclass   == (r2)->rrclass     && \
153 	(r1)->rdlength  == (r2)->rdlength    && \
154 	(r1)->rdatahash == (r2)->rdatahash   && \
155 	SameRDataBody((r1), &(r2)->rdata->u, SameDomainName))
156 
157 // A given RRType answers a QuestionType if RRType is CNAME, or types match, or QuestionType is ANY,
158 // or the RRType is NSEC and positively asserts the nonexistence of the type being requested
159 #define RRTypeAnswersQuestionType(R,Q) ((R)->rrtype == kDNSType_CNAME || (R)->rrtype == (Q) || (Q) == kDNSQType_ANY || RRAssertsNonexistence((R),(Q)))
160 #define RRAssertsNonexistence(R,T) ((R)->rrtype == kDNSType_NSEC && (T) < kDNSQType_ANY && !((R)->rdata->u.nsec.bitmap[(T)>>3] & (128 >> ((T)&7))))
161 
162 extern mDNSu32 RDataHashValue(const ResourceRecord *const rr);
163 extern mDNSBool SameRDataBody(const ResourceRecord *const r1, const RDataBody *const r2, DomainNameComparisonFn *samename);
164 extern mDNSBool SameNameRecordAnswersQuestion(const ResourceRecord *const rr, const DNSQuestion *const q);
165 extern mDNSBool ResourceRecordAnswersQuestion(const ResourceRecord *const rr, const DNSQuestion *const q);
166 extern mDNSBool AnyTypeRecordAnswersQuestion (const ResourceRecord *const rr, const DNSQuestion *const q);
167 extern mDNSBool ResourceRecordAnswersUnicastResponse(const ResourceRecord *const rr, const DNSQuestion *const q);
168 extern mDNSBool LocalOnlyRecordAnswersQuestion(AuthRecord *const rr, const DNSQuestion *const q);
169 extern mDNSu16 GetRDLength(const ResourceRecord *const rr, mDNSBool estimate);
170 extern mDNSBool ValidateRData(const mDNSu16 rrtype, const mDNSu16 rdlength, const RData *const rd);
171 
172 #define GetRRDomainNameTarget(RR) (                                                                          \
173 	((RR)->rrtype == kDNSType_NS || (RR)->rrtype == kDNSType_CNAME || (RR)->rrtype == kDNSType_PTR || (RR)->rrtype == kDNSType_DNAME) ? &(RR)->rdata->u.name        : \
174 	((RR)->rrtype == kDNSType_MX || (RR)->rrtype == kDNSType_AFSDB || (RR)->rrtype == kDNSType_RT  || (RR)->rrtype == kDNSType_KX   ) ? &(RR)->rdata->u.mx.exchange : \
175 	((RR)->rrtype == kDNSType_SRV                                  ) ? &(RR)->rdata->u.srv.target : mDNSNULL )
176 
177 #define LocalRecordReady(X) ((X)->resrec.RecordType != kDNSRecordTypeUnique)
178 
179 // ***************************************************************************
180 #if COMPILER_LIKES_PRAGMA_MARK
181 #pragma mark -
182 #pragma mark - DNS Message Creation Functions
183 #endif
184 
185 extern void InitializeDNSMessage(DNSMessageHeader *h, mDNSOpaque16 id, mDNSOpaque16 flags);
186 extern const mDNSu8 *FindCompressionPointer(const mDNSu8 *const base, const mDNSu8 *const end, const mDNSu8 *const domname);
187 extern mDNSu8 *putDomainNameAsLabels(const DNSMessage *const msg, mDNSu8 *ptr, const mDNSu8 *const limit, const domainname *const name);
188 extern mDNSu8 *putRData(const DNSMessage *const msg, mDNSu8 *ptr, const mDNSu8 *const limit, const ResourceRecord *const rr);
189 
190 // If we have a single large record to put in the packet, then we allow the packet to be up to 9K bytes,
191 // but in the normal case we try to keep the packets below 1500 to avoid IP fragmentation on standard Ethernet
192 
193 #define AllowedRRSpace(msg) (((msg)->h.numAnswers || (msg)->h.numAuthorities || (msg)->h.numAdditionals) ? NormalMaxDNSMessageData : AbsoluteMaxDNSMessageData)
194 
195 extern mDNSu8 *PutResourceRecordTTLWithLimit(DNSMessage *const msg, mDNSu8 *ptr, mDNSu16 *count, ResourceRecord *rr, mDNSu32 ttl, const mDNSu8 *limit);
196 
197 #define PutResourceRecordTTL(msg, ptr, count, rr, ttl) \
198 	PutResourceRecordTTLWithLimit((msg), (ptr), (count), (rr), (ttl), (msg)->data + AllowedRRSpace(msg))
199 
200 #define PutResourceRecordTTLJumbo(msg, ptr, count, rr, ttl) \
201 	PutResourceRecordTTLWithLimit((msg), (ptr), (count), (rr), (ttl), (msg)->data + AbsoluteMaxDNSMessageData)
202 
203 #define PutResourceRecord(MSG, P, C, RR) PutResourceRecordTTL((MSG), (P), (C), (RR), (RR)->rroriginalttl)
204 
205 // The PutRR_OS variants assume a local variable 'm', put build the packet at m->omsg,
206 // and assume a local variable 'OwnerRecordSpace' indicating how many bytes (if any) to reserve to add an OWNER option at the end
207 #define PutRR_OS_TTL(ptr, count, rr, ttl) \
208 	PutResourceRecordTTLWithLimit(&m->omsg, (ptr), (count), (rr), (ttl), m->omsg.data + AllowedRRSpace(&m->omsg) - OwnerRecordSpace)
209 
210 #define PutRR_OS(P, C, RR) PutRR_OS_TTL((P), (C), (RR), (RR)->rroriginalttl)
211 
212 extern mDNSu8 *putQuestion(DNSMessage *const msg, mDNSu8 *ptr, const mDNSu8 *const limit, const domainname *const name, mDNSu16 rrtype, mDNSu16 rrclass);
213 extern mDNSu8 *putZone(DNSMessage *const msg, mDNSu8 *ptr, mDNSu8 *limit, const domainname *zone, mDNSOpaque16 zoneClass);
214 extern mDNSu8 *putPrereqNameNotInUse(const domainname *const name, DNSMessage *const msg, mDNSu8 *const ptr, mDNSu8 *const end);
215 extern mDNSu8 *putDeletionRecord(DNSMessage *msg, mDNSu8 *ptr, ResourceRecord *rr);
216 extern mDNSu8 *putDeletionRecordWithLimit(DNSMessage *msg, mDNSu8 *ptr, ResourceRecord *rr, mDNSu8 *limit);
217 extern mDNSu8 *putDeleteRRSetWithLimit(DNSMessage *msg, mDNSu8 *ptr, const domainname *name, mDNSu16 rrtype, mDNSu8 *limit);
218 extern mDNSu8 *putDeleteAllRRSets(DNSMessage *msg, mDNSu8 *ptr, const domainname *name);
219 extern mDNSu8 *putUpdateLease(DNSMessage *msg, mDNSu8 *end, mDNSu32 lease);
220 extern mDNSu8 *putUpdateLeaseWithLimit(DNSMessage *msg, mDNSu8 *ptr, mDNSu32 lease, mDNSu8 *limit);
221 
222 extern mDNSu8 *putHINFO(const mDNS *const m, DNSMessage *const msg, mDNSu8 *ptr, DomainAuthInfo *authInfo, mDNSu8 *limit);
223 
224 // ***************************************************************************
225 #if COMPILER_LIKES_PRAGMA_MARK
226 #pragma mark -
227 #pragma mark - DNS Message Parsing Functions
228 #endif
229 
230 #define AuthHashSlot(X) (DomainNameHashValue(X) % AUTH_HASH_SLOTS)
231 #define HashSlot(X) (DomainNameHashValue(X) % CACHE_HASH_SLOTS)
232 extern mDNSu32 DomainNameHashValue(const domainname *const name);
233 extern void SetNewRData(ResourceRecord *const rr, RData *NewRData, mDNSu16 rdlength);
234 extern const mDNSu8 *skipDomainName(const DNSMessage *const msg, const mDNSu8 *ptr, const mDNSu8 *const end);
235 extern const mDNSu8 *getDomainName(const DNSMessage *const msg, const mDNSu8 *ptr, const mDNSu8 *const end,
236 	domainname *const name);
237 extern const mDNSu8 *skipResourceRecord(const DNSMessage *msg, const mDNSu8 *ptr, const mDNSu8 *end);
238 extern const mDNSu8 *GetLargeResourceRecord(mDNS *const m, const DNSMessage * const msg, const mDNSu8 *ptr,
239     const mDNSu8 * end, const mDNSInterfaceID InterfaceID, mDNSu8 RecordType, LargeCacheRecord *const largecr);
240 extern const mDNSu8 *skipQuestion(const DNSMessage *msg, const mDNSu8 *ptr, const mDNSu8 *end);
241 extern const mDNSu8 *getQuestion(const DNSMessage *msg, const mDNSu8 *ptr, const mDNSu8 *end, const mDNSInterfaceID InterfaceID,
242 	DNSQuestion *question);
243 extern const mDNSu8 *LocateAnswers(const DNSMessage *const msg, const mDNSu8 *const end);
244 extern const mDNSu8 *LocateAuthorities(const DNSMessage *const msg, const mDNSu8 *const end);
245 extern const mDNSu8 *LocateAdditionals(const DNSMessage *const msg, const mDNSu8 *const end);
246 extern const mDNSu8 *LocateOptRR(const DNSMessage *const msg, const mDNSu8 *const end, int minsize);
247 extern const rdataOPT *GetLLQOptData(mDNS *const m, const DNSMessage *const msg, const mDNSu8 *const end);
248 extern mDNSu32 GetPktLease(mDNS *m, DNSMessage *msg, const mDNSu8 *end);
249 extern void DumpPacket(mDNS *const m, mStatus status, mDNSBool sent, char *transport,
250 	const mDNSAddr *srcaddr, mDNSIPPort srcport,
251 	const mDNSAddr *dstaddr, mDNSIPPort dstport, const DNSMessage *const msg, const mDNSu8 *const end);
252 
253 // ***************************************************************************
254 #if COMPILER_LIKES_PRAGMA_MARK
255 #pragma mark -
256 #pragma mark - Packet Sending Functions
257 #endif
258 
259 extern mStatus mDNSSendDNSMessage(mDNS *const m, DNSMessage *const msg, mDNSu8 *end,
260 	mDNSInterfaceID InterfaceID, UDPSocket *src, const mDNSAddr *dst, mDNSIPPort dstport, TCPSocket *sock, DomainAuthInfo *authInfo);
261 
262 // ***************************************************************************
263 #if COMPILER_LIKES_PRAGMA_MARK
264 #pragma mark -
265 #pragma mark - RR List Management & Task Management
266 #endif
267 
268 extern void ShowTaskSchedulingError(mDNS *const m);
269 extern void mDNS_Lock_(mDNS *const m, const char * const functionname);
270 extern void mDNS_Unlock_(mDNS *const m, const char * const functionname);
271 
272 #if defined(_WIN32)
273  #define __func__ __FUNCTION__
274 #endif
275 
276 #define mDNS_Lock(X) mDNS_Lock_((X), __func__)
277 
278 #define mDNS_Unlock(X) mDNS_Unlock_((X), __func__)
279 
280 #define mDNS_DropLockBeforeCallback() do { m->mDNS_reentrancy++; \
281 	if (m->mDNS_busy != m->mDNS_reentrancy) LogMsg("%s: Locking Failure! mDNS_busy (%ld) != mDNS_reentrancy (%ld)", __func__, m->mDNS_busy, m->mDNS_reentrancy); \
282 	} while (0)
283 
284 #define mDNS_ReclaimLockAfterCallback() do { \
285 	if (m->mDNS_busy != m->mDNS_reentrancy) LogMsg("%s: Unlocking Failure! mDNS_busy (%ld) != mDNS_reentrancy (%ld)", __func__, m->mDNS_busy, m->mDNS_reentrancy); \
286 	m->mDNS_reentrancy--; } while (0)
287 
288 #ifdef	__cplusplus
289 	}
290 #endif
291 
292 #endif // __DNSCOMMON_H_
293