Replace unsafe code with socket2

talpid-tunnel-config-client/Cargo.toml

@@ -26,7 +26,7 @@ pqc_kyber = { version = "0.4.0", features = ["std", "kyber1024", "zeroize"] }
 zeroize = "1.5.7"
 
 [target.'cfg(unix)'.dependencies]
-libc = "0.2"
+socket2 = { version = "0.5.3", features = ["all"] }
 
 [target.'cfg(windows)'.dependencies.windows-sys]
 workspace = true

talpid-tunnel-config-client/src/socket.rs

@@ -3,15 +3,13 @@
 
 use std::io;
 use std::net::SocketAddr;
-use tokio::net::TcpSocket as StdTcpSocket;
+use tokio::net::TcpSocket as TokioTcpSocket;
 use tokio::net::TcpStream;
 
 #[cfg(unix)]
 mod sys {
     use super::*;
-
-    pub use libc::{setsockopt, socklen_t, IPPROTO_TCP, TCP_MAXSEG};
-    pub use std::os::fd::{AsRawFd, RawFd};
+    use socket2::{Domain, Protocol, Socket, Type};
 
     /// MTU to set on the tunnel config client socket. We want a low value to prevent fragmentation.
     /// Especially on Android, we've found that the real MTU is often lower than the default MTU, and
@@ -21,39 +19,28 @@ mod sys {
     const CONFIG_CLIENT_MTU: u16 = 576;
 
     pub struct TcpSocket {
-        socket: StdTcpSocket,
+        socket: Socket,
     }
 
     impl TcpSocket {
         pub fn new() -> io::Result<Self> {
-            let socket = StdTcpSocket::new_v4()?;
-            try_set_tcp_sock_mtu(socket.as_raw_fd());
+            let socket = Socket::new(Domain::IPV4, Type::STREAM, Some(Protocol::TCP))?;
+            try_set_tcp_sock_mtu(&socket);
+            socket.set_nonblocking(true)?;
             Ok(Self { socket })
         }
 
         pub async fn connect(self, addr: SocketAddr) -> io::Result<TcpStream> {
-            self.socket.connect(addr).await
+            let socket = TokioTcpSocket::from_std_stream(self.socket.into());
+            socket.connect(addr).await
         }
     }
 
-    fn try_set_tcp_sock_mtu(sock: RawFd) {
+    fn try_set_tcp_sock_mtu(sock: &Socket) {
         let mss = desired_mss();
         log::debug!("Tunnel config TCP socket MSS: {mss}");
-
-        let result = unsafe {
-            setsockopt(
-                sock,
-                IPPROTO_TCP,
-                TCP_MAXSEG,
-                &mss as *const _ as _,
-                socklen_t::try_from(std::mem::size_of_val(&mss)).unwrap(),
-            )
-        };
-        if result != 0 {
-            log::error!(
-                "Failed to set MSS on tunnel config TCP socket: {}",
-                std::io::Error::last_os_error()
-            );
+        if let Err(error) = sock.set_mss(mss) {
+            log::error!("Failed to set MSS on tunnel config TCP socket: {}", error);
         }
     }
 
@@ -70,13 +57,13 @@ mod sys {
     use super::*;
 
     pub struct TcpSocket {
-        socket: StdTcpSocket,
+        socket: TokioTcpSocket,
     }
 
     impl TcpSocket {
         pub fn new() -> io::Result<Self> {
             Ok(Self {
-                socket: StdTcpSocket::new_v4()?,
+                socket: TokioTcpSocket::new_v4()?,
             })
         }