git.scottworley.com Git - tattlekey/blob - server/src/main.rs

   1 // tattlekey: A one-key UDP keyboard
   2 // Copyright (C) 2023  Scott Worley <scottworley@scottworley.com>
   3 //
   4 // This program is free software: you can redistribute it and/or modify
   5 // it under the terms of the GNU General Public License as published by
   6 // the Free Software Foundation, either version 3 of the License, or
   7 // (at your option) any later version.
   8 //
   9 // This program is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13 //
  14 // You should have received a copy of the GNU General Public License
  15 // along with this program.  If not, see <https://www.gnu.org/licenses/>.
  16
  17 use std::collections::HashMap;
  18 use std::net::UdpSocket;
  19 use std::time::{Duration, SystemTime};
  20
  21 const MESSAGE_SIZE: usize = 12;
  22
  23 #[derive(Eq, Debug, Hash, PartialEq)]
  24 struct MessageKey {
  25     epoch: u32,
  26     device: u16,
  27     seq: u16,
  28 }
  29
  30 #[derive(Debug)]
  31 struct Message {
  32     key: MessageKey,
  33     ago: u32,
  34     t: SystemTime,
  35 }
  36
  37 impl From<&[u8; MESSAGE_SIZE]> for Message {
  38     fn from(value: &[u8; MESSAGE_SIZE]) -> Self {
  39         let ago = u32::from_be_bytes(value[8..=11].try_into().expect("I can't count"));
  40         Self {
  41             key: MessageKey {
  42                 epoch: u32::from_be_bytes(value[0..=3].try_into().expect("I can't count")),
  43                 device: u16::from_be_bytes(value[4..=5].try_into().expect("I can't count")),
  44                 seq: u16::from_be_bytes(value[6..=7].try_into().expect("I can't count")),
  45             },
  46             ago,
  47             t: SystemTime::now() - Duration::new(ago.into(), 0),
  48         }
  49     }
  50 }
  51 impl TryFrom<&[u8]> for Message {
  52     type Error = std::array::TryFromSliceError;
  53     fn try_from(value: &[u8]) -> Result<Self, Self::Error> {
  54         match <[u8; MESSAGE_SIZE]>::try_from(value) {
  55             Ok(correct_size) => Ok(Message::from(&correct_size)),
  56             Err(e) => Err(e),
  57         }
  58     }
  59 }
  60
  61 #[derive(Debug)]
  62 struct Range {
  63     start: SystemTime,
  64     end: SystemTime,
  65 }
  66 impl Range {
  67     fn new(t: &SystemTime) -> Self {
  68         Self { start: *t, end: *t }
  69     }
  70     fn contains(&self, t: &SystemTime) -> bool {
  71         t > &self.start && t < &self.end
  72     }
  73     fn extend(&mut self, t: &SystemTime) {
  74         if t < &self.start {
  75             self.start = *t;
  76         }
  77         if t > &self.end {
  78             self.end = *t;
  79         }
  80     }
  81 }
  82
  83 fn main() {
  84     let mut presses = HashMap::<MessageKey, Range>::new();
  85     let socket = UdpSocket::bind("0.0.0.0:29803").expect("couldn't bind to address");
  86     loop {
  87         let mut buf = [0; MESSAGE_SIZE];
  88         match socket.recv_from(&mut buf) {
  89             Err(e) => eprintln!("Didn't receive data: {e}"),
  90             Ok((number_of_bytes, src_addr)) => {
  91                 let filled_buf = &buf[..number_of_bytes];
  92                 if number_of_bytes != MESSAGE_SIZE {
  93                     eprintln!("Ignoring short message ({number_of_bytes}) from {src_addr}");
  94                     continue;
  95                 }
  96                 let message = Message::try_from(filled_buf).expect("I can't count");
  97                 if let Some(r) = presses.get_mut(&message.key) {
  98                     if !r.contains(&message.t) {
  99                         r.extend(&message.t);
 100                         println!("Updated press: {:?}: {r:?}", message.key);
 101                     }
 102                 } else {
 103                     println!("Got new press: {:?}: {:?}", message.key, message.t);
 104                     presses.insert(message.key, Range::new(&message.t));
 105                 }
 106             }
 107         }
 108     }
 109 }