int silc_parse_userfqdn(const char *string,
                            char *user, SilcUInt32 user_size,
                            char *fqdn, SilcUInt32 fqdn_size);

    Parse userfqdn string which is in user@fqdn format.  Returns 0 on
    error, 1 if `user' was filled and 2 if both `user' and `fqdn'
    was filled.