Struct redbpf::SkLookup

pub struct SkLookup { /* fields omitted */ }

Type to work with sk_lookup BPF programs.

sk_lookup programs were introduced with Linux 5.9 and make it possible to programmatically perform socket lookup for new connections. This can be used, for instance, to listen on a large number of addresses and ports with a single socket.

In order to take effect, sk_lookup programs must be attached to a network namespace, which can be done with the [attach_sk_lookup] method.

Example

The userland code for listening on a port range could look something like this.

use std::net::TcpListener;
use std::os::unix::io::AsRawFd

use redbpf::{HashMap, SockMap};
use redbpf::load::Loader;

let mut listener = TcpListener::bind(("127.0.0.1", 12345)).unwrap();
let mut loaded = Loader::load(SK_LOOKUP).unwrap();

// Pass the listener fd to the BPF program
let mut socket = SockMap::new(loaded.map("socket")).unwrap();
socket.set(0, listener.as_raw_fd());

// Pass our port range to the BPF program
let mut ports = HashMap::<u16, u8>::new(loaded.map("ports")).unwrap();
for port in 80..430 {
    ports.set(port, 1);
}

// Attach the BPF program to the current process' network namespace
loaded
    .sk_lookup_mut("range_listener")
    .unwrap()
    .attach_sk_lookup("/proc/self/ns/net")
    .unwrap();

loop {
    let (client, _) = listener.accept().unwrap();
    let addr = client.local_addr().unwrap();
    println!("accepted new connection on `{}`", addr);
}

Implementations

impl SkLookup

pub fn attach_sk_lookup(&mut self, namespace: &str) -> Result<()>

Attach the sk_lookup to the given network namespace.

In most cases it should be attached to /proc/self/ns/net.

Trait Implementations

impl Drop for SkLookup

fn drop(&mut self)

Executes the destructor for this type.