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use std::sync::atomic::Ordering;
use std::time::Instant;
use byteorder::{ByteOrder, LittleEndian};
use crossbeam_channel::Receiver;
use log::debug;
use rand::rngs::OsRng;
use x25519_dalek::PublicKey;
// IO traits
use super::Endpoint;
use super::tun::Reader as TunReader;
use super::tun::Tun;
use super::udp::Reader as UDPReader;
use super::udp::UDP;
// constants
use super::constants::{
DURATION_UNDER_LOAD, MAX_QUEUED_INCOMING_HANDSHAKES, MESSAGE_PADDING_MULTIPLE,
THRESHOLD_UNDER_LOAD,
};
use super::handshake::MAX_HANDSHAKE_MSG_SIZE;
use super::handshake::{TYPE_COOKIE_REPLY, TYPE_INITIATION, TYPE_RESPONSE};
use super::router::{CAPACITY_MESSAGE_POSTFIX, SIZE_MESSAGE_PREFIX, TYPE_TRANSPORT};
use super::wireguard::WireGuard;
pub enum HandshakeJob<E> {
Message(Vec<u8>, E),
New(PublicKey),
}
/* Returns the padded length of a message:
*
* # Arguments
*
* - `size` : Size of unpadded message
* - `mtu` : Maximum transmission unit of the device
*
* # Returns
*
* The padded length (always less than or equal to the MTU)
*/
#[inline(always)]
const fn padding(size: usize, mtu: usize) -> usize {
#[inline(always)]
const fn min(a: usize, b: usize) -> usize {
let m = (a < b) as usize;
a * m + (1 - m) * b
}
let pad = MESSAGE_PADDING_MULTIPLE;
min(mtu, size + (pad - size % pad) % pad)
}
pub fn tun_worker<T: Tun, B: UDP>(wg: &WireGuard<T, B>, reader: T::Reader) {
loop {
// create vector big enough for any transport message (based on MTU)
let mtu = wg.mtu.load(Ordering::Relaxed);
let size = mtu + SIZE_MESSAGE_PREFIX + 1;
let mut msg: Vec<u8> = vec![0; size + CAPACITY_MESSAGE_POSTFIX];
// read a new IP packet
let payload = match reader.read(&mut msg[..], SIZE_MESSAGE_PREFIX) {
Ok(payload) => payload,
Err(e) => {
debug!("TUN worker, failed to read from tun device: {}", e);
break;
}
};
debug!("TUN worker, IP packet of {} bytes (MTU = {})", payload, mtu);
// check if device is down
if mtu == 0 {
continue;
}
// truncate padding
let padded = padding(payload, mtu);
log::trace!(
"TUN worker, payload length = {}, padded length = {}",
payload,
padded
);
msg.truncate(SIZE_MESSAGE_PREFIX + padded);
debug_assert!(padded <= mtu);
debug_assert_eq!(
if padded < mtu {
(msg.len() - SIZE_MESSAGE_PREFIX) % MESSAGE_PADDING_MULTIPLE
} else {
0
},
0
);
// crypt-key route
let e = wg.router.send(msg);
debug!("TUN worker, router returned {:?}", e);
}
}
pub fn udp_worker<T: Tun, B: UDP>(wg: &WireGuard<T, B>, reader: B::Reader) {
loop {
// create vector big enough for any message given current MTU
let mtu = wg.mtu.load(Ordering::Relaxed);
let size = mtu + MAX_HANDSHAKE_MSG_SIZE;
let mut msg: Vec<u8> = vec![0; size];
// read UDP packet into vector
let (size, src) = match reader.read(&mut msg) {
Err(e) => {
debug!("Bind reader closed with {}", e);
return;
}
Ok(v) => v,
};
msg.truncate(size);
// TODO: start device down
if mtu == 0 {
continue;
}
// message type de-multiplexer
if msg.len() < std::mem::size_of::<u32>() {
continue;
}
match LittleEndian::read_u32(&msg[..]) {
TYPE_COOKIE_REPLY | TYPE_INITIATION | TYPE_RESPONSE => {
debug!("{} : reader, received handshake message", wg);
wg.pending.fetch_add(1, Ordering::SeqCst);
wg.queue.send(HandshakeJob::Message(msg, src));
}
TYPE_TRANSPORT => {
debug!("{} : reader, received transport message", wg);
// transport message
let _ = wg.router.recv(src, msg).map_err(|e| {
debug!("Failed to handle incoming transport message: {}", e);
});
}
_ => (),
}
}
}
pub fn handshake_worker<T: Tun, B: UDP>(
wg: &WireGuard<T, B>,
rx: Receiver<HandshakeJob<B::Endpoint>>,
) {
debug!("{} : handshake worker, started", wg);
// process elements from the handshake queue
for job in rx {
// check if under load
let mut under_load = false;
let job: HandshakeJob<B::Endpoint> = job;
let pending = wg.pending.fetch_sub(1, Ordering::SeqCst);
debug_assert!(pending < MAX_QUEUED_INCOMING_HANDSHAKES + (1 << 16));
// immediate go under load if too many handshakes pending
if pending > THRESHOLD_UNDER_LOAD {
log::trace!("{} : handshake worker, under load (above threshold)", wg);
*wg.last_under_load.lock() = Instant::now();
under_load = true;
}
// remain under load for DURATION_UNDER_LOAD
if !under_load {
let elapsed = wg.last_under_load.lock().elapsed();
if DURATION_UNDER_LOAD >= elapsed {
log::trace!("{} : handshake worker, under load (recent)", wg);
under_load = true;
}
}
// de-multiplex staged handshake jobs and handshake messages
match job {
HandshakeJob::Message(msg, mut src) => {
// process message
let device = wg.peers.read();
match device.process(
&mut OsRng,
&msg[..],
if under_load {
Some(src.into_address())
} else {
None
},
) {
Ok((peer, resp, keypair)) => {
// send response (might be cookie reply or handshake response)
let mut resp_len: u64 = 0;
if let Some(msg) = resp {
resp_len = msg.len() as u64;
let _ = wg.router.write(&msg[..], &mut src).map_err(|e| {
debug!(
"{} : handshake worker, failed to send response, error = {}",
wg, e
);
});
}
// update peer state
if let Some(peer) = peer {
// authenticated handshake packet received
// add to rx_bytes and tx_bytes
let req_len = msg.len() as u64;
peer.rx_bytes.fetch_add(req_len, Ordering::Relaxed);
peer.tx_bytes.fetch_add(resp_len, Ordering::Relaxed);
// update endpoint
peer.router.set_endpoint(src);
if resp_len > 0 {
// update timers after sending handshake response
debug!("{} : handshake worker, handshake response sent", wg);
peer.state.sent_handshake_response();
} else {
// update timers after receiving handshake response
debug!(
"{} : handshake worker, handshake response was received",
wg
);
peer.state.timers_handshake_complete();
}
// add any new keypair to peer
keypair.map(|kp| {
debug!("{} : handshake worker, new keypair for {}", wg, peer);
// this means that a handshake response was processed or sent
peer.timers_session_derived();
// free any unused ids
for id in peer.router.add_keypair(kp) {
device.release(id);
}
});
}
}
Err(e) => debug!("{} : handshake worker, error = {:?}", wg, e),
}
}
HandshakeJob::New(pk) => {
if let Some(peer) = wg.peers.read().get(&pk) {
debug!(
"{} : handshake worker, new handshake requested for {}",
wg, peer
);
let device = wg.peers.read();
let _ = device.begin(&mut OsRng, &peer.pk).map(|msg| {
let _ = peer.router.send(&msg[..]).map_err(|e| {
debug!("{} : handshake worker, failed to send handshake initiation, error = {}", wg, e)
});
peer.state.sent_handshake_initiation();
});
peer.handshake_queued.store(false, Ordering::SeqCst);
}
}
}
}
}
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