path: root/pjnath/src/pjnath/turn_sock.c

/* $Id: turn_sock.c 4360 2013-02-21 11:26:35Z bennylp $ */
/* 
 * Copyright (C) 2008-2011 Teluu Inc. (http://www.teluu.com)
 * Copyright (C) 2003-2008 Benny Prijono <benny@prijono.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
 */
#include <pjnath/turn_sock.h>
#include <pj/activesock.h>
#include <pj/assert.h>
#include <pj/errno.h>
#include <pj/lock.h>
#include <pj/log.h>
#include <pj/pool.h>
#include <pj/ioqueue.h>

enum
{
    TIMER_NONE,
    TIMER_DESTROY
};


enum { MAX_BIND_RETRY = 100 };


#define INIT	0x1FFFFFFF

struct pj_turn_sock
{
    pj_pool_t		*pool;
    const char		*obj_name;
    pj_turn_session	*sess;
    pj_turn_sock_cb	 cb;
    void		*user_data;

    pj_bool_t		 is_destroying;
    pj_grp_lock_t	*grp_lock;

    pj_turn_alloc_param	 alloc_param;
    pj_stun_config	 cfg;
    pj_turn_sock_cfg	 setting;

    pj_timer_entry	 timer;

    int			 af;
    pj_turn_tp_type	 conn_type;
    pj_activesock_t	*active_sock;
    pj_ioqueue_op_key_t	 send_key;
};


/*
 * Callback prototypes.
 */
static pj_status_t turn_on_send_pkt(pj_turn_session *sess,
				    const pj_uint8_t *pkt,
				    unsigned pkt_len,
				    const pj_sockaddr_t *dst_addr,
				    unsigned dst_addr_len);
static void turn_on_channel_bound(pj_turn_session *sess,
				  const pj_sockaddr_t *peer_addr,
				  unsigned addr_len,
				  unsigned ch_num);
static void turn_on_rx_data(pj_turn_session *sess,
			    void *pkt,
			    unsigned pkt_len,
			    const pj_sockaddr_t *peer_addr,
			    unsigned addr_len);
static void turn_on_state(pj_turn_session *sess, 
			  pj_turn_state_t old_state,
			  pj_turn_state_t new_state);

static pj_bool_t on_data_read(pj_activesock_t *asock,
			      void *data,
			      pj_size_t size,
			      pj_status_t status,
			      pj_size_t *remainder);
static pj_bool_t on_connect_complete(pj_activesock_t *asock,
				     pj_status_t status);



static void turn_sock_on_destroy(void *comp);
static void destroy(pj_turn_sock *turn_sock);
static void timer_cb(pj_timer_heap_t *th, pj_timer_entry *e);


/* Init config */
PJ_DEF(void) pj_turn_sock_cfg_default(pj_turn_sock_cfg *cfg)
{
    pj_bzero(cfg, sizeof(*cfg));
    cfg->max_pkt_size = PJ_TURN_MAX_PKT_LEN;
    cfg->qos_type = PJ_QOS_TYPE_BEST_EFFORT;
    cfg->qos_ignore_error = PJ_TRUE;
}


/*
 * Create.
 */
PJ_DEF(pj_status_t) pj_turn_sock_create(pj_stun_config *cfg,
					int af,
					pj_turn_tp_type conn_type,
					const pj_turn_sock_cb *cb,
					const pj_turn_sock_cfg *setting,
					void *user_data,
					pj_turn_sock **p_turn_sock)
{
    pj_turn_sock *turn_sock;
    pj_turn_session_cb sess_cb;
    pj_turn_sock_cfg default_setting;
    pj_pool_t *pool;
    const char *name_tmpl;
    pj_status_t status;

    PJ_ASSERT_RETURN(cfg && p_turn_sock, PJ_EINVAL);
    PJ_ASSERT_RETURN(af==pj_AF_INET() || af==pj_AF_INET6(), PJ_EINVAL);
    PJ_ASSERT_RETURN(conn_type!=PJ_TURN_TP_TCP || PJ_HAS_TCP, PJ_EINVAL);

    if (!setting) {
	pj_turn_sock_cfg_default(&default_setting);
	setting = &default_setting;
    }

    switch (conn_type) {
    case PJ_TURN_TP_UDP:
	name_tmpl = "udprel%p";
	break;
    case PJ_TURN_TP_TCP:
	name_tmpl = "tcprel%p";
	break;
    default:
	PJ_ASSERT_RETURN(!"Invalid TURN conn_type", PJ_EINVAL);
	name_tmpl = "tcprel%p";
	break;
    }

    /* Create and init basic data structure */
    pool = pj_pool_create(cfg->pf, name_tmpl, PJNATH_POOL_LEN_TURN_SOCK,
			  PJNATH_POOL_INC_TURN_SOCK, NULL);
    turn_sock = PJ_POOL_ZALLOC_T(pool, pj_turn_sock);
    turn_sock->pool = pool;
    turn_sock->obj_name = pool->obj_name;
    turn_sock->user_data = user_data;
    turn_sock->af = af;
    turn_sock->conn_type = conn_type;

    /* Copy STUN config (this contains ioqueue, timer heap, etc.) */
    pj_memcpy(&turn_sock->cfg, cfg, sizeof(*cfg));

    /* Copy setting (QoS parameters etc */
    pj_memcpy(&turn_sock->setting, setting, sizeof(*setting));

    /* Set callback */
    if (cb) {
	pj_memcpy(&turn_sock->cb, cb, sizeof(*cb));
    }

    /* Session lock */
    if (setting && setting->grp_lock) {
	turn_sock->grp_lock = setting->grp_lock;
    } else {
	status = pj_grp_lock_create(pool, NULL, &turn_sock->grp_lock);
	if (status != PJ_SUCCESS) {
	    pj_pool_release(pool);
	    return status;
	}
    }

    pj_grp_lock_add_ref(turn_sock->grp_lock);
    pj_grp_lock_add_handler(turn_sock->grp_lock, pool, turn_sock,
                            &turn_sock_on_destroy);

    /* Init timer */
    pj_timer_entry_init(&turn_sock->timer, TIMER_NONE, turn_sock, &timer_cb);

    /* Init TURN session */
    pj_bzero(&sess_cb, sizeof(sess_cb));
    sess_cb.on_send_pkt = &turn_on_send_pkt;
    sess_cb.on_channel_bound = &turn_on_channel_bound;
    sess_cb.on_rx_data = &turn_on_rx_data;
    sess_cb.on_state = &turn_on_state;
    status = pj_turn_session_create(cfg, pool->obj_name, af, conn_type,
                                    turn_sock->grp_lock, &sess_cb, 0,
                                    turn_sock, &turn_sock->sess);
    if (status != PJ_SUCCESS) {
	destroy(turn_sock);
	return status;
    }

    /* Note: socket and ioqueue will be created later once the TURN server
     * has been resolved.
     */

    *p_turn_sock = turn_sock;
    return PJ_SUCCESS;
}

/*
 * Destroy.
 */
static void turn_sock_on_destroy(void *comp)
{
    pj_turn_sock *turn_sock = (pj_turn_sock*) comp;

    if (turn_sock->pool) {
	pj_pool_t *pool = turn_sock->pool;
	PJ_LOG(4,(turn_sock->obj_name, "TURN socket destroyed"));
	turn_sock->pool = NULL;
	pj_pool_release(pool);
    }
}

static void destroy(pj_turn_sock *turn_sock)
{
    PJ_LOG(4,(turn_sock->obj_name, "TURN socket destroy request, ref_cnt=%d",
	      pj_grp_lock_get_ref(turn_sock->grp_lock)));

    pj_grp_lock_acquire(turn_sock->grp_lock);
    if (turn_sock->is_destroying) {
	pj_grp_lock_release(turn_sock->grp_lock);
	return;
    }

    turn_sock->is_destroying = PJ_TRUE;
    if (turn_sock->sess)
	pj_turn_session_shutdown(turn_sock->sess);
    if (turn_sock->active_sock)
	pj_activesock_close(turn_sock->active_sock);
    pj_grp_lock_dec_ref(turn_sock->grp_lock);
    pj_grp_lock_release(turn_sock->grp_lock);
}

PJ_DEF(void) pj_turn_sock_destroy(pj_turn_sock *turn_sock)
{
    pj_grp_lock_acquire(turn_sock->grp_lock);
    if (turn_sock->is_destroying) {
	pj_grp_lock_release(turn_sock->grp_lock);
	return;
    }

    if (turn_sock->sess) {
	pj_turn_session_shutdown(turn_sock->sess);
	/* This will ultimately call our state callback, and when
	 * session state is DESTROYING we will schedule a timer to
	 * destroy ourselves.
	 */
    } else {
	destroy(turn_sock);
    }

    pj_grp_lock_release(turn_sock->grp_lock);
}


/* Timer callback */
static void timer_cb(pj_timer_heap_t *th, pj_timer_entry *e)
{
    pj_turn_sock *turn_sock = (pj_turn_sock*)e->user_data;
    int eid = e->id;

    PJ_UNUSED_ARG(th);

    e->id = TIMER_NONE;

    switch (eid) {
    case TIMER_DESTROY:
	destroy(turn_sock);
	break;
    default:
	pj_assert(!"Invalid timer id");
	break;
    }
}


/* Display error */
static void show_err(pj_turn_sock *turn_sock, const char *title,
		     pj_status_t status)
{
    PJ_PERROR(4,(turn_sock->obj_name, status, title));
}

/* On error, terminate session */
static void sess_fail(pj_turn_sock *turn_sock, const char *title,
		      pj_status_t status)
{
    show_err(turn_sock, title, status);
    if (turn_sock->sess) {
	pj_turn_session_destroy(turn_sock->sess, status);
    }
}

/*
 * Set user data.
 */
PJ_DEF(pj_status_t) pj_turn_sock_set_user_data( pj_turn_sock *turn_sock,
					       void *user_data)
{
    PJ_ASSERT_RETURN(turn_sock, PJ_EINVAL);
    turn_sock->user_data = user_data;
    return PJ_SUCCESS;
}

/*
 * Get user data.
 */
PJ_DEF(void*) pj_turn_sock_get_user_data(pj_turn_sock *turn_sock)
{
    PJ_ASSERT_RETURN(turn_sock, NULL);
    return turn_sock->user_data;
}

/**
 * Get info.
 */
PJ_DEF(pj_status_t) pj_turn_sock_get_info(pj_turn_sock *turn_sock,
					  pj_turn_session_info *info)
{
    PJ_ASSERT_RETURN(turn_sock && info, PJ_EINVAL);

    if (turn_sock->sess) {
	return pj_turn_session_get_info(turn_sock->sess, info);
    } else {
	pj_bzero(info, sizeof(*info));
	info->state = PJ_TURN_STATE_NULL;
	return PJ_SUCCESS;
    }
}

/**
 * Lock the TURN socket. Application may need to call this function to
 * synchronize access to other objects to avoid deadlock.
 */
PJ_DEF(pj_status_t) pj_turn_sock_lock(pj_turn_sock *turn_sock)
{
    return pj_grp_lock_acquire(turn_sock->grp_lock);
}

/**
 * Unlock the TURN socket.
 */
PJ_DEF(pj_status_t) pj_turn_sock_unlock(pj_turn_sock *turn_sock)
{
    return pj_grp_lock_release(turn_sock->grp_lock);
}

/*
 * Set STUN message logging for this TURN session. 
 */
PJ_DEF(void) pj_turn_sock_set_log( pj_turn_sock *turn_sock,
				   unsigned flags)
{
    pj_turn_session_set_log(turn_sock->sess, flags);
}

/*
 * Set software name
 */
PJ_DEF(pj_status_t) pj_turn_sock_set_software_name( pj_turn_sock *turn_sock,
						    const pj_str_t *sw)
{
    return pj_turn_session_set_software_name(turn_sock->sess, sw);
}

/*
 * Initialize.
 */
PJ_DEF(pj_status_t) pj_turn_sock_alloc(pj_turn_sock *turn_sock,
				       const pj_str_t *domain,
				       int default_port,
				       pj_dns_resolver *resolver,
				       const pj_stun_auth_cred *cred,
				       const pj_turn_alloc_param *param)
{
    pj_status_t status;

    PJ_ASSERT_RETURN(turn_sock && domain, PJ_EINVAL);
    PJ_ASSERT_RETURN(turn_sock->sess, PJ_EINVALIDOP);

    pj_grp_lock_acquire(turn_sock->grp_lock);

    /* Copy alloc param. We will call session_alloc() only after the 
     * server address has been resolved.
     */
    if (param) {
	pj_turn_alloc_param_copy(turn_sock->pool, &turn_sock->alloc_param, param);
    } else {
	pj_turn_alloc_param_default(&turn_sock->alloc_param);
    }

    /* Set credental */
    if (cred) {
	status = pj_turn_session_set_credential(turn_sock->sess, cred);
	if (status != PJ_SUCCESS) {
	    sess_fail(turn_sock, "Error setting credential", status);
	    pj_grp_lock_release(turn_sock->grp_lock);
	    return status;
	}
    }

    /* Resolve server */
    status = pj_turn_session_set_server(turn_sock->sess, domain, default_port,
					resolver);
    if (status != PJ_SUCCESS) {
	sess_fail(turn_sock, "Error setting TURN server", status);
	pj_grp_lock_release(turn_sock->grp_lock);
	return status;
    }

    /* Done for now. The next work will be done when session state moved
     * to RESOLVED state.
     */
    pj_grp_lock_release(turn_sock->grp_lock);
    return PJ_SUCCESS;
}

/*
 * Install permission
 */
PJ_DEF(pj_status_t) pj_turn_sock_set_perm( pj_turn_sock *turn_sock,
					   unsigned addr_cnt,
					   const pj_sockaddr addr[],
					   unsigned options)
{
    if (turn_sock->sess == NULL)
	return PJ_EINVALIDOP;

    return pj_turn_session_set_perm(turn_sock->sess, addr_cnt, addr, options);
}

/*
 * Send packet.
 */ 
PJ_DEF(pj_status_t) pj_turn_sock_sendto( pj_turn_sock *turn_sock,
					const pj_uint8_t *pkt,
					unsigned pkt_len,
					const pj_sockaddr_t *addr,
					unsigned addr_len)
{
    PJ_ASSERT_RETURN(turn_sock && addr && addr_len, PJ_EINVAL);

    if (turn_sock->sess == NULL)
	return PJ_EINVALIDOP;

    return pj_turn_session_sendto(turn_sock->sess, pkt, pkt_len, 
				  addr, addr_len);
}

/*
 * Bind a peer address to a channel number.
 */
PJ_DEF(pj_status_t) pj_turn_sock_bind_channel( pj_turn_sock *turn_sock,
					      const pj_sockaddr_t *peer,
					      unsigned addr_len)
{
    PJ_ASSERT_RETURN(turn_sock && peer && addr_len, PJ_EINVAL);
    PJ_ASSERT_RETURN(turn_sock->sess != NULL, PJ_EINVALIDOP);

    return pj_turn_session_bind_channel(turn_sock->sess, peer, addr_len);
}


/*
 * Notification when outgoing TCP socket has been connected.
 */
static pj_bool_t on_connect_complete(pj_activesock_t *asock,
				     pj_status_t status)
{
    pj_turn_sock *turn_sock;

    turn_sock = (pj_turn_sock*) pj_activesock_get_user_data(asock);
    if (!turn_sock)
        return PJ_FALSE;

    pj_grp_lock_acquire(turn_sock->grp_lock);

    /* TURN session may have already been destroyed here.
     * See ticket #1557 (http://trac.pjsip.org/repos/ticket/1557).
     */
    if (!turn_sock->sess) {
	sess_fail(turn_sock, "TURN session already destroyed", status);
	pj_grp_lock_release(turn_sock->grp_lock);
	return PJ_FALSE;
    }

    if (status != PJ_SUCCESS) {
	sess_fail(turn_sock, "TCP connect() error", status);
	pj_grp_lock_release(turn_sock->grp_lock);
	return PJ_FALSE;
    }

    if (turn_sock->conn_type != PJ_TURN_TP_UDP) {
	PJ_LOG(5,(turn_sock->obj_name, "TCP connected"));
    }

    /* Kick start pending read operation */
    status = pj_activesock_start_read(asock, turn_sock->pool, 
				      turn_sock->setting.max_pkt_size, 0);

    /* Init send_key */
    pj_ioqueue_op_key_init(&turn_sock->send_key, sizeof(turn_sock->send_key));

    /* Send Allocate request */
    status = pj_turn_session_alloc(turn_sock->sess, &turn_sock->alloc_param);
    if (status != PJ_SUCCESS) {
	sess_fail(turn_sock, "Error sending ALLOCATE", status);
	pj_grp_lock_release(turn_sock->grp_lock);
	return PJ_FALSE;
    }

    pj_grp_lock_release(turn_sock->grp_lock);
    return PJ_TRUE;
}

static pj_uint16_t GETVAL16H(const pj_uint8_t *buf, unsigned pos)
{
    return (pj_uint16_t) ((buf[pos + 0] << 8) | \
			  (buf[pos + 1] << 0));
}

/* Quick check to determine if there is enough packet to process in the
 * incoming buffer. Return the packet length, or zero if there's no packet.
 */
static unsigned has_packet(pj_turn_sock *turn_sock, const void *buf, pj_size_t bufsize)
{
    pj_bool_t is_stun;

    if (turn_sock->conn_type == PJ_TURN_TP_UDP)
	return bufsize;

    /* Quickly check if this is STUN message, by checking the first two bits and
     * size field which must be multiple of 4 bytes
     */
    is_stun = ((((pj_uint8_t*)buf)[0] & 0xC0) == 0) &&
	      ((GETVAL16H((const pj_uint8_t*)buf, 2) & 0x03)==0);

    if (is_stun) {
	pj_size_t msg_len = GETVAL16H((const pj_uint8_t*)buf, 2);
	return (msg_len+20 <= bufsize) ? msg_len+20 : 0;
    } else {
	/* This must be ChannelData. */
	pj_turn_channel_data cd;

	if (bufsize < 4)
	    return 0;

	/* Decode ChannelData packet */
	pj_memcpy(&cd, buf, sizeof(pj_turn_channel_data));
	cd.length = pj_ntohs(cd.length);

	if (bufsize >= cd.length+sizeof(cd)) 
	    return (cd.length+sizeof(cd)+3) & (~3);
	else
	    return 0;
    }
}

/*
 * Notification from ioqueue when incoming UDP packet is received.
 */
static pj_bool_t on_data_read(pj_activesock_t *asock,
			      void *data,
			      pj_size_t size,
			      pj_status_t status,
			      pj_size_t *remainder)
{
    pj_turn_sock *turn_sock;
    pj_bool_t ret = PJ_TRUE;

    turn_sock = (pj_turn_sock*) pj_activesock_get_user_data(asock);
    pj_grp_lock_acquire(turn_sock->grp_lock);

    if (status == PJ_SUCCESS && turn_sock->sess && !turn_sock->is_destroying) {
	/* Report incoming packet to TURN session, repeat while we have
	 * "packet" in the buffer (required for stream-oriented transports)
	 */
	unsigned pkt_len;

	//PJ_LOG(5,(turn_sock->pool->obj_name, 
	//	  "Incoming data, %lu bytes total buffer", size));

	while ((pkt_len=has_packet(turn_sock, data, size)) != 0) {
	    pj_size_t parsed_len;
	    //const pj_uint8_t *pkt = (const pj_uint8_t*)data;

	    //PJ_LOG(5,(turn_sock->pool->obj_name, 
	    //	      "Packet start: %02X %02X %02X %02X", 
	    //	      pkt[0], pkt[1], pkt[2], pkt[3]));

	    //PJ_LOG(5,(turn_sock->pool->obj_name, 
	    //	      "Processing %lu bytes packet of %lu bytes total buffer",
	    //	      pkt_len, size));

	    parsed_len = (unsigned)size;
	    pj_turn_session_on_rx_pkt(turn_sock->sess, data,  size, &parsed_len);

	    /* parsed_len may be zero if we have parsing error, so use our
	     * previous calculation to exhaust the bad packet.
	     */
	    if (parsed_len == 0)
		parsed_len = pkt_len;

	    if (parsed_len < (unsigned)size) {
		*remainder = size - parsed_len;
		pj_memmove(data, ((char*)data)+parsed_len, *remainder);
	    } else {
		*remainder = 0;
	    }
	    size = *remainder;

	    //PJ_LOG(5,(turn_sock->pool->obj_name, 
	    //	      "Buffer size now %lu bytes", size));
	}
    } else if (status != PJ_SUCCESS && 
	       turn_sock->conn_type != PJ_TURN_TP_UDP) 
    {
	sess_fail(turn_sock, "TCP connection closed", status);
	ret = PJ_FALSE;
	goto on_return;
    }

on_return:
    pj_grp_lock_release(turn_sock->grp_lock);

    return ret;
}


/*
 * Callback from TURN session to send outgoing packet.
 */
static pj_status_t turn_on_send_pkt(pj_turn_session *sess,
				    const pj_uint8_t *pkt,
				    unsigned pkt_len,
				    const pj_sockaddr_t *dst_addr,
				    unsigned dst_addr_len)
{
    pj_turn_sock *turn_sock = (pj_turn_sock*) 
			      pj_turn_session_get_user_data(sess);
    pj_ssize_t len = pkt_len;
    pj_status_t status;

    if (turn_sock == NULL || turn_sock->is_destroying) {
	/* We've been destroyed */
	// https://trac.pjsip.org/repos/ticket/1316
	//pj_assert(!"We should shutdown gracefully");
	return PJ_EINVALIDOP;
    }

    PJ_UNUSED_ARG(dst_addr);
    PJ_UNUSED_ARG(dst_addr_len);

    status = pj_activesock_send(turn_sock->active_sock, &turn_sock->send_key,
				pkt, &len, 0);
    if (status != PJ_SUCCESS && status != PJ_EPENDING) {
	show_err(turn_sock, "socket send()", status);
    }

    return status;
}


/*
 * Callback from TURN session when a channel is successfully bound.
 */
static void turn_on_channel_bound(pj_turn_session *sess,
				  const pj_sockaddr_t *peer_addr,
				  unsigned addr_len,
				  unsigned ch_num)
{
    PJ_UNUSED_ARG(sess);
    PJ_UNUSED_ARG(peer_addr);
    PJ_UNUSED_ARG(addr_len);
    PJ_UNUSED_ARG(ch_num);
}


/*
 * Callback from TURN session upon incoming data.
 */
static void turn_on_rx_data(pj_turn_session *sess,
			    void *pkt,
			    unsigned pkt_len,
			    const pj_sockaddr_t *peer_addr,
			    unsigned addr_len)
{
    pj_turn_sock *turn_sock = (pj_turn_sock*) 
			   pj_turn_session_get_user_data(sess);
    if (turn_sock == NULL || turn_sock->is_destroying) {
	/* We've been destroyed */
	return;
    }

    if (turn_sock->cb.on_rx_data) {
	(*turn_sock->cb.on_rx_data)(turn_sock, pkt, pkt_len, 
				  peer_addr, addr_len);
    }
}


/*
 * Callback from TURN session when state has changed
 */
static void turn_on_state(pj_turn_session *sess, 
			  pj_turn_state_t old_state,
			  pj_turn_state_t new_state)
{
    pj_turn_sock *turn_sock = (pj_turn_sock*) 
			   pj_turn_session_get_user_data(sess);
    pj_status_t status;

    if (turn_sock == NULL) {
	/* We've been destroyed */
	return;
    }

    /* Notify app first */
    if (turn_sock->cb.on_state) {
	(*turn_sock->cb.on_state)(turn_sock, old_state, new_state);
    }

    /* Make sure user hasn't destroyed us in the callback */
    if (turn_sock->sess && new_state == PJ_TURN_STATE_RESOLVED) {
	pj_turn_session_info info;
	pj_turn_session_get_info(turn_sock->sess, &info);
	new_state = info.state;
    }

    if (turn_sock->sess && new_state == PJ_TURN_STATE_RESOLVED) {
	/*
	 * Once server has been resolved, initiate outgoing TCP
	 * connection to the server.
	 */
	pj_turn_session_info info;
	char addrtxt[PJ_INET6_ADDRSTRLEN+8];
	int sock_type;
	pj_sock_t sock;
	pj_activesock_cfg asock_cfg;
	pj_activesock_cb asock_cb;
	pj_sockaddr bound_addr, *cfg_bind_addr;
	pj_uint16_t max_bind_retry;

	/* Close existing connection, if any. This happens when
	 * we're switching to alternate TURN server when either TCP
	 * connection or ALLOCATE request failed.
	 */
	if (turn_sock->active_sock) {
	    pj_activesock_close(turn_sock->active_sock);
	    turn_sock->active_sock = NULL;
	}

	/* Get server address from session info */
	pj_turn_session_get_info(sess, &info);

	if (turn_sock->conn_type == PJ_TURN_TP_UDP)
	    sock_type = pj_SOCK_DGRAM();
	else
	    sock_type = pj_SOCK_STREAM();

	/* Init socket */
	status = pj_sock_socket(turn_sock->af, sock_type, 0, &sock);
	if (status != PJ_SUCCESS) {
	    pj_turn_sock_destroy(turn_sock);
	    return;
	}

	/* Bind socket */
	cfg_bind_addr = &turn_sock->setting.bound_addr;
	max_bind_retry = MAX_BIND_RETRY;
	if (turn_sock->setting.port_range &&
	    turn_sock->setting.port_range < max_bind_retry)
	{
	    max_bind_retry = turn_sock->setting.port_range;
	}
	pj_sockaddr_init(turn_sock->af, &bound_addr, NULL, 0);
	if (cfg_bind_addr->addr.sa_family == pj_AF_INET() || 
	    cfg_bind_addr->addr.sa_family == pj_AF_INET6())
	{
	    pj_sockaddr_cp(&bound_addr, cfg_bind_addr);
	}
	status = pj_sock_bind_random(sock, &bound_addr,
				     turn_sock->setting.port_range,
				     max_bind_retry);
	if (status != PJ_SUCCESS) {
	    pj_turn_sock_destroy(turn_sock);
	    return;
	}

	/* Apply QoS, if specified */
	status = pj_sock_apply_qos2(sock, turn_sock->setting.qos_type,
				    &turn_sock->setting.qos_params, 
				    (turn_sock->setting.qos_ignore_error?2:1),
				    turn_sock->pool->obj_name, NULL);
	if (status != PJ_SUCCESS && !turn_sock->setting.qos_ignore_error) {
	    pj_turn_sock_destroy(turn_sock);
	    return;
	}

	/* Create active socket */
	pj_activesock_cfg_default(&asock_cfg);
	asock_cfg.grp_lock = turn_sock->grp_lock;

	pj_bzero(&asock_cb, sizeof(asock_cb));
	asock_cb.on_data_read = &on_data_read;
	asock_cb.on_connect_complete = &on_connect_complete;
	status = pj_activesock_create(turn_sock->pool, sock,
				      sock_type, &asock_cfg,
				      turn_sock->cfg.ioqueue, &asock_cb, 
				      turn_sock,
				      &turn_sock->active_sock);
	if (status != PJ_SUCCESS) {
	    pj_turn_sock_destroy(turn_sock);
	    return;
	}

	PJ_LOG(5,(turn_sock->pool->obj_name,
		  "Connecting to %s", 
		  pj_sockaddr_print(&info.server, addrtxt, 
				    sizeof(addrtxt), 3)));

	/* Initiate non-blocking connect */
#if PJ_HAS_TCP
	status=pj_activesock_start_connect(turn_sock->active_sock, 
					   turn_sock->pool,
					   &info.server, 
					   pj_sockaddr_get_len(&info.server));
	if (status == PJ_SUCCESS) {
	    on_connect_complete(turn_sock->active_sock, PJ_SUCCESS);
	} else if (status != PJ_EPENDING) {
	    pj_turn_sock_destroy(turn_sock);
	    return;
	}
#else
	on_connect_complete(turn_sock->active_sock, PJ_SUCCESS);
#endif

	/* Done for now. Subsequent work will be done in 
	 * on_connect_complete() callback.
	 */
    }

    if (new_state >= PJ_TURN_STATE_DESTROYING && turn_sock->sess) {
	pj_time_val delay = {0, 0};

	turn_sock->sess = NULL;
	pj_turn_session_set_user_data(sess, NULL);

	pj_timer_heap_cancel_if_active(turn_sock->cfg.timer_heap,
	                               &turn_sock->timer, 0);
	pj_timer_heap_schedule_w_grp_lock(turn_sock->cfg.timer_heap,
	                                  &turn_sock->timer,
	                                  &delay, TIMER_DESTROY,
	                                  turn_sock->grp_lock);
    }
}