Add support for local only bridge notifications (#328)

This update adds an option to only publishes bridge
notification messages to the local side of the bridge.

It adds a config file option called notifications_local_only
that accepts a boolean value, defaults to false to be
consistent with existing behaviour.

Fixes #233

Signed-off-by: Ben Hardill <hardillb@uk.ibm.com>

man/mosquitto.conf.5.xml

@@ -1088,6 +1088,15 @@
 						connection has failed. Defaults to
 						<replaceable>true</replaceable>.</para>
 				</listitem>
+			</varlistentry>
+			 <varlistentry>
+				<term><option>notifications_local_only</option> [ true | false ]</term>
+				<listitem>
+					<para>If set to <replaceable>true</replaceable>, only publish
+						notification messages to the local broker giving 
+						information about the state of the bridge connection.
+						Defaults to <replaceable>false</replaceable>.</para>
+				</listitem>
 			</varlistentry>
 			<varlistentry>
 				<term><option>notification_topic</option> <replaceable>topic</replaceable></term>

src/bridge.c

@@ -149,11 +149,14 @@ int bridge__connect(struct mosquitto_db *db, struct mosquitto *context)
 				db__messages_easy_queue(db, context, context->bridge->notification_topic, 1, 1, &notification_payload, 1);
 				context->bridge->initial_notification_done = true;
 			}
+
+			if (!context->bridge->notifications_local_only) {
 				notification_payload = '0';
 				rc = will__set(context, context->bridge->notification_topic, 1, &notification_payload, 1, true);
 				if(rc != MOSQ_ERR_SUCCESS){
 					return rc;
 				}
+			}
 		}else{
 			notification_topic_len = strlen(context->bridge->remote_clientid)+strlen("$SYS/broker/connection//state");
 			notification_topic = mosquitto__malloc(sizeof(char)*(notification_topic_len+1));
@@ -167,6 +170,7 @@ int bridge__connect(struct mosquitto_db *db, struct mosquitto *context)
 				context->bridge->initial_notification_done = true;
 			}
 
+			if (!context->bridge->notifications_local_only) {
 				notification_payload = '0';
 				rc = will__set(context, notification_topic, 1, &notification_payload, 1, true);
 				mosquitto__free(notification_topic);
@@ -175,6 +179,7 @@ int bridge__connect(struct mosquitto_db *db, struct mosquitto *context)
 				}
 			}
 		}
+	}
 
 	log__printf(NULL, MOSQ_LOG_NOTICE, "Connecting bridge %s (%s:%d)", context->bridge->name, context->bridge->addresses[context->bridge->cur_address].address, context->bridge->addresses[context->bridge->cur_address].port);
 	rc = net__socket_connect(context, context->bridge->addresses[context->bridge->cur_address].address, context->bridge->addresses[context->bridge->cur_address].port, NULL, false);

src/conf.c

@@ -968,6 +968,7 @@ int config__read_file_core(struct mosquitto__config *config, bool reload, const
 						}
 						cur_bridge->keepalive = 60;
 						cur_bridge->notifications = true;
+						cur_bridge->notifications_local_only = false;
 						cur_bridge->start_type = bst_automatic;
 						cur_bridge->idle_timeout = 60;
 						cur_bridge->restart_timeout = 30;
@@ -1355,6 +1356,17 @@ int config__read_file_core(struct mosquitto__config *config, bool reload, const
 					if(conf__parse_bool(&token, "notifications", &cur_bridge->notifications, saveptr)) return MOSQ_ERR_INVAL;
 #else
 					log__printf(NULL, MOSQ_LOG_WARNING, "Warning: Bridge support not available.");
+#endif
+				}else if(!strcmp(token, "notifications_local_only")){
+#ifdef WITH_BRIDGE
+					if(reload) continue; // FIXME
+					if(!cur_bridge){
+						log__printf(NULL, MOSQ_LOG_ERR, "Error: Invalid bridge configuration");
+						return MOSQ_ERR_INVAL;
+					}
+					if(conf__parse_bool(&token, "notifications_local_only", &cur_bridge->notifications_local_only, saveptr)) return MOSQ_ERR_INVAL;
+#else					
+					log__printf(NULL, MOSQ_LOG_WARNING, "Warning: Bridge support not available.");
 #endif
 				}else if(!strcmp(token, "notification_topic")){
 #ifdef WITH_BRIDGE

src/handle_connack.c

@@ -46,11 +46,13 @@ int handle__connack(struct mosquitto_db *db, struct mosquitto *context)
 				if(context->bridge->notifications){
 					notification_payload = '1';
 					if(context->bridge->notification_topic){
+						if(!context->bridge->notifications_local_only){
 							if(send__real_publish(context, mosquitto__mid_generate(context),
 									context->bridge->notification_topic, 1, &notification_payload, 1, true, 0)){
 
 								return 1;
 							}
+						}
 						db__messages_easy_queue(db, context, context->bridge->notification_topic, 1, 1, &notification_payload, 1);
 					}else{
 						notification_topic_len = strlen(context->bridge->remote_clientid)+strlen("$SYS/broker/connection//state");
@@ -59,12 +61,14 @@ int handle__connack(struct mosquitto_db *db, struct mosquitto *context)
 
 						snprintf(notification_topic, notification_topic_len+1, "$SYS/broker/connection/%s/state", context->bridge->remote_clientid);
 						notification_payload = '1';
+						if(!context->bridge->notifications_local_only){
 							if(send__real_publish(context, mosquitto__mid_generate(context),
 									notification_topic, 1, &notification_payload, 1, true, 0)){
 
 								mosquitto__free(notification_topic);
 								return 1;
 							}
+						}
 						db__messages_easy_queue(db, context, notification_topic, 1, 1, &notification_payload, 1);
 						mosquitto__free(notification_topic);
 					}

src/mosquitto_broker_internal.h

@@ -422,6 +422,7 @@ struct mosquitto__bridge{
 	char *local_username;
 	char *local_password;
 	bool notifications;
+	bool notifications_local_only;
 	char *notification_topic;
 	enum mosquitto_bridge_start_type start_type;
 	int idle_timeout;