Struct async_std::net::UdpSocket

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pub struct UdpSocket { /* private fields */ }

Expand description

A UDP socket.

After creating a UdpSocket by binding it to a socket address, data can be sent to and received from any other socket address.

As stated in the User Datagram Protocol’s specification in IETF RFC 768, UDP is an unordered, unreliable protocol. Refer to TcpListener and TcpStream for async TCP primitives.

This type is an async version of std::net::UdpSocket.

§Examples

use async_std::net::UdpSocket;

let socket = UdpSocket::bind("127.0.0.1:8080").await?;
let mut buf = vec![0u8; 1024];

loop {
    let (n, peer) = socket.recv_from(&mut buf).await?;
    socket.send_to(&buf[..n], &peer).await?;
}

Implementations§

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impl UdpSocket

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pub async fn bind<A: ToSocketAddrs>(addrs: A) -> Result<UdpSocket>

Creates a UDP socket from the given address.

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

§Examples

use async_std::net::UdpSocket;

let socket = UdpSocket::bind("127.0.0.1:0").await?;

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

Returns the peer address that this listener is connected to.

This can be useful, for example, when connect to port 0 to figure out which port was actually connected.

§Examples

use async_std::net::UdpSocket;

let socket1 = UdpSocket::bind("127.0.0.1:0").await?;
let socket2 = UdpSocket::bind("127.0.0.1:0").await?;
socket1.connect(socket2.local_addr()?).await?;
let addr = socket1.peer_addr()?;

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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 async_std::net::UdpSocket;

let socket = UdpSocket::bind("127.0.0.1:0").await?;
let addr = socket.local_addr()?;

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pub async fn send_to<A: ToSocketAddrs>( &self, buf: &[u8], addrs: A, ) -> Result<usize>

Sends data on the socket to the given address.

On success, returns the number of bytes written.

§Examples

use async_std::net::UdpSocket;

const THE_MERCHANT_OF_VENICE: &[u8] = b"
    If you prick us, do we not bleed?
    If you tickle us, do we not laugh?
    If you poison us, do we not die?
    And if you wrong us, shall we not revenge?
";

let socket = UdpSocket::bind("127.0.0.1:0").await?;

let addr = "127.0.0.1:7878";
let sent = socket.send_to(THE_MERCHANT_OF_VENICE, &addr).await?;
println!("Sent {} bytes to {}", sent, addr);

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pub async fn recv_from(&self, buf: &mut [u8]) -> Result<(usize, SocketAddr)>

Receives data from the socket.

On success, returns the number of bytes read and the origin.

§Examples

use async_std::net::UdpSocket;

let socket = UdpSocket::bind("127.0.0.1:0").await?;

let mut buf = vec![0; 1024];
let (n, peer) = socket.recv_from(&mut buf).await?;
println!("Received {} bytes from {}", n, peer);

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pub async fn peek_from(&self, buf: &mut [u8]) -> Result<(usize, SocketAddr)>

Receives data from socket without removing it from the queue.

On success, returns the number of bytes peeked and the origin.

§Examples

use async_std::net::UdpSocket;

let socket = UdpSocket::bind("127.0.0.1:0").await?;

let mut buf = vec![0; 1024];
let (n, peer) = socket.peek_from(&mut buf).await?;
println!("Peeked {} bytes from {}", n, peer);

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pub async fn connect<A: ToSocketAddrs>(&self, addrs: A) -> Result<()>

Connects the UDP socket to a remote address.

When connected, methods send and recv will use the specified address for sending and receiving messages. Additionally, a filter will be applied to recv_from so that it only receives messages from that same address.

§Examples

use async_std::net::UdpSocket;

let socket = UdpSocket::bind("127.0.0.1:0").await?;
socket.connect("127.0.0.1:8080").await?;

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pub async fn send(&self, buf: &[u8]) -> Result<usize>

Sends data on the socket to the remote address to which it is connected.

The connect method will connect this socket to a remote address. This method will fail if the socket is not connected.

§Examples

use async_std::net::UdpSocket;

let socket = UdpSocket::bind("127.0.0.1:34254").await?;
socket.connect("127.0.0.1:8080").await?;
let bytes = socket.send(b"Hi there!").await?;

println!("Sent {} bytes", bytes);

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

Receives data from the socket.

On success, returns the number of bytes read.

§Examples

use async_std::net::UdpSocket;

let socket = UdpSocket::bind("127.0.0.1:0").await?;
socket.connect("127.0.0.1:8080").await?;

let mut buf = vec![0; 1024];
let n = socket.recv(&mut buf).await?;
println!("Received {} bytes", n);

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

Receives data from the socket without removing it from the queue.

On success, returns the number of bytes peeked.

§Examples

use async_std::net::UdpSocket;

let socket = UdpSocket::bind("127.0.0.1:0").await?;
socket.connect("127.0.0.1:8080").await?;

let mut buf = vec![0; 1024];
let n = socket.peek(&mut buf).await?;
println!("Peeked {} bytes", n);

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

Gets the value of the SO_BROADCAST option for this socket.

For more information about this option, see set_broadcast.

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pub fn set_broadcast(&self, on: bool) -> Result<()>

Sets the value of the SO_BROADCAST option for this socket.

When enabled, this socket is allowed to send packets to a broadcast address.

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pub fn multicast_loop_v4(&self) -> Result<bool>

Gets the value of the IP_MULTICAST_LOOP option for this socket.

For more information about this option, see set_multicast_loop_v4.

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pub fn set_multicast_loop_v4(&self, on: bool) -> Result<()>

Sets the value of the IP_MULTICAST_LOOP option for this socket.

If enabled, multicast packets will be looped back to the local socket.

§Note

This may not have any affect on IPv6 sockets.

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pub fn multicast_ttl_v4(&self) -> Result<u32>

Gets the value of the IP_MULTICAST_TTL option for this socket.

For more information about this option, see set_multicast_ttl_v4.

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pub fn set_multicast_ttl_v4(&self, ttl: u32) -> Result<()>

Sets the value of the IP_MULTICAST_TTL option for this socket.

Indicates the time-to-live value of outgoing multicast packets for this socket. The default value is 1 which means that multicast packets don’t leave the local network unless explicitly requested.

§Note

This may not have any affect on IPv6 sockets.

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pub fn multicast_loop_v6(&self) -> Result<bool>

Gets the value of the IPV6_MULTICAST_LOOP option for this socket.

For more information about this option, see set_multicast_loop_v6.

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pub fn set_multicast_loop_v6(&self, on: bool) -> Result<()>

Sets the value of the IPV6_MULTICAST_LOOP option for this socket.

Controls whether this socket sees the multicast packets it sends itself.

§Note

This may not have any affect on IPv4 sockets.

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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.

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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.

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pub fn join_multicast_v4( &self, multiaddr: Ipv4Addr, interface: Ipv4Addr, ) -> Result<()>

Executes an operation of the IP_ADD_MEMBERSHIP type.

This method specifies a new multicast group for this socket to join. The address must be a valid multicast address, and interface is the address of the local interface with which the system should join the multicast group. If it’s equal to INADDR_ANY then an appropriate interface is chosen by the system.

§Examples

use std::net::Ipv4Addr;

use async_std::net::UdpSocket;

let interface = Ipv4Addr::new(0, 0, 0, 0);
let mdns_addr = Ipv4Addr::new(224, 0, 0, 123);

let socket = UdpSocket::bind("127.0.0.1:0").await?;
socket.join_multicast_v4(mdns_addr, interface)?;

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pub fn join_multicast_v6( &self, multiaddr: &Ipv6Addr, interface: u32, ) -> Result<()>

Executes an operation of the IPV6_ADD_MEMBERSHIP type.

This method specifies a new multicast group for this socket to join. The address must be a valid multicast address, and interface is the index of the interface to join/leave (or 0 to indicate any interface).

§Examples

use std::net::{Ipv6Addr, SocketAddr};

use async_std::net::UdpSocket;

let socket_addr = SocketAddr::new(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 0).into(), 0);
let mdns_addr = Ipv6Addr::new(0xFF02, 0, 0, 0, 0, 0, 0, 0x0123);
let socket = UdpSocket::bind(&socket_addr).await?;

socket.join_multicast_v6(&mdns_addr, 0)?;