// tattlekey: A one-key UDP keyboard // Copyright (C) 2023 Scott Worley // // This program is free software: you can redistribute it and/or modify // it under the terms of the GNU General Public License as published by // the Free Software Foundation, either version 3 of the License, or // (at your option) any later version. // // This program is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // // You should have received a copy of the GNU General Public License // along with this program. If not, see . use std::net::UdpSocket; use std::time::{Duration, SystemTime}; const MESSAGE_SIZE: usize = 12; #[derive(Debug)] struct MessageKey { epoch: u32, device: u16, seq: u16, } #[derive(Debug)] struct Message { key: MessageKey, ago: u32, t: SystemTime, } impl From<&[u8; MESSAGE_SIZE]> for Message { fn from(value: &[u8; MESSAGE_SIZE]) -> Self { let ago = u32::from_be_bytes(value[8..=11].try_into().expect("I can't count")); Self { key: MessageKey { epoch: u32::from_be_bytes(value[0..=3].try_into().expect("I can't count")), device: u16::from_be_bytes(value[4..=5].try_into().expect("I can't count")), seq: u16::from_be_bytes(value[6..=7].try_into().expect("I can't count")), }, ago, t: SystemTime::now() - Duration::new(ago.into(), 0), } } } impl TryFrom<&[u8]> for Message { type Error = std::array::TryFromSliceError; fn try_from(value: &[u8]) -> Result { match <[u8; MESSAGE_SIZE]>::try_from(value) { Ok(correct_size) => Ok(Message::from(&correct_size)), Err(e) => Err(e), } } } fn main() { let socket = UdpSocket::bind("0.0.0.0:29803").expect("couldn't bind to address"); loop { let mut buf = [0; MESSAGE_SIZE]; match socket.recv_from(&mut buf) { Err(e) => eprintln!("Didn't receive data: {e}"), Ok((number_of_bytes, src_addr)) => { let filled_buf = &buf[..number_of_bytes]; if number_of_bytes != MESSAGE_SIZE { eprintln!("Ignoring short message ({number_of_bytes}) from {src_addr}"); continue; } let message = Message::try_from(filled_buf).expect("I can't count"); println!("Got packet from {src_addr}: {message:?}"); } } } }