Find file
207 lines (173 sloc) 8.43 KB
import re
import warnings
from urllib.parse import urlparse
from django import http
from django.conf import settings
from django.core.exceptions import PermissionDenied
from django.core.mail import mail_managers
from django.urls import is_valid_path
from django.utils.cache import (
cc_delim_re, get_conditional_response, set_response_etag,
from django.utils.deprecation import MiddlewareMixin, RemovedInDjango21Warning
class CommonMiddleware(MiddlewareMixin):
"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
- 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.
This behavior can be customized by subclassing CommonMiddleware and
overriding the response_redirect_class attribute.
- 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. USE_ETAGS is deprecated in favor of
response_redirect_class = http.HttpResponsePermanentRedirect
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:
raise PermissionDenied('Forbidden user agent')
# Check for a redirect based on settings.PREPEND_WWW
host = request.get_host()
must_prepend = settings.PREPEND_WWW and host and not host.startswith('www.')
redirect_url = ('%s://www.%s' % (request.scheme, host)) if must_prepend else ''
# Check if a slash should be appended
if self.should_redirect_with_slash(request):
path = self.get_full_path_with_slash(request)
path = request.get_full_path()
# Return a redirect if necessary
if redirect_url or path != request.get_full_path():
redirect_url += path
return self.response_redirect_class(redirect_url)
def should_redirect_with_slash(self, request):
Return True if settings.APPEND_SLASH is True and appending a slash to
the request path turns an invalid path into a valid one.
if settings.APPEND_SLASH and not request.path_info.endswith('/'):
urlconf = getattr(request, 'urlconf', None)
return (
not is_valid_path(request.path_info, urlconf) and
is_valid_path('%s/' % request.path_info, urlconf)
return False
def get_full_path_with_slash(self, request):
Return the full path of the request with a trailing slash appended.
Raise a RuntimeError if settings.DEBUG is True and request.method is
new_path = request.get_full_path(force_append_slash=True)
if settings.DEBUG and request.method in ('POST', 'PUT', 'PATCH'):
raise RuntimeError(
"You called this URL via %(method)s, 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 %(method)s data. "
"Change your form to point to %(url)s (note the trailing "
"slash), or set APPEND_SLASH=False in your Django settings." % {
'method': request.method,
'url': request.get_host() + new_path,
return new_path
def process_response(self, request, response):
Calculate the ETag, if needed.
When the status code of the response is 404, it may redirect to a path
with an appended slash if should_redirect_with_slash() returns True.
# If the given URL is "Not Found", then check if we should redirect to
# a path with a slash appended.
if response.status_code == 404:
if self.should_redirect_with_slash(request):
return self.response_redirect_class(self.get_full_path_with_slash(request))
if settings.USE_ETAGS and self.needs_etag(response):
"The USE_ETAGS setting is deprecated in favor of "
"ConditionalGetMiddleware which sets the ETag regardless of "
"the setting. CommonMiddleware won't do ETag processing in "
"Django 2.1.",
if not response.has_header('ETag'):
if response.has_header('ETag'):
return get_conditional_response(
# Add the Content-Length header to non-streaming responses if not
# already set.
if not response.streaming and not response.has_header('Content-Length'):
response['Content-Length'] = str(len(response.content))
return response
def needs_etag(self, response):
Return True if an ETag header should be added to response.
cache_control_headers = cc_delim_re.split(response.get('Cache-Control', ''))
return all(header.lower() != 'no-store' for header in cache_control_headers)
class BrokenLinkEmailsMiddleware(MiddlewareMixin):
def process_response(self, request, response):
Send broken link emails for relevant 404 NOT FOUND responses.
if response.status_code == 404 and not settings.DEBUG:
domain = request.get_host()
path = request.get_full_path()
referer = request.META.get('HTTP_REFERER', '')
if not self.is_ignorable_request(request, path, domain, referer):
ua = request.META.get('HTTP_USER_AGENT', '<none>')
ip = request.META.get('REMOTE_ADDR', '<none>')
"Broken %slink on %s" % (
('INTERNAL ' if self.is_internal_request(domain, referer) else ''),
"Referrer: %s\nRequested URL: %s\nUser agent: %s\n"
"IP address: %s\n" % (referer, path, ua, ip),
return response
def is_internal_request(self, domain, referer):
Returns True if the referring URL is the same domain as the current request.
# Different subdomains are treated as different domains.
return bool(re.match("^https?://%s/" % re.escape(domain), referer))
def is_ignorable_request(self, request, uri, domain, referer):
Return True if the given request *shouldn't* notify the site managers
according to project settings or in situations outlined by the inline
# The referer is empty.
if not referer:
return True
# APPEND_SLASH is enabled and the referer is equal to the current URL
# without a trailing slash indicating an internal redirect.
if settings.APPEND_SLASH and uri.endswith('/') and referer == uri[:-1]:
return True
# A '?' in referer is identified as a search engine source.
if not self.is_internal_request(domain, referer) and '?' in referer:
return True
# The referer is equal to the current URL, ignoring the scheme (assumed
# to be a poorly implemented bot).
parsed_referer = urlparse(referer)
if parsed_referer.netloc in ['', domain] and parsed_referer.path == uri:
return True
return any( for pattern in settings.IGNORABLE_404_URLS)