dns_utils.c revision 245609 
1/*-
2 * Copyright (c) 2012 Baptiste Daroussin <bapt@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer,
10 *    without modification, immediately at the beginning of the file.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: stable/9/usr.sbin/pkg/dns_utils.c 245609 2013-01-18 17:49:00Z bapt $");
29
30#include <stdlib.h>
31#include <string.h>
32#include <netinet/in.h>
33#include <resolv.h>
34
35#include "dns_utils.h"
36
37typedef union {
38	HEADER hdr;
39	unsigned char buf[1024];
40} dns_query;
41
42struct dns_srvinfo *
43dns_getsrvinfo(const char *zone)
44{
45	struct dns_srvinfo **res, *first;
46	unsigned char *end, *p;
47	char host[MAXHOSTNAMELEN];
48	dns_query q;
49	int len, qdcount, ancount, n, i;
50	unsigned int type, class, ttl, priority, weight, port;
51
52	if ((len = res_query(zone, C_IN, T_SRV, q.buf, sizeof(q.buf))) == -1 ||
53	    len < (int)sizeof(HEADER))
54		return (NULL);
55
56	qdcount = ntohs(q.hdr.qdcount);
57	ancount = ntohs(q.hdr.ancount);
58
59	end = q.buf + len;
60	p = q.buf + sizeof(HEADER);
61
62	while(qdcount > 0 && p < end) {
63		qdcount--;
64		if((len = dn_expand(q.buf, end, p, host, MAXHOSTNAMELEN)) < 0)
65			return (NULL);
66		p += len + NS_QFIXEDSZ;
67	}
68
69	res = calloc(ancount, sizeof(struct dns_srvinfo));
70	if (res == NULL)
71		return (NULL);
72
73	n = 0;
74	while (ancount > 0 && p < end) {
75		ancount--;
76		len = dn_expand(q.buf, end, p, host, MAXHOSTNAMELEN);
77		if (len < 0) {
78			for (i = 0; i < n; i++)
79				free(res[i]);
80			free(res);
81			return NULL;
82		}
83
84		p += len;
85
86		NS_GET16(type, p);
87		NS_GET16(class, p);
88		NS_GET32(ttl, p);
89		NS_GET16(len, p);
90
91		if (type != T_SRV) {
92			p += len;
93			continue;
94		}
95
96		NS_GET16(priority, p);
97		NS_GET16(weight, p);
98		NS_GET16(port, p);
99
100		len = dn_expand(q.buf, end, p, host, MAXHOSTNAMELEN);
101		if (len < 0) {
102			for (i = 0; i < n; i++)
103				free(res[i]);
104			free(res);
105			return (NULL);
106		}
107
108		res[n] = malloc(sizeof(struct dns_srvinfo));
109		if (res[n] == NULL) {
110			for (i = 0; i < n; i++)
111				free(res[i]);
112			free(res);
113			return (NULL);
114		}
115		res[n]->type = type;
116		res[n]->class = class;
117		res[n]->ttl = ttl;
118		res[n]->priority = priority;
119		res[n]->weight = weight;
120		res[n]->port = port;
121		res[n]->next = NULL;
122		strlcpy(res[n]->host, host, MAXHOSTNAMELEN);
123
124		p += len;
125		n++;
126	}
127
128	for (i = 0; i < n - 1; i++)
129		res[i]->next = res[i + 1];
130
131	first = res[0];
132	free(res);
133
134	return (first);
135}
136