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Inline _check_event_auth for outliers (#10926)

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* Inline `_check_event_auth` for outliers

When we are persisting an outlier, most of `_check_event_auth` is redundant:

 * `_update_auth_events_and_context_for_auth` does nothing, because the
   `input_auth_events` are (now) exactly the event's auth_events,
   which means that `missing_auth` is empty.

 * we don't care about soft-fail, kicking guest users or `send_on_behalf_of`
   for outliers

... so the only thing that matters is the auth itself, so let's just do that.

* `_auth_and_persist_fetched_events_inner`: de-async `prep`

`prep` no longer calls any `async` methods, so let's make it synchronous.

* Simplify `_check_event_auth`

We no longer need to support outliers here, which makes things rather simpler.

* changelog

* lint
This commit is contained in:
Richard van der Hoff 2021-09-28 15:25:07 +01:00 committed by GitHub
parent eb2c7e51c4
commit 2622b28c5c
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4 changed files with 38 additions and 59 deletions
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2
changelog.d/10896.misc
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@ -1 +1 @@
Clean up some of the federation event authentication code for clarity.
Clean up some of the federation event authentication code for clarity.

1
changelog.d/10926.misc Normal file
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@ -0,0 +1 @@
Clean up some of the federation event authentication code for clarity.

93
synapse/handlers/federation_event.py
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@ -68,11 +68,7 @@ from synapse.types import (
UserID,
get_domain_from_id,
)
from synapse.util.async_helpers import (
Linearizer,
concurrently_execute,
yieldable_gather_results,
)
from synapse.util.async_helpers import Linearizer, concurrently_execute
from synapse.util.iterutils import batch_iter
from synapse.util.retryutils import NotRetryingDestination
from synapse.util.stringutils import shortstr
@ -1189,7 +1185,10 @@ class FederationEventHandler:
allow_rejected=True,
)
async def prep(event: EventBase) -> Optional[Tuple[EventBase, EventContext]]:
room_version = await self._store.get_room_version_id(room_id)
room_version_obj = KNOWN_ROOM_VERSIONS[room_version]
def prep(event: EventBase) -> Optional[Tuple[EventBase, EventContext]]:
with nested_logging_context(suffix=event.event_id):
auth = {}
for auth_event_id in event.auth_event_ids():
@ -1207,17 +1206,15 @@ class FederationEventHandler:
auth[(ae.type, ae.state_key)] = ae
context = EventContext.for_outlier()
context = await self._check_event_auth(
origin,
event,
context,
claimed_auth_event_map=auth,
)
try:
event_auth.check(room_version_obj, event, auth_events=auth)
except AuthError as e:
logger.warning("Rejecting %r because %s", event, e)
context.rejected = RejectedReason.AUTH_ERROR
return event, context
events_to_persist = (
x for x in await yieldable_gather_results(prep, fetched_events) if x
)
events_to_persist = (x for x in (prep(event) for event in fetched_events) if x)
await self.persist_events_and_notify(room_id, tuple(events_to_persist))
async def _check_event_auth(
@ -1226,7 +1223,6 @@ class FederationEventHandler:
event: EventBase,
context: EventContext,
state: Optional[Iterable[EventBase]] = None,
claimed_auth_event_map: Optional[StateMap[EventBase]] = None,
backfilled: bool = False,
) -> EventContext:
"""
@ -1242,42 +1238,36 @@ class FederationEventHandler:
The state events used to check the event for soft-fail. If this is
not provided the current state events will be used.
claimed_auth_event_map:
A map of (type, state_key) => event for the event's claimed auth_events.
Possibly including events that were rejected, or are in the wrong room.
Only populated when populating outliers.
backfilled: True if the event was backfilled.
Returns:
The updated context object.
"""
# claimed_auth_event_map should be given iff the event is an outlier
assert bool(claimed_auth_event_map) == event.internal_metadata.outlier
# This method should only be used for non-outliers
assert not event.internal_metadata.outlier
room_version = await self._store.get_room_version_id(event.room_id)
room_version_obj = KNOWN_ROOM_VERSIONS[room_version]
if claimed_auth_event_map:
# if we have a copy of the auth events from the event, use that as the
# basis for auth.
auth_events = claimed_auth_event_map
else:
# otherwise, we calculate what the auth events *should* be, and use that
prev_state_ids = await context.get_prev_state_ids()
auth_events_ids = self._event_auth_handler.compute_auth_events(
event, prev_state_ids, for_verification=True
)
auth_events_x = await self._store.get_events(auth_events_ids)
auth_events = {(e.type, e.state_key): e for e in auth_events_x.values()}
# calculate what the auth events *should* be, to use as a basis for auth.
prev_state_ids = await context.get_prev_state_ids()
auth_events_ids = self._event_auth_handler.compute_auth_events(
event, prev_state_ids, for_verification=True
)
auth_events_x = await self._store.get_events(auth_events_ids)
calculated_auth_event_map = {
(e.type, e.state_key): e for e in auth_events_x.values()
}
try:
(
context,
auth_events_for_auth,
) = await self._update_auth_events_and_context_for_auth(
origin, event, context, auth_events
origin,
event,
context,
calculated_auth_event_map=calculated_auth_event_map,
)
except Exception:
# We don't really mind if the above fails, so lets not fail
@ -1289,7 +1279,7 @@ class FederationEventHandler:
"Ignoring failure and continuing processing of event.",
event.event_id,
)
auth_events_for_auth = auth_events
auth_events_for_auth = calculated_auth_event_map
try:
event_auth.check(room_version_obj, event, auth_events=auth_events_for_auth)
@ -1425,7 +1415,7 @@ class FederationEventHandler:
origin: str,
event: EventBase,
context: EventContext,
input_auth_events: StateMap[EventBase],
calculated_auth_event_map: StateMap[EventBase],
) -> Tuple[EventContext, StateMap[EventBase]]:
"""Helper for _check_event_auth. See there for docs.
@ -1443,19 +1433,17 @@ class FederationEventHandler:
event:
context:
input_auth_events:
Map from (event_type, state_key) to event
Normally, our calculated auth_events based on the state of the room
at the event's position in the DAG, though occasionally (eg if the
event is an outlier), may be the auth events claimed by the remote
server.
calculated_auth_event_map:
Our calculated auth_events based on the state of the room
at the event's position in the DAG.
Returns:
updated context, updated auth event map
"""
# take a copy of input_auth_events before we modify it.
auth_events: MutableStateMap[EventBase] = dict(input_auth_events)
assert not event.internal_metadata.outlier
# take a copy of calculated_auth_event_map before we modify it.
auth_events: MutableStateMap[EventBase] = dict(calculated_auth_event_map)
event_auth_events = set(event.auth_event_ids())
@ -1496,15 +1484,6 @@ class FederationEventHandler:
}
)
if event.internal_metadata.is_outlier():
# XXX: given that, for an outlier, we'll be working with the
# event's *claimed* auth events rather than those we calculated:
# (a) is there any point in this test, since different_auth below will
# obviously be empty
# (b) alternatively, why don't we do it earlier?
logger.info("Skipping auth_event fetch for outlier")
return context, auth_events
different_auth = event_auth_events.difference(
e.event_id for e in auth_events.values()
)

1
tests/test_federation.py
View file

@ -82,7 +82,6 @@ class MessageAcceptTests(unittest.HomeserverTestCase):
event,
context,
state=None,
claimed_auth_event_map=None,
backfilled=False,
):
return context