From a2773922d2fe40e6d95d73f532640702709ab526 Mon Sep 17 00:00:00 2001
From: Will Hunt <will@half-shot.uk>
Date: Wed, 3 Mar 2021 16:27:44 +0000
Subject: Send events to appservice based on room membership (#1680)

* Check membership of room

* Use QueryStateAfterEventsResponse

* Fix complexity

* Changes that I made a long time ago

* Rename to appserviceJoinedAtEvent

* Check membership in GetMemberships

* Update QueryMembershipsForRoom

* Tweaks in client API

* Update appserviceJoinedAtEvent

* Comments

* Try QueryMembershipForUser instead

* Undo some changes to client API that shouldn't be needed

* More /event tweaks

* Refactor /event bit

* Go back to QueryMembershipsForRoom because appservices are hard

* Fix bugs in onMessage

* Add comments

Co-authored-by: Neil Alexander <neilalexander@users.noreply.github.com>
---
 appservice/consumers/roomserver.go | 42 ++++++++++++++++++++++++++++++++++----
 1 file changed, 38 insertions(+), 4 deletions(-)

(limited to 'appservice/consumers')

diff --git a/appservice/consumers/roomserver.go b/appservice/consumers/roomserver.go
index 5cbffa35..2ad7f68f 100644
--- a/appservice/consumers/roomserver.go
+++ b/appservice/consumers/roomserver.go
@@ -85,9 +85,6 @@ func (s *OutputRoomEventConsumer) onMessage(msg *sarama.ConsumerMessage) error {
 	}
 
 	if output.Type != api.OutputTypeNewRoomEvent {
-		log.WithField("type", output.Type).Debug(
-			"roomserver output log: ignoring unknown output type",
-		)
 		return nil
 	}
 
@@ -114,6 +111,7 @@ func (s *OutputRoomEventConsumer) filterRoomserverEvents(
 				// Queue this event to be sent off to the application service
 				if err := s.asDB.StoreEvent(ctx, ws.AppService.ID, event); err != nil {
 					log.WithError(err).Warn("failed to insert incoming event into appservices database")
+					return err
 				} else {
 					// Tell our worker to send out new messages by updating remaining message
 					// count and waking them up with a broadcast
@@ -126,8 +124,43 @@ func (s *OutputRoomEventConsumer) filterRoomserverEvents(
 	return nil
 }
 
+// appserviceJoinedAtEvent returns a boolean depending on whether a given
+// appservice has membership at the time a given event was created.
+func (s *OutputRoomEventConsumer) appserviceJoinedAtEvent(ctx context.Context, event *gomatrixserverlib.HeaderedEvent, appservice config.ApplicationService) bool {
+	// TODO: This is only checking the current room state, not the state at
+	// the event in question. Pretty sure this is what Synapse does too, but
+	// until we have a lighter way of checking the state before the event that
+	// doesn't involve state res, then this is probably OK.
+	membershipReq := &api.QueryMembershipsForRoomRequest{
+		RoomID:     event.RoomID(),
+		JoinedOnly: true,
+	}
+	membershipRes := &api.QueryMembershipsForRoomResponse{}
+
+	// XXX: This could potentially race if the state for the event is not known yet
+	// e.g. the event came over federation but we do not have the full state persisted.
+	if err := s.rsAPI.QueryMembershipsForRoom(ctx, membershipReq, membershipRes); err == nil {
+		for _, ev := range membershipRes.JoinEvents {
+			var membership gomatrixserverlib.MemberContent
+			if err = json.Unmarshal(ev.Content, &membership); err != nil || ev.StateKey == nil {
+				continue
+			}
+			if appservice.IsInterestedInUserID(*ev.StateKey) {
+				return true
+			}
+		}
+	} else {
+		log.WithFields(log.Fields{
+			"room_id": event.RoomID(),
+		}).WithError(err).Errorf("Unable to get membership for room")
+	}
+	return false
+}
+
 // appserviceIsInterestedInEvent returns a boolean depending on whether a given
 // event falls within one of a given application service's namespaces.
+//
+// TODO: This should be cached, see https://github.com/matrix-org/dendrite/issues/1682
 func (s *OutputRoomEventConsumer) appserviceIsInterestedInEvent(ctx context.Context, event *gomatrixserverlib.HeaderedEvent, appservice config.ApplicationService) bool {
 	// No reason to queue events if they'll never be sent to the application
 	// service
@@ -162,5 +195,6 @@ func (s *OutputRoomEventConsumer) appserviceIsInterestedInEvent(ctx context.Cont
 		}).WithError(err).Errorf("Unable to get aliases for room")
 	}
 
-	return false
+	// Check if any of the members in the room match the appservice
+	return s.appserviceJoinedAtEvent(ctx, event, appservice)
 }
-- 
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