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server: Drop `ago` field
[tattlekey] / 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 t: SystemTime,
34 }
35
36 impl From<&[u8; MESSAGE_SIZE]> for Message {
37 fn from(value: &[u8; MESSAGE_SIZE]) -> Self {
38 let ago = u32::from_be_bytes(value[8..=11].try_into().expect("I can't count"));
39 Self {
40 key: MessageKey {
41 epoch: u32::from_be_bytes(value[0..=3].try_into().expect("I can't count")),
42 device: u16::from_be_bytes(value[4..=5].try_into().expect("I can't count")),
43 seq: u16::from_be_bytes(value[6..=7].try_into().expect("I can't count")),
44 },
45 t: SystemTime::now() - Duration::new(ago.into(), 0),
46 }
47 }
48 }
49 impl TryFrom<&[u8]> for Message {
50 type Error = std::array::TryFromSliceError;
51 fn try_from(value: &[u8]) -> Result<Self, Self::Error> {
52 match <[u8; MESSAGE_SIZE]>::try_from(value) {
53 Ok(correct_size) => Ok(Message::from(&correct_size)),
54 Err(e) => Err(e),
55 }
56 }
57 }
58
59 #[derive(Debug)]
60 struct Range {
61 start: SystemTime,
62 end: SystemTime,
63 }
64 impl Range {
65 fn new(t: &SystemTime) -> Self {
66 Self { start: *t, end: *t }
67 }
68 fn contains(&self, t: &SystemTime) -> bool {
69 t > &self.start && t < &self.end
70 }
71 fn extend(&mut self, t: &SystemTime) {
72 if t < &self.start {
73 self.start = *t;
74 }
75 if t > &self.end {
76 self.end = *t;
77 }
78 }
79 }
80
81 fn main() {
82 let mut presses = HashMap::<MessageKey, Range>::new();
83 let socket = UdpSocket::bind("0.0.0.0:29803").expect("couldn't bind to address");
84 loop {
85 let mut buf = [0; MESSAGE_SIZE];
86 match socket.recv_from(&mut buf) {
87 Err(e) => eprintln!("Didn't receive data: {e}"),
88 Ok((number_of_bytes, src_addr)) => {
89 let filled_buf = &buf[..number_of_bytes];
90 if number_of_bytes != MESSAGE_SIZE {
91 eprintln!("Ignoring short message ({number_of_bytes}) from {src_addr}");
92 continue;
93 }
94 let message = Message::try_from(filled_buf).expect("I can't count");
95 if let Some(r) = presses.get_mut(&message.key) {
96 if !r.contains(&message.t) {
97 r.extend(&message.t);
98 println!("Updated press: {:?}: {r:?}", message.key);
99 }
100 } else {
101 println!("Got new press: {:?}: {:?}", message.key, message.t);
102 presses.insert(message.key, Range::new(&message.t));
103 }
104 }
105 }
106 }
107 }