Track knocking in membership updater

roomserver/api/wrapper.go

@@ -54,6 +54,13 @@ func SendEventWithState(
 		return err
 	}
 
+	// The roomserver processes events strictly in the order they are given,
+	// so we need to make sure that events don't refer to auth events that
+	// the roomserver doesn't know about yet.
+	outliers = gomatrixserverlib.ReverseTopologicalOrdering(
+		outliers, gomatrixserverlib.TopologicalOrderByAuthEvents,
+	)
+
 	var ires []InputRoomEvent
 	for _, outlier := range outliers {
 		if haveEventIDs[outlier.EventID()] {

roomserver/internal/input/input_membership.go

@@ -136,6 +136,8 @@ func (r *Inputer) updateMembership(
 		return updateToJoinMembership(mu, add, updates)
 	case gomatrixserverlib.Leave, gomatrixserverlib.Ban:
 		return updateToLeaveMembership(mu, add, newMembership, updates)
+	case gomatrixserverlib.Knock:
+		return updateToKnockMembership(mu, add, updates)
 	default:
 		panic(fmt.Errorf(
 			"input: membership %q is not one of the allowed values", newMembership,
@@ -220,6 +222,18 @@ func updateToLeaveMembership(
 	return updates, nil
 }
 
+func updateToKnockMembership(
+	mu *shared.MembershipUpdater, add *gomatrixserverlib.Event, updates []api.OutputEvent,
+) ([]api.OutputEvent, error) {
+	if mu.IsLeave() {
+		_, err := mu.SetToKnock(add)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return updates, nil
+}
+
 // membershipChanges pairs up the membership state changes.
 func membershipChanges(removed, added []types.StateEntry) []stateChange {
 	changes := pairUpChanges(removed, added)

roomserver/storage/shared/membership_updater.go

@@ -86,6 +86,11 @@ func (u *MembershipUpdater) IsLeave() bool {
 	return u.membership == tables.MembershipStateLeaveOrBan
 }
 
+// IsKnock implements types.MembershipUpdater
+func (u *MembershipUpdater) IsKnock() bool {
+	return u.membership == tables.MembershipStateKnock
+}
+
 // SetToInvite implements types.MembershipUpdater
 func (u *MembershipUpdater) SetToInvite(event gomatrixserverlib.Event) (bool, error) {
 	var inserted bool
@@ -180,3 +185,21 @@ func (u *MembershipUpdater) SetToLeave(senderUserID string, eventID string) ([]s
 	})
 	return inviteEventIDs, err
 }
+
+// SetToKnock implements types.MembershipUpdater
+func (u *MembershipUpdater) SetToKnock(event *gomatrixserverlib.Event) (bool, error) {
+	var inserted bool
+	err := u.d.Writer.Do(u.d.DB, u.txn, func(txn *sql.Tx) error {
+		senderUserNID, err := u.d.assignStateKeyNID(u.ctx, u.txn, event.Sender())
+		if err != nil {
+			return fmt.Errorf("u.d.AssignStateKeyNID: %w", err)
+		}
+		if u.membership != tables.MembershipStateKnock {
+			if err = u.d.MembershipTable.UpdateMembership(u.ctx, u.txn, u.roomNID, u.targetUserNID, senderUserNID, tables.MembershipStateKnock, 0, false); err != nil {
+				return fmt.Errorf("u.d.MembershipTable.UpdateMembership: %w", err)
+			}
+		}
+		return nil
+	})
+	return inserted, err
+}

roomserver/storage/tables/interface.go

@@ -120,6 +120,7 @@ const (
 	MembershipStateLeaveOrBan MembershipState = 1
 	MembershipStateInvite     MembershipState = 2
 	MembershipStateJoin       MembershipState = 3
+	MembershipStateKnock      MembershipState = 4
 )
 
 type Membership interface {