app_confbridge: Use bridge join hook to send join and leave events

The first attempt at publishing confbridge events to participants
involved publishing them at the same time stasis events were
created.  This caused issues with bridge and channel locks.  The
second attempt involved publishing them when the stasis events
were received by the code that published the confbridge AMI events.
This caused timing issues because, depending on resources available,
the event could be received before channels actually joined the
bridge and would therefore fail to send messages to the participant.

This attempt reverts to the original mechanism with one exception.
The join and leave events are published via bridge join and leave
hooks.  This guarantees the states of the channels and bridge and
provides deterministic timing for event publishing.

Change-Id: I2660074f8a30a5224cb953d5e047ee84484a9036

apps/app_confbridge.c

@@ -576,6 +576,10 @@ static void send_conf_stasis(struct confbridge_conference *conference, struct as
 		return;
 	}
 
+	if (ast_test_flag(&conference->b_profile, BRIDGE_OPT_ENABLE_EVENTS)) {
+		conf_send_event_to_participants(conference, chan, msg);
+	}
+
 	if (channel_topic) {
 		stasis_publish(ast_channel_topic(chan), msg);
 	} else {
@@ -2311,6 +2315,25 @@ static int join_callback(struct ast_bridge_channel *bridge_channel, void *ignore
 	return 0;
 }
 
+struct confbridge_hook_data {
+	struct confbridge_conference *conference;
+	struct confbridge_user *user;
+	enum ast_bridge_hook_type hook_type;
+};
+
+static int send_event_hook_callback(struct ast_bridge_channel *bridge_channel, void *data)
+{
+	struct confbridge_hook_data *hook_data = data;
+
+	if (hook_data->hook_type == AST_BRIDGE_HOOK_TYPE_JOIN) {
+		send_join_event(hook_data->user, hook_data->conference);
+	} else {
+		send_leave_event(hook_data->user, hook_data->conference);
+	}
+
+	return 0;
+}
+
 /*! \brief The ConfBridge application */
 static int confbridge_exec(struct ast_channel *chan, const char *data)
 {
@@ -2328,6 +2351,9 @@ static int confbridge_exec(struct ast_channel *chan, const char *data)
 		.tech_args.silence_threshold = DEFAULT_SILENCE_THRESHOLD,
 		.tech_args.drop_silence = 0,
 	};
+	struct confbridge_hook_data *join_hook_data;
+	struct confbridge_hook_data *leave_hook_data;
+
 	AST_DECLARE_APP_ARGS(args,
 		AST_APP_ARG(conf_name);
 		AST_APP_ARG(b_profile_name);
@@ -2510,8 +2536,39 @@ static int confbridge_exec(struct ast_channel *chan, const char *data)
 
 	conf_moh_unsuspend(&user);
 
-	/* Join our conference bridge for real */
+	join_hook_data = ast_malloc(sizeof(*join_hook_data));
-	send_join_event(&user, conference);
+	if (!join_hook_data) {
+		res = -1;
+		goto confbridge_cleanup;
+	}
+	join_hook_data->user = &user;
+	join_hook_data->conference = conference;
+	join_hook_data->hook_type = AST_BRIDGE_HOOK_TYPE_JOIN;
+	res = ast_bridge_join_hook(&user.features, send_event_hook_callback,
+		join_hook_data, ast_free_ptr, 0);
+	if (res) {
+		ast_free(join_hook_data);
+		ast_log(LOG_ERROR, "Couldn't add bridge join hook for channel '%s'\n", ast_channel_name(chan));
+		goto confbridge_cleanup;
+	}
+
+	leave_hook_data = ast_malloc(sizeof(*leave_hook_data));
+	if (!leave_hook_data) {
+		/* join_hook_data is cleaned up by ast_bridge_features_cleanup via the goto */
+		res = -1;
+		goto confbridge_cleanup;
+	}
+	leave_hook_data->user = &user;
+	leave_hook_data->conference = conference;
+	leave_hook_data->hook_type = AST_BRIDGE_HOOK_TYPE_LEAVE;
+	res = ast_bridge_leave_hook(&user.features, send_event_hook_callback,
+		leave_hook_data, ast_free_ptr, 0);
+	if (res) {
+		/* join_hook_data is cleaned up by ast_bridge_features_cleanup via the goto */
+		ast_free(leave_hook_data);
+		ast_log(LOG_ERROR, "Couldn't add bridge leave hook for channel '%s'\n", ast_channel_name(chan));
+		goto confbridge_cleanup;
+	}
 
 	if (ast_bridge_join_hook(&user.features, join_callback, NULL, NULL, 0)) {
 		async_play_sound_ready(user.chan);
@@ -2533,8 +2590,6 @@ static int confbridge_exec(struct ast_channel *chan, const char *data)
 		pbx_builtin_setvar_helper(chan, "CONFBRIDGE_RESULT", "HANGUP");
 	}
 
-	send_leave_event(&user, conference);
-
 	/* if we're shutting down, don't attempt to do further processing */
 	if (ast_shutting_down()) {
 		/*

apps/confbridge/confbridge_manager.c

@@ -395,6 +395,9 @@ static void set_media_labels(struct confbridge_conference *conference,
 	struct ast_stream *stream;
 	struct ast_channel *chan = dir == LABEL_DIRECTION_SRC ? dest_chan : src_chan;
 
+	if (!chan) {
+		return;
+	}
 	topology = ast_channel_get_stream_topology(chan);
 	stream = get_stream(topology, AST_MEDIA_TYPE_VIDEO);
 	if (stream) {
@@ -458,8 +461,8 @@ static void send_message(const char *msg_name, char *conf_name, struct ast_json
 	ast_json_free(json);
 }
 
-static void send_event_to_participants(struct confbridge_conference *conference,
+void conf_send_event_to_participants(struct confbridge_conference *conference,
-	struct ast_channel *chan, struct stasis_message * msg)
+	struct ast_channel *chan, struct stasis_message *msg)
 {
 	struct ast_bridge_blob *obj = stasis_message_data(msg);
 	struct ast_json *extras = obj->blob;
@@ -597,13 +600,6 @@ static void confbridge_publish_manager_event(
 		struct confbridge_conference *conference = conf_find_bridge(conference_name);
 
 		channel_text = ast_manager_build_channel_state_string(blob->channel);
-
-		if (conference && ast_test_flag(&conference->b_profile, BRIDGE_OPT_ENABLE_EVENTS)) {
-			struct ast_channel *chan = ast_channel_get_by_name(blob->channel->name);
-
-			send_event_to_participants(conference, chan, message);
-			ast_channel_cleanup(chan);
-		}
 		ao2_cleanup(conference);
 	}
 

apps/confbridge/include/confbridge.h

@@ -701,6 +701,16 @@ int conf_announce_channel_push(struct ast_channel *ast);
  */
 struct confbridge_conference *conf_find_bridge(const char *conference_name);
 
-
+/*!
+ * \brief Send events to bridge participants.
+ * \since 15.7
+ * \since 16.1
+ *
+ * \param conference The conference bridge
+ * \param chan The channel triggering the action
+ * \param msg The stasis message describing the event
+ */
+void conf_send_event_to_participants(struct confbridge_conference *conference,
+	struct ast_channel *chan, struct stasis_message *msg);
 
 #endif