Source code for django.middleware.common

import re
import warnings

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
from django.utils.encoding import force_text
from django.utils.six.moves.urllib.parse import urlparse


[docs]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 "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. 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 ConditionalGetMiddleware. """ 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: if user_agent_regex.search(request.META['HTTP_USER_AGENT']): 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) else: 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 POST, PUT, or PATCH. """ 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): warnings.warn( "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.", RemovedInDjango21Warning ) if not response.has_header('ETag'): set_response_etag(response) if response.has_header('ETag'): return get_conditional_response( request, etag=response['ETag'], response=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)
[docs]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 = force_text(request.META.get('HTTP_REFERER', ''), errors='replace') if not self.is_ignorable_request(request, path, domain, referer): ua = force_text(request.META.get('HTTP_USER_AGENT', '<none>'), errors='replace') ip = request.META.get('REMOTE_ADDR', '<none>') mail_managers( "Broken %slink on %s" % ( ('INTERNAL ' if self.is_internal_request(domain, referer) else ''), domain ), "Referrer: %s\nRequested URL: %s\nUser agent: %s\n" "IP address: %s\n" % (referer, path, ua, ip), fail_silently=True) 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 comments. """ # 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(pattern.search(uri) for pattern in settings.IGNORABLE_404_URLS)
Back to Top