180 lines
7.4 KiB
Python
180 lines
7.4 KiB
Python
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import re
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from urllib.parse import urlparse
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from django.conf import settings
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from django.core.exceptions import PermissionDenied
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from django.core.mail import mail_managers
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from django.http import HttpResponsePermanentRedirect
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from django.urls import is_valid_path
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from django.utils.deprecation import MiddlewareMixin
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from django.utils.http import escape_leading_slashes
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class CommonMiddleware(MiddlewareMixin):
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"""
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"Common" middleware for taking care of some basic operations:
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- Forbid 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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append missing slashes and/or prepends missing "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, form a new URL by
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appending a slash at the end. If this new URL is found in
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urlpatterns, return an HTTP redirect to this new URL; otherwise
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process the initial URL as usual.
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This behavior can be customized by subclassing CommonMiddleware and
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overriding the response_redirect_class attribute.
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"""
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response_redirect_class = HttpResponsePermanentRedirect
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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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user_agent = request.META.get("HTTP_USER_AGENT")
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if user_agent is not None:
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for user_agent_regex in settings.DISALLOWED_USER_AGENTS:
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if user_agent_regex.search(user_agent):
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raise PermissionDenied("Forbidden user agent")
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# Check for a redirect based on settings.PREPEND_WWW
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host = request.get_host()
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must_prepend = settings.PREPEND_WWW and host and not host.startswith("www.")
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redirect_url = ("%s://www.%s" % (request.scheme, host)) if must_prepend else ""
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# Check if a slash should be appended
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if self.should_redirect_with_slash(request):
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path = self.get_full_path_with_slash(request)
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else:
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path = request.get_full_path()
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# Return a redirect if necessary
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if redirect_url or path != request.get_full_path():
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redirect_url += path
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return self.response_redirect_class(redirect_url)
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def should_redirect_with_slash(self, request):
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"""
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Return True if settings.APPEND_SLASH is True and appending a slash to
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the request path turns an invalid path into a valid one.
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"""
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if settings.APPEND_SLASH and not request.path_info.endswith("/"):
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urlconf = getattr(request, "urlconf", None)
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if not is_valid_path(request.path_info, urlconf):
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match = is_valid_path("%s/" % request.path_info, urlconf)
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if match:
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view = match.func
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return getattr(view, "should_append_slash", True)
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return False
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def get_full_path_with_slash(self, request):
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"""
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Return the full path of the request with a trailing slash appended.
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Raise a RuntimeError if settings.DEBUG is True and request.method is
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POST, PUT, or PATCH.
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"""
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new_path = request.get_full_path(force_append_slash=True)
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# Prevent construction of scheme relative urls.
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new_path = escape_leading_slashes(new_path)
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if settings.DEBUG and request.method in ("POST", "PUT", "PATCH"):
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raise RuntimeError(
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"You called this URL via %(method)s, 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 %(method)s data. "
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"Change your form to point to %(url)s (note the trailing "
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"slash), or set APPEND_SLASH=False in your Django settings."
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% {
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"method": request.method,
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"url": request.get_host() + new_path,
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}
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)
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return new_path
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def process_response(self, request, response):
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"""
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When the status code of the response is 404, it may redirect to a path
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with an appended slash if should_redirect_with_slash() returns True.
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"""
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# If the given URL is "Not Found", then check if we should redirect to
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# a path with a slash appended.
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if response.status_code == 404 and self.should_redirect_with_slash(request):
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return self.response_redirect_class(self.get_full_path_with_slash(request))
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# Add the Content-Length header to non-streaming responses if not
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# already set.
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if not response.streaming and not response.has_header("Content-Length"):
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response.headers["Content-Length"] = str(len(response.content))
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return response
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class BrokenLinkEmailsMiddleware(MiddlewareMixin):
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def process_response(self, request, response):
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"""Send broken link emails for relevant 404 NOT FOUND responses."""
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if response.status_code == 404 and not settings.DEBUG:
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domain = request.get_host()
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path = request.get_full_path()
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referer = request.META.get("HTTP_REFERER", "")
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if not self.is_ignorable_request(request, path, domain, 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(
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"Broken %slink on %s"
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% (
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(
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"INTERNAL "
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if self.is_internal_request(domain, referer)
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else ""
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),
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domain,
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),
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"Referrer: %s\nRequested URL: %s\nUser agent: %s\n"
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"IP address: %s\n" % (referer, path, ua, ip),
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fail_silently=True,
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)
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return response
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def is_internal_request(self, domain, referer):
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"""
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Return True if the referring URL is the same domain as the current
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request.
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"""
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# Different subdomains are treated as different domains.
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return bool(re.match("^https?://%s/" % re.escape(domain), referer))
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def is_ignorable_request(self, request, uri, domain, referer):
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"""
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Return True if the given request *shouldn't* notify the site managers
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according to project settings or in situations outlined by the inline
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comments.
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"""
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# The referer is empty.
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if not referer:
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return True
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# APPEND_SLASH is enabled and the referer is equal to the current URL
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# without a trailing slash indicating an internal redirect.
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if settings.APPEND_SLASH and uri.endswith("/") and referer == uri[:-1]:
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return True
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# A '?' in referer is identified as a search engine source.
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if not self.is_internal_request(domain, referer) and "?" in referer:
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return True
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# The referer is equal to the current URL, ignoring the scheme (assumed
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# to be a poorly implemented bot).
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parsed_referer = urlparse(referer)
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if parsed_referer.netloc in ["", domain] and parsed_referer.path == uri:
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return True
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return any(pattern.search(uri) for pattern in settings.IGNORABLE_404_URLS)
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