Add optional callback ranch_transport:format_error/1

src/ranch_acceptors_sup.erl

@@ -90,7 +90,7 @@ listen_error(Ref, Transport, TransOpts0, Reason, Logger) ->
 	TransOpts = TransOpts0#{socket_opts => SocketOpts},
 	ranch:log(error,
 		"Failed to start Ranch listener ~p in ~p:listen(~999999p) for reason ~p (~s)~n",
-		[Ref, Transport, TransOpts, Reason, format_error(Reason)], Logger),
+		[Ref, Transport, TransOpts, Reason, format_error(Transport, Reason)], Logger),
 	exit({listen_error, Ref, Reason}).
 
 hide_socket_opts([]) ->
@@ -106,9 +106,14 @@ hide_socket_opts([{password, _}|SocketOpts]) ->
 hide_socket_opts([SocketOpt|SocketOpts]) ->
 	[SocketOpt|hide_socket_opts(SocketOpts)].
 
-format_error(no_cert) ->
+format_error(_, no_cert) ->
 	"no certificate provided; see cert, certfile, sni_fun or sni_hosts options";
-format_error(reuseport_local) ->
+format_error(_, reuseport_local) ->
 	"num_listen_sockets must be set to 1 for local sockets";
-format_error(Reason) ->
-	inet:format_error(Reason).
+format_error(Transport, Reason) ->
+	case erlang:function_exported(Transport, format_error, 1) of
+		true ->
+			Transport:format_error(Reason);
+		false ->
+			io_lib:format("~999999p", [Reason])
+	end.

src/ranch_ssl.erl

@@ -46,6 +46,7 @@
 -export([shutdown/2]).
 -export([close/1]).
 -export([cleanup/1]).
+-export([format_error/1]).
 
 -type ssl_opt() :: {alpn_preferred_protocols, [binary()]}
 	| {anti_replay, '10k' | '100k' | {integer(), integer(), integer()}}
@@ -328,6 +329,12 @@ cleanup(#{socket_opts:=SocketOpts}) ->
 cleanup(_) ->
 	ok.
 
+-spec format_error({error, ssl:reason()} | ssl:reason()) -> string().
+format_error(no_cert) ->
+        "no certificate provided; see cert, certfile, sni_fun or sni_hosts options";
+format_error(Reason) ->
+	ssl:format_error(Reason).
+
 get_tls_versions(SocketOpts) ->
 	%% Socket options need to be reversed for keyfind because later options
 	%% take precedence when contained multiple times, but keyfind will return

src/ranch_tcp.erl

@@ -45,6 +45,7 @@
 -export([shutdown/2]).
 -export([close/1]).
 -export([cleanup/1]).
+-export([format_error/1]).
 
 -type opt() :: {backlog, non_neg_integer()}
 	| {buffer, non_neg_integer()}
@@ -285,3 +286,7 @@ cleanup(#{socket_opts:=SocketOpts}) ->
 	end;
 cleanup(_) ->
 	ok.
+
+-spec format_error(inet:posix() | system_limit) -> string().
+format_error(Reason) ->
+	inet:format_error(Reason).

src/ranch_transport.erl

@@ -68,6 +68,9 @@
 	-> ok | {error, atom()}.
 -callback close(socket()) -> ok.
 -callback cleanup(ranch:transport_opts(any())) -> ok.
+-callback format_error(term()) -> string().
+
+-optional_callbacks([format_error/1]).
 
 %% A fallback for transports that don't have a native sendfile implementation.
 %% Note that the ordering of arguments is different from file:sendfile/5 and