def host(self) -> str:
        """The host name the request was made to, including the port if
        it's non-standard. Validated with :attr:`trusted_hosts`.
        """
        return get_host(
            self.scheme, self.headers.get("host"), self.server, self.trusted_hosts
        )
The host name the request was made to, including the port if
        it's non-standard. Validated with :attr:`trusted_hosts`.
        
src/werkzeug/sansio/request.py