1 /*-
2 * SPDX-License-Identifier: ISC
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 /* Import. */
21
22 #include "port_before.h"
23
24 #include <sys/types.h>
25
26 #include <netinet/in.h>
27 #include <arpa/nameser.h>
28
29 #include <errno.h>
30 #include <resolv.h>
31 #include <string.h>
32
33 #include "port_after.h"
34
35 /* Forward. */
36
37 static void setsection(ns_msg *msg, ns_sect sect);
38
39 /* Macros. */
40
41 #define RETERR(err) do { errno = (err); return (-1); } while (0)
42
43 #define PARSE_FMT_PRESO 0 /* Parse using presentation-format names */
44 #define PARSE_FMT_WIRE 1 /* Parse using network-format names */
45
46 /* Public. */
47
48 /* These need to be in the same order as the nres.h:ns_flag enum. */
49 struct _ns_flagdata _ns_flagdata[16] = {
50 { 0x8000, 15 }, /*%< qr. */
51 { 0x7800, 11 }, /*%< opcode. */
52 { 0x0400, 10 }, /*%< aa. */
53 { 0x0200, 9 }, /*%< tc. */
54 { 0x0100, 8 }, /*%< rd. */
55 { 0x0080, 7 }, /*%< ra. */
56 { 0x0040, 6 }, /*%< z. */
57 { 0x0020, 5 }, /*%< ad. */
58 { 0x0010, 4 }, /*%< cd. */
59 { 0x000f, 0 }, /*%< rcode. */
60 { 0x0000, 0 }, /*%< expansion (1/6). */
61 { 0x0000, 0 }, /*%< expansion (2/6). */
62 { 0x0000, 0 }, /*%< expansion (3/6). */
63 { 0x0000, 0 }, /*%< expansion (4/6). */
64 { 0x0000, 0 }, /*%< expansion (5/6). */
65 { 0x0000, 0 }, /*%< expansion (6/6). */
66 };
67
ns_msg_getflag(ns_msg handle,int flag)68 int ns_msg_getflag(ns_msg handle, int flag) {
69 return(((handle)._flags & _ns_flagdata[flag].mask) >> _ns_flagdata[flag].shift);
70 }
71
72 int
ns_skiprr(const u_char * ptr,const u_char * eom,ns_sect section,int count)73 ns_skiprr(const u_char *ptr, const u_char *eom, ns_sect section, int count) {
74 const u_char *optr = ptr;
75
76 for ((void)NULL; count > 0; count--) {
77 int b, rdlength;
78
79 b = dn_skipname(ptr, eom);
80 if (b < 0)
81 RETERR(EMSGSIZE);
82 ptr += b/*Name*/ + NS_INT16SZ/*Type*/ + NS_INT16SZ/*Class*/;
83 if (section != ns_s_qd) {
84 if (ptr + NS_INT32SZ + NS_INT16SZ > eom)
85 RETERR(EMSGSIZE);
86 ptr += NS_INT32SZ/*TTL*/;
87 NS_GET16(rdlength, ptr);
88 ptr += rdlength/*RData*/;
89 }
90 }
91 if (ptr > eom)
92 RETERR(EMSGSIZE);
93 return (ptr - optr);
94 }
95
96 int
ns_initparse(const u_char * msg,int msglen,ns_msg * handle)97 ns_initparse(const u_char *msg, int msglen, ns_msg *handle) {
98 const u_char *eom = msg + msglen;
99 int i;
100
101 handle->_msg = msg;
102 handle->_eom = eom;
103 if (msg + NS_INT16SZ > eom)
104 RETERR(EMSGSIZE);
105 NS_GET16(handle->_id, msg);
106 if (msg + NS_INT16SZ > eom)
107 RETERR(EMSGSIZE);
108 NS_GET16(handle->_flags, msg);
109 for (i = 0; i < ns_s_max; i++) {
110 if (msg + NS_INT16SZ > eom)
111 RETERR(EMSGSIZE);
112 NS_GET16(handle->_counts[i], msg);
113 }
114 for (i = 0; i < ns_s_max; i++)
115 if (handle->_counts[i] == 0)
116 handle->_sections[i] = NULL;
117 else {
118 int b = ns_skiprr(msg, eom, (ns_sect)i,
119 handle->_counts[i]);
120
121 if (b < 0)
122 return (-1);
123 handle->_sections[i] = msg;
124 msg += b;
125 }
126 if (msg != eom)
127 RETERR(EMSGSIZE);
128 setsection(handle, ns_s_max);
129 return (0);
130 }
131
132 int
ns_parserr(ns_msg * handle,ns_sect section,int rrnum,ns_rr * rr)133 ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr) {
134 int b;
135 int tmp;
136
137 /* Make section right. */
138 tmp = section;
139 if (tmp < 0 || section >= ns_s_max)
140 RETERR(ENODEV);
141 if (section != handle->_sect)
142 setsection(handle, section);
143
144 /* Make rrnum right. */
145 if (rrnum == -1)
146 rrnum = handle->_rrnum;
147 if (rrnum < 0 || rrnum >= handle->_counts[(int)section])
148 RETERR(ENODEV);
149 if (rrnum < handle->_rrnum)
150 setsection(handle, section);
151 if (rrnum > handle->_rrnum) {
152 b = ns_skiprr(handle->_msg_ptr, handle->_eom, section,
153 rrnum - handle->_rrnum);
154
155 if (b < 0)
156 return (-1);
157 handle->_msg_ptr += b;
158 handle->_rrnum = rrnum;
159 }
160
161 /* Do the parse. */
162 b = dn_expand(handle->_msg, handle->_eom,
163 handle->_msg_ptr, rr->name, NS_MAXDNAME);
164 if (b < 0)
165 return (-1);
166 handle->_msg_ptr += b;
167 if (handle->_msg_ptr + NS_INT16SZ + NS_INT16SZ > handle->_eom)
168 RETERR(EMSGSIZE);
169 NS_GET16(rr->type, handle->_msg_ptr);
170 NS_GET16(rr->rr_class, handle->_msg_ptr);
171 if (section == ns_s_qd) {
172 rr->ttl = 0;
173 rr->rdlength = 0;
174 rr->rdata = NULL;
175 } else {
176 if (handle->_msg_ptr + NS_INT32SZ + NS_INT16SZ > handle->_eom)
177 RETERR(EMSGSIZE);
178 NS_GET32(rr->ttl, handle->_msg_ptr);
179 NS_GET16(rr->rdlength, handle->_msg_ptr);
180 if (handle->_msg_ptr + rr->rdlength > handle->_eom)
181 RETERR(EMSGSIZE);
182 rr->rdata = handle->_msg_ptr;
183 handle->_msg_ptr += rr->rdlength;
184 }
185 if (++handle->_rrnum > handle->_counts[(int)section])
186 setsection(handle, (ns_sect)((int)section + 1));
187
188 /* All done. */
189 return (0);
190 }
191
192 /*
193 * This is identical to the above but uses network-format (uncompressed) names.
194 */
195 int
ns_parserr2(ns_msg * handle,ns_sect section,int rrnum,ns_rr2 * rr)196 ns_parserr2(ns_msg *handle, ns_sect section, int rrnum, ns_rr2 *rr) {
197 int b;
198 int tmp;
199
200 /* Make section right. */
201 if ((tmp = section) < 0 || section >= ns_s_max)
202 RETERR(ENODEV);
203 if (section != handle->_sect)
204 setsection(handle, section);
205
206 /* Make rrnum right. */
207 if (rrnum == -1)
208 rrnum = handle->_rrnum;
209 if (rrnum < 0 || rrnum >= handle->_counts[(int)section])
210 RETERR(ENODEV);
211 if (rrnum < handle->_rrnum)
212 setsection(handle, section);
213 if (rrnum > handle->_rrnum) {
214 b = ns_skiprr(handle->_msg_ptr, handle->_eom, section,
215 rrnum - handle->_rrnum);
216
217 if (b < 0)
218 return (-1);
219 handle->_msg_ptr += b;
220 handle->_rrnum = rrnum;
221 }
222
223 /* Do the parse. */
224 b = ns_name_unpack2(handle->_msg, handle->_eom, handle->_msg_ptr,
225 rr->nname, NS_MAXNNAME, &rr->nnamel);
226 if (b < 0)
227 return (-1);
228 handle->_msg_ptr += b;
229 if (handle->_msg_ptr + NS_INT16SZ + NS_INT16SZ > handle->_eom)
230 RETERR(EMSGSIZE);
231 NS_GET16(rr->type, handle->_msg_ptr);
232 NS_GET16(rr->rr_class, handle->_msg_ptr);
233 if (section == ns_s_qd) {
234 rr->ttl = 0;
235 rr->rdlength = 0;
236 rr->rdata = NULL;
237 } else {
238 if (handle->_msg_ptr + NS_INT32SZ + NS_INT16SZ > handle->_eom)
239 RETERR(EMSGSIZE);
240 NS_GET32(rr->ttl, handle->_msg_ptr);
241 NS_GET16(rr->rdlength, handle->_msg_ptr);
242 if (handle->_msg_ptr + rr->rdlength > handle->_eom)
243 RETERR(EMSGSIZE);
244 rr->rdata = handle->_msg_ptr;
245 handle->_msg_ptr += rr->rdlength;
246 }
247 if (++handle->_rrnum > handle->_counts[(int)section])
248 setsection(handle, (ns_sect)((int)section + 1));
249
250 /* All done. */
251 return (0);
252 }
253
254 /* Private. */
255
256 static void
setsection(ns_msg * msg,ns_sect sect)257 setsection(ns_msg *msg, ns_sect sect) {
258 msg->_sect = sect;
259 if (sect == ns_s_max) {
260 msg->_rrnum = -1;
261 msg->_msg_ptr = NULL;
262 } else {
263 msg->_rrnum = 0;
264 msg->_msg_ptr = msg->_sections[(int)sect];
265 }
266 }
267
268 /*! \file */
269