File: authentication.py

package info (click to toggle)
python-pyramid 1.6+dfsg-1
  • links: PTS, VCS
  • area: main
  • in suites: stretch
  • size: 9,112 kB
  • ctags: 8,169
  • sloc: python: 41,764; makefile: 111; sh: 17
file content (1189 lines) | stat: -rw-r--r-- 43,073 bytes parent folder | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
import binascii
from codecs import utf_8_decode
from codecs import utf_8_encode
import hashlib
import base64
import re
import time as time_mod
import warnings

from zope.interface import implementer

from webob.cookies import CookieProfile

from pyramid.compat import (
    long,
    text_type,
    binary_type,
    url_unquote,
    url_quote,
    bytes_,
    ascii_native_,
    native_,
    )

from pyramid.interfaces import (
    IAuthenticationPolicy,
    IDebugLogger,
    )

from pyramid.security import (
    Authenticated,
    Everyone,
    )

from pyramid.util import strings_differ

VALID_TOKEN = re.compile(r"^[A-Za-z][A-Za-z0-9+_-]*$")

class CallbackAuthenticationPolicy(object):
    """ Abstract class """

    debug = False
    callback = None

    def _log(self, msg, methodname, request):
        logger = request.registry.queryUtility(IDebugLogger)
        if logger:
            cls = self.__class__
            classname = cls.__module__ + '.' + cls.__name__
            methodname = classname + '.' + methodname
            logger.debug(methodname + ': ' + msg)

    def _clean_principal(self, princid):
        if princid in (Authenticated, Everyone):
            princid = None
        return princid

    def authenticated_userid(self, request):
        """ Return the authenticated userid or ``None``.

        If no callback is registered, this will be the same as
        ``unauthenticated_userid``.

        If a ``callback`` is registered, this will return the userid if
        and only if the callback returns a value that is not ``None``.

        """
        debug = self.debug
        userid = self.unauthenticated_userid(request)
        if userid is None:
            debug and self._log(
                'call to unauthenticated_userid returned None; returning None',
                'authenticated_userid',
                request)
            return None
        if self._clean_principal(userid) is None:
            debug and self._log(
                ('use of userid %r is disallowed by any built-in Pyramid '
                 'security policy, returning None' % userid),
                'authenticated_userid' ,
                request)
            return None
            
        if self.callback is None:
            debug and self._log(
                'there was no groupfinder callback; returning %r' % (userid,),
                'authenticated_userid',
                request)
            return userid
        callback_ok = self.callback(userid, request)
        if callback_ok is not None: # is not None!
            debug and self._log(
                'groupfinder callback returned %r; returning %r' % (
                    callback_ok, userid),
                'authenticated_userid',
                request
                )
            return userid
        debug and self._log(
            'groupfinder callback returned None; returning None',
            'authenticated_userid',
            request
            )

    def effective_principals(self, request):
        """ A list of effective principals derived from request.

        This will return a list of principals including, at least,
        :data:`pyramid.security.Everyone`. If there is no authenticated
        userid, or the ``callback`` returns ``None``, this will be the
        only principal:

        .. code-block:: python

            return [Everyone]

        If the ``callback`` does not return ``None`` and an authenticated
        userid is found, then the principals will include
        :data:`pyramid.security.Authenticated`, the ``authenticated_userid``
        and the list of principals returned by the ``callback``:

        .. code-block:: python

            extra_principals = callback(userid, request)
            return [Everyone, Authenticated, userid] + extra_principals

        """
        debug = self.debug
        effective_principals = [Everyone]
        userid = self.unauthenticated_userid(request)

        if userid is None:
            debug and self._log(
                'unauthenticated_userid returned %r; returning %r' % (
                    userid, effective_principals),
                'effective_principals',
                request
                )
            return effective_principals

        if self._clean_principal(userid) is None:
            debug and self._log(
                ('unauthenticated_userid returned disallowed %r; returning %r '
                 'as if it was None' % (userid, effective_principals)),
                'effective_principals',
                request
                )
            return effective_principals
            
        if self.callback is None:
            debug and self._log(
                'groupfinder callback is None, so groups is []',
                'effective_principals',
                request)
            groups = []
        else:
            groups = self.callback(userid, request)
            debug and self._log(
                'groupfinder callback returned %r as groups' % (groups,),
                'effective_principals',
                request)

        if groups is None: # is None!
            debug and self._log(
                'returning effective principals: %r' % (
                    effective_principals,),
                'effective_principals',
                request
                )
            return effective_principals

        effective_principals.append(Authenticated)
        effective_principals.append(userid)
        effective_principals.extend(groups)

        debug and self._log(
            'returning effective principals: %r' % (
                effective_principals,),
            'effective_principals',
            request
             )
        return effective_principals

@implementer(IAuthenticationPolicy)
class RepozeWho1AuthenticationPolicy(CallbackAuthenticationPolicy):
    """ A :app:`Pyramid` :term:`authentication policy` which
    obtains data from the :mod:`repoze.who` 1.X WSGI 'API' (the
    ``repoze.who.identity`` key in the WSGI environment).

    Constructor Arguments

    ``identifier_name``

       Default: ``auth_tkt``.  The :mod:`repoze.who` plugin name that
       performs remember/forget.  Optional.

    ``callback``

        Default: ``None``.  A callback passed the :mod:`repoze.who` identity
        and the :term:`request`, expected to return ``None`` if the user
        represented by the identity doesn't exist or a sequence of principal
        identifiers (possibly empty) representing groups if the user does
        exist.  If ``callback`` is None, the userid will be assumed to exist
        with no group principals.

    Objects of this class implement the interface described by
    :class:`pyramid.interfaces.IAuthenticationPolicy`.
    """

    def __init__(self, identifier_name='auth_tkt', callback=None):
        self.identifier_name = identifier_name
        self.callback = callback

    def _get_identity(self, request):
        return request.environ.get('repoze.who.identity')

    def _get_identifier(self, request):
        plugins = request.environ.get('repoze.who.plugins')
        if plugins is None:
            return None
        identifier = plugins[self.identifier_name]
        return identifier

    def authenticated_userid(self, request):
        """ Return the authenticated userid or ``None``.

        If no callback is registered, this will be the same as
        ``unauthenticated_userid``.

        If a ``callback`` is registered, this will return the userid if
        and only if the callback returns a value that is not ``None``.

        """
        identity = self._get_identity(request)

        if identity is None:
            self.debug and self._log(
                'repoze.who identity is None, returning None',
                'authenticated_userid',
                request)
            return None

        userid = identity['repoze.who.userid']

        if userid is None:
            self.debug and self._log(
                'repoze.who.userid is None, returning None' % userid,
                'authenticated_userid',
                request)
            return None
            
        if self._clean_principal(userid) is None:
            self.debug and self._log(
                ('use of userid %r is disallowed by any built-in Pyramid '
                 'security policy, returning None' % userid),
                'authenticated_userid',
                request)
            return None

        if self.callback is None:
            return userid

        if self.callback(identity, request) is not None: # is not None!
            return userid

    def unauthenticated_userid(self, request):
        """ Return the ``repoze.who.userid`` key from the detected identity."""
        identity = self._get_identity(request)
        if identity is None:
            return None
        return identity['repoze.who.userid']

    def effective_principals(self, request):
        """ A list of effective principals derived from the identity.

        This will return a list of principals including, at least,
        :data:`pyramid.security.Everyone`. If there is no identity, or
        the ``callback`` returns ``None``, this will be the only principal.

        If the ``callback`` does not return ``None`` and an identity is
        found, then the principals will include
        :data:`pyramid.security.Authenticated`, the ``authenticated_userid``
        and the list of principals returned by the ``callback``.

        """
        effective_principals = [Everyone]
        identity = self._get_identity(request)

        if identity is None:
            self.debug and self._log(
                ('repoze.who identity was None; returning %r' %
                 effective_principals),
                'effective_principals',
                request
                )
            return effective_principals

        if self.callback is None:
            groups = []
        else:
            groups = self.callback(identity, request)

        if groups is None: # is None!
            self.debug and self._log(
                ('security policy groups callback returned None; returning %r' %
                 effective_principals),
                'effective_principals',
                request
                )
            return effective_principals

        userid = identity['repoze.who.userid']

        if userid is None:
            self.debug and self._log(
                ('repoze.who.userid was None; returning %r' %
                 effective_principals),
                'effective_principals',
                request
                )
            return effective_principals

        if self._clean_principal(userid) is None:
            self.debug and self._log(
                ('unauthenticated_userid returned disallowed %r; returning %r '
                 'as if it was None' % (userid, effective_principals)),
                'effective_principals',
                request
                )
            return effective_principals

        effective_principals.append(Authenticated)
        effective_principals.append(userid)
        effective_principals.extend(groups)
        return effective_principals

    def remember(self, request, userid, **kw):
        """ Store the ``userid`` as ``repoze.who.userid``.
        
        The identity to authenticated to :mod:`repoze.who`
        will contain the given userid as ``userid``, and
        provide all keyword arguments as additional identity
        keys. Useful keys could be ``max_age`` or ``userdata``.
        """
        identifier = self._get_identifier(request)
        if identifier is None:
            return []
        environ = request.environ
        identity = kw
        identity['repoze.who.userid'] = userid
        return identifier.remember(environ, identity)

    def forget(self, request):
        """ Forget the current authenticated user.

        Return headers that, if included in a response, will delete the
        cookie responsible for tracking the current user.

        """
        identifier = self._get_identifier(request)
        if identifier is None:
            return []
        identity = self._get_identity(request)
        return identifier.forget(request.environ, identity)

@implementer(IAuthenticationPolicy)
class RemoteUserAuthenticationPolicy(CallbackAuthenticationPolicy):
    """ A :app:`Pyramid` :term:`authentication policy` which
    obtains data from the ``REMOTE_USER`` WSGI environment variable.

    Constructor Arguments

    ``environ_key``

        Default: ``REMOTE_USER``.  The key in the WSGI environ which
        provides the userid.

    ``callback``

        Default: ``None``.  A callback passed the userid and the request,
        expected to return None if the userid doesn't exist or a sequence of
        principal identifiers (possibly empty) representing groups if the
        user does exist.  If ``callback`` is None, the userid will be assumed
        to exist with no group principals.

    ``debug``

        Default: ``False``.  If ``debug`` is ``True``, log messages to the
        Pyramid debug logger about the results of various authentication
        steps.  The output from debugging is useful for reporting to maillist
        or IRC channels when asking for support.

    Objects of this class implement the interface described by
    :class:`pyramid.interfaces.IAuthenticationPolicy`.
    """

    def __init__(self, environ_key='REMOTE_USER', callback=None, debug=False):
        self.environ_key = environ_key
        self.callback = callback
        self.debug = debug

    def unauthenticated_userid(self, request):
        """ The ``REMOTE_USER`` value found within the ``environ``."""
        return request.environ.get(self.environ_key)

    def remember(self, request, userid, **kw):
        """ A no-op. The ``REMOTE_USER`` does not provide a protocol for
        remembering the user. This will be application-specific and can
        be done somewhere else or in a subclass."""
        return []

    def forget(self, request):
        """ A no-op. The ``REMOTE_USER`` does not provide a protocol for
        forgetting the user. This will be application-specific and can
        be done somewhere else or in a subclass."""
        return []

_marker = object()

@implementer(IAuthenticationPolicy)
class AuthTktAuthenticationPolicy(CallbackAuthenticationPolicy):
    """A :app:`Pyramid` :term:`authentication policy` which
    obtains data from a Pyramid "auth ticket" cookie.

    .. warning::

       The default hash algorithm used in this policy is MD5 and has known
       hash collision vulnerabilities. The risk of an exploit is low.
       However, for improved authentication security, use
       ``hashalg='sha512'``.

    Constructor Arguments

    ``secret``

       The secret (a string) used for auth_tkt cookie signing.  This value
       should be unique across all values provided to Pyramid for various
       subsystem secrets (see :ref:`admonishment_against_secret_sharing`).
       Required.

    ``callback``

       Default: ``None``.  A callback passed the userid and the
       request, expected to return ``None`` if the userid doesn't
       exist or a sequence of principal identifiers (possibly empty) if
       the user does exist.  If ``callback`` is ``None``, the userid
       will be assumed to exist with no principals.  Optional.

    ``cookie_name``

       Default: ``auth_tkt``.  The cookie name used
       (string).  Optional.

    ``secure``

       Default: ``False``.  Only send the cookie back over a secure
       conn.  Optional.

    ``include_ip``

       Default: ``False``.  Make the requesting IP address part of
       the authentication data in the cookie.  Optional.

       For IPv6 this option is not recommended. The ``mod_auth_tkt``
       specification does not specify how to handle IPv6 addresses, so using
       this option in combination with IPv6 addresses may cause an
       incompatible cookie. It ties the authentication ticket to that
       individual's IPv6 address.

    ``timeout``

       Default: ``None``.  Maximum number of seconds which a newly
       issued ticket will be considered valid.  After this amount of
       time, the ticket will expire (effectively logging the user
       out).  If this value is ``None``, the ticket never expires.
       Optional.

    ``reissue_time``

       Default: ``None``.  If this parameter is set, it represents the number
       of seconds that must pass before an authentication token cookie is
       automatically reissued as the result of a request which requires
       authentication.  The duration is measured as the number of seconds
       since the last auth_tkt cookie was issued and 'now'.  If this value is
       ``0``, a new ticket cookie will be reissued on every request which
       requires authentication.

       A good rule of thumb: if you want auto-expired cookies based on
       inactivity: set the ``timeout`` value to 1200 (20 mins) and set the
       ``reissue_time`` value to perhaps a tenth of the ``timeout`` value
       (120 or 2 mins).  It's nonsensical to set the ``timeout`` value lower
       than the ``reissue_time`` value, as the ticket will never be reissued
       if so.  However, such a configuration is not explicitly prevented.

       Optional.

    ``max_age``

       Default: ``None``.  The max age of the auth_tkt cookie, in
       seconds.  This differs from ``timeout`` inasmuch as ``timeout``
       represents the lifetime of the ticket contained in the cookie,
       while this value represents the lifetime of the cookie itself.
       When this value is set, the cookie's ``Max-Age`` and
       ``Expires`` settings will be set, allowing the auth_tkt cookie
       to last between browser sessions.  It is typically nonsensical
       to set this to a value that is lower than ``timeout`` or
       ``reissue_time``, although it is not explicitly prevented.
       Optional.

    ``path``

       Default: ``/``. The path for which the auth_tkt cookie is valid.
       May be desirable if the application only serves part of a domain.
       Optional.

    ``http_only``

       Default: ``False``. Hide cookie from JavaScript by setting the
       HttpOnly flag. Not honored by all browsers.
       Optional.

    ``wild_domain``

       Default: ``True``. An auth_tkt cookie will be generated for the
       wildcard domain. If your site is hosted as ``example.com`` this
       will make the cookie available for sites underneath ``example.com``
       such as ``www.example.com``.
       Optional.

    ``parent_domain``

       Default: ``False``. An auth_tkt cookie will be generated for the
       parent domain of the current site. For example if your site is
       hosted under ``www.example.com`` a cookie will be generated for
       ``.example.com``. This can be useful if you have multiple sites
       sharing the same domain. This option supercedes the ``wild_domain``
       option.
       Optional.

       This option is available as of :app:`Pyramid` 1.5.

    ``domain``

       Default: ``None``. If provided the auth_tkt cookie will only be
       set for this domain. This option is not compatible with ``wild_domain``
       and ``parent_domain``.
       Optional.

       This option is available as of :app:`Pyramid` 1.5.

    ``hashalg``

       Default: ``md5`` (the literal string).

       Any hash algorithm supported by Python's ``hashlib.new()`` function
       can be used as the ``hashalg``.

       Cookies generated by different instances of AuthTktAuthenticationPolicy
       using different ``hashalg`` options are not compatible. Switching the
       ``hashalg`` will imply that all existing users with a valid cookie will
       be required to re-login.

       A warning is emitted at startup if an explicit ``hashalg`` is not
       passed.  This is for backwards compatibility reasons.

       This option is available as of :app:`Pyramid` 1.4.

       Optional.

       .. note::

          ``md5`` is the default for backwards compatibility reasons. However,
          if you don't specify ``md5`` as the hashalg explicitly, a warning is
          issued at application startup time.  An explicit value of ``sha512``
          is recommended for improved security, and ``sha512`` will become the
          default in a future Pyramid version.

    ``debug``

        Default: ``False``.  If ``debug`` is ``True``, log messages to the
        Pyramid debug logger about the results of various authentication
        steps.  The output from debugging is useful for reporting to maillist
        or IRC channels when asking for support.

    Objects of this class implement the interface described by
    :class:`pyramid.interfaces.IAuthenticationPolicy`.
    """

    def __init__(self,
                 secret,
                 callback=None,
                 cookie_name='auth_tkt',
                 secure=False,
                 include_ip=False,
                 timeout=None,
                 reissue_time=None,
                 max_age=None,
                 path="/",
                 http_only=False,
                 wild_domain=True,
                 debug=False,
                 hashalg=_marker,
                 parent_domain=False,
                 domain=None,
                 ):
        if hashalg is _marker:
            hashalg = 'md5'
            warnings.warn(
                'The MD5 hash function used by default by the '
                'AuthTktAuthenticationPolicy is known to be '
                'susceptible to collision attacks.  It is the current default '
                'for backwards compatibility reasons, but we recommend that '
                'you use the SHA512 algorithm instead for improved security.  '
                'Pass ``hashalg=\'sha512\'`` to the '
                'AuthTktAuthenticationPolicy constructor to do so.\n\nNote '
                'that a change to the hash algorithms will invalidate existing '
                'auth tkt cookies set by your application.  If backwards '
                'compatibility of existing auth tkt cookies is of greater '
                'concern than the risk posed by the potential for a hash '
                'collision, you\'ll want to continue using MD5 explicitly.  '
                'To do so, pass ``hashalg=\'md5\'`` in your application to '
                'the AuthTktAuthenticationPolicy constructor.   When you do so '
                'this warning will not be emitted again.  The default '
                'algorithm used in this policy will change in the future, so '
                'setting an explicit hashalg will futureproof your '
                'application.',
                DeprecationWarning,
                stacklevel=2
                )
        self.cookie = AuthTktCookieHelper(
            secret,
            cookie_name=cookie_name,
            secure=secure,
            include_ip=include_ip,
            timeout=timeout,
            reissue_time=reissue_time,
            max_age=max_age,
            http_only=http_only,
            path=path,
            wild_domain=wild_domain,
            hashalg=hashalg,
            parent_domain=parent_domain,
            domain=domain,
            )
        self.callback = callback
        self.debug = debug

    def unauthenticated_userid(self, request):
        """ The userid key within the auth_tkt cookie."""
        result = self.cookie.identify(request)
        if result:
            return result['userid']

    def remember(self, request, userid, **kw):
        """ Accepts the following kw args: ``max_age=<int-seconds>,
        ``tokens=<sequence-of-ascii-strings>``.

        Return a list of headers which will set appropriate cookies on
        the response.

        """
        return self.cookie.remember(request, userid, **kw)

    def forget(self, request):
        """ A list of headers which will delete appropriate cookies."""
        return self.cookie.forget(request)

def b64encode(v):
    return base64.b64encode(bytes_(v)).strip().replace(b'\n', b'')

def b64decode(v):
    return base64.b64decode(bytes_(v))

# this class licensed under the MIT license (stolen from Paste)
class AuthTicket(object):
    """
    This class represents an authentication token.  You must pass in
    the shared secret, the userid, and the IP address.  Optionally you
    can include tokens (a list of strings, representing role names),
    'user_data', which is arbitrary data available for your own use in
    later scripts.  Lastly, you can override the cookie name and
    timestamp.

    Once you provide all the arguments, use .cookie_value() to
    generate the appropriate authentication ticket.

    Usage::

        token = AuthTicket('sharedsecret', 'username',
            os.environ['REMOTE_ADDR'], tokens=['admin'])
        val = token.cookie_value()

    """

    def __init__(self, secret, userid, ip, tokens=(), user_data='',
                 time=None, cookie_name='auth_tkt', secure=False,
                 hashalg='md5'):
        self.secret = secret
        self.userid = userid
        self.ip = ip
        self.tokens = ','.join(tokens)
        self.user_data = user_data
        if time is None:
            self.time = time_mod.time()
        else:
            self.time = time
        self.cookie_name = cookie_name
        self.secure = secure
        self.hashalg = hashalg

    def digest(self):
        return calculate_digest(
            self.ip, self.time, self.secret, self.userid, self.tokens,
            self.user_data, self.hashalg)

    def cookie_value(self):
        v = '%s%08x%s!' % (self.digest(), int(self.time),
                           url_quote(self.userid))
        if self.tokens:
            v += self.tokens + '!'
        v += self.user_data
        return v

# this class licensed under the MIT license (stolen from Paste)
class BadTicket(Exception):
    """
    Exception raised when a ticket can't be parsed.  If we get far enough to
    determine what the expected digest should have been, expected is set.
    This should not be shown by default, but can be useful for debugging.
    """
    def __init__(self, msg, expected=None):
        self.expected = expected
        Exception.__init__(self, msg)

# this function licensed under the MIT license (stolen from Paste)
def parse_ticket(secret, ticket, ip, hashalg='md5'):
    """
    Parse the ticket, returning (timestamp, userid, tokens, user_data).

    If the ticket cannot be parsed, a ``BadTicket`` exception will be raised
    with an explanation.
    """
    ticket = native_(ticket).strip('"')
    digest_size = hashlib.new(hashalg).digest_size * 2
    digest = ticket[:digest_size]
    try:
        timestamp = int(ticket[digest_size:digest_size + 8], 16)
    except ValueError as e:
        raise BadTicket('Timestamp is not a hex integer: %s' % e)
    try:
        userid, data = ticket[digest_size + 8:].split('!', 1)
    except ValueError:
        raise BadTicket('userid is not followed by !')
    userid = url_unquote(userid)
    if '!' in data:
        tokens, user_data = data.split('!', 1)
    else: # pragma: no cover (never generated)
        # @@: Is this the right order?
        tokens = ''
        user_data = data

    expected = calculate_digest(ip, timestamp, secret,
                                userid, tokens, user_data, hashalg)

    # Avoid timing attacks (see
    # http://seb.dbzteam.org/crypto/python-oauth-timing-hmac.pdf)
    if strings_differ(expected, digest):
        raise BadTicket('Digest signature is not correct',
                        expected=(expected, digest))

    tokens = tokens.split(',')

    return (timestamp, userid, tokens, user_data)

# this function licensed under the MIT license (stolen from Paste)
def calculate_digest(ip, timestamp, secret, userid, tokens, user_data,
                     hashalg='md5'):
    secret = bytes_(secret, 'utf-8')
    userid = bytes_(userid, 'utf-8')
    tokens = bytes_(tokens, 'utf-8')
    user_data = bytes_(user_data, 'utf-8')
    hash_obj = hashlib.new(hashalg)

    # Check to see if this is an IPv6 address
    if ':' in ip:
        ip_timestamp = ip + str(int(timestamp))
        ip_timestamp = bytes_(ip_timestamp)
    else:
        # encode_ip_timestamp not required, left in for backwards compatibility
        ip_timestamp = encode_ip_timestamp(ip, timestamp)

    hash_obj.update(ip_timestamp + secret + userid + b'\0' +
            tokens + b'\0' + user_data)
    digest = hash_obj.hexdigest()
    hash_obj2 = hashlib.new(hashalg)
    hash_obj2.update(bytes_(digest) + secret)
    return hash_obj2.hexdigest()

# this function licensed under the MIT license (stolen from Paste)
def encode_ip_timestamp(ip, timestamp):
    ip_chars = ''.join(map(chr, map(int, ip.split('.'))))
    t = int(timestamp)
    ts = ((t & 0xff000000) >> 24,
          (t & 0xff0000) >> 16,
          (t & 0xff00) >> 8,
          t & 0xff)
    ts_chars = ''.join(map(chr, ts))
    return bytes_(ip_chars + ts_chars)

class AuthTktCookieHelper(object):
    """
    A helper class for use in third-party authentication policy
    implementations.  See
    :class:`pyramid.authentication.AuthTktAuthenticationPolicy` for the
    meanings of the constructor arguments.
    """
    parse_ticket = staticmethod(parse_ticket) # for tests
    AuthTicket = AuthTicket # for tests
    BadTicket = BadTicket # for tests
    now = None # for tests

    userid_type_decoders = {
        'int':int,
        'unicode':lambda x: utf_8_decode(x)[0], # bw compat for old cookies
        'b64unicode': lambda x: utf_8_decode(b64decode(x))[0],
        'b64str': lambda x: b64decode(x),
        }

    userid_type_encoders = {
        int: ('int', str),
        long: ('int', str),
        text_type: ('b64unicode', lambda x: b64encode(utf_8_encode(x)[0])),
        binary_type: ('b64str', lambda x: b64encode(x)),
        }

    def __init__(self, secret, cookie_name='auth_tkt', secure=False,
                 include_ip=False, timeout=None, reissue_time=None,
                 max_age=None, http_only=False, path="/", wild_domain=True,
                 hashalg='md5', parent_domain=False, domain=None):

        serializer = _SimpleSerializer()
            
        self.cookie_profile = CookieProfile(
            cookie_name = cookie_name,
            secure = secure,
            max_age = max_age,
            httponly = http_only,
            path = path,
            serializer=serializer
            )

        self.secret = secret
        self.cookie_name = cookie_name
        self.secure = secure
        self.include_ip = include_ip
        self.timeout = timeout if timeout is None else int(timeout)
        self.reissue_time = reissue_time if reissue_time is None else int(reissue_time)
        self.max_age = max_age if max_age is None else int(max_age)
        self.wild_domain = wild_domain
        self.parent_domain = parent_domain
        self.domain = domain
        self.hashalg = hashalg

    def _get_cookies(self, request, value, max_age=None):
        cur_domain = request.domain

        domains = []
        if self.domain:
            domains.append(self.domain)
        else:
            if self.parent_domain and cur_domain.count('.') > 1:
                domains.append('.' + cur_domain.split('.', 1)[1])
            else:
                domains.append(None)
                domains.append(cur_domain)
                if self.wild_domain:
                    domains.append('.' + cur_domain)

        profile = self.cookie_profile(request)

        kw = {}
        kw['domains'] = domains
        if max_age is not None:
            kw['max_age'] = max_age
            
        headers = profile.get_headers(value, **kw)
        return headers

    def identify(self, request):
        """ Return a dictionary with authentication information, or ``None``
        if no valid auth_tkt is attached to ``request``"""
        environ = request.environ
        cookie = request.cookies.get(self.cookie_name)

        if cookie is None:
            return None

        if self.include_ip:
            remote_addr = environ['REMOTE_ADDR']
        else:
            remote_addr = '0.0.0.0'

        try:
            timestamp, userid, tokens, user_data = self.parse_ticket(
                self.secret, cookie, remote_addr, self.hashalg)
        except self.BadTicket:
            return None

        now = self.now # service tests

        if now is None:
            now = time_mod.time()

        if self.timeout and ( (timestamp + self.timeout) < now ):
            # the auth_tkt data has expired
            return None

        userid_typename = 'userid_type:'
        user_data_info = user_data.split('|')
        for datum in filter(None, user_data_info):
            if datum.startswith(userid_typename):
                userid_type = datum[len(userid_typename):]
                decoder = self.userid_type_decoders.get(userid_type)
                if decoder:
                    userid = decoder(userid)

        reissue = self.reissue_time is not None

        if reissue and not hasattr(request, '_authtkt_reissued'):
            if ( (now - timestamp) > self.reissue_time ):
                # See https://github.com/Pylons/pyramid/issues#issue/108
                tokens = list(filter(None, tokens))
                headers = self.remember(request, userid, max_age=self.max_age,
                                        tokens=tokens)
                def reissue_authtkt(request, response):
                    if not hasattr(request, '_authtkt_reissue_revoked'):
                        for k, v in headers:
                            response.headerlist.append((k, v))
                request.add_response_callback(reissue_authtkt)
                request._authtkt_reissued = True

        environ['REMOTE_USER_TOKENS'] = tokens
        environ['REMOTE_USER_DATA'] = user_data
        environ['AUTH_TYPE'] = 'cookie'

        identity = {}
        identity['timestamp'] = timestamp
        identity['userid'] = userid
        identity['tokens'] = tokens
        identity['userdata'] = user_data
        return identity

    def forget(self, request):
        """ Return a set of expires Set-Cookie headers, which will destroy
        any existing auth_tkt cookie when attached to a response"""
        request._authtkt_reissue_revoked = True
        return self._get_cookies(request, None)

    def remember(self, request, userid, max_age=None, tokens=()):
        """ Return a set of Set-Cookie headers; when set into a response,
        these headers will represent a valid authentication ticket.

        ``max_age``
          The max age of the auth_tkt cookie, in seconds.  When this value is
          set, the cookie's ``Max-Age`` and ``Expires`` settings will be set,
          allowing the auth_tkt cookie to last between browser sessions.  If
          this value is ``None``, the ``max_age`` value provided to the
          helper itself will be used as the ``max_age`` value.  Default:
          ``None``.

        ``tokens``
          A sequence of strings that will be placed into the auth_tkt tokens
          field.  Each string in the sequence must be of the Python ``str``
          type and must match the regex ``^[A-Za-z][A-Za-z0-9+_-]*$``.
          Tokens are available in the returned identity when an auth_tkt is
          found in the request and unpacked.  Default: ``()``.
        """
        max_age = self.max_age if max_age is None else int(max_age)

        environ = request.environ

        if self.include_ip:
            remote_addr = environ['REMOTE_ADDR']
        else:
            remote_addr = '0.0.0.0'

        user_data = ''

        encoding_data = self.userid_type_encoders.get(type(userid))

        if encoding_data:
            encoding, encoder = encoding_data
            userid = encoder(userid)
            user_data = 'userid_type:%s' % encoding

        new_tokens = []
        for token in tokens:
            if isinstance(token, text_type):
                try:
                    token = ascii_native_(token)
                except UnicodeEncodeError:
                    raise ValueError("Invalid token %r" % (token,))
            if not (isinstance(token, str) and VALID_TOKEN.match(token)):
                raise ValueError("Invalid token %r" % (token,))
            new_tokens.append(token)
        tokens = tuple(new_tokens)

        if hasattr(request, '_authtkt_reissued'):
            request._authtkt_reissue_revoked = True

        ticket = self.AuthTicket(
            self.secret,
            userid,
            remote_addr,
            tokens=tokens,
            user_data=user_data,
            cookie_name=self.cookie_name,
            secure=self.secure,
            hashalg=self.hashalg
            )

        cookie_value = ticket.cookie_value()
        return self._get_cookies(request, cookie_value, max_age)

@implementer(IAuthenticationPolicy)
class SessionAuthenticationPolicy(CallbackAuthenticationPolicy):
    """ A :app:`Pyramid` authentication policy which gets its data from the
    configured :term:`session`.  For this authentication policy to work, you
    will have to follow the instructions in the :ref:`sessions_chapter` to
    configure a :term:`session factory`.

    Constructor Arguments

    ``prefix``

       A prefix used when storing the authentication parameters in the
       session. Defaults to 'auth.'. Optional.

    ``callback``

       Default: ``None``.  A callback passed the userid and the
       request, expected to return ``None`` if the userid doesn't
       exist or a sequence of principal identifiers (possibly empty) if
       the user does exist.  If ``callback`` is ``None``, the userid
       will be assumed to exist with no principals.  Optional.

    ``debug``

        Default: ``False``.  If ``debug`` is ``True``, log messages to the
        Pyramid debug logger about the results of various authentication
        steps.  The output from debugging is useful for reporting to maillist
        or IRC channels when asking for support.

    """

    def __init__(self, prefix='auth.', callback=None, debug=False):
        self.callback = callback
        self.prefix = prefix or ''
        self.userid_key = prefix + 'userid'
        self.debug = debug

    def remember(self, request, userid, **kw):
        """ Store a userid in the session."""
        request.session[self.userid_key] = userid
        return []

    def forget(self, request):
        """ Remove the stored userid from the session."""
        if self.userid_key in request.session:
            del request.session[self.userid_key]
        return []

    def unauthenticated_userid(self, request):
        return request.session.get(self.userid_key)


@implementer(IAuthenticationPolicy)
class BasicAuthAuthenticationPolicy(CallbackAuthenticationPolicy):
    """ A :app:`Pyramid` authentication policy which uses HTTP standard basic
    authentication protocol to authenticate users.  To use this policy you will
    need to provide a callback which checks the supplied user credentials
    against your source of login data.

    Constructor Arguments

    ``check``

       A callback function passed a username, password and request, in that
       order as positional arguments.  Expected to return ``None`` if the
       userid doesn't exist or a sequence of principal identifiers (possibly
       empty) if the user does exist.

    ``realm``

       Default: ``"Realm"``.  The Basic Auth Realm string.  Usually displayed to
       the user by the browser in the login dialog.

    ``debug``

        Default: ``False``.  If ``debug`` is ``True``, log messages to the
        Pyramid debug logger about the results of various authentication
        steps.  The output from debugging is useful for reporting to maillist
        or IRC channels when asking for support.

    **Issuing a challenge**

    Regular browsers will not send username/password credentials unless they
    first receive a challenge from the server.  The following recipe will
    register a view that will send a Basic Auth challenge to the user whenever
    there is an attempt to call a view which results in a Forbidden response::

        from pyramid.httpexceptions import HTTPUnauthorized
        from pyramid.security import forget
        from pyramid.view import forbidden_view_config

        @forbidden_view_config()
        def basic_challenge(request):
            response = HTTPUnauthorized()
            response.headers.update(forget(request))
            return response
    """
    def __init__(self, check, realm='Realm', debug=False):
        self.check = check
        self.realm = realm
        self.debug = debug

    def unauthenticated_userid(self, request):
        """ The userid parsed from the ``Authorization`` request header."""
        credentials = self._get_credentials(request)
        if credentials:
            return credentials[0]

    def remember(self, request, userid, **kw):
        """ A no-op. Basic authentication does not provide a protocol for
        remembering the user. Credentials are sent on every request.

        """
        return []

    def forget(self, request):
        """ Returns challenge headers. This should be attached to a response
        to indicate that credentials are required."""
        return [('WWW-Authenticate', 'Basic realm="%s"' % self.realm)]

    def callback(self, username, request):
        # Username arg is ignored.  Unfortunately _get_credentials winds up
        # getting called twice when authenticated_userid is called.  Avoiding
        # that, however, winds up duplicating logic from the superclass.
        credentials = self._get_credentials(request)
        if credentials:
            username, password = credentials
            return self.check(username, password, request)

    def _get_credentials(self, request):
        authorization = request.headers.get('Authorization')
        if not authorization:
            return None
        try:
            authmeth, auth = authorization.split(' ', 1)
        except ValueError: # not enough values to unpack
            return None
        if authmeth.lower() != 'basic':
            return None

        try:
            authbytes = b64decode(auth.strip())
        except (TypeError, binascii.Error): # can't decode
            return None

        # try utf-8 first, then latin-1; see discussion in
        # https://github.com/Pylons/pyramid/issues/898
        try:
            auth = authbytes.decode('utf-8')
        except UnicodeDecodeError:
            auth = authbytes.decode('latin-1')

        try:
            username, password = auth.split(':', 1)
        except ValueError: # not enough values to unpack
            return None
        return username, password

class _SimpleSerializer(object):
    def loads(self, bstruct):
        return native_(bstruct)

    def dumps(self, appstruct):
        return bytes_(appstruct)