Tweaks around `/messages` (#3149)

Try to mitigate some issues with `/messages`

11 files changed, 178 insertions, 84 deletions

diff --git a/syncapi/routing/messages.go b/syncapi/routing/messages.go
index c3871618..23a09544 100644
--- a/syncapi/routing/messages.go
+++ b/syncapi/routing/messages.go
@@ -53,6 +53,7 @@ type messagesReq struct {
 	wasToProvided    bool
 	backwardOrdering bool
 	filter           *synctypes.RoomEventFilter
+	didBackfill      bool
 }
 
 type messagesResp struct {
@@ -251,18 +252,19 @@ func OnIncomingMessagesRequest(
 	}
 
 	// If start and end are equal, we either reached the beginning or something else
-	// is wrong. To avoid endless loops from clients, set end to 0 an empty string
-	if start == end {
+	// is wrong. If we have nothing to return set end to 0.
+	if start == end || len(clientEvents) == 0 {
 		end = types.TopologyToken{}
 	}
 
 	util.GetLogger(req.Context()).WithFields(logrus.Fields{
-		"from":         from.String(),
-		"to":           to.String(),
-		"limit":        filter.Limit,
-		"backwards":    backwardOrdering,
-		"return_start": start.String(),
-		"return_end":   end.String(),
+		"request_from":   from.String(),
+		"request_to":     to.String(),
+		"limit":          filter.Limit,
+		"backwards":      backwardOrdering,
+		"response_start": start.String(),
+		"response_end":   end.String(),
+		"backfilled":     mReq.didBackfill,
 	}).Info("Responding")
 
 	res := messagesResp{
@@ -284,11 +286,6 @@ func OnIncomingMessagesRequest(
 		})...)
 	}
 
-	// If we didn't return any events, set the end to an empty string, so it will be omitted
-	// in the response JSON.
-	if len(res.Chunk) == 0 {
-		res.End = ""
-	}
 	if fromStream != nil {
 		res.StartStream = fromStream.String()
 	}
@@ -328,11 +325,12 @@ func (r *messagesReq) retrieveEvents(ctx context.Context, rsAPI api.SyncRoomserv
 ) {
 	emptyToken := types.TopologyToken{}
 	// Retrieve the events from the local database.
-	streamEvents, err := r.snapshot.GetEventsInTopologicalRange(r.ctx, r.from, r.to, r.roomID, r.filter, r.backwardOrdering)
+	streamEvents, _, end, err := r.snapshot.GetEventsInTopologicalRange(r.ctx, r.from, r.to, r.roomID, r.filter, r.backwardOrdering)
 	if err != nil {
 		err = fmt.Errorf("GetEventsInRange: %w", err)
-		return []synctypes.ClientEvent{}, emptyToken, emptyToken, err
+		return []synctypes.ClientEvent{}, *r.from, emptyToken, err
 	}
+	end.Decrement()
 
 	var events []*rstypes.HeaderedEvent
 	util.GetLogger(r.ctx).WithFields(logrus.Fields{
@@ -346,32 +344,54 @@ func (r *messagesReq) retrieveEvents(ctx context.Context, rsAPI api.SyncRoomserv
 	// on the ordering), or we've reached a backward extremity.
 	if len(streamEvents) == 0 {
 		if events, err = r.handleEmptyEventsSlice(); err != nil {
-			return []synctypes.ClientEvent{}, emptyToken, emptyToken, err
+			return []synctypes.ClientEvent{}, *r.from, emptyToken, err
 		}
 	} else {
 		if events, err = r.handleNonEmptyEventsSlice(streamEvents); err != nil {
-			return []synctypes.ClientEvent{}, emptyToken, emptyToken, err
+			return []synctypes.ClientEvent{}, *r.from, emptyToken, err
 		}
 	}
 
 	// If we didn't get any event, we don't need to proceed any further.
 	if len(events) == 0 {
-		return []synctypes.ClientEvent{}, *r.from, *r.to, nil
+		return []synctypes.ClientEvent{}, *r.from, emptyToken, nil
 	}
 
-	// Get the position of the first and the last event in the room's topology.
-	// This position is currently determined by the event's depth, so we could
-	// also use it instead of retrieving from the database. However, if we ever
-	// change the way topological positions are defined (as depth isn't the most
-	// reliable way to define it), it would be easier and less troublesome to
-	// only have to change it in one place, i.e. the database.
-	start, end, err = r.getStartEnd(events)
+	// Apply room history visibility filter
+	startTime := time.Now()
+	filteredEvents, err := internal.ApplyHistoryVisibilityFilter(r.ctx, r.snapshot, r.rsAPI, events, nil, r.device.UserID, "messages")
 	if err != nil {
-		return []synctypes.ClientEvent{}, *r.from, *r.to, err
+		return []synctypes.ClientEvent{}, *r.from, *r.to, nil
+	}
+	logrus.WithFields(logrus.Fields{
+		"duration":      time.Since(startTime),
+		"room_id":       r.roomID,
+		"events_before": len(events),
+		"events_after":  len(filteredEvents),
+	}).Debug("applied history visibility (messages)")
+
+	// No events left after applying history visibility
+	if len(filteredEvents) == 0 {
+		return []synctypes.ClientEvent{}, *r.from, emptyToken, nil
+	}
+
+	// If we backfilled in the process of getting events, we need
+	// to re-fetch the start/end positions
+	if r.didBackfill {
+		_, end, err = r.getStartEnd(filteredEvents)
+		if err != nil {
+			return []synctypes.ClientEvent{}, *r.from, *r.to, err
+		}
 	}
 
 	// Sort the events to ensure we send them in the right order.
 	if r.backwardOrdering {
+		if events[len(events)-1].Type() == spec.MRoomCreate {
+			// NOTSPEC: We've hit the beginning of the room so there's really nowhere
+			// else to go. This seems to fix Element iOS from looping on /messages endlessly.
+			end = types.TopologyToken{}
+		}
+
 		// This reverses the array from old->new to new->old
 		reversed := func(in []*rstypes.HeaderedEvent) []*rstypes.HeaderedEvent {
 			out := make([]*rstypes.HeaderedEvent, len(in))
@@ -380,24 +400,14 @@ func (r *messagesReq) retrieveEvents(ctx context.Context, rsAPI api.SyncRoomserv
 			}
 			return out
 		}
-		events = reversed(events)
-	}
-	if len(events) == 0 {
-		return []synctypes.ClientEvent{}, *r.from, *r.to, nil
+		filteredEvents = reversed(filteredEvents)
 	}
 
-	// Apply room history visibility filter
-	startTime := time.Now()
-	filteredEvents, err := internal.ApplyHistoryVisibilityFilter(r.ctx, r.snapshot, r.rsAPI, events, nil, r.device.UserID, "messages")
-	logrus.WithFields(logrus.Fields{
-		"duration":      time.Since(startTime),
-		"room_id":       r.roomID,
-		"events_before": len(events),
-		"events_after":  len(filteredEvents),
-	}).Debug("applied history visibility (messages)")
+	start = *r.from
+
 	return synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(filteredEvents), synctypes.FormatAll, func(roomID spec.RoomID, senderID spec.SenderID) (*spec.UserID, error) {
 		return rsAPI.QueryUserIDForSender(ctx, roomID, senderID)
-	}), start, end, err
+	}), start, end, nil
 }
 
 func (r *messagesReq) getStartEnd(events []*rstypes.HeaderedEvent) (start, end types.TopologyToken, err error) {
@@ -450,6 +460,7 @@ func (r *messagesReq) handleEmptyEventsSlice() (
 		if err != nil {
 			return
 		}
+		r.didBackfill = true
 	} else {
 		// If not, it means the slice was empty because we reached the room's
 		// creation, so return an empty slice.
@@ -499,7 +510,7 @@ func (r *messagesReq) handleNonEmptyEventsSlice(streamEvents []types.StreamEvent
 		if err != nil {
 			return
 		}
-
+		r.didBackfill = true
 		// Append the PDUs to the list to send back to the client.
 		events = append(events, pdus...)
 	}
@@ -561,15 +572,17 @@ func (r *messagesReq) backfill(roomID string, backwardsExtremities map[string][]
 	if res.HistoryVisibility == "" {
 		res.HistoryVisibility = gomatrixserverlib.HistoryVisibilityShared
 	}
-	for i := range res.Events {
+	events := res.Events
+	for i := range events {
+		events[i].Visibility = res.HistoryVisibility
 		_, err = r.db.WriteEvent(
 			context.Background(),
-			res.Events[i],
+			events[i],
 			[]*rstypes.HeaderedEvent{},
 			[]string{},
 			[]string{},
 			nil, true,
-			res.HistoryVisibility,
+			events[i].Visibility,
 		)
 		if err != nil {
 			return nil, err
@@ -577,14 +590,10 @@ func (r *messagesReq) backfill(roomID string, backwardsExtremities map[string][]
 	}
 
 	// we may have got more than the requested limit so resize now
-	events := res.Events
 	if len(events) > limit {
 		// last `limit` events
 		events = events[len(events)-limit:]
 	}
-	for _, ev := range events {
-		ev.Visibility = res.HistoryVisibility
-	}
 
 	return events, nil
 }
diff --git a/syncapi/routing/routing.go b/syncapi/routing/routing.go
index 8542c0b7..a837e169 100644
--- a/syncapi/routing/routing.go
+++ b/syncapi/routing/routing.go
@@ -43,6 +43,7 @@ func Setup(
 	cfg *config.SyncAPI,
 	lazyLoadCache caching.LazyLoadCache,
 	fts fulltext.Indexer,
+	rateLimits *httputil.RateLimits,
 ) {
 	v1unstablemux := csMux.PathPrefix("/{apiversion:(?:v1|unstable)}/").Subrouter()
 	v3mux := csMux.PathPrefix("/{apiversion:(?:r0|v3)}/").Subrouter()
@@ -53,6 +54,10 @@ func Setup(
 	}, httputil.WithAllowGuests())).Methods(http.MethodGet, http.MethodOptions)
 
 	v3mux.Handle("/rooms/{roomID}/messages", httputil.MakeAuthAPI("room_messages", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
+		// not specced, but ensure we're rate limiting requests to this endpoint
+		if r := rateLimits.Limit(req, device); r != nil {
+			return *r
+		}
 		vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 		if err != nil {
 			return util.ErrorResponse(err)
diff --git a/syncapi/storage/interface.go b/syncapi/storage/interface.go
index 243b2592..dca5d1a1 100644
--- a/syncapi/storage/interface.go
+++ b/syncapi/storage/interface.go
@@ -81,8 +81,11 @@ type DatabaseTransaction interface {
 	// If no data is retrieved, returns an empty map
 	// If there was an issue with the retrieval, returns an error
 	GetAccountDataInRange(ctx context.Context, userID string, r types.Range, accountDataFilterPart *synctypes.EventFilter) (map[string][]string, types.StreamPosition, error)
-	// GetEventsInTopologicalRange retrieves all of the events on a given ordering using the given extremities and limit. If backwardsOrdering is true, the most recent event must be first, else last.
-	GetEventsInTopologicalRange(ctx context.Context, from, to *types.TopologyToken, roomID string, filter *synctypes.RoomEventFilter, backwardOrdering bool) (events []types.StreamEvent, err error)
+	// GetEventsInTopologicalRange retrieves all of the events on a given ordering using the given extremities and limit.
+	// If backwardsOrdering is true, the most recent event must be first, else last.
+	// Returns the filtered StreamEvents on success. Returns **unfiltered** StreamEvents and ErrNoEventsForFilter if
+	// the provided filter removed all events, this can be used to still calculate the start/end position. (e.g for `/messages`)
+	GetEventsInTopologicalRange(ctx context.Context, from, to *types.TopologyToken, roomID string, filter *synctypes.RoomEventFilter, backwardOrdering bool) (events []types.StreamEvent, start, end types.TopologyToken, err error)
 	// EventPositionInTopology returns the depth and stream position of the given event.
 	EventPositionInTopology(ctx context.Context, eventID string) (types.TopologyToken, error)
 	// BackwardExtremitiesForRoom returns a map of backwards extremity event ID to a list of its prev_events.
diff --git a/syncapi/storage/postgres/output_room_events_topology_table.go b/syncapi/storage/postgres/output_room_events_topology_table.go
index 7140a92f..b281f330 100644
--- a/syncapi/storage/postgres/output_room_events_topology_table.go
+++ b/syncapi/storage/postgres/output_room_events_topology_table.go
@@ -48,14 +48,14 @@ const insertEventInTopologySQL = "" +
 	" RETURNING topological_position"
 
 const selectEventIDsInRangeASCSQL = "" +
-	"SELECT event_id FROM syncapi_output_room_events_topology" +
+	"SELECT event_id, topological_position, stream_position FROM syncapi_output_room_events_topology" +
 	" WHERE room_id = $1 AND (" +
 	"(topological_position > $2 AND topological_position < $3) OR" +
 	"(topological_position = $4 AND stream_position >= $5)" +
 	") ORDER BY topological_position ASC, stream_position ASC LIMIT $6"
 
 const selectEventIDsInRangeDESCSQL = "" +
-	"SELECT event_id FROM syncapi_output_room_events_topology" +
+	"SELECT event_id, topological_position, stream_position FROM syncapi_output_room_events_topology" +
 	" WHERE room_id = $1 AND (" +
 	"(topological_position > $2 AND topological_position < $3) OR" +
 	"(topological_position = $4 AND stream_position <= $5)" +
@@ -113,12 +113,13 @@ func (s *outputRoomEventsTopologyStatements) InsertEventInTopology(
 }
 
 // SelectEventIDsInRange selects the IDs of events which positions are within a
-// given range in a given room's topological order.
+// given range in a given room's topological order. Returns the start/end topological tokens for
+// the returned eventIDs.
 // Returns an empty slice if no events match the given range.
 func (s *outputRoomEventsTopologyStatements) SelectEventIDsInRange(
 	ctx context.Context, txn *sql.Tx, roomID string, minDepth, maxDepth, maxStreamPos types.StreamPosition,
 	limit int, chronologicalOrder bool,
-) (eventIDs []string, err error) {
+) (eventIDs []string, start, end types.TopologyToken, err error) {
 	// Decide on the selection's order according to whether chronological order
 	// is requested or not.
 	var stmt *sql.Stmt
@@ -132,7 +133,7 @@ func (s *outputRoomEventsTopologyStatements) SelectEventIDsInRange(
 	rows, err := stmt.QueryContext(ctx, roomID, minDepth, maxDepth, maxDepth, maxStreamPos, limit)
 	if err == sql.ErrNoRows {
 		// If no event matched the request, return an empty slice.
-		return []string{}, nil
+		return []string{}, start, end, nil
 	} else if err != nil {
 		return
 	}
@@ -140,14 +141,23 @@ func (s *outputRoomEventsTopologyStatements) SelectEventIDsInRange(
 
 	// Return the IDs.
 	var eventID string
+	var token types.TopologyToken
+	var tokens []types.TopologyToken
 	for rows.Next() {
-		if err = rows.Scan(&eventID); err != nil {
+		if err = rows.Scan(&eventID, &token.Depth, &token.PDUPosition); err != nil {
 			return
 		}
 		eventIDs = append(eventIDs, eventID)
+		tokens = append(tokens, token)
 	}
 
-	return eventIDs, rows.Err()
+	// The values are already ordered by SQL, so we can use them as is.
+	if len(tokens) > 0 {
+		start = tokens[0]
+		end = tokens[len(tokens)-1]
+	}
+
+	return eventIDs, start, end, rows.Err()
 }
 
 // SelectPositionInTopology returns the position of a given event in the
diff --git a/syncapi/storage/shared/storage_sync.go b/syncapi/storage/shared/storage_sync.go
index 8e79b71d..cd17fdc6 100644
--- a/syncapi/storage/shared/storage_sync.go
+++ b/syncapi/storage/shared/storage_sync.go
@@ -237,7 +237,7 @@ func (d *DatabaseTransaction) GetEventsInTopologicalRange(
 	roomID string,
 	filter *synctypes.RoomEventFilter,
 	backwardOrdering bool,
-) (events []types.StreamEvent, err error) {
+) (events []types.StreamEvent, start, end types.TopologyToken, err error) {
 	var minDepth, maxDepth, maxStreamPosForMaxDepth types.StreamPosition
 	if backwardOrdering {
 		// Backward ordering means the 'from' token has a higher depth than the 'to' token
@@ -255,7 +255,7 @@ func (d *DatabaseTransaction) GetEventsInTopologicalRange(
 
 	// Select the event IDs from the defined range.
 	var eIDs []string
-	eIDs, err = d.Topology.SelectEventIDsInRange(
+	eIDs, start, end, err = d.Topology.SelectEventIDsInRange(
 		ctx, d.txn, roomID, minDepth, maxDepth, maxStreamPosForMaxDepth, filter.Limit, !backwardOrdering,
 	)
 	if err != nil {
@@ -264,6 +264,10 @@ func (d *DatabaseTransaction) GetEventsInTopologicalRange(
 
 	// Retrieve the events' contents using their IDs.
 	events, err = d.OutputEvents.SelectEvents(ctx, d.txn, eIDs, filter, true)
+	if err != nil {
+		return
+	}
+
 	return
 }
 
diff --git a/syncapi/storage/sqlite3/output_room_events_topology_table.go b/syncapi/storage/sqlite3/output_room_events_topology_table.go
index 68b75f5b..614e1df9 100644
--- a/syncapi/storage/sqlite3/output_room_events_topology_table.go
+++ b/syncapi/storage/sqlite3/output_room_events_topology_table.go
@@ -44,14 +44,14 @@ const insertEventInTopologySQL = "" +
 	" ON CONFLICT DO NOTHING"
 
 const selectEventIDsInRangeASCSQL = "" +
-	"SELECT event_id FROM syncapi_output_room_events_topology" +
+	"SELECT event_id, topological_position, stream_position FROM syncapi_output_room_events_topology" +
 	" WHERE room_id = $1 AND (" +
 	"(topological_position > $2 AND topological_position < $3) OR" +
 	"(topological_position = $4 AND stream_position >= $5)" +
 	") ORDER BY topological_position ASC, stream_position ASC LIMIT $6"
 
 const selectEventIDsInRangeDESCSQL = "" +
-	"SELECT event_id  FROM syncapi_output_room_events_topology" +
+	"SELECT event_id, topological_position, stream_position FROM syncapi_output_room_events_topology" +
 	" WHERE room_id = $1 AND (" +
 	"(topological_position > $2 AND topological_position < $3) OR" +
 	"(topological_position = $4 AND stream_position <= $5)" +
@@ -111,11 +111,15 @@ func (s *outputRoomEventsTopologyStatements) InsertEventInTopology(
 	return types.StreamPosition(event.Depth()), err
 }
 
+// SelectEventIDsInRange selects the IDs of events which positions are within a
+// given range in a given room's topological order. Returns the start/end topological tokens for
+// the returned eventIDs.
+// Returns an empty slice if no events match the given range.
 func (s *outputRoomEventsTopologyStatements) SelectEventIDsInRange(
 	ctx context.Context, txn *sql.Tx, roomID string,
 	minDepth, maxDepth, maxStreamPos types.StreamPosition,
 	limit int, chronologicalOrder bool,
-) (eventIDs []string, err error) {
+) (eventIDs []string, start, end types.TopologyToken, err error) {
 	// Decide on the selection's order according to whether chronological order
 	// is requested or not.
 	var stmt *sql.Stmt
@@ -129,18 +133,27 @@ func (s *outputRoomEventsTopologyStatements) SelectEventIDsInRange(
 	rows, err := stmt.QueryContext(ctx, roomID, minDepth, maxDepth, maxDepth, maxStreamPos, limit)
 	if err == sql.ErrNoRows {
 		// If no event matched the request, return an empty slice.
-		return []string{}, nil
+		return []string{}, start, end, nil
 	} else if err != nil {
 		return
 	}
 
 	// Return the IDs.
 	var eventID string
+	var token types.TopologyToken
+	var tokens []types.TopologyToken
 	for rows.Next() {
-		if err = rows.Scan(&eventID); err != nil {
+		if err = rows.Scan(&eventID, &token.Depth, &token.PDUPosition); err != nil {
 			return
 		}
 		eventIDs = append(eventIDs, eventID)
+		tokens = append(tokens, token)
+	}
+
+	// The values are already ordered by SQL, so we can use them as is.
+	if len(tokens) > 0 {
+		start = tokens[0]
+		end = tokens[len(tokens)-1]
 	}
 
 	return
diff --git a/syncapi/storage/storage_test.go b/syncapi/storage/storage_test.go
index f57b0d61..ce7ca3fc 100644
--- a/syncapi/storage/storage_test.go
+++ b/syncapi/storage/storage_test.go
@@ -213,12 +213,48 @@ func TestGetEventsInRangeWithTopologyToken(t *testing.T) {
 
 			// backpaginate 5 messages starting at the latest position.
 			filter := &synctypes.RoomEventFilter{Limit: 5}
-			paginatedEvents, err := snapshot.GetEventsInTopologicalRange(ctx, &from, &to, r.ID, filter, true)
+			paginatedEvents, start, end, err := snapshot.GetEventsInTopologicalRange(ctx, &from, &to, r.ID, filter, true)
 			if err != nil {
 				t.Fatalf("GetEventsInTopologicalRange returned an error: %s", err)
 			}
 			gots := snapshot.StreamEventsToEvents(context.Background(), nil, paginatedEvents, nil)
 			test.AssertEventsEqual(t, gots, test.Reversed(events[len(events)-5:]))
+			assert.Equal(t, types.TopologyToken{Depth: 15, PDUPosition: 15}, start)
+			assert.Equal(t, types.TopologyToken{Depth: 11, PDUPosition: 11}, end)
+		})
+	})
+}
+
+// The purpose of this test is to ensure that backfilling returns no start/end if a given filter removes
+// all events.
+func TestGetEventsInRangeWithTopologyTokenNoEventsForFilter(t *testing.T) {
+	test.WithAllDatabases(t, func(t *testing.T, dbType test.DBType) {
+		db, close := MustCreateDatabase(t, dbType)
+		defer close()
+		alice := test.NewUser(t)
+		r := test.NewRoom(t, alice)
+		for i := 0; i < 10; i++ {
+			r.CreateAndInsert(t, alice, "m.room.message", map[string]interface{}{"body": fmt.Sprintf("hi %d", i)})
+		}
+		events := r.Events()
+		_ = MustWriteEvents(t, db, events)
+
+		WithSnapshot(t, db, func(snapshot storage.DatabaseTransaction) {
+			from := types.TopologyToken{Depth: math.MaxInt64, PDUPosition: math.MaxInt64}
+			t.Logf("max topo pos = %+v", from)
+			// head towards the beginning of time
+			to := types.TopologyToken{}
+
+			// backpaginate 20 messages starting at the latest position.
+			notTypes := []string{spec.MRoomRedaction}
+			senders := []string{alice.ID}
+			filter := &synctypes.RoomEventFilter{Limit: 20, NotTypes: &notTypes, Senders: &senders}
+			paginatedEvents, start, end, err := snapshot.GetEventsInTopologicalRange(ctx, &from, &to, r.ID, filter, true)
+			assert.NoError(t, err)
+			assert.Equal(t, 0, len(paginatedEvents))
+			// Even if we didn't get anything back due to the filter, we should still have start/end
+			assert.Equal(t, types.TopologyToken{Depth: 15, PDUPosition: 15}, start)
+			assert.Equal(t, types.TopologyToken{Depth: 1, PDUPosition: 1}, end)
 		})
 	})
 }
diff --git a/syncapi/storage/tables/interface.go b/syncapi/storage/tables/interface.go
index 854292bd..f5c66c42 100644
--- a/syncapi/storage/tables/interface.go
+++ b/syncapi/storage/tables/interface.go
@@ -89,11 +89,11 @@ type Topology interface {
 	// InsertEventInTopology inserts the given event in the room's topology, based on the event's depth.
 	// `pos` is the stream position of this event in the events table, and is used to order events which have the same depth.
 	InsertEventInTopology(ctx context.Context, txn *sql.Tx, event *rstypes.HeaderedEvent, pos types.StreamPosition) (topoPos types.StreamPosition, err error)
-	// SelectEventIDsInRange selects the IDs of events whose depths are within a given range in a given room's topological order.
-	// Events with `minDepth` are *exclusive*, as is the event which has exactly `minDepth`,`maxStreamPos`.
+	// SelectEventIDsInRange selects the IDs and the topological position of events whose depths are within a given range in a given room's topological order.
+	// Events with `minDepth` are *exclusive*, as is the event which has exactly `minDepth`,`maxStreamPos`. Returns the eventIDs and start/end topological tokens.
 	// `maxStreamPos` is only used when events have the same depth as `maxDepth`, which results in events less than `maxStreamPos` being returned.
 	// Returns an empty slice if no events match the given range.
-	SelectEventIDsInRange(ctx context.Context, txn *sql.Tx, roomID string, minDepth, maxDepth, maxStreamPos types.StreamPosition, limit int, chronologicalOrder bool) (eventIDs []string, err error)
+	SelectEventIDsInRange(ctx context.Context, txn *sql.Tx, roomID string, minDepth, maxDepth, maxStreamPos types.StreamPosition, limit int, chronologicalOrder bool) (eventIDs []string, start, end types.TopologyToken, err error)
 	// SelectPositionInTopology returns the depth and stream position of a given event in the topology of the room it belongs to.
 	SelectPositionInTopology(ctx context.Context, txn *sql.Tx, eventID string) (depth, spos types.StreamPosition, err error)
 	// SelectStreamToTopologicalPosition converts a stream position to a topological position by finding the nearest topological position in the room.
diff --git a/syncapi/storage/tables/topology_test.go b/syncapi/storage/tables/topology_test.go
index f4f75bdf..7691cc5f 100644
--- a/syncapi/storage/tables/topology_test.go
+++ b/syncapi/storage/tables/topology_test.go
@@ -13,6 +13,7 @@ import (
 	"github.com/matrix-org/dendrite/syncapi/storage/tables"
 	"github.com/matrix-org/dendrite/syncapi/types"
 	"github.com/matrix-org/dendrite/test"
+	"github.com/stretchr/testify/assert"
 )
 
 func newTopologyTable(t *testing.T, dbType test.DBType) (tables.Topology, *sql.DB, func()) {
@@ -60,28 +61,37 @@ func TestTopologyTable(t *testing.T) {
 				highestPos = topoPos + 1
 			}
 			// check ordering works without limit
-			eventIDs, err := tab.SelectEventIDsInRange(ctx, txn, room.ID, 0, highestPos, highestPos, 100, true)
-			if err != nil {
-				return fmt.Errorf("failed to SelectEventIDsInRange: %s", err)
-			}
+			eventIDs, start, end, err := tab.SelectEventIDsInRange(ctx, txn, room.ID, 0, highestPos, highestPos, 100, true)
+			assert.NoError(t, err, "failed to SelectEventIDsInRange")
 			test.AssertEventIDsEqual(t, eventIDs, events[:])
-			eventIDs, err = tab.SelectEventIDsInRange(ctx, txn, room.ID, 0, highestPos, highestPos, 100, false)
-			if err != nil {
-				return fmt.Errorf("failed to SelectEventIDsInRange: %s", err)
-			}
+			assert.Equal(t, types.TopologyToken{Depth: 1, PDUPosition: 0}, start)
+			assert.Equal(t, types.TopologyToken{Depth: 5, PDUPosition: 4}, end)
+
+			eventIDs, start, end, err = tab.SelectEventIDsInRange(ctx, txn, room.ID, 0, highestPos, highestPos, 100, false)
+			assert.NoError(t, err, "failed to SelectEventIDsInRange")
 			test.AssertEventIDsEqual(t, eventIDs, test.Reversed(events[:]))
+			assert.Equal(t, types.TopologyToken{Depth: 5, PDUPosition: 4}, start)
+			assert.Equal(t, types.TopologyToken{Depth: 1, PDUPosition: 0}, end)
+
 			// check ordering works with limit
-			eventIDs, err = tab.SelectEventIDsInRange(ctx, txn, room.ID, 0, highestPos, highestPos, 3, true)
-			if err != nil {
-				return fmt.Errorf("failed to SelectEventIDsInRange: %s", err)
-			}
+			eventIDs, start, end, err = tab.SelectEventIDsInRange(ctx, txn, room.ID, 0, highestPos, highestPos, 3, true)
+			assert.NoError(t, err, "failed to SelectEventIDsInRange")
 			test.AssertEventIDsEqual(t, eventIDs, events[:3])
-			eventIDs, err = tab.SelectEventIDsInRange(ctx, txn, room.ID, 0, highestPos, highestPos, 3, false)
-			if err != nil {
-				return fmt.Errorf("failed to SelectEventIDsInRange: %s", err)
-			}
+			assert.Equal(t, types.TopologyToken{Depth: 1, PDUPosition: 0}, start)
+			assert.Equal(t, types.TopologyToken{Depth: 3, PDUPosition: 2}, end)
+
+			eventIDs, start, end, err = tab.SelectEventIDsInRange(ctx, txn, room.ID, 0, highestPos, highestPos, 3, false)
+			assert.NoError(t, err, "failed to SelectEventIDsInRange")
 			test.AssertEventIDsEqual(t, eventIDs, test.Reversed(events[len(events)-3:]))
+			assert.Equal(t, types.TopologyToken{Depth: 5, PDUPosition: 4}, start)
+			assert.Equal(t, types.TopologyToken{Depth: 3, PDUPosition: 2}, end)
 
+			// Check that we return no values for invalid rooms
+			eventIDs, start, end, err = tab.SelectEventIDsInRange(ctx, txn, "!doesnotexist:localhost", 0, highestPos, highestPos, 10, false)
+			assert.NoError(t, err, "failed to SelectEventIDsInRange")
+			assert.Equal(t, 0, len(eventIDs))
+			assert.Equal(t, types.TopologyToken{}, start)
+			assert.Equal(t, types.TopologyToken{}, end)
 			return nil
 		})
 		if err != nil {
diff --git a/syncapi/syncapi.go b/syncapi/syncapi.go
index 64a4af75..af6bddc7 100644
--- a/syncapi/syncapi.go
+++ b/syncapi/syncapi.go
@@ -144,8 +144,11 @@ func AddPublicRoutes(
 		logrus.WithError(err).Panicf("failed to start receipts consumer")
 	}
 
+	rateLimits := httputil.NewRateLimits(&dendriteCfg.ClientAPI.RateLimiting)
+
 	routing.Setup(
 		routers.Client, requestPool, syncDB, userAPI,
 		rsAPI, &dendriteCfg.SyncAPI, caches, fts,
+		rateLimits,
 	)
 }
diff --git a/syncapi/syncapi_test.go b/syncapi/syncapi_test.go
index 19815b79..996b21e9 100644
--- a/syncapi/syncapi_test.go
+++ b/syncapi/syncapi_test.go
@@ -433,6 +433,7 @@ func testHistoryVisibility(t *testing.T, dbType test.DBType) {
 		}
 
 		cfg, processCtx, close := testrig.CreateConfig(t, dbType)
+		cfg.ClientAPI.RateLimiting = config.RateLimiting{Enabled: false}
 		routers := httputil.NewRouters()
 		cm := sqlutil.NewConnectionManager(processCtx, cfg.Global.DatabaseOptions)
 		caches := caching.NewRistrettoCache(128*1024*1024, time.Hour, caching.DisableMetrics)