#!/usr/bin/python
import sys
import socket

if (len(sys.argv) > 2):
    remoteHost = sys.argv[1]
    remotePort = int(sys.argv[2])
    mySocket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    mySocket.bind(('',0))
    data = "Hello, world"
    remoteAddress = (remoteHost, remotePort)
    print "Sending '" + data + "' to", remoteAddress
    mySocket.sendto(data, remoteAddress)
    data, fromAddress = mySocket.recvfrom(65536)
    print "received '" + data + "' from ", fromAddress

elif (len(sys.argv) > 1):
    portNum = int(sys.argv[1])
    mySocket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    mySocket.bind(('',portNum))
    while 1:
        data, fromAddress = mySocket.recvfrom(65536)
        print "received '" + data + "' from", fromAddress
        print "sending reply"
        mySocket.sendto("reply", fromAddress)

else:
    print """Usage: %s listenPort
     or
       %s remoteHost remotePort""" % (sys.argv[0], sys.argv[0])