vendor/rustix/src/net/sockopt.rs - toolchain/rustc - Git at Google

 //! `getsockopt` and `setsockopt` functions.
 //!
 //! In the rustix API, there is a separate function for each option, so that
 //! it can be given an option-specific type signature.

 #![doc(alias = "getsockopt")]
 #![doc(alias = "setsockopt")]

 #[cfg(not(any(
     apple,
     windows,
     target_os = "aix",
     target_os = "dragonfly",
     target_os = "emscripten",
     target_os = "espidf",
     target_os = "haiku",
     target_os = "netbsd",
     target_os = "nto",
 )))]
 use crate::net::AddressFamily;
 use crate::net::{Ipv4Addr, Ipv6Addr, SocketType};
 use crate::{backend, io};
 use backend::c;
 use backend::fd::AsFd;
 use core::time::Duration;

 /// Timeout identifier for use with [`set_socket_timeout`] and
 /// [`get_socket_timeout`].
 ///
 /// [`set_socket_timeout`]: crate::net::sockopt::set_socket_timeout.
 /// [`get_socket_timeout`]: crate::net::sockopt::get_socket_timeout.
 #[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
 #[repr(u32)]
 pub enum Timeout {
     /// `SO_RCVTIMEO`—Timeout for receiving.
     Recv = c::SO_RCVTIMEO as _,

     /// `SO_SNDTIMEO`—Timeout for sending.
     Send = c::SO_SNDTIMEO as _,
 }

 /// `getsockopt(fd, SOL_SOCKET, SO_TYPE)`—Returns the type of a socket.
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `sys/socket.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `socket`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `SOL_SOCKET` options]
 ///  - [Apple]
 ///  - [FreeBSD]
 ///  - [NetBSD]
 ///  - [OpenBSD]
 ///  - [DragonFly BSD]
 ///  - [illumos]
 ///  - [glibc `getsockopt`]
 ///  - [glibc `SOL_SOCKET` Options]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `sys/socket.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_socket.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `socket`]: https://man7.org/linux/man-pages/man7/socket.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `SOL_SOCKET` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/sol-socket-socket-options
 /// [Apple]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getsockopt.2.html
 /// [FreeBSD]: https://man.freebsd.org/cgi/man.cgi?query=getsockopt&sektion=2
 /// [NetBSD]: https://man.netbsd.org/getsockopt.2
 /// [OpenBSD]: https://man.openbsd.org/getsockopt.2
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=getsockopt&section=2
 /// [illumos]: https://illumos.org/man/3SOCKET/getsockopt
 /// [glibc `getsockopt`]: https://www.gnu.org/software/libc/manual/html_node/Socket-Option-Functions.html
 /// [glibc `SOL_SOCKET` options]: https://www.gnu.org/software/libc/manual/html_node/Socket_002dLevel-Options.html
 #[inline]
 #[doc(alias = "SO_TYPE")]
 pub fn get_socket_type<Fd: AsFd>(fd: Fd) -> io::Result<SocketType> {
     backend::net::syscalls::sockopt::get_socket_type(fd.as_fd())
 }

 /// `setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, value)`
 ///
 /// # References
 ///  - [POSIX `setsockopt`]
 ///  - [POSIX `sys/socket.h`]
 ///  - [Linux `setsockopt`]
 ///  - [Linux `socket`]
 ///  - [Winsock2 `setsockopt`]
 ///  - [Winsock2 `SOL_SOCKET` options]
 ///  - [Apple]
 ///  - [FreeBSD]
 ///  - [NetBSD]
 ///  - [OpenBSD]
 ///  - [DragonFly BSD]
 ///  - [illumos]
 ///  - [glibc `setsockopt`]
 ///  - [glibc `SOL_SOCKET` Options]
 ///
 /// [POSIX `setsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/setsockopt.html
 /// [POSIX `sys/socket.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_socket.h.html
 /// [Linux `setsockopt`]: https://man7.org/linux/man-pages/man2/setsockopt.2.html
 /// [Linux `socket`]: https://man7.org/linux/man-pages/man7/socket.7.html
 /// [Winsock2 `setsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-setsockopt
 /// [Winsock2 `SOL_SOCKET` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/sol-socket-socket-options
 /// [Apple]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/setsockopt.2.html
 /// [FreeBSD]: https://man.freebsd.org/cgi/man.cgi?query=setsockopt&sektion=2
 /// [NetBSD]: https://man.netbsd.org/setsockopt.2
 /// [OpenBSD]: https://man.openbsd.org/setsockopt.2
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=setsockopt&section=2
 /// [illumos]: https://illumos.org/man/3SOCKET/setsockopt
 /// [glibc `setsockopt`]: https://www.gnu.org/software/libc/manual/html_node/Socket-Option-Functions.html
 /// [glibc `SOL_SOCKET` options]: https://www.gnu.org/software/libc/manual/html_node/Socket_002dLevel-Options.html
 #[inline]
 #[doc(alias = "SO_REUSEADDR")]
 pub fn set_socket_reuseaddr<Fd: AsFd>(fd: Fd, value: bool) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_socket_reuseaddr(fd.as_fd(), value)
 }

 /// `getsockopt(fd, SOL_SOCKET, SO_REUSEADDR)`
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `sys/socket.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `socket`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `SOL_SOCKET` options]
 ///  - [Apple]
 ///  - [FreeBSD]
 ///  - [NetBSD]
 ///  - [OpenBSD]
 ///  - [DragonFly BSD]
 ///  - [illumos]
 ///  - [glibc `getsockopt`]
 ///  - [glibc `SOL_SOCKET` Options]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `sys/socket.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_socket.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `socket`]: https://man7.org/linux/man-pages/man7/socket.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `SOL_SOCKET` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/sol-socket-socket-options
 /// [Apple]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getsockopt.2.html
 /// [FreeBSD]: https://man.freebsd.org/cgi/man.cgi?query=getsockopt&sektion=2
 /// [NetBSD]: https://man.netbsd.org/getsockopt.2
 /// [OpenBSD]: https://man.openbsd.org/getsockopt.2
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=getsockopt&section=2
 /// [illumos]: https://illumos.org/man/3SOCKET/getsockopt
 /// [glibc `getsockopt`]: https://www.gnu.org/software/libc/manual/html_node/Socket-Option-Functions.html
 /// [glibc `SOL_SOCKET` options]: https://www.gnu.org/software/libc/manual/html_node/Socket_002dLevel-Options.html
 #[inline]
 #[doc(alias = "SO_REUSEADDR")]
 pub fn get_socket_reuseaddr<Fd: AsFd>(fd: Fd) -> io::Result<bool> {
     backend::net::syscalls::sockopt::get_socket_reuseaddr(fd.as_fd())
 }

 /// `setsockopt(fd, SOL_SOCKET, SO_BROADCAST, broadcast)`
 ///
 /// # References
 ///  - [POSIX `setsockopt`]
 ///  - [POSIX `sys/socket.h`]
 ///  - [Linux `setsockopt`]
 ///  - [Linux `socket`]
 ///  - [Winsock2 `setsockopt`]
 ///  - [Winsock2 `SOL_SOCKET` options]
 ///  - [Apple]
 ///  - [FreeBSD]
 ///  - [NetBSD]
 ///  - [OpenBSD]
 ///  - [DragonFly BSD]
 ///  - [illumos]
 ///  - [glibc `setsockopt`]
 ///  - [glibc `SOL_SOCKET` Options]
 ///
 /// [POSIX `setsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/setsockopt.html
 /// [POSIX `sys/socket.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_socket.h.html
 /// [Linux `setsockopt`]: https://man7.org/linux/man-pages/man2/setsockopt.2.html
 /// [Linux `socket`]: https://man7.org/linux/man-pages/man7/socket.7.html
 /// [Winsock2 `setsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-setsockopt
 /// [Winsock2 `SOL_SOCKET` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/sol-socket-socket-options
 /// [Apple]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/setsockopt.2.html
 /// [FreeBSD]: https://man.freebsd.org/cgi/man.cgi?query=setsockopt&sektion=2
 /// [NetBSD]: https://man.netbsd.org/setsockopt.2
 /// [OpenBSD]: https://man.openbsd.org/setsockopt.2
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=setsockopt&section=2
 /// [illumos]: https://illumos.org/man/3SOCKET/setsockopt
 /// [glibc `setsockopt`]: https://www.gnu.org/software/libc/manual/html_node/Socket-Option-Functions.html
 /// [glibc `SOL_SOCKET` options]: https://www.gnu.org/software/libc/manual/html_node/Socket_002dLevel-Options.html
 #[inline]
 #[doc(alias = "SO_BROADCAST")]
 pub fn set_socket_broadcast<Fd: AsFd>(fd: Fd, broadcast: bool) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_socket_broadcast(fd.as_fd(), broadcast)
 }

 /// `getsockopt(fd, SOL_SOCKET, SO_BROADCAST)`
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `sys/socket.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `socket`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `SOL_SOCKET` options]
 ///  - [Apple]
 ///  - [FreeBSD]
 ///  - [NetBSD]
 ///  - [OpenBSD]
 ///  - [DragonFly BSD]
 ///  - [illumos]
 ///  - [glibc `getsockopt`]
 ///  - [glibc `SOL_SOCKET` Options]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `sys/socket.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_socket.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `socket`]: https://man7.org/linux/man-pages/man7/socket.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `SOL_SOCKET` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/sol-socket-socket-options
 /// [Apple]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getsockopt.2.html
 /// [FreeBSD]: https://man.freebsd.org/cgi/man.cgi?query=getsockopt&sektion=2
 /// [NetBSD]: https://man.netbsd.org/getsockopt.2
 /// [OpenBSD]: https://man.openbsd.org/getsockopt.2
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=getsockopt&section=2
 /// [illumos]: https://illumos.org/man/3SOCKET/getsockopt
 /// [glibc `getsockopt`]: https://www.gnu.org/software/libc/manual/html_node/Socket-Option-Functions.html
 /// [glibc `SOL_SOCKET` options]: https://www.gnu.org/software/libc/manual/html_node/Socket_002dLevel-Options.html
 #[inline]
 #[doc(alias = "SO_BROADCAST")]
 pub fn get_socket_broadcast<Fd: AsFd>(fd: Fd) -> io::Result<bool> {
     backend::net::syscalls::sockopt::get_socket_broadcast(fd.as_fd())
 }

 /// `setsockopt(fd, SOL_SOCKET, SO_LINGER, linger)`
 ///
 /// # References
 ///  - [POSIX `setsockopt`]
 ///  - [POSIX `sys/socket.h`]
 ///  - [Linux `setsockopt`]
 ///  - [Linux `socket`]
 ///  - [Winsock2 `setsockopt`]
 ///  - [Winsock2 `SOL_SOCKET` options]
 ///  - [Apple]
 ///  - [FreeBSD]
 ///  - [NetBSD]
 ///  - [OpenBSD]
 ///  - [DragonFly BSD]
 ///  - [illumos]
 ///  - [glibc `setsockopt`]
 ///  - [glibc `SOL_SOCKET` Options]
 ///
 /// [POSIX `setsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/setsockopt.html
 /// [POSIX `sys/socket.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_socket.h.html
 /// [Linux `setsockopt`]: https://man7.org/linux/man-pages/man2/setsockopt.2.html
 /// [Linux `socket`]: https://man7.org/linux/man-pages/man7/socket.7.html
 /// [Winsock2 `setsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-setsockopt
 /// [Winsock2 `SOL_SOCKET` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/sol-socket-socket-options
 /// [Apple]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/setsockopt.2.html
 /// [FreeBSD]: https://man.freebsd.org/cgi/man.cgi?query=setsockopt&sektion=2
 /// [NetBSD]: https://man.netbsd.org/setsockopt.2
 /// [OpenBSD]: https://man.openbsd.org/setsockopt.2
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=setsockopt&section=2
 /// [illumos]: https://illumos.org/man/3SOCKET/setsockopt
 /// [glibc `setsockopt`]: https://www.gnu.org/software/libc/manual/html_node/Socket-Option-Functions.html
 /// [glibc `SOL_SOCKET` options]: https://www.gnu.org/software/libc/manual/html_node/Socket_002dLevel-Options.html
 #[inline]
 #[doc(alias = "SO_LINGER")]
 pub fn set_socket_linger<Fd: AsFd>(fd: Fd, linger: Option<Duration>) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_socket_linger(fd.as_fd(), linger)
 }

 /// `getsockopt(fd, SOL_SOCKET, SO_LINGER)`
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `sys/socket.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `socket`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `SOL_SOCKET` options]
 ///  - [Apple]
 ///  - [FreeBSD]
 ///  - [NetBSD]
 ///  - [OpenBSD]
 ///  - [DragonFly BSD]
 ///  - [illumos]
 ///  - [glibc `getsockopt`]
 ///  - [glibc `SOL_SOCKET` Options]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `sys/socket.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_socket.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `socket`]: https://man7.org/linux/man-pages/man7/socket.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `SOL_SOCKET` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/sol-socket-socket-options
 /// [Apple]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getsockopt.2.html
 /// [FreeBSD]: https://man.freebsd.org/cgi/man.cgi?query=getsockopt&sektion=2
 /// [NetBSD]: https://man.netbsd.org/getsockopt.2
 /// [OpenBSD]: https://man.openbsd.org/getsockopt.2
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=getsockopt&section=2
 /// [illumos]: https://illumos.org/man/3SOCKET/getsockopt
 /// [glibc `getsockopt`]: https://www.gnu.org/software/libc/manual/html_node/Socket-Option-Functions.html
 /// [glibc `SOL_SOCKET` options]: https://www.gnu.org/software/libc/manual/html_node/Socket_002dLevel-Options.html
 #[inline]
 #[doc(alias = "SO_LINGER")]
 pub fn get_socket_linger<Fd: AsFd>(fd: Fd) -> io::Result<Option<Duration>> {
     backend::net::syscalls::sockopt::get_socket_linger(fd.as_fd())
 }

 /// `setsockopt(fd, SOL_SOCKET, SO_PASSCRED, passcred)`
 ///
 /// # References
 ///  - [Linux `setsockopt`]
 ///  - [Linux `socket`]
 ///
 /// [Linux `setsockopt`]: https://man7.org/linux/man-pages/man2/setsockopt.2.html
 /// [Linux `socket`]: https://man7.org/linux/man-pages/man7/socket.7.html
 #[cfg(linux_kernel)]
 #[inline]
 #[doc(alias = "SO_PASSCRED")]
 pub fn set_socket_passcred<Fd: AsFd>(fd: Fd, passcred: bool) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_socket_passcred(fd.as_fd(), passcred)
 }

 /// `getsockopt(fd, SOL_SOCKET, SO_PASSCRED)`
 ///
 /// # References
 ///  - [Linux `getsockopt`]
 ///  - [Linux `socket`]
 ///
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `socket`]: https://man7.org/linux/man-pages/man7/socket.7.html
 #[cfg(linux_kernel)]
 #[inline]
 #[doc(alias = "SO_PASSCRED")]
 pub fn get_socket_passcred<Fd: AsFd>(fd: Fd) -> io::Result<bool> {
     backend::net::syscalls::sockopt::get_socket_passcred(fd.as_fd())
 }

 /// `setsockopt(fd, SOL_SOCKET, id, timeout)`—Set the sending or receiving
 /// timeout.
 ///
 /// # References
 ///  - [POSIX `setsockopt`]
 ///  - [POSIX `sys/socket.h`]
 ///  - [Linux `setsockopt`]
 ///  - [Linux `socket`]
 ///  - [Winsock2 `setsockopt`]
 ///  - [Winsock2 `SOL_SOCKET` options]
 ///  - [Apple]
 ///  - [FreeBSD]
 ///  - [NetBSD]
 ///  - [OpenBSD]
 ///  - [DragonFly BSD]
 ///  - [illumos]
 ///  - [glibc `setsockopt`]
 ///  - [glibc `SOL_SOCKET` Options]
 ///
 /// [POSIX `setsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/setsockopt.html
 /// [POSIX `sys/socket.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_socket.h.html
 /// [Linux `setsockopt`]: https://man7.org/linux/man-pages/man2/setsockopt.2.html
 /// [Linux `socket`]: https://man7.org/linux/man-pages/man7/socket.7.html
 /// [Winsock2 `setsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-setsockopt
 /// [Winsock2 `SOL_SOCKET` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/sol-socket-socket-options
 /// [Apple]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/setsockopt.2.html
 /// [FreeBSD]: https://man.freebsd.org/cgi/man.cgi?query=setsockopt&sektion=2
 /// [NetBSD]: https://man.netbsd.org/setsockopt.2
 /// [OpenBSD]: https://man.openbsd.org/setsockopt.2
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=setsockopt&section=2
 /// [illumos]: https://illumos.org/man/3SOCKET/setsockopt
 /// [glibc `setsockopt`]: https://www.gnu.org/software/libc/manual/html_node/Socket-Option-Functions.html
 /// [glibc `SOL_SOCKET` options]: https://www.gnu.org/software/libc/manual/html_node/Socket_002dLevel-Options.html
 #[inline]
 #[doc(alias = "SO_RCVTIMEO")]
 #[doc(alias = "SO_SNDTIMEO")]
 pub fn set_socket_timeout<Fd: AsFd>(
     fd: Fd,
     id: Timeout,
     timeout: Option<Duration>,
 ) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_socket_timeout(fd.as_fd(), id, timeout)
 }

 /// `getsockopt(fd, SOL_SOCKET, id)`—Get the sending or receiving timeout.
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `sys/socket.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `socket`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `SOL_SOCKET` options]
 ///  - [Apple]
 ///  - [FreeBSD]
 ///  - [NetBSD]
 ///  - [OpenBSD]
 ///  - [DragonFly BSD]
 ///  - [illumos]
 ///  - [glibc `getsockopt`]
 ///  - [glibc `SOL_SOCKET` Options]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `sys/socket.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_socket.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `socket`]: https://man7.org/linux/man-pages/man7/socket.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `SOL_SOCKET` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/sol-socket-socket-options
 /// [Apple]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getsockopt.2.html
 /// [FreeBSD]: https://man.freebsd.org/cgi/man.cgi?query=getsockopt&sektion=2
 /// [NetBSD]: https://man.netbsd.org/getsockopt.2
 /// [OpenBSD]: https://man.openbsd.org/getsockopt.2
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=getsockopt&section=2
 /// [illumos]: https://illumos.org/man/3SOCKET/getsockopt
 /// [glibc `getsockopt`]: https://www.gnu.org/software/libc/manual/html_node/Socket-Option-Functions.html
 /// [glibc `SOL_SOCKET` options]: https://www.gnu.org/software/libc/manual/html_node/Socket_002dLevel-Options.html
 #[inline]
 #[doc(alias = "SO_RCVTIMEO")]
 #[doc(alias = "SO_SNDTIMEO")]
 pub fn get_socket_timeout<Fd: AsFd>(fd: Fd, id: Timeout) -> io::Result<Option<Duration>> {
     backend::net::syscalls::sockopt::get_socket_timeout(fd.as_fd(), id)
 }

 /// `getsockopt(fd, SOL_SOCKET, SO_ERROR)`
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `sys/socket.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `socket`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `SOL_SOCKET` options]
 ///  - [Apple]
 ///  - [FreeBSD]
 ///  - [NetBSD]
 ///  - [OpenBSD]
 ///  - [DragonFly BSD]
 ///  - [illumos]
 ///  - [glibc `getsockopt`]
 ///  - [glibc `SOL_SOCKET` Options]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `sys/socket.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_socket.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `socket`]: https://man7.org/linux/man-pages/man7/socket.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `SOL_SOCKET` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/sol-socket-socket-options
 /// [Apple]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getsockopt.2.html
 /// [FreeBSD]: https://man.freebsd.org/cgi/man.cgi?query=getsockopt&sektion=2
 /// [NetBSD]: https://man.netbsd.org/getsockopt.2
 /// [OpenBSD]: https://man.openbsd.org/getsockopt.2
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=getsockopt&section=2
 /// [illumos]: https://illumos.org/man/3SOCKET/getsockopt
 /// [glibc `getsockopt`]: https://www.gnu.org/software/libc/manual/html_node/Socket-Option-Functions.html
 /// [glibc `SOL_SOCKET` options]: https://www.gnu.org/software/libc/manual/html_node/Socket_002dLevel-Options.html
 #[inline]
 #[doc(alias = "SO_ERROR")]
 pub fn get_socket_error<Fd: AsFd>(fd: Fd) -> io::Result<Result<(), io::Errno>> {
     backend::net::syscalls::sockopt::get_socket_error(fd.as_fd())
 }

 /// `getsockopt(fd, SOL_SOCKET, SO_NOSIGPIPE)`
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `sys/socket.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `socket`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `SOL_SOCKET` options]
 ///  - [Apple]
 ///  - [FreeBSD]
 ///  - [NetBSD]
 ///  - [OpenBSD]
 ///  - [DragonFly BSD]
 ///  - [illumos]
 ///  - [glibc `getsockopt`]
 ///  - [glibc `SOL_SOCKET` Options]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `sys/socket.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_socket.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `socket`]: https://man7.org/linux/man-pages/man7/socket.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `SOL_SOCKET` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/sol-socket-socket-options
 /// [Apple]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getsockopt.2.html
 /// [FreeBSD]: https://man.freebsd.org/cgi/man.cgi?query=getsockopt&sektion=2
 /// [NetBSD]: https://man.netbsd.org/getsockopt.2
 /// [OpenBSD]: https://man.openbsd.org/getsockopt.2
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=getsockopt&section=2
 /// [illumos]: https://illumos.org/man/3SOCKET/getsockopt
 /// [glibc `getsockopt`]: https://www.gnu.org/software/libc/manual/html_node/Socket-Option-Functions.html
 /// [glibc `SOL_SOCKET` options]: https://www.gnu.org/software/libc/manual/html_node/Socket_002dLevel-Options.html
 #[cfg(any(apple, target_os = "freebsd"))]
 #[doc(alias = "SO_NOSIGPIPE")]
 #[inline]
 pub fn get_socket_nosigpipe<Fd: AsFd>(fd: Fd) -> io::Result<bool> {
     backend::net::syscalls::sockopt::get_socket_nosigpipe(fd.as_fd())
 }

 /// `setsockopt(fd, SOL_SOCKET, SO_NOSIGPIPE, val)`
 ///
 /// # References
 ///  - [POSIX `setsockopt`]
 ///  - [POSIX `sys/socket.h`]
 ///  - [Linux `setsockopt`]
 ///  - [Linux `socket`]
 ///  - [Winsock2 `setsockopt`]
 ///  - [Winsock2 `SOL_SOCKET` options]
 ///  - [Apple]
 ///  - [FreeBSD]
 ///  - [NetBSD]
 ///  - [OpenBSD]
 ///  - [DragonFly BSD]
 ///  - [illumos]
 ///  - [glibc `setsockopt`]
 ///  - [glibc `SOL_SOCKET` Options]
 ///
 /// [POSIX `setsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/setsockopt.html
 /// [POSIX `sys/socket.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_socket.h.html
 /// [Linux `setsockopt`]: https://man7.org/linux/man-pages/man2/setsockopt.2.html
 /// [Linux `socket`]: https://man7.org/linux/man-pages/man7/socket.7.html
 /// [Winsock2 `setsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-setsockopt
 /// [Winsock2 `SOL_SOCKET` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/sol-socket-socket-options
 /// [Apple]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/setsockopt.2.html
 /// [FreeBSD]: https://man.freebsd.org/cgi/man.cgi?query=setsockopt&sektion=2
 /// [NetBSD]: https://man.netbsd.org/setsockopt.2
 /// [OpenBSD]: https://man.openbsd.org/setsockopt.2
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=setsockopt&section=2
 /// [illumos]: https://illumos.org/man/3SOCKET/setsockopt
 /// [glibc `setsockopt`]: https://www.gnu.org/software/libc/manual/html_node/Socket-Option-Functions.html
 /// [glibc `SOL_SOCKET` options]: https://www.gnu.org/software/libc/manual/html_node/Socket_002dLevel-Options.html
 #[cfg(any(apple, target_os = "freebsd"))]
 #[doc(alias = "SO_NOSIGPIPE")]
 #[inline]
 pub fn set_socket_nosigpipe<Fd: AsFd>(fd: Fd, val: bool) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_socket_nosigpipe(fd.as_fd(), val)
 }

 /// `setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, keepalive)`
 ///
 /// # References
 ///  - [POSIX `setsockopt`]
 ///  - [POSIX `sys/socket.h`]
 ///  - [Linux `setsockopt`]
 ///  - [Linux `socket`]
 ///  - [Winsock2 `setsockopt`]
 ///  - [Winsock2 `SOL_SOCKET` options]
 ///  - [Apple]
 ///  - [FreeBSD]
 ///  - [NetBSD]
 ///  - [OpenBSD]
 ///  - [DragonFly BSD]
 ///  - [illumos]
 ///  - [glibc `setsockopt`]
 ///  - [glibc `SOL_SOCKET` Options]
 ///
 /// [POSIX `setsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/setsockopt.html
 /// [POSIX `sys/socket.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_socket.h.html
 /// [Linux `setsockopt`]: https://man7.org/linux/man-pages/man2/setsockopt.2.html
 /// [Linux `socket`]: https://man7.org/linux/man-pages/man7/socket.7.html
 /// [Winsock2 `setsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-setsockopt
 /// [Winsock2 `SOL_SOCKET` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/sol-socket-socket-options
 /// [Apple]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/setsockopt.2.html
 /// [FreeBSD]: https://man.freebsd.org/cgi/man.cgi?query=setsockopt&sektion=2
 /// [NetBSD]: https://man.netbsd.org/setsockopt.2
 /// [OpenBSD]: https://man.openbsd.org/setsockopt.2
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=setsockopt&section=2
 /// [illumos]: https://illumos.org/man/3SOCKET/setsockopt
 /// [glibc `setsockopt`]: https://www.gnu.org/software/libc/manual/html_node/Socket-Option-Functions.html
 /// [glibc `SOL_SOCKET` options]: https://www.gnu.org/software/libc/manual/html_node/Socket_002dLevel-Options.html
 #[inline]
 #[doc(alias = "SO_KEEPALIVE")]
 pub fn set_socket_keepalive<Fd: AsFd>(fd: Fd, keepalive: bool) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_socket_keepalive(fd.as_fd(), keepalive)
 }

 /// `getsockopt(fd, SOL_SOCKET, SO_KEEPALIVE)`
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `sys/socket.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `socket`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `SOL_SOCKET` options]
 ///  - [Apple]
 ///  - [FreeBSD]
 ///  - [NetBSD]
 ///  - [OpenBSD]
 ///  - [DragonFly BSD]
 ///  - [illumos]
 ///  - [glibc `getsockopt`]
 ///  - [glibc `SOL_SOCKET` Options]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `sys/socket.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_socket.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `socket`]: https://man7.org/linux/man-pages/man7/socket.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `SOL_SOCKET` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/sol-socket-socket-options
 /// [Apple]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getsockopt.2.html
 /// [FreeBSD]: https://man.freebsd.org/cgi/man.cgi?query=getsockopt&sektion=2
 /// [NetBSD]: https://man.netbsd.org/getsockopt.2
 /// [OpenBSD]: https://man.openbsd.org/getsockopt.2
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=getsockopt&section=2
 /// [illumos]: https://illumos.org/man/3SOCKET/getsockopt
 /// [glibc `getsockopt`]: https://www.gnu.org/software/libc/manual/html_node/Socket-Option-Functions.html
 /// [glibc `SOL_SOCKET` options]: https://www.gnu.org/software/libc/manual/html_node/Socket_002dLevel-Options.html
 #[inline]
 #[doc(alias = "SO_KEEPALIVE")]
 pub fn get_socket_keepalive<Fd: AsFd>(fd: Fd) -> io::Result<bool> {
     backend::net::syscalls::sockopt::get_socket_keepalive(fd.as_fd())
 }

 /// `setsockopt(fd, SOL_SOCKET, SO_RCVBUF, size)`
 ///
 /// # References
 ///  - [POSIX `setsockopt`]
 ///  - [POSIX `sys/socket.h`]
 ///  - [Linux `setsockopt`]
 ///  - [Linux `socket`]
 ///  - [Winsock2 `setsockopt`]
 ///  - [Winsock2 `SOL_SOCKET` options]
 ///  - [Apple]
 ///  - [FreeBSD]
 ///  - [NetBSD]
 ///  - [OpenBSD]
 ///  - [DragonFly BSD]
 ///  - [illumos]
 ///  - [glibc `setsockopt`]
 ///  - [glibc `SOL_SOCKET` Options]
 ///
 /// [POSIX `setsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/setsockopt.html
 /// [POSIX `sys/socket.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_socket.h.html
 /// [Linux `setsockopt`]: https://man7.org/linux/man-pages/man2/setsockopt.2.html
 /// [Linux `socket`]: https://man7.org/linux/man-pages/man7/socket.7.html
 /// [Winsock2 `setsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-setsockopt
 /// [Winsock2 `SOL_SOCKET` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/sol-socket-socket-options
 /// [Apple]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/setsockopt.2.html
 /// [FreeBSD]: https://man.freebsd.org/cgi/man.cgi?query=setsockopt&sektion=2
 /// [NetBSD]: https://man.netbsd.org/setsockopt.2
 /// [OpenBSD]: https://man.openbsd.org/setsockopt.2
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=setsockopt&section=2
 /// [illumos]: https://illumos.org/man/3SOCKET/setsockopt
 /// [glibc `setsockopt`]: https://www.gnu.org/software/libc/manual/html_node/Socket-Option-Functions.html
 /// [glibc `SOL_SOCKET` options]: https://www.gnu.org/software/libc/manual/html_node/Socket_002dLevel-Options.html
 #[inline]
 #[doc(alias = "SO_RCVBUF")]
 pub fn set_socket_recv_buffer_size<Fd: AsFd>(fd: Fd, size: usize) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_socket_recv_buffer_size(fd.as_fd(), size)
 }

 /// `getsockopt(fd, SOL_SOCKET, SO_RCVBUF)`
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `sys/socket.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `socket`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `SOL_SOCKET` options]
 ///  - [Apple]
 ///  - [FreeBSD]
 ///  - [NetBSD]
 ///  - [OpenBSD]
 ///  - [DragonFly BSD]
 ///  - [illumos]
 ///  - [glibc `getsockopt`]
 ///  - [glibc `SOL_SOCKET` Options]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `sys/socket.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_socket.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `socket`]: https://man7.org/linux/man-pages/man7/socket.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `SOL_SOCKET` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/sol-socket-socket-options
 /// [Apple]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getsockopt.2.html
 /// [FreeBSD]: https://man.freebsd.org/cgi/man.cgi?query=getsockopt&sektion=2
 /// [NetBSD]: https://man.netbsd.org/getsockopt.2
 /// [OpenBSD]: https://man.openbsd.org/getsockopt.2
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=getsockopt&section=2
 /// [illumos]: https://illumos.org/man/3SOCKET/getsockopt
 /// [glibc `getsockopt`]: https://www.gnu.org/software/libc/manual/html_node/Socket-Option-Functions.html
 /// [glibc `SOL_SOCKET` options]: https://www.gnu.org/software/libc/manual/html_node/Socket_002dLevel-Options.html
 #[inline]
 #[doc(alias = "SO_RCVBUF")]
 pub fn get_socket_recv_buffer_size<Fd: AsFd>(fd: Fd) -> io::Result<usize> {
     backend::net::syscalls::sockopt::get_socket_recv_buffer_size(fd.as_fd())
 }

 /// `setsockopt(fd, SOL_SOCKET, SO_SNDBUF, size)`
 ///
 /// # References
 ///  - [POSIX `setsockopt`]
 ///  - [POSIX `sys/socket.h`]
 ///  - [Linux `setsockopt`]
 ///  - [Linux `socket`]
 ///  - [Winsock2 `setsockopt`]
 ///  - [Winsock2 `SOL_SOCKET` options]
 ///  - [Apple]
 ///  - [FreeBSD]
 ///  - [NetBSD]
 ///  - [OpenBSD]
 ///  - [DragonFly BSD]
 ///  - [illumos]
 ///  - [glibc `setsockopt`]
 ///  - [glibc `SOL_SOCKET` Options]
 ///
 /// [POSIX `setsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/setsockopt.html
 /// [POSIX `sys/socket.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_socket.h.html
 /// [Linux `setsockopt`]: https://man7.org/linux/man-pages/man2/setsockopt.2.html
 /// [Linux `socket`]: https://man7.org/linux/man-pages/man7/socket.7.html
 /// [Winsock2 `setsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-setsockopt
 /// [Winsock2 `SOL_SOCKET` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/sol-socket-socket-options
 /// [Apple]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/setsockopt.2.html
 /// [FreeBSD]: https://man.freebsd.org/cgi/man.cgi?query=setsockopt&sektion=2
 /// [NetBSD]: https://man.netbsd.org/setsockopt.2
 /// [OpenBSD]: https://man.openbsd.org/setsockopt.2
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=setsockopt&section=2
 /// [illumos]: https://illumos.org/man/3SOCKET/setsockopt
 /// [glibc `setsockopt`]: https://www.gnu.org/software/libc/manual/html_node/Socket-Option-Functions.html
 /// [glibc `SOL_SOCKET` options]: https://www.gnu.org/software/libc/manual/html_node/Socket_002dLevel-Options.html
 #[inline]
 #[doc(alias = "SO_SNDBUF")]
 pub fn set_socket_send_buffer_size<Fd: AsFd>(fd: Fd, size: usize) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_socket_send_buffer_size(fd.as_fd(), size)
 }

 /// `getsockopt(fd, SOL_SOCKET, SO_SNDBUF)`
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `sys/socket.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `socket`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `SOL_SOCKET` options]
 ///  - [Apple]
 ///  - [FreeBSD]
 ///  - [NetBSD]
 ///  - [OpenBSD]
 ///  - [DragonFly BSD]
 ///  - [illumos]
 ///  - [glibc `getsockopt`]
 ///  - [glibc `SOL_SOCKET` Options]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `sys/socket.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_socket.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `socket`]: https://man7.org/linux/man-pages/man7/socket.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `SOL_SOCKET` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/sol-socket-socket-options
 /// [Apple]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getsockopt.2.html
 /// [FreeBSD]: https://man.freebsd.org/cgi/man.cgi?query=getsockopt&sektion=2
 /// [NetBSD]: https://man.netbsd.org/getsockopt.2
 /// [OpenBSD]: https://man.openbsd.org/getsockopt.2
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=getsockopt&section=2
 /// [illumos]: https://illumos.org/man/3SOCKET/getsockopt
 /// [glibc `getsockopt`]: https://www.gnu.org/software/libc/manual/html_node/Socket-Option-Functions.html
 /// [glibc `SOL_SOCKET` options]: https://www.gnu.org/software/libc/manual/html_node/Socket_002dLevel-Options.html
 #[inline]
 #[doc(alias = "SO_SNDBUF")]
 pub fn get_socket_send_buffer_size<Fd: AsFd>(fd: Fd) -> io::Result<usize> {
     backend::net::syscalls::sockopt::get_socket_send_buffer_size(fd.as_fd())
 }

 /// `getsockopt(fd, SOL_SOCKET, SO_DOMAIN)`
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `sys/socket.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `socket`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `SOL_SOCKET` options]
 ///  - [Apple]
 ///  - [FreeBSD]
 ///  - [NetBSD]
 ///  - [OpenBSD]
 ///  - [DragonFly BSD]
 ///  - [illumos]
 ///  - [glibc `getsockopt`]
 ///  - [glibc `SOL_SOCKET` Options]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `sys/socket.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_socket.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `socket`]: https://man7.org/linux/man-pages/man7/socket.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `SOL_SOCKET` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/sol-socket-socket-options
 /// [Apple]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getsockopt.2.html
 /// [FreeBSD]: https://man.freebsd.org/cgi/man.cgi?query=getsockopt&sektion=2
 /// [NetBSD]: https://man.netbsd.org/getsockopt.2
 /// [OpenBSD]: https://man.openbsd.org/getsockopt.2
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=getsockopt&section=2
 /// [illumos]: https://illumos.org/man/3SOCKET/getsockopt
 /// [glibc `getsockopt`]: https://www.gnu.org/software/libc/manual/html_node/Socket-Option-Functions.html
 /// [glibc `SOL_SOCKET` options]: https://www.gnu.org/software/libc/manual/html_node/Socket_002dLevel-Options.html
 #[cfg(not(any(
     apple,
     windows,
     target_os = "aix",
     target_os = "dragonfly",
     target_os = "emscripten",
     target_os = "espidf",
     target_os = "haiku",
     target_os = "netbsd",
     target_os = "nto",
 )))]
 #[inline]
 #[doc(alias = "SO_DOMAIN")]
 pub fn get_socket_domain<Fd: AsFd>(fd: Fd) -> io::Result<AddressFamily> {
     backend::net::syscalls::sockopt::get_socket_domain(fd.as_fd())
 }

 /// `getsockopt(fd, SOL_SOCKET, SO_ACCEPTCONN)`
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `sys/socket.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `socket`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `SOL_SOCKET` options]
 ///  - [FreeBSD]
 ///  - [NetBSD]
 ///  - [OpenBSD]
 ///  - [DragonFly BSD]
 ///  - [illumos]
 ///  - [glibc `getsockopt`]
 ///  - [glibc `SOL_SOCKET` Options]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `sys/socket.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_socket.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `socket`]: https://man7.org/linux/man-pages/man7/socket.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `SOL_SOCKET` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/sol-socket-socket-options
 /// [FreeBSD]: https://man.freebsd.org/cgi/man.cgi?query=getsockopt&sektion=2
 /// [NetBSD]: https://man.netbsd.org/getsockopt.2
 /// [OpenBSD]: https://man.openbsd.org/getsockopt.2
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=getsockopt&section=2
 /// [illumos]: https://illumos.org/man/3SOCKET/getsockopt
 /// [glibc `getsockopt`]: https://www.gnu.org/software/libc/manual/html_node/Socket-Option-Functions.html
 /// [glibc `SOL_SOCKET` options]: https://www.gnu.org/software/libc/manual/html_node/Socket_002dLevel-Options.html
 #[cfg(not(apple))] // Apple platforms declare the constant, but do not actually implement it.
 #[inline]
 #[doc(alias = "SO_ACCEPTCONN")]
 pub fn get_socket_acceptconn<Fd: AsFd>(fd: Fd) -> io::Result<bool> {
     backend::net::syscalls::sockopt::get_socket_acceptconn(fd.as_fd())
 }

 /// `setsockopt(fd, IPPROTO_IP, IP_TTL, ttl)`
 ///
 /// # References
 ///  - [POSIX `setsockopt`]
 ///  - [POSIX `netinet/in.h`]
 ///  - [Linux `setsockopt`]
 ///  - [Linux `ip`]
 ///  - [Winsock2 `setsockopt`]
 ///  - [Winsock2 `IPPROTO_IP` options]
 ///  - [Apple `setsockopt`]
 ///  - [Apple `ip`]
 ///  - [FreeBSD `setsockopt`]
 ///  - [FreeBSD `ip`]
 ///  - [NetBSD `setsockopt`]
 ///  - [NetBSD `ip`]
 ///  - [OpenBSD `setsockopt`]
 ///  - [OpenBSD `ip`]
 ///  - [DragonFly BSD `setsockopt`]
 ///  - [DragonFly BSD `ip`]
 ///  - [illumos `setsockopt`]
 ///  - [illumos `ip`]
 ///
 /// [POSIX `setsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/setsockopt.html
 /// [Linux `setsockopt`]: https://man7.org/linux/man-pages/man2/setsockopt.2.html
 /// [Linux `ip`]: https://man7.org/linux/man-pages/man7/ip.7.html
 /// [Winsock2 `setsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-setsockopt
 /// [Winsock2 `IPPROTO_IP` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ip-socket-options
 /// [Apple `setsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/setsockopt.2.html
 /// [Apple `ip`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/ip.4.auto.html
 /// [FreeBSD `setsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=setsockopt&sektion=2
 /// [FreeBSD `ip`]: https://man.freebsd.org/cgi/man.cgi?query=ip&sektion=4
 /// [NetBSD `setsockopt`]: https://man.netbsd.org/setsockopt.2
 /// [NetBSD `ip`]: https://man.netbsd.org/ip.4
 /// [OpenBSD `setsockopt`]: https://man.openbsd.org/setsockopt.2
 /// [OpenBSD `ip`]: https://man.openbsd.org/ip.4
 /// [DragonFly BSD `setsockopt`]: https://man.dragonflybsd.org/?command=setsockopt&section=2
 /// [DragonFly BSD `ip`]: https://man.dragonflybsd.org/?command=ip&section=4
 /// [illumos `setsockopt`]: https://illumos.org/man/3SOCKET/setsockopt
 /// [illumos `ip`]: https://illumos.org/man/4P/ip
 #[inline]
 #[doc(alias = "IP_TTL")]
 pub fn set_ip_ttl<Fd: AsFd>(fd: Fd, ttl: u32) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_ip_ttl(fd.as_fd(), ttl)
 }

 /// `getsockopt(fd, IPPROTO_IP, IP_TTL)`
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `netinet/in.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `ip`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `IPPROTO_IP` options]
 ///  - [Apple `getsockopt`]
 ///  - [Apple `ip`]
 ///  - [FreeBSD `getsockopt`]
 ///  - [FreeBSD `ip`]
 ///  - [NetBSD `getsockopt`]
 ///  - [NetBSD `ip`]
 ///  - [OpenBSD `getsockopt`]
 ///  - [OpenBSD `ip`]
 ///  - [DragonFly BSD `getsockopt`]
 ///  - [DragonFly BSD `ip`]
 ///  - [illumos `getsockopt`]
 ///  - [illumos `ip`]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `netinet/in.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_in.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `ip`]: https://man7.org/linux/man-pages/man7/ip.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `IPPROTO_IP` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ip-socket-options
 /// [Apple `setsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/setsockopt.2.html
 /// [Apple `ip`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/ip.4.auto.html
 /// [FreeBSD `setsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=setsockopt&sektion=2
 /// [FreeBSD `ip`]: https://man.freebsd.org/cgi/man.cgi?query=ip&sektion=4
 /// [NetBSD `setsockopt`]: https://man.netbsd.org/setsockopt.2
 /// [NetBSD `ip`]: https://man.netbsd.org/ip.4
 /// [OpenBSD `setsockopt`]: https://man.openbsd.org/setsockopt.2
 /// [OpenBSD `ip`]: https://man.openbsd.org/ip.4
 /// [DragonFly BSD `setsockopt`]: https://man.dragonflybsd.org/?command=setsockopt&section=2
 /// [DragonFly BSD `ip`]: https://man.dragonflybsd.org/?command=ip&section=4
 /// [illumos `setsockopt`]: https://illumos.org/man/3SOCKET/setsockopt
 /// [illumos `ip`]: https://illumos.org/man/4P/ip
 #[inline]
 #[doc(alias = "IP_TTL")]
 pub fn get_ip_ttl<Fd: AsFd>(fd: Fd) -> io::Result<u32> {
     backend::net::syscalls::sockopt::get_ip_ttl(fd.as_fd())
 }

 /// `setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, only_v6)`
 ///
 /// # References
 ///  - [POSIX `setsockopt`]
 ///  - [POSIX `netinet/in.h`]
 ///  - [Linux `setsockopt`]
 ///  - [Linux `ipv6`]
 ///  - [Winsock2 `setsockopt`]
 ///  - [Winsock2 `IPPROTO_IPV6` options]
 ///  - [Apple `setsockopt`]
 ///  - [Apple `ip6`]
 ///  - [FreeBSD `setsockopt`]
 ///  - [FreeBSD `ip6`]
 ///  - [NetBSD `setsockopt`]
 ///  - [NetBSD `ip6`]
 ///  - [OpenBSD `setsockopt`]
 ///  - [OpenBSD `ip6`]
 ///  - [DragonFly BSD `setsockopt`]
 ///  - [DragonFly BSD `ip6`]
 ///  - [illumos `setsockopt`]
 ///  - [illumos `ip6`]
 ///
 /// [POSIX `setsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/setsockopt.html
 /// [POSIX `netinet/in.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_in.h.html
 /// [Linux `setsockopt`]: https://man7.org/linux/man-pages/man2/setsockopt.2.html
 /// [Linux `ipv6`]: https://man7.org/linux/man-pages/man7/ipv6.7.html
 /// [Winsock2 `setsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-setsockopt
 /// [Winsock2 `IPPROTO_IPV6` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ipv6-socket-options
 /// [Apple `setsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/setsockopt.2.html
 /// [Apple `ip6`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/ip6.4.auto.html
 /// [FreeBSD `setsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=setsockopt&sektion=2
 /// [FreeBSD `ip6`]: https://man.freebsd.org/cgi/man.cgi?query=ip6&sektion=4
 /// [NetBSD `setsockopt`]: https://man.netbsd.org/setsockopt.2
 /// [NetBSD `ip6`]: https://man.netbsd.org/ip6.4
 /// [OpenBSD `setsockopt`]: https://man.openbsd.org/setsockopt.2
 /// [OpenBSD `ip6`]: https://man.openbsd.org/ip6.4
 /// [DragonFly BSD `setsockopt`]: https://man.dragonflybsd.org/?command=setsockopt&section=2
 /// [DragonFly BSD `ip6`]: https://man.dragonflybsd.org/?command=ip6&section=4
 /// [illumos `setsockopt`]: https://illumos.org/man/3SOCKET/setsockopt
 /// [illumos `ip6`]: https://illumos.org/man/4P/ip6
 #[inline]
 #[doc(alias = "IPV6_V6ONLY")]
 pub fn set_ipv6_v6only<Fd: AsFd>(fd: Fd, only_v6: bool) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_ipv6_v6only(fd.as_fd(), only_v6)
 }

 /// `getsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY)`
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `netinet/in.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `ipv6`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `IPPROTO_IPV6` options]
 ///  - [Apple `getsockopt`]
 ///  - [Apple `ip6`]
 ///  - [FreeBSD `getsockopt`]
 ///  - [FreeBSD `ip6`]
 ///  - [NetBSD `getsockopt`]
 ///  - [NetBSD `ip6`]
 ///  - [OpenBSD `getsockopt`]
 ///  - [OpenBSD `ip6`]
 ///  - [DragonFly BSD `getsockopt`]
 ///  - [DragonFly BSD `ip6`]
 ///  - [illumos `getsockopt`]
 ///  - [illumos `ip6`]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `netinet/in.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_in.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `ipv6`]: https://man7.org/linux/man-pages/man7/ipv6.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `IPPROTO_IPV6` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ipv6-socket-options
 /// [Apple `getsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getsockopt.2.html
 /// [Apple `ip6`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/ip6.4.auto.html
 /// [FreeBSD `getsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=getsockopt&sektion=2
 /// [FreeBSD `ip6`]: https://man.freebsd.org/cgi/man.cgi?query=ip6&sektion=4
 /// [NetBSD `getsockopt`]: https://man.netbsd.org/getsockopt.2
 /// [NetBSD `ip6`]: https://man.netbsd.org/ip6.4
 /// [OpenBSD `getsockopt`]: https://man.openbsd.org/getsockopt.2
 /// [OpenBSD `ip6`]: https://man.openbsd.org/ip6.4
 /// [DragonFly BSD `getsockopt`]: https://man.dragonflybsd.org/?command=getsockopt&section=2
 /// [DragonFly BSD `ip6`]: https://man.dragonflybsd.org/?command=ip6&section=4
 /// [illumos `getsockopt`]: https://illumos.org/man/3SOCKET/getsockopt
 /// [illumos `ip6`]: https://illumos.org/man/4P/ip6
 #[inline]
 #[doc(alias = "IPV6_V6ONLY")]
 pub fn get_ipv6_v6only<Fd: AsFd>(fd: Fd) -> io::Result<bool> {
     backend::net::syscalls::sockopt::get_ipv6_v6only(fd.as_fd())
 }

 /// `setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP, multicast_loop)`
 ///
 /// # References
 ///  - [POSIX `setsockopt`]
 ///  - [POSIX `netinet/in.h`]
 ///  - [Linux `setsockopt`]
 ///  - [Linux `ip`]
 ///  - [Winsock2 `setsockopt`]
 ///  - [Winsock2 `IPPROTO_IP` options]
 ///  - [Apple `setsockopt`]
 ///  - [Apple `ip`]
 ///  - [FreeBSD `setsockopt`]
 ///  - [FreeBSD `ip`]
 ///  - [NetBSD `setsockopt`]
 ///  - [NetBSD `ip`]
 ///  - [OpenBSD `setsockopt`]
 ///  - [OpenBSD `ip`]
 ///  - [DragonFly BSD `setsockopt`]
 ///  - [DragonFly BSD `ip`]
 ///  - [illumos `setsockopt`]
 ///  - [illumos `ip`]
 ///
 /// [POSIX `setsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/setsockopt.html
 /// [POSIX `netinet/in.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_in.h.html
 /// [Linux `setsockopt`]: https://man7.org/linux/man-pages/man2/setsockopt.2.html
 /// [Linux `ip`]: https://man7.org/linux/man-pages/man7/ip.7.html
 /// [Winsock2 `setsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-setsockopt
 /// [Winsock2 `IPPROTO_IP` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ip-socket-options
 /// [Apple `setsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/setsockopt.2.html
 /// [Apple `ip`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/ip.4.auto.html
 /// [FreeBSD `setsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=setsockopt&sektion=2
 /// [FreeBSD `ip`]: https://man.freebsd.org/cgi/man.cgi?query=ip&sektion=4
 /// [NetBSD `setsockopt`]: https://man.netbsd.org/setsockopt.2
 /// [NetBSD `ip`]: https://man.netbsd.org/ip.4
 /// [OpenBSD `setsockopt`]: https://man.openbsd.org/setsockopt.2
 /// [OpenBSD `ip`]: https://man.openbsd.org/ip.4
 /// [DragonFly BSD `setsockopt`]: https://man.dragonflybsd.org/?command=setsockopt&section=2
 /// [DragonFly BSD `ip`]: https://man.dragonflybsd.org/?command=ip&section=4
 /// [illumos `setsockopt`]: https://illumos.org/man/3SOCKET/setsockopt
 /// [illumos `ip`]: https://illumos.org/man/4P/ip
 #[inline]
 #[doc(alias = "IP_MULTICAST_LOOP")]
 pub fn set_ip_multicast_loop<Fd: AsFd>(fd: Fd, multicast_loop: bool) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_ip_multicast_loop(fd.as_fd(), multicast_loop)
 }

 /// `getsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP)`
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `netinet/in.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `ip`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `IPPROTO_IP` options]
 ///  - [Apple `getsockopt`]
 ///  - [Apple `ip`]
 ///  - [FreeBSD `getsockopt`]
 ///  - [FreeBSD `ip`]
 ///  - [NetBSD `getsockopt`]
 ///  - [NetBSD `ip`]
 ///  - [OpenBSD `getsockopt`]
 ///  - [OpenBSD `ip`]
 ///  - [DragonFly BSD `getsockopt`]
 ///  - [DragonFly BSD `ip`]
 ///  - [illumos `getsockopt`]
 ///  - [illumos `ip`]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `netinet/in.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_in.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `ip`]: https://man7.org/linux/man-pages/man7/ip.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `IPPROTO_IP` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ip-socket-options
 #[inline]
 #[doc(alias = "IP_MULTICAST_LOOP")]
 pub fn get_ip_multicast_loop<Fd: AsFd>(fd: Fd) -> io::Result<bool> {
     backend::net::syscalls::sockopt::get_ip_multicast_loop(fd.as_fd())
 }

 /// `setsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL, multicast_ttl)`
 ///
 /// # References
 ///  - [POSIX `setsockopt`]
 ///  - [POSIX `netinet/in.h`]
 ///  - [Linux `setsockopt`]
 ///  - [Linux `ip`]
 ///  - [Winsock2 `setsockopt`]
 ///  - [Winsock2 `IPPROTO_IP` options]
 ///  - [Apple `setsockopt`]
 ///  - [Apple `ip`]
 ///  - [FreeBSD `setsockopt`]
 ///  - [FreeBSD `ip`]
 ///  - [NetBSD `setsockopt`]
 ///  - [NetBSD `ip`]
 ///  - [OpenBSD `setsockopt`]
 ///  - [OpenBSD `ip`]
 ///  - [DragonFly BSD `setsockopt`]
 ///  - [DragonFly BSD `ip`]
 ///  - [illumos `setsockopt`]
 ///  - [illumos `ip`]
 ///
 /// [POSIX `setsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/setsockopt.html
 /// [POSIX `netinet/in.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_in.h.html
 /// [Linux `setsockopt`]: https://man7.org/linux/man-pages/man2/setsockopt.2.html
 /// [Linux `ip`]: https://man7.org/linux/man-pages/man7/ip.7.html
 /// [Winsock2 `setsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-setsockopt
 /// [Winsock2 `IPPROTO_IP` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ip-socket-options
 /// [Apple `setsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/setsockopt.2.html
 /// [Apple `ip`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/ip.4.auto.html
 /// [FreeBSD `setsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=setsockopt&sektion=2
 /// [FreeBSD `ip`]: https://man.freebsd.org/cgi/man.cgi?query=ip&sektion=4
 /// [NetBSD `setsockopt`]: https://man.netbsd.org/setsockopt.2
 /// [NetBSD `ip`]: https://man.netbsd.org/ip.4
 /// [OpenBSD `setsockopt`]: https://man.openbsd.org/setsockopt.2
 /// [OpenBSD `ip`]: https://man.openbsd.org/ip.4
 /// [DragonFly BSD `setsockopt`]: https://man.dragonflybsd.org/?command=setsockopt&section=2
 /// [DragonFly BSD `ip`]: https://man.dragonflybsd.org/?command=ip&section=4
 /// [illumos `setsockopt`]: https://illumos.org/man/3SOCKET/setsockopt
 /// [illumos `ip`]: https://illumos.org/man/4P/ip
 #[inline]
 #[doc(alias = "IP_MULTICAST_TTL")]
 pub fn set_ip_multicast_ttl<Fd: AsFd>(fd: Fd, multicast_ttl: u32) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_ip_multicast_ttl(fd.as_fd(), multicast_ttl)
 }

 /// `getsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL)`
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `netinet/in.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `ip`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `IPPROTO_IP` options]
 ///  - [Apple `getsockopt`]
 ///  - [Apple `ip`]
 ///  - [FreeBSD `getsockopt`]
 ///  - [FreeBSD `ip`]
 ///  - [NetBSD `getsockopt`]
 ///  - [NetBSD `ip`]
 ///  - [OpenBSD `getsockopt`]
 ///  - [OpenBSD `ip`]
 ///  - [DragonFly BSD `getsockopt`]
 ///  - [DragonFly BSD `ip`]
 ///  - [illumos `getsockopt`]
 ///  - [illumos `ip`]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `netinet/in.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_in.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `ip`]: https://man7.org/linux/man-pages/man7/ip.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `IPPROTO_IP` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ip-socket-options
 #[inline]
 #[doc(alias = "IP_MULTICAST_TTL")]
 pub fn get_ip_multicast_ttl<Fd: AsFd>(fd: Fd) -> io::Result<u32> {
     backend::net::syscalls::sockopt::get_ip_multicast_ttl(fd.as_fd())
 }

 /// `setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, multicast_loop)`
 ///
 /// # References
 ///  - [POSIX `setsockopt`]
 ///  - [POSIX `netinet/in.h`]
 ///  - [Linux `setsockopt`]
 ///  - [Linux `ipv6`]
 ///  - [Winsock2 `setsockopt`]
 ///  - [Winsock2 `IPPROTO_IPV6` options]
 ///  - [Apple `setsockopt`]
 ///  - [Apple `ip6`]
 ///  - [FreeBSD `setsockopt`]
 ///  - [FreeBSD `ip6`]
 ///  - [NetBSD `setsockopt`]
 ///  - [NetBSD `ip6`]
 ///  - [OpenBSD `setsockopt`]
 ///  - [OpenBSD `ip6`]
 ///  - [DragonFly BSD `setsockopt`]
 ///  - [DragonFly BSD `ip6`]
 ///  - [illumos `setsockopt`]
 ///  - [illumos `ip6`]
 ///
 /// [POSIX `setsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/setsockopt.html
 /// [POSIX `netinet/in.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_in.h.html
 /// [Linux `setsockopt`]: https://man7.org/linux/man-pages/man2/setsockopt.2.html
 /// [Linux `ipv6`]: https://man7.org/linux/man-pages/man7/ipv6.7.html
 /// [Winsock2 `setsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-setsockopt
 /// [Winsock2 `IPPROTO_IPV6` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ipv6-socket-options
 /// [Apple `setsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/setsockopt.2.html
 /// [Apple `ip6`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/ip6.4.auto.html
 /// [FreeBSD `setsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=setsockopt&sektion=2
 /// [FreeBSD `ip6`]: https://man.freebsd.org/cgi/man.cgi?query=ip6&sektion=4
 /// [NetBSD `setsockopt`]: https://man.netbsd.org/setsockopt.2
 /// [NetBSD `ip6`]: https://man.netbsd.org/ip6.4
 /// [OpenBSD `setsockopt`]: https://man.openbsd.org/setsockopt.2
 /// [OpenBSD `ip6`]: https://man.openbsd.org/ip6.4
 /// [DragonFly BSD `setsockopt`]: https://man.dragonflybsd.org/?command=setsockopt&section=2
 /// [DragonFly BSD `ip6`]: https://man.dragonflybsd.org/?command=ip6&section=4
 /// [illumos `setsockopt`]: https://illumos.org/man/3SOCKET/setsockopt
 /// [illumos `ip6`]: https://illumos.org/man/4P/ip6
 #[inline]
 #[doc(alias = "IPV6_MULTICAST_LOOP")]
 pub fn set_ipv6_multicast_loop<Fd: AsFd>(fd: Fd, multicast_loop: bool) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_ipv6_multicast_loop(fd.as_fd(), multicast_loop)
 }

 /// `getsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP)`
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `netinet/in.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `ipv6`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `IPPROTO_IPV6` options]
 ///  - [Apple `getsockopt`]
 ///  - [Apple `ip6`]
 ///  - [FreeBSD `getsockopt`]
 ///  - [FreeBSD `ip6`]
 ///  - [NetBSD `getsockopt`]
 ///  - [NetBSD `ip6`]
 ///  - [OpenBSD `getsockopt`]
 ///  - [OpenBSD `ip6`]
 ///  - [DragonFly BSD `getsockopt`]
 ///  - [DragonFly BSD `ip6`]
 ///  - [illumos `getsockopt`]
 ///  - [illumos `ip6`]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `netinet/in.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_in.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `ipv6`]: https://man7.org/linux/man-pages/man7/ipv6.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `IPPROTO_IPV6` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ipv6-socket-options
 /// [Apple `getsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getsockopt.2.html
 /// [Apple `ip6`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/ip6.4.auto.html
 /// [FreeBSD `getsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=getsockopt&sektion=2
 /// [FreeBSD `ip6`]: https://man.freebsd.org/cgi/man.cgi?query=ip6&sektion=4
 /// [NetBSD `getsockopt`]: https://man.netbsd.org/getsockopt.2
 /// [NetBSD `ip6`]: https://man.netbsd.org/ip6.4
 /// [OpenBSD `getsockopt`]: https://man.openbsd.org/getsockopt.2
 /// [OpenBSD `ip6`]: https://man.openbsd.org/ip6.4
 /// [DragonFly BSD `getsockopt`]: https://man.dragonflybsd.org/?command=getsockopt&section=2
 /// [DragonFly BSD `ip6`]: https://man.dragonflybsd.org/?command=ip6&section=4
 /// [illumos `getsockopt`]: https://illumos.org/man/3SOCKET/getsockopt
 /// [illumos `ip6`]: https://illumos.org/man/4P/ip6
 #[inline]
 #[doc(alias = "IPV6_MULTICAST_LOOP")]
 pub fn get_ipv6_multicast_loop<Fd: AsFd>(fd: Fd) -> io::Result<bool> {
     backend::net::syscalls::sockopt::get_ipv6_multicast_loop(fd.as_fd())
 }

 /// `setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, multicast_hops)`
 ///
 /// # References
 ///  - [POSIX `setsockopt`]
 ///  - [POSIX `netinet/in.h`]
 ///  - [Linux `setsockopt`]
 ///  - [Linux `ipv6`]
 ///  - [Winsock2 `setsockopt`]
 ///  - [Winsock2 `IPPROTO_IPV6` options]
 ///  - [Apple `setsockopt`]
 ///  - [Apple `ip6`]
 ///  - [FreeBSD `setsockopt`]
 ///  - [FreeBSD `ip6`]
 ///  - [NetBSD `setsockopt`]
 ///  - [NetBSD `ip6`]
 ///  - [OpenBSD `setsockopt`]
 ///  - [OpenBSD `ip6`]
 ///  - [DragonFly BSD `setsockopt`]
 ///  - [DragonFly BSD `ip6`]
 ///  - [illumos `setsockopt`]
 ///  - [illumos `ip6`]
 ///
 /// [POSIX `setsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/setsockopt.html
 /// [POSIX `netinet/in.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_in.h.html
 /// [Linux `setsockopt`]: https://man7.org/linux/man-pages/man2/setsockopt.2.html
 /// [Linux `ipv6`]: https://man7.org/linux/man-pages/man7/ipv6.7.html
 /// [Winsock2 `setsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-setsockopt
 /// [Winsock2 `IPPROTO_IPV6` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ipv6-socket-options
 /// [Apple `setsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/setsockopt.2.html
 /// [Apple `ip6`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/ip6.4.auto.html
 /// [FreeBSD `setsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=setsockopt&sektion=2
 /// [FreeBSD `ip6`]: https://man.freebsd.org/cgi/man.cgi?query=ip6&sektion=4
 /// [NetBSD `setsockopt`]: https://man.netbsd.org/setsockopt.2
 /// [NetBSD `ip6`]: https://man.netbsd.org/ip6.4
 /// [OpenBSD `setsockopt`]: https://man.openbsd.org/setsockopt.2
 /// [OpenBSD `ip6`]: https://man.openbsd.org/ip6.4
 /// [DragonFly BSD `setsockopt`]: https://man.dragonflybsd.org/?command=setsockopt&section=2
 /// [DragonFly BSD `ip6`]: https://man.dragonflybsd.org/?command=ip6&section=4
 /// [illumos `setsockopt`]: https://illumos.org/man/3SOCKET/setsockopt
 /// [illumos `ip6`]: https://illumos.org/man/4P/ip6
 #[inline]
 #[doc(alias = "IP_MULTICAST_TTL")]
 pub fn set_ipv6_multicast_hops<Fd: AsFd>(fd: Fd, multicast_hops: u32) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_ipv6_multicast_hops(fd.as_fd(), multicast_hops)
 }

 /// `getsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS)`
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `netinet/in.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `ipv6`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `IPPROTO_IPV6` options]
 ///  - [Apple `getsockopt`]
 ///  - [Apple `ip6`]
 ///  - [FreeBSD `getsockopt`]
 ///  - [FreeBSD `ip6`]
 ///  - [NetBSD `getsockopt`]
 ///  - [NetBSD `ip6`]
 ///  - [OpenBSD `getsockopt`]
 ///  - [OpenBSD `ip6`]
 ///  - [DragonFly BSD `getsockopt`]
 ///  - [DragonFly BSD `ip6`]
 ///  - [illumos `getsockopt`]
 ///  - [illumos `ip6`]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `netinet/in.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_in.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `ipv6`]: https://man7.org/linux/man-pages/man7/ipv6.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `IPPROTO_IPV6` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ipv6-socket-options
 /// [Apple `getsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getsockopt.2.html
 /// [Apple `ip6`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/ip6.4.auto.html
 /// [FreeBSD `getsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=getsockopt&sektion=2
 /// [FreeBSD `ip6`]: https://man.freebsd.org/cgi/man.cgi?query=ip6&sektion=4
 /// [NetBSD `getsockopt`]: https://man.netbsd.org/getsockopt.2
 /// [NetBSD `ip6`]: https://man.netbsd.org/ip6.4
 /// [OpenBSD `getsockopt`]: https://man.openbsd.org/getsockopt.2
 /// [OpenBSD `ip6`]: https://man.openbsd.org/ip6.4
 /// [DragonFly BSD `getsockopt`]: https://man.dragonflybsd.org/?command=getsockopt&section=2
 /// [DragonFly BSD `ip6`]: https://man.dragonflybsd.org/?command=ip6&section=4
 /// [illumos `getsockopt`]: https://illumos.org/man/3SOCKET/getsockopt
 /// [illumos `ip6`]: https://illumos.org/man/4P/ip6
 #[inline]
 #[doc(alias = "IPV6_UNICAST_HOPS")]
 pub fn get_ipv6_unicast_hops<Fd: AsFd>(fd: Fd) -> io::Result<u8> {
     backend::net::syscalls::sockopt::get_ipv6_unicast_hops(fd.as_fd())
 }

 /// `setsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, unicast_hops)`
 ///
 /// # References
 ///  - [POSIX `setsockopt`]
 ///  - [POSIX `netinet/in.h`]
 ///  - [Linux `setsockopt`]
 ///  - [Linux `ipv6`]
 ///  - [Winsock2 `setsockopt`]
 ///  - [Winsock2 `IPPROTO_IPV6` options]
 ///  - [Apple `setsockopt`]
 ///  - [Apple `ip6`]
 ///  - [FreeBSD `setsockopt`]
 ///  - [FreeBSD `ip6`]
 ///  - [NetBSD `setsockopt`]
 ///  - [NetBSD `ip6`]
 ///  - [OpenBSD `setsockopt`]
 ///  - [OpenBSD `ip6`]
 ///  - [DragonFly BSD `setsockopt`]
 ///  - [DragonFly BSD `ip6`]
 ///  - [illumos `setsockopt`]
 ///  - [illumos `ip6`]
 ///
 /// [POSIX `setsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/setsockopt.html
 /// [POSIX `netinet/in.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_in.h.html
 /// [Linux `setsockopt`]: https://man7.org/linux/man-pages/man2/setsockopt.2.html
 /// [Linux `ipv6`]: https://man7.org/linux/man-pages/man7/ipv6.7.html
 /// [Winsock2 `setsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-setsockopt
 /// [Winsock2 `IPPROTO_IPV6` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ipv6-socket-options
 /// [Apple `setsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/setsockopt.2.html
 /// [Apple `ip6`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/ip6.4.auto.html
 /// [FreeBSD `setsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=setsockopt&sektion=2
 /// [FreeBSD `ip6`]: https://man.freebsd.org/cgi/man.cgi?query=ip6&sektion=4
 /// [NetBSD `setsockopt`]: https://man.netbsd.org/setsockopt.2
 /// [NetBSD `ip6`]: https://man.netbsd.org/ip6.4
 /// [OpenBSD `setsockopt`]: https://man.openbsd.org/setsockopt.2
 /// [OpenBSD `ip6`]: https://man.openbsd.org/ip6.4
 /// [DragonFly BSD `setsockopt`]: https://man.dragonflybsd.org/?command=setsockopt&section=2
 /// [DragonFly BSD `ip6`]: https://man.dragonflybsd.org/?command=ip6&section=4
 /// [illumos `setsockopt`]: https://illumos.org/man/3SOCKET/setsockopt
 /// [illumos `ip6`]: https://illumos.org/man/4P/ip6
 #[inline]
 #[doc(alias = "IPV6_UNICAST_HOPS")]
 pub fn set_ipv6_unicast_hops<Fd: AsFd>(fd: Fd, unicast_hops: Option<u8>) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_ipv6_unicast_hops(fd.as_fd(), unicast_hops)
 }

 /// `getsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS)`
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `netinet/in.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `ipv6`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `IPPROTO_IPV6` options]
 ///  - [Apple `getsockopt`]
 ///  - [Apple `ip6`]
 ///  - [FreeBSD `getsockopt`]
 ///  - [FreeBSD `ip6`]
 ///  - [NetBSD `getsockopt`]
 ///  - [NetBSD `ip6`]
 ///  - [OpenBSD `getsockopt`]
 ///  - [OpenBSD `ip6`]
 ///  - [DragonFly BSD `getsockopt`]
 ///  - [DragonFly BSD `ip6`]
 ///  - [illumos `getsockopt`]
 ///  - [illumos `ip6`]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `netinet/in.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_in.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `ipv6`]: https://man7.org/linux/man-pages/man7/ipv6.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `IPPROTO_IPV6` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ipv6-socket-options
 /// [Apple `getsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getsockopt.2.html
 /// [Apple `ip6`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/ip6.4.auto.html
 /// [FreeBSD `getsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=getsockopt&sektion=2
 /// [FreeBSD `ip6`]: https://man.freebsd.org/cgi/man.cgi?query=ip6&sektion=4
 /// [NetBSD `getsockopt`]: https://man.netbsd.org/getsockopt.2
 /// [NetBSD `ip6`]: https://man.netbsd.org/ip6.4
 /// [OpenBSD `getsockopt`]: https://man.openbsd.org/getsockopt.2
 /// [OpenBSD `ip6`]: https://man.openbsd.org/ip6.4
 /// [DragonFly BSD `getsockopt`]: https://man.dragonflybsd.org/?command=getsockopt&section=2
 /// [DragonFly BSD `ip6`]: https://man.dragonflybsd.org/?command=ip6&section=4
 /// [illumos `getsockopt`]: https://illumos.org/man/3SOCKET/getsockopt
 /// [illumos `ip6`]: https://illumos.org/man/4P/ip6
 #[inline]
 #[doc(alias = "IP_MULTICAST_TTL")]
 pub fn get_ipv6_multicast_hops<Fd: AsFd>(fd: Fd) -> io::Result<u32> {
     backend::net::syscalls::sockopt::get_ipv6_multicast_hops(fd.as_fd())
 }

 /// `setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, multiaddr, interface)`
 ///
 /// # References
 ///  - [POSIX `setsockopt`]
 ///  - [POSIX `netinet/in.h`]
 ///  - [Linux `setsockopt`]
 ///  - [Linux `ip`]
 ///  - [Winsock2 `setsockopt`]
 ///  - [Winsock2 `IPPROTO_IP` options]
 ///  - [Apple `setsockopt`]
 ///  - [Apple `ip`]
 ///  - [FreeBSD `setsockopt`]
 ///  - [FreeBSD `ip`]
 ///  - [NetBSD `setsockopt`]
 ///  - [NetBSD `ip`]
 ///  - [OpenBSD `setsockopt`]
 ///  - [OpenBSD `ip`]
 ///  - [DragonFly BSD `setsockopt`]
 ///  - [DragonFly BSD `ip`]
 ///  - [illumos `setsockopt`]
 ///  - [illumos `ip`]
 ///
 /// [POSIX `setsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/setsockopt.html
 /// [POSIX `netinet/in.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_in.h.html
 /// [Linux `setsockopt`]: https://man7.org/linux/man-pages/man2/setsockopt.2.html
 /// [Linux `ip`]: https://man7.org/linux/man-pages/man7/ip.7.html
 /// [Winsock2 `setsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-setsockopt
 /// [Winsock2 `IPPROTO_IP` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ip-socket-options
 /// [Apple `setsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/setsockopt.2.html
 /// [Apple `ip`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/ip.4.auto.html
 /// [FreeBSD `setsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=setsockopt&sektion=2
 /// [FreeBSD `ip`]: https://man.freebsd.org/cgi/man.cgi?query=ip&sektion=4
 /// [NetBSD `setsockopt`]: https://man.netbsd.org/setsockopt.2
 /// [NetBSD `ip`]: https://man.netbsd.org/ip.4
 /// [OpenBSD `setsockopt`]: https://man.openbsd.org/setsockopt.2
 /// [OpenBSD `ip`]: https://man.openbsd.org/ip.4
 /// [DragonFly BSD `setsockopt`]: https://man.dragonflybsd.org/?command=setsockopt&section=2
 /// [DragonFly BSD `ip`]: https://man.dragonflybsd.org/?command=ip&section=4
 /// [illumos `setsockopt`]: https://illumos.org/man/3SOCKET/setsockopt
 /// [illumos `ip`]: https://illumos.org/man/4P/ip
 #[inline]
 #[doc(alias = "IP_ADD_MEMBERSHIP")]
 pub fn set_ip_add_membership<Fd: AsFd>(
     fd: Fd,
     multiaddr: &Ipv4Addr,
     interface: &Ipv4Addr,
 ) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_ip_add_membership(fd.as_fd(), multiaddr, interface)
 }

 /// `setsockopt(fd, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, multiaddr, interface)`
 ///
 /// `IPV6_ADD_MEMBERSHIP` is the same as `IPV6_JOIN_GROUP` in POSIX.
 ///
 /// # References
 ///  - [POSIX `setsockopt`]
 ///  - [POSIX `netinet/in.h`]
 ///  - [Linux `setsockopt`]
 ///  - [Linux `ipv6`]
 ///  - [Winsock2 `setsockopt`]
 ///  - [Winsock2 `IPPROTO_IPV6` options]
 ///  - [Apple `setsockopt`]
 ///  - [Apple `ip6`]
 ///  - [FreeBSD `setsockopt`]
 ///  - [FreeBSD `ip6`]
 ///  - [NetBSD `setsockopt`]
 ///  - [NetBSD `ip6`]
 ///  - [OpenBSD `setsockopt`]
 ///  - [OpenBSD `ip6`]
 ///  - [DragonFly BSD `setsockopt`]
 ///  - [DragonFly BSD `ip6`]
 ///  - [illumos `setsockopt`]
 ///  - [illumos `ip6`]
 ///
 /// [POSIX `setsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/setsockopt.html
 /// [POSIX `netinet/in.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_in.h.html
 /// [Linux `setsockopt`]: https://man7.org/linux/man-pages/man2/setsockopt.2.html
 /// [Linux `ipv6`]: https://man7.org/linux/man-pages/man7/ipv6.7.html
 /// [Winsock2 `setsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-setsockopt
 /// [Winsock2 `IPPROTO_IPV6` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ipv6-socket-options
 /// [Apple `setsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/setsockopt.2.html
 /// [Apple `ip6`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/ip6.4.auto.html
 /// [FreeBSD `setsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=setsockopt&sektion=2
 /// [FreeBSD `ip6`]: https://man.freebsd.org/cgi/man.cgi?query=ip6&sektion=4
 /// [NetBSD `setsockopt`]: https://man.netbsd.org/setsockopt.2
 /// [NetBSD `ip6`]: https://man.netbsd.org/ip6.4
 /// [OpenBSD `setsockopt`]: https://man.openbsd.org/setsockopt.2
 /// [OpenBSD `ip6`]: https://man.openbsd.org/ip6.4
 /// [DragonFly BSD `setsockopt`]: https://man.dragonflybsd.org/?command=setsockopt&section=2
 /// [DragonFly BSD `ip6`]: https://man.dragonflybsd.org/?command=ip6&section=4
 /// [illumos `setsockopt`]: https://illumos.org/man/3SOCKET/setsockopt
 /// [illumos `ip6`]: https://illumos.org/man/4P/ip6
 #[inline]
 #[doc(alias = "IPV6_JOIN_GROUP")]
 #[doc(alias = "IPV6_ADD_MEMBERSHIP")]
 pub fn set_ipv6_add_membership<Fd: AsFd>(
     fd: Fd,
     multiaddr: &Ipv6Addr,
     interface: u32,
 ) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_ipv6_add_membership(fd.as_fd(), multiaddr, interface)
 }

 /// `setsockopt(fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, multiaddr, interface)`
 ///
 /// # References
 ///  - [POSIX `setsockopt`]
 ///  - [POSIX `netinet/in.h`]
 ///  - [Linux `setsockopt`]
 ///  - [Linux `ip`]
 ///  - [Winsock2 `setsockopt`]
 ///  - [Winsock2 `IPPROTO_IP` options]
 ///  - [Apple `setsockopt`]
 ///  - [Apple `ip`]
 ///  - [FreeBSD `setsockopt`]
 ///  - [FreeBSD `ip`]
 ///  - [NetBSD `setsockopt`]
 ///  - [NetBSD `ip`]
 ///  - [OpenBSD `setsockopt`]
 ///  - [OpenBSD `ip`]
 ///  - [DragonFly BSD `setsockopt`]
 ///  - [DragonFly BSD `ip`]
 ///  - [illumos `setsockopt`]
 ///  - [illumos `ip`]
 ///
 /// [POSIX `setsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/setsockopt.html
 /// [POSIX `netinet/in.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_in.h.html
 /// [Linux `setsockopt`]: https://man7.org/linux/man-pages/man2/setsockopt.2.html
 /// [Linux `ip`]: https://man7.org/linux/man-pages/man7/ip.7.html
 /// [Winsock2 `setsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-setsockopt
 /// [Winsock2 `IPPROTO_IP` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ip-socket-options
 /// [Apple `setsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/setsockopt.2.html
 /// [Apple `ip`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/ip.4.auto.html
 /// [FreeBSD `setsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=setsockopt&sektion=2
 /// [FreeBSD `ip`]: https://man.freebsd.org/cgi/man.cgi?query=ip&sektion=4
 /// [NetBSD `setsockopt`]: https://man.netbsd.org/setsockopt.2
 /// [NetBSD `ip`]: https://man.netbsd.org/ip.4
 /// [OpenBSD `setsockopt`]: https://man.openbsd.org/setsockopt.2
 /// [OpenBSD `ip`]: https://man.openbsd.org/ip.4
 /// [DragonFly BSD `setsockopt`]: https://man.dragonflybsd.org/?command=setsockopt&section=2
 /// [DragonFly BSD `ip`]: https://man.dragonflybsd.org/?command=ip&section=4
 /// [illumos `setsockopt`]: https://illumos.org/man/3SOCKET/setsockopt
 /// [illumos `ip`]: https://illumos.org/man/4P/ip
 #[inline]
 #[doc(alias = "IP_DROP_MEMBERSHIP")]
 pub fn set_ip_drop_membership<Fd: AsFd>(
     fd: Fd,
     multiaddr: &Ipv4Addr,
     interface: &Ipv4Addr,
 ) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_ip_drop_membership(fd.as_fd(), multiaddr, interface)
 }

 /// `setsockopt(fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP, multiaddr, interface)`
 ///
 /// `IPV6_DROP_MEMBERSHIP` is the same as `IPV6_LEAVE_GROUP` in POSIX.
 ///
 /// # References
 ///  - [POSIX `setsockopt`]
 ///  - [POSIX `netinet/in.h`]
 ///  - [Linux `setsockopt`]
 ///  - [Linux `ipv6`]
 ///  - [Winsock2 `setsockopt`]
 ///  - [Winsock2 `IPPROTO_IPV6` options]
 ///  - [Apple `setsockopt`]
 ///  - [Apple `ip6`]
 ///  - [FreeBSD `setsockopt`]
 ///  - [FreeBSD `ip6`]
 ///  - [NetBSD `setsockopt`]
 ///  - [NetBSD `ip6`]
 ///  - [OpenBSD `setsockopt`]
 ///  - [OpenBSD `ip6`]
 ///  - [DragonFly BSD `setsockopt`]
 ///  - [DragonFly BSD `ip6`]
 ///  - [illumos `setsockopt`]
 ///  - [illumos `ip6`]
 ///
 /// [POSIX `setsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/setsockopt.html
 /// [POSIX `netinet/in.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_in.h.html
 /// [Linux `setsockopt`]: https://man7.org/linux/man-pages/man2/setsockopt.2.html
 /// [Linux `ipv6`]: https://man7.org/linux/man-pages/man7/ipv6.7.html
 /// [Winsock2 `setsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-setsockopt
 /// [Winsock2 `IPPROTO_IPV6` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ipv6-socket-options
 /// [Apple `setsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/setsockopt.2.html
 /// [Apple `ip6`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/ip6.4.auto.html
 /// [FreeBSD `setsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=setsockopt&sektion=2
 /// [FreeBSD `ip6`]: https://man.freebsd.org/cgi/man.cgi?query=ip6&sektion=4
 /// [NetBSD `setsockopt`]: https://man.netbsd.org/setsockopt.2
 /// [NetBSD `ip6`]: https://man.netbsd.org/ip6.4
 /// [OpenBSD `setsockopt`]: https://man.openbsd.org/setsockopt.2
 /// [OpenBSD `ip6`]: https://man.openbsd.org/ip6.4
 /// [DragonFly BSD `setsockopt`]: https://man.dragonflybsd.org/?command=setsockopt&section=2
 /// [DragonFly BSD `ip6`]: https://man.dragonflybsd.org/?command=ip6&section=4
 /// [illumos `setsockopt`]: https://illumos.org/man/3SOCKET/setsockopt
 /// [illumos `ip6`]: https://illumos.org/man/4P/ip6
 #[inline]
 #[doc(alias = "IPV6_LEAVE_GROUP")]
 #[doc(alias = "IPV6_DROP_MEMBERSHIP")]
 pub fn set_ipv6_drop_membership<Fd: AsFd>(
     fd: Fd,
     multiaddr: &Ipv6Addr,
     interface: u32,
 ) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_ipv6_drop_membership(fd.as_fd(), multiaddr, interface)
 }

 /// `setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, nodelay)`
 ///
 /// # References
 ///  - [POSIX `setsockopt`]
 ///  - [POSIX `netinet/tcp.h`]
 ///  - [Linux `setsockopt`]
 ///  - [Linux `tcp`]
 ///  - [Winsock2 `setsockopt`]
 ///  - [Winsock2 `IPPROTO_TCP` options]
 ///  - [Apple `setsockopt`]
 ///  - [Apple `tcp`]
 ///  - [FreeBSD `setsockopt`]
 ///  - [FreeBSD `tcp`]
 ///  - [NetBSD `setsockopt`]
 ///  - [NetBSD `tcp`]
 ///  - [OpenBSD `setsockopt`]
 ///  - [OpenBSD `tcp`]
 ///  - [DragonFly BSD `setsockopt`]
 ///  - [DragonFly BSD `tcp`]
 ///  - [illumos `setsockopt`]
 ///  - [illumos `tcp`]
 ///
 /// [POSIX `setsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/setsockopt.html
 /// [POSIX `netinet/tcp.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_tcp.h.html
 /// [Linux `setsockopt`]: https://man7.org/linux/man-pages/man2/setsockopt.2.html
 /// [Linux `tcp`]: https://man7.org/linux/man-pages/man7/tcp.7.html
 /// [Winsock2 `setsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-setsockopt
 /// [Winsock2 `IPPROTO_TCP` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-tcp-socket-options
 /// [Apple `setsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/setsockopt.2.html
 /// [Apple `tcp`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/tcp.4.auto.html
 /// [FreeBSD `setsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=setsockopt&sektion=2
 /// [FreeBSD `tcp`]: https://man.freebsd.org/cgi/man.cgi?query=tcp&sektion=4
 /// [NetBSD `setsockopt`]: https://man.netbsd.org/setsockopt.2
 /// [NetBSD `tcp`]: https://man.netbsd.org/tcp.4
 /// [OpenBSD `setsockopt`]: https://man.openbsd.org/setsockopt.2
 /// [OpenBSD `tcp`]: https://man.openbsd.org/tcp.4
 /// [DragonFly BSD `setsockopt`]: https://man.dragonflybsd.org/?command=setsockopt&section=2
 /// [DragonFly BSD `tcp`]: https://man.dragonflybsd.org/?command=tcp&section=4
 /// [illumos `setsockopt`]: https://illumos.org/man/3SOCKET/setsockopt
 /// [illumos `tcp`]: https://illumos.org/man/4P/tcp
 #[inline]
 #[doc(alias = "TCP_NODELAY")]
 pub fn set_tcp_nodelay<Fd: AsFd>(fd: Fd, nodelay: bool) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_tcp_nodelay(fd.as_fd(), nodelay)
 }

 /// `getsockopt(fd, IPPROTO_TCP, TCP_NODELAY)`
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `netinet/tcp.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `tcp`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `IPPROTO_TCP` options]
 ///  - [Apple `getsockopt`]
 ///  - [Apple `tcp`]
 ///  - [FreeBSD `getsockopt`]
 ///  - [FreeBSD `tcp`]
 ///  - [NetBSD `getsockopt`]
 ///  - [NetBSD `tcp`]
 ///  - [OpenBSD `getsockopt`]
 ///  - [OpenBSD `tcp`]
 ///  - [DragonFly BSD `getsockopt`]
 ///  - [DragonFly BSD `tcp`]
 ///  - [illumos `getsockopt`]
 ///  - [illumos `tcp`]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `netinet/tcp.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_tcp.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `tcp`]: https://man7.org/linux/man-pages/man7/tcp.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `IPPROTO_TCP` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-tcp-socket-options
 /// [Apple `getsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getsockopt.2.html
 /// [Apple `tcp`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/tcp.4.auto.html
 /// [FreeBSD `getsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=getsockopt&sektion=2
 /// [FreeBSD `tcp`]: https://man.freebsd.org/cgi/man.cgi?query=tcp&sektion=4
 /// [NetBSD `getsockopt`]: https://man.netbsd.org/getsockopt.2
 /// [NetBSD `tcp`]: https://man.netbsd.org/tcp.4
 /// [OpenBSD `getsockopt`]: https://man.openbsd.org/getsockopt.2
 /// [OpenBSD `tcp`]: https://man.openbsd.org/tcp.4
 /// [DragonFly BSD `getsockopt`]: https://man.dragonflybsd.org/?command=getsockopt&section=2
 /// [DragonFly BSD `tcp`]: https://man.dragonflybsd.org/?command=tcp&section=4
 /// [illumos `getsockopt`]: https://illumos.org/man/3SOCKET/getsockopt
 /// [illumos `tcp`]: https://illumos.org/man/4P/tcp
 #[inline]
 #[doc(alias = "TCP_NODELAY")]
 pub fn get_tcp_nodelay<Fd: AsFd>(fd: Fd) -> io::Result<bool> {
     backend::net::syscalls::sockopt::get_tcp_nodelay(fd.as_fd())
 }

 /// `setsockopt(fd, IPPROTO_TCP, TCP_KEEPCNT, count)`
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `netinet/tcp.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `tcp`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `IPPROTO_TCP` options]
 ///  - [Apple `getsockopt`]
 ///  - [Apple `tcp`]
 ///  - [FreeBSD `getsockopt`]
 ///  - [FreeBSD `tcp`]
 ///  - [NetBSD `getsockopt`]
 ///  - [NetBSD `tcp`]
 ///  - [DragonFly BSD `getsockopt`]
 ///  - [DragonFly BSD `tcp`]
 ///  - [illumos `getsockopt`]
 ///  - [illumos `tcp`]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `netinet/tcp.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_tcp.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `tcp`]: https://man7.org/linux/man-pages/man7/tcp.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `IPPROTO_TCP` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-tcp-socket-options
 /// [Apple `getsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getsockopt.2.html
 /// [Apple `tcp`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/tcp.4.auto.html
 /// [FreeBSD `getsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=getsockopt&sektion=2
 /// [FreeBSD `tcp`]: https://man.freebsd.org/cgi/man.cgi?query=tcp&sektion=4
 /// [NetBSD `getsockopt`]: https://man.netbsd.org/getsockopt.2
 /// [NetBSD `tcp`]: https://man.netbsd.org/tcp.4
 /// [DragonFly BSD `getsockopt`]: https://man.dragonflybsd.org/?command=getsockopt&section=2
 /// [DragonFly BSD `tcp`]: https://man.dragonflybsd.org/?command=tcp&section=4
 /// [illumos `getsockopt`]: https://illumos.org/man/3SOCKET/getsockopt
 /// [illumos `tcp`]: https://illumos.org/man/4P/tcp
 #[inline]
 #[cfg(not(any(target_os = "openbsd", target_os = "haiku", target_os = "nto")))]
 #[doc(alias = "TCP_KEEPCNT")]
 pub fn set_tcp_keepcnt<Fd: AsFd>(fd: Fd, count: u32) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_tcp_keepcnt(fd.as_fd(), count)
 }

 /// `getsockopt(fd, IPPROTO_TCP, TCP_KEEPCNT)`
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `netinet/tcp.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `tcp`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `IPPROTO_TCP` options]
 ///  - [Apple `getsockopt`]
 ///  - [Apple `tcp`]
 ///  - [FreeBSD `getsockopt`]
 ///  - [FreeBSD `tcp`]
 ///  - [NetBSD `getsockopt`]
 ///  - [NetBSD `tcp`]
 ///  - [DragonFly BSD `getsockopt`]
 ///  - [DragonFly BSD `tcp`]
 ///  - [illumos `getsockopt`]
 ///  - [illumos `tcp`]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `netinet/tcp.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_tcp.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `tcp`]: https://man7.org/linux/man-pages/man7/tcp.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `IPPROTO_TCP` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-tcp-socket-options
 /// [Apple `getsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getsockopt.2.html
 /// [Apple `tcp`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/tcp.4.auto.html
 /// [FreeBSD `getsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=getsockopt&sektion=2
 /// [FreeBSD `tcp`]: https://man.freebsd.org/cgi/man.cgi?query=tcp&sektion=4
 /// [NetBSD `getsockopt`]: https://man.netbsd.org/getsockopt.2
 /// [NetBSD `tcp`]: https://man.netbsd.org/tcp.4
 /// [DragonFly BSD `getsockopt`]: https://man.dragonflybsd.org/?command=getsockopt&section=2
 /// [DragonFly BSD `tcp`]: https://man.dragonflybsd.org/?command=tcp&section=4
 /// [illumos `getsockopt`]: https://illumos.org/man/3SOCKET/getsockopt
 /// [illumos `tcp`]: https://illumos.org/man/4P/tcp
 #[inline]
 #[cfg(not(any(target_os = "openbsd", target_os = "haiku", target_os = "nto")))]
 #[doc(alias = "TCP_KEEPCNT")]
 pub fn get_tcp_keepcnt<Fd: AsFd>(fd: Fd) -> io::Result<u32> {
     backend::net::syscalls::sockopt::get_tcp_keepcnt(fd.as_fd())
 }

 /// `setsockopt(fd, IPPROTO_TCP, TCP_KEEPIDLE, duration)`
 ///
 /// `TCP_KEEPALIVE` on Apple platforms.
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `netinet/tcp.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `tcp`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `IPPROTO_TCP` options]
 ///  - [Apple `getsockopt`]
 ///  - [Apple `tcp`]
 ///  - [FreeBSD `getsockopt`]
 ///  - [FreeBSD `tcp`]
 ///  - [NetBSD `getsockopt`]
 ///  - [NetBSD `tcp`]
 ///  - [DragonFly BSD `getsockopt`]
 ///  - [DragonFly BSD `tcp`]
 ///  - [illumos `getsockopt`]
 ///  - [illumos `tcp`]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `netinet/tcp.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_tcp.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `tcp`]: https://man7.org/linux/man-pages/man7/tcp.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `IPPROTO_TCP` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-tcp-socket-options
 /// [Apple `getsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getsockopt.2.html
 /// [Apple `tcp`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/tcp.4.auto.html
 /// [FreeBSD `getsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=getsockopt&sektion=2
 /// [FreeBSD `tcp`]: https://man.freebsd.org/cgi/man.cgi?query=tcp&sektion=4
 /// [NetBSD `getsockopt`]: https://man.netbsd.org/getsockopt.2
 /// [NetBSD `tcp`]: https://man.netbsd.org/tcp.4
 /// [DragonFly BSD `getsockopt`]: https://man.dragonflybsd.org/?command=getsockopt&section=2
 /// [DragonFly BSD `tcp`]: https://man.dragonflybsd.org/?command=tcp&section=4
 /// [illumos `getsockopt`]: https://illumos.org/man/3SOCKET/getsockopt
 /// [illumos `tcp`]: https://illumos.org/man/4P/tcp
 #[inline]
 #[cfg(not(any(target_os = "openbsd", target_os = "haiku", target_os = "nto")))]
 #[doc(alias = "TCP_KEEPIDLE")]
 pub fn set_tcp_keepidle<Fd: AsFd>(fd: Fd, duration: Duration) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_tcp_keepidle(fd.as_fd(), duration)
 }

 /// `getsockopt(fd, IPPROTO_TCP, TCP_KEEPIDLE)`
 ///
 /// `TCP_KEEPALIVE` on Apple platforms.
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `netinet/tcp.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `tcp`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `IPPROTO_TCP` options]
 ///  - [Apple `getsockopt`]
 ///  - [Apple `tcp`]
 ///  - [FreeBSD `getsockopt`]
 ///  - [FreeBSD `tcp`]
 ///  - [NetBSD `getsockopt`]
 ///  - [NetBSD `tcp`]
 ///  - [DragonFly BSD `getsockopt`]
 ///  - [DragonFly BSD `tcp`]
 ///  - [illumos `getsockopt`]
 ///  - [illumos `tcp`]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `netinet/tcp.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_tcp.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `tcp`]: https://man7.org/linux/man-pages/man7/tcp.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `IPPROTO_TCP` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-tcp-socket-options
 /// [Apple `getsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getsockopt.2.html
 /// [Apple `tcp`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/tcp.4.auto.html
 /// [FreeBSD `getsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=getsockopt&sektion=2
 /// [FreeBSD `tcp`]: https://man.freebsd.org/cgi/man.cgi?query=tcp&sektion=4
 /// [NetBSD `getsockopt`]: https://man.netbsd.org/getsockopt.2
 /// [NetBSD `tcp`]: https://man.netbsd.org/tcp.4
 /// [DragonFly BSD `getsockopt`]: https://man.dragonflybsd.org/?command=getsockopt&section=2
 /// [DragonFly BSD `tcp`]: https://man.dragonflybsd.org/?command=tcp&section=4
 /// [illumos `getsockopt`]: https://illumos.org/man/3SOCKET/getsockopt
 /// [illumos `tcp`]: https://illumos.org/man/4P/tcp
 #[inline]
 #[cfg(not(any(target_os = "openbsd", target_os = "haiku", target_os = "nto")))]
 #[doc(alias = "TCP_KEEPIDLE")]
 pub fn get_tcp_keepidle<Fd: AsFd>(fd: Fd) -> io::Result<Duration> {
     backend::net::syscalls::sockopt::get_tcp_keepidle(fd.as_fd())
 }

 /// `setsockopt(fd, IPPROTO_TCP, TCP_KEEPINTVL, duration)`
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `netinet/tcp.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `tcp`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `IPPROTO_TCP` options]
 ///  - [Apple `getsockopt`]
 ///  - [Apple `tcp`]
 ///  - [FreeBSD `getsockopt`]
 ///  - [FreeBSD `tcp`]
 ///  - [NetBSD `getsockopt`]
 ///  - [NetBSD `tcp`]
 ///  - [DragonFly BSD `getsockopt`]
 ///  - [DragonFly BSD `tcp`]
 ///  - [illumos `getsockopt`]
 ///  - [illumos `tcp`]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `netinet/tcp.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_tcp.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `tcp`]: https://man7.org/linux/man-pages/man7/tcp.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `IPPROTO_TCP` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-tcp-socket-options
 /// [Apple `getsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getsockopt.2.html
 /// [Apple `tcp`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/tcp.4.auto.html
 /// [FreeBSD `getsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=getsockopt&sektion=2
 /// [FreeBSD `tcp`]: https://man.freebsd.org/cgi/man.cgi?query=tcp&sektion=4
 /// [NetBSD `getsockopt`]: https://man.netbsd.org/getsockopt.2
 /// [NetBSD `tcp`]: https://man.netbsd.org/tcp.4
 /// [DragonFly BSD `getsockopt`]: https://man.dragonflybsd.org/?command=getsockopt&section=2
 /// [DragonFly BSD `tcp`]: https://man.dragonflybsd.org/?command=tcp&section=4
 /// [illumos `getsockopt`]: https://illumos.org/man/3SOCKET/getsockopt
 /// [illumos `tcp`]: https://illumos.org/man/4P/tcp
 #[inline]
 #[cfg(not(any(target_os = "openbsd", target_os = "haiku", target_os = "nto")))]
 #[doc(alias = "TCP_KEEPINTVL")]
 pub fn set_tcp_keepintvl<Fd: AsFd>(fd: Fd, duration: Duration) -> io::Result<()> {
     backend::net::syscalls::sockopt::set_tcp_keepintvl(fd.as_fd(), duration)
 }

 /// `getsockopt(fd, IPPROTO_TCP, TCP_KEEPINTVL)`
 ///
 /// # References
 ///  - [POSIX `getsockopt`]
 ///  - [POSIX `netinet/tcp.h`]
 ///  - [Linux `getsockopt`]
 ///  - [Linux `tcp`]
 ///  - [Winsock2 `getsockopt`]
 ///  - [Winsock2 `IPPROTO_TCP` options]
 ///  - [Apple `getsockopt`]
 ///  - [Apple `tcp`]
 ///  - [FreeBSD `getsockopt`]
 ///  - [FreeBSD `tcp`]
 ///  - [NetBSD `getsockopt`]
 ///  - [NetBSD `tcp`]
 ///  - [DragonFly BSD `getsockopt`]
 ///  - [DragonFly BSD `tcp`]
 ///  - [illumos `getsockopt`]
 ///  - [illumos `tcp`]
 ///
 /// [POSIX `getsockopt`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html
 /// [POSIX `netinet/tcp.h`]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netinet_tcp.h.html
 /// [Linux `getsockopt`]: https://man7.org/linux/man-pages/man2/getsockopt.2.html
 /// [Linux `tcp`]: https://man7.org/linux/man-pages/man7/tcp.7.html
 /// [Winsock2 `getsockopt`]: https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockopt
 /// [Winsock2 `IPPROTO_TCP` options]: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-tcp-socket-options
 /// [Apple `getsockopt`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getsockopt.2.html
 /// [Apple `tcp`]: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/man/man4/tcp.4.auto.html
 /// [FreeBSD `getsockopt`]: https://man.freebsd.org/cgi/man.cgi?query=getsockopt&sektion=2
 /// [FreeBSD `tcp`]: https://man.freebsd.org/cgi/man.cgi?query=tcp&sektion=4
 /// [NetBSD `getsockopt`]: https://man.netbsd.org/getsockopt.2
 /// [NetBSD `tcp`]: https://man.netbsd.org/tcp.4
 /// [DragonFly BSD `getsockopt`]: https://man.dragonflybsd.org/?command=getsockopt&section=2
 /// [DragonFly BSD `tcp`]: https://man.dragonflybsd.org/?command=tcp&section=4
 /// [illumos `getsockopt`]: https://illumos.org/man/3SOCKET/getsockopt
 /// [illumos `tcp`]: https://illumos.org/man/4P/tcp
 #[inline]
 #[cfg(not(any(target_os = "openbsd", target_os = "haiku", target_os = "nto")))]
 #[doc(alias = "TCP_KEEPINTVL")]
 pub fn get_tcp_keepintvl<Fd: AsFd>(fd: Fd) -> io::Result<Duration> {
     backend::net::syscalls::sockopt::get_tcp_keepintvl(fd.as_fd())
 }

 #[test]
 fn test_sizes() {
     use c::c_int;

     // Backend code needs to cast these to `c_int` so make sure that cast
     // isn't lossy.
     assert_eq_size!(Timeout, c_int);
 }