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use std::iter;
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::mpsc::{sync_channel, Receiver, TryRecvError};
use std::sync::{Arc, Weak};
use std::thread;
use spin;
use crossbeam_deque::{Injector, Steal, Stealer, Worker};
use ring::aead::{Aad, LessSafeKey, Nonce, UnboundKey, CHACHA20_POLY1305};
use zerocopy::{AsBytes, ByteSlice, ByteSliceMut, FromBytes, LayoutVerified, Unaligned};
use super::device::DecryptionState;
use super::device::DeviceInner;
use super::messages::TransportHeader;
use super::peer::PeerInner;
use super::types::{Callback, KeyCallback, Opaque};
#[derive(PartialEq, Debug)]
enum Operation {
Encryption,
Decryption,
}
#[derive(PartialEq, Debug)]
enum Status {
Fault, // unsealing failed
Done, // job valid and complete
Waiting, // job awaiting completion
}
pub struct JobInner {
msg: Vec<u8>, // message buffer (nonce and receiver id set)
key: [u8; 32], // chacha20poly1305 key
status: Status, // state of the job
op: Operation, // should be buffer be encrypted / decrypted?
}
pub type JobBuffer = Arc<spin::Mutex<JobInner>>;
pub type JobParallel = (Arc<thread::JoinHandle<()>>, JobBuffer);
pub type JobInbound<T, S, R, K> = (Weak<DecryptionState<T, S, R, K>>, JobBuffer);
pub type JobOutbound = JobBuffer;
/* Strategy for workers acquiring a new job:
*
* 1. Try the local job queue (owned by the thread)
* 2. Try fetching a batch of jobs from the global injector
* 3. Attempt to steal jobs from other threads.
*/
fn find_task<T>(local: &Worker<T>, global: &Injector<T>, stealers: &[Stealer<T>]) -> Option<T> {
local.pop().or_else(|| {
iter::repeat_with(|| {
global
.steal_batch_and_pop(local)
.or_else(|| stealers.iter().map(|s| s.steal()).collect())
})
.find(|s| !s.is_retry())
.and_then(|s| s.success())
})
}
fn wait_buffer(stopped: AtomicBool, buf: &JobBuffer) {
while !stopped.load(Ordering::Acquire) {
match buf.try_lock() {
None => (),
Some(buf) => {
if buf.status == Status::Waiting {
return;
}
}
};
thread::park();
}
}
fn wait_recv<T>(stopped: &AtomicBool, recv: &Receiver<T>) -> Result<T, TryRecvError> {
while !stopped.load(Ordering::Acquire) {
match recv.try_recv() {
Err(TryRecvError::Empty) => (),
value => {
return value;
}
};
thread::park();
}
return Err(TryRecvError::Disconnected);
}
pub fn worker_inbound<T: Opaque, S: Callback<T>, R: Callback<T>, K: KeyCallback<T>>(
device: Arc<DeviceInner<T, S, R, K>>, // related device
peer: Arc<PeerInner<T, S, R, K>>, // related peer
recv: Receiver<JobInbound<T, S, R, K>>, // in order queue
) {
loop {
match wait_recv(&peer.stopped, &recv) {
Ok((state, buf)) => {
while !peer.stopped.load(Ordering::Acquire) {
match buf.try_lock() {
None => (),
Some(buf) => {
if buf.status != Status::Waiting {
// consume
break;
}
}
};
thread::park();
}
}
Err(_) => {
break;
}
}
}
}
pub fn worker_outbound<T: Opaque, S: Callback<T>, R: Callback<T>, K: KeyCallback<T>>(
device: Arc<DeviceInner<T, S, R, K>>, // related device
peer: Arc<PeerInner<T, S, R, K>>, // related peer
recv: Receiver<JobOutbound>, // in order queue
) {
loop {
match wait_recv(&peer.stopped, &recv) {
Ok(buf) => {
while !peer.stopped.load(Ordering::Acquire) {
match buf.try_lock() {
None => (),
Some(buf) => {
if buf.status != Status::Waiting {
// consume
break;
}
}
};
thread::park();
}
}
Err(_) => {
break;
}
}
}
}
pub fn worker_parallel(
stopped: Arc<AtomicBool>, // stop workers (device has been dropped)
parked: Arc<AtomicBool>, // thread has been parked?
local: Worker<JobParallel>, // local job queue (local to thread)
global: Injector<JobParallel>, // global job injector
stealers: Vec<Stealer<JobParallel>>, // stealers (from other threads)
) {
while !stopped.load(Ordering::SeqCst) {
match find_task(&local, &global, &stealers) {
Some(job) => {
let (handle, buf) = job;
// take ownership of the job buffer and complete it
{
let mut buf = buf.lock();
// cast and check size of packet
let (header, packet) = match LayoutVerified::new_from_prefix(&buf.msg[..]) {
Some(v) => v,
None => continue,
};
if packet.len() < CHACHA20_POLY1305.nonce_len() {
continue;
}
let header: LayoutVerified<&[u8], TransportHeader> = header;
// do the weird ring AEAD dance
let key = LessSafeKey::new(
UnboundKey::new(&CHACHA20_POLY1305, &buf.key[..]).unwrap(),
);
// create a nonce object
let mut nonce = [0u8; 12];
debug_assert_eq!(nonce.len(), CHACHA20_POLY1305.nonce_len()); // why the fuck this is not a constant, god knows...
nonce[4..].copy_from_slice(header.f_counter.as_bytes());
let nonce = Nonce::assume_unique_for_key(nonce);
match buf.op {
Operation::Encryption => {
// note: extends the vector to accommodate the tag
key.seal_in_place_append_tag(nonce, Aad::empty(), &mut buf.msg)
.unwrap();
buf.status = Status::Done;
}
Operation::Decryption => {
// opening failure is signaled by fault state
buf.status = match key.open_in_place(nonce, Aad::empty(), &mut buf.msg)
{
Ok(_) => Status::Done,
Err(_) => Status::Fault,
};
}
}
}
// ensure consumer is unparked
handle.thread().unpark();
}
None => {
// no jobs, park the worker
parked.store(true, Ordering::Release);
thread::park();
}
}
}
}
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