Avoid an exception when an AMQP 0-9-1-originating message with expiration set is converted for an MQTT consumer (backport #12710)

deps/rabbitmq_mqtt/src/mc_mqtt.erl

@@ -426,7 +426,7 @@ protocol_state(Msg = #mqtt_msg{props = Props0,
                 undefined ->
                     Props2;
                 Ttl ->
-                    case maps:get(?ANN_TIMESTAMP, Anns) of
+                    case maps:get(?ANN_TIMESTAMP, Anns, undefined) of
                         undefined ->
                             Props2;
                         Timestamp ->

deps/rabbitmq_mqtt/test/mc_mqtt_SUITE.erl

@@ -33,7 +33,8 @@ groups() ->
        mqtt_amqp,
        mqtt_amqp_alt,
        amqp_mqtt,
-       is_persistent
+       is_persistent,
+       amqpl_to_mqtt_gh_12707
       ]}
     ].
 
@@ -156,6 +157,18 @@ roundtrip_amqpl(_Config) ->
     ExpectedUserProperty = lists:keysort(1, UserProperty),
     ?assertMatch(#{'User-Property' := ExpectedUserProperty}, Props).
 
+amqpl_to_mqtt_gh_12707(_Config) ->
+    Props = #'P_basic'{expiration = <<"12707">>},
+    Payload = [<<"gh_12707">>],
+    Content = #content{properties = Props,
+                       payload_fragments_rev = Payload},
+    Anns = #{?ANN_EXCHANGE => <<"amq.topic">>,
+             ?ANN_ROUTING_KEYS => [<<"dummy">>]},
+    OriginalMsg = mc:init(mc_amqpl, Content, Anns),
+    Converted = mc:convert(mc_mqtt, OriginalMsg),
+    ?assertMatch(#mqtt_msg{}, mc:protocol_state(Converted)),
+    ?assertEqual(12707, mc:get_annotation(ttl, Converted)).
+
 %% Non-UTF-8 Correlation Data should also be converted (via AMQP 0.9.1 header x-correlation-id).
 roundtrip_amqpl_correlation(_Config) ->
     Msg0 = mqtt_msg(),

deps/rabbitmq_mqtt/test/protocol_interop_SUITE.erl

@@ -35,6 +35,7 @@ groups() ->
     [{cluster_size_1, [shuffle],
       [
        mqtt_amqpl_mqtt,
+       amqpl_mqtt_gh_12707,
        mqtt_amqp_mqtt,
        amqp_mqtt_amqp,
        mqtt_stomp_mqtt,
@@ -104,7 +105,6 @@ mqtt_amqpl_mqtt(Config) ->
     #'queue.bind_ok'{} = amqp_channel:call(Ch, #'queue.bind'{queue = Q,
                                                              exchange = <<"amq.topic">>,
                                                              routing_key = <<"my.topic">>}),
-    %% MQTT 5.0 to AMQP 0.9.1
     C = connect(ClientId, Config),
     MqttResponseTopic = <<"response/topic">>,
     {ok, _, [1]} = emqtt:subscribe(C, #{'Subscription-Identifier' => 999}, [{MqttResponseTopic, [{qos, 1}]}]),
@@ -169,6 +169,32 @@ mqtt_amqpl_mqtt(Config) ->
 
     ok = emqtt:disconnect(C).
 
+amqpl_mqtt_gh_12707(Config) ->
+    ClientId = atom_to_binary(?FUNCTION_NAME),
+    Topic = Payload = <<"gh_12707">>,
+    C = connect(ClientId, Config),
+    {ok, _, [1]} = emqtt:subscribe(C, Topic, qos1),
+
+    Ch = rabbit_ct_client_helpers:open_channel(Config),
+    amqp_channel:call(Ch,
+                      #'basic.publish'{exchange = <<"amq.topic">>,
+                                       routing_key = Topic},
+                      #amqp_msg{payload = Payload,
+                                props = #'P_basic'{expiration = <<"12707">>,
+                                                   headers = []}}),
+
+    receive {publish,
+             #{topic := MqttTopic,
+               payload := MqttPayload}} ->
+                ?assertEqual(Topic, MqttTopic),
+                ?assertEqual(Payload, MqttPayload)
+    after 5000 ->
+              ct:fail("did not receive a delivery")
+    end,
+
+    ok = rabbit_ct_client_helpers:close_channel(Ch),
+    ok = emqtt:disconnect(C).
+
 mqtt_amqp_mqtt(Config) ->
     Host = ?config(rmq_hostname, Config),
     Port = rabbit_ct_broker_helpers:get_node_config(Config, 0, tcp_port_amqp),