    def make_homeserver(self, reactor, clock):

        self.hs = self.setup_test_homeserver(
            "red", http_client=None, federation_client=Mock(),
        )

        self.hs.get_federation_handler = Mock()
        self.hs.get_federation_handler.return_value.maybe_backfill = Mock(
            return_value=make_awaitable(None)
        )

        async def _insert_client_ip(*args, **kwargs):
            return None

        self.hs.get_datastore().insert_client_ip = _insert_client_ip

        return self.hs
A web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a Redirect. This simplifies phishing attacks.