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1 /*
2 * Copyright (c) 1996,1999 by Internet Software Consortium.
3 *
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
7 *
8 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
9 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
10 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
11 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
12 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
13 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
14 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
15 * SOFTWARE.
16 */
17
18 #ifndef lint
19 static const char rcsid[] = "$Id: ns_parse.c,v 1.3.2.1 2003/06/27 03:51:42 marka Exp $";
20 #endif
21
22 /* Import. */
23
24 /* #include "port_before.h" */
25 #include "config.h"
26
27 #include <sys/types.h>
28
29 #include <netinet/in.h>
30 #include "arpa_nameser.h"
31
32 #include <errno.h>
33 /* #include <resolv.h> */
34 #ifdef HAVE_STRING_H
35 # include <string.h> /* strstr / strdup */
36 #else
37 # ifdef HAVE_STRINGS_H
38 # include <strings.h> /* strstr / strdup */
39 # endif
40 #endif
41
42
43 /* #include "port_after.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 (0)
52
53 /* Public. */
54
55 /* These need to be in the same order as the nres.h:ns_flag enum. */
56 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
75 int
76 ns_skiprr(const u_char *ptr, const u_char *eom, ns_sect section, int count) {
77 const u_char *optr = ptr;
78
79 for ((void)NULL; count > 0; count--) {
80 int b, rdlength;
81
82 b = dn_skipname(ptr, eom);
83 if (b < 0)
84 RETERR(EMSGSIZE);
85 ptr += b/*Name*/ + NS_INT16SZ/*Type*/ + NS_INT16SZ/*Class*/;
86 if (section != ns_s_qd) {
87 if (ptr + NS_INT32SZ + NS_INT16SZ > eom)
88 RETERR(EMSGSIZE);
89 ptr += NS_INT32SZ/*TTL*/;
90 NS_GET16(rdlength, ptr);
91 ptr += rdlength/*RData*/;
92 }
93 }
94 if (ptr > eom)
95 RETERR(EMSGSIZE);
96 return (ptr - optr);
97 }
98
99 int
100 ns_initparse(const u_char *msg, int msglen, ns_msg *handle) {
101 const u_char *eom = msg + msglen;
102 int i;
103
104 memset(handle, 0x5e, sizeof *handle);
105 handle->_msg = msg;
106 handle->_eom = eom;
107 if (msg + NS_INT16SZ > eom)
108 RETERR(EMSGSIZE);
109 NS_GET16(handle->_id, msg);
110 if (msg + NS_INT16SZ > eom)
111 RETERR(EMSGSIZE);
112 NS_GET16(handle->_flags, msg);
113 for (i = 0; i < ns_s_max; i++) {
114 if (msg + NS_INT16SZ > eom)
115 RETERR(EMSGSIZE);
116 NS_GET16(handle->_counts[i], msg);
117 }
118 for (i = 0; i < ns_s_max; i++)
119 if (handle->_counts[i] == 0)
120 handle->_sections[i] = NULL;
121 else {
122 int b = ns_skiprr(msg, eom, (ns_sect)i,
123 handle->_counts[i]);
124
125 if (b < 0)
126 return (-1);
127 handle->_sections[i] = msg;
128 msg += b;
129 }
130 if (msg != eom)
131 RETERR(EMSGSIZE);
132 setsection(handle, ns_s_max);
133 return (0);
134 }
135
136 int
137 ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr) {
138 int b;
139 int tmp;
140
141 /* Make section right. */
142 if ((tmp = section) < 0 || section >= ns_s_max)
143 RETERR(ENODEV);
144 if (section != handle->_sect)
145 setsection(handle, section);
146
147 /* Make rrnum right. */
148 if (rrnum == -1)
149 rrnum = handle->_rrnum;
150 if (rrnum < 0 || rrnum >= handle->_counts[(int)section])
151 RETERR(ENODEV);
152 if (rrnum < handle->_rrnum)
153 setsection(handle, section);
154 if (rrnum > handle->_rrnum) {
155 b = ns_skiprr(handle->_msg_ptr, handle->_eom, section,
156 rrnum - handle->_rrnum);
157
158 if (b < 0)
159 return (-1);
160 handle->_msg_ptr += b;
161 handle->_rrnum = rrnum;
162 }
163
164 /* Do the parse. */
165 b = dn_expand(handle->_msg, handle->_eom,
166 handle->_msg_ptr, rr->name, NS_MAXDNAME);
167 if (b < 0)
168 return (-1);
169 handle->_msg_ptr += b;
170 if (handle->_msg_ptr + NS_INT16SZ + NS_INT16SZ > handle->_eom)
171 RETERR(EMSGSIZE);
172 NS_GET16(rr->type, handle->_msg_ptr);
173 NS_GET16(rr->rr_class, handle->_msg_ptr);
174 if (section == ns_s_qd) {
175 rr->ttl = 0;
176 rr->rdlength = 0;
177 rr->rdata = NULL;
178 } else {
179 if (handle->_msg_ptr + NS_INT32SZ + NS_INT16SZ > handle->_eom)
180 RETERR(EMSGSIZE);
181 NS_GET32(rr->ttl, handle->_msg_ptr);
182 NS_GET16(rr->rdlength, handle->_msg_ptr);
183 if (handle->_msg_ptr + rr->rdlength > handle->_eom)
184 RETERR(EMSGSIZE);
185 rr->rdata = handle->_msg_ptr;
186 handle->_msg_ptr += rr->rdlength;
187 }
188 if (++handle->_rrnum > handle->_counts[(int)section])
189 setsection(handle, (ns_sect)((int)section + 1));
190
191 /* All done. */
192 return (0);
193 }
194
195 /* Private. */
196
197 static void
198 setsection(ns_msg *msg, ns_sect sect) {
199 msg->_sect = sect;
200 if (sect == ns_s_max) {
201 msg->_rrnum = -1;
202 msg->_msg_ptr = NULL;
203 } else {
204 msg->_rrnum = 0;
205 msg->_msg_ptr = msg->_sections[(int)sect];
206 }
207 }