#!/usr/bin/env python3
import socket
import struct
import sys
from threading import Thread

MADDX = '225.100.100.100'
PORT = 6543
is_listening = False

def listen_messages(is_listening):
    print('Start listening...')
    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
    sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    sock.bind(('', PORT))
    mreq = struct.pack('4sl', socket.inet_aton(MADDX), socket.INADDR_ANY)
    sock.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, mreq)
    sock.settimeout(1)
    while is_listening():
        try:
            print(sock.recv(10240))
        except socket.timeout:
            pass
    print('Stop listening...')

sys.stdout.write('Enter your name: ')
name = sys.stdin.readline().strip()

listening_thread = Thread(target = listen_messages, args = (lambda: is_listening,))
is_listening = True
listening_thread.start()

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, 2)
while True:
    try:
        line = sys.stdin.readline().strip()
        sock.sendto('%s: %s' % (name, line), (MADDX, PORT))
    except KeyboardInterrupt:
        is_listening = False
        listening_thread.join()
        break