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);
}