Membership updater refactoring (#2541)

* Membership updater refactoring

* Pass in membership state

* Use membership check rather than referring to state directly

* Delete irrelevant membership states

* We don't need the leave event after all

* Tweaks

* Put a log entry in that I might stand a chance of finding

* Be less panicky

* Tweak invite handling

* Don't freak if we can't find the event NID

* Use event NID from `types.Event`

* Clean up

* Better invite handling

* Placate the almighty linter

* Blacklist a Sytest which is otherwise fine under Complement for reasons I don't understand

* Fix the sytest after all (thanks @S7evinK for the spot)

roomserver/internal/perform/perform_invite.go

@@ -39,11 +39,13 @@ type Inviter struct {
 	Inputer *input.Inputer
 }
 
+// nolint:gocyclo
 func (r *Inviter) PerformInvite(
 	ctx context.Context,
 	req *api.PerformInviteRequest,
 	res *api.PerformInviteResponse,
 ) ([]api.OutputEvent, error) {
+	var outputUpdates []api.OutputEvent
 	event := req.Event
 	if event.StateKey() == nil {
 		return nil, fmt.Errorf("invite must be a state event")
@@ -66,6 +68,13 @@ func (r *Inviter) PerformInvite(
 	}
 	isTargetLocal := domain == r.Cfg.Matrix.ServerName
 	isOriginLocal := event.Origin() == r.Cfg.Matrix.ServerName
+	if !isOriginLocal && !isTargetLocal {
+		res.Error = &api.PerformError{
+			Code: api.PerformErrorBadRequest,
+			Msg:  "The invite must be either from or to a local user",
+		}
+		return nil, nil
+	}
 
 	logger := util.GetLogger(ctx).WithFields(map[string]interface{}{
 		"inviter":  event.Sender(),
@@ -97,6 +106,34 @@ func (r *Inviter) PerformInvite(
 		}
 	}
 
+	updateMembershipTableManually := func() ([]api.OutputEvent, error) {
+		var updater *shared.MembershipUpdater
+		if updater, err = r.DB.MembershipUpdater(ctx, roomID, targetUserID, isTargetLocal, req.RoomVersion); err != nil {
+			return nil, fmt.Errorf("r.DB.MembershipUpdater: %w", err)
+		}
+		outputUpdates, err = helpers.UpdateToInviteMembership(updater, &types.Event{
+			EventNID: 0,
+			Event:    event.Unwrap(),
+		}, outputUpdates, req.Event.RoomVersion)
+		if err != nil {
+			return nil, fmt.Errorf("updateToInviteMembership: %w", err)
+		}
+		if err = updater.Commit(); err != nil {
+			return nil, fmt.Errorf("updater.Commit: %w", err)
+		}
+		logger.Debugf("updated membership to invite and sending invite OutputEvent")
+		return outputUpdates, nil
+	}
+
+	if (info == nil || info.IsStub) && !isOriginLocal && isTargetLocal {
+		// The invite came in over federation for a room that we don't know about
+		// yet. We need to handle this a bit differently to most invites because
+		// we don't know the room state, therefore the roomserver can't process
+		// an input event. Instead we will update the membership table with the
+		// new invite and generate an output event.
+		return updateMembershipTableManually()
+	}
+
 	var isAlreadyJoined bool
 	if info != nil {
 		_, isAlreadyJoined, _, err = r.DB.GetMembership(ctx, info.RoomNID, *event.StateKey())
@@ -140,31 +177,13 @@ func (r *Inviter) PerformInvite(
 		return nil, nil
 	}
 
+	// If the invite originated remotely then we can't send an
+	// InputRoomEvent for the invite as it will never pass auth checks
+	// due to lacking room state, but we still need to tell the client
+	// about the invite so we can accept it, hence we return an output
+	// event to send to the Sync API.
 	if !isOriginLocal {
-		// The invite originated over federation. Process the membership
-		// update, which will notify the sync API etc about the incoming
-		// invite. We do NOT send an InputRoomEvent for the invite as it
-		// will never pass auth checks due to lacking room state, but we
-		// still need to tell the client about the invite so we can accept
-		// it, hence we return an output event to send to the sync api.
-		var updater *shared.MembershipUpdater
-		updater, err = r.DB.MembershipUpdater(ctx, roomID, targetUserID, isTargetLocal, req.RoomVersion)
-		if err != nil {
-			return nil, fmt.Errorf("r.DB.MembershipUpdater: %w", err)
-		}
-
-		unwrapped := event.Unwrap()
-		var outputUpdates []api.OutputEvent
-		outputUpdates, err = helpers.UpdateToInviteMembership(updater, unwrapped, nil, req.Event.RoomVersion)
-		if err != nil {
-			return nil, fmt.Errorf("updateToInviteMembership: %w", err)
-		}
-
-		if err = updater.Commit(); err != nil {
-			return nil, fmt.Errorf("updater.Commit: %w", err)
-		}
-		logger.Debugf("updated membership to invite and sending invite OutputEvent")
-		return outputUpdates, nil
+		return updateMembershipTableManually()
 	}
 
 	// The invite originated locally. Therefore we have a responsibility to
@@ -229,12 +248,11 @@ func (r *Inviter) PerformInvite(
 			Code: api.PerformErrorNotAllowed,
 		}
 		logger.WithError(err).WithField("event_id", event.EventID()).Error("r.InputRoomEvents failed")
-		return nil, nil
 	}
 
 	// Don't notify the sync api of this event in the same way as a federated invite so the invitee
 	// gets the invite, as the roomserver will do this when it processes the m.room.member invite.
-	return nil, nil
+	return outputUpdates, nil
 }
 
 func buildInviteStrippedState(

roomserver/internal/perform/perform_join.go

@@ -268,21 +268,19 @@ func (r *Joiner) performJoinRoomByID(
 	case nil:
 		// The room join is local. Send the new join event into the
 		// roomserver. First of all check that the user isn't already
-		// a member of the room.
-		alreadyJoined := false
-		for _, se := range buildRes.StateEvents {
-			if !se.StateKeyEquals(userID) {
-				continue
-			}
-			if membership, merr := se.Membership(); merr == nil {
-				alreadyJoined = (membership == gomatrixserverlib.Join)
-				break
-			}
+		// a member of the room. This is best-effort (as in we won't
+		// fail if we can't find the existing membership) because there
+		// is really no harm in just sending another membership event.
+		membershipReq := &api.QueryMembershipForUserRequest{
+			RoomID: req.RoomIDOrAlias,
+			UserID: userID,
 		}
+		membershipRes := &api.QueryMembershipForUserResponse{}
+		_ = r.Queryer.QueryMembershipForUser(ctx, membershipReq, membershipRes)
 
 		// If we haven't already joined the room then send an event
 		// into the room changing our membership status.
-		if !alreadyJoined {
+		if !membershipRes.RoomExists || !membershipRes.IsInRoom {
 			inputReq := rsAPI.InputRoomEventsRequest{
 				InputRoomEvents: []rsAPI.InputRoomEvent{
 					{

roomserver/internal/perform/perform_leave.go

@@ -228,14 +228,14 @@ func (r *Leaver) performFederatedRejectInvite(
 		util.GetLogger(ctx).WithError(err).Errorf("failed to get MembershipUpdater, still retiring invite event")
 	}
 	if updater != nil {
-		if _, err = updater.SetToLeave(req.UserID, eventID); err != nil {
-			util.GetLogger(ctx).WithError(err).Errorf("failed to set membership to leave, still retiring invite event")
+		if err = updater.Delete(); err != nil {
+			util.GetLogger(ctx).WithError(err).Errorf("failed to delete membership, still retiring invite event")
 			if err = updater.Rollback(); err != nil {
-				util.GetLogger(ctx).WithError(err).Errorf("failed to rollback membership leave, still retiring invite event")
+				util.GetLogger(ctx).WithError(err).Errorf("failed to rollback deleting membership, still retiring invite event")
 			}
 		} else {
 			if err = updater.Commit(); err != nil {
-				util.GetLogger(ctx).WithError(err).Errorf("failed to commit membership update, still retiring invite event")
+				util.GetLogger(ctx).WithError(err).Errorf("failed to commit deleting membership, still retiring invite event")
 			}
 		}
 	}