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net: Make flush() wait for RST packets from abort()

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Add docs to note that dropping a TcpSocket early will
prevent the .abort() RST from being sent.
This commit is contained in:
Matt Johnston 2023-05-25 20:07:56 +08:00
parent d55b9bc6e2
commit b20427b2ec
1 changed files with 11 additions and 3 deletions
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14
embassy-net/src/tcp.rs
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@ -95,7 +95,8 @@ impl<'a> TcpWriter<'a> {
/// Flushes the written data to the socket. /// Flushes the written data to the socket.
/// ///
/// This waits until all data has been sent, and ACKed by the remote host. /// This waits until all data has been sent, and ACKed by the remote host. For a connection
/// closed with [`abort()`](TcpSocket::abort) it will wait for the TCP RST packet to be sent.
pub async fn flush(&mut self) -> Result<(), Error> { pub async fn flush(&mut self) -> Result<(), Error> {
self.io.flush().await self.io.flush().await
} }
@ -198,7 +199,8 @@ impl<'a> TcpSocket<'a> {
/// Flushes the written data to the socket. /// Flushes the written data to the socket.
/// ///
/// This waits until all data has been sent, and ACKed by the remote host. /// This waits until all data has been sent, and ACKed by the remote host. For a connection
/// closed with [`abort()`](TcpSocket::abort) it will wait for the TCP RST packet to be sent.
pub async fn flush(&mut self) -> Result<(), Error> { pub async fn flush(&mut self) -> Result<(), Error> {
self.io.flush().await self.io.flush().await
} }
@ -262,6 +264,11 @@ impl<'a> TcpSocket<'a> {
/// ///
/// This instantly closes both the read and write halves of the socket. Any pending data /// This instantly closes both the read and write halves of the socket. Any pending data
/// that has not been sent will be lost. /// that has not been sent will be lost.
///
/// Note that the TCP RST packet is not sent immediately - if the `TcpSocket` is dropped too soon
/// the remote host may not know the connection has been closed.
/// `abort()` callers should wait for a [`flush()`](TcpSocket::flush) call to complete before
/// dropping or reusing the socket.
pub fn abort(&mut self) { pub fn abort(&mut self) {
self.io.with_mut(|s, _| s.abort()) self.io.with_mut(|s, _| s.abort())
} }
@ -347,9 +354,10 @@ impl<'d> TcpIo<'d> {
async fn flush(&mut self) -> Result<(), Error> { async fn flush(&mut self) -> Result<(), Error> {
poll_fn(move |cx| { poll_fn(move |cx| {
self.with_mut(|s, _| { self.with_mut(|s, _| {
let waiting_close = s.state() == tcp::State::Closed && s.remote_endpoint().is_some();
// If there are outstanding send operations, register for wake up and wait // If there are outstanding send operations, register for wake up and wait
// smoltcp issues wake-ups when octets are dequeued from the send buffer // smoltcp issues wake-ups when octets are dequeued from the send buffer
if s.send_queue() > 0 { if s.send_queue() > 0 || waiting_close {
s.register_send_waker(cx.waker()); s.register_send_waker(cx.waker());
Poll::Pending Poll::Pending
// No outstanding sends, socket is flushed // No outstanding sends, socket is flushed