Add a callback for a specific port/header callback with the
        possibility to add a mask for channel and port for multiple
        hits for same callback.

def add_header_callback(self, cb, port, channel, port_mask=0xFF,
                            channel_mask=0xFF):
        """
        Add a callback for a specific port/header callback with the
        possibility to add a mask for channel and port for multiple
        hits for same callback.
        """
        self.cb.append(_CallbackContainer(port, port_mask,
                                          channel, channel_mask, cb))