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Viewing changes to trunk/python-packages/django/middleware/common.py

  • Committer: Matthew Nuzum
  • Date: 2008-11-13 05:46:03 UTC
  • Revision ID: matthew.nuzum@canonical.com-20081113054603-v0kvr6z6xyexvqt3
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trunk/python-packages/django/middleware/common.py
 
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import re
 
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from django.conf import settings
 
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from django import http
 
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from django.core.mail import mail_managers
 
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from django.utils.http import urlquote
 
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from django.core import urlresolvers
 
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from django.utils.hashcompat import md5_constructor
 
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class CommonMiddleware(object):
 
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    """
 
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    "Common" middleware for taking care of some basic operations:
 
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        - Forbids access to User-Agents in settings.DISALLOWED_USER_AGENTS
 
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        - URL rewriting: Based on the APPEND_SLASH and PREPEND_WWW settings,
 
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          this middleware appends missing slashes and/or prepends missing
 
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          "www."s.
 
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            - If APPEND_SLASH is set and the initial URL doesn't end with a
 
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              slash, and it is not found in urlpatterns, a new URL is formed by
 
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              appending a slash at the end. If this new URL is found in
 
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              urlpatterns, then an HTTP-redirect is returned to this new URL;
 
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              otherwise the initial URL is processed as usual.
 
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        - ETags: If the USE_ETAGS setting is set, ETags will be calculated from
 
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          the entire page content and Not Modified responses will be returned
 
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          appropriately.
 
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    """
 
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    def process_request(self, request):
 
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        """
 
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        Check for denied User-Agents and rewrite the URL based on
 
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        settings.APPEND_SLASH and settings.PREPEND_WWW
 
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        """
 
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        # Check for denied User-Agents
 
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        if 'HTTP_USER_AGENT' in request.META:
 
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            for user_agent_regex in settings.DISALLOWED_USER_AGENTS:
 
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                if user_agent_regex.search(request.META['HTTP_USER_AGENT']):
 
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                    return http.HttpResponseForbidden('<h1>Forbidden</h1>')
 
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        # Check for a redirect based on settings.APPEND_SLASH
 
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        # and settings.PREPEND_WWW
 
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        host = request.get_host()
 
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        old_url = [host, request.path]
 
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        new_url = old_url[:]
 
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        if (settings.PREPEND_WWW and old_url[0] and
 
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                not old_url[0].startswith('www.')):
 
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            new_url[0] = 'www.' + old_url[0]
 
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        # Append a slash if APPEND_SLASH is set and the URL doesn't have a
 
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        # trailing slash and there is no pattern for the current path
 
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        if settings.APPEND_SLASH and (not old_url[1].endswith('/')):
 
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            try:
 
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                urlresolvers.resolve(request.path_info)
 
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            except urlresolvers.Resolver404:
 
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                new_url[1] = new_url[1] + '/'
 
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                if settings.DEBUG and request.method == 'POST':
 
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                    raise RuntimeError, (""
 
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                    "You called this URL via POST, but the URL doesn't end "
 
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                    "in a slash and you have APPEND_SLASH set. Django can't "
 
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                    "redirect to the slash URL while maintaining POST data. "
 
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                    "Change your form to point to %s%s (note the trailing "
 
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                    "slash), or set APPEND_SLASH=False in your Django "
 
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                    "settings.") % (new_url[0], new_url[1])
 
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        if new_url != old_url:
 
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            # Redirect if the target url exists
 
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            try:
 
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                urlresolvers.resolve("%s/" % request.path_info)
 
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            except urlresolvers.Resolver404:
 
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                pass
 
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            else:
 
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                if new_url[0]:
 
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                    newurl = "%s://%s%s" % (
 
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                        request.is_secure() and 'https' or 'http',
 
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                        new_url[0], urlquote(new_url[1]))
 
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                else:
 
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                    newurl = urlquote(new_url[1])
 
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                if request.GET:
 
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                    newurl += '?' + request.META['QUERY_STRING']
 
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                return http.HttpResponsePermanentRedirect(newurl)
 
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        return None
 
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    def process_response(self, request, response):
 
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        "Check for a flat page (for 404s) and calculate the Etag, if needed."
 
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        if response.status_code == 404:
 
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            if settings.SEND_BROKEN_LINK_EMAILS:
 
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                # If the referrer was from an internal link or a non-search-engine site,
 
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                # send a note to the managers.
 
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                domain = request.get_host()
 
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                referer = request.META.get('HTTP_REFERER', None)
 
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                is_internal = _is_internal_request(domain, referer)
 
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                path = request.get_full_path()
 
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                if referer and not _is_ignorable_404(path) and (is_internal or '?' not in referer):
 
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                    ua = request.META.get('HTTP_USER_AGENT', '<none>')
 
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                    ip = request.META.get('REMOTE_ADDR', '<none>')
 
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                    mail_managers("Broken %slink on %s" % ((is_internal and 'INTERNAL ' or ''), domain),
 
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                        "Referrer: %s\nRequested URL: %s\nUser agent: %s\nIP address: %s\n" \
 
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                                  % (referer, request.get_full_path(), ua, ip))
 
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                return response
 
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        # Use ETags, if requested.
 
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        if settings.USE_ETAGS:
 
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            if response.has_header('ETag'):
 
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                etag = response['ETag']
 
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            else:
 
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                etag = '"%s"' % md5_constructor(response.content).hexdigest()
 
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            if response.status_code >= 200 and response.status_code < 300 and request.META.get('HTTP_IF_NONE_MATCH') == etag:
 
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                cookies = response.cookies
 
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                response = http.HttpResponseNotModified()
 
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                response.cookies = cookies
 
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            else:
 
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                response['ETag'] = etag
 
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        return response
 
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def _is_ignorable_404(uri):
 
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    "Returns True if a 404 at the given URL *shouldn't* notify the site managers"
 
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    for start in settings.IGNORABLE_404_STARTS:
 
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        if uri.startswith(start):
 
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            return True
 
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    for end in settings.IGNORABLE_404_ENDS:
 
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        if uri.endswith(end):
 
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            return True
 
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    return False
 
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def _is_internal_request(domain, referer):
 
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    "Return true if the referring URL is the same domain as the current request"
 
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    # Different subdomains are treated as different domains.
 
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    return referer is not None and re.match("^https?://%s/" % re.escape(domain), referer)