summary refs log tree commit diff
path: root/synapse/events/utils.py
blob: 3da432c1df58b7d3e928cc3ac360183c7eb402bd (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
# Copyright 2014-2016 OpenMarket 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 collections.abc
import re
from typing import (
    TYPE_CHECKING,
    Any,
    Callable,
    Dict,
    Iterable,
    List,
    Mapping,
    Optional,
    Union,
)

from frozendict import frozendict

from synapse.api.constants import EventContentFields, EventTypes, RelationTypes
from synapse.api.errors import Codes, SynapseError
from synapse.api.room_versions import RoomVersion
from synapse.types import JsonDict
from synapse.util.async_helpers import yieldable_gather_results
from synapse.util.frozenutils import unfreeze

from . import EventBase

if TYPE_CHECKING:
    from synapse.server import HomeServer

# Split strings on "." but not "\." This uses a negative lookbehind assertion for '\'
# (?<!stuff) matches if the current position in the string is not preceded
# by a match for 'stuff'.
# TODO: This is fast, but fails to handle "foo\\.bar" which should be treated as
#       the literal fields "foo\" and "bar" but will instead be treated as "foo\\.bar"
SPLIT_FIELD_REGEX = re.compile(r"(?<!\\)\.")

CANONICALJSON_MAX_INT = (2 ** 53) - 1
CANONICALJSON_MIN_INT = -CANONICALJSON_MAX_INT


def prune_event(event: EventBase) -> EventBase:
    """Returns a pruned version of the given event, which removes all keys we
    don't know about or think could potentially be dodgy.

    This is used when we "redact" an event. We want to remove all fields that
    the user has specified, but we do want to keep necessary information like
    type, state_key etc.
    """
    pruned_event_dict = prune_event_dict(event.room_version, event.get_dict())

    from . import make_event_from_dict

    pruned_event = make_event_from_dict(
        pruned_event_dict, event.room_version, event.internal_metadata.get_dict()
    )

    # copy the internal fields
    pruned_event.internal_metadata.stream_ordering = (
        event.internal_metadata.stream_ordering
    )

    pruned_event.internal_metadata.outlier = event.internal_metadata.outlier

    # Mark the event as redacted
    pruned_event.internal_metadata.redacted = True

    return pruned_event


def prune_event_dict(room_version: RoomVersion, event_dict: JsonDict) -> JsonDict:
    """Redacts the event_dict in the same way as `prune_event`, except it
    operates on dicts rather than event objects

    Returns:
        A copy of the pruned event dict
    """

    allowed_keys = [
        "event_id",
        "sender",
        "room_id",
        "hashes",
        "signatures",
        "content",
        "type",
        "state_key",
        "depth",
        "prev_events",
        "auth_events",
        "origin",
        "origin_server_ts",
    ]

    # Room versions from before MSC2176 had additional allowed keys.
    if not room_version.msc2176_redaction_rules:
        allowed_keys.extend(["prev_state", "membership"])

    event_type = event_dict["type"]

    new_content = {}

    def add_fields(*fields: str) -> None:
        for field in fields:
            if field in event_dict["content"]:
                new_content[field] = event_dict["content"][field]

    if event_type == EventTypes.Member:
        add_fields("membership")
        if room_version.msc3375_redaction_rules:
            add_fields(EventContentFields.AUTHORISING_USER)
    elif event_type == EventTypes.Create:
        # MSC2176 rules state that create events cannot be redacted.
        if room_version.msc2176_redaction_rules:
            return event_dict

        add_fields("creator")
    elif event_type == EventTypes.JoinRules:
        add_fields("join_rule")
        if room_version.msc3083_join_rules:
            add_fields("allow")
    elif event_type == EventTypes.PowerLevels:
        add_fields(
            "users",
            "users_default",
            "events",
            "events_default",
            "state_default",
            "ban",
            "kick",
            "redact",
        )

        if room_version.msc2176_redaction_rules:
            add_fields("invite")

        if room_version.msc2716_historical:
            add_fields("historical")

    elif event_type == EventTypes.Aliases and room_version.special_case_aliases_auth:
        add_fields("aliases")
    elif event_type == EventTypes.RoomHistoryVisibility:
        add_fields("history_visibility")
    elif event_type == EventTypes.Redaction and room_version.msc2176_redaction_rules:
        add_fields("redacts")
    elif room_version.msc2716_redactions and event_type == EventTypes.MSC2716_INSERTION:
        add_fields(EventContentFields.MSC2716_NEXT_BATCH_ID)
    elif room_version.msc2716_redactions and event_type == EventTypes.MSC2716_BATCH:
        add_fields(EventContentFields.MSC2716_BATCH_ID)
    elif room_version.msc2716_redactions and event_type == EventTypes.MSC2716_MARKER:
        add_fields(EventContentFields.MSC2716_MARKER_INSERTION)

    allowed_fields = {k: v for k, v in event_dict.items() if k in allowed_keys}

    allowed_fields["content"] = new_content

    unsigned: JsonDict = {}
    allowed_fields["unsigned"] = unsigned

    event_unsigned = event_dict.get("unsigned", {})

    if "age_ts" in event_unsigned:
        unsigned["age_ts"] = event_unsigned["age_ts"]
    if "replaces_state" in event_unsigned:
        unsigned["replaces_state"] = event_unsigned["replaces_state"]

    return allowed_fields


def _copy_field(src: JsonDict, dst: JsonDict, field: List[str]) -> None:
    """Copy the field in 'src' to 'dst'.

    For example, if src={"foo":{"bar":5}} and dst={}, and field=["foo","bar"]
    then dst={"foo":{"bar":5}}.

    Args:
        src: The dict to read from.
        dst: The dict to modify.
        field: List of keys to drill down to in 'src'.
    """
    if len(field) == 0:  # this should be impossible
        return
    if len(field) == 1:  # common case e.g. 'origin_server_ts'
        if field[0] in src:
            dst[field[0]] = src[field[0]]
        return

    # Else is a nested field e.g. 'content.body'
    # Pop the last field as that's the key to move across and we need the
    # parent dict in order to access the data. Drill down to the right dict.
    key_to_move = field.pop(-1)
    sub_dict = src
    for sub_field in field:  # e.g. sub_field => "content"
        if sub_field in sub_dict and type(sub_dict[sub_field]) in [dict, frozendict]:
            sub_dict = sub_dict[sub_field]
        else:
            return

    if key_to_move not in sub_dict:
        return

    # Insert the key into the output dictionary, creating nested objects
    # as required. We couldn't do this any earlier or else we'd need to delete
    # the empty objects if the key didn't exist.
    sub_out_dict = dst
    for sub_field in field:
        sub_out_dict = sub_out_dict.setdefault(sub_field, {})
    sub_out_dict[key_to_move] = sub_dict[key_to_move]


def only_fields(dictionary: JsonDict, fields: List[str]) -> JsonDict:
    """Return a new dict with only the fields in 'dictionary' which are present
    in 'fields'.

    If there are no event fields specified then all fields are included.
    The entries may include '.' characters to indicate sub-fields.
    So ['content.body'] will include the 'body' field of the 'content' object.
    A literal '.' character in a field name may be escaped using a '\'.

    Args:
        dictionary: The dictionary to read from.
        fields: A list of fields to copy over. Only shallow refs are
        taken.
    Returns:
        A new dictionary with only the given fields. If fields was empty,
        the same dictionary is returned.
    """
    if len(fields) == 0:
        return dictionary

    # for each field, convert it:
    # ["content.body.thing\.with\.dots"] => [["content", "body", "thing\.with\.dots"]]
    split_fields = [SPLIT_FIELD_REGEX.split(f) for f in fields]

    # for each element of the output array of arrays:
    # remove escaping so we can use the right key names.
    split_fields[:] = [
        [f.replace(r"\.", r".") for f in field_array] for field_array in split_fields
    ]

    output: JsonDict = {}
    for field_array in split_fields:
        _copy_field(dictionary, output, field_array)
    return output


def format_event_raw(d: JsonDict) -> JsonDict:
    return d


def format_event_for_client_v1(d: JsonDict) -> JsonDict:
    d = format_event_for_client_v2(d)

    sender = d.get("sender")
    if sender is not None:
        d["user_id"] = sender

    copy_keys = (
        "age",
        "redacted_because",
        "replaces_state",
        "prev_content",
        "invite_room_state",
        "knock_room_state",
    )
    for key in copy_keys:
        if key in d["unsigned"]:
            d[key] = d["unsigned"][key]

    return d


def format_event_for_client_v2(d: JsonDict) -> JsonDict:
    drop_keys = (
        "auth_events",
        "prev_events",
        "hashes",
        "signatures",
        "depth",
        "origin",
        "prev_state",
    )
    for key in drop_keys:
        d.pop(key, None)
    return d


def format_event_for_client_v2_without_room_id(d: JsonDict) -> JsonDict:
    d = format_event_for_client_v2(d)
    d.pop("room_id", None)
    return d


def serialize_event(
    e: Union[JsonDict, EventBase],
    time_now_ms: int,
    *,
    as_client_event: bool = True,
    event_format: Callable[[JsonDict], JsonDict] = format_event_for_client_v1,
    token_id: Optional[str] = None,
    only_event_fields: Optional[List[str]] = None,
    include_stripped_room_state: bool = False,
) -> JsonDict:
    """Serialize event for clients

    Args:
        e
        time_now_ms
        as_client_event
        event_format
        token_id
        only_event_fields
        include_stripped_room_state: Some events can have stripped room state
            stored in the `unsigned` field. This is required for invite and knock
            functionality. If this option is False, that state will be removed from the
            event before it is returned. Otherwise, it will be kept.

    Returns:
        The serialized event dictionary.
    """

    # FIXME(erikj): To handle the case of presence events and the like
    if not isinstance(e, EventBase):
        return e

    time_now_ms = int(time_now_ms)

    # Should this strip out None's?
    d = {k: v for k, v in e.get_dict().items()}

    d["event_id"] = e.event_id

    if "age_ts" in d["unsigned"]:
        d["unsigned"]["age"] = time_now_ms - d["unsigned"]["age_ts"]
        del d["unsigned"]["age_ts"]

    if "redacted_because" in e.unsigned:
        d["unsigned"]["redacted_because"] = serialize_event(
            e.unsigned["redacted_because"], time_now_ms, event_format=event_format
        )

    if token_id is not None:
        if token_id == getattr(e.internal_metadata, "token_id", None):
            txn_id = getattr(e.internal_metadata, "txn_id", None)
            if txn_id is not None:
                d["unsigned"]["transaction_id"] = txn_id

    # invite_room_state and knock_room_state are a list of stripped room state events
    # that are meant to provide metadata about a room to an invitee/knocker. They are
    # intended to only be included in specific circumstances, such as down sync, and
    # should not be included in any other case.
    if not include_stripped_room_state:
        d["unsigned"].pop("invite_room_state", None)
        d["unsigned"].pop("knock_room_state", None)

    if as_client_event:
        d = event_format(d)

    if only_event_fields:
        if not isinstance(only_event_fields, list) or not all(
            isinstance(f, str) for f in only_event_fields
        ):
            raise TypeError("only_event_fields must be a list of strings")
        d = only_fields(d, only_event_fields)

    return d


class EventClientSerializer:
    """Serializes events that are to be sent to clients.

    This is used for bundling extra information with any events to be sent to
    clients.
    """

    def __init__(self, hs: "HomeServer"):
        self.store = hs.get_datastore()
        self._msc1849_enabled = hs.config.experimental.msc1849_enabled
        self._msc3440_enabled = hs.config.experimental.msc3440_enabled

    async def serialize_event(
        self,
        event: Union[JsonDict, EventBase],
        time_now: int,
        *,
        bundle_aggregations: bool = True,
        **kwargs: Any,
    ) -> JsonDict:
        """Serializes a single event.

        Args:
            event: The event being serialized.
            time_now: The current time in milliseconds
            bundle_aggregations: Whether to include the bundled aggregations for this
                event. Only applies to non-state events. (State events never include
                bundled aggregations.)
            **kwargs: Arguments to pass to `serialize_event`

        Returns:
            The serialized event
        """
        # To handle the case of presence events and the like
        if not isinstance(event, EventBase):
            return event

        serialized_event = serialize_event(event, time_now, **kwargs)

        # Check if there are any bundled aggregations to include with the event.
        #
        # Do not bundle aggregations if any of the following at true:
        #
        # * Support is disabled via the configuration or the caller.
        # * The event is a state event.
        # * The event has been redacted.
        if (
            self._msc1849_enabled
            and bundle_aggregations
            and not event.is_state()
            and not event.internal_metadata.is_redacted()
        ):
            await self._injected_bundled_aggregations(event, time_now, serialized_event)

        return serialized_event

    async def _injected_bundled_aggregations(
        self, event: EventBase, time_now: int, serialized_event: JsonDict
    ) -> None:
        """Potentially injects bundled aggregations into the unsigned portion of the serialized event.

        Args:
            event: The event being serialized.
            time_now: The current time in milliseconds
            serialized_event: The serialized event which may be modified.

        """
        # Do not bundle aggregations for an event which represents an edit or an
        # annotation. It does not make sense for them to have related events.
        relates_to = event.content.get("m.relates_to")
        if isinstance(relates_to, (dict, frozendict)):
            relation_type = relates_to.get("rel_type")
            if relation_type in (RelationTypes.ANNOTATION, RelationTypes.REPLACE):
                return

        event_id = event.event_id
        room_id = event.room_id

        # The bundled aggregations to include.
        aggregations = {}

        annotations = await self.store.get_aggregation_groups_for_event(
            event_id, room_id
        )
        if annotations.chunk:
            aggregations[RelationTypes.ANNOTATION] = annotations.to_dict()

        references = await self.store.get_relations_for_event(
            event_id, room_id, RelationTypes.REFERENCE, direction="f"
        )
        if references.chunk:
            aggregations[RelationTypes.REFERENCE] = references.to_dict()

        edit = None
        if event.type == EventTypes.Message:
            edit = await self.store.get_applicable_edit(event_id, room_id)

        if edit:
            # If there is an edit replace the content, preserving existing
            # relations.

            # Ensure we take copies of the edit content, otherwise we risk modifying
            # the original event.
            edit_content = edit.content.copy()

            # Unfreeze the event content if necessary, so that we may modify it below
            edit_content = unfreeze(edit_content)
            serialized_event["content"] = edit_content.get("m.new_content", {})

            # Check for existing relations
            relates_to = event.content.get("m.relates_to")
            if relates_to:
                # Keep the relations, ensuring we use a dict copy of the original
                serialized_event["content"]["m.relates_to"] = relates_to.copy()
            else:
                serialized_event["content"].pop("m.relates_to", None)

            aggregations[RelationTypes.REPLACE] = {
                "event_id": edit.event_id,
                "origin_server_ts": edit.origin_server_ts,
                "sender": edit.sender,
            }

        # If this event is the start of a thread, include a summary of the replies.
        if self._msc3440_enabled:
            (
                thread_count,
                latest_thread_event,
            ) = await self.store.get_thread_summary(event_id, room_id)
            if latest_thread_event:
                aggregations[RelationTypes.THREAD] = {
                    # Don't bundle aggregations as this could recurse forever.
                    "latest_event": await self.serialize_event(
                        latest_thread_event, time_now, bundle_aggregations=False
                    ),
                    "count": thread_count,
                }

        # If any bundled aggregations were found, include them.
        if aggregations:
            serialized_event["unsigned"].setdefault("m.relations", {}).update(
                aggregations
            )

    async def serialize_events(
        self, events: Iterable[Union[JsonDict, EventBase]], time_now: int, **kwargs: Any
    ) -> List[JsonDict]:
        """Serializes multiple events.

        Args:
            event
            time_now: The current time in milliseconds
            **kwargs: Arguments to pass to `serialize_event`

        Returns:
            The list of serialized events
        """
        return await yieldable_gather_results(
            self.serialize_event, events, time_now=time_now, **kwargs
        )


def copy_power_levels_contents(
    old_power_levels: Mapping[str, Union[int, Mapping[str, int]]]
) -> Dict[str, Union[int, Dict[str, int]]]:
    """Copy the content of a power_levels event, unfreezing frozendicts along the way

    Raises:
        TypeError if the input does not look like a valid power levels event content
    """
    if not isinstance(old_power_levels, collections.abc.Mapping):
        raise TypeError("Not a valid power-levels content: %r" % (old_power_levels,))

    power_levels: Dict[str, Union[int, Dict[str, int]]] = {}
    for k, v in old_power_levels.items():

        if isinstance(v, int):
            power_levels[k] = v
            continue

        if isinstance(v, collections.abc.Mapping):
            h: Dict[str, int] = {}
            power_levels[k] = h
            for k1, v1 in v.items():
                # we should only have one level of nesting
                if not isinstance(v1, int):
                    raise TypeError(
                        "Invalid power_levels value for %s.%s: %r" % (k, k1, v1)
                    )
                h[k1] = v1
            continue

        raise TypeError("Invalid power_levels value for %s: %r" % (k, v))

    return power_levels


def validate_canonicaljson(value: Any) -> None:
    """
    Ensure that the JSON object is valid according to the rules of canonical JSON.

    See the appendix section 3.1: Canonical JSON.

    This rejects JSON that has:
    * An integer outside the range of [-2 ^ 53 + 1, 2 ^ 53 - 1]
    * Floats
    * NaN, Infinity, -Infinity
    """
    if isinstance(value, int):
        if value < CANONICALJSON_MIN_INT or CANONICALJSON_MAX_INT < value:
            raise SynapseError(400, "JSON integer out of range", Codes.BAD_JSON)

    elif isinstance(value, float):
        # Note that Infinity, -Infinity, and NaN are also considered floats.
        raise SynapseError(400, "Bad JSON value: float", Codes.BAD_JSON)

    elif isinstance(value, (dict, frozendict)):
        for v in value.values():
            validate_canonicaljson(v)

    elif isinstance(value, (list, tuple)):
        for i in value:
            validate_canonicaljson(i)

    elif not isinstance(value, (bool, str)) and value is not None:
        # Other potential JSON values (bool, None, str) are safe.
        raise SynapseError(400, "Unknown JSON value", Codes.BAD_JSON)