django1/django/contrib/auth/middleware.py

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from django.contrib import auth
from django.contrib.auth import load_backend
from django.contrib.auth.backends import RemoteUserBackend
from django.core.exceptions import ImproperlyConfigured
from django.utils.crypto import constant_time_compare
from django.utils.functional import SimpleLazyObject
def get_user(request):
if not hasattr(request, '_cached_user'):
request._cached_user = auth.get_user(request)
return request._cached_user
class AuthenticationMiddleware(object):
def process_request(self, request):
assert hasattr(request, 'session'), (
"The Django authentication middleware requires session middleware "
"to be installed. Edit your MIDDLEWARE_CLASSES setting to insert "
"'django.contrib.sessions.middleware.SessionMiddleware' before "
"'django.contrib.auth.middleware.AuthenticationMiddleware'."
)
request.user = SimpleLazyObject(lambda: get_user(request))
class SessionAuthenticationMiddleware(object):
"""
Middleware for invalidating a user's sessions that don't correspond to the
user's current session authentication hash (generated based on the user's
password for AbstractUser).
"""
def process_request(self, request):
user = request.user
if user and hasattr(user, 'get_session_auth_hash'):
session_hash = request.session.get(auth.HASH_SESSION_KEY)
session_hash_verified = session_hash and constant_time_compare(
session_hash,
user.get_session_auth_hash()
)
if not session_hash_verified:
auth.logout(request)
class RemoteUserMiddleware(object):
"""
Middleware for utilizing Web-server-provided authentication.
If request.user is not authenticated, then this middleware attempts to
authenticate the username passed in the ``REMOTE_USER`` request header.
If authentication is successful, the user is automatically logged in to
persist the user in the session.
The header used is configurable and defaults to ``REMOTE_USER``. Subclass
this class and change the ``header`` attribute if you need to use a
different header.
"""
# Name of request header to grab username from. This will be the key as
# used in the request.META dictionary, i.e. the normalization of headers to
# all uppercase and the addition of "HTTP_" prefix apply.
header = "REMOTE_USER"
def process_request(self, request):
# AuthenticationMiddleware is required so that request.user exists.
if not hasattr(request, 'user'):
raise ImproperlyConfigured(
"The Django remote user auth middleware requires the"
" authentication middleware to be installed. Edit your"
" MIDDLEWARE_CLASSES setting to insert"
" 'django.contrib.auth.middleware.AuthenticationMiddleware'"
" before the RemoteUserMiddleware class.")
try:
username = request.META[self.header]
except KeyError:
# If specified header doesn't exist then remove any existing
# authenticated remote-user, or return (leaving request.user set to
# AnonymousUser by the AuthenticationMiddleware).
if request.user.is_authenticated():
self._remove_invalid_user(request)
return
# If the user is already authenticated and that user is the user we are
# getting passed in the headers, then the correct user is already
# persisted in the session and we don't need to continue.
if request.user.is_authenticated():
if request.user.get_username() == self.clean_username(username, request):
return
else:
# An authenticated user is associated with the request, but
# it does not match the authorized user in the header.
self._remove_invalid_user(request)
# We are seeing this user for the first time in this session, attempt
# to authenticate the user.
user = auth.authenticate(remote_user=username)
if user:
# User is valid. Set request.user and persist user in the session
# by logging the user in.
request.user = user
auth.login(request, user)
def clean_username(self, username, request):
"""
Allows the backend to clean the username, if the backend defines a
clean_username method.
"""
backend_str = request.session[auth.BACKEND_SESSION_KEY]
backend = auth.load_backend(backend_str)
try:
username = backend.clean_username(username)
except AttributeError: # Backend has no clean_username method.
pass
return username
def _remove_invalid_user(self, request):
"""
Removes the current authenticated user in the request which is invalid
but only if the user is authenticated via the RemoteUserBackend.
"""
try:
stored_backend = load_backend(request.session.get(auth.BACKEND_SESSION_KEY, ''))
except ImportError:
# backend failed to load
auth.logout(request)
else:
if isinstance(stored_backend, RemoteUserBackend):
auth.logout(request)