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-rw-r--r--src/proto.rs617
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diff --git a/src/proto.rs b/src/proto.rs
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-use std::collections::{HashMap, VecDeque};
-use std::pin::Pin;
-use std::sync::Arc;
-use std::task::{Context, Poll};
-
-use log::trace;
-
-use futures::channel::mpsc::{unbounded, UnboundedReceiver, UnboundedSender};
-use futures::{AsyncReadExt, AsyncWriteExt};
-use futures::{Stream, StreamExt};
-use kuska_handshake::async_std::BoxStreamWrite;
-
-use tokio::sync::mpsc;
-
-use async_trait::async_trait;
-
-use crate::error::*;
-use crate::util::{AssociatedStream, Packet};
-
-/// Priority of a request (click to read more about priorities).
-///
-/// This priority value is used to priorize messages
-/// in the send queue of the client, and their responses in the send queue of the
-/// server. Lower values mean higher priority.
-///
-/// This mechanism is usefull for messages bigger than the maximum chunk size
-/// (set at `0x4000` bytes), such as large file transfers.
-/// In such case, all of the messages in the send queue with the highest priority
-/// will take turns to send individual chunks, in a round-robin fashion.
-/// Once all highest priority messages are sent successfully, the messages with
-/// the next highest priority will begin being sent in the same way.
-///
-/// The same priority value is given to a request and to its associated response.
-pub type RequestPriority = u8;
-
-/// Priority class: high
-pub const PRIO_HIGH: RequestPriority = 0x20;
-/// Priority class: normal
-pub const PRIO_NORMAL: RequestPriority = 0x40;
-/// Priority class: background
-pub const PRIO_BACKGROUND: RequestPriority = 0x80;
-/// Priority: primary among given class
-pub const PRIO_PRIMARY: RequestPriority = 0x00;
-/// Priority: secondary among given class (ex: `PRIO_HIGH | PRIO_SECONDARY`)
-pub const PRIO_SECONDARY: RequestPriority = 0x01;
-
-// Messages are sent by chunks
-// Chunk format:
-// - u32 BE: request id (same for request and response)
-// - u16 BE: chunk length, possibly with CHUNK_HAS_CONTINUATION flag
-// when this is not the last chunk of the message
-// - [u8; chunk_length] chunk data
-
-pub(crate) type RequestID = u32;
-type ChunkLength = u16;
-const MAX_CHUNK_LENGTH: ChunkLength = 0x3FF0;
-const ERROR_MARKER: ChunkLength = 0x4000;
-const CHUNK_HAS_CONTINUATION: ChunkLength = 0x8000;
-
-struct SendQueueItem {
- id: RequestID,
- prio: RequestPriority,
- data: DataReader,
-}
-
-#[pin_project::pin_project]
-struct DataReader {
- #[pin]
- reader: AssociatedStream,
- packet: Packet,
- pos: usize,
- buf: Vec<u8>,
- eos: bool,
-}
-
-impl From<AssociatedStream> for DataReader {
- fn from(data: AssociatedStream) -> DataReader {
- DataReader {
- reader: data,
- packet: Ok(Vec::new()),
- pos: 0,
- buf: Vec::with_capacity(MAX_CHUNK_LENGTH as usize),
- eos: false,
- }
- }
-}
-
-enum DataFrame {
- Data {
- /// a fixed size buffer containing some data, possibly padded with 0s
- data: [u8; MAX_CHUNK_LENGTH as usize],
- /// actual lenght of data
- len: usize,
- },
- Error(u8),
-}
-
-struct DataReaderItem {
- data: DataFrame,
- /// whethere there may be more data comming from this stream. Can be used for some
- /// optimization. It's an error to set it to false if there is more data, but it is correct
- /// (albeit sub-optimal) to set it to true if there is nothing coming after
- may_have_more: bool,
-}
-
-impl DataReaderItem {
- fn empty_last() -> Self {
- DataReaderItem {
- data: DataFrame::Data {
- data: [0; MAX_CHUNK_LENGTH as usize],
- len: 0,
- },
- may_have_more: false,
- }
- }
-
- fn header(&self) -> [u8; 2] {
- let continuation = if self.may_have_more {
- CHUNK_HAS_CONTINUATION
- } else {
- 0
- };
- let len = match self.data {
- DataFrame::Data { len, .. } => len as u16,
- DataFrame::Error(e) => e as u16 | ERROR_MARKER,
- };
-
- ChunkLength::to_be_bytes(len | continuation)
- }
-
- fn data(&self) -> &[u8] {
- match self.data {
- DataFrame::Data { ref data, len } => &data[..len],
- DataFrame::Error(_) => &[],
- }
- }
-}
-
-impl Stream for DataReader {
- type Item = DataReaderItem;
-
- fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
- let mut this = self.project();
-
- if *this.eos {
- // eos was reached at previous call to poll_next, where a partial packet
- // was returned. Now return None
- return Poll::Ready(None);
- }
-
- loop {
- let packet = match this.packet {
- Ok(v) => v,
- Err(e) => {
- let e = *e;
- *this.packet = Ok(Vec::new());
- return Poll::Ready(Some(DataReaderItem {
- data: DataFrame::Error(e),
- may_have_more: true,
- }));
- }
- };
- let packet_left = packet.len() - *this.pos;
- let buf_left = MAX_CHUNK_LENGTH as usize - this.buf.len();
- let to_read = std::cmp::min(buf_left, packet_left);
- this.buf
- .extend_from_slice(&packet[*this.pos..*this.pos + to_read]);
- *this.pos += to_read;
- if this.buf.len() == MAX_CHUNK_LENGTH as usize {
- // we have a full buf, ready to send
- break;
- }
-
- // we don't have a full buf, packet is empty; try receive more
- if let Some(p) = futures::ready!(this.reader.as_mut().poll_next(cx)) {
- *this.packet = p;
- *this.pos = 0;
- // if buf is empty, we will loop and return the error directly. If buf
- // isn't empty, send it before by breaking.
- if this.packet.is_err() && !this.buf.is_empty() {
- break;
- }
- } else {
- *this.eos = true;
- break;
- }
- }
-
- let mut body = [0; MAX_CHUNK_LENGTH as usize];
- let len = this.buf.len();
- body[..len].copy_from_slice(this.buf);
- this.buf.clear();
- Poll::Ready(Some(DataReaderItem {
- data: DataFrame::Data { data: body, len },
- may_have_more: !*this.eos,
- }))
- }
-}
-
-struct SendQueue {
- items: VecDeque<(u8, VecDeque<SendQueueItem>)>,
-}
-
-impl SendQueue {
- fn new() -> Self {
- Self {
- items: VecDeque::with_capacity(64),
- }
- }
- fn push(&mut self, item: SendQueueItem) {
- let prio = item.prio;
- let pos_prio = match self.items.binary_search_by(|(p, _)| p.cmp(&prio)) {
- Ok(i) => i,
- Err(i) => {
- self.items.insert(i, (prio, VecDeque::new()));
- i
- }
- };
- self.items[pos_prio].1.push_back(item);
- }
- // used only in tests. They should probably be rewriten
- #[allow(dead_code)]
- fn pop(&mut self) -> Option<SendQueueItem> {
- match self.items.pop_front() {
- None => None,
- Some((prio, mut items_at_prio)) => {
- let ret = items_at_prio.pop_front();
- if !items_at_prio.is_empty() {
- self.items.push_front((prio, items_at_prio));
- }
- ret.or_else(|| self.pop())
- }
- }
- }
- fn is_empty(&self) -> bool {
- self.items.iter().all(|(_k, v)| v.is_empty())
- }
-
- // this is like an async fn, but hand implemented
- fn next_ready(&mut self) -> SendQueuePollNextReady<'_> {
- SendQueuePollNextReady { queue: self }
- }
-}
-
-struct SendQueuePollNextReady<'a> {
- queue: &'a mut SendQueue,
-}
-
-impl<'a> futures::Future for SendQueuePollNextReady<'a> {
- type Output = (RequestID, DataReaderItem);
-
- fn poll(mut self: Pin<&mut Self>, ctx: &mut Context<'_>) -> Poll<Self::Output> {
- for i in 0..self.queue.items.len() {
- let (_prio, items_at_prio) = &mut self.queue.items[i];
-
- for _ in 0..items_at_prio.len() {
- let mut item = items_at_prio.pop_front().unwrap();
-
- match Pin::new(&mut item.data).poll_next(ctx) {
- Poll::Pending => items_at_prio.push_back(item),
- Poll::Ready(Some(data)) => {
- let id = item.id;
- if data.may_have_more {
- self.queue.push(item);
- } else {
- if items_at_prio.is_empty() {
- // this priority level is empty, remove it
- self.queue.items.remove(i);
- }
- }
- return Poll::Ready((id, data));
- }
- Poll::Ready(None) => {
- if items_at_prio.is_empty() {
- // this priority level is empty, remove it
- self.queue.items.remove(i);
- }
- return Poll::Ready((item.id, DataReaderItem::empty_last()));
- }
- }
- }
- }
- // TODO what do we do if self.queue is empty? We won't get scheduled again.
- Poll::Pending
- }
-}
-
-/// The SendLoop trait, which is implemented both by the client and the server
-/// connection objects (ServerConna and ClientConn) adds a method `.send_loop()`
-/// that takes a channel of messages to send and an asynchronous writer,
-/// and sends messages from the channel to the async writer, putting them in a queue
-/// before being sent and doing the round-robin sending strategy.
-///
-/// The `.send_loop()` exits when the sending end of the channel is closed,
-/// or if there is an error at any time writing to the async writer.
-#[async_trait]
-pub(crate) trait SendLoop: Sync {
- async fn send_loop<W>(
- self: Arc<Self>,
- mut msg_recv: mpsc::UnboundedReceiver<(RequestID, RequestPriority, AssociatedStream)>,
- mut write: BoxStreamWrite<W>,
- ) -> Result<(), Error>
- where
- W: AsyncWriteExt + Unpin + Send + Sync,
- {
- let mut sending = SendQueue::new();
- let mut should_exit = false;
- while !should_exit || !sending.is_empty() {
- let recv_fut = msg_recv.recv();
- futures::pin_mut!(recv_fut);
- let send_fut = sending.next_ready();
-
- // recv_fut is cancellation-safe according to tokio doc,
- // send_fut is cancellation-safe as implemented above?
- use futures::future::Either;
- match futures::future::select(recv_fut, send_fut).await {
- Either::Left((sth, _send_fut)) => {
- if let Some((id, prio, data)) = sth {
- sending.push(SendQueueItem {
- id,
- prio,
- data: data.into(),
- });
- } else {
- should_exit = true;
- };
- }
- Either::Right(((id, data), _recv_fut)) => {
- trace!("send_loop: sending bytes for {}", id);
-
- let header_id = RequestID::to_be_bytes(id);
- write.write_all(&header_id[..]).await?;
-
- write.write_all(&data.header()).await?;
- write.write_all(data.data()).await?;
- write.flush().await?;
- }
- }
- }
-
- let _ = write.goodbye().await;
- Ok(())
- }
-}
-
-pub(crate) struct Framing {
- direct: Vec<u8>,
- stream: Option<AssociatedStream>,
-}
-
-impl Framing {
- pub fn new(direct: Vec<u8>, stream: Option<AssociatedStream>) -> Self {
- assert!(direct.len() <= u32::MAX as usize);
- Framing { direct, stream }
- }
-
- pub fn into_stream(self) -> AssociatedStream {
- use futures::stream;
- let len = self.direct.len() as u32;
- // required because otherwise the borrow-checker complains
- let Framing { direct, stream } = self;
-
- let res = stream::once(async move { Ok(u32::to_be_bytes(len).to_vec()) })
- .chain(stream::once(async move { Ok(direct) }));
-
- if let Some(stream) = stream {
- Box::pin(res.chain(stream))
- } else {
- Box::pin(res)
- }
- }
-
- pub async fn from_stream<S: Stream<Item = Packet> + Unpin + Send + 'static>(
- mut stream: S,
- ) -> Result<Self, Error> {
- let mut packet = stream
- .next()
- .await
- .ok_or(Error::Framing)?
- .map_err(|_| Error::Framing)?;
- if packet.len() < 4 {
- return Err(Error::Framing);
- }
-
- let mut len = [0; 4];
- len.copy_from_slice(&packet[..4]);
- let len = u32::from_be_bytes(len);
- packet.drain(..4);
-
- let mut buffer = Vec::new();
- let len = len as usize;
- loop {
- let max_cp = std::cmp::min(len - buffer.len(), packet.len());
-
- buffer.extend_from_slice(&packet[..max_cp]);
- if buffer.len() == len {
- packet.drain(..max_cp);
- break;
- }
- packet = stream
- .next()
- .await
- .ok_or(Error::Framing)?
- .map_err(|_| Error::Framing)?;
- }
-
- let stream: AssociatedStream = if packet.is_empty() {
- Box::pin(stream)
- } else {
- Box::pin(futures::stream::once(async move { Ok(packet) }).chain(stream))
- };
-
- Ok(Framing {
- direct: buffer,
- stream: Some(stream),
- })
- }
-
- pub fn into_parts(self) -> (Vec<u8>, AssociatedStream) {
- let Framing { direct, stream } = self;
- (direct, stream.unwrap_or(Box::pin(futures::stream::empty())))
- }
-}
-
-/// Structure to warn when the sender is dropped before end of stream was reached, like when
-/// connection to some remote drops while transmitting data
-struct Sender {
- inner: UnboundedSender<Packet>,
- closed: bool,
-}
-
-impl Sender {
- fn new(inner: UnboundedSender<Packet>) -> Self {
- Sender {
- inner,
- closed: false,
- }
- }
-
- fn send(&self, packet: Packet) {
- let _ = self.inner.unbounded_send(packet);
- }
-
- fn end(&mut self) {
- self.closed = true;
- }
-}
-
-impl Drop for Sender {
- fn drop(&mut self) {
- if !self.closed {
- self.send(Err(255));
- }
- self.inner.close_channel();
- }
-}
-
-/// The RecvLoop trait, which is implemented both by the client and the server
-/// connection objects (ServerConn and ClientConn) adds a method `.recv_loop()`
-/// and a prototype of a handler for received messages `.recv_handler()` that
-/// must be filled by implementors. `.recv_loop()` receives messages in a loop
-/// according to the protocol defined above: chunks of message in progress of being
-/// received are stored in a buffer, and when the last chunk of a message is received,
-/// the full message is passed to the receive handler.
-#[async_trait]
-pub(crate) trait RecvLoop: Sync + 'static {
- fn recv_handler(self: &Arc<Self>, id: RequestID, stream: UnboundedReceiver<Packet>);
-
- async fn recv_loop<R>(self: Arc<Self>, mut read: R) -> Result<(), Error>
- where
- R: AsyncReadExt + Unpin + Send + Sync,
- {
- let mut streams: HashMap<RequestID, Sender> = HashMap::new();
- loop {
- trace!("recv_loop: reading packet");
- let mut header_id = [0u8; RequestID::BITS as usize / 8];
- match read.read_exact(&mut header_id[..]).await {
- Ok(_) => (),
- Err(e) if e.kind() == std::io::ErrorKind::UnexpectedEof => break,
- Err(e) => return Err(e.into()),
- };
- let id = RequestID::from_be_bytes(header_id);
- trace!("recv_loop: got header id: {:04x}", id);
-
- let mut header_size = [0u8; ChunkLength::BITS as usize / 8];
- read.read_exact(&mut header_size[..]).await?;
- let size = ChunkLength::from_be_bytes(header_size);
- trace!("recv_loop: got header size: {:04x}", size);
-
- let has_cont = (size & CHUNK_HAS_CONTINUATION) != 0;
- let is_error = (size & ERROR_MARKER) != 0;
- let packet = if is_error {
- Err(size as u8)
- } else {
- let size = size & !CHUNK_HAS_CONTINUATION;
- let mut next_slice = vec![0; size as usize];
- read.read_exact(&mut next_slice[..]).await?;
- trace!("recv_loop: read {} bytes", next_slice.len());
- Ok(next_slice)
- };
-
- let mut sender = if let Some(send) = streams.remove(&(id)) {
- send
- } else {
- let (send, recv) = unbounded();
- self.recv_handler(id, recv);
- Sender::new(send)
- };
-
- // if we get an error, the receiving end is disconnected. We still need to
- // reach eos before dropping this sender
- sender.send(packet);
-
- if has_cont {
- streams.insert(id, sender);
- } else {
- sender.end();
- }
- }
- Ok(())
- }
-}
-
-#[cfg(test)]
-mod test {
- use super::*;
-
- fn empty_data() -> DataReader {
- type Item = Packet;
- let stream: Pin<Box<dyn futures::Stream<Item = Item> + Send + 'static>> =
- Box::pin(futures::stream::empty::<Packet>());
- stream.into()
- }
-
- #[test]
- fn test_priority_queue() {
- let i1 = SendQueueItem {
- id: 1,
- prio: PRIO_NORMAL,
- data: empty_data(),
- };
- let i2 = SendQueueItem {
- id: 2,
- prio: PRIO_HIGH,
- data: empty_data(),
- };
- let i2bis = SendQueueItem {
- id: 20,
- prio: PRIO_HIGH,
- data: empty_data(),
- };
- let i3 = SendQueueItem {
- id: 3,
- prio: PRIO_HIGH | PRIO_SECONDARY,
- data: empty_data(),
- };
- let i4 = SendQueueItem {
- id: 4,
- prio: PRIO_BACKGROUND | PRIO_SECONDARY,
- data: empty_data(),
- };
- let i5 = SendQueueItem {
- id: 5,
- prio: PRIO_BACKGROUND | PRIO_PRIMARY,
- data: empty_data(),
- };
-
- let mut q = SendQueue::new();
-
- q.push(i1); // 1
- let a = q.pop().unwrap(); // empty -> 1
- assert_eq!(a.id, 1);
- assert!(q.pop().is_none());
-
- q.push(a); // 1
- q.push(i2); // 2 1
- q.push(i2bis); // [2 20] 1
- let a = q.pop().unwrap(); // 20 1 -> 2
- assert_eq!(a.id, 2);
- let b = q.pop().unwrap(); // 1 -> 20
- assert_eq!(b.id, 20);
- let c = q.pop().unwrap(); // empty -> 1
- assert_eq!(c.id, 1);
- assert!(q.pop().is_none());
-
- q.push(a); // 2
- q.push(b); // [2 20]
- q.push(c); // [2 20] 1
- q.push(i3); // [2 20] 3 1
- q.push(i4); // [2 20] 3 1 4
- q.push(i5); // [2 20] 3 1 5 4
-
- let a = q.pop().unwrap(); // 20 3 1 5 4 -> 2
- assert_eq!(a.id, 2);
- q.push(a); // [20 2] 3 1 5 4
-
- let a = q.pop().unwrap(); // 2 3 1 5 4 -> 20
- assert_eq!(a.id, 20);
- let b = q.pop().unwrap(); // 3 1 5 4 -> 2
- assert_eq!(b.id, 2);
- q.push(b); // 2 3 1 5 4
- let b = q.pop().unwrap(); // 3 1 5 4 -> 2
- assert_eq!(b.id, 2);
- let c = q.pop().unwrap(); // 1 5 4 -> 3
- assert_eq!(c.id, 3);
- q.push(b); // 2 1 5 4
- let b = q.pop().unwrap(); // 1 5 4 -> 2
- assert_eq!(b.id, 2);
- let e = q.pop().unwrap(); // 5 4 -> 1
- assert_eq!(e.id, 1);
- let f = q.pop().unwrap(); // 4 -> 5
- assert_eq!(f.id, 5);
- let g = q.pop().unwrap(); // empty -> 4
- assert_eq!(g.id, 4);
- assert!(q.pop().is_none());
- }
-}
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