Add retain_available support.

man/mosquitto.conf.5.xml

@@ -628,6 +628,16 @@
 					<para>Reloaded on reload signal.</para>
 				</listitem>
 			</varlistentry>
+			<varlistentry>
+				<term><option>retain_available</option> [ true | false ]</term>
+				<listitem>
+					<para>If set to false, then retained messages are not
+						supported. Clients that send a message with the retain
+						bit will be disconnected if this option is set to
+						false. Defaults to true.</para>
+					<para>Reloaded on reload signal.</para>
+				</listitem>
+			</varlistentry>
 			<varlistentry>
 				<term><option>retained_persistence</option> [ true | false ]</term>
 				<listitem>

mosquitto.conf

@@ -149,6 +149,12 @@
 #per_listener_settings false
 
 
+# Set to false to disable retained message support. If a client publishes a
+# message with the retain bit set, it will be disconnected if this is set to
+# false.
+#retain_available true
+
+
 # =================================================================
 # Default listener
 # =================================================================

src/conf.c

@@ -219,6 +219,7 @@ static void config__init_reload(struct mosquitto_db *db, struct mosquitto__confi
 	config->persistence_file = NULL;
 	config->persistent_client_expiration = 0;
 	config->queue_qos0_messages = false;
+	config->retain_available = true;
 	config->set_tcp_nodelay = false;
 	config->sys_interval = 10;
 	config->upgrade_outgoing_qos = false;
@@ -1729,6 +1730,8 @@ int config__read_file_core(struct mosquitto__config *config, bool reload, struct
 #else
 					log__printf(NULL, MOSQ_LOG_WARNING, "Warning: Bridge support not available.");
 #endif
+				}else if(!strcmp(token, "retain_available")){
+					if(conf__parse_bool(&token, token, &config->retain_available, saveptr)) return MOSQ_ERR_INVAL;
 				}else if(!strcmp(token, "retry_interval")){
 					log__printf(NULL, MOSQ_LOG_WARNING, "Warning: The retry_interval option is no longer available.");
 				}else if(!strcmp(token, "round_robin")){

src/database.c

@@ -575,6 +575,10 @@ int db__messages_easy_queue(struct mosquitto_db *db, struct mosquitto *context,
 	topic_heap = mosquitto__strdup(topic);
 	if(!topic_heap) return MOSQ_ERR_INVAL;
 
+	if(db->config->retain_available == false){
+		retain = 0;
+	}
+
 	if(UHPA_ALLOC(payload_uhpa, payloadlen) == 0){
 		mosquitto__free(topic_heap);
 		return MOSQ_ERR_NOMEM;

src/handle_connect.c

@@ -236,6 +236,14 @@ int handle__connect(struct mosquitto_db *db, struct mosquitto *context)
 	password_flag = connect_flags & 0x40;
 	username_flag = connect_flags & 0x80;
 
+	if(will && will_retain && db->config->retain_available == false){
+		if(protocol_version == mosq_p_mqtt5){
+			send__connack(db, context, 0, MQTT_RC_RETAIN_NOT_SUPPORTED);
+		}
+		rc = 1;
+		goto handle_connect_error;
+	}
+
 	if(packet__read_uint16(&context->in_packet, &(context->keepalive))){
 		rc = 1;
 		goto handle_connect_error;

src/handle_publish.c

@@ -68,6 +68,13 @@ int handle__publish(struct mosquitto_db *db, struct mosquitto *context)
 	}
 	retain = (header & 0x01);
 
+	if(retain && db->config->retain_available == false){
+		if(context->protocol == mosq_p_mqtt5){
+			send__disconnect(context, MQTT_RC_RETAIN_NOT_SUPPORTED, NULL);
+		}
+		return 1;
+	}
+
 	if(packet__read_string(&context->in_packet, &topic, &slen)) return 1;
 	if(!slen){
 		/* Invalid publish topic, disconnect client. */

src/mosquitto_broker_internal.h

@@ -268,6 +268,7 @@ struct mosquitto__config {
 	char *pid_file;
 	bool queue_qos0_messages;
 	bool per_listener_settings;
+	bool retain_available;
 	bool set_tcp_nodelay;
 	int sys_interval;
 	bool upgrade_outgoing_qos;

src/send_connack.c

@@ -44,6 +44,13 @@ int send__connack(struct mosquitto_db *db, struct mosquitto *context, int ack, i
 	packet->command = CMD_CONNACK;
 	packet->remaining_length = 2;
 	if(context->protocol == mosq_p_mqtt5){
+		if(reason_code < 128 && db->config->retain_available == false){
+			rc = mosquitto_property_add_byte(&properties, MQTT_PROP_RETAIN_AVAILABLE, 0);
+			if(rc){
+				mosquitto__free(packet);
+				return rc;
+			}
+		}
 		proplen = property__get_length_all(properties);
 		varbytes = packet__varint_bytes(proplen);
 		packet->remaining_length += proplen + varbytes;