component.c 30.9 KB
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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:
 *   Dafydd Harries, Collabora Ltd.
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 *   Youness Alaoui, Collabora Ltd.
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 *   Kai Vehmanen, Nokia
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 *
 * 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 component.c
 * @brief ICE component functions
 */

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

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#include <string.h>

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#include "debug.h"

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#include "component.h"
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#include "agent-priv.h"
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static void
component_schedule_io_callback (Component *component);
static void
component_deschedule_io_callback (Component *component);


/* Must *not* take the agent lock, since it’s called from within
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 * component_set_io_context(), which holds the Component’s I/O lock. */
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static void
socket_source_attach (SocketSource *socket_source, GMainContext *context)
{
  GSource *source;

  /* Create a source. */
  source = g_socket_create_source (socket_source->socket->fileno,
      G_IO_IN, NULL);
  g_source_set_callback (source, (GSourceFunc) component_io_cb,
      socket_source, NULL);

  /* Add the source. */
  nice_debug ("Attaching source %p (socket %p, FD %d) to context %p", source,
      socket_source->socket, g_socket_get_fd (socket_source->socket->fileno),
      context);

  g_assert (socket_source->source == NULL);
  socket_source->source = source;
  g_source_attach (source, context);
}

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static void
socket_source_detach (SocketSource *source)
{
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  nice_debug ("Detaching source %p (socket %p, FD %d) from context %p",
      source->source, source->socket,
      (source->socket->fileno != NULL) ?
          g_socket_get_fd (source->socket->fileno) : 0,
      (source->source != NULL) ? g_source_get_context (source->source) : 0);

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  if (source->source != NULL) {
    g_source_destroy (source->source);
    g_source_unref (source->source);
  }
  source->source = NULL;
}

static void
socket_source_free (SocketSource *source)
{
  socket_source_detach (source);
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  nice_socket_free (source->socket);
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  g_slice_free (SocketSource, source);
}

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Component *
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component_new (guint id, NiceAgent *agent, Stream *stream)
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{
  Component *component;
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  GSource *src;
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  component = g_slice_new0 (Component);
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  component->id = id;
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  component->state = NICE_COMPONENT_STATE_DISCONNECTED;
  component->restart_candidate = NULL;
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  component->tcp = NULL;
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  component->agent = agent;
  component->stream = stream;
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  g_mutex_init (&component->io_mutex);
  g_queue_init (&component->pending_io_messages);
  component->io_callback_id = 0;

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  component->own_ctx = g_main_context_new ();
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  component->stop_cancellable = g_cancellable_new ();
  src = g_cancellable_source_new (component->stop_cancellable);
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  g_source_set_dummy_callback (src);
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  g_source_attach (src, component->own_ctx);
  g_source_unref (src);
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  component->ctx = g_main_context_ref (component->own_ctx);

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  /* Start off with a fresh main context and all I/O paused. This
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   * will be updated when nice_agent_attach_recv() or nice_agent_recv_messages()
   * are called. */
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  component_set_io_context (component, NULL);
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  component_set_io_callback (component, NULL, NULL, NULL, 0, NULL);
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  g_queue_init (&component->queued_tcp_packets);

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  return component;
}

void
component_free (Component *cmp)
{
  GSList *i;
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  GList *item;
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  IOCallbackData *data;
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  GOutputVector *vec;
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  for (i = cmp->local_candidates; i; i = i->next) {
    NiceCandidate *candidate = i->data;
    nice_candidate_free (candidate);
  }
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  for (i = cmp->remote_candidates; i; i = i->next) {
    NiceCandidate *candidate = i->data;
    nice_candidate_free (candidate);
  }
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  if (cmp->restart_candidate)
    nice_candidate_free (cmp->restart_candidate),
      cmp->restart_candidate = NULL;

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  for (i = cmp->incoming_checks; i; i = i->next) {
    IncomingCheck *icheck = i->data;
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    g_free (icheck->username);
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    g_slice_free (IncomingCheck, icheck);
  }
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  g_slist_free (cmp->local_candidates);
  g_slist_free (cmp->remote_candidates);
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  component_free_socket_sources (cmp);
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  g_slist_free (cmp->incoming_checks);
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  for (item = cmp->turn_servers; item; item = g_list_next (item)) {
    TurnServer *turn = item->data;
    g_free (turn->username);
    g_free (turn->password);
    g_slice_free (TurnServer, turn);
  }
  g_list_free (cmp->turn_servers);
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  if (cmp->selected_pair.keepalive.tick_source != NULL) {
    g_source_destroy (cmp->selected_pair.keepalive.tick_source);
    g_source_unref (cmp->selected_pair.keepalive.tick_source);
    cmp->selected_pair.keepalive.tick_source = NULL;
  }

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  if (cmp->tcp_clock) {
    g_source_destroy (cmp->tcp_clock);
    g_source_unref (cmp->tcp_clock);
    cmp->tcp_clock = NULL;
  }
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  if (cmp->tcp_writable_cancellable) {
    g_cancellable_cancel (cmp->tcp_writable_cancellable);
    g_clear_object (&cmp->tcp_writable_cancellable);
  }
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  if (cmp->tcp) {
    pseudo_tcp_socket_close (cmp->tcp, TRUE);
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    g_clear_object(&cmp->tcp);
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  }

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  while ((data = g_queue_pop_head (&cmp->pending_io_messages)) != NULL)
    io_callback_data_free (data);

  component_deschedule_io_callback (cmp);

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  g_cancellable_cancel (cmp->stop_cancellable);
  g_clear_object (&cmp->stop_cancellable);

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  if (cmp->ctx != NULL) {
    g_main_context_unref (cmp->ctx);
    cmp->ctx = NULL;
  }

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  g_main_context_unref (cmp->own_ctx);

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  while ((vec = g_queue_pop_head (&cmp->queued_tcp_packets)) != NULL) {
    g_free ((gpointer) vec->buffer);
    g_slice_free (GOutputVector, vec);
  }

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  g_clear_object (&cmp->iostream);

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  g_mutex_clear (&cmp->io_mutex);

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  g_slice_free (Component, cmp);
}

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/*
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 * Finds a candidate pair that has matching foundation ids.
 *
 * @return TRUE if pair found, pointer to pair stored at 'pair'
 */
gboolean
component_find_pair (Component *cmp, NiceAgent *agent, const gchar *lfoundation, const gchar *rfoundation, CandidatePair *pair)
{
  GSList *i;
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  CandidatePair result;

  memset (&result, 0, sizeof(result));
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  for (i = cmp->local_candidates; i; i = i->next) {
    NiceCandidate *candidate = i->data;
    if (strncmp (candidate->foundation, lfoundation, NICE_CANDIDATE_MAX_FOUNDATION) == 0) {
      result.local = candidate;
      break;
    }
  }

  for (i = cmp->remote_candidates; i; i = i->next) {
    NiceCandidate *candidate = i->data;
    if (strncmp (candidate->foundation, rfoundation, NICE_CANDIDATE_MAX_FOUNDATION) == 0) {
      result.remote = candidate;
      break;
    }
  }

  if (result.local && result.remote) {
    result.priority = agent_candidate_pair_priority (agent, result.local, result.remote);
    if (pair)
      *pair = result;
    return TRUE;
  }

  return FALSE;
}

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/*
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 * Resets the component state to that of a ICE restarted
 * session.
 */
gboolean
component_restart (Component *cmp)
{
  GSList *i;

  for (i = cmp->remote_candidates; i; i = i->next) {
    NiceCandidate *candidate = i->data;

    /* note: do not remove the remote candidate that is
     *       currently part of the 'selected pair', see ICE
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     *       9.1.1.1. "ICE Restarts" (ID-19) */
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    if (candidate == cmp->selected_pair.remote) {
      if (cmp->restart_candidate)
	nice_candidate_free (cmp->restart_candidate);
      cmp->restart_candidate = candidate;
    }
    else 
      nice_candidate_free (candidate);
  }
  g_slist_free (cmp->remote_candidates),
    cmp->remote_candidates = NULL;

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  for (i = cmp->incoming_checks; i; i = i->next) {
    IncomingCheck *icheck = i->data;
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    g_free (icheck->username);
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    g_slice_free (IncomingCheck, icheck);
  }
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  g_slist_free (cmp->incoming_checks);
  cmp->incoming_checks = NULL;
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  /* note: component state managed by agent */

  return TRUE;
}
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/*
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 * Changes the selected pair for the component to 'pair'. Does not
 * emit the "selected-pair-changed" signal.
 */ 
void component_update_selected_pair (Component *component, const CandidatePair *pair)
{
  g_assert (component);
  g_assert (pair);
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  nice_debug ("setting SELECTED PAIR for component %u: %s:%s (prio:%"
      G_GUINT64_FORMAT ").", component->id, pair->local->foundation,
      pair->remote->foundation, pair->priority);
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  if (component->selected_pair.keepalive.tick_source != NULL) {
    g_source_destroy (component->selected_pair.keepalive.tick_source);
    g_source_unref (component->selected_pair.keepalive.tick_source);
    component->selected_pair.keepalive.tick_source = NULL;
  }

  memset (&component->selected_pair, 0, sizeof(CandidatePair));

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  component->selected_pair.local = pair->local;
  component->selected_pair.remote = pair->remote;
  component->selected_pair.priority = pair->priority;
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}
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/*
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 * Finds a remote candidate with matching address and 
 * transport.
 *
 * @return pointer to candidate or NULL if not found
 */
NiceCandidate *
component_find_remote_candidate (const Component *component, const NiceAddress *addr, NiceCandidateTransport transport)
{
  GSList *i;

  for (i = component->remote_candidates; i; i = i->next) {
    NiceCandidate *candidate = i->data;

    if (nice_address_equal(&candidate->addr, addr) &&
	candidate->transport == transport)
      return candidate;

  }
  
  return NULL;
}
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/*
 * Sets the desired remote candidate as the selected pair
 *
 * It will start sending on the highest priority pair available with
 * this candidate.
 */

NiceCandidate *
component_set_selected_remote_candidate (NiceAgent *agent, Component *component,
    NiceCandidate *candidate)
{
  NiceCandidate *local = NULL;
  NiceCandidate *remote = NULL;
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  guint64 priority = 0;
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  GSList *item = NULL;

  for (item = component->local_candidates; item; item = g_slist_next (item)) {
    NiceCandidate *tmp = item->data;
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    guint64 tmp_prio = 0;
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    if (tmp->transport != candidate->transport ||
	tmp->addr.s.addr.sa_family != candidate->addr.s.addr.sa_family ||
        tmp->type != NICE_CANDIDATE_TYPE_HOST)
      continue;

    tmp_prio = agent_candidate_pair_priority (agent, tmp, candidate);

    if (tmp_prio > priority) {
      priority = tmp_prio;
      local = tmp;
    }
  }

  if (local == NULL)
    return NULL;

  remote = component_find_remote_candidate (component, &candidate->addr,
      candidate->transport);

  if (!remote) {
    remote = nice_candidate_copy (candidate);
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    component->remote_candidates = g_slist_append (component->remote_candidates,
        remote);
    agent_signal_new_remote_candidate (agent, remote);
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  }

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  if (component->selected_pair.keepalive.tick_source != NULL) {
    g_source_destroy (component->selected_pair.keepalive.tick_source);
    g_source_unref (component->selected_pair.keepalive.tick_source);
    component->selected_pair.keepalive.tick_source = NULL;
  }

  memset (&component->selected_pair, 0, sizeof(CandidatePair));
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  component->selected_pair.local = local;
  component->selected_pair.remote = remote;
  component->selected_pair.priority = priority;

  return local;
}
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static gint
_find_socket_source (gconstpointer a, gconstpointer b)
{
  const SocketSource *source_a = a;
  const NiceSocket *socket_b = b;

  return (source_a->socket == socket_b) ? 0 : 1;
}

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/* This takes ownership of the socket.
 * It creates and attaches a source to the component’s context. */
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void
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component_attach_socket (Component *component, NiceSocket *socket)
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{
  GSList *l;
  SocketSource *socket_source;

  g_assert (component != NULL);
  g_assert (socket != NULL);

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  g_assert (component->ctx != NULL);

  /* Find an existing SocketSource in the component which contains @socket, or
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   * create a new one.
   *
   * In order for socket_sources_age to work properly, socket_sources must only
   * grow monotonically, or be entirely cleared. i.e. New SocketSources must be
   * prepended to socket_sources, and all other existing SocketSource must be
   * left untouched; *or* the whole of socket_sources must be cleared. If
   * socket_sources is cleared, age is reset to 0 and *must not* be incremented
   * again or the new sockets will not be picked up by ComponentSocket. This is
   * guaranteed by the fact that socket_sources is only cleared on disconnection
   * or discovery failure, which are both unrecoverable states.
   *
   * An empty socket_sources corresponds to age 0. */
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  l = g_slist_find_custom (component->socket_sources, socket,
          _find_socket_source);
  if (l != NULL) {
    socket_source = l->data;
  } else {
    socket_source = g_slice_new0 (SocketSource);
    socket_source->socket = socket;
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    socket_source->component = component;
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    component->socket_sources =
        g_slist_prepend (component->socket_sources, socket_source);
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    component->socket_sources_age++;
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  }

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  /* Create and attach a source */
  nice_debug ("Component %p (agent %p): Attach source (stream %u).",
      component, component->agent, component->stream->id);
  socket_source_attach (socket_source, component->ctx);
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}

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/* Reattaches socket handles of @component to the main context.
 *
 * Must *not* take the agent lock, since it’s called from within
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 * component_set_io_context(), which holds the Component’s I/O lock. */
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static void
component_reattach_all_sockets (Component *component)
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{
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  GSList *i;
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  for (i = component->socket_sources; i != NULL; i = i->next) {
    SocketSource *socket_source = i->data;
    nice_debug ("Reattach source %p.", socket_source->source);
    socket_source_detach (socket_source);
    socket_source_attach (socket_source, component->ctx);
  }
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}

/**
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 * component_detach_socket:
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 * @component: a #Component
 * @socket: the socket to detach the source for
 *
 * Detach the #GSource for the single specified @socket. Leave the socket itself
 * untouched.
 *
 * If the @socket doesn’t exist in this @component, do nothing.
 */
void
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component_detach_socket (Component *component, NiceSocket *socket)
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{
  GSList *l;
  SocketSource *socket_source;

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  nice_debug ("Detach socket %p.", socket);

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  /* Find the SocketSource for the socket. */
  l = g_slist_find_custom (component->socket_sources, socket,
          _find_socket_source);
  if (l == NULL)
    return;

  /* Detach the source. */
  socket_source = l->data;
  socket_source_detach (socket_source);
}

/*
 * Detaches socket handles of @component from the main context. Leaves the
 * sockets themselves untouched.
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 *
 * Must *not* take the agent lock, since it’s called from within
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 * component_set_io_context(), which holds the Component’s I/O lock.
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 */
void
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component_detach_all_sockets (Component *component)
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{
  GSList *i;

  for (i = component->socket_sources; i != NULL; i = i->next) {
    SocketSource *socket_source = i->data;
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    nice_debug ("Detach source %p, socket %p.", socket_source->source,
        socket_source->socket);
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    socket_source_detach (socket_source);
  }
}

void
component_free_socket_sources (Component *component)
{
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  nice_debug ("Free socket sources for component %p.", component);

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  g_slist_free_full (component->socket_sources,
      (GDestroyNotify) socket_source_free);
  component->socket_sources = NULL;
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  component->socket_sources_age = 0;
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}
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GMainContext *
component_dup_io_context (Component *component)
{
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  return g_main_context_ref (component->own_ctx);
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}

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/* If @context is %NULL, it's own context is used, so component->ctx is always
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 * guaranteed to be non-%NULL. */
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void
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component_set_io_context (Component *component, GMainContext *context)
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{
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  g_mutex_lock (&component->io_mutex);

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  if (component->ctx != context) {
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    if (context == NULL)
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      context = g_main_context_ref (component->own_ctx);
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    else
      g_main_context_ref (context);

    component_detach_all_sockets (component);
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    g_main_context_unref (component->ctx);

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    component->ctx = context;
    component_reattach_all_sockets (component);
  }
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  g_mutex_unlock (&component->io_mutex);
}
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/* (func, user_data) and (recv_messages, n_recv_messages) are mutually
 * exclusive. At most one of the two must be specified; if both are NULL, the
 * Component will not receive any data (i.e. reception is paused).
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 *
 * Apart from during setup, this must always be called with the agent lock held,
 * and the I/O lock released (because it takes the I/O lock itself). Requiring
 * the agent lock to be held means it can’t be called between a packet being
 * dequeued from the kernel buffers in agent.c, and an I/O callback being
 * emitted for it (which could cause data loss if the I/O callback function was
 * unset in that time). */
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void
component_set_io_callback (Component *component,
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    NiceAgentRecvFunc func, gpointer user_data,
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    NiceInputMessage *recv_messages, guint n_recv_messages,
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    GError **error)
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{
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  g_assert (func == NULL || recv_messages == NULL);
  g_assert (n_recv_messages == 0 || recv_messages != NULL);
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  g_assert (error == NULL || *error == NULL);

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  g_mutex_lock (&component->io_mutex);
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  if (func != NULL) {
    component->io_callback = func;
    component->io_user_data = user_data;
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    component->recv_messages = NULL;
    component->n_recv_messages = 0;
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    component_schedule_io_callback (component);
  } else {
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    component->io_callback = NULL;
    component->io_user_data = NULL;
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    component->recv_messages = recv_messages;
    component->n_recv_messages = n_recv_messages;
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    component_deschedule_io_callback (component);
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  }
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  nice_input_message_iter_reset (&component->recv_messages_iter);
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  component->recv_buf_error = error;

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  g_mutex_unlock (&component->io_mutex);
}

gboolean
component_has_io_callback (Component *component)
{
  gboolean has_io_callback;

  g_mutex_lock (&component->io_mutex);
  has_io_callback = (component->io_callback != NULL);
  g_mutex_unlock (&component->io_mutex);

  return has_io_callback;
}

IOCallbackData *
io_callback_data_new (const guint8 *buf, gsize buf_len)
{
  IOCallbackData *data;

  data = g_slice_new0 (IOCallbackData);
  data->buf = g_memdup (buf, buf_len);
  data->buf_len = buf_len;
  data->offset = 0;

  return data;
}

void
io_callback_data_free (IOCallbackData *data)
{
  g_free (data->buf);
  g_slice_free (IOCallbackData, data);
}

/* This is called with the global agent lock released. It does not take that
 * lock, but does take the io_mutex. */
static gboolean
emit_io_callback_cb (gpointer user_data)
{
  Component *component = user_data;
  IOCallbackData *data;
  NiceAgentRecvFunc io_callback;
  gpointer io_user_data;
  guint stream_id, component_id;
  NiceAgent *agent;

  agent = component->agent;
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  g_object_ref (agent);
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  stream_id = component->stream->id;
  component_id = component->id;

  g_mutex_lock (&component->io_mutex);

  /* The members of Component are guaranteed not to have changed since this
   * GSource was attached in component_emit_io_callback(). The Component’s agent
   * and stream are immutable after construction, as are the stream and
   * component IDs. The callback and its user data may have changed, but are
   * guaranteed to be non-%NULL at the start as the idle source is removed when
   * the callback is set to %NULL. They may become %NULL during the io_callback,
   * so must be re-checked every loop iteration. The data buffer is copied into
   * the #IOCallbackData closure.
   *
   * If the component is destroyed (which happens if the agent or stream are
   * destroyed) between attaching the GSource and firing it, the GSource is
   * detached in component_free() and this callback is never invoked. If the
   * agent is destroyed during an io_callback, its weak pointer will be
   * nullified. Similarly, the Component needs to be re-queried for after every
   * iteration, just in case the client has removed the stream in the
   * callback. */
  while (TRUE) {
    io_callback = component->io_callback;
    io_user_data = component->io_user_data;
    data = g_queue_peek_head (&component->pending_io_messages);

    if (data == NULL || io_callback == NULL)
      break;

    g_mutex_unlock (&component->io_mutex);

    io_callback (agent, stream_id, component_id,
        data->buf_len - data->offset, (gchar *) data->buf + data->offset,
        io_user_data);

    /* Check for the user destroying things underneath our feet. */
711
    if (!agent_find_component (agent, stream_id, component_id,
712 713
            NULL, &component)) {
      nice_debug ("%s: Agent or component destroyed.", G_STRFUNC);
714
      goto done;
715 716 717 718 719 720 721 722 723 724 725
    }

    g_queue_pop_head (&component->pending_io_messages);
    io_callback_data_free (data);

    g_mutex_lock (&component->io_mutex);
  }

  component->io_callback_id = 0;
  g_mutex_unlock (&component->io_mutex);

726 727
 done:
  g_object_unref (agent);
728 729

  return G_SOURCE_REMOVE;
730 731 732 733
}

/* This must be called with the agent lock *held*. */
void
734 735
component_emit_io_callback (Component *component,
    const guint8 *buf, gsize buf_len)
736
{
737 738
  NiceAgent *agent;
  guint stream_id, component_id;
739 740 741 742 743 744 745
  NiceAgentRecvFunc io_callback;
  gpointer io_user_data;

  g_assert (component != NULL);
  g_assert (buf != NULL);
  g_assert (buf_len > 0);

746 747 748
  agent = component->agent;
  stream_id = component->stream->id;
  component_id = component->id;
749 750

  g_mutex_lock (&component->io_mutex);
751 752
  io_callback = component->io_callback;
  io_user_data = component->io_user_data;
753 754 755 756 757 758
  g_mutex_unlock (&component->io_mutex);

  /* Allow this to be called with a NULL io_callback, since the caller can’t
   * lock io_mutex to check beforehand. */
  if (io_callback == NULL)
    return;
759

760 761 762 763 764
  g_assert (NICE_IS_AGENT (agent));
  g_assert (stream_id > 0);
  g_assert (component_id > 0);
  g_assert (io_callback != NULL);

765 766 767 768
  /* Only allocate a closure if the callback is being deferred to an idle
   * handler. */
  if (g_main_context_is_owner (component->ctx)) {
    /* Thread owns the main context, so invoke the callback directly. */
769
    agent_unlock_and_emit (agent);
770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796
    io_callback (agent, stream_id,
        component_id, buf_len, (gchar *) buf, io_user_data);
    agent_lock ();
  } else {
    IOCallbackData *data;

    g_mutex_lock (&component->io_mutex);

    /* Slow path: Current thread doesn’t own the Component’s context at the
     * moment, so schedule the callback in an idle handler. */
    data = io_callback_data_new (buf, buf_len);
    g_queue_push_tail (&component->pending_io_messages,
        data);  /* transfer ownership */

    nice_debug ("%s: **WARNING: SLOW PATH**", G_STRFUNC);

    component_schedule_io_callback (component);

    g_mutex_unlock (&component->io_mutex);
  }
}

/* Note: Must be called with the io_mutex held. */
static void
component_schedule_io_callback (Component *component)
{
  GSource *source;
797

798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821
  /* Already scheduled or nothing to schedule? */
  if (component->io_callback_id != 0 ||
      g_queue_is_empty (&component->pending_io_messages))
    return;

  /* Add the idle callback. If nice_agent_attach_recv() is called with a
   * NULL callback before this source is dispatched, the source will be
   * destroyed, but any pending data will remain in
   * component->pending_io_messages, ready to be picked up when a callback
   * is re-attached, or if nice_agent_recv() is called. */
  source = g_idle_source_new ();
  g_source_set_priority (source, G_PRIORITY_DEFAULT);
  g_source_set_callback (source, emit_io_callback_cb, component, NULL);
  component->io_callback_id = g_source_attach (source, component->ctx);
  g_source_unref (source);
}

/* Note: Must be called with the io_mutex held. */
static void
component_deschedule_io_callback (Component *component)
{
  /* Already descheduled? */
  if (component->io_callback_id == 0)
    return;
822

823 824
  g_source_remove (component->io_callback_id);
  component->io_callback_id = 0;
825
}
826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853


/**
 * ComponentSource:
 *
 * This is a GSource which wraps a single Component and is dispatched whenever
 * any of its NiceSockets are dispatched, i.e. it proxies all poll() events for
 * every socket in the Component. It is designed for use by GPollableInputStream
 * and GPollableOutputStream, so that a Component can be incorporated into a
 * custom main context iteration.
 *
 * The callbacks dispatched by a ComponentSource have type GPollableSourceFunc.
 *
 * ComponentSource supports adding a GCancellable child source which will
 * additionally dispatch if a provided GCancellable is cancelled.
 *
 * Internally, ComponentSource adds a new GSocketSource for each socket in the
 * Component. Changes to the Component’s list of sockets are detected on each
 * call to component_source_prepare(), which compares a stored age with the
 * current age of the Component’s socket list — if the socket list has changed,
 * the age will have increased (indicating added sockets) or will have been
 * reset to 0 (indicating all sockets have been closed).
 */
typedef struct {
  GSource parent;

  GObject *pollable_stream;  /* owned */

854 855 856
  GWeakRef agent_ref;
  guint stream_id;
  guint component_id;
857
  guint component_socket_sources_age;
858 859

  GIOCondition condition;
860 861 862 863 864 865 866
} ComponentSource;

static gboolean
component_source_prepare (GSource *source, gint *timeout_)
{
  ComponentSource *component_source = (ComponentSource *) source;
  gint age_diff;
867 868 869 870 871 872
  NiceAgent *agent;
  Component *component;

  agent = g_weak_ref_get (&component_source->agent_ref);
  if (!agent)
    return FALSE;
873 874 875 876

  /* Needed due to accessing the Component. */
  agent_lock ();

877 878 879 880 881 882
  if (!agent_find_component (agent,
          component_source->stream_id, component_source->component_id, NULL,
          &component))
    goto done;


883
  age_diff =
884
      component->socket_sources_age -
885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904
      component_source->component_socket_sources_age;

  /* If the age has changed, either:
   *  • a new socket has been *prepended* to component->socket_sources (and
   *    age_diff > 0); or
   *  • component->socket_sources has been emptied (and age_diff < 0).
   * We can’t remove any child sources without destroying them, so must
   * monotonically add new ones, or remove everything.
   *
   * Removing everything only happens on shutdown or failure, in which case
   * the ComponentSource itself can be destroyed, automatically destroying all
   * the child sources. */
  if (age_diff < 0) {
    g_source_destroy (source);
  } else if (age_diff > 0) {
    /* Add the new child sources. The difference between the two ages gives
     * the number of new child sources. */
    guint i;
    GSList *l;

905
    for (i = 0, l = component->socket_sources;
906 907 908 909 910 911 912 913
         i < (guint) age_diff && l != NULL;
         i++, l = l->next) {
      GSource *child_source;
      SocketSource *socket_source;

      socket_source = l->data;

      child_source = g_socket_create_source (socket_source->socket->fileno,
914
          G_IO_IN, NULL);
915 916 917 918 919 920 921
      g_source_set_dummy_callback (child_source);
      g_source_add_child_source (source, child_source);
      g_source_unref (child_source);
    }
  }

  /* Update the age. */
922 923 924
  component_source->component_socket_sources_age = component->socket_sources_age;

 done:
925

926
  agent_unlock_and_emit (agent);
927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947

  /* We can’t be sure if the ComponentSource itself needs to be dispatched until
   * poll() is called on all the child sources. */
  return FALSE;
}

static gboolean
component_source_dispatch (GSource *source, GSourceFunc callback,
    gpointer user_data)
{
  ComponentSource *component_source = (ComponentSource *) source;
  GPollableSourceFunc func = (GPollableSourceFunc) callback;

  return func (component_source->pollable_stream, user_data);
}

static void
component_source_finalize (GSource *source)
{
  ComponentSource *component_source = (ComponentSource *) source;

948
  g_weak_ref_clear (&component_source->agent_ref);
949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983
  g_object_unref (component_source->pollable_stream);
  component_source->pollable_stream = NULL;
}

static gboolean
component_source_closure_callback (GObject *pollable_stream, gpointer user_data)
{
  GClosure *closure = user_data;
  GValue param_value = G_VALUE_INIT;
  GValue result_value = G_VALUE_INIT;
  gboolean retval;

  g_value_init (&result_value, G_TYPE_BOOLEAN);
  g_value_init (&param_value, G_TYPE_OBJECT);
  g_value_set_object (&param_value, pollable_stream);

  g_closure_invoke (closure, &result_value, 1, &param_value, NULL);
  retval = g_value_get_boolean (&result_value);

  g_value_unset (&param_value);
  g_value_unset (&result_value);

  return retval;
}

static GSourceFuncs component_source_funcs = {
  component_source_prepare,
  NULL,  /* check */
  component_source_dispatch,
  component_source_finalize,
  (GSourceFunc) component_source_closure_callback,
};

/**
 * component_source_new:
984 985 986
 * @agent: a #NiceAgent
 * @stream_id: The stream's id
 * @component_id: The component's number
987 988
 * @pollable_stream: a #GPollableInputStream or #GPollableOutputStream to pass
 * to dispatched callbacks
989
 * @condition: underlying socket condition to dispatch on
990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005
 * @cancellable: (allow-none): a #GCancellable, or %NULL
 *
 * Create a new #ComponentSource, a type of #GSource which proxies poll events
 * from all sockets in the given @component.
 *
 * A callback function of type #GPollableSourceFunc must be connected to the
 * returned #GSource using g_source_set_callback(). @pollable_stream is passed
 * to all callbacks dispatched from the #GSource, and a reference is held on it
 * by the #GSource.
 *
 * The #GSource will automatically update to poll sockets as they’re added to
 * the @component (e.g. during peer discovery).
 *
 * Returns: (transfer full): a new #ComponentSource; unref with g_source_unref()
 */
GSource *
1006 1007 1008
component_source_new (NiceAgent *agent, guint stream_id,
    guint component_id, GObject *pollable_stream,
    GIOCondition condition,
1009
    GCancellable *cancellable)
1010 1011 1012
{
  ComponentSource *component_source;

1013 1014
  g_assert (G_IS_POLLABLE_INPUT_STREAM (pollable_stream) ||
            G_IS_POLLABLE_OUTPUT_STREAM (pollable_stream));
1015 1016 1017 1018 1019 1020 1021

  component_source =
      (ComponentSource *)
          g_source_new (&component_source_funcs, sizeof (ComponentSource));
  g_source_set_name ((GSource *) component_source, "ComponentSource");

  component_source->component_socket_sources_age = 0;
1022
  component_source->pollable_stream = g_object_ref (pollable_stream);
1023 1024 1025
  g_weak_ref_init (&component_source->agent_ref, agent);
  component_source->stream_id = stream_id;
  component_source->component_id = component_id;
1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039

  /* Add a cancellable source. */
  if (cancellable != NULL) {
    GSource *cancellable_source;

    cancellable_source = g_cancellable_source_new (cancellable);
    g_source_set_dummy_callback (cancellable_source);
    g_source_add_child_source ((GSource *) component_source,
        cancellable_source);
    g_source_unref (cancellable_source);
  }

  return (GSource *) component_source;
}