udpspring-webfluxproject-reactorssdpreactor-netty

What is the most simple Reactor / Netty implementation for SSDP protocol?


I tried a lot of stuff with UdpClient, UdpServer, Spring Integration Ip module, wrapping DatagramSocket receive method to return a Flux, but I simply cannot receive any response from standard SSDP 239.255.255.250:1900.

Bonus points for also sending a packet to SSDP.


Solution

  • For those interested, here's a snippet. I was able to do it via Flux emitter instead of reactor-netty UDP classes.

    private static final String SSDP_IP = "239.255.255.250";
    private static final int SSDP_PORT = 1900;
    private static final int TIMEOUT = 5000;
    
    String request = new String("example");
    byte[] receiveData = new byte[1024];
    DatagramPacket sendPacket = new DatagramPacket(request.getBytes(),
                request.getBytes().length, InetAddress.getByName(SSDP_IP), SSDP_PORT);
    DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length,
                InetAddress.getLocalHost(), SSDP_PORT);
    
    Flux<String> response = Flux.create(emitter -> {
        try (DatagramSocket socket = new DatagramSocket()) {
            socket.setSoTimeout(TIMEOUT);
            socket.send(sendPacket);
            while (true) {
                socket.receive(receivePacket);
                emitter.next(receivePacket.getData());
            }
        } catch (SocketTimeoutException e) {
            emitter.complete();
        } catch (IOException e) {
            emitter.error(e);
        }
    })
        .map(mapper -> new String(receivePacket.getData(), 0, receivePacket.getLength()))