chan_sip.c

/*
 * Asterisk -- A telephony toolkit for Linux.
 *
 * Implementation of Session Initiation Protocol
 * 
 * Copyright (C) 1999, Mark Spencer
 *
 * Mark Spencer <markster@linux-support.net>
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License
 */

#include <stdio.h>
#include <ctype.h>
#include <pthread.h>
#include <string.h>
#include <asterisk/lock.h>
#include <asterisk/channel.h>
#include <asterisk/channel_pvt.h>
#include <asterisk/config.h>
#include <asterisk/logger.h>
#include <asterisk/module.h>
#include <asterisk/pbx.h>
#include <asterisk/options.h>
#include <asterisk/lock.h>
#include <asterisk/sched.h>
#include <asterisk/io.h>
#include <asterisk/rtp.h>
#include <asterisk/acl.h>
#include <asterisk/callerid.h>
#include <asterisk/cli.h>
#include <asterisk/md5.h>
#include <asterisk/app.h>
#include <asterisk/musiconhold.h>
#include <asterisk/dsp.h>
#include <asterisk/parking.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <sys/signal.h>
#include <netinet/ip.h>

/* #define VOCAL_DATA_HACK */

#define SIPDUMPER
#define DEFAULT_DEFAULT_EXPIRY  120
#define DEFAULT_MAX_EXPIRY      3600
#define EXPIRY_GUARD_SECS	15

#define SIP_DTMF_RFC2833	(1 << 0)
#define SIP_DTMF_INBAND		(1 << 1)
#define SIP_DTMF_INFO		(1 << 2)

static int max_expiry = DEFAULT_MAX_EXPIRY;
static int default_expiry = DEFAULT_DEFAULT_EXPIRY;

#define DEFAULT_MAXMS		2000		/* Must be faster than 2 seconds by default */

#define DEFAULT_MAXMS		2000		/* Must be faster than 2 seconds by default */
#define DEFAULT_FREQ_OK		60 * 1000		/* How often to check for the host to be up */
#define DEFAULT_FREQ_NOTOK	10 * 1000		/* How often to check, if the host is down... */

#define DEFAULT_RETRANS		1000			/* How frequently to retransmit */
#define MAX_RETRANS			5				/* Try only 5 times for retransmissions */

static char *desc = "Session Initiation Protocol (SIP)";
static char *type = "sip";
static char *tdesc = "Session Initiation Protocol (SIP)";
static char *config = "sip.conf";

#define DEFAULT_SIP_PORT	5060	/* From RFC 2543 */
#define SIP_MAX_PACKET	1500		/* Also from RFC 2543, should sub headers tho */

static char context[AST_MAX_EXTENSION] = "default";

static char language[MAX_LANGUAGE] = "";

static char callerid[AST_MAX_EXTENSION] = "asterisk";

static char fromdomain[AST_MAX_EXTENSION] = "";

static int usecnt =0;
static pthread_mutex_t usecnt_lock = AST_MUTEX_INITIALIZER;

/* Protect the interface list (of sip_pvt's) */
static pthread_mutex_t iflock = AST_MUTEX_INITIALIZER;

/* Protect the monitoring thread, so only one process can kill or start it, and not
   when it's doing something critical. */
static pthread_mutex_t netlock = AST_MUTEX_INITIALIZER;

static pthread_mutex_t monlock = AST_MUTEX_INITIALIZER;

/* 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 = 0;

static int restart_monitor(void);

/* Codecs that we support by default: */
static int capability = AST_FORMAT_ULAW | AST_FORMAT_ALAW | AST_FORMAT_GSM;
static int noncodeccapability = AST_RTP_DTMF;

static char ourhost[256];
static struct in_addr __ourip;
static int ourport;

static int sipdebug = 0;

static int tos = 0;

static int globaldtmfmode = SIP_DTMF_RFC2833;

/* Expire slowly */
static int expiry = 900;

static struct sched_context *sched;
static struct io_context *io;
/* The private structures of the  sip channels are linked for
   selecting outgoing channels */
   
#define SIP_MAX_HEADERS		64
#define SIP_MAX_LINES 		64

static struct sip_codec_pref {
	int codec;
	struct sip_codec_pref *next;
} *prefs;

struct sip_request {
  char *rlPart1; /* SIP Method Name or "SIP/2.0" protocol version */
  char *rlPart2; /* The Request URI or Response Status */
	int len;
	int headers;					/* SIP Headers */
	char *header[SIP_MAX_HEADERS];
	int lines;						/* SDP Content */
	char *line[SIP_MAX_LINES];
	char data[SIP_MAX_PACKET];
};

struct sip_pkt;

struct sip_route {
	struct sip_route *next;
	char hop[0];
};

static struct sip_pvt {
	pthread_mutex_t lock;				/* Channel private lock */
	char callid[80];					/* Global CallID */
	char randdata[80];	/* Random data */
	unsigned int ocseq;					/* Current outgoing seqno */
	unsigned int icseq;					/* Current incoming seqno */
	unsigned int callgroup;
	unsigned int pickupgroup;
	int lastinvite;						/* Last Cseq of invite */
	int alreadygone;					/* Whether or not we've already been destroyed by or peer */
	int needdestroy;					/* if we need to be destroyed */
	int capability;						/* Special capability */
	int noncodeccapability;
	int outgoing;						/* Outgoing or incoming call? */
	int authtries;						/* Times we've tried to authenticate */
	int insecure;						/* Don't check source port/ip */
	int expiry;						/* How long we take to expire */
	int branch;							/* One random number */
	int canreinvite;					/* Do we support reinvite */
	int progress;						/* Have sent 183 message progress */
	int tag;							/* Another random number */
	int nat;							/* Whether to try to support NAT */
	struct sockaddr_in sa;				/* Our peer */
	struct sockaddr_in recv;			/* Received as */
	struct in_addr ourip;				/* Our IP */
	struct ast_channel *owner;			/* Who owns us */
	char exten[AST_MAX_EXTENSION];		/* Extention where to start */
	char refer_to[AST_MAX_EXTENSION];	/* Place to store REFER-TO extension */
	char referred_by[AST_MAX_EXTENSION];/* Place to store REFERRED-BY extension */
	char refer_contact[AST_MAX_EXTENSION];/* Place to store Contact info from a REFER extension */
	struct sip_pvt *refer_call;			/* Call we are referring */
	struct sip_route *route;			/* Head of linked list of routing steps (fm Record-Route) */
	char remote_party_id[256];
	char context[AST_MAX_EXTENSION];
	char fromdomain[AST_MAX_EXTENSION];	/* Domain to show in the from field */
	char fromuser[AST_MAX_EXTENSION];	/* Domain to show in the user field */
	char tohost[AST_MAX_EXTENSION];		/* Host we should put in the "to" field */
	char language[MAX_LANGUAGE];
	char theirtag[256];				/* Their tag */
	char username[81];
	char peername[81];
	char uri[81];					/* Original requested URI */
	char peersecret[81];
	char callerid[256];					/* Caller*ID */
	char via[256];
	char accountcode[256];				/* Account code */
	char our_contact[256];				/* Our contact header */
	char realm[256];				/* Authorization realm */
	char nonce[256];				/* Authorization nonce */
	int amaflags;						/* AMA Flags */
	int pendinginvite;					/* Any pending invite */
	int pendingbye;						/* Need to send bye after we ack? */
	struct sip_request initreq;			/* Initial request */
	
	int maxtime;						/* Max time for first response */
	int initid;							/* Auto-congest ID if appropriate */
	int autokillid;						/* Auto-kill ID */

	int subscribed;
    	int stateid;
	int dialogver;
	
        int dtmfmode;
        struct ast_dsp *vad;
	
	struct sip_peer *peerpoke;			/* If this calls is to poke a peer, which one */
	struct sip_registry *registry;			/* If this is a REGISTER call, to which registry */
	struct ast_rtp *rtp;				/* RTP Session */
	struct sip_pkt *packets;			/* Packets scheduled for re-transmission */
	struct sip_pvt *next;
} *iflist = NULL;

struct sip_pkt {
	struct sip_pkt *next;				/* Next packet */
	int retrans;						/* Retransmission number */
	int seqno;							/* Sequence number */
	int resp;							/* non-zero if this is a response packet (e.g. 200 OK) */
	struct sip_pvt *owner;				/* Owner call */
	int retransid;						/* Retransmission ID */
	int packetlen;						/* Length of packet */
	char data[0];
};	

struct sip_user {
	/* Users who can access various contexts */
	char name[80];
	char secret[80];
	char context[80];
	char callerid[80];
	char methods[80];
	char accountcode[80];
	unsigned int callgroup;
	unsigned int pickupgroup;
	int nat;
	int hascallerid;
	int amaflags;
	int insecure;
	int canreinvite;
        int dtmfmode;
	struct ast_ha *ha;
	struct sip_user *next;
};

struct sip_peer {
	char name[80];
	char secret[80];
	char context[80];		/* JK02: peers need context too to allow parking etc */
	char methods[80];
	char username[80];
	char tohost[80];
	char fromuser[80];
	char fromdomain[80];
	char mailbox[AST_MAX_EXTENSION];
	int lastmsgssent;
	time_t	lastmsgcheck;
	int dynamic;
	int expire;
	int expiry;
	int capability;
	int insecure;
	int nat;
	int canreinvite;
	unsigned int callgroup;
	unsigned int pickupgroup;
        int dtmfmode;
	struct sockaddr_in addr;
	struct in_addr mask;

	/* Qualification */
	struct sip_pvt *call;		/* Call pointer */
	int pokeexpire;				/* When to expire poke */
	int lastms;					/* How long last response took (in ms), or -1 for no response */
	int maxms;					/* Max ms we will accept for the host to be up, 0 to not monitor */
	struct timeval ps;			/* Ping send time */
	
	struct sockaddr_in defaddr;
	struct ast_ha *ha;
	int delme;
	int lastmsg;
	struct sip_peer *next;
};

static struct ast_user_list {
	struct sip_user *users;
	pthread_mutex_t lock;
} userl = { NULL, AST_MUTEX_INITIALIZER };

static struct ast_peer_list {
	struct sip_peer *peers;
	pthread_mutex_t lock;
} peerl = { NULL, AST_MUTEX_INITIALIZER };


#define REG_STATE_UNREGISTERED 0
#define REG_STATE_REGSENT	   1
#define REG_STATE_AUTHSENT 	   2
#define REG_STATE_REGISTERED   3
#define REG_STATE_REJECTED	   4
#define REG_STATE_TIMEOUT	   5
#define REG_STATE_NOAUTH	   6

struct sip_registry {
	pthread_mutex_t lock;				/* Channel private lock */
	struct sockaddr_in addr;		/* Who we connect to for registration purposes */
	char username[80];				/* Who we are registering as */
	char authuser[80];				/* Who we *authenticate* as */
	char hostname[80];
	char secret[80];			/* Password or key name in []'s */
	char contact[80];			/* Contact extension */
	char random[80];
	int expire;					/* Sched ID of expiration */
	int timeout; 					/* sched id of sip_reg_timeout */
	int refresh;					/* How often to refresh */
	struct sip_pvt *call;				/* create a sip_pvt structure for each outbound "registration call" in progress */
	int regstate;
	int callid_valid;		/* 0 means we haven't chosen callid for this registry yet. */
	char callid[80];		/* Global CallID for this registry */
	unsigned int ocseq;		/* Sequence number we got to for REGISTERs for this registry */
	struct sockaddr_in us;			/* Who the server thinks we are */
	struct sip_registry *next;
};

#define REINVITE_INVITE		1
#define REINVITE_UPDATE		2

static int sip_do_register(struct sip_registry *r);
struct sip_registry *registrations;

static int sipsock  = -1;
static int globalnat = 0;

static struct sockaddr_in bindaddr;

static struct ast_frame  *sip_read(struct ast_channel *ast);
static int transmit_response(struct sip_pvt *p, char *msg, struct sip_request *req);
static int transmit_response_with_sdp(struct sip_pvt *p, char *msg, struct sip_request *req, int retrans);
static int transmit_response_with_auth(struct sip_pvt *p, char *msg, struct sip_request *req, char *rand, int reliable);
static int transmit_request(struct sip_pvt *p, char *msg, int inc, int reliable);
static int transmit_request_with_auth(struct sip_pvt *p, char *msg, int inc, int reliable);
static int transmit_invite(struct sip_pvt *p, char *msg, int sendsdp, char *auth, char *vxml_url);
static int transmit_reinvite_with_sdp(struct sip_pvt *p, struct ast_rtp *rtp);
static int transmit_info_with_digit(struct sip_pvt *p, char digit);
static int transmit_message_with_text(struct sip_pvt *p, char *text);
static int do_proxy_auth(struct sip_pvt *p, struct sip_request *req);
char *getsipuri(char *header);
static void free_old_route(struct sip_route *route);
static int build_reply_digest(struct sip_pvt *p, char *orig_header, char *digest, int digest_len);

static int __sip_xmit(struct sip_pvt *p, char *data, int len)
{
	int res;
	if (p->nat)
	    res=sendto(sipsock, data, len, 0, (struct sockaddr *)&p->recv, sizeof(struct sockaddr_in));
	else
	    res=sendto(sipsock, data, len, 0, (struct sockaddr *)&p->sa, sizeof(struct sockaddr_in));
	if (res != len) {
		ast_log(LOG_WARNING, "sip_xmit of %p (len %d) to %s returned %d: %s\n", data, len, inet_ntoa(p->sa.sin_addr), res, strerror(errno));
	}
	return res;
}

static void sip_destroy(struct sip_pvt *p);

static int retrans_pkt(void *data)
{
	struct sip_pkt *pkt=data;
	int res = 0;
	ast_pthread_mutex_lock(&pkt->owner->lock);
	if (1 /* !p->owner->needdestroy */) {
		if (pkt->retrans < MAX_RETRANS) {
			pkt->retrans++;
			if (sipdebug) {
				if (pkt->owner->nat)
					ast_verbose("Retransmitting #%d (NAT):\n%s\n to %s:%d\n", pkt->retrans, pkt->data, inet_ntoa(pkt->owner->recv.sin_addr), ntohs(pkt->owner->recv.sin_port));
				else
					ast_verbose("Retransmitting #%d (no NAT):\n%s\n to %s:%d\n", pkt->retrans, pkt->data, inet_ntoa(pkt->owner->sa.sin_addr), ntohs(pkt->owner->sa.sin_port));
			}
			__sip_xmit(pkt->owner, pkt->data, pkt->packetlen);
			res = 1;
		} else {
			ast_log(LOG_WARNING, "Maximum retries exceeded on call %s for seqno %d (%s)\n", pkt->owner->callid, pkt->seqno, pkt->resp ? "Response" : "Request");
			pkt->retransid = -1;
			if (pkt->owner->owner) {
				/* XXX Potential deadlocK?? XXX */
				ast_queue_hangup(pkt->owner->owner, 1);
			} else {
				/* If no owner, destroy now */
				ast_pthread_mutex_unlock(&pkt->owner->lock);
				sip_destroy(pkt->owner);
				pkt = NULL;
			}
		}
	} else {
		/* Don't bother retransmitting.  It's about to be killed anyway */
		pkt->retransid = -1;
		if (pkt->owner->owner) {
			/* XXX Potential deadlocK?? XXX */
			ast_queue_hangup(pkt->owner->owner, 1);
		} else {
			/* If no owner, destroy now */
			ast_pthread_mutex_unlock(&pkt->owner->lock);
			sip_destroy(pkt->owner);
			pkt=NULL;
		}
	}
	if (pkt)
		ast_pthread_mutex_unlock(&pkt->owner->lock);
	return res;
}

static int __sip_reliable_xmit(struct sip_pvt *p, int seqno, int resp, char *data, int len)
{
	struct sip_pkt *pkt;
	pkt = malloc(sizeof(struct sip_pkt) + len);
	if (!pkt)
		return -1;
	memset(pkt, 0, sizeof(struct sip_pkt));
	memcpy(pkt->data, data, len);
	pkt->packetlen = len;
	pkt->next = p->packets;
	pkt->owner = p;
	pkt->seqno = seqno;
	pkt->resp = resp;
	/* Schedule retransmission */
	pkt->retransid = ast_sched_add(sched, 1000, retrans_pkt, pkt);
	pkt->next = p->packets;
	p->packets = pkt;
	__sip_xmit(pkt->owner, pkt->data, pkt->packetlen);
	if (!strncasecmp(pkt->data, "INVITE", 6)) {
		/* Note this is a pending invite */
		p->pendinginvite = seqno;
	}
	return 0;
}

static int __sip_autodestruct(void *data)
{
	struct sip_pvt *p = data;
	p->autokillid = -1;
	ast_log(LOG_DEBUG, "Auto destroying call '%s'\n", p->callid);
	if (p->owner) {
		ast_log(LOG_WARNING, "Autodestruct on call '%s' with owner in place\n", p->callid);
		ast_queue_hangup(p->owner, 0);
	} else {
		sip_destroy(p);
	}
	return 0;
}

static int sip_scheddestroy(struct sip_pvt *p, int ms)
{
	if (p->autokillid > -1)
		ast_sched_del(sched, p->autokillid);
	p->autokillid = ast_sched_add(sched, ms, __sip_autodestruct, p);
	return 0;
}

static int sip_cancel_destroy(struct sip_pvt *p)
{
	if (p->autokillid > -1)
		ast_sched_del(sched, p->autokillid);
	p->autokillid = -1;
	return 0;
}

static int __sip_ack(struct sip_pvt *p, int seqno, int resp)
{
	struct sip_pkt *cur, *prev = NULL;
	int res = -1;
	int resetinvite = 0;
	cur = p->packets;
	while(cur) {
		if ((cur->seqno == seqno) && (cur->resp == resp)) {
			if (!resp && (seqno == p->pendinginvite)) {
				ast_log(LOG_DEBUG, "Acked pending invite %d\n", p->pendinginvite);
				p->pendinginvite = 0;
				resetinvite = 1;
			}
			/* this is our baby */
			if (prev)
				prev->next = cur->next;
			else
				p->packets = cur->next;
			if (cur->retransid > -1)
				ast_sched_del(sched, cur->retransid);
			free(cur);
			res = 0;
			break;
		}
		prev = cur;
		cur = cur->next;
	}
	ast_log(LOG_DEBUG, "Stopping retransmission on '%s' of %s %d: %s\n", p->callid, resp ? "Response" : "Request", seqno, res ? "Not Found" : "Found");
	return res;
}

static int send_response(struct sip_pvt *p, struct sip_request *req, int reliable, int seqno)
{
	int res;
	if (sipdebug) {
		if (p->nat)
			ast_verbose("%sTransmitting (NAT):\n%s\n to %s:%d\n", reliable ? "Reliably " : "", req->data, inet_ntoa(p->recv.sin_addr), ntohs(p->recv.sin_port));
		else
			ast_verbose("%sTransmitting (no NAT):\n%s\n to %s:%d\n", reliable ? "Reliably " : "", req->data, inet_ntoa(p->sa.sin_addr), ntohs(p->sa.sin_port));
	}
	if (reliable)
		res = __sip_reliable_xmit(p, seqno, 1, req->data, req->len);
	else
		res = __sip_xmit(p, req->data, req->len);
	if (res > 0)
		res = 0;
	return res;
}

static int send_request(struct sip_pvt *p, struct sip_request *req, int reliable, int seqno)
{
	int res;
	if (sipdebug) {
		if (p->nat)
			ast_verbose("%sTransmitting:\n%s (NAT) to %s:%d\n", reliable ? "Reliably " : "", req->data, inet_ntoa(p->recv.sin_addr), ntohs(p->recv.sin_port));
		else
			ast_verbose("%sTransmitting:\n%s (no NAT) to %s:%d\n", reliable ? "Reliably " : "", req->data, inet_ntoa(p->sa.sin_addr), ntohs(p->sa.sin_port));
	}
	if (reliable)
		res = __sip_reliable_xmit(p, seqno, 0, req->data, req->len);
	else
		res = __sip_xmit(p, req->data, req->len);
	return res;
}

static char *ditch_braces(char *tmp)
{
	char *c = tmp;
	char *n;
	c = tmp;
	if ((n = strchr(tmp, '<')) ) {
		c = n + 1;
		while(*c && *c != '>') c++;
		if (*c != '>') {
			ast_log(LOG_WARNING, "No closing brace in '%s'\n", tmp);
		} else {
			*c = '\0';
		}
		return n+1;
	}
	return c;
}

static int sip_sendtext(struct ast_channel *ast, char *text)
{
	struct sip_pvt *p = ast->pvt->pvt;
	if (sipdebug) 
		ast_verbose("Sending text %s on %s\n", text, ast->name);
	if (!p)
		return -1;
	if (!text || !strlen(text))
		return 0;
	if (sipdebug)
		ast_verbose("Really sending text %s on %s\n", text, ast->name);
	transmit_message_with_text(p, text);
	return 0;	
}

static int create_addr(struct sip_pvt *r, char *peer)
{
	struct hostent *hp;
	struct sip_peer *p;
	int found=0;
	char *port;

	r->sa.sin_family = AF_INET;
	ast_pthread_mutex_lock(&peerl.lock);
	p = peerl.peers;
	while(p) {
		if (!strcasecmp(p->name, peer)) {
			found++;
			r->capability = p->capability;
			r->nat = p->nat;
			if (r->rtp) {
				ast_log(LOG_DEBUG, "Setting NAT on RTP to %d\n", r->nat);
				ast_rtp_setnat(r->rtp, r->nat);
			}
			strncpy(r->peername, p->username, sizeof(r->peername)-1);
			strncpy(r->peersecret, p->secret, sizeof(r->peersecret)-1);
			strncpy(r->username, p->username, sizeof(r->username)-1);
			strncpy(r->tohost, p->tohost, sizeof(r->tohost)-1);
			if (!strlen(r->tohost)) {
				if (p->addr.sin_addr.s_addr)
					snprintf(r->tohost, sizeof(r->tohost), inet_ntoa(p->addr.sin_addr));
				else
					snprintf(r->tohost, sizeof(r->tohost), inet_ntoa(p->defaddr.sin_addr));
			}
			if (strlen(p->fromdomain))
				strncpy(r->fromdomain, p->fromdomain, sizeof(r->fromdomain)-1);
			if (strlen(p->fromuser))
				strncpy(r->fromuser, p->fromuser, sizeof(r->fromuser)-1);
			r->insecure = p->insecure;
			r->canreinvite = p->canreinvite;
			r->maxtime = p->maxms;
			r->callgroup = p->callgroup;
			r->pickupgroup = p->pickupgroup;
			if (p->dtmfmode) {
				r->dtmfmode = p->dtmfmode;
				if (r->dtmfmode & SIP_DTMF_RFC2833)
					r->noncodeccapability |= AST_RTP_DTMF;
				else
					r->noncodeccapability &= ~AST_RTP_DTMF;
			}
			strncpy(r->context, p->context,sizeof(r->context)-1);
			if ((p->addr.sin_addr.s_addr || p->defaddr.sin_addr.s_addr) &&
				(!p->maxms || ((p->lastms > 0)  && (p->lastms <= p->maxms)))) {
				if (p->addr.sin_addr.s_addr) {
					r->sa.sin_addr = p->addr.sin_addr;
					r->sa.sin_port = p->addr.sin_port;
				} else {
					r->sa.sin_addr = p->defaddr.sin_addr;
					r->sa.sin_port = p->defaddr.sin_port;
				}
				memcpy(&r->recv, &r->sa, sizeof(r->recv));
				break;
			}
		}
		p = p->next;
	}
	ast_pthread_mutex_unlock(&peerl.lock);
	if (!p && !found) {
		if ((port=strchr(peer, ':'))) {
			*port='\0';
			port++;
		}
		hp = gethostbyname(peer);
		if (hp) {
			strncpy(r->tohost, peer, sizeof(r->tohost) - 1);
			memcpy(&r->sa.sin_addr, hp->h_addr, sizeof(r->sa.sin_addr));
			if (port) {
				r->sa.sin_port = htons(atoi(port));
			} else {
				r->sa.sin_port = htons(DEFAULT_SIP_PORT);
			}
			memcpy(&r->recv, &r->sa, sizeof(r->recv));
			return 0;
		} else {
			ast_log(LOG_WARNING, "No such host: %s\n", peer);
			return -1;
		}
	} else if (!p)
		return -1;
	else
		return 0;
}

static int auto_congest(void *nothing)
{
	struct sip_pvt *p = nothing;
	ast_pthread_mutex_lock(&p->lock);
	p->initid = -1;
	if (p->owner) {
		if (!pthread_mutex_trylock(&p->owner->lock)) {
			ast_log(LOG_NOTICE, "Auto-congesting %s\n", p->owner->name);
			ast_queue_control(p->owner, AST_CONTROL_CONGESTION, 0);
			ast_pthread_mutex_unlock(&p->owner->lock);
		}
	}
	ast_pthread_mutex_unlock(&p->lock);
	return 0;
}

static void sip_prefs_free(void)
{
	struct sip_codec_pref *cur, *next;
	cur = prefs;
	while(cur) {
		next = cur->next;
		free(cur);
		cur = next;
	}
	prefs = NULL;
}

static void sip_pref_remove(int format)
{
	struct sip_codec_pref *cur, *prev=NULL;
	cur = prefs;
	while(cur) {
		if (cur->codec == format) {
			if (prev)
				prev->next = cur->next;
			else
				prefs = cur->next;
			free(cur);
			return;
		}
		prev = cur;
		cur = cur->next;
	}
}

static int sip_pref_append(int format)
{
	struct sip_codec_pref *cur, *tmp;
	sip_pref_remove(format);
	tmp = (struct sip_codec_pref *)malloc(sizeof(struct sip_codec_pref));
	if (!tmp)
		return -1;
	memset(tmp, 0, sizeof(struct sip_codec_pref));
	tmp->codec = format;
	if (prefs) {
		cur = prefs;
		while(cur->next)
			cur = cur->next;
		cur->next = tmp;
	} else
		prefs = tmp;
	return 0;
}

static int sip_codec_choose(int formats)
{
	struct sip_codec_pref *cur;
	cur = prefs;
	while(cur) {
		if (formats & cur->codec)
			return cur->codec;
		cur = cur->next;
	}
	return ast_best_codec(formats);
}

static int sip_call(struct ast_channel *ast, char *dest, int timeout)
{
	int res;
	struct sip_pvt *p;
	char *vxml_url = NULL;
	struct varshead *headp;
	struct ast_var_t *current;
	
	p = ast->pvt->pvt;
	if ((ast->_state != AST_STATE_DOWN) && (ast->_state != AST_STATE_RESERVED)) {
		ast_log(LOG_WARNING, "sip_call called on %s, neither down nor reserved\n", ast->name);
		return -1;
	}

	/* Check whether there is a VXML_URL variable */
	headp=&ast->varshead;
	AST_LIST_TRAVERSE(headp,current,entries) {
		if (strcasecmp(ast_var_name(current),"VXML_URL")==0)
	        {
			vxml_url = ast_var_value(current);
			break;
		}
	}
	
	res = 0;
	p->outgoing = 1;
	transmit_invite(p, "INVITE", 1, NULL, vxml_url);
	if (p->maxtime) {
		/* Initialize auto-congest time */
		p->initid = ast_sched_add(sched, p->maxtime * 2, auto_congest, p);
	}
	return res;
}

static void __sip_destroy(struct sip_pvt *p, int lockowner)
{
	struct sip_pvt *cur, *prev = NULL;
	struct sip_pkt *cp;
	if (sipdebug)
		ast_log(LOG_DEBUG, "Destorying call '%s'\n", p->callid);
	if (p->stateid > -1)
		ast_extension_state_del(p->stateid, NULL);
	if (p->initid > -1)
		ast_sched_del(sched, p->initid);
	if (p->autokillid > -1)
		ast_sched_del(sched, p->autokillid);

	if (p->rtp) {
		ast_rtp_destroy(p->rtp);
	}
	if (p->route) {
		free_old_route(p->route);
		p->route = NULL;
	}
	/* Unlink us from the owner if we have one */
	if (p->owner) {
		if (lockowner)
			ast_pthread_mutex_lock(&p->owner->lock);
		ast_log(LOG_DEBUG, "Detaching from %s\n", p->owner->name);
		p->owner->pvt->pvt = NULL;
		if (lockowner)
			ast_pthread_mutex_unlock(&p->owner->lock);
	}
	cur = iflist;
	while(cur) {
		if (cur == p) {
			if (prev)
				prev->next = cur->next;
			else
				iflist = cur->next;
			break;
		}
		prev = cur;
		cur = cur->next;
	}
	if (!cur) {
		ast_log(LOG_WARNING, "%p is not in list?!?! \n", cur);
	} else {
		if (p->initid > -1)
			ast_sched_del(sched, p->initid);
		while((cp = p->packets)) {
			p->packets = p->packets->next;
			if (cp->retransid > -1)
				ast_sched_del(sched, cp->retransid);
			free(cp);
		}
		free(p);
	}
}
static void sip_destroy(struct sip_pvt *p)
{
	ast_pthread_mutex_lock(&iflock);
	__sip_destroy(p, 1);
	ast_pthread_mutex_unlock(&iflock);
}

/* Interface lookup code courtesy Tilghman of DrunkCoder.com.  Thanks! */

struct my_ifreq {
	char ifrn_name[IFNAMSIZ];	/* Interface name, e.g. "en0".  */
	struct sockaddr_in ifru_addr;
};

struct in_addr *lookup_iface(char *iface) {
	int mysock;
	int res;
	static struct  my_ifreq ifreq;
	memset(&ifreq, 0, sizeof(ifreq));
	strncpy(ifreq.ifrn_name,iface,sizeof(ifreq.ifrn_name) - 1);

	mysock = socket(PF_INET,SOCK_DGRAM,IPPROTO_IP);
	res = ioctl(mysock,SIOCGIFADDR,&ifreq);
	
	close(mysock);
	if (res < 0) {
		ast_log(LOG_WARNING, "Unable to get IP of %s: %s\n", iface, strerror(errno));
		return &__ourip;
	}
	return( (struct in_addr *) &ifreq.ifru_addr.sin_addr );
}

static struct in_addr *myaddrfor(struct in_addr *them)
{
	FILE *PROC;
	struct in_addr *temp = NULL;
	unsigned int remote_ip;
	char line[256];
	remote_ip = them->s_addr;
	
	PROC = fopen("/proc/net/route","r");
	if (!PROC) {
		/* If /proc/net/route doesn't exist, fall back to the old method */
		return &__ourip;
	}
	/* First line contains headers */
	fgets(line,sizeof(line),PROC);

	while (!feof(PROC)) {
		char iface[8];
		unsigned int dest, gateway, mask;
		int i,aoffset;
		char *fields[40];

		fgets(line,sizeof(line),PROC);

		aoffset = 0;
		for (i=0;i<sizeof(line);i++) {
			char *boffset;

			fields[aoffset++] = line + i;
			boffset = strchr(line + i,'\t');
			if (boffset == NULL) {
				/* Exit loop */
				break;
			} else {
				*boffset = '\0';
				i = boffset - line;
			}
		}

		sscanf(fields[0],"%s",iface);
		sscanf(fields[1],"%x",&dest);
		sscanf(fields[2],"%x",&gateway);
		sscanf(fields[7],"%x",&mask);
#if 0
		printf("Addr: %s %08x Dest: %08x Mask: %08x\n", inet_ntoa(*them), remote_ip, dest, mask);
#endif		
		if (((remote_ip & mask) ^ dest) == 0) {
			if (sipdebug)
				ast_verbose("Interface is %s\n",iface);
			temp = lookup_iface(iface);
			if (sipdebug)
				ast_verbose("IP Address is %s\n",inet_ntoa(*temp));
			break;
		}
	}
	fclose(PROC);
	if (!temp) {
		ast_log(LOG_WARNING, "Couldn't figure out how to get to %s.  Using default\n", inet_ntoa(*them));
 		temp = &__ourip;
 	}
	return temp;
}

static int transmit_response_reliable(struct sip_pvt *p, char *msg, struct sip_request *req);


static int sip_hangup(struct ast_channel *ast)
{
	struct sip_pvt *p = ast->pvt->pvt;
	int needcancel = 0;
	int needdestroy = 0;
	if (option_debug)
		ast_log(LOG_DEBUG, "sip_hangup(%s)\n", ast->name);
	if (!ast->pvt->pvt) {
		ast_log(LOG_DEBUG, "Asked to hangup channel not connected\n");
		return 0;
	}
	ast_pthread_mutex_lock(&p->lock);
	/* Determine how to disconnect */
	if (p->owner != ast) {
		ast_log(LOG_WARNING, "Huh?  We aren't the owner?\n");
		ast_pthread_mutex_unlock(&p->lock);
		return 0;
	}
	if (!ast || (ast->_state != AST_STATE_UP))
		needcancel = 1;
	/* Disconnect */
	p = ast->pvt->pvt;
        if (p->vad) {
            ast_dsp_free(p->vad);
        }
	p->owner = NULL;
	ast->pvt->pvt = NULL;

	needdestroy = 1;
	/* Start the process if it's not already started */
	if (!p->alreadygone && strlen(p->initreq.data)) {
		if (needcancel) {
			if (p->outgoing) {
				transmit_request_with_auth(p, "CANCEL", p->ocseq, 1);
				/* Actually don't destroy us yet, wait for the 487 on our original 
				   INVITE, but do set an autodestruct just in case. */
				needdestroy = 0;
				sip_scheddestroy(p, 15000);
			} else
				transmit_response_reliable(p, "403 Forbidden", &p->initreq);
		} else {
			if (!p->pendinginvite) {
				/* Send a hangup */
				transmit_request_with_auth(p, "BYE", 0, 1);
			} else {
				/* Note we will need a BYE when this all settles out
				   but we can't send one while we have "INVITE" outstanding. */
				p->pendingbye = 1;
			}
		}
	}
	p->needdestroy = needdestroy;
	ast_pthread_mutex_unlock(&p->lock);
	return 0;
}

static int sip_answer(struct ast_channel *ast)
{
	int res = 0,fmt;
	char *codec;
	struct sip_pvt *p = ast->pvt->pvt;

	
	if (ast->_state != AST_STATE_UP) {
	
	
	
		codec=pbx_builtin_getvar_helper(p->owner,"SIP_CODEC");
		if (codec) {
			ast_log(LOG_NOTICE, "Changing codec to '%s' for this call because of ${SIP_CODEC) variable\n",codec);
			fmt=ast_getformatbyname(codec);