Wed Apr 6 11:29:42 2011

Asterisk developer's documentation


chan_multicast_rtp.c

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 2009, Digium, Inc.
00005  *
00006  * Joshua Colp <jcolp@digium.com>
00007  * Andreas 'MacBrody' Brodmann <andreas.brodmann@gmail.com>
00008  *
00009  * See http://www.asterisk.org for more information about
00010  * the Asterisk project. Please do not directly contact
00011  * any of the maintainers of this project for assistance;
00012  * the project provides a web site, mailing lists and IRC
00013  * channels for your use.
00014  *
00015  * This program is free software, distributed under the terms of
00016  * the GNU General Public License Version 2. See the LICENSE file
00017  * at the top of the source tree.
00018  */
00019 
00020 /*! \file
00021  *
00022  * \author Joshua Colp <jcolp@digium.com>
00023  * \author Andreas 'MacBrody' Broadmann <andreas.brodmann@gmail.com>
00024  *
00025  * \brief Multicast RTP Paging Channel
00026  *
00027  * \ingroup channel_drivers
00028  */
00029 
00030 #include "asterisk.h"
00031 
00032 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
00033 
00034 #include <fcntl.h>
00035 #include <sys/signal.h>
00036 
00037 #include "asterisk/lock.h"
00038 #include "asterisk/channel.h"
00039 #include "asterisk/config.h"
00040 #include "asterisk/module.h"
00041 #include "asterisk/pbx.h"
00042 #include "asterisk/sched.h"
00043 #include "asterisk/io.h"
00044 #include "asterisk/acl.h"
00045 #include "asterisk/callerid.h"
00046 #include "asterisk/file.h"
00047 #include "asterisk/cli.h"
00048 #include "asterisk/app.h"
00049 #include "asterisk/rtp_engine.h"
00050 #include "asterisk/causes.h"
00051 
00052 static const char tdesc[] = "Multicast RTP Paging Channel Driver";
00053 
00054 /* Forward declarations */
00055 static struct ast_channel *multicast_rtp_request(const char *type, format_t format, const struct ast_channel *requestor, void *data, int *cause);
00056 static int multicast_rtp_call(struct ast_channel *ast, char *dest, int timeout);
00057 static int multicast_rtp_hangup(struct ast_channel *ast);
00058 static struct ast_frame *multicast_rtp_read(struct ast_channel *ast);
00059 static int multicast_rtp_write(struct ast_channel *ast, struct ast_frame *f);
00060 
00061 /* Channel driver declaration */
00062 static const struct ast_channel_tech multicast_rtp_tech = {
00063    .type = "MulticastRTP",
00064    .description = tdesc,
00065    .capabilities = -1,
00066    .requester = multicast_rtp_request,
00067    .call = multicast_rtp_call,
00068    .hangup = multicast_rtp_hangup,
00069    .read = multicast_rtp_read,
00070    .write = multicast_rtp_write,
00071 };
00072 
00073 /*! \brief Function called when we should read a frame from the channel */
00074 static struct ast_frame  *multicast_rtp_read(struct ast_channel *ast)
00075 {
00076    return &ast_null_frame;
00077 }
00078 
00079 /*! \brief Function called when we should write a frame to the channel */
00080 static int multicast_rtp_write(struct ast_channel *ast, struct ast_frame *f)
00081 {
00082    struct ast_rtp_instance *instance = ast->tech_pvt;
00083 
00084    return ast_rtp_instance_write(instance, f);
00085 }
00086 
00087 /*! \brief Function called when we should actually call the destination */
00088 static int multicast_rtp_call(struct ast_channel *ast, char *dest, int timeout)
00089 {
00090    struct ast_rtp_instance *instance = ast->tech_pvt;
00091 
00092    ast_queue_control(ast, AST_CONTROL_ANSWER);
00093 
00094    return ast_rtp_instance_activate(instance);
00095 }
00096 
00097 /*! \brief Function called when we should hang the channel up */
00098 static int multicast_rtp_hangup(struct ast_channel *ast)
00099 {
00100    struct ast_rtp_instance *instance = ast->tech_pvt;
00101 
00102    ast_rtp_instance_destroy(instance);
00103 
00104    ast->tech_pvt = NULL;
00105 
00106    return 0;
00107 }
00108 
00109 /*! \brief Function called when we should prepare to call the destination */
00110 static struct ast_channel *multicast_rtp_request(const char *type, format_t format, const struct ast_channel *requestor, void *data, int *cause)
00111 {
00112    char *tmp = ast_strdupa(data), *multicast_type = tmp, *destination, *control;
00113    struct ast_rtp_instance *instance;
00114    struct ast_sockaddr control_address;
00115    struct ast_sockaddr destination_address;
00116    struct ast_channel *chan;
00117    format_t fmt = ast_best_codec(format);
00118 
00119    ast_sockaddr_setnull(&control_address);
00120 
00121    /* If no type was given we can't do anything */
00122    if (ast_strlen_zero(multicast_type)) {
00123       goto failure;
00124    }
00125 
00126    if (!(destination = strchr(tmp, '/'))) {
00127       goto failure;
00128    }
00129    *destination++ = '\0';
00130 
00131    if ((control = strchr(destination, '/'))) {
00132       *control++ = '\0';
00133       if (!ast_sockaddr_parse(&control_address, control,
00134                PARSE_PORT_REQUIRE)) {
00135          goto failure;
00136       }
00137    }
00138 
00139    if (!ast_sockaddr_parse(&destination_address, destination,
00140             PARSE_PORT_REQUIRE)) {
00141       goto failure;
00142    }
00143 
00144    if (!(instance = ast_rtp_instance_new("multicast", NULL, &control_address, multicast_type))) {
00145       goto failure;
00146    }
00147 
00148    if (!(chan = ast_channel_alloc(1, AST_STATE_DOWN, "", "", "", "", "", requestor ? requestor->linkedid : "", 0, "MulticastRTP/%p", instance))) {
00149       ast_rtp_instance_destroy(instance);
00150       goto failure;
00151    }
00152 
00153    ast_rtp_instance_set_remote_address(instance, &destination_address);
00154 
00155    chan->tech = &multicast_rtp_tech;
00156    chan->nativeformats = fmt;
00157    chan->writeformat = fmt;
00158    chan->readformat = fmt;
00159    chan->rawwriteformat = fmt;
00160    chan->rawreadformat = fmt;
00161    chan->tech_pvt = instance;
00162 
00163    return chan;
00164 
00165 failure:
00166    *cause = AST_CAUSE_FAILURE;
00167    return NULL;
00168 }
00169 
00170 /*! \brief Function called when our module is loaded */
00171 static int load_module(void)
00172 {
00173    if (ast_channel_register(&multicast_rtp_tech)) {
00174       ast_log(LOG_ERROR, "Unable to register channel class 'MulticastRTP'\n");
00175       return AST_MODULE_LOAD_DECLINE;
00176    }
00177 
00178    return AST_MODULE_LOAD_SUCCESS;
00179 }
00180 
00181 /*! \brief Function called when our module is unloaded */
00182 static int unload_module(void)
00183 {
00184    ast_channel_unregister(&multicast_rtp_tech);
00185 
00186    return 0;
00187 }
00188 
00189 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "Multicast RTP Paging Channel",
00190    .load = load_module,
00191    .unload = unload_module,
00192    .load_pri = AST_MODPRI_CHANNEL_DRIVER,
00193 );

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