add test and a get method

Author: pepinns

src/socket.rs

@@ -900,16 +900,24 @@ impl Socket {
     /// requires that this option be set on the redirected socket.
     /// this feature is only available on linux
     #[cfg(any(target_os = "linux"))]
-    pub fn set_ip_transparent(&self) -> io::Result<()> {
+    pub fn set_ip_transparent(&self, transparent: bool) -> io::Result<()> {
         unsafe {
             setsockopt(
                 self.inner,
                 sys::IPPROTO_IP,
                 libc::IP_TRANSPARENT,
-                1 as c_int,
+                transparent as c_int,
             )
         }
     }
+    /// Get whether the IP_TRANSPARENT is set for this socket.
+    #[cfg(any(target_os = "linux"))]
+    pub fn ip_transparent(&self) -> io::Result<bool> {
+        unsafe {
+            getsockopt::<c_int>(self.inner, sys::IPPROTO_IP, libc::IP_TRANSPARENT)
+                .map(|transparent| transparent != 0)
+        }
+    }
 
     /// Get the value of the `SO_SNDBUF` option on this socket.
     ///

tests/socket.rs

@@ -1047,6 +1047,12 @@ test!(
     mss,
     set_mss(256)
 );
+#[cfg(any(target_os = "linux"))]
+test!(
+    #[ignore = "setting `IP_TRANSPARENT` requires the `CAP_NET_ADMIN` capability (works when running as root)"]
+    ip_transparent,
+    set_ip_transparent(true)
+);
 #[cfg(all(feature = "all", any(target_os = "fuchsia", target_os = "linux")))]
 test!(
     #[ignore = "setting `SO_MARK` requires the `CAP_NET_ADMIN` capability (works when running as root)"]