Add PowerLevelResolver to resolve the powerlevels before a redaction

event

roomserver/internal/input/input_events.go

@@ -26,14 +26,14 @@ import (
 
 	"github.com/tidwall/gjson"
 
-	"github.com/matrix-org/dendrite/roomserver/internal/helpers"
-
 	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/matrix-org/util"
 	"github.com/opentracing/opentracing-go"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/sirupsen/logrus"
 
+	"github.com/matrix-org/dendrite/roomserver/internal/helpers"
+
 	userAPI "github.com/matrix-org/dendrite/userapi/api"
 
 	fedapi "github.com/matrix-org/dendrite/federationapi/api"
@@ -275,25 +275,12 @@ func (r *Inputer) processRoomEvent(
 
 	// Check if the event is allowed by its auth events. If it isn't then
 	// we consider the event to be "rejected" — it will still be persisted.
-	redactAllowed := true
 	if err = gomatrixserverlib.Allowed(event, &authEvents); err != nil {
 		isRejected = true
-		redactAllowed = false
 		rejectionErr = err
 		logger.WithError(rejectionErr).Warnf("Event %s not allowed by auth events", event.EventID())
 	}
 
-	if event.Type() == gomatrixserverlib.MRoomRedaction {
-		ap, _ := authEvents.PowerLevels()
-		if ap != nil {
-			var powerLevels *gomatrixserverlib.PowerLevelContent
-			powerLevels, _ = ap.PowerLevels()
-			if powerLevels != nil {
-				redactAllowed = powerLevels.UserLevel(event.Sender()) >= powerLevels.Redact
-			}
-		}
-	}
-
 	// Accumulate the auth event NIDs.
 	authEventIDs := event.AuthEventIDs()
 	authEventNIDs := make([]types.EventNID, 0, len(authEventIDs))
@@ -369,22 +356,6 @@ func (r *Inputer) processRoomEvent(
 		return fmt.Errorf("updater.StoreEvent: %w", err)
 	}
 
-	// if storing this event results in it being redacted then do so.
-	var (
-		redactedEventID string
-		redactionEvent  *gomatrixserverlib.Event
-		redactedEvent   *gomatrixserverlib.Event
-	)
-	if !isRejected && !isCreateEvent {
-		redactionEvent, redactedEvent, err = r.DB.MaybeRedactEvent(ctx, roomInfo, eventNID, event, redactAllowed)
-		if err != nil {
-			return err
-		}
-		if redactedEvent != nil {
-			redactedEventID = redactedEvent.EventID()
-		}
-	}
-
 	// For outliers we can stop after we've stored the event itself as it
 	// doesn't have any associated state to store and we don't need to
 	// notify anyone about it.
@@ -413,6 +384,23 @@ func (r *Inputer) processRoomEvent(
 		}
 	}
 
+	// if storing this event results in it being redacted then do so.
+	var (
+		redactedEventID string
+		redactionEvent  *gomatrixserverlib.Event
+		redactedEvent   *gomatrixserverlib.Event
+	)
+	if !isRejected && !isCreateEvent {
+		resolver := state.NewStateResolution(r.DB, roomInfo)
+		redactionEvent, redactedEvent, err = r.DB.MaybeRedactEvent(ctx, roomInfo, eventNID, event, &resolver)
+		if err != nil {
+			return err
+		}
+		if redactedEvent != nil {
+			redactedEventID = redactedEvent.EventID()
+		}
+	}
+
 	// We stop here if the event is rejected: We've stored it but won't update
 	// forward extremities or notify downstream components about it.
 	switch {

roomserver/internal/perform/perform_backfill.go

@@ -26,6 +26,7 @@ import (
 	"github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/dendrite/roomserver/auth"
 	"github.com/matrix-org/dendrite/roomserver/internal/helpers"
+	"github.com/matrix-org/dendrite/roomserver/state"
 	"github.com/matrix-org/dendrite/roomserver/storage"
 	"github.com/matrix-org/dendrite/roomserver/types"
 )
@@ -629,7 +630,9 @@ func persistEvents(ctx context.Context, db storage.Database, events []*gomatrixs
 			continue
 		}
 
-		_, redactedEvent, err := db.MaybeRedactEvent(ctx, roomInfo, eventNID, ev.Unwrap(), true)
+		resolver := state.NewStateResolution(db, roomInfo)
+
+		_, redactedEvent, err := db.MaybeRedactEvent(ctx, roomInfo, eventNID, ev.Unwrap(), &resolver)
 		if err != nil {
 			logrus.WithError(err).WithField("event_id", ev.EventID()).Error("Failed to redact event")
 			continue

roomserver/state/state.go

@@ -59,6 +59,47 @@ func NewStateResolution(db StateResolutionStorage, roomInfo *types.RoomInfo) Sta
 	}
 }
 
+type PowerLevelResolver interface {
+	Resolve(ctx context.Context, roomInfo *types.RoomInfo, eventID string) (*gomatrixserverlib.PowerLevelContent, error)
+}
+
+func (p *StateResolution) Resolve(ctx context.Context, roomInfo *types.RoomInfo, eventID string) (*gomatrixserverlib.PowerLevelContent, error) {
+	stateEntries, err := p.LoadStateAtEvent(ctx, eventID)
+	if err != nil {
+		return nil, err
+	}
+
+	wantTuple := types.StateKeyTuple{
+		EventTypeNID:     types.MRoomPowerLevelsNID,
+		EventStateKeyNID: types.EmptyStateKeyNID,
+	}
+
+	var plNID types.EventNID
+	for _, entry := range stateEntries {
+		if entry.StateKeyTuple == wantTuple {
+			plNID = entry.EventNID
+			break
+		}
+	}
+	if plNID == 0 {
+		return nil, fmt.Errorf("unable to find power level event")
+	}
+
+	events, err := p.db.Events(ctx, roomInfo, []types.EventNID{plNID})
+	if err != nil {
+		return nil, err
+	}
+	if len(events) == 0 {
+		return nil, fmt.Errorf("unable to find power level event")
+	}
+	powerlevels, err := events[0].PowerLevels()
+	if err != nil {
+		return nil, err
+	}
+
+	return powerlevels, nil
+}
+
 // LoadStateAtSnapshot loads the full state of a room at a particular snapshot.
 // This is typically the state before an event or the current state of a room.
 // Returns a sorted list of state entries or an error if there was a problem talking to the database.

roomserver/storage/interface.go

@@ -19,6 +19,7 @@ import (
 
 	"github.com/matrix-org/gomatrixserverlib"
 
+	"github.com/matrix-org/dendrite/roomserver/state"
 	"github.com/matrix-org/dendrite/roomserver/storage/shared"
 	"github.com/matrix-org/dendrite/roomserver/storage/tables"
 	"github.com/matrix-org/dendrite/roomserver/types"
@@ -184,7 +185,7 @@ type Database interface {
 	GetOrCreateEventTypeNID(ctx context.Context, eventType string) (eventTypeNID types.EventTypeNID, err error)
 	GetOrCreateEventStateKeyNID(ctx context.Context, eventStateKey *string) (types.EventStateKeyNID, error)
 	MaybeRedactEvent(
-		ctx context.Context, roomInfo *types.RoomInfo, eventNID types.EventNID, event *gomatrixserverlib.Event, redactAllowed bool,
+		ctx context.Context, roomInfo *types.RoomInfo, eventNID types.EventNID, event *gomatrixserverlib.Event, plResolver state.PowerLevelResolver,
 	) (*gomatrixserverlib.Event, *gomatrixserverlib.Event, error)
 }
 
@@ -226,7 +227,7 @@ type EventDatabase interface {
 	// MaybeRedactEvent returns the redaction event and the redacted event if this call resulted in a redaction, else an error
 	// (nil if there was nothing to do)
 	MaybeRedactEvent(
-		ctx context.Context, roomInfo *types.RoomInfo, eventNID types.EventNID, event *gomatrixserverlib.Event, redactAllowed bool,
+		ctx context.Context, roomInfo *types.RoomInfo, eventNID types.EventNID, event *gomatrixserverlib.Event, plResolver state.PowerLevelResolver,
 	) (*gomatrixserverlib.Event, *gomatrixserverlib.Event, error)
 	StoreEvent(ctx context.Context, event *gomatrixserverlib.Event, roomInfo *types.RoomInfo, eventTypeNID types.EventTypeNID, eventStateKeyNID types.EventStateKeyNID, authEventNIDs []types.EventNID, isRejected bool) (types.EventNID, types.StateAtEvent, error)
 }

roomserver/storage/shared/storage.go

@@ -13,6 +13,7 @@ import (
 
 	"github.com/matrix-org/dendrite/internal/caching"
 	"github.com/matrix-org/dendrite/internal/sqlutil"
+	"github.com/matrix-org/dendrite/roomserver/state"
 	"github.com/matrix-org/dendrite/roomserver/storage/tables"
 	"github.com/matrix-org/dendrite/roomserver/types"
 )
@@ -926,7 +927,7 @@ func extractRoomVersionFromCreateEvent(event *gomatrixserverlib.Event) (
 //
 // Returns the redaction event and the redacted event if this call resulted in a redaction.
 func (d *EventDatabase) MaybeRedactEvent(
-	ctx context.Context, roomInfo *types.RoomInfo, eventNID types.EventNID, event *gomatrixserverlib.Event, redactAllowed bool,
+	ctx context.Context, roomInfo *types.RoomInfo, eventNID types.EventNID, event *gomatrixserverlib.Event, plResolver state.PowerLevelResolver,
 ) (*gomatrixserverlib.Event, *gomatrixserverlib.Event, error) {
 	var (
 		redactionEvent, redactedEvent *types.Event
@@ -968,8 +969,14 @@ func (d *EventDatabase) MaybeRedactEvent(
 
 		_, sender1, _ := gomatrixserverlib.SplitID('@', redactedEvent.Sender())
 		_, sender2, _ := gomatrixserverlib.SplitID('@', redactionEvent.Sender())
+		var powerlevels *gomatrixserverlib.PowerLevelContent
+		powerlevels, err = plResolver.Resolve(ctx, roomInfo, redactionEvent.EventID())
+		if err != nil {
+			return err
+		}
+
 		switch {
-		case redactAllowed:
+		case powerlevels.UserLevel(redactionEvent.Sender()) >= powerlevels.Redact:
 			// 1. The power level of the redaction event’s sender is greater than or equal to the redact level.
 		case sender1 == sender2:
 			// 2. The domain of the redaction event’s sender matches that of the original event’s sender.