bridge.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2007 - 2009, Digium, Inc.
 *
 * Joshua Colp <jcolp@digium.com>
 *
 * 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 API
 *
 * \author Joshua Colp <jcolp@digium.com>
 */
 
/*** MODULEINFO
    <support_level>core</support_level>
 ***/
 
/*** DOCUMENTATION
    <manager name="BridgeTechnologyList" language="en_US">
        <synopsis>
            List available bridging technologies and their statuses.
        </synopsis>
        <syntax>
            <xi:include xpointer="xpointer(/docs/manager[@name='Login']/syntax/parameter[@name='ActionID'])" />
        </syntax>
        <description>
            <para>Returns detailed information about the available bridging technologies.</para>
        </description>
        <see-also>
            <ref type="manager">BridgeTechnologySuspend</ref>
            <ref type="manager">BridgeTechnologyUnsuspend</ref>
        </see-also>
    </manager>
    <manager name="BridgeTechnologySuspend" language="en_US">
        <synopsis>
            Suspend a bridging technology.
        </synopsis>
        <syntax>
            <xi:include xpointer="xpointer(/docs/manager[@name='Login']/syntax/parameter[@name='ActionID'])" />
            <parameter name="BridgeTechnology" required="true">
                <para>The name of the bridging technology to suspend.</para>
            </parameter>
        </syntax>
        <description>
            <para>Marks a bridging technology as suspended, which prevents subsequently created bridges from using it.</para>
        </description>
        <see-also>
            <ref type="manager">BridgeTechnologySuspend</ref>
            <ref type="manager">BridgeTechnologyUnsuspend</ref>
        </see-also>
    </manager>
    <manager name="BridgeTechnologyUnsuspend" language="en_US">
        <synopsis>
            Unsuspend a bridging technology.
        </synopsis>
        <syntax>
            <xi:include xpointer="xpointer(/docs/manager[@name='Login']/syntax/parameter[@name='ActionID'])" />
            <parameter name="BridgeTechnology" required="true">
                <para>The name of the bridging technology to unsuspend.</para>
            </parameter>
        </syntax>
        <description>
            <para>Clears a previously suspended bridging technology, which allows subsequently created bridges to use it.</para>
        </description>
        <see-also>
            <ref type="manager">BridgeTechnologyList</ref>
            <ref type="manager">BridgeTechnologySuspend</ref>
        </see-also>
    </manager>
***/
 
#include "asterisk.h"
 
#include "asterisk/logger.h"
#include "asterisk/channel.h"
#include "asterisk/options.h"
#include "asterisk/utils.h"
#include "asterisk/lock.h"
#include "asterisk/linkedlists.h"
#include "asterisk/bridge.h"
#include "asterisk/bridge_internal.h"
#include "asterisk/bridge_channel_internal.h"
#include "asterisk/bridge_features.h"
#include "asterisk/bridge_basic.h"
#include "asterisk/bridge_technology.h"
#include "asterisk/bridge_channel.h"
#include "asterisk/bridge_after.h"
#include "asterisk/stasis_bridges.h"
#include "asterisk/stasis_channels.h"
#include "asterisk/stasis_cache_pattern.h"
#include "asterisk/app.h"
#include "asterisk/file.h"
#include "asterisk/module.h"
#include "asterisk/astobj2.h"
#include "asterisk/pbx.h"
#include "asterisk/test.h"
#include "asterisk/_private.h"
#include "asterisk/heap.h"
#include "asterisk/say.h"
#include "asterisk/timing.h"
#include "asterisk/stringfields.h"
#include "asterisk/musiconhold.h"
#include "asterisk/features.h"
#include "asterisk/cli.h"
#include "asterisk/parking.h"
#include "asterisk/core_local.h"
#include "asterisk/core_unreal.h"
#include "asterisk/causes.h"
 
/*! All bridges container. */
static struct ao2_container *bridges;
 
static AST_RWLIST_HEAD_STATIC(bridge_technologies, ast_bridge_technology);
 
static unsigned int optimization_id;
 
/* Initial starting point for the bridge array of channels */
#define BRIDGE_ARRAY_START 128
 
/* Grow rate of bridge array of channels */
#define BRIDGE_ARRAY_GROW 32
 
/* Variable name - stores peer information about the most recent blind transfer */
#define BLINDTRANSFER "BLINDTRANSFER"
 
/* Variable name - stores peer information about the most recent attended transfer */
#define ATTENDEDTRANSFER "ATTENDEDTRANSFER"
 
static void cleanup_video_mode(struct ast_bridge *bridge);
 
/*! Default DTMF keys for built in features */
static char builtin_features_dtmf[AST_BRIDGE_BUILTIN_END][MAXIMUM_DTMF_FEATURE_STRING];
 
/*! Function handlers for the built in features */
static ast_bridge_hook_callback builtin_features_handlers[AST_BRIDGE_BUILTIN_END];
 
/*! Function handlers for built in interval features */
static ast_bridge_builtin_set_limits_fn builtin_interval_handlers[AST_BRIDGE_BUILTIN_INTERVAL_END];
 
/*! Bridge manager service request */
struct bridge_manager_request {
    /*! List of bridge service requests. */
    AST_LIST_ENTRY(bridge_manager_request) node;
    /*! Refed bridge requesting service. */
    struct ast_bridge *bridge;
};
 
struct bridge_manager_controller {
    /*! Condition, used to wake up the bridge manager thread. */
    ast_cond_t cond;
    /*! Queue of bridge service requests. */
    AST_LIST_HEAD_NOLOCK(, bridge_manager_request) service_requests;
    /*! Manager thread */
    pthread_t thread;
    /*! TRUE if the manager needs to stop. */
    unsigned int stop:1;
};
 
/*! Bridge manager controller. */
static struct bridge_manager_controller *bridge_manager;
 
struct ao2_container *ast_bridges(void)
{
    return ao2_bump(bridges);
}
 
/*!
 * \internal
 * \brief Request service for a bridge from the bridge manager.
 * \since 12.0.0
 *
 * \param bridge Requesting service.
 */
static void bridge_manager_service_req(struct ast_bridge *bridge)
{
    struct bridge_manager_request *request;
 
    ao2_lock(bridge_manager);
    if (bridge_manager->stop) {
        ao2_unlock(bridge_manager);
        return;
    }
 
    /* Create the service request. */
    request = ast_calloc(1, sizeof(*request));
    if (!request) {
        /* Well. This isn't good. */
        ao2_unlock(bridge_manager);
        return;
    }
    ao2_ref(bridge, +1);
    request->bridge = bridge;
 
    /* Put request into the queue and wake the bridge manager. */
    AST_LIST_INSERT_TAIL(&bridge_manager->service_requests, request, node);
    ast_cond_signal(&bridge_manager->cond);
    ao2_unlock(bridge_manager);
}
 
int __ast_bridge_technology_register(struct ast_bridge_technology *technology, struct ast_module *module)
{
    struct ast_bridge_technology *current;
 
    /* Perform a sanity check to make sure the bridge technology conforms to our needed requirements */
    if (ast_strlen_zero(technology->name)
        || !technology->capabilities
        || !technology->write) {
        ast_log(LOG_WARNING, "Bridge technology %s failed registration sanity check.\n",
            technology->name);
        return -1;
    }
 
    AST_RWLIST_WRLOCK(&bridge_technologies);
 
    /* Look for duplicate bridge technology already using this name, or already registered */
    AST_RWLIST_TRAVERSE(&bridge_technologies, current, entry) {
        if ((!strcasecmp(current->name, technology->name)) || (current == technology)) {
            ast_log(LOG_WARNING, "A bridge technology of %s already claims to exist in our world.\n",
                technology->name);
            AST_RWLIST_UNLOCK(&bridge_technologies);
            return -1;
        }
    }
 
    /* Copy module pointer so reference counting can keep the module from unloading */
    technology->mod = module;
 
    /* Find the correct position to insert the technology. */
    AST_RWLIST_TRAVERSE_SAFE_BEGIN(&bridge_technologies, current, entry) {
        /* Put the highest preference tech's first in the list. */
        if (technology->preference >= current->preference) {
            AST_RWLIST_INSERT_BEFORE_CURRENT(technology, entry);
 
            break;
        }
    }
    AST_RWLIST_TRAVERSE_SAFE_END;
 
    if (!current) {
        /* Insert our new bridge technology to the end of the list. */
        AST_RWLIST_INSERT_TAIL(&bridge_technologies, technology, entry);
    }
 
    AST_RWLIST_UNLOCK(&bridge_technologies);
 
    ast_verb(2, "Registered bridge technology %s\n", technology->name);
 
    return 0;
}
 
int ast_bridge_technology_unregister(struct ast_bridge_technology *technology)
{
    struct ast_bridge_technology *current;
 
    AST_RWLIST_WRLOCK(&bridge_technologies);
 
    /* Ensure the bridge technology is registered before removing it */
    AST_RWLIST_TRAVERSE_SAFE_BEGIN(&bridge_technologies, current, entry) {
        if (current == technology) {
            AST_RWLIST_REMOVE_CURRENT(entry);
            ast_verb(2, "Unregistered bridge technology %s\n", technology->name);
            break;
        }
    }
    AST_RWLIST_TRAVERSE_SAFE_END;
 
    AST_RWLIST_UNLOCK(&bridge_technologies);
 
    return current ? 0 : -1;
}
 
/*!
 * \internal
 * \brief Put an action onto the specified bridge. Don't dup the action frame.
 * \since 12.0.0
 *
 * \param bridge What to queue the action on.
 * \param action What to do.
 */
static void bridge_queue_action_nodup(struct ast_bridge *bridge, struct ast_frame *action)
{
    ast_debug(1, "Bridge %s: queueing action type:%u sub:%d\n",
        bridge->uniqueid, action->frametype, action->subclass.integer);
 
    ast_bridge_lock(bridge);
    AST_LIST_INSERT_TAIL(&bridge->action_queue, action, frame_list);
    ast_bridge_unlock(bridge);
    bridge_manager_service_req(bridge);
}
 
int ast_bridge_queue_action(struct ast_bridge *bridge, struct ast_frame *action)
{
    struct ast_frame *dup;
 
    dup = ast_frdup(action);
    if (!dup) {
        return -1;
    }
    bridge_queue_action_nodup(bridge, dup);
    return 0;
}
 
void bridge_dissolve(struct ast_bridge *bridge, int cause)
{
    struct ast_bridge_channel *bridge_channel;
    struct ast_frame action = {
        .frametype = AST_FRAME_BRIDGE_ACTION,
        .subclass.integer = BRIDGE_CHANNEL_ACTION_DEFERRED_DISSOLVING,
    };
 
    if (bridge->dissolved) {
        return;
    }
    bridge->dissolved = 1;
 
    if (cause <= 0) {
        cause = AST_CAUSE_NORMAL_CLEARING;
    }
    bridge->cause = cause;
 
    ast_debug(1, "Bridge %s: dissolving bridge with cause %d(%s)\n",
        bridge->uniqueid, cause, ast_cause2str(cause));
 
    AST_LIST_TRAVERSE(&bridge->channels, bridge_channel, entry) {
        ast_bridge_channel_leave_bridge(bridge_channel,
            BRIDGE_CHANNEL_STATE_END_NO_DISSOLVE, cause);
    }
 
    /* Must defer dissolving bridge because it is already locked. */
    ast_bridge_queue_action(bridge, &action);
}
 
/*!
 * \internal
 * \brief Check if a bridge should dissolve because of a stolen channel and do it.
 * \since 12.0.0
 *
 * \param bridge Bridge to check.
 * \param bridge_channel Stolen channel causing the check.  It is not in the bridge to check and may be in another bridge.
 *
 * \note On entry, bridge and bridge_channel->bridge are already locked.
 */
static void bridge_dissolve_check_stolen(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
{
    if (bridge->dissolved) {
        return;
    }
 
    if (bridge_channel->features->usable
        && ast_test_flag(&bridge_channel->features->feature_flags,
            AST_BRIDGE_CHANNEL_FLAG_DISSOLVE_HANGUP)) {
        /* The stolen channel controlled the bridge it was stolen from. */
        bridge_dissolve(bridge, 0);
        return;
    }
    if (bridge->num_channels < 2
        && ast_test_flag(&bridge->feature_flags, AST_BRIDGE_FLAG_DISSOLVE_HANGUP)) {
        /*
         * The stolen channel has not left enough channels to keep the
         * bridge alive.  Assume the stolen channel hung up.
         */
        bridge_dissolve(bridge, 0);
        return;
    }
}
 
/*!
 * \internal
 * \brief Update connected line information after a bridge has been reconfigured.
 *
 * \param bridge The bridge itself.
 */
static void bridge_reconfigured_connected_line_update(struct ast_bridge *bridge)
{
    struct ast_party_connected_line connected;
    struct ast_bridge_channel *bridge_channel = AST_LIST_FIRST(&bridge->channels), *peer;
    unsigned char data[1024];
    size_t datalen;
 
    if (!bridge_channel ||
        !(bridge->technology->capabilities & (AST_BRIDGE_CAPABILITY_1TO1MIX | AST_BRIDGE_CAPABILITY_NATIVE)) ||
        !(peer = ast_bridge_channel_peer(bridge_channel)) ||
        ast_test_flag(ast_channel_flags(bridge_channel->chan), AST_FLAG_ZOMBIE) ||
        ast_test_flag(ast_channel_flags(peer->chan), AST_FLAG_ZOMBIE) ||
        ast_check_hangup_locked(bridge_channel->chan) ||
        ast_check_hangup_locked(peer->chan)) {
        return;
    }
 
    ast_party_connected_line_init(&connected);
 
    ast_channel_lock(bridge_channel->chan);
    ast_connected_line_copy_from_caller(&connected, ast_channel_caller(bridge_channel->chan));
    ast_channel_unlock(bridge_channel->chan);
 
    if ((datalen = ast_connected_line_build_data(data, sizeof(data), &connected, NULL)) != (size_t) -1) {
        ast_bridge_channel_queue_control_data(peer, AST_CONTROL_CONNECTED_LINE, data, datalen);
    }
 
    ast_channel_lock(peer->chan);
    ast_connected_line_copy_from_caller(&connected, ast_channel_caller(peer->chan));
    ast_channel_unlock(peer->chan);
 
    if ((datalen = ast_connected_line_build_data(data, sizeof(data), &connected, NULL)) != (size_t) -1) {
        ast_bridge_channel_queue_control_data(bridge_channel, AST_CONTROL_CONNECTED_LINE, data, datalen);
    }
 
    ast_party_connected_line_free(&connected);
}
 
/*!
 * \internal
 * \brief Complete joining a channel to the bridge.
 * \since 12.0.0
 *
 * \param bridge What to operate upon.
 * \param bridge_channel What is joining the bridge technology.
 *
 * \note On entry, bridge is already locked.
 */
static void bridge_channel_complete_join(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
{
    /* Tell the bridge technology we are joining so they set us up */
    ast_debug(1, "Bridge %s: %p(%s) is joining %s technology\n",
        bridge->uniqueid, bridge_channel, ast_channel_name(bridge_channel->chan),
        bridge->technology->name);
    if (bridge->technology->join
        && bridge->technology->join(bridge, bridge_channel)) {
        /* We cannot leave the channel partially in the bridge so we must kick it out */
        ast_debug(1, "Bridge %s: %p(%s) failed to join %s technology (Kicking it out)\n",
            bridge->uniqueid, bridge_channel, ast_channel_name(bridge_channel->chan),
            bridge->technology->name);
        bridge_channel->just_joined = 1;
        ast_bridge_channel_leave_bridge(bridge_channel, BRIDGE_CHANNEL_STATE_END, 0);
        return;
    }
 
    bridge_channel->just_joined = 0;
 
    /*
     * When a channel joins the bridge its streams need to be mapped to the bridge's
     * media types vector. This way all streams map to the same media type index for
     * a given 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);
    }
}
 
/*!
 * \internal
 * \brief Complete joining new channels to the bridge.
 * \since 12.0.0
 *
 * \param bridge Check for new channels on this bridge.
 *
 * \note On entry, bridge is already locked.
 */
static void bridge_complete_join(struct ast_bridge *bridge)
{
    struct ast_bridge_channel *bridge_channel;
 
    if (bridge->dissolved) {
        /*
         * No sense in completing the join on channels for a dissolved
         * bridge.  They are just going to be removed soon anyway.
         * However, we do have reason to abort here because the bridge
         * technology may not be able to handle the number of channels
         * still in the bridge.
         */
        return;
    }
 
    AST_LIST_TRAVERSE(&bridge->channels, bridge_channel, entry) {
        bridge_channel_queue_deferred_frames(bridge_channel);
        if (!bridge_channel->just_joined) {
            continue;
        }
        bridge_channel_complete_join(bridge, bridge_channel);
    }
}
 
/*! \brief Helper function used to find the "best" bridge technology given specified capabilities */
static struct ast_bridge_technology *find_best_technology(uint32_t capabilities, struct ast_bridge *bridge)
{
    struct ast_bridge_technology *current;
    struct ast_bridge_technology *best = NULL;
 
    AST_RWLIST_RDLOCK(&bridge_technologies);
    AST_RWLIST_TRAVERSE(&bridge_technologies, current, entry) {
        if (current->suspended) {
            ast_debug(1, "Bridge technology %s is suspended. Skipping.\n",
                current->name);
            continue;
        }
        if (!(current->capabilities & capabilities)) {
            ast_debug(1, "Bridge technology %s does not have any capabilities we want.\n",
                current->name);
            continue;
        }
        if (best && current->preference <= best->preference) {
            ast_debug(1, "Bridge technology %s has less preference than %s (%u <= %u). Skipping.\n",
                current->name, best->name, current->preference, best->preference);
            continue;
        }
        if (current->compatible && !current->compatible(bridge)) {
            ast_debug(1, "Bridge technology %s is not compatible with properties of existing bridge.\n",
                current->name);
            continue;
        }
        if (!ast_module_running_ref(current->mod)) {
            ast_debug(1, "Bridge technology %s is not running, skipping.\n", current->name);
            continue;
        }
        if (best) {
            ast_module_unref(best->mod);
        }
        best = current;
    }
 
    if (best) {
        ast_debug(1, "Chose bridge technology %s\n", best->name);
    }
 
    AST_RWLIST_UNLOCK(&bridge_technologies);
 
    return best;
}
 
struct tech_deferred_destroy {
    struct ast_bridge_technology *tech;
    void *tech_pvt;
};
 
/*!
 * \internal
 * \brief Deferred destruction of bridge tech private structure.
 * \since 12.0.0
 *
 * \param bridge What to execute the action on.
 * \param action Deferred bridge tech destruction.
 *
 * \note On entry, bridge must not be locked.
 */
static void bridge_tech_deferred_destroy(struct ast_bridge *bridge, struct ast_frame *action)
{
    struct tech_deferred_destroy *deferred = action->data.ptr;
    struct ast_bridge dummy_bridge = {
        .technology = deferred->tech,
        .tech_pvt = deferred->tech_pvt,
        .creator = bridge->creator,
        .name = bridge->name,
        .uniqueid = bridge->uniqueid,
        };
 
    ast_debug(1, "Bridge %s: calling %s technology destructor (deferred, dummy)\n",
        dummy_bridge.uniqueid, dummy_bridge.technology->name);
    dummy_bridge.technology->destroy(&dummy_bridge);
    ast_module_unref(dummy_bridge.technology->mod);
}
 
/*!
 * \internal
 * \brief Handle bridge action frame.
 * \since 12.0.0
 *
 * \param bridge What to execute the action on.
 * \param action What to do.
 *
 * \note On entry, bridge is already locked.
 * \note Can be called by the bridge destructor
 */
static void bridge_action_bridge(struct ast_bridge *bridge, struct ast_frame *action)
{
#if 0   /* In case we need to know when the destructor is calling us. */
    int in_destructor = !ao2_ref(bridge, 0);
#endif
 
    switch (action->subclass.integer) {
    case BRIDGE_CHANNEL_ACTION_DEFERRED_TECH_DESTROY:
        ast_bridge_unlock(bridge);
        bridge_tech_deferred_destroy(bridge, action);
        ast_bridge_lock(bridge);
        break;
    case BRIDGE_CHANNEL_ACTION_DEFERRED_DISSOLVING:
        ast_bridge_unlock(bridge);
        bridge->v_table->dissolving(bridge);
        ast_bridge_lock(bridge);
        break;
    default:
        /* Unexpected deferred action type.  Should never happen. */
        ast_assert(0);
        break;
    }
}
 
/*!
 * \internal
 * \brief Do any pending bridge actions.
 * \since 12.0.0
 *
 * \param bridge What to do actions on.
 *
 * \note On entry, bridge is already locked.
 * \note Can be called by the bridge destructor.
 */
static void bridge_handle_actions(struct ast_bridge *bridge)
{
    struct ast_frame *action;
 
    while ((action = AST_LIST_REMOVE_HEAD(&bridge->action_queue, frame_list))) {
        switch (action->frametype) {
        case AST_FRAME_BRIDGE_ACTION:
            bridge_action_bridge(bridge, action);
            break;
        default:
            /* Unexpected deferred frame type.  Should never happen. */
            ast_assert(0);
            break;
        }
        ast_frfree(action);
    }
}
 
static void destroy_bridge(void *obj)
{
    struct ast_bridge *bridge = obj;
 
    ast_debug(1, "Bridge %s: actually destroying %s bridge, nobody wants it anymore\n",
        bridge->uniqueid, bridge->v_table->name);
 
    if (bridge->construction_completed) {
        bridge_topics_destroy(bridge);
    }
 
    /* Do any pending actions in the context of destruction. */
    ast_bridge_lock(bridge);
    bridge_handle_actions(bridge);
    ast_bridge_unlock(bridge);
 
    /* There should not be any channels left in the bridge. */
    ast_assert(AST_LIST_EMPTY(&bridge->channels));
 
    ast_debug(1, "Bridge %s: calling %s bridge destructor\n",
        bridge->uniqueid, bridge->v_table->name);
    bridge->v_table->destroy(bridge);
 
    /* Pass off the bridge to the technology to destroy if needed */
    if (bridge->technology) {
        ast_debug(1, "Bridge %s: calling %s technology stop\n",
            bridge->uniqueid, bridge->technology->name);
        if (bridge->technology->stop) {
            ast_bridge_lock(bridge);
            bridge->technology->stop(bridge);
            ast_bridge_unlock(bridge);
        }
        ast_debug(1, "Bridge %s: calling %s technology destructor\n",
            bridge->uniqueid, bridge->technology->name);
        if (bridge->technology->destroy) {
            bridge->technology->destroy(bridge);
        }
        ast_module_unref(bridge->technology->mod);
        bridge->technology = NULL;
    }
 
    AST_VECTOR_FREE(&bridge->media_types);
 
    bridge->callid = 0;
 
    cleanup_video_mode(bridge);
 
    ast_string_field_free_memory(bridge);
    ao2_cleanup(bridge->current_snapshot);
}
 
struct ast_bridge *bridge_register(struct ast_bridge *bridge)
{
    if (bridge) {
        bridge->construction_completed = 1;
        ast_bridge_lock(bridge);
        ast_bridge_publish_state(bridge);
        ast_bridge_unlock(bridge);
        if (!ao2_link(bridges, bridge)) {
            ast_bridge_destroy(bridge, 0);
            bridge = NULL;
        }
    }
    return bridge;
}
 
struct ast_bridge *bridge_alloc(size_t size, const struct ast_bridge_methods *v_table)
{
    struct ast_bridge *bridge;
 
    /* Check v_table that all methods are present. */
    if (!v_table
        || !v_table->name
        || !v_table->destroy
        || !v_table->dissolving
        || !v_table->push
        || !v_table->pull
        || !v_table->notify_masquerade
        || !v_table->get_merge_priority) {
        ast_log(LOG_ERROR, "Virtual method table for bridge class %s not complete.\n",
            v_table && v_table->name ? v_table->name : "<unknown>");
        ast_assert(0);
        return NULL;
    }
 
    bridge = ao2_alloc(size, destroy_bridge);
    if (!bridge) {
        return NULL;
    }
 
    if (ast_string_field_init(bridge, 80)) {
        ao2_cleanup(bridge);
        return NULL;
    }
 
    bridge->v_table = v_table;
 
    AST_VECTOR_INIT(&bridge->media_types, AST_MEDIA_TYPE_END);
 
    return bridge;
}
 
struct ast_bridge *bridge_base_init(struct ast_bridge *self, uint32_t capabilities, unsigned int flags, const char *creator, const char *name, const char *id)
{
    char uuid_hold[AST_UUID_STR_LEN];
 
    if (!self) {
        return NULL;
    }
 
    if (!ast_strlen_zero(id)) {
        ast_string_field_set(self, uniqueid, id);
    } else {
        ast_uuid_generate_str(uuid_hold, AST_UUID_STR_LEN);
        ast_string_field_set(self, uniqueid, uuid_hold);
    }
    ast_string_field_set(self, creator, creator);
    if (!ast_strlen_zero(creator)) {
        ast_string_field_set(self, name, name);
    }
 
    ast_set_flag(&self->feature_flags, flags);
    self->allowed_capabilities = capabilities;
 
    if (!(flags & AST_BRIDGE_FLAG_INVISIBLE)) {
        if (bridge_topics_init(self) != 0) {
            ast_log(LOG_WARNING, "Bridge %s: Could not initialize topics\n",
                self->uniqueid);
            ao2_ref(self, -1);
            return NULL;
        }
    }
 
    /* Use our helper function to find the "best" bridge technology. */
    self->technology = find_best_technology(capabilities, self);
    if (!self->technology) {
        ast_log(LOG_WARNING, "Bridge %s: Could not create class %s.  No technology to support it.\n",
            self->uniqueid, self->v_table->name);
        ao2_ref(self, -1);
        return NULL;
    }
 
    /* Pass off the bridge to the technology to manipulate if needed */
    ast_debug(1, "Bridge %s: calling %s technology constructor\n",
        self->uniqueid, self->technology->name);
    if (self->technology->create && self->technology->create(self)) {
        ast_log(LOG_WARNING, "Bridge %s: failed to setup bridge technology %s\n",
            self->uniqueid, self->technology->name);
        ao2_ref(self, -1);
        return NULL;
    }
    ast_debug(1, "Bridge %s: calling %s technology start\n",
        self->uniqueid, self->technology->name);
    if (self->technology->start && self->technology->start(self)) {
        ast_log(LOG_WARNING, "Bridge %s: failed to start bridge technology %s\n",
            self->uniqueid, self->technology->name);
        ao2_ref(self, -1);
        return NULL;
    }
 
    if (!(flags & AST_BRIDGE_FLAG_INVISIBLE)) {
        if (!ast_bridge_topic(self)) {
            ao2_ref(self, -1);
            return NULL;
        }
    }
 
    self->creationtime = ast_tvnow();
 
    return self;
}
 
/*!
 * \internal
 * \brief ast_bridge base class destructor.
 * \since 12.0.0
 *
 * \param self Bridge to operate upon.
 *
 * \note Stub because of nothing to do.
 */
static void bridge_base_destroy(struct ast_bridge *self)
{
}
 
/*!
 * \internal
 * \brief The bridge is being dissolved.
 * \since 12.0.0
 *
 * \param self Bridge to operate upon.
 */
static void bridge_base_dissolving(struct ast_bridge *self)
{
    ao2_unlink(bridges, self);
}
 
/*!
 * \internal
 * \brief ast_bridge base push method.
 * \since 12.0.0
 *
 * \param self Bridge to operate upon.
 * \param bridge_channel Bridge channel to push.
 * \param swap Bridge channel to swap places with if not NULL.
 *
 * \note On entry, self is already locked.
 * \note Stub because of nothing to do.
 *
 * \retval 0 on success
 * \retval -1 on failure
 */
static int bridge_base_push(struct ast_bridge *self, struct ast_bridge_channel *bridge_channel, struct ast_bridge_channel *swap)
{
    return 0;
}
 
/*!
 * \internal
 * \brief ast_bridge base pull method.
 * \since 12.0.0
 *
 * \param self Bridge to operate upon.
 * \param bridge_channel Bridge channel to pull.
 *
 * \note On entry, self is already locked.
 */
static void bridge_base_pull(struct ast_bridge *self, struct ast_bridge_channel *bridge_channel)
{
    ast_bridge_features_remove(bridge_channel->features, AST_BRIDGE_HOOK_REMOVE_ON_PULL);
}
 
/*!
 * \internal
 * \brief ast_bridge base notify_masquerade method.
 * \since 12.0.0
 *
 * \param self Bridge to operate upon.
 * \param bridge_channel Bridge channel that was masqueraded.
 *
 * \note On entry, self is already locked.
 */
static void bridge_base_notify_masquerade(struct ast_bridge *self, struct ast_bridge_channel *bridge_channel)
{
    self->reconfigured = 1;
}
 
/*!
 * \internal
 * \brief Get the merge priority of this bridge.
 * \since 12.0.0
 *
 * \param self Bridge to operate upon.
 *
 * \note On entry, self is already locked.
 *
 * \return Merge priority
 */
static int bridge_base_get_merge_priority(struct ast_bridge *self)
{
    return 0;
}
 
/*!
 * \internal
 * \brief ast_bridge base push_peek method.
 * \since 13.2.0
 *
 * \param self Bridge to operate upon.
 * \param bridge_channel Bridge channel to push.
 * \param swap Bridge channel to swap places with if not NULL.
 *
 * \note On entry, self is already locked.
 * \note Stub because of nothing to do.
 *
 * \retval 0 on success
 * \retval -1 on failure
 */
static int bridge_base_push_peek(struct ast_bridge *self, struct ast_bridge_channel *bridge_channel, struct ast_bridge_channel *swap)
{
    return 0;
}
 
struct ast_bridge_methods ast_bridge_base_v_table = {
    .name = "base",
    .destroy = bridge_base_destroy,
    .dissolving = bridge_base_dissolving,
    .push = bridge_base_push,
    .pull = bridge_base_pull,
    .notify_masquerade = bridge_base_notify_masquerade,
    .get_merge_priority = bridge_base_get_merge_priority,
    .push_peek = bridge_base_push_peek,
};
 
struct ast_bridge *ast_bridge_base_new(uint32_t capabilities, unsigned int flags, const char *creator, const char *name, const char *id)
{
    void *bridge;
 
    bridge = bridge_alloc(sizeof(struct ast_bridge), &ast_bridge_base_v_table);
    bridge = bridge_base_init(bridge, capabilities, flags, creator, name, id);
    bridge = bridge_register(bridge);
    return bridge;
}
 
int ast_bridge_destroy(struct ast_bridge *bridge, int cause)
{
    ast_debug(1, "Bridge %s: telling all channels to leave the party\n", bridge->uniqueid);
    ast_bridge_lock(bridge);
    bridge_dissolve(bridge, cause);
    ast_bridge_unlock(bridge);
 
    ao2_ref(bridge, -1);
 
    return 0;
}
 
/*!
 * \internal
 * \brief Perform the smart bridge operation.
 * \since 12.0.0
 *
 * \param bridge Work on this bridge.
 *
 * \details
 * Basically see if a new bridge technology should be used instead
 * of the current one.
 *
 * \note On entry, bridge is already locked.
 *
 * \retval 0 on success.
 * \retval -1 on error.
 */
static int smart_bridge_operation(struct ast_bridge *bridge)
{
    uint32_t new_capabilities;
    struct ast_bridge_technology *new_technology;
    struct ast_bridge_technology *old_technology = bridge->technology;
    struct ast_bridge_channel *bridge_channel;
    struct ast_frame *deferred_action;
    struct ast_bridge dummy_bridge = {
        .technology = bridge->technology,
        .tech_pvt = bridge->tech_pvt,
        .creator = bridge->creator,
        .name = bridge->name,
        .uniqueid = bridge->uniqueid,
    };
 
    if (bridge->dissolved) {
        ast_debug(1, "Bridge %s is dissolved, not performing smart bridge operation.\n",
            bridge->uniqueid);
        return 0;
    }
 
    /* Determine new bridge technology capabilities needed. */
    if (2 < bridge->num_channels) {
        new_capabilities = AST_BRIDGE_CAPABILITY_MULTIMIX;
        new_capabilities &= bridge->allowed_capabilities;
    } else {
        new_capabilities = AST_BRIDGE_CAPABILITY_NATIVE | AST_BRIDGE_CAPABILITY_1TO1MIX;
        new_capabilities &= bridge->allowed_capabilities;
        if (!new_capabilities
            && (bridge->allowed_capabilities & AST_BRIDGE_CAPABILITY_MULTIMIX)) {
            /* Allow switching between different multimix bridge technologies. */
            new_capabilities = AST_BRIDGE_CAPABILITY_MULTIMIX;
        }
    }
 
    /* Find a bridge technology to satisfy the new capabilities. */
    new_technology = find_best_technology(new_capabilities, bridge);
    if (!new_technology) {
        int is_compatible = 0;
 
        if (old_technology->compatible) {
            is_compatible = old_technology->compatible(bridge);
        } else if (old_technology->capabilities & AST_BRIDGE_CAPABILITY_MULTIMIX) {
            is_compatible = 1;
        } else if (bridge->num_channels <= 2
            && (old_technology->capabilities & AST_BRIDGE_CAPABILITY_1TO1MIX)) {
            is_compatible = 1;
        }
 
        if (is_compatible) {
            ast_debug(1, "Bridge %s could not get a new technology, staying with old technology.\n",
                bridge->uniqueid);
            return 0;
        }
        ast_log(LOG_WARNING, "Bridge %s has no technology available to support it.\n",
            bridge->uniqueid);
        return -1;
    }
    if (new_technology == old_technology) {
        ast_debug(1, "Bridge %s is already using the new technology.\n",
            bridge->uniqueid);
        ast_module_unref(old_technology->mod);
        return 0;
    }
 
    if (old_technology->destroy) {
        struct tech_deferred_destroy deferred_tech_destroy = {
            .tech = dummy_bridge.technology,
            .tech_pvt = dummy_bridge.tech_pvt,
        };
        struct ast_frame action = {
            .frametype = AST_FRAME_BRIDGE_ACTION,
            .subclass.integer = BRIDGE_CHANNEL_ACTION_DEFERRED_TECH_DESTROY,
            .data.ptr = &deferred_tech_destroy,
            .datalen = sizeof(deferred_tech_destroy),
        };
 
        /*
         * We need to defer the bridge technology destroy callback
         * because we have the bridge locked.
         */
        deferred_action = ast_frdup(&action);
        if (!deferred_action) {
            ast_module_unref(new_technology->mod);
            return -1;
        }
    } else {
        deferred_action = NULL;
    }
 
    /*
     * We are now committed to changing the bridge technology.  We
     * must not release the bridge lock until we have installed the
     * new bridge technology.
     */
    ast_verb(4, "Bridge %s: switching from %s technology to %s\n",
        bridge->uniqueid, old_technology->name, new_technology->name);
 
    /*
     * Since we are soon going to pass this bridge to a new
     * technology we need to NULL out the tech_pvt pointer but
     * don't worry as it still exists in dummy_bridge, ditto for the
     * old technology.
     */
    bridge->tech_pvt = NULL;
    bridge->technology = new_technology;
 
    /* Setup the new bridge technology. */
    ast_debug(1, "Bridge %s: calling %s technology constructor\n",
        bridge->uniqueid, new_technology->name);
    if (new_technology->create && new_technology->create(bridge)) {
        ast_log(LOG_WARNING, "Bridge %s: failed to setup bridge technology %s\n",
            bridge->uniqueid, new_technology->name);
        bridge->tech_pvt = dummy_bridge.tech_pvt;
        bridge->technology = dummy_bridge.technology;
        ast_module_unref(new_technology->mod);
        return -1;
    }
 
    /* To ensure that things are sane for the old technology move the channels it
     * expects to the dummy bridge
     */
    AST_LIST_TRAVERSE_SAFE_BEGIN(&bridge->channels, bridge_channel, entry) {
        if (bridge_channel->just_joined) {
            continue;
        }
        ast_debug(1, "Bridge %s: moving %p(%s) to dummy bridge temporarily\n",
            bridge->uniqueid, bridge_channel, ast_channel_name(bridge_channel->chan));
        AST_LIST_REMOVE_CURRENT(entry);
        AST_LIST_INSERT_TAIL(&dummy_bridge.channels, bridge_channel, entry);
        dummy_bridge.num_channels++;
        if (ast_test_flag(&bridge_channel->features->feature_flags, AST_BRIDGE_CHANNEL_FLAG_LONELY)) {
            dummy_bridge.num_lonely++;
        }
        if (!bridge_channel->suspended) {
            dummy_bridge.num_active++;
        }
    }
    AST_LIST_TRAVERSE_SAFE_END;
 
    /* Take all the channels out of the old technology */
    AST_LIST_TRAVERSE_SAFE_BEGIN(&dummy_bridge.channels, bridge_channel, entry) {
        ast_debug(1, "Bridge %s: %p(%s) is leaving %s technology (dummy)\n",
            dummy_bridge.uniqueid, bridge_channel, ast_channel_name(bridge_channel->chan),
            old_technology->name);
        if (old_technology->leave) {
            old_technology->leave(&dummy_bridge, bridge_channel);
        }
        AST_LIST_REMOVE_CURRENT(entry);
        AST_LIST_INSERT_TAIL(&bridge->channels, bridge_channel, entry);
        dummy_bridge.num_channels--;
        if (ast_test_flag(&bridge_channel->features->feature_flags, AST_BRIDGE_CHANNEL_FLAG_LONELY)) {
            dummy_bridge.num_lonely--;
        }
        if (!bridge_channel->suspended) {
            dummy_bridge.num_active--;
        }
    }
    AST_LIST_TRAVERSE_SAFE_END;
 
    ast_debug(1, "Bridge %s: calling %s technology stop\n",
        dummy_bridge.uniqueid, old_technology->name);
    if (old_technology->stop) {
        old_technology->stop(&dummy_bridge);
    }
 
    /* Add any new channels or re-add existing channels to the bridge. */
    AST_LIST_TRAVERSE(&bridge->channels, bridge_channel, entry) {
        bridge_channel_complete_join(bridge, bridge_channel);
    }
 
    ast_debug(1, "Bridge %s: calling %s technology start\n",
        bridge->uniqueid, new_technology->name);
    if (new_technology->start && new_technology->start(bridge)) {
        ast_log(LOG_WARNING, "Bridge %s: failed to start bridge technology %s\n",
            bridge->uniqueid, new_technology->name);
    }
 
    /*
     * Now that all the channels have been moved over we need to get
     * rid of all the information the old technology may have left
     * around.
     */
    if (old_technology->destroy) {
        ast_debug(1, "Bridge %s: deferring %s technology destructor\n",
            dummy_bridge.uniqueid, old_technology->name);
        bridge_queue_action_nodup(bridge, deferred_action);
    } else {
        ast_debug(1, "Bridge %s: calling %s technology destructor\n",
            dummy_bridge.uniqueid, old_technology->name);
        ast_module_unref(old_technology->mod);
    }
 
    return 0;
}
 
/*!
 * \internal
 * \brief Bridge channel to check if a BRIDGE_PLAY_SOUND needs to be played.
 * \since 12.0.0
 *
 * \param bridge_channel What to check.
 */
static void check_bridge_play_sound(struct ast_bridge_channel *bridge_channel)
{
    const char *play_file;
 
    ast_channel_lock(bridge_channel->chan);
    play_file = pbx_builtin_getvar_helper(bridge_channel->chan, "BRIDGE_PLAY_SOUND");
    if (!ast_strlen_zero(play_file)) {
        play_file = ast_strdupa(play_file);
        pbx_builtin_setvar_helper(bridge_channel->chan, "BRIDGE_PLAY_SOUND", NULL);
    } else {
        play_file = NULL;
    }
    ast_channel_unlock(bridge_channel->chan);
 
    if (play_file) {
        ast_bridge_channel_queue_playfile(bridge_channel, NULL, play_file, NULL);
    }
}
 
/*!
 * \internal
 * \brief Check for any BRIDGE_PLAY_SOUND channel variables in the bridge.
 * \since 12.0.0
 *
 * \param bridge What to operate on.
 *
 * \note On entry, the bridge is already locked.
 */
static void check_bridge_play_sounds(struct ast_bridge *bridge)
{
    struct ast_bridge_channel *bridge_channel;
 
    AST_LIST_TRAVERSE(&bridge->channels, bridge_channel, entry) {
        check_bridge_play_sound(bridge_channel);
    }
}
 
void ast_bridge_vars_set(struct ast_channel *chan, const char *name, const char *pvtid)
{
    ast_channel_stage_snapshot(chan);
    pbx_builtin_setvar_helper(chan, "BRIDGEPEER", name);
    pbx_builtin_setvar_helper(chan, "BRIDGEPVTCALLID", pvtid);
    ast_channel_stage_snapshot_done(chan);
}
 
/*!
 * \internal
 * \brief Set BRIDGEPEER and BRIDGEPVTCALLID channel variables in a 2 party bridge.
 * \since 12.0.0
 *
 * \param c0 Party of the first part.
 * \param c1 Party of the second part.
 *
 * \note On entry, the bridge is already locked.
 * \note The bridge is expected to have exactly two parties.
 */
static void set_bridge_peer_vars_2party(struct ast_channel *c0, struct ast_channel *c1)
{
    const char *c0_name;
    const char *c1_name;
    const char *c0_pvtid = NULL;
    const char *c1_pvtid = NULL;
#define UPDATE_BRIDGE_VARS_GET(chan, name, pvtid)                                   \
    do {                                                                            \
        name = ast_strdupa(ast_channel_name(chan));                                 \
        if (ast_channel_tech(chan)->get_pvt_uniqueid) {                             \
            pvtid = ast_strdupa(ast_channel_tech(chan)->get_pvt_uniqueid(chan));    \
        }                                                                           \
    } while (0)
 
    ast_channel_lock(c1);
    UPDATE_BRIDGE_VARS_GET(c1, c1_name, c1_pvtid);
    ast_channel_unlock(c1);
 
    ast_channel_lock(c0);
    ast_bridge_vars_set(c0, c1_name, c1_pvtid);
    UPDATE_BRIDGE_VARS_GET(c0, c0_name, c0_pvtid);
    ast_channel_unlock(c0);
 
    ast_channel_lock(c1);
    ast_bridge_vars_set(c1, c0_name, c0_pvtid);
    ast_channel_unlock(c1);
}
 
/*!
 * \internal
 * \brief Fill the BRIDGEPEER value buffer with a comma separated list of channel names.
 * \since 12.0.0
 *
 * \param buf Buffer to fill.  The caller must guarantee the buffer is large enough.
 * \param cur_idx Which index into names[] to skip.
 * \param names Channel names to put in the buffer.
 * \param num_names Number of names in the array.
 */
static void fill_bridgepeer_buf(char *buf, unsigned int cur_idx, const char *names[], unsigned int num_names)
{
    int need_separator = 0;
    unsigned int idx;
    const char *src;
    char *pos;
 
    pos = buf;
    for (idx = 0; idx < num_names; ++idx) {
        if (idx == cur_idx) {
            continue;
        }
 
        if (need_separator) {
            *pos++ = ',';
        }
        need_separator = 1;
 
        /* Copy name into buffer. */
        src = names[idx];
        while (*src) {
            *pos++ = *src++;
        }
    }
    *pos = '\0';
}
 
/*!
 * \internal
 * \brief Set BRIDGEPEER and BRIDGEPVTCALLID channel variables in a multi-party bridge.
 * \since 12.0.0
 *
 * \param bridge What to operate on.
 *
 * \note On entry, the bridge is already locked.
 * \note The bridge is expected to have more than two parties.
 */
static void set_bridge_peer_vars_multiparty(struct ast_bridge *bridge)
{
/*
 * Set a maximum number of channel names for the BRIDGEPEER
 * list.  The plus one is for the current channel which is not
 * put in the list.
 */
#define MAX_BRIDGEPEER_CHANS    (10 + 1)
 
    unsigned int idx;
    unsigned int num_names;
    unsigned int len;
    const char **names;
    char *buf;
    struct ast_bridge_channel *bridge_channel;
 
    /* Get first MAX_BRIDGEPEER_CHANS channel names. */
    num_names = MIN(bridge->num_channels, MAX_BRIDGEPEER_CHANS);
    names = ast_alloca(num_names * sizeof(*names));
    idx = 0;
    AST_LIST_TRAVERSE(&bridge->channels, bridge_channel, entry) {
        if (num_names <= idx) {
            break;
        }
        ast_channel_lock(bridge_channel->chan);
        names[idx++] = ast_strdupa(ast_channel_name(bridge_channel->chan));
        ast_channel_unlock(bridge_channel->chan);
    }
 
    /* Determine maximum buf size needed. */
    len = num_names;
    for (idx = 0; idx < num_names; ++idx) {
        len += strlen(names[idx]);
    }
    buf = ast_alloca(len);
 
    /* Set the bridge channel variables. */
    idx = 0;
    buf[0] = '\0';
    AST_LIST_TRAVERSE(&bridge->channels, bridge_channel, entry) {
        if (idx < num_names) {
            fill_bridgepeer_buf(buf, idx, names, num_names);
        }
        ++idx;
 
        ast_channel_lock(bridge_channel->chan);
        ast_bridge_vars_set(bridge_channel->chan, buf, NULL);
        ast_channel_unlock(bridge_channel->chan);
    }
}
 
/*!
 * \internal
 * \brief Set BRIDGEPEER and BRIDGEPVTCALLID channel variables in a holding bridge.
 * \since 12.0.0
 *
 * \param bridge What to operate on.
 *
 * \note On entry, the bridge is already locked.
 */
static void set_bridge_peer_vars_holding(struct ast_bridge *bridge)
{
    struct ast_bridge_channel *bridge_channel;
 
    AST_LIST_TRAVERSE(&bridge->channels, bridge_channel, entry) {
        ast_channel_lock(bridge_channel->chan);
        ast_bridge_vars_set(bridge_channel->chan, NULL, NULL);
        ast_channel_unlock(bridge_channel->chan);
    }
}
 
/*!
 * \internal
 * \brief Set BRIDGEPEER and BRIDGEPVTCALLID channel variables in the bridge.
 * \since 12.0.0
 *
 * \param bridge What to operate on.
 *
 * \note On entry, the bridge is already locked.
 */
static void set_bridge_peer_vars(struct ast_bridge *bridge)
{
    if (bridge->technology->capabilities & AST_BRIDGE_CAPABILITY_HOLDING) {
        set_bridge_peer_vars_holding(bridge);
        return;
    }
    if (bridge->num_channels < 2) {
        return;
    }
    if (bridge->num_channels == 2) {
        set_bridge_peer_vars_2party(AST_LIST_FIRST(&bridge->channels)->chan,
            AST_LIST_LAST(&bridge->channels)->chan);
    } else {
        set_bridge_peer_vars_multiparty(bridge);
    }
}
 
void bridge_reconfigured(struct ast_bridge *bridge, unsigned int colp_update)
{
    if (!bridge->reconfigured) {
        return;
    }
    bridge->reconfigured = 0;
    if (ast_test_flag(&bridge->feature_flags, AST_BRIDGE_FLAG_SMART)
        && smart_bridge_operation(bridge)) {
        /* Smart bridge failed. */
        bridge_dissolve(bridge, 0);
        return;
    }
    bridge_complete_join(bridge);
 
    if (bridge->dissolved) {
        return;
    }
    check_bridge_play_sounds(bridge);
    set_bridge_peer_vars(bridge);
    ast_bridge_publish_state(bridge);
 
    if (colp_update) {
        bridge_reconfigured_connected_line_update(bridge);
    }
}
 
struct ast_bridge_channel *bridge_find_channel(struct ast_bridge *bridge, struct ast_channel *chan)
{
    struct ast_bridge_channel *bridge_channel;
 
    AST_LIST_TRAVERSE(&bridge->channels, bridge_channel, entry) {
        if (bridge_channel->chan == chan) {
            break;
        }
    }
 
    return bridge_channel;
}
 
void ast_bridge_notify_masquerade(struct ast_channel *chan)
{
    struct ast_bridge_channel *bridge_channel;
    struct ast_bridge *bridge;
 
    /* Safely get the bridge_channel pointer for the chan. */
    ast_channel_lock(chan);
    bridge_channel = ast_channel_get_bridge_channel(chan);
    ast_channel_unlock(chan);
    if (!bridge_channel) {
        /* Not in a bridge */
        return;
    }
 
    ast_bridge_channel_lock_bridge(bridge_channel);
    bridge = bridge_channel->bridge;
    if (bridge_channel == bridge_find_channel(bridge, chan)) {
/*
 * XXX ASTERISK-22366 this needs more work.  The channels need
 * to be made compatible again if the formats change. The
 * bridge_channel thread needs to monitor for this case.
 */
        /* The channel we want to notify is still in a bridge. */
        bridge->v_table->notify_masquerade(bridge, bridge_channel);
        bridge_reconfigured(bridge, 1);
    }
    ast_bridge_unlock(bridge);
    ao2_ref(bridge_channel, -1);
}
 
/*!
 * \brief Internal bridge impart wait condition and associated conditional.
 */
struct bridge_channel_impart_cond {
    AST_LIST_ENTRY(bridge_channel_impart_cond) node;
    /*! Lock for the data structure */
    ast_mutex_t lock;
    /*! Wait condition */
    ast_cond_t cond;
    /*! Wait until done */
    int done;
};
 
AST_LIST_HEAD_NOLOCK(bridge_channel_impart_ds_head, bridge_channel_impart_cond);
 
/*!
 * \internal
 * \brief Signal imparting threads to wake up.
 * \since 13.9.0
 *
 * \param ds_head List of imparting threads to wake up.
 */
static void bridge_channel_impart_ds_head_signal(struct bridge_channel_impart_ds_head *ds_head)
{
    if (ds_head) {
        struct bridge_channel_impart_cond *cond;
 
        while ((cond = AST_LIST_REMOVE_HEAD(ds_head, node))) {
            ast_mutex_lock(&cond->lock);
            cond->done = 1;
            ast_cond_signal(&cond->cond);
            ast_mutex_unlock(&cond->lock);
        }
    }
}
 
static void bridge_channel_impart_ds_head_dtor(void *doomed)
{
    bridge_channel_impart_ds_head_signal(doomed);
    ast_free(doomed);
}
 
/*!
 * \internal
 * \brief Fixup the bridge impart datastore.
 * \since 13.9.0
 *
 * \param data Bridge impart datastore data to fixup from old_chan.
 * \param old_chan The datastore is moving from this channel.
 * \param new_chan The datastore is moving to this channel.
 */
static void bridge_channel_impart_ds_head_fixup(void *data, struct ast_channel *old_chan, struct ast_channel *new_chan)
{
    /*
     * Signal any waiting impart threads.  The masquerade is going to kill
     * old_chan and we don't need to be waiting on new_chan.
     */
    bridge_channel_impart_ds_head_signal(data);
}
 
static const struct ast_datastore_info bridge_channel_impart_ds_info = {
    .type = "bridge-impart-ds",
    .destroy = bridge_channel_impart_ds_head_dtor,
    .chan_fixup = bridge_channel_impart_ds_head_fixup,
};
 
/*!
 * \internal
 * \brief Add impart wait datastore conditional to channel.
 * \since 13.9.0
 *
 * \param chan Channel to add the impart wait conditional.
 * \param cond Imparting conditional to add.
 *
 * \retval 0 on success.
 * \retval -1 on error.
 */
static int bridge_channel_impart_add(struct ast_channel *chan, struct bridge_channel_impart_cond *cond)
{
    struct ast_datastore *datastore;
    struct bridge_channel_impart_ds_head *ds_head;
 
    ast_channel_lock(chan);
 
    datastore = ast_channel_datastore_find(chan, &bridge_channel_impart_ds_info, NULL);
    if (!datastore) {
        datastore = ast_datastore_alloc(&bridge_channel_impart_ds_info, NULL);
        if (!datastore) {
            ast_channel_unlock(chan);
            return -1;
        }
        ds_head = ast_calloc(1, sizeof(*ds_head));
        if (!ds_head) {
            ast_channel_unlock(chan);
            ast_datastore_free(datastore);
            return -1;
        }
        datastore->data = ds_head;
        ast_channel_datastore_add(chan, datastore);
    } else {
        ds_head = datastore->data;
        ast_assert(ds_head != NULL);
    }
 
    AST_LIST_INSERT_TAIL(ds_head, cond, node);
 
    ast_channel_unlock(chan);
    return 0;
}
 
void bridge_channel_impart_signal(struct ast_channel *chan)
{
    struct ast_datastore *datastore;
 
    ast_channel_lock(chan);
    datastore = ast_channel_datastore_find(chan, &bridge_channel_impart_ds_info, NULL);
    if (datastore) {
        bridge_channel_impart_ds_head_signal(datastore->data);
    }
    ast_channel_unlock(chan);
}
 
/*!
 * \internal
 * \brief Block imparting channel thread until signaled.
 * \since 13.9.0
 *
 * \param cond Imparting conditional to wait for.
 */
static void bridge_channel_impart_wait(struct bridge_channel_impart_cond *cond)
{
    ast_mutex_lock(&cond->lock);
    while (!cond->done) {
        ast_cond_wait(&cond->cond, &cond->lock);
    }
    ast_mutex_unlock(&cond->lock);
}
 
/*
 * XXX ASTERISK-21271 make ast_bridge_join() require features to be allocated just like ast_bridge_impart() and not expect the struct back.
 *
 * This change is really going to break ConfBridge.  All other
 * users are easily changed.  However, it is needed so the
 * bridging code can manipulate features on all channels
 * consistently no matter how they joined.
 *
 * Need to update the features parameter doxygen when this
 * change is made to be like ast_bridge_impart().
 */
int ast_bridge_join(struct ast_bridge *bridge,
    struct ast_channel *chan,
    struct ast_channel *swap,
    struct ast_bridge_features *features,
    struct ast_bridge_tech_optimizations *tech_args,
    enum ast_bridge_join_flags flags)
{
    struct ast_bridge_channel *bridge_channel;
    int res = 0;
    SCOPE_TRACE(1, "%s Bridge: %s\n", ast_channel_name(chan), bridge->uniqueid);
 
    bridge_channel = bridge_channel_internal_alloc(bridge);
    if (flags & AST_BRIDGE_JOIN_PASS_REFERENCE) {
        ao2_ref(bridge, -1);
    }
    if (!bridge_channel) {
        ao2_t_cleanup(swap, "Error exit: bridge_channel alloc failed");
        res = -1;
        goto join_exit;
    }
/* XXX ASTERISK-21271 features cannot be NULL when passed in. When it is changed to allocated we can do like ast_bridge_impart() and allocate one. */
    ast_assert(features != NULL);
    if (!features) {
        ao2_ref(bridge_channel, -1);
        ao2_t_cleanup(swap, "Error exit: features is NULL");
        res = -1;
        goto join_exit;
    }
    if (tech_args) {
        bridge_channel->tech_args = *tech_args;
    }
 
    ast_channel_lock(chan);
    if (ast_test_flag(ast_channel_flags(chan), AST_FLAG_ZOMBIE)) {
        res = -1;
    } else {
        ast_channel_internal_bridge_channel_set(chan, bridge_channel);
    }
    ast_channel_unlock(chan);
    bridge_channel->thread = pthread_self();
    bridge_channel->chan = chan;
    bridge_channel->swap = swap;
    bridge_channel->features = features;
    bridge_channel->inhibit_colp = !!(flags & AST_BRIDGE_JOIN_INHIBIT_JOIN_COLP);
 
    /* allow subclass to peek at upcoming push operation */
    if (bridge->v_table->push_peek && !res) {
        struct ast_bridge_channel *bcswap = NULL;
 
        ast_bridge_lock(bridge);
        if (bridge_channel->swap) {
            bcswap = bridge_find_channel(bridge, bridge_channel->swap);
        }
        res = bridge->v_table->push_peek(bridge, bridge_channel, bcswap);
        ast_bridge_unlock(bridge);
    }
 
    if (!res) {
        res = bridge_channel_internal_join(bridge_channel);
    }
 
    /* Cleanup all the data in the bridge channel after it leaves the bridge. */
    ast_channel_lock(chan);
    ast_channel_internal_bridge_channel_set(chan, NULL);
    ast_channel_unlock(chan);
    /* Due to a race condition, we lock the bridge channel here for ast_bridge_channel_get_chan */
    ao2_lock(bridge_channel);
    bridge_channel->chan = NULL;
    ao2_unlock(bridge_channel);
    /* If bridge_channel->swap is not NULL then the join failed. */
    ao2_t_cleanup(bridge_channel->swap, "Bridge complete: join failed");
    bridge_channel->swap = NULL;
    bridge_channel->features = NULL;
 
    ao2_ref(bridge_channel, -1);
 
join_exit:
    ast_bridge_run_after_callback(chan);
    bridge_channel_impart_signal(chan);
    if (!(ast_channel_softhangup_internal_flag(chan) & AST_SOFTHANGUP_ASYNCGOTO)
        && !ast_bridge_setup_after_goto(chan)) {
        /* Claim the after bridge goto is an async goto destination. */
        ast_channel_lock(chan);
        ast_softhangup_nolock(chan, AST_SOFTHANGUP_ASYNCGOTO);
        ast_channel_unlock(chan);
    }
    return res;
}
 
/*! \brief Thread responsible for imparted bridged channels to be departed */
static void *bridge_channel_depart_thread(void *data)
{
    struct ast_bridge_channel *bridge_channel = data;
    int res = 0;
 
    if (bridge_channel->callid) {
        ast_callid_threadassoc_add(bridge_channel->callid);
    }
 
    res = bridge_channel_internal_join(bridge_channel);
 
    /*
     * cleanup
     *
     * If bridge_channel->swap is not NULL then the join failed.
     */
    ao2_t_cleanup(bridge_channel->swap, "Bridge complete: Departable impart join failed");
    bridge_channel->swap = NULL;
    ast_bridge_features_destroy(bridge_channel->features);
    bridge_channel->features = NULL;
 
    ast_bridge_discard_after_callback(bridge_channel->chan,
        res ? AST_BRIDGE_AFTER_CB_REASON_IMPART_FAILED : AST_BRIDGE_AFTER_CB_REASON_DEPART);
    /* If join failed there will be impart threads waiting. */
    bridge_channel_impart_signal(bridge_channel->chan);
    ast_bridge_discard_after_goto(bridge_channel->chan);
 
    return NULL;
}
 
/*! \brief Thread responsible for independent imparted bridged channels */
static void *bridge_channel_ind_thread(void *data)
{
    struct ast_bridge_channel *bridge_channel = data;
    struct ast_channel *chan;
 
    if (bridge_channel->callid) {
        ast_callid_threadassoc_add(bridge_channel->callid);
    }
 
    bridge_channel_internal_join(bridge_channel);
    chan = bridge_channel->chan;
 
    /* cleanup */
    ast_channel_lock(chan);
    ast_channel_internal_bridge_channel_set(chan, NULL);
    ast_channel_unlock(chan);
    /* Lock here for ast_bridge_channel_get_chan */
    ao2_lock(bridge_channel);
    bridge_channel->chan = NULL;
    ao2_unlock(bridge_channel);
    /* If bridge_channel->swap is not NULL then the join failed. */
    ao2_t_cleanup(bridge_channel->swap, "Bridge complete: Independent impart join failed");
    bridge_channel->swap = NULL;
    ast_bridge_features_destroy(bridge_channel->features);
    bridge_channel->features = NULL;
 
    ao2_ref(bridge_channel, -1);
 
    ast_bridge_run_after_callback(chan);
    /* If join failed there will be impart threads waiting. */
    bridge_channel_impart_signal(chan);
    ast_bridge_run_after_goto(chan);
    return NULL;
}
 
static int bridge_impart_internal(struct ast_bridge *bridge,
    struct ast_channel *chan,
    struct ast_channel *swap,
    struct ast_bridge_features *features,
    enum ast_bridge_impart_flags flags,
    struct bridge_channel_impart_cond *cond)
{
    int res = 0;
    struct ast_bridge_channel *bridge_channel;
 
    /* Imparted channels cannot have a PBX. */
    if (ast_channel_pbx(chan)) {
        ast_log(AST_LOG_WARNING, "Channel %s has a PBX thread and cannot be imparted into bridge %s\n",
            ast_channel_name(chan), bridge->uniqueid);
        ast_bridge_features_destroy(features);
        return -1;
    }
 
    /* Supply an empty features structure if the caller did not. */
    if (!features) {
        features = ast_bridge_features_new();
        if (!features) {
            return -1;
        }
    }
 
    /* Try to allocate a structure for the bridge channel */
    bridge_channel = bridge_channel_internal_alloc(bridge);
    if (!bridge_channel) {
        ast_bridge_features_destroy(features);
        return -1;
    }
 
    ast_channel_lock(chan);
    if (ast_test_flag(ast_channel_flags(chan), AST_FLAG_ZOMBIE)) {
        ast_log(AST_LOG_NOTICE, "Channel %s is a zombie and cannot be imparted into bridge %s\n",
            ast_channel_name(chan), bridge->uniqueid);
        res = -1;
    } else {
        ast_channel_internal_bridge_channel_set(chan, bridge_channel);
    }
    ast_channel_unlock(chan);
    bridge_channel->chan = chan;
    bridge_channel->swap = ao2_t_bump(swap, "Setting up bridge impart");
    bridge_channel->features = features;
    bridge_channel->inhibit_colp = !!(flags & AST_BRIDGE_IMPART_INHIBIT_JOIN_COLP);
    bridge_channel->depart_wait =
        (flags & AST_BRIDGE_IMPART_CHAN_MASK) == AST_BRIDGE_IMPART_CHAN_DEPARTABLE;
    bridge_channel->callid = ast_read_threadstorage_callid();
 
    /* allow subclass to peek at swap channel before it can hangup */
    if (bridge->v_table->push_peek && !res) {
        struct ast_bridge_channel *bcswap = NULL;
 
        ast_bridge_lock(bridge);
        if (bridge_channel->swap) {
            bcswap = bridge_find_channel(bridge, bridge_channel->swap);
        }
        res = bridge->v_table->push_peek(bridge, bridge_channel, bcswap);
        ast_bridge_unlock(bridge);
    }
 
    /* Actually create the thread that will handle the channel */
    if (!res) {
        res = bridge_channel_impart_add(chan, cond);
    }
    if (!res) {
        if ((flags & AST_BRIDGE_IMPART_CHAN_MASK) == AST_BRIDGE_IMPART_CHAN_INDEPENDENT) {
            res = ast_pthread_create_detached(&bridge_channel->thread, NULL,
                bridge_channel_ind_thread, bridge_channel);
        } else {
            res = ast_pthread_create(&bridge_channel->thread, NULL,
                bridge_channel_depart_thread, bridge_channel);
        }
 
        if (!res) {
            bridge_channel_impart_wait(cond);
        }
    }
 
    if (res) {
        /* cleanup */
        ast_channel_lock(chan);
        ast_channel_internal_bridge_channel_set(chan, NULL);
        ast_channel_unlock(chan);
        /* Lock here for ast_bridge_channel_get_chan */
        ao2_lock(bridge_channel);
        bridge_channel->chan = NULL;
        ao2_unlock(bridge_channel);
        ao2_t_cleanup(bridge_channel->swap, "Bridge complete: Impart failed");
        bridge_channel->swap = NULL;
        ast_bridge_features_destroy(bridge_channel->features);
        bridge_channel->features = NULL;
 
        ao2_ref(bridge_channel, -1);
        return -1;
    }
 
    return 0;
}
 
int ast_bridge_impart(struct ast_bridge *bridge,
    struct ast_channel *chan,
    struct ast_channel *swap,
    struct ast_bridge_features *features,
    enum ast_bridge_impart_flags flags)
{
    struct bridge_channel_impart_cond cond = {
        .done = 0,
    };
    int res;
    SCOPE_TRACE(1, "%s Bridge: %s\n", ast_channel_name(chan), bridge->uniqueid);
 
    ast_mutex_init(&cond.lock);
    ast_cond_init(&cond.cond, NULL);
 
    res = bridge_impart_internal(bridge, chan, swap, features, flags, &cond);
    if (res) {
        /* Impart failed.  Signal any other waiting impart threads */
        ast_bridge_discard_after_callback(chan, AST_BRIDGE_AFTER_CB_REASON_IMPART_FAILED);
        bridge_channel_impart_signal(chan);
    }
 
    ast_cond_destroy(&cond.cond);
    ast_mutex_destroy(&cond.lock);
 
    return res;
}
 
int ast_bridge_depart(struct ast_channel *chan)
{
    struct ast_bridge_channel *bridge_channel;
    int departable;
    SCOPE_TRACE(1, "%s\n", ast_channel_name(chan));
 
    ast_channel_lock(chan);
    bridge_channel = ast_channel_internal_bridge_channel(chan);
    departable = bridge_channel && bridge_channel->depart_wait;
    ast_channel_unlock(chan);
    if (!departable) {
        ast_log(LOG_ERROR, "Channel %s cannot be departed.\n",
            ast_channel_name(chan));
        /*
         * Should never happen.  It likely means that
         * ast_bridge_depart() is called by two threads for the same
         * channel, the channel was never imparted to be departed, or it
         * has already been departed.
         */
        ast_assert(0);
        return -1;
    }
 
    /*
     * We are claiming the bridge_channel reference held by
     * bridge_channel_depart_thread().
     */
 
    ast_bridge_channel_leave_bridge(bridge_channel,
        BRIDGE_CHANNEL_STATE_END_NO_DISSOLVE, AST_CAUSE_NORMAL_CLEARING);
 
    /* Wait for the depart thread to die */
    ast_debug(1, "Waiting for %p(%s) bridge thread to die.\n",
        bridge_channel, ast_channel_name(bridge_channel->chan));
    pthread_join(bridge_channel->thread, NULL);
 
    ast_channel_lock(chan);
    ast_channel_internal_bridge_channel_set(chan, NULL);
    ast_channel_unlock(chan);
 
    /* We can get rid of the bridge_channel after the depart thread has died. */
    ao2_ref(bridge_channel, -1);
    return 0;
}
 
int ast_bridge_remove(struct ast_bridge *bridge, struct ast_channel *chan)
{
    struct ast_bridge_channel *bridge_channel;
 
    ast_debug(1, "Removing channel %s from bridge %s\n",
        ast_channel_name(chan), bridge->uniqueid);
 
    ast_bridge_lock(bridge);
 
    /* Try to find the channel that we want to remove */
    if (!(bridge_channel = bridge_find_channel(bridge, chan))) {
        ast_bridge_unlock(bridge);
        return -1;
    }
 
    ast_bridge_channel_leave_bridge(bridge_channel,
        BRIDGE_CHANNEL_STATE_END_NO_DISSOLVE, AST_CAUSE_NORMAL_CLEARING);
 
    ast_bridge_unlock(bridge);
 
    return 0;
}
 
static void kick_it(struct ast_bridge_channel *bridge_channel, const void *payload, size_t payload_size)
{
    ast_bridge_channel_kick(bridge_channel, AST_CAUSE_NORMAL_CLEARING);
}
 
int ast_bridge_kick(struct ast_bridge *bridge, struct ast_channel *chan)
{
    struct ast_bridge_channel *bridge_channel;
    int res;
 
    ast_bridge_lock(bridge);
 
    /* Try to find the channel that we want to kick. */
    if (!(bridge_channel = bridge_find_channel(bridge, chan))) {
        ast_bridge_unlock(bridge);
        return -1;
    }
 
    res = ast_bridge_channel_queue_callback(bridge_channel, 0, kick_it, NULL, 0);
 
    ast_bridge_unlock(bridge);
 
    return res;
}
 
/*!
 * \internal
 * \brief Point the bridge_channel to a new bridge.
 * \since 12.0.0
 *
 * \param bridge_channel What is to point to a new bridge.
 * \param new_bridge Where the bridge channel should point.
 */
static void bridge_channel_change_bridge(struct ast_bridge_channel *bridge_channel, struct ast_bridge *new_bridge)
{
    struct ast_bridge *old_bridge;
 
    ao2_ref(new_bridge, +1);
    ast_bridge_channel_lock(bridge_channel);
    ast_channel_lock(bridge_channel->chan);
    old_bridge = bridge_channel->bridge;
    bridge_channel->bridge = new_bridge;
    ast_channel_internal_bridge_set(bridge_channel->chan, new_bridge);
    ast_channel_unlock(bridge_channel->chan);
    ast_bridge_channel_unlock(bridge_channel);
    ao2_ref(old_bridge, -1);
}
 
static void bridge_channel_moving(struct ast_bridge_channel *bridge_channel, struct ast_bridge *src, struct ast_bridge *dst)
{
    struct ast_bridge_features *features = bridge_channel->features;
    struct ast_bridge_hook *hook;
    struct ao2_iterator iter;
 
    /* Run any moving hooks. */
    iter = ao2_iterator_init(features->other_hooks, 0);
    for (; (hook = ao2_iterator_next(&iter)); ao2_ref(hook, -1)) {
        int remove_me;
        ast_bridge_move_indicate_callback move_cb;
 
        if (hook->type != AST_BRIDGE_HOOK_TYPE_MOVE) {
            continue;
        }
        move_cb = (ast_bridge_move_indicate_callback) hook->callback;
        remove_me = move_cb(bridge_channel, hook->hook_pvt, src, dst);
        if (remove_me) {
            ast_debug(1, "Move 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);
}
 
void bridge_do_merge(struct ast_bridge *dst_bridge, struct ast_bridge *src_bridge, struct ast_bridge_channel **kick_me, unsigned int num_kick,
    unsigned int optimized)
{
    struct ast_bridge_channel *bridge_channel;
    unsigned int idx;
 
    ast_debug(1, "Merging bridge %s into bridge %s\n",
        src_bridge->uniqueid, dst_bridge->uniqueid);
 
    ast_bridge_publish_merge(dst_bridge, src_bridge);
 
    /*
     * Move channels from src_bridge over to dst_bridge.
     *
     * We must use AST_LIST_TRAVERSE_SAFE_BEGIN() because
     * bridge_channel_internal_pull() alters the list we are traversing.
     */
    AST_LIST_TRAVERSE_SAFE_BEGIN(&src_bridge->channels, bridge_channel, entry) {
        if (bridge_channel->state != BRIDGE_CHANNEL_STATE_WAIT) {
            /*
             * The channel is already leaving let it leave normally because
             * pulling it may delete hooks that should run for this channel.
             */
            continue;
        }
        if (ast_test_flag(&bridge_channel->features->feature_flags,
            AST_BRIDGE_CHANNEL_FLAG_IMMOVABLE)) {
            continue;
        }
 
        if (kick_me) {
            for (idx = 0; idx < num_kick; ++idx) {
                if (bridge_channel == kick_me[idx]) {
                    ast_bridge_channel_leave_bridge(bridge_channel,
                        BRIDGE_CHANNEL_STATE_END_NO_DISSOLVE, AST_CAUSE_NORMAL_CLEARING);
                    break;
                }
            }
        }
        bridge_channel_internal_pull(bridge_channel);
        if (bridge_channel->state != BRIDGE_CHANNEL_STATE_WAIT) {
            /*
             * The channel died as a result of being pulled or it was
             * kicked.  Leave it pointing to the original bridge.
             */
            continue;
        }
 
        bridge_channel_moving(bridge_channel, bridge_channel->bridge, dst_bridge);
 
        /* Point to new bridge.*/
        bridge_channel_change_bridge(bridge_channel, dst_bridge);
 
        if (bridge_channel_internal_push(bridge_channel)) {
            ast_bridge_features_remove(bridge_channel->features,
                AST_BRIDGE_HOOK_REMOVE_ON_PULL);
            ast_bridge_channel_leave_bridge(bridge_channel,
                BRIDGE_CHANNEL_STATE_END_NO_DISSOLVE, bridge_channel->bridge->cause);
        }
    }
    AST_LIST_TRAVERSE_SAFE_END;
 
    if (kick_me) {
        /*
         * Now we can kick any channels in the dst_bridge without
         * potentially dissolving the bridge.
         */
        for (idx = 0; idx < num_kick; ++idx) {
            bridge_channel = kick_me[idx];
            ast_bridge_channel_lock(bridge_channel);
            if (bridge_channel->state == BRIDGE_CHANNEL_STATE_WAIT) {
                ast_bridge_channel_leave_bridge_nolock(bridge_channel,
                    BRIDGE_CHANNEL_STATE_END_NO_DISSOLVE, AST_CAUSE_NORMAL_CLEARING);
                bridge_channel_internal_pull(bridge_channel);
            }
            ast_bridge_channel_unlock(bridge_channel);
        }
    }
 
    bridge_reconfigured(dst_bridge, !optimized);
    bridge_reconfigured(src_bridge, !optimized);
 
    ast_debug(1, "Merged bridge %s into bridge %s\n",
        src_bridge->uniqueid, dst_bridge->uniqueid);
}
 
struct merge_direction {
    /*! Destination merge bridge. */
    struct ast_bridge *dest;
    /*! Source merge bridge. */
    struct ast_bridge *src;
};
 
/*!
 * \internal
 * \brief Determine which bridge should merge into the other.
 * \since 12.0.0
 *
 * \param bridge1 A bridge for merging
 * \param bridge2 A bridge for merging
 *
 * \note The two bridges are assumed already locked.
 *
 * \return Which bridge merges into which or NULL bridges if cannot merge.
 */
static struct merge_direction bridge_merge_determine_direction(struct ast_bridge *bridge1, struct ast_bridge *bridge2)
{
    struct merge_direction merge = { NULL, NULL };
    int bridge1_priority;
    int bridge2_priority;
 
    if (!ast_test_flag(&bridge1->feature_flags,
            AST_BRIDGE_FLAG_MERGE_INHIBIT_TO | AST_BRIDGE_FLAG_MERGE_INHIBIT_FROM)
        && !ast_test_flag(&bridge2->feature_flags,
            AST_BRIDGE_FLAG_MERGE_INHIBIT_TO | AST_BRIDGE_FLAG_MERGE_INHIBIT_FROM)) {
        /*
         * Can merge either way.  Merge to the higher priority merge
         * bridge.  Otherwise merge to the larger bridge.
         */
        bridge1_priority = bridge1->v_table->get_merge_priority(bridge1);
        bridge2_priority = bridge2->v_table->get_merge_priority(bridge2);
        if (bridge2_priority < bridge1_priority) {
            merge.dest = bridge1;
            merge.src = bridge2;
        } else if (bridge1_priority < bridge2_priority) {
            merge.dest = bridge2;
            merge.src = bridge1;
        } else {
            /* Merge to the larger bridge. */
            if (bridge2->num_channels <= bridge1->num_channels) {
                merge.dest = bridge1;
                merge.src = bridge2;
            } else {
                merge.dest = bridge2;
                merge.src = bridge1;
            }
        }
    } else if (!ast_test_flag(&bridge1->feature_flags, AST_BRIDGE_FLAG_MERGE_INHIBIT_TO)
        && !ast_test_flag(&bridge2->feature_flags, AST_BRIDGE_FLAG_MERGE_INHIBIT_FROM)) {
        /* Can merge only one way. */
        merge.dest = bridge1;
        merge.src = bridge2;
    } else if (!ast_test_flag(&bridge2->feature_flags, AST_BRIDGE_FLAG_MERGE_INHIBIT_TO)
        && !ast_test_flag(&bridge1->feature_flags, AST_BRIDGE_FLAG_MERGE_INHIBIT_FROM)) {
        /* Can merge only one way. */
        merge.dest = bridge2;
        merge.src = bridge1;
    }
 
    return merge;
}
 
/*!
 * \internal
 * \brief Merge two bridges together
 * \since 12.0.0
 *
 * \param dst_bridge Destination bridge of merge.
 * \param src_bridge Source bridge of merge.
 * \param merge_best_direction TRUE if don't care about which bridge merges into the other.
 * \param kick_me Array of channels to kick from the bridges.
 * \param num_kick Number of channels in the kick_me array.
 *
 * \note The dst_bridge and src_bridge are assumed already locked.
 *
 * \retval 0 on success
 * \retval -1 on failure
 */
static int bridge_merge_locked(struct ast_bridge *dst_bridge, struct ast_bridge *src_bridge, int merge_best_direction, struct ast_channel **kick_me, unsigned int num_kick)
{
    struct merge_direction merge;
    struct ast_bridge_channel **kick_them = NULL;
 
    /* Sanity check. */
    ast_assert(dst_bridge && src_bridge && dst_bridge != src_bridge && (!num_kick || kick_me));
 
    if (dst_bridge->dissolved || src_bridge->dissolved) {
        ast_debug(1, "Can't merge bridges %s and %s, at least one bridge is dissolved.\n",
            src_bridge->uniqueid, dst_bridge->uniqueid);
        return -1;
    }
    if (ast_test_flag(&dst_bridge->feature_flags, AST_BRIDGE_FLAG_MASQUERADE_ONLY)
        || ast_test_flag(&src_bridge->feature_flags, AST_BRIDGE_FLAG_MASQUERADE_ONLY)) {
        ast_debug(1, "Can't merge bridges %s and %s, masquerade only.\n",
            src_bridge->uniqueid, dst_bridge->uniqueid);
        return -1;
    }
    if (dst_bridge->inhibit_merge || src_bridge->inhibit_merge) {
        ast_debug(1, "Can't merge bridges %s and %s, merging temporarily inhibited.\n",
            src_bridge->uniqueid, dst_bridge->uniqueid);
        return -1;
    }
 
    if (merge_best_direction) {
        merge = bridge_merge_determine_direction(dst_bridge, src_bridge);
    } else {
        merge.dest = dst_bridge;
        merge.src = src_bridge;
    }
 
    if (!merge.dest
        || ast_test_flag(&merge.dest->feature_flags, AST_BRIDGE_FLAG_MERGE_INHIBIT_TO)
        || ast_test_flag(&merge.src->feature_flags, AST_BRIDGE_FLAG_MERGE_INHIBIT_FROM)) {
        ast_debug(1, "Can't merge bridges %s and %s, merging inhibited.\n",
            src_bridge->uniqueid, dst_bridge->uniqueid);
        return -1;
    }
    if (merge.src->num_channels < 2) {
        /*
         * For a two party bridge, a channel may be temporarily removed
         * from the source bridge or the initial bridge members have not
         * joined yet.
         */
        ast_debug(1, "Can't merge bridge %s into bridge %s, not enough channels in source bridge.\n",
            merge.src->uniqueid, merge.dest->uniqueid);
        return -1;
    }
    if (2 + num_kick < merge.dest->num_channels + merge.src->num_channels
        && !(merge.dest->technology->capabilities & AST_BRIDGE_CAPABILITY_MULTIMIX)
        && (!ast_test_flag(&merge.dest->feature_flags, AST_BRIDGE_FLAG_SMART)
            || !(merge.dest->allowed_capabilities & AST_BRIDGE_CAPABILITY_MULTIMIX))) {
        ast_debug(1, "Can't merge bridge %s into bridge %s, multimix is needed and it cannot be acquired.\n",
            merge.src->uniqueid, merge.dest->uniqueid);
        return -1;
    }
 
    if (num_kick) {
        unsigned int num_to_kick = 0;
        unsigned int idx;
 
        kick_them = ast_alloca(num_kick * sizeof(*kick_them));
        for (idx = 0; idx < num_kick; ++idx) {
            kick_them[num_to_kick] = bridge_find_channel(merge.src, kick_me[idx]);
            if (!kick_them[num_to_kick]) {
                kick_them[num_to_kick] = bridge_find_channel(merge.dest, kick_me[idx]);
            }
            if (kick_them[num_to_kick]) {
                ++num_to_kick;
            }
        }
 
        if (num_to_kick != num_kick) {
            ast_debug(1, "Can't merge bridge %s into bridge %s, at least one kicked channel is not in either bridge.\n",
                merge.src->uniqueid, merge.dest->uniqueid);
            return -1;
        }
    }
 
    bridge_do_merge(merge.dest, merge.src, kick_them, num_kick, 0);
    return 0;
}
 
int ast_bridge_merge(struct ast_bridge *dst_bridge, struct ast_bridge *src_bridge, int merge_best_direction, struct ast_channel **kick_me, unsigned int num_kick)
{
    int res;
 
    /* Sanity check. */
    ast_assert(dst_bridge && src_bridge);
 
    ast_bridge_lock_both(dst_bridge, src_bridge);
    res = bridge_merge_locked(dst_bridge, src_bridge, merge_best_direction, kick_me, num_kick);
    ast_bridge_unlock(src_bridge);
    ast_bridge_unlock(dst_bridge);
    return res;
}
 
int bridge_do_move(struct ast_bridge *dst_bridge, struct ast_bridge_channel *bridge_channel, int attempt_recovery,
    unsigned int optimized)
{
    struct ast_bridge *orig_bridge;
    int was_in_bridge;
    int res = 0;
 
    if (bridge_channel->swap) {
        ast_debug(1, "Moving %p(%s) into bridge %s swapping with %s\n",
            bridge_channel, ast_channel_name(bridge_channel->chan), dst_bridge->uniqueid,
            ast_channel_name(bridge_channel->swap));
    } else {
        ast_debug(1, "Moving %p(%s) into bridge %s\n",
            bridge_channel, ast_channel_name(bridge_channel->chan), dst_bridge->uniqueid);
    }
 
    orig_bridge = bridge_channel->bridge;
    was_in_bridge = bridge_channel->in_bridge;
 
    bridge_channel_internal_pull(bridge_channel);
    if (bridge_channel->state != BRIDGE_CHANNEL_STATE_WAIT) {
        /*
         * The channel died as a result of being pulled.  Leave it
         * pointing to the original bridge.
         *
         * Clear out the swap channel pointer.  A ref is not held
         * by bridge_channel->swap at this point.
         */
        bridge_channel->swap = NULL;
        bridge_reconfigured(orig_bridge, 0);
        return -1;
    }
 
    /* Point to new bridge.*/
    ao2_ref(orig_bridge, +1);/* Keep a ref in case the push fails. */
    bridge_channel_change_bridge(bridge_channel, dst_bridge);
 
    bridge_channel_moving(bridge_channel, orig_bridge, dst_bridge);
 
    if (bridge_channel_internal_push_full(bridge_channel, optimized)) {
        /* Try to put the channel back into the original bridge. */
        ast_bridge_features_remove(bridge_channel->features,
            AST_BRIDGE_HOOK_REMOVE_ON_PULL);
        if (attempt_recovery && was_in_bridge) {
            /* Point back to original bridge. */
            bridge_channel_change_bridge(bridge_channel, orig_bridge);
 
            if (bridge_channel_internal_push(bridge_channel)) {
                ast_bridge_features_remove(bridge_channel->features,
                    AST_BRIDGE_HOOK_REMOVE_ON_PULL);
                ast_bridge_channel_leave_bridge(bridge_channel,
                    BRIDGE_CHANNEL_STATE_END_NO_DISSOLVE, bridge_channel->bridge->cause);
            }
        } else {
            ast_bridge_channel_leave_bridge(bridge_channel,
                BRIDGE_CHANNEL_STATE_END_NO_DISSOLVE, bridge_channel->bridge->cause);
            bridge_channel_settle_owed_events(orig_bridge, bridge_channel);
        }
        res = -1;
    } else if (!optimized) {
        bridge_channel_settle_owed_events(orig_bridge, bridge_channel);
    }
 
    bridge_reconfigured(dst_bridge, !optimized);
    bridge_reconfigured(orig_bridge, !optimized);
    ao2_ref(orig_bridge, -1);
    return res;
}
 
/*!
 * \internal
 * \brief Move a channel from one bridge to another.
 * \since 12.0.0
 *
 * \param dst_bridge Destination bridge of bridge channel move.
 * \param src_bridge Source bridge of bridge channel move.
 * \param chan Channel to move.
 * \param swap Channel to replace in dst_bridge.
 * \param attempt_recovery TRUE if failure attempts to push channel back into original bridge.
 *
 * \note The dst_bridge and src_bridge are assumed already locked.
 *
 * \retval 0 on success.
 * \retval -1 on failure.
 */
static int bridge_move_locked(struct ast_bridge *dst_bridge, struct ast_bridge *src_bridge, struct ast_channel *chan, struct ast_channel *swap, int attempt_recovery)
{
    struct ast_bridge_channel *bridge_channel;
 
    if (dst_bridge->dissolved || src_bridge->dissolved) {
        ast_debug(1, "Can't move channel %s from bridge %s into bridge %s, at least one bridge is dissolved.\n",
            ast_channel_name(chan), src_bridge->uniqueid, dst_bridge->uniqueid);
        return -1;
    }
    if (ast_test_flag(&dst_bridge->feature_flags, AST_BRIDGE_FLAG_MASQUERADE_ONLY)
        || ast_test_flag(&src_bridge->feature_flags, AST_BRIDGE_FLAG_MASQUERADE_ONLY)) {
        ast_debug(1, "Can't move channel %s from bridge %s into bridge %s, masquerade only.\n",
            ast_channel_name(chan), src_bridge->uniqueid, dst_bridge->uniqueid);
        return -1;
    }
    if (dst_bridge->inhibit_merge || src_bridge->inhibit_merge) {
        ast_debug(1, "Can't move channel %s from bridge %s into bridge %s, temporarily inhibited.\n",
            ast_channel_name(chan), src_bridge->uniqueid, dst_bridge->uniqueid);
        return -1;
    }
 
    bridge_channel = bridge_find_channel(src_bridge, chan);
    if (!bridge_channel) {
        ast_debug(1, "Can't move channel %s from bridge %s into bridge %s, channel not in bridge.\n",
            ast_channel_name(chan), src_bridge->uniqueid, dst_bridge->uniqueid);
        return -1;
    }
    if (bridge_channel->state != BRIDGE_CHANNEL_STATE_WAIT) {
        ast_debug(1, "Can't move channel %s from bridge %s into bridge %s, channel leaving bridge.\n",
            ast_channel_name(chan), src_bridge->uniqueid, dst_bridge->uniqueid);
        return -1;
    }
    if (ast_test_flag(&bridge_channel->features->feature_flags,
        AST_BRIDGE_CHANNEL_FLAG_IMMOVABLE)) {
        ast_debug(1, "Can't move channel %s from bridge %s into bridge %s, channel immovable.\n",
            ast_channel_name(chan), src_bridge->uniqueid, dst_bridge->uniqueid);
        return -1;
    }
 
    if (swap) {
        struct ast_bridge_channel *bridge_channel_swap;
 
        bridge_channel_swap = bridge_find_channel(dst_bridge, swap);
        if (!bridge_channel_swap) {
            ast_debug(1, "Can't move channel %s from bridge %s into bridge %s, swap channel %s not in bridge.\n",
                ast_channel_name(chan), src_bridge->uniqueid, dst_bridge->uniqueid,
                ast_channel_name(swap));
            return -1;
        }
        if (bridge_channel_swap->state != BRIDGE_CHANNEL_STATE_WAIT) {
            ast_debug(1, "Can't move channel %s from bridge %s into bridge %s, swap channel %s leaving bridge.\n",
                ast_channel_name(chan), src_bridge->uniqueid, dst_bridge->uniqueid,
                ast_channel_name(swap));
            return -1;
        }
    }
 
    bridge_channel->swap = swap;
    return bridge_do_move(dst_bridge, bridge_channel, attempt_recovery, 0);
}
 
int ast_bridge_move(struct ast_bridge *dst_bridge, struct ast_bridge *src_bridge, struct ast_channel *chan, struct ast_channel *swap, int attempt_recovery)
{
    int res;
 
    ast_bridge_lock_both(dst_bridge, src_bridge);
    res = bridge_move_locked(dst_bridge, src_bridge, chan, swap, attempt_recovery);
    ast_bridge_unlock(src_bridge);
    ast_bridge_unlock(dst_bridge);
    return res;
}
 
int ast_bridge_add_channel(struct ast_bridge *bridge, struct ast_channel *chan,
    struct ast_bridge_features *features, int play_tone, const char *xfersound)
{
    RAII_VAR(struct ast_bridge *, chan_bridge, NULL, ao2_cleanup);
    RAII_VAR(struct ast_channel *, yanked_chan, NULL, ao2_cleanup);
 
    ast_moh_stop(chan);
 
    ast_channel_lock(chan);
    chan_bridge = ast_channel_get_bridge(chan);
    ast_channel_unlock(chan);
 
    if (chan_bridge) {
        struct ast_bridge_channel *bridge_channel;
 
        /* The channel is in a bridge so it is not getting any new features. */
        ast_bridge_features_destroy(features);
 
        ast_bridge_lock_both(bridge, chan_bridge);
        bridge_channel = bridge_find_channel(chan_bridge, chan);
 
        if (bridge_move_locked(bridge, chan_bridge, chan, NULL, 1)) {
            ast_bridge_unlock(chan_bridge);
            ast_bridge_unlock(bridge);
            return -1;
        }
 
        /*
         * bridge_move_locked() will implicitly ensure that
         * bridge_channel is not NULL.
         */
        ast_assert(bridge_channel != NULL);
 
        /*
         * Additional checks if the channel we just stole dissolves the
         * original bridge.
         */
        bridge_dissolve_check_stolen(chan_bridge, bridge_channel);
        ast_bridge_unlock(chan_bridge);
        ast_bridge_unlock(bridge);
    } else {
        /* Slightly less easy case. We need to yank channel A from
         * where he currently is and impart him into our bridge.
         */
        yanked_chan = ast_channel_yank(chan);
        if (!yanked_chan) {
            ast_log(LOG_WARNING, "Could not gain control of channel %s\n", ast_channel_name(chan));
            ast_bridge_features_destroy(features);
            return -1;
        }
        if (ast_channel_state(yanked_chan) != AST_STATE_UP) {
            ast_answer(yanked_chan);
        }
        ast_channel_ref(yanked_chan);
        if (ast_bridge_impart(bridge, yanked_chan, NULL, features,
            AST_BRIDGE_IMPART_CHAN_INDEPENDENT)) {
            /* It is possible for us to yank a channel and have some other
             * thread start a PBX on the channl after we yanked it. In particular,
             * this can theoretically happen on the ;2 of a Local channel if we
             * yank it prior to the ;1 being answered. Make sure that it isn't
             * executing a PBX before hanging it up.
             */
            if (ast_channel_pbx(yanked_chan)) {
                ast_channel_unref(yanked_chan);
            } else {
                ast_hangup(yanked_chan);
            }
            return -1;
        }
    }
 
    if (play_tone && !ast_strlen_zero(xfersound)) {
        struct ast_channel *play_chan = yanked_chan ?: chan;
        RAII_VAR(struct ast_bridge_channel *, play_bridge_channel, NULL, ao2_cleanup);
 
        ast_channel_lock(play_chan);
        play_bridge_channel = ast_channel_get_bridge_channel(play_chan);
        ast_channel_unlock(play_chan);
 
        if (!play_bridge_channel) {
            ast_log(LOG_WARNING, "Unable to play tone for channel %s. No longer in a bridge.\n",
                ast_channel_name(play_chan));
        } else {
            ast_bridge_channel_queue_playfile(play_bridge_channel, NULL, xfersound, NULL);
        }
    }
    return 0;
}
 
static int bridge_allows_optimization(struct ast_bridge *bridge)
{
    return !(bridge->inhibit_merge
        || bridge->dissolved
        || ast_test_flag(&bridge->feature_flags, AST_BRIDGE_FLAG_MASQUERADE_ONLY));
}
 
/*!
 * \internal
 * \brief Lock the unreal channel stack for chan and prequalify it.
 * \since 12.0.0
 *
 * \param chan Unreal channel writing a frame into the channel driver.
 *
 * \note It is assumed that chan is already locked.
 *
 * \return bridge on success with bridge and bridge_channel locked.
 * \retval NULL if cannot do optimization now.
 */
static struct ast_bridge *optimize_lock_chan_stack(struct ast_channel *chan)
{
    struct ast_bridge *bridge;
    struct ast_bridge_channel *bridge_channel;
 
    if (!AST_LIST_EMPTY(ast_channel_readq(chan))) {
        return NULL;
    }
    if (ast_test_flag(ast_channel_flags(chan), AST_FLAG_EMULATE_DTMF)) {
        return NULL;
    }
    if (ast_channel_has_audio_frame_or_monitor(chan)) {
        /* Channel has an active monitor, audiohook, or framehook. */
        return NULL;
    }
    bridge_channel = ast_channel_internal_bridge_channel(chan);
    if (!bridge_channel || ast_bridge_channel_trylock(bridge_channel)) {
        return NULL;
    }
    bridge = bridge_channel->bridge;
    if (bridge_channel->activity != BRIDGE_CHANNEL_THREAD_SIMPLE
        || bridge_channel->state != BRIDGE_CHANNEL_STATE_WAIT
        || ast_bridge_trylock(bridge)) {
        ast_bridge_channel_unlock(bridge_channel);
        return NULL;
    }
    if (!bridge_channel_internal_allows_optimization(bridge_channel) ||
            !bridge_allows_optimization(bridge)) {
        ast_bridge_unlock(bridge);
        ast_bridge_channel_unlock(bridge_channel);
        return NULL;
    }
    return bridge;
}
 
/*!
 * \internal
 * \brief Lock the unreal channel stack for peer and prequalify it.
 * \since 12.0.0
 *
 * \param peer Other unreal channel in the pair.
 *
 * \return bridge on success with bridge, bridge_channel, and peer locked.
 * \retval NULL if cannot do optimization now.
 */
static struct ast_bridge *optimize_lock_peer_stack(struct ast_channel *peer)
{
    struct ast_bridge *bridge;
    struct ast_bridge_channel *bridge_channel;
 
    if (ast_channel_trylock(peer)) {
        return NULL;
    }
    if (!AST_LIST_EMPTY(ast_channel_readq(peer))) {
        ast_channel_unlock(peer);
        return NULL;
    }
    if (ast_test_flag(ast_channel_flags(peer), AST_FLAG_EMULATE_DTMF)) {
        ast_channel_unlock(peer);
        return NULL;
    }
    if (ast_channel_has_audio_frame_or_monitor(peer)) {
        /* Peer has an active monitor, audiohook, or framehook. */
        ast_channel_unlock(peer);
        return NULL;
    }
    bridge_channel = ast_channel_internal_bridge_channel(peer);
    if (!bridge_channel || ast_bridge_channel_trylock(bridge_channel)) {
        ast_channel_unlock(peer);
        return NULL;
    }
    bridge = bridge_channel->bridge;
    if (bridge_channel->activity != BRIDGE_CHANNEL_THREAD_IDLE
        || bridge_channel->state != BRIDGE_CHANNEL_STATE_WAIT
        || ast_bridge_trylock(bridge)) {
        ast_bridge_channel_unlock(bridge_channel);
        ast_channel_unlock(peer);
        return NULL;
    }
    if (!bridge_allows_optimization(bridge) ||
            !bridge_channel_internal_allows_optimization(bridge_channel)) {
        ast_bridge_unlock(bridge);
        ast_bridge_channel_unlock(bridge_channel);
        ast_channel_unlock(peer);
        return NULL;
    }
    return bridge;
}
 
/*!
 * \internal
 * \brief Indicates allowability of a swap optimization
 */
enum bridge_allow_swap {
    /*! Bridges cannot allow for a swap optimization to occur */
    SWAP_PROHIBITED,
    /*! Bridge swap optimization can occur into the chan_bridge */
    SWAP_TO_CHAN_BRIDGE,
    /*! Bridge swap optimization can occur into the peer_bridge */
    SWAP_TO_PEER_BRIDGE,
};
 
/*!
 * \internal
 * \brief Determine if two bridges allow for swap optimization to occur
 *
 * \param chan_bridge First bridge being tested
 * \param peer_bridge Second bridge being tested
 * \return Allowability of swap optimization
 */
static enum bridge_allow_swap bridges_allow_swap_optimization(struct ast_bridge *chan_bridge,
        struct ast_bridge *peer_bridge)
{
    int chan_priority;
    int peer_priority;
 
    if (!ast_test_flag(&chan_bridge->feature_flags,
            AST_BRIDGE_FLAG_SWAP_INHIBIT_TO | AST_BRIDGE_FLAG_SWAP_INHIBIT_FROM |
            AST_BRIDGE_FLAG_TRANSFER_BRIDGE_ONLY)
        && !ast_test_flag(&peer_bridge->feature_flags,
            AST_BRIDGE_FLAG_SWAP_INHIBIT_TO | AST_BRIDGE_FLAG_SWAP_INHIBIT_FROM |
            AST_BRIDGE_FLAG_TRANSFER_BRIDGE_ONLY)) {
        /*
         * Can swap either way.  Swap to the higher priority merge
         * bridge.
         */
        chan_priority = chan_bridge->v_table->get_merge_priority(chan_bridge);
        peer_priority = peer_bridge->v_table->get_merge_priority(peer_bridge);
        if (chan_bridge->num_channels == 2
            && chan_priority <= peer_priority) {
            return SWAP_TO_PEER_BRIDGE;
        } else if (peer_bridge->num_channels == 2
            && peer_priority <= chan_priority) {
            return SWAP_TO_CHAN_BRIDGE;
        }
    } else if (chan_bridge->num_channels == 2
        && !ast_test_flag(&chan_bridge->feature_flags, AST_BRIDGE_FLAG_SWAP_INHIBIT_FROM | AST_BRIDGE_FLAG_TRANSFER_BRIDGE_ONLY)
        && !ast_test_flag(&peer_bridge->feature_flags, AST_BRIDGE_FLAG_SWAP_INHIBIT_TO)) {
        /* Can swap optimize only one way. */
        return SWAP_TO_PEER_BRIDGE;
    } else if (peer_bridge->num_channels == 2
        && !ast_test_flag(&peer_bridge->feature_flags, AST_BRIDGE_FLAG_SWAP_INHIBIT_FROM | AST_BRIDGE_FLAG_TRANSFER_BRIDGE_ONLY)
        && !ast_test_flag(&chan_bridge->feature_flags, AST_BRIDGE_FLAG_SWAP_INHIBIT_TO)) {
        /* Can swap optimize only one way. */
        return SWAP_TO_CHAN_BRIDGE;
    }
 
    return SWAP_PROHIBITED;
}
 
/*!
 * \internal
 * \brief Check and attempt to swap optimize out the unreal channels.
 * \since 12.0.0
 *
 * \param chan_bridge
 * \param chan_bridge_channel
 * \param peer_bridge
 * \param peer_bridge_channel
 * \param pvt Unreal data containing callbacks to call if the optimization actually
 * happens
 *
 * \retval 1 if unreal channels failed to optimize out.
 * \retval 0 if unreal channels were not optimized out.
 * \retval -1 if unreal channels were optimized out.
 */
static int try_swap_optimize_out(struct ast_bridge *chan_bridge,
    struct ast_bridge_channel *chan_bridge_channel, struct ast_bridge *peer_bridge,
    struct ast_bridge_channel *peer_bridge_channel,
    struct ast_unreal_pvt *pvt)
{
    struct ast_bridge *dst_bridge;
    struct ast_bridge_channel *dst_bridge_channel;
    struct ast_bridge_channel *src_bridge_channel;
    struct ast_bridge_channel *other;
    int res = 1;
 
    switch (bridges_allow_swap_optimization(chan_bridge, peer_bridge)) {
    case SWAP_TO_CHAN_BRIDGE:
        dst_bridge = chan_bridge;
        dst_bridge_channel = chan_bridge_channel;
        src_bridge_channel = peer_bridge_channel;
        break;
    case SWAP_TO_PEER_BRIDGE:
        dst_bridge = peer_bridge;
        dst_bridge_channel = peer_bridge_channel;
        src_bridge_channel = chan_bridge_channel;
        break;
    case SWAP_PROHIBITED:
    default:
        return 0;
    }
 
    other = ast_bridge_channel_peer(src_bridge_channel);
    if (other && other->state == BRIDGE_CHANNEL_STATE_WAIT) {
        unsigned int id;
 
        if (ast_channel_trylock(other->chan)) {
            return 1;
        }
 
        id = ast_atomic_fetchadd_int((int *) &optimization_id, +1);
 
        ast_verb(4, "Move-swap optimizing %s <-- %s.\n",
            ast_channel_name(dst_bridge_channel->chan),
            ast_channel_name(other->chan));
 
        if (pvt && !ast_test_flag(pvt, AST_UNREAL_OPTIMIZE_BEGUN) && pvt->callbacks
                && pvt->callbacks->optimization_started) {
            pvt->callbacks->optimization_started(pvt, other->chan,
                    dst_bridge_channel->chan == pvt->owner ? AST_UNREAL_OWNER : AST_UNREAL_CHAN,
                    id);
            ast_set_flag(pvt, AST_UNREAL_OPTIMIZE_BEGUN);
        }
        other->swap = dst_bridge_channel->chan;
        if (!bridge_do_move(dst_bridge, other, 1, 1)) {
            ast_bridge_channel_leave_bridge(src_bridge_channel,
                BRIDGE_CHANNEL_STATE_END_NO_DISSOLVE, AST_CAUSE_NORMAL_CLEARING);
            res = -1;
        }
        if (pvt && pvt->callbacks && pvt->callbacks->optimization_finished) {
            pvt->callbacks->optimization_finished(pvt, res == 1, id);
        }
        ast_channel_unlock(other->chan);
    }
    return res;
}
 
/*!
 * \internal
 * \brief Indicates allowability of a merge optimization
 */
enum bridge_allow_merge {
    /*! Bridge properties prohibit merge optimization */
    MERGE_PROHIBITED,
    /*! Merge optimization cannot occur because the source bridge has too few channels */
    MERGE_NOT_ENOUGH_CHANNELS,
    /*! Merge optimization cannot occur because multimix capability could not be requested */
    MERGE_NO_MULTIMIX,
    /*! Merge optimization allowed between bridges */
    MERGE_ALLOWED,
};
 
/*!
 * \internal
 * \brief Determines allowability of a merge optimization
 *
 * \note The merge output parameter is undefined if MERGE_PROHIBITED is returned. For success
 * and other failure returns, a merge direction was determined, and the parameter is safe to
 * access.
 *
 * \param chan_bridge First bridge being tested
 * \param peer_bridge Second bridge being tested
 * \param num_kick_channels The number of channels to remove from the bridges during merging
 * \param[out] merge Indicates the recommended direction for the bridge merge
 */
static enum bridge_allow_merge bridges_allow_merge_optimization(struct ast_bridge *chan_bridge,
        struct ast_bridge *peer_bridge, int num_kick_channels, struct merge_direction *merge)
{
    *merge = bridge_merge_determine_direction(chan_bridge, peer_bridge);
    if (!merge->dest) {
        return MERGE_PROHIBITED;
    }
    if (merge->src->num_channels < 2) {
        return MERGE_NOT_ENOUGH_CHANNELS;
    } else if ((2 + num_kick_channels) < merge->dest->num_channels + merge->src->num_channels
        && !(merge->dest->technology->capabilities & AST_BRIDGE_CAPABILITY_MULTIMIX)
        && (!ast_test_flag(&merge->dest->feature_flags, AST_BRIDGE_FLAG_SMART)
            || !(merge->dest->allowed_capabilities & AST_BRIDGE_CAPABILITY_MULTIMIX))) {
        return MERGE_NO_MULTIMIX;
    }
 
    return MERGE_ALLOWED;
}
 
/*!
 * \internal
 * \brief Check and attempt to merge optimize out the unreal channels.
 * \since 12.0.0
 *
 * \param chan_bridge
 * \param chan_bridge_channel
 * \param peer_bridge
 * \param peer_bridge_channel
 * \param pvt Unreal data containing callbacks to call if the optimization actually
 * happens
 *
 * \retval 0 if unreal channels were not optimized out.
 * \retval -1 if unreal channels were optimized out.
 */
static int try_merge_optimize_out(struct ast_bridge *chan_bridge,
    struct ast_bridge_channel *chan_bridge_channel, struct ast_bridge *peer_bridge,
    struct ast_bridge_channel *peer_bridge_channel,
    struct ast_unreal_pvt *pvt)
{
    struct merge_direction merge;
    struct ast_bridge_channel *kick_me[] = {
        chan_bridge_channel,
        peer_bridge_channel,
    };
    unsigned int id;
 
    switch (bridges_allow_merge_optimization(chan_bridge, peer_bridge, ARRAY_LEN(kick_me), &merge)) {
    case MERGE_ALLOWED:
        break;
    case MERGE_PROHIBITED:
        return 0;
    case MERGE_NOT_ENOUGH_CHANNELS:
        ast_debug(4, "Can't optimize %s -- %s out, not enough channels in bridge %s.\n",
            ast_channel_name(chan_bridge_channel->chan),
            ast_channel_name(peer_bridge_channel->chan),
            merge.src->uniqueid);
        return 0;
    case MERGE_NO_MULTIMIX:
        ast_debug(4, "Can't optimize %s -- %s out, multimix is needed and it cannot be acquired.\n",
            ast_channel_name(chan_bridge_channel->chan),
            ast_channel_name(peer_bridge_channel->chan));
        return 0;
    }
 
    ast_verb(4, "Merge optimizing %s -- %s out.\n",
        ast_channel_name(chan_bridge_channel->chan),
        ast_channel_name(peer_bridge_channel->chan));
 
    id = ast_atomic_fetchadd_int((int *) &optimization_id, +1);
 
    if (pvt && !ast_test_flag(pvt, AST_UNREAL_OPTIMIZE_BEGUN) && pvt->callbacks
            && pvt->callbacks->optimization_started) {
        pvt->callbacks->optimization_started(pvt, NULL,
                merge.dest == ast_channel_internal_bridge(pvt->owner) ? AST_UNREAL_OWNER : AST_UNREAL_CHAN,
                id);
        ast_set_flag(pvt, AST_UNREAL_OPTIMIZE_BEGUN);
    }
    bridge_do_merge(merge.dest, merge.src, kick_me, ARRAY_LEN(kick_me), 1);
    if (pvt && pvt->callbacks && pvt->callbacks->optimization_finished) {
        pvt->callbacks->optimization_finished(pvt, 1, id);
    }
 
    return -1;
}
 
int ast_bridge_unreal_optimize_out(struct ast_channel *chan, struct ast_channel *peer, struct ast_unreal_pvt *pvt)
{
    struct ast_bridge *chan_bridge;
    struct ast_bridge *peer_bridge;
    struct ast_bridge_channel *chan_bridge_channel;
    struct ast_bridge_channel *peer_bridge_channel;
    int res = 0;
 
    chan_bridge = optimize_lock_chan_stack(chan);
    if (!chan_bridge) {
        return res;
    }
    chan_bridge_channel = ast_channel_internal_bridge_channel(chan);
 
    peer_bridge = optimize_lock_peer_stack(peer);
    if (peer_bridge) {
        peer_bridge_channel = ast_channel_internal_bridge_channel(peer);
 
        res = try_swap_optimize_out(chan_bridge, chan_bridge_channel,
            peer_bridge, peer_bridge_channel, pvt);
        if (!res) {
            res = try_merge_optimize_out(chan_bridge, chan_bridge_channel,
                peer_bridge, peer_bridge_channel, pvt);
        } else if (0 < res) {
            res = 0;
        }
 
        /* Release peer locks. */
        ast_bridge_unlock(peer_bridge);
        ast_bridge_channel_unlock(peer_bridge_channel);
        ast_channel_unlock(peer);
    }
 
    /* Release chan locks. */
    ast_bridge_unlock(chan_bridge);
    ast_bridge_channel_unlock(chan_bridge_channel);
 
    return res;
}
 
enum ast_bridge_optimization ast_bridges_allow_optimization(struct ast_bridge *chan_bridge,
        struct ast_bridge *peer_bridge)
{
    struct merge_direction merge;
 
    if (!bridge_allows_optimization(chan_bridge) || !bridge_allows_optimization(peer_bridge)) {
        return AST_BRIDGE_OPTIMIZE_PROHIBITED;
    }
 
    switch (bridges_allow_swap_optimization(chan_bridge, peer_bridge)) {
    case SWAP_TO_CHAN_BRIDGE:
        return AST_BRIDGE_OPTIMIZE_SWAP_TO_CHAN_BRIDGE;
    case SWAP_TO_PEER_BRIDGE:
        return AST_BRIDGE_OPTIMIZE_SWAP_TO_PEER_BRIDGE;
    case SWAP_PROHIBITED:
    default:
        break;
    }
 
    /* Two channels will be kicked from the bridges, the unreal;1 and unreal;2 channels */
    if (bridges_allow_merge_optimization(chan_bridge, peer_bridge, 2, &merge) != MERGE_ALLOWED) {
        return AST_BRIDGE_OPTIMIZE_PROHIBITED;
    }
 
    if (merge.dest == chan_bridge) {
        return AST_BRIDGE_OPTIMIZE_MERGE_TO_CHAN_BRIDGE;
    } else {
        return AST_BRIDGE_OPTIMIZE_MERGE_TO_PEER_BRIDGE;
    }
}
 
void bridge_merge_inhibit_nolock(struct ast_bridge *bridge, int request)
{
    int new_request;
 
    new_request = bridge->inhibit_merge + request;
    ast_assert(0 <= new_request);
    bridge->inhibit_merge = new_request;
}
 
void ast_bridge_merge_inhibit(struct ast_bridge *bridge, int request)
{
    ast_bridge_lock(bridge);
    bridge_merge_inhibit_nolock(bridge, request);
    ast_bridge_unlock(bridge);
}
 
int ast_bridge_suspend(struct ast_bridge *bridge, struct ast_channel *chan)
{
    struct ast_bridge_channel *bridge_channel;
/* XXX ASTERISK-21271 the case of a dissolved bridge while channel is suspended is not handled. */
/* XXX ASTERISK-21271 suspend/unsuspend needs to be rethought. The caller must block until it has successfully suspended the channel for temporary control. */
/* XXX ASTERISK-21271 external suspend/unsuspend needs to be eliminated. The channel may be playing a file at the time and stealing it then is not good. */
 
    ast_bridge_lock(bridge);
 
    if (!(bridge_channel = bridge_find_channel(bridge, chan))) {
        ast_bridge_unlock(bridge);
        return -1;
    }
 
    bridge_channel_internal_suspend_nolock(bridge_channel);
 
    ast_bridge_unlock(bridge);
 
    return 0;
}
 
int ast_bridge_unsuspend(struct ast_bridge *bridge, struct ast_channel *chan)
{
    struct ast_bridge_channel *bridge_channel;
/* XXX ASTERISK-21271 the case of a dissolved bridge while channel is suspended is not handled. */
 
    ast_bridge_lock(bridge);
 
    if (!(bridge_channel = bridge_find_channel(bridge, chan))) {
        ast_bridge_unlock(bridge);
        return -1;
    }
 
    bridge_channel_internal_unsuspend_nolock(bridge_channel);
 
    ast_bridge_unlock(bridge);
 
    return 0;
}
 
void ast_bridge_technology_suspend(struct ast_bridge_technology *technology)
{
    technology->suspended = 1;
}
 
void ast_bridge_technology_unsuspend(struct ast_bridge_technology *technology)
{
    /*
     * XXX We may want the act of unsuspending a bridge technology
     * to prod all existing bridges to see if they should start
     * using it.
     */
    technology->suspended = 0;
}
 
int ast_bridge_features_register(enum ast_bridge_builtin_feature feature, ast_bridge_hook_callback callback, const char *dtmf)
{
    if (ARRAY_LEN(builtin_features_handlers) <= feature
        || builtin_features_handlers[feature]) {
        return -1;
    }
 
    if (!ast_strlen_zero(dtmf)) {
        ast_copy_string(builtin_features_dtmf[feature], dtmf, sizeof(builtin_features_dtmf[feature]));
    }
 
    builtin_features_handlers[feature] = callback;
 
    return 0;
}
 
int ast_bridge_features_unregister(enum ast_bridge_builtin_feature feature)
{
    if (ARRAY_LEN(builtin_features_handlers) <= feature
        || !builtin_features_handlers[feature]) {
        return -1;
    }
 
    builtin_features_handlers[feature] = NULL;
 
    return 0;
}
 
int ast_bridge_features_do(enum ast_bridge_builtin_feature feature, struct ast_bridge_channel *bridge_channel, void *hook_pvt)
{
    ast_bridge_hook_callback callback;
 
    if (ARRAY_LEN(builtin_features_handlers) <= feature) {
        return -1;
    }
 
    callback = builtin_features_handlers[feature];
    if (!callback) {
        return -1;
    }
    callback(bridge_channel, hook_pvt);
 
    return 0;
}
 
int ast_bridge_interval_register(enum ast_bridge_builtin_interval interval, ast_bridge_builtin_set_limits_fn callback)
{
    if (ARRAY_LEN(builtin_interval_handlers) <= interval
        || builtin_interval_handlers[interval]) {
        return -1;
    }
 
    builtin_interval_handlers[interval] = callback;
 
    return 0;
}
 
int ast_bridge_interval_unregister(enum ast_bridge_builtin_interval interval)
{
    if (ARRAY_LEN(builtin_interval_handlers) <= interval
        || !builtin_interval_handlers[interval]) {
        return -1;
    }
 
    builtin_interval_handlers[interval] = NULL;
 
    return 0;
 
}
 
/*!
 * \internal
 * \brief Bridge hook destructor.
 * \since 12.0.0
 *
 * \param vhook Object to destroy.
 */
static void bridge_hook_destroy(void *vhook)
{
    struct ast_bridge_hook *hook = vhook;
 
    if (hook->destructor) {
        hook->destructor(hook->hook_pvt);
    }
}
 
/*!
 * \internal
 * \brief Allocate and setup a generic bridge hook.
 * \since 12.0.0
 *
 * \param size How big an object to allocate.
 * \param callback Function to execute upon activation
 * \param hook_pvt Unique data
 * \param destructor Optional destructor callback for hook_pvt data
 * \param remove_flags Dictates what situations the hook should be removed.
 *
 * \return hook on success.
 * \retval NULL on error.
 */
static struct ast_bridge_hook *bridge_hook_generic(size_t size,
    ast_bridge_hook_callback callback,
    void *hook_pvt,
    ast_bridge_hook_pvt_destructor destructor,
    enum ast_bridge_hook_remove_flags remove_flags)
{
    struct ast_bridge_hook *hook;
 
    /* Allocate new hook and setup it's basic variables */
    hook = ao2_alloc_options(size, bridge_hook_destroy, AO2_ALLOC_OPT_LOCK_NOLOCK);
    if (hook) {
        hook->callback = callback;
        hook->destructor = destructor;
        hook->hook_pvt = hook_pvt;
        ast_set_flag(&hook->remove_flags, remove_flags);
    }
 
    return hook;
}
 
int ast_bridge_dtmf_hook(struct ast_bridge_features *features,
    const char *dtmf,
    ast_bridge_hook_callback callback,
    void *hook_pvt,
    ast_bridge_hook_pvt_destructor destructor,
    enum ast_bridge_hook_remove_flags remove_flags)
{
    struct ast_bridge_hook_dtmf *hook;
    int res;
 
    /* Allocate new hook and setup it's various variables */
    hook = (struct ast_bridge_hook_dtmf *) bridge_hook_generic(sizeof(*hook), callback,
        hook_pvt, destructor, remove_flags);
    if (!hook) {
        return -1;
    }
    hook->generic.type = AST_BRIDGE_HOOK_TYPE_DTMF;
    ast_copy_string(hook->dtmf.code, dtmf, sizeof(hook->dtmf.code));
 
    /* Once done we put it in the container. */
    res = ao2_link(features->dtmf_hooks, hook) ? 0 : -1;
    if (res) {
        /*
         * Could not link the hook into the container.
         *
         * Remove the hook_pvt destructor call from the hook since we
         * are returning failure to install the hook.
         */
        hook->generic.destructor = NULL;
    }
    ao2_ref(hook, -1);
 
    return res;
}
 
/*!
 * \internal
 * \brief Attach an other hook to a bridge features structure
 *
 * \param features Bridge features structure
 * \param callback Function to execute upon activation
 * \param hook_pvt Unique data
 * \param destructor Optional destructor callback for hook_pvt data
 * \param remove_flags Dictates what situations the hook should be removed.
 * \param type What type of hook is being attached.
 *
 * \retval 0 on success
 * \retval -1 on failure (The caller must cleanup any hook_pvt resources.)
 */
static int bridge_other_hook(struct ast_bridge_features *features,
    ast_bridge_hook_callback callback,
    void *hook_pvt,
    ast_bridge_hook_pvt_destructor destructor,
    enum ast_bridge_hook_remove_flags remove_flags,
    enum ast_bridge_hook_type type)
{
    struct ast_bridge_hook *hook;
    int res;
 
    /* Allocate new hook and setup it's various variables */
    hook = bridge_hook_generic(sizeof(*hook), callback, hook_pvt, destructor,
        remove_flags);
    if (!hook) {
        return -1;
    }
    hook->type = type;
 
    /* Once done we put it in the container. */
    res = ao2_link(features->other_hooks, hook) ? 0 : -1;
    if (res) {
        /*
         * Could not link the hook into the container.
         *
         * Remove the hook_pvt destructor call from the hook since we
         * are returning failure to install the hook.
         */
        hook->destructor = NULL;
    }
    ao2_ref(hook, -1);
 
    return res;
}
 
int ast_bridge_hangup_hook(struct ast_bridge_features *features,
    ast_bridge_hook_callback callback,
    void *hook_pvt,
    ast_bridge_hook_pvt_destructor destructor,
    enum ast_bridge_hook_remove_flags remove_flags)
{
    return bridge_other_hook(features, callback, hook_pvt, destructor, remove_flags,
        AST_BRIDGE_HOOK_TYPE_HANGUP);
}
 
int ast_bridge_join_hook(struct ast_bridge_features *features,
    ast_bridge_hook_callback callback,
    void *hook_pvt,
    ast_bridge_hook_pvt_destructor destructor,
    enum ast_bridge_hook_remove_flags remove_flags)
{
    return bridge_other_hook(features, callback, hook_pvt, destructor, remove_flags,
        AST_BRIDGE_HOOK_TYPE_JOIN);
}
 
int ast_bridge_leave_hook(struct ast_bridge_features *features,
    ast_bridge_hook_callback callback,
    void *hook_pvt,
    ast_bridge_hook_pvt_destructor destructor,
    enum ast_bridge_hook_remove_flags remove_flags)
{
    return bridge_other_hook(features, callback, hook_pvt, destructor, remove_flags,
        AST_BRIDGE_HOOK_TYPE_LEAVE);
}
 
int ast_bridge_talk_detector_hook(struct ast_bridge_features *features,
    ast_bridge_talking_indicate_callback callback,
    void *hook_pvt,
    ast_bridge_hook_pvt_destructor destructor,
    enum ast_bridge_hook_remove_flags remove_flags)
{
    ast_bridge_hook_callback hook_cb = (ast_bridge_hook_callback) callback;
 
    return bridge_other_hook(features, hook_cb, hook_pvt, destructor, remove_flags,
        AST_BRIDGE_HOOK_TYPE_TALK);
}
 
int ast_bridge_move_hook(struct ast_bridge_features *features,
    ast_bridge_move_indicate_callback callback,
    void *hook_pvt,
    ast_bridge_hook_pvt_destructor destructor,
    enum ast_bridge_hook_remove_flags remove_flags)
{
    ast_bridge_hook_callback hook_cb = (ast_bridge_hook_callback) callback;
 
    return bridge_other_hook(features, hook_cb, hook_pvt, destructor, remove_flags,
        AST_BRIDGE_HOOK_TYPE_MOVE);
}
 
int ast_bridge_interval_hook(struct ast_bridge_features *features,
    enum ast_bridge_hook_timer_option flags,
    unsigned int interval,
    ast_bridge_hook_callback callback,
    void *hook_pvt,
    ast_bridge_hook_pvt_destructor destructor,
    enum ast_bridge_hook_remove_flags remove_flags)
{
    struct ast_bridge_hook_timer *hook;
    int res;
 
    if (!features ||!interval || !callback) {
        return -1;
    }
 
    /* Allocate new hook and setup it's various variables */
    hook = (struct ast_bridge_hook_timer *) bridge_hook_generic(sizeof(*hook), callback,
        hook_pvt, destructor, remove_flags);
    if (!hook) {
        return -1;
    }
    hook->generic.type = AST_BRIDGE_HOOK_TYPE_TIMER;
    hook->timer.interval = interval;
    hook->timer.trip_time = ast_tvadd(ast_tvnow(), ast_samp2tv(interval, 1000));
    hook->timer.seqno = ast_atomic_fetchadd_int((int *) &features->interval_sequence, +1);
    hook->timer.flags = flags;
 
    ast_debug(1, "Putting interval hook %p with interval %u in the heap on features %p\n",
        hook, hook->timer.interval, features);
    ast_heap_wrlock(features->interval_hooks);
    res = ast_heap_push(features->interval_hooks, hook);
    ast_heap_unlock(features->interval_hooks);
    if (res) {
        /*
         * Could not push the hook into the heap
         *
         * Remove the hook_pvt destructor call from the hook since we
         * are returning failure to install the hook.
         */
        hook->generic.destructor = NULL;
        ao2_ref(hook, -1);
    }
 
    return res ? -1 : 0;
}
 
int ast_bridge_features_enable(struct ast_bridge_features *features,
    enum ast_bridge_builtin_feature feature,
    const char *dtmf,
    void *config,
    ast_bridge_hook_pvt_destructor destructor,
    enum ast_bridge_hook_remove_flags remove_flags)
{
    if (ARRAY_LEN(builtin_features_handlers) <= feature
        || !builtin_features_handlers[feature]) {
        return -1;
    }
 
    /* If no alternate DTMF stream was provided use the default one */
    if (ast_strlen_zero(dtmf)) {
        dtmf = builtin_features_dtmf[feature];
        /* If no DTMF is still available (ie: it has been disabled) then error out now */
        if (ast_strlen_zero(dtmf)) {
            ast_debug(1, "Failed to enable built in feature %u on %p, no DTMF string is available for it.\n",
                feature, features);
            return -1;
        }
    }
 
    /*
     * The rest is basically pretty easy.  We create another hook
     * using the built in feature's DTMF callback.  Easy as pie.
     */
    return ast_bridge_dtmf_hook(features, dtmf, builtin_features_handlers[feature],
        config, destructor, remove_flags);
}
 
int ast_bridge_features_limits_construct(struct ast_bridge_features_limits *limits)
{
    memset(limits, 0, sizeof(*limits));
 
    if (ast_string_field_init(limits, 256)) {
        return -1;
    }
 
    return 0;
}
 
void ast_bridge_features_limits_destroy(struct ast_bridge_features_limits *limits)
{
    ast_string_field_free_memory(limits);
}
 
int ast_bridge_features_set_limits(struct ast_bridge_features *features,
    struct ast_bridge_features_limits *limits,
    enum ast_bridge_hook_remove_flags remove_flags)
{
    if (builtin_interval_handlers[AST_BRIDGE_BUILTIN_INTERVAL_LIMITS]) {
        ast_bridge_builtin_set_limits_fn callback;
 
        callback = builtin_interval_handlers[AST_BRIDGE_BUILTIN_INTERVAL_LIMITS];
        return callback(features, limits, remove_flags);
    }
 
    ast_log(LOG_ERROR, "Attempted to set limits without an AST_BRIDGE_BUILTIN_INTERVAL_LIMITS callback registered.\n");
    return -1;
}
 
void ast_bridge_features_set_flag(struct ast_bridge_features *features, unsigned int flag)
{
    ast_set_flag(&features->feature_flags, flag);
    features->usable = 1;
}
 
/*!
 * \internal
 * \brief ao2 object match hooks with appropriate remove_flags.
 * \since 12.0.0
 *
 * \param obj Feature hook object.
 * \param arg Removal flags
 * \param flags Not used
 *
 * \retval CMP_MATCH if hook's remove_flags match the removal flags set.
 * \retval 0 if not match.
 */
static int hook_remove_match(void *obj, void *arg, int flags)
{
    struct ast_bridge_hook *hook = obj;
    enum ast_bridge_hook_remove_flags *remove_flags = arg;
 
    if (ast_test_flag(&hook->remove_flags, *remove_flags)) {
        return CMP_MATCH;
    } else {
        return 0;
    }
}
 
/*!
 * \internal
 * \brief Remove all hooks with appropriate remove_flags in the container.
 * \since 12.0.0
 *
 * \param hooks Hooks container to work on.
 * \param remove_flags Determinator for whether hook is removed
 */
static void hooks_remove_container(struct ao2_container *hooks, enum ast_bridge_hook_remove_flags remove_flags)
{
    ao2_callback(hooks, OBJ_UNLINK | OBJ_NODATA | OBJ_MULTIPLE,
        hook_remove_match, &remove_flags);
}
 
/*!
 * \internal
 * \brief Remove all hooks in the heap with appropriate remove_flags set.
 * \since 12.0.0
 *
 * \param hooks Hooks heap to work on.
 * \param remove_flags Determinator for whether hook is removed
 */
static void hooks_remove_heap(struct ast_heap *hooks, enum ast_bridge_hook_remove_flags remove_flags)
{
    struct ast_bridge_hook *hook;
    int changed;
 
    ast_heap_wrlock(hooks);
    do {
        int idx;
 
        changed = 0;
        for (idx = ast_heap_size(hooks); idx; --idx) {
            hook = ast_heap_peek(hooks, idx);
            if (ast_test_flag(&hook->remove_flags, remove_flags)) {
                ast_heap_remove(hooks, hook);
                ao2_ref(hook, -1);
                changed = 1;
            }
        }
    } while (changed);
    ast_heap_unlock(hooks);
}
 
void ast_bridge_features_remove(struct ast_bridge_features *features, enum ast_bridge_hook_remove_flags remove_flags)
{
    hooks_remove_container(features->dtmf_hooks, remove_flags);
    hooks_remove_container(features->other_hooks, remove_flags);
    hooks_remove_heap(features->interval_hooks, remove_flags);
}
 
static int interval_hook_time_cmp(void *a, void *b)
{
    struct ast_bridge_hook_timer *hook_a = a;
    struct ast_bridge_hook_timer *hook_b = b;
    int cmp;
 
    cmp = ast_tvcmp(hook_b->timer.trip_time, hook_a->timer.trip_time);
    if (cmp) {
        return cmp;
    }
 
    cmp = hook_b->timer.seqno - hook_a->timer.seqno;
    return cmp;
}
 
/*!
 * \internal
 * \brief DTMF hook container sort comparison function.
 * \since 12.0.0
 *
 * \param obj_left pointer to the (user-defined part) of an object.
 * \param obj_right pointer to the (user-defined part) of an object.
 * \param flags flags from ao2_callback()
 *   OBJ_POINTER - if set, 'obj_right', is an object.
 *   OBJ_KEY - if set, 'obj_right', is a search key item that is not an object.
 *   OBJ_PARTIAL_KEY - if set, 'obj_right', is a partial search key item that is not an object.
 *
 * \retval <0 if obj_left < obj_right
 * \retval =0 if obj_left == obj_right
 * \retval >0 if obj_left > obj_right
 */
static int bridge_dtmf_hook_sort(const void *obj_left, const void *obj_right, int flags)
{
    const struct ast_bridge_hook_dtmf *hook_left = obj_left;
    const struct ast_bridge_hook_dtmf *hook_right = obj_right;
    const char *right_key = obj_right;
    int cmp;
 
    switch (flags & (OBJ_POINTER | OBJ_KEY | OBJ_PARTIAL_KEY)) {
    default:
    case OBJ_POINTER:
        right_key = hook_right->dtmf.code;
        /* Fall through */
    case OBJ_KEY:
        cmp = strcasecmp(hook_left->dtmf.code, right_key);
        break;
    case OBJ_PARTIAL_KEY:
        cmp = strncasecmp(hook_left->dtmf.code, right_key, strlen(right_key));
        break;
    }
    return cmp;
}
 
/*! \brief Callback for merging hook ao2_containers */
static int merge_container_cb(void *obj, void *data, int flags)
{
    ao2_link(data, obj);
    return 0;
}
 
/*! \brief Wrapper for interval hooks that calls into the wrapped hook */
static int interval_wrapper_cb(struct ast_bridge_channel *bridge_channel, void *obj)
{
    struct ast_bridge_hook_timer *hook = obj;
 
    return hook->generic.callback(bridge_channel, hook->generic.hook_pvt);
}
 
/*! \brief Destructor for the hook wrapper */
static void interval_wrapper_pvt_dtor(void *obj)
{
    ao2_cleanup(obj);
}
 
/*! \brief Wrap the provided interval hook and add it to features */
static void wrap_hook(struct ast_bridge_features *features, struct ast_bridge_hook_timer *hook)
{
    /* Break out of the current wrapper if it exists to avoid multiple layers */
    if (hook->generic.callback == interval_wrapper_cb) {
        hook = hook->generic.hook_pvt;
    }
 
    ast_bridge_interval_hook(features, hook->timer.flags, hook->timer.interval,
        interval_wrapper_cb, ao2_bump(hook), interval_wrapper_pvt_dtor,
        hook->generic.remove_flags.flags);
}
 
void ast_bridge_features_merge(struct ast_bridge_features *into, const struct ast_bridge_features *from)
{
    struct ast_bridge_hook_timer *hook;
    int idx;
 
    /* Merge hook containers */
    ao2_callback(from->dtmf_hooks, 0, merge_container_cb, into->dtmf_hooks);
    ao2_callback(from->other_hooks, 0, merge_container_cb, into->other_hooks);
 
    /* Merge hook heaps */
    ast_heap_wrlock(from->interval_hooks);
    for (idx = 1; (hook = ast_heap_peek(from->interval_hooks, idx)); idx++) {
        wrap_hook(into, hook);
    }
    ast_heap_unlock(from->interval_hooks);
 
    /* Merge feature flags */
    into->feature_flags.flags |= from->feature_flags.flags;
    into->usable |= from->usable;
 
    into->mute |= from->mute;
    into->dtmf_passthrough |= from->dtmf_passthrough;
}
 
/* XXX ASTERISK-21271 make ast_bridge_features_init() static when make ast_bridge_join() requires features to be allocated. */
int ast_bridge_features_init(struct ast_bridge_features *features)
{
    /* Zero out the structure */
    memset(features, 0, sizeof(*features));
 
    /* Initialize the DTMF hooks container */
    features->dtmf_hooks = ao2_container_alloc_list(AO2_ALLOC_OPT_LOCK_MUTEX,
        AO2_CONTAINER_ALLOC_OPT_DUPS_REPLACE, bridge_dtmf_hook_sort, NULL);
    if (!features->dtmf_hooks) {
        return -1;
    }
 
    /* Initialize the miscellaneous other hooks container */
    features->other_hooks = ao2_container_alloc_list(AO2_ALLOC_OPT_LOCK_MUTEX, 0, NULL,
        NULL);
    if (!features->other_hooks) {
        return -1;
    }
 
    /* Initialize the interval hooks heap */
    features->interval_hooks = ast_heap_create(8, interval_hook_time_cmp,
        offsetof(struct ast_bridge_hook_timer, timer.heap_index));
    if (!features->interval_hooks) {
        return -1;
    }
 
    features->dtmf_passthrough = 1;
    features->text_messaging = 1;
 
    return 0;
}
 
/* XXX ASTERISK-21271 make ast_bridge_features_cleanup() static when make ast_bridge_join() requires features to be allocated. */
void ast_bridge_features_cleanup(struct ast_bridge_features *features)
{
    struct ast_bridge_hook_timer *hook;
 
    /* Destroy the interval hooks heap. */
    if (features->interval_hooks) {
        while ((hook = ast_heap_pop(features->interval_hooks))) {
            ao2_ref(hook, -1);
        }
        features->interval_hooks = ast_heap_destroy(features->interval_hooks);
    }
 
    /* Destroy the miscellaneous other hooks container. */
    ao2_cleanup(features->other_hooks);
    features->other_hooks = NULL;
 
    /* Destroy the DTMF hooks container. */
    ao2_cleanup(features->dtmf_hooks);
    features->dtmf_hooks = NULL;
}
 
void ast_bridge_features_destroy(struct ast_bridge_features *features)
{
    if (!features) {
        return;
    }
    ast_bridge_features_cleanup(features);
    ast_free(features);
}
 
struct ast_bridge_features *ast_bridge_features_new(void)
{
    struct ast_bridge_features *features;
 
    features = ast_malloc(sizeof(*features));
    if (features) {
        if (ast_bridge_features_init(features)) {
            ast_bridge_features_destroy(features);
            features = NULL;
        }
    }
 
    return features;
}
 
void ast_bridge_set_mixing_interval(struct ast_bridge *bridge, unsigned int mixing_interval)
{
    ast_bridge_lock(bridge);
    bridge->softmix.internal_mixing_interval = mixing_interval;
    ast_bridge_unlock(bridge);
}
 
void ast_bridge_set_binaural_active(struct ast_bridge *bridge, unsigned int binaural_active)
{
    ast_bridge_lock(bridge);
    bridge->softmix.binaural_active = binaural_active;
    ast_bridge_unlock(bridge);
}
 
void ast_bridge_set_internal_sample_rate(struct ast_bridge *bridge, unsigned int sample_rate)
{
    ast_bridge_lock(bridge);
    bridge->softmix.internal_sample_rate = sample_rate;
    ast_bridge_unlock(bridge);
}
 
void ast_bridge_set_maximum_sample_rate(struct ast_bridge *bridge, unsigned int sample_rate)
{
    ast_bridge_lock(bridge);
    bridge->softmix.maximum_sample_rate = sample_rate;
    ast_bridge_unlock(bridge);
}
 
static void cleanup_video_mode(struct ast_bridge *bridge)
{
    switch (bridge->softmix.video_mode.mode) {
    case AST_BRIDGE_VIDEO_MODE_NONE:
        break;
    case AST_BRIDGE_VIDEO_MODE_SINGLE_SRC:
        if (bridge->softmix.video_mode.mode_data.single_src_data.chan_vsrc) {
            ast_channel_unref(bridge->softmix.video_mode.mode_data.single_src_data.chan_vsrc);
        }
        break;
    case AST_BRIDGE_VIDEO_MODE_TALKER_SRC:
        if (bridge->softmix.video_mode.mode_data.talker_src_data.chan_vsrc) {
            ast_channel_unref(bridge->softmix.video_mode.mode_data.talker_src_data.chan_vsrc);
        }
        if (bridge->softmix.video_mode.mode_data.talker_src_data.chan_old_vsrc) {
            ast_channel_unref(bridge->softmix.video_mode.mode_data.talker_src_data.chan_old_vsrc);
        }
    case AST_BRIDGE_VIDEO_MODE_SFU:
        break;
    }
    memset(&bridge->softmix.video_mode, 0, sizeof(bridge->softmix.video_mode));
}
 
void ast_bridge_set_single_src_video_mode(struct ast_bridge *bridge, struct ast_channel *video_src_chan)
{
    ast_bridge_lock(bridge);
    cleanup_video_mode(bridge);
    bridge->softmix.video_mode.mode = AST_BRIDGE_VIDEO_MODE_SINGLE_SRC;
    if (video_src_chan) {
        bridge->softmix.video_mode.mode_data.single_src_data.chan_vsrc = ast_channel_ref(video_src_chan);
        ast_verb(5, "Video source in bridge '%s' (%s) is now '%s' (%s)\n",
            bridge->name, bridge->uniqueid,
            ast_channel_name(video_src_chan),
            ast_channel_uniqueid(video_src_chan));
        ast_indicate(video_src_chan, AST_CONTROL_VIDUPDATE);
    }
    ast_bridge_publish_state(bridge);
    ast_bridge_unlock(bridge);
}
 
void ast_bridge_set_talker_src_video_mode(struct ast_bridge *bridge)
{
    ast_bridge_lock(bridge);
    cleanup_video_mode(bridge);
    bridge->softmix.video_mode.mode = AST_BRIDGE_VIDEO_MODE_TALKER_SRC;
    ast_bridge_unlock(bridge);
}
 
void ast_bridge_set_sfu_video_mode(struct ast_bridge *bridge)
{
    ast_bridge_lock(bridge);
    cleanup_video_mode(bridge);
    bridge->softmix.video_mode.mode = AST_BRIDGE_VIDEO_MODE_SFU;
    ast_bridge_unlock(bridge);
}
 
void ast_bridge_set_video_update_discard(struct ast_bridge *bridge, unsigned int video_update_discard)
{
    ast_bridge_lock(bridge);
    bridge->softmix.video_mode.video_update_discard = video_update_discard;
    ast_bridge_unlock(bridge);
}
 
void ast_bridge_set_remb_send_interval(struct ast_bridge *bridge, unsigned int remb_send_interval)
{
    ast_assert(bridge->softmix.video_mode.mode == AST_BRIDGE_VIDEO_MODE_SFU);
 
    ast_bridge_lock(bridge);
    bridge->softmix.video_mode.mode_data.sfu_data.remb_send_interval = remb_send_interval;
    ast_bridge_unlock(bridge);
}
 
void ast_brige_set_remb_behavior(struct ast_bridge *bridge, enum ast_bridge_video_sfu_remb_behavior behavior)
{
    ast_assert(bridge->softmix.video_mode.mode == AST_BRIDGE_VIDEO_MODE_SFU);
 
    ast_bridge_lock(bridge);
    bridge->softmix.video_mode.mode_data.sfu_data.remb_behavior = behavior;
    ast_bridge_unlock(bridge);
}
 
void ast_bridge_set_remb_estimated_bitrate(struct ast_bridge *bridge, float estimated_bitrate)
{
    ast_assert(bridge->softmix.video_mode.mode == AST_BRIDGE_VIDEO_MODE_SFU);
 
    ast_bridge_lock(bridge);
    bridge->softmix.video_mode.mode_data.sfu_data.estimated_bitrate = estimated_bitrate;
    ast_bridge_unlock(bridge);
}
 
void ast_bridge_update_talker_src_video_mode(struct ast_bridge *bridge, struct ast_channel *chan, int talker_energy, int is_keyframe)
{
    struct ast_bridge_video_talker_src_data *data;
 
    /* If the channel doesn't support video, we don't care about it */
    if (!ast_format_cap_has_type(ast_channel_nativeformats(chan), AST_MEDIA_TYPE_VIDEO)) {
        return;
    }
 
    ast_bridge_lock(bridge);
    data = &bridge->softmix.video_mode.mode_data.talker_src_data;
 
    if (data->chan_vsrc == chan) {
        data->average_talking_energy = talker_energy;
    } else if ((data->average_talking_energy < talker_energy) && is_keyframe) {
        if (data->chan_old_vsrc) {
            data->chan_old_vsrc = ast_channel_unref(data->chan_old_vsrc);
        }
        if (data->chan_vsrc) {
            data->chan_old_vsrc = data->chan_vsrc;
            ast_indicate(data->chan_old_vsrc, AST_CONTROL_VIDUPDATE);
        }
        data->chan_vsrc = ast_channel_ref(chan);
        data->average_talking_energy = talker_energy;
        ast_verb(5, "Video source in bridge '%s' (%s) is now '%s' (%s)\n",
            bridge->name, bridge->uniqueid,
            ast_channel_name(data->chan_vsrc),
            ast_channel_uniqueid(data->chan_vsrc));
        ast_bridge_publish_state(bridge);
        ast_indicate(data->chan_vsrc, AST_CONTROL_VIDUPDATE);
    } else if ((data->average_talking_energy < talker_energy) && !is_keyframe) {
        ast_indicate(chan, AST_CONTROL_VIDUPDATE);
    } else if (!data->chan_vsrc && is_keyframe) {
        data->chan_vsrc = ast_channel_ref(chan);
        data->average_talking_energy = talker_energy;
        ast_verb(5, "Video source in bridge '%s' (%s) is now '%s' (%s)\n",
            bridge->name, bridge->uniqueid,
            ast_channel_name(data->chan_vsrc),
            ast_channel_uniqueid(data->chan_vsrc));
        ast_bridge_publish_state(bridge);
        ast_indicate(chan, AST_CONTROL_VIDUPDATE);
    } else if (!data->chan_old_vsrc && is_keyframe) {
        data->chan_old_vsrc = ast_channel_ref(chan);
        ast_indicate(chan, AST_CONTROL_VIDUPDATE);
    }
    ast_bridge_unlock(bridge);
}
 
int ast_bridge_number_video_src(struct ast_bridge *bridge)
{
    int res = 0;
 
    ast_bridge_lock(bridge);
    switch (bridge->softmix.video_mode.mode) {
    case AST_BRIDGE_VIDEO_MODE_NONE:
        break;
    case AST_BRIDGE_VIDEO_MODE_SINGLE_SRC:
        if (bridge->softmix.video_mode.mode_data.single_src_data.chan_vsrc) {
            res = 1;
        }
        break;
    case AST_BRIDGE_VIDEO_MODE_TALKER_SRC:
        if (bridge->softmix.video_mode.mode_data.talker_src_data.chan_vsrc) {
            res++;
        }
        if (bridge->softmix.video_mode.mode_data.talker_src_data.chan_old_vsrc) {
            res++;
        }
    case AST_BRIDGE_VIDEO_MODE_SFU:
        break;
    }
    ast_bridge_unlock(bridge);
    return res;
}
 
int ast_bridge_is_video_src(struct ast_bridge *bridge, struct ast_channel *chan)
{
    int res = 0;
 
    ast_bridge_lock(bridge);
    switch (bridge->softmix.video_mode.mode) {
    case AST_BRIDGE_VIDEO_MODE_NONE:
        break;
    case AST_BRIDGE_VIDEO_MODE_SINGLE_SRC:
        if (bridge->softmix.video_mode.mode_data.single_src_data.chan_vsrc == chan) {
            res = 1;
        }
        break;
    case AST_BRIDGE_VIDEO_MODE_TALKER_SRC:
        if (bridge->softmix.video_mode.mode_data.talker_src_data.chan_vsrc == chan) {
            res = 1;
        } else if (bridge->softmix.video_mode.mode_data.talker_src_data.chan_old_vsrc == chan) {
            res = 2;
        }
    case AST_BRIDGE_VIDEO_MODE_SFU:
        break;
    }
    ast_bridge_unlock(bridge);
    return res;
}
 
void ast_bridge_remove_video_src(struct ast_bridge *bridge, struct ast_channel *chan)
{
    ast_bridge_lock(bridge);
    switch (bridge->softmix.video_mode.mode) {
    case AST_BRIDGE_VIDEO_MODE_NONE:
        break;
    case AST_BRIDGE_VIDEO_MODE_SINGLE_SRC:
        if (bridge->softmix.video_mode.mode_data.single_src_data.chan_vsrc == chan) {
            if (bridge->softmix.video_mode.mode_data.single_src_data.chan_vsrc) {
                ast_channel_unref(bridge->softmix.video_mode.mode_data.single_src_data.chan_vsrc);
            }
            bridge->softmix.video_mode.mode_data.single_src_data.chan_vsrc = NULL;
        }
        break;
    case AST_BRIDGE_VIDEO_MODE_TALKER_SRC:
        if (bridge->softmix.video_mode.mode_data.talker_src_data.chan_vsrc == chan) {
            if (bridge->softmix.video_mode.mode_data.talker_src_data.chan_vsrc) {
                ast_channel_unref(bridge->softmix.video_mode.mode_data.talker_src_data.chan_vsrc);
            }
            bridge->softmix.video_mode.mode_data.talker_src_data.chan_vsrc = NULL;
            bridge->softmix.video_mode.mode_data.talker_src_data.average_talking_energy = 0;
        }
        if (bridge->softmix.video_mode.mode_data.talker_src_data.chan_old_vsrc == chan) {
            if (bridge->softmix.video_mode.mode_data.talker_src_data.chan_old_vsrc) {
                ast_channel_unref(bridge->softmix.video_mode.mode_data.talker_src_data.chan_old_vsrc);
            }
            bridge->softmix.video_mode.mode_data.talker_src_data.chan_old_vsrc = NULL;
        }
    case AST_BRIDGE_VIDEO_MODE_SFU:
        break;
    }
    ast_bridge_unlock(bridge);
}
 
const char *ast_bridge_video_mode_to_string(enum ast_bridge_video_mode_type video_mode)
{
    switch (video_mode) {
    case AST_BRIDGE_VIDEO_MODE_TALKER_SRC:
        return "talker";
    case AST_BRIDGE_VIDEO_MODE_SINGLE_SRC:
        return "single";
    case AST_BRIDGE_VIDEO_MODE_SFU:
        return "sfu";
    case AST_BRIDGE_VIDEO_MODE_NONE:
    default:
        return "none";
    }
}
 
void ast_bridge_set_send_sdp_label(struct ast_bridge *bridge, unsigned int send_sdp_label)
{
    ast_bridge_lock(bridge);
    bridge->softmix.send_sdp_label = send_sdp_label;
    ast_bridge_unlock(bridge);
}
 
static int channel_hash(const void *obj, int flags)
{
    const struct ast_channel *chan = obj;
    const char *name = obj;
    int hash;
 
    switch (flags & (OBJ_POINTER | OBJ_KEY | OBJ_PARTIAL_KEY)) {
    default:
    case OBJ_POINTER:
        name = ast_channel_name(chan);
        /* Fall through */
    case OBJ_KEY:
        hash = ast_str_hash(name);
        break;
    case OBJ_PARTIAL_KEY:
        /* Should never happen in hash callback. */
        ast_assert(0);
        hash = 0;
        break;
    }
    return hash;
}
 
static int channel_cmp(void *obj, void *arg, int flags)
{
    const struct ast_channel *left = obj;
    const struct ast_channel *right = arg;
    const char *right_name = arg;
    int cmp;
 
    switch (flags & (OBJ_POINTER | OBJ_KEY | OBJ_PARTIAL_KEY)) {
    default:
    case OBJ_POINTER:
        right_name = ast_channel_name(right);
        /* Fall through */
    case OBJ_KEY:
        cmp = strcmp(ast_channel_name(left), right_name);
        break;
    case OBJ_PARTIAL_KEY:
        cmp = strncmp(ast_channel_name(left), right_name, strlen(right_name));
        break;
    }
    return cmp ? 0 : CMP_MATCH;
}
 
struct ao2_container *ast_bridge_peers_nolock(struct ast_bridge *bridge)
{
    struct ao2_container *channels;
    struct ast_bridge_channel *iter;
 
    channels = ao2_container_alloc_hash(AO2_ALLOC_OPT_LOCK_NOLOCK, 0,
        13, channel_hash, NULL, channel_cmp);
    if (!channels) {
        return NULL;
    }
 
    AST_LIST_TRAVERSE(&bridge->channels, iter, entry) {
        ao2_link(channels, iter->chan);
    }
 
    return channels;
}
 
struct ao2_container *ast_bridge_peers(struct ast_bridge *bridge)
{
    struct ao2_container *channels;
 
    ast_bridge_lock(bridge);
    channels = ast_bridge_peers_nolock(bridge);
    ast_bridge_unlock(bridge);
 
    return channels;
}
 
struct ast_channel *ast_bridge_peer_nolock(struct ast_bridge *bridge, struct ast_channel *chan)
{
    struct ast_channel *peer = NULL;
    struct ast_bridge_channel *iter;
 
    /* Asking for the peer channel only makes sense on a two-party bridge. */
    if (bridge->num_channels == 2
        && bridge->technology->capabilities
            & (AST_BRIDGE_CAPABILITY_NATIVE | AST_BRIDGE_CAPABILITY_1TO1MIX)) {
        int in_bridge = 0;
 
        AST_LIST_TRAVERSE(&bridge->channels, iter, entry) {
            if (iter->chan != chan) {
                peer = iter->chan;
            } else {
                in_bridge = 1;
            }
        }
        if (in_bridge && peer) {
            ast_channel_ref(peer);
        } else {
            peer = NULL;
        }
    }
 
    return peer;
}
 
struct ast_channel *ast_bridge_peer(struct ast_bridge *bridge, struct ast_channel *chan)
{
    struct ast_channel *peer;
 
    ast_bridge_lock(bridge);
    peer = ast_bridge_peer_nolock(bridge, chan);
    ast_bridge_unlock(bridge);
 
    return peer;
}
 
/*!
 * \internal
 * \brief Transfer an entire bridge to a specific destination.
 *
 * This creates a local channel to dial out and swaps the called local channel
 * with the transferer channel. By doing so, all participants in the bridge are
 * connected to the specified destination.
 *
 * While this means of transferring would work for both two-party and multi-party
 * bridges, this method is only used for multi-party bridges since this method would
 * be less efficient for two-party bridges.
 *
 * \param is_external Whether the transfer is externally initiated
 * \param transferer The channel performing a transfer
 * \param bridge The bridge where the transfer is being performed
 * \param exten The destination extension for the blind transfer
 * \param context The destination context for the blind transfer
 * \param transferee The party being transferred if there is only one
 * \param new_channel_cb Callback to call on channel that is created to
 *        facilitate the blind transfer.
 * \param user_data_wrapper User-provided data needed in new_channel_cb
 * \param transfer_message The Stasis publication for this transfer.
 *
 * \return The success or failure of the operation
 */
static enum ast_transfer_result blind_transfer_bridge(int is_external,
        struct ast_channel *transferer, struct ast_bridge *bridge,
        const char *exten, const char *context, struct ast_channel *transferee,
        transfer_channel_cb new_channel_cb,
        struct transfer_channel_data *user_data_wrapper,
        struct ast_blind_transfer_message *transfer_message)
{
    struct ast_channel *local;
    char chan_name[AST_MAX_EXTENSION + AST_MAX_CONTEXT + 2];
    int cause;
 
    snprintf(chan_name, sizeof(chan_name), "%s@%s", exten, context);
    local = ast_request("Local", ast_channel_nativeformats(transferer), NULL, transferer,
            chan_name, &cause);
    if (!local) {
        return AST_BRIDGE_TRANSFER_FAIL;
    }
 
    ast_channel_lock_both(local, transferer);
    ast_channel_req_accountcodes(local, transferer, AST_CHANNEL_REQUESTOR_REPLACEMENT);
 
    transfer_message->replace_channel = ast_channel_snapshot_get_latest(ast_channel_uniqueid(local));
    if (!transfer_message->replace_channel) {
        ast_hangup(local);
        return AST_BRIDGE_TRANSFER_FAIL;
    }
 
    pbx_builtin_setvar_helper(local, BLINDTRANSFER, ast_channel_name(transferer));
    ast_channel_unlock(local);
    ast_channel_unlock(transferer);
 
    if (new_channel_cb) {
        new_channel_cb(local, user_data_wrapper, AST_BRIDGE_TRANSFER_MULTI_PARTY);
    }
 
    if (ast_call(local, chan_name, 0)) {
        ast_hangup(local);
        return AST_BRIDGE_TRANSFER_FAIL;
    }
 
    if (ast_bridge_impart(bridge, local, transferer, NULL,
        AST_BRIDGE_IMPART_CHAN_INDEPENDENT)) {
        ast_hangup(local);
        return AST_BRIDGE_TRANSFER_FAIL;
    }
 
    return AST_BRIDGE_TRANSFER_SUCCESS;
}
 
/*!
 * \internal
 * \brief Get the transferee channel
 *
 * This is only applicable to cases where a transfer is occurring on a
 * two-party bridge. The channels container passed in is expected to only
 * contain two channels, the transferer and the transferee. The transferer
 * channel is passed in as a parameter to ensure we don't return it as
 * the transferee channel.
 *
 * \param channels A two-channel container containing the transferer and transferee
 * \param transferer The party that is transfering the call
 * \return The party that is being transferred
 */
static struct ast_channel *get_transferee(struct ao2_container *channels, struct ast_channel *transferer)
{
    struct ao2_iterator channel_iter;
    struct ast_channel *transferee;
 
    for (channel_iter = ao2_iterator_init(channels, 0);
            (transferee = ao2_iterator_next(&channel_iter));
            ao2_cleanup(transferee)) {
        if (transferee != transferer) {
            break;
        }
    }
 
    ao2_iterator_destroy(&channel_iter);
    return transferee;
}
 
/*!
 * \brief Perform an attended transfer of a bridge
 *
 * This performs an attended transfer of an entire bridge to a target.
 * The target varies, depending on what bridges exist during the transfer
 * attempt.
 *
 * If two bridges exist, then a local channel is created to link the two
 * bridges together.
 *
 * If only one bridge exists, then a local channel is created with one end
 * placed into the existing bridge and the other end masquerading into
 * the unbridged channel.
 *
 * \param chan1 Transferer channel. Guaranteed to be bridged.
 * \param chan2 Other transferer channel. May or may not be bridged.
 * \param bridge1 Bridge that chan1 is in. Guaranteed to be non-NULL.
 * \param bridge2 Bridge that chan2 is in. If NULL, then chan2 is not bridged.
 * \param transfer_msg Data to publish for a stasis attended transfer message.
 * \retval AST_BRIDGE_TRANSFER_FAIL Internal error occurred
 * \retval AST_BRIDGE_TRANSFER_SUCCESS Succesfully transferred the bridge
 */
static enum ast_transfer_result attended_transfer_bridge(struct ast_channel *chan1,
        struct ast_channel *chan2, struct ast_bridge *bridge1, struct ast_bridge *bridge2,
        struct ast_attended_transfer_message *transfer_msg)
{
#define BRIDGE_LOCK_ONE_OR_BOTH(b1, b2) \
    do { \
        if (b2) { \
            ast_bridge_lock_both(b1, b2); \
        } else { \
            ast_bridge_lock(b1); \
        } \
    } while (0)
 
    static const char *dest = "_attended@transfer/m";
    struct ast_channel *local_chan;
    int cause;
    int res;
    const char *app = NULL;
 
    local_chan = ast_request("Local", ast_channel_nativeformats(chan1), NULL, chan1,
            dest, &cause);
    if (!local_chan) {
        return AST_BRIDGE_TRANSFER_FAIL;
    }
 
    ast_channel_lock_both(local_chan, chan1);
    ast_channel_req_accountcodes(local_chan, chan1, AST_CHANNEL_REQUESTOR_REPLACEMENT);
    pbx_builtin_setvar_helper(local_chan, ATTENDEDTRANSFER, ast_channel_name(chan1));
    ast_channel_unlock(local_chan);
    ast_channel_unlock(chan1);
 
    if (bridge2) {
        res = ast_local_setup_bridge(local_chan, bridge2, chan2, NULL);
    } else {
        app = ast_strdupa(ast_channel_appl(chan2));
        res = ast_local_setup_masquerade(local_chan, chan2);
    }
 
    if (res) {
        ast_hangup(local_chan);
        return AST_BRIDGE_TRANSFER_FAIL;
    }
 
    /*
     * Since bridges need to be unlocked before entering ast_bridge_impart and
     * core_local may call into it then the bridges need to be unlocked here.
     */
    ast_bridge_unlock(bridge1);
    if (bridge2) {
        ast_bridge_unlock(bridge2);
    }
 
    if (ast_call(local_chan, dest, 0)) {
        ast_hangup(local_chan);
        BRIDGE_LOCK_ONE_OR_BOTH(bridge1, bridge2);
        return AST_BRIDGE_TRANSFER_FAIL;
    }
 
    /* Get a ref for use later since this one is being stolen */
    ao2_ref(local_chan, +1);
    if (ast_bridge_impart(bridge1, local_chan, chan1, NULL,
        AST_BRIDGE_IMPART_CHAN_INDEPENDENT)) {
        ast_hangup(local_chan);
        ao2_cleanup(local_chan);
        BRIDGE_LOCK_ONE_OR_BOTH(bridge1, bridge2);
        return AST_BRIDGE_TRANSFER_FAIL;
    }
    BRIDGE_LOCK_ONE_OR_BOTH(bridge1, bridge2);
 
    if (bridge2) {
        void *tech;
        struct ast_channel *locals[2];
 
        /* Have to lock everything just in case a hangup comes in early */
        ast_local_lock_all(local_chan, &tech, &locals[0], &locals[1]);
        if (!locals[0] || !locals[1]) {
            ast_log(LOG_ERROR, "Transfer failed probably due to an early hangup - "
                "missing other half of '%s'\n", ast_channel_name(local_chan));
            ast_local_unlock_all(tech, locals[0], locals[1]);
            ao2_cleanup(local_chan);
            return AST_BRIDGE_TRANSFER_FAIL;
        }
 
        /* Make sure the peer is properly set */
        if (local_chan != locals[0]) {
            SWAP(locals[0], locals[1]);
        }
 
        ast_attended_transfer_message_add_link(transfer_msg, locals);
        ast_local_unlock_all(tech, locals[0], locals[1]);
    } else {
        ast_attended_transfer_message_add_app(transfer_msg, app, local_chan);
    }
 
    ao2_cleanup(local_chan);
    return AST_BRIDGE_TRANSFER_SUCCESS;
}
 
static enum ast_transfer_result try_parking(struct ast_channel *transferer,
    const char *context, const char *exten, transfer_channel_cb new_channel_cb,
    struct transfer_channel_data *user_data_wrapper)
{
    RAII_VAR(struct ast_bridge_channel *, transferer_bridge_channel, NULL, ao2_cleanup);
 
    if (!ast_parking_provider_registered()) {
        return AST_BRIDGE_TRANSFER_FAIL;
    }
 
    ast_channel_lock(transferer);
    transferer_bridge_channel = ast_channel_get_bridge_channel(transferer);
    ast_channel_unlock(transferer);
 
    if (!transferer_bridge_channel) {
        return AST_BRIDGE_TRANSFER_FAIL;
    }
 
    if (ast_parking_blind_transfer_park(transferer_bridge_channel,
        context, exten, new_channel_cb, user_data_wrapper)) {
        return AST_BRIDGE_TRANSFER_FAIL;
    }
 
    return AST_BRIDGE_TRANSFER_SUCCESS;
}
 
void ast_bridge_set_transfer_variables(struct ast_channel *chan, const char *value, int attended)
{
    char *writevar;
    char *erasevar;
 
    if (attended) {
        writevar = ATTENDEDTRANSFER;
        erasevar = BLINDTRANSFER;
    } else {
        writevar = BLINDTRANSFER;
        erasevar = ATTENDEDTRANSFER;
    }
 
    pbx_builtin_setvar_helper(chan, writevar, value);
    pbx_builtin_setvar_helper(chan, erasevar, NULL);
}
 
/*!
 * \internal
 * \brief Set the transfer variable as appropriate on channels involved in the transfer
 *
 * The transferer channel will have its variable set the same as its BRIDGEPEER
 * variable. This will account for all channels that it is bridged to. The other channels
 * involved in the transfer will have their variable set to the transferer
 * channel's name.
 *
 * \param transferer The channel performing the transfer
 * \param channels The channels belonging to the bridge
 * \param is_attended false  set BLINDTRANSFER and unset ATTENDEDTRANSFER
 *                    true   set ATTENDEDTRANSFER and unset BLINDTRANSFER
 */
static void set_transfer_variables_all(struct ast_channel *transferer, struct ao2_container *channels, int is_attended)
{
    struct ao2_iterator iter;
    struct ast_channel *chan;
    const char *transferer_name;
    const char *transferer_bridgepeer;
 
    ast_channel_lock(transferer);
    transferer_name = ast_strdupa(ast_channel_name(transferer));
    transferer_bridgepeer = ast_strdupa(S_OR(pbx_builtin_getvar_helper(transferer, "BRIDGEPEER"), ""));
    ast_channel_unlock(transferer);
 
    for (iter = ao2_iterator_init(channels, 0);
            (chan = ao2_iterator_next(&iter));
            ao2_cleanup(chan)) {
        if (chan == transferer) {
            ast_bridge_set_transfer_variables(chan, transferer_bridgepeer, is_attended);
        } else {
            ast_bridge_set_transfer_variables(chan, transferer_name, is_attended);
        }
    }
 
    ao2_iterator_destroy(&iter);
}
 
struct ast_bridge *ast_bridge_transfer_acquire_bridge(struct ast_channel *chan)
{
    struct ast_bridge *bridge;
 
    ast_channel_lock(chan);
    bridge = ast_channel_get_bridge(chan);
    ast_channel_unlock(chan);
 
    if (bridge && ast_test_flag(&bridge->feature_flags,
            (AST_BRIDGE_FLAG_MASQUERADE_ONLY | AST_BRIDGE_FLAG_INVISIBLE))) {
        ao2_ref(bridge, -1);
        bridge = NULL;
    }
 
    return bridge;
}
 
enum ast_transfer_result ast_bridge_transfer_blind(int is_external,
        struct ast_channel *transferer, const char *exten, const char *context,
        transfer_channel_cb new_channel_cb, void *user_data)
{
    RAII_VAR(struct ast_bridge *, bridge, NULL, ao2_cleanup);
    RAII_VAR(struct ast_bridge_channel *, bridge_channel, NULL, ao2_cleanup);
    RAII_VAR(struct ao2_container *, channels, NULL, ao2_cleanup);
    RAII_VAR(struct ast_channel *, transferee, NULL, ast_channel_cleanup);
    RAII_VAR(struct transfer_channel_data *, user_data_wrapper, NULL, ao2_cleanup);
    RAII_VAR(struct ast_blind_transfer_message *, transfer_message, NULL, ao2_cleanup);
    int do_bridge_transfer;
    int transfer_prohibited;
    enum ast_transfer_result transfer_result;
 
    transfer_message = ast_blind_transfer_message_create(is_external, transferer, exten, context);
    if (!transfer_message) {
        /* Out of memory. Not even possible to publish a Stasis message about the
         * failure
         */
        ast_log(LOG_ERROR, "Unable to allocate memory for blind transfer publication from %s\n",
                ast_channel_name(transferer));
        return AST_BRIDGE_TRANSFER_FAIL;
    }
 
    bridge = ast_bridge_transfer_acquire_bridge(transferer);
    if (!bridge) {
        transfer_result = AST_BRIDGE_TRANSFER_INVALID;
        goto publish;
    }
 
    ast_bridge_lock(bridge);
    transfer_message->bridge = ast_bridge_snapshot_create(bridge);
    ast_bridge_unlock(bridge);
    if (!transfer_message->bridge) {
        transfer_result = AST_BRIDGE_TRANSFER_FAIL;
        goto publish;
    }
 
    transferee = ast_bridge_peer(bridge, transferer);
    if (transferee) {
        transfer_message->transferee = ast_channel_snapshot_get_latest(ast_channel_uniqueid(transferee));
        if (!transfer_message->transferee) {
            transfer_result = AST_BRIDGE_TRANSFER_FAIL;
            goto publish;
        }
    }
 
    ast_channel_lock(transferer);
    bridge_channel = ast_channel_get_bridge_channel(transferer);
    ast_channel_unlock(transferer);
    if (!bridge_channel) {
        transfer_result = AST_BRIDGE_TRANSFER_INVALID;
        goto publish;
    }
 
    user_data_wrapper = ao2_alloc(sizeof(*user_data_wrapper), NULL);
    if (!user_data_wrapper) {
        transfer_result = AST_BRIDGE_TRANSFER_FAIL;
        goto publish;
    }
 
    user_data_wrapper->data = user_data;
 
    /* Take off hold if they are on hold. */
    ast_bridge_channel_write_unhold(bridge_channel);
 
    transfer_result = try_parking(transferer, context, exten, new_channel_cb, user_data_wrapper);
    if (transfer_result == AST_BRIDGE_TRANSFER_SUCCESS) {
        goto publish;
    }
 
    /* Since parking didn't take control of the user_data_wrapper, we are just going to raise the completed flag now. */
    user_data_wrapper->completed = 1;
 
    {
        SCOPED_LOCK(lock, bridge, ast_bridge_lock, ast_bridge_unlock);
 
        channels = ast_bridge_peers_nolock(bridge);
        if (!channels) {
            transfer_result = AST_BRIDGE_TRANSFER_FAIL;
            goto publish;
        }
        if (ao2_container_count(channels) <= 1) {
            transfer_result = AST_BRIDGE_TRANSFER_INVALID;
            goto publish;
        }
        transfer_prohibited = ast_test_flag(&bridge->feature_flags,
                AST_BRIDGE_FLAG_TRANSFER_PROHIBITED);
        do_bridge_transfer = ast_test_flag(&bridge->feature_flags,
                AST_BRIDGE_FLAG_TRANSFER_BRIDGE_ONLY) ||
                ao2_container_count(channels) > 2;
    }
 
    if (transfer_prohibited) {
        transfer_result = AST_BRIDGE_TRANSFER_NOT_PERMITTED;
        goto publish;
    }
 
    set_transfer_variables_all(transferer, channels, 0);
 
    if (do_bridge_transfer) {
        transfer_result = blind_transfer_bridge(is_external, transferer, bridge,
            exten, context, transferee, new_channel_cb, user_data_wrapper, transfer_message);
        goto publish;
    }
 
    /* Reaching this portion means that we're dealing with a two-party bridge */
 
    if (!transferee) {
        transfer_result = AST_BRIDGE_TRANSFER_FAIL;
        goto publish;
    }
 
    if (bridge_channel_internal_queue_blind_transfer(transferee, exten, context,
                new_channel_cb, user_data_wrapper)) {
        transfer_result = AST_BRIDGE_TRANSFER_FAIL;
        goto publish;
    }
 
    ast_bridge_remove(bridge, transferer);
    transfer_result = AST_BRIDGE_TRANSFER_SUCCESS;
 
publish:
    transfer_message->result = transfer_result;
    ast_bridge_publish_blind_transfer(transfer_message);
    return transfer_result;
}
 
/*!
 * \internal
 * \brief Performs an attended transfer by moving a channel from one bridge to another
 *
 * The channel that is bridged to the source_channel is moved into the dest_bridge from
 * the source_bridge_channel's bridge. The swap_channel is swapped out of the dest_bridge and placed in
 * the source_bridge_channel's bridge.
 *
 * \note dest_bridge and source_bridge_channel's bridge MUST be locked before calling this function.
 *
 * \param dest_bridge The final bridge for the attended transfer
 * \param source_bridge_channel Channel who is bridged to the channel that will move
 * \param swap_channel Channel to be swapped out of the dest_bridge
 * \return The success or failure of the swap attempt
 */
static enum ast_transfer_result bridge_swap_attended_transfer(struct ast_bridge *dest_bridge,
        struct ast_bridge_channel *source_bridge_channel, struct ast_channel *swap_channel)
{
    struct ast_bridge_channel *bridged_to_source;
 
    bridged_to_source = ast_bridge_channel_peer(source_bridge_channel);
    if (bridged_to_source
        && bridged_to_source->state == BRIDGE_CHANNEL_STATE_WAIT
        && !ast_test_flag(&bridged_to_source->features->feature_flags,
            AST_BRIDGE_CHANNEL_FLAG_IMMOVABLE)) {
        bridged_to_source->swap = swap_channel;
        if (bridge_do_move(dest_bridge, bridged_to_source, 1, 0)) {
            return AST_BRIDGE_TRANSFER_FAIL;
        }
        /* Must kick the source channel out of its bridge. */
        ast_bridge_channel_leave_bridge(source_bridge_channel,
            BRIDGE_CHANNEL_STATE_END_NO_DISSOLVE, AST_CAUSE_NORMAL_CLEARING);
        return AST_BRIDGE_TRANSFER_SUCCESS;
    } else {
        return AST_BRIDGE_TRANSFER_INVALID;
    }
}
 
/*!
 * \internal
 * \brief Function that performs an attended transfer when both transferer channels are bridged
 *
 * The method by which the transfer is performed is dependent on whether the bridges allow for
 * optimization to occur between them. If no optimization is permitted, then an unreal channel
 * is placed as a link between the two bridges. If optimization is permitted, then that means
 * we are free to perform move or merge operations in order to perform the transfer.
 *
 * \note to_transferee_bridge and to_target_bridge MUST be locked before calling this function
 *
 * \param to_transferee The channel that is bridged to the transferee
 * \param to_transferee_bridge_channel to_transferee's bridge_channel
 * \param to_transfer_target The channel that is bridged to the transfer target
 * \param to_target_bridge_channel to_transfer_target's bridge_channel
 * \param to_transferee_bridge The bridge between to_transferee and the transferee
 * \param to_target_bridge The bridge between to_transfer_target and the transfer_target
 * \param transfer_msg Data to publish for a stasis attended transfer message
 * \return The success or failure of the attended transfer
 */
static enum ast_transfer_result two_bridge_attended_transfer(struct ast_channel *to_transferee,
        struct ast_bridge_channel *to_transferee_bridge_channel,
        struct ast_channel *to_transfer_target,
        struct ast_bridge_channel *to_target_bridge_channel,
        struct ast_bridge *to_transferee_bridge, struct ast_bridge *to_target_bridge,
        struct ast_attended_transfer_message *transfer_msg)
{
    struct ast_bridge_channel *kick_me[] = {
            to_transferee_bridge_channel,
            to_target_bridge_channel,
    };
    enum ast_transfer_result res;
    struct ast_bridge *final_bridge = NULL;
    RAII_VAR(struct ao2_container *, channels, NULL, ao2_cleanup);
 
    channels = ast_bridge_peers_nolock(to_transferee_bridge);
 
    if (!channels) {
        res = AST_BRIDGE_TRANSFER_FAIL;
        goto end;
    }
 
    set_transfer_variables_all(to_transferee, channels, 1);
 
    switch (ast_bridges_allow_optimization(to_transferee_bridge, to_target_bridge)) {
    case AST_BRIDGE_OPTIMIZE_SWAP_TO_CHAN_BRIDGE:
        final_bridge = to_transferee_bridge;
        res = bridge_swap_attended_transfer(to_transferee_bridge, to_target_bridge_channel, to_transferee);
        goto end;
    case AST_BRIDGE_OPTIMIZE_SWAP_TO_PEER_BRIDGE:
        final_bridge = to_target_bridge;
        res = bridge_swap_attended_transfer(to_target_bridge, to_transferee_bridge_channel, to_transfer_target);
        goto end;
    case AST_BRIDGE_OPTIMIZE_MERGE_TO_CHAN_BRIDGE:
        final_bridge = to_transferee_bridge;
        bridge_do_merge(to_transferee_bridge, to_target_bridge, kick_me, ARRAY_LEN(kick_me), 0);
        res = AST_BRIDGE_TRANSFER_SUCCESS;
        goto end;
    case AST_BRIDGE_OPTIMIZE_MERGE_TO_PEER_BRIDGE:
        final_bridge = to_target_bridge;
        bridge_do_merge(to_target_bridge, to_transferee_bridge, kick_me, ARRAY_LEN(kick_me), 0);
        res = AST_BRIDGE_TRANSFER_SUCCESS;
        goto end;
    case AST_BRIDGE_OPTIMIZE_PROHIBITED:
    default:
        /* Just because optimization wasn't doable doesn't necessarily mean
         * that we can actually perform the transfer. Some reasons for non-optimization
         * indicate bridge invalidity, so let's check those before proceeding.
         */
        if (to_transferee_bridge->inhibit_merge || to_transferee_bridge->dissolved ||
                to_target_bridge->inhibit_merge || to_target_bridge->dissolved) {
            return AST_BRIDGE_TRANSFER_INVALID;
        }
 
        return attended_transfer_bridge(to_transferee, to_transfer_target,
            to_transferee_bridge, to_target_bridge, transfer_msg);
    }
 
end:
    if (res == AST_BRIDGE_TRANSFER_SUCCESS) {
        ast_attended_transfer_message_add_merge(transfer_msg, final_bridge);
    }
 
    return res;
}
 
enum ast_transfer_result ast_bridge_transfer_attended(struct ast_channel *to_transferee,
        struct ast_channel *to_transfer_target)
{
    RAII_VAR(struct ast_bridge *, to_transferee_bridge, NULL, ao2_cleanup);
    RAII_VAR(struct ast_bridge *, to_target_bridge, NULL, ao2_cleanup);
    RAII_VAR(struct ast_bridge_channel *, to_transferee_bridge_channel, NULL, ao2_cleanup);
    RAII_VAR(struct ast_bridge_channel *, to_target_bridge_channel, NULL, ao2_cleanup);
    RAII_VAR(struct ao2_container *, channels, NULL, ao2_cleanup);
    RAII_VAR(struct ast_channel *, transferee, NULL, ao2_cleanup);
    RAII_VAR(struct ast_attended_transfer_message *, transfer_msg, NULL, ao2_cleanup);
    struct ast_bridge *the_bridge = NULL;
    struct ast_channel *chan_bridged;
    struct ast_channel *chan_unbridged;
    int transfer_prohibited;
    int do_bridge_transfer;
    enum ast_transfer_result res;
    const char *app = NULL;
    int hangup_target = 0;
 
    to_transferee_bridge = ast_bridge_transfer_acquire_bridge(to_transferee);
    to_target_bridge = ast_bridge_transfer_acquire_bridge(to_transfer_target);
 
    transfer_msg = ast_attended_transfer_message_create(1, to_transferee, to_transferee_bridge,
            to_transfer_target, to_target_bridge, NULL, NULL);
    if (!transfer_msg) {
        ast_log(LOG_ERROR, "Unable to create Stasis publication for attended transfer from %s\n",
                ast_channel_name(to_transferee));
        return AST_BRIDGE_TRANSFER_FAIL;
    }
 
    /* They can't both be unbridged, you silly goose! */
    if (!to_transferee_bridge && !to_target_bridge) {
        res = AST_BRIDGE_TRANSFER_INVALID;
        goto end;
    }
 
    ast_channel_lock(to_transferee);
    to_transferee_bridge_channel = ast_channel_get_bridge_channel(to_transferee);
    ast_channel_unlock(to_transferee);
 
    ast_channel_lock(to_transfer_target);
    to_target_bridge_channel = ast_channel_get_bridge_channel(to_transfer_target);
    ast_channel_unlock(to_transfer_target);
 
    if (to_transferee_bridge_channel) {
        /* Take off hold if they are on hold. */
        if (ast_bridge_channel_write_unhold(to_transferee_bridge_channel)) {
            ast_log(LOG_ERROR, "Transferee channel disappeared during transfer!\n");
            res = AST_BRIDGE_TRANSFER_FAIL;
            goto end;
        }
    }
 
    if (to_target_bridge_channel) {
        const char *target_complete_sound;
 
        /* Take off hold if they are on hold. */
        if (ast_bridge_channel_write_unhold(to_target_bridge_channel)) {
            ast_log(LOG_ERROR, "Target channel disappeared during transfer!\n");
            res = AST_BRIDGE_TRANSFER_FAIL;
            goto end;
        }
 
        /* Is there a courtesy sound to play to the target? */
        ast_channel_lock(to_transfer_target);
        target_complete_sound = pbx_builtin_getvar_helper(to_transfer_target,
            "ATTENDED_TRANSFER_COMPLETE_SOUND");
        if (!ast_strlen_zero(target_complete_sound)) {
            target_complete_sound = ast_strdupa(target_complete_sound);
        } else {
            target_complete_sound = NULL;
        }
        ast_channel_unlock(to_transfer_target);
        if (!target_complete_sound) {
            ast_channel_lock(to_transferee);
            target_complete_sound = pbx_builtin_getvar_helper(to_transferee,
                "ATTENDED_TRANSFER_COMPLETE_SOUND");
            if (!ast_strlen_zero(target_complete_sound)) {
                target_complete_sound = ast_strdupa(target_complete_sound);
            } else {
                target_complete_sound = NULL;
            }
            ast_channel_unlock(to_transferee);
        }
        if (target_complete_sound) {
            ast_bridge_channel_write_playfile(to_target_bridge_channel, NULL,
                target_complete_sound, NULL);
        }
    }
 
    /* Let's get the easy one out of the way first */
    if (to_transferee_bridge && to_target_bridge) {
 
        if (!to_transferee_bridge_channel || !to_target_bridge_channel) {
            res = AST_BRIDGE_TRANSFER_INVALID;
            goto end;
        }
 
        ast_bridge_lock_both(to_transferee_bridge, to_target_bridge);
        res = two_bridge_attended_transfer(to_transferee, to_transferee_bridge_channel,
                to_transfer_target, to_target_bridge_channel,
                to_transferee_bridge, to_target_bridge, transfer_msg);
        ast_bridge_unlock(to_transferee_bridge);
        ast_bridge_unlock(to_target_bridge);
 
        hangup_target = 1;
        goto end;
    }
 
    the_bridge = to_transferee_bridge ?: to_target_bridge;
    chan_bridged = to_transferee_bridge ? to_transferee : to_transfer_target;
    chan_unbridged = to_transferee_bridge ? to_transfer_target : to_transferee;
 
    /*
     * Race condition makes it possible for app to be NULL, so get the app prior to
     * transferring with a fallback of "unknown".
     */
    app = ast_strdupa(ast_channel_appl(chan_unbridged) ?: "unknown");
 
    {
        int chan_count;
        SCOPED_LOCK(lock, the_bridge, ast_bridge_lock, ast_bridge_unlock);
 
        channels = ast_bridge_peers_nolock(the_bridge);
        if (!channels) {
            res = AST_BRIDGE_TRANSFER_FAIL;
            goto end;
        }
        chan_count = ao2_container_count(channels);
        if (chan_count <= 1) {
            res = AST_BRIDGE_TRANSFER_INVALID;
            goto end;
        }
        transfer_prohibited = ast_test_flag(&the_bridge->feature_flags,
                AST_BRIDGE_FLAG_TRANSFER_PROHIBITED);
        do_bridge_transfer = ast_test_flag(&the_bridge->feature_flags,
                AST_BRIDGE_FLAG_TRANSFER_BRIDGE_ONLY) ||
                chan_count > 2;
    }
 
    if (transfer_prohibited) {
        res = AST_BRIDGE_TRANSFER_NOT_PERMITTED;
        goto end;
    }
 
    set_transfer_variables_all(to_transferee, channels, 1);
 
    if (do_bridge_transfer) {
        /*
         * Hang up the target if it was bridged. Note, if it is not bridged
         * it is hung up during the masquerade.
         */
        hangup_target = chan_bridged == to_transfer_target;
        ast_bridge_lock(the_bridge);
        res = attended_transfer_bridge(chan_bridged, chan_unbridged, the_bridge, NULL, transfer_msg);
        ast_bridge_unlock(the_bridge);
        goto end;
    }
 
    transferee = get_transferee(channels, chan_bridged);
    if (!transferee) {
        res = AST_BRIDGE_TRANSFER_FAIL;
        goto end;
    }
 
    if (bridge_channel_internal_queue_attended_transfer(transferee, chan_unbridged)) {
        res = AST_BRIDGE_TRANSFER_FAIL;
        goto end;
    }
 
    ast_bridge_remove(the_bridge, chan_bridged);
 
    ast_attended_transfer_message_add_app(transfer_msg, app, NULL);
    res = AST_BRIDGE_TRANSFER_SUCCESS;
 
end:
    if ((res == AST_BRIDGE_TRANSFER_SUCCESS && hangup_target) || res == AST_BRIDGE_TRANSFER_FAIL) {
        ast_softhangup(to_transfer_target, AST_SOFTHANGUP_DEV);
    }
 
    transfer_msg->result = res;
    ast_bridge_publish_attended_transfer(transfer_msg);
    return res;
}
 
/*!
 * \internal
 * \brief Service the bridge manager request.
 * \since 12.0.0
 *
 * \param bridge requesting service.
 */
static void bridge_manager_service(struct ast_bridge *bridge)
{
    ast_bridge_lock(bridge);
    if (bridge->callid) {