1 import datetime

     2 from django.core.exceptions import ImproperlyConfigured

     3 

     4 SESSION_KEY = '_auth_user_id'

     5 BACKEND_SESSION_KEY = '_auth_user_backend'

     6 REDIRECT_FIELD_NAME = 'next'

     7 

     8 def load_backend(path):

     9     i = path.rfind('.')

    10     module, attr = path[:i], path[i+1:]

    11     try:

    12         mod = __import__(module, {}, {}, [attr])

    13     except ImportError, e:

    14         raise ImproperlyConfigured, 'Error importing authentication backend %s: "%s"' % (module, e)

    15     except ValueError, e:

    16         raise ImproperlyConfigured, 'Error importing authentication backends. Is AUTHENTICATION_BACKENDS a correctly defined list or tuple?'

    17     try:

    18         cls = getattr(mod, attr)

    19     except AttributeError:

    20         raise ImproperlyConfigured, 'Module "%s" does not define a "%s" authentication backend' % (module, attr)

    21     return cls()

    22 

    23 def get_backends():

    24     from django.conf import settings

    25     backends = []

    26     for backend_path in settings.AUTHENTICATION_BACKENDS:

    27         backends.append(load_backend(backend_path))

    28     return backends

    29 

    30 def authenticate(**credentials):

    31     """

    32     If the given credentials are valid, return a User object.

    33     """

    34     for backend in get_backends():

    35         try:

    36             user = backend.authenticate(**credentials)

    37         except TypeError:

    38             # This backend doesn't accept these credentials as arguments. Try the next one.

    39             continue

    40         if user is None:

    41             continue

    42         # Annotate the user object with the path of the backend.

    43         user.backend = "%s.%s" % (backend.__module__, backend.__class__.__name__)

    44         return user

    45 

    46 def login(request, user):

    47     """

    48     Persist a user id and a backend in the request. This way a user doesn't

    49     have to reauthenticate on every request.

    50     """

    51     if user is None:

    52         user = request.user

    53     # TODO: It would be nice to support different login methods, like signed cookies.

    54     user.last_login = datetime.datetime.now()

    55     user.save()

    56     request.session[SESSION_KEY] = user.id

    57     request.session[BACKEND_SESSION_KEY] = user.backend

    58     if hasattr(request, 'user'):

    59         request.user = user

    60 

    61 def logout(request):

    62     """

    63     Remove the authenticated user's ID from the request.

    64     """

    65     try:

    66         del request.session[SESSION_KEY]

    67     except KeyError:

    68         pass

    69     try:

    70         del request.session[BACKEND_SESSION_KEY]

    71     except KeyError:

    72         pass

    73     if hasattr(request, 'user'):

    74         from django.contrib.auth.models import AnonymousUser

    75         request.user = AnonymousUser()

    76 

    77 def get_user(request):

    78     from django.contrib.auth.models import AnonymousUser

    79     try:

    80         user_id = request.session[SESSION_KEY]

    81         backend_path = request.session[BACKEND_SESSION_KEY]

    82         backend = load_backend(backend_path)

    83         user = backend.get_user(user_id) or AnonymousUser()

    84     except KeyError:

    85         user = AnonymousUser()

    86     return user