Remove pdu.UserID & pass in the required accessor

appservice/consumers/roomserver.go

@@ -181,7 +181,9 @@ func (s *OutputRoomEventConsumer) sendEvents(
 	// Create the transaction body.
 	transaction, err := json.Marshal(
 		ApplicationServiceTransaction{
-			Events: synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(events), synctypes.FormatAll),
+			Events: synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(events), synctypes.FormatAll, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+				return s.rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+			}),
 		},
 	)
 	if err != nil {
@@ -234,7 +236,7 @@ func (s *appserviceState) backoffAndPause(err error) error {
 // TODO: This should be cached, see https://github.com/matrix-org/dendrite/issues/1682
 func (s *OutputRoomEventConsumer) appserviceIsInterestedInEvent(ctx context.Context, event *types.HeaderedEvent, appservice *config.ApplicationService) bool {
 	user := ""
-	userID, err := event.UserID()
+	userID, err := s.rsAPI.QueryUserIDForSender(ctx, event.RoomID(), event.SenderID())
 	if err == nil {
 		user = userID.String()
 	}

clientapi/routing/sendevent.go

@@ -331,7 +331,9 @@ func generateSendEvent(
 		stateEvents[i] = queryRes.StateEvents[i].PDU
 	}
 	provider := gomatrixserverlib.NewAuthEvents(gomatrixserverlib.ToPDUs(stateEvents))
-	if err = gomatrixserverlib.Allowed(e.PDU, &provider); err != nil {
+	if err = gomatrixserverlib.Allowed(e.PDU, &provider, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+		return rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+	}); err != nil {
 		return nil, &util.JSONResponse{
 			Code: http.StatusForbidden,
 			JSON: spec.Forbidden(err.Error()), // TODO: Is this error string comprehensible to the client?

clientapi/routing/state.go

@@ -142,7 +142,9 @@ func OnIncomingStateRequest(ctx context.Context, device *userapi.Device, rsAPI a
 		for _, ev := range stateRes.StateEvents {
 			stateEvents = append(
 				stateEvents,
-				synctypes.ToClientEvent(ev, synctypes.FormatAll),
+				synctypes.ToClientEvent(ev, synctypes.FormatAll, func(roomAliasOrID string, senderID string) (*spec.UserID, error) {
+					return rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+				}),
 			)
 		}
 	} else {
@@ -164,7 +166,9 @@ func OnIncomingStateRequest(ctx context.Context, device *userapi.Device, rsAPI a
 		for _, ev := range stateAfterRes.StateEvents {
 			stateEvents = append(
 				stateEvents,
-				synctypes.ToClientEvent(ev, synctypes.FormatAll),
+				synctypes.ToClientEvent(ev, synctypes.FormatAll, func(roomAliasOrID string, senderID string) (*spec.UserID, error) {
+					return rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+				}),
 			)
 		}
 	}
@@ -335,7 +339,9 @@ func OnIncomingStateTypeRequest(
 	}
 
 	stateEvent := stateEventInStateResp{
-		ClientEvent: synctypes.ToClientEvent(event, synctypes.FormatAll),
+		ClientEvent: synctypes.ToClientEvent(event, synctypes.FormatAll, func(roomAliasOrID string, senderID string) (*spec.UserID, error) {
+			return rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+		}),
 	}
 
 	var res interface{}

cmd/resolve-state/main.go

@@ -18,6 +18,7 @@ import (
 	"github.com/matrix-org/dendrite/setup/config"
 	"github.com/matrix-org/dendrite/setup/process"
 	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/gomatrixserverlib/spec"
 )
 
 // This is a utility for inspecting state snapshots and running state resolution
@@ -182,7 +183,9 @@ func main() {
 	fmt.Println("Resolving state")
 	var resolved Events
 	resolved, err = gomatrixserverlib.ResolveConflicts(
-		gomatrixserverlib.RoomVersion(*roomVersion), events, authEvents,
+		gomatrixserverlib.RoomVersion(*roomVersion), events, authEvents, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return roomserverDB.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+		},
 	)
 	if err != nil {
 		panic(err)

federationapi/federationapi_test.go

@@ -36,6 +36,10 @@ type fedRoomserverAPI struct {
 	queryRoomsForUser func(ctx context.Context, req *rsapi.QueryRoomsForUserRequest, res *rsapi.QueryRoomsForUserResponse) error
 }
 
+func (f *fedRoomserverAPI) QueryUserIDForSender(ctx context.Context, roomAliasOrID string, senderID string) (*spec.UserID, error) {
+	return spec.NewUserID(senderID, true)
+}
+
 // PerformJoin will call this function
 func (f *fedRoomserverAPI) InputRoomEvents(ctx context.Context, req *rsapi.InputRoomEventsRequest, res *rsapi.InputRoomEventsResponse) {
 	if f.inputRoomEvents == nil {

federationapi/internal/perform.go

@@ -156,15 +156,20 @@ func (r *FederationInternalAPI) performJoinUsingServer(
 	}
 
 	joinInput := gomatrixserverlib.PerformJoinInput{
-		UserID:        user,
+		UserID:     user,
-		RoomID:        room,
+		RoomID:     room,
-		ServerName:    serverName,
+		ServerName: serverName,
-		Content:       content,
+		Content:    content,
-		Unsigned:      unsigned,
+		Unsigned:   unsigned,
-		PrivateKey:    r.cfg.Matrix.PrivateKey,
+		PrivateKey: r.cfg.Matrix.PrivateKey,
-		KeyID:         r.cfg.Matrix.KeyID,
+		KeyID:      r.cfg.Matrix.KeyID,
-		KeyRing:       r.keyRing,
+		KeyRing:    r.keyRing,
-		EventProvider: federatedEventProvider(ctx, r.federation, r.keyRing, user.Domain(), serverName),
+		EventProvider: federatedEventProvider(ctx, r.federation, r.keyRing, user.Domain(), serverName, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return r.rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+		}),
+		UserIDQuerier: func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return r.rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+		},
 	}
 	response, joinErr := gomatrixserverlib.PerformJoin(ctx, r, joinInput)
 
@@ -358,8 +363,11 @@ func (r *FederationInternalAPI) performOutboundPeekUsingServer(
 
 	// authenticate the state returned (check its auth events etc)
 	// the equivalent of CheckSendJoinResponse()
+	userIDProvider := func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+		return r.rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+	}
 	authEvents, stateEvents, err := gomatrixserverlib.CheckStateResponse(
-		ctx, &respPeek, respPeek.RoomVersion, r.keyRing, federatedEventProvider(ctx, r.federation, r.keyRing, r.cfg.Matrix.ServerName, serverName),
+		ctx, &respPeek, respPeek.RoomVersion, r.keyRing, federatedEventProvider(ctx, r.federation, r.keyRing, r.cfg.Matrix.ServerName, serverName, userIDProvider), userIDProvider,
 	)
 	if err != nil {
 		return fmt.Errorf("error checking state returned from peeking: %w", err)
@@ -509,7 +517,7 @@ func (r *FederationInternalAPI) SendInvite(
 	event gomatrixserverlib.PDU,
 	strippedState []gomatrixserverlib.InviteStrippedState,
 ) (gomatrixserverlib.PDU, error) {
-	inviter, err := event.UserID()
+	inviter, err := r.rsAPI.QueryUserIDForSender(ctx, event.RoomID(), event.SenderID())
 	if err != nil {
 		return nil, err
 	}
@@ -640,6 +648,7 @@ func checkEventsContainCreateEvent(events []gomatrixserverlib.PDU) error {
 func federatedEventProvider(
 	ctx context.Context, federation fclient.FederationClient,
 	keyRing gomatrixserverlib.JSONVerifier, origin, server spec.ServerName,
+	userIDForSender spec.UserIDForSender,
 ) gomatrixserverlib.EventProvider {
 	// A list of events that we have retried, if they were not included in
 	// the auth events supplied in the send_join.
@@ -689,7 +698,7 @@ func federatedEventProvider(
 				}
 
 				// Check the signatures of the event.
-				if err := gomatrixserverlib.VerifyEventSignatures(ctx, ev, keyRing); err != nil {
+				if err := gomatrixserverlib.VerifyEventSignatures(ctx, ev, keyRing, userIDForSender); err != nil {
 					return nil, fmt.Errorf("missingAuth VerifyEventSignatures: %w", err)
 				}
 

federationapi/routing/join.go

@@ -147,15 +147,18 @@ func MakeJoin(
 	}
 
 	input := gomatrixserverlib.HandleMakeJoinInput{
-		Context:            httpReq.Context(),
+		Context:           httpReq.Context(),
-		UserID:             userID,
+		UserID:            userID,
-		RoomID:             roomID,
+		RoomID:            roomID,
-		RoomVersion:        roomVersion,
+		RoomVersion:       roomVersion,
-		RemoteVersions:     remoteVersions,
+		RemoteVersions:    remoteVersions,
-		RequestOrigin:      request.Origin(),
+		RequestOrigin:     request.Origin(),
-		LocalServerName:    cfg.Matrix.ServerName,
+		LocalServerName:   cfg.Matrix.ServerName,
-		LocalServerInRoom:  res.RoomExists && res.IsInRoom,
+		LocalServerInRoom: res.RoomExists && res.IsInRoom,
-		RoomQuerier:        &roomQuerier,
+		RoomQuerier:       &roomQuerier,
+		UserIDQuerier: func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return rsAPI.QueryUserIDForSender(httpReq.Context(), roomAliasOrID, senderID)
+		},
 		BuildEventTemplate: createJoinTemplate,
 	}
 	response, internalErr := gomatrixserverlib.HandleMakeJoin(input)

federationapi/routing/leave.go

@@ -223,7 +223,7 @@ func SendLeave(
 	// Check that the sender belongs to the server that is sending us
 	// the request. By this point we've already asserted that the sender
 	// and the state key are equal so we don't need to check both.
-	sender, err := event.UserID()
+	sender, err := rsAPI.QueryUserIDForSender(httpReq.Context(), event.RoomID(), event.SenderID())
 	if err != nil {
 		return util.JSONResponse{
 			Code: http.StatusForbidden,

go.mod

@@ -22,7 +22,7 @@ require (
 	github.com/matrix-org/dugong v0.0.0-20210921133753-66e6b1c67e2e
 	github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91
 	github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530
-	github.com/matrix-org/gomatrixserverlib v0.0.0-20230603021032-d30b8fdc7ced
+	github.com/matrix-org/gomatrixserverlib v0.0.0-20230606021710-b68a1b0eef30
 	github.com/matrix-org/pinecone v0.11.1-0.20230210171230-8c3b24f2649a
 	github.com/matrix-org/util v0.0.0-20221111132719-399730281e66
 	github.com/mattn/go-sqlite3 v1.14.16
@@ -34,7 +34,7 @@ require (
 	github.com/patrickmn/go-cache v2.1.0+incompatible
 	github.com/pkg/errors v0.9.1
 	github.com/prometheus/client_golang v1.13.0
-	github.com/sirupsen/logrus v1.9.2
+	github.com/sirupsen/logrus v1.9.3
 	github.com/stretchr/testify v1.8.2
 	github.com/tidwall/gjson v1.14.4
 	github.com/tidwall/sjson v1.2.5

go.sum

@@ -323,8 +323,8 @@ github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91 h1:s7fexw
 github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91/go.mod h1:e+cg2q7C7yE5QnAXgzo512tgFh1RbQLC0+jozuegKgo=
 github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530 h1:kHKxCOLcHH8r4Fzarl4+Y3K5hjothkVW5z7T1dUM11U=
 github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530/go.mod h1:/gBX06Kw0exX1HrwmoBibFA98yBk/jxKpGVeyQbff+s=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20230603021032-d30b8fdc7ced h1:pbCM+nno+r2wW3jwxP65xmkzk6008CdMNZaOWYBwB1c=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20230606021710-b68a1b0eef30 h1:G+Do1UoWazY0Fetq+eAX1h1+fimf19NGGyaS86hWg8s=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20230603021032-d30b8fdc7ced/go.mod h1:H9V9N3Uqn1bBJqYJNGK1noqtgJTaCEhtTdcH/mp50uU=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20230606021710-b68a1b0eef30/go.mod h1:H9V9N3Uqn1bBJqYJNGK1noqtgJTaCEhtTdcH/mp50uU=
 github.com/matrix-org/pinecone v0.11.1-0.20230210171230-8c3b24f2649a h1:awrPDf9LEFySxTLKYBMCiObelNx/cBuv/wzllvCCH3A=
 github.com/matrix-org/pinecone v0.11.1-0.20230210171230-8c3b24f2649a/go.mod h1:HchJX9oKMXaT2xYFs0Ha/6Zs06mxLU8k6F1ODnrGkeQ=
 github.com/matrix-org/util v0.0.0-20221111132719-399730281e66 h1:6z4KxomXSIGWqhHcfzExgkH3Z3UkIXry4ibJS4Aqz2Y=
@@ -444,8 +444,8 @@ github.com/sirupsen/logrus v1.2.0/go.mod h1:LxeOpSwHxABJmUn/MG1IvRgCAasNZTLOkJPx
 github.com/sirupsen/logrus v1.4.2/go.mod h1:tLMulIdttU9McNUspp0xgXVQah82FyeX6MwdIuYE2rE=
 github.com/sirupsen/logrus v1.6.0/go.mod h1:7uNnSEd1DgxDLC74fIahvMZmmYsHGZGEOFrfsX/uA88=
 github.com/sirupsen/logrus v1.7.0/go.mod h1:yWOB1SBYBC5VeMP7gHvWumXLIWorT60ONWic61uBYv0=
-github.com/sirupsen/logrus v1.9.2 h1:oxx1eChJGI6Uks2ZC4W1zpLlVgqB8ner4EuQwV4Ik1Y=
+github.com/sirupsen/logrus v1.9.3 h1:dueUQJ1C2q9oE3F7wvmSGAaVtTmUizReu6fjN8uqzbQ=
-github.com/sirupsen/logrus v1.9.2/go.mod h1:naHLuLoDiP4jHNo9R0sCBMtWGeIprob74mVsIT4qYEQ=
+github.com/sirupsen/logrus v1.9.3/go.mod h1:naHLuLoDiP4jHNo9R0sCBMtWGeIprob74mVsIT4qYEQ=
 github.com/smartystreets/assertions v0.0.0-20180927180507-b2de0cb4f26d/go.mod h1:OnSkiWE9lh6wB0YB77sQom3nweQdgAjqCqsofrRNTgc=
 github.com/smartystreets/goconvey v0.0.0-20181108003508-044398e4856c/go.mod h1:XDJAKZRPZ1CvBcN2aX5YOUTYGHki24fSF0Iv48Ibg0s=
 github.com/spf13/pflag v1.0.3/go.mod h1:DYY7MBk1bdzusC3SYhjObp+wFpr4gzcvqqNjLnInEg4=

internal/pushrules/evaluate.go

@@ -6,6 +6,7 @@ import (
 	"strings"
 
 	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/gomatrixserverlib/spec"
 )
 
 // A RuleSetEvaluator encapsulates context to evaluate an event
@@ -53,7 +54,7 @@ func NewRuleSetEvaluator(ec EvaluationContext, ruleSet *RuleSet) *RuleSetEvaluat
 
 // MatchEvent returns the first matching rule. Returns nil if there
 // was no match rule.
-func (rse *RuleSetEvaluator) MatchEvent(event gomatrixserverlib.PDU) (*Rule, error) {
+func (rse *RuleSetEvaluator) MatchEvent(event gomatrixserverlib.PDU, userIDForSender spec.UserIDForSender) (*Rule, error) {
 	// TODO: server-default rules have lower priority than user rules,
 	// but they are stored together with the user rules. It's a bit
 	// unclear what the specification (11.14.1.4 Predefined rules)
@@ -68,7 +69,7 @@ func (rse *RuleSetEvaluator) MatchEvent(event gomatrixserverlib.PDU) (*Rule, err
 				if rule.Default != defRules {
 					continue
 				}
-				ok, err := ruleMatches(rule, rsat.Kind, event, rse.ec)
+				ok, err := ruleMatches(rule, rsat.Kind, event, rse.ec, userIDForSender)
 				if err != nil {
 					return nil, err
 				}
@@ -83,7 +84,7 @@ func (rse *RuleSetEvaluator) MatchEvent(event gomatrixserverlib.PDU) (*Rule, err
 	return nil, nil
 }
 
-func ruleMatches(rule *Rule, kind Kind, event gomatrixserverlib.PDU, ec EvaluationContext) (bool, error) {
+func ruleMatches(rule *Rule, kind Kind, event gomatrixserverlib.PDU, ec EvaluationContext, userIDForSender spec.UserIDForSender) (bool, error) {
 	if !rule.Enabled {
 		return false, nil
 	}
@@ -114,7 +115,7 @@ func ruleMatches(rule *Rule, kind Kind, event gomatrixserverlib.PDU, ec Evaluati
 
 	case SenderKind:
 		userID := ""
-		sender, err := event.UserID()
+		sender, err := userIDForSender(event.RoomID(), event.SenderID())
 		if err == nil {
 			userID = sender.String()
 		}

internal/pushrules/evaluate_test.go

@@ -5,8 +5,13 @@ import (
 
 	"github.com/google/go-cmp/cmp"
 	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/gomatrixserverlib/spec"
 )
 
+func UserIDForSender(roomAliasOrID string, senderID string) (*spec.UserID, error) {
+	return spec.NewUserID(senderID, true)
+}
+
 func TestRuleSetEvaluatorMatchEvent(t *testing.T) {
 	ev := mustEventFromJSON(t, `{}`)
 	defaultEnabled := &Rule{
@@ -45,7 +50,7 @@ func TestRuleSetEvaluatorMatchEvent(t *testing.T) {
 	for _, tst := range tsts {
 		t.Run(tst.Name, func(t *testing.T) {
 			rse := NewRuleSetEvaluator(fakeEvaluationContext{3}, &tst.RuleSet)
-			got, err := rse.MatchEvent(tst.Event)
+			got, err := rse.MatchEvent(tst.Event, UserIDForSender)
 			if err != nil {
 				t.Fatalf("MatchEvent failed: %v", err)
 			}
@@ -90,7 +95,7 @@ func TestRuleMatches(t *testing.T) {
 	}
 	for _, tst := range tsts {
 		t.Run(tst.Name, func(t *testing.T) {
-			got, err := ruleMatches(&tst.Rule, tst.Kind, mustEventFromJSON(t, tst.EventJSON), nil)
+			got, err := ruleMatches(&tst.Rule, tst.Kind, mustEventFromJSON(t, tst.EventJSON), nil, UserIDForSender)
 			if err != nil {
 				t.Fatalf("ruleMatches failed: %v", err)
 			}

internal/transactionrequest.go

@@ -167,7 +167,9 @@ func (t *TxnReq) ProcessTransaction(ctx context.Context) (*fclient.RespSend, *ut
 			}
 			continue
 		}
-		if err = gomatrixserverlib.VerifyEventSignatures(ctx, event, t.keys); err != nil {
+		if err = gomatrixserverlib.VerifyEventSignatures(ctx, event, t.keys, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return t.rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+		}); err != nil {
 			util.GetLogger(ctx).WithError(err).Debugf("Transaction: Couldn't validate signature of event %q", event.EventID())
 			results[event.EventID()] = fclient.PDUResult{
 				Error: err.Error(),

internal/transactionrequest_test.go

@@ -70,6 +70,10 @@ type FakeRsAPI struct {
 	bannedFromRoom  bool
 }
 
+func (r *FakeRsAPI) QueryUserIDForSender(ctx context.Context, roomAliasOrID string, senderID string) (*spec.UserID, error) {
+	return spec.NewUserID(senderID, true)
+}
+
 func (r *FakeRsAPI) QueryRoomVersionForRoom(
 	ctx context.Context,
 	roomID string,
@@ -638,6 +642,10 @@ type testRoomserverAPI struct {
 	queryLatestEventsAndState func(*rsAPI.QueryLatestEventsAndStateRequest) rsAPI.QueryLatestEventsAndStateResponse
 }
 
+func (t *testRoomserverAPI) QueryUserIDForSender(ctx context.Context, roomAliasOrID string, senderID string) (*spec.UserID, error) {
+	return spec.NewUserID(senderID, true)
+}
+
 func (t *testRoomserverAPI) InputRoomEvents(
 	ctx context.Context,
 	request *rsAPI.InputRoomEventsRequest,

roomserver/api/api.go

@@ -39,6 +39,7 @@ type RoomserverInternalAPI interface {
 	ClientRoomserverAPI
 	UserRoomserverAPI
 	FederationRoomserverAPI
+	QuerySenderIDAPI
 
 	// needed to avoid chicken and egg scenario when setting up the
 	// interdependencies between the roomserver and other input APIs
@@ -68,7 +69,7 @@ type InputRoomEventsAPI interface {
 type QuerySenderIDAPI interface {
 	// Accepts either roomID or alias
 	QuerySenderIDForUser(ctx context.Context, roomAliasOrID string, userID spec.UserID) (string, error)
-	QueryUserIDForSender(ctx context.Context, roomAliasOrID string, senderID string) (spec.UserID, error)
+	QueryUserIDForSender(ctx context.Context, roomAliasOrID string, senderID string) (*spec.UserID, error)
 }
 
 // Query the latest events and state for a room from the room server.
@@ -98,6 +99,7 @@ type QueryEventsAPI interface {
 type SyncRoomserverAPI interface {
 	QueryLatestEventsAndStateAPI
 	QueryBulkStateContentAPI
+	QuerySenderIDAPI
 	// QuerySharedUsers returns a list of users who share at least 1 room in common with the given user.
 	QuerySharedUsers(ctx context.Context, req *QuerySharedUsersRequest, res *QuerySharedUsersResponse) error
 	// QueryEventsByID queries a list of events by event ID for one room. If no room is specified, it will try to determine
@@ -138,6 +140,7 @@ type SyncRoomserverAPI interface {
 }
 
 type AppserviceRoomserverAPI interface {
+	QuerySenderIDAPI
 	// QueryEventsByID queries a list of events by event ID for one room. If no room is specified, it will try to determine
 	// which room to use by querying the first events roomID.
 	QueryEventsByID(
@@ -197,6 +200,7 @@ type ClientRoomserverAPI interface {
 }
 
 type UserRoomserverAPI interface {
+	QuerySenderIDAPI
 	QueryLatestEventsAndStateAPI
 	KeyserverRoomserverAPI
 	QueryCurrentState(ctx context.Context, req *QueryCurrentStateRequest, res *QueryCurrentStateResponse) error
@@ -209,6 +213,8 @@ type FederationRoomserverAPI interface {
 	InputRoomEventsAPI
 	QueryLatestEventsAndStateAPI
 	QueryBulkStateContentAPI
+	QuerySenderIDAPI
+
 	// QueryServerBannedFromRoom returns whether a server is banned from a room by server ACLs.
 	QueryServerBannedFromRoom(ctx context.Context, req *QueryServerBannedFromRoomRequest, res *QueryServerBannedFromRoomResponse) error
 	QueryMembershipForUser(ctx context.Context, req *QueryMembershipForUserRequest, res *QueryMembershipForUserResponse) error

roomserver/api/query.go

@@ -463,10 +463,10 @@ type MembershipQuerier struct {
 	Roomserver FederationRoomserverAPI
 }
 
-func (mq *MembershipQuerier) CurrentMembership(ctx context.Context, roomID spec.RoomID, senderID string) (string, error) {
+func (mq *MembershipQuerier) CurrentMembership(ctx context.Context, roomID spec.RoomID, senderID spec.SenderID) (string, error) {
 	req := QueryMembershipForUserRequest{
 		RoomID: roomID.String(),
-		UserID: senderID,
+		UserID: string(senderID),
 	}
 	res := QueryMembershipForUserResponse{}
 	err := mq.Roomserver.QueryMembershipForUser(ctx, &req, &res)

roomserver/internal/helpers/auth.go

@@ -76,7 +76,9 @@ func CheckForSoftFail(
 	}
 
 	// Check if the event is allowed.
-	if err = gomatrixserverlib.Allowed(event.PDU, &authEvents); err != nil {
+	if err = gomatrixserverlib.Allowed(event.PDU, &authEvents, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+		return db.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+	}); err != nil {
 		// return true, nil
 		return true, err
 	}

roomserver/internal/input/input_events.go

@@ -128,7 +128,7 @@ func (r *Inputer) processRoomEvent(
 	if roomInfo == nil && !isCreateEvent {
 		return fmt.Errorf("room %s does not exist for event %s", event.RoomID(), event.EventID())
 	}
-	sender, err := event.UserID()
+	sender, err := r.DB.GetUserIDForSender(ctx, event.RoomID(), event.SenderID())
 	if err != nil {
 		return fmt.Errorf("event has invalid sender %q", event.SenderID())
 	}
@@ -276,7 +276,9 @@ 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.
-	if err = gomatrixserverlib.Allowed(event, &authEvents); err != nil {
+	if err = gomatrixserverlib.Allowed(event, &authEvents, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+		return r.DB.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+	}); err != nil {
 		isRejected = true
 		rejectionErr = err
 		logger.WithError(rejectionErr).Warnf("Event %s not allowed by auth events", event.EventID())
@@ -579,7 +581,9 @@ func (r *Inputer) processStateBefore(
 	stateBeforeAuth := gomatrixserverlib.NewAuthEvents(
 		gomatrixserverlib.ToPDUs(stateBeforeEvent),
 	)
-	if rejectionErr = gomatrixserverlib.Allowed(event, &stateBeforeAuth); rejectionErr != nil {
+	if rejectionErr = gomatrixserverlib.Allowed(event, &stateBeforeAuth, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+		return r.DB.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+	}); rejectionErr != nil {
 		rejectionErr = fmt.Errorf("Allowed() failed for stateBeforeEvent: %w", rejectionErr)
 		return
 	}
@@ -690,7 +694,9 @@ nextAuthEvent:
 		// Check the signatures of the event. If this fails then we'll simply
 		// skip it, because gomatrixserverlib.Allowed() will notice a problem
 		// if a critical event is missing anyway.
-		if err := gomatrixserverlib.VerifyEventSignatures(ctx, authEvent, r.FSAPI.KeyRing()); err != nil {
+		if err := gomatrixserverlib.VerifyEventSignatures(ctx, authEvent, r.FSAPI.KeyRing(), func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return r.DB.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+		}); err != nil {
 			continue nextAuthEvent
 		}
 
@@ -706,7 +712,9 @@ nextAuthEvent:
 		}
 
 		// Check if the auth event should be rejected.
-		err := gomatrixserverlib.Allowed(authEvent, auth)
+		err := gomatrixserverlib.Allowed(authEvent, auth, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return r.DB.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+		})
 		if isRejected = err != nil; isRejected {
 			logger.WithError(err).Warnf("Auth event %s rejected", authEvent.EventID())
 		}

roomserver/internal/input/input_events_test.go

@@ -58,7 +58,7 @@ func Test_EventAuth(t *testing.T) {
 	}
 
 	// Finally check that the event is NOT allowed
-	if err := gomatrixserverlib.Allowed(ev.PDU, &allower); err == nil {
+	if err := gomatrixserverlib.Allowed(ev.PDU, &allower, func(roomAliasOrID, senderID string) (*spec.UserID, error) { return spec.NewUserID(senderID, true) }); err == nil {
 		t.Fatalf("event should not be allowed, but it was")
 	}
 }

roomserver/internal/input/input_missing.go

@@ -473,14 +473,18 @@ func (t *missingStateReq) resolveStatesAndCheck(ctx context.Context, roomVersion
 		stateEventList = append(stateEventList, state.StateEvents...)
 	}
 	resolvedStateEvents, err := gomatrixserverlib.ResolveConflicts(
-		roomVersion, gomatrixserverlib.ToPDUs(stateEventList), gomatrixserverlib.ToPDUs(authEventList),
+		roomVersion, gomatrixserverlib.ToPDUs(stateEventList), gomatrixserverlib.ToPDUs(authEventList), func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return t.db.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+		},
 	)
 	if err != nil {
 		return nil, err
 	}
 	// apply the current event
 retryAllowedState:
-	if err = checkAllowedByState(backwardsExtremity, resolvedStateEvents); err != nil {
+	if err = checkAllowedByState(backwardsExtremity, resolvedStateEvents, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+		return t.db.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+	}); err != nil {
 		switch missing := err.(type) {
 		case gomatrixserverlib.MissingAuthEventError:
 			h, err2 := t.lookupEvent(ctx, roomVersion, backwardsExtremity.RoomID(), missing.AuthEventID, true)
@@ -565,7 +569,9 @@ func (t *missingStateReq) getMissingEvents(ctx context.Context, e gomatrixserver
 	// will be added and duplicates will be removed.
 	missingEvents := make([]gomatrixserverlib.PDU, 0, len(missingResp.Events))
 	for _, ev := range missingResp.Events.UntrustedEvents(roomVersion) {
-		if err = gomatrixserverlib.VerifyEventSignatures(ctx, ev, t.keys); err != nil {
+		if err = gomatrixserverlib.VerifyEventSignatures(ctx, ev, t.keys, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return t.db.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+		}); err != nil {
 			continue
 		}
 		missingEvents = append(missingEvents, t.cacheAndReturn(ev))
@@ -654,7 +660,9 @@ func (t *missingStateReq) lookupMissingStateViaState(
 	authEvents, stateEvents, err := gomatrixserverlib.CheckStateResponse(ctx, &fclient.RespState{
 		StateEvents: state.GetStateEvents(),
 		AuthEvents:  state.GetAuthEvents(),
-	}, roomVersion, t.keys, nil)
+	}, roomVersion, t.keys, nil, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+		return t.db.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+	})
 	if err != nil {
 		return nil, err
 	}
@@ -889,14 +897,16 @@ func (t *missingStateReq) lookupEvent(ctx context.Context, roomVersion gomatrixs
 		t.log.WithField("missing_event_id", missingEventID).Warnf("Failed to get missing /event for event ID from %d server(s)", len(t.servers))
 		return nil, fmt.Errorf("wasn't able to find event via %d server(s)", len(t.servers))
 	}
-	if err := gomatrixserverlib.VerifyEventSignatures(ctx, event, t.keys); err != nil {
+	if err := gomatrixserverlib.VerifyEventSignatures(ctx, event, t.keys, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+		return t.db.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+	}); err != nil {
 		t.log.WithError(err).Warnf("Couldn't validate signature of event %q from /event", event.EventID())
 		return nil, verifySigError{event.EventID(), err}
 	}
 	return t.cacheAndReturn(event), nil
 }
 
-func checkAllowedByState(e gomatrixserverlib.PDU, stateEvents []gomatrixserverlib.PDU) error {
+func checkAllowedByState(e gomatrixserverlib.PDU, stateEvents []gomatrixserverlib.PDU, userIDForSender spec.UserIDForSender) error {
 	authUsingState := gomatrixserverlib.NewAuthEvents(nil)
 	for i := range stateEvents {
 		err := authUsingState.AddEvent(stateEvents[i])
@@ -904,7 +914,7 @@ func checkAllowedByState(e gomatrixserverlib.PDU, stateEvents []gomatrixserverli
 			return err
 		}
 	}
-	return gomatrixserverlib.Allowed(e, &authUsingState)
+	return gomatrixserverlib.Allowed(e, &authUsingState, userIDForSender)
 }
 
 func (t *missingStateReq) hadEvent(eventID string) {

roomserver/internal/perform/perform_admin.go

@@ -262,13 +262,17 @@ func (r *Admin) PerformAdminDownloadState(
 			return fmt.Errorf("r.Inputer.FSAPI.LookupState (%q): %s", fwdExtremity, err)
 		}
 		for _, authEvent := range state.GetAuthEvents().UntrustedEvents(roomInfo.RoomVersion) {
-			if err = gomatrixserverlib.VerifyEventSignatures(ctx, authEvent, r.Inputer.KeyRing); err != nil {
+			if err = gomatrixserverlib.VerifyEventSignatures(ctx, authEvent, r.Inputer.KeyRing, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+				return r.DB.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+			}); err != nil {
 				continue
 			}
 			authEventMap[authEvent.EventID()] = authEvent
 		}
 		for _, stateEvent := range state.GetStateEvents().UntrustedEvents(roomInfo.RoomVersion) {
-			if err = gomatrixserverlib.VerifyEventSignatures(ctx, stateEvent, r.Inputer.KeyRing); err != nil {
+			if err = gomatrixserverlib.VerifyEventSignatures(ctx, stateEvent, r.Inputer.KeyRing, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+				return r.DB.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+			}); err != nil {
 				continue
 			}
 			stateEventMap[stateEvent.EventID()] = stateEvent

roomserver/internal/perform/perform_backfill.go

@@ -121,7 +121,9 @@ func (r *Backfiller) backfillViaFederation(ctx context.Context, req *api.Perform
 	// Specifically the test "Outbound federation can backfill events"
 	events, err := gomatrixserverlib.RequestBackfill(
 		ctx, req.VirtualHost, requester,
-		r.KeyRing, req.RoomID, info.RoomVersion, req.PrevEventIDs(), 100,
+		r.KeyRing, req.RoomID, info.RoomVersion, req.PrevEventIDs(), 100, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return r.DB.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+		},
 	)
 	// Only return an error if we really couldn't get any events.
 	if err != nil && len(events) == 0 {
@@ -210,7 +212,9 @@ func (r *Backfiller) fetchAndStoreMissingEvents(ctx context.Context, roomVer gom
 				continue
 			}
 			loader := gomatrixserverlib.NewEventsLoader(roomVer, r.KeyRing, backfillRequester, backfillRequester.ProvideEvents, false)
-			result, err := loader.LoadAndVerify(ctx, res.PDUs, gomatrixserverlib.TopologicalOrderByPrevEvents)
+			result, err := loader.LoadAndVerify(ctx, res.PDUs, gomatrixserverlib.TopologicalOrderByPrevEvents, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+				return r.DB.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+			})
 			if err != nil {
 				logger.WithError(err).Warn("failed to load and verify event")
 				continue
@@ -484,7 +488,7 @@ FindSuccessor:
 	// Store the server names in a temporary map to avoid duplicates.
 	serverSet := make(map[spec.ServerName]bool)
 	for _, event := range memberEvents {
-		if sender, err := event.UserID(); err == nil {
+		if sender, err := b.db.GetUserIDForSender(ctx, event.RoomID(), event.SenderID()); err == nil {
 			serverSet[sender.Domain()] = true
 		}
 	}

roomserver/internal/perform/perform_create_room.go

@@ -308,7 +308,9 @@ func (c *Creator) PerformCreateRoom(ctx context.Context, userID spec.UserID, roo
 			}
 		}
 
-		if err = gomatrixserverlib.Allowed(ev, &authEvents); err != nil {
+		if err = gomatrixserverlib.Allowed(ev, &authEvents, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return c.DB.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+		}); err != nil {
 			util.GetLogger(ctx).WithError(err).Error("gomatrixserverlib.Allowed failed")
 			return "", &util.JSONResponse{
 				Code: http.StatusInternalServerError,

roomserver/internal/perform/perform_invite.go

@@ -126,7 +126,7 @@ func (r *Inviter) PerformInvite(
 ) error {
 	event := req.Event
 
-	sender, err := event.UserID()
+	sender, err := r.DB.GetUserIDForSender(ctx, event.RoomID(), event.SenderID())
 	if err != nil {
 		return spec.InvalidParam("The sender user ID is invalid")
 	}
@@ -156,6 +156,9 @@ func (r *Inviter) PerformInvite(
 		StrippedState:     req.InviteRoomState,
 		MembershipQuerier: &api.MembershipQuerier{Roomserver: r.RSAPI},
 		StateQuerier:      &QueryState{r.DB},
+		UserIDQuerier: func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return r.DB.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+		},
 	}
 	inviteEvent, err := gomatrixserverlib.PerformInvite(ctx, input, r.FSAPI)
 	if err != nil {

roomserver/internal/perform/perform_upgrade.go

@@ -484,7 +484,9 @@ func (r *Upgrader) sendInitialEvents(ctx context.Context, evTime time.Time, user
 
 		}
 
-		if err = gomatrixserverlib.Allowed(event, &authEvents); err != nil {
+		if err = gomatrixserverlib.Allowed(event, &authEvents, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return r.URSAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+		}); err != nil {
 			return fmt.Errorf("Failed to auth new %q event: %w", builder.Type, err)
 		}
 
@@ -567,7 +569,9 @@ func (r *Upgrader) makeHeaderedEvent(ctx context.Context, evTime time.Time, user
 		stateEvents[i] = queryRes.StateEvents[i].PDU
 	}
 	provider := gomatrixserverlib.NewAuthEvents(stateEvents)
-	if err = gomatrixserverlib.Allowed(headeredEvent.PDU, &provider); err != nil {
+	if err = gomatrixserverlib.Allowed(headeredEvent.PDU, &provider, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+		return r.URSAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+	}); err != nil {
 		return nil, api.ErrNotAllowed{Err: fmt.Errorf("failed to auth new %q event: %w", proto.Type, err)} // TODO: Is this error string comprehensible to the client?
 	}
 

roomserver/internal/query/query.go

@@ -122,7 +122,9 @@ func (r *Queryer) QueryStateAfterEvents(
 		}
 
 		stateEvents, err = gomatrixserverlib.ResolveConflicts(
-			info.RoomVersion, gomatrixserverlib.ToPDUs(stateEvents), gomatrixserverlib.ToPDUs(authEvents),
+			info.RoomVersion, gomatrixserverlib.ToPDUs(stateEvents), gomatrixserverlib.ToPDUs(authEvents), func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+				return r.DB.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+			},
 		)
 		if err != nil {
 			return fmt.Errorf("state.ResolveConflictsAdhoc: %w", err)
@@ -349,7 +351,9 @@ func (r *Queryer) QueryMembershipsForRoom(
 			return fmt.Errorf("r.DB.Events: %w", err)
 		}
 		for _, event := range events {
-			clientEvent := synctypes.ToClientEvent(event.PDU, synctypes.FormatAll)
+			clientEvent := synctypes.ToClientEvent(event.PDU, synctypes.FormatAll, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+				return r.DB.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+			})
 			response.JoinEvents = append(response.JoinEvents, clientEvent)
 		}
 		return nil
@@ -398,7 +402,9 @@ func (r *Queryer) QueryMembershipsForRoom(
 	}
 
 	for _, event := range events {
-		clientEvent := synctypes.ToClientEvent(event.PDU, synctypes.FormatAll)
+		clientEvent := synctypes.ToClientEvent(event.PDU, synctypes.FormatAll, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return r.DB.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+		})
 		response.JoinEvents = append(response.JoinEvents, clientEvent)
 	}
 
@@ -588,7 +594,9 @@ func (r *Queryer) QueryStateAndAuthChain(
 
 	if request.ResolveState {
 		stateEvents, err = gomatrixserverlib.ResolveConflicts(
-			info.RoomVersion, gomatrixserverlib.ToPDUs(stateEvents), gomatrixserverlib.ToPDUs(authEvents),
+			info.RoomVersion, gomatrixserverlib.ToPDUs(stateEvents), gomatrixserverlib.ToPDUs(authEvents), func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+				return r.DB.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+			},
 		)
 		if err != nil {
 			return err
@@ -1036,15 +1044,9 @@ func (r *Queryer) QueryRestrictedJoinAllowed(ctx context.Context, req *api.Query
 }
 
 func (r *Queryer) QuerySenderIDForUser(ctx context.Context, roomAliasOrID string, userID spec.UserID) (string, error) {
-	// TODO: implement this properly with pseudoIDs
+	return r.DB.GetSenderIDForUser(ctx, roomAliasOrID, userID)
-	return userID.String(), nil
 }
 
-func (r *Queryer) QueryUserIDForSender(ctx context.Context, roomAliasOrID string, senderID string) (spec.UserID, error) {
+func (r *Queryer) QueryUserIDForSender(ctx context.Context, roomAliasOrID string, senderID string) (*spec.UserID, error) {
-	// TODO: implement this properly with pseudoIDs
+	return r.DB.GetUserIDForSender(ctx, roomAliasOrID, senderID)
-	userID, err := spec.NewUserID(senderID, true)
-	if err != nil {
-		return spec.UserID{}, err
-	}
-	return *userID, err
 }

roomserver/state/state.go

@@ -24,6 +24,7 @@ import (
 	"time"
 
 	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/gomatrixserverlib/spec"
 	"github.com/matrix-org/util"
 	"github.com/prometheus/client_golang/prometheus"
 
@@ -43,6 +44,7 @@ type StateResolutionStorage interface {
 	AddState(ctx context.Context, roomNID types.RoomNID, stateBlockNIDs []types.StateBlockNID, state []types.StateEntry) (types.StateSnapshotNID, error)
 	Events(ctx context.Context, roomVersion gomatrixserverlib.RoomVersion, eventNIDs []types.EventNID) ([]types.Event, error)
 	EventsFromIDs(ctx context.Context, roomInfo *types.RoomInfo, eventIDs []string) ([]types.Event, error)
+	GetUserIDForSender(ctx context.Context, roomAliasOrID string, senderID string) (*spec.UserID, error)
 }
 
 type StateResolution struct {
@@ -945,7 +947,9 @@ func (v *StateResolution) resolveConflictsV1(
 	}
 
 	// Resolve the conflicts.
-	resolvedEvents := gomatrixserverlib.ResolveStateConflicts(conflictedEvents, authEvents)
+	resolvedEvents := gomatrixserverlib.ResolveStateConflicts(conflictedEvents, authEvents, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+		return v.db.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+	})
 
 	// Map from the full events back to numeric state entries.
 	for _, resolvedEvent := range resolvedEvents {
@@ -1057,6 +1061,9 @@ func (v *StateResolution) resolveConflictsV2(
 			conflictedEvents,
 			nonConflictedEvents,
 			authEvents,
+			func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+				return v.db.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+			},
 		)
 	}()
 

roomserver/storage/interface.go

@@ -166,6 +166,10 @@ type Database interface {
 	GetServerInRoom(ctx context.Context, roomNID types.RoomNID, serverName spec.ServerName) (bool, error)
 	// GetKnownUsers searches all users that userID knows about.
 	GetKnownUsers(ctx context.Context, userID, searchString string, limit int) ([]string, error)
+	// GetKnownUsers tries to obtain the current mxid for a given user.
+	GetUserIDForSender(ctx context.Context, roomAliasOrID string, senderID string) (*spec.UserID, error)
+	// GetKnownUsers tries to obtain the current senderID for a given user.
+	GetSenderIDForUser(ctx context.Context, roomAliasOrID string, userID spec.UserID) (string, error)
 	// GetKnownRooms returns a list of all rooms we know about.
 	GetKnownRooms(ctx context.Context) ([]string, error)
 	// ForgetRoom sets a flag in the membership table, that the user wishes to forget a specific room
@@ -211,6 +215,7 @@ type RoomDatabase interface {
 	GetOrCreateEventTypeNID(ctx context.Context, eventType string) (eventTypeNID types.EventTypeNID, err error)
 	GetOrCreateEventStateKeyNID(ctx context.Context, eventStateKey *string) (types.EventStateKeyNID, error)
 	GetStateEvent(ctx context.Context, roomID, evType, stateKey string) (*types.HeaderedEvent, error)
+	GetUserIDForSender(ctx context.Context, roomAliasOrID string, senderID string) (*spec.UserID, error)
 }
 
 type EventDatabase interface {

roomserver/storage/shared/room_updater.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 
 	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/gomatrixserverlib/spec"
 
 	"github.com/matrix-org/dendrite/roomserver/types"
 )
@@ -250,3 +251,7 @@ func (u *RoomUpdater) MarkEventAsSent(eventNID types.EventNID) error {
 func (u *RoomUpdater) MembershipUpdater(targetUserNID types.EventStateKeyNID, targetLocal bool) (*MembershipUpdater, error) {
 	return u.d.membershipUpdaterTxn(u.ctx, u.txn, u.roomInfo.RoomNID, targetUserNID, targetLocal)
 }
+
+func (u *RoomUpdater) GetUserIDForSender(ctx context.Context, roomAliasOrID string, senderID string) (*spec.UserID, error) {
+	return u.d.GetUserIDForSender(ctx, roomAliasOrID, senderID)
+}

roomserver/storage/shared/storage.go

@@ -988,13 +988,15 @@ func (d *EventDatabase) MaybeRedactEvent(
 			return nil
 		}
 
+		// TODO: Don't hack senderID into userID here (pseudoIDs)
 		sender1Domain := ""
-		sender1, err1 := redactedEvent.UserID()
+		sender1, err1 := spec.NewUserID(redactedEvent.SenderID(), true)
 		if err1 == nil {
 			sender1Domain = string(sender1.Domain())
 		}
+		// TODO: Don't hack senderID into userID here (pseudoIDs)
 		sender2Domain := ""
-		sender2, err2 := redactionEvent.UserID()
+		sender2, err2 := spec.NewUserID(redactionEvent.SenderID(), true)
 		if err2 == nil {
 			sender2Domain = string(sender2.Domain())
 		}
@@ -1522,6 +1524,16 @@ func (d *Database) GetKnownUsers(ctx context.Context, userID, searchString strin
 	return d.MembershipTable.SelectKnownUsers(ctx, nil, stateKeyNID, searchString, limit)
 }
 
+func (d *Database) GetUserIDForSender(ctx context.Context, roomAliasOrID string, senderID string) (*spec.UserID, error) {
+	// TODO: Use real logic once DB for pseudoIDs is in place
+	return spec.NewUserID(senderID, true)
+}
+
+func (d *Database) GetSenderIDForUser(ctx context.Context, roomAliasOrID string, userID spec.UserID) (string, error) {
+	// TODO: Use real logic once DB for pseudoIDs is in place
+	return userID.String(), nil
+}
+
 // GetKnownRooms returns a list of all rooms we know about.
 func (d *Database) GetKnownRooms(ctx context.Context) ([]string, error) {
 	return d.RoomsTable.SelectRoomIDsWithEvents(ctx, nil)

setup/mscs/msc2836/msc2836.go

@@ -92,9 +92,11 @@ type MSC2836EventRelationshipsResponse struct {
 	ParsedAuthChain []gomatrixserverlib.PDU
 }
 
-func toClientResponse(res *MSC2836EventRelationshipsResponse) *EventRelationshipResponse {
+func toClientResponse(ctx context.Context, res *MSC2836EventRelationshipsResponse, rsAPI roomserver.RoomserverInternalAPI) *EventRelationshipResponse {
 	out := &EventRelationshipResponse{
-		Events:    synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(res.ParsedEvents), synctypes.FormatAll),
+		Events: synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(res.ParsedEvents), synctypes.FormatAll, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+		}),
 		Limited:   res.Limited,
 		NextBatch: res.NextBatch,
 	}
@@ -187,7 +189,7 @@ func eventRelationshipHandler(db Database, rsAPI roomserver.RoomserverInternalAP
 
 		return util.JSONResponse{
 			Code: 200,
-			JSON: toClientResponse(res),
+			JSON: toClientResponse(req.Context(), res, rsAPI),
 		}
 	}
 }

setup/mscs/msc2836/msc2836_test.go

@@ -525,6 +525,10 @@ type testRoomserverAPI struct {
 	events            map[string]*types.HeaderedEvent
 }
 
+func (r *testRoomserverAPI) QueryUserIDForSender(ctx context.Context, roomAliasOrID string, senderID string) (*spec.UserID, error) {
+	return spec.NewUserID(senderID, true)
+}
+
 func (r *testRoomserverAPI) QueryEventsByID(ctx context.Context, req *roomserver.QueryEventsByIDRequest, res *roomserver.QueryEventsByIDResponse) error {
 	for _, eventID := range req.EventIDs {
 		ev := r.events[eventID]

syncapi/routing/context.go

@@ -193,14 +193,20 @@ func Context(
 		}
 	}
 
-	eventsBeforeClient := synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(eventsBeforeFiltered), synctypes.FormatAll)
+	eventsBeforeClient := synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(eventsBeforeFiltered), synctypes.FormatAll, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
-	eventsAfterClient := synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(eventsAfterFiltered), synctypes.FormatAll)
+		return rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+	})
+	eventsAfterClient := synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(eventsAfterFiltered), synctypes.FormatAll, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+		return rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+	})
 
 	newState := state
 	if filter.LazyLoadMembers {
 		allEvents := append(eventsBeforeFiltered, eventsAfterFiltered...)
 		allEvents = append(allEvents, &requestedEvent)
-		evs := synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(allEvents), synctypes.FormatAll)
+		evs := synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(allEvents), synctypes.FormatAll, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+		})
 		newState, err = applyLazyLoadMembers(ctx, device, snapshot, roomID, evs, lazyLoadCache)
 		if err != nil {
 			logrus.WithError(err).Error("unable to load membership events")
@@ -211,12 +217,16 @@ func Context(
 		}
 	}
 
-	ev := synctypes.ToClientEvent(&requestedEvent, synctypes.FormatAll)
+	ev := synctypes.ToClientEvent(&requestedEvent, synctypes.FormatAll, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+		return rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+	})
 	response := ContextRespsonse{
 		Event:        &ev,
 		EventsAfter:  eventsAfterClient,
 		EventsBefore: eventsBeforeClient,
-		State:        synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(newState), synctypes.FormatAll),
+		State: synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(newState), synctypes.FormatAll, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+		}),
 	}
 
 	if len(response.State) > filter.Limit {

syncapi/routing/getevent.go

@@ -103,6 +103,8 @@ func GetEvent(
 
 	return util.JSONResponse{
 		Code: http.StatusOK,
-		JSON: synctypes.ToClientEvent(events[0], synctypes.FormatAll),
+		JSON: synctypes.ToClientEvent(events[0], synctypes.FormatAll, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return rsAPI.QueryUserIDForSender(req.Context(), roomAliasOrID, senderID)
+		}),
 	}
 }

syncapi/routing/memberships.go

@@ -153,6 +153,8 @@ func GetMemberships(
 	}
 	return util.JSONResponse{
 		Code: http.StatusOK,
-		JSON: getMembershipResponse{synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(result), synctypes.FormatAll)},
+		JSON: getMembershipResponse{synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(result), synctypes.FormatAll, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return rsAPI.QueryUserIDForSender(req.Context(), roomAliasOrID, senderID)
+		})},
 	}
 }

syncapi/routing/messages.go

@@ -241,7 +241,7 @@ func OnIncomingMessagesRequest(
 		device:           device,
 	}
 
-	clientEvents, start, end, err := mReq.retrieveEvents()
+	clientEvents, start, end, err := mReq.retrieveEvents(req.Context(), rsAPI)
 	if err != nil {
 		util.GetLogger(req.Context()).WithError(err).Error("mreq.retrieveEvents failed")
 		return util.JSONResponse{
@@ -273,7 +273,9 @@ func OnIncomingMessagesRequest(
 				JSON: spec.InternalServerError{},
 			}
 		}
-		res.State = append(res.State, synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(membershipEvents), synctypes.FormatAll)...)
+		res.State = append(res.State, synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(membershipEvents), synctypes.FormatAll, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return rsAPI.QueryUserIDForSender(req.Context(), roomAliasOrID, senderID)
+		})...)
 	}
 
 	// If we didn't return any events, set the end to an empty string, so it will be omitted
@@ -310,7 +312,7 @@ func getMembershipForUser(ctx context.Context, roomID, userID string, rsAPI api.
 // homeserver in the room for older events.
 // Returns an error if there was an issue talking to the database or with the
 // remote homeserver.
-func (r *messagesReq) retrieveEvents() (
+func (r *messagesReq) retrieveEvents(ctx context.Context, rsAPI api.SyncRoomserverAPI) (
 	clientEvents []synctypes.ClientEvent, start,
 	end types.TopologyToken, err error,
 ) {
@@ -382,7 +384,9 @@ func (r *messagesReq) retrieveEvents() (
 		"events_before": len(events),
 		"events_after":  len(filteredEvents),
 	}).Debug("applied history visibility (messages)")
-	return synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(filteredEvents), synctypes.FormatAll), start, end, err
+	return synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(filteredEvents), synctypes.FormatAll, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+		return rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+	}), start, end, err
 }
 
 func (r *messagesReq) getStartEnd(events []*rstypes.HeaderedEvent) (start, end types.TopologyToken, err error) {

syncapi/routing/relations.go

@@ -116,7 +116,9 @@ func Relations(
 	for _, event := range filteredEvents {
 		res.Chunk = append(
 			res.Chunk,
-			synctypes.ToClientEvent(event.PDU, synctypes.FormatAll),
+			synctypes.ToClientEvent(event.PDU, synctypes.FormatAll, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+				return rsAPI.QueryUserIDForSender(req.Context(), roomAliasOrID, senderID)
+			}),
 		)
 	}
 

syncapi/routing/routing.go

@@ -171,7 +171,7 @@ func Setup(
 				nb := req.FormValue("next_batch")
 				nextBatch = &nb
 			}
-			return Search(req, device, syncDB, fts, nextBatch)
+			return Search(req, device, syncDB, fts, nextBatch, rsAPI)
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
 

syncapi/routing/search.go

@@ -31,6 +31,7 @@ import (
 	"github.com/matrix-org/dendrite/clientapi/httputil"
 	"github.com/matrix-org/dendrite/internal/fulltext"
 	"github.com/matrix-org/dendrite/internal/sqlutil"
+	roomserverAPI "github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/dendrite/roomserver/types"
 	"github.com/matrix-org/dendrite/syncapi/storage"
 	"github.com/matrix-org/dendrite/syncapi/synctypes"
@@ -38,7 +39,7 @@ import (
 )
 
 // nolint:gocyclo
-func Search(req *http.Request, device *api.Device, syncDB storage.Database, fts fulltext.Indexer, from *string) util.JSONResponse {
+func Search(req *http.Request, device *api.Device, syncDB storage.Database, fts fulltext.Indexer, from *string, rsAPI roomserverAPI.SyncRoomserverAPI) util.JSONResponse {
 	start := time.Now()
 	var (
 		searchReq SearchRequest
@@ -225,14 +226,20 @@ func Search(req *http.Request, device *api.Device, syncDB storage.Database, fts
 
 		results = append(results, Result{
 			Context: SearchContextResponse{
-				Start:        startToken.String(),
+				Start: startToken.String(),
-				End:          endToken.String(),
+				End:   endToken.String(),
-				EventsAfter:  synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(eventsAfter), synctypes.FormatSync),
+				EventsAfter: synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(eventsAfter), synctypes.FormatSync, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
-				EventsBefore: synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(eventsBefore), synctypes.FormatSync),
+					return rsAPI.QueryUserIDForSender(req.Context(), roomAliasOrID, senderID)
-				ProfileInfo:  profileInfos,
+				}),
+				EventsBefore: synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(eventsBefore), synctypes.FormatSync, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+					return rsAPI.QueryUserIDForSender(req.Context(), roomAliasOrID, senderID)
+				}),
+				ProfileInfo: profileInfos,
 			},
-			Rank:   eventScore[event.EventID()].Score,
+			Rank: eventScore[event.EventID()].Score,
-			Result: synctypes.ToClientEvent(event, synctypes.FormatAll),
+			Result: synctypes.ToClientEvent(event, synctypes.FormatAll, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+				return rsAPI.QueryUserIDForSender(req.Context(), roomAliasOrID, senderID)
+			}),
 		})
 		roomGroup := groups[event.RoomID()]
 		roomGroup.Results = append(roomGroup.Results, event.EventID())
@@ -247,7 +254,9 @@ func Search(req *http.Request, device *api.Device, syncDB storage.Database, fts
 					JSON: spec.InternalServerError{},
 				}
 			}
-			stateForRooms[event.RoomID()] = synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(state), synctypes.FormatSync)
+			stateForRooms[event.RoomID()] = synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(state), synctypes.FormatSync, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+				return rsAPI.QueryUserIDForSender(req.Context(), roomAliasOrID, senderID)
+			})
 		}
 	}
 

syncapi/routing/search_test.go

@@ -2,6 +2,7 @@ package routing
 
 import (
 	"bytes"
+	"context"
 	"encoding/json"
 	"net/http"
 	"net/http/httptest"
@@ -9,6 +10,7 @@ import (
 
 	"github.com/matrix-org/dendrite/internal/fulltext"
 	"github.com/matrix-org/dendrite/internal/sqlutil"
+	rsapi "github.com/matrix-org/dendrite/roomserver/api"
 	rstypes "github.com/matrix-org/dendrite/roomserver/types"
 	"github.com/matrix-org/dendrite/syncapi/storage"
 	"github.com/matrix-org/dendrite/syncapi/synctypes"
@@ -21,6 +23,12 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
+type FakeSyncRoomserverAPI struct{ rsapi.SyncRoomserverAPI }
+
+func (f *FakeSyncRoomserverAPI) QueryUserIDForSender(ctx context.Context, roomAliasOrID string, senderID string) (*spec.UserID, error) {
+	return spec.NewUserID(senderID, true)
+}
+
 func TestSearch(t *testing.T) {
 	alice := test.NewUser(t)
 	aliceDevice := userapi.Device{UserID: alice.ID}
@@ -247,7 +255,7 @@ func TestSearch(t *testing.T) {
 				assert.NoError(t, err)
 				req := httptest.NewRequest(http.MethodPost, "/", reqBody)
 
-				res := Search(req, tc.device, db, fts, tc.from)
+				res := Search(req, tc.device, db, fts, tc.from, &FakeSyncRoomserverAPI{})
 				if !tc.wantOK && !res.Is2xx() {
 					return
 				}

syncapi/streams/stream_invite.go

@@ -10,6 +10,7 @@ import (
 
 	"github.com/matrix-org/gomatrixserverlib/spec"
 
+	"github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/dendrite/syncapi/storage"
 	"github.com/matrix-org/dendrite/syncapi/synctypes"
 	"github.com/matrix-org/dendrite/syncapi/types"
@@ -17,6 +18,7 @@ import (
 
 type InviteStreamProvider struct {
 	DefaultStreamProvider
+	rsAPI api.SyncRoomserverAPI
 }
 
 func (p *InviteStreamProvider) Setup(
@@ -66,7 +68,9 @@ func (p *InviteStreamProvider) IncrementalSync(
 		if _, ok := req.IgnoredUsers.List[inviteEvent.SenderID()]; ok {
 			continue
 		}
-		ir := types.NewInviteResponse(inviteEvent)
+		ir := types.NewInviteResponse(inviteEvent, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return p.rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+		})
 		req.Response.Rooms.Invite[roomID] = ir
 	}
 

syncapi/streams/stream_pdu.go

@@ -376,20 +376,28 @@ func (p *PDUStreamProvider) addRoomDeltaToResponse(
 			}
 		}
 		jr.Timeline.PrevBatch = &prevBatch
-		jr.Timeline.Events = synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(events), synctypes.FormatSync)
+		jr.Timeline.Events = synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(events), synctypes.FormatSync, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return p.rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+		})
 		// If we are limited by the filter AND the history visibility filter
 		// didn't "remove" events, return that the response is limited.
 		jr.Timeline.Limited = (limited && len(events) == len(recentEvents)) || delta.NewlyJoined
-		jr.State.Events = synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(delta.StateEvents), synctypes.FormatSync)
+		jr.State.Events = synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(delta.StateEvents), synctypes.FormatSync, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return p.rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+		})
 		req.Response.Rooms.Join[delta.RoomID] = jr
 
 	case spec.Peek:
 		jr := types.NewJoinResponse()
 		jr.Timeline.PrevBatch = &prevBatch
 		// TODO: Apply history visibility on peeked rooms
-		jr.Timeline.Events = synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(recentEvents), synctypes.FormatSync)
+		jr.Timeline.Events = synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(recentEvents), synctypes.FormatSync, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return p.rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+		})
 		jr.Timeline.Limited = limited
-		jr.State.Events = synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(delta.StateEvents), synctypes.FormatSync)
+		jr.State.Events = synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(delta.StateEvents), synctypes.FormatSync, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return p.rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+		})
 		req.Response.Rooms.Peek[delta.RoomID] = jr
 
 	case spec.Leave:
@@ -398,11 +406,15 @@ func (p *PDUStreamProvider) addRoomDeltaToResponse(
 	case spec.Ban:
 		lr := types.NewLeaveResponse()
 		lr.Timeline.PrevBatch = &prevBatch
-		lr.Timeline.Events = synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(events), synctypes.FormatSync)
+		lr.Timeline.Events = synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(events), synctypes.FormatSync, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return p.rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+		})
 		// If we are limited by the filter AND the history visibility filter
 		// didn't "remove" events, return that the response is limited.
 		lr.Timeline.Limited = limited && len(events) == len(recentEvents)
-		lr.State.Events = synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(delta.StateEvents), synctypes.FormatSync)
+		lr.State.Events = synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(delta.StateEvents), synctypes.FormatSync, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return p.rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+		})
 		req.Response.Rooms.Leave[delta.RoomID] = lr
 	}
 
@@ -552,11 +564,15 @@ func (p *PDUStreamProvider) getJoinResponseForCompleteSync(
 	}
 
 	jr.Timeline.PrevBatch = prevBatch
-	jr.Timeline.Events = synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(events), synctypes.FormatSync)
+	jr.Timeline.Events = synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(events), synctypes.FormatSync, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+		return p.rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+	})
 	// If we are limited by the filter AND the history visibility filter
 	// didn't "remove" events, return that the response is limited.
 	jr.Timeline.Limited = limited && len(events) == len(recentEvents)
-	jr.State.Events = synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(stateEvents), synctypes.FormatSync)
+	jr.State.Events = synctypes.ToClientEvents(gomatrixserverlib.ToPDUs(stateEvents), synctypes.FormatSync, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+		return p.rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+	})
 	return jr, nil
 }
 

syncapi/streams/streams.go

@@ -45,6 +45,7 @@ func NewSyncStreamProviders(
 		},
 		InviteStreamProvider: &InviteStreamProvider{
 			DefaultStreamProvider: DefaultStreamProvider{DB: d},
+			rsAPI:                 rsAPI,
 		},
 		SendToDeviceStreamProvider: &SendToDeviceStreamProvider{
 			DefaultStreamProvider: DefaultStreamProvider{DB: d},

syncapi/syncapi_test.go

@@ -40,6 +40,10 @@ type syncRoomserverAPI struct {
 	rooms []*test.Room
 }
 
+func (s *syncRoomserverAPI) QueryUserIDForSender(ctx context.Context, roomAliasOrID string, senderID string) (*spec.UserID, error) {
+	return spec.NewUserID(senderID, true)
+}
+
 func (s *syncRoomserverAPI) QueryLatestEventsAndState(ctx context.Context, req *rsapi.QueryLatestEventsAndStateRequest, res *rsapi.QueryLatestEventsAndStateResponse) error {
 	var room *test.Room
 	for _, r := range s.rooms {

syncapi/synctypes/clientevent.go

@@ -44,21 +44,21 @@ type ClientEvent struct {
 }
 
 // ToClientEvents converts server events to client events.
-func ToClientEvents(serverEvs []gomatrixserverlib.PDU, format ClientEventFormat) []ClientEvent {
+func ToClientEvents(serverEvs []gomatrixserverlib.PDU, format ClientEventFormat, userIDForSender spec.UserIDForSender) []ClientEvent {
 	evs := make([]ClientEvent, 0, len(serverEvs))
 	for _, se := range serverEvs {
 		if se == nil {
 			continue // TODO: shouldn't happen?
 		}
-		evs = append(evs, ToClientEvent(se, format))
+		evs = append(evs, ToClientEvent(se, format, userIDForSender))
 	}
 	return evs
 }
 
 // ToClientEvent converts a single server event to a client event.
-func ToClientEvent(se gomatrixserverlib.PDU, format ClientEventFormat) ClientEvent {
+func ToClientEvent(se gomatrixserverlib.PDU, format ClientEventFormat, userIDForSender spec.UserIDForSender) ClientEvent {
 	user := ""
-	userID, err := se.UserID()
+	userID, err := userIDForSender(se.RoomID(), se.SenderID())
 	if err == nil {
 		user = userID.String()
 	}

syncapi/synctypes/clientevent_test.go

@@ -21,8 +21,13 @@ import (
 	"testing"
 
 	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/gomatrixserverlib/spec"
 )
 
+func UserIDForSender(roomAliasOrID string, senderID string) (*spec.UserID, error) {
+	return spec.NewUserID(senderID, true)
+}
+
 func TestToClientEvent(t *testing.T) { // nolint: gocyclo
 	ev, err := gomatrixserverlib.MustGetRoomVersion(gomatrixserverlib.RoomVersionV1).NewEventFromTrustedJSON([]byte(`{
 		"type": "m.room.name",
@@ -43,7 +48,7 @@ func TestToClientEvent(t *testing.T) { // nolint: gocyclo
 	if err != nil {
 		t.Fatalf("failed to create Event: %s", err)
 	}
-	ce := ToClientEvent(ev, FormatAll)
+	ce := ToClientEvent(ev, FormatAll, UserIDForSender)
 	if ce.EventID != ev.EventID() {
 		t.Errorf("ClientEvent.EventID: wanted %s, got %s", ev.EventID(), ce.EventID)
 	}
@@ -63,7 +68,7 @@ func TestToClientEvent(t *testing.T) { // nolint: gocyclo
 		t.Errorf("ClientEvent.Unsigned: wanted %s, got %s", string(ev.Unsigned()), string(ce.Unsigned))
 	}
 	user := ""
-	userID, err := ev.UserID()
+	userID, err := UserIDForSender("", ev.SenderID())
 	if err == nil {
 		user = userID.String()
 	}
@@ -103,7 +108,7 @@ func TestToClientFormatSync(t *testing.T) {
 	if err != nil {
 		t.Fatalf("failed to create Event: %s", err)
 	}
-	ce := ToClientEvent(ev, FormatSync)
+	ce := ToClientEvent(ev, FormatSync, UserIDForSender)
 	if ce.RoomID != "" {
 		t.Errorf("ClientEvent.RoomID: wanted '', got %s", ce.RoomID)
 	}

syncapi/types/types.go

@@ -539,7 +539,7 @@ type InviteResponse struct {
 }
 
 // NewInviteResponse creates an empty response with initialised arrays.
-func NewInviteResponse(event *types.HeaderedEvent) *InviteResponse {
+func NewInviteResponse(event *types.HeaderedEvent, userIDForSender spec.UserIDForSender) *InviteResponse {
 	res := InviteResponse{}
 	res.InviteState.Events = []json.RawMessage{}
 
@@ -552,7 +552,7 @@ func NewInviteResponse(event *types.HeaderedEvent) *InviteResponse {
 
 	// Then we'll see if we can create a partial of the invite event itself.
 	// This is needed for clients to work out *who* sent the invite.
-	inviteEvent := synctypes.ToClientEvent(event.PDU, synctypes.FormatSync)
+	inviteEvent := synctypes.ToClientEvent(event.PDU, synctypes.FormatSync, userIDForSender)
 	inviteEvent.Unsigned = nil
 	if ev, err := json.Marshal(inviteEvent); err == nil {
 		res.InviteState.Events = append(res.InviteState.Events, ev)

syncapi/types/types_test.go

@@ -8,8 +8,13 @@ import (
 	"github.com/matrix-org/dendrite/roomserver/types"
 	"github.com/matrix-org/dendrite/syncapi/synctypes"
 	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/gomatrixserverlib/spec"
 )
 
+func UserIDForSender(roomAliasOrID string, senderID string) (*spec.UserID, error) {
+	return spec.NewUserID(senderID, true)
+}
+
 func TestSyncTokens(t *testing.T) {
 	shouldPass := map[string]string{
 		"s4_0_0_0_0_0_0_0_3": StreamingToken{4, 0, 0, 0, 0, 0, 0, 0, 3}.String(),
@@ -56,7 +61,7 @@ func TestNewInviteResponse(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	res := NewInviteResponse(&types.HeaderedEvent{PDU: ev})
+	res := NewInviteResponse(&types.HeaderedEvent{PDU: ev}, UserIDForSender)
 	j, err := json.Marshal(res)
 	if err != nil {
 		t.Fatal(err)

test/room.go

@@ -39,6 +39,10 @@ var (
 	roomIDCounter = int64(0)
 )
 
+func UserIDForSender(roomAliasOrID string, senderID string) (*spec.UserID, error) {
+	return spec.NewUserID(senderID, true)
+}
+
 type Room struct {
 	ID           string
 	Version      gomatrixserverlib.RoomVersion
@@ -195,7 +199,7 @@ func (r *Room) CreateEvent(t *testing.T, creator *User, eventType string, conten
 	if err != nil {
 		t.Fatalf("CreateEvent[%s]: failed to build event: %s", eventType, err)
 	}
-	if err = gomatrixserverlib.Allowed(ev, &r.authEvents); err != nil {
+	if err = gomatrixserverlib.Allowed(ev, &r.authEvents, UserIDForSender); err != nil {
 		t.Fatalf("CreateEvent[%s]: failed to verify event was allowed: %s", eventType, err)
 	}
 	headeredEvent := &rstypes.HeaderedEvent{PDU: ev}

userapi/consumers/roomserver.go

@@ -301,7 +301,9 @@ func (s *OutputRoomEventConsumer) processMessage(ctx context.Context, event *rst
 
 	switch {
 	case event.Type() == spec.MRoomMember:
-		cevent := synctypes.ToClientEvent(event, synctypes.FormatAll)
+		cevent := synctypes.ToClientEvent(event, synctypes.FormatAll, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+			return s.rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+		})
 		var member *localMembership
 		member, err = newLocalMembership(&cevent)
 		if err != nil {
@@ -534,7 +536,9 @@ func (s *OutputRoomEventConsumer) notifyLocal(ctx context.Context, event *rstype
 		// UNSPEC: the spec doesn't say this is a ClientEvent, but the
 		// fields seem to match. room_id should be missing, which
 		// matches the behaviour of FormatSync.
-		Event: synctypes.ToClientEvent(event, synctypes.FormatSync),
+		Event: synctypes.ToClientEvent(event, synctypes.FormatSync, func(roomAliasOrID string, senderID string) (*spec.UserID, error) {
+			return s.rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+		}),
 		// TODO: this is per-device, but it's not part of the primary
 		// key. So inserting one notification per profile tag doesn't
 		// make sense. What is this supposed to be? Sytests require it
@@ -616,7 +620,7 @@ func (s *OutputRoomEventConsumer) notifyLocal(ctx context.Context, event *rstype
 // user. Returns actions (including dont_notify).
 func (s *OutputRoomEventConsumer) evaluatePushRules(ctx context.Context, event *rstypes.HeaderedEvent, mem *localMembership, roomSize int) ([]*pushrules.Action, error) {
 	user := ""
-	userID, err := event.UserID()
+	userID, err := s.rsAPI.QueryUserIDForSender(ctx, event.RoomID(), event.SenderID())
 	if err == nil {
 		user = userID.String()
 	}
@@ -655,7 +659,9 @@ func (s *OutputRoomEventConsumer) evaluatePushRules(ctx context.Context, event *
 		roomSize: roomSize,
 	}
 	eval := pushrules.NewRuleSetEvaluator(ec, &ruleSets.Global)
-	rule, err := eval.MatchEvent(event.PDU)
+	rule, err := eval.MatchEvent(event.PDU, func(roomAliasOrID, senderID string) (*spec.UserID, error) {
+		return s.rsAPI.QueryUserIDForSender(ctx, roomAliasOrID, senderID)
+	})
 	if err != nil {
 		return nil, err
 	}

userapi/consumers/roomserver_test.go

@@ -14,6 +14,7 @@ import (
 	"github.com/stretchr/testify/assert"
 
 	"github.com/matrix-org/dendrite/internal/pushrules"
+	rsapi "github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/dendrite/setup/config"
 	"github.com/matrix-org/dendrite/test"
 	"github.com/matrix-org/dendrite/userapi/storage"
@@ -44,13 +45,19 @@ func mustCreateEvent(t *testing.T, content string) *types.HeaderedEvent {
 	return &types.HeaderedEvent{PDU: ev}
 }
 
+type FakeUserRoomserverAPI struct{ rsapi.UserRoomserverAPI }
+
+func (f *FakeUserRoomserverAPI) QueryUserIDForSender(ctx context.Context, roomAliasOrID string, senderID string) (*spec.UserID, error) {
+	return spec.NewUserID(senderID, true)
+}
+
 func Test_evaluatePushRules(t *testing.T) {
 	ctx := context.Background()
 
 	test.WithAllDatabases(t, func(t *testing.T, dbType test.DBType) {
 		db, close := mustCreateDatabase(t, dbType)
 		defer close()
-		consumer := OutputRoomEventConsumer{db: db}
+		consumer := OutputRoomEventConsumer{db: db, rsAPI: &FakeUserRoomserverAPI{}}
 
 		testCases := []struct {
 			name         string

userapi/util/notify_test.go

@@ -11,6 +11,7 @@ import (
 	"github.com/matrix-org/dendrite/internal/sqlutil"
 	"github.com/matrix-org/dendrite/syncapi/synctypes"
 	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/gomatrixserverlib/spec"
 	"github.com/matrix-org/util"
 	"golang.org/x/crypto/bcrypt"
 
@@ -22,6 +23,10 @@ import (
 	userUtil "github.com/matrix-org/dendrite/userapi/util"
 )
 
+func UserIDForSender(roomAliasOrID string, senderID string) (*spec.UserID, error) {
+	return spec.NewUserID(senderID, true)
+}
+
 func TestNotifyUserCountsAsync(t *testing.T) {
 	alice := test.NewUser(t)
 	aliceLocalpart, serverName, err := gomatrixserverlib.SplitID('@', alice.ID)
@@ -100,7 +105,7 @@ func TestNotifyUserCountsAsync(t *testing.T) {
 
 		// Insert a dummy event
 		if err := db.InsertNotification(ctx, aliceLocalpart, serverName, dummyEvent.EventID(), 0, nil, &api.Notification{
-			Event: synctypes.ToClientEvent(dummyEvent, synctypes.FormatAll),
+			Event: synctypes.ToClientEvent(dummyEvent, synctypes.FormatAll, UserIDForSender),
 		}); err != nil {
 			t.Error(err)
 		}