cfg_not_wasi! {
use crate::future::poll_fn;
use crate::net::{to_socket_addrs, ToSocketAddrs};
use std::time::Duration;
}
use crate::io::{AsyncRead, AsyncWrite, Interest, PollEvented, ReadBuf, Ready};
use crate::net::tcp::split::{split, ReadHalf, WriteHalf};
use crate::net::tcp::split_owned::{split_owned, OwnedReadHalf, OwnedWriteHalf};
use std::convert::TryFrom;
use std::fmt;
use std::io;
use std::net::{Shutdown, SocketAddr};
use std::pin::Pin;
use std::task::{Context, Poll};
cfg_io_util! {
use bytes::BufMut;
}
cfg_net! {
/// A TCP stream between a local and a remote socket.
///
/// A TCP stream can either be created by connecting to an endpoint, via the
/// [`connect`] method, or by [accepting] a connection from a [listener]. A
/// TCP stream can also be created via the [`TcpSocket`] type.
///
/// Reading and writing to a `TcpStream` is usually done using the
/// convenience methods found on the [`AsyncReadExt`] and [`AsyncWriteExt`]
/// traits.
///
/// [`connect`]: method@TcpStream::connect
/// [accepting]: method@crate::net::TcpListener::accept
/// [listener]: struct@crate::net::TcpListener
/// [`TcpSocket`]: struct@crate::net::TcpSocket
/// [`AsyncReadExt`]: trait@crate::io::AsyncReadExt
/// [`AsyncWriteExt`]: trait@crate::io::AsyncWriteExt
///
/// # Examples
///
/// ```no_run
/// use tokio::net::TcpStream;
/// use tokio::io::AsyncWriteExt;
/// use std::error::Error;
///
/// #[tokio::main]
/// async fn main() -> Result<(), Box<dyn Error>> {
/// // Connect to a peer
/// let mut stream = TcpStream::connect("127.0.0.1:8080").await?;
///
/// // Write some data.
/// stream.write_all(b"hello world!").await?;
///
/// Ok(())
/// }
/// ```
///
/// The [`write_all`] method is defined on the [`AsyncWriteExt`] trait.
///
/// [`write_all`]: fn@crate::io::AsyncWriteExt::write_all
/// [`AsyncWriteExt`]: trait@crate::io::AsyncWriteExt
///
/// To shut down the stream in the write direction, you can call the
/// [`shutdown()`] method. This will cause the other peer to receive a read of
/// length 0, indicating that no more data will be sent. This only closes
/// the stream in one direction.
///
/// [`shutdown()`]: fn@crate::io::AsyncWriteExt::shutdown
pub struct TcpStream {
io: PollEvented<mio::net::TcpStream>,
}
}
impl TcpStream {
cfg_not_wasi! {
/// Opens a TCP connection to a remote host.
///
/// `addr` is an address of the remote host. Anything which implements the
/// [`ToSocketAddrs`] trait can be supplied as the address. If `addr`
/// yields multiple addresses, connect will be attempted with each of the
/// addresses until a connection is successful. If none of the addresses
/// result in a successful connection, the error returned from the last
/// connection attempt (the last address) is returned.
///
/// To configure the socket before connecting, you can use the [`TcpSocket`]
/// type.
///
/// [`ToSocketAddrs`]: trait@crate::net::ToSocketAddrs
/// [`TcpSocket`]: struct@crate::net::TcpSocket
///
/// # Examples
///
/// ```no_run
/// use tokio::net::TcpStream;
/// use tokio::io::AsyncWriteExt;
/// use std::error::Error;
///
/// #[tokio::main]
/// async fn main() -> Result<(), Box<dyn Error>> {
/// // Connect to a peer
/// let mut stream = TcpStream::connect("127.0.0.1:8080").await?;
///
/// // Write some data.
/// stream.write_all(b"hello world!").await?;
///
/// Ok(())
/// }
/// ```
///
/// The [`write_all`] method is defined on the [`AsyncWriteExt`] trait.
///
/// [`write_all`]: fn@crate::io::AsyncWriteExt::write_all
/// [`AsyncWriteExt`]: trait@crate::io::AsyncWriteExt
pub async fn connect<A: ToSocketAddrs>(addr: A) -> io::Result<TcpStream> {
let addrs = to_socket_addrs(addr).await?;
let mut last_err = None;
for addr in addrs {
match TcpStream::connect_addr(addr).await {
Ok(stream) => return Ok(stream),
Err(e) => last_err = Some(e),
}
}
Err(last_err.unwrap_or_else(|| {
io::Error::new(
io::ErrorKind::InvalidInput,
"could not resolve to any address",
)
}))
}
/// Establishes a connection to the specified `addr`.
async fn connect_addr(addr: SocketAddr) -> io::Result<TcpStream> {
let sys = mio::net::TcpStream::connect(addr)?;
TcpStream::connect_mio(sys).await
}
pub(crate) async fn connect_mio(sys: mio::net::TcpStream) -> io::Result<TcpStream> {
let stream = TcpStream::new(sys)?;
// Once we've connected, wait for the stream to be writable as
// that's when the actual connection has been initiated. Once we're
// writable we check for `take_socket_error` to see if the connect
// actually hit an error or not.
//
// If all that succeeded then we ship everything on up.
poll_fn(|cx| stream.io.registration().poll_write_ready(cx)).await?;
if let Some(e) = stream.io.take_error()? {
return Err(e);
}
Ok(stream)
}
}
pub(crate) fn new(connected: mio::net::TcpStream) -> io::Result<TcpStream> {
let io = PollEvented::new(connected)?;
Ok(TcpStream { io })
}
/// Creates new `TcpStream` from a `std::net::TcpStream`.
///
/// This function is intended to be used to wrap a TCP stream from the
/// standard library in the Tokio equivalent. The conversion assumes nothing
/// about the underlying stream; it is left up to the user to set it in
/// non-blocking mode.
///
/// # Examples
///
/// ```rust,no_run
/// use std::error::Error;
/// use tokio::net::TcpStream;
///
/// #[tokio::main]
/// async fn main() -> Result<(), Box<dyn Error>> {
/// let std_stream = std::net::TcpStream::connect("127.0.0.1:34254")?;
/// std_stream.set_nonblocking(true)?;
/// let stream = TcpStream::from_std(std_stream)?;
/// Ok(())
/// }
/// ```
///
/// # Panics
///
/// This function panics if it is not called from within a runtime with
/// IO enabled.
///
/// The runtime is usually set implicitly when this function is called
/// from a future driven by a tokio runtime, otherwise runtime can be set
/// explicitly with [`Runtime::enter`](crate::runtime::Runtime::enter) function.
#[track_caller]
#[cfg(not(target_os = "wasi"))]
pub fn from_std(stream: std::net::TcpStream) -> io::Result<TcpStream> {
let io = mio::net::TcpStream::from_std(stream);
let io = PollEvented::new(io)?;
Ok(TcpStream { io })
}
/// Turns a [`tokio::net::TcpStream`] into a [`std::net::TcpStream`].
///
/// The returned [`std::net::TcpStream`] will have nonblocking mode set as `true`.
/// Use [`set_nonblocking`] to change the blocking mode if needed.
///
/// # Examples
///
/// ```
/// use std::error::Error;
/// use std::io::Read;
/// use tokio::net::TcpListener;
/// # use tokio::net::TcpStream;
/// # use tokio::io::AsyncWriteExt;
///
/// #[tokio::main]
/// async fn main() -> Result<(), Box<dyn Error>> {
/// let mut data = [0u8; 12];
/// let listener = TcpListener::bind("127.0.0.1:34254").await?;
/// # let handle = tokio::spawn(async {
/// # let mut stream: TcpStream = TcpStream::connect("127.0.0.1:34254").await.unwrap();
/// # stream.write(b"Hello world!").await.unwrap();
/// # });
/// let (tokio_tcp_stream, _) = listener.accept().await?;
/// let mut std_tcp_stream = tokio_tcp_stream.into_std()?;
/// # handle.await.expect("The task being joined has panicked");
/// std_tcp_stream.set_nonblocking(false)?;
/// std_tcp_stream.read_exact(&mut data)?;
/// # assert_eq!(b"Hello world!", &data);
/// Ok(())
/// }
/// ```
/// [`tokio::net::TcpStream`]: TcpStream
/// [`std::net::TcpStream`]: std::net::TcpStream
/// [`set_nonblocking`]: fn@std::net::TcpStream::set_nonblocking
#[cfg(not(target_os = "wasi"))]
pub fn into_std(self) -> io::Result<std::net::TcpStream> {
#[cfg(unix)]
{
use std::os::unix::io::{FromRawFd, IntoRawFd};
self.io
.into_inner()
.map(|io| io.into_raw_fd())
.map(|raw_fd| unsafe { std::net::TcpStream::from_raw_fd(raw_fd) })
}
#[cfg(windows)]
{
use std::os::windows::io::{FromRawSocket, IntoRawSocket};
self.io
.into_inner()
.map(|io| io.into_raw_socket())
.map(|raw_socket| unsafe { std::net::TcpStream::from_raw_socket(raw_socket) })
}
#[cfg(tokio_wasi)]
{
use std::os::wasi::io::{FromRawFd, IntoRawFd};
self.io
.into_inner()
.map(|io| io.into_raw_fd())
.map(|raw_fd| unsafe { std::net::TcpStream::from_raw_fd(raw_fd) })
}
}
/// Returns the local address that this stream is bound to.
///
/// # Examples
///
/// ```no_run
/// use tokio::net::TcpStream;
///
/// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
/// let stream = TcpStream::connect("127.0.0.1:8080").await?;
///
/// println!("{:?}", stream.local_addr()?);
/// # Ok(())
/// # }
/// ```
pub fn local_addr(&self) -> io::Result<SocketAddr> {
self.io.local_addr()
}
/// Returns the value of the `SO_ERROR` option.
pub fn take_error(&self) -> io::Result<Option<io::Error>> {
self.io.take_error()
}
/// Returns the remote address that this stream is connected to.
///
/// # Examples
///
/// ```no_run
/// use tokio::net::TcpStream;
///
/// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
/// let stream = TcpStream::connect("127.0.0.1:8080").await?;
///
/// println!("{:?}", stream.peer_addr()?);
/// # Ok(())
/// # }
/// ```
pub fn peer_addr(&self) -> io::Result<SocketAddr> {
self.io.peer_addr()
}
/// Attempts to receive data on the socket, without removing that data from
/// the queue, registering the current task for wakeup if data is not yet
/// available.
///
/// Note that on multiple calls to `poll_peek`, `poll_read` or
/// `poll_read_ready`, only the `Waker` from the `Context` passed to the
/// most recent call is scheduled to receive a wakeup. (However,
/// `poll_write` retains a second, independent waker.)
///
/// # Return value
///
/// The function returns:
///
/// * `Poll::Pending` if data is not yet available.
/// * `Poll::Ready(Ok(n))` if data is available. `n` is the number of bytes peeked.
/// * `Poll::Ready(Err(e))` if an error is encountered.
///
/// # Errors
///
/// This function may encounter any standard I/O error except `WouldBlock`.
///
/// # Examples
///
/// ```no_run
/// use tokio::io::{self, ReadBuf};
/// use tokio::net::TcpStream;
///
/// use futures::future::poll_fn;
///
/// #[tokio::main]
/// async fn main() -> io::Result<()> {
/// let stream = TcpStream::connect("127.0.0.1:8000").await?;
/// let mut buf = [0; 10];
/// let mut buf = ReadBuf::new(&mut buf);
///
/// poll_fn(|cx| {
/// stream.poll_peek(cx, &mut buf)
/// }).await?;
///
/// Ok(())
/// }
/// ```
pub fn poll_peek(
&self,
cx: &mut Context<'_>,
buf: &mut ReadBuf<'_>,
) -> Poll<io::Result<usize>> {
loop {
let ev = ready!(self.io.registration().poll_read_ready(cx))?;
let b = unsafe {
&mut *(buf.unfilled_mut() as *mut [std::mem::MaybeUninit<u8>] as *mut [u8])
};
match self.io.peek(b) {
Ok(ret) => {
unsafe { buf.assume_init(ret) };
buf.advance(ret);
return Poll::Ready(Ok(ret));
}
Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
self.io.registration().clear_readiness(ev);
}
Err(e) => return Poll::Ready(Err(e)),
}
}
}
/// Waits for any of the requested ready states.
///
/// This function is usually paired with `try_read()` or `try_write()`. It
/// can be used to concurrently read / write to the same socket on a single
/// task without splitting the socket.
///
/// The function may complete without the socket being ready. This is a
/// false-positive and attempting an operation will return with
/// `io::ErrorKind::WouldBlock`. The function can also return with an empty
/// [`Ready`] set, so you should always check the returned value and possibly
/// wait again if the requested states are not set.
///
/// # Cancel safety
///
/// This method is cancel safe. Once a readiness event occurs, the method
/// will continue to return immediately until the readiness event is
/// consumed by an attempt to read or write that fails with `WouldBlock` or
/// `Poll::Pending`.
///
/// # Examples
///
/// Concurrently read and write to the stream on the same task without
/// splitting.
///
/// ```no_run
/// use tokio::io::Interest;
/// use tokio::net::TcpStream;
/// use std::error::Error;
/// use std::io;
///
/// #[tokio::main]
/// async fn main() -> Result<(), Box<dyn Error>> {
/// let stream = TcpStream::connect("127.0.0.1:8080").await?;
///
/// loop {
/// let ready = stream.ready(Interest::READABLE | Interest::WRITABLE).await?;
///
/// if ready.is_readable() {
/// let mut data = vec![0; 1024];
/// // Try to read data, this may still fail with `WouldBlock`
/// // if the readiness event is a false positive.
/// match stream.try_read(&mut data) {
/// Ok(n) => {
/// println!("read {} bytes", n);
/// }
/// Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
/// continue;
/// }
/// Err(e) => {
/// return Err(e.into());
/// }
/// }
///
/// }
///
/// if ready.is_writable() {
/// // Try to write data, this may still fail with `WouldBlock`
/// // if the readiness event is a false positive.
/// match stream.try_write(b"hello world") {
/// Ok(n) => {
/// println!("write {} bytes", n);
/// }
/// Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
/// continue
/// }
/// Err(e) => {
/// return Err(e.into());
/// }
/// }
/// }
/// }
/// }
/// ```
pub async fn ready(&self, interest: Interest) -> io::Result<Ready> {
let event = self.io.registration().readiness(interest).await?;
Ok(event.ready)
}
/// Waits for the socket to become readable.
///
/// This function is equivalent to `ready(Interest::READABLE)` and is usually
/// paired with `try_read()`.
///
/// # Cancel safety
///
/// This method is cancel safe. Once a readiness event occurs, the method
/// will continue to return immediately until the readiness event is
/// consumed by an attempt to read that fails with `WouldBlock` or
/// `Poll::Pending`.
///
/// # Examples
///
/// ```no_run
/// use tokio::net::TcpStream;
/// use std::error::Error;
/// use std::io;
///
/// #[tokio::main]
/// async fn main() -> Result<(), Box<dyn Error>> {
/// // Connect to a peer
/// let stream = TcpStream::connect("127.0.0.1:8080").await?;
///
/// let mut msg = vec![0; 1024];
///
/// loop {
/// // Wait for the socket to be readable
/// stream.readable().await?;
///
/// // Try to read data, this may still fail with `WouldBlock`
/// // if the readiness event is a false positive.
/// match stream.try_read(&mut msg) {
/// Ok(n) => {
/// msg.truncate(n);
/// break;
/// }
/// Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
/// continue;
/// }
/// Err(e) => {
/// return Err(e.into());
/// }
/// }
/// }
///
/// println!("GOT = {:?}", msg);
/// Ok(())
/// }
/// ```
pub async fn readable(&self) -> io::Result<()> {
self.ready(Interest::READABLE).await?;
Ok(())
}
/// Polls for read readiness.
///
/// If the tcp stream is not currently ready for reading, this method will
/// store a clone of the `Waker` from the provided `Context`. When the tcp
/// stream becomes ready for reading, `Waker::wake` will be called on the
/// waker.
///
/// Note that on multiple calls to `poll_read_ready`, `poll_read` or
/// `poll_peek`, only the `Waker` from the `Context` passed to the most
/// recent call is scheduled to receive a wakeup. (However,
/// `poll_write_ready` retains a second, independent waker.)
///
/// This function is intended for cases where creating and pinning a future
/// via [`readable`] is not feasible. Where possible, using [`readable`] is
/// preferred, as this supports polling from multiple tasks at once.
///
/// # Return value
///
/// The function returns:
///
/// * `Poll::Pending` if the tcp stream is not ready for reading.
/// * `Poll::Ready(Ok(()))` if the tcp stream is ready for reading.
/// * `Poll::Ready(Err(e))` if an error is encountered.
///
/// # Errors
///
/// This function may encounter any standard I/O error except `WouldBlock`.
///
/// [`readable`]: method@Self::readable
pub fn poll_read_ready(&self, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
self.io.registration().poll_read_ready(cx).map_ok(|_| ())
}
/// Tries to read data from the stream into the provided buffer, returning how
/// many bytes were read.
///
/// Receives any pending data from the socket but does not wait for new data
/// to arrive. On success, returns the number of bytes read. Because
/// `try_read()` is non-blocking, the buffer does not have to be stored by
/// the async task and can exist entirely on the stack.
///
/// Usually, [`readable()`] or [`ready()`] is used with this function.
///
/// [`readable()`]: TcpStream::readable()
/// [`ready()`]: TcpStream::ready()
///
/// # Return
///
/// If data is successfully read, `Ok(n)` is returned, where `n` is the
/// number of bytes read. If `n` is `0`, then it can indicate one of two scenarios:
///
/// 1. The stream's read half is closed and will no longer yield data.
/// 2. The specified buffer was 0 bytes in length.
///
/// If the stream is not ready to read data,
/// `Err(io::ErrorKind::WouldBlock)` is returned.
///
/// # Examples
///
/// ```no_run
/// use tokio::net::TcpStream;
/// use std::error::Error;
/// use std::io;
///
/// #[tokio::main]
/// async fn main() -> Result<(), Box<dyn Error>> {
/// // Connect to a peer
/// let stream = TcpStream::connect("127.0.0.1:8080").await?;
///
/// loop {
/// // Wait for the socket to be readable
/// stream.readable().await?;
///
/// // Creating the buffer **after** the `await` prevents it from
/// // being stored in the async task.
/// let mut buf = [0; 4096];
///
/// // Try to read data, this may still fail with `WouldBlock`
/// // if the readiness event is a false positive.
/// match stream.try_read(&mut buf) {
/// Ok(0) => break,
/// Ok(n) => {
/// println!("read {} bytes", n);
/// }
/// Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
/// continue;
/// }
/// Err(e) => {
/// return Err(e.into());
/// }
/// }
/// }
///
/// Ok(())
/// }
/// ```
pub fn try_read(&self, buf: &mut [u8]) -> io::Result<usize> {
use std::io::Read;
self.io
.registration()
.try_io(Interest::READABLE, || (&*self.io).read(buf))
}
/// Tries to read data from the stream into the provided buffers, returning
/// how many bytes were read.
///
/// Data is copied to fill each buffer in order, with the final buffer
/// written to possibly being only partially filled. This method behaves
/// equivalently to a single call to [`try_read()`] with concatenated
/// buffers.
///
/// Receives any pending data from the socket but does not wait for new data
/// to arrive. On success, returns the number of bytes read. Because
/// `try_read_vectored()` is non-blocking, the buffer does not have to be
/// stored by the async task and can exist entirely on the stack.
///
/// Usually, [`readable()`] or [`ready()`] is used with this function.
///
/// [`try_read()`]: TcpStream::try_read()
/// [`readable()`]: TcpStream::readable()
/// [`ready()`]: TcpStream::ready()
///
/// # Return
///
/// If data is successfully read, `Ok(n)` is returned, where `n` is the
/// number of bytes read. `Ok(0)` indicates the stream's read half is closed
/// and will no longer yield data. If the stream is not ready to read data
/// `Err(io::ErrorKind::WouldBlock)` is returned.
///
/// # Examples
///
/// ```no_run
/// use tokio::net::TcpStream;
/// use std::error::Error;
/// use std::io::{self, IoSliceMut};
///
/// #[tokio::main]
/// async fn main() -> Result<(), Box<dyn Error>> {
/// // Connect to a peer
/// let stream = TcpStream::connect("127.0.0.1:8080").await?;
///
/// loop {
/// // Wait for the socket to be readable
/// stream.readable().await?;
///
/// // Creating the buffer **after** the `await` prevents it from
/// // being stored in the async task.
/// let mut buf_a = [0; 512];
/// let mut buf_b = [0; 1024];
/// let mut bufs = [
/// IoSliceMut::new(&mut buf_a),
/// IoSliceMut::new(&mut buf_b),
/// ];
///
/// // Try to read data, this may still fail with `WouldBlock`
/// // if the readiness event is a false positive.
/// match stream.try_read_vectored(&mut bufs) {
/// Ok(0) => break,
/// Ok(n) => {
/// println!("read {} bytes", n);
/// }
/// Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
/// continue;
/// }
/// Err(e) => {
/// return Err(e.into());
/// }
/// }
/// }
///
/// Ok(())
/// }
/// ```
pub fn try_read_vectored(&self, bufs: &mut [io::IoSliceMut<'_>]) -> io::Result<usize> {
use std::io::Read;
self.io
.registration()
.try_io(Interest::READABLE, || (&*self.io).read_vectored(bufs))
}
cfg_io_util! {
/// Tries to read data from the stream into the provided buffer, advancing the
/// buffer's internal cursor, returning how many bytes were read.
///
/// Receives any pending data from the socket but does not wait for new data
/// to arrive. On success, returns the number of bytes read. Because
/// `try_read_buf()` is non-blocking, the buffer does not have to be stored by
/// the async task and can exist entirely on the stack.
///
/// Usually, [`readable()`] or [`ready()`] is used with this function.
///
/// [`readable()`]: TcpStream::readable()
/// [`ready()`]: TcpStream::ready()
///
/// # Return
///
/// If data is successfully read, `Ok(n)` is returned, where `n` is the
/// number of bytes read. `Ok(0)` indicates the stream's read half is closed
/// and will no longer yield data. If the stream is not ready to read data
/// `Err(io::ErrorKind::WouldBlock)` is returned.
///
/// # Examples
///
/// ```no_run
/// use tokio::net::TcpStream;
/// use std::error::Error;
/// use std::io;
///
/// #[tokio::main]
/// async fn main() -> Result<(), Box<dyn Error>> {
/// // Connect to a peer
/// let stream = TcpStream::connect("127.0.0.1:8080").await?;
///
/// loop {
/// // Wait for the socket to be readable
/// stream.readable().await?;
///
/// let mut buf = Vec::with_capacity(4096);
///
/// // Try to read data, this may still fail with `WouldBlock`
/// // if the readiness event is a false positive.
/// match stream.try_read_buf(&mut buf) {
/// Ok(0) => break,
/// Ok(n) => {
/// println!("read {} bytes", n);
/// }
/// Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
/// continue;
/// }
/// Err(e) => {
/// return Err(e.into());
/// }
/// }
/// }
///
/// Ok(())
/// }
/// ```
pub fn try_read_buf<B: BufMut>(&self, buf: &mut B) -> io::Result<usize> {
self.io.registration().try_io(Interest::READABLE, || {
use std::io::Read;
let dst = buf.chunk_mut();
let dst =
unsafe { &mut *(dst as *mut _ as *mut [std::mem::MaybeUninit<u8>] as *mut [u8]) };
// Safety: We trust `TcpStream::read` to have filled up `n` bytes in the
// buffer.
let n = (&*self.io).read(dst)?;
unsafe {
buf.advance_mut(n);
}
Ok(n)
})
}
}
/// Waits for the socket to become writable.
///
/// This function is equivalent to `ready(Interest::WRITABLE)` and is usually
/// paired with `try_write()`.
///
/// # Cancel safety
///
/// This method is cancel safe. Once a readiness event occurs, the method
/// will continue to return immediately until the readiness event is
/// consumed by an attempt to write that fails with `WouldBlock` or
/// `Poll::Pending`.
///
/// # Examples
///
/// ```no_run
/// use tokio::net::TcpStream;
/// use std::error::Error;
/// use std::io;
///
/// #[tokio::main]
/// async fn main() -> Result<(), Box<dyn Error>> {
/// // Connect to a peer
/// let stream = TcpStream::connect("127.0.0.1:8080").await?;
///
/// loop {
/// // Wait for the socket to be writable
/// stream.writable().await?;
///
/// // Try to write data, this may still fail with `WouldBlock`
/// // if the readiness event is a false positive.
/// match stream.try_write(b"hello world") {
/// Ok(n) => {
/// break;
/// }
/// Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
/// continue;
/// }
/// Err(e) => {
/// return Err(e.into());
/// }
/// }
/// }
///
/// Ok(())
/// }
/// ```
pub async fn writable(&self) -> io::Result<()> {
self.ready(Interest::WRITABLE).await?;
Ok(())
}
/// Polls for write readiness.
///
/// If the tcp stream is not currently ready for writing, this method will
/// store a clone of the `Waker` from the provided `Context`. When the tcp
/// stream becomes ready for writing, `Waker::wake` will be called on the
/// waker.
///
/// Note that on multiple calls to `poll_write_ready` or `poll_write`, only
/// the `Waker` from the `Context` passed to the most recent call is
/// scheduled to receive a wakeup. (However, `poll_read_ready` retains a
/// second, independent waker.)
///
/// This function is intended for cases where creating and pinning a future
/// via [`writable`] is not feasible. Where possible, using [`writable`] is
/// preferred, as this supports polling from multiple tasks at once.
///
/// # Return value
///
/// The function returns:
///
/// * `Poll::Pending` if the tcp stream is not ready for writing.
/// * `Poll::Ready(Ok(()))` if the tcp stream is ready for writing.
/// * `Poll::Ready(Err(e))` if an error is encountered.
///
/// # Errors
///
/// This function may encounter any standard I/O error except `WouldBlock`.
///
/// [`writable`]: method@Self::writable
pub fn poll_write_ready(&self, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
self.io.registration().poll_write_ready(cx).map_ok(|_| ())
}
/// Try to write a buffer to the stream, returning how many bytes were
/// written.
///
/// The function will attempt to write the entire contents of `buf`, but
/// only part of the buffer may be written.
///
/// This function is usually paired with `writable()`.
///
/// # Return
///
/// If data is successfully written, `Ok(n)` is returned, where `n` is the
/// number of bytes written. If the stream is not ready to write data,
/// `Err(io::ErrorKind::WouldBlock)` is returned.
///
/// # Examples
///
/// ```no_run
/// use tokio::net::TcpStream;
/// use std::error::Error;
/// use std::io;
///
/// #[tokio::main]
/// async fn main() -> Result<(), Box<dyn Error>> {
/// // Connect to a peer
/// let stream = TcpStream::connect("127.0.0.1:8080").await?;
///
/// loop {
/// // Wait for the socket to be writable
/// stream.writable().await?;
///
/// // Try to write data, this may still fail with `WouldBlock`
/// // if the readiness event is a false positive.
/// match stream.try_write(b"hello world") {
/// Ok(n) => {
/// break;
/// }
/// Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
/// continue;
/// }
/// Err(e) => {
/// return Err(e.into());
/// }
/// }
/// }
///
/// Ok(())
/// }
/// ```
pub fn try_write(&self, buf: &[u8]) -> io::Result<usize> {
use std::io::Write;
self.io
.registration()
.try_io(Interest::WRITABLE, || (&*self.io).write(buf))
}
/// Tries to write several buffers to the stream, returning how many bytes
/// were written.
///
/// Data is written from each buffer in order, with the final buffer read
/// from possible being only partially consumed. This method behaves
/// equivalently to a single call to [`try_write()`] with concatenated
/// buffers.
///
/// This function is usually paired with `writable()`.
///
/// [`try_write()`]: TcpStream::try_write()
///
/// # Return
///
/// If data is successfully written, `Ok(n)` is returned, where `n` is the
/// number of bytes written. If the stream is not ready to write data,
/// `Err(io::ErrorKind::WouldBlock)` is returned.
///
/// # Examples
///
/// ```no_run
/// use tokio::net::TcpStream;
/// use std::error::Error;
/// use std::io;
///
/// #[tokio::main]
/// async fn main() -> Result<(), Box<dyn Error>> {
/// // Connect to a peer
/// let stream = TcpStream::connect("127.0.0.1:8080").await?;
///
/// let bufs = [io::IoSlice::new(b"hello "), io::IoSlice::new(b"world")];
///
/// loop {
/// // Wait for the socket to be writable
/// stream.writable().await?;
///
/// // Try to write data, this may still fail with `WouldBlock`
/// // if the readiness event is a false positive.
/// match stream.try_write_vectored(&bufs) {
/// Ok(n) => {
/// break;
/// }
/// Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
/// continue;
/// }
/// Err(e) => {
/// return Err(e.into());
/// }
/// }
/// }
///
/// Ok(())
/// }
/// ```
pub fn try_write_vectored(&self, bufs: &[io::IoSlice<'_>]) -> io::Result<usize> {
use std::io::Write;
self.io
.registration()
.try_io(Interest::WRITABLE, || (&*self.io).write_vectored(bufs))
}
/// Tries to read or write from the socket using a user-provided IO operation.
///
/// If the socket is ready, the provided closure is called. The closure
/// should attempt to perform IO operation on the socket by manually
/// calling the appropriate syscall. If the operation fails because the
/// socket is not actually ready, then the closure should return a
/// `WouldBlock` error and the readiness flag is cleared. The return value
/// of the closure is then returned by `try_io`.
///
/// If the socket is not ready, then the closure is not called
/// and a `WouldBlock` error is returned.
///
/// The closure should only return a `WouldBlock` error if it has performed
/// an IO operation on the socket that failed due to the socket not being
/// ready. Returning a `WouldBlock` error in any other situation will
/// incorrectly clear the readiness flag, which can cause the socket to
/// behave incorrectly.
///
/// The closure should not perform the IO operation using any of the methods
/// defined on the Tokio `TcpStream` type, as this will mess with the
/// readiness flag and can cause the socket to behave incorrectly.
///
/// This method is not intended to be used with combined interests.
/// The closure should perform only one type of IO operation, so it should not
/// require more than one ready state. This method may panic or sleep forever
/// if it is called with a combined interest.
///
/// Usually, [`readable()`], [`writable()`] or [`ready()`] is used with this function.
///
/// [`readable()`]: TcpStream::readable()
/// [`writable()`]: TcpStream::writable()
/// [`ready()`]: TcpStream::ready()
pub fn try_io<R>(
&self,
interest: Interest,
f: impl FnOnce() -> io::Result<R>,
) -> io::Result<R> {
self.io
.registration()
.try_io(interest, || self.io.try_io(f))
}
/// Receives data on the socket from the remote address to which it is
/// connected, without removing that data from the queue. On success,
/// returns the number of bytes peeked.
///
/// Successive calls return the same data. This is accomplished by passing
/// `MSG_PEEK` as a flag to the underlying recv system call.
///
/// # Examples
///
/// ```no_run
/// use tokio::net::TcpStream;
/// use tokio::io::AsyncReadExt;
/// use std::error::Error;
///
/// #[tokio::main]
/// async fn main() -> Result<(), Box<dyn Error>> {
/// // Connect to a peer
/// let mut stream = TcpStream::connect("127.0.0.1:8080").await?;
///
/// let mut b1 = [0; 10];
/// let mut b2 = [0; 10];
///
/// // Peek at the data
/// let n = stream.peek(&mut b1).await?;
///
/// // Read the data
/// assert_eq!(n, stream.read(&mut b2[..n]).await?);
/// assert_eq!(&b1[..n], &b2[..n]);
///
/// Ok(())
/// }
/// ```
///
/// The [`read`] method is defined on the [`AsyncReadExt`] trait.
///
/// [`read`]: fn@crate::io::AsyncReadExt::read
/// [`AsyncReadExt`]: trait@crate::io::AsyncReadExt
pub async fn peek(&self, buf: &mut [u8]) -> io::Result<usize> {
self.io
.registration()
.async_io(Interest::READABLE, || self.io.peek(buf))
.await
}
/// Shuts down the read, write, or both halves of this connection.
///
/// This function will cause all pending and future I/O on the specified
/// portions to return immediately with an appropriate value (see the
/// documentation of `Shutdown`).
pub(super) fn shutdown_std(&self, how: Shutdown) -> io::Result<()> {
self.io.shutdown(how)
}
/// Gets the value of the `TCP_NODELAY` option on this socket.
///
/// For more information about this option, see [`set_nodelay`].
///
/// [`set_nodelay`]: TcpStream::set_nodelay
///
/// # Examples
///
/// ```no_run
/// use tokio::net::TcpStream;
///
/// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
/// let stream = TcpStream::connect("127.0.0.1:8080").await?;
///
/// println!("{:?}", stream.nodelay()?);
/// # Ok(())
/// # }
/// ```
pub fn nodelay(&self) -> io::Result<bool> {
self.io.nodelay()
}
/// Sets the value of the `TCP_NODELAY` option on this socket.
///
/// If set, this option disables the Nagle algorithm. This means that
/// segments are always sent as soon as possible, even if there is only a
/// small amount of data. When not set, data is buffered until there is a
/// sufficient amount to send out, thereby avoiding the frequent sending of
/// small packets.
///
/// # Examples
///
/// ```no_run
/// use tokio::net::TcpStream;
///
/// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
/// let stream = TcpStream::connect("127.0.0.1:8080").await?;
///
/// stream.set_nodelay(true)?;
/// # Ok(())
/// # }
/// ```
pub fn set_nodelay(&self, nodelay: bool) -> io::Result<()> {
self.io.set_nodelay(nodelay)
}
cfg_not_wasi! {
/// Reads the linger duration for this socket by getting the `SO_LINGER`
/// option.
///
/// For more information about this option, see [`set_linger`].
///
/// [`set_linger`]: TcpStream::set_linger
///
/// # Examples
///
/// ```no_run
/// use tokio::net::TcpStream;
///
/// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
/// let stream = TcpStream::connect("127.0.0.1:8080").await?;
///
/// println!("{:?}", stream.linger()?);
/// # Ok(())
/// # }
/// ```
#[cfg(not(target_os = "wasi"))]
pub fn linger(&self) -> io::Result<Option<Duration>> {
socket2::SockRef::from(self).linger()
}
/// Sets the linger duration of this socket by setting the SO_LINGER option.
///
/// This option controls the action taken when a stream has unsent messages and the stream is
/// closed. If SO_LINGER is set, the system shall block the process until it can transmit the
/// data or until the time expires.
///
/// If SO_LINGER is not specified, and the stream is closed, the system handles the call in a
/// way that allows the process to continue as quickly as possible.
///
/// # Examples
///
/// ```no_run
/// use tokio::net::TcpStream;
///
/// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
/// let stream = TcpStream::connect("127.0.0.1:8080").await?;
///
/// stream.set_linger(None)?;
/// # Ok(())
/// # }
/// ```
#[cfg(not(target_os = "wasi"))]
pub fn set_linger(&self, dur: Option<Duration>) -> io::Result<()> {
socket2::SockRef::from(self).set_linger(dur)
}
}
/// Gets the value of the `IP_TTL` option for this socket.
///
/// For more information about this option, see [`set_ttl`].
///
/// [`set_ttl`]: TcpStream::set_ttl
///
/// # Examples
///
/// ```no_run
/// use tokio::net::TcpStream;
///
/// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
/// let stream = TcpStream::connect("127.0.0.1:8080").await?;
///
/// println!("{:?}", stream.ttl()?);
/// # Ok(())
/// # }
/// ```
pub fn ttl(&self) -> io::Result<u32> {
self.io.ttl()
}
/// Sets the value for the `IP_TTL` option on this socket.
///
/// This value sets the time-to-live field that is used in every packet sent
/// from this socket.
///
/// # Examples
///
/// ```no_run
/// use tokio::net::TcpStream;
///
/// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
/// let stream = TcpStream::connect("127.0.0.1:8080").await?;
///
/// stream.set_ttl(123)?;
/// # Ok(())
/// # }
/// ```
pub fn set_ttl(&self, ttl: u32) -> io::Result<()> {
self.io.set_ttl(ttl)
}
// These lifetime markers also appear in the generated documentation, and make
// it more clear that this is a *borrowed* split.
#[allow(clippy::needless_lifetimes)]
/// Splits a `TcpStream` into a read half and a write half, which can be used
/// to read and write the stream concurrently.
///
/// This method is more efficient than [`into_split`], but the halves cannot be
/// moved into independently spawned tasks.
///
/// [`into_split`]: TcpStream::into_split()
pub fn split<'a>(&'a mut self) -> (ReadHalf<'a>, WriteHalf<'a>) {
split(self)
}
/// Splits a `TcpStream` into a read half and a write half, which can be used
/// to read and write the stream concurrently.
///
/// Unlike [`split`], the owned halves can be moved to separate tasks, however
/// this comes at the cost of a heap allocation.
///
/// **Note:** Dropping the write half will shut down the write half of the TCP
/// stream. This is equivalent to calling [`shutdown()`] on the `TcpStream`.
///
/// [`split`]: TcpStream::split()
/// [`shutdown()`]: fn@crate::io::AsyncWriteExt::shutdown
pub fn into_split(self) -> (OwnedReadHalf, OwnedWriteHalf) {
split_owned(self)
}
// == Poll IO functions that takes `&self` ==
//
// To read or write without mutable access to the `UnixStream`, combine the
// `poll_read_ready` or `poll_write_ready` methods with the `try_read` or
// `try_write` methods.
pub(crate) fn poll_read_priv(
&self,
cx: &mut Context<'_>,
buf: &mut ReadBuf<'_>,
) -> Poll<io::Result<()>> {
// Safety: `TcpStream::read` correctly handles reads into uninitialized memory
unsafe { self.io.poll_read(cx, buf) }
}
pub(super) fn poll_write_priv(
&self,
cx: &mut Context<'_>,
buf: &[u8],
) -> Poll<io::Result<usize>> {
self.io.poll_write(cx, buf)
}
pub(super) fn poll_write_vectored_priv(
&self,
cx: &mut Context<'_>,
bufs: &[io::IoSlice<'_>],
) -> Poll<io::Result<usize>> {
self.io.poll_write_vectored(cx, bufs)
}
}
#[cfg(not(target_os = "wasi"))]
impl TryFrom<std::net::TcpStream> for TcpStream {
type Error = io::Error;
/// Consumes stream, returning the tokio I/O object.
///
/// This is equivalent to
/// [`TcpStream::from_std(stream)`](TcpStream::from_std).
fn try_from(stream: std::net::TcpStream) -> Result<Self, Self::Error> {
Self::from_std(stream)
}
}
// ===== impl Read / Write =====
impl AsyncRead for TcpStream {
fn poll_read(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &mut ReadBuf<'_>,
) -> Poll<io::Result<()>> {
self.poll_read_priv(cx, buf)
}
}
impl AsyncWrite for TcpStream {
fn poll_write(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &[u8],
) -> Poll<io::Result<usize>> {
self.poll_write_priv(cx, buf)
}
fn poll_write_vectored(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
bufs: &[io::IoSlice<'_>],
) -> Poll<io::Result<usize>> {
self.poll_write_vectored_priv(cx, bufs)
}
fn is_write_vectored(&self) -> bool {
true
}
#[inline]
fn poll_flush(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<io::Result<()>> {
// tcp flush is a no-op
Poll::Ready(Ok(()))
}
fn poll_shutdown(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<io::Result<()>> {
self.shutdown_std(std::net::Shutdown::Write)?;
Poll::Ready(Ok(()))
}
}
impl fmt::Debug for TcpStream {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.io.fmt(f)
}
}
#[cfg(unix)]
mod sys {
use super::TcpStream;
use std::os::unix::prelude::*;
impl AsRawFd for TcpStream {
fn as_raw_fd(&self) -> RawFd {
self.io.as_raw_fd()
}
}
}
#[cfg(windows)]
mod sys {
use super::TcpStream;
use std::os::windows::prelude::*;
impl AsRawSocket for TcpStream {
fn as_raw_socket(&self) -> RawSocket {
self.io.as_raw_socket()
}
}
}
#[cfg(all(tokio_unstable, tokio_wasi))]
mod sys {
use super::TcpStream;
use std::os::wasi::prelude::*;
impl AsRawFd for TcpStream {
fn as_raw_fd(&self) -> RawFd {
self.io.as_raw_fd()
}
}
}