l3_extract

extract layer 4 connection from layer 3

This crate aim to provide a way to allow users manipulate TCP and UDP which is obtained from layer-3 protocol packet, like normal async TCP stream and async UDP socket, but with complete based mode.

This crate is based on smoltcp, which is a single threaded, serial and event driven userspace TCP network stack crate, but this crate allows users use TcpStream, UdpSocket and others concurrently.

Notes:

This crate try to put ease of use first, then performance, so it absolutely slower than kernel TCP network stack, also may slower than use smoltcp with hand write event loop.

Examples:

use std::future::ready;
use std::net::Ipv4Addr;
use std::os::fd::OwnedFd;
use std::str::FromStr;
use futures_util::{AsyncRead, AsyncWrite, StreamExt, TryStreamExt};
use futures_util::stream::FuturesUnordered;
use futures_util::task::SpawnExt;
use l3_extract::{EventGenerator, Ipv4Cidr, TcpStack};
use futures_timer::Delay;

#[derive(Default)]
struct MyTimer;

impl Timer for MyTimer {
    async fn sleep(&mut self, dur: Duration) {
        Delay::new(dur).await
    }
}

async fn run() {
    let connection = create_layer3_connection();
    let (mut tcp_stack, event_generator, mut tcp_acceptor, mut udp_acceptor) = TcpStack::builder()
        .ipv4_addr(Ipv4Cidr::from_str("192.168.100.10/24").unwrap())
        .ipv4_gateway(Ipv4Addr::new(192, 168, 100, 1))
        .build()
        .unwrap();
    drive_tcp_stack(tcp_stack, connection);
    let mut futs = FuturesUnordered::new();
    futs.spawn(async {
        handle_events(event_generator).await
    }).unwrap();
    futs.spawn(async {
        let tcp_stream = tcp_acceptor.try_next().await.unwrap().unwrap();
        // do something with tcp_stream
    }).unwrap();
    futs.spawn(async {
        let udp_socket = udp_acceptor.try_next().await.unwrap().unwrap();
        // do something with udp_socket
    }).unwrap();

    futs.for_each(|_| ready(())).await;
}

async fn create_layer3_connection() -> OwnedFd {
    // create a layer3 connection
}

async fn handle_events(event_generator: EventGenerator) {
    // handle events
}

async fn drive_tcp_stack(tcp_stack: TcpStack, fd: OwnedFd) {
    // drive tcp stack on your way, such as spawn a background thread
}