This change adds a deferred queue to bridging. If a bridge technology determines that a frame can not be written and should be deferred it can indicate back to bridging to do so. Bridging will then requeue any deferred frames upon a new channel joining the bridge. This change has been leveraged for T.38 request negotiate control frames. Without the deferred queue there is a race condition between the bridge receiving the T.38 request negotiate and the second channel joining and being in the bridge. If the channel is not yet in the bridge then the T.38 negotiation fails. A unit test has also been added that confirms that a T.38 request negotiate control frame is deferred when no other channel is in the bridge and that it is requeued when a new channel joins the bridge. ASTERISK-26923 Change-Id: Ie05b08523f399eae579130f4a5f562a344d2e415
160 lines
4.2 KiB
C
160 lines
4.2 KiB
C
/*
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* Asterisk -- An open source telephony toolkit.
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*
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* Copyright (C) 2007, Digium, Inc.
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*
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* Joshua Colp <jcolp@digium.com>
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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 Simple two channel bridging module
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*
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* \author Joshua Colp <jcolp@digium.com>
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*
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* \ingroup bridges
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*/
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/*** MODULEINFO
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<support_level>core</support_level>
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***/
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#include "asterisk.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include "asterisk/module.h"
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#include "asterisk/channel.h"
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#include "asterisk/bridge.h"
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#include "asterisk/bridge_technology.h"
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#include "asterisk/frame.h"
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#include "asterisk/stream.h"
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static void simple_bridge_stream_topology_changed(struct ast_bridge *bridge,
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struct ast_bridge_channel *bridge_channel);
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static int simple_bridge_join(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
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{
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struct ast_channel *c0 = AST_LIST_FIRST(&bridge->channels)->chan;
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struct ast_channel *c1 = AST_LIST_LAST(&bridge->channels)->chan;
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/*
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* If this is the first channel we can't make it compatible...
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* unless we make it compatible with itself. O.o
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*/
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if (c0 == c1) {
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return 0;
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}
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if (ast_channel_make_compatible(c0, c1)) {
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return -1;
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}
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/* Align stream topologies */
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simple_bridge_stream_topology_changed(bridge, NULL);
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return 0;
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}
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static int simple_bridge_write(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel, struct ast_frame *frame)
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{
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const struct ast_control_t38_parameters *t38_parameters;
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int defer = 0;
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if (!ast_bridge_queue_everyone_else(bridge, bridge_channel, frame)) {
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/* This frame was successfully queued so no need to defer */
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return 0;
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}
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/* Depending on the frame defer it so when the next channel joins it receives it */
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switch (frame->frametype) {
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case AST_FRAME_CONTROL:
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switch (frame->subclass.integer) {
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case AST_CONTROL_T38_PARAMETERS:
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t38_parameters = frame->data.ptr;
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switch (t38_parameters->request_response) {
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case AST_T38_REQUEST_NEGOTIATE:
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defer = -1;
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break;
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default:
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break;
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}
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break;
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default:
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break;
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}
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break;
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default:
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break;
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}
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return defer;
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}
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static struct ast_bridge_technology simple_bridge = {
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.name = "simple_bridge",
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.capabilities = AST_BRIDGE_CAPABILITY_1TO1MIX,
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.preference = AST_BRIDGE_PREFERENCE_BASE_1TO1MIX,
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.join = simple_bridge_join,
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.write = simple_bridge_write,
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.stream_topology_changed = simple_bridge_stream_topology_changed,
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};
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static void simple_bridge_stream_topology_changed(struct ast_bridge *bridge,
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struct ast_bridge_channel *bridge_channel)
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{
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struct ast_channel *c0 = AST_LIST_FIRST(&bridge->channels)->chan;
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struct ast_channel *c1 = AST_LIST_LAST(&bridge->channels)->chan;
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struct ast_stream_topology *t0 = ast_channel_get_stream_topology(c0);
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struct ast_stream_topology *t1 = ast_channel_get_stream_topology(c1);
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if (bridge_channel) {
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ast_bridge_channel_stream_map(bridge_channel);
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}
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/*
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* The bridge_channel should only be NULL after both channels join
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* the bridge and their topologies are being aligned.
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*/
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if (bridge_channel && ast_channel_get_stream_topology_change_source(
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bridge_channel->chan) == &simple_bridge) {
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return;
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}
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/* Align topologies according to size or first channel to join */
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if (ast_stream_topology_get_count(t0) < ast_stream_topology_get_count(t1)) {
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ast_channel_request_stream_topology_change(c0, t1, &simple_bridge);
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} else {
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ast_channel_request_stream_topology_change(c1, t0, &simple_bridge);
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}
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}
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static int unload_module(void)
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{
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ast_bridge_technology_unregister(&simple_bridge);
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return 0;
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}
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static int load_module(void)
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{
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if (ast_bridge_technology_register(&simple_bridge)) {
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unload_module();
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return AST_MODULE_LOAD_DECLINE;
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}
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return AST_MODULE_LOAD_SUCCESS;
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}
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AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Simple two channel bridging module");
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