pickup.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2013, Digium, Inc.
 * Copyright (C) 2012, Russell Bryant
 *
 * Matt Jordan <mjordan@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 Routines implementing call pickup
 *
 * \author Matt Jordan <mjordan@digium.com>
 */
 
/*!
 * \li Call pickup uses the configuration file \ref features.conf
 * \addtogroup configuration_file Configuration Files
 */
 
/*** MODULEINFO
    <support_level>core</support_level>
 ***/
 
/*** DOCUMENTATION
    <managerEvent language="en_US" name="Pickup">
        <managerEventInstance class="EVENT_FLAG_CALL">
            <synopsis>Raised when a call pickup occurs.</synopsis>
            <syntax>
                <channel_snapshot/>
                <channel_snapshot prefix="Target"/>
            </syntax>
        </managerEventInstance>
    </managerEvent>
 ***/
 
#include "asterisk.h"
 
#include "asterisk/pickup.h"
#include "asterisk/channel.h"
#include "asterisk/pbx.h"
#include "asterisk/app.h"
#include "asterisk/callerid.h"
#include "asterisk/causes.h"
#include "asterisk/stasis.h"
#include "asterisk/stasis_channels.h"
#include "asterisk/features_config.h"
 
static struct ast_manager_event_blob *call_pickup_to_ami(struct stasis_message *message);
 
STASIS_MESSAGE_TYPE_DEFN(
    ast_call_pickup_type,
    .to_ami = call_pickup_to_ami);
 
 
/*!
 * The presence of this datastore on the channel indicates that
 * someone is attemting to pickup or has picked up the channel.
 * The purpose is to prevent a race between two channels
 * attempting to pickup the same channel.
 */
static const struct ast_datastore_info pickup_active = {
    .type = "pickup-active",
};
 
int ast_can_pickup(struct ast_channel *chan)
{
    if (!ast_channel_pbx(chan) && !ast_channel_masq(chan) && !ast_test_flag(ast_channel_flags(chan), AST_FLAG_ZOMBIE)
        && (ast_channel_state(chan) == AST_STATE_RINGING
            || ast_channel_state(chan) == AST_STATE_RING
            /*
             * Check the down state as well because some SIP devices do not
             * give 180 ringing when they can just give 183 session progress
             * instead.  Issue 14005.  (Some ISDN switches as well for that
             * matter.)
             */
            || ast_channel_state(chan) == AST_STATE_DOWN)
        && !ast_channel_datastore_find(chan, &pickup_active, NULL)) {
        return 1;
    }
    return 0;
}
 
static int find_channel_by_group(void *obj, void *arg, void *data, int flags)
{
    struct ast_channel *target = obj; /*!< Potential pickup target */
    struct ast_channel *chan = arg;   /*!< Channel wanting to pickup call */
 
    if (chan == target) {
        return 0;
    }
 
    ast_channel_lock(target);
    if (ast_can_pickup(target)) {
        /* Lock both channels. */
        while (ast_channel_trylock(chan)) {
            ast_channel_unlock(target);
            sched_yield();
            ast_channel_lock(target);
        }
 
        /*
         * Both callgroup and namedcallgroup pickup variants are
         * matched independently.  Checking for named group match is
         * done last since it's a more expensive operation.
         */
        if ((ast_channel_pickupgroup(chan) & ast_channel_callgroup(target))
            || (ast_namedgroups_intersect(ast_channel_named_pickupgroups(chan),
                ast_channel_named_callgroups(target)))) {
            struct ao2_container *candidates = data;/*!< Candidate channels found. */
 
            /* This is a candidate to pickup */
            ao2_link(candidates, target);
        }
        ast_channel_unlock(chan);
    }
    ast_channel_unlock(target);
 
    return 0;
}
 
struct ast_channel *ast_pickup_find_by_group(struct ast_channel *chan)
{
    struct ao2_container *candidates;/*!< Candidate channels found to pickup. */
    struct ast_channel *target;/*!< Potential pickup target */
 
    candidates = ao2_container_alloc_list(AO2_ALLOC_OPT_LOCK_NOLOCK, 0, NULL, NULL);
    if (!candidates) {
        return NULL;
    }
 
    /* Find all candidate targets by group. */
    ast_channel_callback(find_channel_by_group, chan, candidates, 0);
 
    /* Find the oldest pickup target candidate */
    target = NULL;
    for (;;) {
        struct ast_channel *candidate;/*!< Potential new older target */
        struct ao2_iterator iter;
 
        iter = ao2_iterator_init(candidates, 0);
        while ((candidate = ao2_iterator_next(&iter))) {
            if (!target) {
                /* First target. */
                target = candidate;
                continue;
            }
            if (ast_tvcmp(ast_channel_creationtime(candidate), ast_channel_creationtime(target)) < 0) {
                /* We have a new target. */
                ast_channel_unref(target);
                target = candidate;
                continue;
            }
            ast_channel_unref(candidate);
        }
        ao2_iterator_destroy(&iter);
        if (!target) {
            /* No candidates found. */
            break;
        }
 
        /* The found channel must be locked and ref'd. */
        ast_channel_lock(target);
 
        /* Recheck pickup ability */
        if (ast_can_pickup(target)) {
            /* This is the channel to pickup. */
            break;
        }
 
        /* Someone else picked it up or the call went away. */
        ast_channel_unlock(target);
        ao2_unlink(candidates, target);
        target = ast_channel_unref(target);
    }
    ao2_ref(candidates, -1);
 
    return target;
}
 
/*!
 * \brief Pickup a call
 *
 * Walk list of channels, checking it is not itself, channel is pbx one,
 * check that the callgroup for both channels are the same and the channel is ringing.
 * Answer calling channel, flag channel as answered on queue, masq channels together.
 */
int ast_pickup_call(struct ast_channel *chan)
{
    struct ast_channel *target;/*!< Potential pickup target */
    int res = -1;
    RAII_VAR(struct ast_features_pickup_config *, pickup_cfg, NULL, ao2_cleanup);
    const char *pickup_sound;
    const char *fail_sound;
 
    ast_debug(1, "Pickup attempt by %s\n", ast_channel_name(chan));
    ast_channel_lock(chan);
    pickup_cfg = ast_get_chan_features_pickup_config(chan);
    if (!pickup_cfg) {
        ast_log(LOG_ERROR, "Unable to retrieve pickup configuration. Unable to play pickup sounds\n");
    }
    pickup_sound = ast_strdupa(pickup_cfg ? pickup_cfg->pickupsound : "");
    fail_sound = ast_strdupa(pickup_cfg ? pickup_cfg->pickupfailsound : "");
    ast_channel_unlock(chan);
 
    /* The found channel is already locked. */
    target = ast_pickup_find_by_group(chan);
    if (target) {
        ast_log(LOG_NOTICE, "Pickup %s attempt by %s\n", ast_channel_name(target), ast_channel_name(chan));
 
        res = ast_do_pickup(chan, target);
        ast_channel_unlock(target);
        if (!res) {
            if (!ast_strlen_zero(pickup_sound)) {
                pbx_builtin_setvar_helper(target, "BRIDGE_PLAY_SOUND", pickup_sound);
            }
        } else {
            ast_log(LOG_WARNING, "Pickup %s failed by %s\n", ast_channel_name(target), ast_channel_name(chan));
        }
        target = ast_channel_unref(target);
    }
 
    if (res < 0) {
        ast_debug(1, "No call pickup possible... for %s\n", ast_channel_name(chan));
        if (!ast_strlen_zero(fail_sound)) {
            ast_answer(chan);
            ast_stream_and_wait(chan, fail_sound, "");
        }
    }
 
    return res;
}
 
static struct ast_manager_event_blob *call_pickup_to_ami(struct stasis_message *message)
{
    struct ast_multi_channel_blob *contents = stasis_message_data(message);
    struct ast_channel_snapshot *chan;
    struct ast_channel_snapshot *target;
    struct ast_manager_event_blob *res;
 
    RAII_VAR(struct ast_str *, channel_str, NULL, ast_free);
    RAII_VAR(struct ast_str *, target_str, NULL, ast_free);
 
    chan = ast_multi_channel_blob_get_channel(contents, "channel");
    target = ast_multi_channel_blob_get_channel(contents, "target");
 
    ast_assert(chan != NULL && target != NULL);
 
    if (!(channel_str = ast_manager_build_channel_state_string(chan))) {
        return NULL;
    }
 
    if (!(target_str = ast_manager_build_channel_state_string_prefix(target, "Target"))) {
        return NULL;
    }
 
    res = ast_manager_event_blob_create(EVENT_FLAG_CALL, "Pickup",
        "%s"
        "%s",
        ast_str_buffer(channel_str),
        ast_str_buffer(target_str));
 
    return res;
}
 
static int send_call_pickup_stasis_message(struct ast_channel *picking_up, struct ast_channel_snapshot *chan, struct ast_channel_snapshot *target)
{
    RAII_VAR(struct ast_multi_channel_blob *, pickup_payload, NULL, ao2_cleanup);
    RAII_VAR(struct stasis_message *, msg, NULL, ao2_cleanup);
 
    if (!ast_call_pickup_type()) {
        return -1;
    }
 
    if (!(pickup_payload = ast_multi_channel_blob_create(ast_json_null()))) {
        return -1;
    }
 
    ast_multi_channel_blob_add_channel(pickup_payload, "channel", chan);
    ast_multi_channel_blob_add_channel(pickup_payload, "target", target);
 
    if (!(msg = stasis_message_create(ast_call_pickup_type(), pickup_payload))) {
        return -1;
    }
 
    stasis_publish(ast_channel_topic(picking_up), msg);
    return 0;
}
 
int ast_do_pickup(struct ast_channel *chan, struct ast_channel *target)
{
    struct ast_party_connected_line connected_caller;
    struct ast_datastore *ds_pickup;
    const char *chan_name;/*!< A masquerade changes channel names. */
    const char *target_name;/*!< A masquerade changes channel names. */
    int res = -1;
 
    RAII_VAR(struct ast_channel_snapshot *, chan_snapshot, NULL, ao2_cleanup);
    RAII_VAR(struct ast_channel_snapshot *, target_snapshot, NULL, ao2_cleanup);
 
    target_name = ast_strdupa(ast_channel_name(target));
    ast_debug(1, "Call pickup on '%s' by '%s'\n", target_name, ast_channel_name(chan));
 
    /* Mark the target to block any call pickup race. */
    ds_pickup = ast_datastore_alloc(&pickup_active, NULL);
    if (!ds_pickup) {
        ast_log(LOG_WARNING,
            "Unable to create channel datastore on '%s' for call pickup\n", target_name);
        return -1;
    }
    ast_channel_datastore_add(target, ds_pickup);
 
    ast_party_connected_line_init(&connected_caller);
    ast_party_connected_line_copy(&connected_caller, ast_channel_connected(target));
    ast_channel_unlock(target);/* The pickup race is avoided so we do not need the lock anymore. */
    /* Reset any earlier private connected id representation */
    ast_party_id_reset(&connected_caller.priv);
 
    connected_caller.source = AST_CONNECTED_LINE_UPDATE_SOURCE_ANSWER;
    if (ast_channel_connected_line_sub(NULL, chan, &connected_caller, 0)) {
        ast_channel_update_connected_line(chan, &connected_caller, NULL);
    }
    ast_party_connected_line_free(&connected_caller);
 
    ast_channel_lock(chan);
    chan_name = ast_strdupa(ast_channel_name(chan));
    ast_connected_line_copy_from_caller(&connected_caller, ast_channel_caller(chan));
    ast_channel_unlock(chan);
    connected_caller.source = AST_CONNECTED_LINE_UPDATE_SOURCE_ANSWER;
 
    if (ast_answer(chan)) {
        ast_log(LOG_WARNING, "Unable to answer '%s'\n", chan_name);
        goto pickup_failed;
    }
 
    if (ast_queue_control(chan, AST_CONTROL_ANSWER)) {
        ast_log(LOG_WARNING, "Unable to queue answer on '%s'\n", chan_name);
        goto pickup_failed;
    }
 
    ast_channel_queue_connected_line_update(chan, &connected_caller, NULL);
 
    /* setting the HANGUPCAUSE so the ringing channel knows this call was not a missed call */
    ast_channel_hangupcause_set(chan, AST_CAUSE_ANSWERED_ELSEWHERE);
 
    ast_channel_lock(chan);
    chan_snapshot = ast_channel_snapshot_create(chan);
    ast_channel_unlock(chan);
    if (!chan_snapshot) {
        goto pickup_failed;
    }
 
    target_snapshot = ast_channel_snapshot_get_latest(ast_channel_uniqueid(target));
    if (!target_snapshot) {
        goto pickup_failed;
    }
 
    if (ast_channel_move(target, chan)) {
        ast_log(LOG_WARNING, "Unable to complete call pickup of '%s' with '%s'\n",
            chan_name, target_name);
        goto pickup_failed;
    }
 
    /* target points to the channel that did the pickup at this point, so use that channel's topic instead of chan */
    send_call_pickup_stasis_message(target, chan_snapshot, target_snapshot);
 
    res = 0;
 
pickup_failed:
    ast_channel_lock(target);
    if (!ast_channel_datastore_remove(target, ds_pickup)) {
        ast_datastore_free(ds_pickup);
    }
    ast_party_connected_line_free(&connected_caller);
 
    return res;
}
 
/*!
 * \internal
 * \brief Clean up resources on Asterisk shutdown
 */
static void pickup_shutdown(void)
{
    STASIS_MESSAGE_TYPE_CLEANUP(ast_call_pickup_type);
}
 
int ast_pickup_init(void)
{
    STASIS_MESSAGE_TYPE_INIT(ast_call_pickup_type);
    ast_register_cleanup(pickup_shutdown);
 
    return 0;
}