Back sessions with It's Dangerous.

This is a contribution to #668.

mediagoblin/app.py

@@ -25,7 +25,7 @@ from werkzeug.exceptions import HTTPException
 from werkzeug.routing import RequestRedirect
 
 from mediagoblin import meddleware, __version__
-from mediagoblin.tools import common, translate, template
+from mediagoblin.tools import common, session, translate, template
 from mediagoblin.tools.response import render_http_exception
 from mediagoblin.tools.theme import register_themes
 from mediagoblin.tools import request as mg_request
@@ -160,7 +160,8 @@ class MediaGoblinApp(object):
 
         ## Attach utilities to the request object
         # Do we really want to load this via middleware?  Maybe?
-        request.session = request.environ['beaker.session']
+        session_manager = session.SessionManager()
+        request.session = session_manager.load_session_from_cookie(request)
         # Attach self as request.app
         # Also attach a few utilities from request.app for convenience?
         request.app = self
@@ -229,6 +230,8 @@ class MediaGoblinApp(object):
             response = render_http_exeption(
                 request, e, e.get_description(environ))
 
+        session_manager.save_session_to_cookie(request.session, response)
+
         return response(environ, start_response)
 
     def __call__(self, environ, start_response):

mediagoblin/tools/request.py

@@ -35,4 +35,4 @@ def setup_user_in_request(request):
         # Something's wrong... this user doesn't exist?  Invalidate
         # this session.
         _log.warn("Killing session for user id %r", request.session['user_id'])
-        request.session.invalidate()
+        request.session.delete()

mediagoblin/tools/session.py

@@ -0,0 +1,60 @@
+# GNU MediaGoblin -- federated, autonomous media hosting
+# Copyright (C) 2013 MediaGoblin contributors.  See AUTHORS.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import itsdangerous
+import logging
+
+import crypto
+
+_log = logging.getLogger(__name__)
+
+class Session(dict):
+    def save(self):
+        self.send_new_cookie = True
+
+    def is_updated(self):
+        return getattr(self, 'send_new_cookie')
+
+    def delete(self):
+        self.clear()
+        self.save()
+
+
+class SessionManager(object):
+    def __init__(self, cookie_name='MGSession', namespace=None):
+        if namespace is None:
+            namespace = cookie_name
+        self.signer = crypto.get_timed_signer_url(namespace)
+        self.cookie_name = cookie_name
+
+    def load_session_from_cookie(self, request):
+        cookie = request.cookies.get(self.cookie_name)
+        if not cookie:
+            return Session()
+        ### FIXME: Future cookie-blacklisting code
+        # m = BadCookie.query.filter_by(cookie = cookie)
+        # if m:
+        #     _log.warn("Bad cookie received: %s", m.reason)
+        #     raise BadRequest()
+        try:
+            return Session(self.signer.loads(cookie))
+        except itsdangerous.BadData:
+            return Session()
+
+    def save_session_to_cookie(self, session, response):
+        if not session.is_updated:
+            return
+        response.set_cookie(self.cookie_name, self.signer.dumps(session))

setup.py

@@ -60,6 +60,7 @@ setup(
         'sqlalchemy>=0.7.0',
         'sqlalchemy-migrate',
         'mock',
+        'itsdangerous',
         ## This is optional!
         # 'translitcodec',
         ## For now we're expecting that users will install this from