netdev 0.41.0

Cross-platform library for enumerating network interfaces with metadata.
Documentation 
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pub mod flags;
pub mod interface;
pub mod netlink;
pub mod state;
pub mod sysfs;
pub mod types;

use dlopen2::raw::Library;
use once_cell::sync::OnceCell;

pub fn get_libc_ifaddrs() -> Option<(
    unsafe extern "C" fn(*mut *mut libc::ifaddrs) -> libc::c_int,
    unsafe extern "C" fn(*mut libc::ifaddrs),
)> {
    match (get_getifaddrs(), get_freeifaddrs()) {
        (Some(a), Some(b)) => Some((a, b)),
        _ => None,
    }
}

fn load_symbol<T>(sym: &'static str) -> Option<T> {
    const LIB_NAME: &str = "libc.so";
    static LIBC: OnceCell<Option<Library>> = OnceCell::new();

    let lib = LIBC.get_or_init(|| Library::open(LIB_NAME).ok()).as_ref()?;

    match unsafe { lib.symbol::<T>(sym) } {
        Ok(val) => Some(val),
        Err(_) => None,
    }
}

fn get_getifaddrs() -> Option<unsafe extern "C" fn(*mut *mut libc::ifaddrs) -> libc::c_int> {
    static INSTANCE: OnceCell<
        Option<unsafe extern "C" fn(*mut *mut libc::ifaddrs) -> libc::c_int>,
    > = OnceCell::new();

    *INSTANCE.get_or_init(|| load_symbol("getifaddrs"))
}

fn get_freeifaddrs() -> Option<unsafe extern "C" fn(*mut libc::ifaddrs)> {
    static INSTANCE: OnceCell<Option<unsafe extern "C" fn(*mut libc::ifaddrs)>> = OnceCell::new();

    *INSTANCE.get_or_init(|| load_symbol("freeifaddrs"))
}