import datetime
from warnings import warn
from django.core.exceptions import ImproperlyConfigured
from django.utils.importlib import import_module
SESSION_KEY = '_auth_user_id'
BACKEND_SESSION_KEY = '_auth_user_backend'
REDIRECT_FIELD_NAME = 'next'
def load_backend(path):
i = path.rfind('.')
module, attr = path[:i], path[i+1:]
try:
mod = import_module(module)
except ImportError, e:
raise ImproperlyConfigured('Error importing authentication backend %s: "%s"' % (module, e))
except ValueError, e:
raise ImproperlyConfigured('Error importing authentication backends. Is AUTHENTICATION_BACKENDS a correctly defined list or tuple?')
try:
cls = getattr(mod, attr)
except AttributeError:
raise ImproperlyConfigured('Module "%s" does not define a "%s" authentication backend' % (module, attr))
try:
getattr(cls, 'supports_object_permissions')
except AttributeError:
warn("Authentication backends without a `supports_object_permissions` attribute are deprecated. Please define it in %s." % cls,
PendingDeprecationWarning)
cls.supports_object_permissions = False
try:
getattr(cls, 'supports_anonymous_user')
except AttributeError:
warn("Authentication backends without a `supports_anonymous_user` attribute are deprecated. Please define it in %s." % cls,
PendingDeprecationWarning)
cls.supports_anonymous_user = False
return cls()
def get_backends():
from django.conf import settings
backends = []
for backend_path in settings.AUTHENTICATION_BACKENDS:
backends.append(load_backend(backend_path))
return backends
def authenticate(**credentials):
"""
If the given credentials are valid, return a User object.
"""
for backend in get_backends():
try:
user = backend.authenticate(**credentials)
except TypeError:
# This backend doesn't accept these credentials as arguments. Try the next one.
continue
if user is None:
continue
# Annotate the user object with the path of the backend.
user.backend = "%s.%s" % (backend.__module__, backend.__class__.__name__)
return user
def login(request, user):
"""
Persist a user id and a backend in the request. This way a user doesn't
have to reauthenticate on every request.
"""
if user is None:
user = request.user
# TODO: It would be nice to support different login methods, like signed cookies.
user.last_login = datetime.datetime.now()
user.save()
if SESSION_KEY in request.session:
if request.session[SESSION_KEY] != user.id:
# To avoid reusing another user's session, create a new, empty
# session if the existing session corresponds to a different
# authenticated user.
request.session.flush()
else:
request.session.cycle_key()
request.session[SESSION_KEY] = user.id
request.session[BACKEND_SESSION_KEY] = user.backend
if hasattr(request, 'user'):
request.user = user
def logout(request):
"""
Removes the authenticated user's ID from the request and flushes their
session data.
"""
request.session.flush()
if hasattr(request, 'user'):
from django.contrib.auth.models import AnonymousUser
request.user = AnonymousUser()
def get_user(request):
from django.contrib.auth.models import AnonymousUser
try:
user_id = request.session[SESSION_KEY]
backend_path = request.session[BACKEND_SESSION_KEY]
backend = load_backend(backend_path)
user = backend.get_user(user_id) or AnonymousUser()
except KeyError:
user = AnonymousUser()
return user
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