# socket.rs - source
Source of the Rust file `/home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/net/tcp/socket.rs`.
Keywords: rust, rustlang, rust-lang

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    use crate::net::{TcpListener, TcpStream};

    use std::fmt;
    use std::io;
    use std::net::SocketAddr;

    #[cfg(unix)]
    use std::os::unix::io::{AsRawFd, FromRawFd, RawFd};
    #[cfg(windows)]
    use std::os::windows::io::{AsRawSocket, FromRawSocket, IntoRawSocket, RawSocket};

    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/
        pub struct TcpSocket {
            inner: mio::net::TcpSocket,
        }
    }

    impl TcpSocket {
        /// Create 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> {
            let inner = mio::net::TcpSocket::new_v4()?;
            Ok(TcpSocket { inner })
        }

        /// Create 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> {
            let inner = mio::net::TcpSocket::new_v6()?;
            Ok(TcpSocket { inner })
        }

        /// Allow 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_reuseaddr(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.get_reuseaddr()
        }

        /// Allow 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_reuseport(reuseport)
        }

        /// Allow 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.get_reuseport()
        }

        /// 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)
        }

        /// 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.get_send_buffer_size()
        }

        /// 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)
        }

        /// 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.get_recv_buffer_size()
        }

        /// Get 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.get_localaddr()
        }

        /// Bind 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)
        }

        /// Establish 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> {
            let mio = self.inner.connect(addr)?;
            TcpStream::connect_mio(mio).await
        }

        /// Convert 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
        /// operationg-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> {
            let mio = self.inner.listen(backlog)?;
            TcpListener::new(mio)
        }
    }

    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 = mio::net::TcpSocket::from_raw_fd(fd);
            TcpSocket { inner }
        }
    }

    #[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 = mio::net::TcpSocket::from_raw_socket(socket);
            TcpSocket { inner }
        }
    }