rtp_engine.c

/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2008, 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 Pluggable RTP Architecture
 *
 * \author Joshua Colp <jcolp@digium.com>
 */

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision$")

#include <math.h>

#include "asterisk/channel.h"
#include "asterisk/frame.h"
#include "asterisk/module.h"
#include "asterisk/rtp_engine.h"
#include "asterisk/manager.h"
#include "asterisk/options.h"
#include "asterisk/astobj2.h"
#include "asterisk/pbx.h"
#include "asterisk/translate.h"
#include "asterisk/netsock2.h"
#include "asterisk/_private.h"

struct ast_srtp_res *res_srtp = NULL;
struct ast_srtp_policy_res *res_srtp_policy = NULL;

/*! Structure that represents an RTP session (instance) */
struct ast_rtp_instance {
	/*! Engine that is handling this RTP instance */
	struct ast_rtp_engine *engine;
	/*! Data unique to the RTP engine */
	void *data;
	/*! RTP properties that have been set and their value */
	int properties[AST_RTP_PROPERTY_MAX];
	/*! Address that we are expecting RTP to come in to */
	struct ast_sockaddr local_address;
	/*! Address that we are sending RTP to */
	struct ast_sockaddr remote_address;
	/*! Alternate address that we are receiving RTP from */
	struct ast_sockaddr alt_remote_address;
	/*! Instance that we are bridged to if doing remote or local bridging */
	struct ast_rtp_instance *bridged;
	/*! Payload and packetization information */
	struct ast_rtp_codecs codecs;
	/*! RTP timeout time (negative or zero means disabled, negative value means temporarily disabled) */
	int timeout;
	/*! RTP timeout when on hold (negative or zero means disabled, negative value means temporarily disabled). */
	int holdtimeout;
	/*! RTP keepalive interval */
	int keepalive;
	/*! DTMF mode in use */
	enum ast_rtp_dtmf_mode dtmf_mode;
	/*! Glue currently in use */
	struct ast_rtp_glue *glue;
	/*! Channel associated with the instance */
	struct ast_channel *chan;
	/*! SRTP info associated with the instance */
	struct ast_srtp *srtp;
};

/*! List of RTP engines that are currently registered */
static AST_RWLIST_HEAD_STATIC(engines, ast_rtp_engine);

/*! List of RTP glues */
static AST_RWLIST_HEAD_STATIC(glues, ast_rtp_glue);

/*! The following array defines the MIME Media type (and subtype) for each
   of our codecs, or RTP-specific data type. */
static struct ast_rtp_mime_type {
	struct ast_rtp_payload_type payload_type;
	char *type;
	char *subtype;
	unsigned int sample_rate;
} ast_rtp_mime_types[128]; /* This will Likely not need to grow any time soon. */
static ast_rwlock_t mime_types_lock;
static int mime_types_len = 0;

/*!
 * \brief Mapping between Asterisk codecs and rtp payload types
 *
 * Static (i.e., well-known) RTP payload types for our "AST_FORMAT..."s:
 * also, our own choices for dynamic payload types.  This is our master
 * table for transmission
 *
 * See http://www.iana.org/assignments/rtp-parameters for a list of
 * assigned values
 */
static struct ast_rtp_payload_type static_RTP_PT[AST_RTP_MAX_PT];
static ast_rwlock_t static_RTP_PT_lock;

int ast_rtp_engine_register2(struct ast_rtp_engine *engine, struct ast_module *module)
{
	struct ast_rtp_engine *current_engine;

	/* Perform a sanity check on the engine structure to make sure it has the basics */
	if (ast_strlen_zero(engine->name) || !engine->new || !engine->destroy || !engine->write || !engine->read) {
		ast_log(LOG_WARNING, "RTP Engine '%s' failed sanity check so it was not registered.\n", !ast_strlen_zero(engine->name) ? engine->name : "Unknown");
		return -1;
	}

	/* Link owner module to the RTP engine for reference counting purposes */
	engine->mod = module;

	AST_RWLIST_WRLOCK(&engines);

	/* Ensure that no two modules with the same name are registered at the same time */
	AST_RWLIST_TRAVERSE(&engines, current_engine, entry) {
		if (!strcmp(current_engine->name, engine->name)) {
			ast_log(LOG_WARNING, "An RTP engine with the name '%s' has already been registered.\n", engine->name);
			AST_RWLIST_UNLOCK(&engines);
			return -1;
		}
	}

	/* The engine survived our critique. Off to the list it goes to be used */
	AST_RWLIST_INSERT_TAIL(&engines, engine, entry);

	AST_RWLIST_UNLOCK(&engines);

	ast_verb(2, "Registered RTP engine '%s'\n", engine->name);

	return 0;
}

int ast_rtp_engine_unregister(struct ast_rtp_engine *engine)
{
	struct ast_rtp_engine *current_engine = NULL;

	AST_RWLIST_WRLOCK(&engines);

	if ((current_engine = AST_RWLIST_REMOVE(&engines, engine, entry))) {
		ast_verb(2, "Unregistered RTP engine '%s'\n", engine->name);
	}

	AST_RWLIST_UNLOCK(&engines);

	return current_engine ? 0 : -1;
}

int ast_rtp_glue_register2(struct ast_rtp_glue *glue, struct ast_module *module)
{
	struct ast_rtp_glue *current_glue = NULL;

	if (ast_strlen_zero(glue->type)) {
		return -1;
	}

	glue->mod = module;

	AST_RWLIST_WRLOCK(&glues);

	AST_RWLIST_TRAVERSE(&glues, current_glue, entry) {
		if (!strcasecmp(current_glue->type, glue->type)) {
			ast_log(LOG_WARNING, "RTP glue with the name '%s' has already been registered.\n", glue->type);
			AST_RWLIST_UNLOCK(&glues);
			return -1;
		}
	}

	AST_RWLIST_INSERT_TAIL(&glues, glue, entry);

	AST_RWLIST_UNLOCK(&glues);

	ast_verb(2, "Registered RTP glue '%s'\n", glue->type);

	return 0;
}

int ast_rtp_glue_unregister(struct ast_rtp_glue *glue)
{
	struct ast_rtp_glue *current_glue = NULL;

	AST_RWLIST_WRLOCK(&glues);

	if ((current_glue = AST_RWLIST_REMOVE(&glues, glue, entry))) {
		ast_verb(2, "Unregistered RTP glue '%s'\n", glue->type);
	}

	AST_RWLIST_UNLOCK(&glues);

	return current_glue ? 0 : -1;
}

static void instance_destructor(void *obj)
{
	struct ast_rtp_instance *instance = obj;

	/* Pass us off to the engine to destroy */
	if (instance->data && instance->engine->destroy(instance)) {
		ast_debug(1, "Engine '%s' failed to destroy RTP instance '%p'\n", instance->engine->name, instance);
		return;
	}

	if (instance->srtp) {
		res_srtp->destroy(instance->srtp);
	}

	/* Drop our engine reference */
	ast_module_unref(instance->engine->mod);

	ast_debug(1, "Destroyed RTP instance '%p'\n", instance);
}

int ast_rtp_instance_destroy(struct ast_rtp_instance *instance)
{
	ao2_ref(instance, -1);

	return 0;
}

struct ast_rtp_instance *ast_rtp_instance_new(const char *engine_name,
		struct ast_sched_context *sched, const struct ast_sockaddr *sa,
		void *data)
{
	struct ast_sockaddr address = {{0,}};
	struct ast_rtp_instance *instance = NULL;
	struct ast_rtp_engine *engine = NULL;

	AST_RWLIST_RDLOCK(&engines);

	/* If an engine name was specified try to use it or otherwise use the first one registered */
	if (!ast_strlen_zero(engine_name)) {
		AST_RWLIST_TRAVERSE(&engines, engine, entry) {
			if (!strcmp(engine->name, engine_name)) {
				break;
			}
		}
	} else {
		engine = AST_RWLIST_FIRST(&engines);
	}

	/* If no engine was actually found bail out now */
	if (!engine) {
		ast_log(LOG_ERROR, "No RTP engine was found. Do you have one loaded?\n");
		AST_RWLIST_UNLOCK(&engines);
		return NULL;
	}

	/* Bump up the reference count before we return so the module can not be unloaded */
	ast_module_ref(engine->mod);

	AST_RWLIST_UNLOCK(&engines);

	/* Allocate a new RTP instance */
	if (!(instance = ao2_alloc(sizeof(*instance), instance_destructor))) {
		ast_module_unref(engine->mod);
		return NULL;
	}
	instance->engine = engine;
	ast_sockaddr_copy(&instance->local_address, sa);
	ast_sockaddr_copy(&address, sa);

	ast_debug(1, "Using engine '%s' for RTP instance '%p'\n", engine->name, instance);

	/* And pass it off to the engine to setup */
	if (instance->engine->new(instance, sched, &address, data)) {
		ast_debug(1, "Engine '%s' failed to setup RTP instance '%p'\n", engine->name, instance);
		ao2_ref(instance, -1);
		return NULL;
	}

	ast_debug(1, "RTP instance '%p' is setup and ready to go\n", instance);

	return instance;
}

void ast_rtp_instance_set_data(struct ast_rtp_instance *instance, void *data)
{
	instance->data = data;
}

void *ast_rtp_instance_get_data(struct ast_rtp_instance *instance)
{
	return instance->data;
}

int ast_rtp_instance_write(struct ast_rtp_instance *instance, struct ast_frame *frame)
{
	return instance->engine->write(instance, frame);
}

struct ast_frame *ast_rtp_instance_read(struct ast_rtp_instance *instance, int rtcp)
{
	return instance->engine->read(instance, rtcp);
}

int ast_rtp_instance_set_local_address(struct ast_rtp_instance *instance,
		const struct ast_sockaddr *address)
{
	ast_sockaddr_copy(&instance->local_address, address);
	return 0;
}

int ast_rtp_instance_set_remote_address(struct ast_rtp_instance *instance,
		const struct ast_sockaddr *address)
{
	ast_sockaddr_copy(&instance->remote_address, address);

	/* moo */

	if (instance->engine->remote_address_set) {
		instance->engine->remote_address_set(instance, &instance->remote_address);
	}

	return 0;
}

int ast_rtp_instance_set_alt_remote_address(struct ast_rtp_instance *instance,
		const struct ast_sockaddr *address)
{
	ast_sockaddr_copy(&instance->alt_remote_address, address);

	/* oink */

	if (instance->engine->alt_remote_address_set) {
		instance->engine->alt_remote_address_set(instance, &instance->alt_remote_address);
	}

	return 0;
}

int ast_rtp_instance_get_and_cmp_local_address(struct ast_rtp_instance *instance,
		struct ast_sockaddr *address)
{
	if (ast_sockaddr_cmp(address, &instance->local_address) != 0) {
		ast_sockaddr_copy(address, &instance->local_address);
		return 1;
	}

	return 0;
}

void ast_rtp_instance_get_local_address(struct ast_rtp_instance *instance,
		struct ast_sockaddr *address)
{
	ast_sockaddr_copy(address, &instance->local_address);
}

int ast_rtp_instance_get_and_cmp_remote_address(struct ast_rtp_instance *instance,
		struct ast_sockaddr *address)
{
	if (ast_sockaddr_cmp(address, &instance->remote_address) != 0) {
		ast_sockaddr_copy(address, &instance->remote_address);
		return 1;
	}

	return 0;
}

void ast_rtp_instance_get_remote_address(struct ast_rtp_instance *instance,
		struct ast_sockaddr *address)
{
	ast_sockaddr_copy(address, &instance->remote_address);
}

void ast_rtp_instance_set_extended_prop(struct ast_rtp_instance *instance, int property, void *value)
{
	if (instance->engine->extended_prop_set) {
		instance->engine->extended_prop_set(instance, property, value);
	}
}

void *ast_rtp_instance_get_extended_prop(struct ast_rtp_instance *instance, int property)
{
	if (instance->engine->extended_prop_get) {
		return instance->engine->extended_prop_get(instance, property);
	}

	return NULL;
}

void ast_rtp_instance_set_prop(struct ast_rtp_instance *instance, enum ast_rtp_property property, int value)
{
	instance->properties[property] = value;

	if (instance->engine->prop_set) {
		instance->engine->prop_set(instance, property, value);
	}
}

int ast_rtp_instance_get_prop(struct ast_rtp_instance *instance, enum ast_rtp_property property)
{
	return instance->properties[property];
}

struct ast_rtp_codecs *ast_rtp_instance_get_codecs(struct ast_rtp_instance *instance)
{
	return &instance->codecs;
}

void ast_rtp_codecs_payloads_clear(struct ast_rtp_codecs *codecs, struct ast_rtp_instance *instance)
{
	int i;

	for (i = 0; i < AST_RTP_MAX_PT; i++) {
		codecs->payloads[i].asterisk_format = 0;
		codecs->payloads[i].rtp_code = 0;
		ast_format_clear(&codecs->payloads[i].format);
		if (instance && instance->engine && instance->engine->payload_set) {
			instance->engine->payload_set(instance, i, 0, NULL, 0);
		}
	}
}

void ast_rtp_codecs_payloads_default(struct ast_rtp_codecs *codecs, struct ast_rtp_instance *instance)
{
	int i;

	ast_rwlock_rdlock(&static_RTP_PT_lock);
	for (i = 0; i < AST_RTP_MAX_PT; i++) {
		if (static_RTP_PT[i].rtp_code || static_RTP_PT[i].asterisk_format) {

			codecs->payloads[i].asterisk_format = static_RTP_PT[i].asterisk_format;
			codecs->payloads[i].rtp_code = static_RTP_PT[i].rtp_code;
			ast_format_copy(&codecs->payloads[i].format, &static_RTP_PT[i].format);
			if (instance && instance->engine && instance->engine->payload_set) {
				instance->engine->payload_set(instance, i, codecs->payloads[i].asterisk_format, &codecs->payloads[i].format, codecs->payloads[i].rtp_code);
			}
		}
	}
	ast_rwlock_unlock(&static_RTP_PT_lock);
}

void ast_rtp_codecs_payloads_copy(struct ast_rtp_codecs *src, struct ast_rtp_codecs *dest, struct ast_rtp_instance *instance)
{
	int i;

	for (i = 0; i < AST_RTP_MAX_PT; i++) {
		if (src->payloads[i].rtp_code || src->payloads[i].asterisk_format) {
			ast_debug(2, "Copying payload %d from %p to %p\n", i, src, dest);
			dest->payloads[i].asterisk_format = src->payloads[i].asterisk_format;
			dest->payloads[i].rtp_code = src->payloads[i].rtp_code;
			ast_format_copy(&dest->payloads[i].format, &src->payloads[i].format);
			if (instance && instance->engine && instance->engine->payload_set) {
				instance->engine->payload_set(instance, i, dest->payloads[i].asterisk_format, &dest->payloads[i].format, dest->payloads[i].rtp_code);
			}
		}
	}
}

void ast_rtp_codecs_payloads_set_m_type(struct ast_rtp_codecs *codecs, struct ast_rtp_instance *instance, int payload)
{

	ast_rwlock_rdlock(&static_RTP_PT_lock);
	if (payload < 0 || payload >= AST_RTP_MAX_PT || (!static_RTP_PT[payload].rtp_code && !static_RTP_PT[payload].asterisk_format)) {
		ast_rwlock_unlock(&static_RTP_PT_lock);
		return;
	}

	codecs->payloads[payload].asterisk_format = static_RTP_PT[payload].asterisk_format;
	codecs->payloads[payload].rtp_code = static_RTP_PT[payload].rtp_code;
	ast_format_copy(&codecs->payloads[payload].format, &static_RTP_PT[payload].format);

	ast_debug(1, "Setting payload %d based on m type on %p\n", payload, codecs);

	if (instance && instance->engine && instance->engine->payload_set) {
		instance->engine->payload_set(instance, payload, codecs->payloads[payload].asterisk_format, &codecs->payloads[payload].format, codecs->payloads[payload].rtp_code);
	}
	ast_rwlock_unlock(&static_RTP_PT_lock);
}

int ast_rtp_codecs_payloads_set_rtpmap_type_rate(struct ast_rtp_codecs *codecs, struct ast_rtp_instance *instance, int pt,
				 char *mimetype, char *mimesubtype,
				 enum ast_rtp_options options,
				 unsigned int sample_rate)
{
	unsigned int i;
	int found = 0;

	if (pt < 0 || pt >= AST_RTP_MAX_PT)
		return -1; /* bogus payload type */

	ast_rwlock_rdlock(&mime_types_lock);
	for (i = 0; i < mime_types_len; ++i) {
		const struct ast_rtp_mime_type *t = &ast_rtp_mime_types[i];

		if (strcasecmp(mimesubtype, t->subtype)) {
			continue;
		}

		if (strcasecmp(mimetype, t->type)) {
			continue;
		}

		/* if both sample rates have been supplied, and they don't match,
		 * then this not a match; if one has not been supplied, then the
		 * rates are not compared */
		if (sample_rate && t->sample_rate &&
		    (sample_rate != t->sample_rate)) {
			continue;
		}

		found = 1;
		codecs->payloads[pt] = t->payload_type;

		if ((t->payload_type.format.id == AST_FORMAT_G726) && t->payload_type.asterisk_format && (options & AST_RTP_OPT_G726_NONSTANDARD)) {
			ast_format_set(&codecs->payloads[pt].format, AST_FORMAT_G726_AAL2, 0);
		}

		if (instance && instance->engine && instance->engine->payload_set) {
			instance->engine->payload_set(instance, pt, codecs->payloads[i].asterisk_format, &codecs->payloads[i].format, codecs->payloads[i].rtp_code);
		}

		break;
	}
	ast_rwlock_unlock(&mime_types_lock);

	return (found ? 0 : -2);
}

int ast_rtp_codecs_payloads_set_rtpmap_type(struct ast_rtp_codecs *codecs, struct ast_rtp_instance *instance, int payload, char *mimetype, char *mimesubtype, enum ast_rtp_options options)
{
	return ast_rtp_codecs_payloads_set_rtpmap_type_rate(codecs, instance, payload, mimetype, mimesubtype, options, 0);
}

void ast_rtp_codecs_payloads_unset(struct ast_rtp_codecs *codecs, struct ast_rtp_instance *instance, int payload)
{
	if (payload < 0 || payload >= AST_RTP_MAX_PT) {
		return;
	}

	ast_debug(2, "Unsetting payload %d on %p\n", payload, codecs);

	codecs->payloads[payload].asterisk_format = 0;
	codecs->payloads[payload].rtp_code = 0;
	ast_format_clear(&codecs->payloads[payload].format);

	if (instance && instance->engine && instance->engine->payload_set) {
		instance->engine->payload_set(instance, payload, 0, NULL, 0);
	}
}

struct ast_rtp_payload_type ast_rtp_codecs_payload_lookup(struct ast_rtp_codecs *codecs, int payload)
{
	struct ast_rtp_payload_type result = { .asterisk_format = 0, };

	if (payload < 0 || payload >= AST_RTP_MAX_PT) {
		return result;
	}

	result.asterisk_format = codecs->payloads[payload].asterisk_format;
	result.rtp_code = codecs->payloads[payload].rtp_code;
	ast_format_copy(&result.format, &codecs->payloads[payload].format);

	if (!result.rtp_code && !result.asterisk_format) {
		ast_rwlock_rdlock(&static_RTP_PT_lock);
		result = static_RTP_PT[payload];
		ast_rwlock_unlock(&static_RTP_PT_lock);
	}

	return result;
}


struct ast_format *ast_rtp_codecs_get_payload_format(struct ast_rtp_codecs *codecs, int payload)
{
	if (payload < 0 || payload >= AST_RTP_MAX_PT) {
		return NULL;
	}
	if (!codecs->payloads[payload].asterisk_format) {
		return NULL;
	}
	return &codecs->payloads[payload].format;
}

void ast_rtp_codecs_payload_formats(struct ast_rtp_codecs *codecs, struct ast_format_cap *astformats, int *nonastformats)
{
	int i;

	ast_format_cap_remove_all(astformats);
	*nonastformats = 0;

	for (i = 0; i < AST_RTP_MAX_PT; i++) {
		if (codecs->payloads[i].rtp_code || codecs->payloads[i].asterisk_format) {
			ast_debug(1, "Incorporating payload %d on %p\n", i, codecs);
		}
		if (codecs->payloads[i].asterisk_format) {
			ast_format_cap_add(astformats, &codecs->payloads[i].format);
		} else {
			*nonastformats |= codecs->payloads[i].rtp_code;
		}
	}
}

int ast_rtp_codecs_payload_code(struct ast_rtp_codecs *codecs, int asterisk_format, const struct ast_format *format, int code)
{
	int i;
	int res = -1;
	for (i = 0; i < AST_RTP_MAX_PT; i++) {
		if (codecs->payloads[i].asterisk_format && asterisk_format && format &&
			(ast_format_cmp(format, &codecs->payloads[i].format) != AST_FORMAT_CMP_NOT_EQUAL)) {
			return i;
		} else if (!codecs->payloads[i].asterisk_format && !asterisk_format &&
			(codecs->payloads[i].rtp_code == code)) {
			return i;
		}
	}

	ast_rwlock_rdlock(&static_RTP_PT_lock);
	for (i = 0; i < AST_RTP_MAX_PT; i++) {
		if (static_RTP_PT[i].asterisk_format && asterisk_format && format &&
			(ast_format_cmp(format, &static_RTP_PT[i].format) != AST_FORMAT_CMP_NOT_EQUAL)) {
			res = i;
			break;
		} else if (!static_RTP_PT[i].asterisk_format && !asterisk_format &&
			(static_RTP_PT[i].rtp_code == code)) {
			res = i;
			break;
		}
	}
	ast_rwlock_unlock(&static_RTP_PT_lock);

	return res;
}

const char *ast_rtp_lookup_mime_subtype2(const int asterisk_format, struct ast_format *format, int code, enum ast_rtp_options options)
{
	int i;
	const char *res = "";

	ast_rwlock_rdlock(&mime_types_lock);
	for (i = 0; i < mime_types_len; i++) {
		if (ast_rtp_mime_types[i].payload_type.asterisk_format && asterisk_format && format &&
			(ast_format_cmp(format, &ast_rtp_mime_types[i].payload_type.format) != AST_FORMAT_CMP_NOT_EQUAL)) {
			if ((format->id == AST_FORMAT_G726_AAL2) && (options & AST_RTP_OPT_G726_NONSTANDARD)) {
				res = "G726-32";
				break;
			} else {
				res = ast_rtp_mime_types[i].subtype;
				break;
			}
		} else if (!ast_rtp_mime_types[i].payload_type.asterisk_format && !asterisk_format &&
			ast_rtp_mime_types[i].payload_type.rtp_code == code) {

			res = ast_rtp_mime_types[i].subtype;
			break;
		}
	}
	ast_rwlock_unlock(&mime_types_lock);

	return res;
}

unsigned int ast_rtp_lookup_sample_rate2(int asterisk_format, struct ast_format *format, int code)
{
	unsigned int i;
	unsigned int res = 0;

	ast_rwlock_rdlock(&mime_types_lock);
	for (i = 0; i < mime_types_len; ++i) {
		if (ast_rtp_mime_types[i].payload_type.asterisk_format && asterisk_format && format &&
			(ast_format_cmp(format, &ast_rtp_mime_types[i].payload_type.format) != AST_FORMAT_CMP_NOT_EQUAL)) {
			res = ast_rtp_mime_types[i].sample_rate;
			break;
		} else if (!ast_rtp_mime_types[i].payload_type.asterisk_format && !asterisk_format &&
			ast_rtp_mime_types[i].payload_type.rtp_code == code) {
			res = ast_rtp_mime_types[i].sample_rate;
			break;
		}
	}
	ast_rwlock_unlock(&mime_types_lock);

	return res;
}

char *ast_rtp_lookup_mime_multiple2(struct ast_str *buf, struct ast_format_cap *ast_format_capability, int rtp_capability, const int asterisk_format, enum ast_rtp_options options)
{
	int found = 0;
	const char *name;
	if (!buf) {
		return NULL;
	}


	if (asterisk_format) {
		struct ast_format tmp_fmt;
		ast_format_cap_iter_start(ast_format_capability);
		while (!ast_format_cap_iter_next(ast_format_capability, &tmp_fmt)) {
			name = ast_rtp_lookup_mime_subtype2(asterisk_format, &tmp_fmt, 0, options);
			ast_str_append(&buf, 0, "%s|", name);
			found = 1;
		}
		ast_format_cap_iter_end(ast_format_capability);

	} else {
		int x;
		ast_str_append(&buf, 0, "0x%x (", (unsigned int) rtp_capability);
		for (x = 1; x < AST_RTP_MAX; x <<= 1) {
			if (rtp_capability & x) {
				name = ast_rtp_lookup_mime_subtype2(asterisk_format, NULL, x, options);
				ast_str_append(&buf, 0, "%s|", name);
				found = 1;
			}
		}
	}

	ast_str_append(&buf, 0, "%s", found ? ")" : "nothing)");

	return ast_str_buffer(buf);
}

void ast_rtp_codecs_packetization_set(struct ast_rtp_codecs *codecs, struct ast_rtp_instance *instance, struct ast_codec_pref *prefs)
{
	codecs->pref = *prefs;

	if (instance && instance->engine->packetization_set) {
		instance->engine->packetization_set(instance, &instance->codecs.pref);
	}
}

int ast_rtp_instance_dtmf_begin(struct ast_rtp_instance *instance, char digit)
{
	return instance->engine->dtmf_begin ? instance->engine->dtmf_begin(instance, digit) : -1;
}

int ast_rtp_instance_dtmf_end(struct ast_rtp_instance *instance, char digit)
{
	return instance->engine->dtmf_end ? instance->engine->dtmf_end(instance, digit) : -1;
}
int ast_rtp_instance_dtmf_end_with_duration(struct ast_rtp_instance *instance, char digit, unsigned int duration)
{
	return instance->engine->dtmf_end_with_duration ? instance->engine->dtmf_end_with_duration(instance, digit, duration) : -1;
}

int ast_rtp_instance_dtmf_mode_set(struct ast_rtp_instance *instance, enum ast_rtp_dtmf_mode dtmf_mode)
{
	if (!instance->engine->dtmf_mode_set || instance->engine->dtmf_mode_set(instance, dtmf_mode)) {
		return -1;
	}

	instance->dtmf_mode = dtmf_mode;

	return 0;
}

enum ast_rtp_dtmf_mode ast_rtp_instance_dtmf_mode_get(struct ast_rtp_instance *instance)
{
	return instance->dtmf_mode;
}

void ast_rtp_instance_update_source(struct ast_rtp_instance *instance)
{
	if (instance->engine->update_source) {
		instance->engine->update_source(instance);
	}
}

void ast_rtp_instance_change_source(struct ast_rtp_instance *instance)
{
	if (instance->engine->change_source) {
		instance->engine->change_source(instance);
	}
}

int ast_rtp_instance_set_qos(struct ast_rtp_instance *instance, int tos, int cos, const char *desc)
{
	return instance->engine->qos ? instance->engine->qos(instance, tos, cos, desc) : -1;
}

void ast_rtp_instance_stop(struct ast_rtp_instance *instance)
{
	if (instance->engine->stop) {
		instance->engine->stop(instance);
	}
}

int ast_rtp_instance_fd(struct ast_rtp_instance *instance, int rtcp)
{
	return instance->engine->fd ? instance->engine->fd(instance, rtcp) : -1;
}

struct ast_rtp_glue *ast_rtp_instance_get_glue(const char *type)
{
	struct ast_rtp_glue *glue = NULL;

	AST_RWLIST_RDLOCK(&glues);

	AST_RWLIST_TRAVERSE(&glues, glue, entry) {
		if (!strcasecmp(glue->type, type)) {
			break;
		}
	}

	AST_RWLIST_UNLOCK(&glues);

	return glue;
}

static enum ast_bridge_result local_bridge_loop(struct ast_channel *c0, struct ast_channel *c1, struct ast_rtp_instance *instance0, struct ast_rtp_instance *instance1, int timeoutms, int flags, struct ast_frame **fo, struct ast_channel **rc, void *pvt0, void *pvt1)
{
	enum ast_bridge_result res = AST_BRIDGE_FAILED;
	struct ast_channel *who = NULL, *other = NULL, *cs[3] = { NULL, };
	struct ast_frame *fr = NULL;

	/* Start locally bridging both instances */
	if (instance0->engine->local_bridge && instance0->engine->local_bridge(instance0, instance1)) {
		ast_debug(1, "Failed to locally bridge %s to %s, backing out.\n", c0->name, c1->name);
		ast_channel_unlock(c0);
		ast_channel_unlock(c1);
		return AST_BRIDGE_FAILED_NOWARN;
	}
	if (instance1->engine->local_bridge && instance1->engine->local_bridge(instance1, instance0)) {
		ast_debug(1, "Failed to locally bridge %s to %s, backing out.\n", c1->name, c0->name);
		if (instance0->engine->local_bridge) {
			instance0->engine->local_bridge(instance0, NULL);
		}
		ast_channel_unlock(c0);
		ast_channel_unlock(c1);
		return AST_BRIDGE_FAILED_NOWARN;
	}

	ast_channel_unlock(c0);
	ast_channel_unlock(c1);

	instance0->bridged = instance1;
	instance1->bridged = instance0;

	ast_poll_channel_add(c0, c1);

	/* Hop into a loop waiting for a frame from either channel */
	cs[0] = c0;
	cs[1] = c1;
	cs[2] = NULL;
	for (;;) {
		/* If the underlying formats have changed force this bridge to break */
		if ((ast_format_cmp(&c0->rawreadformat, &c1->rawwriteformat) == AST_FORMAT_CMP_NOT_EQUAL) ||
			(ast_format_cmp(&c1->rawreadformat, &c0->rawwriteformat) == AST_FORMAT_CMP_NOT_EQUAL)) {
			ast_debug(1, "rtp-engine-local-bridge: Oooh, formats changed, backing out\n");
			res = AST_BRIDGE_FAILED_NOWARN;
			break;
		}
		/* Check if anything changed */
		if ((c0->tech_pvt != pvt0) ||
		    (c1->tech_pvt != pvt1) ||
		    (c0->masq || c0->masqr || c1->masq || c1->masqr) ||
		    (c0->monitor || c0->audiohooks || c1->monitor || c1->audiohooks)) {
			ast_debug(1, "rtp-engine-local-bridge: Oooh, something is weird, backing out\n");
			/* If a masquerade needs to happen we have to try to read in a frame so that it actually happens. Without this we risk being called again and going into a loop */
			if ((c0->masq || c0->masqr) && (fr = ast_read(c0))) {
				ast_frfree(fr);
			}
			if ((c1->masq || c1->masqr) && (fr = ast_read(c1))) {
				ast_frfree(fr);
			}
			res = AST_BRIDGE_RETRY;
			break;
		}
		/* Wait on a channel to feed us a frame */
		if (!(who = ast_waitfor_n(cs, 2, &timeoutms))) {
			if (!timeoutms) {
				res = AST_BRIDGE_RETRY;
				break;
			}
			ast_debug(2, "rtp-engine-local-bridge: Ooh, empty read...\n");
			if (ast_check_hangup(c0) || ast_check_hangup(c1)) {
				break;
			}
			continue;
		}
		/* Read in frame from channel */
		fr = ast_read(who);
		other = (who == c0) ? c1 : c0;
		/* Depending on the frame we may need to break out of our bridge */
		if (!fr || ((fr->frametype == AST_FRAME_DTMF_BEGIN || fr->frametype == AST_FRAME_DTMF_END) &&
			    ((who == c0) && (flags & AST_BRIDGE_DTMF_CHANNEL_0)) |
			    ((who == c1) && (flags & AST_BRIDGE_DTMF_CHANNEL_1)))) {
			/* Record received frame and who */
			*fo = fr;
			*rc = who;
			ast_debug(1, "rtp-engine-local-bridge: Ooh, got a %s\n", fr ? "digit" : "hangup");
			res = AST_BRIDGE_COMPLETE;
			break;
		} else if ((fr->frametype == AST_FRAME_CONTROL) && !(flags & AST_BRIDGE_IGNORE_SIGS)) {
			if ((fr->subclass.integer == AST_CONTROL_HOLD) ||
			    (fr->subclass.integer == AST_CONTROL_UNHOLD) ||
			    (fr->subclass.integer == AST_CONTROL_VIDUPDATE) ||
			    (fr->subclass.integer == AST_CONTROL_SRCUPDATE) ||
			    (fr->subclass.integer == AST_CONTROL_T38_PARAMETERS)) {
				/* If we are going on hold, then break callback mode and P2P bridging */
				if (fr->subclass.integer == AST_CONTROL_HOLD) {
					if (instance0->engine->local_bridge) {
						instance0->engine->local_bridge(instance0, NULL);
					}
					if (instance1->engine->local_bridge) {
						instance1->engine->local_bridge(instance1, NULL);
					}
					instance0->bridged = NULL;
					instance1->bridged = NULL;
				} else if (fr->subclass.integer == AST_CONTROL_UNHOLD) {
					if (instance0->engine->local_bridge) {
						instance0->engine->local_bridge(instance0, instance1);
					}
					if (instance1->engine->local_bridge) {
						instance1->engine->local_bridge(instance1, instance0);
					}
					instance0->bridged = instance1;
					instance1->bridged = instance0;
				}
				ast_indicate_data(other, fr->subclass.integer, fr->data.ptr, fr->datalen);
				ast_frfree(fr);
			} else if (fr->subclass.integer == AST_CONTROL_CONNECTED_LINE) {
				if (ast_channel_connected_line_macro(who, other, fr, other == c0, 1)) {
					ast_indicate_data(other, fr->subclass.integer, fr->data.ptr, fr->datalen);
				}
				ast_frfree(fr);
			} else if (fr->subclass.integer == AST_CONTROL_REDIRECTING) {
				if (ast_channel_redirecting_macro(who, other, fr, other == c0, 1)) {
					ast_indicate_data(other, fr->subclass.integer, fr->data.ptr, fr->datalen);
				}
				ast_frfree(fr);
			} else {
				*fo = fr;
				*rc = who;
				ast_debug(1, "rtp-engine-local-bridge: Got a FRAME_CONTROL (%d) frame on channel %s\n", fr->subclass.integer, who->name);
				res = AST_BRIDGE_COMPLETE;
				break;
			}
		} else {
			if ((fr->frametype == AST_FRAME_DTMF_BEGIN) ||
			    (fr->frametype == AST_FRAME_DTMF_END) ||
			    (fr->frametype == AST_FRAME_VOICE) ||
			    (fr->frametype == AST_FRAME_VIDEO) ||
			    (fr->frametype == AST_FRAME_IMAGE) ||
			    (fr->frametype == AST_FRAME_HTML) ||
			    (fr->frametype == AST_FRAME_MODEM) ||
			    (fr->frametype == AST_FRAME_TEXT)) {
				ast_write(other, fr);
			}

			ast_frfree(fr);
		}
		/* Swap priority */
		cs[2] = cs[0];
		cs[0] = cs[1];
		cs[1] = cs[2];
	}

	/* Stop locally bridging both instances */
	if (instance0->engine->local_bridge) {
		instance0->engine->local_bridge(instance0, NULL);
	}
	if (instance1->engine->local_bridge) {
		instance1->engine->local_bridge(instance1, NULL);
	}

	instance0->bridged = NULL;
	instance1->bridged = NULL;

	ast_poll_channel_del(c0, c1);

	return res;
}

static enum ast_bridge_result remote_bridge_loop(struct ast_channel *c0,
	struct ast_channel *c1,
	struct ast_rtp_instance *instance0,
	struct ast_rtp_instance *instance1,
	struct ast_rtp_instance *vinstance0,
	struct ast_rtp_instance *vinstance1,
	struct ast_rtp_instance *tinstance0,
	struct ast_rtp_instance *tinstance1,
	struct ast_rtp_glue *glue0,
	struct ast_rtp_glue *glue1,
	struct ast_format_cap *cap0,
	struct ast_format_cap *cap1,
	int timeoutms,
	int flags,
	struct ast_frame **fo,
	struct ast_channel **rc,
	void *pvt0,
	void *pvt1)
{
	enum ast_bridge_result res = AST_BRIDGE_FAILED;
	struct ast_channel *who = NULL, *other = NULL, *cs[3] = { NULL, };
	struct ast_format_cap *oldcap0 = ast_format_cap_dup(cap0);
	struct ast_format_cap *oldcap1 = ast_format_cap_dup(cap1);
	struct ast_sockaddr ac1 = {{0,}}, vac1 = {{0,}}, tac1 = {{0,}}, ac0 = {{0,}}, vac0 = {{0,}}, tac0 = {{0,}};
	struct ast_sockaddr t1 = {{0,}}, vt1 = {{0,}}, tt1 = {{0,}}, t0 = {{0,}}, vt0 = {{0,}}, tt0 = {{0,}};
	struct ast_frame *fr = NULL;