bbangert/velruse — pull request #98 by 2nd (2012-09-13 12:23:16+00:00)
Title: Fix CSRF vulnerability

Currently, OAuth providers are still vulnerable to CSRF attacks.
``` python
if request.GET.get('state') != request.session.get('state'):
raise CSRFError(
'CSRF Validation check failed. Request state %s is not '
'the same as session state %s' % (
request.GET.get('state'), request.session.get('state')))
```
This code is vulnerable, because None equals None.

Related article - http://homakov.blogspot.com/2012/07/saferweb-most-common-oauth2.html