+
−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
+
−from django.utils.hashcompat import md5_constructor
+
−
+
−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('<h1>Forbidden</h1>')
+
−
+
−        # 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('/')):
+
−            if (not _is_valid_path(request.path_info) and
+
−                    _is_valid_path("%s/" % request.path_info)):
+
−                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:
+
−            # No redirects required.
+
−            return
+
−        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.META['QUERY_STRING']
+
−        return http.HttpResponsePermanentRedirect(newurl)
+
−
+
−    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', '<none>')
+
−                    ip = request.META.get('REMOTE_ADDR', '<none>')
+
−                    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 = '"%s"' % md5_constructor(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):
+
−    """
+
−    Returns 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)
+
−
+
−def _is_valid_path(path):
+
−    """
+
−    Returns True if the given path resolves against the default URL resolver,
+
−    False otherwise.
+
−
+
−    This is a convenience method to make working with "is this a match?" cases
+
−    easier, avoiding unnecessarily indented try...except blocks.
+
−    """
+
−    try:
+
−        urlresolvers.resolve(path)
+
−        return True
+
−    except urlresolvers.Resolver404:
+
−        return False
+
−