feat: Allow changing the UDP send/receive buffer sizes

perf/src/lib.rs

@@ -1,6 +1,7 @@
 use std::net::SocketAddr;
 
 use anyhow::{Context, Result};
+use quinn::udp::UdpSocketState;
 use rustls::crypto::ring::cipher_suite;
 use socket2::{Domain, Protocol, Socket, Type};
 use tracing::warn;
@@ -25,22 +26,28 @@ pub fn bind_socket(
     socket
         .bind(&socket2::SockAddr::from(addr))
         .context("binding endpoint")?;
-    socket
-        .set_send_buffer_size(send_buffer_size)
+
+    let socket_state = UdpSocketState::new((&socket).into())?;
+    socket_state
+        .set_send_buffer_size((&socket).into(), send_buffer_size)
         .context("send buffer size")?;
-    socket
-        .set_recv_buffer_size(recv_buffer_size)
+    socket_state
+        .set_recv_buffer_size((&socket).into(), recv_buffer_size)
         .context("recv buffer size")?;
 
-    let buf_size = socket.send_buffer_size().context("send buffer size")?;
+    let buf_size = socket_state
+        .send_buffer_size((&socket).into())
+        .context("send buffer size")?;
     if buf_size < send_buffer_size {
         warn!(
             "Unable to set desired send buffer size. Desired: {}, Actual: {}",
             send_buffer_size, buf_size
         );
     }
 
-    let buf_size = socket.recv_buffer_size().context("recv buffer size")?;
+    let buf_size = socket_state
+        .recv_buffer_size((&socket).into())
+        .context("recv buffer size")?;
     if buf_size < recv_buffer_size {
         warn!(
             "Unable to set desired recv buffer size. Desired: {}, Actual: {}",

quinn-udp/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "quinn-udp"
-version = "0.5.10"
+version = "0.5.11"
 edition.workspace = true
 rust-version.workspace = true
 license.workspace = true

quinn-udp/src/fallback.rs

@@ -86,6 +86,30 @@ impl UdpSocketState {
         1
     }
 
+    /// Resize the send buffer of `socket` to `bytes`
+    #[inline]
+    pub fn set_send_buffer_size(&self, socket: UdpSockRef<'_>, bytes: usize) -> io::Result<()> {
+        socket.0.set_send_buffer_size(bytes)
+    }
+
+    /// Resize the receive buffer of `socket` to `bytes`
+    #[inline]
+    pub fn set_recv_buffer_size(&self, socket: UdpSockRef<'_>, bytes: usize) -> io::Result<()> {
+        socket.0.set_recv_buffer_size(bytes)
+    }
+
+    /// Get the size of the `socket` send buffer
+    #[inline]
+    pub fn send_buffer_size(&self, socket: UdpSockRef<'_>) -> io::Result<usize> {
+        socket.0.send_buffer_size()
+    }
+
+    /// Get the size of the `socket` receive buffer
+    #[inline]
+    pub fn recv_buffer_size(&self, socket: UdpSockRef<'_>) -> io::Result<usize> {
+        socket.0.recv_buffer_size()
+    }
+
     #[inline]
     pub fn may_fragment(&self) -> bool {
         true

quinn-udp/src/unix.rs

@@ -249,6 +249,30 @@ impl UdpSocketState {
         self.gro_segments
     }
 
+    /// Resize the send buffer of `socket` to `bytes`
+    #[inline]
+    pub fn set_send_buffer_size(&self, socket: UdpSockRef<'_>, bytes: usize) -> io::Result<()> {
+        socket.0.set_send_buffer_size(bytes)
+    }
+
+    /// Resize the receive buffer of `socket` to `bytes`
+    #[inline]
+    pub fn set_recv_buffer_size(&self, socket: UdpSockRef<'_>, bytes: usize) -> io::Result<()> {
+        socket.0.set_recv_buffer_size(bytes)
+    }
+
+    /// Get the size of the `socket` send buffer
+    #[inline]
+    pub fn send_buffer_size(&self, socket: UdpSockRef<'_>) -> io::Result<usize> {
+        socket.0.send_buffer_size()
+    }
+
+    /// Get the size of the `socket` receive buffer
+    #[inline]
+    pub fn recv_buffer_size(&self, socket: UdpSockRef<'_>) -> io::Result<usize> {
+        socket.0.recv_buffer_size()
+    }
+
     /// Whether transmitted datagrams might get fragmented by the IP layer
     ///
     /// Returns `false` on targets which employ e.g. the `IPV6_DONTFRAG` socket option.

quinn-udp/src/windows.rs

@@ -292,6 +292,30 @@ impl UdpSocketState {
         64
     }
 
+    /// Resize the send buffer of `socket` to `bytes`
+    #[inline]
+    pub fn set_send_buffer_size(&self, socket: UdpSockRef<'_>, bytes: usize) -> io::Result<()> {
+        socket.0.set_send_buffer_size(bytes)
+    }
+
+    /// Resize the receive buffer of `socket` to `bytes`
+    #[inline]
+    pub fn set_recv_buffer_size(&self, socket: UdpSockRef<'_>, bytes: usize) -> io::Result<()> {
+        socket.0.set_recv_buffer_size(bytes)
+    }
+
+    /// Get the size of the `socket` send buffer
+    #[inline]
+    pub fn send_buffer_size(&self, socket: UdpSockRef<'_>) -> io::Result<usize> {
+        socket.0.send_buffer_size()
+    }
+
+    /// Get the size of the `socket` receive buffer
+    #[inline]
+    pub fn recv_buffer_size(&self, socket: UdpSockRef<'_>) -> io::Result<usize> {
+        socket.0.recv_buffer_size()
+    }
+
     #[inline]
     pub fn may_fragment(&self) -> bool {
         false

quinn-udp/tests/tests.rs

@@ -1,8 +1,8 @@
 #[cfg(not(any(target_os = "openbsd", target_os = "netbsd", solarish)))]
-use std::net::{SocketAddr, SocketAddrV4, SocketAddrV6};
+use std::net::{SocketAddr, SocketAddrV6};
 use std::{
     io::IoSliceMut,
-    net::{IpAddr, Ipv4Addr, Ipv6Addr, UdpSocket},
+    net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddrV4, UdpSocket},
     slice,
 };
 
@@ -186,6 +186,79 @@ fn gso() {
     );
 }
 
+#[test]
+fn socket_buffers() {
+    const BUFFER_SIZE: usize = 123456;
+    const FACTOR: usize = if cfg!(any(target_os = "linux", target_os = "android")) {
+        2 // Linux and Android set the buffer to double the requested size
+    } else {
+        1 // Everyone else is sane.
+    };
+
+    let send = socket2::Socket::new(
+        socket2::Domain::IPV4,
+        socket2::Type::DGRAM,
+        Some(socket2::Protocol::UDP),
+    )
+    .unwrap();
+    let recv = socket2::Socket::new(
+        socket2::Domain::IPV4,
+        socket2::Type::DGRAM,
+        Some(socket2::Protocol::UDP),
+    )
+    .unwrap();
+    for sock in [&send, &recv] {
+        sock.bind(&socket2::SockAddr::from(SocketAddrV4::new(
+            Ipv4Addr::LOCALHOST,
+            0,
+        )))
+        .unwrap();
+
+        let socket_state = UdpSocketState::new(sock.into()).expect("created socket state");
+
+        // Change the send buffer size.
+        let buffer_before = socket_state.send_buffer_size(sock.into()).unwrap();
+        assert_ne!(
+            buffer_before,
+            BUFFER_SIZE * FACTOR,
+            "make sure buffer is not already desired size"
+        );
+        socket_state
+            .set_send_buffer_size(sock.into(), BUFFER_SIZE)
+            .expect("set send buffer size {buffer_before} -> {BUFFER_SIZE}");
+        let buffer_after = socket_state.send_buffer_size(sock.into()).unwrap();
+        assert_eq!(
+            buffer_after,
+            BUFFER_SIZE * FACTOR,
+            "setting send buffer size to {BUFFER_SIZE} resulted in {buffer_before} -> {buffer_after}",
+        );
+
+        // Change the receive buffer size.
+        let buffer_before = socket_state.recv_buffer_size(sock.into()).unwrap();
+        socket_state
+            .set_recv_buffer_size(sock.into(), BUFFER_SIZE)
+            .expect("set recv buffer size {buffer_before} -> {BUFFER_SIZE}");
+        let buffer_after = socket_state.recv_buffer_size(sock.into()).unwrap();
+        assert_eq!(
+            buffer_after,
+            BUFFER_SIZE * FACTOR,
+            "setting recv buffer size to {BUFFER_SIZE} resulted in {buffer_before} -> {buffer_after}",
+        );
+    }
+
+    test_send_recv(
+        &send,
+        &recv,
+        Transmit {
+            destination: recv.local_addr().unwrap().as_socket().unwrap(),
+            ecn: None,
+            contents: b"hello",
+            segment_size: None,
+            src_ip: None,
+        },
+    );
+}
+
 fn test_send_recv(send: &Socket, recv: &Socket, transmit: Transmit) {
     let send_state = UdpSocketState::new(send.into()).unwrap();
     let recv_state = UdpSocketState::new(recv.into()).unwrap();