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/*
* 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: 7221 $")
#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;
}
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