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/*
* Asterisk -- An open source telephony toolkit.
*
* Copyright (C) 2007, Digium, Inc.
*
* Joshua Colp <jcolp@digium.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
*
* \brief Simple two channel bridging module
*
* \author Joshua Colp <jcolp@digium.com>
*
* \ingroup bridges
*/
/*** MODULEINFO
<support_level>core</support_level>
***/
#include "asterisk.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include "asterisk/module.h"
#include "asterisk/channel.h"
#include "asterisk/bridge.h"
#include "asterisk/bridge_technology.h"
#include "asterisk/frame.h"
#include "asterisk/stream.h"
static void simple_bridge_stream_topology_changed(struct ast_bridge *bridge,
struct ast_bridge_channel *bridge_channel);
static int simple_bridge_join(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
{
struct ast_channel *c0 = AST_LIST_FIRST(&bridge->channels)->chan;
struct ast_channel *c1 = AST_LIST_LAST(&bridge->channels)->chan;
/*
* If this is the first channel we can't make it compatible...
* unless we make it compatible with itself. O.o
*/
if (c0 == c1) {
return 0;
}
if (ast_channel_make_compatible(c0, c1)) {
return -1;
}
/* Align stream topologies */
simple_bridge_stream_topology_changed(bridge, NULL);
return 0;
}
static int simple_bridge_write(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel, struct ast_frame *frame)
{
const struct ast_control_t38_parameters *t38_parameters;
int defer = 0;
if (!ast_bridge_queue_everyone_else(bridge, bridge_channel, frame)) {
/* This frame was successfully queued so no need to defer */
return 0;
}
/* Depending on the frame defer it so when the next channel joins it receives it */
switch (frame->frametype) {
case AST_FRAME_CONTROL:
switch (frame->subclass.integer) {
case AST_CONTROL_T38_PARAMETERS:
t38_parameters = frame->data.ptr;
switch (t38_parameters->request_response) {
case AST_T38_REQUEST_NEGOTIATE:
defer = -1;
break;
default:
break;
}
break;
default:
break;
}
break;
default:
break;
}
return defer;
}
static struct ast_bridge_technology simple_bridge = {
.name = "simple_bridge",
.capabilities = AST_BRIDGE_CAPABILITY_1TO1MIX,
.preference = AST_BRIDGE_PREFERENCE_BASE_1TO1MIX,
.join = simple_bridge_join,
.write = simple_bridge_write,
.stream_topology_changed = simple_bridge_stream_topology_changed,
};
static struct ast_stream_topology *simple_bridge_request_stream_topology_update(
struct ast_stream_topology *existing_topology,
struct ast_stream_topology *requested_topology)
{
struct ast_stream *stream;
struct ast_format_cap *audio_formats = NULL;
struct ast_stream_topology *new_topology;
int i;
new_topology = ast_stream_topology_clone(requested_topology);
if (!new_topology) {
return NULL;
}
/* We find an existing stream with negotiated audio formats that we can place into
* any audio streams in the new topology to ensure that negotiation succeeds. Some
* endpoints incorrectly terminate the call if SDP negotiation fails.
*/
for (i = 0; i < ast_stream_topology_get_count(existing_topology); ++i) {
stream = ast_stream_topology_get_stream(existing_topology, i);
if (ast_stream_get_type(stream) != AST_MEDIA_TYPE_AUDIO ||
ast_stream_get_state(stream) == AST_STREAM_STATE_REMOVED) {
continue;
}
audio_formats = ast_stream_get_formats(stream);
break;
}
if (audio_formats) {
for (i = 0; i < ast_stream_topology_get_count(new_topology); ++i) {
stream = ast_stream_topology_get_stream(new_topology, i);
if (ast_stream_get_type(stream) != AST_MEDIA_TYPE_AUDIO ||
ast_stream_get_state(stream) == AST_STREAM_STATE_REMOVED) {
continue;
}
ast_format_cap_append_from_cap(ast_stream_get_formats(stream), audio_formats,
AST_MEDIA_TYPE_AUDIO);
}
}
return new_topology;
}
static void simple_bridge_stream_topology_changed(struct ast_bridge *bridge,
struct ast_bridge_channel *bridge_channel)
{
struct ast_channel *req_chan;
struct ast_channel *existing_chan;
struct ast_stream_topology *req_top;
struct ast_stream_topology *existing_top;
struct ast_stream_topology *new_top;
if (bridge_channel) {
ast_bridge_channel_stream_map(bridge_channel);
if (ast_channel_get_stream_topology_change_source(bridge_channel->chan)
== &simple_bridge) {
return;
}
}
req_chan = AST_LIST_FIRST(&bridge->channels)->chan;
existing_chan = AST_LIST_LAST(&bridge->channels)->chan;
if (req_chan == existing_chan) {
/* Wait until both channels are in the bridge to align topologies. */
return;
}
/* Align topologies according to size or first channel to join */
ast_channel_lock_both(req_chan, existing_chan);
req_top = ast_channel_get_stream_topology(req_chan);
existing_top = ast_channel_get_stream_topology(existing_chan);
if (ast_stream_topology_get_count(req_top) < ast_stream_topology_get_count(existing_top)) {
SWAP(req_top, existing_top);
SWAP(req_chan, existing_chan);
}
new_top = simple_bridge_request_stream_topology_update(existing_top, req_top);
ast_channel_unlock(req_chan);
ast_channel_unlock(existing_chan);
if (!new_top) {
/* Failure. We'll just have to live with the current topology. */
return;
}
ast_channel_request_stream_topology_change(existing_chan, new_top, &simple_bridge);
ast_stream_topology_free(new_top);
}
static int unload_module(void)
{
ast_bridge_technology_unregister(&simple_bridge);
return 0;
}
static int load_module(void)
{
if (ast_bridge_technology_register(&simple_bridge)) {
unload_module();
return AST_MODULE_LOAD_DECLINE;
}
return AST_MODULE_LOAD_SUCCESS;
}
AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Simple two channel bridging module");
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