Fix Unsubscribe with No Topic

Signed-off-by: Tatsuzo Osawa <tatsuzo.osawa@gmail.com>

src/handle_unsubscribe.c

@@ -46,6 +46,12 @@ int handle__unsubscribe(struct mosquitto_db *db, struct mosquitto *context)
 	}
 	if(packet__read_uint16(&context->in_packet, &mid)) return 1;
 
+	if(context->protocol == mosq_p_mqtt311){
+		if(context->in_packet.pos == context->in_packet.remaining_length){
+			/* No topic specified, protocol error. */
+			return MOSQ_ERR_PROTOCOL;
+		}
+	}
 	while(context->in_packet.pos < context->in_packet.remaining_length){
 		sub = NULL;
 		if(packet__read_string(&context->in_packet, &sub)){

test/broker/02-unsubscribe-invalid-no-topic.py

@@ -0,0 +1,46 @@
+#!/usr/bin/env python
+
+# Test whether a UNSUBSCRIBE with no topic results in a disconnect. MQTT-3.10.3-2
+
+import inspect, os, sys
+import struct
+
+def gen_unsubscribe_invalid_no_topic(mid):
+    pack_format = "!BBH"
+    return struct.pack(pack_format, 162, 2, mid)
+
+# From http://stackoverflow.com/questions/279237/python-import-a-module-from-a-folder
+cmd_subfolder = os.path.realpath(os.path.abspath(os.path.join(os.path.split(inspect.getfile( inspect.currentframe() ))[0],"..")))
+if cmd_subfolder not in sys.path:
+    sys.path.insert(0, cmd_subfolder)
+
+import mosq_test
+
+rc = 1
+mid = 3
+keepalive = 60
+connect_packet = mosq_test.gen_connect("unsubscribe-invalid-no-topic-test", keepalive=keepalive, proto_ver=4)
+connack_packet = mosq_test.gen_connack(rc=0)
+
+unsubscribe_packet = gen_unsubscribe_invalid_no_topic(mid)
+
+cmd = ['../../src/mosquitto', '-p', '1888']
+broker = mosq_test.start_broker(filename=os.path.basename(__file__), cmd=cmd)
+
+try:
+    sock = mosq_test.do_client_connect(connect_packet, connack_packet)
+    sock.send(unsubscribe_packet)
+
+    if mosq_test.expect_packet(sock, "disconnect", ""):
+        rc = 0
+
+    sock.close()
+finally:
+    broker.terminate()
+    broker.wait()
+    if rc:
+        (stdo, stde) = broker.communicate()
+        print(stde)
+
+exit(rc)
+

test/broker/Makefile

@@ -41,6 +41,7 @@ endif
 	./02-unsubscribe-qos0.py
 	./02-unsubscribe-qos1.py
 	./02-unsubscribe-qos2.py
+	./02-unsubscribe-invalid-no-topic.py
 
 03 :
 	./03-publish-qos1.py