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/*
 * This file is part of the Nice GLib ICE library.
 *
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 * (C) 2006-2009 Collabora Ltd.
 *  Contact: Youness Alaoui
 * (C) 2006-2009 Nokia Corporation. All rights reserved.
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 *  Contact: Kai Vehmanen
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is the Nice GLib ICE library.
 *
 * The Initial Developers of the Original Code are Collabora Ltd and Nokia
 * Corporation. All Rights Reserved.
 *
 * Contributors:
 *   Kai Vehmanen, Nokia
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 *   Youness Alaoui, Collabora Ltd.
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 *   Dafydd Harries, Collabora Ltd.
 *
 * Alternatively, the contents of this file may be used under the terms of the
 * the GNU Lesser General Public License Version 2.1 (the "LGPL"), in which
 * case the provisions of LGPL are applicable instead of those above. If you
 * wish to allow use of your version of this file only under the terms of the
 * LGPL and not to allow others to use your version of this file under the
 * MPL, indicate your decision by deleting the provisions above and replace
 * them with the notice and other provisions required by the LGPL. If you do
 * not delete the provisions above, a recipient may use your version of this
 * file under either the MPL or the LGPL.
 */

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/*
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 * @file conncheck.c
 * @brief ICE connectivity checks
 */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

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#include <errno.h>
#include <string.h>

#include <glib.h>

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#include "debug.h"

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#include "agent.h"
#include "agent-priv.h"
#include "conncheck.h"
#include "discovery.h"
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#include "stun/stun5389.h"
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#include "stun/usages/ice.h"
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#include "stun/usages/bind.h"
#include "stun/usages/turn.h"
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static void priv_update_check_list_failed_components (NiceAgent *agent, NiceStream *stream);
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static void priv_update_check_list_state_for_ready (NiceAgent *agent, NiceStream *stream, NiceComponent *component);
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static guint priv_prune_pending_checks (NiceAgent *agent, NiceStream *stream, guint component_id);
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static gboolean priv_schedule_triggered_check (NiceAgent *agent, NiceStream *stream, NiceComponent *component, NiceSocket *local_socket, NiceCandidate *remote_cand);
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static void priv_mark_pair_nominated (NiceAgent *agent, NiceStream *stream, NiceComponent *component, NiceCandidate *localcand, NiceCandidate *remotecand);
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static size_t priv_create_username (NiceAgent *agent, NiceStream *stream,
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    guint component_id, NiceCandidate *remote, NiceCandidate *local,
    uint8_t *dest, guint dest_len, gboolean inbound);
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static size_t priv_get_password (NiceAgent *agent, NiceStream *stream,
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    NiceCandidate *remote, uint8_t **password);
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static void candidate_check_pair_free (NiceAgent *agent,
    CandidateCheckPair *pair);
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static CandidateCheckPair *priv_conn_check_add_for_candidate_pair_matched (
    NiceAgent *agent, guint stream_id, NiceComponent *component,
    NiceCandidate *local, NiceCandidate *remote, NiceCheckState initial_state);
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static gboolean priv_update_selected_pair (NiceAgent *agent,
    NiceComponent *component, CandidateCheckPair *pair);
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static int priv_timer_expired (GTimeVal *timer, GTimeVal *now)
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{
  return (now->tv_sec == timer->tv_sec) ?
    now->tv_usec >= timer->tv_usec :
    now->tv_sec >= timer->tv_sec;
}
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static unsigned int priv_timer_remainder (GTimeVal *timer, GTimeVal *now)
{
  unsigned int delay;
  if (now->tv_sec > timer->tv_sec ||
      (now->tv_sec == timer->tv_sec && now->tv_usec > timer->tv_usec))
    return 0;
  delay = (timer->tv_sec - now->tv_sec) * 1000;
  delay += ((signed long)(timer->tv_usec - now->tv_usec)) / 1000;
  return delay;
}

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static gchar
priv_state_to_gchar (NiceCheckState state)
{
  switch (state) {
    case NICE_CHECK_WAITING:
      return 'W';
    case NICE_CHECK_IN_PROGRESS:
      return 'I';
    case NICE_CHECK_SUCCEEDED:
      return 'S';
    case NICE_CHECK_FAILED:
      return 'F';
    case NICE_CHECK_FROZEN:
      return 'Z';
    case NICE_CHECK_DISCOVERED:
      return 'D';
    default:
      g_assert_not_reached ();
  }
}

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static const gchar *
priv_state_to_string (NiceCheckState state)
{
  switch (state) {
    case NICE_CHECK_WAITING:
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      return "WAITING";
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    case NICE_CHECK_IN_PROGRESS:
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      return "IN_PROGRESS";
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    case NICE_CHECK_SUCCEEDED:
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      return "SUCCEEDED";
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    case NICE_CHECK_FAILED:
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      return "FAILED";
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    case NICE_CHECK_FROZEN:
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      return "FROZEN";
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    case NICE_CHECK_DISCOVERED:
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      return "DISCOVERED";
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    default:
      g_assert_not_reached ();
  }
}

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#define SET_PAIR_STATE( a, p, s ) G_STMT_START{\
  g_assert (p); \
  p->state = s; \
  nice_debug ("Agent %p : pair %p state %s (%s)", \
      a, p, priv_state_to_string (s), G_STRFUNC); \
}G_STMT_END

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static const gchar *
priv_ice_return_to_string (StunUsageIceReturn ice_return)
{
  switch (ice_return) {
    case STUN_USAGE_ICE_RETURN_SUCCESS:
      return "success";
    case STUN_USAGE_ICE_RETURN_ERROR:
      return "error";
    case STUN_USAGE_ICE_RETURN_INVALID:
      return "invalid";
    case STUN_USAGE_ICE_RETURN_ROLE_CONFLICT:
      return "role conflict";
    case STUN_USAGE_ICE_RETURN_INVALID_REQUEST:
      return "invalid request";
    case STUN_USAGE_ICE_RETURN_INVALID_METHOD:
      return "invalid method";
    case STUN_USAGE_ICE_RETURN_MEMORY_ERROR:
      return "memory error";
    case STUN_USAGE_ICE_RETURN_INVALID_ADDRESS:
      return "invalid address";
    case STUN_USAGE_ICE_RETURN_NO_MAPPED_ADDRESS:
      return "no mapped address";
    default:
      g_assert_not_reached ();
  }
}

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static const gchar *
priv_candidate_type_to_string (NiceCandidateType type)
{
  switch (type) {
    case NICE_CANDIDATE_TYPE_HOST:
      return "host";
    case NICE_CANDIDATE_TYPE_SERVER_REFLEXIVE:
      return "srflx";
    case NICE_CANDIDATE_TYPE_PEER_REFLEXIVE:
      return "prflx";
    case NICE_CANDIDATE_TYPE_RELAYED:
      return "relay";
    default:
      g_assert_not_reached ();
  }
}

/*
 * Dump the conncheck lists of the agent
 */
static void
priv_print_conn_check_lists (NiceAgent *agent, const gchar *where, const gchar *detail)
{
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  GSList *i, *k, *l;
  guint j, m;
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  GTimeVal now;
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  if (!nice_debug_is_verbose ())
    return;

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  g_get_current_time (&now);

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#define PRIORITY_LEN 32

  nice_debug ("Agent %p : *** conncheck list DUMP (called from %s%s)",
      agent, where, detail ? detail : "");
  for (i = agent->streams; i ; i = i->next) {
    NiceStream *stream = i->data;
    for (j = 1; j <= stream->n_components; j++) {
      for (k = stream->conncheck_list; k ; k = k->next) {
        CandidateCheckPair *pair = k->data;
        if (pair->component_id == j) {
          gchar local_addr[INET6_ADDRSTRLEN];
          gchar remote_addr[INET6_ADDRSTRLEN];

          nice_address_to_string (&pair->local->addr, local_addr);
          nice_address_to_string (&pair->remote->addr, remote_addr);

          nice_debug ("Agent %p : *** sc=%d/%d : pair %p : "
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              "f=%s t=%s:%s [%s]:%u > [%s]:%u state=%c%s%s%s",
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              agent, pair->stream_id, pair->component_id, pair,
              pair->foundation,
              priv_candidate_type_to_string (pair->local->type),
              priv_candidate_type_to_string (pair->remote->type),
              local_addr, nice_address_get_port (&pair->local->addr),
              remote_addr, nice_address_get_port (&pair->remote->addr),
              priv_state_to_gchar (pair->state),
              pair->valid ? "V" : "",
              pair->nominated ? "N" : "",
              g_slist_find (agent->triggered_check_queue, pair) ? "T" : "");
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          for (l = pair->stun_transactions, m = 0; l; l = l->next, m++) {
            StunTransaction *stun = l->data;
            nice_debug ("Agent %p : *** sc=%d/%d : pair %p : "
                "stun#=%d timer=%d/%d %d/%dms buf=%p %s",
                agent, pair->stream_id, pair->component_id, pair, m,
                stun->timer.retransmissions, stun->timer.max_retransmissions,
                stun->timer.delay - priv_timer_remainder (&stun->next_tick, &now),
                stun->timer.delay,
                stun->message.buffer,
                (m == 0 && pair->retransmit) ? "(R)" : "");
          }
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        }
      }
    }
  }
}

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/* Add the pair to the triggered checks list, if not already present
 */
static void
priv_add_pair_to_triggered_check_queue (NiceAgent *agent, CandidateCheckPair *pair)
{
  g_assert (pair);

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  SET_PAIR_STATE (agent, pair, NICE_CHECK_IN_PROGRESS);
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  if (agent->triggered_check_queue == NULL ||
      g_slist_find (agent->triggered_check_queue, pair) == NULL)
    agent->triggered_check_queue = g_slist_append (agent->triggered_check_queue, pair);
}

/* Remove the pair from the triggered checks list
 */
static void
priv_remove_pair_from_triggered_check_queue (NiceAgent *agent, CandidateCheckPair *pair)
{
  g_assert (pair);
  agent->triggered_check_queue = g_slist_remove (agent->triggered_check_queue, pair);
}

/* Get the pair from the triggered checks list
 */
static CandidateCheckPair *
priv_get_pair_from_triggered_check_queue (NiceAgent *agent)
{
  CandidateCheckPair *pair = NULL;

  if (agent->triggered_check_queue) {
    pair = (CandidateCheckPair *)agent->triggered_check_queue->data;
    priv_remove_pair_from_triggered_check_queue (agent, pair);
  }
  return pair;
}

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/*
 * Check if the conncheck list if Active according to
 * ICE spec, 5.7.4 (Computing States)
 *
 * note: the ICE spec in unclear about that, but the check list should
 * be considered active when there is at least a pair in Waiting state
 * OR a pair in In-Progress state.
 */
static gboolean
priv_is_checklist_active (NiceStream *stream)
{
  GSList *i;

  for (i = stream->conncheck_list; i ; i = i->next) {
    CandidateCheckPair *p = i->data;
    if (p->state == NICE_CHECK_WAITING || p->state == NICE_CHECK_IN_PROGRESS)
      return TRUE;
  }
  return FALSE;
}

/*
 * Check if the conncheck list if Frozen according to
 * ICE spec, 5.7.4 (Computing States)
 */
static gboolean
priv_is_checklist_frozen (NiceStream *stream)
{
  GSList *i;

  if (stream->conncheck_list == NULL)
    return FALSE;

  for (i = stream->conncheck_list; i ; i = i->next) {
    CandidateCheckPair *p = i->data;
    if (p->state != NICE_CHECK_FROZEN)
      return FALSE;
  }
  return TRUE;
}

/*
 * Check if all components of the stream have
 * a valid pair (used for ICE spec, 7.1.3.2.3, point 2.)
 */
static gboolean
priv_all_components_have_valid_pair (NiceStream *stream)
{
  guint i;
  GSList *j;

  for (i = 1; i <= stream->n_components; i++) {
    for (j = stream->conncheck_list; j ; j = j->next) {
      CandidateCheckPair *p = j->data;
      if (p->component_id == i && p->valid)
        break;
    }
    if (j == NULL)
      return FALSE;
  }
  return TRUE;
}

/*
 * Check if the foundation in parameter matches the foundation
 * of a valid pair in the conncheck list [of stream] (used for ICE spec,
 * 7.1.3.2.3, point 2.)
 */
static gboolean
priv_foundation_matches_a_valid_pair (const gchar *foundation, NiceStream *stream)
{
  GSList *i;

  for (i = stream->conncheck_list; i ; i = i->next) {
    CandidateCheckPair *p = i->data;
    if (p->valid &&
        strncmp (p->foundation, foundation,
            NICE_CANDIDATE_PAIR_MAX_FOUNDATION) == 0)
      return TRUE;
  }
  return FALSE;
}

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/*
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 * Finds the next connectivity check in WAITING state.
 */
static CandidateCheckPair *priv_conn_check_find_next_waiting (GSList *conn_check_list)
{
  GSList *i;

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  /* note: list is sorted in priority order to first waiting check has
   *       the highest priority */
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  for (i = conn_check_list; i ; i = i->next) {
    CandidateCheckPair *p = i->data;
    if (p->state == NICE_CHECK_WAITING)
      return p;
  }

  return NULL;
}

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/*
 * Finds the next connectivity check in FROZEN state.
 */
static CandidateCheckPair *
priv_conn_check_find_next_frozen (GSList *conn_check_list)
{
  GSList *i;

  /* note: list is sorted in priority order to first frozen check has
   *       the highest priority */
  for (i = conn_check_list; i ; i = i->next) {
    CandidateCheckPair *p = i->data;
    if (p->state == NICE_CHECK_FROZEN)
      return p;
  }

  return NULL;
}

/*
 * Returns the number of active check lists of the agent
 */
static guint
priv_number_of_active_check_lists (NiceAgent *agent)
{
  guint n = 0;
  GSList *i;

  for (i = agent->streams; i ; i = i->next)
    if (priv_is_checklist_active (i->data))
      n++;
  return n;
}

/*
 * Returns the first stream of the agent having a Frozen
 * connection check list
 */
static NiceStream *
priv_find_first_frozen_check_list (NiceAgent *agent)
{
  GSList *i;

  for (i = agent->streams; i ; i = i->next) {
    NiceStream *stream = i->data;
    if (priv_is_checklist_frozen (stream))
      return stream;
  }
  return NULL;
}

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/*
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 * Initiates a new connectivity check for a ICE candidate pair.
 *
 * @return TRUE on success, FALSE on error
 */
static gboolean priv_conn_check_initiate (NiceAgent *agent, CandidateCheckPair *pair)
{
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  SET_PAIR_STATE (agent, pair, NICE_CHECK_IN_PROGRESS);
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  if (conn_check_send (agent, pair)) {
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    SET_PAIR_STATE (agent, pair, NICE_CHECK_FAILED);
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    return FALSE;
  }
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  return TRUE;
}

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/*
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 * Unfreezes the next connectivity check in the list. Follows the
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 * algorithm (2.) defined in 5.7.4 (Computing States) of the ICE spec
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 * (RFC5245)
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 *
 * See also sect 7.1.2.2.3 (Updating Pair States), and
 * priv_conn_check_unfreeze_related().
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 * 
 * @return TRUE on success, and FALSE if no frozen candidates were found.
 */
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static gboolean priv_conn_check_unfreeze_next (NiceAgent *agent, NiceStream *stream)
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{
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  GSList *i, *j;
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  GSList *found_list = NULL;
  gboolean result = FALSE;
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  priv_print_conn_check_lists (agent, G_STRFUNC, NULL);

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  for (i = stream->conncheck_list; i ; i = i->next) {
    CandidateCheckPair *p1 = i->data;
    CandidateCheckPair *pair = NULL;
    guint lowest_component_id = stream->n_components + 1;
    guint64 highest_priority = 0;
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    if (g_slist_find_custom (found_list, p1->foundation, (GCompareFunc)strcmp))
      continue;
    found_list = g_slist_prepend (found_list, p1->foundation);
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    for (j = stream->conncheck_list; j ; j = j->next) {
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      CandidateCheckPair *p2 = i->data;
      if (strncmp (p2->foundation, p1->foundation,
              NICE_CANDIDATE_PAIR_MAX_FOUNDATION) == 0) {
        if (p2->component_id < lowest_component_id ||
            (p2->component_id == lowest_component_id &&
             p2->priority > highest_priority)) {
          pair = p2;
          lowest_component_id = p2->component_id;
          highest_priority = p2->priority;
        }
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      }
    }
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    if (pair) {
      nice_debug ("Agent %p : Pair %p with s/c-id %u/%u (%s) unfrozen.",
          agent, pair, pair->stream_id, pair->component_id, pair->foundation);
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      SET_PAIR_STATE (agent, pair, NICE_CHECK_WAITING);
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      result = TRUE;
    }
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  }
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  g_slist_free (found_list);
  return result;
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}

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/*
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 * Unfreezes the next next connectivity check in the list after
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 * check 'success_check' has successfully completed.
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 *
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 * See sect 7.1.2.2.3 (Updating Pair States) of ICE spec (ID-19).
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 * 
 * @param agent context
 * @param ok_check a connectivity check that has just completed
 *
 * @return TRUE on success, and FALSE if no frozen candidates were found.
 */
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static void priv_conn_check_unfreeze_related (NiceAgent *agent, NiceStream *stream, CandidateCheckPair *ok_check)
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{
  GSList *i, *j;

  g_assert (ok_check);
  g_assert (ok_check->state == NICE_CHECK_SUCCEEDED);
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  g_assert (stream);
  g_assert (stream->id == ok_check->stream_id);
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  priv_print_conn_check_lists (agent, G_STRFUNC, NULL);

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  /* step: perform the step (1) of 'Updating Pair States' */
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  for (i = stream->conncheck_list; i ; i = i->next) {
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    CandidateCheckPair *p = i->data;
   
    if (p->stream_id == ok_check->stream_id) {
      if (p->state == NICE_CHECK_FROZEN &&
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          strncmp (p->foundation, ok_check->foundation,
              NICE_CANDIDATE_PAIR_MAX_FOUNDATION) == 0) {
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	nice_debug ("Agent %p : Unfreezing check %p (after successful check %p).", agent, p, ok_check);
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	SET_PAIR_STATE (agent, p, NICE_CHECK_WAITING);
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      }
    }
  }

  /* step: perform the step (2) of 'Updating Pair States' */
  stream = agent_find_stream (agent, ok_check->stream_id);
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  if (priv_all_components_have_valid_pair (stream)) {
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    for (i = agent->streams; i ; i = i->next) {
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      /* the agent examines the check list for each other
       * media stream in turn
       */
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      NiceStream *s = i->data;
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      if (s->id == ok_check->stream_id)
        continue;
      if (priv_is_checklist_active (s)) {
        /* checklist is Active
         */
        for (j = s->conncheck_list; j ; j = j->next) {
	  CandidateCheckPair *p = j->data;
          if (p->state == NICE_CHECK_FROZEN &&
              priv_foundation_matches_a_valid_pair (p->foundation, stream)) {
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	    nice_debug ("Agent %p : Unfreezing check %p from stream %u (after successful check %p).", agent, p, s->id, ok_check);
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	    SET_PAIR_STATE (agent, p, NICE_CHECK_WAITING);
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          }
        }
      } else if (priv_is_checklist_frozen (s)) {
        /* checklist is Frozen
         */
        gboolean match_found = FALSE;
        /* check if there is one pair in the check list whose
         * foundation matches a pair in the valid list under
         * consideration
         */
        for (j = s->conncheck_list; j ; j = j->next) {
	  CandidateCheckPair *p = j->data;
          if (priv_foundation_matches_a_valid_pair (p->foundation, stream)) {
            match_found = TRUE;
            nice_debug ("Agent %p : Unfreezing check %p from stream %u (after successful check %p).", agent, p, s->id, ok_check);
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            SET_PAIR_STATE (agent, p, NICE_CHECK_WAITING);
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          }
        }

        if (!match_found) {
          /* set the pair with the lowest component ID
           * and highest priority to Waiting
           */
          priv_conn_check_unfreeze_next (agent, s);
        }
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      }
    }
  }    
}

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/*
 * Create a new STUN transaction and add it to the list
 * of ongoing stun transactions of a pair.
 *
 * @pair the pair the new stun transaction should be added to.
 * @return the created stun transaction.
 */
static StunTransaction *
priv_add_stun_transaction (CandidateCheckPair *pair)
{
  StunTransaction *stun = g_slice_new0 (StunTransaction);
  pair->stun_transactions = g_slist_prepend (pair->stun_transactions, stun);
  pair->retransmit = TRUE;
  return stun;
}

/*
 * Forget a STUN transaction.
 *
 * @data the stun transaction to be forgotten.
 * @user_data the component contained the concerned stun agent.
 */
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static void
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priv_forget_stun_transaction (gpointer data, gpointer user_data)
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{
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  StunTransaction *stun = data;
  NiceComponent *component = user_data;
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  StunTransactionId id;

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  if (stun->message.buffer != NULL) {
    stun_message_id (&stun->message, id);
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    stun_agent_forget_transaction (&component->stun_agent, id);
  }
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}
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static void
priv_free_stun_transaction (gpointer data)
{
  g_slice_free (StunTransaction, data);
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}

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/*
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 * Remove a STUN transaction from a pair, and forget it
 * from the related component stun agent.
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 *
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 * @pair the pair the stun transaction should be removed from.
 * @stun the stun transaction to be removed.
 * @component the component containing the stun agent used to
 * forget the stun transaction.
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 */
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static void
priv_remove_stun_transaction (CandidateCheckPair *pair,
  StunTransaction *stun, NiceComponent *component)
{
  priv_forget_stun_transaction (stun, component);
  pair->stun_transactions = g_slist_remove (pair->stun_transactions, stun);
  priv_free_stun_transaction (stun);
}

/*
 * Remove all STUN transactions from a pair, and forget them
 * from the related component stun agent.
 *
 * @pair the pair the stun list should be cleared.
 * @component the component containing the stun agent used to
 * forget the stun transactions.
 */
static void
priv_free_all_stun_transactions (CandidateCheckPair *pair,
  NiceComponent *component)
{
  if (component)
    g_slist_foreach (pair->stun_transactions, priv_forget_stun_transaction, component);
  g_slist_free_full (pair->stun_transactions, priv_free_stun_transaction);
  pair->stun_transactions = NULL;
}

static void
candidate_check_pair_fail (NiceStream *stream, NiceAgent *agent, CandidateCheckPair *p)
{
  NiceComponent *component;

  component = nice_stream_find_component_by_id (stream, p->component_id);
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  SET_PAIR_STATE (agent, p, NICE_CHECK_FAILED);
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  priv_free_all_stun_transactions (p, component);
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}

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/*
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 * Helper function for connectivity check timer callback that
 * runs through the stream specific part of the state machine. 
 *
 * @param schedule if TRUE, schedule a new check
 *
 * @return will return FALSE when no more pending timers.
 */
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static gboolean priv_conn_check_tick_stream (NiceStream *stream, NiceAgent *agent)
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{
  gboolean keep_timer_going = FALSE;
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  GSList *i, *j;
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  CandidateCheckPair *pair;
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  unsigned int timeout;
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  GTimeVal now;

  g_get_current_time (&now);
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  /* step: process ongoing STUN transactions */
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  for (i = stream->conncheck_list; i ; i = i->next) {
    CandidateCheckPair *p = i->data;
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    gchar tmpbuf1[INET6_ADDRSTRLEN], tmpbuf2[INET6_ADDRSTRLEN];
    NiceComponent *component;
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    StunTransaction *stun;

    if (p->stun_transactions == NULL)
      continue;
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    if (!agent_find_component (agent, p->stream_id, p->component_id,
        NULL, &component))
      continue;

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    /* The first stun transaction of the list may eventually be
     * retransmitted, other stun transactions just have their
     * timer updated.
     */
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    j = p->stun_transactions->next;

    /* process all stun transactions except the first one */
    while (j) {
      StunTransaction *s = j->data;
      GSList *next = j->next;

      if (priv_timer_expired (&s->next_tick, &now))
        switch (stun_timer_refresh (&s->timer)) {
          case STUN_USAGE_TIMER_RETURN_TIMEOUT:
            priv_remove_stun_transaction (p, s, component);
            break;
          case STUN_USAGE_TIMER_RETURN_RETRANSMIT:
            timeout = stun_timer_remainder (&s->timer);
            s->next_tick = now;
            g_time_val_add (&s->next_tick, timeout * 1000);
            break;
          default:
            break;
      }
      j = next;
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    }

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    if (p->state != NICE_CHECK_IN_PROGRESS)
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      continue;
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    /* process the first stun transaction of the list */
    stun = p->stun_transactions->data;
    if (!priv_timer_expired (&stun->next_tick, &now))
      continue;
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    switch (stun_timer_refresh (&stun->timer)) {
      case STUN_USAGE_TIMER_RETURN_TIMEOUT:
timer_return_timeout:
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        /* case: error, abort processing */
        nice_address_to_string (&p->local->addr, tmpbuf1);
        nice_address_to_string (&p->remote->addr, tmpbuf2);
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        nice_debug ("Agent %p : Retransmissions failed, giving up on pair %p",
            agent, p);
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        nice_debug ("Agent %p : Failed pair is [%s]:%u --> [%s]:%u", agent,
            tmpbuf1, nice_address_get_port (&p->local->addr),
            tmpbuf2, nice_address_get_port (&p->remote->addr));
        candidate_check_pair_fail (stream, agent, p);
        priv_print_conn_check_lists (agent, G_STRFUNC,
            ", retransmission failed");

        /* perform a check if a transition state from connected to
         * ready can be performed. This may happen here, when the last
         * in-progress pair has expired its retransmission count
         * in priv_conn_check_tick_stream(), which is a condition to
         * make the transition connected to ready.
         */
        priv_update_check_list_state_for_ready (agent, stream, component);
        break;
      case STUN_USAGE_TIMER_RETURN_RETRANSMIT:
        /* case: retransmission stopped, due to the nomination of
         * a pair with a higher priority than this in-progress pair,
         * ICE spec, sect 8.1.2 "Updating States", item 2.2
         */
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        if (!p->retransmit)
          goto timer_return_timeout;
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        /* case: not ready, so schedule a new timeout */
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        timeout = stun_timer_remainder (&stun->timer);
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        nice_debug ("Agent %p :STUN transaction retransmitted on pair %p "
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            "(timer=%d/%d %d/%dms).",
            agent, p,
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            stun->timer.retransmissions, stun->timer.max_retransmissions,
            stun->timer.delay - timeout, stun->timer.delay);
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        agent_socket_send (p->sockptr, &p->remote->addr,
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            stun_message_length (&stun->message),
            (gchar *)stun->buffer);
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        /* note: convert from milli to microseconds for g_time_val_add() */
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        stun->next_tick = now;
        g_time_val_add (&stun->next_tick, timeout * 1000);
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        return TRUE;
      case STUN_USAGE_TIMER_RETURN_SUCCESS:
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        timeout = stun_timer_remainder (&stun->timer);
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        /* note: convert from milli to microseconds for g_time_val_add() */
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        stun->next_tick = now;
        g_time_val_add (&stun->next_tick, timeout * 1000);
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        keep_timer_going = TRUE;
        break;
      default:
        /* Nothing to do. */
        break;
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    }
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  }
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  /* step: perform an ordinary check, ICE spec, 5.8 "Scheduling Checks"
   * note: This code is executed when the triggered checks list is
   * empty, and when no STUN message has been sent (pacing constraint)
   */
  pair = priv_conn_check_find_next_waiting (stream->conncheck_list);
  if (pair) {
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    priv_print_conn_check_lists (agent, G_STRFUNC,
        ", got a pair in Waiting state");
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    priv_conn_check_initiate (agent, pair);
    return TRUE;
  }

  /* note: this is unclear in the ICE spec, but a check list in Frozen
   * state (where all pairs are in Frozen state) is not supposed to
   * change its state by an ordinary check, but only by the success of
   * checks in other check lists, in priv_conn_check_unfreeze_related().
   * The underlying idea is to concentrate the checks on a single check
   * list initially.
   */
  if (priv_is_checklist_frozen (stream))
    return keep_timer_going;

  /* step: ordinary check continued, if there's no pair in the waiting
   * state, pick a pair in the frozen state
   */
  pair = priv_conn_check_find_next_frozen (stream->conncheck_list);
  if (pair) {
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    priv_print_conn_check_lists (agent, G_STRFUNC,
        ", got a pair in Frozen state");
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    SET_PAIR_STATE (agent, pair, NICE_CHECK_WAITING);
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    priv_conn_check_initiate (agent, pair);
    return TRUE;
  }
  return keep_timer_going;
}

static gboolean
priv_conn_check_tick_stream_nominate (NiceStream *stream, NiceAgent *agent)
{
  gboolean keep_timer_going = FALSE;
  guint s_inprogress = 0;
  guint s_succeeded = 0;
  guint s_discovered = 0;
  guint s_nominated = 0;
  guint s_waiting_for_nomination = 0;
  guint s_valid = 0;
  guint frozen = 0;
  guint waiting = 0;
  GSList *i, *k;
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  for (i = stream->conncheck_list; i ; i = i->next) {
    CandidateCheckPair *p = i->data;
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    if (p->state == NICE_CHECK_FROZEN)
      ++frozen;
    else if (p->state == NICE_CHECK_IN_PROGRESS)
      ++s_inprogress;
    else if (p->state == NICE_CHECK_WAITING)
      ++waiting;
    else if (p->state == NICE_CHECK_SUCCEEDED)
      ++s_succeeded;
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    else if (p->state == NICE_CHECK_DISCOVERED)
      ++s_discovered;
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    if (p->valid)
      ++s_valid;
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    if ((p->state == NICE_CHECK_SUCCEEDED || p->state == NICE_CHECK_DISCOVERED)
        && p->nominated)
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      ++s_nominated;
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    else if ((p->state == NICE_CHECK_SUCCEEDED ||
            p->state == NICE_CHECK_DISCOVERED) && !p->nominated)
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      ++s_waiting_for_nomination;
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  }
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    /* note: keep the timer going as long as there is work to be done */
  if (s_inprogress)
    keep_timer_going = TRUE;
  
  if (s_nominated < stream->n_components &&
      s_waiting_for_nomination) {
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    if (NICE_AGENT_IS_COMPATIBLE_WITH_RFC5245_OR_OC2007R2 (agent)) {
      if (agent->nomination_mode == NICE_NOMINATION_MODE_REGULAR &&
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          agent->controlling_mode) {
#define NICE_MIN_NUMBER_OF_VALID_PAIRS 2
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        /* ICE 8.1.1.1 Regular nomination
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         * we choose to nominate the valid pair of a component if
         * - there is no pair left frozen, waiting or in-progress, or
         * - if there are at least two valid pairs, or
         * - if there is at least one valid pair of type HOST-HOST
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         *
         * This is the "stopping criterion" described in 8.1.1.1, and is
         * a "local optimization" between accumulating more valid pairs,
         * and limiting the time spent waiting for in-progress connections
         * checks until they finally fail.
         */
        GSList *component_item;

        for (component_item = stream->components; component_item;
             component_item = component_item->next) {
          NiceComponent *component = component_item->data;
          gboolean already_done = FALSE;
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          gboolean stopping_criterion = FALSE;
          guint p_valid = 0;
          guint p_frozen = 0;
          guint p_waiting = 0;
          guint p_inprogress = 0;
          guint p_host_host_valid = 0;
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          /* verify that the choice of the pair to be nominated
           * has not already been done
           */
          for (k = stream->conncheck_list; k ; k = k->next) {
            CandidateCheckPair *p = k->data;
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            if (p->component_id == component->id) {
              if (p->use_candidate_on_next_check)
                already_done = TRUE;
              if (p->state == NICE_CHECK_FROZEN)
                p_frozen++;
              else if (p->state == NICE_CHECK_WAITING)
                p_waiting++;
              else if (p->state == NICE_CHECK_IN_PROGRESS)
                p_inprogress++;
              if (p->valid)
                p_valid++;
              if (p->valid &&
                  p->local->type == NICE_CANDIDATE_TYPE_HOST &&
                  p->remote->type == NICE_CANDIDATE_TYPE_HOST)
                p_host_host_valid++;
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            }
          }

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          if (already_done)
            continue;

          stopping_criterion =
              (p_host_host_valid > 0 ||
               p_valid >= NICE_MIN_NUMBER_OF_VALID_PAIRS ||
               (p_waiting == 0 && p_inprogress == 0 && p_frozen == 0));

          if (!stopping_criterion)
            continue;

          /* when the stopping criterion is satisfied, we choose
           * a pair to be nominated in the list of valid pairs,
           * and add it to the triggered checks list
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           */
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          for (k = stream->conncheck_list; k ; k = k->next) {
            CandidateCheckPair *p = k->data;
            /* note: highest priority item selected (list always sorted) */
            if (p->component_id == component->id &&
                !p->nominated &&
                !p->use_candidate_on_next_check &&
                p->valid) {
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              /* According a ICE spec, sect 8.1.1.1.  "Regular
               * Nomination", we enqueue the check that produced this
               * valid pair. When this pair has been discovered, we want
               * to test its parent pair instead.
               */
              if (p->succeeded_pair != NULL) {
                g_assert (p->state == NICE_CHECK_DISCOVERED);
                p = p->succeeded_pair;
              }
              g_assert (p->state == NICE_CHECK_SUCCEEDED);
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              nice_debug ("Agent %p : restarting check of pair %p with "
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                  "USE-CANDIDATE attrib (regular nomination)", agent, p);
              p->use_candidate_on_next_check = TRUE;
              priv_add_pair_to_triggered_check_queue (agent, p);
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              keep_timer_going = TRUE;
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              break; /* move to the next component */
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            }
          }
        }
      }
    } else if (agent->controlling_mode) {
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      GSList *component_item;

      for (component_item = stream->components; component_item;
           component_item = component_item->next) {
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        NiceComponent *component = component_item->data;
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	for (k = stream->conncheck_list; k ; k = k->next) {
	  CandidateCheckPair *p = k->data;
	  /* note: highest priority item selected (list always sorted) */
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	  if (p->component_id == component->id &&
              (p->state == NICE_CHECK_SUCCEEDED ||
               p->state == NICE_CHECK_DISCOVERED)) {
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	    nice_debug ("Agent %p : restarting check of pair %p as the "
                "nominated pair.", agent, p);
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	    p->nominated = TRUE;
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            priv_update_selected_pair (agent, component, p);
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            priv_add_pair_to_triggered_check_queue (agent, p);
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            keep_timer_going = TRUE;
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	    break; /* move to the next component */
	  }
	}
      }
    }
  }
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  if (stream->tick_counter++ % 50 == 0)
    nice_debug ("Agent %p : stream %u: timer tick #%u: %u frozen, %u in-progress, "
        "%u waiting, %u succeeded, %u discovered, %u nominated, "
        "%u waiting-for-nom, %u valid.", agent, stream->id,
        stream->tick_counter, frozen, s_inprogress, waiting, s_succeeded,
        s_discovered, s_nominated, s_waiting_for_nomination, s_valid);
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  return keep_timer_going;

}

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static void
conn_check_stop (NiceAgent *agent)
{
  if (agent->conncheck_timer_source == NULL)
    return;

  g_source_destroy (agent->conncheck_timer_source);
  g_source_unref (agent->conncheck_timer_source);
  agent->conncheck_timer_source = NULL;
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  agent->conncheck_timer_grace_period = 0;
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}

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/*
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 * Timer callback that handles initiating and managing connectivity
 * checks (paced by the Ta timer).
 *
 * This function is designed for the g_timeout_add() interface.
 *
 * @return will return FALSE when no more pending timers.
 */
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static gboolean priv_conn_check_tick_agent_locked (NiceAgent *agent,
    gpointer user_data)
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{
  CandidateCheckPair *pair = NULL;
  gboolean keep_timer_going = FALSE;
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  GSList *i, *j;
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  /* configure the initial state of the check lists of the agent
   * as described in ICE spec, 5.7.4
   *
   * if all pairs in all check lists are in frozen state, then
   * we are in the initial state (5.7.4, point 1.)
   */
  if (priv_number_of_active_check_lists (agent) == 0) {
    /* set some pairs of the first stream in the waiting state
     * ICE spec, 5.7.4, point 2.
     *
     * note: we adapt the ICE spec here, by selecting the first
     * frozen check list, which is not necessarily the check
     * list of the first stream (the first stream may be completed)
     */
    NiceStream *stream = priv_find_first_frozen_check_list (agent);
    if (stream)
      priv_conn_check_unfreeze_next (agent, stream);
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  }
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  /* step: perform a test from the triggered checks list,
   * ICE spec, 5.8 "Scheduling Checks"
   */
  pair = priv_get_pair_from_triggered_check_queue (agent);

1075
  if (pair) {
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    priv_print_conn_check_lists (agent, G_STRFUNC,
        ", got a pair from triggered check list");
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    if (conn_check_send (agent, pair)) {
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      SET_PAIR_STATE (agent, pair, NICE_CHECK_FAILED);
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      return FALSE;
    }
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    return TRUE;
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  }

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  /* step: process ongoing STUN transactions and
   * perform an ordinary check, ICE spec, 5.8, "Scheduling Checks"
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   */
  for (i = agent->streams; i ; i = i->next) {
    NiceStream *stream = i->data;
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    if (priv_conn_check_tick_stream (stream, agent))
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      keep_timer_going = TRUE;
    if (priv_conn_check_tick_stream_nominate (stream, agent))
      keep_timer_going = TRUE;
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  }
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  /* step: if no work left and a conncheck list of a stream is still
   * frozen, set the pairs to waiting, according to ICE SPEC, sect
   * 7.1.3.3.  "Check List and Timer State Updates"
   */
  if (!keep_timer_going) {
    for (i = agent->streams; i ; i = i->next) {
      NiceStream *stream = i->data;
      if (priv_is_checklist_frozen (stream)) {
        nice_debug ("Agent %p : stream %d conncheck list is still "
            "frozen, while other lists are completed. Unfreeze it.",
            agent, stream->id);
        keep_timer_going = priv_conn_check_unfreeze_next (agent, stream);
      }
    }
  }

  /* note: we provide a grace period before declaring a component as
   * failed. Components marked connected, and then ready follow another
   * code path, and are not concerned by this grace period.
   */
  if (!keep_timer_going && agent->conncheck_timer_grace_period == 0)
    nice_debug ("Agent %p : waiting %d msecs before checking "
        "for failed components.", agent, NICE_AGENT_MAX_TIMER_GRACE_PERIOD);

  if (keep_timer_going)
    agent->conncheck_timer_grace_period = 0;
  else
    agent->conncheck_timer_grace_period += agent->timer_ta;

1125
  /* step: stop timer if no work left */
1126 1127 1128
  if (!keep_timer_going &&
      agent->conncheck_timer_grace_period >= NICE_AGENT_MAX_TIMER_GRACE_PERIOD) {
    nice_debug ("Agent %p : checking for failed components now.", agent);
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    for (i = agent->streams; i; i = i->next) {
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      NiceStream *stream = i->data;
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      priv_update_check_list_failed_components (agent, stream);
1132
      for (j = stream->components; j; j = j->next) {
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        NiceComponent *component = j->data;
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        priv_update_check_list_state_for_ready (agent, stream, component);
      }
1136
    }
1137

1138
    nice_debug ("Agent %p : %s: stopping conncheck timer", agent, G_STRFUNC);
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    priv_print_conn_check_lists (agent, G_STRFUNC,
        ", conncheck timer stopped");

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    /* Stopping the timer so destroy the source.. this will allow
       the timer to be reset if we get a set_remote_candidates after this
       point */
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    conn_check_stop (agent);
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    /* XXX: what to signal, is all processing now really done? */
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    nice_debug ("Agent %p : changing conncheck state to COMPLETED.", agent);
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    return FALSE;
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  }

1152
  return TRUE;
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}

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static gboolean priv_conn_keepalive_retransmissions_tick_agent_locked (
    NiceAgent *agent, gpointer pointer)
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{
  CandidatePair *pair = (CandidatePair *) pointer;

  g_source_destroy (pair->keepalive.tick_source);
  g_source_unref (pair->keepalive.tick_source);
  pair->keepalive.tick_source = NULL;

  switch (stun_timer_refresh (&pair->keepalive.timer)) {
    case STUN_USAGE_TIMER_RETURN_TIMEOUT:
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      {
        /* Time out */
        StunTransactionId id;
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        NiceComponent *component;
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        if (!agent_find_component (agent,
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                pair->keepalive.stream_id, pair->keepalive.component_id,
                NULL, &component)) {
          nice_debug ("Could not find stream or component in"
              " priv_conn_keepalive_retransmissions_tick");
          return FALSE;
        }
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        stun_message_id (&pair->keepalive.stun_message, id);
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        stun_agent_forget_transaction (&component->stun_agent, id);
1181
        pair->keepalive.stun_message.buffer = NULL;
1182

1183
        if (agent->media_after_tick) {
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          nice_debug ("Agent %p : Keepalive conncheck timed out!! "
              "but media was received. Suspecting keepalive lost because of "
1186
              "network bottleneck", agent);
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        } else {
          nice_debug ("Agent %p : Keepalive conncheck timed out!! "
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              "peer probably lost connection", agent);
          agent_signal_component_state_change (agent,
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              pair->keepalive.stream_id, pair->keepalive.component_id,
              NICE_COMPONENT_STATE_FAILED);
        }
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        break;
      }
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    case STUN_USAGE_TIMER_RETURN_RETRANSMIT:
      /* Retransmit */
1198
      agent_socket_send (pair->local->sockptr, &pair->remote->addr,
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          stun_message_length (&pair->keepalive.stun_message),
          (gchar *)pair->keepalive.stun_buffer);

1202
      nice_debug ("Agent %p : Retransmitting keepalive conncheck",
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          agent);
      agent_timeout_add_with_context (agent,
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          &pair->keepalive.tick_source,
          "Pair keepalive", stun_timer_remainder (&pair->keepalive.timer),
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          priv_conn_keepalive_retransmissions_tick_agent_locked, pair);
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      break;
    case STUN_USAGE_TIMER_RETURN_SUCCESS:
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      agent_timeout_add_with_context (agent,
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          &pair->keepalive.tick_source,
          "Pair keepalive", stun_timer_remainder (&pair->keepalive.timer),
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          priv_conn_keepalive_retransmissions_tick_agent_locked, pair);
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      break;
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    default:
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      g_assert_not_reached();
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      break;
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  }

  return FALSE;
}

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static guint32 peer_reflexive_candidate_priority (NiceAgent *agent,
    NiceCandidate *local_candidate)
{
  NiceCandidate *candidate_priority =
      nice_candidate_new (NICE_CANDIDATE_TYPE_PEER_REFLEXIVE);
  guint32 priority;

  candidate_priority->transport = local_candidate->transport;
  candidate_priority->component_id = local_candidate->component_id;
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  candidate_priority->base_addr = local_candidate->addr;
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  if (agent->compatibility == NICE_COMPATIBILITY_GOOGLE) {
    priority = nice_candidate_jingle_priority (candidate_priority);
  } else if (agent->compatibility == NICE_COMPATIBILITY_MSN ||
             agent->compatibility == NICE_COMPATIBILITY_OC2007) {
    priority = nice_candidate_msn_priority (candidate_priority);
  } else if (agent->compatibility == NICE_COMPATIBILITY_OC2007R2) {
    priority = nice_candidate_ms_ice_priority (candidate_priority,
        agent->reliable, FALSE);
  } else {
    priority = nice_candidate_ice_priority (candidate_priority,
        agent->reliable, FALSE);
  }
  nice_candidate_free (candidate_priority);

  return priority;
}

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static void ms_ice2_legacy_conncheck_send(StunMessage *msg, NiceSocket *sock,
    const NiceAddress *remote_addr)
{
  uint32_t *fingerprint_attr;
  uint32_t fingerprint_orig;
  uint16_t fingerprint_len;
  size_t buffer_len;

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  if (msg->agent->ms_ice2_send_legacy_connchecks == FALSE) {
    return;
  }

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  fingerprint_attr = (uint32_t *)stun_message_find (msg,
      STUN_ATTRIBUTE_FINGERPRINT, &fingerprint_len);

  if (fingerprint_attr == NULL) {
    nice_debug ("FINGERPRINT not found.");
    return;
  }

  if (fingerprint_len != sizeof (fingerprint_orig)) {
    nice_debug ("Unexpected FINGERPRINT length %u.", fingerprint_len);
    return;
  }

  memcpy (&fingerprint_orig, fingerprint_attr, sizeof (fingerprint_orig));
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  buffer_len = stun_message_length (msg);

  *fingerprint_attr = stun_fingerprint (msg->buffer, buffer_len, TRUE);

  agent_socket_send (sock, remote_addr, buffer_len, (gchar *)msg->buffer);

  memcpy (fingerprint_attr, &fingerprint_orig, sizeof (fingerprint_orig));
}
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/*
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 * Timer callback that handles initiating and managing connectivity
 * checks (paced by the Ta timer).
 *
 * This function is designed for the g_timeout_add() interface.
 *
 * @return will return FALSE when no more pending timers.
 */
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static gboolean priv_conn_keepalive_tick_unlocked (NiceAgent *agent)
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{
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  GSList *i, *j, *k;
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  int errors = 0;
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  gboolean ret = FALSE;
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  size_t buf_len = 0;
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  /* case 1: session established and media flowing
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   *         (ref ICE sect 10 "Keepalives" ID-19)  */
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  for (i = agent->streams; i; i = i->next) {
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    NiceStream *stream = i->data;
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    for (j = stream->components; j; j = j->next) {
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      NiceComponent *component = j->data;
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      if (component->selected_pair.local != NULL) {
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	CandidatePair *p = &component->selected_pair;
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        /* Disable keepalive checks on TCP candidates unless explicitly enabled */
        if (p->local->transport != NICE_CANDIDATE_TRANSPORT_UDP &&
            !agent->keepalive_conncheck)
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          continue;

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        if (agent->compatibility == NICE_COMPATIBILITY_GOOGLE ||
            agent->keepalive_conncheck) {
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          uint8_t uname[NICE_STREAM_MAX_UNAME];
          size_t uname_len =
              priv_create_username (agent, agent_find_stream (agent, stream->id),
                  component->id, p->remote, p->local, uname, sizeof (uname),
                  FALSE);
          uint8_t *password = NULL;
          size_t password_len = priv_get_password (agent,
              agent_find_stream (agent, stream->id), p->remote, &password);

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          if (p->keepalive.stun_message.buffer != NULL) {
            nice_debug ("Agent %p: Keepalive for s%u:c%u still"
                " retransmitting, not restarting", agent, stream->id,
                component->id);
            continue;
          }

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          if (nice_debug_is_enabled ()) {
            gchar tmpbuf[INET6_ADDRSTRLEN];
            nice_address_to_string (&p->remote->addr, tmpbuf);
            nice_debug ("Agent %p : Keepalive STUN-CC REQ to '%s:%u', "
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                "(c-id:%u), username='%.*s' (%" G_GSIZE_FORMAT "), "
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                "password='%.*s' (%" G_GSIZE_FORMAT "), priority=%u.", agent,
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                tmpbuf, nice_address_get_port (&p->remote->addr),
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                component->id, (int) uname_len, uname, uname_len,
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                (int) password_len, password, password_len,
                p->prflx_priority);
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          }
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          if (uname_len > 0) {
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            buf_len = stun_usage_ice_conncheck_create (&component->stun_agent,
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                &p->keepalive.stun_message, p->keepalive.stun_buffer,
                sizeof(p->keepalive.stun_buffer),
                uname, uname_len, password, password_len,
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                agent->controlling_mode, agent->controlling_mode,
                p->prflx_priority,
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                agent->tie_breaker,
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                NULL,
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                agent_to_ice_compatibility (agent));

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            nice_debug ("Agent %p: conncheck created %zd - %p",
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                agent, buf_len, p->keepalive.stun_message.buffer);

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            if (buf_len > 0) {
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              stun_timer_start (&p->keepalive.timer,
                  agent->stun_initial_timeout,
                  agent->stun_max_retransmissions);
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              agent->media_after_tick = FALSE;

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              /* send the conncheck */
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              agent_socket_send (p->local->sockptr, &p->remote->addr,
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                  buf_len, (gchar *)p->keepalive.stun_buffer);

              p->keepalive.stream_id = stream->id;
              p->keepalive.component_id = component->id;

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              agent_timeout_add_with_context (agent,
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                  &p->keepalive.tick_source, "Pair keepalive",
                  stun_timer_remainder (&p->keepalive.timer),