Middleware to remove the WWW from the URL

from django.conf import settings
from django import http
from django.utils.http import urlquote
from django.core import urlresolvers

class UrlMiddleware(object):
	"""
	Middleware for removing the WWW from a URL if the users sets settings.REMOVE_WWW.
	Based on Django CommonMiddleware.
	"""
	
	def process_request(self, request):
	    host = request.get_host()
	    old_url = [host, request.path]
	    new_url = old_url[:]
	    
	    if (settings.REMOVE_WWW and old_url[0] and old_url[0].startswith('www.')):
	        new_url[0] = old_url[0][4:]
	    
	    if new_url != old_url:
	        try:
	            urlresolvers.resolve(new_url[1])
	        except urlresolvers.Resolver404:
	            pass
	        else:
	            if new_url[0]:
	                newurl = "%s://%s%s" % (
	                    request.is_secure() and 'https' or 'http',
	                    new_url[0], urlquote(new_url[1]))
	            else:
	                newurl = urlquote(new_url[1])
	            if request.GET:
	                newurl += '?' + request.GET.urlencode()
	            return http.HttpResponsePermanentRedirect(newurl)
	    return None