Struct tokio::net::TcpStream

pub struct TcpStream { /* fields omitted */ }

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.

Reading and writing to a TcpStream is usually done using the convenience methods found on the AsyncReadExt and AsyncWriteExt traits. Examples import these traits through the prelude.

Examples

use tokio::net::TcpStream;
use tokio::prelude::*;
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.

Implementations

impl TcpStream

pub async fn connect<A: ToSocketAddrs>(addr: A) -> Result<TcpStream>

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. Note that strings only implement this trait when the net feature is enabled, as strings may contain domain names that need to be resolved.

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.

Examples

use tokio::net::TcpStream;
use tokio::prelude::*;
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.

pub fn from_std(stream: TcpStream) -> Result<TcpStream>

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

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")?;
    let stream = TcpStream::from_std(std_stream)?;
    Ok(())
}

Panics

This function panics if thread-local runtime is not set.

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 function.

pub fn local_addr(&self) -> Result<SocketAddr>

Returns the local address that this stream is bound to.

Examples

use tokio::net::TcpStream;

let stream = TcpStream::connect("127.0.0.1:8080").await?;

println!("{:?}", stream.local_addr()?);

pub fn peer_addr(&self) -> Result<SocketAddr>

Returns the remote address that this stream is connected to.

Examples

use tokio::net::TcpStream;

let stream = TcpStream::connect("127.0.0.1:8080").await?;

println!("{:?}", stream.peer_addr()?);

pub fn poll_peek(
    &self,
    cx: &mut Context<'_>,
    buf: &mut [u8]
) -> Poll<Result<usize>>

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.

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

use tokio::io;
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];

    poll_fn(|cx| {
        stream.poll_peek(cx, &mut buf)
    }).await?;

    Ok(())
}

pub async fn peek<'_, '_>(&'_ self, buf: &'_ mut [u8]) -> Result<usize>

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

use tokio::net::TcpStream;
use tokio::prelude::*;
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.

pub fn shutdown(&self, how: Shutdown) -> Result<()>

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).

Examples

use tokio::net::TcpStream;
use std::error::Error;
use std::net::Shutdown;

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
    // Connect to a peer
    let stream = TcpStream::connect("127.0.0.1:8080").await?;

    // Shutdown the stream
    stream.shutdown(Shutdown::Write)?;

    Ok(())
}

pub fn nodelay(&self) -> Result<bool>

Gets the value of the TCP_NODELAY option on this socket.

For more information about this option, see set_nodelay.

Examples

use tokio::net::TcpStream;

let stream = TcpStream::connect("127.0.0.1:8080").await?;

println!("{:?}", stream.nodelay()?);

pub fn set_nodelay(&self, nodelay: bool) -> Result<()>

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

use tokio::net::TcpStream;

let stream = TcpStream::connect("127.0.0.1:8080").await?;

stream.set_nodelay(true)?;

pub fn ttl(&self) -> Result<u32>

Gets the value of the IP_TTL option for this socket.

For more information about this option, see set_ttl.

Examples

use tokio::net::TcpStream;

let stream = TcpStream::connect("127.0.0.1:8080").await?;

println!("{:?}", stream.ttl()?);

pub fn set_ttl(&self, ttl: u32) -> Result<()>

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

use tokio::net::TcpStream;

let stream = TcpStream::connect("127.0.0.1:8080").await?;

stream.set_ttl(123)?;

pub fn split<'a>(&'a mut self) -> (ReadHalf<'a>, WriteHalf<'a>)

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.

pub fn into_split(self) -> (OwnedReadHalf, OwnedWriteHalf)

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(Write) on the TcpStream.

Trait Implementations

impl AsRawFd for TcpStream

fn as_raw_fd(&self) -> RawFd

Extracts the raw file descriptor.

impl<'_> AsRef<TcpStream> for ReadHalf<'_>

fn as_ref(&self) -> &TcpStream

Performs the conversion.

impl<'_> AsRef<TcpStream> for WriteHalf<'_>

fn as_ref(&self) -> &TcpStream

Performs the conversion.

impl AsRef<TcpStream> for OwnedReadHalf

fn as_ref(&self) -> &TcpStream

Performs the conversion.

impl AsRef<TcpStream> for OwnedWriteHalf

fn as_ref(&self) -> &TcpStream

Performs the conversion.

impl AsyncRead for TcpStream

fn poll_read(
    self: Pin<&mut Self>,
    cx: &mut Context<'_>,
    buf: &mut ReadBuf<'_>
) -> Poll<Result<()>>

Attempts to read from the AsyncRead into buf.

impl AsyncWrite for TcpStream

fn poll_write(
    self: Pin<&mut Self>,
    cx: &mut Context<'_>,
    buf: &[u8]
) -> Poll<Result<usize>>

Attempt to write bytes from buf into the object.

fn poll_flush(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Result<()>>

Attempts to flush the object, ensuring that any buffered data reach their destination.

fn poll_shutdown(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Result<()>>

Initiates or attempts to shut down this writer, returning success when the I/O connection has completely shut down.

impl Debug for TcpStream

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl TryFrom<TcpStream> for TcpStream

type Error = Error

The type returned in the event of a conversion error.

fn try_from(stream: TcpStream) -> Result<Self, Self::Error>

Consumes stream, returning the tokio I/O object.

This is equivalent to TcpStream::from_std(stream).