fix: improve the error logs in proxy-protocol mode

src/esockd_proxy_protocol.erl

@@ -25,6 +25,9 @@
 -export([parse_v1/2, parse_v2/4, parse_pp2_tlv/2, parse_pp2_ssl/1]).
 -endif.
 
+-define(LOG(LEVEL, Format, Args), logger:log(LEVEL, "[~s] " ++ Format, [?MODULE | Args])).
+-define(ERR_MSG_IN_PP_MODE, "The listener is working in proxy protocol mode").
+
 %% Protocol Command
 -define(LOCAL, 16#0).
 -define(PROXY, 16#1).
@@ -83,20 +86,26 @@ recv(Transport, Sock, Timeout) ->
                     Transport:setopts(Sock, OriginOpts),
                     parse_v2(Cmd, Trans, ProxyInfo, #proxy_socket{inet = inet_family(AF), socket = Sock});
                 {error, Reason} ->
-                    {error, {recv_proxy_info_error, Reason}}
+                    ?LOG(error, ?ERR_MSG_IN_PP_MODE", but some errors occurred "
+                        "while waiting for proxy info: ~p", [Reason]),
+                    {error, recv_proxy_info_error}
             end;
         {tcp_error, _Sock, Reason} ->
-            {error, {recv_proxy_info_error, Reason}};
+            ?LOG(error, ?ERR_MSG_IN_PP_MODE", but got a TCP error "
+                "while waiting for proxy info: ~p", [Reason]),
+            {error, recv_proxy_info_error};
         {tcp_closed, _Sock} ->
             %% Socket closed before any data is received.
             %% Here we return an atom here to avoid error level logging.
             %% See the from the connection_crashed function in esockd_connection_sup.erl.
             {error, proxy_proto_close};
         {_, _Sock, ProxyInfo} ->
-            {error, {invalid_proxy_info, ProxyInfo}}
+            ?LOG(error, ?ERR_MSG_IN_PP_MODE", but got invalid proxy info: ~p", [ProxyInfo]),
+            {error, invalid_proxy_info}
     after
         Timeout ->
-            {error, {proxy_proto_timeout, Timeout}}
+            ?LOG(error, ?ERR_MSG_IN_PP_MODE", but timed out while waiting for proxy info", []),
+            {error, proxy_proto_timeout}
     end.
 
 parse_v1(ProxyInfo, ProxySock) ->