windows: Add support for SSH (#29145)

Closes #19892

This PR builds on top of #20587 and improves upon it.

Release Notes:

- N/A

---------

Co-authored-by: Kirill Bulatov <kirill@zed.dev>

crates/net/src/util.rs

@@ -0,0 +1,76 @@
+use std::{
+    io::{Error, ErrorKind, Result},
+    path::Path,
+    sync::Once,
+};
+
+use windows::Win32::Networking::WinSock::{
+    ADDRESS_FAMILY, AF_UNIX, SOCKADDR_UN, SOCKET_ERROR, WSAGetLastError, WSAStartup,
+};
+
+pub(crate) fn init() {
+    static ONCE: Once = Once::new();
+
+    ONCE.call_once(|| unsafe {
+        let mut wsa_data = std::mem::zeroed();
+        let result = WSAStartup(0x202, &mut wsa_data);
+        if result != 0 {
+            panic!("WSAStartup failed: {}", result);
+        }
+    });
+}
+
+// https://devblogs.microsoft.com/commandline/af_unix-comes-to-windows/
+pub(crate) fn sockaddr_un<P: AsRef<Path>>(path: P) -> Result<(SOCKADDR_UN, usize)> {
+    let mut addr = SOCKADDR_UN::default();
+    addr.sun_family = ADDRESS_FAMILY(AF_UNIX);
+
+    let bytes = path
+        .as_ref()
+        .to_str()
+        .map(|s| s.as_bytes())
+        .ok_or(ErrorKind::InvalidInput)?;
+
+    if bytes.contains(&0) {
+        return Err(Error::new(
+            ErrorKind::InvalidInput,
+            "paths may not contain interior null bytes",
+        ));
+    }
+    if bytes.len() >= addr.sun_path.len() {
+        return Err(Error::new(
+            ErrorKind::InvalidInput,
+            "path must be shorter than SUN_LEN",
+        ));
+    }
+
+    unsafe {
+        std::ptr::copy_nonoverlapping(
+            bytes.as_ptr(),
+            addr.sun_path.as_mut_ptr().cast(),
+            bytes.len(),
+        );
+    }
+
+    let mut len = sun_path_offset(&addr) + bytes.len();
+    match bytes.first() {
+        Some(&0) | None => {}
+        Some(_) => len += 1,
+    }
+    Ok((addr, len))
+}
+
+pub(crate) fn map_ret(ret: i32) -> Result<usize> {
+    if ret == SOCKET_ERROR {
+        Err(Error::from_raw_os_error(unsafe { WSAGetLastError().0 }))
+    } else {
+        Ok(ret as usize)
+    }
+}
+
+fn sun_path_offset(addr: &SOCKADDR_UN) -> usize {
+    // Work with an actual instance of the type since using a null pointer is UB
+    let base = addr as *const _ as usize;
+    let path = &addr.sun_path as *const _ as usize;
+    path - base
+}