Add ip_mtu_discover and ipv6_mtu_discover socket options (#1466)

Author: pekkarr

src/backend/libc/net/sockopt.rs

@@ -14,6 +14,8 @@ use crate::fd::BorrowedFd;
 use crate::ffi::CStr;
 use crate::io;
 use crate::net::sockopt::Timeout;
+#[cfg(linux_kernel)]
+use crate::net::sockopt::{Ipv4PathMtuDiscovery, Ipv6PathMtuDiscovery};
 #[cfg(target_os = "linux")]
 use crate::net::xdp::{XdpMmapOffsets, XdpOptionsFlags, XdpRingOffset, XdpStatistics, XdpUmemReg};
 #[cfg(not(any(
@@ -504,6 +506,36 @@ pub(crate) fn ipv6_mtu(fd: BorrowedFd<'_>) -> io::Result<u32> {
     getsockopt(fd, c::IPPROTO_IPV6, c::IPV6_MTU)
 }
 
+#[cfg(linux_kernel)]
+#[inline]
+pub(crate) fn set_ip_mtu_discover(
+    fd: BorrowedFd<'_>,
+    value: Ipv4PathMtuDiscovery,
+) -> io::Result<()> {
+    setsockopt(fd, c::IPPROTO_IP, c::IP_MTU_DISCOVER, value)
+}
+
+#[cfg(linux_kernel)]
+#[inline]
+pub(crate) fn ip_mtu_discover(fd: BorrowedFd<'_>) -> io::Result<Ipv4PathMtuDiscovery> {
+    getsockopt(fd, c::IPPROTO_IP, c::IP_MTU_DISCOVER)
+}
+
+#[cfg(linux_kernel)]
+#[inline]
+pub(crate) fn set_ipv6_mtu_discover(
+    fd: BorrowedFd<'_>,
+    value: Ipv6PathMtuDiscovery,
+) -> io::Result<()> {
+    setsockopt(fd, c::IPPROTO_IPV6, c::IPV6_MTU_DISCOVER, value)
+}
+
+#[cfg(linux_kernel)]
+#[inline]
+pub(crate) fn ipv6_mtu_discover(fd: BorrowedFd<'_>) -> io::Result<Ipv6PathMtuDiscovery> {
+    getsockopt(fd, c::IPPROTO_IPV6, c::IPV6_MTU_DISCOVER)
+}
+
 #[inline]
 pub(crate) fn set_ip_multicast_if(fd: BorrowedFd<'_>, value: &Ipv4Addr) -> io::Result<()> {
     setsockopt(fd, c::IPPROTO_IP, c::IP_MULTICAST_IF, to_imr_addr(value))

src/backend/linux_raw/c.rs

@@ -87,9 +87,12 @@ pub(crate) use linux_raw_sys::{
         AF_RXRPC, AF_SECURITY, AF_SNA, AF_TIPC, AF_UNIX, AF_UNSPEC, AF_VSOCK, AF_WANPIPE, AF_X25,
         AF_XDP, IP6T_SO_ORIGINAL_DST, IPPROTO_FRAGMENT, IPPROTO_ICMPV6, IPPROTO_MH,
         IPPROTO_ROUTING, IPV6_ADD_MEMBERSHIP, IPV6_DROP_MEMBERSHIP, IPV6_FREEBIND,
-        IPV6_MULTICAST_HOPS, IPV6_MULTICAST_LOOP, IPV6_RECVTCLASS, IPV6_TCLASS, IPV6_UNICAST_HOPS,
-        IPV6_V6ONLY, IP_ADD_MEMBERSHIP, IP_ADD_SOURCE_MEMBERSHIP, IP_DROP_MEMBERSHIP,
-        IP_DROP_SOURCE_MEMBERSHIP, IP_FREEBIND, IP_MULTICAST_LOOP, IP_MULTICAST_TTL, IP_RECVTOS,
+        IPV6_MULTICAST_HOPS, IPV6_MULTICAST_LOOP, IPV6_PMTUDISC_DO, IPV6_PMTUDISC_DONT,
+        IPV6_PMTUDISC_INTERFACE, IPV6_PMTUDISC_OMIT, IPV6_PMTUDISC_PROBE, IPV6_PMTUDISC_WANT,
+        IPV6_RECVTCLASS, IPV6_TCLASS, IPV6_UNICAST_HOPS, IPV6_V6ONLY, IP_ADD_MEMBERSHIP,
+        IP_ADD_SOURCE_MEMBERSHIP, IP_DROP_MEMBERSHIP, IP_DROP_SOURCE_MEMBERSHIP, IP_FREEBIND,
+        IP_MULTICAST_LOOP, IP_MULTICAST_TTL, IP_PMTUDISC_DO, IP_PMTUDISC_DONT,
+        IP_PMTUDISC_INTERFACE, IP_PMTUDISC_OMIT, IP_PMTUDISC_PROBE, IP_PMTUDISC_WANT, IP_RECVTOS,
         IP_TOS, IP_TTL, MSG_CMSG_CLOEXEC, MSG_CONFIRM, MSG_CTRUNC, MSG_DONTROUTE, MSG_DONTWAIT,
         MSG_EOR, MSG_ERRQUEUE, MSG_MORE, MSG_NOSIGNAL, MSG_OOB, MSG_PEEK, MSG_TRUNC, MSG_WAITALL,
         SCM_CREDENTIALS, SCM_RIGHTS, SHUT_RD, SHUT_RDWR, SHUT_WR, SOCK_DGRAM, SOCK_RAW, SOCK_RDM,

src/backend/linux_raw/net/sockopt.rs

@@ -13,7 +13,7 @@ use crate::fd::BorrowedFd;
 #[cfg(feature = "alloc")]
 use crate::ffi::CStr;
 use crate::io;
-use crate::net::sockopt::Timeout;
+use crate::net::sockopt::{Ipv4PathMtuDiscovery, Ipv6PathMtuDiscovery, Timeout};
 #[cfg(target_os = "linux")]
 use crate::net::xdp::{XdpMmapOffsets, XdpOptionsFlags, XdpRingOffset, XdpStatistics, XdpUmemReg};
 #[cfg(all(target_os = "linux", feature = "time"))]
@@ -29,7 +29,9 @@ use alloc::string::String;
 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_MTU_DISCOVER, IPV6_MULTICAST_IF, IP_MTU, IP_MTU_DISCOVER, IP_MULTICAST_IF,
+};
 #[cfg(target_os = "linux")]
 use linux_raw_sys::xdp::{xdp_mmap_offsets, xdp_statistics, xdp_statistics_v1};
 #[cfg(target_arch = "x86")]
@@ -466,6 +468,32 @@ pub(crate) fn ipv6_mtu(fd: BorrowedFd<'_>) -> io::Result<u32> {
     getsockopt(fd, c::IPPROTO_IPV6, IPV6_MTU)
 }
 
+#[inline]
+pub(crate) fn set_ip_mtu_discover(
+    fd: BorrowedFd<'_>,
+    value: Ipv4PathMtuDiscovery,
+) -> io::Result<()> {
+    setsockopt(fd, c::IPPROTO_IP, IP_MTU_DISCOVER, value)
+}
+
+#[inline]
+pub(crate) fn ip_mtu_discover(fd: BorrowedFd<'_>) -> io::Result<Ipv4PathMtuDiscovery> {
+    getsockopt(fd, c::IPPROTO_IP, IP_MTU_DISCOVER)
+}
+
+#[inline]
+pub(crate) fn set_ipv6_mtu_discover(
+    fd: BorrowedFd<'_>,
+    value: Ipv6PathMtuDiscovery,
+) -> io::Result<()> {
+    setsockopt(fd, c::IPPROTO_IPV6, IPV6_MTU_DISCOVER, value)
+}
+
+#[inline]
+pub(crate) fn ipv6_mtu_discover(fd: BorrowedFd<'_>) -> io::Result<Ipv6PathMtuDiscovery> {
+    getsockopt(fd, c::IPPROTO_IPV6, IPV6_MTU_DISCOVER)
+}
+
 #[inline]
 pub(crate) fn set_ip_multicast_if_with_ifindex(
     fd: BorrowedFd<'_>,

src/net/sockopt.rs

@@ -202,6 +202,110 @@ pub enum Timeout {
     Send = c::SO_SNDTIMEO as _,
 }
 
+/// A type for holding raw integer IPv4 Path MTU Discovery options.
+#[cfg(linux_kernel)]
+pub type RawIpv4PathMtuDiscovery = i32;
+
+/// IPv4 Path MTU Discovery option values (`IP_PMTUDISC_*`) for use with
+/// [`set_ip_mtu_discover`] and [`ip_mtu_discover`].
+///
+/// # References
+/// - [Linux]
+/// - [Linux INET header]
+///
+/// [Linux]: https://man7.org/linux/man-pages/man7/ip.7.html
+/// [Linux INET header]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/uapi/linux/in.h?h=v6.14#n135
+#[cfg(linux_kernel)]
+#[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
+#[repr(transparent)]
+pub struct Ipv4PathMtuDiscovery(RawIpv4PathMtuDiscovery);
+
+#[cfg(linux_kernel)]
+impl Ipv4PathMtuDiscovery {
+    /// `IP_PMTUDISC_DONT`
+    #[doc(alias = "IP_PMTUDISC_DONT")]
+    pub const DONT: Self = Self(c::IP_PMTUDISC_DONT as _);
+    /// `IP_PMTUDISC_WANT`
+    #[doc(alias = "IP_PMTUDISC_WANT")]
+    pub const WANT: Self = Self(c::IP_PMTUDISC_WANT as _);
+    /// `IP_PMTUDISC_DO`
+    #[doc(alias = "IP_PMTUDISC_DO")]
+    pub const DO: Self = Self(c::IP_PMTUDISC_DO as _);
+    /// `IP_PMTUDISC_PROBE`
+    #[doc(alias = "IP_PMTUDISC_PROBE")]
+    pub const PROBE: Self = Self(c::IP_PMTUDISC_PROBE as _);
+    /// `IP_PMTUDISC_INTERFACE`
+    #[doc(alias = "IP_PMTUDISC_INTERFACE")]
+    pub const INTERFACE: Self = Self(c::IP_PMTUDISC_INTERFACE as _);
+    /// `IP_PMTUDISC_OMIT`
+    #[doc(alias = "IP_PMTUDISC_OMIT")]
+    pub const OMIT: Self = Self(c::IP_PMTUDISC_OMIT as _);
+
+    /// Constructs an option from a raw integer.
+    #[inline]
+    pub const fn from_raw(raw: RawIpv4PathMtuDiscovery) -> Self {
+        Self(raw)
+    }
+
+    /// Returns the raw integer for this option.
+    #[inline]
+    pub const fn as_raw(self) -> RawIpv4PathMtuDiscovery {
+        self.0
+    }
+}
+
+/// A type for holding raw integer IPv6 Path MTU Discovery options.
+#[cfg(linux_kernel)]
+pub type RawIpv6PathMtuDiscovery = i32;
+
+/// IPv6 Path MTU Discovery option values (`IPV6_PMTUDISC_*`) for use with
+/// [`set_ipv6_mtu_discover`] and [`ipv6_mtu_discover`].
+///
+/// # References
+/// - [Linux]
+/// - [Linux INET6 header]
+///
+/// [Linux]: https://man7.org/linux/man-pages/man7/ipv6.7.html
+/// [Linux INET6 header]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/uapi/linux/in6.h?h=v6.14#n185
+#[cfg(linux_kernel)]
+#[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
+#[repr(transparent)]
+pub struct Ipv6PathMtuDiscovery(RawIpv6PathMtuDiscovery);
+
+#[cfg(linux_kernel)]
+impl Ipv6PathMtuDiscovery {
+    /// `IPV6_PMTUDISC_DONT`
+    #[doc(alias = "IPV6_PMTUDISC_DONT")]
+    pub const DONT: Self = Self(c::IPV6_PMTUDISC_DONT as _);
+    /// `IPV6_PMTUDISC_WANT`
+    #[doc(alias = "IPV6_PMTUDISC_WANT")]
+    pub const WANT: Self = Self(c::IPV6_PMTUDISC_WANT as _);
+    /// `IPV6_PMTUDISC_DO`
+    #[doc(alias = "IPV6_PMTUDISC_DO")]
+    pub const DO: Self = Self(c::IPV6_PMTUDISC_DO as _);
+    /// `IPV6_PMTUDISC_PROBE`
+    #[doc(alias = "IPV6_PMTUDISC_PROBE")]
+    pub const PROBE: Self = Self(c::IPV6_PMTUDISC_PROBE as _);
+    /// `IPV6_PMTUDISC_INTERFACE`
+    #[doc(alias = "IPV6_PMTUDISC_INTERFACE")]
+    pub const INTERFACE: Self = Self(c::IPV6_PMTUDISC_INTERFACE as _);
+    /// `IPV6_PMTUDISC_OMIT`
+    #[doc(alias = "IPV6_PMTUDISC_OMIT")]
+    pub const OMIT: Self = Self(c::IPV6_PMTUDISC_OMIT as _);
+
+    /// Constructs an option from a raw integer.
+    #[inline]
+    pub const fn from_raw(raw: RawIpv6PathMtuDiscovery) -> Self {
+        Self(raw)
+    }
+
+    /// Returns the raw integer for this option.
+    #[inline]
+    pub const fn as_raw(self) -> RawIpv6PathMtuDiscovery {
+        self.0
+    }
+}
+
 /// `getsockopt(fd, SOL_SOCKET, SO_TYPE)`—Returns the type of a socket.
 ///
 /// See the [module-level documentation] for more.
@@ -690,6 +794,54 @@ pub fn ipv6_mtu<Fd: AsFd>(fd: Fd) -> io::Result<u32> {
     backend::net::sockopt::ipv6_mtu(fd.as_fd())
 }
 
+/// `setsockopt(fd, IPPROTO_IP, IP_MTU_DISCOVER, value)`
+///
+/// See the [module-level documentation] for more.
+///
+/// [module-level documentation]: self#references-for-get_ip_-and-set_ip_-functions
+#[cfg(linux_kernel)]
+#[inline]
+#[doc(alias = "IP_MTU_DISCOVER")]
+pub fn set_ip_mtu_discover<Fd: AsFd>(fd: Fd, value: Ipv4PathMtuDiscovery) -> io::Result<()> {
+    backend::net::sockopt::set_ip_mtu_discover(fd.as_fd(), value)
+}
+
+/// `getsockopt(fd, IPPROTO_IP, IP_MTU_DISCOVER)`
+///
+/// See the [module-level documentation] for more.
+///
+/// [module-level documentation]: self#references-for-get_ip_-and-set_ip_-functions
+#[cfg(linux_kernel)]
+#[inline]
+#[doc(alias = "IP_MTU_DISCOVER")]
+pub fn ip_mtu_discover<Fd: AsFd>(fd: Fd) -> io::Result<Ipv4PathMtuDiscovery> {
+    backend::net::sockopt::ip_mtu_discover(fd.as_fd())
+}
+
+/// `setsockopt(fd, IPPROTO_IPV6, IPV6_MTU_DISCOVER, value)`
+///
+/// See the [module-level documentation] for more.
+///
+/// [module-level documentation]: self#references-for-get_ipv6_-and-set_ipv6_-functions
+#[cfg(linux_kernel)]
+#[inline]
+#[doc(alias = "IPV6_MTU_DISCOVER")]
+pub fn set_ipv6_mtu_discover<Fd: AsFd>(fd: Fd, value: Ipv6PathMtuDiscovery) -> io::Result<()> {
+    backend::net::sockopt::set_ipv6_mtu_discover(fd.as_fd(), value)
+}
+
+/// `getsockopt(fd, IPPROTO_IPV6, IPV6_MTU_DISCOVER)`
+///
+/// See the [module-level documentation] for more.
+///
+/// [module-level documentation]: self#references-for-get_ipv6_-and-set_ipv6_-functions
+#[cfg(linux_kernel)]
+#[inline]
+#[doc(alias = "IPV6_MTU_DISCOVER")]
+pub fn ipv6_mtu_discover<Fd: AsFd>(fd: Fd) -> io::Result<Ipv6PathMtuDiscovery> {
+    backend::net::sockopt::ipv6_mtu_discover(fd.as_fd())
+}
+
 /// `setsockopt(fd, IPPROTO_IP, IP_MULTICAST_IF, value)`
 ///
 /// See the [module-level documentation] for more.

tests/net/sockopt.rs

@@ -570,6 +570,34 @@ fn test_socketopts_ipv6_mtu() {
     }
 }
 
+#[cfg(linux_kernel)]
+#[test]
+fn test_ip_mtu_discover() {
+    crate::init();
+
+    // IPv4
+    {
+        use sockopt::Ipv4PathMtuDiscovery as P;
+
+        let s = rustix::net::socket(AddressFamily::INET, SocketType::DGRAM, None).unwrap();
+        for val in [P::DONT, P::WANT, P::DO, P::PROBE, P::INTERFACE, P::OMIT] {
+            sockopt::set_ip_mtu_discover(&s, val).unwrap();
+            assert_eq!(sockopt::ip_mtu_discover(&s), Ok(val));
+        }
+    }
+
+    // IPv6
+    {
+        use sockopt::Ipv6PathMtuDiscovery as P;
+
+        let s = rustix::net::socket(AddressFamily::INET6, SocketType::DGRAM, None).unwrap();
+        for val in [P::DONT, P::WANT, P::DO, P::PROBE, P::INTERFACE, P::OMIT] {
+            sockopt::set_ipv6_mtu_discover(&s, val).unwrap();
+            assert_eq!(sockopt::ipv6_mtu_discover(&s), Ok(val));
+        }
+    }
+}
+
 #[test]
 fn test_sockopts_multicast_ifv4() {
     crate::init();