Clean up federation event auth code (#10539)
* drop old-room hack pretty sure we don't need this any more. * Remove incorrect comment about modifying `context` It doesn't look like the supplied context is ever modified. * Stop `_auth_and_persist_event` modifying its parameters This is only called in three places. Two of them don't pass `auth_events`, and the third doesn't use the dict after passing it in, so this should be non-functional. * Stop `_check_event_auth` modifying its parameters `_check_event_auth` is only called in three places. `on_send_membership_event` doesn't pass an `auth_events`, and `prep` and `_auth_and_persist_event` do not use the map after passing it in. * Stop `_update_auth_events_and_context_for_auth` modifying its parameters Return the updated auth event dict, rather than modifying the parameter. This is only called from `_check_event_auth`. * Improve documentation on `_auth_and_persist_event` Rename `auth_events` parameter to better reflect what it contains. * Improve documentation on `_NewEventInfo` * Improve documentation on `_check_event_auth` rename `auth_events` parameter to better describe what it contains * changelog
This commit is contained in:
Richard van der Hoff
GitHub
parent
f4ade972ad
commit
1bebc0b78c
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Clean up some of the federation event authentication code for clarity.
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@ -109,21 +109,33 @@ soft_failed_event_counter = Counter(
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)
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@attr.s(slots=True)
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@attr.s(slots=True, frozen=True, auto_attribs=True)
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class _NewEventInfo:
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"""Holds information about a received event, ready for passing to _auth_and_persist_events
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Attributes:
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event: the received event
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state: the state at that event
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state: the state at that event, according to /state_ids from a remote
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homeserver. Only populated for backfilled events which are going to be a
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new backwards extremity.
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claimed_auth_event_map: a map of (type, state_key) => event for the event's
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claimed auth_events.
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This can include events which have not yet been persisted, in the case that
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we are backfilling a batch of events.
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Note: May be incomplete: if we were unable to find all of the claimed auth
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events. Also, treat the contents with caution: the events might also have
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been rejected, might not yet have been authorized themselves, or they might
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be in the wrong room.
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auth_events: the auth_event map for that event
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"""
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event = attr.ib(type=EventBase)
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state = attr.ib(type=Optional[Sequence[EventBase]], default=None)
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auth_events = attr.ib(type=Optional[MutableStateMap[EventBase]], default=None)
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event: EventBase
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state: Optional[Sequence[EventBase]]
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claimed_auth_event_map: StateMap[EventBase]
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class FederationHandler(BaseHandler):
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@ -1086,7 +1098,7 @@ class FederationHandler(BaseHandler):
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_NewEventInfo(
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event=ev,
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state=events_to_state[e_id],
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auth_events={
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claimed_auth_event_map={
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(
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auth_events[a_id].type,
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auth_events[a_id].state_key,
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@ -2315,7 +2327,7 @@ class FederationHandler(BaseHandler):
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event: EventBase,
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context: EventContext,
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state: Optional[Iterable[EventBase]] = None,
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auth_events: Optional[MutableStateMap[EventBase]] = None,
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claimed_auth_event_map: Optional[StateMap[EventBase]] = None,
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backfilled: bool = False,
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) -> None:
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"""
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@ -2327,17 +2339,18 @@ class FederationHandler(BaseHandler):
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context:
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The event context.
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NB that this function potentially modifies it.
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state:
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The state events used to check the event for soft-fail. If this is
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not provided the current state events will be used.
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auth_events:
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Map from (event_type, state_key) to event
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Normally, our calculated auth_events based on the state of the room
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at the event's position in the DAG, though occasionally (eg if the
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event is an outlier), may be the auth events claimed by the remote
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server.
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claimed_auth_event_map:
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A map of (type, state_key) => event for the event's claimed auth_events.
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Possibly incomplete, and possibly including events that are not yet
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persisted, or authed, or in the right room.
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Only populated where we may not already have persisted these events -
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for example, when populating outliers.
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backfilled: True if the event was backfilled.
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"""
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context = await self._check_event_auth(
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@ -2345,7 +2358,7 @@ class FederationHandler(BaseHandler):
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event,
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context,
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state=state,
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auth_events=auth_events,
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claimed_auth_event_map=claimed_auth_event_map,
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backfilled=backfilled,
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)
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@ -2409,7 +2422,7 @@ class FederationHandler(BaseHandler):
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event,
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res,
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state=ev_info.state,
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auth_events=ev_info.auth_events,
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claimed_auth_event_map=ev_info.claimed_auth_event_map,
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backfilled=backfilled,
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)
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return res
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@ -2675,7 +2688,7 @@ class FederationHandler(BaseHandler):
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event: EventBase,
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context: EventContext,
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state: Optional[Iterable[EventBase]] = None,
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auth_events: Optional[MutableStateMap[EventBase]] = None,
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claimed_auth_event_map: Optional[StateMap[EventBase]] = None,
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backfilled: bool = False,
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) -> EventContext:
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"""
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@ -2687,21 +2700,19 @@ class FederationHandler(BaseHandler):
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context:
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The event context.
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NB that this function potentially modifies it.
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state:
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The state events used to check the event for soft-fail. If this is
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not provided the current state events will be used.
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auth_events:
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Map from (event_type, state_key) to event
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Normally, our calculated auth_events based on the state of the room
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at the event's position in the DAG, though occasionally (eg if the
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event is an outlier), may be the auth events claimed by the remote
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server.
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claimed_auth_event_map:
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A map of (type, state_key) => event for the event's claimed auth_events.
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Possibly incomplete, and possibly including events that are not yet
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persisted, or authed, or in the right room.
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Also NB that this function adds entries to it.
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Only populated where we may not already have persisted these events -
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for example, when populating outliers, or the state for a backwards
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extremity.
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If this is not provided, it is calculated from the previous state IDs.
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backfilled: True if the event was backfilled.
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Returns:
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@ -2710,7 +2721,12 @@ class FederationHandler(BaseHandler):
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room_version = await self.store.get_room_version_id(event.room_id)
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room_version_obj = KNOWN_ROOM_VERSIONS[room_version]
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if not auth_events:
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if claimed_auth_event_map:
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# if we have a copy of the auth events from the event, use that as the
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# basis for auth.
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auth_events = claimed_auth_event_map
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else:
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# otherwise, we calculate what the auth events *should* be, and use that
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prev_state_ids = await context.get_prev_state_ids()
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auth_events_ids = self._event_auth_handler.compute_auth_events(
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event, prev_state_ids, for_verification=True
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@ -2718,18 +2734,11 @@ class FederationHandler(BaseHandler):
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auth_events_x = await self.store.get_events(auth_events_ids)
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auth_events = {(e.type, e.state_key): e for e in auth_events_x.values()}
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# This is a hack to fix some old rooms where the initial join event
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# didn't reference the create event in its auth events.
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if event.type == EventTypes.Member and not event.auth_event_ids():
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if len(event.prev_event_ids()) == 1 and event.depth < 5:
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c = await self.store.get_event(
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event.prev_event_ids()[0], allow_none=True
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)
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if c and c.type == EventTypes.Create:
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auth_events[(c.type, c.state_key)] = c
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try:
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context = await self._update_auth_events_and_context_for_auth(
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(
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context,
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auth_events_for_auth,
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) = await self._update_auth_events_and_context_for_auth(
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origin, event, context, auth_events
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)
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except Exception:
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@ -2742,9 +2751,10 @@ class FederationHandler(BaseHandler):
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"Ignoring failure and continuing processing of event.",
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event.event_id,
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)
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auth_events_for_auth = auth_events
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try:
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event_auth.check(room_version_obj, event, auth_events=auth_events)
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event_auth.check(room_version_obj, event, auth_events=auth_events_for_auth)
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except AuthError as e:
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logger.warning("Failed auth resolution for %r because %s", event, e)
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context.rejected = RejectedReason.AUTH_ERROR
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@ -2769,8 +2779,8 @@ class FederationHandler(BaseHandler):
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origin: str,
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event: EventBase,
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context: EventContext,
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auth_events: MutableStateMap[EventBase],
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) -> EventContext:
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input_auth_events: StateMap[EventBase],
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) -> Tuple[EventContext, StateMap[EventBase]]:
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"""Helper for _check_event_auth. See there for docs.
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Checks whether a given event has the expected auth events. If it
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@ -2787,7 +2797,7 @@ class FederationHandler(BaseHandler):
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event:
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context:
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auth_events:
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input_auth_events:
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Map from (event_type, state_key) to event
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Normally, our calculated auth_events based on the state of the room
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@ -2795,11 +2805,12 @@ class FederationHandler(BaseHandler):
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event is an outlier), may be the auth events claimed by the remote
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server.
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Also NB that this function adds entries to it.
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Returns:
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updated context
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updated context, updated auth event map
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"""
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# take a copy of input_auth_events before we modify it.
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auth_events: MutableStateMap[EventBase] = dict(input_auth_events)
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event_auth_events = set(event.auth_event_ids())
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# missing_auth is the set of the event's auth_events which we don't yet have
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@ -2828,7 +2839,7 @@ class FederationHandler(BaseHandler):
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# The other side isn't around or doesn't implement the
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# endpoint, so lets just bail out.
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logger.info("Failed to get event auth from remote: %s", e1)
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return context
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return context, auth_events
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seen_remotes = await self.store.have_seen_events(
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event.room_id, [e.event_id for e in remote_auth_chain]
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@ -2859,7 +2870,10 @@ class FederationHandler(BaseHandler):
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await self.state_handler.compute_event_context(e)
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)
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await self._auth_and_persist_event(
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origin, e, missing_auth_event_context, auth_events=auth
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origin,
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e,
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missing_auth_event_context,
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claimed_auth_event_map=auth,
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)
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if e.event_id in event_auth_events:
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@ -2877,14 +2891,14 @@ class FederationHandler(BaseHandler):
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# obviously be empty
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# (b) alternatively, why don't we do it earlier?
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logger.info("Skipping auth_event fetch for outlier")
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return context
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return context, auth_events
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different_auth = event_auth_events.difference(
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e.event_id for e in auth_events.values()
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)
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if not different_auth:
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return context
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return context, auth_events
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logger.info(
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"auth_events refers to events which are not in our calculated auth "
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@ -2910,7 +2924,7 @@ class FederationHandler(BaseHandler):
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# XXX: should we reject the event in this case? It feels like we should,
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# but then shouldn't we also do so if we've failed to fetch any of the
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# auth events?
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return context
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return context, auth_events
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# now we state-resolve between our own idea of the auth events, and the remote's
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# idea of them.
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@ -2940,7 +2954,7 @@ class FederationHandler(BaseHandler):
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event, context, auth_events
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)
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return context
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return context, auth_events
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async def _update_context_for_auth_events(
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self, event: EventBase, context: EventContext, auth_events: StateMap[EventBase]
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@ -75,10 +75,8 @@ class MessageAcceptTests(unittest.HomeserverTestCase):
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)
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self.handler = self.homeserver.get_federation_handler()
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self.handler._check_event_auth = (
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lambda origin, event, context, state, auth_events, backfilled: succeed(
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context
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)
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self.handler._check_event_auth = lambda origin, event, context, state, claimed_auth_event_map, backfilled: succeed(
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context
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)
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self.client = self.homeserver.get_federation_client()
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self.client._check_sigs_and_hash_and_fetch = lambda dest, pdus, **k: succeed(
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