summary refs log tree commit diff
path: root/synapse/handlers/auth.py
blob: c8c1ed324656ecd67b57a4c90f02b78160fe1b4f (plain) (blame)
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
# -*- coding: utf-8 -*-
# Copyright 2014 - 2016 OpenMarket Ltd
# Copyright 2017 Vector Creations Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import logging
import unicodedata

import attr
import bcrypt
import pymacaroons
from canonicaljson import json

from twisted.internet import defer
from twisted.web.client import PartialDownloadError

import synapse.util.stringutils as stringutils
from synapse.api.constants import LoginType
from synapse.api.errors import (
    AuthError,
    Codes,
    InteractiveAuthIncompleteError,
    LoginError,
    StoreError,
    SynapseError,
)
from synapse.api.ratelimiting import Ratelimiter
from synapse.module_api import ModuleApi
from synapse.types import UserID
from synapse.util import logcontext
from synapse.util.caches.expiringcache import ExpiringCache

from ._base import BaseHandler

logger = logging.getLogger(__name__)


class AuthHandler(BaseHandler):
    SESSION_EXPIRE_MS = 48 * 60 * 60 * 1000

    def __init__(self, hs):
        """
        Args:
            hs (synapse.server.HomeServer):
        """
        super(AuthHandler, self).__init__(hs)
        self.checkers = {
            LoginType.RECAPTCHA: self._check_recaptcha,
            LoginType.EMAIL_IDENTITY: self._check_email_identity,
            LoginType.MSISDN: self._check_msisdn,
            LoginType.DUMMY: self._check_dummy_auth,
            LoginType.TERMS: self._check_terms_auth,
        }
        self.bcrypt_rounds = hs.config.bcrypt_rounds

        # This is not a cache per se, but a store of all current sessions that
        # expire after N hours
        self.sessions = ExpiringCache(
            cache_name="register_sessions",
            clock=hs.get_clock(),
            expiry_ms=self.SESSION_EXPIRE_MS,
            reset_expiry_on_get=True,
        )

        account_handler = ModuleApi(hs, self)
        self.password_providers = [
            module(config=config, account_handler=account_handler)
            for module, config in hs.config.password_providers
        ]

        logger.info("Extra password_providers: %r", self.password_providers)

        self.hs = hs  # FIXME better possibility to access registrationHandler later?
        self.macaroon_gen = hs.get_macaroon_generator()
        self._password_enabled = hs.config.password_enabled

        # we keep this as a list despite the O(N^2) implication so that we can
        # keep PASSWORD first and avoid confusing clients which pick the first
        # type in the list. (NB that the spec doesn't require us to do so and
        # clients which favour types that they don't understand over those that
        # they do are technically broken)
        login_types = []
        if self._password_enabled:
            login_types.append(LoginType.PASSWORD)
        for provider in self.password_providers:
            if hasattr(provider, "get_supported_login_types"):
                for t in provider.get_supported_login_types().keys():
                    if t not in login_types:
                        login_types.append(t)
        self._supported_login_types = login_types

        self._account_ratelimiter = Ratelimiter()
        self._failed_attempts_ratelimiter = Ratelimiter()

        self._clock = self.hs.get_clock()

    @defer.inlineCallbacks
    def validate_user_via_ui_auth(self, requester, request_body, clientip):
        """
        Checks that the user is who they claim to be, via a UI auth.

        This is used for things like device deletion and password reset where
        the user already has a valid access token, but we want to double-check
        that it isn't stolen by re-authenticating them.

        Args:
            requester (Requester): The user, as given by the access token

            request_body (dict): The body of the request sent by the client

            clientip (str): The IP address of the client.

        Returns:
            defer.Deferred[dict]: the parameters for this request (which may
                have been given only in a previous call).

        Raises:
            InteractiveAuthIncompleteError if the client has not yet completed
                any of the permitted login flows

            AuthError if the client has completed a login flow, and it gives
                a different user to `requester`
        """

        # build a list of supported flows
        flows = [[login_type] for login_type in self._supported_login_types]

        result, params, _ = yield self.check_auth(flows, request_body, clientip)

        # find the completed login type
        for login_type in self._supported_login_types:
            if login_type not in result:
                continue

            user_id = result[login_type]
            break
        else:
            # this can't happen
            raise Exception("check_auth returned True but no successful login type")

        # check that the UI auth matched the access token
        if user_id != requester.user.to_string():
            raise AuthError(403, "Invalid auth")

        defer.returnValue(params)

    @defer.inlineCallbacks
    def check_auth(self, flows, clientdict, clientip, password_servlet=False):
        """
        Takes a dictionary sent by the client in the login / registration
        protocol and handles the User-Interactive Auth flow.

        As a side effect, this function fills in the 'creds' key on the user's
        session with a map, which maps each auth-type (str) to the relevant
        identity authenticated by that auth-type (mostly str, but for captcha, bool).

        If no auth flows have been completed successfully, raises an
        InteractiveAuthIncompleteError. To handle this, you can use
        synapse.rest.client.v2_alpha._base.interactive_auth_handler as a
        decorator.

        Args:
            flows (list): A list of login flows. Each flow is an ordered list of
                          strings representing auth-types. At least one full
                          flow must be completed in order for auth to be successful.

            clientdict: The dictionary from the client root level, not the
                        'auth' key: this method prompts for auth if none is sent.

            clientip (str): The IP address of the client.

            password_servlet (bool): Whether the request originated from
                PasswordRestServlet.
                XXX: This is a temporary hack to distinguish between checking
                for threepid validations locally (in the case of password
                resets) and using the identity server (in the case of binding
                a 3PID during registration). Once we start using the
                homeserver for both tasks, this distinction will no longer be
                necessary.


        Returns:
            defer.Deferred[dict, dict, str]: a deferred tuple of
                (creds, params, session_id).

                'creds' contains the authenticated credentials of each stage.

                'params' contains the parameters for this request (which may
                have been given only in a previous call).

                'session_id' is the ID of this session, either passed in by the
                client or assigned by this call

        Raises:
            InteractiveAuthIncompleteError if the client has not yet completed
                all the stages in any of the permitted flows.
        """

        authdict = None
        sid = None
        if clientdict and "auth" in clientdict:
            authdict = clientdict["auth"]
            del clientdict["auth"]
            if "session" in authdict:
                sid = authdict["session"]
        session = self._get_session_info(sid)

        if len(clientdict) > 0:
            # This was designed to allow the client to omit the parameters
            # and just supply the session in subsequent calls so it split
            # auth between devices by just sharing the session, (eg. so you
            # could continue registration from your phone having clicked the
            # email auth link on there). It's probably too open to abuse
            # because it lets unauthenticated clients store arbitrary objects
            # on a home server.
            # Revisit: Assumimg the REST APIs do sensible validation, the data
            # isn't arbintrary.
            session["clientdict"] = clientdict
            self._save_session(session)
        elif "clientdict" in session:
            clientdict = session["clientdict"]

        if not authdict:
            raise InteractiveAuthIncompleteError(
                self._auth_dict_for_flows(flows, session)
            )

        if "creds" not in session:
            session["creds"] = {}
        creds = session["creds"]

        # check auth type currently being presented
        errordict = {}
        if "type" in authdict:
            login_type = authdict["type"]
            try:
                result = yield self._check_auth_dict(
                    authdict, clientip, password_servlet=password_servlet
                )
                if result:
                    creds[login_type] = result
                    self._save_session(session)
            except LoginError as e:
                if login_type == LoginType.EMAIL_IDENTITY:
                    # riot used to have a bug where it would request a new
                    # validation token (thus sending a new email) each time it
                    # got a 401 with a 'flows' field.
                    # (https://github.com/vector-im/vector-web/issues/2447).
                    #
                    # Grandfather in the old behaviour for now to avoid
                    # breaking old riot deployments.
                    raise

                # this step failed. Merge the error dict into the response
                # so that the client can have another go.
                errordict = e.error_dict()

        for f in flows:
            if len(set(f) - set(creds)) == 0:
                # it's very useful to know what args are stored, but this can
                # include the password in the case of registering, so only log
                # the keys (confusingly, clientdict may contain a password
                # param, creds is just what the user authed as for UI auth
                # and is not sensitive).
                logger.info(
                    "Auth completed with creds: %r. Client dict has keys: %r",
                    creds,
                    list(clientdict),
                )
                defer.returnValue((creds, clientdict, session["id"]))

        ret = self._auth_dict_for_flows(flows, session)
        ret["completed"] = list(creds)
        ret.update(errordict)
        raise InteractiveAuthIncompleteError(ret)

    @defer.inlineCallbacks
    def add_oob_auth(self, stagetype, authdict, clientip):
        """
        Adds the result of out-of-band authentication into an existing auth
        session. Currently used for adding the result of fallback auth.
        """
        if stagetype not in self.checkers:
            raise LoginError(400, "", Codes.MISSING_PARAM)
        if "session" not in authdict:
            raise LoginError(400, "", Codes.MISSING_PARAM)

        sess = self._get_session_info(authdict["session"])
        if "creds" not in sess:
            sess["creds"] = {}
        creds = sess["creds"]

        result = yield self.checkers[stagetype](authdict, clientip)
        if result:
            creds[stagetype] = result
            self._save_session(sess)
            defer.returnValue(True)
        defer.returnValue(False)

    def get_session_id(self, clientdict):
        """
        Gets the session ID for a client given the client dictionary

        Args:
            clientdict: The dictionary sent by the client in the request

        Returns:
            str|None: The string session ID the client sent. If the client did
                not send a session ID, returns None.
        """
        sid = None
        if clientdict and "auth" in clientdict:
            authdict = clientdict["auth"]
            if "session" in authdict:
                sid = authdict["session"]
        return sid

    def set_session_data(self, session_id, key, value):
        """
        Store a key-value pair into the sessions data associated with this
        request. This data is stored server-side and cannot be modified by
        the client.

        Args:
            session_id (string): The ID of this session as returned from check_auth
            key (string): The key to store the data under
            value (any): The data to store
        """
        sess = self._get_session_info(session_id)
        sess.setdefault("serverdict", {})[key] = value
        self._save_session(sess)

    def get_session_data(self, session_id, key, default=None):
        """
        Retrieve data stored with set_session_data

        Args:
            session_id (string): The ID of this session as returned from check_auth
            key (string): The key to store the data under
            default (any): Value to return if the key has not been set
        """
        sess = self._get_session_info(session_id)
        return sess.setdefault("serverdict", {}).get(key, default)

    @defer.inlineCallbacks
    def _check_auth_dict(self, authdict, clientip, password_servlet=False):
        """Attempt to validate the auth dict provided by a client

        Args:
            authdict (object): auth dict provided by the client
            clientip (str): IP address of the client

        Returns:
            Deferred: result of the stage verification.

        Raises:
            StoreError if there was a problem accessing the database
            SynapseError if there was a problem with the request
            LoginError if there was an authentication problem.
        """
        login_type = authdict["type"]
        checker = self.checkers.get(login_type)
        if checker is not None:
            # XXX: Temporary workaround for having Synapse handle password resets
            # See AuthHandler.check_auth for further details
            res = yield checker(
                authdict, clientip=clientip, password_servlet=password_servlet
            )
            defer.returnValue(res)

        # build a v1-login-style dict out of the authdict and fall back to the
        # v1 code
        user_id = authdict.get("user")

        if user_id is None:
            raise SynapseError(400, "", Codes.MISSING_PARAM)

        (canonical_id, callback) = yield self.validate_login(user_id, authdict)
        defer.returnValue(canonical_id)

    @defer.inlineCallbacks
    def _check_recaptcha(self, authdict, clientip, **kwargs):
        try:
            user_response = authdict["response"]
        except KeyError:
            # Client tried to provide captcha but didn't give the parameter:
            # bad request.
            raise LoginError(
                400, "Captcha response is required", errcode=Codes.CAPTCHA_NEEDED
            )

        logger.info(
            "Submitting recaptcha response %s with remoteip %s", user_response, clientip
        )

        # TODO: get this from the homeserver rather than creating a new one for
        # each request
        try:
            client = self.hs.get_simple_http_client()
            resp_body = yield client.post_urlencoded_get_json(
                self.hs.config.recaptcha_siteverify_api,
                args={
                    "secret": self.hs.config.recaptcha_private_key,
                    "response": user_response,
                    "remoteip": clientip,
                },
            )
        except PartialDownloadError as pde:
            # Twisted is silly
            data = pde.response
            resp_body = json.loads(data)

        if "success" in resp_body:
            # Note that we do NOT check the hostname here: we explicitly
            # intend the CAPTCHA to be presented by whatever client the
            # user is using, we just care that they have completed a CAPTCHA.
            logger.info(
                "%s reCAPTCHA from hostname %s",
                "Successful" if resp_body["success"] else "Failed",
                resp_body.get("hostname"),
            )
            if resp_body["success"]:
                defer.returnValue(True)
        raise LoginError(401, "", errcode=Codes.UNAUTHORIZED)

    def _check_email_identity(self, authdict, **kwargs):
        return self._check_threepid("email", authdict, **kwargs)

    def _check_msisdn(self, authdict, **kwargs):
        return self._check_threepid("msisdn", authdict)

    def _check_dummy_auth(self, authdict, **kwargs):
        return defer.succeed(True)

    def _check_terms_auth(self, authdict, **kwargs):
        return defer.succeed(True)

    @defer.inlineCallbacks
    def _check_threepid(self, medium, authdict, password_servlet=False, **kwargs):
        if "threepid_creds" not in authdict:
            raise LoginError(400, "Missing threepid_creds", Codes.MISSING_PARAM)

        threepid_creds = authdict["threepid_creds"]

        identity_handler = self.hs.get_handlers().identity_handler

        logger.info("Getting validated threepid. threepidcreds: %r", (threepid_creds,))
        if (
            not password_servlet
            or self.hs.config.email_password_reset_behaviour == "remote"
        ):
            threepid = yield identity_handler.threepid_from_creds(threepid_creds)
        elif self.hs.config.email_password_reset_behaviour == "local":
            row = yield self.store.get_threepid_validation_session(
                medium,
                threepid_creds["client_secret"],
                sid=threepid_creds["sid"],
                validated=True,
            )

            threepid = (
                {
                    "medium": row["medium"],
                    "address": row["address"],
                    "validated_at": row["validated_at"],
                }
                if row
                else None
            )

            if row:
                # Valid threepid returned, delete from the db
                yield self.store.delete_threepid_session(threepid_creds["sid"])
        else:
            raise SynapseError(
                400, "Password resets are not enabled on this homeserver"
            )

        if not threepid:
            raise LoginError(401, "", errcode=Codes.UNAUTHORIZED)

        if threepid["medium"] != medium:
            raise LoginError(
                401,
                "Expecting threepid of type '%s', got '%s'"
                % (medium, threepid["medium"]),
                errcode=Codes.UNAUTHORIZED,
            )

        threepid["threepid_creds"] = authdict["threepid_creds"]

        defer.returnValue(threepid)

    def _get_params_recaptcha(self):
        return {"public_key": self.hs.config.recaptcha_public_key}

    def _get_params_terms(self):
        return {
            "policies": {
                "privacy_policy": {
                    "version": self.hs.config.user_consent_version,
                    "en": {
                        "name": self.hs.config.user_consent_policy_name,
                        "url": "%s_matrix/consent?v=%s"
                        % (
                            self.hs.config.public_baseurl,
                            self.hs.config.user_consent_version,
                        ),
                    },
                }
            }
        }

    def _auth_dict_for_flows(self, flows, session):
        public_flows = []
        for f in flows:
            public_flows.append(f)

        get_params = {
            LoginType.RECAPTCHA: self._get_params_recaptcha,
            LoginType.TERMS: self._get_params_terms,
        }

        params = {}

        for f in public_flows:
            for stage in f:
                if stage in get_params and stage not in params:
                    params[stage] = get_params[stage]()

        return {
            "session": session["id"],
            "flows": [{"stages": f} for f in public_flows],
            "params": params,
        }

    def _get_session_info(self, session_id):
        if session_id not in self.sessions:
            session_id = None

        if not session_id:
            # create a new session
            while session_id is None or session_id in self.sessions:
                session_id = stringutils.random_string(24)
            self.sessions[session_id] = {"id": session_id}

        return self.sessions[session_id]

    @defer.inlineCallbacks
    def get_access_token_for_user_id(self, user_id, device_id=None):
        """
        Creates a new access token for the user with the given user ID.

        The user is assumed to have been authenticated by some other
        machanism (e.g. CAS), and the user_id converted to the canonical case.

        The device will be recorded in the table if it is not there already.

        Args:
            user_id (str): canonical User ID
            device_id (str|None): the device ID to associate with the tokens.
               None to leave the tokens unassociated with a device (deprecated:
               we should always have a device ID)
        Returns:
              The access token for the user's session.
        Raises:
            StoreError if there was a problem storing the token.
        """
        logger.info("Logging in user %s on device %s", user_id, device_id)
        access_token = yield self.issue_access_token(user_id, device_id)
        yield self.auth.check_auth_blocking(user_id)

        # the device *should* have been registered before we got here; however,
        # it's possible we raced against a DELETE operation. The thing we
        # really don't want is active access_tokens without a record of the
        # device, so we double-check it here.
        if device_id is not None:
            try:
                yield self.store.get_device(user_id, device_id)
            except StoreError:
                yield self.store.delete_access_token(access_token)
                raise StoreError(400, "Login raced against device deletion")

        defer.returnValue(access_token)

    @defer.inlineCallbacks
    def check_user_exists(self, user_id):
        """
        Checks to see if a user with the given id exists. Will check case
        insensitively, but return None if there are multiple inexact matches.

        Args:
            (unicode|bytes) user_id: complete @user:id

        Returns:
            defer.Deferred: (unicode) canonical_user_id, or None if zero or
            multiple matches

        Raises:
            LimitExceededError if the ratelimiter's login requests count for this
                user is too high too proceed.
        """
        self.ratelimit_login_per_account(user_id)
        res = yield self._find_user_id_and_pwd_hash(user_id)
        if res is not None:
            defer.returnValue(res[0])
        defer.returnValue(None)

    @defer.inlineCallbacks
    def _find_user_id_and_pwd_hash(self, user_id):
        """Checks to see if a user with the given id exists. Will check case
        insensitively, but will return None if there are multiple inexact
        matches.

        Returns:
            tuple: A 2-tuple of `(canonical_user_id, password_hash)`
            None: if there is not exactly one match
        """
        user_infos = yield self.store.get_users_by_id_case_insensitive(user_id)

        result = None
        if not user_infos:
            logger.warn("Attempted to login as %s but they do not exist", user_id)
        elif len(user_infos) == 1:
            # a single match (possibly not exact)
            result = user_infos.popitem()
        elif user_id in user_infos:
            # multiple matches, but one is exact
            result = (user_id, user_infos[user_id])
        else:
            # multiple matches, none of them exact
            logger.warn(
                "Attempted to login as %s but it matches more than one user "
                "inexactly: %r",
                user_id,
                user_infos.keys(),
            )
        defer.returnValue(result)

    def get_supported_login_types(self):
        """Get a the login types supported for the /login API

        By default this is just 'm.login.password' (unless password_enabled is
        False in the config file), but password auth providers can provide
        other login types.

        Returns:
            Iterable[str]: login types
        """
        return self._supported_login_types

    @defer.inlineCallbacks
    def validate_login(self, username, login_submission):
        """Authenticates the user for the /login API

        Also used by the user-interactive auth flow to validate
        m.login.password auth types.

        Args:
            username (str): username supplied by the user
            login_submission (dict): the whole of the login submission
                (including 'type' and other relevant fields)
        Returns:
            Deferred[str, func]: canonical user id, and optional callback
                to be called once the access token and device id are issued
        Raises:
            StoreError if there was a problem accessing the database
            SynapseError if there was a problem with the request
            LoginError if there was an authentication problem.
            LimitExceededError if the ratelimiter's login requests count for this
                user is too high too proceed.
        """

        if username.startswith("@"):
            qualified_user_id = username
        else:
            qualified_user_id = UserID(username, self.hs.hostname).to_string()

        self.ratelimit_login_per_account(qualified_user_id)

        login_type = login_submission.get("type")
        known_login_type = False

        # special case to check for "password" for the check_password interface
        # for the auth providers
        password = login_submission.get("password")

        if login_type == LoginType.PASSWORD:
            if not self._password_enabled:
                raise SynapseError(400, "Password login has been disabled.")
            if not password:
                raise SynapseError(400, "Missing parameter: password")

        for provider in self.password_providers:
            if hasattr(provider, "check_password") and login_type == LoginType.PASSWORD:
                known_login_type = True
                is_valid = yield provider.check_password(qualified_user_id, password)
                if is_valid:
                    defer.returnValue((qualified_user_id, None))

            if not hasattr(provider, "get_supported_login_types") or not hasattr(
                provider, "check_auth"
            ):
                # this password provider doesn't understand custom login types
                continue

            supported_login_types = provider.get_supported_login_types()
            if login_type not in supported_login_types:
                # this password provider doesn't understand this login type
                continue

            known_login_type = True
            login_fields = supported_login_types[login_type]

            missing_fields = []
            login_dict = {}
            for f in login_fields:
                if f not in login_submission:
                    missing_fields.append(f)
                else:
                    login_dict[f] = login_submission[f]
            if missing_fields:
                raise SynapseError(
                    400,
                    "Missing parameters for login type %s: %s"
                    % (login_type, missing_fields),
                )

            result = yield provider.check_auth(username, login_type, login_dict)
            if result:
                if isinstance(result, str):
                    result = (result, None)
                defer.returnValue(result)

        if login_type == LoginType.PASSWORD and self.hs.config.password_localdb_enabled:
            known_login_type = True

            canonical_user_id = yield self._check_local_password(
                qualified_user_id, password
            )

            if canonical_user_id:
                defer.returnValue((canonical_user_id, None))

        if not known_login_type:
            raise SynapseError(400, "Unknown login type %s" % login_type)

        # unknown username or invalid password.
        self._failed_attempts_ratelimiter.ratelimit(
            qualified_user_id.lower(),
            time_now_s=self._clock.time(),
            rate_hz=self.hs.config.rc_login_failed_attempts.per_second,
            burst_count=self.hs.config.rc_login_failed_attempts.burst_count,
            update=True,
        )

        # We raise a 403 here, but note that if we're doing user-interactive
        # login, it turns all LoginErrors into a 401 anyway.
        raise LoginError(403, "Invalid password", errcode=Codes.FORBIDDEN)

    @defer.inlineCallbacks
    def check_password_provider_3pid(self, medium, address, password):
        """Check if a password provider is able to validate a thirdparty login

        Args:
            medium (str): The medium of the 3pid (ex. email).
            address (str): The address of the 3pid (ex. jdoe@example.com).
            password (str): The password of the user.

        Returns:
            Deferred[(str|None, func|None)]: A tuple of `(user_id,
            callback)`. If authentication is successful, `user_id` is a `str`
            containing the authenticated, canonical user ID. `callback` is
            then either a function to be later run after the server has
            completed login/registration, or `None`. If authentication was
            unsuccessful, `user_id` and `callback` are both `None`.
        """
        for provider in self.password_providers:
            if hasattr(provider, "check_3pid_auth"):
                # This function is able to return a deferred that either
                # resolves None, meaning authentication failure, or upon
                # success, to a str (which is the user_id) or a tuple of
                # (user_id, callback_func), where callback_func should be run
                # after we've finished everything else
                result = yield provider.check_3pid_auth(medium, address, password)
                if result:
                    # Check if the return value is a str or a tuple
                    if isinstance(result, str):
                        # If it's a str, set callback function to None
                        result = (result, None)
                    defer.returnValue(result)

        defer.returnValue((None, None))

    @defer.inlineCallbacks
    def _check_local_password(self, user_id, password):
        """Authenticate a user against the local password database.

        user_id is checked case insensitively, but will return None if there are
        multiple inexact matches.

        Args:
            user_id (unicode): complete @user:id
            password (unicode): the provided password
        Returns:
            Deferred[unicode] the canonical_user_id, or Deferred[None] if
                unknown user/bad password

        Raises:
            LimitExceededError if the ratelimiter's login requests count for this
                user is too high too proceed.
        """
        lookupres = yield self._find_user_id_and_pwd_hash(user_id)
        if not lookupres:
            defer.returnValue(None)
        (user_id, password_hash) = lookupres
        result = yield self.validate_hash(password, password_hash)
        if not result:
            logger.warn("Failed password login for user %s", user_id)
            defer.returnValue(None)
        defer.returnValue(user_id)

    @defer.inlineCallbacks
    def issue_access_token(self, user_id, device_id=None):
        access_token = self.macaroon_gen.generate_access_token(user_id)
        yield self.store.add_access_token_to_user(user_id, access_token, device_id)
        defer.returnValue(access_token)

    @defer.inlineCallbacks
    def validate_short_term_login_token_and_get_user_id(self, login_token):
        auth_api = self.hs.get_auth()
        user_id = None
        try:
            macaroon = pymacaroons.Macaroon.deserialize(login_token)
            user_id = auth_api.get_user_id_from_macaroon(macaroon)
            auth_api.validate_macaroon(macaroon, "login", True, user_id)
        except Exception:
            raise AuthError(403, "Invalid token", errcode=Codes.FORBIDDEN)
        self.ratelimit_login_per_account(user_id)
        yield self.auth.check_auth_blocking(user_id)
        defer.returnValue(user_id)

    @defer.inlineCallbacks
    def delete_access_token(self, access_token):
        """Invalidate a single access token

        Args:
            access_token (str): access token to be deleted

        Returns:
            Deferred
        """
        user_info = yield self.auth.get_user_by_access_token(access_token)
        yield self.store.delete_access_token(access_token)

        # see if any of our auth providers want to know about this
        for provider in self.password_providers:
            if hasattr(provider, "on_logged_out"):
                yield provider.on_logged_out(
                    user_id=str(user_info["user"]),
                    device_id=user_info["device_id"],
                    access_token=access_token,
                )

        # delete pushers associated with this access token
        if user_info["token_id"] is not None:
            yield self.hs.get_pusherpool().remove_pushers_by_access_token(
                str(user_info["user"]), (user_info["token_id"],)
            )

    @defer.inlineCallbacks
    def delete_access_tokens_for_user(
        self, user_id, except_token_id=None, device_id=None
    ):
        """Invalidate access tokens belonging to a user

        Args:
            user_id (str):  ID of user the tokens belong to
            except_token_id (str|None): access_token ID which should *not* be
                deleted
            device_id (str|None):  ID of device the tokens are associated with.
                If None, tokens associated with any device (or no device) will
                be deleted
        Returns:
            Deferred
        """
        tokens_and_devices = yield self.store.user_delete_access_tokens(
            user_id, except_token_id=except_token_id, device_id=device_id
        )

        # see if any of our auth providers want to know about this
        for provider in self.password_providers:
            if hasattr(provider, "on_logged_out"):
                for token, token_id, device_id in tokens_and_devices:
                    yield provider.on_logged_out(
                        user_id=user_id, device_id=device_id, access_token=token
                    )

        # delete pushers associated with the access tokens
        yield self.hs.get_pusherpool().remove_pushers_by_access_token(
            user_id, (token_id for _, token_id, _ in tokens_and_devices)
        )

    @defer.inlineCallbacks
    def add_threepid(self, user_id, medium, address, validated_at):
        # 'Canonicalise' email addresses down to lower case.
        # We've now moving towards the Home Server being the entity that
        # is responsible for validating threepids used for resetting passwords
        # on accounts, so in future Synapse will gain knowledge of specific
        # types (mediums) of threepid. For now, we still use the existing
        # infrastructure, but this is the start of synapse gaining knowledge
        # of specific types of threepid (and fixes the fact that checking
        # for the presence of an email address during password reset was
        # case sensitive).
        if medium == "email":
            address = address.lower()

        yield self.store.user_add_threepid(
            user_id, medium, address, validated_at, self.hs.get_clock().time_msec()
        )

    @defer.inlineCallbacks
    def delete_threepid(self, user_id, medium, address, id_server=None):
        """Attempts to unbind the 3pid on the identity servers and deletes it
        from the local database.

        Args:
            user_id (str)
            medium (str)
            address (str)
            id_server (str|None): Use the given identity server when unbinding
                any threepids. If None then will attempt to unbind using the
                identity server specified when binding (if known).


        Returns:
            Deferred[bool]: Returns True if successfully unbound the 3pid on
            the identity server, False if identity server doesn't support the
            unbind API.
        """

        # 'Canonicalise' email addresses as per above
        if medium == "email":
            address = address.lower()

        identity_handler = self.hs.get_handlers().identity_handler
        result = yield identity_handler.try_unbind_threepid(
            user_id, {"medium": medium, "address": address, "id_server": id_server}
        )

        yield self.store.user_delete_threepid(user_id, medium, address)
        defer.returnValue(result)

    def _save_session(self, session):
        # TODO: Persistent storage
        logger.debug("Saving session %s", session)
        session["last_used"] = self.hs.get_clock().time_msec()
        self.sessions[session["id"]] = session

    def hash(self, password):
        """Computes a secure hash of password.

        Args:
            password (unicode): Password to hash.

        Returns:
            Deferred(unicode): Hashed password.
        """

        def _do_hash():
            # Normalise the Unicode in the password
            pw = unicodedata.normalize("NFKC", password)

            return bcrypt.hashpw(
                pw.encode("utf8") + self.hs.config.password_pepper.encode("utf8"),
                bcrypt.gensalt(self.bcrypt_rounds),
            ).decode("ascii")

        return logcontext.defer_to_thread(self.hs.get_reactor(), _do_hash)

    def validate_hash(self, password, stored_hash):
        """Validates that self.hash(password) == stored_hash.

        Args:
            password (unicode): Password to hash.
            stored_hash (bytes): Expected hash value.

        Returns:
            Deferred(bool): Whether self.hash(password) == stored_hash.
        """

        def _do_validate_hash():
            # Normalise the Unicode in the password
            pw = unicodedata.normalize("NFKC", password)

            return bcrypt.checkpw(
                pw.encode("utf8") + self.hs.config.password_pepper.encode("utf8"),
                stored_hash,
            )

        if stored_hash:
            if not isinstance(stored_hash, bytes):
                stored_hash = stored_hash.encode("ascii")

            return logcontext.defer_to_thread(self.hs.get_reactor(), _do_validate_hash)
        else:
            return defer.succeed(False)

    def ratelimit_login_per_account(self, user_id):
        """Checks whether the process must be stopped because of ratelimiting.

        Checks against two ratelimiters: the generic one for login attempts per
        account and the one specific to failed attempts.

        Args:
            user_id (unicode): complete @user:id

        Raises:
            LimitExceededError if one of the ratelimiters' login requests count
                for this user is too high too proceed.
        """
        self._failed_attempts_ratelimiter.ratelimit(
            user_id.lower(),
            time_now_s=self._clock.time(),
            rate_hz=self.hs.config.rc_login_failed_attempts.per_second,
            burst_count=self.hs.config.rc_login_failed_attempts.burst_count,
            update=False,
        )

        self._account_ratelimiter.ratelimit(
            user_id.lower(),
            time_now_s=self._clock.time(),
            rate_hz=self.hs.config.rc_login_account.per_second,
            burst_count=self.hs.config.rc_login_account.burst_count,
            update=True,
        )


@attr.s
class MacaroonGenerator(object):

    hs = attr.ib()

    def generate_access_token(self, user_id, extra_caveats=None):
        extra_caveats = extra_caveats or []
        macaroon = self._generate_base_macaroon(user_id)
        macaroon.add_first_party_caveat("type = access")
        # Include a nonce, to make sure that each login gets a different
        # access token.
        macaroon.add_first_party_caveat(
            "nonce = %s" % (stringutils.random_string_with_symbols(16),)
        )
        for caveat in extra_caveats:
            macaroon.add_first_party_caveat(caveat)
        return macaroon.serialize()

    def generate_short_term_login_token(self, user_id, duration_in_ms=(2 * 60 * 1000)):
        """

        Args:
            user_id (unicode):
            duration_in_ms (int):

        Returns:
            unicode
        """
        macaroon = self._generate_base_macaroon(user_id)
        macaroon.add_first_party_caveat("type = login")
        now = self.hs.get_clock().time_msec()
        expiry = now + duration_in_ms
        macaroon.add_first_party_caveat("time < %d" % (expiry,))
        return macaroon.serialize()

    def generate_delete_pusher_token(self, user_id):
        macaroon = self._generate_base_macaroon(user_id)
        macaroon.add_first_party_caveat("type = delete_pusher")
        return macaroon.serialize()

    def _generate_base_macaroon(self, user_id):
        macaroon = pymacaroons.Macaroon(
            location=self.hs.config.server_name,
            identifier="key",
            key=self.hs.config.macaroon_secret_key,
        )
        macaroon.add_first_party_caveat("gen = 1")
        macaroon.add_first_party_caveat("user_id = %s" % (user_id,))
        return macaroon