feat: add dont_frag option

Signed-off-by: loongtao.zhang <[email protected]>

Author: cathaysia

src/socket.rs

@@ -1615,6 +1615,41 @@ impl Socket {
                 .map(|recv_tos| recv_tos > 0)
         }
     }
+
+    /// Set value for `IP_DONTFRAG` option of this socket
+    pub fn dont_frag(&self) -> io::Result<bool> {
+        unsafe {
+            #[cfg(target_os = "macos")]
+            return getsockopt::<c_int>(self.as_raw(), sys::IPPROTO_IP, libc::IP_DONTFRAG)
+                .map(|dont_frag| dont_frag > 0);
+            #[cfg(not(target_os = "macos"))]
+            return getsockopt::<c_int>(self.as_raw(), sys::IPPROTO_IP, sys::IP_MTU_DISCOVER)
+                .map(|dont_frag| dont_frag == 0);
+        }
+    }
+    /// Set value for `IP_DONTFRAG` option on this socket
+    pub fn set_dont_frag(&self, dont_frag: bool) -> io::Result<()> {
+        unsafe {
+            #[cfg(target_os = "macos")]
+            return setsockopt(
+                self.as_raw(),
+                sys::IPPROTO_IP,
+                libc::IP_DONTFRAG,
+                dont_frag as c_int,
+            );
+            #[cfg(not(target_os = "macos"))]
+            return setsockopt(
+                self.as_raw(),
+                sys::IPPROTO_IP,
+                sys::IP_MTU_DISCOVER,
+                if dont_frag {
+                    sys::IP_PMTUDISC_DONT
+                } else {
+                    sys::IP_PMTUDISC_DO
+                },
+            );
+        };
+    }
 }
 
 /// Socket options for IPv6 sockets, get/set using `IPPROTO_IPV6`.
@@ -2015,6 +2050,42 @@ impl Socket {
             )
         }
     }
+
+    /// Get value for `IP_DONTFRAG` option on this socket.
+    pub fn dont_frag_v6(&self) -> io::Result<bool> {
+        unsafe {
+            #[cfg(target_os = "macos")]
+            return getsockopt::<c_int>(self.as_raw(), sys::IPPROTO_IPV6, libc::IPV6_DONTFRAG)
+                .map(|dont_frag| dont_frag > 0);
+            #[cfg(not(target_os = "macos"))]
+            return getsockopt::<c_int>(self.as_raw(), sys::IPPROTO_IPV6, sys::IPV6_MTU_DISCOVER)
+                .map(|dont_frag| dont_frag == sys::IP_PMTUDISC_DONT);
+        }
+    }
+
+    /// Set value for `IP_DONTFRAG` option on this socket
+    pub fn set_dont_frag_v6(&self, dont_frag: bool) -> io::Result<()> {
+        unsafe {
+            #[cfg(target_os = "macos")]
+            return setsockopt(
+                self.as_raw(),
+                sys::IPPROTO_IPV6,
+                libc::IPV6_DONTFRAG,
+                dont_frag as c_int,
+            );
+            #[cfg(not(target_os = "macos"))]
+            setsockopt(
+                self.as_raw(),
+                sys::IPPROTO_IPV6,
+                sys::IPV6_MTU_DISCOVER,
+                if dont_frag {
+                    sys::IP_PMTUDISC_DONT
+                } else {
+                    sys::IP_PMTUDISC_DO
+                },
+            )
+        }
+    }
 }
 
 /// Socket options for TCP sockets, get/set using `IPPROTO_TCP`.

src/sys/unix.rs

@@ -204,6 +204,10 @@ pub(crate) use libc::{
     SO_BROADCAST, SO_ERROR, SO_KEEPALIVE, SO_RCVBUF, SO_RCVTIMEO, SO_REUSEADDR, SO_SNDBUF,
     SO_SNDTIMEO, SO_TYPE, TCP_NODELAY,
 };
+
+#[cfg(not(target_os = "macos"))]
+pub(crate) use libc::{IPV6_MTU_DISCOVER, IP_MTU_DISCOVER, IP_PMTUDISC_DO, IP_PMTUDISC_DONT};
+
 #[cfg(not(any(
     target_os = "dragonfly",
     target_os = "haiku",

src/sys/windows.rs

@@ -22,9 +22,10 @@ use std::{process, ptr, slice};
 use windows_sys::Win32::Foundation::{SetHandleInformation, HANDLE, HANDLE_FLAG_INHERIT};
 use windows_sys::Win32::Networking::WinSock::{
     self, tcp_keepalive, FIONBIO, IN6_ADDR, IN6_ADDR_0, INVALID_SOCKET, IN_ADDR, IN_ADDR_0,
-    POLLERR, POLLHUP, POLLRDNORM, POLLWRNORM, SD_BOTH, SD_RECEIVE, SD_SEND, SIO_KEEPALIVE_VALS,
-    SOCKET_ERROR, WSABUF, WSAEMSGSIZE, WSAESHUTDOWN, WSAPOLLFD, WSAPROTOCOL_INFOW,
-    WSA_FLAG_NO_HANDLE_INHERIT, WSA_FLAG_OVERLAPPED,
+    IPV6_MTU_DISCOVER, IP_MTU_DISCOVER, IP_PMTUDISC_DO, IP_PMTUDISC_DONT, POLLERR, POLLHUP,
+    POLLRDNORM, POLLWRNORM, SD_BOTH, SD_RECEIVE, SD_SEND, SIO_KEEPALIVE_VALS, SOCKET_ERROR, WSABUF,
+    WSAEMSGSIZE, WSAESHUTDOWN, WSAPOLLFD, WSAPROTOCOL_INFOW, WSA_FLAG_NO_HANDLE_INHERIT,
+    WSA_FLAG_OVERLAPPED,
 };
 #[cfg(feature = "all")]
 use windows_sys::Win32::Networking::WinSock::{

tests/socket.rs

@@ -1350,6 +1350,11 @@ test!(
 #[cfg(not(target_os = "redox"))]
 test!(out_of_band_inline, set_out_of_band_inline(true));
 test!(reuse_address, set_reuse_address(true));
+test!(IPv4 dont_frag, set_dont_frag(true));
+// TODO: macos can only set on udp socket.
+#[cfg(not(target_os = "macos"))]
+test!(IPv6 dont_frag_v6, set_dont_frag_v6(true));
+
 #[cfg(all(
     feature = "all",
     not(any(windows, target_os = "solaris", target_os = "illumos"))