Merge branch 'master' into neilalexander/apis

README.md

@@ -33,7 +33,7 @@ Then point your favourite Matrix client at `http://localhost:8008`. For full ins
 
 We use a script called Are We Synapse Yet which checks Sytest compliance rates. Sytest is a black-box homeserver
 test rig with around 900 tests. The script works out how many of these tests are passing on Dendrite and it
-updates with CI. As of July 2020 we're at around 48% CS API coverage and 50% Federation coverage, though check
+updates with CI. As of August 2020 we're at around 52% CS API coverage and 65% Federation coverage, though check
 CI for the latest numbers. In practice, this means you can communicate locally and via federation with Synapse
 servers such as matrix.org reasonably well. There's a long list of features that are not implemented, notably:
  - Receipts
@@ -42,7 +42,6 @@ servers such as matrix.org reasonably well. There's a long list of features that
  - User Directory
  - Presence
  - Guests
- - E2E keys and device lists
 
 We are prioritising features that will benefit single-user homeservers first (e.g Receipts, E2E) rather
 than features that massive deployments may be interested in (User Directory, OpenID, Guests, Admin APIs, AS API).
@@ -56,6 +55,7 @@ This means Dendrite supports amongst others:
  - Media APIs
  - Redaction
  - Tagging
+ - E2E keys and device lists
 
 
 # Contributing

are-we-synapse-yet.list

@@ -831,6 +831,7 @@ psh Trying to get push rules with unknown scope fails with 400
 psh Trying to get push rules with unknown template fails with 400 
 psh Trying to get push rules with unknown attribute fails with 400 
 psh Trying to get push rules with unknown rule_id fails with 404
+psh Rooms with names are correctly named in pushes
 v1s GET /initialSync with non-numeric 'limit' 
 v1s GET /events with non-numeric 'limit' 
 v1s GET /events with negative 'limit' 
@@ -839,7 +840,7 @@ ath Event size limits
 syn Check creating invalid filters returns 4xx 
 f,pre New federated private chats get full presence information (SYN-115) 
 pre Left room members do not cause problems for presence 
-crm Rooms can be created with an initial invite list (SYN-205) 
+crm Rooms can be created with an initial invite list (SYN-205) (1 subtests)
 typ Typing notifications don't leak 
 ban Non-present room members cannot ban others 
 psh Getting push rules doesn't corrupt the cache SYN-390 

currentstateserver/currentstateserver_test.go

@@ -29,7 +29,9 @@ import (
 	"github.com/Shopify/sarama"
 	"github.com/gorilla/mux"
 	"github.com/matrix-org/dendrite/currentstateserver/api"
+	"github.com/matrix-org/dendrite/currentstateserver/internal"
 	"github.com/matrix-org/dendrite/currentstateserver/inthttp"
+	"github.com/matrix-org/dendrite/currentstateserver/storage"
 	"github.com/matrix-org/dendrite/internal/config"
 	"github.com/matrix-org/dendrite/internal/httputil"
 	"github.com/matrix-org/dendrite/internal/sqlutil"
@@ -76,7 +78,24 @@ func init() {
 	}
 }
 
-func MustWriteOutputEvent(t *testing.T, producer sarama.SyncProducer, out *roomserverAPI.OutputNewRoomEvent) error {
+func waitForOffsetProcessed(t *testing.T, db storage.Database, offset int64) {
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+	for {
+		poffsets, err := db.PartitionOffsets(ctx, kafkaTopic)
+		if err != nil {
+			t.Fatalf("failed to PartitionOffsets: %s", err)
+		}
+		for _, partition := range poffsets {
+			if partition.Offset >= offset {
+				return
+			}
+		}
+		time.Sleep(50 * time.Millisecond)
+	}
+}
+
+func MustWriteOutputEvent(t *testing.T, producer sarama.SyncProducer, out *roomserverAPI.OutputNewRoomEvent) int64 {
 	value, err := json.Marshal(roomserverAPI.OutputEvent{
 		Type:         roomserverAPI.OutputTypeNewRoomEvent,
 		NewRoomEvent: out,
@@ -84,7 +103,7 @@ func MustWriteOutputEvent(t *testing.T, producer sarama.SyncProducer, out *rooms
 	if err != nil {
 		t.Fatalf("failed to marshal output event: %s", err)
 	}
-	_, _, err = producer.SendMessage(&sarama.ProducerMessage{
+	_, offset, err := producer.SendMessage(&sarama.ProducerMessage{
 		Topic: kafkaTopic,
 		Key:   sarama.StringEncoder(out.Event.RoomID()),
 		Value: sarama.ByteEncoder(value),
@@ -92,10 +111,10 @@ func MustWriteOutputEvent(t *testing.T, producer sarama.SyncProducer, out *rooms
 	if err != nil {
 		t.Fatalf("failed to send message: %s", err)
 	}
-	return nil
+	return offset
 }
 
-func MustMakeInternalAPI(t *testing.T) (api.CurrentStateInternalAPI, sarama.SyncProducer, func()) {
+func MustMakeInternalAPI(t *testing.T) (api.CurrentStateInternalAPI, storage.Database, sarama.SyncProducer, func()) {
 	cfg := &config.Dendrite{}
 	cfg.Defaults()
 	stateDBName := "test_state.db"
@@ -117,26 +136,28 @@ func MustMakeInternalAPI(t *testing.T) (api.CurrentStateInternalAPI, sarama.Sync
 	if err != nil {
 		t.Fatalf("Failed to create naffka consumer: %s", err)
 	}
-	return NewInternalAPI(&cfg.CurrentStateServer, naff), naff, func() {
+	stateAPI := NewInternalAPI(&cfg.CurrentStateServer, naff)
+	// type-cast to pull out the DB
+	stateAPIVal := stateAPI.(*internal.CurrentStateInternalAPI)
+	return stateAPI, stateAPIVal.DB, naff, func() {
 		os.Remove(naffkaDBName)
 		os.Remove(stateDBName)
 	}
 }
 
 func TestQueryCurrentState(t *testing.T) {
-	currStateAPI, producer, cancel := MustMakeInternalAPI(t)
+	currStateAPI, db, producer, cancel := MustMakeInternalAPI(t)
 	defer cancel()
 	plTuple := gomatrixserverlib.StateKeyTuple{
 		EventType: "m.room.power_levels",
 		StateKey:  "",
 	}
 	plEvent := testEvents[4]
-	MustWriteOutputEvent(t, producer, &roomserverAPI.OutputNewRoomEvent{
+	offset := MustWriteOutputEvent(t, producer, &roomserverAPI.OutputNewRoomEvent{
 		Event:             plEvent,
 		AddsStateEventIDs: []string{plEvent.EventID()},
 	})
-	// we have no good way to know /when/ the server has consumed the event
+	waitForOffsetProcessed(t, db, offset)
-	time.Sleep(100 * time.Millisecond)
 
 	testCases := []struct {
 		req     api.QueryCurrentStateRequest
@@ -228,7 +249,7 @@ func mustMakeMembershipEvent(t *testing.T, roomID, userID, membership string) *r
 
 // This test makes sure that QuerySharedUsers is returning the correct users for a range of sets.
 func TestQuerySharedUsers(t *testing.T) {
-	currStateAPI, producer, cancel := MustMakeInternalAPI(t)
+	currStateAPI, db, producer, cancel := MustMakeInternalAPI(t)
 	defer cancel()
 	MustWriteOutputEvent(t, producer, mustMakeMembershipEvent(t, "!foo:bar", "@alice:localhost", "join"))
 	MustWriteOutputEvent(t, producer, mustMakeMembershipEvent(t, "!foo:bar", "@bob:localhost", "join"))
@@ -240,10 +261,8 @@ func TestQuerySharedUsers(t *testing.T) {
 	MustWriteOutputEvent(t, producer, mustMakeMembershipEvent(t, "!foo3:bar", "@bob:localhost", "join"))
 	MustWriteOutputEvent(t, producer, mustMakeMembershipEvent(t, "!foo3:bar", "@dave:localhost", "leave"))
 
-	MustWriteOutputEvent(t, producer, mustMakeMembershipEvent(t, "!foo4:bar", "@alice:localhost", "join"))
+	offset := MustWriteOutputEvent(t, producer, mustMakeMembershipEvent(t, "!foo4:bar", "@alice:localhost", "join"))
-
+	waitForOffsetProcessed(t, db, offset)
-	// we don't know when the server has processed the events
-	time.Sleep(10 * time.Millisecond)
 
 	testCases := []struct {
 		req     api.QuerySharedUsersRequest

keyserver/api/api.go

@@ -110,6 +110,11 @@ type OneTimeKeysCount struct {
 type PerformUploadKeysRequest struct {
 	DeviceKeys  []DeviceKeys
 	OneTimeKeys []OneTimeKeys
+	// OnlyDisplayNameUpdates should be `true` if ALL the DeviceKeys are present to update
+	// the display name for their respective device, and NOT to modify the keys. The key
+	// itself doesn't change but it's easier to pretend upload new keys and reuse the same code paths.
+	// Without this flag, requests to modify device display names would delete device keys.
+	OnlyDisplayNameUpdates bool
 }
 
 // PerformUploadKeysResponse is the response to PerformUploadKeys

keyserver/internal/device_list_update.go

@@ -67,6 +67,11 @@ type DeviceListUpdater struct {
 	producer    KeyChangeProducer
 	fedClient   *gomatrixserverlib.FederationClient
 	workerChans []chan gomatrixserverlib.ServerName
+
+	// When device lists are stale for a user, they get inserted into this map with a channel which `Update` will
+	// block on or timeout via a select.
+	userIDToChan   map[string]chan bool
+	userIDToChanMu *sync.Mutex
 }
 
 // DeviceListUpdaterDatabase is the subset of functionality from storage.Database required for the updater.
@@ -80,8 +85,9 @@ type DeviceListUpdaterDatabase interface {
 	MarkDeviceListStale(ctx context.Context, userID string, isStale bool) error
 
 	// StoreRemoteDeviceKeys persists the given keys. Keys with the same user ID and device ID will be replaced. An empty KeyJSON removes the key
-	// for this (user, device). Does not modify the stream ID for keys.
+	// for this (user, device). Does not modify the stream ID for keys. User IDs in `clearUserIDs` will have all their device keys deleted prior
-	StoreRemoteDeviceKeys(ctx context.Context, keys []api.DeviceMessage) error
+	// to insertion - use this when you have a complete snapshot of a user's keys in order to track device deletions correctly.
+	StoreRemoteDeviceKeys(ctx context.Context, keys []api.DeviceMessage, clearUserIDs []string) error
 
 	// PrevIDsExists returns true if all prev IDs exist for this user.
 	PrevIDsExists(ctx context.Context, userID string, prevIDs []int) (bool, error)
@@ -98,12 +104,14 @@ func NewDeviceListUpdater(
 	numWorkers int,
 ) *DeviceListUpdater {
 	return &DeviceListUpdater{
-		userIDToMutex: make(map[string]*sync.Mutex),
+		userIDToMutex:  make(map[string]*sync.Mutex),
-		mu:            &sync.Mutex{},
+		mu:             &sync.Mutex{},
-		db:            db,
+		db:             db,
-		producer:      producer,
+		producer:       producer,
-		fedClient:     fedClient,
+		fedClient:      fedClient,
-		workerChans:   make([]chan gomatrixserverlib.ServerName, numWorkers),
+		workerChans:    make([]chan gomatrixserverlib.ServerName, numWorkers),
+		userIDToChan:   make(map[string]chan bool),
+		userIDToChanMu: &sync.Mutex{},
 	}
 }
 
@@ -137,6 +145,22 @@ func (u *DeviceListUpdater) mutex(userID string) *sync.Mutex {
 	return u.userIDToMutex[userID]
 }
 
+// ManualUpdate invalidates the device list for the given user and fetches the latest and tracks it.
+// Blocks until the device list is synced or the timeout is reached.
+func (u *DeviceListUpdater) ManualUpdate(ctx context.Context, serverName gomatrixserverlib.ServerName, userID string) error {
+	mu := u.mutex(userID)
+	mu.Lock()
+	err := u.db.MarkDeviceListStale(ctx, userID, true)
+	mu.Unlock()
+	if err != nil {
+		return fmt.Errorf("ManualUpdate: failed to mark device list for %s as stale: %w", userID, err)
+	}
+	u.notifyWorkers(userID)
+	return nil
+}
+
+// Update blocks until the update has been stored in the database. It blocks primarily for satisfying sytest,
+// which assumes when /send 200 OKs that the device lists have been updated.
 func (u *DeviceListUpdater) Update(ctx context.Context, event gomatrixserverlib.DeviceListUpdateEvent) error {
 	isDeviceListStale, err := u.update(ctx, event)
 	if err != nil {
@@ -169,22 +193,27 @@ func (u *DeviceListUpdater) update(ctx context.Context, event gomatrixserverlib.
 		"stream_id":      event.StreamID,
 		"prev_ids":       event.PrevID,
 		"display_name":   event.DeviceDisplayName,
+		"deleted":        event.Deleted,
 	}).Info("DeviceListUpdater.Update")
 
 	// if we haven't missed anything update the database and notify users
 	if exists {
+		k := event.Keys
+		if event.Deleted {
+			k = nil
+		}
 		keys := []api.DeviceMessage{
 			{
 				DeviceKeys: api.DeviceKeys{
 					DeviceID:    event.DeviceID,
 					DisplayName: event.DeviceDisplayName,
-					KeyJSON:     event.Keys,
+					KeyJSON:     k,
 					UserID:      event.UserID,
 				},
 				StreamID: event.StreamID,
 			},
 		}
-		err = u.db.StoreRemoteDeviceKeys(ctx, keys)
+		err = u.db.StoreRemoteDeviceKeys(ctx, keys, nil)
 		if err != nil {
 			return false, fmt.Errorf("failed to store remote device keys for %s (%s): %w", event.UserID, event.DeviceID, err)
 		}
@@ -213,7 +242,35 @@ func (u *DeviceListUpdater) notifyWorkers(userID string) {
 	hash := fnv.New32a()
 	_, _ = hash.Write([]byte(remoteServer))
 	index := int(hash.Sum32()) % len(u.workerChans)
+
+	ch := u.assignChannel(userID)
 	u.workerChans[index] <- remoteServer
+	select {
+	case <-ch:
+	case <-time.After(10 * time.Second):
+		// we don't return an error in this case as it's not a failure condition.
+		// we mainly block for the benefit of sytest anyway
+	}
+}
+
+func (u *DeviceListUpdater) assignChannel(userID string) chan bool {
+	u.userIDToChanMu.Lock()
+	defer u.userIDToChanMu.Unlock()
+	if ch, ok := u.userIDToChan[userID]; ok {
+		return ch
+	}
+	ch := make(chan bool)
+	u.userIDToChan[userID] = ch
+	return ch
+}
+
+func (u *DeviceListUpdater) clearChannel(userID string) {
+	u.userIDToChanMu.Lock()
+	defer u.userIDToChanMu.Unlock()
+	if ch, ok := u.userIDToChan[userID]; ok {
+		close(ch)
+		delete(u.userIDToChan, userID)
+	}
 }
 
 func (u *DeviceListUpdater) worker(ch chan gomatrixserverlib.ServerName) {
@@ -230,6 +287,7 @@ func (u *DeviceListUpdater) worker(ch chan gomatrixserverlib.ServerName) {
 	}
 
 	// on failure, spin up a short-lived goroutine to inject the server name again.
+	scheduledRetries := make(map[gomatrixserverlib.ServerName]time.Time)
 	inject := func(srv gomatrixserverlib.ServerName, duration time.Duration) {
 		time.Sleep(duration)
 		ch <- srv
@@ -237,13 +295,20 @@ func (u *DeviceListUpdater) worker(ch chan gomatrixserverlib.ServerName) {
 
 	for serverName := range ch {
 		if !shouldProcess(serverName) {
-			// do not inject into the channel as we know there will be a sleeping goroutine
+			if time.Now().Before(scheduledRetries[serverName]) {
-			// which will do it after the cooloff period expires
+				// do not inject into the channel as we know there will be a sleeping goroutine
-			continue
+				// which will do it after the cooloff period expires
+				continue
+			} else {
+				scheduledRetries[serverName] = time.Now().Add(cooloffPeriod)
+				go inject(serverName, cooloffPeriod) // TODO: Backoff?
+				continue
+			}
 		}
 		lastProcessed[serverName] = time.Now()
 		shouldRetry := u.processServer(serverName)
 		if shouldRetry {
+			scheduledRetries[serverName] = time.Now().Add(cooloffPeriod)
 			go inject(serverName, cooloffPeriod) // TODO: Backoff?
 		}
 	}
@@ -277,6 +342,8 @@ func (u *DeviceListUpdater) processServer(serverName gomatrixserverlib.ServerNam
 		if err != nil {
 			logger.WithError(err).WithField("user_id", userID).Error("fetched device list but failed to store/emit it")
 			hasFailures = true
+		} else {
+			u.clearChannel(userID)
 		}
 	}
 	return hasFailures
@@ -301,7 +368,7 @@ func (u *DeviceListUpdater) updateDeviceList(res *gomatrixserverlib.RespUserDevi
 			},
 		}
 	}
-	err := u.db.StoreRemoteDeviceKeys(ctx, keys)
+	err := u.db.StoreRemoteDeviceKeys(ctx, keys, []string{res.UserID})
 	if err != nil {
 		return fmt.Errorf("failed to store remote device keys: %w", err)
 	}

keyserver/internal/device_list_update_test.go

@@ -81,7 +81,7 @@ func (d *mockDeviceListUpdaterDatabase) MarkDeviceListStale(ctx context.Context,
 
 // StoreRemoteDeviceKeys persists the given keys. Keys with the same user ID and device ID will be replaced. An empty KeyJSON removes the key
 // for this (user, device). Does not modify the stream ID for keys.
-func (d *mockDeviceListUpdaterDatabase) StoreRemoteDeviceKeys(ctx context.Context, keys []api.DeviceMessage) error {
+func (d *mockDeviceListUpdaterDatabase) StoreRemoteDeviceKeys(ctx context.Context, keys []api.DeviceMessage, clear []string) error {
 	d.storedKeys = append(d.storedKeys, keys...)
 	return nil
 }
@@ -204,16 +204,6 @@ func TestUpdateNoPrevID(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Update returned an error: %s", err)
 	}
-	// At this point we show have this device list marked as stale and not store the keys or emitted anything
-	if !db.staleUsers[event.UserID] {
-		t.Errorf("%s not marked as stale", event.UserID)
-	}
-	if len(producer.events) > 0 {
-		t.Errorf("Update incorrect emitted %d device change events", len(producer.events))
-	}
-	if len(db.storedKeys) > 0 {
-		t.Errorf("Update incorrect stored %d device change events", len(db.storedKeys))
-	}
 	t.Log("waiting for /users/devices to be called...")
 	wg.Wait()
 	// wait a bit for db to be updated...

keyserver/internal/internal.go

@@ -28,6 +28,7 @@ import (
 	userapi "github.com/matrix-org/dendrite/userapi/api"
 	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/matrix-org/util"
+	"github.com/sirupsen/logrus"
 	"github.com/tidwall/gjson"
 	"github.com/tidwall/sjson"
 )
@@ -205,7 +206,15 @@ func (a *KeyInternalAPI) QueryDeviceMessages(ctx context.Context, req *api.Query
 			maxStreamID = m.StreamID
 		}
 	}
-	res.Devices = msgs
+	// remove deleted devices
+	var result []api.DeviceMessage
+	for _, m := range msgs {
+		if m.KeyJSON == nil {
+			continue
+		}
+		result = append(result, m)
+	}
+	res.Devices = result
 	res.StreamID = maxStreamID
 }
 
@@ -282,27 +291,21 @@ func (a *KeyInternalAPI) remoteKeysFromDatabase(
 	fetchRemote := make(map[string]map[string][]string)
 	for domain, userToDeviceMap := range domainToDeviceKeys {
 		for userID, deviceIDs := range userToDeviceMap {
-			keys, err := a.DB.DeviceKeysForUser(ctx, userID, deviceIDs)
+			// we can't safely return keys from the db when all devices are requested as we don't
-			// if we can't query the db or there are fewer keys than requested, fetch from remote.
-			// Likewise, we can't safely return keys from the db when all devices are requested as we don't
 			// know if one has just been added.
-			if len(deviceIDs) == 0 || err != nil || len(keys) < len(deviceIDs) {
+			if len(deviceIDs) > 0 {
-				if _, ok := fetchRemote[domain]; !ok {
+				err := a.populateResponseWithDeviceKeysFromDatabase(ctx, res, userID, deviceIDs)
-					fetchRemote[domain] = make(map[string][]string)
+				if err == nil {
+					continue
 				}
-				fetchRemote[domain][userID] = append(fetchRemote[domain][userID], deviceIDs...)
+				util.GetLogger(ctx).WithError(err).Error("populateResponseWithDeviceKeysFromDatabase")
-				continue
 			}
-			if res.DeviceKeys[userID] == nil {
+			// fetch device lists from remote
-				res.DeviceKeys[userID] = make(map[string]json.RawMessage)
+			if _, ok := fetchRemote[domain]; !ok {
-			}
+				fetchRemote[domain] = make(map[string][]string)
-			for _, key := range keys {
-				// inject the display name
-				key.KeyJSON, _ = sjson.SetBytes(key.KeyJSON, "unsigned", struct {
-					DisplayName string `json:"device_display_name,omitempty"`
-				}{key.DisplayName})
-				res.DeviceKeys[userID][key.DeviceID] = key.KeyJSON
 			}
+			fetchRemote[domain][userID] = append(fetchRemote[domain][userID], deviceIDs...)
+
 		}
 	}
 	return fetchRemote
@@ -324,6 +327,45 @@ func (a *KeyInternalAPI) queryRemoteKeys(
 			defer wg.Done()
 			fedCtx, cancel := context.WithTimeout(ctx, timeout)
 			defer cancel()
+			// for users who we do not have any knowledge about, try to start doing device list updates for them
+			// by hitting /users/devices - otherwise fallback to /keys/query which has nicer bulk properties but
+			// lack a stream ID.
+			var userIDsForAllDevices []string
+			for userID, deviceIDs := range devKeys {
+				if len(deviceIDs) == 0 {
+					userIDsForAllDevices = append(userIDsForAllDevices, userID)
+					delete(devKeys, userID)
+				}
+			}
+			for _, userID := range userIDsForAllDevices {
+				err := a.Updater.ManualUpdate(context.Background(), gomatrixserverlib.ServerName(serverName), userID)
+				if err != nil {
+					logrus.WithFields(logrus.Fields{
+						logrus.ErrorKey: err,
+						"user_id":       userID,
+						"server":        serverName,
+					}).Error("Failed to manually update device lists for user")
+					// try to do it via /keys/query
+					devKeys[userID] = []string{}
+					continue
+				}
+				// refresh entries from DB: unlike remoteKeysFromDatabase we know we previously had no device info for this
+				// user so the fact that we're populating all devices here isn't a problem so long as we have devices.
+				err = a.populateResponseWithDeviceKeysFromDatabase(ctx, res, userID, nil)
+				if err != nil {
+					logrus.WithFields(logrus.Fields{
+						logrus.ErrorKey: err,
+						"user_id":       userID,
+						"server":        serverName,
+					}).Error("Failed to manually update device lists for user")
+					// try to do it via /keys/query
+					devKeys[userID] = []string{}
+					continue
+				}
+			}
+			if len(devKeys) == 0 {
+				return
+			}
 			queryKeysResp, err := a.FedClient.QueryKeys(fedCtx, gomatrixserverlib.ServerName(serverName), devKeys)
 			if err != nil {
 				failMu.Lock()
@@ -357,6 +399,37 @@ func (a *KeyInternalAPI) queryRemoteKeys(
 	}
 }
 
+func (a *KeyInternalAPI) populateResponseWithDeviceKeysFromDatabase(
+	ctx context.Context, res *api.QueryKeysResponse, userID string, deviceIDs []string,
+) error {
+	keys, err := a.DB.DeviceKeysForUser(ctx, userID, deviceIDs)
+	// if we can't query the db or there are fewer keys than requested, fetch from remote.
+	if err != nil {
+		return fmt.Errorf("DeviceKeysForUser %s %v failed: %w", userID, deviceIDs, err)
+	}
+	if len(keys) < len(deviceIDs) {
+		return fmt.Errorf("DeviceKeysForUser %s returned fewer devices than requested, falling back to remote", userID)
+	}
+	if len(deviceIDs) == 0 && len(keys) == 0 {
+		return fmt.Errorf("DeviceKeysForUser %s returned no keys but wanted all keys, falling back to remote", userID)
+	}
+	if res.DeviceKeys[userID] == nil {
+		res.DeviceKeys[userID] = make(map[string]json.RawMessage)
+	}
+
+	for _, key := range keys {
+		if len(key.KeyJSON) == 0 {
+			continue // ignore deleted keys
+		}
+		// inject the display name
+		key.KeyJSON, _ = sjson.SetBytes(key.KeyJSON, "unsigned", struct {
+			DisplayName string `json:"device_display_name,omitempty"`
+		}{key.DisplayName})
+		res.DeviceKeys[userID][key.DeviceID] = key.KeyJSON
+	}
+	return nil
+}
+
 func (a *KeyInternalAPI) uploadLocalDeviceKeys(ctx context.Context, req *api.PerformUploadKeysRequest, res *api.PerformUploadKeysResponse) {
 	var keysToStore []api.DeviceMessage
 	// assert that the user ID / device ID are not lying for each key
@@ -403,6 +476,10 @@ func (a *KeyInternalAPI) uploadLocalDeviceKeys(ctx context.Context, req *api.Per
 		}
 		return
 	}
+	if req.OnlyDisplayNameUpdates {
+		// add the display name field from keysToStore into existingKeys
+		keysToStore = appendDisplayNames(existingKeys, keysToStore)
+	}
 	// store the device keys and emit changes
 	err := a.DB.StoreLocalDeviceKeys(ctx, keysToStore)
 	if err != nil {
@@ -475,3 +552,16 @@ func (a *KeyInternalAPI) emitDeviceKeyChanges(existing, new []api.DeviceMessage)
 	}
 	return a.Producer.ProduceKeyChanges(keysAdded)
 }
+
+func appendDisplayNames(existing, new []api.DeviceMessage) []api.DeviceMessage {
+	for i, existingDevice := range existing {
+		for _, newDevice := range new {
+			if existingDevice.DeviceID != newDevice.DeviceID {
+				continue
+			}
+			existingDevice.DisplayName = newDevice.DisplayName
+			existing[i] = existingDevice
+		}
+	}
+	return existing
+}

keyserver/storage/interface.go

@@ -43,8 +43,9 @@ type Database interface {
 	StoreLocalDeviceKeys(ctx context.Context, keys []api.DeviceMessage) error
 
 	// StoreRemoteDeviceKeys persists the given keys. Keys with the same user ID and device ID will be replaced. An empty KeyJSON removes the key
-	// for this (user, device). Does not modify the stream ID for keys.
+	// for this (user, device). Does not modify the stream ID for keys. User IDs in `clearUserIDs` will have all their device keys deleted prior
-	StoreRemoteDeviceKeys(ctx context.Context, keys []api.DeviceMessage) error
+	// to insertion - use this when you have a complete snapshot of a user's keys in order to track device deletions correctly.
+	StoreRemoteDeviceKeys(ctx context.Context, keys []api.DeviceMessage, clearUserIDs []string) error
 
 	// PrevIDsExists returns true if all prev IDs exist for this user.
 	PrevIDsExists(ctx context.Context, userID string, prevIDs []int) (bool, error)

keyserver/storage/postgres/device_keys_table.go

@@ -61,6 +61,9 @@ const selectMaxStreamForUserSQL = "" +
 const countStreamIDsForUserSQL = "" +
 	"SELECT COUNT(*) FROM keyserver_device_keys WHERE user_id=$1 AND stream_id = ANY($2)"
 
+const deleteAllDeviceKeysSQL = "" +
+	"DELETE FROM keyserver_device_keys WHERE user_id=$1"
+
 type deviceKeysStatements struct {
 	db                         *sql.DB
 	upsertDeviceKeysStmt       *sql.Stmt
@@ -68,6 +71,7 @@ type deviceKeysStatements struct {
 	selectBatchDeviceKeysStmt  *sql.Stmt
 	selectMaxStreamForUserStmt *sql.Stmt
 	countStreamIDsForUserStmt  *sql.Stmt
+	deleteAllDeviceKeysStmt    *sql.Stmt
 }
 
 func NewPostgresDeviceKeysTable(db *sql.DB) (tables.DeviceKeys, error) {
@@ -93,6 +97,9 @@ func NewPostgresDeviceKeysTable(db *sql.DB) (tables.DeviceKeys, error) {
 	if s.countStreamIDsForUserStmt, err = db.Prepare(countStreamIDsForUserSQL); err != nil {
 		return nil, err
 	}
+	if s.deleteAllDeviceKeysStmt, err = db.Prepare(deleteAllDeviceKeysSQL); err != nil {
+		return nil, err
+	}
 	return s, nil
 }
 
@@ -154,6 +161,11 @@ func (s *deviceKeysStatements) InsertDeviceKeys(ctx context.Context, txn *sql.Tx
 	return nil
 }
 
+func (s *deviceKeysStatements) DeleteAllDeviceKeys(ctx context.Context, txn *sql.Tx, userID string) error {
+	_, err := txn.Stmt(s.deleteAllDeviceKeysStmt).ExecContext(ctx, userID)
+	return err
+}
+
 func (s *deviceKeysStatements) SelectBatchDeviceKeys(ctx context.Context, userID string, deviceIDs []string) ([]api.DeviceMessage, error) {
 	rows, err := s.selectBatchDeviceKeysStmt.QueryContext(ctx, userID)
 	if err != nil {

keyserver/storage/shared/storage.go

@@ -61,8 +61,14 @@ func (d *Database) PrevIDsExists(ctx context.Context, userID string, prevIDs []i
 	return count == len(prevIDs), nil
 }
 
-func (d *Database) StoreRemoteDeviceKeys(ctx context.Context, keys []api.DeviceMessage) error {
+func (d *Database) StoreRemoteDeviceKeys(ctx context.Context, keys []api.DeviceMessage, clearUserIDs []string) error {
 	return sqlutil.WithTransaction(d.DB, func(txn *sql.Tx) error {
+		for _, userID := range clearUserIDs {
+			err := d.DeviceKeysTable.DeleteAllDeviceKeys(ctx, txn, userID)
+			if err != nil {
+				return err
+			}
+		}
 		return d.DeviceKeysTable.InsertDeviceKeys(ctx, txn, keys)
 	})
 }

keyserver/storage/sqlite3/device_keys_table.go

@@ -58,6 +58,9 @@ const selectMaxStreamForUserSQL = "" +
 const countStreamIDsForUserSQL = "" +
 	"SELECT COUNT(*) FROM keyserver_device_keys WHERE user_id=$1 AND stream_id IN ($2)"
 
+const deleteAllDeviceKeysSQL = "" +
+	"DELETE FROM keyserver_device_keys WHERE user_id=$1"
+
 type deviceKeysStatements struct {
 	db                         *sql.DB
 	writer                     *sqlutil.TransactionWriter
@@ -65,6 +68,7 @@ type deviceKeysStatements struct {
 	selectDeviceKeysStmt       *sql.Stmt
 	selectBatchDeviceKeysStmt  *sql.Stmt
 	selectMaxStreamForUserStmt *sql.Stmt
+	deleteAllDeviceKeysStmt    *sql.Stmt
 }
 
 func NewSqliteDeviceKeysTable(db *sql.DB) (tables.DeviceKeys, error) {
@@ -88,9 +92,17 @@ func NewSqliteDeviceKeysTable(db *sql.DB) (tables.DeviceKeys, error) {
 	if s.selectMaxStreamForUserStmt, err = db.Prepare(selectMaxStreamForUserSQL); err != nil {
 		return nil, err
 	}
+	if s.deleteAllDeviceKeysStmt, err = db.Prepare(deleteAllDeviceKeysSQL); err != nil {
+		return nil, err
+	}
 	return s, nil
 }
 
+func (s *deviceKeysStatements) DeleteAllDeviceKeys(ctx context.Context, txn *sql.Tx, userID string) error {
+	_, err := txn.Stmt(s.deleteAllDeviceKeysStmt).ExecContext(ctx, userID)
+	return err
+}
+
 func (s *deviceKeysStatements) SelectBatchDeviceKeys(ctx context.Context, userID string, deviceIDs []string) ([]api.DeviceMessage, error) {
 	deviceIDMap := make(map[string]bool)
 	for _, d := range deviceIDs {

keyserver/storage/tables/interface.go

@@ -38,6 +38,7 @@ type DeviceKeys interface {
 	SelectMaxStreamIDForUser(ctx context.Context, txn *sql.Tx, userID string) (streamID int32, err error)
 	CountStreamIDsForUser(ctx context.Context, userID string, streamIDs []int64) (int, error)
 	SelectBatchDeviceKeys(ctx context.Context, userID string, deviceIDs []string) ([]api.DeviceMessage, error)
+	DeleteAllDeviceKeys(ctx context.Context, txn *sql.Tx, userID string) error
 }
 
 type KeyChanges interface {

syncapi/internal/keychange.go

@@ -96,7 +96,8 @@ func DeviceListCatchup(
 		return hasNew, nil
 	}
 	// QueryKeyChanges gets ALL users who have changed keys, we want the ones who share rooms with the user.
-	queryRes.UserIDs = filterSharedUsers(ctx, stateAPI, userID, queryRes.UserIDs)
+	var sharedUsersMap map[string]int
+	sharedUsersMap, queryRes.UserIDs = filterSharedUsers(ctx, stateAPI, userID, queryRes.UserIDs)
 	util.GetLogger(ctx).Debugf(
 		"QueryKeyChanges request p=%d,off=%d,to=%d response p=%d off=%d uids=%v",
 		partition, offset, toOffset, queryRes.Partition, queryRes.Offset, queryRes.UserIDs,
@@ -114,13 +115,20 @@ func DeviceListCatchup(
 	}
 	// if the response has any join/leave events, add them now.
 	// TODO: This is sub-optimal because we will add users to `changed` even if we already shared a room with them.
-	for _, userID := range membershipEvents(res) {
+	joinUserIDs, leaveUserIDs := membershipEvents(res)
+	for _, userID := range joinUserIDs {
 		if !userSet[userID] {
 			res.DeviceLists.Changed = append(res.DeviceLists.Changed, userID)
 			hasNew = true
 			userSet[userID] = true
 		}
 	}
+	for _, userID := range leaveUserIDs {
+		if sharedUsersMap[userID] == 0 {
+			// we no longer share a room with this user when they left, so add to left list.
+			res.DeviceLists.Left = append(res.DeviceLists.Left, userID)
+		}
+	}
 	// set the new token
 	to.SetLog(DeviceListLogName, &types.LogPosition{
 		Partition: queryRes.Partition,
@@ -221,7 +229,7 @@ func TrackChangedUsers(
 
 func filterSharedUsers(
 	ctx context.Context, stateAPI currentstateAPI.CurrentStateInternalAPI, userID string, usersWithChangedKeys []string,
-) []string {
+) (map[string]int, []string) {
 	var result []string
 	var sharedUsersRes currentstateAPI.QuerySharedUsersResponse
 	err := stateAPI.QuerySharedUsers(ctx, &currentstateAPI.QuerySharedUsersRequest{
@@ -229,7 +237,7 @@ func filterSharedUsers(
 	}, &sharedUsersRes)
 	if err != nil {
 		// default to all users so we do needless queries rather than miss some important device update
-		return usersWithChangedKeys
+		return nil, usersWithChangedKeys
 	}
 	// We forcibly put ourselves in this list because we should be notified about our own device updates
 	// and if we are in 0 rooms then we don't technically share any room with ourselves so we wouldn't
@@ -241,7 +249,7 @@ func filterSharedUsers(
 			result = append(result, uid)
 		}
 	}
-	return result
+	return sharedUsersRes.UserIDsToCount, result
 }
 
 func joinedRooms(res *types.Response, userID string) []string {
@@ -288,16 +296,16 @@ func membershipEventPresent(events []gomatrixserverlib.ClientEvent, userID strin
 // "For optimal performance, Alice should be added to changed in Bob's sync only when she adds a new device,
 // or when Alice and Bob now share a room but didn't share any room previously. However, for the sake of simpler
 // logic, a server may add Alice to changed when Alice and Bob share a new room, even if they previously already shared a room."
-func membershipEvents(res *types.Response) (userIDs []string) {
+func membershipEvents(res *types.Response) (joinUserIDs, leaveUserIDs []string) {
 	for _, room := range res.Rooms.Join {
 		for _, ev := range room.Timeline.Events {
 			if ev.Type == gomatrixserverlib.MRoomMember && ev.StateKey != nil {
 				if strings.Contains(string(ev.Content), `"join"`) {
-					userIDs = append(userIDs, *ev.StateKey)
+					joinUserIDs = append(joinUserIDs, *ev.StateKey)
 				} else if strings.Contains(string(ev.Content), `"leave"`) {
-					userIDs = append(userIDs, *ev.StateKey)
+					leaveUserIDs = append(leaveUserIDs, *ev.StateKey)
 				} else if strings.Contains(string(ev.Content), `"ban"`) {
-					userIDs = append(userIDs, *ev.StateKey)
+					leaveUserIDs = append(leaveUserIDs, *ev.StateKey)
 				}
 			}
 		}

sytest-whitelist

@@ -142,7 +142,12 @@ Server correctly handles incoming m.device_list_update
 Device deletion propagates over federation
 If remote user leaves room, changes device and rejoins we see update in sync
 If remote user leaves room, changes device and rejoins we see update in /keys/changes
+If remote user leaves room we no longer receive device updates
+If a device list update goes missing, the server resyncs on the next one
+Get left notifs in sync and /keys/changes when other user leaves
 Can query remote device keys using POST after notification
+Server correctly resyncs when client query keys and there is no remote cache
+Server correctly resyncs when server leaves and rejoins a room
 Can add account data
 Can add account data to room
 Can get account data without syncing

userapi/internal/api.go

@@ -180,6 +180,27 @@ func (a *UserInternalAPI) PerformDeviceUpdate(ctx context.Context, req *api.Perf
 		util.GetLogger(ctx).WithError(err).Error("deviceDB.UpdateDevice failed")
 		return err
 	}
+	if req.DisplayName != nil && dev.DisplayName != *req.DisplayName {
+		// display name has changed: update the device key
+		var uploadRes keyapi.PerformUploadKeysResponse
+		a.KeyAPI.PerformUploadKeys(context.Background(), &keyapi.PerformUploadKeysRequest{
+			DeviceKeys: []keyapi.DeviceKeys{
+				{
+					DeviceID:    dev.ID,
+					DisplayName: *req.DisplayName,
+					KeyJSON:     nil,
+					UserID:      dev.UserID,
+				},
+			},
+			OnlyDisplayNameUpdates: true,
+		}, &uploadRes)
+		if uploadRes.Error != nil {
+			return fmt.Errorf("Failed to update device key display name: %v", uploadRes.Error)
+		}
+		if len(uploadRes.KeyErrors) > 0 {
+			return fmt.Errorf("Failed to update device key display name, key errors: %+v", uploadRes.KeyErrors)
+		}
+	}
 	return nil
 }