94 lines
3.5 KiB
Python
94 lines
3.5 KiB
Python
from datetime import date
|
|
|
|
from django.conf import settings
|
|
from django.utils.crypto import constant_time_compare, salted_hmac
|
|
from django.utils.http import base36_to_int, int_to_base36
|
|
|
|
|
|
class PasswordResetTokenGenerator:
|
|
"""
|
|
Strategy object used to generate and check tokens for the password
|
|
reset mechanism.
|
|
"""
|
|
key_salt = "django.contrib.auth.tokens.PasswordResetTokenGenerator"
|
|
secret = settings.SECRET_KEY
|
|
|
|
def make_token(self, user):
|
|
"""
|
|
Return a token that can be used once to do a password reset
|
|
for the given user.
|
|
"""
|
|
return self._make_token_with_timestamp(user, self._num_days(self._today()))
|
|
|
|
def check_token(self, user, token):
|
|
"""
|
|
Check that a password reset token is correct for a given user.
|
|
"""
|
|
if not (user and token):
|
|
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/uid has not been tampered with
|
|
if not constant_time_compare(self._make_token_with_timestamp(user, ts), token):
|
|
return False
|
|
|
|
# Check the timestamp is within limit. Timestamps are rounded to
|
|
# midnight (server time) providing a resolution of only 1 day. If a
|
|
# link is generated 5 minutes before midnight and used 6 minutes later,
|
|
# that counts as 1 day. Therefore, PASSWORD_RESET_TIMEOUT_DAYS = 1 means
|
|
# "at least 1 day, could be up to 2."
|
|
if (self._num_days(self._today()) - ts) > settings.PASSWORD_RESET_TIMEOUT_DAYS:
|
|
return False
|
|
|
|
return True
|
|
|
|
def _make_token_with_timestamp(self, user, timestamp):
|
|
# timestamp is number of days since 2001-1-1. Converted to
|
|
# base 36, this gives us a 3 digit string until about 2121
|
|
ts_b36 = int_to_base36(timestamp)
|
|
hash = salted_hmac(
|
|
self.key_salt,
|
|
self._make_hash_value(user, timestamp),
|
|
secret=self.secret,
|
|
).hexdigest()[::2] # Limit to 20 characters to shorten the URL.
|
|
return "%s-%s" % (ts_b36, hash)
|
|
|
|
def _make_hash_value(self, user, timestamp):
|
|
"""
|
|
Hash the user's primary key and some user state that's sure to change
|
|
after a password reset to produce a token that invalidated when it's
|
|
used:
|
|
1. The password field will change upon a password reset (even if the
|
|
same password is chosen, due to password salting).
|
|
2. The last_login field will usually be updated very shortly after
|
|
a password reset.
|
|
Failing those things, settings.PASSWORD_RESET_TIMEOUT_DAYS eventually
|
|
invalidates the token.
|
|
|
|
Running this data through salted_hmac() prevents password cracking
|
|
attempts using the reset token, provided the secret isn't compromised.
|
|
"""
|
|
# Truncate microseconds so that tokens are consistent even if the
|
|
# database doesn't support microseconds.
|
|
login_timestamp = '' if user.last_login is None else user.last_login.replace(microsecond=0, tzinfo=None)
|
|
return str(user.pk) + user.password + str(login_timestamp) + str(timestamp)
|
|
|
|
def _num_days(self, dt):
|
|
return (dt - date(2001, 1, 1)).days
|
|
|
|
def _today(self):
|
|
# Used for mocking in tests
|
|
return date.today()
|
|
|
|
|
|
default_token_generator = PasswordResetTokenGenerator()
|