138 lines
3.0 KiB
C
138 lines
3.0 KiB
C
/*
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* Asterisk -- An open source telephony toolkit.
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*
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* Copyright (C) 1999 - 2005, Digium, Inc.
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*
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* Mark Spencer <markster@digium.com>
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*
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* Funding provided by nic.at
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*
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* See http://www.asterisk.org for more information about
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* the Asterisk project. Please do not directly contact
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* any of the maintainers of this project for assistance;
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* the project provides a web site, mailing lists and IRC
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* channels for your use.
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*
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* This program is free software, distributed under the terms of
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* the GNU General Public License Version 2. See the LICENSE file
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* at the top of the source tree.
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*/
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/*! \file
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*
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* \brief DNS SRV Record Lookup Support for Asterisk
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*
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* \arg See also \ref AstENUM
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*
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*/
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#include <sys/types.h>
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#include <netinet/in.h>
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#include <arpa/nameser.h>
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#if __APPLE_CC__ >= 1495
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#include <arpa/nameser_compat.h>
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#endif
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#include <resolv.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include "asterisk.h"
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ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
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#include "asterisk/channel.h"
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#include "asterisk/logger.h"
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#include "asterisk/srv.h"
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#include "asterisk/dns.h"
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#include "asterisk/options.h"
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#include "asterisk/utils.h"
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#ifdef __APPLE__
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#undef T_SRV
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#define T_SRV 33
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#endif
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struct srv {
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unsigned short priority;
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unsigned short weight;
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unsigned short portnum;
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} __attribute__ ((__packed__));
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static int parse_srv(char *host, int hostlen, int *portno, char *answer, int len, char *msg)
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{
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int res = 0;
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struct srv *srv = (struct srv *)answer;
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char repl[256] = "";
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if (len < sizeof(struct srv)) {
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printf("Length too short\n");
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return -1;
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}
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answer += sizeof(struct srv);
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len -= sizeof(struct srv);
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if ((res = dn_expand((unsigned char *)msg, (unsigned char *)answer + len, (unsigned char *)answer, repl, sizeof(repl) - 1)) < 0) {
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ast_log(LOG_WARNING, "Failed to expand hostname\n");
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return -1;
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}
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if (res && strcmp(repl, ".")) {
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if (option_verbose > 3)
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ast_verbose( VERBOSE_PREFIX_3 "parse_srv: SRV mapped to host %s, port %d\n", repl, ntohs(srv->portnum));
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if (host) {
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ast_copy_string(host, repl, hostlen);
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host[hostlen-1] = '\0';
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}
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if (portno)
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*portno = ntohs(srv->portnum);
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return 0;
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}
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return -1;
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}
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struct srv_context {
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char *host;
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int hostlen;
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int *port;
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};
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static int srv_callback(void *context, char *answer, int len, char *fullanswer)
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{
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struct srv_context *c = (struct srv_context *)context;
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if (parse_srv(c->host, c->hostlen, c->port, answer, len, fullanswer)) {
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ast_log(LOG_WARNING, "Failed to parse srv\n");
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return -1;
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}
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if (!ast_strlen_zero(c->host))
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return 1;
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return 0;
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}
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int ast_get_srv(struct ast_channel *chan, char *host, int hostlen, int *port, const char *service)
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{
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struct srv_context context;
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int ret;
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context.host = host;
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context.hostlen = hostlen;
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context.port = port;
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if (chan && ast_autoservice_start(chan) < 0)
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return -1;
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ret = ast_search_dns(&context, service, C_IN, T_SRV, srv_callback);
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if (chan)
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ret |= ast_autoservice_stop(chan);
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if (ret <= 0) {
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host[0] = '\0';
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*port = -1;
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return ret;
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}
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return ret;
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}
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