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Refactor get_events_as_list (#5699)

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A couple of changes here:

* get rid of a redundant `allow_rejected` condition - we should already have filtered out any rejected
  events before we get to that point in the code, and the redundancy is confusing. Instead, let's stick in
  an assertion just to make double-sure we aren't leaking rejected events by mistake.

* factor out a `_get_events_from_cache_or_db` method, which is going to be important for a 
  forthcoming fix to redactions.
This commit is contained in:
Richard van der Hoff 2019-07-17 16:49:19 +01:00 committed by GitHub
parent c831c5b2bb
commit 65c5592b8e
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2 changed files with 73 additions and 46 deletions
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1
changelog.d/5699.bugfix Normal file
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@ -0,0 +1 @@
Fix some problems with authenticating redactions in recent room versions.

118
synapse/storage/events_worker.py
View file

@ -218,37 +218,23 @@ class EventsWorkerStore(SQLBaseStore):
if not event_ids:
defer.returnValue([])
event_id_list = event_ids
event_ids = set(event_ids)
event_entry_map = self._get_events_from_cache(
event_ids, allow_rejected=allow_rejected
# there may be duplicates so we cast the list to a set
event_entry_map = yield self._get_events_from_cache_or_db(
set(event_ids), allow_rejected=allow_rejected
)
missing_events_ids = [e for e in event_ids if e not in event_entry_map]
if missing_events_ids:
log_ctx = LoggingContext.current_context()
log_ctx.record_event_fetch(len(missing_events_ids))
# Note that _enqueue_events is also responsible for turning db rows
# into FrozenEvents (via _get_event_from_row), which involves seeing if
# the events have been redacted, and if so pulling the redaction event out
# of the database to check it.
#
# _enqueue_events is a bit of a rubbish name but naming is hard.
missing_events = yield self._enqueue_events(
missing_events_ids, allow_rejected=allow_rejected
)
event_entry_map.update(missing_events)
events = []
for event_id in event_id_list:
for event_id in event_ids:
entry = event_entry_map.get(event_id, None)
if not entry:
continue
if not allow_rejected:
assert not entry.event.rejected_reason, (
"rejected event returned from _get_events_from_cache_or_db despite "
"allow_rejected=False"
)
# Starting in room version v3, some redactions need to be rechecked if we
# didn't have the redacted event at the time, so we recheck on read
# instead.
@ -291,34 +277,74 @@ class EventsWorkerStore(SQLBaseStore):
# recheck.
entry.event.internal_metadata.recheck_redaction = False
else:
# We don't have the event that is being redacted, so we
# assume that the event isn't authorized for now. (If we
# later receive the event, then we will always redact
# it anyway, since we have this redaction)
# We either don't have the event that is being redacted (so we
# assume that the event isn't authorised for now), or the
# senders don't match (so it will never be authorised). Either
# way, we shouldn't return it.
#
# (If we later receive the event, then we will redact it anyway,
# since we have this redaction)
continue
if allow_rejected or not entry.event.rejected_reason:
if check_redacted and entry.redacted_event:
event = entry.redacted_event
else:
event = entry.event
if check_redacted and entry.redacted_event:
event = entry.redacted_event
else:
event = entry.event
events.append(event)
events.append(event)
if get_prev_content:
if "replaces_state" in event.unsigned:
prev = yield self.get_event(
event.unsigned["replaces_state"],
get_prev_content=False,
allow_none=True,
)
if prev:
event.unsigned = dict(event.unsigned)
event.unsigned["prev_content"] = prev.content
event.unsigned["prev_sender"] = prev.sender
if get_prev_content:
if "replaces_state" in event.unsigned:
prev = yield self.get_event(
event.unsigned["replaces_state"],
get_prev_content=False,
allow_none=True,
)
if prev:
event.unsigned = dict(event.unsigned)
event.unsigned["prev_content"] = prev.content
event.unsigned["prev_sender"] = prev.sender
defer.returnValue(events)
@defer.inlineCallbacks
def _get_events_from_cache_or_db(self, event_ids, allow_rejected=False):
"""Fetch a bunch of events from the cache or the database.
If events are pulled from the database, they will be cached for future lookups.
Args:
event_ids (Iterable[str]): The event_ids of the events to fetch
allow_rejected (bool): Whether to include rejected events
Returns:
Deferred[Dict[str, _EventCacheEntry]]:
map from event id to result
"""
event_entry_map = self._get_events_from_cache(
event_ids, allow_rejected=allow_rejected
)
missing_events_ids = [e for e in event_ids if e not in event_entry_map]
if missing_events_ids:
log_ctx = LoggingContext.current_context()
log_ctx.record_event_fetch(len(missing_events_ids))
# Note that _enqueue_events is also responsible for turning db rows
# into FrozenEvents (via _get_event_from_row), which involves seeing if
# the events have been redacted, and if so pulling the redaction event out
# of the database to check it.
#
# _enqueue_events is a bit of a rubbish name but naming is hard.
missing_events = yield self._enqueue_events(
missing_events_ids, allow_rejected=allow_rejected
)
event_entry_map.update(missing_events)
return event_entry_map
def _invalidate_get_event_cache(self, event_id):
self._get_event_cache.invalidate((event_id,))
@ -326,7 +352,7 @@ class EventsWorkerStore(SQLBaseStore):
"""Fetch events from the caches
Args:
events (list(str)): list of event_ids to fetch
events (Iterable[str]): list of event_ids to fetch
allow_rejected (bool): Whether to return events that were rejected
update_metrics (bool): Whether to update the cache hit ratio metrics