[Dovecot] Auth protocol and XMPP

Hello.

I've written an authentication backend for the XMPP server Prosody, which makes it use Dovecots auth socket and protocol, and letting the client use any SASL mechanism Dovecot offers.

However, setups using the full user@domain as authnid won't work, due to most XMPP clients assuming that the authnid is the localpart.

I want to avoid hardcoding it to PLAIN, or otherwise doing MITM/rewrites if possible. (There exists an older auth backend that does just that already)

Ideas?

-- Kim Alvefur <zash@zash.se>