A simple threaded caching HTTP proxy

proxy.py

#!/usr/bin/python

"""
A simple threaded caching HTTP proxy.
Hereward Cooper <[email protected]>
v0.1
"""

LISTENPORT  = 8000
LISTENINT   = '127.0.0.1'
REMOTEHOST  = 'http://remote.server:80'
CACHEDIR    = './cache'
LOGFILE     = './proxy.log'

import BaseHTTPServer
from BaseHTTPServer import HTTPServer, BaseHTTPRequestHandler
import hashlib
import os
import urllib2
from SocketServer import ThreadingMixIn
import threading
import sys

class CacheHandler(BaseHTTPServer.BaseHTTPRequestHandler):
	def do_GET(self):
		'''Hash the query'''
	 	m = hashlib.md5()
	 	m.update(self.path)
	 	hexname = m.hexdigest()

	 	'''Spread cache across subdirectories (for performance)'''
	 	path = CACHEDIR + "/" + hexname[:2]
	  	fullpath = path + "/" + hexname

	 	'''Hit or miss the cache'''
	 	if os.path.exists(fullpath):
		 	open(LOGFILE, "a").write("%s - - [CACHE HIT] [%s] %s\n" %
		 		(self.address_string(),
		 		self.log_date_time_string(),
		 		self.path))
		 	data = open(fullpath).readlines()
	 	else:
			if not os.path.exists(path):
				os.makedirs(path)
	 		open(LOGFILE, "a").write("%s - - [CACHE MISS] [%s] %s\n" %
		 		(self.address_string(),
		 		self.log_date_time_string(),
		 		self.path))
			data = urllib2.urlopen(REMOTEHOST + self.path).readlines()
			open(fullpath, 'wb').writelines(data)
	
		'''Return HTTP headers and data'''
		self.send_response(200)
		self.end_headers()
		self.wfile.writelines(data)

	def log_message(self, format, *args):
		""" Disable the default logging setup as we use our own"""
		return

class ThreadedHTTPServer(ThreadingMixIn, HTTPServer):
	"""Handle requests in a separate thread"""

def run():
	server_address = (LISTENINT, LISTENPORT)
	httpd = ThreadedHTTPServer(server_address, CacheHandler)
	print 'Starting proxy on port ' + str(LISTENPORT) + ', use <Ctrl-C> to stop'
	print 'Log file: ' + LOGFILE
	print 'Cache directory: ' + CACHEDIR
	httpd.serve_forever()

if __name__ == '__main__':
	run()