forked-synapse/synapse/state/v1.py
2020-07-24 10:59:51 -04:00

319 lines
11 KiB
Python

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