Bare-metal Rust on Zynq-7000
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//! async TCP interface
//!
//! TODO: implement futures AsyncRead/AsyncWrite/Stream/Sink interfaces
use core::{
future::Future,
pin::Pin,
task::{Context, Poll},
};
use alloc::vec::Vec;
use smoltcp::{
Error, Result,
socket::{
SocketHandle, SocketRef,
TcpSocketBuffer, TcpSocket, TcpState,
},
time::Duration,
};
use crate::task;
use super::Sockets;
/// References a smoltcp TcpSocket
pub struct TcpStream {
handle: SocketHandle,
}
/// Wait while letting `$f()` poll a stream's socket
macro_rules! poll_stream {
($stream: expr, $output: ty, $f: expr) => (async {
struct Adhoc<'a> {
stream: &'a TcpStream,
}
impl<'a> Future for Adhoc<'a> {
type Output = $output;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
let result = self.stream.with_socket($f);
if !result.is_ready() {
Sockets::register_waker(cx.waker().clone());
}
result
}
}
Adhoc { stream: $stream }.await
})
}
impl TcpStream {
/// Allocates sockets and its buffers, registers it in the
/// SocketSet.
///
/// Not `pub` as the result can not yet be used. Use `listen()` or
/// `connect()` to obtain a valid TcpStream.
fn new(rx_bufsize: usize, tx_bufsize: usize) -> Self {
fn uninit_vec<T>(size: usize) -> Vec<T> {
let mut result = Vec::with_capacity(size);
unsafe {
result.set_len(size);
}
result
}
let rx_buffer = TcpSocketBuffer::new(uninit_vec(rx_bufsize));
let tx_buffer = TcpSocketBuffer::new(uninit_vec(tx_bufsize));
let socket = TcpSocket::new(rx_buffer, tx_buffer);
let handle = Sockets::instance().sockets.borrow_mut()
.add(socket);
TcpStream { handle }
}
/// Operate on the referenced TCP socket
fn with_socket<F, R>(&self, f: F) -> R
where
F: FnOnce(SocketRef<TcpSocket>) -> R,
{
let mut sockets = Sockets::instance().sockets.borrow_mut();
let socket_ref = sockets.get::<TcpSocket>(self.handle);
f(socket_ref)
}
/// Listen for the next incoming connection on a TCP
/// port. Succeeds on connection attempt.
///
/// Calling this serially in a loop will cause slow/botched
/// connection attempts stall any more new connections. Use
/// `listen()` with a backlog instead.
pub async fn accept(port: u16, rx_bufsize: usize, tx_bufsize: usize) -> Result<Self> {
let stream = Self::new(rx_bufsize, tx_bufsize);
// Set socket to listen
stream.with_socket(|mut s| s.listen(port))?;
// Wait for a connection
poll_stream!(&stream, (), |socket| {
if socket.state() != TcpState::Listen {
Poll::Ready(())
} else {
Poll::Pending
}
}).await;
Ok(stream)
}
/// Probe the receive buffer
///
/// Your callback will only be called when there is some data available,
/// and it must consume at least one byte. It returns a tuple with the
/// number of bytes it consumed, and a user-defined return value of type R.
pub async fn recv<F, R>(&self, f: F) -> Result<R>
where
F: Fn(&[u8]) -> (usize, R),
{
struct Recv<'a, F: FnOnce(&[u8]) -> (usize, R), R> {
stream: &'a TcpStream,
f: F,
}
impl<'a, F: Fn(&[u8]) -> (usize, R), R> Future for Recv<'a, F, R> {
type Output = Result<R>;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
let result = self.stream.with_socket(|mut socket| {
if socket_is_handhshaking(&socket) {
return Ok(Poll::Pending);
}
socket.recv(|buf| {
if buf.len() > 0 {
let (amount, result) = (self.f)(buf);
assert!(amount > 0);
(amount, Poll::Ready(Ok(result)))
} else {
(0, Poll::Pending)
}
})
});
match result {
Ok(Poll::Pending) => {
Sockets::register_waker(cx.waker().clone());
Poll::Pending
}
Ok(result) => {
result
}
Err(e) =>
Poll::Ready(Err(e)),
}
}
}
Recv {
stream: self,
f,
}.await
}
/// Wait until there is any space in the socket's send queue
async fn wait_can_send(&self) -> Result<()> {
poll_stream!(self, Result<()>, |socket| {
if socket_is_handhshaking(&socket) {
Poll::Pending
} else if socket.can_send() {
Poll::Ready(Ok(()))
} else if ! socket.may_send() {
Poll::Ready(Err(Error::Truncated))
} else {
Poll::Pending
}
}).await
}
/// Yields to wait for more buffer space
pub async fn send<I: IntoIterator<Item = u8>>(&self, data: I) -> Result<()> {
let mut data = data.into_iter();
let mut done = false;
while !done {
self.wait_can_send().await?;
self.with_socket(|mut socket| {
socket.send(|buf| {
for i in 0..buf.len() {
if let Some(byte) = data.next() {
buf[i] = byte;
} else {
done = true;
return (i, ())
}
}
(buf.len(), ())
})
})?;
}
Ok(())
}
/// Yields to wait for more buffer space
pub async fn send_slice(&self, mut data: &'_ [u8]) -> Result<()> {
while data.len() > 0 {
self.wait_can_send().await?;
data = self.with_socket(|mut socket| {
socket.send(|buf| {
let len = buf.len().min(data.len());
buf[..len].copy_from_slice(&data[..len]);
data = &data[len..];
(len, data)
})
})?;
}
Ok(())
}
/// Wait for all queued data to be sent and ACKed
///
/// **Warning:** this may not work as immediately as expected! The
/// other side may wait until it sends packets to you for
/// piggybacking the ACKs.
pub async fn flush(&self) -> Result<()> {
poll_stream!(self, Result<()>, |socket| {
if socket_is_handhshaking(&socket) {
Poll::Pending
} else if socket.may_send() && socket.send_queue() > 0 {
Poll::Pending
} else if socket.may_send() {
Poll::Ready(Ok(()))
} else {
Poll::Ready(Err(Error::Truncated))
}
}).await
}
/// Close the transmit half of the connection
pub async fn close(&self) {
self.with_socket(|mut socket| socket.close());
// Yield for one iface.poll() to send the packet
task::r#yield().await;
}
/// Destroy the socket, sending the RST
pub async fn abort(self) {
self.with_socket(|mut socket| socket.abort());
// Yield for one iface.poll() to send the packet
task::r#yield().await;
}
pub fn keep_alive(&self) -> Option<Duration> {
self.with_socket(|socket| socket.keep_alive())
}
pub fn set_keep_alive(&mut self, interval: Option<Duration>) {
self.with_socket(|mut socket| socket.set_keep_alive(interval));
}
pub fn timeout(&self) -> Option<Duration> {
self.with_socket(|socket| socket.timeout())
}
pub fn set_timeout(&mut self, duration: Option<Duration>) {
self.with_socket(|mut socket| socket.set_timeout(duration));
}
pub fn ack_delay(&self) -> Option<Duration> {
self.with_socket(|socket| socket.ack_delay())
}
pub fn set_ack_delay(&mut self, duration: Option<Duration>) {
self.with_socket(|mut socket| socket.set_ack_delay(duration));
}
}
impl Drop for TcpStream {
/// Free item in the socket set, which leads to deallocation of
/// the rx/tx buffers associated with this socket.
fn drop(&mut self) {
Sockets::instance().sockets.borrow_mut()
.remove(self.handle);
}
}
fn socket_is_handhshaking(socket: &SocketRef<TcpSocket>) -> bool {
match socket.state() {
TcpState::SynSent | TcpState::SynReceived =>
true,
_ =>
false,
}
}