--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/app/django/contrib/admin/views/decorators.py	Fri Jul 18 18:22:23 2008 +0000
@@ -0,0 +1,114 @@
+import base64
+import md5
+import cPickle as pickle
+try:
+    from functools import wraps
+except ImportError:
+    from django.utils.functional import wraps  # Python 2.3, 2.4 fallback.
+
+from django import http, template
+from django.conf import settings
+from django.contrib.auth.models import User
+from django.contrib.auth import authenticate, login
+from django.shortcuts import render_to_response
+from django.utils.translation import ugettext_lazy, ugettext as _
+from django.utils.safestring import mark_safe
+
+ERROR_MESSAGE = ugettext_lazy("Please enter a correct username and password. Note that both fields are case-sensitive.")
+LOGIN_FORM_KEY = 'this_is_the_login_form'
+
+def _display_login_form(request, error_message=''):
+    request.session.set_test_cookie()
+    if request.POST and 'post_data' in request.POST:
+        # User has failed login BUT has previously saved post data.
+        post_data = request.POST['post_data']
+    elif request.POST:
+        # User's session must have expired; save their post data.
+        post_data = _encode_post_data(request.POST)
+    else:
+        post_data = _encode_post_data({})
+    return render_to_response('admin/login.html', {
+        'title': _('Log in'),
+        'app_path': request.path,
+        'post_data': post_data,
+        'error_message': error_message
+    }, context_instance=template.RequestContext(request))
+
+def _encode_post_data(post_data):
+    pickled = pickle.dumps(post_data)
+    pickled_md5 = md5.new(pickled + settings.SECRET_KEY).hexdigest()
+    return base64.encodestring(pickled + pickled_md5)
+
+def _decode_post_data(encoded_data):
+    encoded_data = base64.decodestring(encoded_data)
+    pickled, tamper_check = encoded_data[:-32], encoded_data[-32:]
+    if md5.new(pickled + settings.SECRET_KEY).hexdigest() != tamper_check:
+        from django.core.exceptions import SuspiciousOperation
+        raise SuspiciousOperation, "User may have tampered with session cookie."
+    return pickle.loads(pickled)
+
+def staff_member_required(view_func):
+    """
+    Decorator for views that checks that the user is logged in and is a staff
+    member, displaying the login page if necessary.
+    """
+    def _checklogin(request, *args, **kwargs):
+        if request.user.is_authenticated() and request.user.is_staff:
+            # The user is valid. Continue to the admin page.
+            if 'post_data' in request.POST:
+                # User must have re-authenticated through a different window
+                # or tab.
+                request.POST = _decode_post_data(request.POST['post_data'])
+            return view_func(request, *args, **kwargs)
+
+        assert hasattr(request, 'session'), "The Django admin requires session middleware to be installed. Edit your MIDDLEWARE_CLASSES setting to insert 'django.contrib.sessions.middleware.SessionMiddleware'."
+
+        # If this isn't already the login page, display it.
+        if LOGIN_FORM_KEY not in request.POST:
+            if request.POST:
+                message = _("Please log in again, because your session has expired. Don't worry: Your submission has been saved.")
+            else:
+                message = ""
+            return _display_login_form(request, message)
+
+        # Check that the user accepts cookies.
+        if not request.session.test_cookie_worked():
+            message = _("Looks like your browser isn't configured to accept cookies. Please enable cookies, reload this page, and try again.")
+            return _display_login_form(request, message)
+
+        # Check the password.
+        username = request.POST.get('username', None)
+        password = request.POST.get('password', None)
+        user = authenticate(username=username, password=password)
+        if user is None:
+            message = ERROR_MESSAGE
+            if '@' in username:
+                # Mistakenly entered e-mail address instead of username? Look it up.
+                users = list(User.objects.filter(email=username))
+                if len(users) == 1:
+                    message = _("Your e-mail address is not your username. Try '%s' instead.") % users[0].username
+                else:
+                    # Either we cannot find the user, or if more than 1 
+                    # we cannot guess which user is the correct one.
+                    message = _("Usernames cannot contain the '@' character.")
+            return _display_login_form(request, message)
+
+        # The user data is correct; log in the user in and continue.
+        else:
+            if user.is_active and user.is_staff:
+                login(request, user)
+                # TODO: set last_login with an event.
+                if 'post_data' in request.POST:
+                    post_data = _decode_post_data(request.POST['post_data'])
+                    if post_data and LOGIN_FORM_KEY not in post_data:
+                        # overwrite request.POST with the saved post_data, and continue
+                        request.POST = post_data
+                        request.user = user
+                        return view_func(request, *args, **kwargs)
+                    else:
+                        request.session.delete_test_cookie()
+                        return http.HttpResponseRedirect(request.path)
+            else:
+                return _display_login_form(request, ERROR_MESSAGE)
+
+    return wraps(view_func)(_checklogin)