def wait_for_response(self, event):
        max_ts = None
        if self.transport.auth_timeout is not None:
            max_ts = time.time() + self.transport.auth_timeout
        while True:
            event.wait(0.1)
            if not self.transport.is_active():
                e = self.transport.get_exception()
                if (e is None) or issubclass(e.__class__, EOFError):
                    e = AuthenticationException('Authentication failed.')
                raise e
            if event.is_set():
                break
            if max_ts is not None and max_ts <= time.time():
                raise AuthenticationException('Authentication timeout.')

        if not self.is_authenticated():
            e = self.transport.get_exception()
            if e is None:
                e = AuthenticationException('Authentication failed.')
            # this is horrible.  Python Exception isn't yet descended from
            # object, so type(e) won't work. :(
            if issubclass(e.__class__, PartialAuthentication):
                return e.allowed_types
            raise e
        return []