1 /*	$NetBSD: ns_parse.c,v 1.9 2012/03/13 21:13:39 christos Exp $	*/
2 
3 /*
4  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
5  * Copyright (c) 1996,1999 by Internet Software Consortium.
6  *
7  * Permission to use, copy, modify, and distribute this software for any
8  * purpose with or without fee is hereby granted, provided that the above
9  * copyright notice and this permission notice appear in all copies.
10  *
11  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
12  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
14  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
17  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18  */
19 
20 #include <sys/cdefs.h>
21 #ifndef lint
22 #ifdef notdef
23 static const char rcsid[] = "Id: ns_parse.c,v 1.10 2009/01/23 19:59:16 each Exp";
24 #else
25 __RCSID("$NetBSD: ns_parse.c,v 1.9 2012/03/13 21:13:39 christos Exp $");
26 #endif
27 #endif
28 
29 /* Import. */
30 
31 #include <sys/types.h>
32 
33 #include <netinet/in.h>
34 #include <arpa/nameser.h>
35 
36 #include <assert.h>
37 #include <errno.h>
38 #ifdef ANDROID_CHANGES
39 #include "resolv_private.h"
40 #else
41 #include <resolv.h>
42 #endif
43 #include <string.h>
44 
45 /* Forward. */
46 
47 static void	setsection(ns_msg *msg, ns_sect sect);
48 
49 /* Macros. */
50 
51 #define RETERR(err) do { errno = (err); return (-1); } while (/*NOTREACHED*//*CONSTCOND*/0)
52 
53 /* Public. */
54 
55 /* These need to be in the same order as the nres.h:ns_flag enum. */
56 const struct _ns_flagdata _ns_flagdata[16] = {
57 	{ 0x8000, 15 },		/* qr. */
58 	{ 0x7800, 11 },		/* opcode. */
59 	{ 0x0400, 10 },		/* aa. */
60 	{ 0x0200, 9 },		/* tc. */
61 	{ 0x0100, 8 },		/* rd. */
62 	{ 0x0080, 7 },		/* ra. */
63 	{ 0x0040, 6 },		/* z. */
64 	{ 0x0020, 5 },		/* ad. */
65 	{ 0x0010, 4 },		/* cd. */
66 	{ 0x000f, 0 },		/* rcode. */
67 	{ 0x0000, 0 },		/* expansion (1/6). */
68 	{ 0x0000, 0 },		/* expansion (2/6). */
69 	{ 0x0000, 0 },		/* expansion (3/6). */
70 	{ 0x0000, 0 },		/* expansion (4/6). */
71 	{ 0x0000, 0 },		/* expansion (5/6). */
72 	{ 0x0000, 0 },		/* expansion (6/6). */
73 };
74 
ns_msg_getflag(ns_msg handle,int flag)75 int ns_msg_getflag(ns_msg handle, int flag) {
76 	return((u_int32_t)((handle)._flags & _ns_flagdata[flag].mask) >> _ns_flagdata[flag].shift);
77 }
78 
79 int
ns_skiprr(const u_char * ptr,const u_char * eom,ns_sect section,int count)80 ns_skiprr(const u_char *ptr, const u_char *eom, ns_sect section, int count) {
81 	const u_char *optr = ptr;
82 
83 	for (; count > 0; count--) {
84 		int b, rdlength;
85 
86 		b = dn_skipname(ptr, eom);
87 		if (b < 0)
88 			RETERR(EMSGSIZE);
89 		ptr += b/*Name*/ + NS_INT16SZ/*Type*/ + NS_INT16SZ/*Class*/;
90 		if (section != ns_s_qd) {
91 			if (ptr + NS_INT32SZ + NS_INT16SZ > eom)
92 				RETERR(EMSGSIZE);
93 			ptr += NS_INT32SZ/*TTL*/;
94 			NS_GET16(rdlength, ptr);
95 			ptr += rdlength/*RData*/;
96 		}
97 	}
98 	if (ptr > eom)
99 		RETERR(EMSGSIZE);
100 	_DIAGASSERT(__type_fit(int, ptr - optr));
101 	return (int)(ptr - optr);
102 }
103 
104 int
ns_initparse(const u_char * msg,int msglen,ns_msg * handle)105 ns_initparse(const u_char *msg, int msglen, ns_msg *handle) {
106 	const u_char *eom = msg + msglen;
107 	int i;
108 
109 	handle->_msg = msg;
110 	handle->_eom = eom;
111 	if (msg + NS_INT16SZ > eom)
112 		RETERR(EMSGSIZE);
113 	NS_GET16(handle->_id, msg);
114 	if (msg + NS_INT16SZ > eom)
115 		RETERR(EMSGSIZE);
116 	NS_GET16(handle->_flags, msg);
117 	for (i = 0; i < ns_s_max; i++) {
118 		if (msg + NS_INT16SZ > eom)
119 			RETERR(EMSGSIZE);
120 		NS_GET16(handle->_counts[i], msg);
121 	}
122 	for (i = 0; i < ns_s_max; i++)
123 		if (handle->_counts[i] == 0)
124 			handle->_sections[i] = NULL;
125 		else {
126 			int b = ns_skiprr(msg, eom, (ns_sect)i,
127 					  handle->_counts[i]);
128 
129 			if (b < 0)
130 				return (-1);
131 			handle->_sections[i] = msg;
132 			msg += b;
133 		}
134 	if (msg != eom)
135 		RETERR(EMSGSIZE);
136 	setsection(handle, ns_s_max);
137 	return (0);
138 }
139 
140 int
ns_parserr(ns_msg * handle,ns_sect section,int rrnum,ns_rr * rr)141 ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr) {
142 	int b;
143 	int tmp;
144 
145 	/* Make section right. */
146 	tmp = section;
147 	if (tmp < 0 || section >= ns_s_max)
148 		RETERR(ENODEV);
149 	if (section != handle->_sect)
150 		setsection(handle, section);
151 
152 	/* Make rrnum right. */
153 	if (rrnum == -1)
154 		rrnum = handle->_rrnum;
155 	if (rrnum < 0 || rrnum >= handle->_counts[(int)section])
156 		RETERR(ENODEV);
157 	if (rrnum < handle->_rrnum)
158 		setsection(handle, section);
159 	if (rrnum > handle->_rrnum) {
160 		b = ns_skiprr(handle->_msg_ptr, handle->_eom, section,
161 			      rrnum - handle->_rrnum);
162 
163 		if (b < 0)
164 			return (-1);
165 		handle->_msg_ptr += b;
166 		handle->_rrnum = rrnum;
167 	}
168 
169 	/* Do the parse. */
170 	b = dn_expand(handle->_msg, handle->_eom,
171 		      handle->_msg_ptr, rr->name, NS_MAXDNAME);
172 	if (b < 0)
173 		return (-1);
174 	handle->_msg_ptr += b;
175 	if (handle->_msg_ptr + NS_INT16SZ + NS_INT16SZ > handle->_eom)
176 		RETERR(EMSGSIZE);
177 	NS_GET16(rr->type, handle->_msg_ptr);
178 	NS_GET16(rr->rr_class, handle->_msg_ptr);
179 	if (section == ns_s_qd) {
180 		rr->ttl = 0;
181 		rr->rdlength = 0;
182 		rr->rdata = NULL;
183 	} else {
184 		if (handle->_msg_ptr + NS_INT32SZ + NS_INT16SZ > handle->_eom)
185 			RETERR(EMSGSIZE);
186 		NS_GET32(rr->ttl, handle->_msg_ptr);
187 		NS_GET16(rr->rdlength, handle->_msg_ptr);
188 		if (handle->_msg_ptr + rr->rdlength > handle->_eom)
189 			RETERR(EMSGSIZE);
190 		rr->rdata = handle->_msg_ptr;
191 		handle->_msg_ptr += rr->rdlength;
192 	}
193 	if (++handle->_rrnum > handle->_counts[(int)section])
194 		setsection(handle, (ns_sect)((int)section + 1));
195 
196 	/* All done. */
197 	return (0);
198 }
199 
200 /*
201  * This is identical to the above but uses network-format (uncompressed) names.
202  */
203 int
ns_parserr2(ns_msg * handle,ns_sect section,int rrnum,ns_rr2 * rr)204 ns_parserr2(ns_msg *handle, ns_sect section, int rrnum, ns_rr2 *rr) {
205 	int b;
206 	int tmp;
207 
208 	/* Make section right. */
209 	tmp = section;
210 	if (tmp < 0 || section >= ns_s_max)
211 		RETERR(ENODEV);
212 	if (section != handle->_sect)
213 		setsection(handle, section);
214 
215 	/* Make rrnum right. */
216 	if (rrnum == -1)
217 		rrnum = handle->_rrnum;
218 	if (rrnum < 0 || rrnum >= handle->_counts[(int)section])
219 		RETERR(ENODEV);
220 	if (rrnum < handle->_rrnum)
221 		setsection(handle, section);
222 	if (rrnum > handle->_rrnum) {
223 		b = ns_skiprr(handle->_msg_ptr, handle->_eom, section,
224 			      rrnum - handle->_rrnum);
225 
226 		if (b < 0)
227 			return (-1);
228 		handle->_msg_ptr += b;
229 		handle->_rrnum = rrnum;
230 	}
231 
232 	/* Do the parse. */
233 	b = ns_name_unpack2(handle->_msg, handle->_eom, handle->_msg_ptr,
234 			    rr->nname, NS_MAXNNAME, &rr->nnamel);
235 	if (b < 0)
236 		return (-1);
237 	handle->_msg_ptr += b;
238 	if (handle->_msg_ptr + NS_INT16SZ + NS_INT16SZ > handle->_eom)
239 		RETERR(EMSGSIZE);
240 	NS_GET16(rr->type, handle->_msg_ptr);
241 	NS_GET16(rr->rr_class, handle->_msg_ptr);
242 	if (section == ns_s_qd) {
243 		rr->ttl = 0;
244 		rr->rdlength = 0;
245 		rr->rdata = NULL;
246 	} else {
247 		if (handle->_msg_ptr + NS_INT32SZ + NS_INT16SZ > handle->_eom)
248 			RETERR(EMSGSIZE);
249 		NS_GET32(rr->ttl, handle->_msg_ptr);
250 		NS_GET16(rr->rdlength, handle->_msg_ptr);
251 		if (handle->_msg_ptr + rr->rdlength > handle->_eom)
252 			RETERR(EMSGSIZE);
253 		rr->rdata = handle->_msg_ptr;
254 		handle->_msg_ptr += rr->rdlength;
255 	}
256 	if (++handle->_rrnum > handle->_counts[(int)section])
257 		setsection(handle, (ns_sect)((int)section + 1));
258 
259 	/* All done. */
260 	return (0);
261 }
262 
263 /* Private. */
264 
265 static void
setsection(ns_msg * msg,ns_sect sect)266 setsection(ns_msg *msg, ns_sect sect) {
267 	msg->_sect = sect;
268 	if (sect == ns_s_max) {
269 		msg->_rrnum = -1;
270 		msg->_msg_ptr = NULL;
271 	} else {
272 		msg->_rrnum = 0;
273 		msg->_msg_ptr = msg->_sections[(int)sect];
274 	}
275 }
276