Test: WebSocket close behavior.

[mstyura]

PR Type

Test/Question/Other

PR Checklist

• Tests for the changes have been added / updated.
• Documentation comments have been added / updated.
• A changelog entry has been made for the appropriate packages.
• Format code with the latest stable rustfmt.
• (Team) Label with affected crates and semver status.

Overview

This PR emphasises my question regarding proper behavior of WebSocket close procedure.
It seems like neither receiving close and sending it back to client nor initiating close and receiving it back from client (close handshake) does not cause web socket stream to finish and TCP connection released.

I'm not sure if it's my expectation from API is wrong or there is a bug. But anyway the question is what is the proper way to terminate WebSocket (except ctx.stop() which seems to terminate connection ungracefully, possibly loosing pending messages)?

I've inspected code and it seems like there are some parts which are intended to do some special handling of web socket closure, but this code seems to be never executed. E.g. there is Message::Close with single usage across actix-web repo, so it's not created anywhere:

actix-web/actix-http/src/ws/dispatcher.rs

Lines 357 to 360 in ff8fd2f

	Poll::Ready(Some(Ok(Message::Close))) => {
	*this.state = State::FlushAndStop;
	return true;
	}

There is also some code within WebsocketContextFut to mark WebSocket as closed, which marks WS as closed when None is read from messages queue:

actix-web/actix-web-actors/src/ws.rs

Lines 703 to 710 in ff8fd2f

	while let Some(item) = this.fut.ctx().messages.pop_front() {
	if let Some(msg) = item {
	this.encoder.encode(msg, &mut this.buf)?;
	} else {
	this.closed = true;
	break;
	}
	}

while there is no possibly to write None to outgoing messages queue:

actix-web/actix-web-actors/src/ws.rs

Lines 605 to 638 in ff8fd2f

	#[inline]
	pub fn write_raw(&mut self, msg: Message) {
	self.messages.push_back(Some(msg));
	}
	/// Send text frame
	#[inline]
	pub fn text(&mut self, text: impl Into<ByteString>) {
	self.write_raw(Message::Text(text.into()));
	}
	/// Send binary frame
	#[inline]
	pub fn binary(&mut self, data: impl Into<Bytes>) {
	self.write_raw(Message::Binary(data.into()));
	}
	/// Send ping frame
	#[inline]
	pub fn ping(&mut self, message: &[u8]) {
	self.write_raw(Message::Ping(Bytes::copy_from_slice(message)));
	}
	/// Send pong frame
	#[inline]
	pub fn pong(&mut self, message: &[u8]) {
	self.write_raw(Message::Pong(Bytes::copy_from_slice(message)));
	}
	/// Send close frame
	#[inline]
	pub fn close(&mut self, reason: Option<CloseReason>) {
	self.write_raw(Message::Close(reason));
	}

The only part of close which seems to work as expected is when underlying connection is closed by client app and handled here:

actix-web/actix-web-actors/src/ws.rs

Lines 769 to 784 in ff8fd2f

	match Pin::new(&mut this.stream).poll_next(cx) {
	Poll::Ready(Some(Ok(chunk))) => {
	this.buf.extend_from_slice(&chunk[..]);
	}
	Poll::Ready(None) => {
	*this.closed = true;
	break;
	}
	Poll::Pending => break,
	Poll::Ready(Some(Err(e))) => {
	return Poll::Ready(Some(Err(ProtocolError::Io(io::Error::new(
	io::ErrorKind::Other,
	format!("{}", e),
	)))));
	}
	}

So maybe maintainers could kindly provide answers to questions I've raised here:

1. Is provided modifications to tests should be passed or not? (currently not passed)
2. If no, what is the proper way to gracefully close WebSocket connection by server side?