feat(frame): better log for proxy_protocol config disabled

src/emqx_connection.erl

@@ -629,10 +629,15 @@ parse_incoming(Data, Packets, State = #state{parse_state = ParseState}) ->
             NState = State#state{parse_state = NParseState},
             parse_incoming(Rest, [Packet|Packets], NState)
     catch
+        error:proxy_protocol_config_disabled:_Stk ->
+            ?LOG(error,
+                 "~nMalformed packet, "
+                 "please check proxy_protocol config for specific listeners and zones~n"),
+            {[{frame_error, proxy_protocol_config_disabled} | Packets], State};
         error:Reason:Stk ->
             ?LOG(error, "~nParse failed for ~0p~n~0p~nFrame data:~0p",
                  [Reason, Stk, Data]),
-            {[{frame_error, Reason}|Packets], State}
+            {[{frame_error, Reason} | Packets], State}
     end.
 
 -compile({inline, [next_incoming_msgs/1]}).

src/emqx_frame.erl

@@ -71,6 +71,13 @@
 
 -define(MULTIPLIER_MAX, 16#200000).
 
+%% proxy_protocol v1 header human readable
+-define(PPV1_PROXY, "PROXY ").
+-define(PPV1_PROXY_UNKNOWN, "PROXY UNKNOWN").
+%% proxy_protocol v2 header signature:
+%% 16#0D,16#0A, 16#0D,16#0A,16#00,16#0D,16#0A,16#51,16#55,16#49,16#54,16#0A
+-define(PPV2_HEADER_SIG, "\r\n\r\n\0\r\nQUIT\n").
+
 -dialyzer({no_match, [serialize_utf8_string/2]}).
 
 %%--------------------------------------------------------------------
@@ -100,6 +107,13 @@ parse(Bin) ->
 -spec(parse(binary(), parse_state()) -> parse_result()).
 parse(<<>>, {none, Options}) ->
     {more, {none, Options}};
+parse(<<?PPV1_PROXY, IPVer:5/binary, _Rest/binary>>, {none, _Options})
+  when IPVer =:= <<"TCP4 ">> orelse IPVer =:= <<"TCP6 ">> ->
+    error(proxy_protocol_config_disabled);
+parse(<<?PPV1_PROXY_UNKNOWN, _Rest/binary>>, {none, _Options}) ->
+    error(proxy_protocol_config_disabled);
+parse(<<?PPV2_HEADER_SIG, _Rest/binary>>, {none, _Options}) ->
+    error(proxy_protocol_config_disabled);
 parse(<<Type:4, Dup:1, QoS:2, Retain:1, Rest/binary>>,
       {none, Options = #{strict_mode := StrictMode}}) ->
     %% Validate header if strict mode.