套接字编程作业4：多线程Web代理服务器

from socket import *
import sys

if len(sys.argv) <= 1:
    print 'Usage : "python ProxyServer.py server_ip"\n[server_ip : It is the IP Address Of Proxy Server'
	sys.exit(2)
# Create a server socket, bind it to a port and start listening
tcpSerSock = socket(AF_INET, SOCK_STREAM)
# Fill in start.
# Fill in end.
while 1:
	# Strat receiving data from the client
	print 'Ready to serve...'
	tcpCliSock, addr = tcpSerSock.accept()
	print 'Received a connection from:', addr
	message = # Fill in start. # Fill in end.
	print message
	# Extract the filename from the given message
	print message.split()[1]
	filename = message.split()[1].partition("/")[2]
	print filename
	fileExist = "false"
	filetouse = "/" + filename
	print filetouse
	try:
		# Check wether the file exist in the cache
		f = open(filetouse[1:], "r")
		outputdata = f.readlines()
		fileExist = "true"
		# ProxyServer finds a cache hit and generates a response message
		tcpCliSock.send("HTTP/1.0 200 OK\r\n")
		tcpCliSock.send("Content-Type:text/html\r\n")
		# Fill in start.
		# Fill in end.
			print 'Read from cache'
	# Error handling for file not found in cache
	except IOError:
		if fileExist == "false":
			# Create a socket on the proxyserver
			c = # Fill in start. # Fill in end.
			hostn = filename.replace("www.","",1) 
			print hostn
			try:
				# Connect to the socket to port 80
				# Fill in start.
				# Fill in end.
				# Create a temporary file on this socket and ask port 80
				for the file requested by the client
				fileobj = c.makefile('r', 0)
				fileobj.write("GET "+"http://" + filename + " HTTP/1.0\n\n")
				# Read the response into buffer
				# Fill in start.
				# Fill in end.
				# Create a new file in the cache for the requested file.
				# Also send the response in the buffer to client socket and the corresponding file in the cache
				tmpFile = open("./" + filename,"wb")
				# Fill in start.
				# Fill in end.
			except:
				print "Illegal request"
		else:
			# HTTP response message for file not found
			# Fill in start.
			# Fill in end.
	# Close the client and the server sockets
	tcpCliSock.close()
# Fill in start.
# Fill in end.