# 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_relations: bool = True, **kwargs: Any, ) -> JsonDict: """Serializes a single event. Args: event: The event being serialized. time_now: The current time in milliseconds bundle_relations: Whether to include the bundled relations for this event. **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) # If MSC1849 is enabled then we need to look if there are any relations # we need to bundle in with the event. # Do not bundle relations if the event has been redacted if not event.internal_metadata.is_redacted() and ( self._msc1849_enabled and bundle_relations ): await self._injected_bundled_relations(event, time_now, serialized_event) return serialized_event async def _injected_bundled_relations( self, event: EventBase, time_now: int, serialized_event: JsonDict ) -> None: """Potentially injects bundled relations 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. """ event_id = event.event_id # The bundled relations to include. relations = {} annotations = await self.store.get_aggregation_groups_for_event(event_id) if annotations.chunk: relations[RelationTypes.ANNOTATION] = annotations.to_dict() references = await self.store.get_relations_for_event( event_id, RelationTypes.REFERENCE, direction="f" ) if references.chunk: relations[RelationTypes.REFERENCE] = references.to_dict() edit = None if event.type == EventTypes.Message: edit = await self.store.get_applicable_edit(event_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) relations[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) if latest_thread_event: relations[RelationTypes.THREAD] = { # Don't bundle relations as this could recurse forever. "latest_event": await self.serialize_event( latest_thread_event, time_now, bundle_relations=False ), "count": thread_count, } # If any bundled relations were found, include them. if relations: serialized_event["unsigned"].setdefault("m.relations", {}).update(relations) 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)