fix(mqttsn): fix mqtt-sn client disconnected due to re-send a duplicated qos2 message

CHANGES-4.3.md

@@ -23,8 +23,8 @@ File format:
 
 ### Bug fixes
 * List subscription topic (/api/v4/subscriptions), the result do not match with multiple conditions.
-
 * SSL closed error bug fixed for redis client.
+* Fix mqtt-sn client disconnected due to re-send a duplicated qos2 message
 
 * Improved resilience against autocluster partitioning during cluster
   startup. [#7876]

apps/emqx_sn/src/emqx_sn.app.src

@@ -1,6 +1,6 @@
 {application, emqx_sn,
  [{description, "EMQ X MQTT-SN Plugin"},
-  {vsn, "4.3.6"}, % strict semver, bump manually!
+  {vsn, "4.3.7"}, % strict semver, bump manually!
   {modules, []},
   {registered, []},
   {applications, [kernel,stdlib,esockd]},

apps/emqx_sn/src/emqx_sn.appup.src

@@ -1,6 +1,9 @@
 %% -*- mode: erlang -*-
 {VSN,
   [
+   {"4.3.6",[
+       {load_module,emqx_sn_gateway,brutal_purge,soft_purge,[]}
+   ]},
    {"4.3.5",[
        {load_module,emqx_sn_frame,brutal_purge,soft_purge,[]},
        {load_module,emqx_sn_app,brutal_purge,soft_purge,[]},
@@ -26,6 +29,9 @@
    {<<"4\\.3\\.[0-1]">>, [{restart_application,emqx_sn}]}
   ],
   [
+   {"4.3.6",[
+       {load_module,emqx_sn_gateway,brutal_purge,soft_purge,[]}
+   ]},
    {"4.3.5",[
        {load_module,emqx_sn_frame,brutal_purge,soft_purge,[]},
        {load_module,emqx_sn_app,brutal_purge,soft_purge,[]},

apps/emqx_sn/src/emqx_sn_gateway.erl

@@ -831,13 +831,15 @@ mqtt2sn(?CONNACK_PACKET(0, _SessPresent),  _State) ->
 mqtt2sn(?CONNACK_PACKET(_ReturnCode, _SessPresent), _State) ->
     ?SN_CONNACK_MSG(?SN_RC_CONGESTION);
 
-mqtt2sn(?PUBREC_PACKET(MsgId), _State) ->
+mqtt2sn(?PUBACK_PACKET(MsgId, _ReasonCode), _State) ->
+    TopicIdFinal =  get_topic_id(puback, MsgId),
+    ?SN_PUBACK_MSG(TopicIdFinal, MsgId, ?SN_RC_ACCEPTED);
+
+mqtt2sn(?PUBREC_PACKET(MsgId, _ReturnCode), _State) ->
     ?SN_PUBREC_MSG(?SN_PUBREC, MsgId);
-
-mqtt2sn(?PUBREL_PACKET(MsgId), _State) ->
+mqtt2sn(?PUBREL_PACKET(MsgId, _ReturnCode), _State) ->
     ?SN_PUBREC_MSG(?SN_PUBREL, MsgId);
-
-mqtt2sn(?PUBCOMP_PACKET(MsgId), _State) ->
+mqtt2sn(?PUBCOMP_PACKET(MsgId, _ReturnCode), _State) ->
     ?SN_PUBREC_MSG(?SN_PUBCOMP, MsgId);
 
 mqtt2sn(?UNSUBACK_PACKET(MsgId), _State)->
@@ -884,11 +886,7 @@ mqtt2sn(?SUBACK_PACKET(MsgId, ReturnCodes), _State)->
                   {?QOS_0, get_topic_id(suback, MsgId), ?SN_RC_NOT_SUPPORTED}
           end,
     Flags = #mqtt_sn_flags{qos = QoS},
-    ?SN_SUBACK_MSG(Flags, TopicId, MsgId, NewReturnCode);
-
-mqtt2sn(?PUBACK_PACKET(MsgId, _ReasonCode), _State) ->
-    TopicIdFinal =  get_topic_id(puback, MsgId),
-    ?SN_PUBACK_MSG(TopicIdFinal, MsgId, ?SN_RC_ACCEPTED).
+    ?SN_SUBACK_MSG(Flags, TopicId, MsgId, NewReturnCode).
 
 send_register(TopicName, TopicId, MsgId, State) ->
     send_message(?SN_REGISTER_MSG(TopicId, MsgId, TopicName), State).

apps/emqx_sn/test/emqx_sn_protocol_SUITE.erl

@@ -36,7 +36,7 @@
 -define(FLAG_RETAIN(X),X).
 -define(FLAG_SESSION(X),X).
 
--define(LOG(Format, Args), ct:print("TEST: " ++ Format, Args)).
+-define(LOG(Format, Args), ct:log("TEST: " ++ Format, Args)).
 
 -define(MAX_PRED_TOPIC_ID, 2).
 -define(PREDEF_TOPIC_ID1, 1).
@@ -825,6 +825,42 @@ t_publish_qos2_case03(_) ->
     ?assertEqual(<<2, ?SN_DISCONNECT>>, receive_response(Socket)),
     gen_udp:close(Socket).
 
+t_publish_qos2_re_sent(_) ->
+    Dup = 0,
+    QoS = 2,
+    Retain = 0,
+    Will = 0,
+    CleanSession = 0,
+    MsgId = 7,
+    TopicId0 = 0,
+    {ok, Socket} = gen_udp:open(0, [binary]),
+    send_connect_msg(Socket, <<"test">>),
+    ?assertEqual(<<3, ?SN_CONNACK, 0>>, receive_response(Socket)),
+
+    send_subscribe_msg_normal_topic(Socket, QoS, <<"/#">>, MsgId),
+    ?assertEqual(<<8, ?SN_SUBACK, ?FNU:1, QoS:2, ?FNU:5, TopicId0:16, MsgId:16, ?SN_RC_ACCEPTED>>,
+        receive_response(Socket)),
+
+    Payload1 = <<20, 21, 22, 23>>,
+    send_publish_msg_short_topic(Socket, QoS, MsgId, <<"/a">>, Payload1),
+    ?assertEqual(<<4, ?SN_PUBREC, MsgId:16>>, receive_response(Socket)),
+    ?assertEqual(<<11, ?SN_PUBLISH, Dup:1, QoS:2, Retain:1, Will:1, CleanSession:1, ?SN_SHORT_TOPIC :2, <<"/a">>/binary, 1:16, <<20, 21, 22, 23>>/binary>>, receive_response(Socket)),
+
+    %% re-sent qos2 PUBLISH
+    send_publish_msg_short_topic(Socket, QoS, MsgId, <<"/a">>, Payload1),
+    %% still receive PUBREC normally
+    ?assertEqual(<<4, ?SN_PUBREC, MsgId:16>>, receive_response(Socket)),
+    send_pubrel_msg(Socket, MsgId),
+    ?assertEqual(<<4, ?SN_PUBCOMP, MsgId:16>>, receive_response(Socket)),
+
+    timer:sleep(100),
+
+    send_disconnect_msg(Socket, undefined),
+    %% note: receiving DISCONNECT packet here means that the qos2 is not duplicated
+    %% publish to broker
+    ?assertEqual(<<2, ?SN_DISCONNECT>>, receive_response(Socket)),
+    gen_udp:close(Socket).
+
 t_delivery_qos1_register_invalid_topic_id(_) ->
     Dup = 0,
     QoS = 1,