chan_mgcp.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 Implementation of Media Gateway Control Protocol
 *
 * \author Mark Spencer <markster@digium.com>
 *
 * \par See also
 * \arg \ref Config_mgcp
 * \arg \ref res_pktccops
 *
 * \ingroup channel_drivers
 */

/*** MODULEINFO
        <use>res_pktccops</use>
 ***/

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision$")

#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <fcntl.h>
#include <netdb.h>
#include <sys/signal.h>
#include <signal.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <arpa/inet.h>
#include <ctype.h>

#include "asterisk/lock.h"
#include "asterisk/channel.h"
#include "asterisk/config.h"
#include "asterisk/module.h"
#include "asterisk/pbx.h"
#include "asterisk/sched.h"
#include "asterisk/io.h"
#include "asterisk/rtp_engine.h"
#include "asterisk/acl.h"
#include "asterisk/callerid.h"
#include "asterisk/cli.h"
#include "asterisk/say.h"
#include "asterisk/cdr.h"
#include "asterisk/astdb.h"
#include "asterisk/features.h"
#include "asterisk/app.h"
#include "asterisk/musiconhold.h"
#include "asterisk/utils.h"
#include "asterisk/netsock.h"
#include "asterisk/causes.h"
#include "asterisk/dsp.h"
#include "asterisk/devicestate.h"
#include "asterisk/stringfields.h"
#include "asterisk/abstract_jb.h"
#include "asterisk/event.h"
#include "asterisk/chanvars.h"
#include "asterisk/pktccops.h"

/*
 * Define to work around buggy dlink MGCP phone firmware which
 * appears not to know that "rt" is part of the "G" package.
 */
/* #define DLINK_BUGGY_FIRMWARE	*/

#define MGCPDUMPER
#define DEFAULT_EXPIRY	120
#define MAX_EXPIRY	3600
#define DIRECTMEDIA	1

#ifndef INADDR_NONE
#define INADDR_NONE (in_addr_t)(-1)
#endif

/*! Global jitterbuffer configuration - by default, jb is disabled */
static struct ast_jb_conf default_jbconf =
{
	.flags = 0,
	.max_size = -1,
	.resync_threshold = -1,
	.impl = "",
	.target_extra = -1,
};
static struct ast_jb_conf global_jbconf;

static const char tdesc[] = "Media Gateway Control Protocol (MGCP)";
static const char config[] = "mgcp.conf";

#define MGCP_DTMF_RFC2833	(1 << 0)
#define MGCP_DTMF_INBAND	(1 << 1)
#define MGCP_DTMF_HYBRID	(1 << 2)

#define DEFAULT_MGCP_GW_PORT	2427 /*!< From RFC 2705 */
#define DEFAULT_MGCP_CA_PORT	2727 /*!< From RFC 2705 */
#define MGCP_MAX_PACKET		1500 /*!< Also from RFC 2543, should sub headers tho */
#define DEFAULT_RETRANS		1000 /*!< How frequently to retransmit */
#define MAX_RETRANS		5    /*!< Try only 5 times for retransmissions */

/*! MGCP rtp stream modes { */
#define MGCP_CX_SENDONLY	0
#define MGCP_CX_RECVONLY	1
#define MGCP_CX_SENDRECV	2
#define MGCP_CX_CONF		3
#define MGCP_CX_CONFERENCE	3
#define MGCP_CX_MUTE		4
#define MGCP_CX_INACTIVE	4
/*! } */

static const char * const mgcp_cxmodes[] = {
	"sendonly",
	"recvonly",
	"sendrecv",
	"confrnce",
	"inactive"
};

enum {
	MGCP_CMD_EPCF,
	MGCP_CMD_CRCX,
	MGCP_CMD_MDCX,
	MGCP_CMD_DLCX,
	MGCP_CMD_RQNT,
	MGCP_CMD_NTFY,
	MGCP_CMD_AUEP,
	MGCP_CMD_AUCX,
	MGCP_CMD_RSIP
};

static char context[AST_MAX_EXTENSION] = "default";

static char language[MAX_LANGUAGE] = "";
static char musicclass[MAX_MUSICCLASS] = "";
static char parkinglot[AST_MAX_CONTEXT];
static char cid_num[AST_MAX_EXTENSION] = "";
static char cid_name[AST_MAX_EXTENSION] = "";

static int dtmfmode = 0;
static int nat = 0;
static int ncs = 0;
static int pktcgatealloc = 0;
static int hangupongateremove = 0;

static ast_group_t cur_callergroup = 0;
static ast_group_t cur_pickupgroup = 0;

static struct {
	unsigned int tos;
	unsigned int tos_audio;
	unsigned int cos;
	unsigned int cos_audio;
} qos = { 0, 0, 0, 0 };

static int immediate = 0;

static int callwaiting = 0;

static int callreturn = 0;

static int slowsequence = 0;

static int threewaycalling = 0;

/*! This is for flashhook transfers */
static int transfer = 0;

static int cancallforward = 0;

static int singlepath = 0;

static int directmedia = DIRECTMEDIA;

static char accountcode[AST_MAX_ACCOUNT_CODE] = "";

static char mailbox[AST_MAX_EXTENSION];

static int amaflags = 0;

static int adsi = 0;

static unsigned int oseq;

/*! Wait up to 16 seconds for first digit (FXO logic) */
static int firstdigittimeout = 16000;

/*! How long to wait for following digits (FXO logic) */
static int gendigittimeout = 8000;

/*! How long to wait for an extra digit, if there is an ambiguous match */
static int matchdigittimeout = 3000;

/*! Protect the monitoring thread, so only one process can kill or start it, and not
    when it's doing something critical. */
AST_MUTEX_DEFINE_STATIC(netlock);

AST_MUTEX_DEFINE_STATIC(monlock);

/*! This is the thread for the monitor which checks for input on the channels
 *  which are not currently in use.
 */
static pthread_t monitor_thread = AST_PTHREADT_NULL;

static int restart_monitor(void);

static format_t capability = AST_FORMAT_ULAW;
static int nonCodecCapability = AST_RTP_DTMF;

static char ourhost[MAXHOSTNAMELEN];
static struct in_addr __ourip;
static int ourport;

static int mgcpdebug = 0;

static struct ast_sched_context *sched;
static struct io_context *io;
/*! The private structures of the mgcp channels are linked for
 * selecting outgoing channels
 */

#define MGCP_MAX_HEADERS	64
#define MGCP_MAX_LINES		64

struct mgcp_request {
	int len;
	char *verb;
	char *identifier;
	char *endpoint;
	char *version;
	int headers;			/*!< MGCP Headers */
	char *header[MGCP_MAX_HEADERS];
	int lines;			/*!< SDP Content */
	char *line[MGCP_MAX_LINES];
	char data[MGCP_MAX_PACKET];
	int cmd;                        /*!< int version of verb = command */
	unsigned int trid;              /*!< int version of identifier = transaction id */
	struct mgcp_request *next;      /*!< next in the queue */
};

/*! \brief mgcp_message: MGCP message for queuing up */
struct mgcp_message {
	struct mgcp_endpoint *owner_ep;
	struct mgcp_subchannel *owner_sub;
	int retrans;
	unsigned long expire;
	unsigned int seqno;
	int len;
	struct mgcp_message *next;
	char buf[0];
};

#define RESPONSE_TIMEOUT 30	/*!< in seconds */

struct mgcp_response {
	time_t whensent;
	int len;
	int seqno;
	struct mgcp_response *next;
	char buf[0];
};

#define MAX_SUBS 2

#define SUB_REAL 0
#define SUB_ALT  1

struct mgcp_subchannel {
	/*! subchannel magic string.
	   Needed to prove that any subchannel pointer passed by asterisk
	   really points to a valid subchannel memory area.
	   Ugly.. But serves the purpose for the time being.
	 */
#define MGCP_SUBCHANNEL_MAGIC "!978!"
	char magic[6];
	ast_mutex_t lock;
	int id;
	struct ast_channel *owner;
	struct mgcp_endpoint *parent;
	struct ast_rtp_instance *rtp;
	struct sockaddr_in tmpdest;
	char txident[80]; /*! \todo FIXME txident is replaced by rqnt_ident in endpoint.
			This should be obsoleted */
	char cxident[80];
	char callid[80];
	int cxmode;
	struct mgcp_request *cx_queue; /*!< pending CX commands */
	ast_mutex_t cx_queue_lock;     /*!< CX queue lock */
	int nat;
	int iseq;                      /*!< Not used? RTP? */
	int outgoing;
	int alreadygone;
	int sdpsent;
	struct cops_gate *gate;
	struct mgcp_subchannel *next;  /*!< for out circular linked list */
};

#define MGCP_ONHOOK  1
#define MGCP_OFFHOOK 2

#define TYPE_TRUNK 1
#define TYPE_LINE  2

struct mgcp_endpoint {
	ast_mutex_t lock;
	char name[80];
	struct mgcp_subchannel *sub;		/*!< Pointer to our current connection, channel and stuff */
	char accountcode[AST_MAX_ACCOUNT_CODE];
	char exten[AST_MAX_EXTENSION];		/*!< Extention where to start */
	char context[AST_MAX_EXTENSION];
	char language[MAX_LANGUAGE];
	char cid_num[AST_MAX_EXTENSION];	/*!< Caller*ID number */
	char cid_name[AST_MAX_EXTENSION];	/*!< Caller*ID name */
	char lastcallerid[AST_MAX_EXTENSION];	/*!< Last Caller*ID */
	char dtmf_buf[AST_MAX_EXTENSION];	/*!< place to collect digits be */
	char call_forward[AST_MAX_EXTENSION];	/*!< Last Caller*ID */
	char musicclass[MAX_MUSICCLASS];
	char curtone[80];			/*!< Current tone */
	char mailbox[AST_MAX_EXTENSION];
	char parkinglot[AST_MAX_CONTEXT];   /*!< Parkinglot */
	struct ast_event_sub *mwi_event_sub;
	ast_group_t callgroup;
	ast_group_t pickupgroup;
	int callwaiting;
	int hascallwaiting;
	int transfer;
	int threewaycalling;
	int singlepath;
	int cancallforward;
	int directmedia;
	int callreturn;
	int dnd; /* How does this affect callwait? Do we just deny a mgcp_request if we're dnd? */
	int hascallerid;
	int hidecallerid;
	int dtmfmode;
	int amaflags;
	int ncs;
	int pktcgatealloc;
	int hangupongateremove;
	int type;
	int slowsequence;			/*!< MS: Sequence the endpoint as a whole */
	int group;
	int iseq; /*!< Not used? */
	int lastout; /*!< tracking this on the subchannels.  Is it needed here? */
	int needdestroy; /*!< Not used? */
	format_t capability;
	int nonCodecCapability;
	int onhooktime;
	int msgstate; /*!< voicemail message state */
	int immediate;
	int hookstate;
	int adsi;
	char rqnt_ident[80];             /*!< request identifier */
	struct mgcp_request *rqnt_queue; /*!< pending RQNT commands */
	ast_mutex_t rqnt_queue_lock;
	struct mgcp_request *cmd_queue;  /*!< pending commands other than RQNT */
	ast_mutex_t cmd_queue_lock;
	int delme;                       /*!< needed for reload */
	int needaudit;                   /*!< needed for reload */
	struct ast_dsp *dsp; /*!< XXX Should there be a dsp/subchannel? XXX */
	/* owner is tracked on the subchannels, and the *sub indicates whos in charge */
	/* struct ast_channel *owner; */
	/* struct ast_rtp *rtp; */
	/* struct sockaddr_in tmpdest; */
	/* message go the the endpoint and not the channel so they stay here */
	struct ast_variable *chanvars;		/*!< Variables to set for channel created by user */
	struct mgcp_endpoint *next;
	struct mgcp_gateway *parent;
};

static struct mgcp_gateway {
	/* A gateway containing one or more endpoints */
	char name[80];
	int isnamedottedip; /*!< is the name FQDN or dotted ip */
	struct sockaddr_in addr;
	struct sockaddr_in defaddr;
	struct in_addr ourip;
	int dynamic;
	int expire;		/*!< XXX Should we ever expire dynamic registrations? XXX */
	struct mgcp_endpoint *endpoints;
	struct ast_ha *ha;
/* obsolete
	time_t lastouttime;
	int lastout;
	int messagepending;
*/
/* Wildcard endpoint name */
	char wcardep[30];
	struct mgcp_message *msgs; /*!< gw msg queue */
	ast_mutex_t msgs_lock;     /*!< queue lock */
	int retransid;             /*!< retrans timer id */
	int delme;                 /*!< needed for reload */
	int realtime;
	struct mgcp_response *responses;
	struct mgcp_gateway *next;
} *gateways = NULL;

AST_MUTEX_DEFINE_STATIC(mgcp_reload_lock);
static int mgcp_reloading = 0;

/*! \brief gatelock: mutex for gateway/endpoint lists */
AST_MUTEX_DEFINE_STATIC(gatelock);

static int mgcpsock  = -1;

static struct sockaddr_in bindaddr;

static struct ast_frame  *mgcp_read(struct ast_channel *ast);
static int transmit_response(struct mgcp_subchannel *sub, char *msg, struct mgcp_request *req, char *msgrest);
static int transmit_notify_request(struct mgcp_subchannel *sub, char *tone);
static int transmit_modify_request(struct mgcp_subchannel *sub);
static int transmit_connect(struct mgcp_subchannel *sub);
static int transmit_notify_request_with_callerid(struct mgcp_subchannel *sub, char *tone, char *callernum, char *callername);
static int transmit_modify_with_sdp(struct mgcp_subchannel *sub, struct ast_rtp_instance *rtp, format_t codecs);
static int transmit_connection_del(struct mgcp_subchannel *sub);
static int transmit_audit_endpoint(struct mgcp_endpoint *p);
static void start_rtp(struct mgcp_subchannel *sub);
static void handle_response(struct mgcp_endpoint *p, struct mgcp_subchannel *sub,
                            int result, unsigned int ident, struct mgcp_request *resp);
static void dump_cmd_queues(struct mgcp_endpoint *p, struct mgcp_subchannel *sub);
static char *mgcp_reload(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a);
static int reload_config(int reload);

static struct ast_channel *mgcp_request(const char *type, format_t format, const struct ast_channel *requestor, void *data, int *cause);
static int mgcp_call(struct ast_channel *ast, char *dest, int timeout);
static int mgcp_hangup(struct ast_channel *ast);
static int mgcp_answer(struct ast_channel *ast);
static struct ast_frame *mgcp_read(struct ast_channel *ast);
static int mgcp_write(struct ast_channel *ast, struct ast_frame *frame);
static int mgcp_indicate(struct ast_channel *ast, int ind, const void *data, size_t datalen);
static int mgcp_fixup(struct ast_channel *oldchan, struct ast_channel *newchan);
static int mgcp_senddigit_begin(struct ast_channel *ast, char digit);
static int mgcp_senddigit_end(struct ast_channel *ast, char digit, unsigned int duration);
static int mgcp_devicestate(void *data);
static void add_header_offhook(struct mgcp_subchannel *sub, struct mgcp_request *resp, char *tone);
static int transmit_connect_with_sdp(struct mgcp_subchannel *sub, struct ast_rtp_instance *rtp);
static struct mgcp_gateway *build_gateway(char *cat, struct ast_variable *v);
static int mgcp_alloc_pktcgate(struct mgcp_subchannel *sub);
static int acf_channel_read(struct ast_channel *chan, const char *funcname, char *preparse, char *buf, size_t buflen);
static struct ast_variable *add_var(const char *buf, struct ast_variable *list);
static struct ast_variable *copy_vars(struct ast_variable *src);

static const struct ast_channel_tech mgcp_tech = {
	.type = "MGCP",
	.description = tdesc,
	.capabilities = AST_FORMAT_ULAW | AST_FORMAT_ALAW,
	.properties = AST_CHAN_TP_WANTSJITTER | AST_CHAN_TP_CREATESJITTER,
	.requester = mgcp_request,
	.devicestate = mgcp_devicestate,
	.call = mgcp_call,
	.hangup = mgcp_hangup,
	.answer = mgcp_answer,
	.read = mgcp_read,
	.write = mgcp_write,
	.indicate = mgcp_indicate,
	.fixup = mgcp_fixup,
	.send_digit_begin = mgcp_senddigit_begin,
	.send_digit_end = mgcp_senddigit_end,
	.bridge = ast_rtp_instance_bridge,
	.func_channel_read = acf_channel_read,
};

static void mwi_event_cb(const struct ast_event *event, void *userdata)
{
	/* This module does not handle MWI in an event-based manner.  However, it
	 * subscribes to MWI for each mailbox that is configured so that the core
	 * knows that we care about it.  Then, chan_mgcp will get the MWI from the
	 * event cache instead of checking the mailbox directly. */
}

static int has_voicemail(struct mgcp_endpoint *p)
{
	int new_msgs;
	struct ast_event *event;
	char *mbox, *cntx;

	cntx = mbox = ast_strdupa(p->mailbox);
	strsep(&cntx, "@");
	if (ast_strlen_zero(cntx))
		cntx = "default";

	event = ast_event_get_cached(AST_EVENT_MWI,
		AST_EVENT_IE_MAILBOX, AST_EVENT_IE_PLTYPE_STR, mbox,
		AST_EVENT_IE_CONTEXT, AST_EVENT_IE_PLTYPE_STR, cntx,
		AST_EVENT_IE_END);

	if (event) {
		new_msgs = ast_event_get_ie_uint(event, AST_EVENT_IE_NEWMSGS);
		ast_event_destroy(event);
	} else
		new_msgs = ast_app_has_voicemail(p->mailbox, NULL);

	return new_msgs;
}

static int unalloc_sub(struct mgcp_subchannel *sub)
{
	struct mgcp_endpoint *p = sub->parent;
	if (p->sub == sub) {
		ast_log(LOG_WARNING, "Trying to unalloc the real channel %s@%s?!?\n", p->name, p->parent->name);
		return -1;
	}
	ast_debug(1, "Released sub %d of channel %s@%s\n", sub->id, p->name, p->parent->name);

	sub->owner = NULL;
	if (!ast_strlen_zero(sub->cxident)) {
		transmit_connection_del(sub);
	}
	sub->cxident[0] = '\0';
	sub->callid[0] = '\0';
	sub->cxmode = MGCP_CX_INACTIVE;
	sub->outgoing = 0;
	sub->alreadygone = 0;
	memset(&sub->tmpdest, 0, sizeof(sub->tmpdest));
	if (sub->rtp) {
		ast_rtp_instance_destroy(sub->rtp);
		sub->rtp = NULL;
	}
	dump_cmd_queues(NULL, sub);
	return 0;
}

/* modified for new transport mechanism */
static int __mgcp_xmit(struct mgcp_gateway *gw, char *data, int len)
{
	int res;
	if (gw->addr.sin_addr.s_addr)
		res=sendto(mgcpsock, data, len, 0, (struct sockaddr *)&gw->addr, sizeof(struct sockaddr_in));
	else
		res=sendto(mgcpsock, data, len, 0, (struct sockaddr *)&gw->defaddr, sizeof(struct sockaddr_in));
	if (res != len) {
		ast_log(LOG_WARNING, "mgcp_xmit returned %d: %s\n", res, strerror(errno));
	}
	return res;
}

static int resend_response(struct mgcp_subchannel *sub, struct mgcp_response *resp)
{
	struct mgcp_endpoint *p = sub->parent;
	int res;
	ast_debug(1, "Retransmitting:\n%s\n to %s:%d\n", resp->buf, ast_inet_ntoa(p->parent->addr.sin_addr), ntohs(p->parent->addr.sin_port));
	res = __mgcp_xmit(p->parent, resp->buf, resp->len);
	if (res > 0)
		res = 0;
	return res;
}

static int send_response(struct mgcp_subchannel *sub, struct mgcp_request *req)
{
	struct mgcp_endpoint *p = sub->parent;
	int res;
	ast_debug(1, "Transmitting:\n%s\n to %s:%d\n", req->data, ast_inet_ntoa(p->parent->addr.sin_addr), ntohs(p->parent->addr.sin_port));
	res = __mgcp_xmit(p->parent, req->data, req->len);
	if (res > 0)
		res = 0;
	return res;
}

/* modified for new transport framework */
static void dump_queue(struct mgcp_gateway *gw, struct mgcp_endpoint *p)
{
	struct mgcp_message *cur, *q = NULL, *w, *prev;

	ast_mutex_lock(&gw->msgs_lock);
	for (prev = NULL, cur = gw->msgs; cur; prev = cur, cur = cur->next) {
		if (!p || cur->owner_ep == p) {
			if (prev) {
				prev->next = cur->next;
			} else {
				gw->msgs = cur->next;
			}

			ast_log(LOG_NOTICE, "Removing message from %s transaction %u\n",
				gw->name, cur->seqno);

			w = cur;
			if (q) {
				w->next = q;
			} else {
				w->next = NULL;
			}
			q = w;
		}
	}
	ast_mutex_unlock(&gw->msgs_lock);

	while (q) {
		cur = q;
		q = q->next;
		ast_free(cur);
	}
}

static void mgcp_queue_frame(struct mgcp_subchannel *sub, struct ast_frame *f)
{
	for (;;) {
		if (sub->owner) {
			if (!ast_channel_trylock(sub->owner)) {
				ast_queue_frame(sub->owner, f);
				ast_channel_unlock(sub->owner);
				break;
			} else {
				DEADLOCK_AVOIDANCE(&sub->lock);
			}
		} else {
			break;
		}
	}
}

static void mgcp_queue_hangup(struct mgcp_subchannel *sub)
{
	for (;;) {
		if (sub->owner) {
			if (!ast_channel_trylock(sub->owner)) {
				ast_queue_hangup(sub->owner);
				ast_channel_unlock(sub->owner);
				break;
			} else {
				DEADLOCK_AVOIDANCE(&sub->lock);
			}
		} else {
			break;
		}
	}
}

static void mgcp_queue_control(struct mgcp_subchannel *sub, int control)
{
	struct ast_frame f = { AST_FRAME_CONTROL, { control } };
	return mgcp_queue_frame(sub, &f);
}

static int retrans_pkt(const void *data)
{
	struct mgcp_gateway *gw = (struct mgcp_gateway *)data;
	struct mgcp_message *cur, *exq = NULL, *w, *prev;
	int res = 0;

	/* find out expired msgs */
	ast_mutex_lock(&gw->msgs_lock);

	for (prev = NULL, cur = gw->msgs; cur; prev = cur, cur = cur->next) {
		if (cur->retrans < MAX_RETRANS) {
			cur->retrans++;
			ast_debug(1, "Retransmitting #%d transaction %u on [%s]\n",
				cur->retrans, cur->seqno, gw->name);
			__mgcp_xmit(gw, cur->buf, cur->len);
		} else {
			if (prev)
				prev->next = cur->next;
			else
				gw->msgs = cur->next;

			ast_log(LOG_WARNING, "Maximum retries exceeded for transaction %u on [%s]\n",
				cur->seqno, gw->name);

			w = cur;

			if (exq) {
				w->next = exq;
			} else {
				w->next = NULL;
			}
			exq = w;
		}
	}

	if (!gw->msgs) {
		gw->retransid = -1;
		res = 0;
	} else {
		res = 1;
	}
	ast_mutex_unlock(&gw->msgs_lock);

	while (exq) {
		cur = exq;
		/* time-out transaction */
		handle_response(cur->owner_ep, cur->owner_sub, 406, cur->seqno, NULL);
		exq = exq->next;
		ast_free(cur);
	}

	return res;
}

/* modified for the new transaction mechanism */
static int mgcp_postrequest(struct mgcp_endpoint *p, struct mgcp_subchannel *sub,
                            char *data, int len, unsigned int seqno)
{
	struct mgcp_message *msg;
	struct mgcp_message *cur;
	struct mgcp_gateway *gw;
	struct timeval now;

	if (!(msg = ast_malloc(sizeof(*msg) + len))) {
		return -1;
	}
	if (!(gw = ((p && p->parent) ? p->parent : NULL))) {
		ast_free(msg);
		return -1;
	}

	msg->owner_sub = sub;
	msg->owner_ep = p;
	msg->seqno = seqno;
	msg->next = NULL;
	msg->len = len;
	msg->retrans = 0;
	memcpy(msg->buf, data, msg->len);

	ast_mutex_lock(&gw->msgs_lock);
	for (cur = gw->msgs; cur && cur->next; cur = cur->next);
	if (cur) {
		cur->next = msg;
	} else {
		gw->msgs = msg;
	}

	now = ast_tvnow();
	msg->expire = now.tv_sec * 1000 + now.tv_usec / 1000 + DEFAULT_RETRANS;

	if (gw->retransid == -1)
		gw->retransid = ast_sched_add(sched, DEFAULT_RETRANS, retrans_pkt, (void *)gw);
	ast_mutex_unlock(&gw->msgs_lock);
	__mgcp_xmit(gw, msg->buf, msg->len);
	/* XXX Should schedule retransmission XXX */
	return 0;
}

/* modified for new transport */
static int send_request(struct mgcp_endpoint *p, struct mgcp_subchannel *sub,
                        struct mgcp_request *req, unsigned int seqno)
{
	int res = 0;
	struct mgcp_request **queue, *q, *r, *t;
	ast_mutex_t *l;

	ast_debug(1, "Slow sequence is %d\n", p->slowsequence);
	if (p->slowsequence) {
		queue = &p->cmd_queue;
		l = &p->cmd_queue_lock;
		ast_mutex_lock(l);
	} else {
		switch (req->cmd) {
		case MGCP_CMD_DLCX:
			queue = &sub->cx_queue;
			l = &sub->cx_queue_lock;
			ast_mutex_lock(l);
			q = sub->cx_queue;
			/* delete pending cx cmds */
			/* buggy sb5120 */
			if (!sub->parent->ncs) {
				while (q) {
					r = q->next;
					ast_free(q);
					q = r;
				}
				*queue = NULL;
			}
			break;

		case MGCP_CMD_CRCX:
		case MGCP_CMD_MDCX:
			queue = &sub->cx_queue;
			l = &sub->cx_queue_lock;
			ast_mutex_lock(l);
			break;

		case MGCP_CMD_RQNT:
			queue = &p->rqnt_queue;
			l = &p->rqnt_queue_lock;
			ast_mutex_lock(l);
			break;

		default:
			queue = &p->cmd_queue;
			l = &p->cmd_queue_lock;
			ast_mutex_lock(l);
			break;
		}
	}

	if (!(r = ast_malloc(sizeof(*r)))) {
		ast_log(LOG_WARNING, "Cannot post MGCP request: insufficient memory\n");
		ast_mutex_unlock(l);
		return -1;
	}
	memcpy(r, req, sizeof(*r));

	if (!(*queue)) {
		ast_debug(1, "Posting Request:\n%s to %s:%d\n", req->data,
			ast_inet_ntoa(p->parent->addr.sin_addr), ntohs(p->parent->addr.sin_port));

		res = mgcp_postrequest(p, sub, req->data, req->len, seqno);
	} else {
		ast_debug(1, "Queueing Request:\n%s to %s:%d\n", req->data,
			ast_inet_ntoa(p->parent->addr.sin_addr), ntohs(p->parent->addr.sin_port));
	}

	/* XXX find tail. We could also keep tail in the data struct for faster access */
	for (t = *queue; t && t->next; t = t->next);

	r->next = NULL;
	if (t)
		t->next = r;
	else
		*queue = r;

	ast_mutex_unlock(l);

	return res;
}

static int mgcp_call(struct ast_channel *ast, char *dest, int timeout)
{
	int res;
	struct mgcp_endpoint *p;
	struct mgcp_subchannel *sub;
	char tone[50] = "";
	const char *distinctive_ring = NULL;
	struct varshead *headp;
	struct ast_var_t *current;

	ast_debug(3, "MGCP mgcp_call(%s)\n", ast->name);
	sub = ast->tech_pvt;
	p = sub->parent;
	headp = &ast->varshead;
	AST_LIST_TRAVERSE(headp,current,entries) {
		/* Check whether there is an ALERT_INFO variable */
		if (strcasecmp(ast_var_name(current),"ALERT_INFO") == 0) {
			distinctive_ring = ast_var_value(current);
		}
	}

	ast_mutex_lock(&sub->lock);
	switch (p->hookstate) {
	case MGCP_OFFHOOK:
		if (!ast_strlen_zero(distinctive_ring)) {
			snprintf(tone, sizeof(tone), "L/wt%s", distinctive_ring);
			ast_debug(3, "MGCP distinctive callwait %s\n", tone);
		} else {
			ast_copy_string(tone, (p->ncs ? "L/wt1" : "L/wt"), sizeof(tone));
			ast_debug(3, "MGCP normal callwait %s\n", tone);
		}
		break;
	case MGCP_ONHOOK:
	default:
		if (!ast_strlen_zero(distinctive_ring)) {
			snprintf(tone, sizeof(tone), "L/r%s", distinctive_ring);
			ast_debug(3, "MGCP distinctive ring %s\n", tone);
		} else {
			ast_copy_string(tone, "L/rg", sizeof(tone));
			ast_debug(3, "MGCP default ring\n");
		}
		break;
	}

	if ((ast->_state != AST_STATE_DOWN) && (ast->_state != AST_STATE_RESERVED)) {
		ast_log(LOG_WARNING, "mgcp_call called on %s, neither down nor reserved\n", ast->name);
		ast_mutex_unlock(&sub->lock);
		return -1;
	}

	res = 0;
	sub->outgoing = 1;
	sub->cxmode = MGCP_CX_RECVONLY;
	ast_setstate(ast, AST_STATE_RINGING);
	if (p->type == TYPE_LINE) {
		if (!sub->rtp) {
			start_rtp(sub);
		} else {
			transmit_modify_request(sub);
		}

		if (sub->next->owner && !ast_strlen_zero(sub->next->cxident) && !ast_strlen_zero(sub->next->callid)) {
			/* try to prevent a callwait from disturbing the other connection */
			sub->next->cxmode = MGCP_CX_RECVONLY;
			transmit_modify_request(sub->next);
		}

		transmit_notify_request_with_callerid(sub, tone,
			S_COR(ast->connected.id.number.valid, ast->connected.id.number.str, ""),
			S_COR(ast->connected.id.name.valid, ast->connected.id.name.str, ""));
		ast_setstate(ast, AST_STATE_RINGING);

		if (sub->next->owner && !ast_strlen_zero(sub->next->cxident) && !ast_strlen_zero(sub->next->callid)) {
			/* Put the connection back in sendrecv */
			sub->next->cxmode = MGCP_CX_SENDRECV;
			transmit_modify_request(sub->next);
		}
	} else {
		ast_log(LOG_NOTICE, "Don't know how to dial on trunks yet\n");
		res = -1;
	}
	ast_mutex_unlock(&sub->lock);
	return res;
}

static int mgcp_hangup(struct ast_channel *ast)
{
	struct mgcp_subchannel *sub = ast->tech_pvt;
	struct mgcp_endpoint *p = sub->parent;
	struct ast_channel *bridged;

	ast_debug(1, "mgcp_hangup(%s)\n", ast->name);
	if (!ast->tech_pvt) {
		ast_debug(1, "Asked to hangup channel not connected\n");
		return 0;
	}
	if (strcmp(sub->magic, MGCP_SUBCHANNEL_MAGIC)) {
		ast_debug(1, "Invalid magic. MGCP subchannel freed up already.\n");
		return 0;
	}
	ast_mutex_lock(&sub->lock);
	ast_debug(3, "MGCP mgcp_hangup(%s) on %s@%s\n", ast->name, p->name, p->parent->name);

	if ((p->dtmfmode & MGCP_DTMF_INBAND) && p->dsp) {
		/* check whether other channel is active. */
		if (!sub->next->owner) {
			if (p->dtmfmode & MGCP_DTMF_HYBRID) {
				p->dtmfmode &= ~MGCP_DTMF_INBAND;
			}
			ast_debug(2, "MGCP free dsp on %s@%s\n", p->name, p->parent->name);
			ast_dsp_free(p->dsp);
			p->dsp = NULL;
		}
	}

	sub->owner = NULL;

	/* for deleting gate */
	if (p->pktcgatealloc && sub->gate) {
		sub->gate->gate_open = NULL;
		sub->gate->gate_remove = NULL;
		sub->gate->got_dq_gi = NULL;
		sub->gate->tech_pvt = NULL;
		if (sub->gate->state == GATE_ALLOC_PROGRESS || sub->gate->state == GATE_ALLOCATED) {
			ast_pktccops_gate_alloc(GATE_DEL, sub->gate, 0, 0, 0, 0, 0, 0, NULL, NULL);
		} else {
			sub->gate->deltimer = time(NULL) + 5;
		}
		sub->gate = NULL;
	}

	if (!ast_strlen_zero(sub->cxident)) {
		transmit_connection_del(sub);
	}
	sub->cxident[0] = '\0';
	if ((sub == p->sub) && sub->next->owner) {
		if (p->hookstate == MGCP_OFFHOOK) {
			if (sub->next->owner && ast_bridged_channel(sub->next->owner)) {
				/* ncs fix! */
				bridged = ast_bridged_channel(sub->next->owner);
				transmit_notify_request_with_callerid(p->sub, (p->ncs ? "L/wt1" : "L/wt"),
					S_COR(bridged->caller.id.number.valid, bridged->caller.id.number.str, ""),
					S_COR(bridged->caller.id.name.valid, bridged->caller.id.name.str, ""));
			}
		} else {
			/* set our other connection as the primary and swith over to it */
			p->sub = sub->next;
			p->sub->cxmode = MGCP_CX_RECVONLY;
			transmit_modify_request(p->sub);
			if (sub->next->owner && ast_bridged_channel(sub->next->owner)) {
				bridged = ast_bridged_channel(sub->next->owner);
				transmit_notify_request_with_callerid(p->sub, "L/rg",
					S_COR(bridged->caller.id.number.valid, bridged->caller.id.number.str, ""),
					S_COR(bridged->caller.id.name.valid, bridged->caller.id.name.str, ""));
			}
		}

	} else if ((sub == p->sub->next) && p->hookstate == MGCP_OFFHOOK) {
		transmit_notify_request(sub, p->ncs ? "" : "L/v");
	} else if (p->hookstate == MGCP_OFFHOOK) {
		transmit_notify_request(sub, "L/ro");
	} else {
		transmit_notify_request(sub, "");
	}

	ast->tech_pvt = NULL;
	sub->alreadygone = 0;