Maybe this is a bug?

[wwhai]

Today I ready to add a UDP listener in emqx,When I add it to esockd , it work normal but detected an error in "managerment listener". My code in here:
This code used to support raw udp:

start_urap_listener()->
    Opts = [{udp_options, [binary, {reuseaddr, true}]}],
    MFA = {emqx_urap_connection, start_link, []},
    esockd:open_udp('urap:udp', 1885, Opts, MFA).

This callback:

%%%-------------------------------------------------------------------
%%% @author admin
%%% @copyright (C) 2020, <COMPANY>
%%% @doc
%%%
%%% @end
%%% Created : 8. 4月 2020 11:20
%%%-------------------------------------------------------------------
-module(emqx_urap_connection).
-author("wwhai").

-behaviour(gen_server).

%% API
-export([start_link/2, init/2]).

%% gen_server callbacks
-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2,
  code_change/3]).

-define(SERVER, ?MODULE).
-define(UDP_OPTS, [binary, {reuseaddr, true}]).

-record(emqx_urap_state, {}).

%%%===================================================================
%%% API
% %%%===================================================================
% start(Port) ->
%   Opts = [{udp_options, [binary, {reuseaddr, true}]}],
%   MFA = {?MODULE, start_link, []},
%   esockd:open_udp('urap:udp', Port, Opts, MFA).


start_link(Transport, Peer) ->
  {ok, proc_lib:spawn_link(?MODULE, init, [Transport, Peer])}.

init(_T, _P) ->
  gen_server:enter_loop(?MODULE, [], #emqx_urap_state{}).

init(_) -> ok.

%%
%% 消息接收处理
%%

handle_call(_Request, _From, State) ->
  {reply, ok, State}.

handle_info(Msg, State) ->
  io:format("MSG:~p~n", [Msg]),
  {noreply, State}.

terminate(_Reason, _State) ->
  ok.

code_change(_OldVsn, State, _Extra) ->
  {ok, State}.


handle_cast(_Msg, State) ->
  {noreply, State}.

It can work:

• Client send:
  
• Server received:
  

But front appear this:

And error log:

2020-04-08 21:14:46.394 [error] [esockd_udp]: Unexpected call: which_children
2020-04-08 21:14:46.394 [error] GET /api/v4/nodes/emqx@127.0.0.1/listeners error: function_clause, stacktrace:
[{esockd_listener_sup,'-child_pid/2-lc$^0/1-0-',
                      [ignore],
                      [{file,"/mnt/d/github/emqx-rel/_checkouts/esockd/src/esockd_listener_sup.erl"},
                       {line,87}]},
 {esockd_listener_sup,child_pid,2,
                      [{file,"/mnt/d/github/emqx-rel/_checkouts/esockd/src/esockd_listener_sup.erl"},
                       {line,87}]},
 {esockd,get_acceptors,1,
         [{file,"/mnt/d/github/emqx-rel/_checkouts/esockd/src/esockd.erl"},
          {line,194}]},
 {emqx_mgmt,'-list_listeners/1-fun-0-',1,
            [{file,"/mnt/d/github/emqx-rel/_checkouts/emqx_management/src/emqx_mgmt.erl"},
             {line,391}]},
 {lists,map,2,[{file,"lists.erl"},{line,1239}]},
 {lists,map,2,[{file,"lists.erl"},{line,1239}]},
 {emqx_mgmt,list_listeners,1,
            [{file,"/mnt/d/github/emqx-rel/_checkouts/emqx_management/src/emqx_mgmt.erl"},
             {line,388}]},
 {emqx_mgmt_api_listeners,list,2,
                          [{file,"/mnt/d/github/emqx-rel/_checkouts/emqx_management/src/emqx_mgmt_api_listeners.erl"},
                           {line,37}]}]

I checked code fond in here:

It looks like current version only filter tcpkeywords but no udp?