import md5 import re from django.conf import settings from django import http from django.core.mail import mail_managers from django.utils.http import urlquote from django.core import urlresolvers class CommonMiddleware(object): """ "Common" middleware for taking care of some basic operations: - Forbids access to User-Agents in settings.DISALLOWED_USER_AGENTS - URL rewriting: Based on the APPEND_SLASH and PREPEND_WWW settings, this middleware appends missing slashes and/or prepends missing "www."s. - If APPEND_SLASH is set and the initial URL doesn't end with a slash, and it is not found in urlpatterns, a new URL is formed by appending a slash at the end. If this new URL is found in urlpatterns, then an HTTP-redirect is returned to this new URL; otherwise the initial URL is processed as usual. - ETags: If the USE_ETAGS setting is set, ETags will be calculated from the entire page content and Not Modified responses will be returned appropriately. """ def process_request(self, request): """ Check for denied User-Agents and rewrite the URL based on settings.APPEND_SLASH and settings.PREPEND_WWW """ # Check for denied User-Agents if 'HTTP_USER_AGENT' in request.META: for user_agent_regex in settings.DISALLOWED_USER_AGENTS: if user_agent_regex.search(request.META['HTTP_USER_AGENT']): return http.HttpResponseForbidden('

Forbidden

') # Check for a redirect based on settings.APPEND_SLASH # and settings.PREPEND_WWW host = request.get_host() old_url = [host, request.path] new_url = old_url[:] if (settings.PREPEND_WWW and old_url[0] and not old_url[0].startswith('www.')): new_url[0] = 'www.' + old_url[0] # Append a slash if APPEND_SLASH is set and the URL doesn't have a # trailing slash and there is no pattern for the current path if settings.APPEND_SLASH and (not old_url[1].endswith('/')): try: urlresolvers.resolve(request.path) except urlresolvers.Resolver404: new_url[1] = new_url[1] + '/' if settings.DEBUG and request.method == 'POST': raise RuntimeError, ("" "You called this URL via POST, but the URL doesn't end " "in a slash and you have APPEND_SLASH set. Django can't " "redirect to the slash URL while maintaining POST data. " "Change your form to point to %s%s (note the trailing " "slash), or set APPEND_SLASH=False in your Django " "settings.") % (new_url[0], new_url[1]) if new_url != old_url: # Redirect if the target url exists 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 def process_response(self, request, response): "Check for a flat page (for 404s) and calculate the Etag, if needed." if response.status_code == 404: if settings.SEND_BROKEN_LINK_EMAILS: # If the referrer was from an internal link or a non-search-engine site, # send a note to the managers. domain = request.get_host() referer = request.META.get('HTTP_REFERER', None) is_internal = _is_internal_request(domain, referer) path = request.get_full_path() if referer and not _is_ignorable_404(path) and (is_internal or '?' not in referer): ua = request.META.get('HTTP_USER_AGENT', '') ip = request.META.get('REMOTE_ADDR', '') mail_managers("Broken %slink on %s" % ((is_internal and 'INTERNAL ' or ''), domain), "Referrer: %s\nRequested URL: %s\nUser agent: %s\nIP address: %s\n" \ % (referer, request.get_full_path(), ua, ip)) return response # Use ETags, if requested. if settings.USE_ETAGS: if response.has_header('ETag'): etag = response['ETag'] else: etag = md5.new(response.content).hexdigest() if response.status_code >= 200 and response.status_code < 300 and request.META.get('HTTP_IF_NONE_MATCH') == etag: cookies = response.cookies response = http.HttpResponseNotModified() response.cookies = cookies else: response['ETag'] = etag return response def _is_ignorable_404(uri): "Returns True if a 404 at the given URL *shouldn't* notify the site managers" for start in settings.IGNORABLE_404_STARTS: if uri.startswith(start): return True for end in settings.IGNORABLE_404_ENDS: if uri.endswith(end): return True return False def _is_internal_request(domain, referer): "Return true if the referring URL is the same domain as the current request" # Different subdomains are treated as different domains. return referer is not None and re.match("^https?://%s/" % re.escape(domain), referer)