django1/django/middleware/common.py

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from django.conf import settings
from django.core import exceptions
from django.utils import httpwrappers
from django.core.mail import mail_managers
from django.views.core.flatfiles import flat_file
import md5, os
class CommonMiddleware:
"""
"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 will -- shocking, isn't it -- append missing slashes
and/or prepend missing "www."s.
- 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.
- Flat files: for 404 responses, a flat file matching the given path
will be looked up and used if found.
"""
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 request.META.has_key('HTTP_USER_AGENT'):
for user_agent_regex in settings.DISALLOWED_USER_AGENTS:
if user_agent_regex.search(request.META['HTTP_USER_AGENT']):
return httpwrappers.HttpResponseForbidden('<h1>Forbidden</h1>')
# Check for a redirect based on settings.APPEND_SLASH and settings.PREPEND_WWW
old_url = [request.META['HTTP_HOST'], request.path]
new_url = old_url[:]
if settings.PREPEND_WWW 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 or a file extension.
if settings.APPEND_SLASH and (old_url[1][-1] != '/') and ('.' not in old_url[1].split('/')[-1]):
new_url[1] = new_url[1] + '/'
if new_url != old_url:
# Redirect
newurl = "%s://%s%s" % (os.environ.get('HTTPS') == 'on' and 'https' or 'http', new_url[0], new_url[1])
if request.GET:
newurl += '?' + request.GET.urlencode()
return httpwrappers.HttpResponseRedirect(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.USE_FLAT_PAGES:
try:
return flat_file(request, request.path)
except exceptions.Http404:
pass
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.META['HTTP_HOST']
referer = request.META.get('HTTP_REFERER', None)
is_internal = referer and (domain in referer)
path = request.get_full_path()
if referer and not _is_ignorable_404(path) and (is_internal or '?' not in referer):
mail_managers("Broken %slink on %s" % ((is_internal and 'INTERNAL ' or ''), domain),
"Referrer: %s\nRequested URL: %s\n" % (referer, request.get_full_path()))
return response
# Use ETags, if requested.
if settings.USE_ETAGS:
etag = md5.new(response.get_content_as_string(settings.DEFAULT_CHARSET)).hexdigest()
if request.META.get('HTTP_IF_NONE_MATCH') == etag:
response = httpwrappers.HttpResponseNotModified()
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