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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
     */
    
    #include "asterisk.h"
    
    ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
    
    #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/bridging.h"
    #include "asterisk/bridging_technology.h"
    #include "asterisk/frame.h"
    
    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, *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 (AST_LIST_FIRST(&bridge->channels) == AST_LIST_LAST(&bridge->channels)) {
    		return 0;
    	}
    
    	/* See if we need to make these compatible */
    	if (((c0->writeformat == c1->readformat) && (c0->readformat == c1->writeformat) && (c0->nativeformats == c1->nativeformats))) {
    		return 0;
    	}
    
    	/* BOOM! We do. */
    	return ast_channel_make_compatible(c0, c1);
    }
    
    static enum ast_bridge_write_result simple_bridge_write(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel, struct ast_frame *frame)
    {
    	struct ast_bridge_channel *other = NULL;
    
    	/* If this is the only channel in this bridge then immediately exit */
    	if (AST_LIST_FIRST(&bridge->channels) == AST_LIST_LAST(&bridge->channels)) {
    		return AST_BRIDGE_WRITE_FAILED;
    	}
    
    	/* Find the channel we actually want to write to */
    	if (!(other = (AST_LIST_FIRST(&bridge->channels) == bridge_channel ? AST_LIST_LAST(&bridge->channels) : AST_LIST_FIRST(&bridge->channels)))) {
    		return AST_BRIDGE_WRITE_FAILED;
    	}
    
    	/* Write the frame out if they are in the waiting state... don't worry about freeing it, the bridging core will take care of it */
    	if (other->state == AST_BRIDGE_CHANNEL_STATE_WAIT) {
    		ast_write(other->chan, frame);
    	}
    
    	return AST_BRIDGE_WRITE_SUCCESS;
    }
    
    static struct ast_bridge_technology simple_bridge = {
    	.name = "simple_bridge",
    	.capabilities = AST_BRIDGE_CAPABILITY_1TO1MIX | AST_BRIDGE_CAPABILITY_THREAD,
    	.preference = AST_BRIDGE_PREFERENCE_MEDIUM,
    	.formats = AST_FORMAT_AUDIO_MASK | AST_FORMAT_VIDEO_MASK | AST_FORMAT_TEXT_MASK,
    	.join = simple_bridge_join,
    	.write = simple_bridge_write,
    };
    
    static int unload_module(void)
    {
    	return ast_bridge_technology_unregister(&simple_bridge);
    }
    
    static int load_module(void)
    {
    	return ast_bridge_technology_register(&simple_bridge);
    }
    
    AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Simple two channel bridging module");