def get_extra_info(self, name, default=None):
        """
        Return optional transport information.

        - `'related_address'`: the related address
        - `'sockname'`: the relayed address
        """
        if name == 'related_address':
            return self.__inner_protocol.transport.get_extra_info('sockname')
        elif name == 'sockname':
            return self.__relayed_address
        return default