# Copyright 2016 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style
# license that can be found in the LICENSE file or at
# https://developers.google.com/open-source/licenses/bsd

"""Tests for XSRF utility functions."""
from __future__ import print_function
from __future__ import division
from __future__ import absolute_import

import time
import unittest

from mock import patch

from google.appengine.ext import testbed

import settings
from framework import xsrf


class XsrfTest(unittest.TestCase):
  """Set of unit tests for blocking XSRF attacks."""

  def setUp(self):
    self.testbed = testbed.Testbed()
    self.testbed.activate()
    self.testbed.init_memcache_stub()
    self.testbed.init_datastore_v3_stub()

  def tearDown(self):
    self.testbed.deactivate()

  def testGenerateToken_AnonUserGetsAToken(self):
    self.assertNotEqual('', xsrf.GenerateToken(0, '/path'))

  def testGenerateToken_DifferentUsersGetDifferentTokens(self):
    self.assertNotEqual(
        xsrf.GenerateToken(111, '/path'),
        xsrf.GenerateToken(222, '/path'))

    self.assertNotEqual(
        xsrf.GenerateToken(111, '/path'),
        xsrf.GenerateToken(0, '/path'))

  def testGenerateToken_DifferentPathsGetDifferentTokens(self):
    self.assertNotEqual(
        xsrf.GenerateToken(111, '/path/one'),
        xsrf.GenerateToken(111, '/path/two'))

  def testValidToken(self):
    token = xsrf.GenerateToken(111, '/path')
    xsrf.ValidateToken(token, 111, '/path')  # no exception raised

  def testMalformedToken(self):
    self.assertRaises(
      xsrf.TokenIncorrect,
      xsrf.ValidateToken, 'bad', 111, '/path')
    self.assertRaises(
      xsrf.TokenIncorrect,
      xsrf.ValidateToken, '', 111, '/path')

    self.assertRaises(
        xsrf.TokenIncorrect,
        xsrf.ValidateToken, '098a08fe08b08c08a05e:9721973123', 111, '/path')

  def testWrongUser(self):
    token = xsrf.GenerateToken(111, '/path')
    self.assertRaises(
      xsrf.TokenIncorrect,
      xsrf.ValidateToken, token, 222, '/path')

  def testWrongPath(self):
    token = xsrf.GenerateToken(111, '/path/one')
    self.assertRaises(
      xsrf.TokenIncorrect,
      xsrf.ValidateToken, token, 111, '/path/two')

  @patch('time.time')
  def testValidateToken_Expiration(self, mockTime):
    test_time = 1526671379
    mockTime.return_value = test_time
    token = xsrf.GenerateToken(111, '/path')
    xsrf.ValidateToken(token, 111, '/path')

    mockTime.return_value = test_time + 1
    xsrf.ValidateToken(token, 111, '/path')

    mockTime.return_value = test_time + xsrf.TOKEN_TIMEOUT_SEC
    xsrf.ValidateToken(token, 111, '/path')

    mockTime.return_value = test_time + xsrf.TOKEN_TIMEOUT_SEC + 1
    self.assertRaises(
      xsrf.TokenIncorrect,
      xsrf.ValidateToken, token, 11, '/path')

  @patch('time.time')
  def testValidateToken_Future(self, mockTime):
    """We reject tokens from the future."""
    test_time = 1526671379
    mockTime.return_value = test_time
    token = xsrf.GenerateToken(111, '/path')
    xsrf.ValidateToken(token, 111, '/path')

    # The clock of the GAE instance doing the checking might be slightly slow.
    mockTime.return_value = test_time - 1
    xsrf.ValidateToken(token, 111, '/path')

    # But, if the difference is too much, someone is trying to fake a token.
    mockTime.return_value = test_time - xsrf.CLOCK_SKEW_SEC - 1
    self.assertRaises(
      xsrf.TokenIncorrect,
      xsrf.ValidateToken, token, 111, '/path')