add option to control whether sub errors are fatal for bridge connect…

…ions

Signed-off-by: Abilio Marques <[email protected]>

ChangeLog.txt

@@ -74,6 +74,8 @@ Broker:
   choose TLS v1.1, but this is not recommended and will be removed in a future
   version.
 - Add -q option to allow logging to be disabled at the command line.
+- Add `bridge_outgoing_retain` option to control what happens when a bridge
+  fails to subscribe to a topic.
 
 Plugins / plugin interface:
 - Add persist-sqlite plugin.

fuzzing/corpora/broker_conf.dict

@@ -29,6 +29,7 @@
 "bridge_max_packet_size"
 "bridge_max_topic_alias"
 "bridge_outgoing_retain"
+"bridge_fatal_sub_errors"
 "bridge_protocol_version"
 "bridge_psk"
 "bridge_receive_maximum"

man/mosquitto.conf.5.xml

@@ -1899,7 +1899,16 @@ openssl dhparam -out dhparam.pem 2048</programlisting>
 						other setting. Defaults to <replaceable>true</replaceable>.</para>
 				</listitem>
 			</varlistentry>
-
+			<varlistentry>
+				<term><option>bridge_fatal_sub_errors</option> [ true | false ]</term>
+				<listitem>
+					<para> A failure to subscribe to a topic will cause an immediate
+						disconnection. The hope is that a temporary failure will disappear
+						after reconnecting. If you desire to silently ignore subscription
+						errors (not advised), you can set the bridge_fatal_sub_errors
+						option to false. Defaults to <replaceable>true</replaceable>.</para>
+				</listitem>
+			</varlistentry>
 			<varlistentry>
 				<term><option>bridge_protocol_version</option> <replaceable>version</replaceable></term>
 				<listitem>

mosquitto.conf

@@ -940,6 +940,12 @@
 # all outgoing messages to that bridge, regardless of any other setting.
 #bridge_outgoing_retain true
 
+# A failure to subscribe to a topic will cause an immediate disconnection. The
+# hope is that a temporary failure will disappear after reconnecting. If you
+# desire to silently ignore subscription errors (not advised), you can set the
+# bridge_fatal_sub_errors option to false.
+#bridge_fatal_sub_errors true
+
 # If you wish to restrict the size of messages sent to a remote bridge, use the
 # bridge_max_packet_size option. This sets the maximum number of bytes for
 # the total message, including headers and payload.

src/bridge.c

@@ -717,7 +717,7 @@ int bridge__on_connect(struct mosquitto *context)
 }
 
 int bridge__on_suback(struct mosquitto *context, int qos) {
-	if (qos > 2) {
+	if (qos > 2 && context->bridge->fatal_sub_errors) {
 		log__printf(NULL, MOSQ_LOG_ERR, "Error on bridge subscription: %s", mosquitto_reason_string(qos));
 		do_disconnect(context, MOSQ_ERR_CONN_LOST);
 	}

src/conf.c

@@ -1313,6 +1313,13 @@ static int config__read_file_core(struct mosquitto__config *config, bool reload,
 					if(conf__parse_bool(&token, "bridge_outgoing_retain", &cur_bridge->outgoing_retain, &saveptr)) return MOSQ_ERR_INVAL;
 #else
 					log__printf(NULL, MOSQ_LOG_WARNING, "Warning: Bridge support not available.");
+#endif
+				}else if(!strcmp(token, "bridge_fatal_sub_errors")){
+#if defined(WITH_BRIDGE)
+					REQUIRE_BRIDGE(token);
+					if(conf__parse_bool(&token, "bridge_fatal_sub_errors", &cur_bridge->fatal_sub_errors, &saveptr)) return MOSQ_ERR_INVAL;
+#else
+					log__printf(NULL, MOSQ_LOG_WARNING, "Warning: Bridge support not available.");
 #endif
 				}else if(!strcmp(token, "bridge_keyfile")){
 #if defined(WITH_BRIDGE) && defined(WITH_TLS)
@@ -1585,6 +1592,7 @@ static int config__read_file_core(struct mosquitto__config *config, bool reload,
 					cur_bridge->protocol_version = mosq_p_mqtt311;
 					cur_bridge->primary_retry_sock = INVALID_SOCKET;
 					cur_bridge->outgoing_retain = true;
+					cur_bridge->fatal_sub_errors = true;
 					cur_bridge->clean_start_local = -1;
 					cur_bridge->reload_type = brt_lazy;
 					cur_bridge->max_topic_alias = 10;

src/mosquitto_broker_internal.h

@@ -598,6 +598,7 @@ struct mosquitto__bridge{
 	bool attempt_unsubscribe;
 	bool initial_notification_done;
 	bool outgoing_retain;
+	bool fatal_sub_errors;
 	enum mosquitto_bridge_reload_type reload_type;
 	uint16_t max_topic_alias;
 #ifdef WITH_TLS