Function to build an asynchronous UDP stream that listens on a given local address

create_udp_stream.rs

fn create_udp_stream(addr: &str) -> io::Result<impl Stream<Item = Event, Error = io::Error>> {
    // IPv6 socket bound to the ANY address behave differently on different OS-es.
    // On Windows it will listen on IPv6 only, but on Linux it listens on both IPv4 and IPv6,
    // unless the IPv6 only flag is set.
    let socket = match addr
        .parse()
        .map_err(|e| io::Error::new(io::ErrorKind::InvalidInput, e))?
    {
        SocketAddr::V4(a) => UdpBuilder::new_v4()?.bind(a),
        SocketAddr::V6(a) => UdpBuilder::new_v6()?.only_v6(true)?.bind(a),
    }?;
    
    Ok(UdpFramed::new(
        UdpSocket::from_std(socket, &Handle::default())?,
        BeaconCodec,
    ).filter_map(|(item, addr)| {
        item.map(|packet| Event::HostFound(packet.host_int, addr))
    }))
}