Character sets with mod_irc

That option is documented in the Guide, but I didn't see it implemented in the code. It can be implemented with this patch, can you try it and report if now it works?

--- a/src/mod_irc/mod_irc.erl
+++ b/src/mod_irc/mod_irc.erl
@@ -330,7 +330,7 @@ do_route1(Host, ServerHost, From, To, Packet) ->
                        [] ->
                            ?DEBUG("open new connection~n", []),
                            {Username, Encoding, Port, Password} = get_connection_params(
-                                                    Host, From, Server),
+                                                    Host, ServerHost, From, Server),
                            ConnectionUsername =
                                case Packet of
                                    %% If the user tries to join a
@@ -662,7 +662,14 @@ set_form(_Host, _, _, _Lang, _XData) ->
     {error, ?ERR_SERVICE_UNAVAILABLE}.


+%% Host = "irc.example.com"
+%% ServerHost = "example.com"
 get_connection_params(Host, From, IRCServer) ->
+    [_ | HostTail] = string:tokens(Host, "."),
+    ServerHost = string:join(HostTail, "."),
+    get_connection_params(Host, ServerHost, From, IRCServer).
+
+get_connection_params(Host, ServerHost, From, IRCServer) ->
     #jid{user = User, server = _Server,
         luser = LUser, lserver = LServer} = From,
     US = {LUser, LServer},
@@ -682,7 +689,10 @@ get_connection_params(Host, From, IRCServer) ->
                    {value, {_, Encoding}} ->
                        {Username, Encoding, ?DEFAULT_IRC_PORT, ""};
                    _ ->
-                       {Username, ?DEFAULT_IRC_ENCODING, ?DEFAULT_IRC_PORT, ""}
+                       Encoding = gen_mod:get_module_opt(
+                                    ServerHost, ?MODULE, default_encoding,
+                                    ?DEFAULT_IRC_ENCODING),
+                       {Username, Encoding, ?DEFAULT_IRC_PORT, ""}
                end,
            {NewUsername,
             NewEncoding,

Each user can also define what encoding he wants when connecting to specific IRC servers. This is possible by "registering" with the IRC transport.

I reorder the letters a little bit to see it better:

A) IRC client with iso8859 encoding
B) XMPP client with utf-8 encoding
C) XMPP server with utf-8 encoding
D) IRC-XMPP transport
E) IRC server with iso8859 encoding

So D speaks (IRC server->client) iso8859 OR utf-8 with E and D speaks utf-8 with C.
This leaves two solutions:
1. If D checks the characters set (to convert?) it has to know that it is iso8859.
2. If XMPP had the support, characters might be passed as-is from D to A.

Now if the user uses utf-8 IRC client (A) as the current practice is, the character set has to be converted from X to utf-8 or do no conversion when it's already utf-8. The client must check at least that the input is utf-8 or not utf-8.

When it's not utf-8 the client uses some guessing. It might not use guessing if the user has defined that this-and-this channel (or "room") uses iso8859 or this-and-this user uses this-and-this character set.

The utf-8-only limitation (?) in XMPP causes that only option 1 can be used with guessing. The guessing would be a good feature if it works. I think the guessing would also need some extra parameters such as language to work better. That, again, needs some channel specific information (user might talk two different languages on different channels).

I can live with the utf-8-only support for D. The utf-8 is anyway recommended for IRC. I still think we can't change the users to use utf-8-only OR the xmpp clients with IRC extensions to support other than utf-8 because there is no need to do it.

Do you think the character set conversion (or guessing) should/can be done in D? If not, do you know whether we will get your mod_irc utf-8 patch to some official ejabberd release?