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common.py
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common.py
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import hashlib
import logging
import re
from django import http
from django.conf import settings
from django.core import urlresolvers
from django.core.mail import mail_managers
from django.utils import six
from django.utils.encoding import force_text
from django.utils.http import urlquote
logger = logging.getLogger('django.request')
class CommonMiddleware(object):
"""
"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.
"""
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']):
logger.warning('Forbidden (User agent): %s', request.path,
extra={
'status_code': 403,
'request': request
}
)
return http.HttpResponseForbidden('<h1>Forbidden</h1>')
# Check for a redirect based on settings.APPEND_SLASH
# and settings.PREPEND_WWW
host = request.get_host()
old_url = [host, request.path]
new_url = old_url[:]
if (settings.PREPEND_WWW and old_url[0] 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 and there is no pattern for the current path
if settings.APPEND_SLASH and (not old_url[1].endswith('/')):
urlconf = getattr(request, 'urlconf', None)
if (not urlresolvers.is_valid_path(request.path_info, urlconf) and
urlresolvers.is_valid_path("%s/" % request.path_info, urlconf)):
new_url[1] = new_url[1] + '/'
if settings.DEBUG and request.method == 'POST':
raise RuntimeError((""
"You called this URL via POST, 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 POST data. "
"Change your form to point to %s%s (note the trailing "
"slash), or set APPEND_SLASH=False in your Django "
"settings.") % (new_url[0], new_url[1]))
if new_url == old_url:
# No redirects required.
return
if new_url[0]:
newurl = "%s://%s%s" % (
request.scheme,
new_url[0], urlquote(new_url[1]))
else:
newurl = urlquote(new_url[1])
if request.META.get('QUERY_STRING', ''):
if six.PY3:
newurl += '?' + request.META['QUERY_STRING']
else:
# `query_string` is a bytestring. Appending it to the unicode
# string `newurl` will fail if it isn't ASCII-only. This isn't
# allowed; only broken software generates such query strings.
# Better drop the invalid query string than crash (#15152).
try:
newurl += '?' + request.META['QUERY_STRING'].decode()
except UnicodeDecodeError:
pass
return self.response_redirect_class(newurl)
def process_response(self, request, response):
"""
Calculate the ETag, if needed.
"""
if settings.USE_ETAGS:
if response.has_header('ETag'):
etag = response['ETag']
elif response.streaming:
etag = None
else:
etag = '"%s"' % hashlib.md5(response.content).hexdigest()
if etag is not None:
if (200 <= response.status_code < 300
and request.META.get('HTTP_IF_NONE_MATCH') == etag):
cookies = response.cookies
response = http.HttpResponseNotModified()
response.cookies = cookies
else:
response['ETag'] = etag
return response
class BrokenLinkEmailsMiddleware(object):
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 = request.META.get('HTTP_USER_AGENT', '<none>')
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):
"""
Returns True if the given request *shouldn't* notify the site managers.
"""
# '?' in referer is identified as search engine source
if (not referer or
(not self.is_internal_request(domain, referer) and '?' in referer)):
return True
return any(pattern.search(uri) for pattern in settings.IGNORABLE_404_URLS)