chatserve

i#!/usr/bin/env python

#Name: Alan macabuhay
#Date: 10/16/18
#Description: A simple python client-server program
#References: (1)http://docs.python.org/2/howto/sockets.html
#			 (2)http://docs.python.org/3/library/socket.html#example
#            (3)https://stackoverflow.com/questions/27651772/check-length-of-user-input
#			 (4)https://stackoverflow.com/questions/1112343/how-do-i-capture-sigint-in-python

import signal
import sys
from socket import *


#function to handle SIGINT. (4)
def signal_handler(sig, frame):
	print "Server exiting with Ctrl+C"
	sys.exit(0)

#captures SIGINT. (4)
signal.signal(signal.SIGINT, signal_handler)

#function that handles the chatting
def chat(clientSocket, clientName, serverName):
	
	#continue until quitting. (2)
	while 1:
		#receive msg from client
		recvData = clientSocket.recv(501)[0:-1]
	
		if recvData == "":
			print "Ending connection with {}".format(clientName)
			print "waiting for new connection..."
			break	

		#print received msg
		print "{}> {}".format(clientName, recvData)

		sendData = ""

		#get msg to send to client and check length. (3)	
		while 1:
			sendData = raw_input("{}> ".format(serverName))

			if len(sendData) > 500:
				print "Message must not exceed 500 characters"

			#prompts user if they press enter without typing a msg.
			#can still send a blank msg if len(sendData) > 0
			elif len(sendData) == 0:
				print "Please enter a message."

			else:
				break

		if sendData == "\quit":
			print "Ending connection with {}".format(clientName)
			print "waiting for new connection..."
			break

		#send msg to client
		clientSocket.send(sendData)

#function that handles exchanging of handle between server and client
def handshake(clientSocket, serverName):
	name = clientSocket.recv(1024)
	clientSocket.send(serverName)

	return name

#function that creates socket, binds it, and listens for connections
def socketHelper(portNum):
	#create TCP socket. (1)
	sock = socket(AF_INET, SOCK_STREAM)

	#bind and listen for up to 5 connections. (1)
	sock.bind(('', int(portNum)))
	sock.listen(5)

	return sock

#function to get server handle from user
def getServerHandle():

	server = ""
	while 1:
		server = raw_input("Enter a handle for the server (max 10 characters): ")
		
		if len(server) <= 10 and len(server) > 0:
			break

	return server

#main function
if __name__ == "__main__":
	#check arguments are correct
	if len(sys.argv) != 2:
		print "Error: Missing argument(s)"
		exit(1)

	#get port number 
	portNum = sys.argv[1]

	#create socket
	serverSocket = socketHelper(portNum)

	#get server's handle name
	serverName = getServerHandle()

	print "{} now waiting for messages...".format(serverName)

	#keep talking with client
	while 1:
		#accept connection to client socket. (1)
		(clientSocket, address) = serverSocket.accept()

		#exchange handle names between client and server
		clientName = handshake(clientSocket, serverName)

		print "Now connected with {} on {}".format(clientName, address)
	
		#start chat
		chat(clientSocket, clientName, serverName)

		#close socket
		clientSocket.close()