UDPServer.py | Python Fiddle

# ----------------------------------------------------------------------------------------------------------------------
# Phase 1 Project, UDPServer.py
# Written by Richard Douglas and Mounika Gannu
# for 16.483/583.201 - Network Design: Principles, Protocols, and Applications at UMass Lowell
# February 6, 2015
#
# Credits to "Computer Networking, A Top Down Approach, 6th Ed." by Kurose and Ross for Python 2 code in Chapter 2,
# as well as to Jeremy Plante for finding compatibility issues between Python 2 and Python 3 code.
# ----------------------------------------------------------------------------------------------------------------------

from socket import *  # this line allows the creation of sockets
serverPort = 12000  # communication will be on port 12000
serverSocket = socket(AF_INET, SOCK_DGRAM)
# creates a server socket. AF_INET indicates the network is using IPv4,
# SOCK_DGRAM indicates that the socket will be a UDP socket

serverSocket.bind(('', serverPort))
# assigns port 12000 to the server socket. All packets sent to port 12000 of the
# server's IP address will be sent to the server's socket.

filename = "ImageStorage.png"
fileIn = open(filename, 'w+b')

print "The server is ready to receive"  # prints the statement to screen
while 1:  # begins an infinite loop
    data, clientAddress = serverSocket.recvfrom(2048)
    # the server waits to receive data from the client. when data arrives, the method 'recvfrom' takes the 2048 bit
    # buffer input and puts the incoming message into the variable 'message' and combines the client's IP address and
    # client's port number into the variable 'clientAddress'.
		if not data:
            print "Finished receiving file.\n"
            fileIn = open(filename, 'rb')
            break
    fileIn = data(2048)
    
while 1:
    data = fileIn(2048)
    	if not data:
            print "Finished sending file.\n"
            break
    serverSocket.sendto(data, clientAddress)
    # the method 'sendto' attaches the clientAddress to the modifiedMessage and sends it to the process's socket,
    # 'serverSocket'

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