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 struct _ns_flagdata { int mask, shift; };
56
57 /* These need to be in the same order as the nres.h:ns_flag enum. */
58 const struct _ns_flagdata _ns_flagdata[16] = {
59 { 0x8000, 15 }, /* qr. */
60 { 0x7800, 11 }, /* opcode. */
61 { 0x0400, 10 }, /* aa. */
62 { 0x0200, 9 }, /* tc. */
63 { 0x0100, 8 }, /* rd. */
64 { 0x0080, 7 }, /* ra. */
65 { 0x0040, 6 }, /* z. */
66 { 0x0020, 5 }, /* ad. */
67 { 0x0010, 4 }, /* cd. */
68 { 0x000f, 0 }, /* rcode. */
69 { 0x0000, 0 }, /* expansion (1/6). */
70 { 0x0000, 0 }, /* expansion (2/6). */
71 { 0x0000, 0 }, /* expansion (3/6). */
72 { 0x0000, 0 }, /* expansion (4/6). */
73 { 0x0000, 0 }, /* expansion (5/6). */
74 { 0x0000, 0 }, /* expansion (6/6). */
75 };
76
ns_msg_getflag(ns_msg handle,int flag)77 int ns_msg_getflag(ns_msg handle, int flag) {
78 return((u_int32_t)((handle)._flags & _ns_flagdata[flag].mask) >> _ns_flagdata[flag].shift);
79 }
80
81 int
ns_skiprr(const u_char * ptr,const u_char * eom,ns_sect section,int count)82 ns_skiprr(const u_char *ptr, const u_char *eom, ns_sect section, int count) {
83 const u_char *optr = ptr;
84
85 for (; count > 0; count--) {
86 int b, rdlength;
87
88 b = dn_skipname(ptr, eom);
89 if (b < 0)
90 RETERR(EMSGSIZE);
91 ptr += b/*Name*/ + NS_INT16SZ/*Type*/ + NS_INT16SZ/*Class*/;
92 if (section != ns_s_qd) {
93 if (ptr + NS_INT32SZ + NS_INT16SZ > eom)
94 RETERR(EMSGSIZE);
95 ptr += NS_INT32SZ/*TTL*/;
96 NS_GET16(rdlength, ptr);
97 ptr += rdlength/*RData*/;
98 }
99 }
100 if (ptr > eom)
101 RETERR(EMSGSIZE);
102 _DIAGASSERT(__type_fit(int, ptr - optr));
103 return (int)(ptr - optr);
104 }
105
106 int
ns_initparse(const u_char * msg,int msglen,ns_msg * handle)107 ns_initparse(const u_char *msg, int msglen, ns_msg *handle) {
108 const u_char *eom = msg + msglen;
109 int i;
110
111 handle->_msg = msg;
112 handle->_eom = eom;
113 if (msg + NS_INT16SZ > eom)
114 RETERR(EMSGSIZE);
115 NS_GET16(handle->_id, msg);
116 if (msg + NS_INT16SZ > eom)
117 RETERR(EMSGSIZE);
118 NS_GET16(handle->_flags, msg);
119 for (i = 0; i < ns_s_max; i++) {
120 if (msg + NS_INT16SZ > eom)
121 RETERR(EMSGSIZE);
122 NS_GET16(handle->_counts[i], msg);
123 }
124 for (i = 0; i < ns_s_max; i++)
125 if (handle->_counts[i] == 0)
126 handle->_sections[i] = NULL;
127 else {
128 int b = ns_skiprr(msg, eom, (ns_sect)i,
129 handle->_counts[i]);
130
131 if (b < 0)
132 return (-1);
133 handle->_sections[i] = msg;
134 msg += b;
135 }
136 if (msg != eom)
137 RETERR(EMSGSIZE);
138 setsection(handle, ns_s_max);
139 return (0);
140 }
141
142 int
ns_parserr(ns_msg * handle,ns_sect section,int rrnum,ns_rr * rr)143 ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr) {
144 int b;
145 int tmp;
146
147 /* Make section right. */
148 tmp = section;
149 if (tmp < 0 || section >= ns_s_max)
150 RETERR(ENODEV);
151 if (section != handle->_sect)
152 setsection(handle, section);
153
154 /* Make rrnum right. */
155 if (rrnum == -1)
156 rrnum = handle->_rrnum;
157 if (rrnum < 0 || rrnum >= handle->_counts[(int)section])
158 RETERR(ENODEV);
159 if (rrnum < handle->_rrnum)
160 setsection(handle, section);
161 if (rrnum > handle->_rrnum) {
162 b = ns_skiprr(handle->_msg_ptr, handle->_eom, section,
163 rrnum - handle->_rrnum);
164
165 if (b < 0)
166 return (-1);
167 handle->_msg_ptr += b;
168 handle->_rrnum = rrnum;
169 }
170
171 /* Do the parse. */
172 b = dn_expand(handle->_msg, handle->_eom,
173 handle->_msg_ptr, rr->name, NS_MAXDNAME);
174 if (b < 0)
175 return (-1);
176 handle->_msg_ptr += b;
177 if (handle->_msg_ptr + NS_INT16SZ + NS_INT16SZ > handle->_eom)
178 RETERR(EMSGSIZE);
179 NS_GET16(rr->type, handle->_msg_ptr);
180 NS_GET16(rr->rr_class, handle->_msg_ptr);
181 if (section == ns_s_qd) {
182 rr->ttl = 0;
183 rr->rdlength = 0;
184 rr->rdata = NULL;
185 } else {
186 if (handle->_msg_ptr + NS_INT32SZ + NS_INT16SZ > handle->_eom)
187 RETERR(EMSGSIZE);
188 NS_GET32(rr->ttl, handle->_msg_ptr);
189 NS_GET16(rr->rdlength, handle->_msg_ptr);
190 if (handle->_msg_ptr + rr->rdlength > handle->_eom)
191 RETERR(EMSGSIZE);
192 rr->rdata = handle->_msg_ptr;
193 handle->_msg_ptr += rr->rdlength;
194 }
195 if (++handle->_rrnum > handle->_counts[(int)section])
196 setsection(handle, (ns_sect)((int)section + 1));
197
198 /* All done. */
199 return (0);
200 }
201
202 /*
203 * This is identical to the above but uses network-format (uncompressed) names.
204 */
205 int
ns_parserr2(ns_msg * handle,ns_sect section,int rrnum,ns_rr2 * rr)206 ns_parserr2(ns_msg *handle, ns_sect section, int rrnum, ns_rr2 *rr) {
207 int b;
208 int tmp;
209
210 /* Make section right. */
211 tmp = section;
212 if (tmp < 0 || section >= ns_s_max)
213 RETERR(ENODEV);
214 if (section != handle->_sect)
215 setsection(handle, section);
216
217 /* Make rrnum right. */
218 if (rrnum == -1)
219 rrnum = handle->_rrnum;
220 if (rrnum < 0 || rrnum >= handle->_counts[(int)section])
221 RETERR(ENODEV);
222 if (rrnum < handle->_rrnum)
223 setsection(handle, section);
224 if (rrnum > handle->_rrnum) {
225 b = ns_skiprr(handle->_msg_ptr, handle->_eom, section,
226 rrnum - handle->_rrnum);
227
228 if (b < 0)
229 return (-1);
230 handle->_msg_ptr += b;
231 handle->_rrnum = rrnum;
232 }
233
234 /* Do the parse. */
235 b = ns_name_unpack2(handle->_msg, handle->_eom, handle->_msg_ptr,
236 rr->nname, NS_MAXNNAME, &rr->nnamel);
237 if (b < 0)
238 return (-1);
239 handle->_msg_ptr += b;
240 if (handle->_msg_ptr + NS_INT16SZ + NS_INT16SZ > handle->_eom)
241 RETERR(EMSGSIZE);
242 NS_GET16(rr->type, handle->_msg_ptr);
243 NS_GET16(rr->rr_class, handle->_msg_ptr);
244 if (section == ns_s_qd) {
245 rr->ttl = 0;
246 rr->rdlength = 0;
247 rr->rdata = NULL;
248 } else {
249 if (handle->_msg_ptr + NS_INT32SZ + NS_INT16SZ > handle->_eom)
250 RETERR(EMSGSIZE);
251 NS_GET32(rr->ttl, handle->_msg_ptr);
252 NS_GET16(rr->rdlength, handle->_msg_ptr);
253 if (handle->_msg_ptr + rr->rdlength > handle->_eom)
254 RETERR(EMSGSIZE);
255 rr->rdata = handle->_msg_ptr;
256 handle->_msg_ptr += rr->rdlength;
257 }
258 if (++handle->_rrnum > handle->_counts[(int)section])
259 setsection(handle, (ns_sect)((int)section + 1));
260
261 /* All done. */
262 return (0);
263 }
264
265 /* Private. */
266
267 static void
setsection(ns_msg * msg,ns_sect sect)268 setsection(ns_msg *msg, ns_sect sect) {
269 msg->_sect = sect;
270 if (sect == ns_s_max) {
271 msg->_rrnum = -1;
272 msg->_msg_ptr = NULL;
273 } else {
274 msg->_rrnum = 0;
275 msg->_msg_ptr = msg->_sections[(int)sect];
276 }
277 }
278