doc additions

library/std/src/os/unix/net/datagram.rs

@@ -838,6 +838,25 @@ impl UnixDatagram {
         self.0.passcred()
     }
 
+    /// Set the id of the socket for network filtering purpose
+    /// and is only a setter.
+    ///
+    /// ```no_run
+    /// #![feature(unix_set_mark)]
+    /// use std::os::unix::net::UnixDatagram;
+    ///
+    /// fn main() -> std::io::Result<()> {
+    ///     let sock = UnixDatagram::unbound()?;
+    ///     sock.set_mark(32 as u32).expect("set_mark function failed");
+    ///     Ok(())
+    /// }
+    /// ```
+    #[cfg(any(doc, target_os = "linux", target_os = "freebsd", target_os = "openbsd",))]
+    #[unstable(feature = "unix_set_mark", issue = "none")]
+    pub fn set_mark(&self, mark: u32) -> io::Result<()> {
+        self.0.set_mark(mark)
+    }
+
     /// Returns the value of the `SO_ERROR` option.
     ///
     /// # Examples

library/std/src/os/unix/net/stream.rs

@@ -424,7 +424,20 @@ impl UnixStream {
         self.0.passcred()
     }
 
-    #[cfg(any(doc, target_os = "linux", target_os = "freebsd",))]
+    /// Set the id of the socket for network filtering purpose
+    /// and is only a setter.
+    ///
+    /// ```no_run
+    /// #![feature(unix_set_mark)]
+    /// use std::os::unix::net::UnixStream;
+    ///
+    /// fn main() -> std::io::Result<()> {
+    ///     let sock = UnixStream::connect("/tmp/sock")?;
+    ///     sock.set_mark(32 as u32).expect("set_mark function failed");
+    ///     Ok(())
+    /// }
+    /// ```
+    #[cfg(any(doc, target_os = "linux", target_os = "freebsd", target_os = "openbsd",))]
     #[unstable(feature = "unix_set_mark", issue = "none")]
     pub fn set_mark(&self, mark: u32) -> io::Result<()> {
         self.0.set_mark(mark)

library/std/src/sys/unix/net.rs

@@ -437,6 +437,11 @@ impl Socket {
         setsockopt(self, libc::SOL_SOCKET, libc::SO_USER_COOKIE, mark)
     }
 
+    #[cfg(target_os = "openbsd")]
+    pub fn set_mark(&self, mark: u32) -> io::Result<()> {
+        setsockopt(self, libc::SOL_SOCKET, libc::SO_RTABLE, mark as libc::c_int)
+    }
+
     pub fn take_error(&self) -> io::Result<Option<io::Error>> {
         let raw: c_int = getsockopt(self, libc::SOL_SOCKET, libc::SO_ERROR)?;
         if raw == 0 { Ok(None) } else { Ok(Some(io::Error::from_raw_os_error(raw as i32))) }