Stasis: Fix StasisStart/End order and missing events

This corrects several bugs that currently exist in the stasis
application code.

* After a masquerade, the resulting channels have channel topics that
  do not match their uniqueids
** Masquerades now swap channel topics appropriately
* StasisStart and StasisEnd messages are leaked to observer
  applications due to being published on channel topics
** StasisStart and StasisEnd publishing is now properly restricted
   to controlling apps via app topics
* Race conditions exist where StasisStart and StasisEnd messages due to
  a masquerade may be received out of order due to being published on
  different topics
** These messages are now published directly on the app topic so this
   is now a non-issue
* StasisEnds are sometimes missing when sent due to masquerades and
  bridge swaps into and out of Stasis()
** This was due to StasisEnd processing adjusting message-sent flags
   after Stasis() had already exited and Stasis() had been re-entered
** This was corrected by adjusting these flags prior to sending the
   message while the initial Stasis() application was still shutting
   down

Review: https://reviewboard.asterisk.org/r/4213/
ASTERISK-24537 #close
Reported by: Matt DiMeo
........

Merged revisions 429061 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/13@429062 65c4cc65-6c06-0410-ace0-fbb531ad65f3

include/asterisk/channel.h

@@ -2464,6 +2464,17 @@ void ast_channel_internal_copy_linkedid(struct ast_channel *dest, struct ast_cha
  */
 void ast_channel_internal_swap_uniqueid_and_linkedid(struct ast_channel *a, struct ast_channel *b);
 
+/*!
+ * \brief Swap topics beteween two channels
+ * \param a First channel
+ * \param b Second channel
+ * \return void
+ *
+ * \note
+ * This is used in masquerade to exchange topics for message routing
+ */
+void ast_channel_internal_swap_topics(struct ast_channel *a, struct ast_channel *b);
+
 /*!
  * \brief Set uniqueid and linkedid string value only (not time)
  * \param chan The channel to set the uniqueid to

main/channel.c

@@ -6519,6 +6519,9 @@ static void channel_do_masquerade(struct ast_channel *original, struct ast_chann
 	 */
 	ast_channel_internal_swap_uniqueid_and_linkedid(clonechan, original);
 
+	/* Make sure the Stasis topic on the channel is updated appropriately */
+	ast_channel_internal_swap_topics(clonechan, original);
+
 	/* Swap channel names. This uses ast_channel_name_set directly, so we
 	 * don't get any spurious rename events.
 	 */

main/channel_internal_api.c

@@ -1534,6 +1534,15 @@ void ast_channel_internal_swap_uniqueid_and_linkedid(struct ast_channel *a, stru
 	b->linkedid = temp;
 }
 
+void ast_channel_internal_swap_topics(struct ast_channel *a, struct ast_channel *b)
+{
+	struct stasis_cp_single *temp;
+
+	temp = a->topics;
+	a->topics = b->topics;
+	b->topics = temp;
+}
+
 void ast_channel_internal_set_fake_ids(struct ast_channel *chan, const char *uniqueid, const char *linkedid)
 {
 	ast_copy_string(chan->uniqueid.unique_id, uniqueid, sizeof(chan->uniqueid.unique_id));

res/res_stasis.c

@@ -125,7 +125,7 @@ static struct ast_json *stasis_end_to_json(struct stasis_message *message,
 		"channel", ast_channel_snapshot_to_json(payload->snapshot, sanitize));
 }
 
-STASIS_MESSAGE_TYPE_DEFN(app_end_message_type,
+STASIS_MESSAGE_TYPE_DEFN_LOCAL(end_message_type,
 	.to_json = stasis_end_to_json);
 
 struct start_message_blob {
@@ -919,6 +919,12 @@ static int send_start_msg_snapshots(struct ast_channel *chan, struct stasis_app
 	struct stasis_message *msg;
 	int i;
 
+	if (app_subscribe_channel(app, chan)) {
+		ast_log(LOG_ERROR, "Error subscribing app '%s' to channel '%s'\n",
+			app_name(app), ast_channel_name(chan));
+		return -1;
+	}
+
 	payload = ao2_alloc(sizeof(*payload), start_message_blob_dtor);
 	if (!payload) {
 		ast_log(LOG_ERROR, "Error packing JSON for StasisStart message\n");
@@ -928,7 +934,8 @@ static int send_start_msg_snapshots(struct ast_channel *chan, struct stasis_app
 	payload->channel = ao2_bump(snapshot);
 	payload->replace_channel = ao2_bump(replace_channel_snapshot);
 
-	json_blob = ast_json_pack("{s: o, s: []}",
+	json_blob = ast_json_pack("{s: s, s: o, s: []}",
+		"app", app_name(app),
 		"timestamp", ast_json_timeval(ast_tvnow(), NULL),
 		"args");
 	if (!json_blob) {
@@ -956,7 +963,10 @@ static int send_start_msg_snapshots(struct ast_channel *chan, struct stasis_app
 		return -1;
 	}
 
-	stasis_publish(ast_channel_topic(chan), msg);
+	if (replace_channel_snapshot) {
+		app_unsubscribe_channel_id(app, replace_channel_snapshot->uniqueid);
+	}
+	stasis_publish(ast_app_get_topic(app), msg);
 	ao2_ref(msg, -1);
 	return 0;
 }
@@ -988,6 +998,7 @@ int app_send_end_msg(struct stasis_app *app, struct ast_channel *chan)
 {
 	struct stasis_message_sanitizer *sanitize = stasis_app_get_sanitizer();
 	struct ast_json *blob;
+	struct stasis_message *msg;
 
 	if (sanitize && sanitize->channel
 		&& sanitize->channel(chan)) {
@@ -1000,10 +1011,13 @@ int app_send_end_msg(struct stasis_app *app, struct ast_channel *chan)
 		return -1;
 	}
 
-	stasis_app_channel_set_stasis_end_published(chan);
 	remove_masquerade_store(chan);
-	ast_channel_publish_blob(chan, app_end_message_type(), blob);
+	app_unsubscribe_channel(app, chan);
-
+	msg = ast_channel_blob_create(chan, end_message_type(), blob);
+	if (msg) {
+		stasis_publish(ast_app_get_topic(app), msg);
+	}
+	ao2_cleanup(msg);
 	ast_json_unref(blob);
 
 	return 0;
@@ -1034,6 +1048,7 @@ static void channel_stolen_cb(void *data, struct ast_channel *old_chan, struct a
 	}
 
 	/* send the StasisEnd message to the app */
+	stasis_app_channel_set_stasis_end_published(new_chan);
 	app_send_end_msg(control_app(control), new_chan);
 
 	/* remove the datastore */
@@ -1083,11 +1098,6 @@ static void channel_replaced_cb(void *data, struct ast_channel *old_chan, struct
 	/* send the StasisEnd message to the app */
 	app_send_end_msg(control_app(control), old_chan);
 
-	/* fixup channel topic forwards */
-	if (app_replace_channel_forwards(control_app(control), old_snapshot->uniqueid, new_chan)) {
-		ast_log(LOG_ERROR, "Failed to fixup channel topic forwards for %s(%s) owned by %s\n",
-			old_snapshot->name, old_snapshot->uniqueid, app_name(control_app(control)));
-	}
 	ao2_cleanup(control);
 }
 
@@ -1251,14 +1261,6 @@ int stasis_app_exec(struct ast_channel *chan, const char *app_name, int argc,
 		return -1;
 	}
 
-	res = app_subscribe_channel(app, chan);
-	if (res != 0) {
-		ast_log(LOG_ERROR, "Error subscribing app '%s' to channel '%s'\n",
-			app_name, ast_channel_name(chan));
-		remove_masquerade_store(chan);
-		return -1;
-	}
-
 	res = send_start_msg(app, chan, argc, argv);
 	if (res != 0) {
 		ast_log(LOG_ERROR,
@@ -1894,7 +1896,7 @@ static int unload_module(void)
 	ao2_cleanup(app_bridges_playback);
 	app_bridges_playback = NULL;
 
-	STASIS_MESSAGE_TYPE_CLEANUP(app_end_message_type);
+	STASIS_MESSAGE_TYPE_CLEANUP(end_message_type);
 	STASIS_MESSAGE_TYPE_CLEANUP(start_message_type);
 
 	return 0;
@@ -1938,28 +1940,6 @@ struct stasis_message_sanitizer *stasis_app_get_sanitizer(void)
 	return &app_sanitizer;
 }
 
-void app_end_message_handler(struct stasis_message *message)
-{
-	struct ast_channel_blob *payload;
-	struct ast_channel_snapshot *snapshot;
-	const char *app_name;
-	char *channel_uri;
-	size_t alloc_size;
-	const char *channels[1];
-
-	payload = stasis_message_data(message);
-	snapshot = payload->snapshot;
-	app_name = ast_json_string_get(ast_json_object_get(payload->blob, "app"));
-
-	/* +8 is for the length of "channel:" */
-	alloc_size = AST_MAX_UNIQUEID + 8;
-	channel_uri = ast_alloca(alloc_size);
-	snprintf(channel_uri, alloc_size, "channel:%s", snapshot->uniqueid);
-
-	channels[0] = channel_uri;
-	stasis_app_unsubscribe(app_name, channels, ARRAY_LEN(channels), NULL);
-}
-
 static const struct ast_datastore_info stasis_internal_channel_info = {
 	.type = "stasis-internal-channel",
 };
@@ -2033,7 +2013,7 @@ static int load_module(void)
 	if (STASIS_MESSAGE_TYPE_INIT(start_message_type) != 0) {
 		return AST_MODULE_LOAD_DECLINE;
 	}
-	if (STASIS_MESSAGE_TYPE_INIT(app_end_message_type) != 0) {
+	if (STASIS_MESSAGE_TYPE_INIT(end_message_type) != 0) {
 		return AST_MODULE_LOAD_DECLINE;
 	}
 	apps_registry = ao2_container_alloc(APPS_NUM_BUCKETS, app_hash, app_compare);

res/stasis/app.c

@@ -302,10 +302,6 @@ static void sub_default_handler(void *data, struct stasis_subscription *sub,
 		call_forwarded_handler(app, message);
 	}
 
-	if (stasis_message_type(message) == app_end_message_type()) {
-		app_end_message_handler(message);
-	}
-
 	/* By default, send any message that has a JSON representation */
 	json = stasis_message_to_json(message, stasis_app_get_sanitizer());
 	if (!json) {
@@ -1128,30 +1124,6 @@ int app_is_subscribed_channel_id(struct stasis_app *app, const char *channel_id)
 	return forwards != NULL;
 }
 
-int app_replace_channel_forwards(struct stasis_app *app, const char *old_id, struct ast_channel *new_chan)
-{
-	RAII_VAR(struct app_forwards *, old_forwards, NULL, ao2_cleanup);
-	struct app_forwards *new_forwards;
-
-	old_forwards = ao2_find(app->forwards, old_id, OBJ_SEARCH_KEY | OBJ_UNLINK);
-	if (!old_forwards) {
-		return -1;
-	}
-
-	new_forwards = forwards_create_channel(app, new_chan);
-	if (!new_forwards) {
-		return -1;
-	}
-
-	new_forwards->interested = old_forwards->interested;
-	ao2_link_flags(app->forwards, new_forwards, 0);
-	ao2_cleanup(new_forwards);
-
-	/* Clean up old forwards */
-	forwards_unsubscribe(old_forwards);
-	return 0;
-}
-
 static void *channel_find(const struct stasis_app *app, const char *id)
 {
 	return ast_channel_get_by_name(id);

res/stasis/app.h

@@ -258,18 +258,6 @@ int app_set_replace_channel_app(struct ast_channel *chan, const char *replace_ap
  */
 char *app_get_replace_channel_app(struct ast_channel *chan);
 
-/*!
- * \brief Replace channel topic forwards for the old channel with forwards for the new channel
- *
- * \param app The app that owns the channel
- * \param old_id The unique ID of the channel to be replaced
- * \param new_chan The channel that is replacing the old one
- *
- * \retval zero on success
- * \return non-zero on failure
- */
-int app_replace_channel_forwards(struct stasis_app *app, const char *old_id, struct ast_channel *new_chan);
-
 /*!
  * \brief Send StasisEnd message to the listening app
  *
@@ -281,16 +269,4 @@ int app_replace_channel_forwards(struct stasis_app *app, const char *old_id, str
  */
 int app_send_end_msg(struct stasis_app *app, struct ast_channel *chan);
 
-/*!
- * \brief Handle cleanup related to StasisEnd messages
- *
- * \param message The message for which to clean up
- */
-void app_end_message_handler(struct stasis_message *message);
-
-/*!
- * \brief Accessor for the StasisEnd message type
- */
-struct stasis_message_type *app_end_message_type(void);
-
 #endif /* _ASTERISK_RES_STASIS_APP_H */

res/stasis/stasis_bridge.c

@@ -175,6 +175,7 @@ static int bridge_stasis_moving(struct ast_bridge_channel *bridge_channel, void
 			return -1;
 		}
 
+		stasis_app_channel_set_stasis_end_published(chan);
 		app_send_end_msg(control_app(control), chan);
 	}