Simple UDP messaging tool in python to send cross-network messages to all other users. (Useful for people in multiple rooms at home!)

udp-messaging.py

#!/usr/bin/python
# UDP messaging
try:
	import tkMessageBox
	def displayMessage(message):
		tkMessageBox.showinfo("Message", message)
except ImportError:
	pass

def geti(array, item):
	try:
		return array[item]
	except Exception:
		return ""

import sys, socket, struct, getpass

UDP_IP="239.192.1.100"
UDP_PORT=9898

if sys.argv[0] == "udp-messaging.py":
	sys.argv.pop(0)
arg = geti(sys.argv, 0)
message = geti(sys.argv, 1)

sock = socket.socket( socket.AF_INET, socket.SOCK_DGRAM )

if arg == "server":
	intf = socket.gethostbyname(socket.gethostname())
	sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
	sock.setsockopt(socket.SOL_IP, socket.IP_MULTICAST_TTL, 20)
	sock.setsockopt(socket.SOL_IP, socket.IP_MULTICAST_LOOP, 1)
	sock.bind( ('', UDP_PORT ) )
	intf = socket.gethostbyname(socket.gethostname())
	sock.setsockopt(socket.SOL_IP, socket.IP_MULTICAST_IF, socket.inet_aton(intf))
	sock.setsockopt(socket.SOL_IP, socket.IP_ADD_MEMBERSHIP, socket.inet_aton(UDP_IP) + socket.inet_aton(intf))
	while True:
		data, addr = sock.recvfrom( 1024 )
		parts = data.split("|")
		displayMessage("Message from " + parts[0] + ":\n" + parts[1])
elif arg == "send":
	message = getpass.getuser() + '|' + message
	sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, 2)
	sock.sendto( message, (UDP_IP, UDP_PORT) )
else:
	print "Add server or send as commands"