Add TCP retries to Windows

Author: keithmattix

src/lib.rs

@@ -441,7 +441,6 @@ pub struct TcpKeepalive {
         target_os = "openbsd",
         target_os = "redox",
         target_os = "solaris",
-        target_os = "windows",
         target_os = "nto",
         target_os = "espidf",
         target_os = "vita",
@@ -470,7 +469,6 @@ impl TcpKeepalive {
                 target_os = "openbsd",
                 target_os = "redox",
                 target_os = "solaris",
-                target_os = "windows",
                 target_os = "nto",
                 target_os = "espidf",
                 target_os = "vita",
@@ -548,6 +546,7 @@ impl TcpKeepalive {
             target_os = "tvos",
             target_os = "watchos",
             target_os = "cygwin",
+            target_os = "windows",
         )
     ))]
     pub const fn with_retries(self, retries: u32) -> Self {

src/socket.rs

@@ -2116,6 +2116,7 @@ impl Socket {
             target_os = "tvos",
             target_os = "watchos",
             target_os = "cygwin",
+            target_os = "windows",
         )
     ))]
     pub fn keepalive_retries(&self) -> io::Result<u32> {

src/sys/windows.rs

@@ -59,6 +59,9 @@ pub(crate) const SOCK_SEQPACKET: c_int =
 pub(crate) use windows_sys::Win32::Networking::WinSock::{
     IPPROTO_ICMP, IPPROTO_ICMPV6, IPPROTO_TCP, IPPROTO_UDP,
 };
+
+#[cfg(feature = "all")]
+pub(crate) use windows_sys::Win32::Networking::WinSock::TCP_KEEPCNT;
 // Used in `SockAddr`.
 pub(crate) use windows_sys::Win32::Networking::WinSock::{
     SOCKADDR as sockaddr, SOCKADDR_IN as sockaddr_in, SOCKADDR_IN6 as sockaddr_in6,
@@ -737,17 +740,18 @@ fn into_ms(duration: Option<Duration>) -> u32 {
 }
 
 pub(crate) fn set_tcp_keepalive(socket: Socket, keepalive: &TcpKeepalive) -> io::Result<()> {
-    let mut keepalive = tcp_keepalive {
+    let mut tcp_keepalive = tcp_keepalive {
         onoff: 1,
         keepalivetime: into_ms(keepalive.time),
         keepaliveinterval: into_ms(keepalive.interval),
     };
+
     let mut out = 0;
     syscall!(
         WSAIoctl(
             socket,
             SIO_KEEPALIVE_VALS,
-            &mut keepalive as *mut _ as *mut _,
+            &mut tcp_keepalive as *mut _ as *mut _,
             size_of::<tcp_keepalive>() as _,
             ptr::null_mut(),
             0,
@@ -757,8 +761,18 @@ pub(crate) fn set_tcp_keepalive(socket: Socket, keepalive: &TcpKeepalive) -> io:
         ),
         PartialEq::eq,
         SOCKET_ERROR
-    )
-    .map(|_| ())
+    )?;
+    if let Some(retries) = keepalive.retries {
+        unsafe {
+            setsockopt(
+                socket,
+                WinSock::IPPROTO_TCP,
+                WinSock::TCP_KEEPCNT,
+                retries as c_int,
+            )?
+        }
+    }
+    Ok(())
 }
 
 /// Caller must ensure `T` is the correct type for `level` and `optname`.

tests/socket.rs

@@ -900,6 +900,7 @@ fn tcp_keepalive() {
             target_os = "netbsd",
             target_os = "tvos",
             target_os = "watchos",
+            target_os = "windows"
         )
     ))]
     let params = params.with_retries(10);
@@ -950,6 +951,7 @@ fn tcp_keepalive() {
             target_os = "netbsd",
             target_os = "tvos",
             target_os = "watchos",
+            target_os = "windows",
         )
     ))]
     assert_eq!(socket.keepalive_retries().unwrap(), 10);