Set historyVisibility for backfilled events over federation

roomserver/api/perform.go

@@ -5,9 +5,10 @@ import (
 	"fmt"
 	"net/http"
 
-	"github.com/matrix-org/dendrite/clientapi/jsonerror"
 	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/matrix-org/util"
+
+	"github.com/matrix-org/dendrite/clientapi/jsonerror"
 )
 
 type PerformErrorCode int
@@ -161,7 +162,8 @@ func (r *PerformBackfillRequest) PrevEventIDs() []string {
 // PerformBackfillResponse is a response to PerformBackfill.
 type PerformBackfillResponse struct {
 	// Missing events, arbritrary order.
-	Events []*gomatrixserverlib.HeaderedEvent `json:"events"`
+	Events            []*gomatrixserverlib.HeaderedEvent  `json:"events"`
+	HistoryVisibility gomatrixserverlib.HistoryVisibility `json:"history_visibility"`
 }
 
 type PerformPublishRequest struct {

roomserver/internal/perform/perform_backfill.go

@@ -164,6 +164,7 @@ func (r *Backfiller) backfillViaFederation(ctx context.Context, req *api.Perform
 	// TODO: update backwards extremities, as that should be moved from syncapi to roomserver at some point.
 
 	res.Events = events
+	res.HistoryVisibility = requester.historyVisiblity
 	return nil
 }
 
@@ -248,6 +249,7 @@ type backfillRequester struct {
 	servers                 []gomatrixserverlib.ServerName
 	eventIDToBeforeStateIDs map[string][]string
 	eventIDMap              map[string]*gomatrixserverlib.Event
+	historyVisiblity        gomatrixserverlib.HistoryVisibility
 }
 
 func newBackfillRequester(
@@ -266,6 +268,7 @@ func newBackfillRequester(
 		eventIDMap:              make(map[string]*gomatrixserverlib.Event),
 		bwExtrems:               bwExtrems,
 		preferServer:            preferServer,
+		historyVisiblity:        gomatrixserverlib.HistoryVisibilityShared,
 	}
 }
 
@@ -447,7 +450,8 @@ FindSuccessor:
 	}
 
 	// possibly return all joined servers depending on history visiblity
-	memberEventsFromVis, err := joinEventsFromHistoryVisibility(ctx, b.db, roomID, stateEntries, b.thisServer)
+	memberEventsFromVis, visibility, err := joinEventsFromHistoryVisibility(ctx, b.db, roomID, stateEntries, b.thisServer)
+	b.historyVisiblity = visibility
 	if err != nil {
 		logrus.WithError(err).Error("ServersAtEvent: failed calculate servers from history visibility rules")
 		return nil
@@ -528,7 +532,7 @@ func (b *backfillRequester) ProvideEvents(roomVer gomatrixserverlib.RoomVersion,
 // pull all events and then filter by that table.
 func joinEventsFromHistoryVisibility(
 	ctx context.Context, db storage.Database, roomID string, stateEntries []types.StateEntry,
-	thisServer gomatrixserverlib.ServerName) ([]types.Event, error) {
+	thisServer gomatrixserverlib.ServerName) ([]types.Event, gomatrixserverlib.HistoryVisibility, error) {
 
 	var eventNIDs []types.EventNID
 	for _, entry := range stateEntries {
@@ -542,7 +546,9 @@ func joinEventsFromHistoryVisibility(
 	// Get all of the events in this state
 	stateEvents, err := db.Events(ctx, eventNIDs)
 	if err != nil {
-		return nil, err
+		// even though the default should be shared, restricting the visibility to joined
+		// feels more secure here.
+		return nil, gomatrixserverlib.HistoryVisibilityJoined, err
 	}
 	events := make([]*gomatrixserverlib.Event, len(stateEvents))
 	for i := range stateEvents {
@@ -551,20 +557,22 @@ func joinEventsFromHistoryVisibility(
 
 	// Can we see events in the room?
 	canSeeEvents := auth.IsServerAllowed(thisServer, true, events)
+	visibility := gomatrixserverlib.HistoryVisibility(auth.HistoryVisibilityForRoom(events))
 	if !canSeeEvents {
-		logrus.Infof("ServersAtEvent history not visible to us: %s", auth.HistoryVisibilityForRoom(events))
-		return nil, nil
+		logrus.Infof("ServersAtEvent history not visible to us: %s", visibility)
+		return nil, visibility, nil
 	}
 	// get joined members
 	info, err := db.RoomInfo(ctx, roomID)
 	if err != nil {
-		return nil, err
+		return nil, visibility, nil
 	}
 	joinEventNIDs, err := db.GetMembershipEventNIDsForRoom(ctx, info.RoomNID, true, false)
 	if err != nil {
-		return nil, err
+		return nil, visibility, err
 	}
-	return db.Events(ctx, joinEventNIDs)
+	evs, err := db.Events(ctx, joinEventNIDs)
+	return evs, visibility, err
 }
 
 func persistEvents(ctx context.Context, db storage.Database, events []*gomatrixserverlib.HeaderedEvent) (types.RoomNID, map[string]types.Event) {

syncapi/routing/messages.go

@@ -350,8 +350,10 @@ func (r *messagesReq) retrieveEvents() (
 	startTime := time.Now()
 	filteredEvents, err := internal.ApplyHistoryVisibilityFilter(r.ctx, r.db, r.rsAPI, events, nil, r.device.UserID, "messages")
 	logrus.WithFields(logrus.Fields{
-		"duration": time.Since(startTime),
-		"room_id":  r.roomID,
+		"duration":      time.Since(startTime),
+		"room_id":       r.roomID,
+		"events_before": len(events),
+		"events_after":  len(filteredEvents),
 	}).Debug("applied history visibility (messages)")
 	return gomatrixserverlib.HeaderedToClientEvents(filteredEvents, gomatrixserverlib.FormatAll), start, end, err
 }
@@ -513,6 +515,9 @@ func (r *messagesReq) backfill(roomID string, backwardsExtremities map[string][]
 
 	// Store the events in the database, while marking them as unfit to show
 	// up in responses to sync requests.
+	if res.HistoryVisibility == "" {
+		res.HistoryVisibility = gomatrixserverlib.HistoryVisibilityShared
+	}
 	for i := range res.Events {
 		_, err = r.db.WriteEvent(
 			context.Background(),
@@ -521,7 +526,7 @@ func (r *messagesReq) backfill(roomID string, backwardsExtremities map[string][]
 			[]string{},
 			[]string{},
 			nil, true,
-			gomatrixserverlib.HistoryVisibilityShared,
+			res.HistoryVisibility,
 		)
 		if err != nil {
 			return nil, err
@@ -534,6 +539,9 @@ func (r *messagesReq) backfill(roomID string, backwardsExtremities map[string][]
 		// last `limit` events
 		events = events[len(events)-limit:]
 	}
+	for _, ev := range events {
+		ev.Visibility = res.HistoryVisibility
+	}
 
 	return events, nil
 }