Display MQTT 5 CONNECT User Property in Management UI

and CLI as requested in
#2554 (comment)

"User Properties on the CONNECT packet can be used to send connection related properties from the Client to the Server.
The meaning of these properties is not defined by this specification."
[v5 3.1.2.11.8]

It makes sense to display the User Property of the CONNECT packet in the
Management UI in the connection's Client Properties.

Author: ansd

deps/rabbitmq_mqtt/include/rabbit_mqtt.hrl

@@ -37,6 +37,7 @@
         [
          client_id,
          conn_name,
+         user_property,
          connection_state,
          ssl_login_name,
          recv_cnt,

deps/rabbitmq_mqtt/include/rabbit_mqtt_packet.hrl

@@ -14,6 +14,7 @@
 -type property_name() :: atom().
 -type property_value() :: any().
 -type properties() :: #{property_name() := property_value()}.
+-type user_property() :: [{binary(), binary()}].
 
 -define(TWO_BYTE_INTEGER_MAX, 16#FFFF).
 %% Packet identifier is a non zero two byte integer.

deps/rabbitmq_mqtt/src/rabbit_mqtt_processor.erl

@@ -68,6 +68,8 @@
          prefetch :: non_neg_integer(),
          vhost :: rabbit_types:vhost(),
          client_id :: client_id(),
+         %% User Property set in the CONNECT packet.
+         user_prop :: user_property(),
          conn_name :: option(binary()),
          ip_addr :: inet:ip_address(),
          port :: inet:port_number(),
@@ -215,6 +217,7 @@ process_connect(
                           retainer_pid = rabbit_mqtt_retainer_sup:start_child_for_vhost(VHost),
                           vhost = VHost,
                           client_id = ClientId,
+                          user_prop = maps:get('User-Property', ConnectProps, []),
                           will_msg = WillMsg,
                           max_packet_size_outbound = MaxPacketSize,
                           topic_alias_maximum_outbound = TopicAliasMaxOutbound},
@@ -2540,10 +2543,18 @@ info(messages_unacknowledged, #state{unacked_server_pubs = Val}) ->
     maps:size(Val);
 info(node, _) -> node();
 info(client_id, #state{cfg = #cfg{client_id = Val}}) -> Val;
+info(user_property, #state{cfg = #cfg{user_prop = Val}}) -> Val;
 info(vhost, #state{cfg = #cfg{vhost = Val}}) -> Val;
 %% for rabbitmq_management/priv/www/js/tmpl/connection.ejs
-info(client_properties, #state{cfg = #cfg{client_id = Val}}) ->
-    [{client_id, longstr, Val}];
+info(client_properties, #state{cfg = #cfg{client_id = ClientId,
+                                          user_prop = Prop}}) ->
+    L = [{client_id, longstr, ClientId}],
+    if Prop =:= [] ->
+           L;
+       Prop =/= [] ->
+           Tab = rabbit_misc:to_amqp_table(maps:from_list(Prop)),
+           [{user_property, table, Tab} | L]
+    end;
 info(channel_max, _) -> 0;
 %% Maximum packet size supported only in MQTT 5.0.
 info(frame_max, _) -> 0;

deps/rabbitmq_mqtt/test/command_SUITE.erl

@@ -26,7 +26,8 @@ groups() ->
     [
      {unit, [], [merge_defaults]},
      {v4, [], [run]},
-     {v5, [], [run]}
+     {v5, [], [run,
+               user_property]}
     ].
 
 suite() ->
@@ -141,6 +142,22 @@ run(Config) ->
     ok = emqtt:disconnect(C2),
     ok = emqtt:disconnect(C3).
 
+user_property(Config) ->
+    Node = rabbit_ct_broker_helpers:get_node_config(Config, 0, nodename),
+    Opts = #{node => Node, timeout => 10_000, verbose => false},
+    ClientId = <<"my-client">>,
+    UserProp = [{<<"name 1">>, <<"value 1">>},
+                {<<"name 2">>, <<"value 2">>},
+                %% "The same name is allowed to appear more than once." [v5 3.1.2.11.8]
+                {<<"name 2">>, <<"value 3">>}],
+    C = connect(ClientId, Config, 1, [{properties, #{'User-Property' => UserProp}}]),
+    rabbit_ct_helpers:eventually(
+      ?_assertEqual(
+         [[{client_id, ClientId},
+           {user_property, UserProp}]],
+         'Elixir.Enum':to_list(?COMMAND:run([<<"client_id">>, <<"user_property">>], Opts)))),
+    ok = emqtt:disconnect(C).
+
 start_amqp_connection(Type, Node, Port) ->
     amqp_connection:start(amqp_params(Type, Node, Port)).