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//! Uniform interface to send/recv UDP packets with ECN information.
#![warn(unreachable_pub)]
#![warn(clippy::use_self)]
#[cfg(unix)]
use std::os::unix::io::AsFd;
#[cfg(windows)]
use std::os::windows::io::AsSocket;
#[cfg(not(windows))]
use std::sync::atomic::AtomicBool;
use std::{
net::{IpAddr, Ipv6Addr, SocketAddr},
sync::{
atomic::{AtomicUsize, Ordering},
Mutex,
},
time::{Duration, Instant},
};
use bytes::Bytes;
use tracing::warn;
#[cfg(unix)]
mod cmsg;
#[cfg(unix)]
#[path = "unix.rs"]
mod imp;
#[cfg(windows)]
#[path = "windows.rs"]
mod imp;
// No ECN support
#[cfg(not(any(unix, windows)))]
#[path = "fallback.rs"]
mod imp;
pub use imp::UdpSocketState;
/// Whether transmitted datagrams might get fragmented by the IP layer
///
/// Returns `false` on targets which employ e.g. the `IPV6_DONTFRAG` socket option.
#[inline]
pub fn may_fragment() -> bool {
imp::may_fragment()
}
/// Number of UDP packets to send/receive at a time
pub const BATCH_SIZE: usize = imp::BATCH_SIZE;
/// The capabilities a UDP socket suppports on a certain platform
#[derive(Debug)]
pub struct UdpState {
max_gso_segments: AtomicUsize,
gro_segments: usize,
/// True if we have received EINVAL error from `sendmsg` or `sendmmsg` system call at least once.
///
/// If enabled, we assume that old kernel is used and switch to fallback mode.
/// In particular, we do not use IP_TOS cmsg_type in this case,
/// which is not supported on Linux <3.13 and results in not sending the UDP packet at all.
#[cfg(not(windows))]
sendmsg_einval: AtomicBool,
}
impl UdpState {
pub fn new() -> Self {
imp::udp_state()
}
/// The maximum amount of segments which can be transmitted if a platform
/// supports Generic Send Offload (GSO).
///
/// This is 1 if the platform doesn't support GSO. Subject to change if errors are detected
/// while using GSO.
#[inline]
pub fn max_gso_segments(&self) -> usize {
self.max_gso_segments.load(Ordering::Relaxed)
}
/// The number of segments to read when GRO is enabled. Used as a factor to
/// compute the receive buffer size.
///
/// Returns 1 if the platform doesn't support GRO.
#[inline]
pub fn gro_segments(&self) -> usize {
self.gro_segments
}
/// Returns true if we previously got an EINVAL error from `sendmsg` or `sendmmsg` syscall.
#[inline]
#[cfg(not(windows))]
fn sendmsg_einval(&self) -> bool {
self.sendmsg_einval.load(Ordering::Relaxed)
}
/// Sets the flag indicating we got EINVAL error from `sendmsg` or `sendmmsg` syscall.
#[inline]
#[cfg(all(
unix,
not(any(
target_os = "macos",
target_os = "ios",
target_os = "openbsd",
target_os = "netbsd"
))
))]
fn set_sendmsg_einval(&self) {
self.sendmsg_einval.store(true, Ordering::Relaxed)
}
}
impl Default for UdpState {
fn default() -> Self {
Self::new()
}
}
#[derive(Debug, Copy, Clone)]
pub struct RecvMeta {
pub addr: SocketAddr,
pub len: usize,
pub stride: usize,
pub ecn: Option<EcnCodepoint>,
/// The destination IP address which was encoded in this datagram
pub dst_ip: Option<IpAddr>,
}
impl Default for RecvMeta {
/// Constructs a value with arbitrary fields, intended to be overwritten
fn default() -> Self {
Self {
addr: SocketAddr::new(Ipv6Addr::UNSPECIFIED.into(), 0),
len: 0,
stride: 0,
ecn: None,
dst_ip: None,
}
}
}
/// An outgoing packet
#[derive(Debug, Clone)]
pub struct Transmit {
/// The socket this datagram should be sent to
pub destination: SocketAddr,
/// Explicit congestion notification bits to set on the packet
pub ecn: Option<EcnCodepoint>,
/// Contents of the datagram
pub contents: Bytes,
/// The segment size if this transmission contains multiple datagrams.
/// This is `None` if the transmit only contains a single datagram
pub segment_size: Option<usize>,
/// Optional source IP address for the datagram
pub src_ip: Option<IpAddr>,
}
/// Log at most 1 IO error per minute
const IO_ERROR_LOG_INTERVAL: Duration = std::time::Duration::from_secs(60);
/// Logs a warning message when sendmsg fails
///
/// Logging will only be performed if at least [`IO_ERROR_LOG_INTERVAL`]
/// has elapsed since the last error was logged.
fn log_sendmsg_error(
last_send_error: &Mutex<Instant>,
err: impl core::fmt::Debug,
transmit: &Transmit,
) {
let now = Instant::now();
let last_send_error = &mut *last_send_error.lock().expect("poisend lock");
if now.saturating_duration_since(*last_send_error) > IO_ERROR_LOG_INTERVAL {
*last_send_error = now;
warn!(
"sendmsg error: {:?}, Transmit: {{ destination: {:?}, src_ip: {:?}, enc: {:?}, len: {:?}, segment_size: {:?} }}",
err, transmit.destination, transmit.src_ip, transmit.ecn, transmit.contents.len(), transmit.segment_size);
}
}
/// A borrowed UDP socket
///
/// On Unix, constructible via `From<T: AsRawFd>`. On Windows, constructible via `From<T:
/// AsRawSocket>`.
// Wrapper around socket2 to avoid making it a public dependency and incurring stability risk
pub struct UdpSockRef<'a>(socket2::SockRef<'a>);
#[cfg(unix)]
impl<'s, S> From<&'s S> for UdpSockRef<'s>
where
S: AsFd,
{
fn from(socket: &'s S) -> Self {
Self(socket.into())
}
}
#[cfg(windows)]
impl<'s, S> From<&'s S> for UdpSockRef<'s>
where
S: AsSocket,
{
fn from(socket: &'s S) -> Self {
Self(socket.into())
}
}
/// Explicit congestion notification codepoint
#[repr(u8)]
#[derive(Debug, Copy, Clone, Eq, PartialEq)]
pub enum EcnCodepoint {
#[doc(hidden)]
Ect0 = 0b10,
#[doc(hidden)]
Ect1 = 0b01,
#[doc(hidden)]
Ce = 0b11,
}
impl EcnCodepoint {
/// Create new object from the given bits
pub fn from_bits(x: u8) -> Option<Self> {
use self::EcnCodepoint::*;
Some(match x & 0b11 {
0b10 => Ect0,
0b01 => Ect1,
0b11 => Ce,
_ => {
return None;
}
})
}
}