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use flume::{Receiver, Sender};
use rand_chacha::ChaCha20Rng;
use tokio::io::{AsyncWriteExt, BufReader, BufWriter, ReadHalf, WriteHalf};
use super::frame::Frame;
use super::stream::Stream;
use super::FrameType;
#[allow(unused_imports)] // for intra doc links
use super::WebSocket;
use crate::error::WebSocketError;
/// Events sent from the read half to the write half
#[derive(Debug)]
pub(super) enum Event {
SendPongFrame(Frame),
SendCloseFrameAndShutdown(Frame),
}
/// The read half of a WebSocket connection, generated from [`WebSocket::split()`].
/// This half can only receive frames.
#[derive(Debug)]
pub struct WebSocketReadHalf {
pub(super) stream: BufReader<ReadHalf<Stream>>,
pub(super) last_frame_type: FrameType,
pub(super) sender: Sender<Event>,
}
impl WebSocketReadHalf {
/// Receives a [`Frame`] over the WebSocket connection.
///
/// If the received frame is a Ping frame, an event to send a Pong frame will be queued.
/// If the received frame is a Close frame, an event to send a Close frame
/// will be queued and the WebSocket will close. However, events are not
/// acted upon unless flushed (see the documentation on the [`WebSocket`](WebSocket#splitting)
/// type for more details).
pub async fn receive(&mut self) -> Result<Frame, WebSocketError> {
let frame = self.receive_without_handling().await?;
// handle incoming frames
match &frame {
// echo ping frame (https://tools.ietf.org/html/rfc6455#section-5.5.2)
Frame::Ping { payload } => {
let pong = Frame::Pong {
payload: payload.clone(),
};
self.sender
.send(Event::SendPongFrame(pong))
.map_err(|_e| WebSocketError::ChannelError)?;
}
// echo close frame and shutdown (https://tools.ietf.org/html/rfc6455#section-1.4)
Frame::Close { payload } => {
let close = Frame::Close {
payload: payload
.as_ref()
.map(|(status_code, _reason)| (status_code.clone(), String::new())),
};
self.sender
.send(Event::SendCloseFrameAndShutdown(close))
.map_err(|_e| WebSocketError::ChannelError)?;
}
_ => (),
}
Ok(frame)
}
/// Receives a [`Frame`] over the WebSocket connection **without handling incoming frames.**
/// For example, receiving a Ping frame will not queue a Pong frame to be sent,
/// and receiving a Close frame will not queue a Close frame to be sent nor close
/// the connection.
///
/// To automatically handle incoming frames, use the [`receive()`](WebSocketReadHalf::receive())
/// method instead.
pub async fn receive_without_handling(&mut self) -> Result<Frame, WebSocketError> {
let frame = Frame::read_from_websocket(self).await?;
// remember last data frame type in case we get continuation frames (https://tools.ietf.org/html/rfc6455#section-5.2)
match frame {
Frame::Text { .. } => self.last_frame_type = FrameType::Text,
Frame::Binary { .. } => self.last_frame_type = FrameType::Binary,
_ => (),
};
Ok(frame)
}
}
/// The write half of a WebSocket connection, generated from [`WebSocket::split()`].
/// This half can only send frames.
#[derive(Debug)]
pub struct WebSocketWriteHalf {
pub(super) shutdown: bool,
pub(super) sent_closed: bool,
pub(super) stream: BufWriter<WriteHalf<Stream>>,
pub(super) rng: ChaCha20Rng,
pub(super) receiver: Receiver<Event>,
}
impl WebSocketWriteHalf {
/// Flushes incoming events from the read half. If the read half received a Ping frame,
/// a Pong frame will be sent. If the read half received a Close frame,
/// an echoed Close frame will be sent and the WebSocket will close.
/// See the documentation on the [`WebSocket`](WebSocket#splitting) type for more details
/// about events.
pub async fn flush(&mut self) -> Result<(), WebSocketError> {
while let Ok(event) = self.receiver.try_recv() {
if self.shutdown {
break;
}
match event {
Event::SendPongFrame(frame) => self.send_without_events_check(frame).await?,
Event::SendCloseFrameAndShutdown(frame) => {
// read half will always send this event if it has received a close frame,
// but if we have sent one already, then we have sent and received a close
// frame, so we will shutdown
if self.sent_closed {
self.send_without_events_check(frame).await?;
self.shutdown().await?;
}
}
};
}
Ok(())
}
/// Sends an already constructed [`Frame`] over the WebSocket connection.
///
/// This method will flush incoming events.
/// See the documentation on the [`WebSocket`](WebSocket#splitting) type for more details
/// about events.
pub async fn send(&mut self, frame: Frame) -> Result<(), WebSocketError> {
self.flush().await?;
if self.shutdown || self.sent_closed {
return Err(WebSocketError::WebSocketClosedError);
}
self.send_without_events_check(frame).await
}
/// Sends an already constructed [`Frame`] over the WebSocket connection
/// without flushing incoming events from the read half.
/// See the documentation on the [`WebSocket`](WebSocket#splitting) type for more details
/// about events.
async fn send_without_events_check(&mut self, frame: Frame) -> Result<(), WebSocketError> {
frame.send(self).await?;
Ok(())
}
/// Sends a Text frame over the WebSocket connection, constructed
/// from passed arguments. `continuation` will be `false` and `fin` will be `true`.
/// To use a custom `continuation` or `fin`, construct a [`Frame`] and use
/// [`WebSocketWriteHalf::send()`].
///
/// This method will flush incoming events.
/// See the documentation on the [`WebSocket`](WebSocket#splitting) type for more details
/// about events.
pub async fn send_text(&mut self, payload: String) -> Result<(), WebSocketError> {
// https://tools.ietf.org/html/rfc6455#section-5.6
self.send(Frame::text(payload)).await
}
/// Sends a Binary frame over the WebSocket connection, constructed
/// from passed arguments. `continuation` will be `false` and `fin` will be `true`.
/// To use a custom `continuation` or `fin`, construct a [`Frame`] and use
/// [`WebSocketWriteHalf::send()`].
///
/// This method will flush incoming events.
/// See the documentation on the [`WebSocket`](WebSocket#splitting) type for more details
/// about events.
pub async fn send_binary(&mut self, payload: Vec<u8>) -> Result<(), WebSocketError> {
// https://tools.ietf.org/html/rfc6455#section-5.6
self.send(Frame::binary(payload)).await
}
/// Shuts down the WebSocket connection **without sending a Close frame**.
/// It is recommended to use the [`close()`](WebSocketWriteHalf::close()) method instead.
pub async fn shutdown(&mut self) -> Result<(), WebSocketError> {
self.stream
.shutdown()
.await
.map_err(|e| WebSocketError::ShutdownError(e))?;
// indicates that a closed frame has been sent, so no more frames should be sent,
// but the underlying stream is not technically closed (closing the stream
// would prevent a Close frame from being received by the read half)
self.sent_closed = true;
Ok(())
}
/// Sends a Close frame over the WebSocket connection, constructed
/// from passed arguments, and closes the WebSocket connection.
///
/// As per the WebSocket protocol, the server should send a Close frame in response
/// upon receiving a Close frame. Although the write half will be closed,
/// the server's echoed Close frame can be read from the still open read half.
///
/// This method will flush incoming events.
/// See the documentation on the [`WebSocket`](WebSocket#splitting) type for more details
/// about events.
pub async fn close(&mut self, payload: Option<(u16, String)>) -> Result<(), WebSocketError> {
// https://tools.ietf.org/html/rfc6455#section-5.5.1
self.send(Frame::Close { payload }).await?;
// self.shutdown().await?;
Ok(())
}
/// Sends a Ping frame over the WebSocket connection, constructed
/// from passed arguments.
///
/// This method will flush incoming events.
/// See the documentation on the [`WebSocket`](WebSocket#splitting) type for more details
/// about events.
pub async fn send_ping(&mut self, payload: Option<Vec<u8>>) -> Result<(), WebSocketError> {
// https://tools.ietf.org/html/rfc6455#section-5.5.2
self.send(Frame::Ping { payload }).await
}
/// Sends a Pong frame over the WebSocket connection, constructed
/// from passed arguments.
///
/// This method will flush incoming events.
/// See the documentation on the [`WebSocket`](WebSocket#splitting) type for more details
/// about events.
pub async fn send_pong(&mut self, payload: Option<Vec<u8>>) -> Result<(), WebSocketError> {
// https://tools.ietf.org/html/rfc6455#section-5.5.3
self.send(Frame::Pong { payload }).await
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn assert_send_sync()
where
WebSocketReadHalf: Send + Sync,
WebSocketWriteHalf: Send + Sync,
{
}
}