autodiscover-rs implements a simple algorithm to detect peers on an IP network, connects to them, and calls back with the connected stream. The algorthm supports both UDP broadcast and multicasting.
Cargo.toml
autodiscover-rs = "0.1.0"
In your app:
``` use std::net::{TcpListener, TcpStream}; use std::thread;
use autodiscoverrs::{self, Method}; use envlogger;
fn handleclient(stream: std::io::Result
fn main() -> std::io::Result<()> { envlogger::init(); // make sure to bind before announcing ready let listener = TcpListener::bind(":::0")?; // get the port we were bound too; note that the trailing :0 above gives us a random unused port let socket = listener.localaddr()?; thread::spawn(move || { // this function blocks forever; running it a seperate thread autodiscoverrs::run(&socket, Method::Multicast("[ff0e::1]:1337".parse().unwrap()), |s| { // change this to task::spawn if using asyncstd or tokio thread::spawn(|| handleclient(s)); }).unwrap(); }); let mut incoming = listener.incoming(); while let Some(stream) = incoming.next() { // if you are using an async library, such as asyncstd or tokio, you can convert the stream to the // appropriate type before using task::spawn from your library of choice. thread::spawn(|| handle_client(stream)); } Ok(()) } ```
The algorithm for peer discovery is to: - Send a message to the broadcast/multicast address with the configured 'listen address' compressed to a 6 byte (IPv4) or 18 byte (IPv6) packet - Start listening for new messages on the broadcast/multicast address; when one is recv., connect to it and run the callback
This has a few gotchas: - If a broadcast packet goes missing, some connections won't be made
The IP address we are broadcasting is of the form:
IPv4:
buff[0..4].clone_from_slice(&addr.ip().octets());
buff[4..6].clone_from_slice(&addr.port().to_be_bytes());
IPv6:
buff[0..16].clone_from_slice(&addr.ip().octets());
buff[16..18].clone_from_slice(&addr.port().to_be_bytes());