Struct mio::net::UdpSocket

pub struct UdpSocket { /* private fields */ }

A User Datagram Protocol socket.

This is an implementation of a bound UDP socket. This supports both IPv4 and IPv6 addresses, and there is no corresponding notion of a server because UDP is a datagram protocol.

Examples

// An Echo program:
// SENDER -> sends a message.
// ECHOER -> listens and prints the message received.

use mio::net::UdpSocket;
use mio::{Events, Ready, Poll, PollOpt, Token};
use std::time::Duration;

const SENDER: Token = Token(0);
const ECHOER: Token = Token(1);

// This operation will fail if the address is in use, so we select different ports for each
// socket.
let sender_socket = UdpSocket::bind(&"127.0.0.1:0".parse()?)?;
let echoer_socket = UdpSocket::bind(&"127.0.0.1:0".parse()?)?;

// If we do not use connect here, SENDER and ECHOER would need to call send_to and recv_from
// respectively.
sender_socket.connect(echoer_socket.local_addr().unwrap())?;

// We need a Poll to check if SENDER is ready to be written into, and if ECHOER is ready to be
// read from.
let poll = Poll::new()?;

// We register our sockets here so that we can check if they are ready to be written/read.
poll.register(&sender_socket, SENDER, Ready::writable(), PollOpt::edge())?;
poll.register(&echoer_socket, ECHOER, Ready::readable(), PollOpt::edge())?;

let msg_to_send = [9; 9];
let mut buffer = [0; 9];

let mut events = Events::with_capacity(128);
loop {
    poll.poll(&mut events, Some(Duration::from_millis(100)))?;
    for event in events.iter() {
        match event.token() {
            // Our SENDER is ready to be written into.
            SENDER => {
                let bytes_sent = sender_socket.send(&msg_to_send)?;
                assert_eq!(bytes_sent, 9);
                println!("sent {:?} -> {:?} bytes", msg_to_send, bytes_sent);
            },
            // Our ECHOER is ready to be read from.
            ECHOER => {
                let num_recv = echoer_socket.recv(&mut buffer)?;
                println!("echo {:?} -> {:?}", buffer, num_recv);
                buffer = [0; 9];
            }
            _ => unreachable!()
        }
    }
}

Implementations

impl UdpSocket

pub fn bind(addr: &SocketAddr) -> Result<UdpSocket>

Creates a UDP socket from the given address.

Examples

use mio::net::UdpSocket;

// We must bind it to an open address.
let socket = match UdpSocket::bind(&"127.0.0.1:0".parse()?) {
    Ok(new_socket) => new_socket,
    Err(fail) => {
        // We panic! here, but you could try to bind it again on another address.
        panic!("Failed to bind socket. {:?}", fail);
    }
};

// Our socket was created, but we should not use it before checking it's readiness.

pub fn from_socket(socket: UdpSocket) -> Result<UdpSocket>

Creates a new mio-wrapped socket from an underlying and bound std socket.

This function requires that socket has previously been bound to an address to work correctly, and returns an I/O object which can be used with mio to send/receive UDP messages.

This can be used in conjunction with net2’s UdpBuilder interface to configure a socket before it’s handed off to mio, such as setting options like reuse_address or binding to multiple addresses.

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

Returns the socket address that this socket was created from.

Examples

use mio::net::UdpSocket;

let addr = "127.0.0.1:0".parse()?;
let socket = UdpSocket::bind(&addr)?;

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

Creates a new independently owned handle to the underlying socket.

The returned UdpSocket is a reference to the same socket that this object references. Both handles will read and write the same port, and options set on one socket will be propagated to the other.

Examples

use mio::net::UdpSocket;

// We must bind it to an open address.
let socket = UdpSocket::bind(&"127.0.0.1:0".parse()?)?;
let cloned_socket = socket.try_clone()?;

assert_eq!(socket.local_addr()?, cloned_socket.local_addr()?);

pub fn send_to(&self, buf: &[u8], target: &SocketAddr) -> Result<usize>

Sends data on the socket to the given address. On success, returns the number of bytes written.

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

Examples

use mio::net::UdpSocket;

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

// We must check if the socket is writable before calling send_to,
// or we could run into a WouldBlock error.

let bytes_sent = socket.send_to(&[9; 9], &"127.0.0.1:11100".parse()?)?;
assert_eq!(bytes_sent, 9);

pub 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 address from whence the data came.

Examples

use mio::net::UdpSocket;

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

// We must check if the socket is readable before calling recv_from,
// or we could run into a WouldBlock error.

let mut buf = [0; 9];
let (num_recv, from_addr) = socket.recv_from(&mut buf)?;
println!("Received {:?} -> {:?} bytes from {:?}", buf, num_recv, from_addr);

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

Sends data on the socket to the address previously bound via connect(). On success, returns the number of bytes written.

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

Receives data from the socket previously bound with connect(). On success, returns the number of bytes read.

pub fn connect(&self, addr: SocketAddr) -> Result<()>

Connects the UDP socket setting the default destination for send() and limiting packets that are read via recv from the address specified in addr.

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.

Examples

use mio::net::UdpSocket;

let broadcast_socket = UdpSocket::bind(&"127.0.0.1:0".parse()?)?;
if broadcast_socket.broadcast()? == false {
    broadcast_socket.set_broadcast(true)?;
}

assert_eq!(broadcast_socket.broadcast()?, true);

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.

Examples

use mio::net::UdpSocket;

let broadcast_socket = UdpSocket::bind(&"127.0.0.1:0".parse()?)?;
assert_eq!(broadcast_socket.broadcast()?, false);

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 that this may not have any affect on IPv6 sockets.

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.

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 that this may not have any affect on IPv6 sockets.

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.

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 that this may not have any affect on IPv4 sockets.

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.

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 mio::net::UdpSocket;

let socket = UdpSocket::bind(&"127.0.0.1:0".parse()?)?;
if socket.ttl()? < 255 {
    socket.set_ttl(255)?;
}

assert_eq!(socket.ttl()?, 255);

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 mio::net::UdpSocket;

let socket = UdpSocket::bind(&"127.0.0.1:0".parse()?)?;
socket.set_ttl(255)?;

assert_eq!(socket.ttl()?, 255);

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

Executes an operation of the IP_ADD_MEMBERSHIP type.

This function 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.

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

Executes an operation of the IPV6_ADD_MEMBERSHIP type.

This function 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).

pub fn leave_multicast_v4(
    &self,
    multiaddr: &Ipv4Addr,
    interface: &Ipv4Addr
) -> Result<()>

Executes an operation of the IP_DROP_MEMBERSHIP type.

For more information about this option, see join_multicast_v4.

pub fn leave_multicast_v6(
    &self,
    multiaddr: &Ipv6Addr,
    interface: u32
) -> Result<()>

Executes an operation of the IPV6_DROP_MEMBERSHIP type.

For more information about this option, see join_multicast_v6.

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

Sets the value for the IPV6_V6ONLY option on this socket.

If this is set to true then the socket is restricted to sending and receiving IPv6 packets only. In this case two IPv4 and IPv6 applications can bind the same port at the same time.

If this is set to false then the socket can be used to send and receive packets from an IPv4-mapped IPv6 address.

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

Gets the value of the IPV6_V6ONLY option for this socket.

For more information about this option, see set_only_v6.

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

Get 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.

pub fn recv_bufs(&self, bufs: &mut [&mut IoVec]) -> Result<usize>

Receives a single datagram message socket previously bound with connect.

This operation will attempt to read bytes from this socket and place them into the list of buffers provided. Note that each buffer is an IoVec which can be created from a byte slice.

The buffers provided will be filled sequentially. A buffer will be entirely filled up before the next is written to.

The number of bytes read is returned, if successful, or an error is returned otherwise. If no bytes are available to be read yet then a WouldBlock error is returned. This operation does not block.

On Unix this corresponds to the readv syscall.

pub fn send_bufs(&self, bufs: &[&IoVec]) -> Result<usize>

Sends data on the socket to the address previously bound via connect.

This operation will attempt to send a list of byte buffers to this socket in a single datagram. Note that each buffer is an IoVec which can be created from a byte slice.

The buffers provided will be written sequentially. A buffer will be entirely written before the next is written.

The number of bytes written is returned, if successful, or an error is returned otherwise. If the socket is not currently writable then a WouldBlock error is returned. This operation does not block.

On Unix this corresponds to the writev syscall.

Trait Implementations

impl AsRawFd for UdpSocket

fn as_raw_fd(&self) -> RawFd

Extracts the raw file descriptor.

impl Debug for UdpSocket

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

Formats the value using the given formatter.

impl Evented for UdpSocket

fn register(
    &self,
    poll: &Poll,
    token: Token,
    interest: Ready,
    opts: PollOpt
) -> Result<()>

Register self with the given Poll instance.

fn reregister(
    &self,
    poll: &Poll,
    token: Token,
    interest: Ready,
    opts: PollOpt
) -> Result<()>

Re-register self with the given Poll instance.

fn deregister(&self, poll: &Poll) -> Result<()>

Deregister self from the given Poll instance

impl FromRawFd for UdpSocket

unsafe fn from_raw_fd(fd: RawFd) -> UdpSocket

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

impl IntoRawFd for UdpSocket

fn into_raw_fd(self) -> RawFd

Consumes this object, returning the raw underlying file descriptor.