Fix v5 DISCONNECT packets with remaining length == 2.

These were being treated as a protocol error.

Closes #1367. Thanks to Frank Pagliughi.

ChangeLog.txt

@@ -1,3 +1,7 @@
+Broker:
+- Fix v5 DISCONNECT packets with remaining length == 2 being treated as a
+  protocol error. Closes #1367.
+
 Build:
 - Fix missing function warnings on NetBSD.
 

src/handle_disconnect.c

@@ -34,12 +34,12 @@ int handle__disconnect(struct mosquitto_db *db, struct mosquitto *context)
 		return MOSQ_ERR_INVAL;
 	}
 
-	if(context->protocol == mosq_p_mqtt5 && context->in_packet.remaining_length > 1){
+	if(context->protocol == mosq_p_mqtt5 && context->in_packet.remaining_length > 0){
 		/* FIXME - must handle reason code */
 		rc = packet__read_byte(&context->in_packet, &reason_code);
 		if(rc) return rc;
 
-		if(context->in_packet.remaining_length > 2){
+		if(context->in_packet.remaining_length > 1){
 			rc = property__read_all(CMD_DISCONNECT, &context->in_packet, &properties);
 			if(rc) return rc;
 		}
@@ -54,7 +54,7 @@ int handle__disconnect(struct mosquitto_db *db, struct mosquitto *context)
 	}
 	mosquitto_property_free_all(&properties); /* FIXME - TEMPORARY UNTIL PROPERTIES PROCESSED */
 
-	if(context->in_packet.remaining_length != 0){
+	if(context->in_packet.pos != context->in_packet.remaining_length){
 		return MOSQ_ERR_PROTOCOL;
 	}
 	log__printf(NULL, MOSQ_LOG_DEBUG, "Received DISCONNECT from %s", context->id);

test/broker/01-connect-disconnect-v5.py

@@ -7,16 +7,32 @@ from mosq_test_helper import *
 def disco_test(test, disconnect_packet):
     global rc
 
-    sock = mosq_test.do_client_connect(connect_packet, connack_packet, port=port)
-    sock.send(disconnect_packet)
-    sock.close()
+    sock1 = mosq_test.do_client_connect(connect1_packet, connack1_packet, port=port)
+    mosq_test.do_send_receive(sock1, subscribe1_packet, suback1_packet, "suback1")
+
+
+    sock2 = mosq_test.do_client_connect(connect2_packet, connack2_packet, port=port)
+    sock2.send(disconnect_packet)
+    sock2.close()
+
+    # If this fails then we probably received the will
+    mosq_test.do_ping(sock1)
+
     rc -= 1
 
 
 rc = 4
 keepalive = 10
-connect_packet = mosq_test.gen_connect("connect-disconnect-test", proto_ver=5, keepalive=keepalive)
-connack_packet = mosq_test.gen_connack(rc=0, proto_ver=5)
+
+connect1_packet = mosq_test.gen_connect("sub", proto_ver=5, keepalive=keepalive)
+connack1_packet = mosq_test.gen_connack(rc=0, proto_ver=5)
+
+mid = 1
+subscribe1_packet = mosq_test.gen_subscribe(mid, "#", 0, proto_ver=5)
+suback1_packet = mosq_test.gen_suback(mid, 0, proto_ver=5)
+
+connect2_packet = mosq_test.gen_connect("connect-disconnect-test", proto_ver=5, keepalive=keepalive, will_topic="failure", will_payload=b"failure")
+connack2_packet = mosq_test.gen_connack(rc=0, proto_ver=5)
 
 port = mosq_test.get_port()
 broker = mosq_test.start_broker(filename=os.path.basename(__file__), port=port)