Add bridge_session_expiry_interval option for MQTT v5.0 bridges.

ChangeLog.txt

@@ -85,6 +85,7 @@ Broker:
 - Allow multiple instances of mosquitto to run as services on Windows. See
   README-windows.txt.
 - Add ability to deny wildcard subscriptions for a role to the dynsec plugin.
+- Add bridge_session_expiry_interval option for MQTT v5.0 bridges.
 
 Client library:
 - Add MOSQ_OPT_DISABLE_SOCKETPAIR to allow the disabling of the socketpair

man/mosquitto.conf.5.xml

@@ -1828,6 +1828,21 @@ openssl dhparam -out dhparam.pem 2048</programlisting>
 						<replaceable>mqttv311</replaceable>.</para>
 				</listitem>
 			</varlistentry>
+			<varlistentry>
+				<term><option>bridge_session_expiry_interval</option> <replaceable>interval</replaceable></term>
+				<listitem>
+					<para>
+						If the bridge is using MQTT v5.0 then use
+						<option>bridge_session_expiry_interval</option>
+						to set the session expiry interval. Set to
+						<replaceable>0</replaceable> to have the session expire
+						immediately when the connection drops. Set to
+						<replaceable>0xFFFFFFFF</replaceable> to have an infinite
+						expiry interval. Otherwise the expiry interval is set to
+						the number of seconds that you specify. Defaults to 0.
+					</para>
+				</listitem>
+			</varlistentry>
 			<varlistentry>
 				<term><option>bridge_tcp_keepalive</option> <replaceable>idle</replaceable> <replaceable>interval</replaceable> <replaceable>counter</replaceable></term>
 				<listitem>

mosquitto.conf

@@ -778,6 +778,14 @@
 # remote broker, and delivered when the bridge reconnects.
 #cleansession false
 
+# If the bridge is using MQTT v5.0 then use bridge_session_expiry_interval to
+# set the session expiry interval. Set to 0 to have the session expire
+# immediately when the connection drops. Set to 0xFFFFFFFF to have an infinite
+# expiry interval. Otherwise the expiry interval is set to the number of
+# seconds that you specify.
+# Defaults to 0.
+#bridge_session_expiry_interval 0
+
 # Set the amount of time a bridge using the lazy start type must be idle before
 # it will be stopped. Defaults to 60 seconds.
 #idle_timeout 60

src/bridge.c

@@ -366,7 +366,9 @@ static int bridge__connect_step2(struct mosquitto *context)
 int bridge__connect_step3(struct mosquitto *context)
 {
 	int rc;
-	mosquitto_property topic_alias_max, *topic_alias_max_prop = NULL;
+	mosquitto_property topic_alias_max;
+	mosquitto_property session_expiry_interval;
+	mosquitto_property *properties = NULL;
 
 	rc = net__socket_connect_step3(context, context->bridge->addresses[context->bridge->cur_address].address);
 	if(rc > 0){
@@ -394,14 +396,21 @@ int bridge__connect_step3(struct mosquitto *context)
 #endif
 
 	if(context->bridge->max_topic_alias != 0){
-		topic_alias_max.next = NULL;
 		topic_alias_max.value.i16 = context->bridge->max_topic_alias;
 		topic_alias_max.identifier = MQTT_PROP_TOPIC_ALIAS_MAXIMUM;
 		topic_alias_max.client_generated = false;
-		topic_alias_max_prop = &topic_alias_max;
+		topic_alias_max.next = properties;
+		properties = &topic_alias_max;
+	}
+	if(context->bridge->session_expiry_interval != 0){
+		session_expiry_interval.value.i32 = context->bridge->session_expiry_interval;
+		session_expiry_interval.identifier = MQTT_PROP_SESSION_EXPIRY_INTERVAL;
+		session_expiry_interval.client_generated = false;
+		session_expiry_interval.next = properties;
+		properties = &session_expiry_interval;
 	}
 
-	rc = send__connect(context, context->keepalive, context->clean_start, topic_alias_max_prop);
+	rc = send__connect(context, context->keepalive, context->clean_start, properties);
 	if(rc == MOSQ_ERR_SUCCESS){
 		return MOSQ_ERR_SUCCESS;
 	}else if(rc == MOSQ_ERR_ERRNO && errno == ENOTCONN){
@@ -429,7 +438,9 @@ int bridge__connect(struct mosquitto *context)
 	uint8_t notification_payload;
 	struct mosquitto__bridge_topic *cur_topic;
 	uint8_t qos;
-	mosquitto_property topic_alias_max, *topic_alias_max_prop = NULL;
+	mosquitto_property topic_alias_max;
+	mosquitto_property session_expiry_interval;
+	mosquitto_property *properties = NULL;
 
 	if(!context || !context->bridge) return MOSQ_ERR_INVAL;
 
@@ -550,14 +561,21 @@ int bridge__connect(struct mosquitto *context)
 #endif
 
 	if(context->bridge->max_topic_alias){
-		topic_alias_max.next = NULL;
 		topic_alias_max.value.i16 = context->bridge->max_topic_alias;
 		topic_alias_max.identifier = MQTT_PROP_TOPIC_ALIAS_MAXIMUM;
 		topic_alias_max.client_generated = false;
-		topic_alias_max_prop = &topic_alias_max;
+		topic_alias_max.next = properties;
+		properties = &topic_alias_max;
+	}
+	if(context->bridge->session_expiry_interval != 0){
+		session_expiry_interval.value.i32 = context->bridge->session_expiry_interval;
+		session_expiry_interval.identifier = MQTT_PROP_SESSION_EXPIRY_INTERVAL;
+		session_expiry_interval.client_generated = false;
+		session_expiry_interval.next = properties;
+		properties = &session_expiry_interval;
 	}
 
-	rc2 = send__connect(context, context->keepalive, context->clean_start, topic_alias_max_prop);
+	rc2 = send__connect(context, context->keepalive, context->clean_start, properties);
 	if(rc2 == MOSQ_ERR_SUCCESS){
 		return rc;
 	}else if(rc2 == MOSQ_ERR_ERRNO && errno == ENOTCONN){

src/conf.c

@@ -1292,6 +1292,25 @@ static int config__read_file_core(struct mosquitto__config *config, bool reload,
 					}
 #else
 					log__printf(NULL, MOSQ_LOG_WARNING, "Warning: Bridge support not available.");
+#endif
+				}else if(!strcmp(token, "bridge_session_expiry_interval")){
+#if defined(WITH_BRIDGE)
+					if(reload) continue; /* Bridges not valid for reloading. */
+					if(!cur_bridge){
+						log__printf(NULL, MOSQ_LOG_ERR, "Error: Invalid bridge configuration.");
+						return MOSQ_ERR_INVAL;
+					}
+					if(conf__parse_int(&token, "bridge_session_expiry_interval", &tmp_int, &saveptr)) return MOSQ_ERR_INVAL;
+					if(tmp_int < 0){
+						log__printf(NULL, MOSQ_LOG_ERR, "Error: bridge_session_expiry_interval must not be negative.");
+						return MOSQ_ERR_INVAL;
+					}else if((uint64_t)tmp_int > (uint64_t)UINT32_MAX){
+						log__printf(NULL, MOSQ_LOG_ERR, "Error: bridge_session_expiry_interval must be lower than %u.", UINT32_MAX);
+						return MOSQ_ERR_INVAL;
+					}
+					cur_bridge->session_expiry_interval = (uint32_t)tmp_int;
+#else
+					log__printf(NULL, MOSQ_LOG_WARNING, "Warning: Bridge support not available.");
 #endif
 				}else if(!strcmp(token, "bridge_tcp_keepalive")){
 #ifdef WITH_BRIDGE

src/mosquitto_broker_internal.h

@@ -581,6 +581,7 @@ struct mosquitto__bridge{
 	int backoff_cap;
 	int threshold;
 	uint32_t maximum_packet_size;
+	uint32_t session_expiry_interval;
 	bool lazy_reconnect;
 	bool attempt_unsubscribe;
 	bool initial_notification_done;