Struct std::net::TcpListener

pub struct TcpListener(_);

A TCP socket server, listening for connections.

After creating a TcpListener by binding it to a socket address, it listens for incoming TCP connections. These can be accepted by calling accept or by iterating over the Incoming iterator returned by incoming.

The socket will be closed when the value is dropped.

The Transmission Control Protocol is specified in IETF RFC 793.

Examples

use std::net::{TcpListener, TcpStream};

fn handle_client(stream: TcpStream) {
    // ...
}

fn main() -> io::Result<()> {
    let listener = TcpListener::bind("127.0.0.1:80")?;

    // accept connections and process them serially
    for stream in listener.incoming() {
        handle_client(stream?);
    }
    Ok(())
}

Methods

impl TcpListener

pub fn bind<A: ToSocketAddrs>(addr: A) -> Result<TcpListener>

Creates a new TcpListener which will be bound to the specified address.

The returned listener is ready for accepting connections.

Binding with a port number of 0 will request that the OS assigns a port to this listener. The port allocated can be queried via the local_addr method.

The address type can be any implementor of ToSocketAddrs trait. See its documentation for concrete examples.

If addr yields multiple addresses, bind will be attempted with each of the addresses until one succeeds and returns the listener. If none of the addresses succeed in creating a listener, the error returned from the last attempt (the last address) is returned.

Examples

Creates a TCP listener bound to 127.0.0.1:80:

use std::net::TcpListener;

let listener = TcpListener::bind("127.0.0.1:80").unwrap();

Creates a TCP listener bound to 127.0.0.1:80. If that fails, create a TCP listener bound to 127.0.0.1:443:

use std::net::{SocketAddr, TcpListener};

let addrs = [
    SocketAddr::from(([127, 0, 0, 1], 80)),
    SocketAddr::from(([127, 0, 0, 1], 443)),
];
let listener = TcpListener::bind(&addrs[..]).unwrap();

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

Returns the local socket address of this listener.

Examples

use std::net::{Ipv4Addr, SocketAddr, SocketAddrV4, TcpListener};

let listener = TcpListener::bind("127.0.0.1:8080").unwrap();
assert_eq!(listener.local_addr().unwrap(),
           SocketAddr::V4(SocketAddrV4::new(Ipv4Addr::new(127, 0, 0, 1), 8080)));

pub fn try_clone(&self) -> Result<TcpListener>

Creates a new independently owned handle to the underlying socket.

The returned TcpListener is a reference to the same socket that this object references. Both handles can be used to accept incoming connections and options set on one listener will affect the other.

Examples

use std::net::TcpListener;

let listener = TcpListener::bind("127.0.0.1:8080").unwrap();
let listener_clone = listener.try_clone().unwrap();

pub fn accept(&self) -> Result<(TcpStream, SocketAddr)>

Accept a new incoming connection from this listener.

This function will block the calling thread until a new TCP connection is established. When established, the corresponding TcpStream and the remote peer's address will be returned.

Examples

use std::net::TcpListener;

let listener = TcpListener::bind("127.0.0.1:8080").unwrap();
match listener.accept() {
    Ok((_socket, addr)) => println!("new client: {:?}", addr),
    Err(e) => println!("couldn't get client: {:?}", e),
}

Important traits for Incoming<'a>

impl<'a> Iterator for Incoming<'a> type Item = Result<TcpStream>;

pub fn incoming(&self) -> Incoming

Returns an iterator over the connections being received on this listener.

The returned iterator will never return None and will also not yield the peer's SocketAddr structure. Iterating over it is equivalent to calling accept in a loop.

Examples

use std::net::TcpListener;

let listener = TcpListener::bind("127.0.0.1:80").unwrap();

for stream in listener.incoming() {
    match stream {
        Ok(stream) => {
            println!("new client!");
        }
        Err(e) => { /* connection failed */ }
    }
}

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 std::net::TcpListener;

let listener = TcpListener::bind("127.0.0.1:80").unwrap();
listener.set_ttl(100).expect("could not set TTL");

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 std::net::TcpListener;

let listener = TcpListener::bind("127.0.0.1:80").unwrap();
listener.set_ttl(100).expect("could not set TTL");
assert_eq!(listener.ttl().unwrap_or(0), 100);

pub fn set_only_v6(&self, only_v6: bool) -> Result<()>

Deprecated since 1.16.0:

this option can only be set before the socket is bound

pub fn only_v6(&self) -> Result<bool>

Deprecated since 1.16.0:

this option can only be set before the socket is bound

pub fn take_error(&self) -> Result<Option<Error>>

Gets the value of the SO_ERROR option on this socket.

This will retrieve the stored error in the underlying socket, clearing the field in the process. This can be useful for checking errors between calls.

Examples

use std::net::TcpListener;

let listener = TcpListener::bind("127.0.0.1:80").unwrap();
listener.take_error().expect("No error was expected");

pub fn set_nonblocking(&self, nonblocking: bool) -> Result<()>

Moves this TCP stream into or out of nonblocking mode.

This will result in the accept operation becoming nonblocking, i.e., immediately returning from their calls. If the IO operation is successful, Ok is returned and no further action is required. If the IO operation could not be completed and needs to be retried, an error with kind io::ErrorKind::WouldBlock is returned.

On Unix platforms, calling this method corresponds to calling fcntl FIONBIO. On Windows calling this method corresponds to calling ioctlsocket FIONBIO.

Examples

Bind a TCP listener to an address, listen for connections, and read bytes in nonblocking mode:

use std::io;
use std::net::TcpListener;

let listener = TcpListener::bind("127.0.0.1:7878").unwrap();
listener.set_nonblocking(true).expect("Cannot set non-blocking");

for stream in listener.incoming() {
    match stream {
        Ok(s) => {
            // do something with the TcpStream
            handle_connection(s);
        }
        Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
            // wait until network socket is ready, typically implemented
            // via platform-specific APIs such as epoll or IOCP
            wait_for_fd();
            continue;
        }
        Err(e) => panic!("encountered IO error: {}", e),
    }
}

Trait Implementations

impl AsRawFd for TcpListener

fn as_raw_fd(&self) -> RawFd

This is supported on Unix only.

Extracts the raw file descriptor.

impl FromRawFd for TcpListener

unsafe fn from_raw_fd(fd: RawFd) -> TcpListener

This is supported on Unix only.

Constructs a new instance of Self from the given raw file descriptor.

impl IntoRawFd for TcpListener

fn into_raw_fd(self) -> RawFd

This is supported on Unix only.

Consumes this object, returning the raw underlying file descriptor.

impl AsRawSocket for TcpListener

fn as_raw_socket(&self) -> RawSocket

This is supported on Windows only.

Extracts the underlying raw socket from this object.

impl FromRawSocket for TcpListener

unsafe fn from_raw_socket(sock: RawSocket) -> TcpListener

This is supported on Windows only.

Creates a new I/O object from the given raw socket.

impl IntoRawSocket for TcpListener

fn into_raw_socket(self) -> RawSocket

This is supported on Windows only.

Consumes this object, returning the raw underlying socket.

impl Debug for TcpListener

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

Formats the value using the given formatter.