debug!(
                            "{:?}, line {:?} req_type = {:?}",
                            file!(),
                            line!(),
                            std::str::from_utf8(x)
                        );
                        if let Some(ref mut enc) = self.common.encrypted {
                            push_packet!(enc.write, {
                                enc.write.push(msg::CHANNEL_FAILURE);
                            });
                        }

                        warn!("unknown channel request {}", String::from_utf8_lossy(x));
                        self.channel_failure(channel_num);