chan_multicast_rtp.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2009, Digium, Inc.
 *
 * Joshua Colp <jcolp@digium.com>
 * Andreas 'MacBrody' Brodmann <andreas.brodmann@gmail.com>
 *
 * 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
 *
 * \author Joshua Colp <jcolp@digium.com>
 * \author Andreas 'MacBrody' Broadmann <andreas.brodmann@gmail.com>
 *
 * \brief Multicast RTP Paging Channel
 *
 * \ingroup channel_drivers
 */

/*** MODULEINFO
   <support_level>core</support_level>
 ***/

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision: 385689 $")

#include <fcntl.h>
#include <sys/signal.h>

#include "asterisk/lock.h"
#include "asterisk/channel.h"
#include "asterisk/config.h"
#include "asterisk/module.h"
#include "asterisk/pbx.h"
#include "asterisk/sched.h"
#include "asterisk/io.h"
#include "asterisk/acl.h"
#include "asterisk/callerid.h"
#include "asterisk/file.h"
#include "asterisk/cli.h"
#include "asterisk/app.h"
#include "asterisk/rtp_engine.h"
#include "asterisk/causes.h"

static const char tdesc[] = "Multicast RTP Paging Channel Driver";

/* Forward declarations */
static struct ast_channel *multicast_rtp_request(const char *type, struct ast_format_cap *cap, const struct ast_channel *requestor, const char *data, int *cause);
static int multicast_rtp_call(struct ast_channel *ast, const char *dest, int timeout);
static int multicast_rtp_hangup(struct ast_channel *ast);
static struct ast_frame *multicast_rtp_read(struct ast_channel *ast);
static int multicast_rtp_write(struct ast_channel *ast, struct ast_frame *f);

/* Channel driver declaration */
static struct ast_channel_tech multicast_rtp_tech = {
   .type = "MulticastRTP",
   .description = tdesc,
   .requester = multicast_rtp_request,
   .call = multicast_rtp_call,
   .hangup = multicast_rtp_hangup,
   .read = multicast_rtp_read,
   .write = multicast_rtp_write,
};

/*! \brief Function called when we should read a frame from the channel */
static struct ast_frame  *multicast_rtp_read(struct ast_channel *ast)
{
   return &ast_null_frame;
}

/*! \brief Function called when we should write a frame to the channel */
static int multicast_rtp_write(struct ast_channel *ast, struct ast_frame *f)
{
   struct ast_rtp_instance *instance = ast_channel_tech_pvt(ast);

   return ast_rtp_instance_write(instance, f);
}

/*! \brief Function called when we should actually call the destination */
static int multicast_rtp_call(struct ast_channel *ast, const char *dest, int timeout)
{
   struct ast_rtp_instance *instance = ast_channel_tech_pvt(ast);

   ast_queue_control(ast, AST_CONTROL_ANSWER);

   return ast_rtp_instance_activate(instance);
}

/*! \brief Function called when we should hang the channel up */
static int multicast_rtp_hangup(struct ast_channel *ast)
{
   struct ast_rtp_instance *instance = ast_channel_tech_pvt(ast);

   ast_rtp_instance_destroy(instance);

   ast_channel_tech_pvt_set(ast, NULL);

   return 0;
}

/*! \brief Function called when we should prepare to call the destination */
static struct ast_channel *multicast_rtp_request(const char *type, struct ast_format_cap *cap, const struct ast_channel *requestor, const char *data, int *cause)
{
   char *tmp = ast_strdupa(data), *multicast_type = tmp, *destination, *control;
   struct ast_rtp_instance *instance;
   struct ast_sockaddr control_address;
   struct ast_sockaddr destination_address;
   struct ast_channel *chan;
   struct ast_format fmt;
   ast_best_codec(cap, &fmt);

   ast_sockaddr_setnull(&control_address);

   /* If no type was given we can't do anything */
   if (ast_strlen_zero(multicast_type)) {
      goto failure;
   }

   if (!(destination = strchr(tmp, '/'))) {
      goto failure;
   }
   *destination++ = '\0';

   if ((control = strchr(destination, '/'))) {
      *control++ = '\0';
      if (!ast_sockaddr_parse(&control_address, control,
               PARSE_PORT_REQUIRE)) {
         goto failure;
      }
   }

   if (!ast_sockaddr_parse(&destination_address, destination,
            PARSE_PORT_REQUIRE)) {
      goto failure;
   }

   if (!(instance = ast_rtp_instance_new("multicast", NULL, &control_address, multicast_type))) {
      goto failure;
   }

   if (!(chan = ast_channel_alloc(1, AST_STATE_DOWN, "", "", "", "", "", requestor ? ast_channel_linkedid(requestor) : "", 0, "MulticastRTP/%p", instance))) {
      ast_rtp_instance_destroy(instance);
      goto failure;
   }

   ast_rtp_instance_set_remote_address(instance, &destination_address);

   ast_channel_tech_set(chan, &multicast_rtp_tech);

   ast_format_cap_add(ast_channel_nativeformats(chan), &fmt);
   ast_format_copy(ast_channel_writeformat(chan), &fmt);
   ast_format_copy(ast_channel_rawwriteformat(chan), &fmt);
   ast_format_copy(ast_channel_readformat(chan), &fmt);
   ast_format_copy(ast_channel_rawreadformat(chan), &fmt);

   ast_channel_tech_pvt_set(chan, instance);

   return chan;

failure:
   *cause = AST_CAUSE_FAILURE;
   return NULL;
}

/*! \brief Function called when our module is loaded */
static int load_module(void)
{
   if (!(multicast_rtp_tech.capabilities = ast_format_cap_alloc())) {
      return AST_MODULE_LOAD_DECLINE;
   }
   ast_format_cap_add_all(multicast_rtp_tech.capabilities);
   if (ast_channel_register(&multicast_rtp_tech)) {
      ast_log(LOG_ERROR, "Unable to register channel class 'MulticastRTP'\n");
      return AST_MODULE_LOAD_DECLINE;
   }

   return AST_MODULE_LOAD_SUCCESS;
}

/*! \brief Function called when our module is unloaded */
static int unload_module(void)
{
   ast_channel_unregister(&multicast_rtp_tech);
   multicast_rtp_tech.capabilities = ast_format_cap_destroy(multicast_rtp_tech.capabilities);

   return 0;
}

AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "Multicast RTP Paging Channel",
   .load = load_module,
   .unload = unload_module,
   .load_pri = AST_MODPRI_CHANNEL_DRIVER,
);