/*
 * 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/ice_strans.h>
#include <pjnath/errno.h>
#include <pj/addr_resolv.h>
#include <pj/array.h>
#include <pj/assert.h>
#include <pj/ip_helper.h>
#include <pj/lock.h>
#include <pj/log.h>
#include <pj/os.h>
#include <pj/pool.h>
#include <pj/rand.h>
#include <pj/string.h>
#include <pj/compat/socket.h>

#define ENABLE_TRACE 0

#if defined(ENABLE_TRACE) && (ENABLE_TRACE != 0)
#  define TRACE_PKT(expr)           PJ_LOG(5,expr)
#else
#  define TRACE_PKT(expr)
#endif


/* Transport IDs */
enum tp_type
{
    TP_NONE,
    TP_STUN,
    TP_TURN
};


#define CREATE_TP_ID(type, idx)     (pj_uint8_t)((type << 6) | idx)
#define GET_TP_TYPE(transport_id)   ((transport_id & 0xC0) >> 6)
#define GET_TP_IDX(transport_id)    (transport_id & 0x3F)


/* Candidate's local preference values. This is mostly used to
 * specify preference among candidates with the same type. Since
 * we don't have the facility to specify that, we'll just set it
 * all to the same value.
 */
#if PJNATH_ICE_PRIO_STD
#   define SRFLX_PREF  65535
#   define HOST_PREF   65535
#   define RELAY_PREF  65535
#else
#   define SRFLX_PREF  ((1 << PJ_ICE_LOCAL_PREF_BITS) - 1)
#   define HOST_PREF   ((1 << PJ_ICE_LOCAL_PREF_BITS) - 1)
#   define RELAY_PREF  ((1 << PJ_ICE_LOCAL_PREF_BITS) - 1)
#endif


/* The candidate type preference when STUN candidate is used */
static pj_uint8_t srflx_pref_table[PJ_ICE_CAND_TYPE_MAX] =
{
#if PJNATH_ICE_PRIO_STD
    100,    /**< PJ_ICE_HOST_PREF           */
    110,    /**< PJ_ICE_SRFLX_PREF          */
    126,    /**< PJ_ICE_PRFLX_PREF          */
    0       /**< PJ_ICE_RELAYED_PREF    */
#else
    /* Keep it to 2 bits */
    1,  /**< PJ_ICE_HOST_PREF       */
    2,  /**< PJ_ICE_SRFLX_PREF      */
    3,  /**< PJ_ICE_PRFLX_PREF      */
    0   /**< PJ_ICE_RELAYED_PREF    */
#endif
};


/* ICE callbacks */
static void        on_valid_pair(pj_ice_sess *ice);
static void        on_ice_complete(pj_ice_sess *ice, pj_status_t status);
static pj_status_t ice_tx_pkt(pj_ice_sess *ice,
                              unsigned comp_id,
                              unsigned transport_id,
                              const void *pkt, pj_size_t size,
                              const pj_sockaddr_t *dst_addr,
                              unsigned dst_addr_len);
static void        ice_rx_data(pj_ice_sess *ice,
                               unsigned comp_id,
                               unsigned transport_id,
                               void *pkt, pj_size_t size,
                               const pj_sockaddr_t *src_addr,
                               unsigned src_addr_len);


/* STUN socket callbacks */
/* Notification when incoming packet has been received. */
static pj_bool_t stun_on_rx_data(pj_stun_sock *stun_sock,
                                 void *pkt,
                                 unsigned pkt_len,
                                 const pj_sockaddr_t *src_addr,
                                 unsigned addr_len);
/* Notifification when asynchronous send operation has completed. */
static pj_bool_t stun_on_data_sent(pj_stun_sock *stun_sock,
                                   pj_ioqueue_op_key_t *send_key,
                                   pj_ssize_t sent);
/* Notification when the status of the STUN transport has changed. */
static pj_bool_t stun_on_status(pj_stun_sock *stun_sock,
                                pj_stun_sock_op op,
                                pj_status_t status);


/* TURN callbacks */
static void turn_on_rx_data(pj_turn_sock *turn_sock,
                            void *pkt,
                            unsigned pkt_len,
                            const pj_sockaddr_t *peer_addr,
                            unsigned addr_len);
static pj_bool_t turn_on_data_sent(pj_turn_sock *turn_sock,
                                   pj_ssize_t sent);
static void turn_on_state(pj_turn_sock *turn_sock, pj_turn_state_t old_state,
                          pj_turn_state_t new_state);



/* Forward decls */
static pj_bool_t on_data_sent(pj_ice_strans *ice_st, pj_ssize_t sent);
static void check_pending_send(pj_ice_strans *ice_st);
static void ice_st_on_destroy(void *obj);
static void destroy_ice_st(pj_ice_strans *ice_st);
#define ice_st_perror(ice_st,msg,rc) pjnath_perror(ice_st->obj_name,msg,rc)
static void sess_init_update(pj_ice_strans *ice_st);

/**
 * This structure describes an ICE stream transport component. A component
 * in ICE stream transport typically corresponds to a single socket created
 * for this component, and bound to a specific transport address. This
 * component may have multiple alias addresses, for example one alias
 * address for each interfaces in multi-homed host, another for server
 * reflexive alias, and another for relayed alias. For each transport
 * address alias, an ICE stream transport candidate (#pj_ice_sess_cand) will
 * be created, and these candidates will eventually registered to the ICE
 * session.
 */
typedef struct pj_ice_strans_comp
{
    pj_ice_strans       *ice_st;        /**< ICE stream transport.      */
    unsigned             comp_id;       /**< Component ID.              */

    struct {
        pj_stun_sock    *sock;          /**< STUN transport.            */
    } stun[PJ_ICE_MAX_STUN];

    struct {
        pj_turn_sock    *sock;          /**< TURN relay transport.      */
        pj_bool_t        log_off;       /**< TURN loggin off?           */
        unsigned         err_cnt;       /**< TURN disconnected count.   */
    } turn[PJ_ICE_MAX_TURN];

    pj_bool_t            creating;      /**< Is creating the candidates?*/
    unsigned             cand_cnt;      /**< # of candidates/aliaes.    */
    pj_ice_sess_cand     cand_list[PJ_ICE_ST_MAX_CAND]; /**< Cand array */

    pj_bool_t            ipv4_mapped;   /**< Is IPv6 addr mapped to IPv4?*/
    pj_sockaddr          dst_addr;      /**< Destination address        */
    pj_sockaddr          synth_addr;    /**< Synthesized dest address   */
    unsigned             synth_addr_len;/**< Synthesized dest addr len  */

    unsigned             default_cand;  /**< Default candidate.         */

} pj_ice_strans_comp;


/* Pending send buffer */
typedef struct pending_send
{
    void               *buffer;
    unsigned            comp_id;
    pj_size_t           data_len;
    pj_sockaddr         dst_addr;
    int                 dst_addr_len;
} pending_send;

/**
 * This structure represents the ICE stream transport.
 */
struct pj_ice_strans
{
    char                    *obj_name;  /**< Log ID.                    */
    pj_pool_factory         *pf;        /**< Pool factory.              */
    pj_pool_t               *pool;      /**< Pool used by this object.  */
    void                    *user_data; /**< Application data.          */
    pj_ice_strans_cfg        cfg;       /**< Configuration.             */
    pj_ice_strans_cb         cb;        /**< Application callback.      */
    pj_grp_lock_t           *grp_lock;  /**< Group lock.                */

    pj_ice_strans_state      state;     /**< Session state.             */
    pj_ice_sess             *ice;       /**< ICE session.               */
    pj_ice_sess             *ice_prev;  /**< Previous ICE session.      */
    pj_grp_lock_handler      ice_prev_hndlr; /**< Handler of prev ICE   */
    pj_time_val              start_time;/**< Time when ICE was started  */

    unsigned                 comp_cnt;  /**< Number of components.      */
    pj_ice_strans_comp     **comp;      /**< Components array.          */

    pj_pool_t               *buf_pool;  /**< Pool for buffers.          */
    unsigned                 num_buf;   /**< Number of buffers.         */
    unsigned                 buf_idx;   /**< Index of buffer.           */
    unsigned                 empty_idx; /**< Index of empty buffer.     */
    unsigned                 buf_size;  /**< Buffer size.               */
    pending_send            *send_buf;  /**< Send buffers.              */
    pj_bool_t                is_pending;/**< Any pending send?          */

    pj_timer_entry           ka_timer;  /**< STUN keep-alive timer.     */

    pj_bool_t                destroy_req;/**< Destroy has been called?  */
    pj_bool_t                cb_called; /**< Init error callback called?*/
    pj_bool_t                call_send_cb;/**< Need to call send cb?    */

    pj_bool_t                rem_cand_end;/**< Trickle ICE: remote has
                                               signalled end of candidate? */
    pj_bool_t                loc_cand_end;/**< Trickle ICE: local has
                                               signalled end of candidate? */
};


/**
 * This structure describe user data for STUN/TURN sockets of the
 * ICE stream transport.
 */
typedef struct sock_user_data
{
    pj_ice_strans_comp      *comp;
    pj_uint8_t               transport_id;

} sock_user_data;


/* Validate configuration */
static pj_status_t pj_ice_strans_cfg_check_valid(const pj_ice_strans_cfg *cfg)
{
    pj_status_t status;

    status = pj_stun_config_check_valid(&cfg->stun_cfg);
    if (!status)
        return status;

    return PJ_SUCCESS;
}


/*
 * Initialize ICE transport configuration with default values.
 */
PJ_DEF(void) pj_ice_strans_cfg_default(pj_ice_strans_cfg *cfg)
{
    pj_bzero(cfg, sizeof(*cfg));

    cfg->af = pj_AF_INET();
    pj_stun_config_init(&cfg->stun_cfg, NULL, 0, NULL, NULL);
    pj_ice_strans_stun_cfg_default(&cfg->stun);
    pj_ice_strans_turn_cfg_default(&cfg->turn);
    pj_ice_sess_options_default(&cfg->opt);

    cfg->num_send_buf = 4;
}


/*
 * Initialize ICE STUN transport configuration with default values.
 */
PJ_DEF(void) pj_ice_strans_stun_cfg_default(pj_ice_strans_stun_cfg *cfg)
{
    pj_bzero(cfg, sizeof(*cfg));

    cfg->af = pj_AF_INET();
    cfg->port = PJ_STUN_PORT;
    cfg->max_host_cands = 64;
    cfg->ignore_stun_error = PJ_FALSE;
    pj_stun_sock_cfg_default(&cfg->cfg);
}


/*
 * Initialize ICE TURN transport configuration with default values.
 */
PJ_DEF(void) pj_ice_strans_turn_cfg_default(pj_ice_strans_turn_cfg *cfg)
{
    pj_bzero(cfg, sizeof(*cfg));

    cfg->af = pj_AF_INET();
    cfg->conn_type = PJ_TURN_TP_UDP;
    pj_turn_alloc_param_default(&cfg->alloc_param);
    pj_turn_sock_cfg_default(&cfg->cfg);
}


/*
 * Copy configuration.
 */
PJ_DEF(void) pj_ice_strans_cfg_copy( pj_pool_t *pool,
                                     pj_ice_strans_cfg *dst,
                                     const pj_ice_strans_cfg *src)
{
    unsigned i;

    pj_memcpy(dst, src, sizeof(*src));

    if (src->stun.server.slen)
        pj_strdup(pool, &dst->stun.server, &src->stun.server);

    for (i = 0; i < src->stun_tp_cnt; ++i) {
        if (src->stun_tp[i].server.slen)
            pj_strdup(pool, &dst->stun_tp[i].server,
                      &src->stun_tp[i].server);
    }

    if (src->turn.server.slen)
        pj_strdup(pool, &dst->turn.server, &src->turn.server);
    pj_stun_auth_cred_dup(pool, &dst->turn.auth_cred, &src->turn.auth_cred);

    for (i = 0; i < src->turn_tp_cnt; ++i) {
        if (src->turn_tp[i].server.slen)
            pj_strdup(pool, &dst->turn_tp[i].server,
                      &src->turn_tp[i].server);
        pj_stun_auth_cred_dup(pool, &dst->turn_tp[i].auth_cred,
                              &src->turn_tp[i].auth_cred);
    }
}


/*
 * Add or update TURN candidate.
 */
static pj_status_t add_update_turn(pj_ice_strans *ice_st,
                                   pj_ice_strans_comp *comp,
                                   unsigned idx,
                                   unsigned max_cand_cnt)
{
    pj_ice_sess_cand *cand = NULL;
    pj_ice_strans_turn_cfg *turn_cfg = &ice_st->cfg.turn_tp[idx];
    pj_turn_sock_cfg *sock_cfg  = &turn_cfg->cfg;
    unsigned comp_idx = comp->comp_id - 1;
    pj_turn_sock_cb turn_sock_cb;
    sock_user_data *data;
    unsigned i;
    pj_bool_t new_cand = PJ_FALSE;
    pj_uint8_t tp_id;
    pj_status_t status;

    /* Check if TURN transport is configured */
    if (turn_cfg->server.slen == 0)
        return PJ_SUCCESS;

    /* Find relayed candidate in the component */
    tp_id = CREATE_TP_ID(TP_TURN, idx);
    for (i=0; i<comp->cand_cnt; ++i) {
        if (comp->cand_list[i].transport_id == tp_id) {
            cand = &comp->cand_list[i];
            break;
        }
    }

    /* If candidate is found, invalidate it first */
    if (cand) {
        cand->status = PJ_EPENDING;

        /* Also if this component's default candidate is set to relay,
         * move it temporarily to something else.
         */
        if ((int)comp->default_cand == cand - comp->cand_list) {
            /* Init to something */
            comp->default_cand = 0;
            /* Use srflx candidate as the default, if any */
            for (i=0; i<comp->cand_cnt; ++i) {
                if (comp->cand_list[i].type == PJ_ICE_CAND_TYPE_SRFLX) {
                    comp->default_cand = i;
                    if (ice_st->cfg.af == pj_AF_UNSPEC() ||
                        comp->cand_list[i].base_addr.addr.sa_family ==
                        ice_st->cfg.af)
                    {
                        break;
                    }
                }
            }
        }
    }

    /* Init TURN socket */
    pj_bzero(&turn_sock_cb, sizeof(turn_sock_cb));
    turn_sock_cb.on_rx_data = &turn_on_rx_data;
    turn_sock_cb.on_data_sent = &turn_on_data_sent;
    turn_sock_cb.on_state = &turn_on_state;

    /* Override with component specific QoS settings, if any */
    if (ice_st->cfg.comp[comp_idx].qos_type)
        sock_cfg->qos_type = ice_st->cfg.comp[comp_idx].qos_type;
    if (ice_st->cfg.comp[comp_idx].qos_params.flags)
        pj_memcpy(&sock_cfg->qos_params,
                  &ice_st->cfg.comp[comp_idx].qos_params,
                  sizeof(sock_cfg->qos_params));

    /* Override with component specific socket buffer size settings, if any */
    if (ice_st->cfg.comp[comp_idx].so_rcvbuf_size > 0)
        sock_cfg->so_rcvbuf_size = ice_st->cfg.comp[comp_idx].so_rcvbuf_size;
    if (ice_st->cfg.comp[comp_idx].so_sndbuf_size > 0)
        sock_cfg->so_sndbuf_size = ice_st->cfg.comp[comp_idx].so_sndbuf_size;

    /* Add relayed candidate with pending status if there's no existing one */
    if (cand == NULL) {
        PJ_ASSERT_RETURN(max_cand_cnt > 0, PJ_ETOOSMALL);

        cand = &comp->cand_list[comp->cand_cnt];
        cand->type = PJ_ICE_CAND_TYPE_RELAYED;
        cand->status = PJ_EPENDING;
        cand->local_pref = (pj_uint16_t)(RELAY_PREF - idx);
        cand->transport_id = tp_id;
        cand->comp_id = (pj_uint8_t) comp->comp_id;
        new_cand = PJ_TRUE;
    }

    /* Allocate and initialize TURN socket data */
    data = PJ_POOL_ZALLOC_T(ice_st->pool, sock_user_data);
    data->comp = comp;
    data->transport_id = cand->transport_id;

    /* Create the TURN transport */
    status = pj_turn_sock_create(&ice_st->cfg.stun_cfg, turn_cfg->af,
                                 turn_cfg->conn_type,
                                 &turn_sock_cb, sock_cfg,
                                 data, &comp->turn[idx].sock);
    if (status != PJ_SUCCESS) {
        return status;
    }

    if (new_cand) {
        /* Commit the relayed candidate before pj_turn_sock_alloc(), as
         * otherwise there can be race condition, please check
         * https://github.com/pjsip/pjproject/pull/2525 for more info.
         */
        comp->cand_cnt++;
    }

    /* Add pending job */
    ///sess_add_ref(ice_st);

    /* Start allocation */
    status=pj_turn_sock_alloc(comp->turn[idx].sock,
                              &turn_cfg->server,
                              turn_cfg->port,
                              ice_st->cfg.resolver,
                              &turn_cfg->auth_cred,
                              &turn_cfg->alloc_param);
    if (status != PJ_SUCCESS) {
        ///sess_dec_ref(ice_st);
        cand->status = status;
        return status;
    }

    PJ_LOG(4,(ice_st->obj_name,
                  "Comp %d/%d: TURN relay candidate (tpid=%d) "
                  "waiting for allocation",
                  comp->comp_id, comp->cand_cnt-1, cand->transport_id));

    return PJ_SUCCESS;
}

static pj_bool_t ice_cand_equals(pj_ice_sess_cand *lcand, 
                                 pj_ice_sess_cand *rcand)
{
    if (lcand == NULL && rcand == NULL){
        return PJ_TRUE;
    }
    if (lcand == NULL || rcand == NULL){
        return PJ_FALSE;
    }
    
    if (lcand->type != rcand->type
        || lcand->status != rcand->status
        || lcand->comp_id != rcand->comp_id
        || lcand->transport_id != rcand->transport_id
        // local pref is no longer a constant, so it may be different
        //|| lcand->local_pref != rcand->local_pref
        || lcand->prio != rcand->prio
        || pj_sockaddr_cmp(&lcand->addr, &rcand->addr) != 0
        || pj_sockaddr_cmp(&lcand->base_addr, &rcand->base_addr) != 0)
    {
        return PJ_FALSE;
    }
    
    return PJ_TRUE;
}


static pj_status_t add_stun_and_host(pj_ice_strans *ice_st,
                                     pj_ice_strans_comp *comp,
                                     unsigned idx,
                                     unsigned max_cand_cnt)
{
    pj_ice_sess_cand *cand;
    pj_ice_strans_stun_cfg *stun_cfg = &ice_st->cfg.stun_tp[idx];
    pj_stun_sock_cfg *sock_cfg  = &stun_cfg->cfg;
    unsigned comp_idx = comp->comp_id - 1;
    pj_stun_sock_cb stun_sock_cb;
    sock_user_data *data;
    pj_status_t status;

    PJ_ASSERT_RETURN(max_cand_cnt > 0, PJ_ETOOSMALL);

    /* Check if STUN transport or host candidate is configured */
    if (stun_cfg->server.slen == 0 && stun_cfg->max_host_cands == 0)
        return PJ_SUCCESS;

    /* Initialize STUN socket callback */
    pj_bzero(&stun_sock_cb, sizeof(stun_sock_cb));
    stun_sock_cb.on_rx_data = &stun_on_rx_data;
    stun_sock_cb.on_status = &stun_on_status;
    stun_sock_cb.on_data_sent = &stun_on_data_sent;

    /* Override component specific QoS settings, if any */
    if (ice_st->cfg.comp[comp_idx].qos_type) {
        sock_cfg->qos_type = ice_st->cfg.comp[comp_idx].qos_type;
    }
    if (ice_st->cfg.comp[comp_idx].qos_params.flags) {
        pj_memcpy(&sock_cfg->qos_params,
                  &ice_st->cfg.comp[comp_idx].qos_params,
                  sizeof(sock_cfg->qos_params));
    }

    /* Override component specific socket buffer size settings, if any */
    if (ice_st->cfg.comp[comp_idx].so_rcvbuf_size > 0) {
        sock_cfg->so_rcvbuf_size = ice_st->cfg.comp[comp_idx].so_rcvbuf_size;
    }
    if (ice_st->cfg.comp[comp_idx].so_sndbuf_size > 0) {
        sock_cfg->so_sndbuf_size = ice_st->cfg.comp[comp_idx].so_sndbuf_size;
    }

    /* Prepare srflx candidate with pending status. */
    cand = &comp->cand_list[comp->cand_cnt];
    cand->type = PJ_ICE_CAND_TYPE_SRFLX;
    cand->status = PJ_EPENDING;
    cand->local_pref = (pj_uint16_t)(SRFLX_PREF - idx);
    cand->transport_id = CREATE_TP_ID(TP_STUN, idx);
    cand->comp_id = (pj_uint8_t) comp->comp_id;

    /* Allocate and initialize STUN socket data */
    data = PJ_POOL_ZALLOC_T(ice_st->pool, sock_user_data);
    data->comp = comp;
    data->transport_id = cand->transport_id;

    /* Create the STUN transport */
    status = pj_stun_sock_create(&ice_st->cfg.stun_cfg, NULL,
                                 stun_cfg->af, &stun_sock_cb,
                                 sock_cfg, data, &comp->stun[idx].sock);
    if (status != PJ_SUCCESS)
        return status;

    /* Start STUN Binding resolution and add srflx candidate only if server
     * is set. When any error occur during STUN Binding resolution, let's
     * just skip it and generate host candidates.
     */
    while (stun_cfg->server.slen) {
        pj_stun_sock_info stun_sock_info;

        /* Add pending job */
        ///sess_add_ref(ice_st);

        PJ_LOG(4,(ice_st->obj_name,
                  "Comp %d: srflx candidate (tpid=%d) starts "
                  "Binding discovery",
                  comp->comp_id, cand->transport_id));

        pj_log_push_indent();

        /* Start Binding resolution */
        status = pj_stun_sock_start(comp->stun[idx].sock, &stun_cfg->server,
                                    stun_cfg->port, ice_st->cfg.resolver);
        if (status != PJ_SUCCESS) {
            ///sess_dec_ref(ice_st);
            PJ_PERROR(5,(ice_st->obj_name, status,
                         "Comp %d: srflx candidate (tpid=%d) failed in "
                         "pj_stun_sock_start()",
                         comp->comp_id, cand->transport_id));
            pj_log_pop_indent();
            break;
        }

        /* Enumerate addresses */
        status = pj_stun_sock_get_info(comp->stun[idx].sock, &stun_sock_info);
        if (status != PJ_SUCCESS) {
            ///sess_dec_ref(ice_st);
            PJ_PERROR(5,(ice_st->obj_name, status,
                         "Comp %d: srflx candidate (tpid=%d) failed in "
                         "pj_stun_sock_get_info()",
                         comp->comp_id, cand->transport_id));
            pj_log_pop_indent();
            break;
        }

        /* Update and commit the srflx candidate. */
        pj_sockaddr_cp(&cand->base_addr, &stun_sock_info.aliases[0]);
        pj_sockaddr_cp(&cand->rel_addr, &cand->base_addr);
        pj_ice_calc_foundation(ice_st->pool, &cand->foundation,
                               cand->type, &cand->base_addr);
        comp->cand_cnt++;
        max_cand_cnt--;

        /* Set default candidate to srflx */
        if (comp->cand_list[comp->default_cand].type != PJ_ICE_CAND_TYPE_SRFLX
            || (ice_st->cfg.af != pj_AF_UNSPEC() &&
                comp->cand_list[comp->default_cand].base_addr.addr.sa_family
                != ice_st->cfg.af))
        {
            comp->default_cand = (unsigned)(cand - comp->cand_list);
        }

        pj_log_pop_indent();

        /* Not really a loop, just trying to avoid complex 'if' blocks */
        break;
    }

    /* Add local addresses to host candidates, unless max_host_cands
     * is set to zero.
     */
    if (stun_cfg->max_host_cands) {
        pj_stun_sock_info stun_sock_info;
        unsigned i, cand_cnt = 0;

        /* Enumerate addresses */
        status = pj_stun_sock_get_info(comp->stun[idx].sock, &stun_sock_info);
        if (status != PJ_SUCCESS) {
            PJ_PERROR(4,(ice_st->obj_name, status,
                         "Failed in querying STUN socket info"));
            return status;
        }

        for (i = 0; i < stun_sock_info.alias_cnt &&
                    cand_cnt < stun_cfg->max_host_cands; ++i)
        {
            unsigned j;
            pj_bool_t cand_duplicate = PJ_FALSE;
            char addrinfo[PJ_INET6_ADDRSTRLEN+10];
            const pj_sockaddr *addr = &stun_sock_info.aliases[i];

            if (max_cand_cnt==0) {
                PJ_LOG(4,(ice_st->obj_name, "Too many host candidates"));
                break;
            }

            /* Ignore loopback addresses if cfg->stun.loop_addr is unset */
            if (stun_cfg->loop_addr==PJ_FALSE) {
                if (stun_cfg->af == pj_AF_INET() && 
                    (pj_ntohl(addr->ipv4.sin_addr.s_addr)>>24)==127)
                {
                    continue;
                }
                else if (stun_cfg->af == pj_AF_INET6()) {
                    pj_in6_addr in6addr = {{{0}}};
                    in6addr.s6_addr[15] = 1;
                    if (pj_memcmp(&in6addr, &addr->ipv6.sin6_addr,
                                  sizeof(in6addr))==0)
                    {
                        continue;
                    }
                }
            }

            /* Ignore IPv6 link-local address, unless it is the default
             * address (first alias).
             */
            if (stun_cfg->af == pj_AF_INET6() && i != 0) {
                const pj_in6_addr *a = &addr->ipv6.sin6_addr;
                if (a->s6_addr[0] == 0xFE && (a->s6_addr[1] & 0xC0) == 0x80)
                    continue;
            }

            cand = &comp->cand_list[comp->cand_cnt];

            cand->type = PJ_ICE_CAND_TYPE_HOST;
            cand->status = PJ_SUCCESS;
            cand->local_pref = (pj_uint16_t)(HOST_PREF - cand_cnt);
            cand->transport_id = CREATE_TP_ID(TP_STUN, idx);
            cand->comp_id = (pj_uint8_t) comp->comp_id;
            pj_sockaddr_cp(&cand->addr, addr);
            pj_sockaddr_cp(&cand->base_addr, addr);
            pj_bzero(&cand->rel_addr, sizeof(cand->rel_addr));
            
            /* Check if not already in list */
            for (j=0; j<comp->cand_cnt; j++) {
                if (ice_cand_equals(cand, &comp->cand_list[j])) {
                    cand_duplicate = PJ_TRUE;
                    break;
                }
            }

            if (cand_duplicate) {
                PJ_LOG(4, (ice_st->obj_name,
                       "Comp %d: host candidate %s (tpid=%d) is a duplicate",
                       comp->comp_id, pj_sockaddr_print(&cand->addr, addrinfo,
                       sizeof(addrinfo), 3), cand->transport_id));

                pj_bzero(&cand->addr, sizeof(cand->addr));
                pj_bzero(&cand->base_addr, sizeof(cand->base_addr));
                continue;
            } else {
                comp->cand_cnt+=1;
                cand_cnt++;
                max_cand_cnt--;
            }
            
            pj_ice_calc_foundation(ice_st->pool, &cand->foundation,
                                   cand->type, &cand->base_addr);

            /* Set default candidate with the preferred default
             * address family
             */
            if (comp->ice_st->cfg.af != pj_AF_UNSPEC() &&
                addr->addr.sa_family == comp->ice_st->cfg.af &&
                comp->cand_list[comp->default_cand].base_addr.addr.sa_family !=
                ice_st->cfg.af)
            {
                comp->default_cand = (unsigned)(cand - comp->cand_list);
            }

            PJ_LOG(4,(ice_st->obj_name,
                      "Comp %d/%d: host candidate %s (tpid=%d) added",
                      comp->comp_id, comp->cand_cnt-1, 
                      pj_sockaddr_print(&cand->addr, addrinfo,
                                        sizeof(addrinfo), 3),
                                        cand->transport_id));
        }
    }

    return status;
}


/*
 * Create the component.
 */
static pj_status_t create_comp(pj_ice_strans *ice_st, unsigned comp_id)
{
    pj_ice_strans_comp *comp = NULL;
    unsigned i;
    pj_status_t status;

    /* Verify arguments */
    PJ_ASSERT_RETURN(ice_st && comp_id, PJ_EINVAL);

    /* Check that component ID present */
    PJ_ASSERT_RETURN(comp_id <= ice_st->comp_cnt, PJNATH_EICEINCOMPID);

    /* Create component */
    comp = PJ_POOL_ZALLOC_T(ice_st->pool, pj_ice_strans_comp);
    comp->ice_st = ice_st;
    comp->comp_id = comp_id;
    comp->creating = PJ_TRUE;

    ice_st->comp[comp_id-1] = comp;

    /* Initialize default candidate */
    comp->default_cand = 0;

    /* Create STUN transport if configured */
    for (i=0; i<ice_st->cfg.stun_tp_cnt; ++i) {
        unsigned max_cand_cnt = PJ_ICE_ST_MAX_CAND - comp->cand_cnt -
                                ice_st->cfg.turn_tp_cnt;

        status = PJ_ETOOSMALL;

        if ((max_cand_cnt > 0) && (max_cand_cnt <= PJ_ICE_ST_MAX_CAND))
            status = add_stun_and_host(ice_st, comp, i, max_cand_cnt);

        if (status != PJ_SUCCESS) {
            PJ_PERROR(3,(ice_st->obj_name, status,
                         "Failed creating STUN transport #%d for comp %d",
                         i, comp->comp_id));
            //return status;
        }
    }

    /* Create TURN relay if configured. */
    for (i=0; i<ice_st->cfg.turn_tp_cnt; ++i) {
        unsigned max_cand_cnt = PJ_ICE_ST_MAX_CAND - comp->cand_cnt;

        status = PJ_ETOOSMALL;

        if ((max_cand_cnt > 0) && (max_cand_cnt <= PJ_ICE_ST_MAX_CAND))
            status = add_update_turn(ice_st, comp, i, max_cand_cnt);

        if (status != PJ_SUCCESS) {
            PJ_PERROR(3,(ice_st->obj_name, status,
                         "Failed creating TURN transport #%d for comp %d",
                         i, comp->comp_id));

            //return status;
        } else if (max_cand_cnt > 0) {
            max_cand_cnt = PJ_ICE_ST_MAX_CAND - comp->cand_cnt;
        }
    }

    /* Done creating all the candidates */
    comp->creating = PJ_FALSE;

    /* It's possible that we end up without any candidates */
    if (comp->cand_cnt == 0) {
        PJ_LOG(4,(ice_st->obj_name,
                  "Error: no candidate is created due to settings"));
        return PJ_EINVAL;
    }

    return PJ_SUCCESS;
}

static pj_status_t alloc_send_buf(pj_ice_strans *ice_st, unsigned buf_size)
{
    if (buf_size > ice_st->buf_size) {
        unsigned i;
        
        if (ice_st->is_pending) {
            /* The current buffer is insufficient, but still currently used.*/
            return PJ_EBUSY;
        }

        pj_pool_safe_release(&ice_st->buf_pool);

        ice_st->buf_pool = pj_pool_create(ice_st->pf, "ice_buf",
                               (buf_size + sizeof(pending_send)) *
                               ice_st->num_buf, 512, NULL);
        if (!ice_st->buf_pool)
            return PJ_ENOMEM;

        ice_st->buf_size = buf_size;
        ice_st->send_buf = pj_pool_calloc(ice_st->buf_pool, ice_st->num_buf,
                                          sizeof(pending_send));
        for (i = 0; i < ice_st->num_buf; i++) {
            ice_st->send_buf[i].buffer = pj_pool_alloc(ice_st->buf_pool,
                                                       buf_size);
        }
        ice_st->buf_idx = ice_st->empty_idx = 0;
    }
    
    return PJ_SUCCESS;
}

/*
 * Create ICE stream transport
 */
PJ_DEF(pj_status_t) pj_ice_strans_create( const char *name,
                                          const pj_ice_strans_cfg *cfg,
                                          unsigned comp_cnt,
                                          void *user_data,
                                          const pj_ice_strans_cb *cb,
                                          pj_ice_strans **p_ice_st)
{
    pj_pool_t *pool;
    pj_ice_strans *ice_st;
    unsigned i;
    pj_status_t status;

    status = pj_ice_strans_cfg_check_valid(cfg);
    if (status != PJ_SUCCESS)
        return status;

    PJ_ASSERT_RETURN(comp_cnt && cb && p_ice_st &&
                     comp_cnt <= PJ_ICE_MAX_COMP , PJ_EINVAL);

    if (name == NULL)
        name = "ice%p";

    pool = pj_pool_create(cfg->stun_cfg.pf, name, PJNATH_POOL_LEN_ICE_STRANS,
                          PJNATH_POOL_INC_ICE_STRANS, NULL);
    ice_st = PJ_POOL_ZALLOC_T(pool, pj_ice_strans);
    ice_st->pool = pool;
    ice_st->pf = cfg->stun_cfg.pf;
    ice_st->obj_name = pool->obj_name;
    ice_st->user_data = user_data;

    PJ_LOG(4,(ice_st->obj_name,
              "Creating ICE stream transport with %d component(s)",
              comp_cnt));
    pj_log_push_indent();

    status = pj_grp_lock_create(pool, NULL, &ice_st->grp_lock);
    if (status != PJ_SUCCESS) {
        pj_pool_release(pool);
        pj_log_pop_indent();
        return status;
    }

    /* Allocate send buffer */
    ice_st->num_buf = cfg->num_send_buf;
    status = alloc_send_buf(ice_st, cfg->send_buf_size);
    if (status != PJ_SUCCESS) {
        destroy_ice_st(ice_st);
        pj_log_pop_indent();
        return status;
    }

    pj_grp_lock_add_ref(ice_st->grp_lock);
    pj_grp_lock_add_handler(ice_st->grp_lock, pool, ice_st,
                            &ice_st_on_destroy);

    pj_ice_strans_cfg_copy(pool, &ice_st->cfg, cfg);

    /* To maintain backward compatibility, check if old/deprecated setting is set
     * and the new setting is not, copy the value to the new setting.
     */
    if (cfg->stun_tp_cnt == 0 && 
        (cfg->stun.server.slen || cfg->stun.max_host_cands))
    {
        ice_st->cfg.stun_tp_cnt = 1;
        ice_st->cfg.stun_tp[0] = ice_st->cfg.stun;
    }
    if (cfg->turn_tp_cnt == 0 && cfg->turn.server.slen) {
        ice_st->cfg.turn_tp_cnt = 1;
        ice_st->cfg.turn_tp[0] = ice_st->cfg.turn;
    }

    for (i=0; i<ice_st->cfg.stun_tp_cnt; ++i)
        ice_st->cfg.stun_tp[i].cfg.grp_lock = ice_st->grp_lock;
    for (i=0; i<ice_st->cfg.turn_tp_cnt; ++i)
        ice_st->cfg.turn_tp[i].cfg.grp_lock = ice_st->grp_lock;
    pj_memcpy(&ice_st->cb, cb, sizeof(*cb));

    ice_st->comp_cnt = comp_cnt;
    ice_st->comp = (pj_ice_strans_comp**)
                   pj_pool_calloc(pool, comp_cnt, sizeof(pj_ice_strans_comp*));

    /* Move state to candidate gathering */
    ice_st->state = PJ_ICE_STRANS_STATE_INIT;

    /* Acquire initialization mutex to prevent callback to be
     * called before we finish initialization.
     */
    pj_grp_lock_acquire(ice_st->grp_lock);

    for (i=0; i<comp_cnt; ++i) {
        status = create_comp(ice_st, i+1);
        if (status != PJ_SUCCESS) {
            pj_grp_lock_release(ice_st->grp_lock);
            destroy_ice_st(ice_st);
            pj_log_pop_indent();
            return status;
        }
    }

    /* Done with initialization */
    pj_grp_lock_release(ice_st->grp_lock);

    PJ_LOG(4,(ice_st->obj_name, "ICE stream transport %p created", ice_st));

    *p_ice_st = ice_st;

    /* Check if all candidates are ready (this may call callback) */
    sess_init_update(ice_st);

    /* If ICE init done, notify app about end of candidate gathering via
     * on_new_candidate() callback.
     */
    if (ice_st->state==PJ_ICE_STRANS_STATE_READY &&
        ice_st->cb.on_new_candidate)
    {
        (*ice_st->cb.on_new_candidate)(ice_st, NULL, PJ_TRUE);
    }

    pj_log_pop_indent();

    return PJ_SUCCESS;
}

/* REALLY destroy ICE */
static void ice_st_on_destroy(void *obj)
{
    pj_ice_strans *ice_st = (pj_ice_strans*)obj;

    /* Destroy any previous ICE session */
    if (ice_st->ice_prev) {
        (*ice_st->ice_prev_hndlr)(ice_st->ice_prev);
        ice_st->ice_prev = NULL;
    }

    PJ_LOG(4,(ice_st->obj_name, "ICE stream transport %p destroyed", obj));

    /* Done */
    pj_pool_safe_release(&ice_st->buf_pool);
    pj_pool_safe_release(&ice_st->pool);
}

/* Destroy ICE */
static void destroy_ice_st(pj_ice_strans *ice_st)
{
    unsigned i;

    PJ_LOG(5,(ice_st->obj_name, "ICE stream transport %p destroy request..",
              ice_st));
    pj_log_push_indent();

    /* Reset callback and user data */
    pj_bzero(&ice_st->cb, sizeof(ice_st->cb));
    ice_st->user_data = NULL;

    pj_grp_lock_acquire(ice_st->grp_lock);

    if (ice_st->destroy_req) {
        pj_grp_lock_release(ice_st->grp_lock);
        return;
    }

    ice_st->destroy_req = PJ_TRUE;

    /* Destroy ICE if we have ICE */
    if (ice_st->ice) {
        pj_ice_sess *ice = ice_st->ice;
        ice_st->ice = NULL;
        pj_ice_sess_destroy(ice);
    }

    /* Destroy all components */
    for (i=0; i<ice_st->comp_cnt; ++i) {
        if (ice_st->comp[i]) {
            pj_ice_strans_comp *comp = ice_st->comp[i];
            unsigned j;
            for (j = 0; j < ice_st->cfg.stun_tp_cnt; ++j) {
                if (comp->stun[j].sock) {
                    pj_stun_sock_destroy(comp->stun[j].sock);
                    comp->stun[j].sock = NULL;
                }
            }
            for (j = 0; j < ice_st->cfg.turn_tp_cnt; ++j) {
                if (comp->turn[j].sock) {
                    pj_turn_sock_destroy(comp->turn[j].sock);
                    comp->turn[j].sock = NULL;
                }
            }
        }
    }

    pj_grp_lock_dec_ref(ice_st->grp_lock);
    pj_grp_lock_release(ice_st->grp_lock);

    pj_log_pop_indent();
}

/* Get ICE session state. */
PJ_DEF(pj_ice_strans_state) pj_ice_strans_get_state(pj_ice_strans *ice_st)
{
    return ice_st->state;
}

/* State string */
PJ_DEF(const char*) pj_ice_strans_state_name(pj_ice_strans_state state)
{
    const char *names[] = {
        "Null",
        "Candidate Gathering",
        "Candidate Gathering Complete",
        "Session Initialized",
        "Negotiation In Progress",
        "Negotiation Success",
        "Negotiation Failed"
    };

    PJ_ASSERT_RETURN(state <= PJ_ICE_STRANS_STATE_FAILED, "???");
    return names[state];
}

/* Notification about failure */
static void sess_fail(pj_ice_strans *ice_st, pj_ice_strans_op op,
                      const char *title, pj_status_t status)
{
    PJ_PERROR(4,(ice_st->obj_name, status, title));

    pj_log_push_indent();

    if (op==PJ_ICE_STRANS_OP_INIT && ice_st->cb_called) {
        pj_log_pop_indent();
        return;
    }

    ice_st->cb_called = PJ_TRUE;

    if (ice_st->cb.on_ice_complete)
        (*ice_st->cb.on_ice_complete)(ice_st, op, status);

    pj_log_pop_indent();
}

/* Update initialization status */
static void sess_init_update(pj_ice_strans *ice_st)
{
    unsigned i;
    pj_status_t status = PJ_EUNKNOWN;

    /* Ignore if ICE is destroying or init callback has been called */
    if (ice_st->destroy_req || ice_st->cb_called)
        return;

    /* Notify application when all candidates have been gathered */
    for (i=0; i<ice_st->comp_cnt; ++i) {
        unsigned j;
        pj_ice_strans_comp *comp = ice_st->comp[i];

        /* This function can be called when all components or candidates
         * have not been created.
         */
        if (!comp || comp->creating) {
            PJ_LOG(5, (ice_st->obj_name, "ICE init update: creating comp %d",
                       (comp?comp->comp_id:(i+1)) ));
            return;
        }

        status = PJ_EUNKNOWN;
        for (j=0; j<comp->cand_cnt; ++j) {
            pj_ice_sess_cand *cand = &comp->cand_list[j];

            if (cand->status == PJ_EPENDING) {
                PJ_LOG(5, (ice_st->obj_name, "ICE init update: "
                           "comp %d/%d[%s] is pending",
                           comp->comp_id, j,
                           pj_ice_get_cand_type_name(cand->type)));
                return;
            }
            
            if (status == PJ_EUNKNOWN) {
                status = cand->status;
            } else {
                /* We only need one successful candidate. */
                if (cand->status == PJ_SUCCESS)
                    status = PJ_SUCCESS;
            }
        }
        
        if (status != PJ_SUCCESS)
            break;
    }

    /* All candidates have been gathered or there's no successful
     * candidate for a component.
     */
    ice_st->cb_called = PJ_TRUE;
    ice_st->state = PJ_ICE_STRANS_STATE_READY;
    if (ice_st->cb.on_ice_complete)
        (*ice_st->cb.on_ice_complete)(ice_st, PJ_ICE_STRANS_OP_INIT,
                                      status);

    /* Tell ICE session that trickling is done */
    ice_st->loc_cand_end = PJ_TRUE;
    if (ice_st->ice && ice_st->ice->is_trickling && ice_st->rem_cand_end) {
        pj_ice_sess_update_check_list(ice_st->ice, NULL, NULL, 0, NULL,
                                      PJ_TRUE);
    }
}

/*
 * Destroy ICE stream transport.
 */
PJ_DEF(pj_status_t) pj_ice_strans_destroy(pj_ice_strans *ice_st)
{
    destroy_ice_st(ice_st);
    return PJ_SUCCESS;
}


/*
 * Get user data
 */
PJ_DEF(void*) pj_ice_strans_get_user_data(pj_ice_strans *ice_st)
{
    PJ_ASSERT_RETURN(ice_st, NULL);
    return ice_st->user_data;
}


/*
 * Get the value of various options of the ICE stream transport.
 */
PJ_DEF(pj_status_t) pj_ice_strans_get_options( pj_ice_strans *ice_st,
                                               pj_ice_sess_options *opt)
{
    PJ_ASSERT_RETURN(ice_st && opt, PJ_EINVAL);
    pj_memcpy(opt, &ice_st->cfg.opt, sizeof(*opt));
    return PJ_SUCCESS;
}

/*
 * Specify various options for this ICE stream transport.
 */
PJ_DEF(pj_status_t) pj_ice_strans_set_options(pj_ice_strans *ice_st,
                                              const pj_ice_sess_options *opt)
{
    PJ_ASSERT_RETURN(ice_st && opt, PJ_EINVAL);
    pj_memcpy(&ice_st->cfg.opt, opt, sizeof(*opt));
    if (ice_st->ice)
        pj_ice_sess_set_options(ice_st->ice, &ice_st->cfg.opt);
    return PJ_SUCCESS;
}

/*
 * Update number of components of the ICE stream transport.
 */
PJ_DEF(pj_status_t) pj_ice_strans_update_comp_cnt( pj_ice_strans *ice_st,
                                                   unsigned comp_cnt)
{
    unsigned i;

    PJ_ASSERT_RETURN(ice_st && comp_cnt < ice_st->comp_cnt, PJ_EINVAL);
    PJ_ASSERT_RETURN(ice_st->ice == NULL, PJ_EINVALIDOP);

    pj_grp_lock_acquire(ice_st->grp_lock);

    for (i=comp_cnt; i<ice_st->comp_cnt; ++i) {
        pj_ice_strans_comp *comp = ice_st->comp[i];
        unsigned j;

        /* Destroy the component */
        for (j = 0; j < ice_st->cfg.stun_tp_cnt; ++j) {
            if (comp->stun[j].sock) {
                pj_stun_sock_destroy(comp->stun[j].sock);
                comp->stun[j].sock = NULL;
            }
        }
        for (j = 0; j < ice_st->cfg.turn_tp_cnt; ++j) {
            if (comp->turn[j].sock) {
                pj_turn_sock_destroy(comp->turn[j].sock);
                comp->turn[j].sock = NULL;
            }
        }
        comp->cand_cnt = 0;
        ice_st->comp[i] = NULL;
    }
    ice_st->comp_cnt = comp_cnt;
    pj_grp_lock_release(ice_st->grp_lock);

    PJ_LOG(4,(ice_st->obj_name,
              "Updated ICE stream transport components number to %d",
              comp_cnt));

    return PJ_SUCCESS;
}

/**
 * Get the group lock for this ICE stream transport.
 */
PJ_DEF(pj_grp_lock_t *) pj_ice_strans_get_grp_lock(pj_ice_strans *ice_st)
{
    PJ_ASSERT_RETURN(ice_st, NULL);
    return ice_st->grp_lock;
}

/*
 * Create ICE!
 */
PJ_DEF(pj_status_t) pj_ice_strans_init_ice(pj_ice_strans *ice_st,
                                           pj_ice_sess_role role,
                                           const pj_str_t *local_ufrag,
                                           const pj_str_t *local_passwd)
{
    pj_status_t status;
    unsigned i;
    pj_ice_sess_cb ice_cb;
    //const pj_uint8_t srflx_prio[4] = { 100, 126, 110, 0 };

    /* Check arguments */
    PJ_ASSERT_RETURN(ice_st, PJ_EINVAL);
    /* Must not have ICE */
    PJ_ASSERT_RETURN(ice_st->ice == NULL, PJ_EINVALIDOP);
    /* Components must have been created */
    PJ_ASSERT_RETURN(ice_st->comp[0] != NULL, PJ_EINVALIDOP);

    /* Init callback */
    pj_bzero(&ice_cb, sizeof(ice_cb));
    ice_cb.on_valid_pair   = &on_valid_pair;
    ice_cb.on_ice_complete = &on_ice_complete;
    ice_cb.on_rx_data = &ice_rx_data;
    ice_cb.on_tx_pkt = &ice_tx_pkt;

    /* Release the pool of previous ICE session to avoid memory bloat,
     * as otherwise it will only be released after ICE strans is destroyed
     * (due to group lock).
     */
    if (ice_st->ice_prev) {
        (*ice_st->ice_prev_hndlr)(ice_st->ice_prev);
        ice_st->ice_prev = NULL;
    }

    /* Create! */
    status = pj_ice_sess_create(&ice_st->cfg.stun_cfg, ice_st->obj_name, role,
                                ice_st->comp_cnt, &ice_cb,
                                local_ufrag, local_passwd,
                                ice_st->grp_lock,
                                &ice_st->ice);
    if (status != PJ_SUCCESS)
        return status;

    /* Associate user data */
    ice_st->ice->user_data = (void*)ice_st;

    /* Set options */
    pj_ice_sess_set_options(ice_st->ice, &ice_st->cfg.opt);

    /* If default candidate for components are SRFLX one, upload a custom
     * type priority to ICE session so that SRFLX candidates will get
     * checked first.
     */
    if (ice_st->comp[0]->cand_list[ice_st->comp[0]->default_cand].type
            == PJ_ICE_CAND_TYPE_SRFLX)
    {
        pj_ice_sess_set_prefs(ice_st->ice, srflx_pref_table);
    }

    /* Add components/candidates */
    for (i=0; i<ice_st->comp_cnt; ++i) {
        unsigned j;
        pj_ice_strans_comp *comp = ice_st->comp[i];

        /* Re-enable logging for Send/Data indications */
        if (ice_st->cfg.turn_tp_cnt) {
            PJ_LOG(5,(ice_st->obj_name,
                      "Enabling STUN Indication logging for "
                      "component %d", i+1));
        }
        for (j = 0; j < ice_st->cfg.turn_tp_cnt; ++j) {
            if (comp->turn[j].sock) {
                pj_turn_sock_set_log(comp->turn[j].sock, 0xFFFF);
                comp->turn[j].log_off = PJ_FALSE;
            }
        }

        for (j=0; j<comp->cand_cnt; ++j) {
            pj_ice_sess_cand *cand = &comp->cand_list[j];
            unsigned ice_cand_id;

            /* Skip if candidate is not ready */
            if (cand->status != PJ_SUCCESS) {
                PJ_LOG(5,(ice_st->obj_name,
                          "Candidate %d of comp %d is not added (pending)",
                          j, i));
                continue;
            }

            /* Must have address */
            pj_assert(pj_sockaddr_has_addr(&cand->addr));

            /* Skip if we are mapped to IPv4 address and this candidate
             * is not IPv4.
             */
            if (comp->ipv4_mapped &&
                cand->addr.addr.sa_family != pj_AF_INET())
            {
                continue;
            }

            /* Add the candidate */
            status = pj_ice_sess_add_cand(ice_st->ice, comp->comp_id,
                                          cand->transport_id, cand->type,
                                          cand->local_pref,
                                          &cand->foundation, &cand->addr,
                                          &cand->base_addr,  &cand->rel_addr,
                                          pj_sockaddr_get_len(&cand->addr),
                                          (unsigned*)&ice_cand_id);
            if (status != PJ_SUCCESS)
                goto on_error;
        }
    }

    /* ICE session is ready for negotiation */
    ice_st->state = PJ_ICE_STRANS_STATE_SESS_READY;

    return PJ_SUCCESS;

on_error:
    pj_ice_strans_stop_ice(ice_st);
    return status;
}

/*
 * Check if the ICE stream transport has the ICE session created.
 */
PJ_DEF(pj_bool_t) pj_ice_strans_has_sess(pj_ice_strans *ice_st)
{
    PJ_ASSERT_RETURN(ice_st, PJ_FALSE);
    return ice_st->ice != NULL;
}

/*
 * Check if ICE negotiation is still running.
 */
PJ_DEF(pj_bool_t) pj_ice_strans_sess_is_running(pj_ice_strans *ice_st)
{
    // Trickle ICE can start ICE before remote candidate list is received
    return ice_st && ice_st->ice && /* ice_st->ice->rcand_cnt && */
           ice_st->ice->clist.state == PJ_ICE_SESS_CHECKLIST_ST_RUNNING &&
           !pj_ice_strans_sess_is_complete(ice_st);
}


/*
 * Check if ICE negotiation has completed.
 */
PJ_DEF(pj_bool_t) pj_ice_strans_sess_is_complete(pj_ice_strans *ice_st)
{
    return ice_st && ice_st->ice && ice_st->ice->is_complete;
}


/*
 * Get the current/running component count.
 */
PJ_DEF(unsigned) pj_ice_strans_get_running_comp_cnt(pj_ice_strans *ice_st)
{
    PJ_ASSERT_RETURN(ice_st, PJ_EINVAL);

    if (ice_st->ice && ice_st->ice->rcand_cnt) {
        return ice_st->ice->comp_cnt;
    } else {
        return ice_st->comp_cnt;
    }
}


/*
 * Get the ICE username fragment and password of the ICE session.
 */
PJ_DEF(pj_status_t) pj_ice_strans_get_ufrag_pwd( pj_ice_strans *ice_st,
                                                 pj_str_t *loc_ufrag,
                                                 pj_str_t *loc_pwd,
                                                 pj_str_t *rem_ufrag,
                                                 pj_str_t *rem_pwd)
{
    PJ_ASSERT_RETURN(ice_st && ice_st->ice, PJ_EINVALIDOP);

    if (loc_ufrag) *loc_ufrag = ice_st->ice->rx_ufrag;
    if (loc_pwd) *loc_pwd = ice_st->ice->rx_pass;

    if (rem_ufrag || rem_pwd) {
        // In trickle ICE, remote may send initial SDP with empty candidates
        //PJ_ASSERT_RETURN(ice_st->ice->rcand_cnt != 0, PJ_EINVALIDOP);
        if (rem_ufrag) *rem_ufrag = ice_st->ice->tx_ufrag;
        if (rem_pwd) *rem_pwd = ice_st->ice->tx_pass;
    }

    return PJ_SUCCESS;
}

/*
 * Get number of candidates
 */
PJ_DEF(unsigned) pj_ice_strans_get_cands_count(pj_ice_strans *ice_st,
                                               unsigned comp_id)
{
    unsigned i, cnt;

    PJ_ASSERT_RETURN(ice_st && ice_st->ice && comp_id &&
                     comp_id <= ice_st->comp_cnt, 0);

    cnt = 0;
    for (i=0; i<ice_st->ice->lcand_cnt; ++i) {
        if (ice_st->ice->lcand[i].comp_id != comp_id)
            continue;
        ++cnt;
    }

    return cnt;
}

/*
 * Enum candidates
 */
PJ_DEF(pj_status_t) pj_ice_strans_enum_cands(pj_ice_strans *ice_st,
                                             unsigned comp_id,
                                             unsigned *count,
                                             pj_ice_sess_cand cand[])
{
    unsigned i, cnt;

    PJ_ASSERT_RETURN(ice_st && ice_st->ice && comp_id &&
                     comp_id <= ice_st->comp_cnt && count && cand, PJ_EINVAL);

    cnt = 0;
    for (i=0; i<ice_st->ice->lcand_cnt && cnt<*count; ++i) {
        if (ice_st->ice->lcand[i].comp_id != comp_id)
            continue;
        pj_memcpy(&cand[cnt], &ice_st->ice->lcand[i],
                  sizeof(pj_ice_sess_cand));
        ++cnt;
    }

    *count = cnt;
    return PJ_SUCCESS;
}

/*
 * Get default candidate.
 */
PJ_DEF(pj_status_t) pj_ice_strans_get_def_cand( pj_ice_strans *ice_st,
                                                unsigned comp_id,
                                                pj_ice_sess_cand *cand)
{
    const pj_ice_sess_check *valid_pair;

    PJ_ASSERT_RETURN(ice_st && comp_id && comp_id <= ice_st->comp_cnt &&
                      cand, PJ_EINVAL);

    valid_pair = pj_ice_strans_get_valid_pair(ice_st, comp_id);
    if (valid_pair) {
        pj_memcpy(cand, valid_pair->lcand, sizeof(pj_ice_sess_cand));
    } else {
        pj_ice_strans_comp *comp = ice_st->comp[comp_id - 1];
        pj_assert(comp->default_cand<comp->cand_cnt);
        pj_memcpy(cand, &comp->cand_list[comp->default_cand],
                  sizeof(pj_ice_sess_cand));
    }
    return PJ_SUCCESS;
}

/*
 * Get the current ICE role.
 */
PJ_DEF(pj_ice_sess_role) pj_ice_strans_get_role(pj_ice_strans *ice_st)
{
    PJ_ASSERT_RETURN(ice_st && ice_st->ice, PJ_ICE_SESS_ROLE_UNKNOWN);
    return ice_st->ice->role;
}

/*
 * Change session role.
 */
PJ_DEF(pj_status_t) pj_ice_strans_change_role( pj_ice_strans *ice_st,
                                               pj_ice_sess_role new_role)
{
    PJ_ASSERT_RETURN(ice_st && ice_st->ice, PJ_EINVALIDOP);
    return pj_ice_sess_change_role(ice_st->ice, new_role);
}

static pj_status_t setup_turn_perm( pj_ice_strans *ice_st)
{
    unsigned n;
    pj_status_t status;

    for (n = 0; n < ice_st->cfg.turn_tp_cnt; ++n) {
        unsigned i, comp_cnt;

        comp_cnt = pj_ice_strans_get_running_comp_cnt(ice_st);
        for (i=0; i<comp_cnt; ++i) {
            pj_ice_strans_comp *comp = ice_st->comp[i];
            pj_turn_session_info info;
            pj_sockaddr addrs[PJ_ICE_ST_MAX_CAND];
            unsigned j, count=0;
            unsigned rem_cand_cnt;
            const pj_ice_sess_cand *rem_cand;

            if (!comp->turn[n].sock)
                continue;

            status = pj_turn_sock_get_info(comp->turn[n].sock, &info);
            if (status != PJ_SUCCESS || info.state != PJ_TURN_STATE_READY)
                continue;

            /* Gather remote addresses for this component */
            rem_cand_cnt = ice_st->ice->rcand_cnt;
            rem_cand = ice_st->ice->rcand;
            if (status != PJ_SUCCESS)
                continue;

            for (j=0; j<rem_cand_cnt && count<PJ_ARRAY_SIZE(addrs); ++j) {
                if (rem_cand[j].comp_id==i+1 &&
                    rem_cand[j].addr.addr.sa_family==
                    ice_st->cfg.turn_tp[n].af)
                {
                    pj_sockaddr_cp(&addrs[count++], &rem_cand[j].addr);
                }
            }

            if (count && !comp->turn[n].err_cnt && comp->turn[n].sock) {
                status = pj_turn_sock_set_perm(
                                    comp->turn[n].sock, count,
                                    addrs, PJ_ICE_ST_USE_TURN_PERMANENT_PERM);
                if (status != PJ_SUCCESS) {
                    pj_ice_strans_stop_ice(ice_st);
                    return status;
                }
            }
        }
    }

    return PJ_SUCCESS;
}

/*
 * Start ICE processing !
 */
PJ_DEF(pj_status_t) pj_ice_strans_start_ice( pj_ice_strans *ice_st,
                                             const pj_str_t *rem_ufrag,
                                             const pj_str_t *rem_passwd,
                                             unsigned rem_cand_cnt,
                                             const pj_ice_sess_cand rem_cand[])
{
    pj_status_t status;

    PJ_ASSERT_RETURN(ice_st, PJ_EINVAL);
    PJ_ASSERT_RETURN(ice_st->ice, PJ_EINVALIDOP);

    /* Mark start time */
    pj_gettimeofday(&ice_st->start_time);

    /* Update check list */
    status = pj_ice_strans_update_check_list(ice_st, rem_ufrag, rem_passwd,
                                             rem_cand_cnt, rem_cand,
                                             !ice_st->ice->is_trickling);
    if (status != PJ_SUCCESS)
        return status;

    /* If we have TURN candidate, now is the time to create the permissions */
    status = setup_turn_perm(ice_st);
    if (status != PJ_SUCCESS) {
        pj_ice_strans_stop_ice(ice_st);
        return status;
    }

    /* Start ICE negotiation! */
    status = pj_ice_sess_start_check(ice_st->ice);
    if (status != PJ_SUCCESS) {
        pj_ice_strans_stop_ice(ice_st);
        return status;
    }

    ice_st->state = PJ_ICE_STRANS_STATE_NEGO;
    return status;
}


/*
 * Update check list after discovering and conveying new local ICE candidate,
 * or receiving update of remote ICE candidates in trickle ICE.
 */
PJ_DEF(pj_status_t) pj_ice_strans_update_check_list(
                                         pj_ice_strans *ice_st,
                                         const pj_str_t *rem_ufrag,
                                         const pj_str_t *rem_passwd,
                                         unsigned rem_cand_cnt,
                                         const pj_ice_sess_cand rem_cand[],
                                         pj_bool_t rcand_end)
{
    pj_bool_t checklist_created;
    pj_status_t status;

    PJ_ASSERT_RETURN(ice_st && ((rem_cand_cnt==0) ||
                                (rem_ufrag && rem_passwd && rem_cand)),
                     PJ_EINVAL);
    PJ_ASSERT_RETURN(ice_st->ice, PJ_EINVALIDOP);

    pj_grp_lock_acquire(ice_st->grp_lock);

    checklist_created = ice_st->ice->tx_ufrag.slen > 0;

    /* Create checklist (if not yet) */
    if (rem_ufrag && !checklist_created) {
        status = pj_ice_sess_create_check_list(ice_st->ice, rem_ufrag,
                                               rem_passwd, rem_cand_cnt,
                                               rem_cand);
        if (status != PJ_SUCCESS) {
            PJ_PERROR(4,(ice_st->obj_name, status,
                         "Failed setting up remote ufrag"));
            pj_grp_lock_release(ice_st->grp_lock);
            return status;
        }
    }

    /* Update checklist for trickling ICE */
    if (ice_st->ice->is_trickling) {
        if (rcand_end && !ice_st->rem_cand_end)
            ice_st->rem_cand_end = PJ_TRUE;

        status = pj_ice_sess_update_check_list(
                            ice_st->ice, rem_ufrag, rem_passwd,
                            (checklist_created? rem_cand_cnt:0), rem_cand,
                            (ice_st->rem_cand_end && ice_st->loc_cand_end));
        if (status != PJ_SUCCESS) {
            PJ_PERROR(4,(ice_st->obj_name, status,
                         "Failed updating checklist"));
            pj_grp_lock_release(ice_st->grp_lock);
            return status;
        }
    }

    /* Update TURN permissions if periodic check has been started. */
    if (pj_ice_strans_sess_is_running(ice_st)) {
        status = setup_turn_perm(ice_st);
        if (status != PJ_SUCCESS) {
            PJ_PERROR(4,(ice_st->obj_name, status,
                         "Failed setting up TURN permission"));
            pj_grp_lock_release(ice_st->grp_lock);
            return status;
        }
    }

    pj_grp_lock_release(ice_st->grp_lock);

    return PJ_SUCCESS;
}


/*
 * Get valid pair.
 */
PJ_DEF(const pj_ice_sess_check*)
pj_ice_strans_get_valid_pair(const pj_ice_strans *ice_st,
                             unsigned comp_id)
{
    PJ_ASSERT_RETURN(ice_st && comp_id && comp_id <= ice_st->comp_cnt,
                     NULL);

    if (ice_st->ice == NULL)
        return NULL;

    return ice_st->ice->comp[comp_id-1].valid_check;
}

/*
 * Stop ICE!
 */
PJ_DEF(pj_status_t) pj_ice_strans_stop_ice(pj_ice_strans *ice_st)
{
    PJ_ASSERT_RETURN(ice_st, PJ_EINVAL);
    
    /* Protect with group lock, since this may cause race condition with
     * pj_ice_strans_sendto2().
     * See ticket #1877.
     */
    pj_grp_lock_acquire(ice_st->grp_lock);

    if (ice_st->ice) {
        ice_st->ice_prev = ice_st->ice;
        ice_st->ice = NULL;
        pj_ice_sess_detach_grp_lock(ice_st->ice_prev, &ice_st->ice_prev_hndlr);
        pj_ice_sess_destroy(ice_st->ice_prev);
    }

    ice_st->state = PJ_ICE_STRANS_STATE_INIT;

    pj_grp_lock_release(ice_st->grp_lock);

    return PJ_SUCCESS;
}

static pj_status_t use_buffer( pj_ice_strans *ice_st,
                               unsigned comp_id,
                               const void *data,
                               pj_size_t data_len,
                               const pj_sockaddr_t *dst_addr,
                               int dst_addr_len,
                               void **buffer )
{
    unsigned idx;
    pj_status_t status;

    /* Allocate send buffer, if necessary. */
    status = alloc_send_buf(ice_st, (unsigned)data_len);
    if (status != PJ_SUCCESS)
        return status;
    
    if (ice_st->is_pending && ice_st->empty_idx == ice_st->buf_idx) {
        /* We don't use buffer or there's no more empty buffer. */
        return PJ_EBUSY;
    }

    idx = ice_st->empty_idx;
    ice_st->empty_idx = (ice_st->empty_idx + 1) % ice_st->num_buf;
    ice_st->send_buf[idx].comp_id = comp_id;
    ice_st->send_buf[idx].data_len = data_len;
    pj_assert(ice_st->buf_size >= data_len);
    pj_memcpy(ice_st->send_buf[idx].buffer, data, data_len);
    pj_sockaddr_cp(&ice_st->send_buf[idx].dst_addr, dst_addr);
    ice_st->send_buf[idx].dst_addr_len = dst_addr_len;
    *buffer = ice_st->send_buf[idx].buffer;
    
    if (ice_st->is_pending) {
        /* We'll continue later since there's still a pending send. */
        return PJ_EPENDING;
    }
    
    ice_st->is_pending = PJ_TRUE;
    ice_st->buf_idx = idx;

    return PJ_SUCCESS;
}

/*
 * Application wants to send outgoing packet.
 */
static pj_status_t send_data(pj_ice_strans *ice_st,
                             unsigned comp_id,
                             const void *data,
                             pj_size_t data_len,
                             const pj_sockaddr_t *dst_addr,
                             int dst_addr_len,
                             pj_bool_t use_buf,
                             pj_bool_t call_cb)
{
    pj_ice_strans_comp *comp;
    pj_ice_sess_cand *def_cand;
    void *buf = (void *)data;
    pj_status_t status;

    PJ_ASSERT_RETURN(ice_st && comp_id && comp_id <= ice_st->comp_cnt &&
                     dst_addr && dst_addr_len, PJ_EINVAL);

    comp = ice_st->comp[comp_id-1];

    /* Check that default candidate for the component exists */
    if (comp->default_cand >= comp->cand_cnt) {
        status = PJ_EINVALIDOP;
        if (call_cb)
            on_data_sent(ice_st, -status);
        return status;
    }

    /* Protect with group lock, since this may cause race condition with
     * pj_ice_strans_stop_ice().
     * See ticket #1877.
     */
    pj_grp_lock_acquire(ice_st->grp_lock);

    if (use_buf && ice_st->num_buf > 0) {
        status = use_buffer(ice_st, comp_id, data, data_len, dst_addr,
                            dst_addr_len, &buf);

        if (status == PJ_EPENDING || status != PJ_SUCCESS) {
            pj_grp_lock_release(ice_st->grp_lock);
            return status;
        }
    }

    /* If ICE is available, send data with ICE. If ICE nego is not completed
     * yet, ICE will try to send using any valid candidate pair. For any
     * failure, it will fallback to sending with the default candidate
     * selected during initialization.
     *
     * https://github.com/pjsip/pjproject/issues/1416:
     * Once ICE has failed, also send data with the default candidate.
     */
    if (ice_st->ice && ice_st->state <= PJ_ICE_STRANS_STATE_RUNNING) {
        status = pj_ice_sess_send_data(ice_st->ice, comp_id, buf, data_len);
        if (status == PJ_SUCCESS || status == PJ_EPENDING) {
            pj_grp_lock_release(ice_st->grp_lock);
            goto on_return;
        }
    } 

    pj_grp_lock_release(ice_st->grp_lock);

    def_cand = &comp->cand_list[comp->default_cand];
    
    if (def_cand->status == PJ_SUCCESS) {
        unsigned tp_idx = GET_TP_IDX(def_cand->transport_id);

        if (def_cand->type == PJ_ICE_CAND_TYPE_RELAYED) {

            enum {
                msg_disable_ind = 0xFFFF &
                                  ~(PJ_STUN_SESS_LOG_TX_IND|
                                    PJ_STUN_SESS_LOG_RX_IND)
            };

            /* https://github.com/pjsip/pjproject/issues/1316 */
            if (comp->turn[tp_idx].sock == NULL) {
                /* TURN socket error */
                status = PJ_EINVALIDOP;
                goto on_return;
            }

            if (!comp->turn[tp_idx].log_off) {
                /* Disable logging for Send/Data indications */
                PJ_LOG(5,(ice_st->obj_name,
                          "Disabling STUN Indication logging for "
                          "component %d", comp->comp_id));
                pj_turn_sock_set_log(comp->turn[tp_idx].sock,
                                     msg_disable_ind);
                comp->turn[tp_idx].log_off = PJ_TRUE;
            }

            status = pj_turn_sock_sendto(comp->turn[tp_idx].sock,
                                         (const pj_uint8_t*)buf,
                                         (unsigned)data_len,
                                         dst_addr, dst_addr_len);
            goto on_return;
        } else {
            const pj_sockaddr_t *dest_addr;
            unsigned dest_addr_len;

            if (comp->ipv4_mapped) {
                if (comp->synth_addr_len == 0 ||
                    pj_sockaddr_cmp(&comp->dst_addr, dst_addr) != 0)
                {
                    status = pj_sockaddr_synthesize(pj_AF_INET6(),
                                                    &comp->synth_addr,
                                                    dst_addr);
                    if (status != PJ_SUCCESS)
                        goto on_return;

                    pj_sockaddr_cp(&comp->dst_addr, dst_addr);
                    comp->synth_addr_len = pj_sockaddr_get_len(
                                               &comp->synth_addr);
                }
                dest_addr = &comp->synth_addr;
                dest_addr_len = comp->synth_addr_len;
            } else {
                dest_addr = dst_addr;
                dest_addr_len = dst_addr_len;
            }

            status = pj_stun_sock_sendto(comp->stun[tp_idx].sock, NULL, buf,
                                         (unsigned)data_len, 0, dest_addr,
                                         dest_addr_len);
            goto on_return;
        }

    } else
        status = PJ_EINVALIDOP;

on_return:
    /* We continue later in on_data_sent() callback. */
    if (status == PJ_EPENDING)
        return status;

    if (call_cb) {
        on_data_sent(ice_st, (status == PJ_SUCCESS? data_len: -status));
    } else {
        check_pending_send(ice_st);
    }

    return status;
}


#if !DEPRECATED_FOR_TICKET_2229
/*
 * Application wants to send outgoing packet.
 */
PJ_DEF(pj_status_t) pj_ice_strans_sendto( pj_ice_strans *ice_st,
                                          unsigned comp_id,
                                          const void *data,
                                          pj_size_t data_len,
                                          const pj_sockaddr_t *dst_addr,
                                          int dst_addr_len)
{
    pj_status_t status;

    PJ_LOG(1, (ice_st->obj_name, "pj_ice_strans_sendto() is deprecated. "
                                 "Application is recommended to use "
                                 "pj_ice_strans_sendto2() instead."));
    status = send_data(ice_st, comp_id, data, data_len, dst_addr,
                       dst_addr_len, PJ_TRUE, PJ_FALSE);
    if (status == PJ_EPENDING)
        status = PJ_SUCCESS;
    
    return status;
}
#endif


/*
 * Application wants to send outgoing packet.
 */
PJ_DEF(pj_status_t) pj_ice_strans_sendto2(pj_ice_strans *ice_st,
                                          unsigned comp_id,
                                          const void *data,
                                          pj_size_t data_len,
                                          const pj_sockaddr_t *dst_addr,
                                          int dst_addr_len)
{
    ice_st->call_send_cb = PJ_TRUE;
    return send_data(ice_st, comp_id, data, data_len, dst_addr,
                     dst_addr_len, PJ_TRUE, PJ_FALSE);
}

static void on_valid_pair(pj_ice_sess *ice)
{
    pj_time_val t;
    unsigned msec;
    pj_ice_strans *ice_st = (pj_ice_strans *)ice->user_data;
    pj_ice_strans_cb cb   = ice_st->cb;
    pj_status_t status    = PJ_SUCCESS;

    pj_grp_lock_add_ref(ice_st->grp_lock);

    pj_gettimeofday(&t);
    PJ_TIME_VAL_SUB(t, ice_st->start_time);
    msec = PJ_TIME_VAL_MSEC(t);

    if (cb.on_valid_pair) {
        unsigned i;
        enum {
            msg_disable_ind = 0xFFFF & ~(PJ_STUN_SESS_LOG_TX_IND |
                                         PJ_STUN_SESS_LOG_RX_IND)
        };

        PJ_LOG(4,
               (ice_st->obj_name, "First ICE candidate nominated in %ds:%03d",
                msec / 1000, msec % 1000));

        for (i = 0; i < ice_st->comp_cnt; ++i) {
            const pj_ice_sess_check *check;
            pj_ice_strans_comp *comp = ice_st->comp[i];

            check = pj_ice_strans_get_valid_pair(ice_st, i + 1);
            if (check) {
                char lip[PJ_INET6_ADDRSTRLEN + 10];
                char rip[PJ_INET6_ADDRSTRLEN + 10];
                unsigned tp_idx = GET_TP_IDX(check->lcand->transport_id);
                unsigned tp_typ = GET_TP_TYPE(check->lcand->transport_id);

                pj_sockaddr_print(&check->lcand->addr, lip, sizeof(lip), 3);
                pj_sockaddr_print(&check->rcand->addr, rip, sizeof(rip), 3);

                if (tp_typ == TP_TURN) {
                    /* Activate channel binding for the remote address
                     * for more efficient data transfer using TURN.
                     */
                    status = pj_turn_sock_bind_channel(
                            comp->turn[tp_idx].sock, &check->rcand->addr,
                            sizeof(check->rcand->addr));

                    /* Disable logging for Send/Data indications */
                    PJ_LOG(5, (ice_st->obj_name,
                               "Disabling STUN Indication logging for "
                               "component %d",
                               i + 1));
                    pj_turn_sock_set_log(comp->turn[tp_idx].sock,
                                         msg_disable_ind);
                    comp->turn[tp_idx].log_off = PJ_TRUE;
                }

                PJ_LOG(4, (ice_st->obj_name,
                           " Comp %d: "
                           "sending from %s candidate %s to "
                           "%s candidate %s",
                           i + 1, pj_ice_get_cand_type_name(check->lcand->type),
                           lip, pj_ice_get_cand_type_name(check->rcand->type),
                           rip));

            } else {
                PJ_LOG(4, (ice_st->obj_name, "Comp %d: disabled", i + 1));
            }
        }

        ice_st->state = (status == PJ_SUCCESS) ? PJ_ICE_STRANS_STATE_RUNNING :
                                                 PJ_ICE_STRANS_STATE_FAILED;

        pj_log_push_indent();
        (*cb.on_valid_pair)(ice_st);
        pj_log_pop_indent();
    }

    pj_grp_lock_dec_ref(ice_st->grp_lock);
}

/*
 * Callback called by ICE session when ICE processing is complete, either
 * successfully or with failure.
 */
static void on_ice_complete(pj_ice_sess *ice, pj_status_t status)
{
    pj_ice_strans *ice_st = (pj_ice_strans*)ice->user_data;
    pj_time_val t;
    unsigned msec;
    pj_ice_strans_cb cb = ice_st->cb;

    pj_grp_lock_add_ref(ice_st->grp_lock);

    pj_gettimeofday(&t);
    PJ_TIME_VAL_SUB(t, ice_st->start_time);
    msec = PJ_TIME_VAL_MSEC(t);

    if (cb.on_ice_complete) {
        if (status != PJ_SUCCESS) {
            PJ_PERROR(4,(ice_st->obj_name, status,
                         "ICE negotiation failed after %ds:%03d",
                         msec/1000, msec%1000));
        } else {
            unsigned i;
            enum {
                msg_disable_ind = 0xFFFF &
                                  ~(PJ_STUN_SESS_LOG_TX_IND|
                                    PJ_STUN_SESS_LOG_RX_IND)
            };

            PJ_LOG(4,(ice_st->obj_name,
                      "ICE negotiation success after %ds:%03d",
                      msec/1000, msec%1000));

            for (i=0; i<ice_st->comp_cnt; ++i) {
                const pj_ice_sess_check *check;
                pj_ice_strans_comp *comp = ice_st->comp[i];

                check = pj_ice_strans_get_valid_pair(ice_st, i+1);
                if (check) {
                    char lip[PJ_INET6_ADDRSTRLEN+10];
                    char rip[PJ_INET6_ADDRSTRLEN+10];
                    unsigned tp_idx = GET_TP_IDX(check->lcand->transport_id);
                    unsigned tp_typ = GET_TP_TYPE(check->lcand->transport_id);

                    pj_sockaddr_print(&check->lcand->addr, lip,
                                      sizeof(lip), 3);
                    pj_sockaddr_print(&check->rcand->addr, rip,
                                      sizeof(rip), 3);

                    if (tp_typ == TP_TURN) {
                        /* Activate channel binding for the remote address
                         * for more efficient data transfer using TURN.
                         */
                        status = pj_turn_sock_bind_channel(
                                        comp->turn[tp_idx].sock,
                                        &check->rcand->addr,
                                        sizeof(check->rcand->addr));

                        /* Disable logging for Send/Data indications */
                        PJ_LOG(5,(ice_st->obj_name,
                                  "Disabling STUN Indication logging for "
                                  "component %d", i+1));
                        pj_turn_sock_set_log(comp->turn[tp_idx].sock,
                                             msg_disable_ind);
                        comp->turn[tp_idx].log_off = PJ_TRUE;
                    }

                    PJ_LOG(4,(ice_st->obj_name, " Comp %d: "
                              "sending from %s candidate %s to "
                              "%s candidate %s",
                              i+1,
                              pj_ice_get_cand_type_name(check->lcand->type),
                              lip,
                              pj_ice_get_cand_type_name(check->rcand->type),
                              rip));

                } else {
                    PJ_LOG(4,(ice_st->obj_name,
                              "Comp %d: disabled", i+1));
                }
            }
        }

        ice_st->state = (status==PJ_SUCCESS) ? PJ_ICE_STRANS_STATE_RUNNING :
                                               PJ_ICE_STRANS_STATE_FAILED;

        pj_log_push_indent();
        (*cb.on_ice_complete)(ice_st, PJ_ICE_STRANS_OP_NEGOTIATION, status);
        pj_log_pop_indent();

    }

    pj_grp_lock_dec_ref(ice_st->grp_lock);
}

/*
 * Callback called by ICE session when it wants to send outgoing packet.
 */
static pj_status_t ice_tx_pkt(pj_ice_sess *ice,
                              unsigned comp_id,
                              unsigned transport_id,
                              const void *pkt, pj_size_t size,
                              const pj_sockaddr_t *dst_addr,
                              unsigned dst_addr_len)
{
    pj_ice_strans *ice_st = (pj_ice_strans*)ice->user_data;
    pj_ice_strans_comp *comp;
    pj_status_t status;
    void *buf = (void *)pkt;
    pj_bool_t use_buf = PJ_FALSE;
#if defined(ENABLE_TRACE) && (ENABLE_TRACE != 0)
    char daddr[PJ_INET6_ADDRSTRLEN];
#endif
    unsigned tp_idx = GET_TP_IDX(transport_id);
    unsigned tp_typ = GET_TP_TYPE(transport_id);

    PJ_ASSERT_RETURN(comp_id && comp_id <= ice_st->comp_cnt, PJ_EINVAL);

    pj_grp_lock_acquire(ice_st->grp_lock);
    if (ice_st->num_buf > 0 &&
        (!ice_st->send_buf ||
         ice_st->send_buf[ice_st->buf_idx].buffer != pkt))
    {
        use_buf = PJ_TRUE;
        status = use_buffer(ice_st, comp_id, pkt, size, dst_addr,
                            dst_addr_len, &buf);
        if (status == PJ_EPENDING || status != PJ_SUCCESS) {
            pj_grp_lock_release(ice_st->grp_lock);
            return status;
        }
    }
    pj_grp_lock_release(ice_st->grp_lock);

    comp = ice_st->comp[comp_id-1];

    TRACE_PKT((comp->ice_st->obj_name,
               "Component %d TX packet to %s:%d with transport %d",
               comp_id,
               pj_sockaddr_print(dst_addr, daddr, sizeof(addr), 2),
               pj_sockaddr_get_port(dst_addr),
               tp_typ));

    if (tp_typ == TP_TURN) {
        if (comp->turn[tp_idx].sock) {
            status = pj_turn_sock_sendto(comp->turn[tp_idx].sock,
                                         (const pj_uint8_t*)buf,
                                         (unsigned)size,
                                         dst_addr, dst_addr_len);
        } else {
            status = PJ_EINVALIDOP;
        }
    } else if (tp_typ == TP_STUN) {
        const pj_sockaddr_t *dest_addr;
        unsigned dest_addr_len;

        if (comp->ipv4_mapped) {
            if (comp->synth_addr_len == 0 ||
                pj_sockaddr_cmp(&comp->dst_addr, dst_addr) != 0)
            {
                status = pj_sockaddr_synthesize(pj_AF_INET6(),
                                                &comp->synth_addr, dst_addr);
                if (status != PJ_SUCCESS) {
                    goto on_return;
                }
            
                pj_sockaddr_cp(&comp->dst_addr, dst_addr);
                comp->synth_addr_len = pj_sockaddr_get_len(&comp->synth_addr);
            }
            dest_addr = &comp->synth_addr;
            dest_addr_len = comp->synth_addr_len;
        } else {
            dest_addr = dst_addr;
            dest_addr_len = dst_addr_len;
        }

        status = pj_stun_sock_sendto(comp->stun[tp_idx].sock, NULL,
                                     buf, (unsigned)size, 0,
                                     dest_addr, dest_addr_len);
    } else {
        pj_assert(!"Invalid transport ID");
        status = PJ_EINVALIDOP;
    }

on_return:
    if (use_buf && status != PJ_EPENDING) {
        pj_grp_lock_acquire(ice_st->grp_lock);
        if (ice_st->num_buf > 0) {
            ice_st->buf_idx = (ice_st->buf_idx + 1) % ice_st->num_buf;
            pj_assert(ice_st->buf_idx == ice_st->empty_idx);
        }
        ice_st->is_pending = PJ_FALSE;
        pj_grp_lock_release(ice_st->grp_lock);
    }

    return status;
}

/*
 * Callback called by ICE session when it receives application data.
 */
static void ice_rx_data(pj_ice_sess *ice,
                        unsigned comp_id,
                        unsigned transport_id,
                        void *pkt, pj_size_t size,
                        const pj_sockaddr_t *src_addr,
                        unsigned src_addr_len)
{
    pj_ice_strans *ice_st = (pj_ice_strans*)ice->user_data;

    PJ_UNUSED_ARG(transport_id);

    if (ice_st->cb.on_rx_data) {
        (*ice_st->cb.on_rx_data)(ice_st, comp_id, pkt, size,
                                 src_addr, src_addr_len);
    }
}

static void check_pending_send(pj_ice_strans *ice_st)
{
    pj_grp_lock_acquire(ice_st->grp_lock);

    if (ice_st->num_buf > 0)
        ice_st->buf_idx = (ice_st->buf_idx + 1) % ice_st->num_buf;
    
    if (ice_st->num_buf > 0 && ice_st->buf_idx != ice_st->empty_idx) {
        /* There's some pending send. Send it one by one. */
        pending_send *ps = &ice_st->send_buf[ice_st->buf_idx];

        pj_grp_lock_release(ice_st->grp_lock);
        send_data(ice_st, ps->comp_id, ps->buffer, ps->data_len,
                  &ps->dst_addr, ps->dst_addr_len, PJ_FALSE, PJ_TRUE);
    } else {
        ice_st->is_pending = PJ_FALSE;
        pj_grp_lock_release(ice_st->grp_lock);
    }
}

/* Notifification when asynchronous send operation via STUN/TURN
 * has completed.
 */
static pj_bool_t on_data_sent(pj_ice_strans *ice_st, pj_ssize_t sent)
{
    if (ice_st->destroy_req || !ice_st->is_pending)
        return PJ_TRUE;

    if (ice_st->call_send_cb && ice_st->cb.on_data_sent) {
        (*ice_st->cb.on_data_sent)(ice_st, sent);
    }

    check_pending_send(ice_st);

    return PJ_TRUE;
}

/* Notification when incoming packet has been received from
 * the STUN socket.
 */
static pj_bool_t stun_on_rx_data(pj_stun_sock *stun_sock,
                                 void *pkt,
                                 unsigned pkt_len,
                                 const pj_sockaddr_t *src_addr,
                                 unsigned addr_len)
{
    sock_user_data *data;
    pj_ice_strans_comp *comp;
    pj_ice_strans *ice_st;
    pj_status_t status;

    data = (sock_user_data*) pj_stun_sock_get_user_data(stun_sock);
    if (data == NULL) {
        /* We have disassociated ourselves from the STUN socket */
        return PJ_FALSE;
    }

    comp = data->comp;
    ice_st = comp->ice_st;

    pj_grp_lock_add_ref(ice_st->grp_lock);

    if (ice_st->ice == NULL) {
        /* The ICE session is gone, but we're still receiving packets.
         * This could also happen if remote doesn't do ICE. So just
         * report this to application.
         */
        if (ice_st->cb.on_rx_data) {
            (*ice_st->cb.on_rx_data)(ice_st, comp->comp_id, pkt, pkt_len,
                                     src_addr, addr_len);
        }

    } else {

        /* Hand over the packet to ICE session */
        status = pj_ice_sess_on_rx_pkt(comp->ice_st->ice, comp->comp_id,
                                       data->transport_id,
                                       pkt, pkt_len,
                                       src_addr, addr_len);

        if (status != PJ_SUCCESS) {
            ice_st_perror(comp->ice_st, "Error processing packet",
                          status);
        }
    }

    return pj_grp_lock_dec_ref(ice_st->grp_lock) ? PJ_FALSE : PJ_TRUE;
}

/* Notifification when asynchronous send operation to the STUN socket
 * has completed.
 */
static pj_bool_t stun_on_data_sent(pj_stun_sock *stun_sock,
                                   pj_ioqueue_op_key_t *send_key,
                                   pj_ssize_t sent)
{
    sock_user_data *data;

    PJ_UNUSED_ARG(send_key);

    data = (sock_user_data *)pj_stun_sock_get_user_data(stun_sock);
    if (!data || !data->comp || !data->comp->ice_st) return PJ_TRUE;

    return on_data_sent(data->comp->ice_st, sent);
}

/* Notification when the status of the STUN transport has changed. */
static pj_bool_t stun_on_status(pj_stun_sock *stun_sock,
                                pj_stun_sock_op op,
                                pj_status_t status)
{
    sock_user_data *data;
    pj_ice_strans_comp *comp;
    pj_ice_strans *ice_st;
    pj_ice_sess_cand *cand = NULL;
    unsigned i;
    int tp_idx;

    pj_assert(status != PJ_EPENDING);

    data = (sock_user_data*) pj_stun_sock_get_user_data(stun_sock);
    comp = data->comp;
    ice_st = comp->ice_st;

    pj_grp_lock_add_ref(ice_st->grp_lock);

    /* Wait until initialization completes */
    pj_grp_lock_acquire(ice_st->grp_lock);

    /* Find the srflx cancidate */
    for (i=0; i<comp->cand_cnt; ++i) {
        if (comp->cand_list[i].type == PJ_ICE_CAND_TYPE_SRFLX &&
            comp->cand_list[i].transport_id == data->transport_id)
        {
            cand = &comp->cand_list[i];
            break;
        }
    }

    pj_grp_lock_release(ice_st->grp_lock);

    /* It is possible that we don't have srflx candidate even though this
     * callback is called. This could happen when we cancel adding srflx
     * candidate due to initialization error.
     */
    if (cand == NULL) {
        return pj_grp_lock_dec_ref(ice_st->grp_lock) ? PJ_FALSE : PJ_TRUE;
    }

    tp_idx = GET_TP_IDX(data->transport_id);

    switch (op) {
    case PJ_STUN_SOCK_DNS_OP:
        if (status != PJ_SUCCESS) {
            /* May not have cand, e.g. when error during init */
            if (cand)
                cand->status = status;
            if (!ice_st->cfg.stun_tp[tp_idx].ignore_stun_error) {
                sess_fail(ice_st, PJ_ICE_STRANS_OP_INIT,
                          "DNS resolution failed", status);
            } else {
                PJ_LOG(4,(ice_st->obj_name,
                          "STUN error is ignored for comp %d",
                          comp->comp_id));
            }
        }
        break;
    case PJ_STUN_SOCK_BINDING_OP:
    case PJ_STUN_SOCK_MAPPED_ADDR_CHANGE:
        if (status == PJ_SUCCESS) {
            pj_stun_sock_info info;

            status = pj_stun_sock_get_info(stun_sock, &info);
            if (status == PJ_SUCCESS) {
                char ipaddr[PJ_INET6_ADDRSTRLEN+10];
                const char *op_name = (op==PJ_STUN_SOCK_BINDING_OP) ?
                                    "Binding discovery complete" :
                                    "srflx address changed";
                pj_bool_t dup = PJ_FALSE;
                pj_bool_t init_done;

                if (info.mapped_addr.addr.sa_family == pj_AF_INET() &&
                    cand->base_addr.addr.sa_family == pj_AF_INET6())
                {
                    /* We get an IPv4 mapped address for our IPv6
                     * host address.
                     */              
                    comp->ipv4_mapped = PJ_TRUE;

                    /* Find other host candidates with the same (IPv6)
                     * address, and replace it with the new (IPv4)
                     * mapped address.
                     */
                    for (i = 0; i < comp->cand_cnt; ++i) {
                        pj_sockaddr *a1, *a2;

                        if (comp->cand_list[i].type != PJ_ICE_CAND_TYPE_HOST)
                            continue;
                        
                        a1 = &comp->cand_list[i].addr;
                        a2 = &cand->base_addr;
                        if (pj_memcmp(pj_sockaddr_get_addr(a1),
                                      pj_sockaddr_get_addr(a2),
                                      pj_sockaddr_get_addr_len(a1)) == 0)
                        {
                            pj_uint16_t port = pj_sockaddr_get_port(a1);
                            pj_sockaddr_cp(a1, &info.mapped_addr);
                            if (port != pj_sockaddr_get_port(a2))
                                pj_sockaddr_set_port(a1, port);
                            pj_sockaddr_cp(&comp->cand_list[i].base_addr, a1);
                        }
                    }
                    pj_sockaddr_cp(&cand->base_addr, &info.mapped_addr);
                    pj_sockaddr_cp(&cand->rel_addr, &info.mapped_addr);
                }
                
                /* Eliminate the srflx candidate if the address is
                 * equal to other (host) candidates.
                 */
                for (i=0; i<comp->cand_cnt; ++i) {
                    if (comp->cand_list[i].type == PJ_ICE_CAND_TYPE_HOST &&
                        pj_sockaddr_cmp(&comp->cand_list[i].addr,
                                        &info.mapped_addr) == 0)
                    {
                        dup = PJ_TRUE;
                        break;
                    }
                }

                if (dup) {
                    /* Duplicate found, remove the srflx candidate */
                    unsigned idx = (unsigned)(cand - comp->cand_list);

                    /* Update default candidate index */
                    if (comp->default_cand > idx) {
                        --comp->default_cand;
                    } else if (comp->default_cand == idx) {
                        comp->default_cand = 0;
                    }

                    /* Remove srflx candidate */
                    pj_array_erase(comp->cand_list, sizeof(comp->cand_list[0]),
                                   comp->cand_cnt, idx);
                    --comp->cand_cnt;
                } else {
                    /* Otherwise update the address */
                    pj_sockaddr_cp(&cand->addr, &info.mapped_addr);
                    cand->status = PJ_SUCCESS;

                    /* Add the candidate (for trickle ICE) */
                    if (pj_ice_strans_has_sess(ice_st)) {
                        status = pj_ice_sess_add_cand(
                                        ice_st->ice,
                                        comp->comp_id,
                                        cand->transport_id,
                                        cand->type,
                                        cand->local_pref,
                                        &cand->foundation,
                                        &cand->addr,
                                        &cand->base_addr,
                                        &cand->rel_addr,
                                        pj_sockaddr_get_len(&cand->addr),
                                        NULL);
                    }
                }

                PJ_LOG(4,(comp->ice_st->obj_name,
                          "Comp %d: %s, "
                          "srflx address is %s",
                          comp->comp_id, op_name,
                          pj_sockaddr_print(&info.mapped_addr, ipaddr,
                                             sizeof(ipaddr), 3)));

                sess_init_update(ice_st);

                /* Invoke on_new_candidate() callback */
                init_done = (ice_st->state==PJ_ICE_STRANS_STATE_READY);
                if (op == PJ_STUN_SOCK_BINDING_OP && status == PJ_SUCCESS &&
                    ice_st->cb.on_new_candidate && (!dup || init_done))
                {
                    (*ice_st->cb.on_new_candidate)
                                        (ice_st, (dup? NULL:cand), init_done);
                }

                if (op == PJ_STUN_SOCK_MAPPED_ADDR_CHANGE &&
                    ice_st->cb.on_ice_complete)
                {
                    (*ice_st->cb.on_ice_complete)(ice_st, 
                                                  PJ_ICE_STRANS_OP_ADDR_CHANGE,
                                                  status);
                }
            }
        }

        if (status != PJ_SUCCESS) {
            /* May not have cand, e.g. when error during init */
            if (cand)
                cand->status = status;
            if (!ice_st->cfg.stun_tp[tp_idx].ignore_stun_error ||
                comp->cand_cnt==1)
            {
                sess_fail(ice_st, PJ_ICE_STRANS_OP_INIT,
                          "STUN binding request failed", status);
            } else {
                pj_bool_t init_done;

                PJ_LOG(4,(ice_st->obj_name,
                          "STUN error is ignored for comp %d",
                          comp->comp_id));

                if (cand) {
                    unsigned idx = (unsigned)(cand - comp->cand_list);

                    /* Update default candidate index */
                    if (comp->default_cand == idx) {
                        comp->default_cand = !idx;
                    }
                }

                sess_init_update(ice_st);

                /* Invoke on_new_candidate() callback */
                init_done = (ice_st->state==PJ_ICE_STRANS_STATE_READY);
                if (op == PJ_STUN_SOCK_BINDING_OP &&
                    ice_st->cb.on_new_candidate && init_done)
                {
                    (*ice_st->cb.on_new_candidate) (ice_st, NULL, PJ_TRUE);
                }
            }
        }
        break;
    case PJ_STUN_SOCK_KEEP_ALIVE_OP:
        if (status != PJ_SUCCESS) {
            pj_assert(cand != NULL);
            cand->status = status;
            if (!ice_st->cfg.stun_tp[tp_idx].ignore_stun_error) {
                sess_fail(ice_st, PJ_ICE_STRANS_OP_INIT,
                          "STUN keep-alive failed", status);
            } else {
                PJ_LOG(4,(ice_st->obj_name, "STUN error is ignored"));
            }
        }
        break;
    }

    return pj_grp_lock_dec_ref(ice_st->grp_lock)? PJ_FALSE : PJ_TRUE;
}

/* Callback when TURN socket has received a packet */
static void turn_on_rx_data(pj_turn_sock *turn_sock,
                            void *pkt,
                            unsigned pkt_len,
                            const pj_sockaddr_t *peer_addr,
                            unsigned addr_len)
{
    pj_ice_strans_comp *comp;
    sock_user_data *data;
    pj_status_t status;

    data = (sock_user_data*) pj_turn_sock_get_user_data(turn_sock);
    if (data == NULL) {
        /* We have disassociated ourselves from the TURN socket */
        return;
    }

    comp = data->comp;

    pj_grp_lock_add_ref(comp->ice_st->grp_lock);

    if (comp->ice_st->ice == NULL) {
        /* The ICE session is gone, but we're still receiving packets.
         * This could also happen if remote doesn't do ICE and application
         * specifies TURN as the default address in SDP.
         * So in this case just give the packet to application.
         */
        if (comp->ice_st->cb.on_rx_data) {
            (*comp->ice_st->cb.on_rx_data)(comp->ice_st, comp->comp_id, pkt,
                                           pkt_len, peer_addr, addr_len);
        }

    } else {

        /* Hand over the packet to ICE */
        status = pj_ice_sess_on_rx_pkt(comp->ice_st->ice, comp->comp_id,
                                       data->transport_id, pkt, pkt_len,
                                       peer_addr, addr_len);

        if (status != PJ_SUCCESS) {
            ice_st_perror(comp->ice_st,
                          "Error processing packet from TURN relay",
                          status);
        }
    }

    pj_grp_lock_dec_ref(comp->ice_st->grp_lock);
}

/* Notifification when asynchronous send operation to the TURN socket
 * has completed.
 */
static pj_bool_t turn_on_data_sent(pj_turn_sock *turn_sock,
                                   pj_ssize_t sent)
{
    sock_user_data *data;

    data = (sock_user_data *)pj_turn_sock_get_user_data(turn_sock);
    if (!data || !data->comp || !data->comp->ice_st) return PJ_TRUE;

    return on_data_sent(data->comp->ice_st, sent);
}

/* Callback when TURN client state has changed */
static void turn_on_state(pj_turn_sock *turn_sock, pj_turn_state_t old_state,
                          pj_turn_state_t new_state)
{
    pj_ice_strans_comp *comp;
    sock_user_data *data;
    int tp_idx;

    data = (sock_user_data*) pj_turn_sock_get_user_data(turn_sock);
    if (data == NULL) {
        /* Not interested in further state notification once the relay is
         * disconnecting.
         */
        return;
    }

    comp = data->comp;
    tp_idx = GET_TP_IDX(data->transport_id);

    PJ_LOG(5,(comp->ice_st->obj_name, "TURN client state changed %s --> %s",
              pj_turn_state_name(old_state), pj_turn_state_name(new_state)));
    pj_log_push_indent();

    pj_grp_lock_add_ref(comp->ice_st->grp_lock);

    if (new_state == PJ_TURN_STATE_READY) {
        pj_turn_session_info rel_info;
        char ipaddr[PJ_INET6_ADDRSTRLEN+8];
        pj_ice_sess_cand *cand = NULL;
        unsigned i, cand_idx = 0xFF;

        comp->turn[tp_idx].err_cnt = 0;

        /* Get allocation info */
        pj_turn_sock_get_info(turn_sock, &rel_info);

        /* Wait until initialization completes */
        pj_grp_lock_acquire(comp->ice_st->grp_lock);

        /* Find relayed candidate in the component */
        for (i=0; i<comp->cand_cnt; ++i) {
            if (comp->cand_list[i].type == PJ_ICE_CAND_TYPE_RELAYED &&
                comp->cand_list[i].transport_id == data->transport_id)
            {
                cand = &comp->cand_list[i];
                cand_idx = i;
                break;
            }
        }

        pj_grp_lock_release(comp->ice_st->grp_lock);

        if (cand == NULL)
            goto on_return;

        /* Update candidate */
        pj_sockaddr_cp(&cand->addr, &rel_info.relay_addr);
        pj_sockaddr_cp(&cand->base_addr, &rel_info.relay_addr);
        pj_sockaddr_cp(&cand->rel_addr, &rel_info.mapped_addr);
        pj_ice_calc_foundation(comp->ice_st->pool, &cand->foundation,
                               PJ_ICE_CAND_TYPE_RELAYED,
                               &rel_info.relay_addr);
        cand->status = PJ_SUCCESS;

        /* Set default candidate to relay */
        if (comp->cand_list[comp->default_cand].type!=PJ_ICE_CAND_TYPE_RELAYED
            || (comp->ice_st->cfg.af != pj_AF_UNSPEC() &&
                comp->cand_list[comp->default_cand].addr.addr.sa_family
                != comp->ice_st->cfg.af))
        {
            comp->default_cand = (unsigned)(cand - comp->cand_list);
        }

        /* Prefer IPv4 relay as default candidate for better connectivity
         * with IPv4 endpoints.
         */
        /*
        if (cand->addr.addr.sa_family != pj_AF_INET()) {
            for (i=0; i<comp->cand_cnt; ++i) {
                if (comp->cand_list[i].type == PJ_ICE_CAND_TYPE_RELAYED &&
                    comp->cand_list[i].addr.addr.sa_family == pj_AF_INET() &&
                    comp->cand_list[i].status == PJ_SUCCESS)
                {
                    comp->default_cand = i;
                    break;
                }
            }
        }
        */

        PJ_LOG(4,(comp->ice_st->obj_name,
                  "Comp %d/%d: TURN allocation (tpid=%d) complete, "
                  "relay address is %s",
                  comp->comp_id, cand_idx, cand->transport_id,
                  pj_sockaddr_print(&rel_info.relay_addr, ipaddr,
                                     sizeof(ipaddr), 3)));

        /* For trickle ICE, add the candidate to ICE session and setup TURN
         * permission for remote candidates.
         */
        if (comp->ice_st->cfg.opt.trickle != PJ_ICE_SESS_TRICKLE_DISABLED &&
            pj_ice_strans_has_sess(comp->ice_st))
        {
            pj_sockaddr addrs[PJ_ICE_ST_MAX_CAND];
            pj_ice_sess *sess = comp->ice_st->ice;
            unsigned j, count=0;
            pj_status_t status;

            /* Add the candidate */
            status = pj_ice_sess_add_cand(comp->ice_st->ice,
                                          comp->comp_id,
                                          cand->transport_id,
                                          cand->type,
                                          cand->local_pref,
                                          &cand->foundation,
                                          &cand->addr,
                                          &cand->base_addr, 
                                          &cand->rel_addr,
                                          pj_sockaddr_get_len(&cand->addr),
                                          NULL);
            if (status != PJ_SUCCESS) {
                PJ_PERROR(4,(comp->ice_st->obj_name, status,
                          "Comp %d/%d: failed to add TURN (tpid=%d) to ICE",
                          comp->comp_id, cand_idx, cand->transport_id));
                sess_fail(comp->ice_st, PJ_ICE_STRANS_OP_INIT,
                          "adding TURN candidate failed", status);
            }

            /* Gather remote addresses for this component */
            for (j=0; j<sess->rcand_cnt && count<PJ_ARRAY_SIZE(addrs); ++j) {
                if (sess->rcand[j].addr.addr.sa_family==
                    rel_info.relay_addr.addr.sa_family)
                {
                    pj_sockaddr_cp(&addrs[count++], &sess->rcand[j].addr);
                }
            }

            if (count) {
                status = pj_turn_sock_set_perm(turn_sock, count, addrs, 0);
                if (status != PJ_SUCCESS) {
                    PJ_PERROR(4,(comp->ice_st->obj_name, status,
                              "Comp %d/%d: TURN set perm (tpid=%d) failed",
                              comp->comp_id, cand_idx, cand->transport_id));
                    sess_fail(comp->ice_st, PJ_ICE_STRANS_OP_INIT,
                              "TURN set permission failed", status);
                }
            }
        }

        sess_init_update(comp->ice_st);

        /* Invoke on_new_candidate() callback */
        if (comp->ice_st->cb.on_new_candidate) {
            (*comp->ice_st->cb.on_new_candidate)
                        (comp->ice_st, cand,
                         (comp->ice_st->state==PJ_ICE_STRANS_STATE_READY));
        }

    } else if ((old_state == PJ_TURN_STATE_RESOLVING ||
                old_state == PJ_TURN_STATE_RESOLVED ||
                old_state == PJ_TURN_STATE_ALLOCATING) &&
               new_state >= PJ_TURN_STATE_DEALLOCATING)
    {
        pj_ice_sess_cand *cand = NULL;
        unsigned i, cand_idx = 0xFF;

        /* DNS resolution or TURN transport creation/allocation
         * has failed.
         */
        ++comp->turn[tp_idx].err_cnt;

        /* Unregister ourself from the TURN relay */
        pj_turn_sock_set_user_data(turn_sock, NULL);
        comp->turn[tp_idx].sock = NULL;

        /* Wait until initialization completes */
        pj_grp_lock_acquire(comp->ice_st->grp_lock);

        /* Find relayed candidate in the component */
        for (i=0; i<comp->cand_cnt; ++i) {
            if (comp->cand_list[i].type == PJ_ICE_CAND_TYPE_RELAYED &&
                comp->cand_list[i].transport_id == data->transport_id)
            {
                cand = &comp->cand_list[i];
                cand_idx = i;
                break;
            }
        }

        pj_grp_lock_release(comp->ice_st->grp_lock);

        /* If the error happens during pj_turn_sock_create() or
         * pj_turn_sock_alloc(), the candidate hasn't been added
         * to the list.
         */
        if (cand) {
            pj_turn_session_info info;

            pj_turn_sock_get_info(turn_sock, &info);
            cand->status = (old_state == PJ_TURN_STATE_RESOLVING)?
                           PJ_ERESOLVE : info.last_status;
            PJ_LOG(4,(comp->ice_st->obj_name,
                      "Comp %d/%d: TURN error (tpid=%d) during state %s",
                      comp->comp_id, cand_idx, cand->transport_id,
                      pj_turn_state_name(old_state)));
        }

        sess_init_update(comp->ice_st);

        /* Invoke on_new_candidate() callback */
        if (comp->ice_st->cb.on_new_candidate &&
            comp->ice_st->state==PJ_ICE_STRANS_STATE_READY)
        {
            (*comp->ice_st->cb.on_new_candidate)(comp->ice_st, NULL, PJ_TRUE);
        }

    } else if (new_state >= PJ_TURN_STATE_DEALLOCATING) {
        pj_turn_session_info info;

        ++comp->turn[tp_idx].err_cnt;

        pj_turn_sock_get_info(turn_sock, &info);

        /* Unregister ourself from the TURN relay */
        pj_turn_sock_set_user_data(turn_sock, NULL);
        comp->turn[tp_idx].sock = NULL;

        /* Set session to fail on error. last_status PJ_SUCCESS means normal
         * deallocation, which should not trigger sess_fail as it may have
         * been initiated by ICE destroy
         */
        if (info.last_status != PJ_SUCCESS) {
            if (comp->ice_st->state < PJ_ICE_STRANS_STATE_READY) {
                sess_fail(comp->ice_st, PJ_ICE_STRANS_OP_INIT,
                          "TURN allocation failed", info.last_status);
            } else if (comp->turn[tp_idx].err_cnt > 1) {
                sess_fail(comp->ice_st, PJ_ICE_STRANS_OP_KEEP_ALIVE,
                          "TURN refresh failed", info.last_status);
            } else {
                PJ_PERROR(4,(comp->ice_st->obj_name, info.last_status,
                          "Comp %d: TURN allocation failed, retrying",
                          comp->comp_id));
                add_update_turn(comp->ice_st, comp, tp_idx,
                                PJ_ICE_ST_MAX_CAND - comp->cand_cnt);
            }
        }
    }

on_return:
    pj_grp_lock_dec_ref(comp->ice_st->grp_lock);

    pj_log_pop_indent();
}

