Add connect_from methods to TcpStream

library/std/src/net/tcp.rs

@@ -157,6 +157,21 @@ impl TcpStream {
         super::each_addr(addr, net_imp::TcpStream::connect).map(TcpStream)
     }
 
+    /// Opens a TCP connection to a remote host using the specified local address.
+    ///
+    /// `addr` is an address of the remote host. Anything which implements
+    /// [`ToSocketAddrs`] trait can be supplied for the address; see this trait
+    /// documentation for concrete examples.
+    ///
+    /// If `addr` yields multiple addresses, `connect_from` will be attempted with
+    /// each of the addresses until a connection is successful. If none of
+    /// the addresses result in a successful connection, the error returned from
+    /// the last connection attempt (the last address) is returned.
+    #[unstable(feature = "tcpstream_connect_from", issue = "115710")]
+    pub fn connect_from<A: ToSocketAddrs>(from: &SocketAddr, addr: A) -> io::Result<TcpStream> {
+        super::each_addr(addr, |addr| net_imp::TcpStream::connect_from(from, addr)).map(TcpStream)
+    }
+
     /// Opens a TCP connection to a remote host with a timeout.
     ///
     /// Unlike `connect`, `connect_timeout` takes a single [`SocketAddr`] since
@@ -173,6 +188,21 @@ impl TcpStream {
         net_imp::TcpStream::connect_timeout(addr, timeout).map(TcpStream)
     }
 
+    /// Opens a TCP connection to a remote host using the specified local address with a timeout.
+    ///
+    /// Unlike `connect_from`, `connect_from_timeout` takes a single [`SocketAddr`] since
+    /// timeout must be applied to individual addresses.
+    ///
+    /// It is an error to pass a zero `Duration` to this function.
+    #[unstable(feature = "tcpstream_connect_from", issue = "115710")]
+    pub fn connect_from_timeout(
+        from: &SocketAddr,
+        addr: &SocketAddr,
+        timeout: Duration,
+    ) -> io::Result<TcpStream> {
+        net_imp::TcpStream::connect_from_timeout(from, addr, timeout).map(TcpStream)
+    }
+
     /// Returns the socket address of the remote peer of this TCP connection.
     ///
     /// # Examples

library/std/src/sys_common/net.rs

@@ -231,6 +231,21 @@ impl TcpStream {
         Ok(TcpStream { inner: sock })
     }
 
+    pub fn connect_from(from: &SocketAddr, addr: io::Result<&SocketAddr>) -> io::Result<TcpStream> {
+        let addr = addr?;
+
+        init();
+
+        let sock = Socket::new(addr, c::SOCK_STREAM)?;
+
+        let (from, len) = from.into_inner();
+        cvt(unsafe { c::bind(sock.as_raw(), from.as_ptr(), len as _) })?;
+
+        let (addr, len) = addr.into_inner();
+        cvt_r(|| unsafe { c::connect(sock.as_raw(), addr.as_ptr(), len) })?;
+        Ok(TcpStream { inner: sock })
+    }
+
     pub fn connect_timeout(addr: &SocketAddr, timeout: Duration) -> io::Result<TcpStream> {
         init();
 
@@ -239,6 +254,22 @@ impl TcpStream {
         Ok(TcpStream { inner: sock })
     }
 
+    pub fn connect_from_timeout(
+        from: &SocketAddr,
+        addr: &SocketAddr,
+        timeout: Duration,
+    ) -> io::Result<TcpStream> {
+        init();
+
+        let sock = Socket::new(addr, c::SOCK_STREAM)?;
+
+        let (from, len) = from.into_inner();
+        cvt(unsafe { c::bind(sock.as_raw(), from.as_ptr(), len as _) })?;
+
+        sock.connect_timeout(addr, timeout)?;
+        Ok(TcpStream { inner: sock })
+    }
+
     #[inline]
     pub fn socket(&self) -> &Socket {
         &self.inner