Implement socket_bind_device and set_socket_bind_device

src/backend/libc/net/sockopt.rs

@@ -70,6 +70,9 @@ use alloc::borrow::ToOwned as _;
     target_os = "illumos"
 ))]
 use alloc::string::String;
+#[cfg(feature = "alloc")]
+#[cfg(any(linux_kernel, target_os = "fuchsia"))]
+use alloc::vec::Vec;
 #[cfg(apple)]
 use c::TCP_KEEPALIVE as TCP_KEEPIDLE;
 #[cfg(not(any(apple, target_os = "haiku", target_os = "nto", target_os = "openbsd")))]
@@ -357,6 +360,41 @@ pub(crate) fn socket_recv_buffer_size(fd: BorrowedFd<'_>) -> io::Result<usize> {
     getsockopt(fd, c::SOL_SOCKET, c::SO_RCVBUF).map(|size: u32| size as usize)
 }
 
+#[cfg(feature = "alloc")]
+#[cfg(any(linux_kernel, target_os = "fuchsia"))]
+#[inline]
+pub(crate) fn socket_bind_device(fd: BorrowedFd<'_>) -> io::Result<Vec<u8>> {
+    let mut value = MaybeUninit::<[MaybeUninit<u8>; 16]>::uninit();
+    let mut optlen = 16;
+    getsockopt_raw(
+        fd,
+        c::SOL_SOCKET,
+        c::SO_BINDTODEVICE,
+        &mut value,
+        &mut optlen,
+    )?;
+    unsafe {
+        let value = value.assume_init();
+        let slice: &[u8] = core::mem::transmute(&value[..optlen as usize]);
+        assert!(slice.contains(&b'\0'));
+        Ok(slice[..optlen as usize - 1].to_vec())
+    }
+}
+
+#[cfg(any(linux_kernel, target_os = "fuchsia"))]
+#[inline]
+pub(crate) fn set_socket_bind_device(
+    fd: BorrowedFd<'_>,
+    interface: Option<&[u8]>,
+) -> io::Result<()> {
+    setsockopt(
+        fd,
+        c::SOL_SOCKET,
+        c::SO_BINDTODEVICE,
+        interface.unwrap_or(&[]),
+    )
+}
+
 #[inline]
 pub(crate) fn set_socket_send_buffer_size(fd: BorrowedFd<'_>, size: usize) -> io::Result<()> {
     let size: c::c_int = size.try_into().map_err(|_| io::Errno::INVAL)?;

src/backend/linux_raw/net/sockopt.rs

@@ -22,10 +22,12 @@ use crate::net::{
 use alloc::borrow::ToOwned as _;
 #[cfg(feature = "alloc")]
 use alloc::string::String;
+#[cfg(feature = "alloc")]
+use alloc::vec::Vec;
 use core::mem::{size_of, MaybeUninit};
 use core::time::Duration;
 use linux_raw_sys::general::{__kernel_old_timeval, __kernel_sock_timeval};
-use linux_raw_sys::net::{IPV6_MTU, IPV6_MULTICAST_IF, IP_MTU, IP_MULTICAST_IF};
+use linux_raw_sys::net::{IPV6_MTU, IPV6_MULTICAST_IF, IP_MTU, IP_MULTICAST_IF, SO_BINDTODEVICE};
 #[cfg(target_os = "linux")]
 use linux_raw_sys::xdp::{xdp_mmap_offsets, xdp_statistics, xdp_statistics_v1};
 #[cfg(target_arch = "x86")]
@@ -432,6 +434,28 @@ pub(crate) fn set_socket_incoming_cpu(fd: BorrowedFd<'_>, value: u32) -> io::Res
     setsockopt(fd, c::SOL_SOCKET, c::SO_INCOMING_CPU, value)
 }
 
+#[cfg(feature = "alloc")]
+#[inline]
+pub(crate) fn socket_bind_device(fd: BorrowedFd<'_>) -> io::Result<Vec<u8>> {
+    let mut value = MaybeUninit::<[MaybeUninit<u8>; 16]>::uninit();
+    let mut optlen = 16;
+    getsockopt_raw(fd, c::SOL_SOCKET, SO_BINDTODEVICE, &mut value, &mut optlen)?;
+    unsafe {
+        let value = value.assume_init();
+        let slice: &[u8] = core::mem::transmute(&value[..optlen as usize]);
+        assert!(slice.contains(&b'\0'));
+        Ok(slice[..optlen as usize - 1].to_vec())
+    }
+}
+
+#[inline]
+pub(crate) fn set_socket_bind_device(
+    fd: BorrowedFd<'_>,
+    interface: Option<&[u8]>,
+) -> io::Result<()> {
+    setsockopt(fd, c::SOL_SOCKET, SO_BINDTODEVICE, interface.unwrap_or(&[]))
+}
+
 #[inline]
 pub(crate) fn set_ip_ttl(fd: BorrowedFd<'_>, ttl: u32) -> io::Result<()> {
     setsockopt(fd, c::IPPROTO_IP, c::IP_TTL, ttl)

src/net/sockopt.rs

@@ -618,6 +618,30 @@ pub fn set_socket_incoming_cpu<Fd: AsFd>(fd: Fd, value: u32) -> io::Result<()> {
     backend::net::sockopt::set_socket_incoming_cpu(fd.as_fd(), value)
 }
 
+/// `getsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE)`
+///
+/// See the [module-level documentation] for more.
+///
+/// [module-level documentation]: self#references-for-get_socket_-and-set_socket_-functions
+#[cfg(feature = "alloc")]
+#[cfg(any(linux_kernel, target_os = "fuchsia"))]
+#[inline]
+#[doc(alias = "SO_BINDTODEVICE")]
+pub fn socket_bind_device<Fd: AsFd>(fd: Fd) -> io::Result<Vec<u8>> {
+    backend::net::sockopt::socket_bind_device(fd.as_fd())
+}
+
+/// `setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, interface)`
+///
+/// See the [module-level documentation] for more.
+///
+/// [module-level documentation]: self#references-for-get_socket_-and-set_socket_-functions
+#[cfg(any(linux_kernel, target_os = "fuchsia"))]
+#[doc(alias = "SO_BINDTODEVICE")]
+pub fn set_socket_bind_device<Fd: AsFd>(fd: Fd, interface: Option<&[u8]>) -> io::Result<()> {
+    backend::net::sockopt::set_socket_bind_device(fd.as_fd(), interface)
+}
+
 /// `setsockopt(fd, IPPROTO_IP, IP_TTL, value)`
 ///
 /// See the [module-level documentation] for more.

tests/net/sockopt.rs

@@ -633,3 +633,26 @@ fn test_sockopts_multicast_ifv6() {
         Err(e) => panic!("{e}"),
     }
 }
+
+#[cfg(feature = "alloc")]
+#[cfg(any(linux_kernel, target_os = "fuchsia"))]
+#[test]
+fn test_socket_bind_device() {
+    let fd = rustix::net::socket(AddressFamily::INET, SocketType::STREAM, None).unwrap();
+
+    let loopback_index = std::fs::read_to_string("/sys/class/net/lo/ifindex")
+        .unwrap()
+        .as_str()
+        .split_at(1)
+        .0
+        .parse::<u32>()
+        .unwrap();
+    let name = rustix::net::netdevice::index_to_name(&fd, loopback_index).unwrap();
+
+    sockopt::set_socket_bind_device(&fd, Some(name.as_bytes())).unwrap();
+
+    assert_eq!(
+        name.as_bytes(),
+        sockopt::socket_bind_device(&fd).unwrap().as_slice()
+    );
+}