319 lines
11 KiB
Python
319 lines
11 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2018 New Vector 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 hashlib
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import logging
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from typing import Awaitable, Callable, Dict, List, Optional
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from synapse import event_auth
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from synapse.api.constants import EventTypes
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from synapse.api.errors import AuthError
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from synapse.api.room_versions import RoomVersions
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from synapse.events import EventBase
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from synapse.types import StateMap
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logger = logging.getLogger(__name__)
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POWER_KEY = (EventTypes.PowerLevels, "")
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async def resolve_events_with_store(
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room_id: str,
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state_sets: List[StateMap[str]],
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event_map: Optional[Dict[str, EventBase]],
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state_map_factory: Callable[[List[str]], Awaitable],
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):
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"""
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Args:
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room_id: the room we are working in
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state_sets: List of dicts of (type, state_key) -> event_id,
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which are the different state groups to resolve.
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event_map:
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a dict from event_id to event, for any events that we happen to
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have in flight (eg, those currently being persisted). This will be
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used as a starting point fof finding the state we need; any missing
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events will be requested via state_map_factory.
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If None, all events will be fetched via state_map_factory.
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state_map_factory: will be called
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with a list of event_ids that are needed, and should return with
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an Awaitable that resolves to a dict of event_id to event.
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Returns:
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Deferred[dict[(str, str), str]]:
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a map from (type, state_key) to event_id.
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"""
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if len(state_sets) == 1:
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return state_sets[0]
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unconflicted_state, conflicted_state = _seperate(state_sets)
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needed_events = {
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event_id for event_ids in conflicted_state.values() for event_id in event_ids
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}
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needed_event_count = len(needed_events)
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if event_map is not None:
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needed_events -= set(event_map.keys())
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logger.info(
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"Asking for %d/%d conflicted events", len(needed_events), needed_event_count
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)
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# dict[str, FrozenEvent]: a map from state event id to event. Only includes
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# the state events which are in conflict (and those in event_map)
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state_map = await state_map_factory(needed_events)
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if event_map is not None:
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state_map.update(event_map)
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# everything in the state map should be in the right room
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for event in state_map.values():
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if event.room_id != room_id:
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raise Exception(
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"Attempting to state-resolve for room %s with event %s which is in %s"
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% (room_id, event.event_id, event.room_id,)
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)
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# get the ids of the auth events which allow us to authenticate the
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# conflicted state, picking only from the unconflicting state.
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#
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# dict[(str, str), str]: a map from state key to event id
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auth_events = _create_auth_events_from_maps(
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unconflicted_state, conflicted_state, state_map
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)
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new_needed_events = set(auth_events.values())
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new_needed_event_count = len(new_needed_events)
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new_needed_events -= needed_events
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if event_map is not None:
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new_needed_events -= set(event_map.keys())
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logger.info(
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"Asking for %d/%d auth events", len(new_needed_events), new_needed_event_count
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)
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state_map_new = await state_map_factory(new_needed_events)
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for event in state_map_new.values():
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if event.room_id != room_id:
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raise Exception(
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"Attempting to state-resolve for room %s with event %s which is in %s"
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% (room_id, event.event_id, event.room_id,)
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)
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state_map.update(state_map_new)
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return _resolve_with_state(
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unconflicted_state, conflicted_state, auth_events, state_map
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)
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def _seperate(state_sets):
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"""Takes the state_sets and figures out which keys are conflicted and
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which aren't. i.e., which have multiple different event_ids associated
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with them in different state sets.
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Args:
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state_sets(iterable[dict[(str, str), str]]):
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List of dicts of (type, state_key) -> event_id, which are the
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different state groups to resolve.
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Returns:
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(dict[(str, str), str], dict[(str, str), set[str]]):
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A tuple of (unconflicted_state, conflicted_state), where:
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unconflicted_state is a dict mapping (type, state_key)->event_id
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for unconflicted state keys.
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conflicted_state is a dict mapping (type, state_key) to a set of
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event ids for conflicted state keys.
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"""
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state_set_iterator = iter(state_sets)
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unconflicted_state = dict(next(state_set_iterator))
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conflicted_state = {}
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for state_set in state_set_iterator:
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for key, value in state_set.items():
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# Check if there is an unconflicted entry for the state key.
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unconflicted_value = unconflicted_state.get(key)
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if unconflicted_value is None:
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# There isn't an unconflicted entry so check if there is a
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# conflicted entry.
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ls = conflicted_state.get(key)
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if ls is None:
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# There wasn't a conflicted entry so haven't seen this key before.
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# Therefore it isn't conflicted yet.
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unconflicted_state[key] = value
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else:
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# This key is already conflicted, add our value to the conflict set.
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ls.add(value)
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elif unconflicted_value != value:
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# If the unconflicted value is not the same as our value then we
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# have a new conflict. So move the key from the unconflicted_state
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# to the conflicted state.
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conflicted_state[key] = {value, unconflicted_value}
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unconflicted_state.pop(key, None)
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return unconflicted_state, conflicted_state
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def _create_auth_events_from_maps(unconflicted_state, conflicted_state, state_map):
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auth_events = {}
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for event_ids in conflicted_state.values():
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for event_id in event_ids:
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if event_id in state_map:
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keys = event_auth.auth_types_for_event(state_map[event_id])
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for key in keys:
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if key not in auth_events:
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event_id = unconflicted_state.get(key, None)
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if event_id:
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auth_events[key] = event_id
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return auth_events
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def _resolve_with_state(
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unconflicted_state_ids, conflicted_state_ids, auth_event_ids, state_map
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):
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conflicted_state = {}
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for key, event_ids in conflicted_state_ids.items():
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events = [state_map[ev_id] for ev_id in event_ids if ev_id in state_map]
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if len(events) > 1:
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conflicted_state[key] = events
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elif len(events) == 1:
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unconflicted_state_ids[key] = events[0].event_id
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auth_events = {
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key: state_map[ev_id]
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for key, ev_id in auth_event_ids.items()
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if ev_id in state_map
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}
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try:
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resolved_state = _resolve_state_events(conflicted_state, auth_events)
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except Exception:
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logger.exception("Failed to resolve state")
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raise
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new_state = unconflicted_state_ids
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for key, event in resolved_state.items():
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new_state[key] = event.event_id
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return new_state
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def _resolve_state_events(conflicted_state, auth_events):
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""" This is where we actually decide which of the conflicted state to
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use.
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We resolve conflicts in the following order:
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1. power levels
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2. join rules
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3. memberships
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4. other events.
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"""
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resolved_state = {}
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if POWER_KEY in conflicted_state:
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events = conflicted_state[POWER_KEY]
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logger.debug("Resolving conflicted power levels %r", events)
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resolved_state[POWER_KEY] = _resolve_auth_events(events, auth_events)
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auth_events.update(resolved_state)
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for key, events in conflicted_state.items():
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if key[0] == EventTypes.JoinRules:
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logger.debug("Resolving conflicted join rules %r", events)
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resolved_state[key] = _resolve_auth_events(events, auth_events)
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auth_events.update(resolved_state)
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for key, events in conflicted_state.items():
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if key[0] == EventTypes.Member:
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logger.debug("Resolving conflicted member lists %r", events)
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resolved_state[key] = _resolve_auth_events(events, auth_events)
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auth_events.update(resolved_state)
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for key, events in conflicted_state.items():
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if key not in resolved_state:
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logger.debug("Resolving conflicted state %r:%r", key, events)
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resolved_state[key] = _resolve_normal_events(events, auth_events)
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return resolved_state
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def _resolve_auth_events(events, auth_events):
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reverse = list(reversed(_ordered_events(events)))
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auth_keys = {
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key for event in events for key in event_auth.auth_types_for_event(event)
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}
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new_auth_events = {}
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for key in auth_keys:
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auth_event = auth_events.get(key, None)
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if auth_event:
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new_auth_events[key] = auth_event
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auth_events = new_auth_events
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prev_event = reverse[0]
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for event in reverse[1:]:
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auth_events[(prev_event.type, prev_event.state_key)] = prev_event
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try:
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# The signatures have already been checked at this point
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event_auth.check(
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RoomVersions.V1,
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event,
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auth_events,
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do_sig_check=False,
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do_size_check=False,
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)
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prev_event = event
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except AuthError:
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return prev_event
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return event
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def _resolve_normal_events(events, auth_events):
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for event in _ordered_events(events):
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try:
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# The signatures have already been checked at this point
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event_auth.check(
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RoomVersions.V1,
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event,
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auth_events,
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do_sig_check=False,
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do_size_check=False,
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)
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return event
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except AuthError:
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pass
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# Use the last event (the one with the least depth) if they all fail
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# the auth check.
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return event
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def _ordered_events(events):
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def key_func(e):
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# we have to use utf-8 rather than ascii here because it turns out we allow
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# people to send us events with non-ascii event IDs :/
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return -int(e.depth), hashlib.sha1(e.event_id.encode("utf-8")).hexdigest()
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return sorted(events, key=key_func)
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