Adding upstream version 115.7.0esr.upstream/115.7.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

6 files changed, 3297 insertions, 0 deletions

diff --git a/third_party/rust/tokio/src/net/tcp/listener.rs b/third_party/rust/tokio/src/net/tcp/listener.rs
new file mode 100644
index 0000000000..8aecb21aaa
--- /dev/null
+++ b/third_party/rust/tokio/src/net/tcp/listener.rs
@@ -0,0 +1,397 @@
+use crate::io::{Interest, PollEvented};
+use crate::net::tcp::TcpStream;
+use crate::net::{to_socket_addrs, ToSocketAddrs};
+
+use std::convert::TryFrom;
+use std::fmt;
+use std::io;
+use std::net::{self, SocketAddr};
+use std::task::{Context, Poll};
+
+cfg_net! {
+    /// A TCP socket server, listening for connections.
+    ///
+    /// You can accept a new connection by using the [`accept`](`TcpListener::accept`)
+    /// method.
+    ///
+    /// A `TcpListener` can be turned into a `Stream` with [`TcpListenerStream`].
+    ///
+    /// [`TcpListenerStream`]: https://docs.rs/tokio-stream/0.1/tokio_stream/wrappers/struct.TcpListenerStream.html
+    ///
+    /// # Errors
+    ///
+    /// Note that accepting a connection can lead to various errors and not all
+    /// of them are necessarily fatal ‒ for example having too many open file
+    /// descriptors or the other side closing the connection while it waits in
+    /// an accept queue. These would terminate the stream if not handled in any
+    /// way.
+    ///
+    /// # Examples
+    ///
+    /// Using `accept`:
+    /// ```no_run
+    /// use tokio::net::TcpListener;
+    ///
+    /// use std::io;
+    ///
+    /// async fn process_socket<T>(socket: T) {
+    ///     # drop(socket);
+    ///     // do work with socket here
+    /// }
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let listener = TcpListener::bind("127.0.0.1:8080").await?;
+    ///
+    ///     loop {
+    ///         let (socket, _) = listener.accept().await?;
+    ///         process_socket(socket).await;
+    ///     }
+    /// }
+    /// ```
+    pub struct TcpListener {
+        io: PollEvented<mio::net::TcpListener>,
+    }
+}
+
+impl TcpListener {
+    /// Creates a new TcpListener, which will be bound to the specified address.
+    ///
+    /// The returned listener is ready for accepting connections.
+    ///
+    /// Binding with a port number of 0 will request that the OS assigns a port
+    /// to this listener. The port allocated can be queried via the `local_addr`
+    /// method.
+    ///
+    /// The address type can be any implementor of the [`ToSocketAddrs`] trait.
+    /// If `addr` yields multiple addresses, bind will be attempted with each of
+    /// the addresses until one succeeds and returns the listener. If none of
+    /// the addresses succeed in creating a listener, the error returned from
+    /// the last attempt (the last address) is returned.
+    ///
+    /// This function sets the `SO_REUSEADDR` option on the socket.
+    ///
+    /// To configure the socket before binding, you can use the [`TcpSocket`]
+    /// type.
+    ///
+    /// [`ToSocketAddrs`]: trait@crate::net::ToSocketAddrs
+    /// [`TcpSocket`]: struct@crate::net::TcpSocket
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpListener;
+    ///
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let listener = TcpListener::bind("127.0.0.1:2345").await?;
+    ///
+    ///     // use the listener
+    ///
+    ///     # let _ = listener;
+    ///     Ok(())
+    /// }
+    /// ```
+    pub async fn bind<A: ToSocketAddrs>(addr: A) -> io::Result<TcpListener> {
+        let addrs = to_socket_addrs(addr).await?;
+
+        let mut last_err = None;
+
+        for addr in addrs {
+            match TcpListener::bind_addr(addr) {
+                Ok(listener) => return Ok(listener),
+                Err(e) => last_err = Some(e),
+            }
+        }
+
+        Err(last_err.unwrap_or_else(|| {
+            io::Error::new(
+                io::ErrorKind::InvalidInput,
+                "could not resolve to any address",
+            )
+        }))
+    }
+
+    fn bind_addr(addr: SocketAddr) -> io::Result<TcpListener> {
+        let listener = mio::net::TcpListener::bind(addr)?;
+        TcpListener::new(listener)
+    }
+
+    /// Accepts a new incoming connection from this listener.
+    ///
+    /// This function will yield once a new TCP connection is established. When
+    /// established, the corresponding [`TcpStream`] and the remote peer's
+    /// address will be returned.
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. If the method is used as the event in a
+    /// [`tokio::select!`](crate::select) statement and some other branch
+    /// completes first, then it is guaranteed that no new connections were
+    /// accepted by this method.
+    ///
+    /// [`TcpStream`]: struct@crate::net::TcpStream
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpListener;
+    ///
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let listener = TcpListener::bind("127.0.0.1:8080").await?;
+    ///
+    ///     match listener.accept().await {
+    ///         Ok((_socket, addr)) => println!("new client: {:?}", addr),
+    ///         Err(e) => println!("couldn't get client: {:?}", e),
+    ///     }
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    pub async fn accept(&self) -> io::Result<(TcpStream, SocketAddr)> {
+        let (mio, addr) = self
+            .io
+            .registration()
+            .async_io(Interest::READABLE, || self.io.accept())
+            .await?;
+
+        let stream = TcpStream::new(mio)?;
+        Ok((stream, addr))
+    }
+
+    /// Polls to accept a new incoming connection to this listener.
+    ///
+    /// If there is no connection to accept, `Poll::Pending` is returned and the
+    /// current task will be notified by a waker.  Note that on multiple calls
+    /// to `poll_accept`, only the `Waker` from the `Context` passed to the most
+    /// recent call is scheduled to receive a wakeup.
+    pub fn poll_accept(&self, cx: &mut Context<'_>) -> Poll<io::Result<(TcpStream, SocketAddr)>> {
+        loop {
+            let ev = ready!(self.io.registration().poll_read_ready(cx))?;
+
+            match self.io.accept() {
+                Ok((io, addr)) => {
+                    let io = TcpStream::new(io)?;
+                    return Poll::Ready(Ok((io, addr)));
+                }
+                Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+                    self.io.registration().clear_readiness(ev);
+                }
+                Err(e) => return Poll::Ready(Err(e)),
+            }
+        }
+    }
+
+    /// Creates new `TcpListener` from a `std::net::TcpListener`.
+    ///
+    /// This function is intended to be used to wrap a TCP listener from the
+    /// standard library in the Tokio equivalent. The conversion assumes nothing
+    /// about the underlying listener; it is left up to the user to set it in
+    /// non-blocking mode.
+    ///
+    /// This API is typically paired with the `socket2` crate and the `Socket`
+    /// type to build up and customize a listener before it's shipped off to the
+    /// backing event loop. This allows configuration of options like
+    /// `SO_REUSEPORT`, binding to multiple addresses, etc.
+    ///
+    /// # Examples
+    ///
+    /// ```rust,no_run
+    /// use std::error::Error;
+    /// use tokio::net::TcpListener;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> Result<(), Box<dyn Error>> {
+    ///     let std_listener = std::net::TcpListener::bind("127.0.0.1:0")?;
+    ///     std_listener.set_nonblocking(true)?;
+    ///     let listener = TcpListener::from_std(std_listener)?;
+    ///     Ok(())
+    /// }
+    /// ```
+    ///
+    /// # Panics
+    ///
+    /// This function panics if thread-local runtime is not set.
+    ///
+    /// The runtime is usually set implicitly when this function is called
+    /// from a future driven by a tokio runtime, otherwise runtime can be set
+    /// explicitly with [`Runtime::enter`](crate::runtime::Runtime::enter) function.
+    pub fn from_std(listener: net::TcpListener) -> io::Result<TcpListener> {
+        let io = mio::net::TcpListener::from_std(listener);
+        let io = PollEvented::new(io)?;
+        Ok(TcpListener { io })
+    }
+
+    /// Turns a [`tokio::net::TcpListener`] into a [`std::net::TcpListener`].
+    ///
+    /// The returned [`std::net::TcpListener`] will have nonblocking mode set as
+    /// `true`.  Use [`set_nonblocking`] to change the blocking mode if needed.
+    ///
+    /// # Examples
+    ///
+    /// ```rust,no_run
+    /// use std::error::Error;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> Result<(), Box<dyn Error>> {
+    ///     let tokio_listener = tokio::net::TcpListener::bind("127.0.0.1:0").await?;
+    ///     let std_listener = tokio_listener.into_std()?;
+    ///     std_listener.set_nonblocking(false)?;
+    ///     Ok(())
+    /// }
+    /// ```
+    ///
+    /// [`tokio::net::TcpListener`]: TcpListener
+    /// [`std::net::TcpListener`]: std::net::TcpListener
+    /// [`set_nonblocking`]: fn@std::net::TcpListener::set_nonblocking
+    pub fn into_std(self) -> io::Result<std::net::TcpListener> {
+        #[cfg(unix)]
+        {
+            use std::os::unix::io::{FromRawFd, IntoRawFd};
+            self.io
+                .into_inner()
+                .map(|io| io.into_raw_fd())
+                .map(|raw_fd| unsafe { std::net::TcpListener::from_raw_fd(raw_fd) })
+        }
+
+        #[cfg(windows)]
+        {
+            use std::os::windows::io::{FromRawSocket, IntoRawSocket};
+            self.io
+                .into_inner()
+                .map(|io| io.into_raw_socket())
+                .map(|raw_socket| unsafe { std::net::TcpListener::from_raw_socket(raw_socket) })
+        }
+    }
+
+    pub(crate) fn new(listener: mio::net::TcpListener) -> io::Result<TcpListener> {
+        let io = PollEvented::new(listener)?;
+        Ok(TcpListener { io })
+    }
+
+    /// Returns the local address that this listener is bound to.
+    ///
+    /// This can be useful, for example, when binding to port 0 to figure out
+    /// which port was actually bound.
+    ///
+    /// # Examples
+    ///
+    /// ```rust,no_run
+    /// use tokio::net::TcpListener;
+    ///
+    /// use std::io;
+    /// use std::net::{Ipv4Addr, SocketAddr, SocketAddrV4};
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let listener = TcpListener::bind("127.0.0.1:8080").await?;
+    ///
+    ///     assert_eq!(listener.local_addr()?,
+    ///                SocketAddr::V4(SocketAddrV4::new(Ipv4Addr::new(127, 0, 0, 1), 8080)));
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    pub fn local_addr(&self) -> io::Result<SocketAddr> {
+        self.io.local_addr()
+    }
+
+    /// Gets the value of the `IP_TTL` option for this socket.
+    ///
+    /// For more information about this option, see [`set_ttl`].
+    ///
+    /// [`set_ttl`]: method@Self::set_ttl
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpListener;
+    ///
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///    let listener = TcpListener::bind("127.0.0.1:0").await?;
+    ///
+    ///    listener.set_ttl(100).expect("could not set TTL");
+    ///    assert_eq!(listener.ttl()?, 100);
+    ///
+    ///    Ok(())
+    /// }
+    /// ```
+    pub fn ttl(&self) -> io::Result<u32> {
+        self.io.ttl()
+    }
+
+    /// Sets the value for the `IP_TTL` option on this socket.
+    ///
+    /// This value sets the time-to-live field that is used in every packet sent
+    /// from this socket.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpListener;
+    ///
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let listener = TcpListener::bind("127.0.0.1:0").await?;
+    ///
+    ///     listener.set_ttl(100).expect("could not set TTL");
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    pub fn set_ttl(&self, ttl: u32) -> io::Result<()> {
+        self.io.set_ttl(ttl)
+    }
+}
+
+impl TryFrom<net::TcpListener> for TcpListener {
+    type Error = io::Error;
+
+    /// Consumes stream, returning the tokio I/O object.
+    ///
+    /// This is equivalent to
+    /// [`TcpListener::from_std(stream)`](TcpListener::from_std).
+    fn try_from(stream: net::TcpListener) -> Result<Self, Self::Error> {
+        Self::from_std(stream)
+    }
+}
+
+impl fmt::Debug for TcpListener {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.io.fmt(f)
+    }
+}
+
+#[cfg(unix)]
+mod sys {
+    use super::TcpListener;
+    use std::os::unix::prelude::*;
+
+    impl AsRawFd for TcpListener {
+        fn as_raw_fd(&self) -> RawFd {
+            self.io.as_raw_fd()
+        }
+    }
+}
+
+#[cfg(windows)]
+mod sys {
+    use super::TcpListener;
+    use std::os::windows::prelude::*;
+
+    impl AsRawSocket for TcpListener {
+        fn as_raw_socket(&self) -> RawSocket {
+            self.io.as_raw_socket()
+        }
+    }
+}
diff --git a/third_party/rust/tokio/src/net/tcp/mod.rs b/third_party/rust/tokio/src/net/tcp/mod.rs
new file mode 100644
index 0000000000..cb8a8b238b
--- /dev/null
+++ b/third_party/rust/tokio/src/net/tcp/mod.rs
@@ -0,0 +1,14 @@
+//! TCP utility types.
+
+pub(crate) mod listener;
+
+pub(crate) mod socket;
+
+mod split;
+pub use split::{ReadHalf, WriteHalf};
+
+mod split_owned;
+pub use split_owned::{OwnedReadHalf, OwnedWriteHalf, ReuniteError};
+
+pub(crate) mod stream;
+pub(crate) use stream::TcpStream;
diff --git a/third_party/rust/tokio/src/net/tcp/socket.rs b/third_party/rust/tokio/src/net/tcp/socket.rs
new file mode 100644
index 0000000000..171e240189
--- /dev/null
+++ b/third_party/rust/tokio/src/net/tcp/socket.rs
@@ -0,0 +1,690 @@
+use crate::net::{TcpListener, TcpStream};
+
+use std::fmt;
+use std::io;
+use std::net::SocketAddr;
+
+#[cfg(unix)]
+use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
+#[cfg(windows)]
+use std::os::windows::io::{AsRawSocket, FromRawSocket, IntoRawSocket, RawSocket};
+use std::time::Duration;
+
+cfg_net! {
+    /// A TCP socket that has not yet been converted to a `TcpStream` or
+    /// `TcpListener`.
+    ///
+    /// `TcpSocket` wraps an operating system socket and enables the caller to
+    /// configure the socket before establishing a TCP connection or accepting
+    /// inbound connections. The caller is able to set socket option and explicitly
+    /// bind the socket with a socket address.
+    ///
+    /// The underlying socket is closed when the `TcpSocket` value is dropped.
+    ///
+    /// `TcpSocket` should only be used directly if the default configuration used
+    /// by `TcpStream::connect` and `TcpListener::bind` does not meet the required
+    /// use case.
+    ///
+    /// Calling `TcpStream::connect("127.0.0.1:8080")` is equivalent to:
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpSocket;
+    ///
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let addr = "127.0.0.1:8080".parse().unwrap();
+    ///
+    ///     let socket = TcpSocket::new_v4()?;
+    ///     let stream = socket.connect(addr).await?;
+    /// # drop(stream);
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    ///
+    /// Calling `TcpListener::bind("127.0.0.1:8080")` is equivalent to:
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpSocket;
+    ///
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let addr = "127.0.0.1:8080".parse().unwrap();
+    ///
+    ///     let socket = TcpSocket::new_v4()?;
+    ///     // On platforms with Berkeley-derived sockets, this allows to quickly
+    ///     // rebind a socket, without needing to wait for the OS to clean up the
+    ///     // previous one.
+    ///     //
+    ///     // On Windows, this allows rebinding sockets which are actively in use,
+    ///     // which allows “socket hijacking”, so we explicitly don't set it here.
+    ///     // https://docs.microsoft.com/en-us/windows/win32/winsock/using-so-reuseaddr-and-so-exclusiveaddruse
+    ///     socket.set_reuseaddr(true)?;
+    ///     socket.bind(addr)?;
+    ///
+    ///     let listener = socket.listen(1024)?;
+    /// # drop(listener);
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    ///
+    /// Setting socket options not explicitly provided by `TcpSocket` may be done by
+    /// accessing the `RawFd`/`RawSocket` using [`AsRawFd`]/[`AsRawSocket`] and
+    /// setting the option with a crate like [`socket2`].
+    ///
+    /// [`RawFd`]: https://doc.rust-lang.org/std/os/unix/io/type.RawFd.html
+    /// [`RawSocket`]: https://doc.rust-lang.org/std/os/windows/io/type.RawSocket.html
+    /// [`AsRawFd`]: https://doc.rust-lang.org/std/os/unix/io/trait.AsRawFd.html
+    /// [`AsRawSocket`]: https://doc.rust-lang.org/std/os/windows/io/trait.AsRawSocket.html
+    /// [`socket2`]: https://docs.rs/socket2/
+    #[cfg_attr(docsrs, doc(alias = "connect_std"))]
+    pub struct TcpSocket {
+        inner: socket2::Socket,
+    }
+}
+
+impl TcpSocket {
+    /// Creates a new socket configured for IPv4.
+    ///
+    /// Calls `socket(2)` with `AF_INET` and `SOCK_STREAM`.
+    ///
+    /// # Returns
+    ///
+    /// On success, the newly created `TcpSocket` is returned. If an error is
+    /// encountered, it is returned instead.
+    ///
+    /// # Examples
+    ///
+    /// Create a new IPv4 socket and start listening.
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpSocket;
+    ///
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let addr = "127.0.0.1:8080".parse().unwrap();
+    ///     let socket = TcpSocket::new_v4()?;
+    ///     socket.bind(addr)?;
+    ///
+    ///     let listener = socket.listen(128)?;
+    /// # drop(listener);
+    ///     Ok(())
+    /// }
+    /// ```
+    pub fn new_v4() -> io::Result<TcpSocket> {
+        TcpSocket::new(socket2::Domain::IPV4)
+    }
+
+    /// Creates a new socket configured for IPv6.
+    ///
+    /// Calls `socket(2)` with `AF_INET6` and `SOCK_STREAM`.
+    ///
+    /// # Returns
+    ///
+    /// On success, the newly created `TcpSocket` is returned. If an error is
+    /// encountered, it is returned instead.
+    ///
+    /// # Examples
+    ///
+    /// Create a new IPv6 socket and start listening.
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpSocket;
+    ///
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let addr = "[::1]:8080".parse().unwrap();
+    ///     let socket = TcpSocket::new_v6()?;
+    ///     socket.bind(addr)?;
+    ///
+    ///     let listener = socket.listen(128)?;
+    /// # drop(listener);
+    ///     Ok(())
+    /// }
+    /// ```
+    pub fn new_v6() -> io::Result<TcpSocket> {
+        TcpSocket::new(socket2::Domain::IPV6)
+    }
+
+    fn new(domain: socket2::Domain) -> io::Result<TcpSocket> {
+        let ty = socket2::Type::STREAM;
+        #[cfg(any(
+            target_os = "android",
+            target_os = "dragonfly",
+            target_os = "freebsd",
+            target_os = "fuchsia",
+            target_os = "illumos",
+            target_os = "linux",
+            target_os = "netbsd",
+            target_os = "openbsd"
+        ))]
+        let ty = ty.nonblocking();
+        let inner = socket2::Socket::new(domain, ty, Some(socket2::Protocol::TCP))?;
+        #[cfg(not(any(
+            target_os = "android",
+            target_os = "dragonfly",
+            target_os = "freebsd",
+            target_os = "fuchsia",
+            target_os = "illumos",
+            target_os = "linux",
+            target_os = "netbsd",
+            target_os = "openbsd"
+        )))]
+        inner.set_nonblocking(true)?;
+        Ok(TcpSocket { inner })
+    }
+
+    /// Allows the socket to bind to an in-use address.
+    ///
+    /// Behavior is platform specific. Refer to the target platform's
+    /// documentation for more details.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpSocket;
+    ///
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let addr = "127.0.0.1:8080".parse().unwrap();
+    ///
+    ///     let socket = TcpSocket::new_v4()?;
+    ///     socket.set_reuseaddr(true)?;
+    ///     socket.bind(addr)?;
+    ///
+    ///     let listener = socket.listen(1024)?;
+    /// # drop(listener);
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    pub fn set_reuseaddr(&self, reuseaddr: bool) -> io::Result<()> {
+        self.inner.set_reuse_address(reuseaddr)
+    }
+
+    /// Retrieves the value set for `SO_REUSEADDR` on this socket.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpSocket;
+    ///
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let addr = "127.0.0.1:8080".parse().unwrap();
+    ///
+    ///     let socket = TcpSocket::new_v4()?;
+    ///     socket.set_reuseaddr(true)?;
+    ///     assert!(socket.reuseaddr().unwrap());
+    ///     socket.bind(addr)?;
+    ///
+    ///     let listener = socket.listen(1024)?;
+    ///     Ok(())
+    /// }
+    /// ```
+    pub fn reuseaddr(&self) -> io::Result<bool> {
+        self.inner.reuse_address()
+    }
+
+    /// Allows the socket to bind to an in-use port. Only available for unix systems
+    /// (excluding Solaris & Illumos).
+    ///
+    /// Behavior is platform specific. Refer to the target platform's
+    /// documentation for more details.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpSocket;
+    ///
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let addr = "127.0.0.1:8080".parse().unwrap();
+    ///
+    ///     let socket = TcpSocket::new_v4()?;
+    ///     socket.set_reuseport(true)?;
+    ///     socket.bind(addr)?;
+    ///
+    ///     let listener = socket.listen(1024)?;
+    ///     Ok(())
+    /// }
+    /// ```
+    #[cfg(all(unix, not(target_os = "solaris"), not(target_os = "illumos")))]
+    #[cfg_attr(
+        docsrs,
+        doc(cfg(all(unix, not(target_os = "solaris"), not(target_os = "illumos"))))
+    )]
+    pub fn set_reuseport(&self, reuseport: bool) -> io::Result<()> {
+        self.inner.set_reuse_port(reuseport)
+    }
+
+    /// Allows the socket to bind to an in-use port. Only available for unix systems
+    /// (excluding Solaris & Illumos).
+    ///
+    /// Behavior is platform specific. Refer to the target platform's
+    /// documentation for more details.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpSocket;
+    ///
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let addr = "127.0.0.1:8080".parse().unwrap();
+    ///
+    ///     let socket = TcpSocket::new_v4()?;
+    ///     socket.set_reuseport(true)?;
+    ///     assert!(socket.reuseport().unwrap());
+    ///     socket.bind(addr)?;
+    ///
+    ///     let listener = socket.listen(1024)?;
+    ///     Ok(())
+    /// }
+    /// ```
+    #[cfg(all(unix, not(target_os = "solaris"), not(target_os = "illumos")))]
+    #[cfg_attr(
+        docsrs,
+        doc(cfg(all(unix, not(target_os = "solaris"), not(target_os = "illumos"))))
+    )]
+    pub fn reuseport(&self) -> io::Result<bool> {
+        self.inner.reuse_port()
+    }
+
+    /// Sets the size of the TCP send buffer on this socket.
+    ///
+    /// On most operating systems, this sets the `SO_SNDBUF` socket option.
+    pub fn set_send_buffer_size(&self, size: u32) -> io::Result<()> {
+        self.inner.set_send_buffer_size(size as usize)
+    }
+
+    /// Returns the size of the TCP send buffer for this socket.
+    ///
+    /// On most operating systems, this is the value of the `SO_SNDBUF` socket
+    /// option.
+    ///
+    /// Note that if [`set_send_buffer_size`] has been called on this socket
+    /// previously, the value returned by this function may not be the same as
+    /// the argument provided to `set_send_buffer_size`. This is for the
+    /// following reasons:
+    ///
+    /// * Most operating systems have minimum and maximum allowed sizes for the
+    ///   send buffer, and will clamp the provided value if it is below the
+    ///   minimum or above the maximum. The minimum and maximum buffer sizes are
+    ///   OS-dependent.
+    /// * Linux will double the buffer size to account for internal bookkeeping
+    ///   data, and returns the doubled value from `getsockopt(2)`. As per `man
+    ///   7 socket`:
+    ///   > Sets or gets the maximum socket send buffer in bytes. The
+    ///   > kernel doubles this value (to allow space for bookkeeping
+    ///   > overhead) when it is set using `setsockopt(2)`, and this doubled
+    ///   > value is returned by `getsockopt(2)`.
+    ///
+    /// [`set_send_buffer_size`]: #method.set_send_buffer_size
+    pub fn send_buffer_size(&self) -> io::Result<u32> {
+        self.inner.send_buffer_size().map(|n| n as u32)
+    }
+
+    /// Sets the size of the TCP receive buffer on this socket.
+    ///
+    /// On most operating systems, this sets the `SO_RCVBUF` socket option.
+    pub fn set_recv_buffer_size(&self, size: u32) -> io::Result<()> {
+        self.inner.set_recv_buffer_size(size as usize)
+    }
+
+    /// Returns the size of the TCP receive buffer for this socket.
+    ///
+    /// On most operating systems, this is the value of the `SO_RCVBUF` socket
+    /// option.
+    ///
+    /// Note that if [`set_recv_buffer_size`] has been called on this socket
+    /// previously, the value returned by this function may not be the same as
+    /// the argument provided to `set_send_buffer_size`. This is for the
+    /// following reasons:
+    ///
+    /// * Most operating systems have minimum and maximum allowed sizes for the
+    ///   receive buffer, and will clamp the provided value if it is below the
+    ///   minimum or above the maximum. The minimum and maximum buffer sizes are
+    ///   OS-dependent.
+    /// * Linux will double the buffer size to account for internal bookkeeping
+    ///   data, and returns the doubled value from `getsockopt(2)`. As per `man
+    ///   7 socket`:
+    ///   > Sets or gets the maximum socket send buffer in bytes. The
+    ///   > kernel doubles this value (to allow space for bookkeeping
+    ///   > overhead) when it is set using `setsockopt(2)`, and this doubled
+    ///   > value is returned by `getsockopt(2)`.
+    ///
+    /// [`set_recv_buffer_size`]: #method.set_recv_buffer_size
+    pub fn recv_buffer_size(&self) -> io::Result<u32> {
+        self.inner.recv_buffer_size().map(|n| n as u32)
+    }
+
+    /// Sets the linger duration of this socket by setting the SO_LINGER option.
+    ///
+    /// This option controls the action taken when a stream has unsent messages and the stream is
+    /// closed. If SO_LINGER is set, the system shall block the process until it can transmit the
+    /// data or until the time expires.
+    ///
+    /// If SO_LINGER is not specified, and the socket is closed, the system handles the call in a
+    /// way that allows the process to continue as quickly as possible.
+    pub fn set_linger(&self, dur: Option<Duration>) -> io::Result<()> {
+        self.inner.set_linger(dur)
+    }
+
+    /// Reads the linger duration for this socket by getting the `SO_LINGER`
+    /// option.
+    ///
+    /// For more information about this option, see [`set_linger`].
+    ///
+    /// [`set_linger`]: TcpSocket::set_linger
+    pub fn linger(&self) -> io::Result<Option<Duration>> {
+        self.inner.linger()
+    }
+
+    /// Gets the local address of this socket.
+    ///
+    /// Will fail on windows if called before `bind`.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpSocket;
+    ///
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let addr = "127.0.0.1:8080".parse().unwrap();
+    ///
+    ///     let socket = TcpSocket::new_v4()?;
+    ///     socket.bind(addr)?;
+    ///     assert_eq!(socket.local_addr().unwrap().to_string(), "127.0.0.1:8080");
+    ///     let listener = socket.listen(1024)?;
+    ///     Ok(())
+    /// }
+    /// ```
+    pub fn local_addr(&self) -> io::Result<SocketAddr> {
+        self.inner.local_addr().and_then(convert_address)
+    }
+
+    /// Binds the socket to the given address.
+    ///
+    /// This calls the `bind(2)` operating-system function. Behavior is
+    /// platform specific. Refer to the target platform's documentation for more
+    /// details.
+    ///
+    /// # Examples
+    ///
+    /// Bind a socket before listening.
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpSocket;
+    ///
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let addr = "127.0.0.1:8080".parse().unwrap();
+    ///
+    ///     let socket = TcpSocket::new_v4()?;
+    ///     socket.bind(addr)?;
+    ///
+    ///     let listener = socket.listen(1024)?;
+    /// # drop(listener);
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    pub fn bind(&self, addr: SocketAddr) -> io::Result<()> {
+        self.inner.bind(&addr.into())
+    }
+
+    /// Establishes a TCP connection with a peer at the specified socket address.
+    ///
+    /// The `TcpSocket` is consumed. Once the connection is established, a
+    /// connected [`TcpStream`] is returned. If the connection fails, the
+    /// encountered error is returned.
+    ///
+    /// [`TcpStream`]: TcpStream
+    ///
+    /// This calls the `connect(2)` operating-system function. Behavior is
+    /// platform specific. Refer to the target platform's documentation for more
+    /// details.
+    ///
+    /// # Examples
+    ///
+    /// Connecting to a peer.
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpSocket;
+    ///
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let addr = "127.0.0.1:8080".parse().unwrap();
+    ///
+    ///     let socket = TcpSocket::new_v4()?;
+    ///     let stream = socket.connect(addr).await?;
+    /// # drop(stream);
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    pub async fn connect(self, addr: SocketAddr) -> io::Result<TcpStream> {
+        if let Err(err) = self.inner.connect(&addr.into()) {
+            #[cfg(unix)]
+            if err.raw_os_error() != Some(libc::EINPROGRESS) {
+                return Err(err);
+            }
+            #[cfg(windows)]
+            if err.kind() != io::ErrorKind::WouldBlock {
+                return Err(err);
+            }
+        }
+        #[cfg(unix)]
+        let mio = {
+            use std::os::unix::io::{FromRawFd, IntoRawFd};
+
+            let raw_fd = self.inner.into_raw_fd();
+            unsafe { mio::net::TcpStream::from_raw_fd(raw_fd) }
+        };
+
+        #[cfg(windows)]
+        let mio = {
+            use std::os::windows::io::{FromRawSocket, IntoRawSocket};
+
+            let raw_socket = self.inner.into_raw_socket();
+            unsafe { mio::net::TcpStream::from_raw_socket(raw_socket) }
+        };
+
+        TcpStream::connect_mio(mio).await
+    }
+
+    /// Converts the socket into a `TcpListener`.
+    ///
+    /// `backlog` defines the maximum number of pending connections are queued
+    /// by the operating system at any given time. Connection are removed from
+    /// the queue with [`TcpListener::accept`]. When the queue is full, the
+    /// operating-system will start rejecting connections.
+    ///
+    /// [`TcpListener::accept`]: TcpListener::accept
+    ///
+    /// This calls the `listen(2)` operating-system function, marking the socket
+    /// as a passive socket. Behavior is platform specific. Refer to the target
+    /// platform's documentation for more details.
+    ///
+    /// # Examples
+    ///
+    /// Create a `TcpListener`.
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpSocket;
+    ///
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let addr = "127.0.0.1:8080".parse().unwrap();
+    ///
+    ///     let socket = TcpSocket::new_v4()?;
+    ///     socket.bind(addr)?;
+    ///
+    ///     let listener = socket.listen(1024)?;
+    /// # drop(listener);
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    pub fn listen(self, backlog: u32) -> io::Result<TcpListener> {
+        self.inner.listen(backlog as i32)?;
+        #[cfg(unix)]
+        let mio = {
+            use std::os::unix::io::{FromRawFd, IntoRawFd};
+
+            let raw_fd = self.inner.into_raw_fd();
+            unsafe { mio::net::TcpListener::from_raw_fd(raw_fd) }
+        };
+
+        #[cfg(windows)]
+        let mio = {
+            use std::os::windows::io::{FromRawSocket, IntoRawSocket};
+
+            let raw_socket = self.inner.into_raw_socket();
+            unsafe { mio::net::TcpListener::from_raw_socket(raw_socket) }
+        };
+
+        TcpListener::new(mio)
+    }
+
+    /// Converts a [`std::net::TcpStream`] into a `TcpSocket`. The provided
+    /// socket must not have been connected prior to calling this function. This
+    /// function is typically used together with crates such as [`socket2`] to
+    /// configure socket options that are not available on `TcpSocket`.
+    ///
+    /// [`std::net::TcpStream`]: struct@std::net::TcpStream
+    /// [`socket2`]: https://docs.rs/socket2/
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::net::TcpSocket;
+    /// use socket2::{Domain, Socket, Type};
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> std::io::Result<()> {
+    ///
+    ///     let socket2_socket = Socket::new(Domain::IPV4, Type::STREAM, None)?;
+    ///
+    ///     let socket = TcpSocket::from_std_stream(socket2_socket.into());
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    pub fn from_std_stream(std_stream: std::net::TcpStream) -> TcpSocket {
+        #[cfg(unix)]
+        {
+            use std::os::unix::io::{FromRawFd, IntoRawFd};
+
+            let raw_fd = std_stream.into_raw_fd();
+            unsafe { TcpSocket::from_raw_fd(raw_fd) }
+        }
+
+        #[cfg(windows)]
+        {
+            use std::os::windows::io::{FromRawSocket, IntoRawSocket};
+
+            let raw_socket = std_stream.into_raw_socket();
+            unsafe { TcpSocket::from_raw_socket(raw_socket) }
+        }
+    }
+}
+
+fn convert_address(address: socket2::SockAddr) -> io::Result<SocketAddr> {
+    match address.as_socket() {
+        Some(address) => Ok(address),
+        None => Err(io::Error::new(
+            io::ErrorKind::InvalidInput,
+            "invalid address family (not IPv4 or IPv6)",
+        )),
+    }
+}
+
+impl fmt::Debug for TcpSocket {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.inner.fmt(fmt)
+    }
+}
+
+#[cfg(unix)]
+impl AsRawFd for TcpSocket {
+    fn as_raw_fd(&self) -> RawFd {
+        self.inner.as_raw_fd()
+    }
+}
+
+#[cfg(unix)]
+impl FromRawFd for TcpSocket {
+    /// Converts a `RawFd` to a `TcpSocket`.
+    ///
+    /// # Notes
+    ///
+    /// The caller is responsible for ensuring that the socket is in
+    /// non-blocking mode.
+    unsafe fn from_raw_fd(fd: RawFd) -> TcpSocket {
+        let inner = socket2::Socket::from_raw_fd(fd);
+        TcpSocket { inner }
+    }
+}
+
+#[cfg(unix)]
+impl IntoRawFd for TcpSocket {
+    fn into_raw_fd(self) -> RawFd {
+        self.inner.into_raw_fd()
+    }
+}
+
+#[cfg(windows)]
+impl IntoRawSocket for TcpSocket {
+    fn into_raw_socket(self) -> RawSocket {
+        self.inner.into_raw_socket()
+    }
+}
+
+#[cfg(windows)]
+impl AsRawSocket for TcpSocket {
+    fn as_raw_socket(&self) -> RawSocket {
+        self.inner.as_raw_socket()
+    }
+}
+
+#[cfg(windows)]
+impl FromRawSocket for TcpSocket {
+    /// Converts a `RawSocket` to a `TcpStream`.
+    ///
+    /// # Notes
+    ///
+    /// The caller is responsible for ensuring that the socket is in
+    /// non-blocking mode.
+    unsafe fn from_raw_socket(socket: RawSocket) -> TcpSocket {
+        let inner = socket2::Socket::from_raw_socket(socket);
+        TcpSocket { inner }
+    }
+}
diff --git a/third_party/rust/tokio/src/net/tcp/split.rs b/third_party/rust/tokio/src/net/tcp/split.rs
new file mode 100644
index 0000000000..0e02928495
--- /dev/null
+++ b/third_party/rust/tokio/src/net/tcp/split.rs
@@ -0,0 +1,401 @@
+//! `TcpStream` split support.
+//!
+//! A `TcpStream` can be split into a `ReadHalf` and a
+//! `WriteHalf` with the `TcpStream::split` method. `ReadHalf`
+//! implements `AsyncRead` while `WriteHalf` implements `AsyncWrite`.
+//!
+//! Compared to the generic split of `AsyncRead + AsyncWrite`, this specialized
+//! split has no associated overhead and enforces all invariants at the type
+//! level.
+
+use crate::future::poll_fn;
+use crate::io::{AsyncRead, AsyncWrite, Interest, ReadBuf, Ready};
+use crate::net::TcpStream;
+
+use std::io;
+use std::net::{Shutdown, SocketAddr};
+use std::pin::Pin;
+use std::task::{Context, Poll};
+
+cfg_io_util! {
+    use bytes::BufMut;
+}
+
+/// Borrowed read half of a [`TcpStream`], created by [`split`].
+///
+/// Reading from a `ReadHalf` is usually done using the convenience methods found on the
+/// [`AsyncReadExt`] trait.
+///
+/// [`TcpStream`]: TcpStream
+/// [`split`]: TcpStream::split()
+/// [`AsyncReadExt`]: trait@crate::io::AsyncReadExt
+#[derive(Debug)]
+pub struct ReadHalf<'a>(&'a TcpStream);
+
+/// Borrowed write half of a [`TcpStream`], created by [`split`].
+///
+/// Note that in the [`AsyncWrite`] implementation of this type, [`poll_shutdown`] will
+/// shut down the TCP stream in the write direction.
+///
+/// Writing to an `WriteHalf` is usually done using the convenience methods found
+/// on the [`AsyncWriteExt`] trait.
+///
+/// [`TcpStream`]: TcpStream
+/// [`split`]: TcpStream::split()
+/// [`AsyncWrite`]: trait@crate::io::AsyncWrite
+/// [`poll_shutdown`]: fn@crate::io::AsyncWrite::poll_shutdown
+/// [`AsyncWriteExt`]: trait@crate::io::AsyncWriteExt
+#[derive(Debug)]
+pub struct WriteHalf<'a>(&'a TcpStream);
+
+pub(crate) fn split(stream: &mut TcpStream) -> (ReadHalf<'_>, WriteHalf<'_>) {
+    (ReadHalf(&*stream), WriteHalf(&*stream))
+}
+
+impl ReadHalf<'_> {
+    /// Attempts to receive data on the socket, without removing that data from
+    /// the queue, registering the current task for wakeup if data is not yet
+    /// available.
+    ///
+    /// Note that on multiple calls to `poll_peek` or `poll_read`, only the
+    /// `Waker` from the `Context` passed to the most recent call is scheduled
+    /// to receive a wakeup.
+    ///
+    /// See the [`TcpStream::poll_peek`] level documentation for more details.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::io::{self, ReadBuf};
+    /// use tokio::net::TcpStream;
+    ///
+    /// use futures::future::poll_fn;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let mut stream = TcpStream::connect("127.0.0.1:8000").await?;
+    ///     let (mut read_half, _) = stream.split();
+    ///     let mut buf = [0; 10];
+    ///     let mut buf = ReadBuf::new(&mut buf);
+    ///
+    ///     poll_fn(|cx| {
+    ///         read_half.poll_peek(cx, &mut buf)
+    ///     }).await?;
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    ///
+    /// [`TcpStream::poll_peek`]: TcpStream::poll_peek
+    pub fn poll_peek(
+        &mut self,
+        cx: &mut Context<'_>,
+        buf: &mut ReadBuf<'_>,
+    ) -> Poll<io::Result<usize>> {
+        self.0.poll_peek(cx, buf)
+    }
+
+    /// Receives data on the socket from the remote address to which it is
+    /// connected, without removing that data from the queue. On success,
+    /// returns the number of bytes peeked.
+    ///
+    /// See the [`TcpStream::peek`] level documentation for more details.
+    ///
+    /// [`TcpStream::peek`]: TcpStream::peek
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpStream;
+    /// use tokio::io::AsyncReadExt;
+    /// use std::error::Error;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> Result<(), Box<dyn Error>> {
+    ///     // Connect to a peer
+    ///     let mut stream = TcpStream::connect("127.0.0.1:8080").await?;
+    ///     let (mut read_half, _) = stream.split();
+    ///
+    ///     let mut b1 = [0; 10];
+    ///     let mut b2 = [0; 10];
+    ///
+    ///     // Peek at the data
+    ///     let n = read_half.peek(&mut b1).await?;
+    ///
+    ///     // Read the data
+    ///     assert_eq!(n, read_half.read(&mut b2[..n]).await?);
+    ///     assert_eq!(&b1[..n], &b2[..n]);
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    ///
+    /// The [`read`] method is defined on the [`AsyncReadExt`] trait.
+    ///
+    /// [`read`]: fn@crate::io::AsyncReadExt::read
+    /// [`AsyncReadExt`]: trait@crate::io::AsyncReadExt
+    pub async fn peek(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        let mut buf = ReadBuf::new(buf);
+        poll_fn(|cx| self.poll_peek(cx, &mut buf)).await
+    }
+
+    /// Waits for any of the requested ready states.
+    ///
+    /// This function is usually paired with `try_read()` or `try_write()`. It
+    /// can be used to concurrently read / write to the same socket on a single
+    /// task without splitting the socket.
+    ///
+    /// This function is equivalent to [`TcpStream::ready`].
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to read or write that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn ready(&self, interest: Interest) -> io::Result<Ready> {
+        self.0.ready(interest).await
+    }
+
+    /// Waits for the socket to become readable.
+    ///
+    /// This function is equivalent to `ready(Interest::READABLE)` and is usually
+    /// paired with `try_read()`.
+    ///
+    /// This function is also equivalent to [`TcpStream::ready`].
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to read that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn readable(&self) -> io::Result<()> {
+        self.0.readable().await
+    }
+
+    /// Tries to read data from the stream into the provided buffer, returning how
+    /// many bytes were read.
+    ///
+    /// Receives any pending data from the socket but does not wait for new data
+    /// to arrive. On success, returns the number of bytes read. Because
+    /// `try_read()` is non-blocking, the buffer does not have to be stored by
+    /// the async task and can exist entirely on the stack.
+    ///
+    /// Usually, [`readable()`] or [`ready()`] is used with this function.
+    ///
+    /// [`readable()`]: Self::readable()
+    /// [`ready()`]: Self::ready()
+    ///
+    /// # Return
+    ///
+    /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+    /// number of bytes read. `Ok(0)` indicates the stream's read half is closed
+    /// and will no longer yield data. If the stream is not ready to read data
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_read(&self, buf: &mut [u8]) -> io::Result<usize> {
+        self.0.try_read(buf)
+    }
+
+    /// Tries to read data from the stream into the provided buffers, returning
+    /// how many bytes were read.
+    ///
+    /// Data is copied to fill each buffer in order, with the final buffer
+    /// written to possibly being only partially filled. This method behaves
+    /// equivalently to a single call to [`try_read()`] with concatenated
+    /// buffers.
+    ///
+    /// Receives any pending data from the socket but does not wait for new data
+    /// to arrive. On success, returns the number of bytes read. Because
+    /// `try_read_vectored()` is non-blocking, the buffer does not have to be
+    /// stored by the async task and can exist entirely on the stack.
+    ///
+    /// Usually, [`readable()`] or [`ready()`] is used with this function.
+    ///
+    /// [`try_read()`]: Self::try_read()
+    /// [`readable()`]: Self::readable()
+    /// [`ready()`]: Self::ready()
+    ///
+    /// # Return
+    ///
+    /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+    /// number of bytes read. `Ok(0)` indicates the stream's read half is closed
+    /// and will no longer yield data. If the stream is not ready to read data
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_read_vectored(&self, bufs: &mut [io::IoSliceMut<'_>]) -> io::Result<usize> {
+        self.0.try_read_vectored(bufs)
+    }
+
+    cfg_io_util! {
+        /// Tries to read data from the stream into the provided buffer, advancing the
+        /// buffer's internal cursor, returning how many bytes were read.
+        ///
+        /// Receives any pending data from the socket but does not wait for new data
+        /// to arrive. On success, returns the number of bytes read. Because
+        /// `try_read_buf()` is non-blocking, the buffer does not have to be stored by
+        /// the async task and can exist entirely on the stack.
+        ///
+        /// Usually, [`readable()`] or [`ready()`] is used with this function.
+        ///
+        /// [`readable()`]: Self::readable()
+        /// [`ready()`]: Self::ready()
+        ///
+        /// # Return
+        ///
+        /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+        /// number of bytes read. `Ok(0)` indicates the stream's read half is closed
+        /// and will no longer yield data. If the stream is not ready to read data
+        /// `Err(io::ErrorKind::WouldBlock)` is returned.
+        pub fn try_read_buf<B: BufMut>(&self, buf: &mut B) -> io::Result<usize> {
+            self.0.try_read_buf(buf)
+        }
+    }
+
+    /// Returns the remote address that this stream is connected to.
+    pub fn peer_addr(&self) -> io::Result<SocketAddr> {
+        self.0.peer_addr()
+    }
+
+    /// Returns the local address that this stream is bound to.
+    pub fn local_addr(&self) -> io::Result<SocketAddr> {
+        self.0.local_addr()
+    }
+}
+
+impl WriteHalf<'_> {
+    /// Waits for any of the requested ready states.
+    ///
+    /// This function is usually paired with `try_read()` or `try_write()`. It
+    /// can be used to concurrently read / write to the same socket on a single
+    /// task without splitting the socket.
+    ///
+    /// This function is equivalent to [`TcpStream::ready`].
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to read or write that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn ready(&self, interest: Interest) -> io::Result<Ready> {
+        self.0.ready(interest).await
+    }
+
+    /// Waits for the socket to become writable.
+    ///
+    /// This function is equivalent to `ready(Interest::WRITABLE)` and is usually
+    /// paired with `try_write()`.
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to write that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn writable(&self) -> io::Result<()> {
+        self.0.writable().await
+    }
+
+    /// Tries to write a buffer to the stream, returning how many bytes were
+    /// written.
+    ///
+    /// The function will attempt to write the entire contents of `buf`, but
+    /// only part of the buffer may be written.
+    ///
+    /// This function is usually paired with `writable()`.
+    ///
+    /// # Return
+    ///
+    /// If data is successfully written, `Ok(n)` is returned, where `n` is the
+    /// number of bytes written. If the stream is not ready to write data,
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_write(&self, buf: &[u8]) -> io::Result<usize> {
+        self.0.try_write(buf)
+    }
+
+    /// Tries to write several buffers to the stream, returning how many bytes
+    /// were written.
+    ///
+    /// Data is written from each buffer in order, with the final buffer read
+    /// from possible being only partially consumed. This method behaves
+    /// equivalently to a single call to [`try_write()`] with concatenated
+    /// buffers.
+    ///
+    /// This function is usually paired with `writable()`.
+    ///
+    /// [`try_write()`]: Self::try_write()
+    ///
+    /// # Return
+    ///
+    /// If data is successfully written, `Ok(n)` is returned, where `n` is the
+    /// number of bytes written. If the stream is not ready to write data,
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_write_vectored(&self, bufs: &[io::IoSlice<'_>]) -> io::Result<usize> {
+        self.0.try_write_vectored(bufs)
+    }
+
+    /// Returns the remote address that this stream is connected to.
+    pub fn peer_addr(&self) -> io::Result<SocketAddr> {
+        self.0.peer_addr()
+    }
+
+    /// Returns the local address that this stream is bound to.
+    pub fn local_addr(&self) -> io::Result<SocketAddr> {
+        self.0.local_addr()
+    }
+}
+
+impl AsyncRead for ReadHalf<'_> {
+    fn poll_read(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &mut ReadBuf<'_>,
+    ) -> Poll<io::Result<()>> {
+        self.0.poll_read_priv(cx, buf)
+    }
+}
+
+impl AsyncWrite for WriteHalf<'_> {
+    fn poll_write(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &[u8],
+    ) -> Poll<io::Result<usize>> {
+        self.0.poll_write_priv(cx, buf)
+    }
+
+    fn poll_write_vectored(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        bufs: &[io::IoSlice<'_>],
+    ) -> Poll<io::Result<usize>> {
+        self.0.poll_write_vectored_priv(cx, bufs)
+    }
+
+    fn is_write_vectored(&self) -> bool {
+        self.0.is_write_vectored()
+    }
+
+    #[inline]
+    fn poll_flush(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<io::Result<()>> {
+        // tcp flush is a no-op
+        Poll::Ready(Ok(()))
+    }
+
+    // `poll_shutdown` on a write half shutdowns the stream in the "write" direction.
+    fn poll_shutdown(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<io::Result<()>> {
+        self.0.shutdown_std(Shutdown::Write).into()
+    }
+}
+
+impl AsRef<TcpStream> for ReadHalf<'_> {
+    fn as_ref(&self) -> &TcpStream {
+        self.0
+    }
+}
+
+impl AsRef<TcpStream> for WriteHalf<'_> {
+    fn as_ref(&self) -> &TcpStream {
+        self.0
+    }
+}
diff --git a/third_party/rust/tokio/src/net/tcp/split_owned.rs b/third_party/rust/tokio/src/net/tcp/split_owned.rs
new file mode 100644
index 0000000000..ef4e7b5361
--- /dev/null
+++ b/third_party/rust/tokio/src/net/tcp/split_owned.rs
@@ -0,0 +1,485 @@
+//! `TcpStream` owned split support.
+//!
+//! A `TcpStream` can be split into an `OwnedReadHalf` and a `OwnedWriteHalf`
+//! with the `TcpStream::into_split` method.  `OwnedReadHalf` implements
+//! `AsyncRead` while `OwnedWriteHalf` implements `AsyncWrite`.
+//!
+//! Compared to the generic split of `AsyncRead + AsyncWrite`, this specialized
+//! split has no associated overhead and enforces all invariants at the type
+//! level.
+
+use crate::future::poll_fn;
+use crate::io::{AsyncRead, AsyncWrite, Interest, ReadBuf, Ready};
+use crate::net::TcpStream;
+
+use std::error::Error;
+use std::net::{Shutdown, SocketAddr};
+use std::pin::Pin;
+use std::sync::Arc;
+use std::task::{Context, Poll};
+use std::{fmt, io};
+
+cfg_io_util! {
+    use bytes::BufMut;
+}
+
+/// Owned read half of a [`TcpStream`], created by [`into_split`].
+///
+/// Reading from an `OwnedReadHalf` is usually done using the convenience methods found
+/// on the [`AsyncReadExt`] trait.
+///
+/// [`TcpStream`]: TcpStream
+/// [`into_split`]: TcpStream::into_split()
+/// [`AsyncReadExt`]: trait@crate::io::AsyncReadExt
+#[derive(Debug)]
+pub struct OwnedReadHalf {
+    inner: Arc<TcpStream>,
+}
+
+/// Owned write half of a [`TcpStream`], created by [`into_split`].
+///
+/// Note that in the [`AsyncWrite`] implementation of this type, [`poll_shutdown`] will
+/// shut down the TCP stream in the write direction.  Dropping the write half
+/// will also shut down the write half of the TCP stream.
+///
+/// Writing to an `OwnedWriteHalf` is usually done using the convenience methods found
+/// on the [`AsyncWriteExt`] trait.
+///
+/// [`TcpStream`]: TcpStream
+/// [`into_split`]: TcpStream::into_split()
+/// [`AsyncWrite`]: trait@crate::io::AsyncWrite
+/// [`poll_shutdown`]: fn@crate::io::AsyncWrite::poll_shutdown
+/// [`AsyncWriteExt`]: trait@crate::io::AsyncWriteExt
+#[derive(Debug)]
+pub struct OwnedWriteHalf {
+    inner: Arc<TcpStream>,
+    shutdown_on_drop: bool,
+}
+
+pub(crate) fn split_owned(stream: TcpStream) -> (OwnedReadHalf, OwnedWriteHalf) {
+    let arc = Arc::new(stream);
+    let read = OwnedReadHalf {
+        inner: Arc::clone(&arc),
+    };
+    let write = OwnedWriteHalf {
+        inner: arc,
+        shutdown_on_drop: true,
+    };
+    (read, write)
+}
+
+pub(crate) fn reunite(
+    read: OwnedReadHalf,
+    write: OwnedWriteHalf,
+) -> Result<TcpStream, ReuniteError> {
+    if Arc::ptr_eq(&read.inner, &write.inner) {
+        write.forget();
+        // This unwrap cannot fail as the api does not allow creating more than two Arcs,
+        // and we just dropped the other half.
+        Ok(Arc::try_unwrap(read.inner).expect("TcpStream: try_unwrap failed in reunite"))
+    } else {
+        Err(ReuniteError(read, write))
+    }
+}
+
+/// Error indicating that two halves were not from the same socket, and thus could
+/// not be reunited.
+#[derive(Debug)]
+pub struct ReuniteError(pub OwnedReadHalf, pub OwnedWriteHalf);
+
+impl fmt::Display for ReuniteError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(
+            f,
+            "tried to reunite halves that are not from the same socket"
+        )
+    }
+}
+
+impl Error for ReuniteError {}
+
+impl OwnedReadHalf {
+    /// Attempts to put the two halves of a `TcpStream` back together and
+    /// recover the original socket. Succeeds only if the two halves
+    /// originated from the same call to [`into_split`].
+    ///
+    /// [`into_split`]: TcpStream::into_split()
+    pub fn reunite(self, other: OwnedWriteHalf) -> Result<TcpStream, ReuniteError> {
+        reunite(self, other)
+    }
+
+    /// Attempt to receive data on the socket, without removing that data from
+    /// the queue, registering the current task for wakeup if data is not yet
+    /// available.
+    ///
+    /// Note that on multiple calls to `poll_peek` or `poll_read`, only the
+    /// `Waker` from the `Context` passed to the most recent call is scheduled
+    /// to receive a wakeup.
+    ///
+    /// See the [`TcpStream::poll_peek`] level documentation for more details.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::io::{self, ReadBuf};
+    /// use tokio::net::TcpStream;
+    ///
+    /// use futures::future::poll_fn;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let stream = TcpStream::connect("127.0.0.1:8000").await?;
+    ///     let (mut read_half, _) = stream.into_split();
+    ///     let mut buf = [0; 10];
+    ///     let mut buf = ReadBuf::new(&mut buf);
+    ///
+    ///     poll_fn(|cx| {
+    ///         read_half.poll_peek(cx, &mut buf)
+    ///     }).await?;
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    ///
+    /// [`TcpStream::poll_peek`]: TcpStream::poll_peek
+    pub fn poll_peek(
+        &mut self,
+        cx: &mut Context<'_>,
+        buf: &mut ReadBuf<'_>,
+    ) -> Poll<io::Result<usize>> {
+        self.inner.poll_peek(cx, buf)
+    }
+
+    /// Receives data on the socket from the remote address to which it is
+    /// connected, without removing that data from the queue. On success,
+    /// returns the number of bytes peeked.
+    ///
+    /// See the [`TcpStream::peek`] level documentation for more details.
+    ///
+    /// [`TcpStream::peek`]: TcpStream::peek
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpStream;
+    /// use tokio::io::AsyncReadExt;
+    /// use std::error::Error;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> Result<(), Box<dyn Error>> {
+    ///     // Connect to a peer
+    ///     let stream = TcpStream::connect("127.0.0.1:8080").await?;
+    ///     let (mut read_half, _) = stream.into_split();
+    ///
+    ///     let mut b1 = [0; 10];
+    ///     let mut b2 = [0; 10];
+    ///
+    ///     // Peek at the data
+    ///     let n = read_half.peek(&mut b1).await?;
+    ///
+    ///     // Read the data
+    ///     assert_eq!(n, read_half.read(&mut b2[..n]).await?);
+    ///     assert_eq!(&b1[..n], &b2[..n]);
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    ///
+    /// The [`read`] method is defined on the [`AsyncReadExt`] trait.
+    ///
+    /// [`read`]: fn@crate::io::AsyncReadExt::read
+    /// [`AsyncReadExt`]: trait@crate::io::AsyncReadExt
+    pub async fn peek(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        let mut buf = ReadBuf::new(buf);
+        poll_fn(|cx| self.poll_peek(cx, &mut buf)).await
+    }
+
+    /// Waits for any of the requested ready states.
+    ///
+    /// This function is usually paired with `try_read()` or `try_write()`. It
+    /// can be used to concurrently read / write to the same socket on a single
+    /// task without splitting the socket.
+    ///
+    /// This function is equivalent to [`TcpStream::ready`].
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to read or write that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn ready(&self, interest: Interest) -> io::Result<Ready> {
+        self.inner.ready(interest).await
+    }
+
+    /// Waits for the socket to become readable.
+    ///
+    /// This function is equivalent to `ready(Interest::READABLE)` and is usually
+    /// paired with `try_read()`.
+    ///
+    /// This function is also equivalent to [`TcpStream::ready`].
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to read that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn readable(&self) -> io::Result<()> {
+        self.inner.readable().await
+    }
+
+    /// Tries to read data from the stream into the provided buffer, returning how
+    /// many bytes were read.
+    ///
+    /// Receives any pending data from the socket but does not wait for new data
+    /// to arrive. On success, returns the number of bytes read. Because
+    /// `try_read()` is non-blocking, the buffer does not have to be stored by
+    /// the async task and can exist entirely on the stack.
+    ///
+    /// Usually, [`readable()`] or [`ready()`] is used with this function.
+    ///
+    /// [`readable()`]: Self::readable()
+    /// [`ready()`]: Self::ready()
+    ///
+    /// # Return
+    ///
+    /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+    /// number of bytes read. `Ok(0)` indicates the stream's read half is closed
+    /// and will no longer yield data. If the stream is not ready to read data
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_read(&self, buf: &mut [u8]) -> io::Result<usize> {
+        self.inner.try_read(buf)
+    }
+
+    /// Tries to read data from the stream into the provided buffers, returning
+    /// how many bytes were read.
+    ///
+    /// Data is copied to fill each buffer in order, with the final buffer
+    /// written to possibly being only partially filled. This method behaves
+    /// equivalently to a single call to [`try_read()`] with concatenated
+    /// buffers.
+    ///
+    /// Receives any pending data from the socket but does not wait for new data
+    /// to arrive. On success, returns the number of bytes read. Because
+    /// `try_read_vectored()` is non-blocking, the buffer does not have to be
+    /// stored by the async task and can exist entirely on the stack.
+    ///
+    /// Usually, [`readable()`] or [`ready()`] is used with this function.
+    ///
+    /// [`try_read()`]: Self::try_read()
+    /// [`readable()`]: Self::readable()
+    /// [`ready()`]: Self::ready()
+    ///
+    /// # Return
+    ///
+    /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+    /// number of bytes read. `Ok(0)` indicates the stream's read half is closed
+    /// and will no longer yield data. If the stream is not ready to read data
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_read_vectored(&self, bufs: &mut [io::IoSliceMut<'_>]) -> io::Result<usize> {
+        self.inner.try_read_vectored(bufs)
+    }
+
+    cfg_io_util! {
+        /// Tries to read data from the stream into the provided buffer, advancing the
+        /// buffer's internal cursor, returning how many bytes were read.
+        ///
+        /// Receives any pending data from the socket but does not wait for new data
+        /// to arrive. On success, returns the number of bytes read. Because
+        /// `try_read_buf()` is non-blocking, the buffer does not have to be stored by
+        /// the async task and can exist entirely on the stack.
+        ///
+        /// Usually, [`readable()`] or [`ready()`] is used with this function.
+        ///
+        /// [`readable()`]: Self::readable()
+        /// [`ready()`]: Self::ready()
+        ///
+        /// # Return
+        ///
+        /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+        /// number of bytes read. `Ok(0)` indicates the stream's read half is closed
+        /// and will no longer yield data. If the stream is not ready to read data
+        /// `Err(io::ErrorKind::WouldBlock)` is returned.
+        pub fn try_read_buf<B: BufMut>(&self, buf: &mut B) -> io::Result<usize> {
+            self.inner.try_read_buf(buf)
+        }
+    }
+
+    /// Returns the remote address that this stream is connected to.
+    pub fn peer_addr(&self) -> io::Result<SocketAddr> {
+        self.inner.peer_addr()
+    }
+
+    /// Returns the local address that this stream is bound to.
+    pub fn local_addr(&self) -> io::Result<SocketAddr> {
+        self.inner.local_addr()
+    }
+}
+
+impl AsyncRead for OwnedReadHalf {
+    fn poll_read(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &mut ReadBuf<'_>,
+    ) -> Poll<io::Result<()>> {
+        self.inner.poll_read_priv(cx, buf)
+    }
+}
+
+impl OwnedWriteHalf {
+    /// Attempts to put the two halves of a `TcpStream` back together and
+    /// recover the original socket. Succeeds only if the two halves
+    /// originated from the same call to [`into_split`].
+    ///
+    /// [`into_split`]: TcpStream::into_split()
+    pub fn reunite(self, other: OwnedReadHalf) -> Result<TcpStream, ReuniteError> {
+        reunite(other, self)
+    }
+
+    /// Destroys the write half, but don't close the write half of the stream
+    /// until the read half is dropped. If the read half has already been
+    /// dropped, this closes the stream.
+    pub fn forget(mut self) {
+        self.shutdown_on_drop = false;
+        drop(self);
+    }
+
+    /// Waits for any of the requested ready states.
+    ///
+    /// This function is usually paired with `try_read()` or `try_write()`. It
+    /// can be used to concurrently read / write to the same socket on a single
+    /// task without splitting the socket.
+    ///
+    /// This function is equivalent to [`TcpStream::ready`].
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to read or write that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn ready(&self, interest: Interest) -> io::Result<Ready> {
+        self.inner.ready(interest).await
+    }
+
+    /// Waits for the socket to become writable.
+    ///
+    /// This function is equivalent to `ready(Interest::WRITABLE)` and is usually
+    /// paired with `try_write()`.
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to write that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn writable(&self) -> io::Result<()> {
+        self.inner.writable().await
+    }
+
+    /// Tries to write a buffer to the stream, returning how many bytes were
+    /// written.
+    ///
+    /// The function will attempt to write the entire contents of `buf`, but
+    /// only part of the buffer may be written.
+    ///
+    /// This function is usually paired with `writable()`.
+    ///
+    /// # Return
+    ///
+    /// If data is successfully written, `Ok(n)` is returned, where `n` is the
+    /// number of bytes written. If the stream is not ready to write data,
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_write(&self, buf: &[u8]) -> io::Result<usize> {
+        self.inner.try_write(buf)
+    }
+
+    /// Tries to write several buffers to the stream, returning how many bytes
+    /// were written.
+    ///
+    /// Data is written from each buffer in order, with the final buffer read
+    /// from possible being only partially consumed. This method behaves
+    /// equivalently to a single call to [`try_write()`] with concatenated
+    /// buffers.
+    ///
+    /// This function is usually paired with `writable()`.
+    ///
+    /// [`try_write()`]: Self::try_write()
+    ///
+    /// # Return
+    ///
+    /// If data is successfully written, `Ok(n)` is returned, where `n` is the
+    /// number of bytes written. If the stream is not ready to write data,
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_write_vectored(&self, bufs: &[io::IoSlice<'_>]) -> io::Result<usize> {
+        self.inner.try_write_vectored(bufs)
+    }
+
+    /// Returns the remote address that this stream is connected to.
+    pub fn peer_addr(&self) -> io::Result<SocketAddr> {
+        self.inner.peer_addr()
+    }
+
+    /// Returns the local address that this stream is bound to.
+    pub fn local_addr(&self) -> io::Result<SocketAddr> {
+        self.inner.local_addr()
+    }
+}
+
+impl Drop for OwnedWriteHalf {
+    fn drop(&mut self) {
+        if self.shutdown_on_drop {
+            let _ = self.inner.shutdown_std(Shutdown::Write);
+        }
+    }
+}
+
+impl AsyncWrite for OwnedWriteHalf {
+    fn poll_write(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &[u8],
+    ) -> Poll<io::Result<usize>> {
+        self.inner.poll_write_priv(cx, buf)
+    }
+
+    fn poll_write_vectored(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        bufs: &[io::IoSlice<'_>],
+    ) -> Poll<io::Result<usize>> {
+        self.inner.poll_write_vectored_priv(cx, bufs)
+    }
+
+    fn is_write_vectored(&self) -> bool {
+        self.inner.is_write_vectored()
+    }
+
+    #[inline]
+    fn poll_flush(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<io::Result<()>> {
+        // tcp flush is a no-op
+        Poll::Ready(Ok(()))
+    }
+
+    // `poll_shutdown` on a write half shutdowns the stream in the "write" direction.
+    fn poll_shutdown(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<io::Result<()>> {
+        let res = self.inner.shutdown_std(Shutdown::Write);
+        if res.is_ok() {
+            Pin::into_inner(self).shutdown_on_drop = false;
+        }
+        res.into()
+    }
+}
+
+impl AsRef<TcpStream> for OwnedReadHalf {
+    fn as_ref(&self) -> &TcpStream {
+        &*self.inner
+    }
+}
+
+impl AsRef<TcpStream> for OwnedWriteHalf {
+    fn as_ref(&self) -> &TcpStream {
+        &*self.inner
+    }
+}
diff --git a/third_party/rust/tokio/src/net/tcp/stream.rs b/third_party/rust/tokio/src/net/tcp/stream.rs
new file mode 100644
index 0000000000..ebb67b84d1
--- /dev/null
+++ b/third_party/rust/tokio/src/net/tcp/stream.rs
@@ -0,0 +1,1310 @@
+use crate::future::poll_fn;
+use crate::io::{AsyncRead, AsyncWrite, Interest, PollEvented, ReadBuf, Ready};
+use crate::net::tcp::split::{split, ReadHalf, WriteHalf};
+use crate::net::tcp::split_owned::{split_owned, OwnedReadHalf, OwnedWriteHalf};
+use crate::net::{to_socket_addrs, ToSocketAddrs};
+
+use std::convert::TryFrom;
+use std::fmt;
+use std::io;
+use std::net::{Shutdown, SocketAddr};
+use std::pin::Pin;
+use std::task::{Context, Poll};
+use std::time::Duration;
+
+cfg_io_util! {
+    use bytes::BufMut;
+}
+
+cfg_net! {
+    /// A TCP stream between a local and a remote socket.
+    ///
+    /// A TCP stream can either be created by connecting to an endpoint, via the
+    /// [`connect`] method, or by [accepting] a connection from a [listener]. A
+    /// TCP stream can also be created via the [`TcpSocket`] type.
+    ///
+    /// Reading and writing to a `TcpStream` is usually done using the
+    /// convenience methods found on the [`AsyncReadExt`] and [`AsyncWriteExt`]
+    /// traits.
+    ///
+    /// [`connect`]: method@TcpStream::connect
+    /// [accepting]: method@crate::net::TcpListener::accept
+    /// [listener]: struct@crate::net::TcpListener
+    /// [`TcpSocket`]: struct@crate::net::TcpSocket
+    /// [`AsyncReadExt`]: trait@crate::io::AsyncReadExt
+    /// [`AsyncWriteExt`]: trait@crate::io::AsyncWriteExt
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpStream;
+    /// use tokio::io::AsyncWriteExt;
+    /// use std::error::Error;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> Result<(), Box<dyn Error>> {
+    ///     // Connect to a peer
+    ///     let mut stream = TcpStream::connect("127.0.0.1:8080").await?;
+    ///
+    ///     // Write some data.
+    ///     stream.write_all(b"hello world!").await?;
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    ///
+    /// The [`write_all`] method is defined on the [`AsyncWriteExt`] trait.
+    ///
+    /// [`write_all`]: fn@crate::io::AsyncWriteExt::write_all
+    /// [`AsyncWriteExt`]: trait@crate::io::AsyncWriteExt
+    ///
+    /// To shut down the stream in the write direction, you can call the
+    /// [`shutdown()`] method. This will cause the other peer to receive a read of
+    /// length 0, indicating that no more data will be sent. This only closes
+    /// the stream in one direction.
+    ///
+    /// [`shutdown()`]: fn@crate::io::AsyncWriteExt::shutdown
+    pub struct TcpStream {
+        io: PollEvented<mio::net::TcpStream>,
+    }
+}
+
+impl TcpStream {
+    /// Opens a TCP connection to a remote host.
+    ///
+    /// `addr` is an address of the remote host. Anything which implements the
+    /// [`ToSocketAddrs`] trait can be supplied as the address.  If `addr`
+    /// yields multiple addresses, connect 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.
+    ///
+    /// To configure the socket before connecting, you can use the [`TcpSocket`]
+    /// type.
+    ///
+    /// [`ToSocketAddrs`]: trait@crate::net::ToSocketAddrs
+    /// [`TcpSocket`]: struct@crate::net::TcpSocket
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpStream;
+    /// use tokio::io::AsyncWriteExt;
+    /// use std::error::Error;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> Result<(), Box<dyn Error>> {
+    ///     // Connect to a peer
+    ///     let mut stream = TcpStream::connect("127.0.0.1:8080").await?;
+    ///
+    ///     // Write some data.
+    ///     stream.write_all(b"hello world!").await?;
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    ///
+    /// The [`write_all`] method is defined on the [`AsyncWriteExt`] trait.
+    ///
+    /// [`write_all`]: fn@crate::io::AsyncWriteExt::write_all
+    /// [`AsyncWriteExt`]: trait@crate::io::AsyncWriteExt
+    pub async fn connect<A: ToSocketAddrs>(addr: A) -> io::Result<TcpStream> {
+        let addrs = to_socket_addrs(addr).await?;
+
+        let mut last_err = None;
+
+        for addr in addrs {
+            match TcpStream::connect_addr(addr).await {
+                Ok(stream) => return Ok(stream),
+                Err(e) => last_err = Some(e),
+            }
+        }
+
+        Err(last_err.unwrap_or_else(|| {
+            io::Error::new(
+                io::ErrorKind::InvalidInput,
+                "could not resolve to any address",
+            )
+        }))
+    }
+
+    /// Establishes a connection to the specified `addr`.
+    async fn connect_addr(addr: SocketAddr) -> io::Result<TcpStream> {
+        let sys = mio::net::TcpStream::connect(addr)?;
+        TcpStream::connect_mio(sys).await
+    }
+
+    pub(crate) async fn connect_mio(sys: mio::net::TcpStream) -> io::Result<TcpStream> {
+        let stream = TcpStream::new(sys)?;
+
+        // Once we've connected, wait for the stream to be writable as
+        // that's when the actual connection has been initiated. Once we're
+        // writable we check for `take_socket_error` to see if the connect
+        // actually hit an error or not.
+        //
+        // If all that succeeded then we ship everything on up.
+        poll_fn(|cx| stream.io.registration().poll_write_ready(cx)).await?;
+
+        if let Some(e) = stream.io.take_error()? {
+            return Err(e);
+        }
+
+        Ok(stream)
+    }
+
+    pub(crate) fn new(connected: mio::net::TcpStream) -> io::Result<TcpStream> {
+        let io = PollEvented::new(connected)?;
+        Ok(TcpStream { io })
+    }
+
+    /// Creates new `TcpStream` from a `std::net::TcpStream`.
+    ///
+    /// This function is intended to be used to wrap a TCP stream from the
+    /// standard library in the Tokio equivalent. The conversion assumes nothing
+    /// about the underlying stream; it is left up to the user to set it in
+    /// non-blocking mode.
+    ///
+    /// # Examples
+    ///
+    /// ```rust,no_run
+    /// use std::error::Error;
+    /// use tokio::net::TcpStream;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> Result<(), Box<dyn Error>> {
+    ///     let std_stream = std::net::TcpStream::connect("127.0.0.1:34254")?;
+    ///     std_stream.set_nonblocking(true)?;
+    ///     let stream = TcpStream::from_std(std_stream)?;
+    ///     Ok(())
+    /// }
+    /// ```
+    ///
+    /// # Panics
+    ///
+    /// This function panics if thread-local runtime is not set.
+    ///
+    /// The runtime is usually set implicitly when this function is called
+    /// from a future driven by a tokio runtime, otherwise runtime can be set
+    /// explicitly with [`Runtime::enter`](crate::runtime::Runtime::enter) function.
+    pub fn from_std(stream: std::net::TcpStream) -> io::Result<TcpStream> {
+        let io = mio::net::TcpStream::from_std(stream);
+        let io = PollEvented::new(io)?;
+        Ok(TcpStream { io })
+    }
+
+    /// Turns a [`tokio::net::TcpStream`] into a [`std::net::TcpStream`].
+    ///
+    /// The returned [`std::net::TcpStream`] will have nonblocking mode set as `true`.
+    /// Use [`set_nonblocking`] to change the blocking mode if needed.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::error::Error;
+    /// use std::io::Read;
+    /// use tokio::net::TcpListener;
+    /// # use tokio::net::TcpStream;
+    /// # use tokio::io::AsyncWriteExt;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> Result<(), Box<dyn Error>> {
+    ///     let mut data = [0u8; 12];
+    ///     let listener = TcpListener::bind("127.0.0.1:34254").await?;
+    /// #   let handle = tokio::spawn(async {
+    /// #       let mut stream: TcpStream = TcpStream::connect("127.0.0.1:34254").await.unwrap();
+    /// #       stream.write(b"Hello world!").await.unwrap();
+    /// #   });
+    ///     let (tokio_tcp_stream, _) = listener.accept().await?;
+    ///     let mut std_tcp_stream = tokio_tcp_stream.into_std()?;
+    /// #   handle.await.expect("The task being joined has panicked");
+    ///     std_tcp_stream.set_nonblocking(false)?;
+    ///     std_tcp_stream.read_exact(&mut data)?;
+    /// #   assert_eq!(b"Hello world!", &data);
+    ///     Ok(())
+    /// }
+    /// ```
+    /// [`tokio::net::TcpStream`]: TcpStream
+    /// [`std::net::TcpStream`]: std::net::TcpStream
+    /// [`set_nonblocking`]: fn@std::net::TcpStream::set_nonblocking
+    pub fn into_std(self) -> io::Result<std::net::TcpStream> {
+        #[cfg(unix)]
+        {
+            use std::os::unix::io::{FromRawFd, IntoRawFd};
+            self.io
+                .into_inner()
+                .map(|io| io.into_raw_fd())
+                .map(|raw_fd| unsafe { std::net::TcpStream::from_raw_fd(raw_fd) })
+        }
+
+        #[cfg(windows)]
+        {
+            use std::os::windows::io::{FromRawSocket, IntoRawSocket};
+            self.io
+                .into_inner()
+                .map(|io| io.into_raw_socket())
+                .map(|raw_socket| unsafe { std::net::TcpStream::from_raw_socket(raw_socket) })
+        }
+    }
+
+    /// Returns the local address that this stream is bound to.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpStream;
+    ///
+    /// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
+    /// let stream = TcpStream::connect("127.0.0.1:8080").await?;
+    ///
+    /// println!("{:?}", stream.local_addr()?);
+    /// # Ok(())
+    /// # }
+    /// ```
+    pub fn local_addr(&self) -> io::Result<SocketAddr> {
+        self.io.local_addr()
+    }
+
+    /// Returns the remote address that this stream is connected to.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpStream;
+    ///
+    /// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
+    /// let stream = TcpStream::connect("127.0.0.1:8080").await?;
+    ///
+    /// println!("{:?}", stream.peer_addr()?);
+    /// # Ok(())
+    /// # }
+    /// ```
+    pub fn peer_addr(&self) -> io::Result<SocketAddr> {
+        self.io.peer_addr()
+    }
+
+    /// Attempts to receive data on the socket, without removing that data from
+    /// the queue, registering the current task for wakeup if data is not yet
+    /// available.
+    ///
+    /// Note that on multiple calls to `poll_peek`, `poll_read` or
+    /// `poll_read_ready`, only the `Waker` from the `Context` passed to the
+    /// most recent call is scheduled to receive a wakeup. (However,
+    /// `poll_write` retains a second, independent waker.)
+    ///
+    /// # Return value
+    ///
+    /// The function returns:
+    ///
+    /// * `Poll::Pending` if data is not yet available.
+    /// * `Poll::Ready(Ok(n))` if data is available. `n` is the number of bytes peeked.
+    /// * `Poll::Ready(Err(e))` if an error is encountered.
+    ///
+    /// # Errors
+    ///
+    /// This function may encounter any standard I/O error except `WouldBlock`.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::io::{self, ReadBuf};
+    /// use tokio::net::TcpStream;
+    ///
+    /// use futures::future::poll_fn;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let stream = TcpStream::connect("127.0.0.1:8000").await?;
+    ///     let mut buf = [0; 10];
+    ///     let mut buf = ReadBuf::new(&mut buf);
+    ///
+    ///     poll_fn(|cx| {
+    ///         stream.poll_peek(cx, &mut buf)
+    ///     }).await?;
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    pub fn poll_peek(
+        &self,
+        cx: &mut Context<'_>,
+        buf: &mut ReadBuf<'_>,
+    ) -> Poll<io::Result<usize>> {
+        loop {
+            let ev = ready!(self.io.registration().poll_read_ready(cx))?;
+
+            let b = unsafe {
+                &mut *(buf.unfilled_mut() as *mut [std::mem::MaybeUninit<u8>] as *mut [u8])
+            };
+
+            match self.io.peek(b) {
+                Ok(ret) => {
+                    unsafe { buf.assume_init(ret) };
+                    buf.advance(ret);
+                    return Poll::Ready(Ok(ret));
+                }
+                Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+                    self.io.registration().clear_readiness(ev);
+                }
+                Err(e) => return Poll::Ready(Err(e)),
+            }
+        }
+    }
+
+    /// Waits for any of the requested ready states.
+    ///
+    /// This function is usually paired with `try_read()` or `try_write()`. It
+    /// can be used to concurrently read / write to the same socket on a single
+    /// task without splitting the socket.
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to read or write that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    ///
+    /// # Examples
+    ///
+    /// Concurrently read and write to the stream on the same task without
+    /// splitting.
+    ///
+    /// ```no_run
+    /// use tokio::io::Interest;
+    /// use tokio::net::TcpStream;
+    /// use std::error::Error;
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> Result<(), Box<dyn Error>> {
+    ///     let stream = TcpStream::connect("127.0.0.1:8080").await?;
+    ///
+    ///     loop {
+    ///         let ready = stream.ready(Interest::READABLE | Interest::WRITABLE).await?;
+    ///
+    ///         if ready.is_readable() {
+    ///             let mut data = vec![0; 1024];
+    ///             // Try to read data, this may still fail with `WouldBlock`
+    ///             // if the readiness event is a false positive.
+    ///             match stream.try_read(&mut data) {
+    ///                 Ok(n) => {
+    ///                     println!("read {} bytes", n);
+    ///                 }
+    ///                 Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+    ///                     continue;
+    ///                 }
+    ///                 Err(e) => {
+    ///                     return Err(e.into());
+    ///                 }
+    ///             }
+    ///
+    ///         }
+    ///
+    ///         if ready.is_writable() {
+    ///             // Try to write data, this may still fail with `WouldBlock`
+    ///             // if the readiness event is a false positive.
+    ///             match stream.try_write(b"hello world") {
+    ///                 Ok(n) => {
+    ///                     println!("write {} bytes", n);
+    ///                 }
+    ///                 Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+    ///                     continue
+    ///                 }
+    ///                 Err(e) => {
+    ///                     return Err(e.into());
+    ///                 }
+    ///             }
+    ///         }
+    ///     }
+    /// }
+    /// ```
+    pub async fn ready(&self, interest: Interest) -> io::Result<Ready> {
+        let event = self.io.registration().readiness(interest).await?;
+        Ok(event.ready)
+    }
+
+    /// Waits for the socket to become readable.
+    ///
+    /// This function is equivalent to `ready(Interest::READABLE)` and is usually
+    /// paired with `try_read()`.
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to read that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpStream;
+    /// use std::error::Error;
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> Result<(), Box<dyn Error>> {
+    ///     // Connect to a peer
+    ///     let stream = TcpStream::connect("127.0.0.1:8080").await?;
+    ///
+    ///     let mut msg = vec![0; 1024];
+    ///
+    ///     loop {
+    ///         // Wait for the socket to be readable
+    ///         stream.readable().await?;
+    ///
+    ///         // Try to read data, this may still fail with `WouldBlock`
+    ///         // if the readiness event is a false positive.
+    ///         match stream.try_read(&mut msg) {
+    ///             Ok(n) => {
+    ///                 msg.truncate(n);
+    ///                 break;
+    ///             }
+    ///             Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+    ///                 continue;
+    ///             }
+    ///             Err(e) => {
+    ///                 return Err(e.into());
+    ///             }
+    ///         }
+    ///     }
+    ///
+    ///     println!("GOT = {:?}", msg);
+    ///     Ok(())
+    /// }
+    /// ```
+    pub async fn readable(&self) -> io::Result<()> {
+        self.ready(Interest::READABLE).await?;
+        Ok(())
+    }
+
+    /// Polls for read readiness.
+    ///
+    /// If the tcp stream is not currently ready for reading, this method will
+    /// store a clone of the `Waker` from the provided `Context`. When the tcp
+    /// stream becomes ready for reading, `Waker::wake` will be called on the
+    /// waker.
+    ///
+    /// Note that on multiple calls to `poll_read_ready`, `poll_read` or
+    /// `poll_peek`, only the `Waker` from the `Context` passed to the most
+    /// recent call is scheduled to receive a wakeup. (However,
+    /// `poll_write_ready` retains a second, independent waker.)
+    ///
+    /// This function is intended for cases where creating and pinning a future
+    /// via [`readable`] is not feasible. Where possible, using [`readable`] is
+    /// preferred, as this supports polling from multiple tasks at once.
+    ///
+    /// # Return value
+    ///
+    /// The function returns:
+    ///
+    /// * `Poll::Pending` if the tcp stream is not ready for reading.
+    /// * `Poll::Ready(Ok(()))` if the tcp stream is ready for reading.
+    /// * `Poll::Ready(Err(e))` if an error is encountered.
+    ///
+    /// # Errors
+    ///
+    /// This function may encounter any standard I/O error except `WouldBlock`.
+    ///
+    /// [`readable`]: method@Self::readable
+    pub fn poll_read_ready(&self, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        self.io.registration().poll_read_ready(cx).map_ok(|_| ())
+    }
+
+    /// Tries to read data from the stream into the provided buffer, returning how
+    /// many bytes were read.
+    ///
+    /// Receives any pending data from the socket but does not wait for new data
+    /// to arrive. On success, returns the number of bytes read. Because
+    /// `try_read()` is non-blocking, the buffer does not have to be stored by
+    /// the async task and can exist entirely on the stack.
+    ///
+    /// Usually, [`readable()`] or [`ready()`] is used with this function.
+    ///
+    /// [`readable()`]: TcpStream::readable()
+    /// [`ready()`]: TcpStream::ready()
+    ///
+    /// # Return
+    ///
+    /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+    /// number of bytes read. `Ok(0)` indicates the stream's read half is closed
+    /// and will no longer yield data. If the stream is not ready to read data
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpStream;
+    /// use std::error::Error;
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> Result<(), Box<dyn Error>> {
+    ///     // Connect to a peer
+    ///     let stream = TcpStream::connect("127.0.0.1:8080").await?;
+    ///
+    ///     loop {
+    ///         // Wait for the socket to be readable
+    ///         stream.readable().await?;
+    ///
+    ///         // Creating the buffer **after** the `await` prevents it from
+    ///         // being stored in the async task.
+    ///         let mut buf = [0; 4096];
+    ///
+    ///         // Try to read data, this may still fail with `WouldBlock`
+    ///         // if the readiness event is a false positive.
+    ///         match stream.try_read(&mut buf) {
+    ///             Ok(0) => break,
+    ///             Ok(n) => {
+    ///                 println!("read {} bytes", n);
+    ///             }
+    ///             Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+    ///                 continue;
+    ///             }
+    ///             Err(e) => {
+    ///                 return Err(e.into());
+    ///             }
+    ///         }
+    ///     }
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    pub fn try_read(&self, buf: &mut [u8]) -> io::Result<usize> {
+        use std::io::Read;
+
+        self.io
+            .registration()
+            .try_io(Interest::READABLE, || (&*self.io).read(buf))
+    }
+
+    /// Tries to read data from the stream into the provided buffers, returning
+    /// how many bytes were read.
+    ///
+    /// Data is copied to fill each buffer in order, with the final buffer
+    /// written to possibly being only partially filled. This method behaves
+    /// equivalently to a single call to [`try_read()`] with concatenated
+    /// buffers.
+    ///
+    /// Receives any pending data from the socket but does not wait for new data
+    /// to arrive. On success, returns the number of bytes read. Because
+    /// `try_read_vectored()` is non-blocking, the buffer does not have to be
+    /// stored by the async task and can exist entirely on the stack.
+    ///
+    /// Usually, [`readable()`] or [`ready()`] is used with this function.
+    ///
+    /// [`try_read()`]: TcpStream::try_read()
+    /// [`readable()`]: TcpStream::readable()
+    /// [`ready()`]: TcpStream::ready()
+    ///
+    /// # Return
+    ///
+    /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+    /// number of bytes read. `Ok(0)` indicates the stream's read half is closed
+    /// and will no longer yield data. If the stream is not ready to read data
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpStream;
+    /// use std::error::Error;
+    /// use std::io::{self, IoSliceMut};
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> Result<(), Box<dyn Error>> {
+    ///     // Connect to a peer
+    ///     let stream = TcpStream::connect("127.0.0.1:8080").await?;
+    ///
+    ///     loop {
+    ///         // Wait for the socket to be readable
+    ///         stream.readable().await?;
+    ///
+    ///         // Creating the buffer **after** the `await` prevents it from
+    ///         // being stored in the async task.
+    ///         let mut buf_a = [0; 512];
+    ///         let mut buf_b = [0; 1024];
+    ///         let mut bufs = [
+    ///             IoSliceMut::new(&mut buf_a),
+    ///             IoSliceMut::new(&mut buf_b),
+    ///         ];
+    ///
+    ///         // Try to read data, this may still fail with `WouldBlock`
+    ///         // if the readiness event is a false positive.
+    ///         match stream.try_read_vectored(&mut bufs) {
+    ///             Ok(0) => break,
+    ///             Ok(n) => {
+    ///                 println!("read {} bytes", n);
+    ///             }
+    ///             Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+    ///                 continue;
+    ///             }
+    ///             Err(e) => {
+    ///                 return Err(e.into());
+    ///             }
+    ///         }
+    ///     }
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    pub fn try_read_vectored(&self, bufs: &mut [io::IoSliceMut<'_>]) -> io::Result<usize> {
+        use std::io::Read;
+
+        self.io
+            .registration()
+            .try_io(Interest::READABLE, || (&*self.io).read_vectored(bufs))
+    }
+
+    cfg_io_util! {
+        /// Tries to read data from the stream into the provided buffer, advancing the
+        /// buffer's internal cursor, returning how many bytes were read.
+        ///
+        /// Receives any pending data from the socket but does not wait for new data
+        /// to arrive. On success, returns the number of bytes read. Because
+        /// `try_read_buf()` is non-blocking, the buffer does not have to be stored by
+        /// the async task and can exist entirely on the stack.
+        ///
+        /// Usually, [`readable()`] or [`ready()`] is used with this function.
+        ///
+        /// [`readable()`]: TcpStream::readable()
+        /// [`ready()`]: TcpStream::ready()
+        ///
+        /// # Return
+        ///
+        /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+        /// number of bytes read. `Ok(0)` indicates the stream's read half is closed
+        /// and will no longer yield data. If the stream is not ready to read data
+        /// `Err(io::ErrorKind::WouldBlock)` is returned.
+        ///
+        /// # Examples
+        ///
+        /// ```no_run
+        /// use tokio::net::TcpStream;
+        /// use std::error::Error;
+        /// use std::io;
+        ///
+        /// #[tokio::main]
+        /// async fn main() -> Result<(), Box<dyn Error>> {
+        ///     // Connect to a peer
+        ///     let stream = TcpStream::connect("127.0.0.1:8080").await?;
+        ///
+        ///     loop {
+        ///         // Wait for the socket to be readable
+        ///         stream.readable().await?;
+        ///
+        ///         let mut buf = Vec::with_capacity(4096);
+        ///
+        ///         // Try to read data, this may still fail with `WouldBlock`
+        ///         // if the readiness event is a false positive.
+        ///         match stream.try_read_buf(&mut buf) {
+        ///             Ok(0) => break,
+        ///             Ok(n) => {
+        ///                 println!("read {} bytes", n);
+        ///             }
+        ///             Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+        ///                 continue;
+        ///             }
+        ///             Err(e) => {
+        ///                 return Err(e.into());
+        ///             }
+        ///         }
+        ///     }
+        ///
+        ///     Ok(())
+        /// }
+        /// ```
+        pub fn try_read_buf<B: BufMut>(&self, buf: &mut B) -> io::Result<usize> {
+            self.io.registration().try_io(Interest::READABLE, || {
+                use std::io::Read;
+
+                let dst = buf.chunk_mut();
+                let dst =
+                    unsafe { &mut *(dst as *mut _ as *mut [std::mem::MaybeUninit<u8>] as *mut [u8]) };
+
+                // Safety: We trust `TcpStream::read` to have filled up `n` bytes in the
+                // buffer.
+                let n = (&*self.io).read(dst)?;
+
+                unsafe {
+                    buf.advance_mut(n);
+                }
+
+                Ok(n)
+            })
+        }
+    }
+
+    /// Waits for the socket to become writable.
+    ///
+    /// This function is equivalent to `ready(Interest::WRITABLE)` and is usually
+    /// paired with `try_write()`.
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to write that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpStream;
+    /// use std::error::Error;
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> Result<(), Box<dyn Error>> {
+    ///     // Connect to a peer
+    ///     let stream = TcpStream::connect("127.0.0.1:8080").await?;
+    ///
+    ///     loop {
+    ///         // Wait for the socket to be writable
+    ///         stream.writable().await?;
+    ///
+    ///         // Try to write data, this may still fail with `WouldBlock`
+    ///         // if the readiness event is a false positive.
+    ///         match stream.try_write(b"hello world") {
+    ///             Ok(n) => {
+    ///                 break;
+    ///             }
+    ///             Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+    ///                 continue;
+    ///             }
+    ///             Err(e) => {
+    ///                 return Err(e.into());
+    ///             }
+    ///         }
+    ///     }
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    pub async fn writable(&self) -> io::Result<()> {
+        self.ready(Interest::WRITABLE).await?;
+        Ok(())
+    }
+
+    /// Polls for write readiness.
+    ///
+    /// If the tcp stream is not currently ready for writing, this method will
+    /// store a clone of the `Waker` from the provided `Context`. When the tcp
+    /// stream becomes ready for writing, `Waker::wake` will be called on the
+    /// waker.
+    ///
+    /// Note that on multiple calls to `poll_write_ready` or `poll_write`, only
+    /// the `Waker` from the `Context` passed to the most recent call is
+    /// scheduled to receive a wakeup. (However, `poll_read_ready` retains a
+    /// second, independent waker.)
+    ///
+    /// This function is intended for cases where creating and pinning a future
+    /// via [`writable`] is not feasible. Where possible, using [`writable`] is
+    /// preferred, as this supports polling from multiple tasks at once.
+    ///
+    /// # Return value
+    ///
+    /// The function returns:
+    ///
+    /// * `Poll::Pending` if the tcp stream is not ready for writing.
+    /// * `Poll::Ready(Ok(()))` if the tcp stream is ready for writing.
+    /// * `Poll::Ready(Err(e))` if an error is encountered.
+    ///
+    /// # Errors
+    ///
+    /// This function may encounter any standard I/O error except `WouldBlock`.
+    ///
+    /// [`writable`]: method@Self::writable
+    pub fn poll_write_ready(&self, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        self.io.registration().poll_write_ready(cx).map_ok(|_| ())
+    }
+
+    /// Try to write a buffer to the stream, returning how many bytes were
+    /// written.
+    ///
+    /// The function will attempt to write the entire contents of `buf`, but
+    /// only part of the buffer may be written.
+    ///
+    /// This function is usually paired with `writable()`.
+    ///
+    /// # Return
+    ///
+    /// If data is successfully written, `Ok(n)` is returned, where `n` is the
+    /// number of bytes written. If the stream is not ready to write data,
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpStream;
+    /// use std::error::Error;
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> Result<(), Box<dyn Error>> {
+    ///     // Connect to a peer
+    ///     let stream = TcpStream::connect("127.0.0.1:8080").await?;
+    ///
+    ///     loop {
+    ///         // Wait for the socket to be writable
+    ///         stream.writable().await?;
+    ///
+    ///         // Try to write data, this may still fail with `WouldBlock`
+    ///         // if the readiness event is a false positive.
+    ///         match stream.try_write(b"hello world") {
+    ///             Ok(n) => {
+    ///                 break;
+    ///             }
+    ///             Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+    ///                 continue;
+    ///             }
+    ///             Err(e) => {
+    ///                 return Err(e.into());
+    ///             }
+    ///         }
+    ///     }
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    pub fn try_write(&self, buf: &[u8]) -> io::Result<usize> {
+        use std::io::Write;
+
+        self.io
+            .registration()
+            .try_io(Interest::WRITABLE, || (&*self.io).write(buf))
+    }
+
+    /// Tries to write several buffers to the stream, returning how many bytes
+    /// were written.
+    ///
+    /// Data is written from each buffer in order, with the final buffer read
+    /// from possible being only partially consumed. This method behaves
+    /// equivalently to a single call to [`try_write()`] with concatenated
+    /// buffers.
+    ///
+    /// This function is usually paired with `writable()`.
+    ///
+    /// [`try_write()`]: TcpStream::try_write()
+    ///
+    /// # Return
+    ///
+    /// If data is successfully written, `Ok(n)` is returned, where `n` is the
+    /// number of bytes written. If the stream is not ready to write data,
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpStream;
+    /// use std::error::Error;
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> Result<(), Box<dyn Error>> {
+    ///     // Connect to a peer
+    ///     let stream = TcpStream::connect("127.0.0.1:8080").await?;
+    ///
+    ///     let bufs = [io::IoSlice::new(b"hello "), io::IoSlice::new(b"world")];
+    ///
+    ///     loop {
+    ///         // Wait for the socket to be writable
+    ///         stream.writable().await?;
+    ///
+    ///         // Try to write data, this may still fail with `WouldBlock`
+    ///         // if the readiness event is a false positive.
+    ///         match stream.try_write_vectored(&bufs) {
+    ///             Ok(n) => {
+    ///                 break;
+    ///             }
+    ///             Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+    ///                 continue;
+    ///             }
+    ///             Err(e) => {
+    ///                 return Err(e.into());
+    ///             }
+    ///         }
+    ///     }
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    pub fn try_write_vectored(&self, bufs: &[io::IoSlice<'_>]) -> io::Result<usize> {
+        use std::io::Write;
+
+        self.io
+            .registration()
+            .try_io(Interest::WRITABLE, || (&*self.io).write_vectored(bufs))
+    }
+
+    /// Tries to read or write from the socket using a user-provided IO operation.
+    ///
+    /// If the socket is ready, the provided closure is called. The closure
+    /// should attempt to perform IO operation from the socket by manually
+    /// calling the appropriate syscall. If the operation fails because the
+    /// socket is not actually ready, then the closure should return a
+    /// `WouldBlock` error and the readiness flag is cleared. The return value
+    /// of the closure is then returned by `try_io`.
+    ///
+    /// If the socket is not ready, then the closure is not called
+    /// and a `WouldBlock` error is returned.
+    ///
+    /// The closure should only return a `WouldBlock` error if it has performed
+    /// an IO operation on the socket that failed due to the socket not being
+    /// ready. Returning a `WouldBlock` error in any other situation will
+    /// incorrectly clear the readiness flag, which can cause the socket to
+    /// behave incorrectly.
+    ///
+    /// The closure should not perform the IO operation using any of the methods
+    /// defined on the Tokio `TcpStream` type, as this will mess with the
+    /// readiness flag and can cause the socket to behave incorrectly.
+    ///
+    /// Usually, [`readable()`], [`writable()`] or [`ready()`] is used with this function.
+    ///
+    /// [`readable()`]: TcpStream::readable()
+    /// [`writable()`]: TcpStream::writable()
+    /// [`ready()`]: TcpStream::ready()
+    pub fn try_io<R>(
+        &self,
+        interest: Interest,
+        f: impl FnOnce() -> io::Result<R>,
+    ) -> io::Result<R> {
+        self.io.registration().try_io(interest, f)
+    }
+
+    /// Receives data on the socket from the remote address to which it is
+    /// connected, without removing that data from the queue. On success,
+    /// returns the number of bytes peeked.
+    ///
+    /// Successive calls return the same data. This is accomplished by passing
+    /// `MSG_PEEK` as a flag to the underlying recv system call.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpStream;
+    /// use tokio::io::AsyncReadExt;
+    /// use std::error::Error;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> Result<(), Box<dyn Error>> {
+    ///     // Connect to a peer
+    ///     let mut stream = TcpStream::connect("127.0.0.1:8080").await?;
+    ///
+    ///     let mut b1 = [0; 10];
+    ///     let mut b2 = [0; 10];
+    ///
+    ///     // Peek at the data
+    ///     let n = stream.peek(&mut b1).await?;
+    ///
+    ///     // Read the data
+    ///     assert_eq!(n, stream.read(&mut b2[..n]).await?);
+    ///     assert_eq!(&b1[..n], &b2[..n]);
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    ///
+    /// The [`read`] method is defined on the [`AsyncReadExt`] trait.
+    ///
+    /// [`read`]: fn@crate::io::AsyncReadExt::read
+    /// [`AsyncReadExt`]: trait@crate::io::AsyncReadExt
+    pub async fn peek(&self, buf: &mut [u8]) -> io::Result<usize> {
+        self.io
+            .registration()
+            .async_io(Interest::READABLE, || self.io.peek(buf))
+            .await
+    }
+
+    /// Shuts down the read, write, or both halves of this connection.
+    ///
+    /// This function will cause all pending and future I/O on the specified
+    /// portions to return immediately with an appropriate value (see the
+    /// documentation of `Shutdown`).
+    pub(super) fn shutdown_std(&self, how: Shutdown) -> io::Result<()> {
+        self.io.shutdown(how)
+    }
+
+    /// Gets the value of the `TCP_NODELAY` option on this socket.
+    ///
+    /// For more information about this option, see [`set_nodelay`].
+    ///
+    /// [`set_nodelay`]: TcpStream::set_nodelay
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpStream;
+    ///
+    /// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
+    /// let stream = TcpStream::connect("127.0.0.1:8080").await?;
+    ///
+    /// println!("{:?}", stream.nodelay()?);
+    /// # Ok(())
+    /// # }
+    /// ```
+    pub fn nodelay(&self) -> io::Result<bool> {
+        self.io.nodelay()
+    }
+
+    /// Sets the value of the `TCP_NODELAY` option on this socket.
+    ///
+    /// If set, this option disables the Nagle algorithm. This means that
+    /// segments are always sent as soon as possible, even if there is only a
+    /// small amount of data. When not set, data is buffered until there is a
+    /// sufficient amount to send out, thereby avoiding the frequent sending of
+    /// small packets.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpStream;
+    ///
+    /// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
+    /// let stream = TcpStream::connect("127.0.0.1:8080").await?;
+    ///
+    /// stream.set_nodelay(true)?;
+    /// # Ok(())
+    /// # }
+    /// ```
+    pub fn set_nodelay(&self, nodelay: bool) -> io::Result<()> {
+        self.io.set_nodelay(nodelay)
+    }
+
+    /// Reads the linger duration for this socket by getting the `SO_LINGER`
+    /// option.
+    ///
+    /// For more information about this option, see [`set_linger`].
+    ///
+    /// [`set_linger`]: TcpStream::set_linger
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpStream;
+    ///
+    /// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
+    /// let stream = TcpStream::connect("127.0.0.1:8080").await?;
+    ///
+    /// println!("{:?}", stream.linger()?);
+    /// # Ok(())
+    /// # }
+    /// ```
+    pub fn linger(&self) -> io::Result<Option<Duration>> {
+        socket2::SockRef::from(self).linger()
+    }
+
+    /// Sets the linger duration of this socket by setting the SO_LINGER option.
+    ///
+    /// This option controls the action taken when a stream has unsent messages and the stream is
+    /// closed. If SO_LINGER is set, the system shall block the process until it can transmit the
+    /// data or until the time expires.
+    ///
+    /// If SO_LINGER is not specified, and the stream is closed, the system handles the call in a
+    /// way that allows the process to continue as quickly as possible.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpStream;
+    ///
+    /// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
+    /// let stream = TcpStream::connect("127.0.0.1:8080").await?;
+    ///
+    /// stream.set_linger(None)?;
+    /// # Ok(())
+    /// # }
+    /// ```
+    pub fn set_linger(&self, dur: Option<Duration>) -> io::Result<()> {
+        socket2::SockRef::from(self).set_linger(dur)
+    }
+
+    /// Gets the value of the `IP_TTL` option for this socket.
+    ///
+    /// For more information about this option, see [`set_ttl`].
+    ///
+    /// [`set_ttl`]: TcpStream::set_ttl
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpStream;
+    ///
+    /// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
+    /// let stream = TcpStream::connect("127.0.0.1:8080").await?;
+    ///
+    /// println!("{:?}", stream.ttl()?);
+    /// # Ok(())
+    /// # }
+    /// ```
+    pub fn ttl(&self) -> io::Result<u32> {
+        self.io.ttl()
+    }
+
+    /// Sets the value for the `IP_TTL` option on this socket.
+    ///
+    /// This value sets the time-to-live field that is used in every packet sent
+    /// from this socket.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpStream;
+    ///
+    /// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
+    /// let stream = TcpStream::connect("127.0.0.1:8080").await?;
+    ///
+    /// stream.set_ttl(123)?;
+    /// # Ok(())
+    /// # }
+    /// ```
+    pub fn set_ttl(&self, ttl: u32) -> io::Result<()> {
+        self.io.set_ttl(ttl)
+    }
+
+    // These lifetime markers also appear in the generated documentation, and make
+    // it more clear that this is a *borrowed* split.
+    #[allow(clippy::needless_lifetimes)]
+    /// Splits a `TcpStream` into a read half and a write half, which can be used
+    /// to read and write the stream concurrently.
+    ///
+    /// This method is more efficient than [`into_split`], but the halves cannot be
+    /// moved into independently spawned tasks.
+    ///
+    /// [`into_split`]: TcpStream::into_split()
+    pub fn split<'a>(&'a mut self) -> (ReadHalf<'a>, WriteHalf<'a>) {
+        split(self)
+    }
+
+    /// Splits a `TcpStream` into a read half and a write half, which can be used
+    /// to read and write the stream concurrently.
+    ///
+    /// Unlike [`split`], the owned halves can be moved to separate tasks, however
+    /// this comes at the cost of a heap allocation.
+    ///
+    /// **Note:** Dropping the write half will shut down the write half of the TCP
+    /// stream. This is equivalent to calling [`shutdown()`] on the `TcpStream`.
+    ///
+    /// [`split`]: TcpStream::split()
+    /// [`shutdown()`]: fn@crate::io::AsyncWriteExt::shutdown
+    pub fn into_split(self) -> (OwnedReadHalf, OwnedWriteHalf) {
+        split_owned(self)
+    }
+
+    // == Poll IO functions that takes `&self` ==
+    //
+    // To read or write without mutable access to the `UnixStream`, combine the
+    // `poll_read_ready` or `poll_write_ready` methods with the `try_read` or
+    // `try_write` methods.
+
+    pub(crate) fn poll_read_priv(
+        &self,
+        cx: &mut Context<'_>,
+        buf: &mut ReadBuf<'_>,
+    ) -> Poll<io::Result<()>> {
+        // Safety: `TcpStream::read` correctly handles reads into uninitialized memory
+        unsafe { self.io.poll_read(cx, buf) }
+    }
+
+    pub(super) fn poll_write_priv(
+        &self,
+        cx: &mut Context<'_>,
+        buf: &[u8],
+    ) -> Poll<io::Result<usize>> {
+        self.io.poll_write(cx, buf)
+    }
+
+    pub(super) fn poll_write_vectored_priv(
+        &self,
+        cx: &mut Context<'_>,
+        bufs: &[io::IoSlice<'_>],
+    ) -> Poll<io::Result<usize>> {
+        self.io.poll_write_vectored(cx, bufs)
+    }
+}
+
+impl TryFrom<std::net::TcpStream> for TcpStream {
+    type Error = io::Error;
+
+    /// Consumes stream, returning the tokio I/O object.
+    ///
+    /// This is equivalent to
+    /// [`TcpStream::from_std(stream)`](TcpStream::from_std).
+    fn try_from(stream: std::net::TcpStream) -> Result<Self, Self::Error> {
+        Self::from_std(stream)
+    }
+}
+
+// ===== impl Read / Write =====
+
+impl AsyncRead for TcpStream {
+    fn poll_read(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &mut ReadBuf<'_>,
+    ) -> Poll<io::Result<()>> {
+        self.poll_read_priv(cx, buf)
+    }
+}
+
+impl AsyncWrite for TcpStream {
+    fn poll_write(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &[u8],
+    ) -> Poll<io::Result<usize>> {
+        self.poll_write_priv(cx, buf)
+    }
+
+    fn poll_write_vectored(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        bufs: &[io::IoSlice<'_>],
+    ) -> Poll<io::Result<usize>> {
+        self.poll_write_vectored_priv(cx, bufs)
+    }
+
+    fn is_write_vectored(&self) -> bool {
+        true
+    }
+
+    #[inline]
+    fn poll_flush(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<io::Result<()>> {
+        // tcp flush is a no-op
+        Poll::Ready(Ok(()))
+    }
+
+    fn poll_shutdown(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<io::Result<()>> {
+        self.shutdown_std(std::net::Shutdown::Write)?;
+        Poll::Ready(Ok(()))
+    }
+}
+
+impl fmt::Debug for TcpStream {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.io.fmt(f)
+    }
+}
+
+#[cfg(unix)]
+mod sys {
+    use super::TcpStream;
+    use std::os::unix::prelude::*;
+
+    impl AsRawFd for TcpStream {
+        fn as_raw_fd(&self) -> RawFd {
+            self.io.as_raw_fd()
+        }
+    }
+}
+
+#[cfg(windows)]
+mod sys {
+    use super::TcpStream;
+    use std::os::windows::prelude::*;
+
+    impl AsRawSocket for TcpStream {
+        fn as_raw_socket(&self) -> RawSocket {
+            self.io.as_raw_socket()
+        }
+    }
+}