1
0
forked from s434650/CatOrNot
CatOrNot/venv/lib/python3.6/site-packages/wtforms/ext/csrf/session.py

72 lines
2.6 KiB
Python
Raw Normal View History

2018-12-11 00:32:28 +01:00
"""
A provided CSRF implementation which puts CSRF data in a session.
This can be used fairly comfortably with many `request.session` type
objects, including the Werkzeug/Flask session store, Django sessions, and
potentially other similar objects which use a dict-like API for storing
session keys.
The basic concept is a randomly generated value is stored in the user's
session, and an hmac-sha1 of it (along with an optional expiration time,
for extra security) is used as the value of the csrf_token. If this token
validates with the hmac of the random value + expiration time, and the
expiration time is not passed, the CSRF validation will pass.
"""
from __future__ import unicode_literals
import hmac
import os
from hashlib import sha1
from datetime import datetime, timedelta
from ...validators import ValidationError
from .form import SecureForm
__all__ = ('SessionSecureForm', )
class SessionSecureForm(SecureForm):
TIME_FORMAT = '%Y%m%d%H%M%S'
TIME_LIMIT = timedelta(minutes=30)
SECRET_KEY = None
def generate_csrf_token(self, csrf_context):
if self.SECRET_KEY is None:
raise Exception('must set SECRET_KEY in a subclass of this form for it to work')
if csrf_context is None:
raise TypeError('Must provide a session-like object as csrf context')
session = getattr(csrf_context, 'session', csrf_context)
if 'csrf' not in session:
session['csrf'] = sha1(os.urandom(64)).hexdigest()
self.csrf_token.csrf_key = session['csrf']
if self.TIME_LIMIT:
expires = (datetime.now() + self.TIME_LIMIT).strftime(self.TIME_FORMAT)
csrf_build = '%s%s' % (session['csrf'], expires)
else:
expires = ''
csrf_build = session['csrf']
hmac_csrf = hmac.new(self.SECRET_KEY, csrf_build.encode('utf8'), digestmod=sha1)
return '%s##%s' % (expires, hmac_csrf.hexdigest())
def validate_csrf_token(self, field):
if not field.data or '##' not in field.data:
raise ValidationError(field.gettext('CSRF token missing'))
expires, hmac_csrf = field.data.split('##')
check_val = (field.csrf_key + expires).encode('utf8')
hmac_compare = hmac.new(self.SECRET_KEY, check_val, digestmod=sha1)
if hmac_compare.hexdigest() != hmac_csrf:
raise ValidationError(field.gettext('CSRF failed'))
if self.TIME_LIMIT:
now_formatted = datetime.now().strftime(self.TIME_FORMAT)
if now_formatted > expires:
raise ValidationError(field.gettext('CSRF token expired'))