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

/*! \file
 *
 * \brief Routines implementing call pickup
 *
 * \author Matt Jordan <[email protected]>
 */

/*!
 * \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
 * \param chan channel that initiated pickup.
 *
 * 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_connected_line_macro(NULL, chan, &connected_caller, 0, 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;
}