summary refs log tree commit diff
path: root/synapse/federation/transport/client.py
blob: de408f7f8d3edab2ff99945388de4a7bc860e616 (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
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
#
# This file is licensed under the Affero General Public License (AGPL) version 3.
#
# Copyright 2020 Sorunome
# Copyright 2014-2022 The Matrix.org Foundation C.I.C.
# Copyright (C) 2023 New Vector, Ltd
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# See the GNU Affero General Public License for more details:
# <https://www.gnu.org/licenses/agpl-3.0.html>.
#
# Originally licensed under the Apache License, Version 2.0:
# <http://www.apache.org/licenses/LICENSE-2.0>.
#
# [This file includes modifications made by New Vector Limited]
#
#

import logging
import urllib
from typing import (
    TYPE_CHECKING,
    Any,
    BinaryIO,
    Callable,
    Collection,
    Dict,
    Generator,
    Iterable,
    List,
    Mapping,
    Optional,
    Tuple,
    Union,
)

import attr
import ijson

from synapse.api.constants import Direction, Membership
from synapse.api.errors import Codes, HttpResponseException, SynapseError
from synapse.api.room_versions import RoomVersion
from synapse.api.urls import (
    FEDERATION_UNSTABLE_PREFIX,
    FEDERATION_V1_PREFIX,
    FEDERATION_V2_PREFIX,
)
from synapse.events import EventBase, make_event_from_dict
from synapse.federation.units import Transaction
from synapse.http.matrixfederationclient import ByteParser, LegacyJsonSendParser
from synapse.http.types import QueryParams
from synapse.types import JsonDict, UserID
from synapse.util import ExceptionBundle

if TYPE_CHECKING:
    from synapse.app.homeserver import HomeServer

logger = logging.getLogger(__name__)


class TransportLayerClient:
    """Sends federation HTTP requests to other servers"""

    def __init__(self, hs: "HomeServer"):
        self.client = hs.get_federation_http_client()
        self._is_mine_server_name = hs.is_mine_server_name

    async def get_room_state_ids(
        self, destination: str, room_id: str, event_id: str
    ) -> JsonDict:
        """Requests the IDs of all state for a given room at the given event.

        Args:
            destination: The host name of the remote homeserver we want
                to get the state from.
            room_id: the room we want the state of
            event_id: The event we want the context at.

        Returns:
            Results in a dict received from the remote homeserver.
        """
        logger.debug("get_room_state_ids dest=%s, room=%s", destination, room_id)

        path = _create_v1_path("/state_ids/%s", room_id)
        return await self.client.get_json(
            destination,
            path=path,
            args={"event_id": event_id},
            try_trailing_slash_on_400=True,
        )

    async def get_room_state(
        self, room_version: RoomVersion, destination: str, room_id: str, event_id: str
    ) -> "StateRequestResponse":
        """Requests the full state for a given room at the given event.

        Args:
            room_version: the version of the room (required to build the event objects)
            destination: The host name of the remote homeserver we want
                to get the state from.
            room_id: the room we want the state of
            event_id: The event we want the context at.

        Returns:
            Results in a dict received from the remote homeserver.
        """
        path = _create_v1_path("/state/%s", room_id)
        return await self.client.get_json(
            destination,
            path=path,
            args={"event_id": event_id},
            # This can take a looooooong time for large rooms. Give this a generous
            # timeout of 10 minutes to avoid the partial state resync timing out early
            # and trying a bunch of servers who haven't seen our join yet.
            timeout=600_000,
            parser=_StateParser(room_version),
        )

    async def get_event(
        self, destination: str, event_id: str, timeout: Optional[int] = None
    ) -> JsonDict:
        """Requests the pdu with give id and origin from the given server.

        Args:
            destination: The host name of the remote homeserver we want
                to get the state from.
            event_id: The id of the event being requested.
            timeout: How long to try (in ms) the destination for before
                giving up. None indicates no timeout.

        Returns:
            Results in a dict received from the remote homeserver.
        """
        logger.debug("get_pdu dest=%s, event_id=%s", destination, event_id)

        path = _create_v1_path("/event/%s", event_id)
        return await self.client.get_json(
            destination, path=path, timeout=timeout, try_trailing_slash_on_400=True
        )

    async def backfill(
        self, destination: str, room_id: str, event_tuples: Collection[str], limit: int
    ) -> Optional[Union[JsonDict, list]]:
        """Requests `limit` previous PDUs in a given context before list of
        PDUs.

        Args:
            destination
            room_id
            event_tuples:
                Must be a Collection that is falsy when empty.
                (Iterable is not enough here!)
            limit

        Returns:
            Results in a dict received from the remote homeserver.
        """
        logger.debug(
            "backfill dest=%s, room_id=%s, event_tuples=%r, limit=%s",
            destination,
            room_id,
            event_tuples,
            str(limit),
        )

        if not event_tuples:
            # TODO: raise?
            return None

        path = _create_v1_path("/backfill/%s", room_id)

        args = {"v": event_tuples, "limit": [str(limit)]}

        return await self.client.get_json(
            destination, path=path, args=args, try_trailing_slash_on_400=True
        )

    async def timestamp_to_event(
        self, destination: str, room_id: str, timestamp: int, direction: Direction
    ) -> Union[JsonDict, List]:
        """
        Calls a remote federating server at `destination` asking for their
        closest event to the given timestamp in the given direction.

        Args:
            destination: Domain name of the remote homeserver
            room_id: Room to fetch the event from
            timestamp: The point in time (inclusive) we should navigate from in
                the given direction to find the closest event.
            direction: indicates whether we should navigate forward
                or backward from the given timestamp to find the closest event.

        Returns:
            Response dict received from the remote homeserver.

        Raises:
            Various exceptions when the request fails
        """
        path = _create_v1_path(
            "/timestamp_to_event/%s",
            room_id,
        )

        args = {"ts": [str(timestamp)], "dir": [direction.value]}

        remote_response = await self.client.get_json(
            destination, path=path, args=args, try_trailing_slash_on_400=True
        )

        return remote_response

    async def send_transaction(
        self,
        transaction: Transaction,
        json_data_callback: Optional[Callable[[], JsonDict]] = None,
    ) -> JsonDict:
        """Sends the given Transaction to its destination

        Args:
            transaction

        Returns:
            Succeeds when we get a 2xx HTTP response. The result
            will be the decoded JSON body.

            Fails with ``HTTPRequestException`` if we get an HTTP response
            code >= 300.

            Fails with ``NotRetryingDestination`` if we are not yet ready
            to retry this server.

            Fails with ``FederationDeniedError`` if this destination
            is not on our federation whitelist
        """
        logger.debug(
            "send_data dest=%s, txid=%s",
            transaction.destination,
            transaction.transaction_id,
        )

        if self._is_mine_server_name(transaction.destination):
            raise RuntimeError("Transport layer cannot send to itself!")

        # FIXME: This is only used by the tests. The actual json sent is
        # generated by the json_data_callback.
        json_data = transaction.get_dict()

        path = _create_v1_path("/send/%s", transaction.transaction_id)

        return await self.client.put_json(
            transaction.destination,
            path=path,
            data=json_data,
            json_data_callback=json_data_callback,
            long_retries=True,
            try_trailing_slash_on_400=True,
            # Sending a transaction should always succeed, if it doesn't
            # then something is wrong and we should backoff.
            backoff_on_all_error_codes=True,
        )

    async def make_query(
        self,
        destination: str,
        query_type: str,
        args: QueryParams,
        retry_on_dns_fail: bool,
        ignore_backoff: bool = False,
        prefix: str = FEDERATION_V1_PREFIX,
    ) -> JsonDict:
        path = _create_path(prefix, "/query/%s", query_type)

        return await self.client.get_json(
            destination=destination,
            path=path,
            args=args,
            retry_on_dns_fail=retry_on_dns_fail,
            timeout=10000,
            ignore_backoff=ignore_backoff,
        )

    async def make_membership_event(
        self,
        destination: str,
        room_id: str,
        user_id: str,
        membership: str,
        params: Optional[Mapping[str, Union[str, Iterable[str]]]],
    ) -> JsonDict:
        """Asks a remote server to build and sign us a membership event

        Note that this does not append any events to any graphs.

        Args:
            destination: address of remote homeserver
            room_id: room to join/leave
            user_id: user to be joined/left
            membership: one of join/leave
            params: Query parameters to include in the request.

        Returns:
            Succeeds when we get a 2xx HTTP response. The result
            will be the decoded JSON body (ie, the new event).

            Fails with ``HTTPRequestException`` if we get an HTTP response
            code >= 300.

            Fails with ``NotRetryingDestination`` if we are not yet ready
            to retry this server.

            Fails with ``FederationDeniedError`` if the remote destination
            is not in our federation whitelist
        """
        valid_memberships = {Membership.JOIN, Membership.LEAVE, Membership.KNOCK}

        if membership not in valid_memberships:
            raise RuntimeError(
                "make_membership_event called with membership='%s', must be one of %s"
                % (membership, ",".join(valid_memberships))
            )
        path = _create_v1_path("/make_%s/%s/%s", membership, room_id, user_id)

        ignore_backoff = False
        retry_on_dns_fail = False

        if membership == Membership.LEAVE:
            # we particularly want to do our best to send leave events. The
            # problem is that if it fails, we won't retry it later, so if the
            # remote server was just having a momentary blip, the room will be
            # out of sync.
            ignore_backoff = True
            retry_on_dns_fail = True

        return await self.client.get_json(
            destination=destination,
            path=path,
            args=params,
            retry_on_dns_fail=retry_on_dns_fail,
            timeout=20000,
            ignore_backoff=ignore_backoff,
        )

    async def send_join_v1(
        self,
        room_version: RoomVersion,
        destination: str,
        room_id: str,
        event_id: str,
        content: JsonDict,
    ) -> "SendJoinResponse":
        path = _create_v1_path("/send_join/%s/%s", room_id, event_id)

        return await self.client.put_json(
            destination=destination,
            path=path,
            data=content,
            parser=SendJoinParser(room_version, v1_api=True),
        )

    async def send_join_v2(
        self,
        room_version: RoomVersion,
        destination: str,
        room_id: str,
        event_id: str,
        content: JsonDict,
        omit_members: bool,
    ) -> "SendJoinResponse":
        path = _create_v2_path("/send_join/%s/%s", room_id, event_id)
        query_params: Dict[str, str] = {}
        # lazy-load state on join
        query_params["omit_members"] = "true" if omit_members else "false"

        return await self.client.put_json(
            destination=destination,
            path=path,
            args=query_params,
            data=content,
            parser=SendJoinParser(room_version, v1_api=False),
        )

    async def send_leave_v1(
        self, destination: str, room_id: str, event_id: str, content: JsonDict
    ) -> Tuple[int, JsonDict]:
        path = _create_v1_path("/send_leave/%s/%s", room_id, event_id)

        return await self.client.put_json(
            destination=destination,
            path=path,
            data=content,
            # we want to do our best to send this through. The problem is
            # that if it fails, we won't retry it later, so if the remote
            # server was just having a momentary blip, the room will be out of
            # sync.
            ignore_backoff=True,
            parser=LegacyJsonSendParser(),
        )

    async def send_leave_v2(
        self, destination: str, room_id: str, event_id: str, content: JsonDict
    ) -> JsonDict:
        path = _create_v2_path("/send_leave/%s/%s", room_id, event_id)

        return await self.client.put_json(
            destination=destination,
            path=path,
            data=content,
            # we want to do our best to send this through. The problem is
            # that if it fails, we won't retry it later, so if the remote
            # server was just having a momentary blip, the room will be out of
            # sync.
            ignore_backoff=True,
        )

    async def send_knock_v1(
        self,
        destination: str,
        room_id: str,
        event_id: str,
        content: JsonDict,
    ) -> JsonDict:
        """
        Sends a signed knock membership event to a remote server. This is the second
        step for knocking after make_knock.

        Args:
            destination: The remote homeserver.
            room_id: The ID of the room to knock on.
            event_id: The ID of the knock membership event that we're sending.
            content: The knock membership event that we're sending. Note that this is not the
                `content` field of the membership event, but the entire signed membership event
                itself represented as a JSON dict.

        Returns:
            The remote homeserver can optionally return some state from the room. The response
            dictionary is in the form:

            {"knock_room_state": [<state event dict>, ...]}

            The list of state events may be empty.
        """
        path = _create_v1_path("/send_knock/%s/%s", room_id, event_id)

        return await self.client.put_json(
            destination=destination, path=path, data=content
        )

    async def send_invite_v1(
        self, destination: str, room_id: str, event_id: str, content: JsonDict
    ) -> Tuple[int, JsonDict]:
        path = _create_v1_path("/invite/%s/%s", room_id, event_id)

        return await self.client.put_json(
            destination=destination,
            path=path,
            data=content,
            ignore_backoff=True,
            parser=LegacyJsonSendParser(),
        )

    async def send_invite_v2(
        self, destination: str, room_id: str, event_id: str, content: JsonDict
    ) -> JsonDict:
        path = _create_v2_path("/invite/%s/%s", room_id, event_id)

        return await self.client.put_json(
            destination=destination, path=path, data=content, ignore_backoff=True
        )

    async def get_public_rooms(
        self,
        remote_server: str,
        limit: Optional[int] = None,
        since_token: Optional[str] = None,
        search_filter: Optional[Dict] = None,
        include_all_networks: bool = False,
        third_party_instance_id: Optional[str] = None,
    ) -> JsonDict:
        """Get the list of public rooms from a remote homeserver

        See synapse.federation.federation_client.FederationClient.get_public_rooms for
        more information.
        """
        path = _create_v1_path("/publicRooms")

        if search_filter:
            # this uses MSC2197 (Search Filtering over Federation)
            data: Dict[str, Any] = {"include_all_networks": include_all_networks}
            if third_party_instance_id:
                data["third_party_instance_id"] = third_party_instance_id
            if limit:
                data["limit"] = limit
            if since_token:
                data["since"] = since_token

            data["filter"] = search_filter

            try:
                response = await self.client.post_json(
                    destination=remote_server, path=path, data=data, ignore_backoff=True
                )
            except HttpResponseException as e:
                if e.code == 403:
                    raise SynapseError(
                        403,
                        "You are not allowed to view the public rooms list of %s"
                        % (remote_server,),
                        errcode=Codes.FORBIDDEN,
                    )
                raise
        else:
            args: Dict[str, Union[str, Iterable[str]]] = {
                "include_all_networks": "true" if include_all_networks else "false"
            }
            if third_party_instance_id:
                args["third_party_instance_id"] = third_party_instance_id
            if limit:
                args["limit"] = str(limit)
            if since_token:
                args["since"] = since_token

            try:
                response = await self.client.get_json(
                    destination=remote_server, path=path, args=args, ignore_backoff=True
                )
            except HttpResponseException as e:
                if e.code == 403:
                    raise SynapseError(
                        403,
                        "You are not allowed to view the public rooms list of %s"
                        % (remote_server,),
                        errcode=Codes.FORBIDDEN,
                    )
                raise

        return response

    async def exchange_third_party_invite(
        self, destination: str, room_id: str, event_dict: JsonDict
    ) -> JsonDict:
        path = _create_v1_path("/exchange_third_party_invite/%s", room_id)

        return await self.client.put_json(
            destination=destination, path=path, data=event_dict
        )

    async def get_event_auth(
        self, destination: str, room_id: str, event_id: str
    ) -> JsonDict:
        path = _create_v1_path("/event_auth/%s/%s", room_id, event_id)

        return await self.client.get_json(destination=destination, path=path)

    async def query_client_keys(
        self, destination: str, query_content: JsonDict, timeout: int
    ) -> JsonDict:
        """Query the device keys for a list of user ids hosted on a remote
        server.

        Request:
            {
              "device_keys": {
                "<user_id>": ["<device_id>"]
              }
            }

        Response:
            {
              "device_keys": {
                "<user_id>": {
                  "<device_id>": {...}
                }
              },
              "master_key": {
                "<user_id>": {...}
                }
              },
              "self_signing_key": {
                "<user_id>": {...}
              }
            }

        Args:
            destination: The server to query.
            query_content: The user ids to query.
        Returns:
            A dict containing device and cross-signing keys.
        """
        path = _create_v1_path("/user/keys/query")

        return await self.client.post_json(
            destination=destination, path=path, data=query_content, timeout=timeout
        )

    async def query_user_devices(
        self, destination: str, user_id: str, timeout: int
    ) -> JsonDict:
        """Query the devices for a user id hosted on a remote server.

        Response:
            {
              "stream_id": "...",
              "devices": [ { ... } ],
              "master_key": {
                "user_id": "<user_id>",
                "usage": [...],
                "keys": {...},
                "signatures": {
                  "<user_id>": {...}
                }
              },
              "self_signing_key": {
                "user_id": "<user_id>",
                "usage": [...],
                "keys": {...},
                "signatures": {
                  "<user_id>": {...}
                }
              }
            }

        Args:
            destination: The server to query.
            query_content: The user ids to query.
        Returns:
            A dict containing device and cross-signing keys.
        """
        path = _create_v1_path("/user/devices/%s", user_id)

        return await self.client.get_json(
            destination=destination, path=path, timeout=timeout
        )

    async def claim_client_keys(
        self,
        user: UserID,
        destination: str,
        query_content: JsonDict,
        timeout: Optional[int],
    ) -> JsonDict:
        """Claim one-time keys for a list of devices hosted on a remote server.

        Request:
            {
              "one_time_keys": {
                "<user_id>": {
                  "<device_id>": "<algorithm>"
                }
              }
            }

        Response:
            {
              "one_time_keys": {
                "<user_id>": {
                  "<device_id>": {
                    "<algorithm>:<key_id>": <OTK JSON>
                  }
                }
              }
            }

        Args:
            user: the user_id of the requesting user
            destination: The server to query.
            query_content: The user ids to query.
        Returns:
            A dict containing the one-time keys.
        """

        path = _create_v1_path("/user/keys/claim")

        return await self.client.post_json(
            destination=destination,
            path=path,
            data={"one_time_keys": query_content},
            timeout=timeout,
        )

    async def claim_client_keys_unstable(
        self,
        user: UserID,
        destination: str,
        query_content: JsonDict,
        timeout: Optional[int],
    ) -> JsonDict:
        """Claim one-time keys for a list of devices hosted on a remote server.

        Request:
            {
              "one_time_keys": {
                "<user_id>": {
                  "<device_id>": {"<algorithm>": <count>}
                }
              }
            }

        Response:
            {
              "one_time_keys": {
                "<user_id>": {
                  "<device_id>": {
                    "<algorithm>:<key_id>": <OTK JSON>
                  }
                }
              }
            }

        Args:
            user: the user_id of the requesting user
            destination: The server to query.
            query_content: The user ids to query.
        Returns:
            A dict containing the one-time keys.
        """
        path = _create_path(FEDERATION_UNSTABLE_PREFIX, "/user/keys/claim")

        return await self.client.post_json(
            destination=destination,
            path=path,
            data={"one_time_keys": query_content},
            timeout=timeout,
        )

    async def get_missing_events(
        self,
        destination: str,
        room_id: str,
        earliest_events: Iterable[str],
        latest_events: Iterable[str],
        limit: int,
        min_depth: int,
        timeout: int,
    ) -> JsonDict:
        path = _create_v1_path("/get_missing_events/%s", room_id)

        return await self.client.post_json(
            destination=destination,
            path=path,
            data={
                "limit": int(limit),
                "min_depth": int(min_depth),
                "earliest_events": earliest_events,
                "latest_events": latest_events,
            },
            timeout=timeout,
        )

    async def get_room_complexity(self, destination: str, room_id: str) -> JsonDict:
        """
        Args:
            destination: The remote server
            room_id: The room ID to ask about.
        """
        path = _create_path(FEDERATION_UNSTABLE_PREFIX, "/rooms/%s/complexity", room_id)

        return await self.client.get_json(destination=destination, path=path)

    async def get_room_hierarchy(
        self, destination: str, room_id: str, suggested_only: bool
    ) -> JsonDict:
        """
        Args:
            destination: The remote server
            room_id: The room ID to ask about.
            suggested_only: if True, only suggested rooms will be returned
        """
        path = _create_v1_path("/hierarchy/%s", room_id)

        return await self.client.get_json(
            destination=destination,
            path=path,
            args={"suggested_only": "true" if suggested_only else "false"},
        )

    async def get_room_hierarchy_unstable(
        self, destination: str, room_id: str, suggested_only: bool
    ) -> JsonDict:
        """
        Args:
            destination: The remote server
            room_id: The room ID to ask about.
            suggested_only: if True, only suggested rooms will be returned
        """
        path = _create_path(
            FEDERATION_UNSTABLE_PREFIX, "/org.matrix.msc2946/hierarchy/%s", room_id
        )

        return await self.client.get_json(
            destination=destination,
            path=path,
            args={"suggested_only": "true" if suggested_only else "false"},
        )

    async def get_account_status(
        self, destination: str, user_ids: List[str]
    ) -> JsonDict:
        """
        Args:
            destination: The remote server.
            user_ids: The user ID(s) for which to request account status(es).
        """
        path = _create_path(
            FEDERATION_UNSTABLE_PREFIX, "/org.matrix.msc3720/account_status"
        )

        return await self.client.post_json(
            destination=destination, path=path, data={"user_ids": user_ids}
        )

    async def download_media_r0(
        self,
        destination: str,
        media_id: str,
        output_stream: BinaryIO,
        max_size: int,
        max_timeout_ms: int,
    ) -> Tuple[int, Dict[bytes, List[bytes]]]:
        path = f"/_matrix/media/r0/download/{destination}/{media_id}"

        return await self.client.get_file(
            destination,
            path,
            output_stream=output_stream,
            max_size=max_size,
            args={
                # tell the remote server to 404 if it doesn't
                # recognise the server_name, to make sure we don't
                # end up with a routing loop.
                "allow_remote": "false",
                "timeout_ms": str(max_timeout_ms),
            },
        )

    async def download_media_v3(
        self,
        destination: str,
        media_id: str,
        output_stream: BinaryIO,
        max_size: int,
        max_timeout_ms: int,
    ) -> Tuple[int, Dict[bytes, List[bytes]]]:
        path = f"/_matrix/media/v3/download/{destination}/{media_id}"

        return await self.client.get_file(
            destination,
            path,
            output_stream=output_stream,
            max_size=max_size,
            args={
                # tell the remote server to 404 if it doesn't
                # recognise the server_name, to make sure we don't
                # end up with a routing loop.
                "allow_remote": "false",
                "timeout_ms": str(max_timeout_ms),
                # Matrix 1.7 allows for this to redirect to another URL, this should
                # just be ignored for an old homeserver, so always provide it.
                "allow_redirect": "true",
            },
            follow_redirects=True,
        )


def _create_path(federation_prefix: str, path: str, *args: str) -> str:
    """
    Ensures that all args are url encoded.
    """
    return federation_prefix + path % tuple(urllib.parse.quote(arg, "") for arg in args)


def _create_v1_path(path: str, *args: str) -> str:
    """Creates a path against V1 federation API from the path template and
    args. Ensures that all args are url encoded.

    Example:

        _create_v1_path("/event/%s", event_id)

    Args:
        path: String template for the path
        args: Args to insert into path. Each arg will be url encoded
    """
    return _create_path(FEDERATION_V1_PREFIX, path, *args)


def _create_v2_path(path: str, *args: str) -> str:
    """Creates a path against V2 federation API from the path template and
    args. Ensures that all args are url encoded.

    Example:

        _create_v2_path("/event/%s", event_id)

    Args:
        path: String template for the path
        args: Args to insert into path. Each arg will be url encoded
    """
    return _create_path(FEDERATION_V2_PREFIX, path, *args)


@attr.s(slots=True, auto_attribs=True)
class SendJoinResponse:
    """The parsed response of a `/send_join` request."""

    # The list of auth events from the /send_join response.
    auth_events: List[EventBase]
    # The list of state from the /send_join response.
    state: List[EventBase]
    # The raw join event from the /send_join response.
    event_dict: JsonDict
    # The parsed join event from the /send_join response. This will be None if
    # "event" is not included in the response.
    event: Optional[EventBase] = None

    # The room state is incomplete
    members_omitted: bool = False

    # List of servers in the room
    servers_in_room: Optional[List[str]] = None


@attr.s(slots=True, auto_attribs=True)
class StateRequestResponse:
    """The parsed response of a `/state` request."""

    auth_events: List[EventBase]
    state: List[EventBase]


@ijson.coroutine
def _event_parser(event_dict: JsonDict) -> Generator[None, Tuple[str, Any], None]:
    """Helper function for use with `ijson.kvitems_coro` to parse key-value pairs
    to add them to a given dictionary.
    """

    while True:
        key, value = yield
        event_dict[key] = value


@ijson.coroutine
def _event_list_parser(
    room_version: RoomVersion, events: List[EventBase]
) -> Generator[None, JsonDict, None]:
    """Helper function for use with `ijson.items_coro` to parse an array of
    events and add them to the given list.
    """

    while True:
        obj = yield
        event = make_event_from_dict(obj, room_version)
        events.append(event)


@ijson.coroutine
def _members_omitted_parser(response: SendJoinResponse) -> Generator[None, Any, None]:
    """Helper function for use with `ijson.items_coro`

    Parses the members_omitted field in send_join responses
    """
    while True:
        val = yield
        if not isinstance(val, bool):
            raise TypeError("members_omitted must be a boolean")
        response.members_omitted = val


@ijson.coroutine
def _servers_in_room_parser(response: SendJoinResponse) -> Generator[None, Any, None]:
    """Helper function for use with `ijson.items_coro`

    Parses the servers_in_room field in send_join responses
    """
    while True:
        val = yield
        if not isinstance(val, list) or any(not isinstance(x, str) for x in val):
            raise TypeError("servers_in_room must be a list of strings")
        response.servers_in_room = val


class SendJoinParser(ByteParser[SendJoinResponse]):
    """A parser for the response to `/send_join` requests.

    Args:
        room_version: The version of the room.
        v1_api: Whether the response is in the v1 format.
    """

    CONTENT_TYPE = "application/json"

    # /send_join responses can be huge, so we override the size limit here. The response
    # is parsed in a streaming manner, which helps alleviate the issue of memory
    # usage a bit.
    MAX_RESPONSE_SIZE = 500 * 1024 * 1024

    def __init__(self, room_version: RoomVersion, v1_api: bool):
        self._response = SendJoinResponse([], [], event_dict={})
        self._room_version = room_version
        self._coros: List[Generator[None, bytes, None]] = []

        # The V1 API has the shape of `[200, {...}]`, which we handle by
        # prefixing with `item.*`.
        prefix = "item." if v1_api else ""

        self._coros = [
            ijson.items_coro(
                _event_list_parser(room_version, self._response.state),
                prefix + "state.item",
                use_float=True,
            ),
            ijson.items_coro(
                _event_list_parser(room_version, self._response.auth_events),
                prefix + "auth_chain.item",
                use_float=True,
            ),
            ijson.kvitems_coro(
                _event_parser(self._response.event_dict),
                prefix + "event",
                use_float=True,
            ),
        ]

        if not v1_api:
            self._coros.append(
                ijson.items_coro(
                    _members_omitted_parser(self._response),
                    "members_omitted",
                    use_float="True",
                )
            )

            # Again, stable field name comes last
            self._coros.append(
                ijson.items_coro(
                    _servers_in_room_parser(self._response),
                    "servers_in_room",
                    use_float="True",
                )
            )

    def write(self, data: bytes) -> int:
        for c in self._coros:
            c.send(data)

        return len(data)

    def finish(self) -> SendJoinResponse:
        _close_coros(self._coros)

        if self._response.event_dict:
            self._response.event = make_event_from_dict(
                self._response.event_dict, self._room_version
            )
        return self._response


class _StateParser(ByteParser[StateRequestResponse]):
    """A parser for the response to `/state` requests.

    Args:
        room_version: The version of the room.
    """

    CONTENT_TYPE = "application/json"

    # As with /send_join, /state responses can be huge.
    MAX_RESPONSE_SIZE = 500 * 1024 * 1024

    def __init__(self, room_version: RoomVersion):
        self._response = StateRequestResponse([], [])
        self._room_version = room_version
        self._coros: List[Generator[None, bytes, None]] = [
            ijson.items_coro(
                _event_list_parser(room_version, self._response.state),
                "pdus.item",
                use_float=True,
            ),
            ijson.items_coro(
                _event_list_parser(room_version, self._response.auth_events),
                "auth_chain.item",
                use_float=True,
            ),
        ]

    def write(self, data: bytes) -> int:
        for c in self._coros:
            c.send(data)
        return len(data)

    def finish(self) -> StateRequestResponse:
        _close_coros(self._coros)
        return self._response


def _close_coros(coros: Iterable[Generator[None, bytes, None]]) -> None:
    """Close each of the given coroutines.

    Always calls .close() on each coroutine, even if doing so raises an exception.
    Any exceptions raised are aggregated into an ExceptionBundle.

    :raises ExceptionBundle: if at least one coroutine fails to close.
    """
    exceptions = []
    for c in coros:
        try:
            c.close()
        except Exception as e:
            exceptions.append(e)

    if exceptions:
        # raise from the first exception so that the traceback has slightly more context
        raise ExceptionBundle(
            f"There were {len(exceptions)} errors closing coroutines", exceptions
        ) from exceptions[0]