synapse-product/synapse/state/v1.py
Richard van der Hoff 428174f902
Split event_auth.check into two parts (#10940)
Broadly, the existing `event_auth.check` function has two parts:
 * a validation section: checks that the event isn't too big, that it has the rught signatures, etc. 
   This bit is independent of the rest of the state in the room, and so need only be done once 
   for each event.
 * an auth section: ensures that the event is allowed, given the rest of the state in the room.
   This gets done multiple times, against various sets of room state, because it forms part of
   the state res algorithm.

Currently, this is implemented with `do_sig_check` and `do_size_check` parameters, but I think
that makes everything hard to follow. Instead, we split the function in two and call each part
separately where it is needed.
2021-09-29 18:59:15 +01:00

371 lines
12 KiB
Python

# 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,
Iterable,
List,
Optional,
Sequence,
Set,
Tuple,
)
from synapse import event_auth
from synapse.api.constants import EventTypes
from synapse.api.errors import AuthError
from synapse.api.room_versions import RoomVersion, RoomVersions
from synapse.events import EventBase
from synapse.types import MutableStateMap, StateMap
logger = logging.getLogger(__name__)
POWER_KEY = (EventTypes.PowerLevels, "")
async def resolve_events_with_store(
room_id: str,
room_version: RoomVersion,
state_sets: Sequence[StateMap[str]],
event_map: Optional[Dict[str, EventBase]],
state_map_factory: Callable[[Iterable[str]], Awaitable[Dict[str, EventBase]]],
) -> StateMap[str]:
"""
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 for 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:
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
)
# 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.
auth_events = _create_auth_events_from_maps(
room_version, 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(
room_version, unconflicted_state, conflicted_state, auth_events, state_map
)
def _seperate(
state_sets: Iterable[StateMap[str]],
) -> Tuple[MutableStateMap[str], MutableStateMap[Set[str]]]:
"""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:
List of dicts of (type, state_key) -> event_id, which are the
different state groups to resolve.
Returns:
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: MutableStateMap[Set[str]] = {}
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(
room_version: RoomVersion,
unconflicted_state: StateMap[str],
conflicted_state: StateMap[Set[str]],
state_map: Dict[str, EventBase],
) -> StateMap[str]:
"""
Args:
room_version: The room version.
unconflicted_state: The unconflicted state map.
conflicted_state: The conflicted state map.
state_map:
Returns:
A map from state key to event id.
"""
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(
room_version, state_map[event_id]
)
for key in keys:
if key not in auth_events:
auth_event_id = unconflicted_state.get(key, None)
if auth_event_id:
auth_events[key] = auth_event_id
return auth_events
def _resolve_with_state(
room_version: RoomVersion,
unconflicted_state_ids: MutableStateMap[str],
conflicted_state_ids: StateMap[Set[str]],
auth_event_ids: StateMap[str],
state_map: Dict[str, EventBase],
):
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(
room_version, 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(
room_version: RoomVersion,
conflicted_state: StateMap[List[EventBase]],
auth_events: MutableStateMap[EventBase],
) -> StateMap[EventBase]:
"""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(
room_version, 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(
room_version, 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(
room_version, 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(
room_version: RoomVersion, events: List[EventBase], auth_events: StateMap[EventBase]
) -> EventBase:
reverse = list(reversed(_ordered_events(events)))
auth_keys = {
key
for event in events
for key in event_auth.auth_types_for_event(room_version, 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_auth_rules_for_event(
RoomVersions.V1,
event,
auth_events,
)
prev_event = event
except AuthError:
return prev_event
return event
def _resolve_normal_events(
events: List[EventBase], auth_events: StateMap[EventBase]
) -> EventBase:
for event in _ordered_events(events):
try:
# The signatures have already been checked at this point
event_auth.check_auth_rules_for_event(
RoomVersions.V1,
event,
auth_events,
)
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: Iterable[EventBase]) -> List[EventBase]:
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)