2 releases
0.1.1 | Jul 8, 2020 |
---|---|
0.1.0 | Jul 4, 2020 |
#19 in #multicast
11KB
103 lines
autodiscover-rs
autodiscover-rs implements a simple algorithm to detect peers on an IP network, connects to them, and calls back with the connected stream. The algorithm supports both UDP broadcast and multicasting.
Usage
Cargo.toml
autodiscover-rs = "0.1.0"
In your app:
use std::net::{TcpListener, TcpStream};
use std::thread;
use autodiscover_rs::{self, Method};
use env_logger;
fn handle_client(stream: std::io::Result<TcpStream>) {
println!("Got a connection from {:?}", stream.unwrap().peer_addr());
}
fn main() -> std::io::Result<()> {
env_logger::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.local_addr()?;
thread::spawn(move || {
// this function blocks forever; running it a seperate thread
autodiscover_rs::run(&socket, Method::Multicast("[ff0e::1]:1337".parse().unwrap()), |s| {
// change this to task::spawn if using async_std or tokio
thread::spawn(|| handle_client(s));
}).unwrap();
});
let mut incoming = listener.incoming();
while let Some(stream) = incoming.next() {
// if you are using an async library, such as async_std 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(())
}
Notes
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
Packet format
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());
TODO
- Provide features for async frameworks (such as async_std and tokio)
- Figure out some way of testing this
- Provides some mechanism to stop the thread listening for discovery
Dependencies
~310–560KB