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Diffstat (limited to 'synapse/state/v1.py')
| -rw-r--r-- | synapse/state/v1.py | 293 |
1 files changed, 293 insertions, 0 deletions
diff --git a/synapse/state/v1.py b/synapse/state/v1.py new file mode 100644 index 0000000000..c95477d318 --- /dev/null +++ b/synapse/state/v1.py @@ -0,0 +1,293 @@ +# -*- 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 six import iteritems, iterkeys, itervalues + +from twisted.internet import defer + +from synapse import event_auth +from synapse.api.constants import EventTypes +from synapse.api.errors import AuthError + +logger = logging.getLogger(__name__) + + +POWER_KEY = (EventTypes.PowerLevels, "") + + +@defer.inlineCallbacks +def resolve_events_with_factory(state_sets, event_map, state_map_factory): + """ + Args: + state_sets(list): List of dicts of (type, state_key) -> event_id, + which are the different state groups to resolve. + + event_map(dict[str,FrozenEvent]|None): + 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(func): will be called + with a list of event_ids that are needed, and should return with + a Deferred of 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: + defer.returnValue(state_sets[0]) + + unconflicted_state, conflicted_state = _seperate( + state_sets, + ) + + needed_events = set( + event_id + for event_ids in itervalues(conflicted_state) + for event_id in event_ids + ) + if event_map is not None: + needed_events -= set(iterkeys(event_map)) + + logger.info("Asking for %d conflicted events", len(needed_events)) + + # 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 = yield state_map_factory(needed_events) + if event_map is not None: + state_map.update(event_map) + + # 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(itervalues(auth_events)) + new_needed_events -= needed_events + if event_map is not None: + new_needed_events -= set(iterkeys(event_map)) + + logger.info("Asking for %d auth events", len(new_needed_events)) + + state_map_new = yield state_map_factory(new_needed_events) + state_map.update(state_map_new) + + defer.returnValue(_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 iteritems(state_set): + # 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 itervalues(conflicted_state): + 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 iteritems(conflicted_state_ids): + 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 iteritems(auth_event_ids) + 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 iteritems(resolved_state): + 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 iteritems(conflicted_state): + 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 iteritems(conflicted_state): + 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 iteritems(conflicted_state): + 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 = [i for i in reversed(_ordered_events(events))] + + auth_keys = set( + 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(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(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): + return -int(e.depth), hashlib.sha1(e.event_id.encode('ascii')).hexdigest() + + return sorted(events, key=key_func) |