imdl/peer/
handshake.rs

1use crate::common::*;
2
3pub(crate) const HEADER: &[u8; 20] = b"\x13BitTorrent protocol";
4pub(crate) const SUPPORTS_EXTENSION_PROTOCOL: u8 = 0b0001_0000;
5pub(crate) const IMDL_RESERVED_BYTES: [u8; 8] = [0, 0, 0, 0, 0, SUPPORTS_EXTENSION_PROTOCOL, 0, 0];
6
7#[derive(Debug)]
8pub(crate) struct Handshake {
9  pub(crate) peer_id: [u8; 20],
10  pub(crate) infohash: [u8; 20],
11  pub(crate) reserved: [u8; 8],
12}
13
14impl Handshake {
15  pub(crate) const LENGTH: usize = 68;
16
17  pub(crate) fn new(infohash: Infohash) -> Self {
18    Handshake {
19      peer_id: rand::rng().random(),
20      infohash: infohash.into(),
21      reserved: IMDL_RESERVED_BYTES,
22    }
23  }
24
25  pub(crate) fn serialize(&self) -> [u8; Handshake::LENGTH] {
26    let mut msg = [0u8; Handshake::LENGTH];
27
28    msg[0..20].copy_from_slice(HEADER);
29    msg[20..28].copy_from_slice(&self.reserved);
30    msg[28..48].copy_from_slice(&self.infohash);
31    msg[48..68].copy_from_slice(&self.peer_id);
32
33    msg
34  }
35
36  pub fn supports_extension_protocol(&self) -> bool {
37    self.reserved[5] & SUPPORTS_EXTENSION_PROTOCOL > 0
38  }
39}
40
41impl TryFrom<[u8; Handshake::LENGTH]> for Handshake {
42  type Error = Error;
43
44  fn try_from(buf: [u8; Handshake::LENGTH]) -> Result<Self> {
45    if &buf[0..20] != HEADER {
46      return Err(error::Error::PeerHandshakeHeader);
47    }
48
49    let mut infohash = [0u8; 20];
50    let mut reserved = [0u8; 8];
51    let mut peer_id = [0u8; 20];
52
53    reserved.clone_from_slice(&buf[20..28]);
54    infohash.clone_from_slice(&buf[28..48]);
55    peer_id.clone_from_slice(&buf[48..68]);
56
57    Ok(Handshake {
58      peer_id,
59      infohash,
60      reserved,
61    })
62  }
63}
imdl/peer/handshake.rs

imdl/peer/
handshake.rs
