+"""
+Based on django.contrib.auth.tokens
+"""
+
+
+from datetime import date
+from django.conf import settings
+from django.utils.http import int_to_base36, base36_to_int
+from django.contrib.auth.tokens import PasswordResetTokenGenerator
+
+
+REGISTRATION_TIMEOUT_DAYS = getattr(settings, 'WALDO_REGISTRATION_TIMEOUT_DAYS', 1)
+
+
+class RegistrationTokenGenerator(PasswordResetTokenGenerator):
+ """
+ Strategy object used to generate and check tokens for the user registration mechanism.
+ """
+ def make_token(self, user):
+ """
+ Returns a token that can be used once to activate a user's account.
+ """
+ if user.is_active:
+ return False
+ return self._make_token_with_timestamp(user, self._num_days(self._today()))
+
+ def check_token(self, user, token):
+ """
+ Check that a registration token is correct for a given user.
+ """
+ # If the user is active, the hash can't be valid.
+ if user.is_active:
+ return False
+
+ # Parse the token
+ try:
+ ts_b36, hash = token.split('-')
+ except ValueError:
+ return False
+
+ try:
+ ts = base36_to_int(ts_b36)
+ except ValueError:
+ return False
+
+ # Check that the timestamp and uid have not been tampered with.
+ if self._make_token_with_timestamp(user, ts) != token:
+ return False
+
+ # Check that the timestamp is within limit
+ if (self._num_days(self._today()) - ts) > REGISTRATION_TIMEOUT_DAYS:
+ return False
+
+ return True
+
+ def _make_token_with_timestamp(self, user, timestamp):
+ ts_b36 = int_to_base36(timestamp)
+
+ # By hashing on the internal state of the user and using state that is
+ # sure to change, we produce a hash that will be invalid as soon as it
+ # is used.
+ from django.utils.hashcompat import sha_constructor
+ hash = sha_constructor(settings.SECRET_KEY + unicode(user.id) + unicode(user.is_active) + user.last_login.strftime('%Y-%m-%d %H:%M:%S') + unicode(timestamp)).hexdigest()[::2]
+ return '%s-%s' % (ts_b36, hash)
+
+default_token_generator = RegistrationTokenGenerator()
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