1 /* $NetBSD: ns_parse.c,v 1.2 2004/05/20 20:35:05 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 1.3.2.1.4.1 2004/03/09 08:33:44 marka Exp";
24 #else
25 __RCSID("$NetBSD: ns_parse.c,v 1.2 2004/05/20 20:35:05 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 <errno.h>
37 #ifdef ANDROID_CHANGES
38 #include "resolv_private.h"
39 #else
40 #include <resolv.h>
41 #endif
42 #include <string.h>
43
44 /* Forward. */
45
46 static void setsection(ns_msg *msg, ns_sect sect);
47
48 /* Macros. */
49
50 #define RETERR(err) do { errno = (err); return (-1); } while (/*NOTREACHED*//*CONSTCOND*/0)
51
52 /* Public. */
53
54 /* These need to be in the same order as the nres.h:ns_flag enum. */
55 const struct _ns_flagdata _ns_flagdata[16] = {
56 { 0x8000, 15 }, /* qr. */
57 { 0x7800, 11 }, /* opcode. */
58 { 0x0400, 10 }, /* aa. */
59 { 0x0200, 9 }, /* tc. */
60 { 0x0100, 8 }, /* rd. */
61 { 0x0080, 7 }, /* ra. */
62 { 0x0040, 6 }, /* z. */
63 { 0x0020, 5 }, /* ad. */
64 { 0x0010, 4 }, /* cd. */
65 { 0x000f, 0 }, /* rcode. */
66 { 0x0000, 0 }, /* expansion (1/6). */
67 { 0x0000, 0 }, /* expansion (2/6). */
68 { 0x0000, 0 }, /* expansion (3/6). */
69 { 0x0000, 0 }, /* expansion (4/6). */
70 { 0x0000, 0 }, /* expansion (5/6). */
71 { 0x0000, 0 }, /* expansion (6/6). */
72 };
73
ns_msg_getflag(ns_msg handle,int flag)74 int ns_msg_getflag(ns_msg handle, int flag) {
75 return((u_int32_t)((handle)._flags & _ns_flagdata[flag].mask) >> _ns_flagdata[flag].shift);
76 }
77
78 int
ns_skiprr(const u_char * ptr,const u_char * eom,ns_sect section,int count)79 ns_skiprr(const u_char *ptr, const u_char *eom, ns_sect section, int count) {
80 const u_char *optr = ptr;
81
82 for (; count > 0; count--) {
83 int b, rdlength;
84
85 b = dn_skipname(ptr, eom);
86 if (b < 0)
87 RETERR(EMSGSIZE);
88 ptr += b/*Name*/ + NS_INT16SZ/*Type*/ + NS_INT16SZ/*Class*/;
89 if (section != ns_s_qd) {
90 if (ptr + NS_INT32SZ + NS_INT16SZ > eom)
91 RETERR(EMSGSIZE);
92 ptr += NS_INT32SZ/*TTL*/;
93 NS_GET16(rdlength, ptr);
94 ptr += rdlength/*RData*/;
95 }
96 }
97 if (ptr > eom)
98 RETERR(EMSGSIZE);
99 return (ptr - optr);
100 }
101
102 int
ns_initparse(const u_char * msg,int msglen,ns_msg * handle)103 ns_initparse(const u_char *msg, int msglen, ns_msg *handle) {
104 const u_char *eom = msg + msglen;
105 int i;
106
107 memset(handle, 0x5e, sizeof *handle);
108 handle->_msg = msg;
109 handle->_eom = eom;
110 if (msg + NS_INT16SZ > eom)
111 RETERR(EMSGSIZE);
112 NS_GET16(handle->_id, msg);
113 if (msg + NS_INT16SZ > eom)
114 RETERR(EMSGSIZE);
115 NS_GET16(handle->_flags, msg);
116 for (i = 0; i < ns_s_max; i++) {
117 if (msg + NS_INT16SZ > eom)
118 RETERR(EMSGSIZE);
119 NS_GET16(handle->_counts[i], msg);
120 }
121 for (i = 0; i < ns_s_max; i++)
122 if (handle->_counts[i] == 0)
123 handle->_sections[i] = NULL;
124 else {
125 int b = ns_skiprr(msg, eom, (ns_sect)i,
126 handle->_counts[i]);
127
128 if (b < 0)
129 return (-1);
130 handle->_sections[i] = msg;
131 msg += b;
132 }
133 if (msg != eom)
134 RETERR(EMSGSIZE);
135 setsection(handle, ns_s_max);
136 return (0);
137 }
138
139 int
ns_parserr(ns_msg * handle,ns_sect section,int rrnum,ns_rr * rr)140 ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr) {
141 int b;
142
143 /* Make section right. */
144 if ((unsigned)section >= (unsigned)ns_s_max)
145 RETERR(ENODEV);
146 if (section != handle->_sect)
147 setsection(handle, section);
148
149 /* Make rrnum right. */
150 if (rrnum == -1)
151 rrnum = handle->_rrnum;
152 if (rrnum < 0 || rrnum >= handle->_counts[(int)section])
153 RETERR(ENODEV);
154 if (rrnum < handle->_rrnum)
155 setsection(handle, section);
156 if (rrnum > handle->_rrnum) {
157 b = ns_skiprr(handle->_msg_ptr, handle->_eom, section,
158 rrnum - handle->_rrnum);
159
160 if (b < 0)
161 return (-1);
162 handle->_msg_ptr += b;
163 handle->_rrnum = rrnum;
164 }
165
166 /* Do the parse. */
167 b = dn_expand(handle->_msg, handle->_eom,
168 handle->_msg_ptr, rr->name, NS_MAXDNAME);
169 if (b < 0)
170 return (-1);
171 handle->_msg_ptr += b;
172 if (handle->_msg_ptr + NS_INT16SZ + NS_INT16SZ > handle->_eom)
173 RETERR(EMSGSIZE);
174 NS_GET16(rr->type, handle->_msg_ptr);
175 NS_GET16(rr->rr_class, handle->_msg_ptr);
176 if (section == ns_s_qd) {
177 rr->ttl = 0;
178 rr->rdlength = 0;
179 rr->rdata = NULL;
180 } else {
181 if (handle->_msg_ptr + NS_INT32SZ + NS_INT16SZ > handle->_eom)
182 RETERR(EMSGSIZE);
183 NS_GET32(rr->ttl, handle->_msg_ptr);
184 NS_GET16(rr->rdlength, handle->_msg_ptr);
185 if (handle->_msg_ptr + rr->rdlength > handle->_eom)
186 RETERR(EMSGSIZE);
187 rr->rdata = handle->_msg_ptr;
188 handle->_msg_ptr += rr->rdlength;
189 }
190 if (++handle->_rrnum > handle->_counts[(int)section])
191 setsection(handle, (ns_sect)((int)section + 1));
192
193 /* All done. */
194 return (0);
195 }
196
197 /* Private. */
198
199 static void
setsection(ns_msg * msg,ns_sect sect)200 setsection(ns_msg *msg, ns_sect sect) {
201 msg->_sect = sect;
202 if (sect == ns_s_max) {
203 msg->_rrnum = -1;
204 msg->_msg_ptr = NULL;
205 } else {
206 msg->_rrnum = 0;
207 msg->_msg_ptr = msg->_sections[(int)sect];
208 }
209 }
210