bridge_channel.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2007 - 2009, Digium, Inc.
 *
 * Joshua Colp <[email protected]>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief Bridging Channel API
 *
 * \author Joshua Colp <[email protected]>
 * \author Richard Mudgett <[email protected]>
 * \author Matt Jordan <[email protected]>
 *
 */

/*** MODULEINFO
   <support_level>core</support_level>
 ***/

#include "asterisk.h"

#include <signal.h>

#include "asterisk/heap.h"
#include "asterisk/alertpipe.h"
#include "asterisk/astobj2.h"
#include "asterisk/stringfields.h"
#include "asterisk/app.h"
#include "asterisk/pbx.h"
#include "asterisk/channel.h"
#include "asterisk/timing.h"
#include "asterisk/bridge.h"
#include "asterisk/bridge_channel.h"
#include "asterisk/bridge_after.h"
#include "asterisk/bridge_channel_internal.h"
#include "asterisk/bridge_internal.h"
#include "asterisk/stasis_bridges.h"
#include "asterisk/stasis_channels.h"
#include "asterisk/musiconhold.h"
#include "asterisk/features_config.h"
#include "asterisk/parking.h"
#include "asterisk/causes.h"
#include "asterisk/test.h"
#include "asterisk/sem.h"
#include "asterisk/stream.h"
#include "asterisk/message.h"

/*!
 * \brief Used to queue an action frame onto a bridge channel and write an action frame into a bridge.
 * \since 12.0.0
 *
 * \param bridge_channel Which channel work with.
 * \param action Type of bridge action frame.
 * \param data Frame payload data to pass.
 * \param datalen Frame payload data length to pass.
 *
 * \retval 0 on success.
 * \retval -1 on error.
 */
typedef int (*ast_bridge_channel_post_action_data)(struct ast_bridge_channel *bridge_channel, enum bridge_channel_action_type action, const void *data, size_t datalen);

/*!
 * \brief Counter used for assigning synchronous bridge action IDs
 */
static int sync_ids;

/*!
 * \brief Frame payload for synchronous bridge actions.
 *
 * The payload serves as a wrapper around the actual payload of the
 * frame, with the addition of an id used to find the associated
 * bridge_sync object.
 */
struct sync_payload {
   /*! Unique ID for this synchronous action */
   unsigned int id;
   /*! Actual frame data to process */
   unsigned char data[0];
};

/*!
 * \brief Synchronous bridge action object.
 *
 * Synchronous bridge actions require the ability for one thread to wait
 * and for another thread to indicate that the action has completed. This
 * structure facilitates that goal by providing synchronization structures.
 */
struct bridge_sync {
   /*! Unique ID of this synchronization object. Corresponds with ID in synchronous frame payload */
   unsigned int id;
   /*! Semaphore used for synchronization */
   struct ast_sem sem;
   /*! Pointer to next entry in the list */
   AST_LIST_ENTRY(bridge_sync) list;
};

/*!
 * \brief List holding active synchronous action objects.
 */
static AST_RWLIST_HEAD_STATIC(sync_structs, bridge_sync);

/*!
 * \brief initialize a synchronous bridge object.
 *
 * This both initializes the structure and adds it to the list of
 * synchronization structures.
 *
 * \param sync_struct The synchronization object to initialize.
 * \param id ID to assign to the synchronization object.
 */
static void bridge_sync_init(struct bridge_sync *sync_struct, unsigned int id)
{
   memset(sync_struct, 0, sizeof(*sync_struct));
   sync_struct->id = id;
   ast_sem_init(&sync_struct->sem, 0, 0);

   AST_RWLIST_WRLOCK(&sync_structs);
   AST_RWLIST_INSERT_TAIL(&sync_structs, sync_struct, list);
   AST_RWLIST_UNLOCK(&sync_structs);
}

/*!
 * \brief Clean up a syncrhonization bridge object.
 *
 * This frees fields within the synchronization object and removes
 * it from the list of active synchronization objects.
 *
 * Since synchronization objects are stack-allocated, it is vital
 * that this is called before the synchronization object goes
 * out of scope.
 *
 * \param sync_struct Synchronization object to clean up.
 */
static void bridge_sync_cleanup(struct bridge_sync *sync_struct)
{
   struct bridge_sync *iter;

   AST_RWLIST_WRLOCK(&sync_structs);
   AST_LIST_TRAVERSE_SAFE_BEGIN(&sync_structs, iter, list) {
      if (iter->id == sync_struct->id) {
         AST_LIST_REMOVE_CURRENT(list);
         break;
      }
   }
   AST_LIST_TRAVERSE_SAFE_END;
   AST_RWLIST_UNLOCK(&sync_structs);

   ast_sem_destroy(&sync_struct->sem);
}

/*!
 * \brief Failsafe for synchronous bridge action waiting.
 *
 * When waiting for a synchronous bridge action to complete,
 * if there is a frame resource leak somewhere, it is possible
 * that we will never get notified that the synchronous action
 * completed.
 *
 * If a significant amount of time passes, then we will abandon
 * waiting for the synchrnous bridge action to complete.
 *
 * This constant represents the number of milliseconds we will
 * wait for the bridge action to complete.
 */
#define PLAYBACK_TIMEOUT (600 * 1000)

/*!
 * \brief Wait for a synchronous bridge action to complete.
 *
 * \param sync_struct Synchronization object corresponding to the bridge action.
 */
static void bridge_sync_wait(struct bridge_sync *sync_struct)
{
   struct timeval timeout_val = ast_tvadd(ast_tvnow(), ast_samp2tv(PLAYBACK_TIMEOUT, 1000));
   struct timespec timeout_spec = {
      .tv_sec = timeout_val.tv_sec,
      .tv_nsec = timeout_val.tv_usec * 1000,
   };

   ast_sem_timedwait(&sync_struct->sem, &timeout_spec);
}

/*!
 * \brief Signal that waiting for a synchronous bridge action is no longer necessary.
 *
 * This may occur for several reasons
 * \li The synchronous bridge action has completed.
 * \li The bridge channel has been removed from the bridge.
 * \li The synchronous bridge action could not be queued.
 *
 * \param sync_struct Synchronization object corresponding to the bridge action.
 */
static void bridge_sync_signal(struct bridge_sync *sync_struct)
{
   ast_sem_post(&sync_struct->sem);
}

struct ast_channel *ast_bridge_channel_get_chan(struct ast_bridge_channel *bridge_channel)
{
   struct ast_channel *chan;

   ao2_lock(bridge_channel);
   chan = ao2_bump(bridge_channel->chan);
   ao2_unlock(bridge_channel);

   return chan;
}

void ast_bridge_channel_lock_bridge(struct ast_bridge_channel *bridge_channel)
{
   struct ast_bridge *bridge;

   for (;;) {
      /* Safely get the bridge pointer */
      ast_bridge_channel_lock(bridge_channel);
      bridge = bridge_channel->bridge;
      ao2_ref(bridge, +1);
      ast_bridge_channel_unlock(bridge_channel);

      /* Lock the bridge and see if it is still the bridge we need to lock. */
      ast_bridge_lock(bridge);
      if (bridge == bridge_channel->bridge) {
         ao2_ref(bridge, -1);
         return;
      }
      ast_bridge_unlock(bridge);
      ao2_ref(bridge, -1);
   }
}

int ast_bridge_channel_notify_talking(struct ast_bridge_channel *bridge_channel, int started_talking)
{
   struct ast_frame action = {
      .frametype = AST_FRAME_BRIDGE_ACTION,
      .subclass.integer = started_talking
         ? BRIDGE_CHANNEL_ACTION_TALKING_START : BRIDGE_CHANNEL_ACTION_TALKING_STOP,
   };

   return ast_bridge_channel_queue_frame(bridge_channel, &action);
}

/*!
 * \internal
 * \brief Poke the bridge_channel thread
 */
static void bridge_channel_poke(struct ast_bridge_channel *bridge_channel)
{
   if (!pthread_equal(pthread_self(), bridge_channel->thread)) {
      /* Wake up the bridge channel thread. */
      ast_queue_frame(bridge_channel->chan, &ast_null_frame);
   }
}

/*!
 * \internal
 * \brief Set actual cause on channel.
 * \since 12.0.0
 *
 * \param chan Channel to set cause.
 * \param cause Cause to set on channel.
 *   If cause <= 0 then use cause on channel if cause still <= 0 use AST_CAUSE_NORMAL_CLEARING.
 *
 * \return Actual cause set on channel.
 */
static int channel_set_cause(struct ast_channel *chan, int cause)
{
   ast_channel_lock(chan);
   if (cause <= 0) {
      cause = ast_channel_hangupcause(chan);
      if (cause <= 0) {
         cause = AST_CAUSE_NORMAL_CLEARING;
      }
   }
   ast_channel_hangupcause_set(chan, cause);
   ast_channel_unlock(chan);
   return cause;
}

void ast_bridge_channel_leave_bridge_nolock(struct ast_bridge_channel *bridge_channel, enum bridge_channel_state new_state, int cause)
{
   if (bridge_channel->state != BRIDGE_CHANNEL_STATE_WAIT) {
      return;
   }

   ast_debug(1, "Setting %p(%s) state from:%u to:%u\n",
      bridge_channel, ast_channel_name(bridge_channel->chan), bridge_channel->state,
      new_state);

   channel_set_cause(bridge_channel->chan, cause);

   ast_channel_lock(bridge_channel->chan);
   ast_bridge_vars_set(bridge_channel->chan, NULL, NULL);
   ast_channel_unlock(bridge_channel->chan);

   /* Change the state on the bridge channel */
   bridge_channel->state = new_state;

   bridge_channel_poke(bridge_channel);
}

void ast_bridge_channel_leave_bridge(struct ast_bridge_channel *bridge_channel, enum bridge_channel_state new_state, int cause)
{
   ast_bridge_channel_lock(bridge_channel);
   ast_bridge_channel_leave_bridge_nolock(bridge_channel, new_state, cause);
   ast_bridge_channel_unlock(bridge_channel);
}

struct ast_bridge_channel *ast_bridge_channel_peer(struct ast_bridge_channel *bridge_channel)
{
   struct ast_bridge *bridge = bridge_channel->bridge;
   struct ast_bridge_channel *other = NULL;

   if (bridge_channel->in_bridge && bridge->num_channels == 2) {
      AST_LIST_TRAVERSE(&bridge->channels, other, entry) {
         if (other != bridge_channel) {
            break;
         }
      }
   }

   return other;
}

void ast_bridge_channel_restore_formats(struct ast_bridge_channel *bridge_channel)
{
   ast_assert(bridge_channel->read_format != NULL);
   ast_assert(bridge_channel->write_format != NULL);

   ast_channel_lock(bridge_channel->chan);

   /* Restore original formats of the channel as they came in */
   if (ast_format_cmp(ast_channel_readformat(bridge_channel->chan), bridge_channel->read_format) == AST_FORMAT_CMP_NOT_EQUAL) {
      ast_debug(1, "Bridge is returning %p(%s) to read format %s\n",
         bridge_channel, ast_channel_name(bridge_channel->chan),
         ast_format_get_name(bridge_channel->read_format));
      if (ast_set_read_format(bridge_channel->chan, bridge_channel->read_format)) {
         ast_debug(1, "Bridge failed to return %p(%s) to read format %s\n",
            bridge_channel, ast_channel_name(bridge_channel->chan),
            ast_format_get_name(bridge_channel->read_format));
      }
   }
   if (ast_format_cmp(ast_channel_writeformat(bridge_channel->chan), bridge_channel->write_format) == AST_FORMAT_CMP_NOT_EQUAL) {
      ast_debug(1, "Bridge is returning %p(%s) to write format %s\n",
         bridge_channel, ast_channel_name(bridge_channel->chan),
         ast_format_get_name(bridge_channel->write_format));
      if (ast_set_write_format(bridge_channel->chan, bridge_channel->write_format)) {
         ast_debug(1, "Bridge failed to return %p(%s) to write format %s\n",
            bridge_channel, ast_channel_name(bridge_channel->chan),
            ast_format_get_name(bridge_channel->write_format));
      }
   }

   ast_channel_unlock(bridge_channel->chan);
}

struct ast_bridge *ast_bridge_channel_merge_inhibit(struct ast_bridge_channel *bridge_channel, int request)
{
   struct ast_bridge *bridge;

   ast_bridge_channel_lock_bridge(bridge_channel);
   bridge = bridge_channel->bridge;
   ao2_ref(bridge, +1);
   bridge_merge_inhibit_nolock(bridge, request);
   ast_bridge_unlock(bridge);
   return bridge;
}

void ast_bridge_channel_update_linkedids(struct ast_bridge_channel *bridge_channel, struct ast_bridge_channel *swap)
{
   struct ast_bridge_channel *other;
   struct ast_bridge *bridge = bridge_channel->bridge;
   struct ast_channel *oldest_linkedid_chan = bridge_channel->chan;

   AST_LIST_TRAVERSE(&bridge->channels, other, entry) {
      if (other == swap) {
         continue;
      }
      oldest_linkedid_chan = ast_channel_internal_oldest_linkedid(
         oldest_linkedid_chan, other->chan);
   }

   ast_channel_lock(bridge_channel->chan);
   ast_channel_internal_copy_linkedid(bridge_channel->chan, oldest_linkedid_chan);
   ast_channel_unlock(bridge_channel->chan);
   AST_LIST_TRAVERSE(&bridge->channels, other, entry) {
      if (other == swap) {
         continue;
      }
      ast_channel_lock(other->chan);
      ast_channel_internal_copy_linkedid(other->chan, oldest_linkedid_chan);
      ast_channel_unlock(other->chan);
   }
}

/*!
 * \internal
 * \brief Set dest's empty peeraccount with the src's non-empty accountcode.
 * \since 12.5.0
 *
 * \param dest Channel to update peeraccount.
 * \param src Channel to get accountcode from.
 *
 * \note Both channels are already locked.
 *
 * \return Nothing
 */
static void channel_fill_empty_peeraccount(struct ast_channel *dest, struct ast_channel *src)
{
   if (ast_strlen_zero(ast_channel_peeraccount(dest))
      && !ast_strlen_zero(ast_channel_accountcode(src))) {
      ast_debug(1, "Setting channel %s peeraccount with channel %s accountcode '%s'.\n",
         ast_channel_name(dest),
         ast_channel_name(src), ast_channel_accountcode(src));
      ast_channel_peeraccount_set(dest, ast_channel_accountcode(src));
   }
}

/*!
 * \internal
 * \brief Set dest's empty accountcode with the src's non-empty peeraccount.
 * \since 12.5.0
 *
 * \param dest Channel to update accountcode.
 * \param src Channel to get peeraccount from.
 *
 * \note Both channels are already locked.
 *
 * \return Nothing
 */
static void channel_fill_empty_accountcode(struct ast_channel *dest, struct ast_channel *src)
{
   if (ast_strlen_zero(ast_channel_accountcode(dest))
      && !ast_strlen_zero(ast_channel_peeraccount(src))) {
      ast_debug(1, "Setting channel %s accountcode with channel %s peeraccount '%s'.\n",
         ast_channel_name(dest),
         ast_channel_name(src), ast_channel_peeraccount(src));
      ast_channel_accountcode_set(dest, ast_channel_peeraccount(src));
   }
}

/*!
 * \internal
 * \brief Set empty peeraccount and accountcode in a channel from the other channel.
 * \since 12.5.0
 *
 * \param c0 First bridge channel to update.
 * \param c1 Second bridge channel to update.
 *
 * \note Both channels are already locked.
 *
 * \return Nothing
 */
static void channel_set_empty_accountcodes(struct ast_channel *c0, struct ast_channel *c1)
{
   /* Set empty peeraccount from the other channel's accountcode. */
   channel_fill_empty_peeraccount(c0, c1);
   channel_fill_empty_peeraccount(c1, c0);

   /* Set empty accountcode from the other channel's peeraccount. */
   channel_fill_empty_accountcode(c0, c1);
   channel_fill_empty_accountcode(c1, c0);
}

/*!
 * \internal
 * \brief Update dest's peeraccount with the src's different accountcode.
 * \since 12.5.0
 *
 * \param dest Channel to update peeraccount.
 * \param src Channel to get accountcode from.
 *
 * \note Both channels are already locked.
 *
 * \return Nothing
 */
static void channel_update_peeraccount(struct ast_channel *dest, struct ast_channel *src)
{
   if (strcmp(ast_channel_accountcode(src), ast_channel_peeraccount(dest))) {
      ast_debug(1, "Changing channel %s peeraccount '%s' to match channel %s accountcode '%s'.\n",
         ast_channel_name(dest), ast_channel_peeraccount(dest),
         ast_channel_name(src), ast_channel_accountcode(src));
      ast_channel_peeraccount_set(dest, ast_channel_accountcode(src));
   }
}

/*!
 * \internal
 * \brief Update peeraccounts to match the other channel's accountcode.
 * \since 12.5.0
 *
 * \param c0 First channel to update.
 * \param c1 Second channel to update.
 *
 * \note Both channels are already locked.
 *
 * \return Nothing
 */
static void channel_update_peeraccounts(struct ast_channel *c0, struct ast_channel *c1)
{
   channel_update_peeraccount(c0, c1);
   channel_update_peeraccount(c1, c0);
}

/*!
 * \internal
 * \brief Update channel accountcodes because a channel is joining a bridge.
 * \since 12.5.0
 *
 * \param joining Channel joining the bridge.
 * \param swap Channel being replaced by the joining channel.  May be NULL.
 *
 * \note The bridge must be locked prior to calling this function.
 *
 * \return Nothing
 */
static void bridge_channel_update_accountcodes_joining(struct ast_bridge_channel *joining, struct ast_bridge_channel *swap)
{
   struct ast_bridge *bridge = joining->bridge;
   struct ast_bridge_channel *other;
   unsigned int swap_in_bridge = 0;
   unsigned int will_be_two_party;

   /*
    * Only update the peeraccount to match if the joining channel
    * will make it a two party bridge.
    */
   if (bridge->num_channels <= 2 && swap) {
      AST_LIST_TRAVERSE(&bridge->channels, other, entry) {
         if (other == swap) {
            swap_in_bridge = 1;
            break;
         }
      }
   }
   will_be_two_party = (1 == bridge->num_channels - swap_in_bridge);

   AST_LIST_TRAVERSE(&bridge->channels, other, entry) {
      if (other == swap) {
         continue;
      }
      ast_assert(joining != other);
      ast_channel_lock_both(joining->chan, other->chan);
      channel_set_empty_accountcodes(joining->chan, other->chan);
      if (will_be_two_party) {
         channel_update_peeraccounts(joining->chan, other->chan);
      }
      ast_channel_unlock(joining->chan);
      ast_channel_unlock(other->chan);
   }
}

/*!
 * \internal
 * \brief Update channel peeraccount codes because a channel has left a bridge.
 * \since 12.5.0
 *
 * \param leaving Channel leaving the bridge. (Has already been removed actually)
 *
 * \note The bridge must be locked prior to calling this function.
 *
 * \return Nothing
 */
static void bridge_channel_update_accountcodes_leaving(struct ast_bridge_channel *leaving)
{
   struct ast_bridge *bridge = leaving->bridge;
   struct ast_bridge_channel *first;
   struct ast_bridge_channel *second;

   if (bridge->num_channels != 2 || bridge->dissolved) {
      return;
   }

   first = AST_LIST_FIRST(&bridge->channels);
   second = AST_LIST_LAST(&bridge->channels);
   ast_assert(first && first != second);
   ast_channel_lock_both(first->chan, second->chan);
   channel_set_empty_accountcodes(first->chan, second->chan);
   channel_update_peeraccounts(first->chan, second->chan);
   ast_channel_unlock(second->chan);
   ast_channel_unlock(first->chan);
}

void ast_bridge_channel_update_accountcodes(struct ast_bridge_channel *joining, struct ast_bridge_channel *leaving)
{
   if (joining) {
      bridge_channel_update_accountcodes_joining(joining, leaving);
   } else {
      bridge_channel_update_accountcodes_leaving(leaving);
   }
}

void ast_bridge_channel_kick(struct ast_bridge_channel *bridge_channel, int cause)
{
   struct ast_bridge_features *features = bridge_channel->features;
   struct ast_bridge_hook *hook;
   struct ao2_iterator iter;

   ast_bridge_channel_lock(bridge_channel);
   if (bridge_channel->state == BRIDGE_CHANNEL_STATE_WAIT) {
      channel_set_cause(bridge_channel->chan, cause);
      cause = 0;
   }
   ast_bridge_channel_unlock(bridge_channel);

   /* Run any hangup hooks. */
   iter = ao2_iterator_init(features->other_hooks, 0);
   for (; (hook = ao2_iterator_next(&iter)); ao2_ref(hook, -1)) {
      int remove_me;

      if (hook->type != AST_BRIDGE_HOOK_TYPE_HANGUP) {
         continue;
      }
      remove_me = hook->callback(bridge_channel, hook->hook_pvt);
      if (remove_me) {
         ast_debug(1, "Hangup hook %p is being removed from %p(%s)\n",
            hook, bridge_channel, ast_channel_name(bridge_channel->chan));
         ao2_unlink(features->other_hooks, hook);
      }
   }
   ao2_iterator_destroy(&iter);

   /* Default hangup action. */
   ast_bridge_channel_leave_bridge(bridge_channel, BRIDGE_CHANNEL_STATE_END, cause);
}

/*!
 * \internal
 * \brief Write an \ref ast_frame into the bridge
 * \since 12.0.0
 *
 * \param bridge_channel Which channel is queueing the frame.
 * \param frame The frame to write into the bridge
 *
 * \retval 0 on success.
 * \retval -1 on error.
 */
static int bridge_channel_write_frame(struct ast_bridge_channel *bridge_channel, struct ast_frame *frame)
{
   const struct ast_control_t38_parameters *t38_parameters;
   int unmapped_stream_num;
   int deferred;

   ast_assert(frame->frametype != AST_FRAME_BRIDGE_ACTION_SYNC);

   ast_bridge_channel_lock_bridge(bridge_channel);

   /*
    * Map the frame to the bridge.
    * We need to lock the bridge_channel to make sure that bridge_channel->chan
    * isn't NULL and keep it locked while we do multistream processing.
    */
   ast_bridge_channel_lock(bridge_channel);
   if (bridge_channel->chan && ast_channel_is_multistream(bridge_channel->chan)) {
      unmapped_stream_num = frame->stream_num;
      switch (frame->frametype) {
      case AST_FRAME_VOICE:
      case AST_FRAME_VIDEO:
      case AST_FRAME_TEXT:
      case AST_FRAME_IMAGE:
      case AST_FRAME_RTCP:
         /* These frames need to be mapped to an appropriate write stream */
         if (frame->stream_num < 0) {
            /* Map to default stream */
            frame->stream_num = -1;
            break;
         }
         if (frame->stream_num < (int)AST_VECTOR_SIZE(&bridge_channel->stream_map.to_bridge)) {
            frame->stream_num = AST_VECTOR_GET(
               &bridge_channel->stream_map.to_bridge, frame->stream_num);
            if (0 <= frame->stream_num) {
               break;
            }
         }
         ast_bridge_channel_unlock(bridge_channel);
         ast_bridge_unlock(bridge_channel->bridge);
         /*
          * Ignore frame because we don't know how to map the frame
          * or the bridge is not expecting any media from that
          * stream.
          */
         return 0;
      case AST_FRAME_DTMF_BEGIN:
      case AST_FRAME_DTMF_END:
         /*
          * XXX It makes sense that DTMF could be on any audio stream.
          * For now we will only put it on the default audio stream.
          */
      default:
         frame->stream_num = -1;
         break;
      }
   } else {
      unmapped_stream_num = -1;
      frame->stream_num = -1;
   }
   ast_bridge_channel_unlock(bridge_channel);

   deferred = bridge_channel->bridge->technology->write(bridge_channel->bridge, bridge_channel, frame);
   if (deferred) {
      struct ast_frame *dup;

      dup = ast_frdup(frame);
      if (dup) {
         /*
          * We have to unmap the deferred frame so it comes back
          * in like a new frame.
          */
         dup->stream_num = unmapped_stream_num;
         ast_bridge_channel_lock(bridge_channel);
         AST_LIST_INSERT_HEAD(&bridge_channel->deferred_queue, dup, frame_list);
         ast_bridge_channel_unlock(bridge_channel);
      }
   }

   /* Remember any owed events to the bridge. */
   switch (frame->frametype) {
   case AST_FRAME_DTMF_BEGIN:
      bridge_channel->owed.dtmf_tv = ast_tvnow();
      bridge_channel->owed.dtmf_digit = frame->subclass.integer;
      break;
   case AST_FRAME_DTMF_END:
      bridge_channel->owed.dtmf_digit = '\0';
      break;
   case AST_FRAME_CONTROL:
      /*
       * We explicitly will not remember HOLD/UNHOLD frames because
       * things like attended transfers will handle them.
       */
      switch (frame->subclass.integer) {
      case AST_CONTROL_T38_PARAMETERS:
         t38_parameters = frame->data.ptr;
         switch (t38_parameters->request_response) {
         case AST_T38_REQUEST_NEGOTIATE:
         case AST_T38_NEGOTIATED:
            bridge_channel->owed.t38_terminate = 1;
            break;
         case AST_T38_REQUEST_TERMINATE:
         case AST_T38_TERMINATED:
         case AST_T38_REFUSED:
            bridge_channel->owed.t38_terminate = 0;
            break;
         default:
            break;
         }
         break;
      default:
         break;
      }
      break;
   default:
      break;
   }
   ast_bridge_unlock(bridge_channel->bridge);

   /*
    * Claim successful write to bridge.  If deferred frame
    * support is added, claim successfully deferred.
    */
   return 0;
}

/*!
 * \internal
 * \brief Cancel owed events by the channel to the bridge.
 * \since 13.8.0
 *
 * \param bridge_channel Channel that owes events to the bridge.
 *
 * \note On entry, the bridge_channel->bridge is already locked.
 *
 * \return Nothing
 */
static void bridge_channel_cancel_owed_events(struct ast_bridge_channel *bridge_channel)
{
   bridge_channel->owed.dtmf_digit = '\0';
   bridge_channel->owed.t38_terminate = 0;
}

void bridge_channel_settle_owed_events(struct ast_bridge *orig_bridge, struct ast_bridge_channel *bridge_channel)
{
   if (bridge_channel->owed.dtmf_digit) {
      struct ast_frame frame = {
         .frametype = AST_FRAME_DTMF_END,
         .subclass.integer = bridge_channel->owed.dtmf_digit,
         .src = "Bridge channel owed DTMF",
      };

      frame.len = ast_tvdiff_ms(ast_tvnow(), bridge_channel->owed.dtmf_tv);
      if (frame.len < option_dtmfminduration) {
         frame.len = option_dtmfminduration;
      }
      ast_log(LOG_DTMF, "DTMF end '%c' simulated to bridge %s because %s left.  Duration %ld ms.\n",
         bridge_channel->owed.dtmf_digit, orig_bridge->uniqueid,
         ast_channel_name(bridge_channel->chan), frame.len);
      bridge_channel->owed.dtmf_digit = '\0';
      orig_bridge->technology->write(orig_bridge, NULL, &frame);
   }
   if (bridge_channel->owed.t38_terminate) {
      struct ast_control_t38_parameters t38_parameters = {
         .request_response = AST_T38_TERMINATED,
      };
      struct ast_frame frame = {
         .frametype = AST_FRAME_CONTROL,
         .subclass.integer = AST_CONTROL_T38_PARAMETERS,
         .data.ptr = &t38_parameters,
         .datalen = sizeof(t38_parameters),
         .src = "Bridge channel owed T.38 terminate",
      };

      ast_debug(1, "T.38 terminate simulated to bridge %s because %s left.\n",
         orig_bridge->uniqueid, ast_channel_name(bridge_channel->chan));
      bridge_channel->owed.t38_terminate = 0;
      orig_bridge->technology->write(orig_bridge, NULL, &frame);
   }
}

void bridge_channel_queue_deferred_frames(struct ast_bridge_channel *bridge_channel)
{
   struct ast_frame *frame;

   ast_bridge_channel_lock(bridge_channel);
   ast_channel_lock(bridge_channel->chan);
   while ((frame = AST_LIST_REMOVE_HEAD(&bridge_channel->deferred_queue, frame_list))) {
      ast_queue_frame_head(bridge_channel->chan, frame);
      ast_frfree(frame);
   }
   ast_channel_unlock(bridge_channel->chan);
   ast_bridge_channel_unlock(bridge_channel);
}

/*!
 * \internal
 * \brief Suspend a channel from a bridge.
 *
 * \param bridge_channel Channel to suspend.
 *
 * \note This function assumes bridge_channel->bridge is locked.
 *
 * \return Nothing
 */
void bridge_channel_internal_suspend_nolock(struct ast_bridge_channel *bridge_channel)
{
   bridge_channel->suspended = 1;
   if (bridge_channel->in_bridge) {
      --bridge_channel->bridge->num_active;
   }

   /* Get technology bridge threads off of the channel. */
   if (bridge_channel->bridge->technology->suspend) {
      bridge_channel->bridge->technology->suspend(bridge_channel->bridge, bridge_channel);
   }
}

/*!
 * \internal
 * \brief Suspend a channel from a bridge.
 *
 * \param bridge_channel Channel to suspend.
 *
 * \return Nothing
 */
static void bridge_channel_suspend(struct ast_bridge_channel *bridge_channel)
{
   ast_bridge_channel_lock_bridge(bridge_channel);
   bridge_channel_internal_suspend_nolock(bridge_channel);
   ast_bridge_unlock(bridge_channel->bridge);
}

/*!
 * \internal
 * \brief Unsuspend a channel from a bridge.
 *
 * \param bridge_channel Channel to unsuspend.
 *
 * \note This function assumes bridge_channel->bridge is locked.
 *
 * \return Nothing
 */
void bridge_channel_internal_unsuspend_nolock(struct ast_bridge_channel *bridge_channel)
{
   bridge_channel->suspended = 0;
   if (bridge_channel->in_bridge) {
      ++bridge_channel->bridge->num_active;
   }

   /* Wake technology bridge threads to take care of channel again. */
   if (bridge_channel->bridge->technology->unsuspend) {
      bridge_channel->bridge->technology->unsuspend(bridge_channel->bridge, bridge_channel);
   }

   /* Wake suspended channel. */
   ast_bridge_channel_lock(bridge_channel);
   ast_cond_signal(&bridge_channel->cond);
   ast_bridge_channel_unlock(bridge_channel);
}

/*!
 * \internal
 * \brief Unsuspend a channel from a bridge.
 *
 * \param bridge_channel Channel to unsuspend.
 *
 * \return Nothing
 */
static void bridge_channel_unsuspend(struct ast_bridge_channel *bridge_channel)
{
   ast_bridge_channel_lock_bridge(bridge_channel);
   bridge_channel_internal_unsuspend_nolock(bridge_channel);
   ast_bridge_unlock(bridge_channel->bridge);
}

/*!
 * \internal
 * \brief Queue an action frame onto the bridge channel with data.
 * \since 12.0.0
 *
 * \param bridge_channel Which channel to queue the frame onto.
 * \param action Type of bridge action frame.
 * \param data Frame payload data to pass.
 * \param datalen Frame payload data length to pass.
 *
 * \retval 0 on success.
 * \retval -1 on error.
 */
static int bridge_channel_queue_action_data(struct ast_bridge_channel *bridge_channel,
   enum bridge_channel_action_type action, const void *data, size_t datalen)
{
   struct ast_frame frame = {
      .frametype = AST_FRAME_BRIDGE_ACTION,
      .subclass.integer = action,
      .datalen = datalen,
      .data.ptr = (void *) data,
   };

   return ast_bridge_channel_queue_frame(bridge_channel, &frame);
}

/*!
 * \internal
 * \brief Queue an action frame onto the bridge channel with data synchronously.
 * \since 12.2.0
 *
 * The function will not return until the queued frame is freed.
 *
 * \param bridge_channel Which channel to queue the frame onto.
 * \param action Type of bridge action frame.
 * \param data Frame payload data to pass.
 * \param datalen Frame payload data length to pass.
 *
 * \retval 0 on success.
 * \retval -1 on error.
 */
static int bridge_channel_queue_action_data_sync(struct ast_bridge_channel *bridge_channel,
   enum bridge_channel_action_type action, const void *data, size_t datalen)
{
   struct sync_payload *sync_payload;
   int sync_payload_len = sizeof(*sync_payload) + datalen;
   struct bridge_sync sync_struct;
   struct ast_frame frame = {
      .frametype = AST_FRAME_BRIDGE_ACTION_SYNC,
      .subclass.integer = action,
   };

   /* Make sure we don't end up trying to wait on ourself to deliver the frame */
   ast_assert(!pthread_equal(pthread_self(), bridge_channel->thread));

   sync_payload = ast_alloca(sync_payload_len);
   sync_payload->id = ast_atomic_fetchadd_int(&sync_ids, +1);
   memcpy(sync_payload->data, data, datalen);

   frame.datalen = sync_payload_len;
   frame.data.ptr = sync_payload;

   bridge_sync_init(&sync_struct, sync_payload->id);
   if (ast_bridge_channel_queue_frame(bridge_channel, &frame)) {
      bridge_sync_cleanup(&sync_struct);
      return -1;
   }

   bridge_sync_wait(&sync_struct);
   bridge_sync_cleanup(&sync_struct);
   return 0;
}
/*!
 * \internal
 * \brief Write an action frame onto the bridge channel with data.
 * \since 12.0.0
 *
 * \param bridge_channel Which channel to queue the frame onto.
 * \param action Type of bridge action frame.
 * \param data Frame payload data to pass.
 * \param datalen Frame payload data length to pass.
 *
 * \retval 0 on success.
 * \retval -1 on error.
 */
static int bridge_channel_write_action_data(struct ast_bridge_channel *bridge_channel,
   enum bridge_channel_action_type action, const void *data, size_t datalen)
{
   struct ast_frame frame = {
      .frametype = AST_FRAME_BRIDGE_ACTION,
      .subclass.integer = action,
      .datalen = datalen,
      .data.ptr = (void *) data,
   };

   return bridge_channel_write_frame(bridge_channel, &frame);
}

static void bridge_frame_free(struct ast_frame *frame)
{
   if (frame->frametype == AST_FRAME_BRIDGE_ACTION_SYNC) {
      struct sync_payload *sync_payload = frame->data.ptr;
      struct bridge_sync *sync;

      AST_RWLIST_RDLOCK(&sync_structs);
      AST_RWLIST_TRAVERSE(&sync_structs, sync, list) {
         if (sync->id == sync_payload->id) {
            break;
         }
      }
      if (sync) {
         bridge_sync_signal(sync);
      }
      AST_RWLIST_UNLOCK(&sync_structs);
   }

   ast_frfree(frame);
}

int ast_bridge_channel_queue_frame(struct ast_bridge_channel *bridge_channel, struct ast_frame *fr)
{
   struct ast_frame *dup;

   if (bridge_channel->suspended
      /* Also defer DTMF frames. */
      && fr->frametype != AST_FRAME_DTMF_BEGIN
      && fr->frametype != AST_FRAME_DTMF_END
      && !ast_is_deferrable_frame(fr)) {
      /* Drop non-deferable frames when suspended. */
      return 0;
   }
   if (fr->frametype == AST_FRAME_NULL) {
      /* "Accept" the frame and discard it. */
      return 0;
   }

   if ((fr->frametype == AST_FRAME_VOICE || fr->frametype == AST_FRAME_VIDEO ||
      fr->frametype == AST_FRAME_TEXT || fr->frametype == AST_FRAME_IMAGE ||
      fr->frametype == AST_FRAME_RTCP) && fr->stream_num > -1) {
      int num = -1;

      ast_bridge_channel_lock(bridge_channel);
      if (fr->stream_num < (int)AST_VECTOR_SIZE(&bridge_channel->stream_map.to_channel)) {
         num = AST_VECTOR_GET(&bridge_channel->stream_map.to_channel, fr->stream_num);
      }
      ast_bridge_channel_unlock(bridge_channel);

      if (num == -1) {
         /* We don't have a mapped stream so just discard this frame. */
         return 0;
      }
   }

   dup = ast_frdup(fr);
   if (!dup) {
      return -1;
   }

   ast_bridge_channel_lock(bridge_channel);
   if (bridge_channel->state != BRIDGE_CHANNEL_STATE_WAIT) {
      /* Drop frames on channels leaving the bridge. */
      ast_bridge_channel_unlock(bridge_channel);
      bridge_frame_free(dup);
      return 0;
   }

   if ((fr->frametype == AST_FRAME_TEXT || fr->frametype == AST_FRAME_TEXT_DATA) &&
      !bridge_channel->features->text_messaging) {
      /* This channel is not accepting text messages. */
      ast_bridge_channel_unlock(bridge_channel);
      bridge_frame_free(dup);
      return 0;
   }

   if (DEBUG_ATLEAST(1)) {
      if (fr->frametype == AST_FRAME_TEXT) {
         ast_log(LOG_DEBUG, "Queuing TEXT frame to '%s': %*.s\n", ast_channel_name(bridge_channel->chan),
            fr->datalen, (char *)fr->data.ptr);
      } else if (fr->frametype == AST_FRAME_TEXT_DATA) {
         struct ast_msg_data *msg = fr->data.ptr;
         ast_log(LOG_DEBUG, "Queueing TEXT_DATA frame from '%s' to '%s:%s': %s\n",
            ast_msg_data_get_attribute(msg, AST_MSG_DATA_ATTR_FROM),
            ast_msg_data_get_attribute(msg, AST_MSG_DATA_ATTR_TO),
            ast_channel_name(bridge_channel->chan),
            ast_msg_data_get_attribute(msg, AST_MSG_DATA_ATTR_BODY));
      }
   }

   AST_LIST_INSERT_TAIL(&bridge_channel->wr_queue, dup, frame_list);
   if (ast_alertpipe_write(bridge_channel->alert_pipe)) {
      ast_log(LOG_ERROR, "We couldn't write alert pipe for %p(%s)... something is VERY wrong\n",
         bridge_channel, ast_channel_name(bridge_channel->chan));
   }
   ast_bridge_channel_unlock(bridge_channel);
   return 0;
}

int ast_bridge_queue_everyone_else(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel, struct ast_frame *frame)
{
   struct ast_bridge_channel *cur;
   int not_written = -1;

   if (frame->frametype == AST_FRAME_NULL) {
      /* "Accept" the frame and discard it. */
      return 0;
   }

   AST_LIST_TRAVERSE(&bridge->channels, cur, entry) {
      if (cur == bridge_channel) {
         continue;
      }
      if (!ast_bridge_channel_queue_frame(cur, frame)) {
         not_written = 0;
      }
   }
   return not_written;
}

int ast_bridge_channel_queue_control_data(struct ast_bridge_channel *bridge_channel, enum ast_control_frame_type control, const void *data, size_t datalen)
{
   struct ast_frame frame = {
      .frametype = AST_FRAME_CONTROL,
      .subclass.integer = control,
      .datalen = datalen,
      .data.ptr = (void *) data,
   };

   return ast_bridge_channel_queue_frame(bridge_channel, &frame);
}

int ast_bridge_channel_write_control_data(struct ast_bridge_channel *bridge_channel, enum ast_control_frame_type control, const void *data, size_t datalen)
{
   struct ast_frame frame = {
      .frametype = AST_FRAME_CONTROL,
      .subclass.integer = control,
      .datalen = datalen,
      .data.ptr = (void *) data,
   };

   return bridge_channel_write_frame(bridge_channel, &frame);
}

int ast_bridge_channel_write_hold(struct ast_bridge_channel *bridge_channel, const char *moh_class)
{
   struct ast_json *blob;
   int res;
   size_t datalen;

   if (!ast_strlen_zero(moh_class)) {
      datalen = strlen(moh_class) + 1;

      blob = ast_json_pack("{s: s}",
         "musicclass", moh_class);
   } else {
      moh_class = NULL;
      datalen = 0;
      blob = NULL;
   }

   ast_channel_publish_cached_blob(bridge_channel->chan, ast_channel_hold_type(), blob);

   res = ast_bridge_channel_write_control_data(bridge_channel, AST_CONTROL_HOLD,
      moh_class, datalen);

   ast_json_unref(blob);
   return res;
}

int ast_bridge_channel_write_unhold(struct ast_bridge_channel *bridge_channel)
{
   struct ast_channel *chan = ast_bridge_channel_get_chan(bridge_channel);

   if (!chan) {
      return -1;
   }

   ast_channel_publish_cached_blob(chan, ast_channel_unhold_type(), NULL);
   ao2_ref(chan, -1);

   return ast_bridge_channel_write_control_data(bridge_channel, AST_CONTROL_UNHOLD, NULL, 0);
}

/*!
 * \internal
 * \brief Helper function to kick off a PBX app on a bridge_channel
 */
static int run_app_helper(struct ast_channel *chan, const char *app_name, const char *app_args)
{
   int res = 0;

   if (!strcasecmp("Gosub", app_name)) {
      ast_app_exec_sub(NULL, chan, app_args, 0);
   } else if (!strcasecmp("Macro", app_name)) {
      ast_app_exec_macro(NULL, chan, app_args);
   } else {
      struct ast_app *app;

      app = pbx_findapp(app_name);
      if (!app) {
         ast_log(LOG_WARNING, "Could not find application (%s)\n", app_name);
      } else {
         struct ast_str *substituted_args = ast_str_create(16);

         if (substituted_args) {
            ast_str_substitute_variables(&substituted_args, 0, chan, app_args);
            res = pbx_exec(chan, app, ast_str_buffer(substituted_args));
            ast_free(substituted_args);
         } else {
            ast_log(LOG_WARNING, "Could not substitute application argument variables for %s\n", app_name);
            res = pbx_exec(chan, app, app_args);
         }
      }
   }
   return res;
}

void ast_bridge_channel_run_app(struct ast_bridge_channel *bridge_channel, const char *app_name, const char *app_args, const char *moh_class)
{
   if (moh_class) {
      ast_bridge_channel_write_hold(bridge_channel, moh_class);
   }
   if (run_app_helper(bridge_channel->chan, app_name, S_OR(app_args, ""))) {
      /* Break the bridge if the app returns non-zero. */
      ast_bridge_channel_kick(bridge_channel, AST_CAUSE_NORMAL_CLEARING);
   }
   if (moh_class) {
      ast_bridge_channel_write_unhold(bridge_channel);
   }
}

struct bridge_run_app {
   /*! Offset into app_name[] where the MOH class name starts.  (zero if no MOH) */
   int moh_offset;
   /*! Offset into app_name[] where the application argument string starts. (zero if no arguments) */
   int app_args_offset;
   /*! Application name to run. */
   char app_name[0];
};

/*!
 * \internal
 * \brief Handle the run application bridge action.
 * \since 12.0.0
 *
 * \param bridge_channel Which channel to run the application on.
 * \param data Action frame data to run the application.
 *
 * \return Nothing
 */
static void bridge_channel_run_app(struct ast_bridge_channel *bridge_channel, struct bridge_run_app *data)
{
   ast_bridge_channel_run_app(bridge_channel, data->app_name,
      data->app_args_offset ? &data->app_name[data->app_args_offset] : NULL,
      data->moh_offset ? &data->app_name[data->moh_offset] : NULL);
}

/*!
 * \internal
 * \brief Marshal an application to be executed on a bridge_channel
 */
static int payload_helper_app(ast_bridge_channel_post_action_data post_it,
   struct ast_bridge_channel *bridge_channel, const char *app_name, const char *app_args, const char *moh_class)
{
   struct bridge_run_app *app_data;
   size_t len_name = strlen(app_name) + 1;
   size_t len_args = ast_strlen_zero(app_args) ? 0 : strlen(app_args) + 1;
   size_t len_moh = !moh_class ? 0 : strlen(moh_class) + 1;
   size_t len_data = sizeof(*app_data) + len_name + len_args + len_moh;

   /* Fill in application run frame data. */
   app_data = alloca(len_data);
   app_data->app_args_offset = len_args ? len_name : 0;
   app_data->moh_offset = len_moh ? len_name + len_args : 0;
   strcpy(app_data->app_name, app_name);/* Safe */
   if (len_args) {
      strcpy(&app_data->app_name[app_data->app_args_offset], app_args);/* Safe */
   }
   if (moh_class) {
      strcpy(&app_data->app_name[app_data->moh_offset], moh_class);/* Safe */
   }

   return post_it(bridge_channel, BRIDGE_CHANNEL_ACTION_RUN_APP, app_data, len_data);
}

int ast_bridge_channel_write_app(struct ast_bridge_channel *bridge_channel, const char *app_name, const char *app_args, const char *moh_class)
{
   return payload_helper_app(bridge_channel_write_action_data,
      bridge_channel, app_name, app_args, moh_class);
}

int ast_bridge_channel_queue_app(struct ast_bridge_channel *bridge_channel, const char *app_name, const char *app_args, const char *moh_class)
{
   return payload_helper_app(bridge_channel_queue_action_data,
      bridge_channel, app_name, app_args, moh_class);
}

void ast_bridge_channel_playfile(struct ast_bridge_channel *bridge_channel, ast_bridge_custom_play_fn custom_play, const char *playfile, const char *moh_class)
{
   if (moh_class) {
      ast_bridge_channel_write_hold(bridge_channel, moh_class);
   }
   if (custom_play) {
      custom_play(bridge_channel, playfile);
   } else {
      ast_stream_and_wait(bridge_channel->chan, playfile, AST_DIGIT_NONE);
   }
   if (moh_class) {
      ast_bridge_channel_write_unhold(bridge_channel);
   }

   /*
    * It may be necessary to resume music on hold after we finish
    * playing the announcment.
    */
   if (ast_test_flag(ast_channel_flags(bridge_channel->chan), AST_FLAG_MOH)) {
      const char *latest_musicclass;

      ast_channel_lock(bridge_channel->chan);
      latest_musicclass = ast_strdupa(ast_channel_latest_musicclass(bridge_channel->chan));
      ast_channel_unlock(bridge_channel->chan);
      ast_moh_start(bridge_channel->chan, latest_musicclass, NULL);
   }
}

struct bridge_playfile {
   /*! Call this function to play the playfile. (NULL if normal sound file to play) */
   ast_bridge_custom_play_fn custom_play;
   /*! Offset into playfile[] where the MOH class name starts.  (zero if no MOH)*/
   int moh_offset;
   /*! Filename to play. */
   char playfile[0];
};

/*!
 * \internal
 * \brief Handle the playfile bridge action.
 * \since 12.0.0
 *
 * \param bridge_channel Which channel to play a file on.
 * \param payload Action frame payload to play a file.
 *
 * \return Nothing
 */
static void bridge_channel_playfile(struct ast_bridge_channel *bridge_channel, struct bridge_playfile *payload)
{
   ast_bridge_channel_playfile(bridge_channel, payload->custom_play, payload->playfile,
      payload->moh_offset ? &payload->playfile[payload->moh_offset] : NULL);
}

/*!
 * \internal
 * \brief Marshal a file to be played on a bridge_channel
 */
static int payload_helper_playfile(ast_bridge_channel_post_action_data post_it,
   struct ast_bridge_channel *bridge_channel, ast_bridge_custom_play_fn custom_play, const char *playfile, const char *moh_class)
{
   struct bridge_playfile *payload;
   size_t len_name = strlen(playfile) + 1;
   size_t len_moh = !moh_class ? 0 : strlen(moh_class) + 1;
   size_t len_payload = sizeof(*payload) + len_name + len_moh;

   /* Fill in play file frame data. */
   payload = ast_alloca(len_payload);
   payload->custom_play = custom_play;
   payload->moh_offset = len_moh ? len_name : 0;
   strcpy(payload->playfile, playfile);/* Safe */
   if (moh_class) {
      strcpy(&payload->playfile[payload->moh_offset], moh_class);/* Safe */
   }

   return post_it(bridge_channel, BRIDGE_CHANNEL_ACTION_PLAY_FILE, payload, len_payload);
}

int ast_bridge_channel_write_playfile(struct ast_bridge_channel *bridge_channel, ast_bridge_custom_play_fn custom_play, const char *playfile, const char *moh_class)
{
   return payload_helper_playfile(bridge_channel_write_action_data,
      bridge_channel, custom_play, playfile, moh_class);
}

int ast_bridge_channel_queue_playfile(struct ast_bridge_channel *bridge_channel, ast_bridge_custom_play_fn custom_play, const char *playfile, const char *moh_class)
{
   return payload_helper_playfile(bridge_channel_queue_action_data,
      bridge_channel, custom_play, playfile, moh_class);
}

int ast_bridge_channel_queue_playfile_sync(struct ast_bridge_channel *bridge_channel,
      ast_bridge_custom_play_fn custom_play, const char *playfile, const char *moh_class)
{
   return payload_helper_playfile(bridge_channel_queue_action_data_sync,
      bridge_channel, custom_play, playfile, moh_class);
}

struct bridge_custom_callback {
   /*! Call this function on the bridge channel thread. */
   ast_bridge_custom_callback_fn callback;
   /*! Size of the payload if it exists.  A number otherwise. */
   size_t payload_size;
   /*! Option flags determining how callback is called. */
   unsigned int flags;
   /*! Nonzero if the payload exists. */
   char payload_exists;
   /*! Payload to give to callback. */
   char payload[0];
};

/*!
 * \internal
 * \brief Handle the do custom callback bridge action.
 * \since 12.0.0
 *
 * \param bridge_channel Which channel to call the callback on.
 * \param data Action frame data to call the callback.
 *
 * \return Nothing
 */
static void bridge_channel_do_callback(struct ast_bridge_channel *bridge_channel, struct bridge_custom_callback *data)
{
   if (ast_test_flag(data, AST_BRIDGE_CHANNEL_CB_OPTION_MEDIA)) {
      bridge_channel_suspend(bridge_channel);
      ast_indicate(bridge_channel->chan, AST_CONTROL_SRCUPDATE);
   }
   data->callback(bridge_channel, data->payload_exists ? data->payload : NULL, data->payload_size);
   if (ast_test_flag(data, AST_BRIDGE_CHANNEL_CB_OPTION_MEDIA)) {
      ast_indicate(bridge_channel->chan, AST_CONTROL_SRCUPDATE);
      bridge_channel_unsuspend(bridge_channel);
   }
}

/*!
 * \internal
 * \brief Marshal a custom callback function to be called on a bridge_channel
 */
static int payload_helper_cb(ast_bridge_channel_post_action_data post_it,
   struct ast_bridge_channel *bridge_channel,
   enum ast_bridge_channel_custom_callback_option flags,
   ast_bridge_custom_callback_fn callback, const void *payload, size_t payload_size)
{
   struct bridge_custom_callback *cb_data;
   size_t len_data = sizeof(*cb_data) + (payload ? payload_size : 0);

   /* Sanity check. */
   if (!callback) {
      ast_assert(0);
      return -1;
   }

   /* Fill in custom callback frame data. */
   cb_data = alloca(len_data);
   cb_data->callback = callback;
   cb_data->payload_size = payload_size;
   cb_data->flags = flags;
   cb_data->payload_exists = payload && payload_size;
   if (cb_data->payload_exists) {
      memcpy(cb_data->payload, payload, payload_size);/* Safe */
   }

   return post_it(bridge_channel, BRIDGE_CHANNEL_ACTION_CALLBACK, cb_data, len_data);
}

int ast_bridge_channel_write_callback(struct ast_bridge_channel *bridge_channel,
   enum ast_bridge_channel_custom_callback_option flags,
   ast_bridge_custom_callback_fn callback, const void *payload, size_t payload_size)
{
   return payload_helper_cb(bridge_channel_write_action_data,
      bridge_channel, flags, callback, payload, payload_size);
}

int ast_bridge_channel_queue_callback(struct ast_bridge_channel *bridge_channel,
   enum ast_bridge_channel_custom_callback_option flags,
   ast_bridge_custom_callback_fn callback, const void *payload, size_t payload_size)
{
   return payload_helper_cb(bridge_channel_queue_action_data,
      bridge_channel, flags, callback, payload, payload_size);
}

struct bridge_park {
   int parker_uuid_offset;
   int app_data_offset;
   /* buffer used for holding those strings */
   char parkee_uuid[0];
};

/*!
 * \internal
 * \brief Park a bridge_cahnnel
 */
static void bridge_channel_park(struct ast_bridge_channel *bridge_channel, struct bridge_park *payload)
{
   if (!ast_parking_provider_registered()) {
      ast_log(AST_LOG_WARNING, "Unable to park %s: No parking provider loaded!\n",
         ast_channel_name(bridge_channel->chan));
      return;
   }

   if (ast_parking_park_bridge_channel(bridge_channel, payload->parkee_uuid,
      &payload->parkee_uuid[payload->parker_uuid_offset],
      payload->app_data_offset ? &payload->parkee_uuid[payload->app_data_offset] : NULL)) {
      ast_log(AST_LOG_WARNING, "Error occurred while parking %s\n",
         ast_channel_name(bridge_channel->chan));
   }
}

/*!
 * \internal
 * \brief Marshal a park action onto a bridge_channel
 */
static int payload_helper_park(ast_bridge_channel_post_action_data post_it,
   struct ast_bridge_channel *bridge_channel,
   const char *parkee_uuid,
   const char *parker_uuid,
   const char *app_data)
{
   struct bridge_park *payload;
   size_t len_parkee_uuid = strlen(parkee_uuid) + 1;
   size_t len_parker_uuid = strlen(parker_uuid) + 1;
   size_t len_app_data = !app_data ? 0 : strlen(app_data) + 1;
   size_t len_payload = sizeof(*payload) + len_parker_uuid + len_parkee_uuid + len_app_data;

   payload = alloca(len_payload);
   payload->app_data_offset = len_app_data ? len_parkee_uuid + len_parker_uuid : 0;
   payload->parker_uuid_offset = len_parkee_uuid;
   strcpy(payload->parkee_uuid, parkee_uuid);
   strcpy(&payload->parkee_uuid[payload->parker_uuid_offset], parker_uuid);
   if (app_data) {
      strcpy(&payload->parkee_uuid[payload->app_data_offset], app_data);
   }

   return post_it(bridge_channel, BRIDGE_CHANNEL_ACTION_PARK, payload, len_payload);
}

int ast_bridge_channel_write_park(struct ast_bridge_channel *bridge_channel, const char *parkee_uuid, const char *parker_uuid, const char *app_data)
{
   return payload_helper_park(bridge_channel_write_action_data,
      bridge_channel, parkee_uuid, parker_uuid, app_data);
}

/*!
 * \internal
 * \brief Handle bridge channel interval expiration.
 * \since 12.0.0
 *
 * \param bridge_channel Channel to run expired intervals on.
 *
 * \return Nothing
 */
static void bridge_channel_handle_interval(struct ast_bridge_channel *bridge_channel)
{
   struct ast_heap *interval_hooks;
   struct ast_bridge_hook_timer *hook;
   struct timeval start;
   int chan_suspended = 0;

   interval_hooks = bridge_channel->features->interval_hooks;
   ast_heap_wrlock(interval_hooks);
   start = ast_tvnow();
   while ((hook = ast_heap_peek(interval_hooks, 1))) {
      int interval;
      unsigned int execution_time;

      if (ast_tvdiff_ms(hook->timer.trip_time, start) > 0) {
         ast_debug(1, "Hook %p on %p(%s) wants to happen in the future, stopping our traversal\n",
            hook, bridge_channel, ast_channel_name(bridge_channel->chan));
         break;
      }
      ao2_ref(hook, +1);
      ast_heap_unlock(interval_hooks);

      if (!chan_suspended
         && ast_test_flag(&hook->timer, AST_BRIDGE_HOOK_TIMER_OPTION_MEDIA)) {
         chan_suspended = 1;
         bridge_channel_suspend(bridge_channel);
         ast_indicate(bridge_channel->chan, AST_CONTROL_SRCUPDATE);
      }

      ast_debug(1, "Executing hook %p on %p(%s)\n",
         hook, bridge_channel, ast_channel_name(bridge_channel->chan));
      interval = hook->generic.callback(bridge_channel, hook->generic.hook_pvt);

      ast_heap_wrlock(interval_hooks);
      if (ast_heap_peek(interval_hooks, hook->timer.heap_index) != hook
         || !ast_heap_remove(interval_hooks, hook)) {
         /* Interval hook is already removed from the bridge_channel. */
         ao2_ref(hook, -1);
         continue;
      }
      ao2_ref(hook, -1);

      if (interval < 0) {
         ast_debug(1, "Removed interval hook %p from %p(%s)\n",
            hook, bridge_channel, ast_channel_name(bridge_channel->chan));
         ao2_ref(hook, -1);
         continue;
      }
      if (interval) {
         /* Set new interval for the hook. */
         hook->timer.interval = interval;
      }

      ast_debug(1, "Updating interval hook %p with interval %u on %p(%s)\n",
         hook, hook->timer.interval, bridge_channel,
         ast_channel_name(bridge_channel->chan));

      /* resetting start */
      start = ast_tvnow();

      /*
       * Resetup the interval hook for the next interval.  We may need
       * to skip over any missed intervals because the hook was
       * delayed or took too long.
       */
      execution_time = ast_tvdiff_ms(start, hook->timer.trip_time);
      while (hook->timer.interval < execution_time) {
         execution_time -= hook->timer.interval;
      }
      hook->timer.trip_time = ast_tvadd(start, ast_samp2tv(hook->timer.interval - execution_time, 1000));
      hook->timer.seqno = ast_atomic_fetchadd_int((int *) &bridge_channel->features->interval_sequence, +1);

      if (ast_heap_push(interval_hooks, hook)) {
         /* Could not push the hook back onto the heap. */
         ao2_ref(hook, -1);
      }
   }
   ast_heap_unlock(interval_hooks);

   if (chan_suspended) {
      ast_indicate(bridge_channel->chan, AST_CONTROL_SRCUPDATE);
      bridge_channel_unsuspend(bridge_channel);
   }
}

/*!
 * \internal
 * \brief Write a DTMF stream out to a channel
 */
static int bridge_channel_write_dtmf_stream(struct ast_bridge_channel *bridge_channel, const char *dtmf)
{
   return bridge_channel_write_action_data(bridge_channel,
      BRIDGE_CHANNEL_ACTION_DTMF_STREAM, dtmf, strlen(dtmf) + 1);
}

/*!
 * \internal
 * \brief Indicate to the testsuite a feature was successfully detected.
 *
 * Currently, this function only will relay built-in features to the testsuite,
 * but it could be modified to detect applicationmap items should the need arise.
 *
 * \param chan The channel that activated the feature
 * \param dtmf The DTMF sequence entered to activate the feature
 */
static void testsuite_notify_feature_success(struct ast_channel *chan, const char *dtmf)
{
#ifdef TEST_FRAMEWORK
   char *feature = "unknown";
   struct ast_featuremap_config *featuremap;
   struct ast_features_xfer_config *xfer;

   ast_channel_lock(chan);
   featuremap = ast_get_chan_featuremap_config(chan);
   xfer = ast_get_chan_features_xfer_config(chan);
   ast_channel_unlock(chan);

   if (featuremap) {
      if (!strcmp(dtmf, featuremap->blindxfer)) {
         feature = "blindxfer";
      } else if (!strcmp(dtmf, featuremap->atxfer)) {
         feature = "atxfer";
      } else if (!strcmp(dtmf, featuremap->disconnect)) {
         feature = "disconnect";
      } else if (!strcmp(dtmf, featuremap->automon)) {
         feature = "automon";
      } else if (!strcmp(dtmf, featuremap->automixmon)) {
         feature = "automixmon";
      } else if (!strcmp(dtmf, featuremap->parkcall)) {
         feature = "parkcall";
      }
   }
   if (xfer) {
      if (!strcmp(dtmf, xfer->atxferthreeway)) {
         feature = "atxferthreeway";
      }
   }

   ao2_cleanup(featuremap);
   ao2_cleanup(xfer);

   ast_test_suite_event_notify("FEATURE_DETECTION",
         "Result: success\r\n"
         "Feature: %s", feature);
#endif /* TEST_FRAMEWORK */
}

static int bridge_channel_feature_digit_add(
   struct ast_bridge_channel *bridge_channel, int digit, size_t dtmf_len)
{
   if (dtmf_len < ARRAY_LEN(bridge_channel->dtmf_hook_state.collected) - 1) {
      /* Add the new digit to the DTMF string so we can do our matching */
      bridge_channel->dtmf_hook_state.collected[dtmf_len++] = digit;
      bridge_channel->dtmf_hook_state.collected[dtmf_len] = '\0';

      ast_debug(1, "DTMF feature string on %p(%s) is now '%s'\n",
           bridge_channel, ast_channel_name(bridge_channel->chan),
           bridge_channel->dtmf_hook_state.collected);
   }

   return dtmf_len;
}

static unsigned int bridge_channel_feature_digit_timeout(struct ast_bridge_channel *bridge_channel)
{
   unsigned int digit_timeout;
   struct ast_features_general_config *gen_cfg;

   /* Determine interdigit timeout */
   ast_channel_lock(bridge_channel->chan);
   gen_cfg = ast_get_chan_features_general_config(bridge_channel->chan);
   ast_channel_unlock(bridge_channel->chan);

   if (!gen_cfg) {
      ast_log(LOG_ERROR, "Unable to retrieve features configuration.\n");
      return 3000; /* Pick a reasonable failsafe timeout in ms */
   }

   digit_timeout = gen_cfg->featuredigittimeout;
   ao2_ref(gen_cfg, -1);

   return digit_timeout;
}

void ast_bridge_channel_feature_digit_add(struct ast_bridge_channel *bridge_channel, int digit)
{
   if (digit) {
      bridge_channel_feature_digit_add(
         bridge_channel, digit, strlen(bridge_channel->dtmf_hook_state.collected));
   }
}

void ast_bridge_channel_feature_digit(struct ast_bridge_channel *bridge_channel, int digit)
{
   struct ast_bridge_features *features = bridge_channel->features;
   struct ast_bridge_hook_dtmf *hook = NULL;
   size_t dtmf_len;

   struct sanity_check_of_dtmf_size {
      char check[1 / (ARRAY_LEN(bridge_channel->dtmf_hook_state.collected) == ARRAY_LEN(hook->dtmf.code))];
   };

   dtmf_len = strlen(bridge_channel->dtmf_hook_state.collected);
   if (!dtmf_len && !digit) {
      /* Nothing to do */
      return;
   }

   if (digit) {
      dtmf_len = bridge_channel_feature_digit_add(bridge_channel, digit, dtmf_len);
   }

   while (digit) {
      /* See if a DTMF feature hook matches or can match */
      hook = ao2_find(features->dtmf_hooks, bridge_channel->dtmf_hook_state.collected,
         OBJ_SEARCH_PARTIAL_KEY);
      if (!hook) {
         ast_debug(1, "No DTMF feature hooks on %p(%s) match '%s'\n",
            bridge_channel, ast_channel_name(bridge_channel->chan),
            bridge_channel->dtmf_hook_state.collected);
         break;
      } else if (dtmf_len != strlen(hook->dtmf.code)) {
         unsigned int digit_timeout;
         /* Need more digits to match */
         ao2_ref(hook, -1);
         digit_timeout = bridge_channel_feature_digit_timeout(bridge_channel);
         bridge_channel->dtmf_hook_state.interdigit_timeout =
            ast_tvadd(ast_tvnow(), ast_samp2tv(digit_timeout, 1000));
         return;
      } else {
         int remove_me;
         int already_suspended;

         ast_debug(1, "DTMF feature hook %p matched DTMF string '%s' on %p(%s)\n",
            hook, bridge_channel->dtmf_hook_state.collected, bridge_channel,
            ast_channel_name(bridge_channel->chan));

         /*
          * Clear the collected digits before executing the hook
          * in case the hook starts another sequence.
          */
         bridge_channel->dtmf_hook_state.collected[0] = '\0';

         ast_bridge_channel_lock_bridge(bridge_channel);
         already_suspended = bridge_channel->suspended;
         if (!already_suspended) {
            bridge_channel_internal_suspend_nolock(bridge_channel);
         }
         ast_bridge_unlock(bridge_channel->bridge);
         ast_indicate(bridge_channel->chan, AST_CONTROL_SRCUPDATE);

         /* Execute the matched hook on this channel. */
         remove_me = hook->generic.callback(bridge_channel, hook->generic.hook_pvt);
         if (remove_me) {
            ast_debug(1, "DTMF hook %p is being removed from %p(%s)\n",
               hook, bridge_channel, ast_channel_name(bridge_channel->chan));
            ao2_unlink(features->dtmf_hooks, hook);
         }
         testsuite_notify_feature_success(bridge_channel->chan, hook->dtmf.code);
         ao2_ref(hook, -1);

         ast_indicate(bridge_channel->chan, AST_CONTROL_SRCUPDATE);
         if (!already_suspended) {
            bridge_channel_unsuspend(bridge_channel);
         }

         /*
          * If we are handing the channel off to an external hook for
          * ownership, we are not guaranteed what kind of state it will
          * come back in.  If the channel hungup, we need to detect that
          * here if the hook did not already change the state.
          */
         if (bridge_channel->chan && ast_check_hangup_locked(bridge_channel->chan)) {
            ast_bridge_channel_kick(bridge_channel, 0);
            bridge_channel->dtmf_hook_state.collected[0] = '\0';
            return;
         }

         /* if there is dtmf that has been collected then loop back through,
            but set digit to -1 so it doesn't try to do an add since the dtmf
            is already in the buffer */
         dtmf_len = strlen(bridge_channel->dtmf_hook_state.collected);
         if (!dtmf_len) {
            return;
         }
      }
   }

   if (!digit) {
      ast_debug(1, "DTMF feature string collection on %p(%s) timed out\n",
         bridge_channel, ast_channel_name(bridge_channel->chan));
   }

   /* Timeout or DTMF digit didn't allow a match with any hooks. */
   if (features->dtmf_passthrough) {
      /* Stream the collected DTMF to the other channels. */
      bridge_channel_write_dtmf_stream(bridge_channel,
         bridge_channel->dtmf_hook_state.collected);
   }
   bridge_channel->dtmf_hook_state.collected[0] = '\0';

   ast_test_suite_event_notify("FEATURE_DETECTION", "Result: fail");
}

/*!
 * \internal
 * \brief Handle bridge channel DTMF feature timeout expiration.
 * \since 12.8.0
 *
 * \param bridge_channel Channel to check expired interdigit timer on.
 *
 * \return Nothing
 */
static void bridge_channel_handle_feature_timeout(struct ast_bridge_channel *bridge_channel)
{
   if (!bridge_channel->dtmf_hook_state.collected[0]
      || 0 < ast_tvdiff_ms(bridge_channel->dtmf_hook_state.interdigit_timeout,
         ast_tvnow())) {
      /* Not within a sequence or not timed out. */
      return;
   }

   ast_bridge_channel_feature_digit(bridge_channel, 0);
}

/*!
 * \internal
 * \brief Indicate that a bridge_channel is talking
 */
static void bridge_channel_talking(struct ast_bridge_channel *bridge_channel, int talking)
{
   struct ast_bridge_features *features = bridge_channel->features;
   struct ast_bridge_hook *hook;
   struct ao2_iterator iter;

   /* Run any talk detection hooks. */
   iter = ao2_iterator_init(features->other_hooks, 0);
   for (; (hook = ao2_iterator_next(&iter)); ao2_ref(hook, -1)) {
      int remove_me;
      ast_bridge_talking_indicate_callback talk_cb;

      if (hook->type != AST_BRIDGE_HOOK_TYPE_TALK) {
         continue;
      }
      talk_cb = (ast_bridge_talking_indicate_callback) hook->callback;
      remove_me = talk_cb(bridge_channel, hook->hook_pvt, talking);
      if (remove_me) {
         ast_debug(1, "Talk detection hook %p is being removed from %p(%s)\n",
            hook, bridge_channel, ast_channel_name(bridge_channel->chan));
         ao2_unlink(features->other_hooks, hook);
      }
   }
   ao2_iterator_destroy(&iter);
}

/*! \brief Internal function that plays back DTMF on a bridge channel */
static void bridge_channel_dtmf_stream(struct ast_bridge_channel *bridge_channel, const char *dtmf)
{
   ast_debug(1, "Playing DTMF stream '%s' out to %p(%s)\n",
      dtmf, bridge_channel, ast_channel_name(bridge_channel->chan));
   ast_dtmf_stream(bridge_channel->chan, NULL, dtmf, 0, 0);
}

/*! \brief Data specifying where a blind transfer is going to */
struct blind_transfer_data {
   char exten[AST_MAX_EXTENSION];
   char context[AST_MAX_CONTEXT];
};

/*!
 * \internal
 * \brief Execute after bridge actions on a channel when it leaves a bridge
 */
static void after_bridge_move_channel(struct ast_channel *chan_bridged, void *data)
{
   RAII_VAR(struct ast_channel *, chan_target, data, ao2_cleanup);
   struct ast_party_connected_line connected_target;
   unsigned char connected_line_data[1024];
   int payload_size;

   ast_party_connected_line_init(&connected_target);

   ast_channel_lock(chan_target);
   ast_party_connected_line_copy(&connected_target, ast_channel_connected(chan_target));
   ast_channel_unlock(chan_target);
   ast_party_id_reset(&connected_target.priv);

   if (ast_channel_move(chan_target, chan_bridged)) {
      ast_softhangup(chan_target, AST_SOFTHANGUP_DEV);
      ast_party_connected_line_free(&connected_target);
      return;
   }

   /* The ast_channel_move function will end up updating the connected line information
    * on chan_target to the value we have here, but will not inform it. To ensure that
    * AST_FRAME_READ_ACTION_CONNECTED_LINE_MACRO is executed we wipe it away here. If
    * we don't do this then the change will be considered redundant, since the connected
    * line information is already there (despite the channel not being told).
    */
   ast_channel_lock(chan_target);
   ast_party_connected_line_free(ast_channel_connected_indicated(chan_target));
   ast_party_connected_line_init(ast_channel_connected_indicated(chan_target));
   ast_channel_unlock(chan_target);

   if ((payload_size = ast_connected_line_build_data(connected_line_data,
      sizeof(connected_line_data), &connected_target, NULL)) != -1) {
      struct ast_control_read_action_payload *frame_payload;
      int frame_size;

      frame_size = payload_size + sizeof(*frame_payload);
      frame_payload = ast_alloca(frame_size);
      frame_payload->action = AST_FRAME_READ_ACTION_CONNECTED_LINE_MACRO;
      frame_payload->payload_size = payload_size;
      memcpy(frame_payload->payload, connected_line_data, payload_size);
      ast_queue_control_data(chan_target, AST_CONTROL_READ_ACTION, frame_payload, frame_size);
   }

   /* A connected line update is queued so that if chan_target is remotely involved with
    * anything (such as dialing a channel) the other channel(s) will be informed of the
    * new channel they are involved with.
    */
   ast_channel_lock(chan_target);
   ast_connected_line_copy_from_caller(&connected_target, ast_channel_caller(chan_target));
   ast_channel_queue_connected_line_update(chan_target, &connected_target, NULL);
   ast_channel_unlock(chan_target);

   ast_party_connected_line_free(&connected_target);
}

/*!
 * \internal
 * \brief Execute logic to cleanup when after bridge fails
 */
static void after_bridge_move_channel_fail(enum ast_bridge_after_cb_reason reason, void *data)
{
   RAII_VAR(struct ast_channel *, chan_target, data, ao2_cleanup);

   ast_log(LOG_WARNING, "Unable to complete transfer: %s\n",
      ast_bridge_after_cb_reason_string(reason));
   ast_softhangup(chan_target, AST_SOFTHANGUP_DEV);
}

/*!
 * \internal
 * \brief Perform a blind transfer on a channel in a bridge
 */
static void bridge_channel_blind_transfer(struct ast_bridge_channel *bridge_channel,
      struct blind_transfer_data *blind_data)
{
   ast_async_goto(bridge_channel->chan, blind_data->context, blind_data->exten, 1);
   ast_bridge_channel_kick(bridge_channel, AST_CAUSE_NORMAL_CLEARING);
}

/*!
 * \internal
 * \brief Perform an attended transfer on a channel in a bridge
 */
static void bridge_channel_attended_transfer(struct ast_bridge_channel *bridge_channel,
      const char *target_chan_name)
{
   RAII_VAR(struct ast_channel *, chan_target, NULL, ao2_cleanup);
   RAII_VAR(struct ast_channel *, chan_bridged, NULL, ao2_cleanup);

   chan_target = ast_channel_get_by_name(target_chan_name);
   if (!chan_target) {
      /* Dang, it disappeared somehow */
      ast_bridge_channel_kick(bridge_channel, AST_CAUSE_NORMAL_CLEARING);
      return;
   }

   ast_bridge_channel_lock(bridge_channel);
   chan_bridged = bridge_channel->chan;
   ast_assert(chan_bridged != NULL);
   ao2_ref(chan_bridged, +1);
   ast_bridge_channel_unlock(bridge_channel);

   if (ast_bridge_set_after_callback(chan_bridged, after_bridge_move_channel,
      after_bridge_move_channel_fail, ast_channel_ref(chan_target))) {
      ast_softhangup(chan_target, AST_SOFTHANGUP_DEV);

      /* Release the ref we tried to pass to ast_bridge_set_after_callback(). */
      ast_channel_unref(chan_target);
   }
   ast_bridge_channel_kick(bridge_channel, AST_CAUSE_NORMAL_CLEARING);
}

/*!
 * \internal
 * \brief Handle bridge channel bridge action frame.
 * \since 12.0.0
 *
 * \param bridge_channel Channel to execute the action on.
 * \param action What to do.
 * \param data data from the action.
 *
 * \return Nothing
 */
static void bridge_channel_handle_action(struct ast_bridge_channel *bridge_channel,
   enum bridge_channel_action_type action, void *data)
{
   switch (action) {
   case BRIDGE_CHANNEL_ACTION_DTMF_STREAM:
      bridge_channel_suspend(bridge_channel);
      ast_indicate(bridge_channel->chan, AST_CONTROL_SRCUPDATE);
      bridge_channel_dtmf_stream(bridge_channel, data);
      ast_indicate(bridge_channel->chan, AST_CONTROL_SRCUPDATE);
      bridge_channel_unsuspend(bridge_channel);
      break;
   case BRIDGE_CHANNEL_ACTION_TALKING_START:
   case BRIDGE_CHANNEL_ACTION_TALKING_STOP:
      bridge_channel_talking(bridge_channel,
         action == BRIDGE_CHANNEL_ACTION_TALKING_START);
      break;
   case BRIDGE_CHANNEL_ACTION_PLAY_FILE:
      bridge_channel_suspend(bridge_channel);
      ast_indicate(bridge_channel->chan, AST_CONTROL_SRCUPDATE);
      bridge_channel_playfile(bridge_channel, data);
      ast_indicate(bridge_channel->chan, AST_CONTROL_SRCUPDATE);
      bridge_channel_unsuspend(bridge_channel);
      break;
   case BRIDGE_CHANNEL_ACTION_RUN_APP:
      bridge_channel_suspend(bridge_channel);
      ast_indicate(bridge_channel->chan, AST_CONTROL_SRCUPDATE);
      bridge_channel_run_app(bridge_channel, data);
      ast_indicate(bridge_channel->chan, AST_CONTROL_SRCUPDATE);
      bridge_channel_unsuspend(bridge_channel);
      break;
   case BRIDGE_CHANNEL_ACTION_CALLBACK:
      bridge_channel_do_callback(bridge_channel, data);
      break;
   case BRIDGE_CHANNEL_ACTION_PARK:
      bridge_channel_suspend(bridge_channel);
      ast_indicate(bridge_channel->chan, AST_CONTROL_SRCUPDATE);
      bridge_channel_park(bridge_channel, data);
      ast_indicate(bridge_channel->chan, AST_CONTROL_SRCUPDATE);
      bridge_channel_unsuspend(bridge_channel);
      break;
   case BRIDGE_CHANNEL_ACTION_BLIND_TRANSFER:
      bridge_channel_blind_transfer(bridge_channel, data);
      break;
   case BRIDGE_CHANNEL_ACTION_ATTENDED_TRANSFER:
      bridge_channel_attended_transfer(bridge_channel, data);
      break;
   default:
      break;
   }

   /* While invoking an action it is possible for the channel to be hung up. So
    * that the bridge respects this we check here and if hung up kick it out.
    */
   if (bridge_channel->chan && ast_check_hangup_locked(bridge_channel->chan)) {
      ast_bridge_channel_kick(bridge_channel, 0);
   }
}

/*!
 * \internal
 * \brief Check if a bridge should dissolve and do it.
 * \since 12.0.0
 *
 * \param bridge_channel Channel causing the check.
 *
 * \note On entry, bridge_channel->bridge is already locked.
 *
 * \return Nothing
 */
static void bridge_channel_dissolve_check(struct ast_bridge_channel *bridge_channel)
{
   struct ast_bridge *bridge = bridge_channel->bridge;

   if (bridge->dissolved) {
      return;
   }

   if (!bridge->num_channels
      && ast_test_flag(&bridge->feature_flags, AST_BRIDGE_FLAG_DISSOLVE_EMPTY)) {
      /* Last channel leaving the bridge turns off the lights. */
      bridge_dissolve(bridge, ast_channel_hangupcause(bridge_channel->chan));
      return;
   }

   switch (bridge_channel->state) {
   case BRIDGE_CHANNEL_STATE_END:
      /* Do we need to dissolve the bridge because this channel hung up? */
      if (ast_test_flag(&bridge->feature_flags, AST_BRIDGE_FLAG_DISSOLVE_HANGUP)
         || (bridge_channel->features->usable
            && ast_test_flag(&bridge_channel->features->feature_flags,
               AST_BRIDGE_CHANNEL_FLAG_DISSOLVE_HANGUP))) {
         bridge_dissolve(bridge, ast_channel_hangupcause(bridge_channel->chan));
         return;
      }
      break;
   default:
      break;
   }

   if (bridge->num_lonely && bridge->num_lonely == bridge->num_channels) {
      /*
       * This will start a chain reaction where each channel leaving
       * enters this function and causes the next to leave as long as
       * there aren't non-lonely channels in the bridge.
       */
      ast_bridge_channel_leave_bridge(AST_LIST_FIRST(&bridge->channels),
         BRIDGE_CHANNEL_STATE_END_NO_DISSOLVE,
         ast_channel_hangupcause(bridge_channel->chan));
   }
}

void bridge_channel_internal_pull(struct ast_bridge_channel *bridge_channel)
{
   struct ast_bridge *bridge = bridge_channel->bridge;

   if (!bridge_channel->in_bridge) {
      return;
   }
   bridge_channel->in_bridge = 0;

   ast_debug(1, "Bridge %s: pulling %p(%s)\n",
      bridge->uniqueid, bridge_channel, ast_channel_name(bridge_channel->chan));

   ast_verb(3, "Channel %s left '%s' %s-bridge <%s>\n",
      ast_channel_name(bridge_channel->chan),
      bridge->technology->name,
      bridge->v_table->name,
      bridge->uniqueid);

   if (!bridge_channel->just_joined) {
      /* Tell the bridge technology we are leaving so they tear us down */
      ast_debug(1, "Bridge %s: %p(%s) is leaving %s technology\n",
         bridge->uniqueid, bridge_channel, ast_channel_name(bridge_channel->chan),
         bridge->technology->name);
      if (bridge->technology->leave) {
         bridge->technology->leave(bridge, bridge_channel);
      }
   }

   /* Remove channel from the bridge */
   if (!bridge_channel->suspended) {
      --bridge->num_active;
   }
   if (ast_test_flag(&bridge_channel->features->feature_flags, AST_BRIDGE_CHANNEL_FLAG_LONELY)) {
      --bridge->num_lonely;
   }
   --bridge->num_channels;
   AST_LIST_REMOVE(&bridge->channels, bridge_channel, entry);

   bridge_channel_dissolve_check(bridge_channel);
   bridge->v_table->pull(bridge, bridge_channel);

   ast_bridge_channel_clear_roles(bridge_channel);

   /* If we are not going to be hung up after leaving a bridge, and we were an
    * outgoing channel, clear the outgoing flag.
    */
   if (ast_test_flag(ast_channel_flags(bridge_channel->chan), AST_FLAG_OUTGOING)
       && (ast_channel_is_leaving_bridge(bridge_channel->chan)
           || bridge_channel->state == BRIDGE_CHANNEL_STATE_WAIT)) {
      ast_debug(2, "Channel %s will survive this bridge; clearing outgoing (dialed) flag\n", ast_channel_name(bridge_channel->chan));
      ast_channel_clear_flag(bridge_channel->chan, AST_FLAG_OUTGOING);
   }

   bridge->reconfigured = 1;
   ast_bridge_publish_leave(bridge, bridge_channel->chan);
}

int bridge_channel_internal_push_full(struct ast_bridge_channel *bridge_channel, int optimized)
{
   struct ast_bridge *bridge = bridge_channel->bridge;
   struct ast_bridge_channel *swap;

   ast_assert(!bridge_channel->in_bridge);

   swap = bridge_find_channel(bridge, bridge_channel->swap);
   bridge_channel->swap = NULL;

   if (swap) {
      ast_debug(1, "Bridge %s: pushing %p(%s) by swapping with %p(%s)\n",
         bridge->uniqueid, bridge_channel, ast_channel_name(bridge_channel->chan),
         swap, ast_channel_name(swap->chan));
   } else {
      ast_debug(1, "Bridge %s: pushing %p(%s)\n",
         bridge->uniqueid, bridge_channel, ast_channel_name(bridge_channel->chan));
   }

   /* Add channel to the bridge */
   if (bridge->dissolved
      || bridge_channel->state != BRIDGE_CHANNEL_STATE_WAIT
      || (swap && swap->state != BRIDGE_CHANNEL_STATE_WAIT)
      || bridge->v_table->push(bridge, bridge_channel, swap)) {
      ast_debug(1, "Bridge %s: pushing %p(%s) into bridge failed\n",
         bridge->uniqueid, bridge_channel, ast_channel_name(bridge_channel->chan));
      return -1;
   }

   ast_bridge_channel_establish_roles(bridge_channel);

   if (swap) {
      int dissolve = ast_test_flag(&bridge->feature_flags, AST_BRIDGE_FLAG_DISSOLVE_EMPTY);

      /* This flag is cleared so the act of this channel leaving does not cause it to dissolve if need be */
      ast_clear_flag(&bridge->feature_flags, AST_BRIDGE_FLAG_DISSOLVE_EMPTY);

      if (optimized) {
         bridge_channel_cancel_owed_events(swap);
      }
      ast_bridge_channel_leave_bridge(swap, BRIDGE_CHANNEL_STATE_END_NO_DISSOLVE, 0);
      bridge_channel_internal_pull(swap);

      ast_set2_flag(&bridge->feature_flags, dissolve, AST_BRIDGE_FLAG_DISSOLVE_EMPTY);
   }

   bridge_channel->in_bridge = 1;
   bridge_channel->just_joined = 1;
   AST_LIST_INSERT_TAIL(&bridge->channels, bridge_channel, entry);
   ++bridge->num_channels;
   if (ast_test_flag(&bridge_channel->features->feature_flags, AST_BRIDGE_CHANNEL_FLAG_LONELY)) {
      ++bridge->num_lonely;
   }
   if (!bridge_channel->suspended) {
      ++bridge->num_active;
   }

   ast_verb(3, "Channel %s %s%s%s '%s' %s-bridge <%s>\n",
      ast_channel_name(bridge_channel->chan),
      swap ? "swapped with " : "joined",
      swap ? ast_channel_name(swap->chan) : "",
      swap ? " into" : "",
      bridge->technology->name,
      bridge->v_table->name,
      bridge->uniqueid);

   ast_bridge_publish_enter(bridge, bridge_channel->chan, swap ? swap->chan : NULL);

   /* Clear any BLINDTRANSFER,ATTENDEDTRANSFER and FORWARDERNAME since the transfer has completed. */
   pbx_builtin_setvar_helper(bridge_channel->chan, "BLINDTRANSFER", NULL);
   pbx_builtin_setvar_helper(bridge_channel->chan, "ATTENDEDTRANSFER", NULL);
   pbx_builtin_setvar_helper(bridge_channel->chan, "FORWARDERNAME", NULL);

   /* Wake up the bridge channel thread to reevaluate any interval timers. */
   ast_queue_frame(bridge_channel->chan, &ast_null_frame);

   bridge->reconfigured = 1;
   return 0;
}

int bridge_channel_internal_push(struct ast_bridge_channel *bridge_channel)
{
   return bridge_channel_internal_push_full(bridge_channel, 0);
}

/*!
 * \internal
 * \brief Handle bridge channel control frame action.
 * \since 12.0.0
 *
 * \param bridge_channel Channel to execute the control frame action on.
 * \param fr Control frame to handle.
 *
 * \return Nothing
 */
static void bridge_channel_handle_control(struct ast_bridge_channel *bridge_channel, struct ast_frame *fr)
{
   struct ast_channel *chan;
   struct ast_option_header *aoh;
   int is_caller;

   chan = bridge_channel->chan;
   switch (fr->subclass.integer) {
   case AST_CONTROL_REDIRECTING:
      is_caller = !ast_test_flag(ast_channel_flags(chan), AST_FLAG_OUTGOING);
      if (ast_channel_redirecting_sub(NULL, chan, fr, 1) &&
         ast_channel_redirecting_macro(NULL, chan, fr, is_caller, 1)) {
         ast_indicate_data(chan, fr->subclass.integer, fr->data.ptr, fr->datalen);
      }
      break;
   case AST_CONTROL_CONNECTED_LINE:
      is_caller = !ast_test_flag(ast_channel_flags(chan), AST_FLAG_OUTGOING);
      if (ast_channel_connected_line_sub(NULL, chan, fr, 1) &&
         ast_channel_connected_line_macro(NULL, chan, fr, is_caller, 1)) {
         ast_indicate_data(chan, fr->subclass.integer, fr->data.ptr, fr->datalen);
      }
      break;
   case AST_CONTROL_OPTION:
      /*
       * Forward option Requests, but only ones we know are safe These
       * are ONLY sent by chan_iax2 and I'm not convinced that they
       * are useful. I haven't deleted them entirely because I just am
       * not sure of the ramifications of removing them.
       */
      aoh = fr->data.ptr;
      if (aoh && aoh->flag == AST_OPTION_FLAG_REQUEST) {
         switch (ntohs(aoh->option)) {
         case AST_OPTION_TONE_VERIFY:
         case AST_OPTION_TDD:
         case AST_OPTION_RELAXDTMF:
         case AST_OPTION_AUDIO_MODE:
         case AST_OPTION_DIGIT_DETECT:
         case AST_OPTION_FAX_DETECT:
            ast_channel_setoption(chan, ntohs(aoh->option), aoh->data,
               fr->datalen - sizeof(*aoh), 0);
            break;
         default:
            break;
         }
      }
      break;
   case AST_CONTROL_ANSWER:
      if (ast_channel_state(chan) != AST_STATE_UP) {
         ast_answer(chan);
         ast_bridge_channel_lock_bridge(bridge_channel);
         bridge_channel->bridge->reconfigured = 1;
         bridge_reconfigured(bridge_channel->bridge, 0);
         ast_bridge_unlock(bridge_channel->bridge);
      } else {
         ast_indicate(chan, -1);
      }
      break;
   case AST_CONTROL_MASQUERADE_NOTIFY:
      /* Should never happen. */
      ast_assert(0);
      break;
   case AST_CONTROL_STREAM_TOPOLOGY_CHANGED:
      ast_indicate_data(chan, fr->subclass.integer, fr->data.ptr, fr->datalen);
      break;
   default:
      ast_indicate_data(chan, fr->subclass.integer, fr->data.ptr, fr->datalen);
      break;
   }
}

/*!
 * \internal
 * \brief Ensure text data is zero terminated before sending
 *
 * \param chan Channel to send text to
 * \param f The frame containing the text data to send
 *
 * \return Nothing
 */
static void sendtext_safe(struct ast_channel *chan, const struct ast_frame *f)
{
   if (f->datalen) {
      char *text = f->data.ptr;

      if (text[f->datalen - 1]) {
         /* Not zero terminated, we need to allocate */
         text = ast_strndup(text, f->datalen);
         if (!text) {
            return;
         }
      }

      ast_sendtext(chan, text);

      if (text != f->data.ptr) {
         /* Only free if we allocated */
         ast_free(text);
      }
   } else {
      /* Special case if the frame length is zero (although I
       * am not sure this is possible?) */
      ast_sendtext(chan, "");
   }
}

/*!
 * \internal
 * \brief Handle bridge channel write frame to channel.
 * \since 12.0.0
 *
 * \param bridge_channel Channel to write outgoing frame.
 *
 * \return Nothing
 */
static void bridge_channel_handle_write(struct ast_bridge_channel *bridge_channel)
{
   struct ast_frame *fr;
   struct sync_payload *sync_payload;
   int num;
   struct ast_msg_data *msg;

   ast_bridge_channel_lock(bridge_channel);

   /* It's not good to have unbalanced frames and alert_pipe alerts. */
   ast_assert(!AST_LIST_EMPTY(&bridge_channel->wr_queue));
   if (AST_LIST_EMPTY(&bridge_channel->wr_queue)) {
      /* No frame, flush the alert pipe of excess alerts. */
      ast_log(LOG_WARNING, "Weird.  No frame from bridge for %s to process?\n",
         ast_channel_name(bridge_channel->chan));
      ast_alertpipe_read(bridge_channel->alert_pipe);
      ast_bridge_channel_unlock(bridge_channel);
      return;
   }

   AST_LIST_TRAVERSE_SAFE_BEGIN(&bridge_channel->wr_queue, fr, frame_list) {
      if (bridge_channel->dtmf_hook_state.collected[0]) {
         switch (fr->frametype) {
         case AST_FRAME_BRIDGE_ACTION:
         case AST_FRAME_BRIDGE_ACTION_SYNC:
            /* Defer processing these frames while DTMF is collected. */
            continue;
         default:
            break;
         }
      }
      ast_alertpipe_read(bridge_channel->alert_pipe);
      AST_LIST_REMOVE_CURRENT(frame_list);
      break;
   }
   AST_LIST_TRAVERSE_SAFE_END;

   ast_bridge_channel_unlock(bridge_channel);

   if (!fr) {
      /*
       * Wait some to reduce CPU usage from a tight loop
       * without any wait because we only have deferred
       * frames in the wr_queue.
       */
      usleep(1);
      return;
   }

   switch (fr->frametype) {
   case AST_FRAME_BRIDGE_ACTION:
      bridge_channel_handle_action(bridge_channel, fr->subclass.integer, fr->data.ptr);
      break;
   case AST_FRAME_BRIDGE_ACTION_SYNC:
      sync_payload = fr->data.ptr;
      bridge_channel_handle_action(bridge_channel, fr->subclass.integer, sync_payload->data);
      break;
   case AST_FRAME_CONTROL:
      bridge_channel_handle_control(bridge_channel, fr);
      break;
   case AST_FRAME_NULL:
      break;
   case AST_FRAME_TEXT:
      ast_debug(1, "Sending TEXT frame to '%s': %*.s\n",
         ast_channel_name(bridge_channel->chan), fr->datalen, (char *)fr->data.ptr);
      sendtext_safe(bridge_channel->chan, fr);
      break;
   case AST_FRAME_TEXT_DATA:
      msg = (struct ast_msg_data *)fr->data.ptr;
      ast_debug(1, "Sending TEXT_DATA frame from '%s' to '%s:%s': %s\n",
         ast_msg_data_get_attribute(msg, AST_MSG_DATA_ATTR_FROM),
         ast_msg_data_get_attribute(msg, AST_MSG_DATA_ATTR_TO),
         ast_channel_name(bridge_channel->chan),
         ast_msg_data_get_attribute(msg, AST_MSG_DATA_ATTR_BODY));
      ast_sendtext_data(bridge_channel->chan, msg);
      break;
   default:
      /* Assume that there is no mapped stream for this */
      num = -1;

      if (fr->stream_num > -1) {
         ast_bridge_channel_lock(bridge_channel);
         if (fr->stream_num < (int)AST_VECTOR_SIZE(&bridge_channel->stream_map.to_channel)) {
            num = AST_VECTOR_GET(&bridge_channel->stream_map.to_channel, fr->stream_num);
         }
         ast_bridge_channel_unlock(bridge_channel);

         /* If there is no mapped stream after checking the mapping then there is nowhere
          * to write this frame to, so drop it.
          */
         if (num == -1) {
            break;
         }
      }

      /* Write the frame to the channel. */
      bridge_channel->activity = BRIDGE_CHANNEL_THREAD_SIMPLE;
      ast_write_stream(bridge_channel->chan, num, fr);
      break;
   }
   bridge_frame_free(fr);
}

/*! \brief Internal function to handle DTMF from a channel */
static struct ast_frame *bridge_handle_dtmf(struct ast_bridge_channel *bridge_channel, struct ast_frame *frame)
{
   struct ast_bridge_features *features = bridge_channel->features;
   struct ast_bridge_hook_dtmf *hook = NULL;
   char dtmf[2];

   /*
    * See if we are already matching a DTMF feature hook sequence or
    * if this DTMF matches the beginning of any DTMF feature hooks.
    */
   dtmf[0] = frame->subclass.integer;
   dtmf[1] = '\0';
   if (bridge_channel->dtmf_hook_state.collected[0]
      || (hook = ao2_find(features->dtmf_hooks, dtmf, OBJ_SEARCH_PARTIAL_KEY))) {
      enum ast_frame_type frametype = frame->frametype;

      bridge_frame_free(frame);
      frame = NULL;

      ao2_cleanup(hook);

      switch (frametype) {
      case AST_FRAME_DTMF_BEGIN:
         /* Just eat the frame. */
         break;
      case AST_FRAME_DTMF_END:
         ast_bridge_channel_feature_digit(bridge_channel, dtmf[0]);
         break;
      default:
         /* Unexpected frame type. */
         ast_assert(0);
         break;
      }
#ifdef TEST_FRAMEWORK
   } else if (frame->frametype == AST_FRAME_DTMF_END) {
      /* Only transmit this event on DTMF end or else every DTMF
       * press will result in the event being broadcast twice
       */
      ast_test_suite_event_notify("FEATURE_DETECTION", "Result: fail");
#endif
   }

   return frame;
}

static const char *controls[] = {
   [AST_CONTROL_RINGING] = "RINGING",
   [AST_CONTROL_PROCEEDING] = "PROCEEDING",
   [AST_CONTROL_PROGRESS] = "PROGRESS",
   [AST_CONTROL_BUSY] = "BUSY",
   [AST_CONTROL_CONGESTION] = "CONGESTION",
   [AST_CONTROL_ANSWER] = "ANSWER",
};

/*!
 * \internal
 * \brief Feed notification that a frame is waiting on a channel into the bridging core
 *
 * \param bridge_channel Bridge channel the notification was received on
 */
static void bridge_handle_trip(struct ast_bridge_channel *bridge_channel)
{
   struct ast_frame *frame;
   int blocked;

   if (!ast_strlen_zero(ast_channel_call_forward(bridge_channel->chan))) {
      /* TODO If early bridging is ever used by anything other than ARI,
       * it's important that we actually attempt to handle the call forward
       * attempt, as well as expand features on a bridge channel to allow/disallow
       * call forwarding. For now, all we do is raise an event, showing that
       * a call forward is being attempted.
       */
      ast_channel_publish_dial_forward(NULL, bridge_channel->chan, NULL, NULL, "CANCEL",
         ast_channel_call_forward(bridge_channel->chan));
   }

   if (bridge_channel->features->mute) {
      frame = ast_read_stream_noaudio(bridge_channel->chan);
   } else {
      frame = ast_read_stream(bridge_channel->chan);
   }

   if (!frame) {
      ast_bridge_channel_kick(bridge_channel, 0);
      return;
   }

   if (!ast_channel_is_multistream(bridge_channel->chan)) {
      /* This may not be initialized by non-multistream channel drivers */
      frame->stream_num = -1;
   }

   switch (frame->frametype) {
   case AST_FRAME_CONTROL:
      switch (frame->subclass.integer) {
      case AST_CONTROL_CONGESTION:
      case AST_CONTROL_BUSY:
         ast_channel_publish_dial(NULL, bridge_channel->chan, NULL, controls[frame->subclass.integer]);
         break;
      case AST_CONTROL_HANGUP:
         ast_bridge_channel_kick(bridge_channel, 0);
         bridge_frame_free(frame);
         return;
      case AST_CONTROL_RINGING:
      case AST_CONTROL_PROGRESS:
      case AST_CONTROL_PROCEEDING:
      case AST_CONTROL_ANSWER:
         ast_channel_publish_dial(NULL, bridge_channel->chan, NULL, controls[frame->subclass.integer]);
         break;
      case AST_CONTROL_STREAM_TOPOLOGY_REQUEST_CHANGE:
         ast_bridge_channel_lock_bridge(bridge_channel);
         blocked = bridge_channel->bridge->technology->stream_topology_request_change
            && bridge_channel->bridge->technology->stream_topology_request_change(
               bridge_channel->bridge, bridge_channel);
         ast_bridge_unlock(bridge_channel->bridge);
         if (blocked) {
            /*
             * Topology change was intercepted by the bridge technology
             * so drop frame.
             */
            bridge_frame_free(frame);
            return;
         }
         break;
      case AST_CONTROL_STREAM_TOPOLOGY_CHANGED:
         /*
          * If a stream topology has changed then the bridge_channel's
          * media mapping needs to be updated.
          */
         ast_bridge_channel_lock_bridge(bridge_channel);
         if (bridge_channel->bridge->technology->stream_topology_changed) {
            bridge_channel->bridge->technology->stream_topology_changed(
               bridge_channel->bridge, bridge_channel);
         } else {
            ast_bridge_channel_stream_map(bridge_channel);
         }
         ast_bridge_unlock(bridge_channel->bridge);
         break;
      default:
         break;
      }
      break;
   case AST_FRAME_DTMF_BEGIN:
   case AST_FRAME_DTMF_END:
      frame = bridge_handle_dtmf(bridge_channel, frame);
      if (!frame) {
         return;
      }
      if (!bridge_channel->features->dtmf_passthrough) {
         bridge_frame_free(frame);
         return;
      }
      break;
   default:
      break;
   }

   /* Simply write the frame out to the bridge technology. */
   bridge_channel_write_frame(bridge_channel, frame);
   bridge_frame_free(frame);
}

/*!
 * \internal
 * \brief Determine how long till the next timer interval.
 * \since 12.0.0
 *
 * \param bridge_channel Channel to determine how long can wait.
 *
 * \retval ms Number of milliseconds to wait.
 * \retval -1 to wait forever.
 */
static int bridge_channel_next_interval(struct ast_bridge_channel *bridge_channel)
{
   struct ast_heap *interval_hooks = bridge_channel->features->interval_hooks;
   struct ast_bridge_hook_timer *hook;
   int ms;

   ast_heap_wrlock(interval_hooks);
   hook = ast_heap_peek(interval_hooks, 1);
   if (hook) {
      ms = ast_tvdiff_ms(hook->timer.trip_time, ast_tvnow());
      if (ms < 0) {
         /* Expire immediately.  An interval hook is ready to run. */
         ms = 0;
      }
   } else {
      /* No hook so wait forever. */
      ms = -1;
   }
   ast_heap_unlock(interval_hooks);

   return ms;
}

/*!
 * \internal
 * \brief Determine how long till the DTMF interdigit timeout.
 * \since 12.8.0
 *
 * \param bridge_channel Channel to determine how long can wait.
 *
 * \retval ms Number of milliseconds to wait.
 * \retval -1 to wait forever.
 */
static int bridge_channel_feature_timeout(struct ast_bridge_channel *bridge_channel)
{
   int ms;

   if (bridge_channel->dtmf_hook_state.collected[0]) {
      ms = ast_tvdiff_ms(bridge_channel->dtmf_hook_state.interdigit_timeout,
         ast_tvnow());
      if (ms < 0) {
         /* Expire immediately. */
         ms = 0;
      }
   } else {
      /* Timer is not active so wait forever. */
      ms = -1;
   }

   return ms;
}

/*!
 * \internal
 * \brief Determine how long till a timeout.
 * \since 12.8.0
 *
 * \param bridge_channel Channel to determine how long can wait.
 *
 * \retval ms Number of milliseconds to wait.
 * \retval -1 to wait forever.
 */
static int bridge_channel_next_timeout(struct ast_bridge_channel *bridge_channel)
{
   int ms_interval;
   int ms;

   ms_interval = bridge_channel_next_interval(bridge_channel);
   ms = bridge_channel_feature_timeout(bridge_channel);
   if (ms < 0 || (0 <= ms_interval && ms_interval < ms)) {
      /* Interval hook timeout is next. */
      ms = ms_interval;
   }

   return ms;
}

/*!
 * \internal
 * \brief Wait for something to happen on the bridge channel and handle it.
 * \since 12.0.0
 *
 * \param bridge_channel Channel to wait.
 *
 * \note Each channel does writing/reading in their own thread.
 *
 * \return Nothing
 */
static void bridge_channel_wait(struct ast_bridge_channel *bridge_channel)
{
   int ms;
   int outfd;
   struct ast_channel *chan;

   /* Wait for data to either come from the channel or us to be signaled */
   ast_bridge_channel_lock(bridge_channel);
   if (bridge_channel->state != BRIDGE_CHANNEL_STATE_WAIT) {
   } else if (bridge_channel->suspended) {
/* XXX ASTERISK-21271 the external party use of suspended will go away as will these references because this is the bridge channel thread */
      ast_debug(1, "Bridge %s: %p(%s) is going into a signal wait\n",
         bridge_channel->bridge->uniqueid, bridge_channel,
         ast_channel_name(bridge_channel->chan));
      ast_cond_wait(&bridge_channel->cond, ao2_object_get_lockaddr(bridge_channel));
   } else {
      ast_bridge_channel_unlock(bridge_channel);
      outfd = -1;
      ms = bridge_channel_next_timeout(bridge_channel);
      chan = ast_waitfor_nandfds(&bridge_channel->chan, 1,
         &bridge_channel->alert_pipe[0], 1, NULL, &outfd, &ms);
      if (ast_channel_unbridged(bridge_channel->chan)) {
         ast_channel_set_unbridged(bridge_channel->chan, 0);
         ast_bridge_channel_lock_bridge(bridge_channel);
         bridge_channel->bridge->reconfigured = 1;
         bridge_reconfigured(bridge_channel->bridge, 0);
         ast_bridge_unlock(bridge_channel->bridge);
      }
      ast_bridge_channel_lock(bridge_channel);
      bridge_channel->activity = BRIDGE_CHANNEL_THREAD_FRAME;
      ast_bridge_channel_unlock(bridge_channel);
      if (!bridge_channel->suspended
         && bridge_channel->state == BRIDGE_CHANNEL_STATE_WAIT) {
         if (chan) {
            bridge_handle_trip(bridge_channel);
         } else if (ms == 0) {
            /* An interdigit timeout or interval expired. */
            bridge_channel_handle_feature_timeout(bridge_channel);
            bridge_channel_handle_interval(bridge_channel);
         } else if (-1 < outfd) {
            /*
             * Must do this after checking timeouts or may have
             * an infinite loop due to deferring write queue
             * actions while trying to match DTMF feature hooks.
             */
            bridge_channel_handle_write(bridge_channel);
         }
      }
      bridge_channel->activity = BRIDGE_CHANNEL_THREAD_IDLE;
      return;
   }
   ast_bridge_channel_unlock(bridge_channel);
}

/*!
 * \internal
 * \brief Handle bridge channel join/leave event.
 * \since 12.0.0
 *
 * \param bridge_channel Which channel is involved.
 * \param type Specified join/leave event.
 *
 * \return Nothing
 */
static void bridge_channel_event_join_leave(struct ast_bridge_channel *bridge_channel, enum ast_bridge_hook_type type)
{
   struct ast_bridge_features *features = bridge_channel->features;
   struct ast_bridge_hook *hook;
   struct ao2_iterator iter;

   /* Run the specified hooks. */
   iter = ao2_iterator_init(features->other_hooks, 0);
   for (; (hook = ao2_iterator_next(&iter)); ao2_ref(hook, -1)) {
      if (hook->type == type) {
         break;
      }
   }
   if (hook) {
      /* Found the first specified hook to run. */
      bridge_channel_suspend(bridge_channel);
      ast_indicate(bridge_channel->chan, AST_CONTROL_SRCUPDATE);
      do {
         if (hook->type == type) {
            hook->callback(bridge_channel, hook->hook_pvt);
            ao2_unlink(features->other_hooks, hook);
         }
         ao2_ref(hook, -1);
      } while ((hook = ao2_iterator_next(&iter)));
      ast_indicate(bridge_channel->chan, AST_CONTROL_SRCUPDATE);
      bridge_channel_unsuspend(bridge_channel);
   }
   ao2_iterator_destroy(&iter);
}

int bridge_channel_internal_join(struct ast_bridge_channel *bridge_channel)
{
   int res = 0;
   uint8_t indicate_src_change = 0;
   struct ast_bridge_features *channel_features;
   struct ast_channel *swap;

   ast_debug(1, "Bridge %s: %p(%s) is joining\n",
      bridge_channel->bridge->uniqueid,
      bridge_channel, ast_channel_name(bridge_channel->chan));

   /*
    * Directly locking the bridge is safe here because nobody else
    * knows about this bridge_channel yet.
    */
   ast_bridge_lock(bridge_channel->bridge);

   ast_channel_lock(bridge_channel->chan);

   bridge_channel->read_format = ao2_bump(ast_channel_readformat(bridge_channel->chan));
   bridge_channel->write_format = ao2_bump(ast_channel_writeformat(bridge_channel->chan));

   /* Make sure we're still good to be put into a bridge */
   if (ast_channel_internal_bridge(bridge_channel->chan)
      || ast_test_flag(ast_channel_flags(bridge_channel->chan), AST_FLAG_ZOMBIE)) {
      ast_channel_unlock(bridge_channel->chan);
      ast_bridge_unlock(bridge_channel->bridge);
      ast_debug(1, "Bridge %s: %p(%s) failed to join Bridge\n",
         bridge_channel->bridge->uniqueid,
         bridge_channel,
         ast_channel_name(bridge_channel->chan));
      return -1;
   }
   ast_channel_internal_bridge_set(bridge_channel->chan, bridge_channel->bridge);

   /* Attach features requested by the channel */
   channel_features = ast_channel_feature_hooks_get(bridge_channel->chan);
   if (channel_features) {
      ast_bridge_features_merge(bridge_channel->features, channel_features);
   }
   ast_channel_unlock(bridge_channel->chan);

   /* Add the jitterbuffer if the channel requires it */
   ast_jb_enable_for_channel(bridge_channel->chan);

   if (!bridge_channel->bridge->callid) {
      bridge_channel->bridge->callid = ast_read_threadstorage_callid();
   }

   /* Take the swap channel ref from the bridge_channel struct. */
   swap = bridge_channel->swap;

   if (bridge_channel_internal_push(bridge_channel)) {
      int cause = bridge_channel->bridge->cause;

      ast_bridge_unlock(bridge_channel->bridge);
      ast_bridge_channel_kick(bridge_channel, cause);
      ast_bridge_channel_lock_bridge(bridge_channel);
      ast_bridge_features_remove(bridge_channel->features,
         AST_BRIDGE_HOOK_REMOVE_ON_PULL);
      bridge_channel_dissolve_check(bridge_channel);
      res = -1;
   }
   bridge_reconfigured(bridge_channel->bridge, !bridge_channel->inhibit_colp);

   if (bridge_channel->state == BRIDGE_CHANNEL_STATE_WAIT) {
      /*
       * Indicate a source change since this channel is entering the
       * bridge system only if the bridge technology is not MULTIMIX
       * capable.  The MULTIMIX technology has already done it.
       */
      if (!(bridge_channel->bridge->technology->capabilities
         & AST_BRIDGE_CAPABILITY_MULTIMIX)) {
         indicate_src_change = 1;
      }

      bridge_channel_impart_signal(bridge_channel->chan);
      ast_bridge_unlock(bridge_channel->bridge);

      /* Must release any swap ref after unlocking the bridge. */
      ao2_t_cleanup(swap, "Bridge push with swap successful");
      swap = NULL;

      if (indicate_src_change) {
         ast_indicate(bridge_channel->chan, AST_CONTROL_SRCCHANGE);
      }

      bridge_channel_event_join_leave(bridge_channel, AST_BRIDGE_HOOK_TYPE_JOIN);

      while (bridge_channel->state == BRIDGE_CHANNEL_STATE_WAIT) {
         /* Wait for something to do. */
         bridge_channel_wait(bridge_channel);
      }

      /* Force a timeout on any accumulated DTMF hook digits. */
      ast_bridge_channel_feature_digit(bridge_channel, 0);

      bridge_channel_event_join_leave(bridge_channel, AST_BRIDGE_HOOK_TYPE_LEAVE);
      ast_bridge_channel_lock_bridge(bridge_channel);
   }

   bridge_channel_internal_pull(bridge_channel);
   bridge_channel_settle_owed_events(bridge_channel->bridge, bridge_channel);
   bridge_reconfigured(bridge_channel->bridge, 1);

   /* Remove ourselves if we are the video source */
   ast_bridge_remove_video_src(bridge_channel->bridge, bridge_channel->chan);

   ast_bridge_unlock(bridge_channel->bridge);

   /* Must release any swap ref after unlocking the bridge. */
   ao2_t_cleanup(swap, "Bridge push with swap failed or exited immediately");

   /* Complete any active hold before exiting the bridge. */
   if (ast_channel_hold_state(bridge_channel->chan) == AST_CONTROL_HOLD) {
      ast_debug(1, "Channel %s simulating UNHOLD for bridge end.\n",
         ast_channel_name(bridge_channel->chan));
      ast_indicate(bridge_channel->chan, AST_CONTROL_UNHOLD);
   }

   /* Complete any partial DTMF digit before exiting the bridge. */
   if (ast_channel_sending_dtmf_digit(bridge_channel->chan)) {
      ast_channel_end_dtmf(bridge_channel->chan,
         ast_channel_sending_dtmf_digit(bridge_channel->chan),
         ast_channel_sending_dtmf_tv(bridge_channel->chan), "bridge end");
   }

   /* Complete any T.38 session before exiting the bridge. */
   if (ast_channel_is_t38_active(bridge_channel->chan)) {
      struct ast_control_t38_parameters t38_parameters = {
         .request_response = AST_T38_TERMINATED,
      };

      ast_debug(1, "Channel %s simulating T.38 terminate for bridge end.\n",
         ast_channel_name(bridge_channel->chan));
      ast_indicate_data(bridge_channel->chan, AST_CONTROL_T38_PARAMETERS,
         &t38_parameters, sizeof(t38_parameters));
   }

   /* Indicate a source change since this channel is leaving the bridge system. */
   ast_indicate(bridge_channel->chan, AST_CONTROL_SRCCHANGE);

   /*
    * Wait for any dual redirect to complete.
    *
    * Must be done while "still in the bridge" for ast_async_goto()
    * to work right.
    */
   while (ast_test_flag(ast_channel_flags(bridge_channel->chan), AST_FLAG_BRIDGE_DUAL_REDIRECT_WAIT)) {
      sched_yield();
   }
   ast_channel_lock(bridge_channel->chan);
   ast_channel_internal_bridge_set(bridge_channel->chan, NULL);
   ast_channel_unlock(bridge_channel->chan);

   ast_bridge_channel_restore_formats(bridge_channel);

   return res;
}

int bridge_channel_internal_queue_blind_transfer(struct ast_channel *transferee,
      const char *exten, const char *context,
      transfer_channel_cb new_channel_cb, void *user_data)
{
   RAII_VAR(struct ast_bridge_channel *, transferee_bridge_channel, NULL, ao2_cleanup);
   struct blind_transfer_data blind_data;

   ast_channel_lock(transferee);
   transferee_bridge_channel = ast_channel_get_bridge_channel(transferee);
   ast_channel_unlock(transferee);

   if (!transferee_bridge_channel) {
      return -1;
   }

   if (new_channel_cb) {
      new_channel_cb(transferee, user_data, AST_BRIDGE_TRANSFER_SINGLE_PARTY);
   }

   ast_copy_string(blind_data.exten, exten, sizeof(blind_data.exten));
   ast_copy_string(blind_data.context, context, sizeof(blind_data.context));

   return bridge_channel_queue_action_data(transferee_bridge_channel,
      BRIDGE_CHANNEL_ACTION_BLIND_TRANSFER, &blind_data, sizeof(blind_data));
}

int bridge_channel_internal_queue_attended_transfer(struct ast_channel *transferee,
      struct ast_channel *unbridged_chan)
{
   RAII_VAR(struct ast_bridge_channel *, transferee_bridge_channel, NULL, ao2_cleanup);
   char unbridged_chan_name[AST_CHANNEL_NAME];

   ast_channel_lock(transferee);
   transferee_bridge_channel = ast_channel_get_bridge_channel(transferee);
   ast_channel_unlock(transferee);

   if (!transferee_bridge_channel) {
      return -1;
   }

   ast_copy_string(unbridged_chan_name, ast_channel_name(unbridged_chan),
      sizeof(unbridged_chan_name));

   return bridge_channel_queue_action_data(transferee_bridge_channel,
      BRIDGE_CHANNEL_ACTION_ATTENDED_TRANSFER, unbridged_chan_name,
      sizeof(unbridged_chan_name));
}

int bridge_channel_internal_allows_optimization(struct ast_bridge_channel *bridge_channel)
{
   return bridge_channel->in_bridge
      && AST_LIST_EMPTY(&bridge_channel->wr_queue);
}

/* Destroy elements of the bridge channel structure and the bridge channel structure itself */
static void bridge_channel_destroy(void *obj)
{
   struct ast_bridge_channel *bridge_channel = obj;
   struct ast_frame *fr;

   if (bridge_channel->callid) {
      bridge_channel->callid = 0;
   }

   if (bridge_channel->bridge) {
      ao2_ref(bridge_channel->bridge, -1);
      bridge_channel->bridge = NULL;
   }

   /* Flush any unhandled wr_queue frames. */
   while ((fr = AST_LIST_REMOVE_HEAD(&bridge_channel->wr_queue, frame_list))) {
      bridge_frame_free(fr);
   }
   ast_alertpipe_close(bridge_channel->alert_pipe);

   /* Flush any unhandled deferred_queue frames. */
   while ((fr = AST_LIST_REMOVE_HEAD(&bridge_channel->deferred_queue, frame_list))) {
      ast_frfree(fr);
   }

   ast_cond_destroy(&bridge_channel->cond);

   ao2_cleanup(bridge_channel->write_format);
   ao2_cleanup(bridge_channel->read_format);

   AST_VECTOR_FREE(&bridge_channel->stream_map.to_bridge);
   AST_VECTOR_FREE(&bridge_channel->stream_map.to_channel);
}

struct ast_bridge_channel *bridge_channel_internal_alloc(struct ast_bridge *bridge)
{
   struct ast_bridge_channel *bridge_channel;

   bridge_channel = ao2_alloc(sizeof(struct ast_bridge_channel), bridge_channel_destroy);
   if (!bridge_channel) {
      return NULL;
   }
   ast_cond_init(&bridge_channel->cond, NULL);
   if (ast_alertpipe_init(bridge_channel->alert_pipe)) {
      ao2_ref(bridge_channel, -1);
      return NULL;
   }
   if (bridge) {
      bridge_channel->bridge = bridge;
      ao2_ref(bridge_channel->bridge, +1);
   }

   /* The stream_map is initialized later - see ast_bridge_channel_stream_map */

   return bridge_channel;
}

void ast_bridge_channel_stream_map(struct ast_bridge_channel *bridge_channel)
{
   ast_bridge_channel_lock(bridge_channel);
   ast_channel_lock(bridge_channel->chan);
   ast_stream_topology_map(ast_channel_get_stream_topology(bridge_channel->chan),
      &bridge_channel->bridge->media_types, &bridge_channel->stream_map.to_bridge,
      &bridge_channel->stream_map.to_channel);
   ast_channel_unlock(bridge_channel->chan);
   ast_bridge_channel_unlock(bridge_channel);
}