summary refs log tree commit diff
path: root/tests/rest/media/test_url_preview.py
blob: e91dc581c2045e699b5a25b44d79110bf202e30a (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
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
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
# Copyright 2018 New Vector Ltd
# Copyright 2021 The Matrix.org Foundation C.I.C.
#
# 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 base64
import json
import os
import re
from typing import Any, Dict, Optional, Sequence, Tuple, Type
from urllib.parse import quote, urlencode

from twisted.internet._resolver import HostResolution
from twisted.internet.address import IPv4Address, IPv6Address
from twisted.internet.error import DNSLookupError
from twisted.internet.interfaces import IAddress, IResolutionReceiver
from twisted.test.proto_helpers import AccumulatingProtocol, MemoryReactor

from synapse.config.oembed import OEmbedEndpointConfig
from synapse.rest.media.media_repository_resource import MediaRepositoryResource
from synapse.rest.media.preview_url_resource import IMAGE_CACHE_EXPIRY_MS
from synapse.server import HomeServer
from synapse.types import JsonDict
from synapse.util import Clock
from synapse.util.stringutils import parse_and_validate_mxc_uri

from tests import unittest
from tests.server import FakeTransport
from tests.test_utils import SMALL_PNG
from tests.utils import MockClock

try:
    import lxml
except ImportError:
    lxml = None


class URLPreviewTests(unittest.HomeserverTestCase):
    if not lxml:
        skip = "url preview feature requires lxml"

    hijack_auth = True
    user_id = "@test:user"
    end_content = (
        b"<html><head>"
        b'<meta property="og:title" content="~matrix~" />'
        b'<meta property="og:description" content="hi" />'
        b"</head></html>"
    )

    def make_homeserver(self, reactor: MemoryReactor, clock: Clock) -> HomeServer:
        config = self.default_config()
        config["url_preview_enabled"] = True
        config["max_spider_size"] = 9999999
        config["url_preview_ip_range_blacklist"] = (
            "192.168.1.1",
            "1.0.0.0/8",
            "3fff:ffff:ffff:ffff:ffff:ffff:ffff:ffff",
            "2001:800::/21",
        )
        config["url_preview_ip_range_whitelist"] = ("1.1.1.1",)
        config["url_preview_accept_language"] = [
            "en-UK",
            "en-US;q=0.9",
            "fr;q=0.8",
            "*;q=0.7",
        ]

        self.storage_path = self.mktemp()
        self.media_store_path = self.mktemp()
        os.mkdir(self.storage_path)
        os.mkdir(self.media_store_path)
        config["media_store_path"] = self.media_store_path

        provider_config = {
            "module": "synapse.media.storage_provider.FileStorageProviderBackend",
            "store_local": True,
            "store_synchronous": False,
            "store_remote": True,
            "config": {"directory": self.storage_path},
        }

        config["media_storage_providers"] = [provider_config]

        hs = self.setup_test_homeserver(config=config)

        # After the hs is created, modify the parsed oEmbed config (to avoid
        # messing with files).
        #
        # Note that HTTP URLs are used to avoid having to deal with TLS in tests.
        hs.config.oembed.oembed_patterns = [
            OEmbedEndpointConfig(
                api_endpoint="http://publish.twitter.com/oembed",
                url_patterns=[
                    re.compile(r"http://twitter\.com/.+/status/.+"),
                ],
                formats=None,
            ),
            OEmbedEndpointConfig(
                api_endpoint="http://www.hulu.com/api/oembed.{format}",
                url_patterns=[
                    re.compile(r"http://www\.hulu\.com/watch/.+"),
                ],
                formats=["json"],
            ),
        ]

        return hs

    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
        self.media_repo = hs.get_media_repository_resource()
        self.preview_url = self.media_repo.children[b"preview_url"]

        self.lookups: Dict[str, Any] = {}

        class Resolver:
            def resolveHostName(
                _self,
                resolutionReceiver: IResolutionReceiver,
                hostName: str,
                portNumber: int = 0,
                addressTypes: Optional[Sequence[Type[IAddress]]] = None,
                transportSemantics: str = "TCP",
            ) -> IResolutionReceiver:
                resolution = HostResolution(hostName)
                resolutionReceiver.resolutionBegan(resolution)
                if hostName not in self.lookups:
                    raise DNSLookupError("OH NO")

                for i in self.lookups[hostName]:
                    resolutionReceiver.addressResolved(i[0]("TCP", i[1], portNumber))
                resolutionReceiver.resolutionComplete()
                return resolutionReceiver

        self.reactor.nameResolver = Resolver()  # type: ignore[assignment]

    def create_test_resource(self) -> MediaRepositoryResource:
        return self.hs.get_media_repository_resource()

    def _assert_small_png(self, json_body: JsonDict) -> None:
        """Assert properties from the SMALL_PNG test image."""
        self.assertTrue(json_body["og:image"].startswith("mxc://"))
        self.assertEqual(json_body["og:image:height"], 1)
        self.assertEqual(json_body["og:image:width"], 1)
        self.assertEqual(json_body["og:image:type"], "image/png")
        self.assertEqual(json_body["matrix:image:size"], 67)

    def test_cache_returns_correct_type(self) -> None:
        self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")]

        channel = self.make_request(
            "GET",
            "preview_url?url=http://matrix.org",
            shorthand=False,
            await_result=False,
        )
        self.pump()

        client = self.reactor.tcpClients[0][2].buildProtocol(None)
        server = AccumulatingProtocol()
        server.makeConnection(FakeTransport(client, self.reactor))
        client.makeConnection(FakeTransport(server, self.reactor))
        client.dataReceived(
            b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\nContent-Type: text/html\r\n\r\n"
            % (len(self.end_content),)
            + self.end_content
        )

        self.pump()
        self.assertEqual(channel.code, 200)
        self.assertEqual(
            channel.json_body, {"og:title": "~matrix~", "og:description": "hi"}
        )

        # Check the cache returns the correct response
        channel = self.make_request(
            "GET", "preview_url?url=http://matrix.org", shorthand=False
        )

        # Check the cache response has the same content
        self.assertEqual(channel.code, 200)
        self.assertEqual(
            channel.json_body, {"og:title": "~matrix~", "og:description": "hi"}
        )

        # Clear the in-memory cache
        self.assertIn("http://matrix.org", self.preview_url._cache)
        self.preview_url._cache.pop("http://matrix.org")
        self.assertNotIn("http://matrix.org", self.preview_url._cache)

        # Check the database cache returns the correct response
        channel = self.make_request(
            "GET", "preview_url?url=http://matrix.org", shorthand=False
        )

        # Check the cache response has the same content
        self.assertEqual(channel.code, 200)
        self.assertEqual(
            channel.json_body, {"og:title": "~matrix~", "og:description": "hi"}
        )

    def test_non_ascii_preview_httpequiv(self) -> None:
        self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")]

        end_content = (
            b"<html><head>"
            b'<meta http-equiv="Content-Type" content="text/html; charset=windows-1251"/>'
            b'<meta property="og:title" content="\xe4\xea\xe0" />'
            b'<meta property="og:description" content="hi" />'
            b"</head></html>"
        )

        channel = self.make_request(
            "GET",
            "preview_url?url=http://matrix.org",
            shorthand=False,
            await_result=False,
        )
        self.pump()

        client = self.reactor.tcpClients[0][2].buildProtocol(None)
        server = AccumulatingProtocol()
        server.makeConnection(FakeTransport(client, self.reactor))
        client.makeConnection(FakeTransport(server, self.reactor))
        client.dataReceived(
            (
                b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                b'Content-Type: text/html; charset="utf8"\r\n\r\n'
            )
            % (len(end_content),)
            + end_content
        )

        self.pump()
        self.assertEqual(channel.code, 200)
        self.assertEqual(channel.json_body["og:title"], "\u0434\u043a\u0430")

    def test_video_rejected(self) -> None:
        self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")]

        end_content = b"anything"

        channel = self.make_request(
            "GET",
            "preview_url?url=http://matrix.org",
            shorthand=False,
            await_result=False,
        )
        self.pump()

        client = self.reactor.tcpClients[0][2].buildProtocol(None)
        server = AccumulatingProtocol()
        server.makeConnection(FakeTransport(client, self.reactor))
        client.makeConnection(FakeTransport(server, self.reactor))
        client.dataReceived(
            (
                b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                b"Content-Type: video/mp4\r\n\r\n"
            )
            % (len(end_content))
            + end_content
        )

        self.pump()
        self.assertEqual(channel.code, 502)
        self.assertEqual(
            channel.json_body,
            {
                "errcode": "M_UNKNOWN",
                "error": "Requested file's content type not allowed for this operation: video/mp4",
            },
        )

    def test_audio_rejected(self) -> None:
        self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")]

        end_content = b"anything"

        channel = self.make_request(
            "GET",
            "preview_url?url=http://matrix.org",
            shorthand=False,
            await_result=False,
        )
        self.pump()

        client = self.reactor.tcpClients[0][2].buildProtocol(None)
        server = AccumulatingProtocol()
        server.makeConnection(FakeTransport(client, self.reactor))
        client.makeConnection(FakeTransport(server, self.reactor))
        client.dataReceived(
            (
                b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                b"Content-Type: audio/aac\r\n\r\n"
            )
            % (len(end_content))
            + end_content
        )

        self.pump()
        self.assertEqual(channel.code, 502)
        self.assertEqual(
            channel.json_body,
            {
                "errcode": "M_UNKNOWN",
                "error": "Requested file's content type not allowed for this operation: audio/aac",
            },
        )

    def test_non_ascii_preview_content_type(self) -> None:
        self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")]

        end_content = (
            b"<html><head>"
            b'<meta property="og:title" content="\xe4\xea\xe0" />'
            b'<meta property="og:description" content="hi" />'
            b"</head></html>"
        )

        channel = self.make_request(
            "GET",
            "preview_url?url=http://matrix.org",
            shorthand=False,
            await_result=False,
        )
        self.pump()

        client = self.reactor.tcpClients[0][2].buildProtocol(None)
        server = AccumulatingProtocol()
        server.makeConnection(FakeTransport(client, self.reactor))
        client.makeConnection(FakeTransport(server, self.reactor))
        client.dataReceived(
            (
                b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                b'Content-Type: text/html; charset="windows-1251"\r\n\r\n'
            )
            % (len(end_content),)
            + end_content
        )

        self.pump()
        self.assertEqual(channel.code, 200)
        self.assertEqual(channel.json_body["og:title"], "\u0434\u043a\u0430")

    def test_overlong_title(self) -> None:
        self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")]

        end_content = (
            b"<html><head>"
            b"<title>" + b"x" * 2000 + b"</title>"
            b'<meta property="og:description" content="hi" />'
            b"</head></html>"
        )

        channel = self.make_request(
            "GET",
            "preview_url?url=http://matrix.org",
            shorthand=False,
            await_result=False,
        )
        self.pump()

        client = self.reactor.tcpClients[0][2].buildProtocol(None)
        server = AccumulatingProtocol()
        server.makeConnection(FakeTransport(client, self.reactor))
        client.makeConnection(FakeTransport(server, self.reactor))
        client.dataReceived(
            (
                b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                b'Content-Type: text/html; charset="windows-1251"\r\n\r\n'
            )
            % (len(end_content),)
            + end_content
        )

        self.pump()
        self.assertEqual(channel.code, 200)
        res = channel.json_body
        # We should only see the `og:description` field, as `title` is too long and should be stripped out
        self.assertCountEqual(["og:description"], res.keys())

    def test_ipaddr(self) -> None:
        """
        IP addresses can be previewed directly.
        """
        self.lookups["example.com"] = [(IPv4Address, "10.1.2.3")]

        channel = self.make_request(
            "GET",
            "preview_url?url=http://example.com",
            shorthand=False,
            await_result=False,
        )
        self.pump()

        client = self.reactor.tcpClients[0][2].buildProtocol(None)
        server = AccumulatingProtocol()
        server.makeConnection(FakeTransport(client, self.reactor))
        client.makeConnection(FakeTransport(server, self.reactor))
        client.dataReceived(
            b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\nContent-Type: text/html\r\n\r\n"
            % (len(self.end_content),)
            + self.end_content
        )

        self.pump()
        self.assertEqual(channel.code, 200)
        self.assertEqual(
            channel.json_body, {"og:title": "~matrix~", "og:description": "hi"}
        )

    def test_blacklisted_ip_specific(self) -> None:
        """
        Blacklisted IP addresses, found via DNS, are not spidered.
        """
        self.lookups["example.com"] = [(IPv4Address, "192.168.1.1")]

        channel = self.make_request(
            "GET", "preview_url?url=http://example.com", shorthand=False
        )

        # No requests made.
        self.assertEqual(len(self.reactor.tcpClients), 0)
        self.assertEqual(channel.code, 502)
        self.assertEqual(
            channel.json_body,
            {
                "errcode": "M_UNKNOWN",
                "error": "DNS resolution failure during URL preview generation",
            },
        )

    def test_blacklisted_ip_range(self) -> None:
        """
        Blacklisted IP ranges, IPs found over DNS, are not spidered.
        """
        self.lookups["example.com"] = [(IPv4Address, "1.1.1.2")]

        channel = self.make_request(
            "GET", "preview_url?url=http://example.com", shorthand=False
        )

        self.assertEqual(channel.code, 502)
        self.assertEqual(
            channel.json_body,
            {
                "errcode": "M_UNKNOWN",
                "error": "DNS resolution failure during URL preview generation",
            },
        )

    def test_blacklisted_ip_specific_direct(self) -> None:
        """
        Blacklisted IP addresses, accessed directly, are not spidered.
        """
        channel = self.make_request(
            "GET", "preview_url?url=http://192.168.1.1", shorthand=False
        )

        # No requests made.
        self.assertEqual(len(self.reactor.tcpClients), 0)
        self.assertEqual(
            channel.json_body,
            {
                "errcode": "M_UNKNOWN",
                "error": "IP address blocked by IP blacklist entry",
            },
        )
        self.assertEqual(channel.code, 403)

    def test_blacklisted_ip_range_direct(self) -> None:
        """
        Blacklisted IP ranges, accessed directly, are not spidered.
        """
        channel = self.make_request(
            "GET", "preview_url?url=http://1.1.1.2", shorthand=False
        )

        self.assertEqual(channel.code, 403)
        self.assertEqual(
            channel.json_body,
            {
                "errcode": "M_UNKNOWN",
                "error": "IP address blocked by IP blacklist entry",
            },
        )

    def test_blacklisted_ip_range_whitelisted_ip(self) -> None:
        """
        Blacklisted but then subsequently whitelisted IP addresses can be
        spidered.
        """
        self.lookups["example.com"] = [(IPv4Address, "1.1.1.1")]

        channel = self.make_request(
            "GET",
            "preview_url?url=http://example.com",
            shorthand=False,
            await_result=False,
        )
        self.pump()

        client = self.reactor.tcpClients[0][2].buildProtocol(None)

        server = AccumulatingProtocol()
        server.makeConnection(FakeTransport(client, self.reactor))
        client.makeConnection(FakeTransport(server, self.reactor))

        client.dataReceived(
            b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\nContent-Type: text/html\r\n\r\n"
            % (len(self.end_content),)
            + self.end_content
        )

        self.pump()
        self.assertEqual(channel.code, 200)
        self.assertEqual(
            channel.json_body, {"og:title": "~matrix~", "og:description": "hi"}
        )

    def test_blacklisted_ip_with_external_ip(self) -> None:
        """
        If a hostname resolves a blacklisted IP, even if there's a
        non-blacklisted one, it will be rejected.
        """
        # Hardcode the URL resolving to the IP we want.
        self.lookups["example.com"] = [
            (IPv4Address, "1.1.1.2"),
            (IPv4Address, "10.1.2.3"),
        ]

        channel = self.make_request(
            "GET", "preview_url?url=http://example.com", shorthand=False
        )
        self.assertEqual(channel.code, 502)
        self.assertEqual(
            channel.json_body,
            {
                "errcode": "M_UNKNOWN",
                "error": "DNS resolution failure during URL preview generation",
            },
        )

    def test_blacklisted_ipv6_specific(self) -> None:
        """
        Blacklisted IP addresses, found via DNS, are not spidered.
        """
        self.lookups["example.com"] = [
            (IPv6Address, "3fff:ffff:ffff:ffff:ffff:ffff:ffff:ffff")
        ]

        channel = self.make_request(
            "GET", "preview_url?url=http://example.com", shorthand=False
        )

        # No requests made.
        self.assertEqual(len(self.reactor.tcpClients), 0)
        self.assertEqual(channel.code, 502)
        self.assertEqual(
            channel.json_body,
            {
                "errcode": "M_UNKNOWN",
                "error": "DNS resolution failure during URL preview generation",
            },
        )

    def test_blacklisted_ipv6_range(self) -> None:
        """
        Blacklisted IP ranges, IPs found over DNS, are not spidered.
        """
        self.lookups["example.com"] = [(IPv6Address, "2001:800::1")]

        channel = self.make_request(
            "GET", "preview_url?url=http://example.com", shorthand=False
        )

        self.assertEqual(channel.code, 502)
        self.assertEqual(
            channel.json_body,
            {
                "errcode": "M_UNKNOWN",
                "error": "DNS resolution failure during URL preview generation",
            },
        )

    def test_OPTIONS(self) -> None:
        """
        OPTIONS returns the OPTIONS.
        """
        channel = self.make_request(
            "OPTIONS", "preview_url?url=http://example.com", shorthand=False
        )
        self.assertEqual(channel.code, 200)
        self.assertEqual(channel.json_body, {})

    def test_accept_language_config_option(self) -> None:
        """
        Accept-Language header is sent to the remote server
        """
        self.lookups["example.com"] = [(IPv4Address, "10.1.2.3")]

        # Build and make a request to the server
        channel = self.make_request(
            "GET",
            "preview_url?url=http://example.com",
            shorthand=False,
            await_result=False,
        )
        self.pump()

        # Extract Synapse's tcp client
        client = self.reactor.tcpClients[0][2].buildProtocol(None)

        # Build a fake remote server to reply with
        server = AccumulatingProtocol()

        # Connect the two together
        server.makeConnection(FakeTransport(client, self.reactor))
        client.makeConnection(FakeTransport(server, self.reactor))

        # Tell Synapse that it has received some data from the remote server
        client.dataReceived(
            b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\nContent-Type: text/html\r\n\r\n"
            % (len(self.end_content),)
            + self.end_content
        )

        # Move the reactor along until we get a response on our original channel
        self.pump()
        self.assertEqual(channel.code, 200)
        self.assertEqual(
            channel.json_body, {"og:title": "~matrix~", "og:description": "hi"}
        )

        # Check that the server received the Accept-Language header as part
        # of the request from Synapse
        self.assertIn(
            (
                b"Accept-Language: en-UK\r\n"
                b"Accept-Language: en-US;q=0.9\r\n"
                b"Accept-Language: fr;q=0.8\r\n"
                b"Accept-Language: *;q=0.7"
            ),
            server.data,
        )

    def test_nonexistent_image(self) -> None:
        """If the preview image doesn't exist, ensure some data is returned."""
        self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")]

        result = (
            b"""<html><body><img src="http://cdn.matrix.org/foo.jpg"></body></html>"""
        )

        channel = self.make_request(
            "GET",
            "preview_url?url=http://matrix.org",
            shorthand=False,
            await_result=False,
        )
        self.pump()

        client = self.reactor.tcpClients[0][2].buildProtocol(None)
        server = AccumulatingProtocol()
        server.makeConnection(FakeTransport(client, self.reactor))
        client.makeConnection(FakeTransport(server, self.reactor))
        client.dataReceived(
            (
                b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                b'Content-Type: text/html; charset="utf8"\r\n\r\n'
            )
            % (len(result),)
            + result
        )

        self.pump()
        self.assertEqual(channel.code, 200)

        # The image should not be in the result.
        self.assertNotIn("og:image", channel.json_body)

    def test_oembed_failure(self) -> None:
        """If the autodiscovered oEmbed URL fails, ensure some data is returned."""
        self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")]

        result = b"""
        <title>oEmbed Autodiscovery Fail</title>
        <link rel="alternate" type="application/json+oembed"
            href="http://example.com/oembed?url=http%3A%2F%2Fmatrix.org&format=json"
            title="matrixdotorg" />
        """

        channel = self.make_request(
            "GET",
            "preview_url?url=http://matrix.org",
            shorthand=False,
            await_result=False,
        )
        self.pump()

        client = self.reactor.tcpClients[0][2].buildProtocol(None)
        server = AccumulatingProtocol()
        server.makeConnection(FakeTransport(client, self.reactor))
        client.makeConnection(FakeTransport(server, self.reactor))
        client.dataReceived(
            (
                b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                b'Content-Type: text/html; charset="utf8"\r\n\r\n'
            )
            % (len(result),)
            + result
        )

        self.pump()
        self.assertEqual(channel.code, 200)

        # The image should not be in the result.
        self.assertEqual(channel.json_body["og:title"], "oEmbed Autodiscovery Fail")

    def test_data_url(self) -> None:
        """
        Requesting to preview a data URL is not supported.
        """
        self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")]

        data = base64.b64encode(SMALL_PNG).decode()

        query_params = urlencode(
            {
                "url": f'<html><head><img src="data:image/png;base64,{data}" /></head></html>'
            }
        )

        channel = self.make_request(
            "GET",
            f"preview_url?{query_params}",
            shorthand=False,
        )
        self.pump()

        self.assertEqual(channel.code, 500)

    def test_inline_data_url(self) -> None:
        """
        An inline image (as a data URL) should be parsed properly.
        """
        self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")]

        data = base64.b64encode(SMALL_PNG)

        end_content = (
            b"<html><head>" b'<img src="data:image/png;base64,%s" />' b"</head></html>"
        ) % (data,)

        channel = self.make_request(
            "GET",
            "preview_url?url=http://matrix.org",
            shorthand=False,
            await_result=False,
        )
        self.pump()

        client = self.reactor.tcpClients[0][2].buildProtocol(None)
        server = AccumulatingProtocol()
        server.makeConnection(FakeTransport(client, self.reactor))
        client.makeConnection(FakeTransport(server, self.reactor))
        client.dataReceived(
            (
                b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                b'Content-Type: text/html; charset="utf8"\r\n\r\n'
            )
            % (len(end_content),)
            + end_content
        )

        self.pump()
        self.assertEqual(channel.code, 200)
        self._assert_small_png(channel.json_body)

    def test_oembed_photo(self) -> None:
        """Test an oEmbed endpoint which returns a 'photo' type which redirects the preview to a new URL."""
        self.lookups["publish.twitter.com"] = [(IPv4Address, "10.1.2.3")]
        self.lookups["cdn.twitter.com"] = [(IPv4Address, "10.1.2.3")]

        result = {
            "version": "1.0",
            "type": "photo",
            "url": "http://cdn.twitter.com/matrixdotorg",
        }
        oembed_content = json.dumps(result).encode("utf-8")

        channel = self.make_request(
            "GET",
            "preview_url?url=http://twitter.com/matrixdotorg/status/12345",
            shorthand=False,
            await_result=False,
        )
        self.pump()

        client = self.reactor.tcpClients[0][2].buildProtocol(None)
        server = AccumulatingProtocol()
        server.makeConnection(FakeTransport(client, self.reactor))
        client.makeConnection(FakeTransport(server, self.reactor))
        client.dataReceived(
            (
                b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                b'Content-Type: application/json; charset="utf8"\r\n\r\n'
            )
            % (len(oembed_content),)
            + oembed_content
        )

        self.pump()

        # Ensure a second request is made to the photo URL.
        client = self.reactor.tcpClients[1][2].buildProtocol(None)
        server = AccumulatingProtocol()
        server.makeConnection(FakeTransport(client, self.reactor))
        client.makeConnection(FakeTransport(server, self.reactor))
        client.dataReceived(
            (
                b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                b"Content-Type: image/png\r\n\r\n"
            )
            % (len(SMALL_PNG),)
            + SMALL_PNG
        )

        self.pump()

        # Ensure the URL is what was requested.
        self.assertIn(b"/matrixdotorg", server.data)

        self.assertEqual(channel.code, 200)
        body = channel.json_body
        self.assertEqual(body["og:url"], "http://twitter.com/matrixdotorg/status/12345")
        self._assert_small_png(body)

    def test_oembed_rich(self) -> None:
        """Test an oEmbed endpoint which returns HTML content via the 'rich' type."""
        self.lookups["publish.twitter.com"] = [(IPv4Address, "10.1.2.3")]

        result = {
            "version": "1.0",
            "type": "rich",
            # Note that this provides the author, not the title.
            "author_name": "Alice",
            "html": "<div>Content Preview</div>",
        }
        end_content = json.dumps(result).encode("utf-8")

        channel = self.make_request(
            "GET",
            "preview_url?url=http://twitter.com/matrixdotorg/status/12345",
            shorthand=False,
            await_result=False,
        )
        self.pump()

        client = self.reactor.tcpClients[0][2].buildProtocol(None)
        server = AccumulatingProtocol()
        server.makeConnection(FakeTransport(client, self.reactor))
        client.makeConnection(FakeTransport(server, self.reactor))
        client.dataReceived(
            (
                b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                b'Content-Type: application/json; charset="utf8"\r\n\r\n'
            )
            % (len(end_content),)
            + end_content
        )

        self.pump()
        self.assertEqual(channel.code, 200)
        body = channel.json_body
        self.assertEqual(
            body,
            {
                "og:url": "http://twitter.com/matrixdotorg/status/12345",
                "og:title": "Alice",
                "og:description": "Content Preview",
            },
        )

    def test_oembed_format(self) -> None:
        """Test an oEmbed endpoint which requires the format in the URL."""
        self.lookups["www.hulu.com"] = [(IPv4Address, "10.1.2.3")]

        result = {
            "version": "1.0",
            "type": "rich",
            "html": "<div>Content Preview</div>",
        }
        end_content = json.dumps(result).encode("utf-8")

        channel = self.make_request(
            "GET",
            "preview_url?url=http://www.hulu.com/watch/12345",
            shorthand=False,
            await_result=False,
        )
        self.pump()

        client = self.reactor.tcpClients[0][2].buildProtocol(None)
        server = AccumulatingProtocol()
        server.makeConnection(FakeTransport(client, self.reactor))
        client.makeConnection(FakeTransport(server, self.reactor))
        client.dataReceived(
            (
                b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                b'Content-Type: application/json; charset="utf8"\r\n\r\n'
            )
            % (len(end_content),)
            + end_content
        )

        self.pump()

        # The {format} should have been turned into json.
        self.assertIn(b"/api/oembed.json", server.data)
        # A URL parameter of format=json should be provided.
        self.assertIn(b"format=json", server.data)

        self.assertEqual(channel.code, 200)
        body = channel.json_body
        self.assertEqual(
            body,
            {
                "og:url": "http://www.hulu.com/watch/12345",
                "og:description": "Content Preview",
            },
        )

    def test_oembed_autodiscovery(self) -> None:
        """
        Autodiscovery works by finding the link in the HTML response and then requesting an oEmbed URL.
        1. Request a preview of a URL which is not known to the oEmbed code.
        2. It returns HTML including a link to an oEmbed preview.
        3. The oEmbed preview is requested and returns a URL for an image.
        4. The image is requested for thumbnailing.
        """
        # This is a little cheesy in that we use the www subdomain (which isn't the
        # list of oEmbed patterns) to get "raw" HTML response.
        self.lookups["www.twitter.com"] = [(IPv4Address, "10.1.2.3")]
        self.lookups["publish.twitter.com"] = [(IPv4Address, "10.1.2.3")]
        self.lookups["cdn.twitter.com"] = [(IPv4Address, "10.1.2.3")]

        result = b"""
        <link rel="alternate" type="application/json+oembed"
            href="http://publish.twitter.com/oembed?url=http%3A%2F%2Fcdn.twitter.com%2Fmatrixdotorg%2Fstatus%2F12345&format=json"
            title="matrixdotorg" />
        """

        channel = self.make_request(
            "GET",
            "preview_url?url=http://www.twitter.com/matrixdotorg/status/12345",
            shorthand=False,
            await_result=False,
        )
        self.pump()

        client = self.reactor.tcpClients[0][2].buildProtocol(None)
        server = AccumulatingProtocol()
        server.makeConnection(FakeTransport(client, self.reactor))
        client.makeConnection(FakeTransport(server, self.reactor))
        client.dataReceived(
            (
                b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                b'Content-Type: text/html; charset="utf8"\r\n\r\n'
            )
            % (len(result),)
            + result
        )

        self.pump()

        # The oEmbed response.
        result2 = {
            "version": "1.0",
            "type": "photo",
            "url": "http://cdn.twitter.com/matrixdotorg",
        }
        oembed_content = json.dumps(result2).encode("utf-8")

        # Ensure a second request is made to the oEmbed URL.
        client = self.reactor.tcpClients[1][2].buildProtocol(None)
        server = AccumulatingProtocol()
        server.makeConnection(FakeTransport(client, self.reactor))
        client.makeConnection(FakeTransport(server, self.reactor))
        client.dataReceived(
            (
                b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                b'Content-Type: application/json; charset="utf8"\r\n\r\n'
            )
            % (len(oembed_content),)
            + oembed_content
        )

        self.pump()

        # Ensure the URL is what was requested.
        self.assertIn(b"/oembed?", server.data)

        # Ensure a third request is made to the photo URL.
        client = self.reactor.tcpClients[2][2].buildProtocol(None)
        server = AccumulatingProtocol()
        server.makeConnection(FakeTransport(client, self.reactor))
        client.makeConnection(FakeTransport(server, self.reactor))
        client.dataReceived(
            (
                b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                b"Content-Type: image/png\r\n\r\n"
            )
            % (len(SMALL_PNG),)
            + SMALL_PNG
        )

        self.pump()

        # Ensure the URL is what was requested.
        self.assertIn(b"/matrixdotorg", server.data)

        self.assertEqual(channel.code, 200)
        body = channel.json_body
        self.assertEqual(
            body["og:url"], "http://www.twitter.com/matrixdotorg/status/12345"
        )
        self._assert_small_png(body)

    def _download_image(self) -> Tuple[str, str]:
        """Downloads an image into the URL cache.
        Returns:
            A (host, media_id) tuple representing the MXC URI of the image.
        """
        self.lookups["cdn.twitter.com"] = [(IPv4Address, "10.1.2.3")]

        channel = self.make_request(
            "GET",
            "preview_url?url=http://cdn.twitter.com/matrixdotorg",
            shorthand=False,
            await_result=False,
        )
        self.pump()

        client = self.reactor.tcpClients[0][2].buildProtocol(None)
        server = AccumulatingProtocol()
        server.makeConnection(FakeTransport(client, self.reactor))
        client.makeConnection(FakeTransport(server, self.reactor))
        client.dataReceived(
            b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\nContent-Type: image/png\r\n\r\n"
            % (len(SMALL_PNG),)
            + SMALL_PNG
        )

        self.pump()
        self.assertEqual(channel.code, 200)
        body = channel.json_body
        mxc_uri = body["og:image"]
        host, _port, media_id = parse_and_validate_mxc_uri(mxc_uri)
        self.assertIsNone(_port)
        return host, media_id

    def test_storage_providers_exclude_files(self) -> None:
        """Test that files are not stored in or fetched from storage providers."""
        host, media_id = self._download_image()

        rel_file_path = self.preview_url.filepaths.url_cache_filepath_rel(media_id)
        media_store_path = os.path.join(self.media_store_path, rel_file_path)
        storage_provider_path = os.path.join(self.storage_path, rel_file_path)

        # Check storage
        self.assertTrue(os.path.isfile(media_store_path))
        self.assertFalse(
            os.path.isfile(storage_provider_path),
            "URL cache file was unexpectedly stored in a storage provider",
        )

        # Check fetching
        channel = self.make_request(
            "GET",
            f"download/{host}/{media_id}",
            shorthand=False,
            await_result=False,
        )
        self.pump()
        self.assertEqual(channel.code, 200)

        # Move cached file into the storage provider
        os.makedirs(os.path.dirname(storage_provider_path), exist_ok=True)
        os.rename(media_store_path, storage_provider_path)

        channel = self.make_request(
            "GET",
            f"download/{host}/{media_id}",
            shorthand=False,
            await_result=False,
        )
        self.pump()
        self.assertEqual(
            channel.code,
            404,
            "URL cache file was unexpectedly retrieved from a storage provider",
        )

    def test_storage_providers_exclude_thumbnails(self) -> None:
        """Test that thumbnails are not stored in or fetched from storage providers."""
        host, media_id = self._download_image()

        rel_thumbnail_path = (
            self.preview_url.filepaths.url_cache_thumbnail_directory_rel(media_id)
        )
        media_store_thumbnail_path = os.path.join(
            self.media_store_path, rel_thumbnail_path
        )
        storage_provider_thumbnail_path = os.path.join(
            self.storage_path, rel_thumbnail_path
        )

        # Check storage
        self.assertTrue(os.path.isdir(media_store_thumbnail_path))
        self.assertFalse(
            os.path.isdir(storage_provider_thumbnail_path),
            "URL cache thumbnails were unexpectedly stored in a storage provider",
        )

        # Check fetching
        channel = self.make_request(
            "GET",
            f"thumbnail/{host}/{media_id}?width=32&height=32&method=scale",
            shorthand=False,
            await_result=False,
        )
        self.pump()
        self.assertEqual(channel.code, 200)

        # Remove the original, otherwise thumbnails will regenerate
        rel_file_path = self.preview_url.filepaths.url_cache_filepath_rel(media_id)
        media_store_path = os.path.join(self.media_store_path, rel_file_path)
        os.remove(media_store_path)

        # Move cached thumbnails into the storage provider
        os.makedirs(os.path.dirname(storage_provider_thumbnail_path), exist_ok=True)
        os.rename(media_store_thumbnail_path, storage_provider_thumbnail_path)

        channel = self.make_request(
            "GET",
            f"thumbnail/{host}/{media_id}?width=32&height=32&method=scale",
            shorthand=False,
            await_result=False,
        )
        self.pump()
        self.assertEqual(
            channel.code,
            404,
            "URL cache thumbnail was unexpectedly retrieved from a storage provider",
        )

    def test_cache_expiry(self) -> None:
        """Test that URL cache files and thumbnails are cleaned up properly on expiry."""
        self.preview_url.clock = MockClock()

        _host, media_id = self._download_image()

        file_path = self.preview_url.filepaths.url_cache_filepath(media_id)
        file_dirs = self.preview_url.filepaths.url_cache_filepath_dirs_to_delete(
            media_id
        )
        thumbnail_dir = self.preview_url.filepaths.url_cache_thumbnail_directory(
            media_id
        )
        thumbnail_dirs = self.preview_url.filepaths.url_cache_thumbnail_dirs_to_delete(
            media_id
        )

        self.assertTrue(os.path.isfile(file_path))
        self.assertTrue(os.path.isdir(thumbnail_dir))

        self.preview_url.clock.advance_time_msec(IMAGE_CACHE_EXPIRY_MS + 1)
        self.get_success(self.preview_url._expire_url_cache_data())

        for path in [file_path] + file_dirs + [thumbnail_dir] + thumbnail_dirs:
            self.assertFalse(
                os.path.exists(path),
                f"{os.path.relpath(path, self.media_store_path)} was not deleted",
            )

    @unittest.override_config({"url_preview_url_blacklist": [{"port": "*"}]})
    def test_blacklist_port(self) -> None:
        """Tests that blacklisting URLs with a port makes previewing such URLs
        fail with a 403 error and doesn't impact other previews.
        """
        self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")]

        bad_url = quote("http://matrix.org:8888/foo")
        good_url = quote("http://matrix.org/foo")

        channel = self.make_request(
            "GET",
            "preview_url?url=" + bad_url,
            shorthand=False,
            await_result=False,
        )
        self.pump()
        self.assertEqual(channel.code, 403, channel.result)

        channel = self.make_request(
            "GET",
            "preview_url?url=" + good_url,
            shorthand=False,
            await_result=False,
        )
        self.pump()

        client = self.reactor.tcpClients[0][2].buildProtocol(None)
        server = AccumulatingProtocol()
        server.makeConnection(FakeTransport(client, self.reactor))
        client.makeConnection(FakeTransport(server, self.reactor))
        client.dataReceived(
            b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\nContent-Type: text/html\r\n\r\n"
            % (len(self.end_content),)
            + self.end_content
        )

        self.pump()
        self.assertEqual(channel.code, 200)