267 lines
9.2 KiB
Python
267 lines
9.2 KiB
Python
import functools
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import gzip
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import re
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from difflib import SequenceMatcher
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from pathlib import Path
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from django.conf import settings
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from django.core.exceptions import (
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FieldDoesNotExist,
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ImproperlyConfigured,
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ValidationError,
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)
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from django.utils.functional import cached_property, lazy
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from django.utils.html import format_html, format_html_join
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from django.utils.module_loading import import_string
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from django.utils.translation import gettext as _
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from django.utils.translation import ngettext
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@functools.lru_cache(maxsize=None)
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def get_default_password_validators():
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return get_password_validators(settings.AUTH_PASSWORD_VALIDATORS)
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def get_password_validators(validator_config):
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validators = []
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for validator in validator_config:
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try:
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klass = import_string(validator["NAME"])
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except ImportError:
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msg = (
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"The module in NAME could not be imported: %s. Check your "
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"AUTH_PASSWORD_VALIDATORS setting."
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)
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raise ImproperlyConfigured(msg % validator["NAME"])
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validators.append(klass(**validator.get("OPTIONS", {})))
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return validators
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def validate_password(password, user=None, password_validators=None):
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"""
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Validate that the password meets all validator requirements.
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If the password is valid, return ``None``.
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If the password is invalid, raise ValidationError with all error messages.
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"""
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errors = []
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if password_validators is None:
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password_validators = get_default_password_validators()
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for validator in password_validators:
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try:
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validator.validate(password, user)
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except ValidationError as error:
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errors.append(error)
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if errors:
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raise ValidationError(errors)
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def password_changed(password, user=None, password_validators=None):
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"""
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Inform all validators that have implemented a password_changed() method
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that the password has been changed.
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"""
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if password_validators is None:
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password_validators = get_default_password_validators()
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for validator in password_validators:
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password_changed = getattr(validator, "password_changed", lambda *a: None)
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password_changed(password, user)
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def password_validators_help_texts(password_validators=None):
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"""
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Return a list of all help texts of all configured validators.
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"""
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help_texts = []
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if password_validators is None:
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password_validators = get_default_password_validators()
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for validator in password_validators:
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help_texts.append(validator.get_help_text())
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return help_texts
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def _password_validators_help_text_html(password_validators=None):
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"""
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Return an HTML string with all help texts of all configured validators
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in an <ul>.
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"""
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help_texts = password_validators_help_texts(password_validators)
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help_items = format_html_join(
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"", "<li>{}</li>", ((help_text,) for help_text in help_texts)
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)
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return format_html("<ul>{}</ul>", help_items) if help_items else ""
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password_validators_help_text_html = lazy(_password_validators_help_text_html, str)
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class MinimumLengthValidator:
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"""
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Validate that the password is of a minimum length.
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"""
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def __init__(self, min_length=8):
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self.min_length = min_length
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def validate(self, password, user=None):
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if len(password) < self.min_length:
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raise ValidationError(
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ngettext(
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"This password is too short. It must contain at least "
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"%(min_length)d character.",
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"This password is too short. It must contain at least "
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"%(min_length)d characters.",
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self.min_length,
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),
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code="password_too_short",
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params={"min_length": self.min_length},
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)
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def get_help_text(self):
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return ngettext(
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"Your password must contain at least %(min_length)d character.",
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"Your password must contain at least %(min_length)d characters.",
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self.min_length,
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) % {"min_length": self.min_length}
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def exceeds_maximum_length_ratio(password, max_similarity, value):
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"""
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Test that value is within a reasonable range of password.
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The following ratio calculations are based on testing SequenceMatcher like
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this:
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for i in range(0,6):
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print(10**i, SequenceMatcher(a='A', b='A'*(10**i)).quick_ratio())
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which yields:
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1 1.0
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10 0.18181818181818182
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100 0.019801980198019802
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1000 0.001998001998001998
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10000 0.00019998000199980003
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100000 1.999980000199998e-05
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This means a length_ratio of 10 should never yield a similarity higher than
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0.2, for 100 this is down to 0.02 and for 1000 it is 0.002. This can be
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calculated via 2 / length_ratio. As a result we avoid the potentially
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expensive sequence matching.
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"""
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pwd_len = len(password)
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length_bound_similarity = max_similarity / 2 * pwd_len
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value_len = len(value)
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return pwd_len >= 10 * value_len and value_len < length_bound_similarity
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class UserAttributeSimilarityValidator:
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"""
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Validate that the password is sufficiently different from the user's
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attributes.
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If no specific attributes are provided, look at a sensible list of
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defaults. Attributes that don't exist are ignored. Comparison is made to
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not only the full attribute value, but also its components, so that, for
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example, a password is validated against either part of an email address,
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as well as the full address.
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"""
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DEFAULT_USER_ATTRIBUTES = ("username", "first_name", "last_name", "email")
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def __init__(self, user_attributes=DEFAULT_USER_ATTRIBUTES, max_similarity=0.7):
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self.user_attributes = user_attributes
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if max_similarity < 0.1:
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raise ValueError("max_similarity must be at least 0.1")
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self.max_similarity = max_similarity
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def validate(self, password, user=None):
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if not user:
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return
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password = password.lower()
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for attribute_name in self.user_attributes:
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value = getattr(user, attribute_name, None)
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if not value or not isinstance(value, str):
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continue
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value_lower = value.lower()
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value_parts = re.split(r"\W+", value_lower) + [value_lower]
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for value_part in value_parts:
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if exceeds_maximum_length_ratio(
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password, self.max_similarity, value_part
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):
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continue
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if (
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SequenceMatcher(a=password, b=value_part).quick_ratio()
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>= self.max_similarity
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):
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try:
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verbose_name = str(
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user._meta.get_field(attribute_name).verbose_name
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)
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except FieldDoesNotExist:
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verbose_name = attribute_name
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raise ValidationError(
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_("The password is too similar to the %(verbose_name)s."),
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code="password_too_similar",
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params={"verbose_name": verbose_name},
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)
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def get_help_text(self):
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return _(
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"Your password can’t be too similar to your other personal information."
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)
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class CommonPasswordValidator:
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"""
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Validate that the password is not a common password.
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The password is rejected if it occurs in a provided list of passwords,
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which may be gzipped. The list Django ships with contains 20000 common
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passwords (lowercased and deduplicated), created by Royce Williams:
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https://gist.github.com/roycewilliams/281ce539915a947a23db17137d91aeb7
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The password list must be lowercased to match the comparison in validate().
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"""
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@cached_property
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def DEFAULT_PASSWORD_LIST_PATH(self):
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return Path(__file__).resolve().parent / "common-passwords.txt.gz"
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def __init__(self, password_list_path=DEFAULT_PASSWORD_LIST_PATH):
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if password_list_path is CommonPasswordValidator.DEFAULT_PASSWORD_LIST_PATH:
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password_list_path = self.DEFAULT_PASSWORD_LIST_PATH
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try:
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with gzip.open(password_list_path, "rt", encoding="utf-8") as f:
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self.passwords = {x.strip() for x in f}
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except OSError:
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with open(password_list_path) as f:
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self.passwords = {x.strip() for x in f}
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def validate(self, password, user=None):
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if password.lower().strip() in self.passwords:
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raise ValidationError(
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_("This password is too common."),
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code="password_too_common",
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)
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def get_help_text(self):
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return _("Your password can’t be a commonly used password.")
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class NumericPasswordValidator:
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"""
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Validate that the password is not entirely numeric.
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"""
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def validate(self, password, user=None):
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if password.isdigit():
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raise ValidationError(
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_("This password is entirely numeric."),
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code="password_entirely_numeric",
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)
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def get_help_text(self):
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return _("Your password can’t be entirely numeric.")
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