socket2/
sockref.rs

1use std::fmt;
2use std::marker::PhantomData;
3use std::mem::ManuallyDrop;
4use std::ops::Deref;
5#[cfg(unix)]
6use std::os::fd::{AsFd, AsRawFd, FromRawFd};
7#[cfg(windows)]
8use std::os::windows::io::{AsRawSocket, AsSocket, FromRawSocket};
9
10use crate::Socket;
11
12/// A reference to a [`Socket`] that can be used to configure socket types other
13/// than the `Socket` type itself.
14///
15/// This allows for example a [`TcpStream`], found in the standard library, to
16/// be configured using all the additional methods found in the [`Socket`] API.
17///
18/// `SockRef` can be created from any socket type that implements [`AsFd`]
19/// (Unix) or [`AsSocket`] (Windows) using the [`From`] implementation.
20///
21/// [`TcpStream`]: std::net::TcpStream
22// Don't use intra-doc links because they won't build on every platform.
23/// [`AsFd`]: https://doc.rust-lang.org/stable/std/os/fd/trait.AsFd.html
24/// [`AsSocket`]: https://doc.rust-lang.org/stable/std/os/windows/io/trait.AsSocket.html
25///
26/// # Examples
27///
28/// Below is an example of converting a [`TcpStream`] into a [`SockRef`].
29///
30/// ```
31/// use std::net::{TcpStream, SocketAddr};
32///
33/// use socket2::SockRef;
34///
35/// # fn main() -> Result<(), Box<dyn std::error::Error>> {
36/// // Create `TcpStream` from the standard library.
37/// let address: SocketAddr = "127.0.0.1:1234".parse()?;
38/// # let b1 = std::sync::Arc::new(std::sync::Barrier::new(2));
39/// # let b2 = b1.clone();
40/// # let handle = std::thread::spawn(move || {
41/// #    let listener = std::net::TcpListener::bind(address).unwrap();
42/// #    b2.wait();
43/// #    let (stream, _) = listener.accept().unwrap();
44/// #    std::thread::sleep(std::time::Duration::from_millis(10));
45/// #    drop(stream);
46/// # });
47/// # b1.wait();
48/// let stream = TcpStream::connect(address)?;
49///
50/// // Create a `SockRef`erence to the stream.
51/// let socket_ref = SockRef::from(&stream);
52/// // Use `Socket::set_tcp_nodelay` on the stream.
53/// socket_ref.set_tcp_nodelay(true)?;
54/// drop(socket_ref);
55///
56/// assert_eq!(stream.nodelay()?, true);
57/// # handle.join().unwrap();
58/// # Ok(())
59/// # }
60/// ```
61pub struct SockRef<'s> {
62    /// Because this is a reference we don't own the `Socket`, however `Socket`
63    /// closes itself when dropped, so we use `ManuallyDrop` to prevent it from
64    /// closing itself.
65    socket: ManuallyDrop<Socket>,
66    /// Because we don't own the socket we need to ensure the socket remains
67    /// open while we have a "reference" to it, the lifetime `'s` ensures this.
68    _lifetime: PhantomData<&'s Socket>,
69}
70
71impl<'s> Deref for SockRef<'s> {
72    type Target = Socket;
73
74    fn deref(&self) -> &Self::Target {
75        &self.socket
76    }
77}
78
79/// On Windows, a corresponding `From<&impl AsSocket>` implementation exists.
80#[cfg(unix)]
81impl<'s, S> From<&'s S> for SockRef<'s>
82where
83    S: AsFd,
84{
85    /// The caller must ensure `S` is actually a socket.
86    fn from(socket: &'s S) -> Self {
87        let fd = socket.as_fd().as_raw_fd();
88        assert!(fd >= 0);
89        SockRef {
90            socket: ManuallyDrop::new(unsafe { Socket::from_raw_fd(fd) }),
91            _lifetime: PhantomData,
92        }
93    }
94}
95
96/// On Unix, a corresponding `From<&impl AsFd>` implementation exists.
97#[cfg(windows)]
98impl<'s, S> From<&'s S> for SockRef<'s>
99where
100    S: AsSocket,
101{
102    /// See the `From<&impl AsFd>` implementation.
103    fn from(socket: &'s S) -> Self {
104        let socket = socket.as_socket().as_raw_socket();
105        assert!(socket != windows_sys::Win32::Networking::WinSock::INVALID_SOCKET as _);
106        SockRef {
107            socket: ManuallyDrop::new(unsafe { Socket::from_raw_socket(socket) }),
108            _lifetime: PhantomData,
109        }
110    }
111}
112
113impl fmt::Debug for SockRef<'_> {
114    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
115        f.debug_struct("SockRef")
116            .field("raw", &self.socket.as_raw())
117            .field("local_addr", &self.socket.local_addr().ok())
118            .field("peer_addr", &self.socket.peer_addr().ok())
119            .finish()
120    }
121}
socket2/sockref.rs

socket2/
sockref.rs
