autoservice.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2008, Digium, Inc.
 *
 * Mark Spencer <[email protected]>
 * Russell Bryant <[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 Automatic channel service routines
 *
 * \author Mark Spencer <[email protected]>
 * \author Russell Bryant <[email protected]>
 */

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

#include "asterisk.h"

#include <sys/time.h>
#include <signal.h>

#include "asterisk/_private.h" /* prototype for ast_autoservice_init() */

#include "asterisk/pbx.h"
#include "asterisk/frame.h"
#include "asterisk/sched.h"
#include "asterisk/channel.h"
#include "asterisk/file.h"
#include "asterisk/translate.h"
#include "asterisk/manager.h"
#include "asterisk/chanvars.h"
#include "asterisk/linkedlists.h"
#include "asterisk/indications.h"
#include "asterisk/lock.h"
#include "asterisk/utils.h"

#define MAX_AUTOMONS 1500

struct asent {
 struct ast_channel *chan;
 /*! This gets incremented each time autoservice gets started on the same
 * channel. It will ensure that it doesn't actually get stopped until
 * it gets stopped for the last time. */
 unsigned int use_count;
 unsigned int orig_end_dtmf_flag:1;
 unsigned int video_update:1;
 unsigned int ignore_frame_types;
 /*! Frames go on at the head of deferred_frames, so we have the frames
 * from newest to oldest. As we put them at the head of the readq, we'll
 * end up with them in the right order for the channel's readq. */
 AST_LIST_HEAD_NOLOCK(, ast_frame) deferred_frames;
 AST_LIST_ENTRY(asent) list;
};

static AST_LIST_HEAD_STATIC(aslist, asent);
static ast_cond_t as_cond;

static pthread_t asthread = AST_PTHREADT_NULL;
static volatile int asexit = 0;

static int as_chan_list_state;

static void *autoservice_run(void *ign)
{
 ast_callid callid = 0;
 struct ast_frame hangup_frame = {
 .frametype = AST_FRAME_CONTROL,
 .subclass.integer = AST_CONTROL_HANGUP,
 };

 while (!asexit) {
 struct ast_channel *mons[MAX_AUTOMONS];
 struct asent *ents[MAX_AUTOMONS];
 struct ast_channel *chan;
 struct asent *as;
 int i, x = 0, ms = 50;
 struct ast_frame *f = NULL;
 struct ast_frame *defer_frame = NULL;

 AST_LIST_LOCK(&aslist);

 /* At this point, we know that no channels that have been removed are going
 * to get used again. */
 as_chan_list_state++;

 if (AST_LIST_EMPTY(&aslist)) {
 ast_cond_wait(&as_cond, &aslist.lock);
 }

 AST_LIST_TRAVERSE(&aslist, as, list) {
 if (!ast_check_hangup(as->chan)) {
 if (x < MAX_AUTOMONS) {
 ents[x] = as;
 mons[x++] = as->chan;
 } else {
 ast_log(LOG_WARNING, "Exceeded maximum number of automatic monitoring events. Fix autoservice.c\n");
 }
 }
 }

 AST_LIST_UNLOCK(&aslist);

 if (!x) {
 /* If we don't sleep, this becomes a busy loop, which causes
 * problems when Asterisk runs at a different priority than other
 * user processes. As long as we check for new channels at least
 * once every 10ms, we should be fine. */
 usleep(10000);
 continue;
 }

 chan = ast_waitfor_n(mons, x, &ms);
 if (!chan) {
 continue;
 }

 callid = ast_channel_callid(chan);
 ast_callid_threadassoc_change(callid);

 f = ast_read(chan);

 if (!f) {
 /* No frame means the channel has been hung up.
 * A hangup frame needs to be queued here as ast_waitfor() may
 * never return again for the condition to be detected outside
 * of autoservice. So, we'll leave a HANGUP queued up so the
 * thread in charge of this channel will know. */

 defer_frame = &hangup_frame;
 } else if (ast_is_deferrable_frame(f)) {
 defer_frame = f;
 } else {
 /* Can't defer. Discard and continue with next. */
 ast_frfree(f);
 continue;
 }

 for (i = 0; i < x; i++) {
 struct ast_frame *dup_f;

 if (mons[i] != chan) {
 continue;
 }

 if (!f) { /* defer_frame == &hangup_frame */
 if ((dup_f = ast_frdup(defer_frame))) {
 AST_LIST_INSERT_HEAD(&ents[i]->deferred_frames, dup_f, frame_list);
 }
 } else {
 if (defer_frame->frametype == AST_FRAME_CONTROL &&
 defer_frame->subclass.integer == AST_CONTROL_VIDUPDATE) {

 /* If a video update is already queued don't needlessly queue another */
 if (ents[i]->video_update) {
 ast_frfree(defer_frame);
 break;
 }

 ents[i]->video_update = 1;
 }
 if ((dup_f = ast_frisolate(defer_frame))) {
 AST_LIST_INSERT_HEAD(&ents[i]->deferred_frames, dup_f, frame_list);
 }
 if (dup_f != defer_frame) {
 ast_frfree(defer_frame);
 }
 }

 break;
 }
 /* The ast_waitfor_n() call will only read frames from
 * the channels' file descriptors. If ast_waitfor_n()
 * returns non-NULL, then one of the channels in the
 * mons array must have triggered the return. It's
 * therefore impossible that we got here while (i >= x).
 * If we did, we'd need to ast_frfree(f) if (f). */
 }

 ast_callid_threadassoc_change(0);
 asthread = AST_PTHREADT_NULL;

 return NULL;
}

int ast_autoservice_start(struct ast_channel *chan)
{
 int res = 0;
 struct asent *as;

 if (ast_thread_is_user_interface()) {
 /* User interface threads do not handle channel media. */
 ast_debug(1, "Thread is a user interface, not putting channel %s into autoservice\n",
 ast_channel_name(chan));
 return 0;
 }

 AST_LIST_LOCK(&aslist);
 AST_LIST_TRAVERSE(&aslist, as, list) {
 if (as->chan == chan) {
 as->use_count++;
 break;
 }
 }
 AST_LIST_UNLOCK(&aslist);

 if (as) {
 /* Entry exists, autoservice is already handling this channel */
 return 0;
 }

 if (!(as = ast_calloc(1, sizeof(*as))))
 return -1;

 /* New entry created */
 as->chan = chan;
 as->use_count = 1;

 ast_channel_lock(chan);
 as->orig_end_dtmf_flag = ast_test_flag(ast_channel_flags(chan), AST_FLAG_END_DTMF_ONLY) ? 1 : 0;
 if (!as->orig_end_dtmf_flag)
 ast_set_flag(ast_channel_flags(chan), AST_FLAG_END_DTMF_ONLY);
 ast_channel_unlock(chan);

 AST_LIST_LOCK(&aslist);

 if (AST_LIST_EMPTY(&aslist) && asthread != AST_PTHREADT_NULL) {
 ast_cond_signal(&as_cond);
 }

 AST_LIST_INSERT_HEAD(&aslist, as, list);

 if (asthread == AST_PTHREADT_NULL) { /* need start the thread */
 if (ast_pthread_create_background(&asthread, NULL, autoservice_run, NULL)) {
 ast_log(LOG_WARNING, "Unable to create autoservice thread :(\n");
 /* There will only be a single member in the list at this point,
 the one we just added. */
 AST_LIST_REMOVE(&aslist, as, list);
 ast_free(as);
 asthread = AST_PTHREADT_NULL;
 res = -1;
 } else {
 pthread_kill(asthread, SIGURG);
 }
 }

 AST_LIST_UNLOCK(&aslist);

 return res;
}

int ast_autoservice_stop(struct ast_channel *chan)
{
 int res = -1;
 struct asent *as, *removed = NULL;
 struct ast_frame *f;
 int chan_list_state;

 if (ast_thread_is_user_interface()) {
 /* User interface threads do not handle channel media. */
 ast_debug(1, "Thread is a user interface, not removing channel %s from autoservice\n",
 ast_channel_name(chan));
 return 0;
 }

 AST_LIST_LOCK(&aslist);

 /* Save the autoservice channel list state. We _must_ verify that the channel
 * list has been rebuilt before we return. Because, after we return, the channel
 * could get destroyed and we don't want our poor autoservice thread to step on
 * it after its gone! */
 chan_list_state = as_chan_list_state;

 /* Find the entry, but do not free it because it still can be in the
 autoservice thread array */
 AST_LIST_TRAVERSE_SAFE_BEGIN(&aslist, as, list) {
 if (as->chan == chan) {
 as->use_count--;
 if (as->use_count < 1) {
 AST_LIST_REMOVE_CURRENT(list);
 removed = as;
 }
 break;
 }
 }
 AST_LIST_TRAVERSE_SAFE_END;

 if (removed && asthread != AST_PTHREADT_NULL) {
 pthread_kill(asthread, SIGURG);
 }

 AST_LIST_UNLOCK(&aslist);

 if (!removed) {
 return 0;
 }

 /* Wait while autoservice thread rebuilds its list. */
 while (chan_list_state == as_chan_list_state) {
 usleep(1000);
 }

 /* Now autoservice thread should have no references to our entry
 and we can safely destroy it */

 if (!ast_channel_softhangup_internal_flag(chan)) {
 res = 0;
 }

 ast_channel_lock(chan);
 if (!as->orig_end_dtmf_flag) {
 ast_clear_flag(ast_channel_flags(chan), AST_FLAG_END_DTMF_ONLY);
 }

 while ((f = AST_LIST_REMOVE_HEAD(&as->deferred_frames, frame_list))) {
 if (!((1 << f->frametype) & as->ignore_frame_types)) {
 ast_queue_frame_head(chan, f);
 }
 ast_frfree(f);
 }
 ast_channel_unlock(chan);

 ast_free(as);

 return res;
}

void ast_autoservice_chan_hangup_peer(struct ast_channel *chan, struct ast_channel *peer)
{
 if (chan && !ast_autoservice_start(chan)) {
 ast_hangup(peer);
 ast_autoservice_stop(chan);
 } else {
 ast_hangup(peer);
 }
}

int ast_autoservice_ignore(struct ast_channel *chan, enum ast_frame_type ftype)
{
 struct asent *as;
 int res = -1;

 AST_LIST_LOCK(&aslist);
 AST_LIST_TRAVERSE(&aslist, as, list) {
 if (as->chan == chan) {
 res = 0;
 as->ignore_frame_types |= (1 << ftype);
 break;
 }
 }
 AST_LIST_UNLOCK(&aslist);
 return res;
}

static void autoservice_shutdown(void)
{
 pthread_t th = asthread;
 asexit = 1;
 if (th != AST_PTHREADT_NULL) {
 ast_cond_signal(&as_cond);
 pthread_kill(th, SIGURG);
 pthread_join(th, NULL);
 }
}

void ast_autoservice_init(void)
{
 ast_register_cleanup(autoservice_shutdown);
 ast_cond_init(&as_cond, NULL);
}