272 lines
10 KiB
Python
272 lines
10 KiB
Python
# 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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from typing import Iterable, Type, Union, cast
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import jsonschema
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from synapse.api.constants import MAX_ALIAS_LENGTH, EventTypes, Membership
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from synapse.api.errors import Codes, SynapseError
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from synapse.api.room_versions import EventFormatVersions
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from synapse.config.homeserver import HomeServerConfig
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from synapse.events import EventBase
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from synapse.events.builder import EventBuilder
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from synapse.events.utils import (
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CANONICALJSON_MAX_INT,
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CANONICALJSON_MIN_INT,
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validate_canonicaljson,
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)
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from synapse.federation.federation_server import server_matches_acl_event
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from synapse.types import EventID, JsonDict, RoomID, UserID
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class EventValidator:
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def validate_new(self, event: EventBase, config: HomeServerConfig) -> None:
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"""Validates the event has roughly the right format
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Suitable for checking a locally-created event. It has stricter checks than
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is appropriate for an event received over federation (for which, see
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event_auth.validate_event_for_room_version)
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Args:
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event: The event to validate.
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config: The homeserver's configuration.
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"""
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self.validate_builder(event)
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if event.format_version == EventFormatVersions.ROOM_V1_V2:
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EventID.from_string(event.event_id)
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required = [
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"auth_events",
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"content",
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"hashes",
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"origin",
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"prev_events",
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"sender",
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"type",
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]
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for k in required:
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if k not in event:
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raise SynapseError(400, "Event does not have key %s" % (k,))
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# Check that the following keys have string values
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event_strings = ["origin"]
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for s in event_strings:
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if not isinstance(getattr(event, s), str):
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raise SynapseError(400, "'%s' not a string type" % (s,))
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# Depending on the room version, ensure the data is spec compliant JSON.
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if event.room_version.strict_canonicaljson:
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# Note that only the client controlled portion of the event is
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# checked, since we trust the portions of the event we created.
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validate_canonicaljson(event.content)
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if event.type == EventTypes.Aliases:
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if "aliases" in event.content:
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for alias in event.content["aliases"]:
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if len(alias) > MAX_ALIAS_LENGTH:
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raise SynapseError(
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400,
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(
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"Can't create aliases longer than"
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" %d characters" % (MAX_ALIAS_LENGTH,)
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),
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Codes.INVALID_PARAM,
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)
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if event.type == EventTypes.Retention:
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self._validate_retention(event)
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if event.type == EventTypes.ServerACL:
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if not server_matches_acl_event(config.server.server_name, event):
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raise SynapseError(
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400, "Can't create an ACL event that denies the local server"
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)
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if event.type == EventTypes.PowerLevels:
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try:
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jsonschema.validate(
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instance=event.content,
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schema=POWER_LEVELS_SCHEMA,
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cls=plValidator,
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)
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except jsonschema.ValidationError as e:
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if e.path:
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# example: "users_default": '0' is not of type 'integer'
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# cast safety: path entries can be integers, if we fail to validate
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# items in an array. However the POWER_LEVELS_SCHEMA doesn't expect
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# to see any arrays.
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message = (
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'"' + cast(str, e.path[-1]) + '": ' + e.message # noqa: B306
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)
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# jsonschema.ValidationError.message is a valid attribute
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else:
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# example: '0' is not of type 'integer'
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message = e.message # noqa: B306
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# jsonschema.ValidationError.message is a valid attribute
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raise SynapseError(
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code=400,
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msg=message,
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errcode=Codes.BAD_JSON,
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)
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def _validate_retention(self, event: EventBase) -> None:
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"""Checks that an event that defines the retention policy for a room respects the
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format enforced by the spec.
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Args:
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event: The event to validate.
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"""
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if not event.is_state():
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raise SynapseError(code=400, msg="must be a state event")
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min_lifetime = event.content.get("min_lifetime")
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max_lifetime = event.content.get("max_lifetime")
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if min_lifetime is not None:
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if type(min_lifetime) is not int:
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raise SynapseError(
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code=400,
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msg="'min_lifetime' must be an integer",
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errcode=Codes.BAD_JSON,
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)
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if max_lifetime is not None:
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if type(max_lifetime) is not int:
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raise SynapseError(
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code=400,
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msg="'max_lifetime' must be an integer",
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errcode=Codes.BAD_JSON,
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)
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if (
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min_lifetime is not None
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and max_lifetime is not None
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and min_lifetime > max_lifetime
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):
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raise SynapseError(
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code=400,
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msg="'min_lifetime' can't be greater than 'max_lifetime",
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errcode=Codes.BAD_JSON,
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)
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def validate_builder(self, event: Union[EventBase, EventBuilder]) -> None:
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"""Validates that the builder/event has roughly the right format. Only
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checks values that we expect a proto event to have, rather than all the
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fields an event would have
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"""
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strings = ["room_id", "sender", "type"]
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if hasattr(event, "state_key"):
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strings.append("state_key")
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for s in strings:
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if not isinstance(getattr(event, s), str):
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raise SynapseError(400, "Not '%s' a string type" % (s,))
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RoomID.from_string(event.room_id)
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UserID.from_string(event.sender)
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if event.type == EventTypes.Message:
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strings = ["body", "msgtype"]
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self._ensure_strings(event.content, strings)
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elif event.type == EventTypes.Topic:
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self._ensure_strings(event.content, ["topic"])
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self._ensure_state_event(event)
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elif event.type == EventTypes.Name:
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self._ensure_strings(event.content, ["name"])
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self._ensure_state_event(event)
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elif event.type == EventTypes.Member:
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if "membership" not in event.content:
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raise SynapseError(400, "Content has not membership key")
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if event.content["membership"] not in Membership.LIST:
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raise SynapseError(400, "Invalid membership key")
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self._ensure_state_event(event)
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elif event.type == EventTypes.Tombstone:
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if "replacement_room" not in event.content:
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raise SynapseError(400, "Content has no replacement_room key")
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if event.content["replacement_room"] == event.room_id:
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raise SynapseError(
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400, "Tombstone cannot reference the room it was sent in"
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)
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self._ensure_state_event(event)
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def _ensure_strings(self, d: JsonDict, keys: Iterable[str]) -> None:
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for s in keys:
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if s not in d:
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raise SynapseError(400, "'%s' not in content" % (s,))
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if not isinstance(d[s], str):
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raise SynapseError(400, "'%s' not a string type" % (s,))
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def _ensure_state_event(self, event: Union[EventBase, EventBuilder]) -> None:
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if not event.is_state():
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raise SynapseError(400, "'%s' must be state events" % (event.type,))
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POWER_LEVELS_SCHEMA = {
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"type": "object",
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"properties": {
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"ban": {"$ref": "#/definitions/int"},
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"events": {"$ref": "#/definitions/objectOfInts"},
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"events_default": {"$ref": "#/definitions/int"},
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"invite": {"$ref": "#/definitions/int"},
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"kick": {"$ref": "#/definitions/int"},
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"notifications": {"$ref": "#/definitions/objectOfInts"},
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"redact": {"$ref": "#/definitions/int"},
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"state_default": {"$ref": "#/definitions/int"},
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"users": {"$ref": "#/definitions/objectOfInts"},
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"users_default": {"$ref": "#/definitions/int"},
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},
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"definitions": {
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"int": {
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"type": "integer",
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"minimum": CANONICALJSON_MIN_INT,
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"maximum": CANONICALJSON_MAX_INT,
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},
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"objectOfInts": {
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"type": "object",
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"additionalProperties": {"$ref": "#/definitions/int"},
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},
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},
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}
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# This could return something newer than Draft 7, but that's the current "latest"
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# validator.
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def _create_power_level_validator() -> Type[jsonschema.Draft7Validator]:
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validator = jsonschema.validators.validator_for(POWER_LEVELS_SCHEMA)
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# by default jsonschema does not consider a frozendict to be an object so
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# we need to use a custom type checker
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# https://python-jsonschema.readthedocs.io/en/stable/validate/?highlight=object#validating-with-additional-types
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type_checker = validator.TYPE_CHECKER.redefine(
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"object", lambda checker, thing: isinstance(thing, collections.abc.Mapping)
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)
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return jsonschema.validators.extend(validator, type_checker=type_checker)
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plValidator = _create_power_level_validator()
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