pub struct TcpListener { /* private fields */ }
Expand description
A TCP socket server, listening for connections.
You can accept a new connection by using the accept
method.
A TcpListener
can be turned into a Stream
with TcpListenerStream
.
§Errors
Note that accepting a connection can lead to various errors and not all of them are necessarily fatal ‒ for example having too many open file descriptors or the other side closing the connection while it waits in an accept queue. These would terminate the stream if not handled in any way.
§Examples
Using accept
:
use tokio::net::TcpListener;
use std::io;
async fn process_socket<T>(socket: T) {
// do work with socket here
}
#[tokio::main]
async fn main() -> io::Result<()> {
let listener = TcpListener::bind("127.0.0.1:8080").await?;
loop {
let (socket, _) = listener.accept().await?;
process_socket(socket).await;
}
}
Implementations§
Source§impl TcpListener
impl TcpListener
Sourcepub async fn bind<A: ToSocketAddrs>(addr: A) -> Result<TcpListener>
pub async 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 the ToSocketAddrs
trait.
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.
This function sets the SO_REUSEADDR
option on the socket.
To configure the socket before binding, you can use the TcpSocket
type.
§Examples
use tokio::net::TcpListener;
use std::io;
#[tokio::main]
async fn main() -> io::Result<()> {
let listener = TcpListener::bind("127.0.0.1:2345").await?;
// use the listener
Ok(())
}
Sourcepub async fn accept(&self) -> Result<(TcpStream, SocketAddr)>
pub async fn accept(&self) -> Result<(TcpStream, SocketAddr)>
Accepts a new incoming connection from this listener.
This function will yield once a new TCP connection is established. When
established, the corresponding TcpStream
and the remote peer’s
address will be returned.
§Cancel safety
This method is cancel safe. If the method is used as the event in a
tokio::select!
statement and some other branch
completes first, then it is guaranteed that no new connections were
accepted by this method.
§Examples
use tokio::net::TcpListener;
use std::io;
#[tokio::main]
async fn main() -> io::Result<()> {
let listener = TcpListener::bind("127.0.0.1:8080").await?;
match listener.accept().await {
Ok((_socket, addr)) => println!("new client: {:?}", addr),
Err(e) => println!("couldn't get client: {:?}", e),
}
Ok(())
}
Sourcepub fn poll_accept(
&self,
cx: &mut Context<'_>,
) -> Poll<Result<(TcpStream, SocketAddr)>>
pub fn poll_accept( &self, cx: &mut Context<'_>, ) -> Poll<Result<(TcpStream, SocketAddr)>>
Polls to accept a new incoming connection to this listener.
If there is no connection to accept, Poll::Pending
is returned and the
current task will be notified by a waker. Note that on multiple calls
to poll_accept
, only the Waker
from the Context
passed to the most
recent call is scheduled to receive a wakeup.
Sourcepub fn from_std(listener: TcpListener) -> Result<TcpListener>
pub fn from_std(listener: TcpListener) -> Result<TcpListener>
Creates new TcpListener
from a std::net::TcpListener
.
This function is intended to be used to wrap a TCP listener from the standard library in the Tokio equivalent.
This API is typically paired with the socket2
crate and the Socket
type to build up and customize a listener before it’s shipped off to the
backing event loop. This allows configuration of options like
SO_REUSEPORT
, binding to multiple addresses, etc.
§Notes
The caller is responsible for ensuring that the listener is in
non-blocking mode. Otherwise all I/O operations on the listener
will block the thread, which will cause unexpected behavior.
Non-blocking mode can be set using set_nonblocking
.
§Examples
use std::error::Error;
use tokio::net::TcpListener;
#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
let std_listener = std::net::TcpListener::bind("127.0.0.1:0")?;
std_listener.set_nonblocking(true)?;
let listener = TcpListener::from_std(std_listener)?;
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
function.
Sourcepub fn into_std(self) -> Result<TcpListener>
pub fn into_std(self) -> Result<TcpListener>
Turns a tokio::net::TcpListener
into a std::net::TcpListener
.
The returned std::net::TcpListener
will have nonblocking mode set as
true
. Use set_nonblocking
to change the blocking mode if needed.
§Examples
use std::error::Error;
#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
let tokio_listener = tokio::net::TcpListener::bind("127.0.0.1:0").await?;
let std_listener = tokio_listener.into_std()?;
std_listener.set_nonblocking(false)?;
Ok(())
}
Sourcepub fn local_addr(&self) -> Result<SocketAddr>
pub fn local_addr(&self) -> Result<SocketAddr>
Returns the local address that this listener is bound to.
This can be useful, for example, when binding to port 0 to figure out which port was actually bound.
§Examples
use tokio::net::TcpListener;
use std::io;
use std::net::{Ipv4Addr, SocketAddr, SocketAddrV4};
#[tokio::main]
async fn main() -> io::Result<()> {
let listener = TcpListener::bind("127.0.0.1:8080").await?;
assert_eq!(listener.local_addr()?,
SocketAddr::V4(SocketAddrV4::new(Ipv4Addr::new(127, 0, 0, 1), 8080)));
Ok(())
}
Sourcepub fn ttl(&self) -> Result<u32>
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::TcpListener;
use std::io;
#[tokio::main]
async fn main() -> io::Result<()> {
let listener = TcpListener::bind("127.0.0.1:0").await?;
listener.set_ttl(100).expect("could not set TTL");
assert_eq!(listener.ttl()?, 100);
Ok(())
}
Sourcepub fn set_ttl(&self, ttl: u32) -> Result<()>
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::TcpListener;
use std::io;
#[tokio::main]
async fn main() -> io::Result<()> {
let listener = TcpListener::bind("127.0.0.1:0").await?;
listener.set_ttl(100).expect("could not set TTL");
Ok(())
}