mirror of
https://git.anonymousland.org/anonymousland/synapse.git
synced 2024-12-27 08:09:44 -05:00
7b06f85c0e
This bug was discovered by DINUM. We were modifying `serialized_event["content"]`, which - if you've got `USE_FROZEN_DICTS` turned on or are [using a third party rules module](17cd48fe51/synapse/events/third_party_rules.py (L73-L76)) - will raise a 500 if you try to a edit a reply to a message.
`serialized_event["content"]` could be set to the edit event's content, instead of a copy of it, which is bad as we attempt to modify it. Instead, we also end up modifying the original event's content. DINUM uses a third party rules module, which meant the event's content got frozen and thus an exception was raised.
To be clear, the problem is not that the event's content was frozen. In fact doing so helped us uncover the fact we weren't copying event content correctly.
511 lines
16 KiB
Python
511 lines
16 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2014-2016 OpenMarket Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import collections.abc
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import re
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from typing import Any, Mapping, Union
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from frozendict import frozendict
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from synapse.api.constants import EventTypes, RelationTypes
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from synapse.api.errors import Codes, SynapseError
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from synapse.api.room_versions import RoomVersion
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from synapse.util.async_helpers import yieldable_gather_results
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from synapse.util.frozenutils import unfreeze
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from . import EventBase
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# Split strings on "." but not "\." This uses a negative lookbehind assertion for '\'
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# (?<!stuff) matches if the current position in the string is not preceded
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# by a match for 'stuff'.
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# TODO: This is fast, but fails to handle "foo\\.bar" which should be treated as
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# the literal fields "foo\" and "bar" but will instead be treated as "foo\\.bar"
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SPLIT_FIELD_REGEX = re.compile(r"(?<!\\)\.")
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def prune_event(event: EventBase) -> EventBase:
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"""Returns a pruned version of the given event, which removes all keys we
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don't know about or think could potentially be dodgy.
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This is used when we "redact" an event. We want to remove all fields that
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the user has specified, but we do want to keep necessary information like
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type, state_key etc.
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"""
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pruned_event_dict = prune_event_dict(event.room_version, event.get_dict())
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from . import make_event_from_dict
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pruned_event = make_event_from_dict(
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pruned_event_dict, event.room_version, event.internal_metadata.get_dict()
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)
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# copy the internal fields
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pruned_event.internal_metadata.stream_ordering = (
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event.internal_metadata.stream_ordering
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)
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pruned_event.internal_metadata.outlier = event.internal_metadata.outlier
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# Mark the event as redacted
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pruned_event.internal_metadata.redacted = True
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return pruned_event
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def prune_event_dict(room_version: RoomVersion, event_dict: dict) -> dict:
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"""Redacts the event_dict in the same way as `prune_event`, except it
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operates on dicts rather than event objects
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Returns:
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A copy of the pruned event dict
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"""
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allowed_keys = [
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"event_id",
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"sender",
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"room_id",
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"hashes",
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"signatures",
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"content",
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"type",
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"state_key",
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"depth",
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"prev_events",
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"auth_events",
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"origin",
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"origin_server_ts",
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]
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# Room versions from before MSC2176 had additional allowed keys.
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if not room_version.msc2176_redaction_rules:
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allowed_keys.extend(["prev_state", "membership"])
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event_type = event_dict["type"]
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new_content = {}
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def add_fields(*fields):
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for field in fields:
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if field in event_dict["content"]:
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new_content[field] = event_dict["content"][field]
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if event_type == EventTypes.Member:
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add_fields("membership")
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elif event_type == EventTypes.Create:
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# MSC2176 rules state that create events cannot be redacted.
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if room_version.msc2176_redaction_rules:
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return event_dict
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add_fields("creator")
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elif event_type == EventTypes.JoinRules:
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add_fields("join_rule")
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elif event_type == EventTypes.PowerLevels:
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add_fields(
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"users",
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"users_default",
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"events",
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"events_default",
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"state_default",
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"ban",
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"kick",
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"redact",
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)
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if room_version.msc2176_redaction_rules:
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add_fields("invite")
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elif event_type == EventTypes.Aliases and room_version.special_case_aliases_auth:
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add_fields("aliases")
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elif event_type == EventTypes.RoomHistoryVisibility:
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add_fields("history_visibility")
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elif event_type == EventTypes.Redaction and room_version.msc2176_redaction_rules:
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add_fields("redacts")
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allowed_fields = {k: v for k, v in event_dict.items() if k in allowed_keys}
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allowed_fields["content"] = new_content
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unsigned = {}
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allowed_fields["unsigned"] = unsigned
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event_unsigned = event_dict.get("unsigned", {})
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if "age_ts" in event_unsigned:
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unsigned["age_ts"] = event_unsigned["age_ts"]
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if "replaces_state" in event_unsigned:
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unsigned["replaces_state"] = event_unsigned["replaces_state"]
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return allowed_fields
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def _copy_field(src, dst, field):
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"""Copy the field in 'src' to 'dst'.
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For example, if src={"foo":{"bar":5}} and dst={}, and field=["foo","bar"]
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then dst={"foo":{"bar":5}}.
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Args:
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src(dict): The dict to read from.
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dst(dict): The dict to modify.
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field(list<str>): List of keys to drill down to in 'src'.
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"""
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if len(field) == 0: # this should be impossible
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return
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if len(field) == 1: # common case e.g. 'origin_server_ts'
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if field[0] in src:
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dst[field[0]] = src[field[0]]
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return
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# Else is a nested field e.g. 'content.body'
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# Pop the last field as that's the key to move across and we need the
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# parent dict in order to access the data. Drill down to the right dict.
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key_to_move = field.pop(-1)
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sub_dict = src
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for sub_field in field: # e.g. sub_field => "content"
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if sub_field in sub_dict and type(sub_dict[sub_field]) in [dict, frozendict]:
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sub_dict = sub_dict[sub_field]
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else:
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return
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if key_to_move not in sub_dict:
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return
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# Insert the key into the output dictionary, creating nested objects
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# as required. We couldn't do this any earlier or else we'd need to delete
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# the empty objects if the key didn't exist.
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sub_out_dict = dst
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for sub_field in field:
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sub_out_dict = sub_out_dict.setdefault(sub_field, {})
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sub_out_dict[key_to_move] = sub_dict[key_to_move]
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def only_fields(dictionary, fields):
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"""Return a new dict with only the fields in 'dictionary' which are present
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in 'fields'.
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If there are no event fields specified then all fields are included.
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The entries may include '.' characters to indicate sub-fields.
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So ['content.body'] will include the 'body' field of the 'content' object.
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A literal '.' character in a field name may be escaped using a '\'.
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Args:
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dictionary(dict): The dictionary to read from.
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fields(list<str>): A list of fields to copy over. Only shallow refs are
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taken.
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Returns:
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dict: A new dictionary with only the given fields. If fields was empty,
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the same dictionary is returned.
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"""
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if len(fields) == 0:
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return dictionary
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# for each field, convert it:
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# ["content.body.thing\.with\.dots"] => [["content", "body", "thing\.with\.dots"]]
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split_fields = [SPLIT_FIELD_REGEX.split(f) for f in fields]
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# for each element of the output array of arrays:
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# remove escaping so we can use the right key names.
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split_fields[:] = [
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[f.replace(r"\.", r".") for f in field_array] for field_array in split_fields
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]
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output = {}
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for field_array in split_fields:
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_copy_field(dictionary, output, field_array)
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return output
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def format_event_raw(d):
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return d
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def format_event_for_client_v1(d):
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d = format_event_for_client_v2(d)
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sender = d.get("sender")
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if sender is not None:
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d["user_id"] = sender
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copy_keys = (
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"age",
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"redacted_because",
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"replaces_state",
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"prev_content",
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"invite_room_state",
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)
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for key in copy_keys:
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if key in d["unsigned"]:
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d[key] = d["unsigned"][key]
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return d
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def format_event_for_client_v2(d):
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drop_keys = (
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"auth_events",
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"prev_events",
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"hashes",
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"signatures",
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"depth",
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"origin",
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"prev_state",
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)
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for key in drop_keys:
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d.pop(key, None)
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return d
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def format_event_for_client_v2_without_room_id(d):
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d = format_event_for_client_v2(d)
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d.pop("room_id", None)
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return d
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def serialize_event(
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e,
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time_now_ms,
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as_client_event=True,
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event_format=format_event_for_client_v1,
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token_id=None,
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only_event_fields=None,
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is_invite=False,
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):
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"""Serialize event for clients
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Args:
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e (EventBase)
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time_now_ms (int)
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as_client_event (bool)
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event_format
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token_id
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only_event_fields
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is_invite (bool): Whether this is an invite that is being sent to the
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invitee
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Returns:
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dict
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"""
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# FIXME(erikj): To handle the case of presence events and the like
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if not isinstance(e, EventBase):
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return e
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time_now_ms = int(time_now_ms)
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# Should this strip out None's?
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d = {k: v for k, v in e.get_dict().items()}
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d["event_id"] = e.event_id
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if "age_ts" in d["unsigned"]:
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d["unsigned"]["age"] = time_now_ms - d["unsigned"]["age_ts"]
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del d["unsigned"]["age_ts"]
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if "redacted_because" in e.unsigned:
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d["unsigned"]["redacted_because"] = serialize_event(
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e.unsigned["redacted_because"], time_now_ms, event_format=event_format
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)
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if token_id is not None:
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if token_id == getattr(e.internal_metadata, "token_id", None):
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txn_id = getattr(e.internal_metadata, "txn_id", None)
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if txn_id is not None:
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d["unsigned"]["transaction_id"] = txn_id
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# If this is an invite for somebody else, then we don't care about the
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# invite_room_state as that's meant solely for the invitee. Other clients
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# will already have the state since they're in the room.
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if not is_invite:
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d["unsigned"].pop("invite_room_state", None)
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if as_client_event:
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d = event_format(d)
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if only_event_fields:
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if not isinstance(only_event_fields, list) or not all(
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isinstance(f, str) for f in only_event_fields
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):
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raise TypeError("only_event_fields must be a list of strings")
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d = only_fields(d, only_event_fields)
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return d
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class EventClientSerializer:
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"""Serializes events that are to be sent to clients.
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This is used for bundling extra information with any events to be sent to
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clients.
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"""
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def __init__(self, hs):
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self.store = hs.get_datastore()
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self.experimental_msc1849_support_enabled = (
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hs.config.experimental_msc1849_support_enabled
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)
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async def serialize_event(
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self, event, time_now, bundle_aggregations=True, **kwargs
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):
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"""Serializes a single event.
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Args:
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event (EventBase)
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time_now (int): The current time in milliseconds
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bundle_aggregations (bool): Whether to bundle in related events
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**kwargs: Arguments to pass to `serialize_event`
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Returns:
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dict: The serialized event
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"""
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# To handle the case of presence events and the like
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if not isinstance(event, EventBase):
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return event
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event_id = event.event_id
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serialized_event = serialize_event(event, time_now, **kwargs)
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# If MSC1849 is enabled then we need to look if there are any relations
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# we need to bundle in with the event.
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# Do not bundle relations if the event has been redacted
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if not event.internal_metadata.is_redacted() and (
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self.experimental_msc1849_support_enabled and bundle_aggregations
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):
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annotations = await self.store.get_aggregation_groups_for_event(event_id)
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references = await self.store.get_relations_for_event(
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event_id, RelationTypes.REFERENCE, direction="f"
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)
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if annotations.chunk:
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r = serialized_event["unsigned"].setdefault("m.relations", {})
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r[RelationTypes.ANNOTATION] = annotations.to_dict()
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if references.chunk:
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r = serialized_event["unsigned"].setdefault("m.relations", {})
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r[RelationTypes.REFERENCE] = references.to_dict()
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edit = None
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if event.type == EventTypes.Message:
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edit = await self.store.get_applicable_edit(event_id)
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if edit:
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# If there is an edit replace the content, preserving existing
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# relations.
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# Ensure we take copies of the edit content, otherwise we risk modifying
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# the original event.
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edit_content = edit.content.copy()
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# Unfreeze the event content if necessary, so that we may modify it below
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edit_content = unfreeze(edit_content)
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serialized_event["content"] = edit_content.get("m.new_content", {})
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# Check for existing relations
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relations = event.content.get("m.relates_to")
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if relations:
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# Keep the relations, ensuring we use a dict copy of the original
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serialized_event["content"]["m.relates_to"] = relations.copy()
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else:
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serialized_event["content"].pop("m.relates_to", None)
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r = serialized_event["unsigned"].setdefault("m.relations", {})
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r[RelationTypes.REPLACE] = {
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"event_id": edit.event_id,
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"origin_server_ts": edit.origin_server_ts,
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"sender": edit.sender,
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}
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return serialized_event
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def serialize_events(self, events, time_now, **kwargs):
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"""Serializes multiple events.
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Args:
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event (iter[EventBase])
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time_now (int): The current time in milliseconds
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**kwargs: Arguments to pass to `serialize_event`
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Returns:
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Deferred[list[dict]]: The list of serialized events
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"""
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return yieldable_gather_results(
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self.serialize_event, events, time_now=time_now, **kwargs
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)
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def copy_power_levels_contents(
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old_power_levels: Mapping[str, Union[int, Mapping[str, int]]]
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):
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"""Copy the content of a power_levels event, unfreezing frozendicts along the way
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Raises:
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TypeError if the input does not look like a valid power levels event content
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"""
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if not isinstance(old_power_levels, collections.abc.Mapping):
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raise TypeError("Not a valid power-levels content: %r" % (old_power_levels,))
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power_levels = {}
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for k, v in old_power_levels.items():
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if isinstance(v, int):
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power_levels[k] = v
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continue
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if isinstance(v, collections.abc.Mapping):
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power_levels[k] = h = {}
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for k1, v1 in v.items():
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# we should only have one level of nesting
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if not isinstance(v1, int):
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raise TypeError(
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"Invalid power_levels value for %s.%s: %r" % (k, k1, v1)
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)
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h[k1] = v1
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continue
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raise TypeError("Invalid power_levels value for %s: %r" % (k, v))
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return power_levels
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def validate_canonicaljson(value: Any):
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"""
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Ensure that the JSON object is valid according to the rules of canonical JSON.
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See the appendix section 3.1: Canonical JSON.
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This rejects JSON that has:
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* An integer outside the range of [-2 ^ 53 + 1, 2 ^ 53 - 1]
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* Floats
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* NaN, Infinity, -Infinity
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"""
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if isinstance(value, int):
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if value <= -(2 ** 53) or 2 ** 53 <= value:
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raise SynapseError(400, "JSON integer out of range", Codes.BAD_JSON)
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elif isinstance(value, float):
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# Note that Infinity, -Infinity, and NaN are also considered floats.
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raise SynapseError(400, "Bad JSON value: float", Codes.BAD_JSON)
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elif isinstance(value, (dict, frozendict)):
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for v in value.values():
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validate_canonicaljson(v)
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elif isinstance(value, (list, tuple)):
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for i in value:
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validate_canonicaljson(i)
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elif not isinstance(value, (bool, str)) and value is not None:
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# Other potential JSON values (bool, None, str) are safe.
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raise SynapseError(400, "Unknown JSON value", Codes.BAD_JSON)
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