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//! Low-level Linux network device access
//!
//! The methods in this module take a socket's file descriptor to communicate with
//! the kernel in their ioctl call:
//! - glibc uses an `AF_UNIX`, `AF_INET`, or `AF_INET6` socket.
//! The address family itself does not matter and glibc tries the next address family if socket creation with one fails.
//! - Android (bionic) uses an `AF_INET` socket.
//! - Both create the socket with `SOCK_DGRAM|SOCK_CLOEXEC` type/flag.
//! - The [man-pages] specify, that the ioctl calls "can be used on any socket's file descriptor regardless of the
//! family or type".
//!
//! # References
//! - [Linux]
//!
//! [man-pages]: https://man7.org/linux/man-pages/man7/netdevice.7.html
//! [Linux]: https://man7.org/linux/man-pages/man7/netdevice.7.html

#[cfg(feature = "alloc")]
use crate::alloc::string::String;
use crate::fd::AsFd;
use crate::io;

/// `ioctl(fd, SIOCGIFINDEX, ifreq)`—Returns the interface index for a given name.
///
/// See the [module-level documentation] for information about `fd` usage.
///
/// # References
///  - [Linux]
///
/// [module-level documentation]: self
/// [Linux]: https://man7.org/linux/man-pages/man7/netdevice.7.html
#[inline]
#[doc(alias = "SIOCGIFINDEX")]
pub fn name_to_index(fd: impl AsFd, if_name: &str) -> io::Result<u32> {
    crate::backend::net::netdevice::name_to_index(fd, if_name)
}

/// `ioctl(fd, SIOCGIFNAME, ifreq)`—Returns the interface name for a given index.
///
/// See the [module-level documentation] for information about `fd` usage.
///
/// # References
///  - [Linux]
///
/// [module-level documentation]: self
/// [Linux]: https://man7.org/linux/man-pages/man7/netdevice.7.html
#[inline]
#[doc(alias = "SIOCGIFNAME")]
#[cfg(feature = "alloc")]
pub fn index_to_name(fd: impl AsFd, index: u32) -> io::Result<String> {
    crate::backend::net::netdevice::index_to_name(fd, index)
}

#[cfg(test)]
mod tests {
    use crate::backend::net::netdevice::{index_to_name, name_to_index};
    use crate::net::{AddressFamily, SocketFlags, SocketType};

    #[test]
    fn test_name_to_index() {
        let fd = crate::net::socket_with(
            AddressFamily::INET,
            SocketType::DGRAM,
            SocketFlags::CLOEXEC,
            None,
        )
        .unwrap();

        let loopback_index = std::fs::read_to_string("/sys/class/net/lo/ifindex")
            .unwrap()
            .as_str()
            .split_at(1)
            .0
            .parse::<u32>()
            .unwrap();
        assert_eq!(Ok(loopback_index), name_to_index(fd, "lo"));
    }

    #[test]
    #[cfg(feature = "alloc")]
    fn test_index_to_name() {
        let fd = crate::net::socket_with(
            AddressFamily::INET,
            SocketType::DGRAM,
            SocketFlags::CLOEXEC,
            None,
        )
        .unwrap();

        let loopback_index = std::fs::read_to_string("/sys/class/net/lo/ifindex")
            .unwrap()
            .as_str()
            .split_at(1)
            .0
            .parse::<u32>()
            .unwrap();
        assert_eq!(Ok("lo".to_owned()), index_to_name(fd, loopback_index));
    }
}