# socket.rs - source
Source of the Rust file `/home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/socket2-0.3.19/src/socket.rs`.
Keywords: rust, rustlang, rust-lang

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    // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
    // file at the top-level directory of this distribution and at
    // http://rust-lang.org/COPYRIGHT.
    //
    // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
    // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
    // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
    // option. This file may not be copied, modified, or distributed
    // except according to those terms.

    #[cfg(target_os = "linux")]
    use std::ffi::{CStr, CString};
    use std::fmt;
    use std::io::{self, Read, Write};
    use std::net::{self, Ipv4Addr, Ipv6Addr, Shutdown};
    #[cfg(all(unix, feature = "unix"))]
    use std::os::unix::net::{UnixDatagram, UnixListener, UnixStream};
    use std::time::Duration;

    #[cfg(any(unix, target_os = "redox"))]
    use libc::MSG_OOB;
    #[cfg(windows)]
    use winapi::um::winsock2::MSG_OOB;

    use crate::sys;
    use crate::{Domain, Protocol, SockAddr, Type};

    /// Newtype, owned, wrapper around a system socket.
    ///
    /// This type simply wraps an instance of a file descriptor (`c_int`) on Unix
    /// and an instance of `SOCKET` on Windows. This is the main type exported by
    /// this crate and is intended to mirror the raw semantics of sockets on
    /// platforms as closely as possible. Almost all methods correspond to
    /// precisely one libc or OS API call which is essentially just a "Rustic
    /// translation" of what's below.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use std::net::SocketAddr;
    /// use socket2::{Socket, Domain, Type, SockAddr};
    ///
    /// // create a TCP listener bound to two addresses
    /// let socket = Socket::new(Domain::ipv4(), Type::stream(), None).unwrap();
    ///
    /// socket.bind(&"127.0.0.1:12345".parse::<SocketAddr>().unwrap().into()).unwrap();
    /// socket.bind(&"127.0.0.1:12346".parse::<SocketAddr>().unwrap().into()).unwrap();
    /// socket.listen(128).unwrap();
    ///
    /// let listener = socket.into_tcp_listener();
    /// // ...
    /// ```
    pub struct Socket {
        // The `sys` module most have access to the socket.
        pub(crate) inner: sys::Socket,
    }

    impl Socket {
        /// Creates a new socket ready to be configured.
        ///
        /// This function corresponds to `socket(2)` and simply creates a new
        /// socket, no other configuration is done and further functions must be
        /// invoked to configure this socket.
        pub fn new(domain: Domain, type_: Type, protocol: Option<Protocol>) -> io::Result<Socket> {
            let protocol = protocol.map(|p| p.0).unwrap_or(0);
            Ok(Socket {
                inner: sys::Socket::new(domain.0, type_.0, protocol)?,
            })
        }

        /// Creates a pair of sockets which are connected to each other.
        ///
        /// This function corresponds to `socketpair(2)`.
        ///
        /// This function is only available on Unix when the `pair` feature is
        /// enabled.
        #[cfg(all(unix, feature = "pair"))]
        pub fn pair(
            domain: Domain,
            type_: Type,
            protocol: Option<Protocol>,
        ) -> io::Result<(Socket, Socket)> {
            let protocol = protocol.map(|p| p.0).unwrap_or(0);
            let sockets = sys::Socket::pair(domain.0, type_.0, protocol)?;
            Ok((Socket { inner: sockets.0 }, Socket { inner: sockets.1 }))
        }

        /// Consumes this `Socket`, converting it to a `TcpStream`.
        pub fn into_tcp_stream(self) -> net::TcpStream {
            self.into()
        }

        /// Consumes this `Socket`, converting it to a `TcpListener`.
        pub fn into_tcp_listener(self) -> net::TcpListener {
            self.into()
        }

        /// Consumes this `Socket`, converting it to a `UdpSocket`.
        pub fn into_udp_socket(self) -> net::UdpSocket {
            self.into()
        }

        /// Consumes this `Socket`, converting it into a `UnixStream`.
        ///
        /// This function is only available on Unix when the `unix` feature is
        /// enabled.
        #[cfg(all(unix, feature = "unix"))]
        pub fn into_unix_stream(self) -> UnixStream {
            self.into()
        }

        /// Consumes this `Socket`, converting it into a `UnixListener`.
        ///
        /// This function is only available on Unix when the `unix` feature is
        /// enabled.
        #[cfg(all(unix, feature = "unix"))]
        pub fn into_unix_listener(self) -> UnixListener {
            self.into()
        }

        /// Consumes this `Socket`, converting it into a `UnixDatagram`.
        ///
        /// This function is only available on Unix when the `unix` feature is
        /// enabled.
        #[cfg(all(unix, feature = "unix"))]
        pub fn into_unix_datagram(self) -> UnixDatagram {
            self.into()
        }

        /// Initiate a connection on this socket to the specified address.
        ///
        /// This function directly corresponds to the connect(2) function on Windows
        /// and Unix.
        ///
        /// An error will be returned if `listen` or `connect` has already been
        /// called on this builder.
        pub fn connect(&self, addr: &SockAddr) -> io::Result<()> {
            self.inner.connect(addr)
        }

        /// Initiate a connection on this socket to the specified address, only
        /// only waiting for a certain period of time for the connection to be
        /// established.
        ///
        /// Unlike many other methods on `Socket`, this does *not* correspond to a
        /// single C function. It sets the socket to nonblocking mode, connects via
        /// connect(2), and then waits for the connection to complete with poll(2)
        /// on Unix and select on Windows. When the connection is complete, the
        /// socket is set back to blocking mode. On Unix, this will loop over
        /// `EINTR` errors.
        ///
        /// # Warnings
        ///
        /// The nonblocking state of the socket is overridden by this function -
        /// it will be returned in blocking mode on success, and in an indeterminate
        /// state on failure.
        ///
        /// If the connection request times out, it may still be processing in the
        /// background - a second call to `connect` or `connect_timeout` may fail.
        pub fn connect_timeout(&self, addr: &SockAddr, timeout: Duration) -> io::Result<()> {
            self.inner.connect_timeout(addr, timeout)
        }

        /// Binds this socket to the specified address.
        ///
        /// This function directly corresponds to the bind(2) function on Windows
        /// and Unix.
        pub fn bind(&self, addr: &SockAddr) -> io::Result<()> {
            self.inner.bind(addr)
        }

        /// Mark a socket as ready to accept incoming connection requests using
        /// accept()
        ///
        /// This function directly corresponds to the listen(2) function on Windows
        /// and Unix.
        ///
        /// An error will be returned if `listen` or `connect` has already been
        /// called on this builder.
        pub fn listen(&self, backlog: i32) -> io::Result<()> {
            self.inner.listen(backlog)
        }

        /// Accept a new incoming connection from this listener.
        ///
        /// This function will block the calling thread until a new connection is
        /// established. When established, the corresponding `Socket` and the
        /// remote peer's address will be returned.
        pub fn accept(&self) -> io::Result<(Socket, SockAddr)> {
            self.inner
                .accept()
                .map(|(socket, addr)| (Socket { inner: socket }, addr))
        }

        /// Returns the socket address of the local half of this TCP connection.
        pub fn local_addr(&self) -> io::Result<SockAddr> {
            self.inner.local_addr()
        }

        /// Returns the socket address of the remote peer of this TCP connection.
        pub fn peer_addr(&self) -> io::Result<SockAddr> {
            self.inner.peer_addr()
        }

        /// Creates a new independently owned handle to the underlying socket.
        ///
        /// The returned `TcpStream` is a reference to the same stream that this
        /// object references. Both handles will read and write the same stream of
        /// data, and options set on one stream will be propagated to the other
        /// stream.
        pub fn try_clone(&self) -> io::Result<Socket> {
            self.inner.try_clone().map(|s| Socket { inner: s })
        }

        /// Get the value of the `SO_ERROR` option on this socket.
        ///
        /// This will retrieve the stored error in the underlying socket, clearing
        /// the field in the process. This can be useful for checking errors between
        /// calls.
        pub fn take_error(&self) -> io::Result<Option<io::Error>> {
            self.inner.take_error()
        }

        /// Moves this TCP stream into or out of nonblocking mode.
        ///
        /// On Unix this corresponds to calling fcntl, and on Windows this
        /// corresponds to calling ioctlsocket.
        pub fn set_nonblocking(&self, nonblocking: bool) -> io::Result<()> {
            self.inner.set_nonblocking(nonblocking)
        }

        /// 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.
        pub fn shutdown(&self, how: Shutdown) -> io::Result<()> {
            self.inner.shutdown(how)
        }

        /// Receives data on the socket from the remote address to which it is
        /// connected.
        ///
        /// The [`connect`] method will connect this socket to a remote address. This
        /// method will fail if the socket is not connected.
        ///
        /// [`connect`]: #method.connect
        pub fn recv(&self, buf: &mut [u8]) -> io::Result<usize> {
            self.inner.recv(buf, 0)
        }

        /// Identical to [`recv`] but allows for specification of arbitrary flags to the underlying
        /// `recv` call.
        ///
        /// [`recv`]: #method.recv
        pub fn recv_with_flags(&self, buf: &mut [u8], flags: i32) -> io::Result<usize> {
            self.inner.recv(buf, flags)
        }

        /// Receives out-of-band (OOB) data on the socket from the remote address to
        /// which it is connected by setting the `MSG_OOB` flag for this call.
        ///
        /// For more information, see [`recv`], [`out_of_band_inline`].
        ///
        /// [`recv`]: #method.recv
        /// [`out_of_band_inline`]: #method.out_of_band_inline
        pub fn recv_out_of_band(&self, buf: &mut [u8]) -> io::Result<usize> {
            self.inner.recv(buf, MSG_OOB)
        }

        /// Receives data on the socket from the remote adress 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.
        pub fn peek(&self, buf: &mut [u8]) -> io::Result<usize> {
            self.inner.peek(buf)
        }

        /// Receives data from the socket. On success, returns the number of bytes
        /// read and the address from whence the data came.
        pub fn recv_from(&self, buf: &mut [u8]) -> io::Result<(usize, SockAddr)> {
            self.inner.recv_from(buf, 0)
        }

        /// Identical to [`recv_from`] but allows for specification of arbitrary flags to the underlying
        /// `recvfrom` call.
        ///
        /// [`recv_from`]: #method.recv_from
        pub fn recv_from_with_flags(
            &self,
            buf: &mut [u8],
            flags: i32,
        ) -> io::Result<(usize, SockAddr)> {
            self.inner.recv_from(buf, flags)
        }

        /// Receives data from the socket, without removing it from the queue.
        ///
        /// Successive calls return the same data. This is accomplished by passing
        /// `MSG_PEEK` as a flag to the underlying `recvfrom` system call.
        ///
        /// On success, returns the number of bytes peeked and the address from
        /// whence the data came.
        pub fn peek_from(&self, buf: &mut [u8]) -> io::Result<(usize, SockAddr)> {
            self.inner.peek_from(buf)
        }

        /// Sends data on the socket to a connected peer.
        ///
        /// This is typically used on TCP sockets or datagram sockets which have
        /// been connected.
        ///
        /// On success returns the number of bytes that were sent.
        pub fn send(&self, buf: &[u8]) -> io::Result<usize> {
            self.inner.send(buf, 0)
        }

        /// Identical to [`send`] but allows for specification of arbitrary flags to the underlying
        /// `send` call.
        ///
        /// [`send`]: #method.send
        pub fn send_with_flags(&self, buf: &[u8], flags: i32) -> io::Result<usize> {
            self.inner.send(buf, flags)
        }

        /// Sends out-of-band (OOB) data on the socket to connected peer
        /// by setting the `MSG_OOB` flag for this call.
        ///
        /// For more information, see [`send`], [`out_of_band_inline`].
        ///
        /// [`send`]: #method.send
        /// [`out_of_band_inline`]: #method.out_of_band_inline
        pub fn send_out_of_band(&self, buf: &[u8]) -> io::Result<usize> {
            self.inner.send(buf, MSG_OOB)
        }

        /// Sends data on the socket to the given address. On success, returns the
        /// number of bytes written.
        ///
        /// This is typically used on UDP or datagram-oriented sockets. On success
        /// returns the number of bytes that were sent.
        pub fn send_to(&self, buf: &[u8], addr: &SockAddr) -> io::Result<usize> {
            self.inner.send_to(buf, 0, addr)
        }

        /// Identical to [`send_to`] but allows for specification of arbitrary flags to the underlying
        /// `sendto` call.
        ///
        /// [`send_to`]: #method.send_to
        pub fn send_to_with_flags(&self, buf: &[u8], addr: &SockAddr, flags: i32) -> io::Result<usize> {
            self.inner.send_to(buf, flags, addr)
        }

        // ================================================

        /// Gets the value of the `IP_TTL` option for this socket.
        ///
        /// For more information about this option, see [`set_ttl`][link].
        ///
        /// [link]: #method.set_ttl
        pub fn ttl(&self) -> io::Result<u32> {
            self.inner.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.
        pub fn set_ttl(&self, ttl: u32) -> io::Result<()> {
            self.inner.set_ttl(ttl)
        }

        /// Gets the value of the `TCP_MAXSEG` option on this socket.
        ///
        /// The `TCP_MAXSEG` option denotes the TCP Maximum Segment
        /// Size and is only available on TCP sockets.
        #[cfg(all(unix, not(target_os = "redox")))]
        pub fn mss(&self) -> io::Result<u32> {
            self.inner.mss()
        }

        /// Sets the value of the `TCP_MAXSEG` option on this socket.
        ///
        /// The `TCP_MAXSEG` option denotes the TCP Maximum Segment
        /// Size and is only available on TCP sockets.
        #[cfg(all(unix, not(target_os = "redox")))]
        pub fn set_mss(&self, mss: u32) -> io::Result<()> {
            self.inner.set_mss(mss)
        }

        /// Gets the value for the `SO_MARK` option on this socket.
        ///
        /// This value gets the socket mark field for each packet sent through
        /// this socket.
        ///
        /// This function is only available on Linux and requires the
        /// `CAP_NET_ADMIN` capability.
        #[cfg(target_os = "linux")]
        pub fn mark(&self) -> io::Result<u32> {
            self.inner.mark()
        }

        /// Sets the value for the `SO_MARK` option on this socket.
        ///
        /// This value sets the socket mark field for each packet sent through
        /// this socket. Changing the mark can be used for mark-based routing
        /// without netfilter or for packet filtering.
        ///
        /// This function is only available on Linux and requires the
        /// `CAP_NET_ADMIN` capability.
        #[cfg(target_os = "linux")]
        pub fn set_mark(&self, mark: u32) -> io::Result<()> {
            self.inner.set_mark(mark)
        }

        /// Gets the value for the `SO_BINDTODEVICE` option on this socket.
        ///
        /// This value gets the socket binded device's interface name.
        ///
        /// This function is only available on Linux.
        #[cfg(target_os = "linux")]
        pub fn device(&self) -> io::Result<Option<CString>> {
            self.inner.device()
        }

        /// Sets the value for the `SO_BINDTODEVICE` option on this socket.
        ///
        /// If a socket is bound to an interface, only packets received from that
        /// particular interface are processed by the socket. Note that this only
        /// works for some socket types, particularly `AF_INET` sockets.
        ///
        /// If `interface` is `None` or an empty string it removes the binding.
        ///
        /// This function is only available on Linux.
        #[cfg(target_os = "linux")]
        pub fn bind_device(&self, interface: Option<&CStr>) -> io::Result<()> {
            self.inner.bind_device(interface)
        }

        /// Gets the value of the `IPV6_UNICAST_HOPS` option for this socket.
        ///
        /// Specifies the hop limit for ipv6 unicast packets
        pub fn unicast_hops_v6(&self) -> io::Result<u32> {
            self.inner.unicast_hops_v6()
        }

        /// Sets the value for the `IPV6_UNICAST_HOPS` option on this socket.
        ///
        /// Specifies the hop limit for ipv6 unicast packets
        pub fn set_unicast_hops_v6(&self, ttl: u32) -> io::Result<()> {
            self.inner.set_unicast_hops_v6(ttl)
        }

        /// Gets the value of the `IPV6_V6ONLY` option for this socket.
        ///
        /// For more information about this option, see [`set_only_v6`][link].
        ///
        /// [link]: #method.set_only_v6
        pub fn only_v6(&self) -> io::Result<bool> {
            self.inner.only_v6()
        }

        /// Sets the value for the `IPV6_V6ONLY` option on this socket.
        ///
        /// If this is set to `true` then the socket is restricted to sending and
        /// receiving IPv6 packets only. In this case two IPv4 and IPv6 applications
        /// can bind the same port at the same time.
        ///
        /// If this is set to `false` then the socket can be used to send and
        /// receive packets from an IPv4-mapped IPv6 address.
        pub fn set_only_v6(&self, only_v6: bool) -> io::Result<()> {
            self.inner.set_only_v6(only_v6)
        }

        /// Returns the read timeout of this socket.
        ///
        /// If the timeout is `None`, then `read` calls will block indefinitely.
        pub fn read_timeout(&self) -> io::Result<Option<Duration>> {
            self.inner.read_timeout()
        }

        /// Sets the read timeout to the timeout specified.
        ///
        /// If the value specified is `None`, then `read` calls will block
        /// indefinitely. It is an error to pass the zero `Duration` to this
        /// method.
        pub fn set_read_timeout(&self, dur: Option<Duration>) -> io::Result<()> {
            self.inner.set_read_timeout(dur)
        }

        /// Returns the write timeout of this socket.
        ///
        /// If the timeout is `None`, then `write` calls will block indefinitely.
        pub fn write_timeout(&self) -> io::Result<Option<Duration>> {
            self.inner.write_timeout()
        }

        /// Sets the write timeout to the timeout specified.
        ///
        /// If the value specified is `None`, then `write` calls will block
        /// indefinitely. It is an error to pass the zero `Duration` to this
        /// method.
        pub fn set_write_timeout(&self, dur: Option<Duration>) -> io::Result<()> {
            self.inner.set_write_timeout(dur)
        }

        /// Gets the value of the `TCP_NODELAY` option on this socket.
        ///
        /// For more information about this option, see [`set_nodelay`][link].
        ///
        /// [link]: #method.set_nodelay
        pub fn nodelay(&self) -> io::Result<bool> {
            self.inner.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.
        pub fn set_nodelay(&self, nodelay: bool) -> io::Result<()> {
            self.inner.set_nodelay(nodelay)
        }

        /// Sets the value of the `SO_BROADCAST` option for this socket.
        ///
        /// When enabled, this socket is allowed to send packets to a broadcast
        /// address.
        pub fn broadcast(&self) -> io::Result<bool> {
            self.inner.broadcast()
        }

        /// Gets the value of the `SO_BROADCAST` option for this socket.
        ///
        /// For more information about this option, see
        /// [`set_broadcast`][link].
        ///
        /// [link]: #method.set_broadcast
        pub fn set_broadcast(&self, broadcast: bool) -> io::Result<()> {
            self.inner.set_broadcast(broadcast)
        }

        /// Gets the value of the `IP_MULTICAST_LOOP` option for this socket.
        ///
        /// For more information about this option, see
        /// [`set_multicast_loop_v4`][link].
        ///
        /// [link]: #method.set_multicast_loop_v4
        pub fn multicast_loop_v4(&self) -> io::Result<bool> {
            self.inner.multicast_loop_v4()
        }

        /// Sets the value of the `IP_MULTICAST_LOOP` option for this socket.
        ///
        /// If enabled, multicast packets will be looped back to the local socket.
        /// Note that this may not have any affect on IPv6 sockets.
        pub fn set_multicast_loop_v4(&self, multicast_loop_v4: bool) -> io::Result<()> {
            self.inner.set_multicast_loop_v4(multicast_loop_v4)
        }

        /// Gets the value of the `IP_MULTICAST_TTL` option for this socket.
        ///
        /// For more information about this option, see
        /// [`set_multicast_ttl_v4`][link].
        ///
        /// [link]: #method.set_multicast_ttl_v4
        pub fn multicast_ttl_v4(&self) -> io::Result<u32> {
            self.inner.multicast_ttl_v4()
        }

        /// Sets the value of the `IP_MULTICAST_TTL` option for this socket.
        ///
        /// Indicates the time-to-live value of outgoing multicast packets for
        /// this socket. The default value is 1 which means that multicast packets
        /// don't leave the local network unless explicitly requested.
        ///
        /// Note that this may not have any affect on IPv6 sockets.
        pub fn set_multicast_ttl_v4(&self, multicast_ttl_v4: u32) -> io::Result<()> {
            self.inner.set_multicast_ttl_v4(multicast_ttl_v4)
        }

        /// Gets the value of the `IPV6_MULTICAST_HOPS` option for this socket
        ///
        /// For more information about this option, see
        /// [`set_multicast_hops_v6`][link].
        ///
        /// [link]: #method.set_multicast_hops_v6
        pub fn multicast_hops_v6(&self) -> io::Result<u32> {
            self.inner.multicast_hops_v6()
        }

        /// Sets the value of the `IPV6_MULTICAST_HOPS` option for this socket
        ///
        /// Indicates the number of "routers" multicast packets will transit for
        /// this socket. The default value is 1 which means that multicast packets
        /// don't leave the local network unless explicitly requested.
        pub fn set_multicast_hops_v6(&self, hops: u32) -> io::Result<()> {
            self.inner.set_multicast_hops_v6(hops)
        }

        /// Gets the value of the `IP_MULTICAST_IF` option for this socket.
        ///
        /// For more information about this option, see
        /// [`set_multicast_if_v4`][link].
        ///
        /// [link]: #method.set_multicast_if_v4
        ///
        /// Returns the interface to use for routing multicast packets.
        pub fn multicast_if_v4(&self) -> io::Result<Ipv4Addr> {
            self.inner.multicast_if_v4()
        }

        /// Sets the value of the `IP_MULTICAST_IF` option for this socket.
        ///
        /// Specifies the interface to use for routing multicast packets.
        pub fn set_multicast_if_v4(&self, interface: &Ipv4Addr) -> io::Result<()> {
            self.inner.set_multicast_if_v4(interface)
        }

        /// Gets the value of the `IPV6_MULTICAST_IF` option for this socket.
        ///
        /// For more information about this option, see
        /// [`set_multicast_if_v6`][link].
        ///
        /// [link]: #method.set_multicast_if_v6
        ///
        /// Returns the interface to use for routing multicast packets.
        pub fn multicast_if_v6(&self) -> io::Result<u32> {
            self.inner.multicast_if_v6()
        }

        /// Sets the value of the `IPV6_MULTICAST_IF` option for this socket.
        ///
        /// Specifies the interface to use for routing multicast packets. Unlike ipv4, this
        /// is generally required in ipv6 contexts where network routing prefixes may
        /// overlap.
        pub fn set_multicast_if_v6(&self, interface: u32) -> io::Result<()> {
            self.inner.set_multicast_if_v6(interface)
        }

        /// Gets the value of the `IPV6_MULTICAST_LOOP` option for this socket.
        ///
        /// For more information about this option, see
        /// [`set_multicast_loop_v6`][link].
        ///
        /// [link]: #method.set_multicast_loop_v6
        pub fn multicast_loop_v6(&self) -> io::Result<bool> {
            self.inner.multicast_loop_v6()
        }

        /// Sets the value of the `IPV6_MULTICAST_LOOP` option for this socket.
        ///
        /// Controls whether this socket sees the multicast packets it sends itself.
        /// Note that this may not have any affect on IPv4 sockets.
        pub fn set_multicast_loop_v6(&self, multicast_loop_v6: bool) -> io::Result<()> {
            self.inner.set_multicast_loop_v6(multicast_loop_v6)
        }

        /// Executes an operation of the `IP_ADD_MEMBERSHIP` type.
        ///
        /// This function specifies a new multicast group for this socket to join.
        /// The address must be a valid multicast address, and `interface` is the
        /// address of the local interface with which the system should join the
        /// multicast group. If it's equal to `INADDR_ANY` then an appropriate
        /// interface is chosen by the system.
        pub fn join_multicast_v4(&self, multiaddr: &Ipv4Addr, interface: &Ipv4Addr) -> io::Result<()> {
            self.inner.join_multicast_v4(multiaddr, interface)
        }

        /// Executes an operation of the `IPV6_ADD_MEMBERSHIP` type.
        ///
        /// This function specifies a new multicast group for this socket to join.
        /// The address must be a valid multicast address, and `interface` is the
        /// index of the interface to join/leave (or 0 to indicate any interface).
        pub fn join_multicast_v6(&self, multiaddr: &Ipv6Addr, interface: u32) -> io::Result<()> {
            self.inner.join_multicast_v6(multiaddr, interface)
        }

        /// Executes an operation of the `IP_DROP_MEMBERSHIP` type.
        ///
        /// For more information about this option, see
        /// [`join_multicast_v4`][link].
        ///
        /// [link]: #method.join_multicast_v4
        pub fn leave_multicast_v4(&self, multiaddr: &Ipv4Addr, interface: &Ipv4Addr) -> io::Result<()> {
            self.inner.leave_multicast_v4(multiaddr, interface)
        }

        /// Executes an operation of the `IPV6_DROP_MEMBERSHIP` type.
        ///
        /// For more information about this option, see
        /// [`join_multicast_v6`][link].
        ///
        /// [link]: #method.join_multicast_v6
        pub fn leave_multicast_v6(&self, multiaddr: &Ipv6Addr, interface: u32) -> io::Result<()> {
            self.inner.leave_multicast_v6(multiaddr, interface)
        }

        /// Reads the linger duration for this socket by getting the SO_LINGER
        /// option
        pub fn linger(&self) -> io::Result<Option<Duration>> {
            self.inner.linger()
        }

        /// Sets the linger duration of this socket by setting the SO_LINGER option
        pub fn set_linger(&self, dur: Option<Duration>) -> io::Result<()> {
            self.inner.set_linger(dur)
        }

        /// Check the `SO_REUSEADDR` option on this socket.
        pub fn reuse_address(&self) -> io::Result<bool> {
            self.inner.reuse_address()
        }

        /// Set value for the `SO_REUSEADDR` option on this socket.
        ///
        /// This indicates that futher calls to `bind` may allow reuse of local
        /// addresses. For IPv4 sockets this means that a socket may bind even when
        /// there's a socket already listening on this port.
        pub fn set_reuse_address(&self, reuse: bool) -> io::Result<()> {
            self.inner.set_reuse_address(reuse)
        }

        /// Gets the value of the `SO_RCVBUF` option on this socket.
        ///
        /// For more information about this option, see
        /// [`set_recv_buffer_size`][link].
        ///
        /// [link]: #method.set_recv_buffer_size
        pub fn recv_buffer_size(&self) -> io::Result<usize> {
            self.inner.recv_buffer_size()
        }

        /// Sets the value of the `SO_RCVBUF` option on this socket.
        ///
        /// Changes the size of the operating system's receive buffer associated
        /// with the socket.
        pub fn set_recv_buffer_size(&self, size: usize) -> io::Result<()> {
            self.inner.set_recv_buffer_size(size)
        }

        /// Gets the value of the `SO_SNDBUF` option on this socket.
        ///
        /// For more information about this option, see [`set_send_buffer`][link].
        ///
        /// [link]: #method.set_send_buffer
        pub fn send_buffer_size(&self) -> io::Result<usize> {
            self.inner.send_buffer_size()
        }

        /// Sets the value of the `SO_SNDBUF` option on this socket.
        ///
        /// Changes the size of the operating system's send buffer associated with
        /// the socket.
        pub fn set_send_buffer_size(&self, size: usize) -> io::Result<()> {
            self.inner.set_send_buffer_size(size)
        }

        /// Returns whether keepalive messages are enabled on this socket, and if so
        /// the duration of time between them.
        ///
        /// For more information about this option, see [`set_keepalive`][link].
        ///
        /// [link]: #method.set_keepalive
        pub fn keepalive(&self) -> io::Result<Option<Duration>> {
            self.inner.keepalive()
        }

        /// Sets whether keepalive messages are enabled to be sent on this socket.
        ///
        /// On Unix, this option will set the `SO_KEEPALIVE` as well as the
        /// `TCP_KEEPALIVE` or `TCP_KEEPIDLE` option (depending on your platform).
        /// On Windows, this will set the `SIO_KEEPALIVE_VALS` option.
        ///
        /// If `None` is specified then keepalive messages are disabled, otherwise
        /// the duration specified will be the time to remain idle before sending a
        /// TCP keepalive probe.
        ///
        /// Some platforms specify this value in seconds, so sub-second
        /// specifications may be omitted.
        pub fn set_keepalive(&self, keepalive: Option<Duration>) -> io::Result<()> {
            self.inner.set_keepalive(keepalive)
        }

        /// Returns the value of the `SO_OOBINLINE` flag of the underlying socket.
        /// For more information about this option, see [`set_out_of_band_inline`][link].
        ///
        /// [link]: #method.set_out_of_band_inline
        pub fn out_of_band_inline(&self) -> io::Result<bool> {
            self.inner.out_of_band_inline()
        }

        /// Sets the `SO_OOBINLINE` flag of the underlying socket.
        /// as per RFC6093, TCP sockets using the Urgent mechanism
        /// are encouraged to set this flag.
        ///
        /// If this flag is not set, the `MSG_OOB` flag is needed
        /// while `recv`ing to aquire the out-of-band data.
        pub fn set_out_of_band_inline(&self, oob_inline: bool) -> io::Result<()> {
            self.inner.set_out_of_band_inline(oob_inline)
        }

        /// Check the value of the `SO_REUSEPORT` option on this socket.
        ///
        /// This function is only available on Unix when the `reuseport` feature is
        /// enabled.
        #[cfg(all(
            unix,
            not(any(target_os = "solaris", target_os = "illumos")),
            feature = "reuseport"
        ))]
        pub fn reuse_port(&self) -> io::Result<bool> {
            self.inner.reuse_port()
        }

        /// Set value for the `SO_REUSEPORT` option on this socket.
        ///
        /// This indicates that further calls to `bind` may allow reuse of local
        /// addresses. For IPv4 sockets this means that a socket may bind even when
        /// there's a socket already listening on this port.
        ///
        /// This function is only available on Unix when the `reuseport` feature is
        /// enabled.
        #[cfg(all(
            unix,
            not(any(target_os = "solaris", target_os = "illumos")),
            feature = "reuseport"
        ))]
        pub fn set_reuse_port(&self, reuse: bool) -> io::Result<()> {
            self.inner.set_reuse_port(reuse)
        }
    }

    impl Read for Socket {
        fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
            self.inner.read(buf)
        }
    }

    impl<'a> Read for &'a Socket {
        fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
            (&self.inner).read(buf)
        }
    }

    impl Write for Socket {
        fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
            self.inner.write(buf)
        }

        fn flush(&mut self) -> io::Result<()> {
            self.inner.flush()
        }
    }

    impl<'a> Write for &'a Socket {
        fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
            (&self.inner).write(buf)
        }

        fn flush(&mut self) -> io::Result<()> {
            (&self.inner).flush()
        }
    }

    impl fmt::Debug for Socket {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            self.inner.fmt(f)
        }
    }

    impl From<net::TcpStream> for Socket {
        fn from(socket: net::TcpStream) -> Socket {
            Socket {
                inner: socket.into(),
            }
        }
    }

    impl From<net::TcpListener> for Socket {
        fn from(socket: net::TcpListener) -> Socket {
            Socket {
                inner: socket.into(),
            }
        }
    }

    impl From<net::UdpSocket> for Socket {
        fn from(socket: net::UdpSocket) -> Socket {
            Socket {
                inner: socket.into(),
            }
        }
    }

    #[cfg(all(unix, feature = "unix"))]
    impl From<UnixStream> for Socket {
        fn from(socket: UnixStream) -> Socket {
            Socket {
                inner: socket.into(),
            }
        }
    }

    #[cfg(all(unix, feature = "unix"))]
    impl From<UnixListener> for Socket {
        fn from(socket: UnixListener) -> Socket {
            Socket {
                inner: socket.into(),
            }
        }
    }

    #[cfg(all(unix, feature = "unix"))]
    impl From<UnixDatagram> for Socket {
        fn from(socket: UnixDatagram) -> Socket {
            Socket {
                inner: socket.into(),
            }
        }
    }

    impl From<Socket> for net::TcpStream {
        fn from(socket: Socket) -> net::TcpStream {
            socket.inner.into()
        }
    }

    impl From<Socket> for net::TcpListener {
        fn from(socket: Socket) -> net::TcpListener {
            socket.inner.into()
        }
    }

    impl From<Socket> for net::UdpSocket {
        fn from(socket: Socket) -> net::UdpSocket {
            socket.inner.into()
        }
    }

    #[cfg(all(unix, feature = "unix"))]
    impl From<Socket> for UnixStream {
        fn from(socket: Socket) -> UnixStream {
            socket.inner.into()
        }
    }

    #[cfg(all(unix, feature = "unix"))]
    impl From<Socket> for UnixListener {
        fn from(socket: Socket) -> UnixListener {
            socket.inner.into()
        }
    }

    #[cfg(all(unix, feature = "unix"))]
    impl From<Socket> for UnixDatagram {
        fn from(socket: Socket) -> UnixDatagram {
            socket.inner.into()
        }
    }

    #[cfg(test)]
    mod test {
        use std::net::SocketAddr;

        use super::*;

        #[test]
        fn connect_timeout_unrouteable() {
            // this IP is unroutable, so connections should always time out
            let addr = "10.255.255.1:80".parse::<SocketAddr>().unwrap().into();

            let socket = Socket::new(Domain::ipv4(), Type::stream(), None).unwrap();
            match socket.connect_timeout(&addr, Duration::from_millis(250)) {
                Ok(_) => panic!("unexpected success"),
                Err(ref e) if e.kind() == io::ErrorKind::TimedOut => {}
                Err(e) => panic!("unexpected error {}", e),
            }
        }

        #[test]
        fn connect_timeout_unbound() {
            // bind and drop a socket to track down a "probably unassigned" port
            let socket = Socket::new(Domain::ipv4(), Type::stream(), None).unwrap();
            let addr = "127.0.0.1:0".parse::<SocketAddr>().unwrap().into();
            socket.bind(&addr).unwrap();
            let addr = socket.local_addr().unwrap();
            drop(socket);

            let socket = Socket::new(Domain::ipv4(), Type::stream(), None).unwrap();
            match socket.connect_timeout(&addr, Duration::from_millis(250)) {
                Ok(_) => panic!("unexpected success"),
                Err(ref e)
                    if e.kind() == io::ErrorKind::ConnectionRefused
                        || e.kind() == io::ErrorKind::TimedOut => {}
                Err(e) => panic!("unexpected error {}", e),
            }
        }

        #[test]
        fn connect_timeout_valid() {
            let socket = Socket::new(Domain::ipv4(), Type::stream(), None).unwrap();
            socket
                .bind(&"127.0.0.1:0".parse::<SocketAddr>().unwrap().into())
                .unwrap();
            socket.listen(128).unwrap();

            let addr = socket.local_addr().unwrap();

            let socket = Socket::new(Domain::ipv4(), Type::stream(), None).unwrap();
            socket
                .connect_timeout(&addr, Duration::from_millis(250))
                .unwrap();
        }

        #[test]
        #[cfg(all(unix, feature = "pair", feature = "unix"))]
        fn pair() {
            let (mut a, mut b) = Socket::pair(Domain::unix(), Type::stream(), None).unwrap();
            a.write_all(b"hello world").unwrap();
            let mut buf = [0; 11];
            b.read_exact(&mut buf).unwrap();
            assert_eq!(buf, &b"hello world"[..]);
        }

        #[test]
        #[cfg(all(unix, feature = "unix"))]
        fn unix() {
            use tempdir::TempDir;

            let dir = TempDir::new("unix").unwrap();
            let addr = SockAddr::unix(dir.path().join("sock")).unwrap();

            let listener = Socket::new(Domain::unix(), Type::stream(), None).unwrap();
            listener.bind(&addr).unwrap();
            listener.listen(10).unwrap();

            let mut a = Socket::new(Domain::unix(), Type::stream(), None).unwrap();
            a.connect(&addr).unwrap();

            let mut b = listener.accept().unwrap().0;

            a.write_all(b"hello world").unwrap();
            let mut buf = [0; 11];
            b.read_exact(&mut buf).unwrap();
            assert_eq!(buf, &b"hello world"[..]);
        }

        #[test]
        fn keepalive() {
            let socket = Socket::new(Domain::ipv4(), Type::stream(), None).unwrap();
            socket.set_keepalive(Some(Duration::from_secs(7))).unwrap();
            // socket.keepalive() doesn't work on Windows #24
            #[cfg(unix)]
            assert_eq!(socket.keepalive().unwrap(), Some(Duration::from_secs(7)));
            socket.set_keepalive(None).unwrap();
            #[cfg(unix)]
            assert_eq!(socket.keepalive().unwrap(), None);
        }

        #[test]
        fn nodelay() {
            let socket = Socket::new(Domain::ipv4(), Type::stream(), None).unwrap();

            assert!(socket.set_nodelay(true).is_ok());

            let result = socket.nodelay();

            assert!(result.is_ok());
            assert!(result.unwrap());
        }

        #[test]
        fn out_of_band_inline() {
            let socket = Socket::new(Domain::ipv4(), Type::stream(), None).unwrap();

            assert_eq!(socket.out_of_band_inline().unwrap(), false);

            socket.set_out_of_band_inline(true).unwrap();
            assert_eq!(socket.out_of_band_inline().unwrap(), true);
        }

        #[test]
        #[cfg(any(target_os = "windows", target_os = "linux"))]
        fn out_of_band_send_recv() {
            let s1 = Socket::new(Domain::ipv4(), Type::stream(), None).unwrap();
            s1.bind(&"127.0.0.1:0".parse::<SocketAddr>().unwrap().into())
                .unwrap();
            let s1_addr = s1.local_addr().unwrap();
            s1.listen(1).unwrap();

            let s2 = Socket::new(Domain::ipv4(), Type::stream(), None).unwrap();
            s2.connect(&s1_addr).unwrap();

            let (s3, _) = s1.accept().unwrap();

            let mut buf = [0; 10];
            // send some plain inband data
            s2.send(&mut buf).unwrap();
            // send a single out of band byte
            assert_eq!(s2.send_out_of_band(&mut [b"!"[0]]).unwrap(), 1);
            // recv the OOB data first
            assert_eq!(s3.recv_out_of_band(&mut buf).unwrap(), 1);
            assert_eq!(buf[0], b"!"[0]);
            assert_eq!(s3.recv(&mut buf).unwrap(), 10);
        }

        #[test]
        fn tcp() {
            let s1 = Socket::new(Domain::ipv4(), Type::stream(), None).unwrap();
            s1.bind(&"127.0.0.1:0".parse::<SocketAddr>().unwrap().into())
                .unwrap();
            let s1_addr = s1.local_addr().unwrap();
            s1.listen(1).unwrap();

            let s2 = Socket::new(Domain::ipv4(), Type::stream(), None).unwrap();
            s2.connect(&s1_addr).unwrap();

            let (s3, _) = s1.accept().unwrap();

            let mut buf = [0; 11];
            assert_eq!(s2.send(&mut buf).unwrap(), 11);
            assert_eq!(s3.recv(&mut buf).unwrap(), 11);
        }
    }