SSDP sample code

client.java

public static void main(String[] args) throws IOException {
    System.setProperty("java.net.preferIPv4Stack", "true");
    int PORT = 1900;
    String MULTICAST_GROUP_IPV4 = "239.172.243.75";
    InetAddress LOCALHOST = Inet4Address.getByName("127.0.0.1");
    byte[] requestBytes = SEARCH_MESSAGE;
    MulticastSocket socket = new MulticastSocket(new InetSocketAddress(LOCALHOST, 0));
    socket.setLoopbackMode(false);
    socket.setInterface(LOCALHOST);
    DatagramPacket packet = new DatagramPacket(
        requestBytes, requestBytes.length,
        new InetSocketAddress(
            InetAddress.getByName(MULTICAST_GROUP_IPV4), PORT));
    try {
        socket.send(packet);
    }
    catch (Exception e) {
        System.err.println(e.getMessage());
    }
}

client.py

import socket
from server import PORT, MULTICAST_GROUP_IPV4, LOCALHOST

client = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
client.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
client.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_IF, socket.inet_aton(LOCALHOST))

search_message = (
    "M-SEARCH * HTTP/1.1\r\n" +
    "MAN: \"ssdp:discover\"\r\n" +
    "MX: 1\r\n" +
    "ST: fusion_idea:debug\r\n" +
    "HOST: 127.0.0.1:" + str(PORT) + "\r\n\r\n"
)
client.sendto(search_message.encode(), (MULTICAST_GROUP_IPV4, PORT))

server.py

import socket
import struct

PORT = 1900
MULTICAST_GROUP_IPV4 = "239.172.243.75"
LOCALHOST = "127.0.0.1"

if __name__ == "__main__":
    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
    sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    sock.bind(("", PORT))
    # req = struct.pack("=4s4s", socket.inet_aton(MULTICAST_GROUP_IPV4), socket.inet_aton("0.0.0.0"))
    req = struct.pack("=4s4s", socket.inet_aton(MULTICAST_GROUP_IPV4), socket.inet_aton(LOCALHOST))
    sock.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, req)

    print("Bound to IP address: %s, Port: %d" % sock.getsockname())

    while True:
        data, addr = sock.recvfrom(1024)
        print("Received data from %s: %s" % (addr, data))