133 lines
4.2 KiB
Python
133 lines
4.2 KiB
Python
|
from datetime import datetime
|
||
|
|
|
||
|
|
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"
|
||
|
|
algorithm = None
|
||
|
|
_secret = None
|
||
|
|
_secret_fallbacks = None
|
||
|
|
|
||
|
|
def __init__(self):
|
||
|
|
self.algorithm = self.algorithm or "sha256"
|
||
|
|
|
||
|
|
def _get_secret(self):
|
||
|
|
return self._secret or settings.SECRET_KEY
|
||
|
|
|
||
|
|
def _set_secret(self, secret):
|
||
|
|
self._secret = secret
|
||
|
|
|
||
|
|
secret = property(_get_secret, _set_secret)
|
||
|
|
|
||
|
|
def _get_fallbacks(self):
|
||
|
|
if self._secret_fallbacks is None:
|
||
|
|
return settings.SECRET_KEY_FALLBACKS
|
||
|
|
return self._secret_fallbacks
|
||
|
|
|
||
|
|
def _set_fallbacks(self, fallbacks):
|
||
|
|
self._secret_fallbacks = fallbacks
|
||
|
|
|
||
|
|
secret_fallbacks = property(_get_fallbacks, _set_fallbacks)
|
||
|
|
|
||
|
|
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_seconds(self._now()),
|
||
|
|
self.secret,
|
||
|
|
)
|
||
|
|
|
||
|
|
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, _ = 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
|
||
|
|
for secret in [self.secret, *self.secret_fallbacks]:
|
||
|
|
if constant_time_compare(
|
||
|
|
self._make_token_with_timestamp(user, ts, secret),
|
||
|
|
token,
|
||
|
|
):
|
||
|
|
break
|
||
|
|
else:
|
||
|
|
return False
|
||
|
|
|
||
|
|
# Check the timestamp is within limit.
|
||
|
|
if (self._num_seconds(self._now()) - ts) > settings.PASSWORD_RESET_TIMEOUT:
|
||
|
|
return False
|
||
|
|
|
||
|
|
return True
|
||
|
|
|
||
|
|
def _make_token_with_timestamp(self, user, timestamp, secret):
|
||
|
|
# timestamp is number of seconds since 2001-1-1. Converted to base 36,
|
||
|
|
# this gives us a 6 digit string until about 2069.
|
||
|
|
ts_b36 = int_to_base36(timestamp)
|
||
|
|
hash_string = salted_hmac(
|
||
|
|
self.key_salt,
|
||
|
|
self._make_hash_value(user, timestamp),
|
||
|
|
secret=secret,
|
||
|
|
algorithm=self.algorithm,
|
||
|
|
).hexdigest()[
|
||
|
|
::2
|
||
|
|
] # Limit to shorten the URL.
|
||
|
|
return "%s-%s" % (ts_b36, hash_string)
|
||
|
|
|
||
|
|
def _make_hash_value(self, user, timestamp):
|
||
|
|
"""
|
||
|
|
Hash the user's primary key, email (if available), and some user state
|
||
|
|
that's sure to change after a password reset to produce a token that is
|
||
|
|
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 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)
|
||
|
|
)
|
||
|
|
email_field = user.get_email_field_name()
|
||
|
|
email = getattr(user, email_field, "") or ""
|
||
|
|
return f"{user.pk}{user.password}{login_timestamp}{timestamp}{email}"
|
||
|
|
|
||
|
|
def _num_seconds(self, dt):
|
||
|
|
return int((dt - datetime(2001, 1, 1)).total_seconds())
|
||
|
|
|
||
|
|
def _now(self):
|
||
|
|
# Used for mocking in tests
|
||
|
|
return datetime.now()
|
||
|
|
|
||
|
|
|
||
|
|
default_token_generator = PasswordResetTokenGenerator()
|