Initial snapshot.

lib/security.py

@@ -0,0 +1,70 @@
+# Copyright 2014, Ian Gulliver
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import functools
+
+from google.appengine.api import users
+
+from cosmopolite.lib import auth
+
+
+def google_user_xsrf_protection(handler):
+  """Validate google user cookie.
+
+  We can't trust that the action being requested is being made by this user due
+  to XSRF concerns (since google user is stored in a cookie). We have to make
+  sure that this user can actually receive responses, so we ask them to pass a
+  second token about their user that we can validate.
+  """
+
+  @functools.wraps(handler)
+  def ValidateGoogleUser(self):
+    self.verified_google_user = None
+
+    google_user = users.get_current_user()
+    if not google_user:
+      return handler(self)
+
+    google_user_id = auth.Parse(self.request.get('google_user_id', None))
+    if (not google_user_id or 
+        google_user_id != google_user.user_id()):
+      return {
+        'status': 'retry',
+        'google_user_id': auth.Sign(google_user.user_id()),
+      }
+
+    self.verified_google_user = google_user
+    return handler(self)
+
+  return ValidateGoogleUser
+
+
+def weak_security_checks(handler):
+
+  @functools.wraps(handler)
+  def CheckOriginHeader(self):
+    origin = self.request.headers.get('Origin')
+    if origin:
+      host = self.request.headers.get('Host')
+      possible_origins = {
+        'http://%s' % host,
+        'https://%s' % host,
+      }
+      if origin not in possible_origins:
+        self.error(403)
+        self.response.out.write('Origin/Host header mismatch')
+        return
+    return handler(self)
+
+  return CheckOriginHeader