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//! UDP I/O via mio (kqueue on OpenBSD, epoll on Linux).
//!
//! Supports dynamic registration of additional sockets
//! (needed by NAT detector's temporary probe socket).
use std::net::SocketAddr;
use std::time::Duration;
use mio::net::UdpSocket;
use mio::{Events, Interest, Poll, Registry, Token};
use crate::error::Error;
/// Token for the primary DHT socket.
pub const UDP_TOKEN: Token = Token(0);
/// Event-driven network I/O loop.
///
/// Wraps a mio `Poll` with a primary UDP socket.
/// Additional sockets can be registered dynamically
/// (e.g. for NAT detection probes).
pub struct NetLoop {
poll: Poll,
events: Events,
socket: UdpSocket,
next_token: usize,
}
impl NetLoop {
/// Bind a UDP socket and register it with the poller.
pub fn bind(addr: SocketAddr) -> Result<Self, Error> {
let poll = Poll::new()?;
let mut socket = UdpSocket::bind(addr)?;
poll.registry()
.register(&mut socket, UDP_TOKEN, Interest::READABLE)?;
Ok(Self {
poll,
events: Events::with_capacity(64),
socket,
next_token: 1,
})
}
/// Send a datagram to the given address.
pub fn send_to(
&self,
buf: &[u8],
addr: SocketAddr,
) -> Result<usize, Error> {
self.socket.send_to(buf, addr).map_err(Error::Io)
}
/// Receive a datagram from the primary socket.
///
/// Returns `(bytes_read, sender_address)` or
/// `WouldBlock` if no data available.
pub fn recv_from(
&self,
buf: &mut [u8],
) -> Result<(usize, SocketAddr), Error> {
self.socket.recv_from(buf).map_err(Error::Io)
}
/// Poll for I/O events, blocking up to `timeout`.
pub fn poll_events(&mut self, timeout: Duration) -> Result<(), Error> {
self.poll.poll(&mut self.events, Some(timeout))?;
Ok(())
}
/// Iterate over events from the last `poll_events` call.
pub fn drain_events(&self) -> impl Iterator<Item = &mio::event::Event> {
self.events.iter()
}
/// Get the local address of the primary socket.
pub fn local_addr(&self) -> Result<SocketAddr, Error> {
self.socket.local_addr().map_err(Error::Io)
}
/// Access the mio registry for registering additional
/// sockets (e.g. NAT detection probe sockets).
pub fn registry(&self) -> &Registry {
self.poll.registry()
}
/// Allocate a new unique token for a dynamic socket.
/// Wraps at usize::MAX, skips 0 (reserved for
/// UDP_TOKEN).
pub fn next_token(&mut self) -> Token {
let t = Token(self.next_token);
self.next_token = self.next_token.wrapping_add(1).max(1);
t
}
/// Register an additional UDP socket with the poller.
///
/// Returns the assigned token.
pub fn register_socket(
&mut self,
socket: &mut UdpSocket,
) -> Result<Token, Error> {
let token = self.next_token();
self.poll
.registry()
.register(socket, token, Interest::READABLE)?;
Ok(token)
}
/// Deregister a previously registered socket.
pub fn deregister_socket(
&mut self,
socket: &mut UdpSocket,
) -> Result<(), Error> {
self.poll.registry().deregister(socket)?;
Ok(())
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn bind_and_local_addr() {
let net = NetLoop::bind("127.0.0.1:0".parse().unwrap()).unwrap();
let addr = net.local_addr().unwrap();
assert_eq!(addr.ip(), "127.0.0.1".parse::<std::net::IpAddr>().unwrap());
assert_ne!(addr.port(), 0);
}
#[test]
fn send_recv_loopback() {
let net = NetLoop::bind("127.0.0.1:0".parse().unwrap()).unwrap();
let addr = net.local_addr().unwrap();
// Send to self
let sent = net.send_to(b"ping", addr).unwrap();
assert_eq!(sent, 4);
// Poll for the event
let mut net = net;
net.poll_events(Duration::from_millis(100)).unwrap();
let mut buf = [0u8; 64];
let (len, from) = net.recv_from(&mut buf).unwrap();
assert_eq!(&buf[..len], b"ping");
assert_eq!(from, addr);
}
#[test]
fn register_extra_socket() {
let mut net = NetLoop::bind("127.0.0.1:0".parse().unwrap()).unwrap();
let mut extra =
UdpSocket::bind("127.0.0.1:0".parse().unwrap()).unwrap();
let token = net.register_socket(&mut extra).unwrap();
assert_ne!(token, UDP_TOKEN);
net.deregister_socket(&mut extra).unwrap();
}
}
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