rtp.c

/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2006, Digium, Inc.
 *
 * Mark Spencer <markster@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 Supports RTP and RTCP with Symmetric RTP support for NAT traversal.
 *
 * \author Mark Spencer <markster@digium.com>
 * 
 * \note RTP is deffined in RFC 3550.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include <signal.h>
#include <errno.h>
#include <unistd.h>
#include <netinet/in.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <fcntl.h>

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision$")

#include "asterisk/rtp.h"
#include "asterisk/frame.h"
#include "asterisk/logger.h"
#include "asterisk/options.h"
#include "asterisk/channel.h"
#include "asterisk/acl.h"
#include "asterisk/channel.h"
#include "asterisk/config.h"
#include "asterisk/lock.h"
#include "asterisk/utils.h"
#include "asterisk/cli.h"
#include "asterisk/unaligned.h"
#include "asterisk/utils.h"

#define MAX_TIMESTAMP_SKEW	640

#define RTP_MTU		1200

#define DEFAULT_DTMF_TIMEOUT 3000	/*!< samples */

static int dtmftimeout = DEFAULT_DTMF_TIMEOUT;

static int rtpstart = 0;		/*!< First port for RTP sessions (set in rtp.conf) */
static int rtpend = 0;			/*!< Last port for RTP sessions (set in rtp.conf) */
static int rtpdebug = 0;		/*!< Are we debugging? */
static struct sockaddr_in rtpdebugaddr;	/*!< Debug packets to/from this host */
#ifdef SO_NO_CHECK
static int nochecksums = 0;
#endif

/*! \brief The value of each payload format mapping: */
struct rtpPayloadType {
	int isAstFormat; 	/*!< whether the following code is an AST_FORMAT */
	int code;
};

#define MAX_RTP_PT			256

#define FLAG_3389_WARNING		(1 << 0)
#define FLAG_NAT_ACTIVE			(3 << 1)
#define FLAG_NAT_INACTIVE		(0 << 1)
#define FLAG_NAT_INACTIVE_NOWARN	(1 << 1)

/*! \brief RTP session description */
struct ast_rtp {
	int s;
	char resp;
	struct ast_frame f;
	unsigned char rawdata[8192 + AST_FRIENDLY_OFFSET];
	unsigned int ssrc;		/*!< Synchronization source, RFC 3550, page 10. */
	unsigned int lastts;
	unsigned int lastdigitts;
	unsigned int lastrxts;
	unsigned int lastividtimestamp;
	unsigned int lastovidtimestamp;
	unsigned int lasteventseqn;
	unsigned int lasteventendseqn;
	int lasttxformat;
	int lastrxformat;
	int dtmfcount;
	unsigned int dtmfduration;
	int nat;
	unsigned int flags;
	struct sockaddr_in us;		/*!< Socket representation of the local endpoint. */
	struct sockaddr_in them;	/*!< Socket representation of the remote endpoint. */
	struct timeval rxcore;
	struct timeval txcore;
	struct timeval dtmfmute;
	struct ast_smoother *smoother;
	int *ioid;
	unsigned short seqno;		/*!< Sequence number, RFC 3550, page 13. */
	unsigned short rxseqno;
	struct sched_context *sched;
	struct io_context *io;
	void *data;
	ast_rtp_callback callback;
	struct rtpPayloadType current_RTP_PT[MAX_RTP_PT];
	int rtp_lookup_code_cache_isAstFormat; /*!< a cache for the result of rtp_lookup_code(): */
	int rtp_lookup_code_cache_code;
	int rtp_lookup_code_cache_result;
	struct ast_rtcp *rtcp;
};

/*!
 * \brief Structure defining an RTCP session.
 * 
 * The concept "RTCP session" is not defined in RFC 3550, but since 
 * this structure is analogous to ast_rtp, which tracks a RTP session, 
 * it is logical to think of this as a RTCP session.
 *
 * RTCP packet is defined on page 9 of RFC 3550.
 * 
 */
struct ast_rtcp {
	int s;				/*!< Socket */
	struct sockaddr_in us;		/*!< Socket representation of the local endpoint. */
	struct sockaddr_in them;	/*!< Socket representation of the remote endpoint. */
};

/*! \brief List of current sessions */
static AST_LIST_HEAD_STATIC(protos, ast_rtp_protocol);

int ast_rtp_fd(struct ast_rtp *rtp)
{
	return rtp->s;
}

int ast_rtcp_fd(struct ast_rtp *rtp)
{
	if (rtp->rtcp)
		return rtp->rtcp->s;
	return -1;
}

void ast_rtp_set_data(struct ast_rtp *rtp, void *data)
{
	rtp->data = data;
}

void ast_rtp_set_callback(struct ast_rtp *rtp, ast_rtp_callback callback)
{
	rtp->callback = callback;
}

void ast_rtp_setnat(struct ast_rtp *rtp, int nat)
{
	rtp->nat = nat;
}

static struct ast_frame *send_dtmf(struct ast_rtp *rtp)
{
	char iabuf[INET_ADDRSTRLEN];

	if (ast_tvcmp(ast_tvnow(), rtp->dtmfmute) < 0) {
		if (option_debug)
			ast_log(LOG_DEBUG, "Ignore potential DTMF echo from '%s'\n", ast_inet_ntoa(iabuf, sizeof(iabuf), rtp->them.sin_addr));
		rtp->resp = 0;
		rtp->dtmfduration = 0;
		return &ast_null_frame;
	}
	if (option_debug)
		ast_log(LOG_DEBUG, "Sending dtmf: %d (%c), at %s\n", rtp->resp, rtp->resp, ast_inet_ntoa(iabuf, sizeof(iabuf), rtp->them.sin_addr));
	if (rtp->resp == 'X') {
		rtp->f.frametype = AST_FRAME_CONTROL;
		rtp->f.subclass = AST_CONTROL_FLASH;
	} else {
		rtp->f.frametype = AST_FRAME_DTMF;
		rtp->f.subclass = rtp->resp;
	}
	rtp->f.datalen = 0;
	rtp->f.samples = 0;
	rtp->f.mallocd = 0;
	rtp->f.src = "RTP";
	rtp->resp = 0;
	rtp->dtmfduration = 0;