3 files changed, 178 insertions, 1 deletions
diff --git a/mediagoblin/tools/crypto.py b/mediagoblin/tools/crypto.py
new file mode 100644
index 00000000..55811aea
--- /dev/null
+++ b/mediagoblin/tools/crypto.py
@@ -0,0 +1,110 @@
+# 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 errno
+import itsdangerous
+import logging
+import os.path
+import random
+import tempfile
+from mediagoblin import mg_globals
+
+_log = logging.getLogger(__name__)
+
+
+# Use the system (hardware-based) random number generator if it exists.
+# -- this optimization is lifted from Django
+try:
+    getrandbits = random.SystemRandom().getrandbits
+except AttributeError:
+    getrandbits = random.getrandbits
+
+
+__itsda_secret = None
+
+
+def load_key(filename):
+    global __itsda_secret
+    key_file = open(filename)
+    try:
+        __itsda_secret = key_file.read()
+    finally:
+        key_file.close()
+
+def create_key(key_dir, key_filepath):
+    global __itsda_secret
+    old_umask = os.umask(077)
+    key_file = None
+    try:
+        if not os.path.isdir(key_dir):
+            os.makedirs(key_dir)
+            _log.info("Created %s", dirname)
+        key = str(getrandbits(192))
+        key_file = tempfile.NamedTemporaryFile(dir=key_dir, suffix='.bin',
+                                               delete=False)
+        key_file.write(key)
+        key_file.flush()
+        os.rename(key_file.name, key_filepath)
+        key_file.close()
+    finally:
+        os.umask(old_umask)
+        if (key_file is not None) and (not key_file.closed):
+            key_file.close()
+            os.unlink(key_file.name)
+    __itsda_secret = key
+    _log.info("Saved new key for It's Dangerous")
+
+def setup_crypto():
+    global __itsda_secret
+    key_dir = mg_globals.app_config["crypto_path"]
+    key_filepath = os.path.join(key_dir, 'itsdangeroussecret.bin')
+    try:
+        load_key(key_filepath)
+    except IOError, error:
+        if error.errno != errno.ENOENT:
+            raise
+        create_key(key_dir, key_filepath)
+
+def get_timed_signer_url(namespace):
+    """
+    This gives a basic signing/verifying object.
+
+    The namespace makes sure signed tokens can't be used in
+    a different area. Like using a forgot-password-token as
+    a session cookie.
+
+    Basic usage:
+
+    .. code-block:: python
+
+       _signer = None
+       TOKEN_VALID_DAYS = 10
+       def setup():
+           global _signer
+           _signer = get_timed_signer_url("session cookie")
+       def create_token(obj):
+           return _signer.dumps(obj)
+       def parse_token(token):
+           # This might raise an exception in case
+           # of an invalid token, or an expired token.
+           return _signer.loads(token, max_age=TOKEN_VALID_DAYS*24*3600)
+
+    For more details see
+    http://pythonhosted.org/itsdangerous/#itsdangerous.URLSafeTimedSerializer
+    """
+    assert __itsda_secret is not None
+    return itsdangerous.URLSafeTimedSerializer(__itsda_secret,
+         salt=namespace)
diff --git a/mediagoblin/tools/request.py b/mediagoblin/tools/request.py
index bc67b96f..ee342eae 100644
--- a/mediagoblin/tools/request.py
+++ b/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()
diff --git a/mediagoblin/tools/session.py b/mediagoblin/tools/session.py
new file mode 100644
index 00000000..d452b851
--- /dev/null
+++ b/mediagoblin/tools/session.py
@@ -0,0 +1,67 @@
+# 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 __init__(self, *args, **kwargs):
+        self.send_new_cookie = False
+        dict.__init__(self, *args, **kwargs)
+
+    def save(self):
+        self.send_new_cookie = True
+
+    def is_updated(self):
+        return 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
+        elif not session:
+            response.delete_cookie(self.cookie_name)
+        else:
+            response.set_cookie(self.cookie_name, self.signer.dumps(session))