aboutsummaryrefslogtreecommitdiffstats
path: root/srv.c
blob: 9e04d84e4531afe15958e63d9b3f479f80b5a48c (plain)
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
/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2005, Digium, Inc.
 *
 * Mark Spencer <markster@digium.com>
 *
 * Funding provided by nic.at
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief DNS SRV Record Lookup Support for Asterisk
 * 
 * \arg See also \ref AstENUM
 *
 */

#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#if __APPLE_CC__ >= 1495
#include <arpa/nameser_compat.h>
#endif
#include <resolv.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision$")

#include "asterisk/channel.h"
#include "asterisk/logger.h"
#include "asterisk/srv.h"
#include "asterisk/dns.h"
#include "asterisk/options.h"
#include "asterisk/utils.h"

#ifdef __APPLE__
#undef T_SRV
#define T_SRV 33
#endif

struct srv {
	unsigned short priority;
	unsigned short weight;
	unsigned short portnum;
} __attribute__ ((__packed__));

static int parse_srv(char *host, int hostlen, int *portno, char *answer, int len, char *msg)
{
	int res = 0;
	struct srv *srv = (struct srv *)answer;
	char repl[256] = "";

	if (len < sizeof(struct srv)) {
		printf("Length too short\n");
		return -1;
	}
	answer += sizeof(struct srv);
	len -= sizeof(struct srv);

	if ((res = dn_expand((unsigned char *)msg, (unsigned char *)answer + len, (unsigned char *)answer, repl, sizeof(repl) - 1)) < 0) {
		ast_log(LOG_WARNING, "Failed to expand hostname\n");
		return -1;
	}
	if (res && strcmp(repl, ".")) {
		if (option_verbose > 3)
			ast_verbose( VERBOSE_PREFIX_3 "parse_srv: SRV mapped to host %s, port %d\n", repl, ntohs(srv->portnum));
		if (host) {
			ast_copy_string(host, repl, hostlen);
			host[hostlen-1] = '\0';
		}
		if (portno)
			*portno = ntohs(srv->portnum);
		return 0;
	}
	return -1;
}

struct srv_context {
	char *host;
	int hostlen;
	int *port;
};

static int srv_callback(void *context, char *answer, int len, char *fullanswer)
{
	struct srv_context *c = (struct srv_context *)context;

	if (parse_srv(c->host, c->hostlen, c->port, answer, len, fullanswer)) {
		ast_log(LOG_WARNING, "Failed to parse srv\n");
		return -1;
	}

	if (!ast_strlen_zero(c->host))
		return 1;

	return 0;
}

int ast_get_srv(struct ast_channel *chan, char *host, int hostlen, int *port, const char *service)
{
	struct srv_context context;
	int ret;

	context.host = host;
	context.hostlen = hostlen;
	context.port = port;

	if (chan && ast_autoservice_start(chan) < 0)
		return -1;

	ret = ast_search_dns(&context, service, C_IN, T_SRV, srv_callback);

	if (chan)
		ret |= ast_autoservice_stop(chan);

	if (ret <= 0) {
		host[0] = '\0';
		*port = -1;
		return ret;
	}
	return ret;
}