summary refs log tree commit diff
path: root/resolv/ns_parse.c
blob: 7bbdc41cdfaa5198b3e8e14d34a045c62a9dac31 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
/*
 * Copyright (c) 1996,1999 by Internet Software Consortium.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 */

#ifndef lint
static const char rcsid[] = "$Id$";
#endif

/* Import. */

#include <sys/types.h>

#include <netinet/in.h>
#include <arpa/nameser.h>

#include <errno.h>
#include <resolv.h>
#include <string.h>

/* Forward. */

static void	setsection(ns_msg *msg, ns_sect sect);

/* Macros. */

#define RETERR(err) do { __set_errno (err); return (-1); } while (0)

/* Public. */

/* These need to be in the same order as the nres.h:ns_flag enum. */
struct _ns_flagdata _ns_flagdata[16] = {
	{ 0x8000, 15 },		/* qr. */
	{ 0x7800, 11 },		/* opcode. */
	{ 0x0400, 10 },		/* aa. */
	{ 0x0200, 9 },		/* tc. */
	{ 0x0100, 8 },		/* rd. */
	{ 0x0080, 7 },		/* ra. */
	{ 0x0040, 6 },		/* z. */
	{ 0x0020, 5 },		/* ad. */
	{ 0x0010, 4 },		/* cd. */
	{ 0x000f, 0 },		/* rcode. */
	{ 0x0000, 0 },		/* expansion (1/6). */
	{ 0x0000, 0 },		/* expansion (2/6). */
	{ 0x0000, 0 },		/* expansion (3/6). */
	{ 0x0000, 0 },		/* expansion (4/6). */
	{ 0x0000, 0 },		/* expansion (5/6). */
	{ 0x0000, 0 },		/* expansion (6/6). */
};

int
ns_skiprr(const u_char *ptr, const u_char *eom, ns_sect section, int count) {
	const u_char *optr = ptr;

	for ((void)NULL; count > 0; count--) {
		int b, rdlength;

		b = dn_skipname(ptr, eom);
		if (b < 0)
			RETERR(EMSGSIZE);
		ptr += b/*Name*/ + NS_INT16SZ/*Type*/ + NS_INT16SZ/*Class*/;
		if (section != ns_s_qd) {
			if (ptr + NS_INT32SZ + NS_INT16SZ > eom)
				RETERR(EMSGSIZE);
			ptr += NS_INT32SZ/*TTL*/;
			NS_GET16(rdlength, ptr);
			ptr += rdlength/*RData*/;
		}
	}
	if (ptr > eom)
		RETERR(EMSGSIZE);
	return (ptr - optr);
}

int
ns_initparse(const u_char *msg, int msglen, ns_msg *handle) {
	const u_char *eom = msg + msglen;
	int i;

	memset(handle, 0x5e, sizeof *handle);
	handle->_msg = msg;
	handle->_eom = eom;
	if (msg + NS_INT16SZ > eom)
		RETERR(EMSGSIZE);
	NS_GET16(handle->_id, msg);
	if (msg + NS_INT16SZ > eom)
		RETERR(EMSGSIZE);
	NS_GET16(handle->_flags, msg);
	for (i = 0; i < ns_s_max; i++) {
		if (msg + NS_INT16SZ > eom)
			RETERR(EMSGSIZE);
		NS_GET16(handle->_counts[i], msg);
	}
	for (i = 0; i < ns_s_max; i++)
		if (handle->_counts[i] == 0)
			handle->_sections[i] = NULL;
		else {
			int b = ns_skiprr(msg, eom, (ns_sect)i,
					  handle->_counts[i]);

			if (b < 0)
				return (-1);
			handle->_sections[i] = msg;
			msg += b;
		}
	if (msg != eom)
		RETERR(EMSGSIZE);
	setsection(handle, ns_s_max);
	return (0);
}

int
ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr) {
	int b;

	/* Make section right. */
	if (section < 0 || section >= ns_s_max)
		RETERR(ENODEV);
	if (section != handle->_sect)
		setsection(handle, section);

	/* Make rrnum right. */
	if (rrnum == -1)
		rrnum = handle->_rrnum;
	if (rrnum < 0 || rrnum >= handle->_counts[(int)section])
		RETERR(ENODEV);
	if (rrnum < handle->_rrnum)
		setsection(handle, section);
	if (rrnum > handle->_rrnum) {
		b = ns_skiprr(handle->_ptr, handle->_eom, section,
			      rrnum - handle->_rrnum);

		if (b < 0)
			return (-1);
		handle->_ptr += b;
		handle->_rrnum = rrnum;
	}

	/* Do the parse. */
	b = dn_expand(handle->_msg, handle->_eom,
		      handle->_ptr, rr->name, NS_MAXDNAME);
	if (b < 0)
		return (-1);
	handle->_ptr += b;
	if (handle->_ptr + NS_INT16SZ + NS_INT16SZ > handle->_eom)
		RETERR(EMSGSIZE);
	NS_GET16(rr->type, handle->_ptr);
	NS_GET16(rr->rr_class, handle->_ptr);
	if (section == ns_s_qd) {
		rr->ttl = 0;
		rr->rdlength = 0;
		rr->rdata = NULL;
	} else {
		if (handle->_ptr + NS_INT32SZ + NS_INT16SZ > handle->_eom)
			RETERR(EMSGSIZE);
		NS_GET32(rr->ttl, handle->_ptr);
		NS_GET16(rr->rdlength, handle->_ptr);
		if (handle->_ptr + rr->rdlength > handle->_eom)
			RETERR(EMSGSIZE);
		rr->rdata = handle->_ptr;
		handle->_ptr += rr->rdlength;
	}
	if (++handle->_rrnum > handle->_counts[(int)section])
		setsection(handle, (ns_sect)((int)section + 1));

	/* All done. */
	return (0);
}

/* Private. */

static void
setsection(ns_msg *msg, ns_sect sect) {
	msg->_sect = sect;
	if (sect == ns_s_max) {
		msg->_rrnum = -1;
		msg->_ptr = NULL;
	} else {
		msg->_rrnum = 0;
		msg->_ptr = msg->_sections[(int)sect];
	}
}