1 /*
2 * Copyright (c) 1996 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 #include <sys/cdefs.h>
19 #include <sys/types.h>
20
21 #include <sys/types.h>
22
23 #include <netinet/in.h>
24 #include <arpa/nameser.h>
25
26 #include <errno.h>
27 #include <resolv.h>
28 #include <string.h>
29
30 /* These need to be in the same order as the nres.h:ns_flag enum. */
31 struct _ns_flagdata _ns_flagdata[16] = {
32 { 0x8000, 15 }, /* qr. */
33 { 0x7800, 11 }, /* opcode. */
34 { 0x0400, 10 }, /* aa. */
35 { 0x0200, 9 }, /* tc. */
36 { 0x0100, 8 }, /* rd. */
37 { 0x0080, 7 }, /* ra. */
38 { 0x0040, 6 }, /* z. */
39 { 0x0020, 5 }, /* ad. */
40 { 0x0010, 4 }, /* cd. */
41 { 0x000f, 0 }, /* rcode. */
42 { 0x0000, 0 }, /* expansion (1/6). */
43 { 0x0000, 0 }, /* expansion (2/6). */
44 { 0x0000, 0 }, /* expansion (3/6). */
45 { 0x0000, 0 }, /* expansion (4/6). */
46 { 0x0000, 0 }, /* expansion (5/6). */
47 { 0x0000, 0 }, /* expansion (6/6). */
48 };
49
50 static int
skiprr(const u_char * ptr,const u_char * eom,ns_sect section,int count)51 skiprr(const u_char *ptr, const u_char *eom, ns_sect section, int count) {
52 const u_char *optr = ptr;
53
54 for ((void)NULL; count > 0; count--) {
55 int b, rdlength;
56
57 b = dn_skipname(ptr, eom);
58 if (b < 0)
59 goto emsgsize;
60 ptr += b/*Name*/ + NS_INT16SZ/*Type*/ + NS_INT16SZ/*Class*/;
61 if (section != ns_s_qd) {
62 if (ptr + NS_INT32SZ > eom)
63 goto emsgsize;
64 ptr += NS_INT32SZ/*TTL*/;
65 if (ptr + NS_INT16SZ > eom)
66 goto emsgsize;
67 NS_GET16(rdlength, ptr);
68 ptr += rdlength/*RData*/;
69 }
70 }
71 if (ptr > eom)
72 goto emsgsize;
73 return (ptr - optr);
74 emsgsize:
75 errno = EMSGSIZE;
76 return (-1);
77 }
78
79 int
ns_initparse(const u_char * msg,int msglen,ns_msg * handle)80 ns_initparse(const u_char *msg, int msglen, ns_msg *handle) {
81 const u_char *eom = msg + msglen;
82 int i;
83
84 memset(handle, 0x5e, sizeof *handle);
85 handle->_msg = msg;
86 handle->_eom = eom;
87 if (msg + NS_INT16SZ > eom)
88 goto emsgsize;
89 NS_GET16(handle->_id, msg);
90 if (msg + NS_INT16SZ > eom)
91 goto emsgsize;
92 NS_GET16(handle->_flags, msg);
93 for (i = 0; i < ns_s_max; i++) {
94 if (msg + NS_INT16SZ > eom)
95 goto emsgsize;
96 NS_GET16(handle->_counts[i], msg);
97 }
98 for (i = 0; i < ns_s_max; i++)
99 if (handle->_counts[i] == 0)
100 handle->_sections[i] = NULL;
101 else {
102 int b = skiprr(msg, eom, (ns_sect)i,
103 handle->_counts[i]);
104
105 if (b < 0)
106 return (-1);
107 handle->_sections[i] = msg;
108 msg += b;
109 }
110 if (msg != eom)
111 goto emsgsize;
112 handle->_sect = ns_s_max;
113 handle->_rrnum = -1;
114 handle->_ptr = NULL;
115 return (0);
116 emsgsize:
117 errno = EMSGSIZE;
118 return (-1);
119 }
120
121 int
ns_parserr(ns_msg * handle,ns_sect section,int rrnum,ns_rr * rr)122 ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr) {
123 int b;
124
125 /* Make section right. */
126 if (section < 0 || section >= ns_s_max)
127 goto enodev;
128 if ((int)section != (int)handle->_sect) {
129 handle->_sect = section;
130 handle->_rrnum = 0;
131 handle->_ptr = handle->_sections[(int)section];
132 }
133
134 /* Make rrnum right. */
135 if (rrnum == -1)
136 rrnum = handle->_rrnum;
137 if (rrnum < 0 || rrnum >= handle->_counts[(int)section])
138 goto enodev;
139 if (rrnum < handle->_rrnum) {
140 handle->_rrnum = 0;
141 handle->_ptr = handle->_sections[(int)section];
142 }
143
144 b = skiprr(handle->_msg, handle->_eom, section,
145 rrnum - handle->_rrnum);
146 if (b < 0)
147 return (-1);
148 handle->_ptr += b;
149 handle->_rrnum = rrnum;
150
151 /* Do the parse. */
152 b = dn_expand(handle->_msg, handle->_eom,
153 handle->_ptr, rr->name, NS_MAXDNAME);
154 if (b < 0)
155 return (-1);
156 handle->_ptr += b;
157 if (handle->_ptr + NS_INT16SZ > handle->_eom)
158 goto emsgsize;
159 NS_GET16(rr->type, handle->_ptr);
160 if (handle->_ptr + NS_INT16SZ > handle->_eom)
161 goto emsgsize;
162 NS_GET16(rr->rr_class, handle->_ptr);
163 if (section == ns_s_qd) {
164 rr->ttl = 0;
165 rr->rdlength = 0;
166 rr->rdata = NULL;
167 } else {
168 if (handle->_ptr + NS_INT32SZ > handle->_eom)
169 goto emsgsize;
170 NS_GET32(rr->ttl, handle->_ptr);
171 if (handle->_ptr + NS_INT16SZ > handle->_eom)
172 goto emsgsize;
173 NS_GET16(rr->rdlength, handle->_ptr);
174 if (handle->_ptr + rr->rdlength > handle->_eom)
175 goto emsgsize;
176 rr->rdata = handle->_ptr;
177 handle->_ptr += rr->rdlength;
178 }
179 handle->_rrnum++;
180
181 /* All done. */
182 return (0);
183 enodev:
184 errno = ENODEV;
185 return (-1);
186 emsgsize:
187 errno = EMSGSIZE;
188 return (-1);
189 }
190