Merge branch 'master' into neilalexander/localtracking

build-dendritejs.sh

@@ -0,0 +1,4 @@
+#!/bin/bash -eu
+
+export GIT_COMMIT=$(git rev-list -1 HEAD) && \
+GOOS=js GOARCH=wasm go build -ldflags "-X main.GitCommit=$GIT_COMMIT" -o main.wasm ./cmd/dendritejs

cmd/dendritejs/main.go

@@ -20,6 +20,7 @@ import (
 	"crypto/ed25519"
 	"fmt"
 	"net/http"
+	"syscall/js"
 
 	"github.com/matrix-org/dendrite/appservice"
 	"github.com/matrix-org/dendrite/clientapi"
@@ -45,15 +46,95 @@ import (
 	_ "github.com/matrix-org/go-sqlite3-js"
 )
 
+var GitCommit string
+
 func init() {
-	fmt.Println("dendrite.js starting...")
+	fmt.Printf("[%s] dendrite.js starting...\n", GitCommit)
+}
+
+const keyNameEd25519 = "_go_ed25519_key"
+
+func readKeyFromLocalStorage() (key ed25519.PrivateKey, err error) {
+	localforage := js.Global().Get("localforage")
+	if !localforage.Truthy() {
+		err = fmt.Errorf("readKeyFromLocalStorage: no localforage")
+		return
+	}
+	// https://localforage.github.io/localForage/
+	item, ok := await(localforage.Call("getItem", keyNameEd25519))
+	if !ok || !item.Truthy() {
+		err = fmt.Errorf("readKeyFromLocalStorage: no key in localforage")
+		return
+	}
+	fmt.Println("Found key in localforage")
+	// extract []byte and make an ed25519 key
+	seed := make([]byte, 32, 32)
+	js.CopyBytesToGo(seed, item)
+
+	return ed25519.NewKeyFromSeed(seed), nil
+}
+
+func writeKeyToLocalStorage(key ed25519.PrivateKey) error {
+	localforage := js.Global().Get("localforage")
+	if !localforage.Truthy() {
+		return fmt.Errorf("writeKeyToLocalStorage: no localforage")
+	}
+
+	// make a Uint8Array from the key's seed
+	seed := key.Seed()
+	jsSeed := js.Global().Get("Uint8Array").New(len(seed))
+	js.CopyBytesToJS(jsSeed, seed)
+	// write it
+	localforage.Call("setItem", keyNameEd25519, jsSeed)
+	return nil
+}
+
+// taken from https://go-review.googlesource.com/c/go/+/150917
+
+// await waits until the promise v has been resolved or rejected and returns the promise's result value.
+// The boolean value ok is true if the promise has been resolved, false if it has been rejected.
+// If v is not a promise, v itself is returned as the value and ok is true.
+func await(v js.Value) (result js.Value, ok bool) {
+	if v.Type() != js.TypeObject || v.Get("then").Type() != js.TypeFunction {
+		return v, true
+	}
+	done := make(chan struct{})
+	onResolve := js.FuncOf(func(this js.Value, args []js.Value) interface{} {
+		result = args[0]
+		ok = true
+		close(done)
+		return nil
+	})
+	defer onResolve.Release()
+	onReject := js.FuncOf(func(this js.Value, args []js.Value) interface{} {
+		result = args[0]
+		ok = false
+		close(done)
+		return nil
+	})
+	defer onReject.Release()
+	v.Call("then", onResolve, onReject)
+	<-done
+	return
 }
 
 func generateKey() ed25519.PrivateKey {
-	_, priv, err := ed25519.GenerateKey(nil)
+	// attempt to look for a seed in JS-land and if it exists use it.
+	priv, err := readKeyFromLocalStorage()
+	if err == nil {
+		fmt.Println("Read key from localStorage")
+		return priv
+	}
+	// generate a new key
+	fmt.Println(err, " : Generating new ed25519 key")
+	_, priv, err = ed25519.GenerateKey(nil)
 	if err != nil {
 		logrus.Fatalf("Failed to generate ed25519 key: %s", err)
 	}
+	if err := writeKeyToLocalStorage(priv); err != nil {
+		fmt.Println("failed to write key to localStorage: ", err)
+		// non-fatal, we'll just have amnesia for a while
+	}
 	return priv
 }
 

federationapi/routing/backfill.go

@@ -69,9 +69,14 @@ func Backfill(
 
 	// Populate the request.
 	req := api.QueryBackfillRequest{
-		RoomID:            roomID,
-		EarliestEventsIDs: eIDs,
-		ServerName:        request.Origin(),
+		RoomID: roomID,
+		// we don't know who the successors are for these events, which won't
+		// be a problem because we don't use that information when servicing /backfill requests,
+		// only when making them. TODO: Think of a better API shape
+		BackwardsExtremities: map[string][]string{
+			"": eIDs,
+		},
+		ServerName: request.Origin(),
 	}
 	if req.Limit, err = strconv.Atoi(limit); err != nil {
 		util.GetLogger(httpReq.Context()).WithError(err).Error("strconv.Atoi failed")
@@ -97,7 +102,7 @@ func Backfill(
 		}
 	}
 
-	var eventJSONs []json.RawMessage
+	eventJSONs := []json.RawMessage{}
 	for _, e := range gomatrixserverlib.ReverseTopologicalOrdering(
 		evs,
 		gomatrixserverlib.TopologicalOrderByPrevEvents,
@@ -105,6 +110,12 @@ func Backfill(
 		eventJSONs = append(eventJSONs, e.JSON())
 	}
 
+	// sytest wants these in reversed order, similar to /messages, so reverse them now.
+	for i := len(eventJSONs)/2 - 1; i >= 0; i-- {
+		opp := len(eventJSONs) - 1 - i
+		eventJSONs[i], eventJSONs[opp] = eventJSONs[opp], eventJSONs[i]
+	}
+
 	txn := gomatrixserverlib.Transaction{
 		Origin:         cfg.Matrix.ServerName,
 		PDUs:           eventJSONs,

roomserver/api/query.go

@@ -21,6 +21,7 @@ import (
 
 	commonHTTP "github.com/matrix-org/dendrite/common/http"
 	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/util"
 	opentracing "github.com/opentracing/opentracing-go"
 )
 
@@ -228,14 +229,24 @@ type QueryStateAndAuthChainResponse struct {
 type QueryBackfillRequest struct {
 	// The room to backfill
 	RoomID string `json:"room_id"`
-	// Events to start paginating from.
-	EarliestEventsIDs []string `json:"earliest_event_ids"`
+	// A map of backwards extremity event ID to a list of its prev_event IDs.
+	BackwardsExtremities map[string][]string `json:"backwards_extremities"`
 	// The maximum number of events to retrieve.
 	Limit int `json:"limit"`
 	// The server interested in the events.
 	ServerName gomatrixserverlib.ServerName `json:"server_name"`
 }
 
+// PrevEventIDs returns the prev_event IDs of all backwards extremities, de-duplicated in a lexicographically sorted order.
+func (r *QueryBackfillRequest) PrevEventIDs() []string {
+	var prevEventIDs []string
+	for _, pes := range r.BackwardsExtremities {
+		prevEventIDs = append(prevEventIDs, pes...)
+	}
+	prevEventIDs = util.UniqueStrings(prevEventIDs)
+	return prevEventIDs
+}
+
 // QueryBackfillResponse is a response to QueryBackfill.
 type QueryBackfillResponse struct {
 	// Missing events, arbritrary order.

roomserver/internal/query.go

@@ -495,14 +495,8 @@ func (r *RoomserverInternalAPI) QueryBackfill(
 	// defines the highest number of elements in the map below.
 	visited := make(map[string]bool, request.Limit)
 
-	// The provided event IDs have already been seen by the request's emitter,
-	// and will be retrieved anyway, so there's no need to care about them if
-	// they appear in our exploration of the event tree.
-	for _, id := range request.EarliestEventsIDs {
-		visited[id] = true
-	}
-
-	front = request.EarliestEventsIDs
+	// this will include these events which is what we want
+	front = request.PrevEventIDs()
 
 	// Scan the event tree for events to send back.
 	resultNIDs, err := r.scanEventTree(ctx, front, visited, request.Limit, request.ServerName)
@@ -534,10 +528,15 @@ func (r *RoomserverInternalAPI) backfillViaFederation(ctx context.Context, req *
 	if err != nil {
 		return fmt.Errorf("backfillViaFederation: unknown room version for room %s : %w", req.RoomID, err)
 	}
-	requester := newBackfillRequester(r.DB, r.FedClient, r.ServerName)
+	requester := newBackfillRequester(r.DB, r.FedClient, r.ServerName, req.BackwardsExtremities)
+	// Request 100 items regardless of what the query asks for.
+	// We don't want to go much higher than this.
+	// We can't honour exactly the limit as some sytests rely on requesting more for tests to pass
+	// (so we don't need to hit /state_ids which the test has no listener for)
+	// Specifically the test "Outbound federation can backfill events"
 	events, err := gomatrixserverlib.RequestBackfill(
 		ctx, requester,
-		r.KeyRing, req.RoomID, roomVer, req.EarliestEventsIDs, req.Limit)
+		r.KeyRing, req.RoomID, roomVer, req.PrevEventIDs(), 100)
 	if err != nil {
 		return err
 	}

roomserver/internal/query_backfill.go

@@ -7,6 +7,7 @@ import (
 	"github.com/matrix-org/dendrite/roomserver/storage"
 	"github.com/matrix-org/dendrite/roomserver/types"
 	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/util"
 	"github.com/sirupsen/logrus"
 )
 
@@ -15,6 +16,7 @@ type backfillRequester struct {
 	db         storage.Database
 	fedClient  *gomatrixserverlib.FederationClient
 	thisServer gomatrixserverlib.ServerName
+	bwExtrems  map[string][]string
 
 	// per-request state
 	servers                 []gomatrixserverlib.ServerName
@@ -22,13 +24,14 @@ type backfillRequester struct {
 	eventIDMap              map[string]gomatrixserverlib.Event
 }
 
-func newBackfillRequester(db storage.Database, fedClient *gomatrixserverlib.FederationClient, thisServer gomatrixserverlib.ServerName) *backfillRequester {
+func newBackfillRequester(db storage.Database, fedClient *gomatrixserverlib.FederationClient, thisServer gomatrixserverlib.ServerName, bwExtrems map[string][]string) *backfillRequester {
 	return &backfillRequester{
 		db:                      db,
 		fedClient:               fedClient,
 		thisServer:              thisServer,
 		eventIDToBeforeStateIDs: make(map[string][]string),
 		eventIDMap:              make(map[string]gomatrixserverlib.Event),
+		bwExtrems:               bwExtrems,
 	}
 }
 
@@ -37,6 +40,11 @@ func (b *backfillRequester) StateIDsBeforeEvent(ctx context.Context, targetEvent
 	if ids, ok := b.eventIDToBeforeStateIDs[targetEvent.EventID()]; ok {
 		return ids, nil
 	}
+	if len(targetEvent.PrevEventIDs()) == 0 && targetEvent.Type() == "m.room.create" && targetEvent.StateKeyEquals("") {
+		util.GetLogger(ctx).WithField("room_id", targetEvent.RoomID()).Info("Backfilled to the beginning of the room")
+		b.eventIDToBeforeStateIDs[targetEvent.EventID()] = []string{}
+		return nil, nil
+	}
 	// if we have exactly 1 prev event and we know the state of the room at that prev event, then just roll forward the prev event.
 	// Else, we have to hit /state_ids because either we don't know the state at all at this event (new backwards extremity) or
 	// we don't know the result of state res to merge forks (2 or more prev_events)
@@ -154,26 +162,44 @@ func (b *backfillRequester) StateBeforeEvent(ctx context.Context, roomVer gomatr
 // It returns a list of servers which can be queried for backfill requests. These servers
 // will be servers that are in the room already. The entries at the beginning are preferred servers
 // and will be tried first. An empty list will fail the request.
-func (b *backfillRequester) ServersAtEvent(ctx context.Context, roomID, eventID string) (servers []gomatrixserverlib.ServerName) {
+func (b *backfillRequester) ServersAtEvent(ctx context.Context, roomID, eventID string) []gomatrixserverlib.ServerName {
+	// eventID will be a prev_event ID of a backwards extremity, meaning we will not have a database entry for it. Instead, use
+	// its successor, so look it up.
+	successor := ""
+FindSuccessor:
+	for sucID, prevEventIDs := range b.bwExtrems {
+		for _, pe := range prevEventIDs {
+			if pe == eventID {
+				successor = sucID
+				break FindSuccessor
+			}
+		}
+	}
+	if successor == "" {
+		logrus.WithField("event_id", eventID).Error("ServersAtEvent: failed to find successor of this event to determine room state")
+		return nil
+	}
+	eventID = successor
+
 	// getMembershipsBeforeEventNID requires a NID, so retrieving the NID for
 	// the event is necessary.
 	NIDs, err := b.db.EventNIDs(ctx, []string{eventID})
 	if err != nil {
 		logrus.WithField("event_id", eventID).WithError(err).Error("ServersAtEvent: failed to get event NID for event")
-		return
+		return nil
 	}
 
 	stateEntries, err := stateBeforeEvent(ctx, b.db, NIDs[eventID])
 	if err != nil {
 		logrus.WithField("event_id", eventID).WithError(err).Error("ServersAtEvent: failed to load state before event")
-		return
+		return nil
 	}
 
 	// possibly return all joined servers depending on history visiblity
 	memberEventsFromVis, err := joinEventsFromHistoryVisibility(ctx, b.db, roomID, stateEntries)
 	if err != nil {
 		logrus.WithError(err).Error("ServersAtEvent: failed calculate servers from history visibility rules")
-		return
+		return nil
 	}
 	logrus.Infof("ServersAtEvent including %d current events from history visibility", len(memberEventsFromVis))
 
@@ -183,7 +209,7 @@ func (b *backfillRequester) ServersAtEvent(ctx context.Context, roomID, eventID
 	memberEvents, err := getMembershipsAtState(ctx, b.db, stateEntries, true)
 	if err != nil {
 		logrus.WithField("event_id", eventID).WithError(err).Error("ServersAtEvent: failed to get memberships before event")
-		return
+		return nil
 	}
 	memberEvents = append(memberEvents, memberEventsFromVis...)
 
@@ -192,6 +218,7 @@ func (b *backfillRequester) ServersAtEvent(ctx context.Context, roomID, eventID
 	for _, event := range memberEvents {
 		serverSet[event.Origin()] = true
 	}
+	var servers []gomatrixserverlib.ServerName
 	for server := range serverSet {
 		if server == b.thisServer {
 			continue
@@ -199,7 +226,7 @@ func (b *backfillRequester) ServersAtEvent(ctx context.Context, roomID, eventID
 		servers = append(servers, server)
 	}
 	b.servers = servers
-	return
+	return servers
 }
 
 // Backfill performs a backfill request to the given server.

syncapi/routing/messages.go

@@ -205,6 +205,7 @@ func (r *messagesReq) retrieveEvents() (
 	}
 
 	var events []gomatrixserverlib.HeaderedEvent
+	util.GetLogger(r.ctx).WithField("start", start).WithField("end", end).Infof("Fetched %d events locally", len(streamEvents))
 
 	// There can be two reasons for streamEvents to be empty: either we've
 	// reached the oldest event in the room (or the most recent one, depending
@@ -373,13 +374,13 @@ func (e eventsByDepth) Less(i, j int) bool {
 // event, or if there is no remote homeserver to contact.
 // Returns an error if there was an issue with retrieving the list of servers in
 // the room or sending the request.
-func (r *messagesReq) backfill(roomID string, fromEventIDs []string, limit int) ([]gomatrixserverlib.HeaderedEvent, error) {
+func (r *messagesReq) backfill(roomID string, backwardsExtremities map[string][]string, limit int) ([]gomatrixserverlib.HeaderedEvent, error) {
 	var res api.QueryBackfillResponse
 	err := r.rsAPI.QueryBackfill(context.Background(), &api.QueryBackfillRequest{
-		RoomID:            roomID,
-		EarliestEventsIDs: fromEventIDs,
-		Limit:             limit,
-		ServerName:        r.cfg.Matrix.ServerName,
+		RoomID:               roomID,
+		BackwardsExtremities: backwardsExtremities,
+		Limit:                limit,
+		ServerName:           r.cfg.Matrix.ServerName,
 	}, &res)
 	if err != nil {
 		return nil, fmt.Errorf("QueryBackfill failed: %w", err)
@@ -412,7 +413,14 @@ func (r *messagesReq) backfill(roomID string, fromEventIDs []string, limit int)
 		}
 	}
 
-	return res.Events, nil
+	// 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:]
+	}
+
+	return events, nil
 }
 
 // setToDefault returns the default value for the "to" query parameter of a

syncapi/storage/interface.go

@@ -94,9 +94,8 @@ type Database interface {
 	GetEventsInTopologicalRange(ctx context.Context, from, to *types.TopologyToken, roomID string, limit int, backwardOrdering bool) (events []types.StreamEvent, err error)
 	// EventPositionInTopology returns the depth and stream position of the given event.
 	EventPositionInTopology(ctx context.Context, eventID string) (types.TopologyToken, error)
-	// BackwardExtremitiesForRoom returns the event IDs of all of the backward
-	// extremities we know of for a given room.
-	BackwardExtremitiesForRoom(ctx context.Context, roomID string) (backwardExtremities []string, err error)
+	// BackwardExtremitiesForRoom returns a map of backwards extremity event ID to a list of its prev_events.
+	BackwardExtremitiesForRoom(ctx context.Context, roomID string) (backwardExtremities map[string][]string, err error)
 	// MaxTopologicalPosition returns the highest topological position for a given room.
 	MaxTopologicalPosition(ctx context.Context, roomID string) (types.TopologyToken, error)
 	// StreamEventsToEvents converts streamEvent to Event. If device is non-nil and

syncapi/storage/postgres/backwards_extremities_table.go

@@ -41,7 +41,7 @@ const insertBackwardExtremitySQL = "" +
 	" ON CONFLICT DO NOTHING"
 
 const selectBackwardExtremitiesForRoomSQL = "" +
-	"SELECT DISTINCT event_id FROM syncapi_backward_extremities WHERE room_id = $1"
+	"SELECT event_id, prev_event_id FROM syncapi_backward_extremities WHERE room_id = $1"
 
 const deleteBackwardExtremitySQL = "" +
 	"DELETE FROM syncapi_backward_extremities WHERE room_id = $1 AND prev_event_id = $2"
@@ -79,23 +79,24 @@ func (s *backwardExtremitiesStatements) InsertsBackwardExtremity(
 
 func (s *backwardExtremitiesStatements) SelectBackwardExtremitiesForRoom(
 	ctx context.Context, roomID string,
-) (eventIDs []string, err error) {
+) (bwExtrems map[string][]string, err error) {
 	rows, err := s.selectBackwardExtremitiesForRoomStmt.QueryContext(ctx, roomID)
 	if err != nil {
 		return
 	}
 	defer common.CloseAndLogIfError(ctx, rows, "selectBackwardExtremitiesForRoom: rows.close() failed")
 
+	bwExtrems = make(map[string][]string)
 	for rows.Next() {
 		var eID string
-		if err = rows.Scan(&eID); err != nil {
+		var prevEventID string
+		if err = rows.Scan(&eID, &prevEventID); err != nil {
 			return
 		}
-
-		eventIDs = append(eventIDs, eID)
+		bwExtrems[eID] = append(bwExtrems[eID], prevEventID)
 	}
 
-	return eventIDs, rows.Err()
+	return bwExtrems, rows.Err()
 }
 
 func (s *backwardExtremitiesStatements) DeleteBackwardExtremity(

syncapi/storage/shared/syncserver.go

@@ -310,6 +310,7 @@ func (d *Database) updateRoomState(
 			}
 			membership = &value
 		}
+
 		if err := d.CurrentRoomState.UpsertRoomState(ctx, txn, event, membership, pduPosition); err != nil {
 			return err
 		}
@@ -367,7 +368,7 @@ func (d *Database) SyncPosition(ctx context.Context) (tok types.StreamingToken,
 
 func (d *Database) BackwardExtremitiesForRoom(
 	ctx context.Context, roomID string,
-) (backwardExtremities []string, err error) {
+) (backwardExtremities map[string][]string, err error) {
 	return d.BackwardExtremities.SelectBackwardExtremitiesForRoom(ctx, roomID)
 }
 

syncapi/storage/sqlite3/backwards_extremities_table.go

@@ -41,7 +41,7 @@ const insertBackwardExtremitySQL = "" +
 	" ON CONFLICT (room_id, event_id, prev_event_id) DO NOTHING"
 
 const selectBackwardExtremitiesForRoomSQL = "" +
-	"SELECT DISTINCT event_id FROM syncapi_backward_extremities WHERE room_id = $1"
+	"SELECT event_id, prev_event_id FROM syncapi_backward_extremities WHERE room_id = $1"
 
 const deleteBackwardExtremitySQL = "" +
 	"DELETE FROM syncapi_backward_extremities WHERE room_id = $1 AND prev_event_id = $2"
@@ -79,23 +79,24 @@ func (s *backwardExtremitiesStatements) InsertsBackwardExtremity(
 
 func (s *backwardExtremitiesStatements) SelectBackwardExtremitiesForRoom(
 	ctx context.Context, roomID string,
-) (eventIDs []string, err error) {
+) (bwExtrems map[string][]string, err error) {
 	rows, err := s.selectBackwardExtremitiesForRoomStmt.QueryContext(ctx, roomID)
 	if err != nil {
 		return
 	}
 	defer common.CloseAndLogIfError(ctx, rows, "selectBackwardExtremitiesForRoom: rows.close() failed")
 
+	bwExtrems = make(map[string][]string)
 	for rows.Next() {
 		var eID string
-		if err = rows.Scan(&eID); err != nil {
+		var prevEventID string
+		if err = rows.Scan(&eID, &prevEventID); err != nil {
 			return
 		}
-
-		eventIDs = append(eventIDs, eID)
+		bwExtrems[eID] = append(bwExtrems[eID], prevEventID)
 	}
 
-	return eventIDs, rows.Err()
+	return bwExtrems, rows.Err()
 }
 
 func (s *backwardExtremitiesStatements) DeleteBackwardExtremity(

syncapi/storage/tables/interface.go

@@ -89,8 +89,8 @@ type CurrentRoomState interface {
 type BackwardsExtremities interface {
 	// InsertsBackwardExtremity inserts a new backwards extremity.
 	InsertsBackwardExtremity(ctx context.Context, txn *sql.Tx, roomID, eventID string, prevEventID string) (err error)
-	// SelectBackwardExtremitiesForRoom retrieves all backwards extremities for the room.
-	SelectBackwardExtremitiesForRoom(ctx context.Context, roomID string) (eventIDs []string, err error)
+	// SelectBackwardExtremitiesForRoom retrieves all backwards extremities for the room, as a map of event_id to list of prev_event_ids.
+	SelectBackwardExtremitiesForRoom(ctx context.Context, roomID string) (bwExtrems map[string][]string, err error)
 	// DeleteBackwardExtremity removes a backwards extremity for a room, if one existed.
 	DeleteBackwardExtremity(ctx context.Context, txn *sql.Tx, roomID, knownEventID string) (err error)
 }

syncapi/sync/request.go

@@ -16,6 +16,7 @@ package sync
 
 import (
 	"context"
+	"encoding/json"
 	"net/http"
 	"strconv"
 	"time"
@@ -30,6 +31,14 @@ import (
 const defaultSyncTimeout = time.Duration(0)
 const defaultTimelineLimit = 20
 
+type filter struct {
+	Room struct {
+		Timeline struct {
+			Limit *int `json:"limit"`
+		} `json:"timeline"`
+	} `json:"room"`
+}
+
 // syncRequest represents a /sync request, with sensible defaults/sanity checks applied.
 type syncRequest struct {
 	ctx           context.Context
@@ -54,6 +63,17 @@ func newSyncRequest(req *http.Request, device authtypes.Device) (*syncRequest, e
 		}
 		since = &tok
 	}
+	timelineLimit := defaultTimelineLimit
+	// TODO: read from stored filters too
+	filterQuery := req.URL.Query().Get("filter")
+	if filterQuery != "" && filterQuery[0] == '{' {
+		// attempt to parse the timeline limit at least
+		var f filter
+		err := json.Unmarshal([]byte(filterQuery), &f)
+		if err == nil && f.Room.Timeline.Limit != nil {
+			timelineLimit = *f.Room.Timeline.Limit
+		}
+	}
 	// TODO: Additional query params: set_presence, filter
 	return &syncRequest{
 		ctx:           req.Context(),
@@ -61,7 +81,7 @@ func newSyncRequest(req *http.Request, device authtypes.Device) (*syncRequest, e
 		timeout:       timeout,
 		since:         since,
 		wantFullState: wantFullState,
-		limit:         defaultTimelineLimit, // TODO: read from filter
+		limit:         timelineLimit,
 		log:           util.GetLogger(req.Context()),
 	}, nil
 }

syncapi/sync/requestpool.go

@@ -59,6 +59,7 @@ func (rp *RequestPool) OnIncomingSyncRequest(req *http.Request, device *authtype
 		"userID":  userID,
 		"since":   syncReq.since,
 		"timeout": syncReq.timeout,
+		"limit":   syncReq.limit,
 	})
 
 	currPos := rp.notifier.CurrentPosition()

sytest-whitelist

@@ -279,3 +279,7 @@ Inbound federation can return missing events for invite visibility
 Inbound federation can get public room list
 An event which redacts itself should be ignored
 A pair of events which redact each other should be ignored
+Outbound federation can backfill events
+Inbound federation can backfill events
+Backfill checks the events requested belong to the room
+Backfilled events whose prev_events are in a different room do not allow cross-room back-pagination