diff --git a/federationapi/routing/send_test.go b/federationapi/routing/send_test.go
index 9b9db873b..8bdf54c4a 100644
--- a/federationapi/routing/send_test.go
+++ b/federationapi/routing/send_test.go
@@ -9,7 +9,6 @@ import (
 	"time"
 
 	eduAPI "github.com/matrix-org/dendrite/eduserver/api"
-	fsAPI "github.com/matrix-org/dendrite/federationsender/api"
 	"github.com/matrix-org/dendrite/internal/test"
 	"github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/gomatrixserverlib"
@@ -85,6 +84,7 @@ func (o *testEDUProducer) InputReceiptEvent(
 }
 
 type testRoomserverAPI struct {
+	api.RoomserverInternalAPITrace
 	inputRoomEvents            []api.InputRoomEvent
 	queryMissingAuthPrevEvents func(*api.QueryMissingAuthPrevEventsRequest) api.QueryMissingAuthPrevEventsResponse
 	queryStateAfterEvents      func(*api.QueryStateAfterEventsRequest) api.QueryStateAfterEventsResponse
@@ -92,12 +92,6 @@ type testRoomserverAPI struct {
 	queryLatestEventsAndState  func(*api.QueryLatestEventsAndStateRequest) api.QueryLatestEventsAndStateResponse
 }
 
-func (t *testRoomserverAPI) PerformForget(ctx context.Context, req *api.PerformForgetRequest, resp *api.PerformForgetResponse) error {
-	return nil
-}
-
-func (t *testRoomserverAPI) SetFederationSenderAPI(fsAPI fsAPI.FederationSenderInternalAPI) {}
-
 func (t *testRoomserverAPI) InputRoomEvents(
 	ctx context.Context,
 	request *api.InputRoomEventsRequest,
@@ -109,43 +103,6 @@ func (t *testRoomserverAPI) InputRoomEvents(
 	}
 }
 
-func (t *testRoomserverAPI) PerformInvite(
-	ctx context.Context,
-	req *api.PerformInviteRequest,
-	res *api.PerformInviteResponse,
-) error {
-	return nil
-}
-
-func (t *testRoomserverAPI) PerformJoin(
-	ctx context.Context,
-	req *api.PerformJoinRequest,
-	res *api.PerformJoinResponse,
-) {
-}
-
-func (t *testRoomserverAPI) PerformPeek(
-	ctx context.Context,
-	req *api.PerformPeekRequest,
-	res *api.PerformPeekResponse,
-) {
-}
-
-func (t *testRoomserverAPI) PerformPublish(
-	ctx context.Context,
-	req *api.PerformPublishRequest,
-	res *api.PerformPublishResponse,
-) {
-}
-
-func (t *testRoomserverAPI) PerformLeave(
-	ctx context.Context,
-	req *api.PerformLeaveRequest,
-	res *api.PerformLeaveResponse,
-) error {
-	return nil
-}
-
 // Query the latest events and state for a room from the room server.
 func (t *testRoomserverAPI) QueryLatestEventsAndState(
 	ctx context.Context,
diff --git a/roomserver/api/api.go b/roomserver/api/api.go
index 2683918a8..fff61ed6f 100644
--- a/roomserver/api/api.go
+++ b/roomserver/api/api.go
@@ -126,6 +126,14 @@ type RoomserverInternalAPI interface {
 		response *QueryStateAndAuthChainResponse,
 	) error
 
+	// QueryAuthChain returns the entire auth chain for the event IDs given.
+	// Omits without error any missing auth events.
+	QueryAuthChain(
+		ctx context.Context,
+		request *QueryAuthChainRequest,
+		response *QueryAuthChainResponse,
+	) error
+
 	// QueryCurrentState retrieves the requested state events. If state events are not found, they will be missing from
 	// the response.
 	QueryCurrentState(ctx context.Context, req *QueryCurrentStateRequest, res *QueryCurrentStateResponse) error
diff --git a/roomserver/api/api_trace.go b/roomserver/api/api_trace.go
index e625fb04a..13c1fe1c0 100644
--- a/roomserver/api/api_trace.go
+++ b/roomserver/api/api_trace.go
@@ -315,6 +315,16 @@ func (t *RoomserverInternalAPITrace) QueryServerBannedFromRoom(ctx context.Conte
 	return err
 }
 
+func (t *RoomserverInternalAPITrace) QueryAuthChain(
+	ctx context.Context,
+	request *QueryAuthChainRequest,
+	response *QueryAuthChainResponse,
+) error {
+	err := t.Impl.QueryAuthChain(ctx, request, response)
+	util.GetLogger(ctx).WithError(err).Infof("QueryAuthChain req=%+v res=%+v", js(request), js(response))
+	return err
+}
+
 func js(thing interface{}) string {
 	b, err := json.Marshal(thing)
 	if err != nil {
diff --git a/roomserver/api/query.go b/roomserver/api/query.go
index 55922b7fe..43e562a98 100644
--- a/roomserver/api/query.go
+++ b/roomserver/api/query.go
@@ -275,6 +275,14 @@ type QueryPublishedRoomsResponse struct {
 	RoomIDs []string
 }
 
+type QueryAuthChainRequest struct {
+	EventIDs []string
+}
+
+type QueryAuthChainResponse struct {
+	AuthChain []*gomatrixserverlib.HeaderedEvent
+}
+
 type QuerySharedUsersRequest struct {
 	UserID         string
 	ExcludeRoomIDs []string
diff --git a/roomserver/internal/query/query.go b/roomserver/internal/query/query.go
index c9940c3c2..7346c7a77 100644
--- a/roomserver/internal/query/query.go
+++ b/roomserver/internal/query/query.go
@@ -716,3 +716,16 @@ func (r *Queryer) QueryServerBannedFromRoom(ctx context.Context, req *api.QueryS
 	res.Banned = r.ServerACLs.IsServerBannedFromRoom(req.ServerName, req.RoomID)
 	return nil
 }
+
+func (r *Queryer) QueryAuthChain(ctx context.Context, req *api.QueryAuthChainRequest, res *api.QueryAuthChainResponse) error {
+	chain, err := getAuthChain(ctx, r.DB.EventsFromIDs, req.EventIDs)
+	if err != nil {
+		return err
+	}
+	hchain := make([]*gomatrixserverlib.HeaderedEvent, len(chain))
+	for i := range chain {
+		hchain[i] = chain[i].Headered(chain[i].Version())
+	}
+	res.AuthChain = hchain
+	return nil
+}
diff --git a/roomserver/inthttp/client.go b/roomserver/inthttp/client.go
index f5b66ca6a..6e3b2c661 100644
--- a/roomserver/inthttp/client.go
+++ b/roomserver/inthttp/client.go
@@ -53,6 +53,7 @@ const (
 	RoomserverQuerySharedUsersPath             = "/roomserver/querySharedUsers"
 	RoomserverQueryKnownUsersPath              = "/roomserver/queryKnownUsers"
 	RoomserverQueryServerBannedFromRoomPath    = "/roomserver/queryServerBannedFromRoom"
+	RoomserverQueryAuthChainPath               = "/roomserver/queryAuthChain"
 )
 
 type httpRoomserverInternalAPI struct {
@@ -484,6 +485,16 @@ func (h *httpRoomserverInternalAPI) QueryKnownUsers(
 	return httputil.PostJSON(ctx, span, h.httpClient, apiURL, req, res)
 }
 
+func (h *httpRoomserverInternalAPI) QueryAuthChain(
+	ctx context.Context, req *api.QueryAuthChainRequest, res *api.QueryAuthChainResponse,
+) error {
+	span, ctx := opentracing.StartSpanFromContext(ctx, "QueryAuthChain")
+	defer span.Finish()
+
+	apiURL := h.roomserverURL + RoomserverQueryAuthChainPath
+	return httputil.PostJSON(ctx, span, h.httpClient, apiURL, req, res)
+}
+
 func (h *httpRoomserverInternalAPI) QueryServerBannedFromRoom(
 	ctx context.Context, req *api.QueryServerBannedFromRoomRequest, res *api.QueryServerBannedFromRoomResponse,
 ) error {
diff --git a/roomserver/inthttp/server.go b/roomserver/inthttp/server.go
index 2bc8f82df..9d0793cb1 100644
--- a/roomserver/inthttp/server.go
+++ b/roomserver/inthttp/server.go
@@ -441,4 +441,17 @@ func AddRoutes(r api.RoomserverInternalAPI, internalAPIMux *mux.Router) {
 			return util.JSONResponse{Code: http.StatusOK, JSON: &response}
 		}),
 	)
+	internalAPIMux.Handle(RoomserverQueryAuthChainPath,
+		httputil.MakeInternalAPI("queryAuthChain", func(req *http.Request) util.JSONResponse {
+			request := api.QueryAuthChainRequest{}
+			response := api.QueryAuthChainResponse{}
+			if err := json.NewDecoder(req.Body).Decode(&request); err != nil {
+				return util.MessageResponse(http.StatusBadRequest, err.Error())
+			}
+			if err := r.QueryAuthChain(req.Context(), &request, &response); err != nil {
+				return util.ErrorResponse(err)
+			}
+			return util.JSONResponse{Code: http.StatusOK, JSON: &response}
+		}),
+	)
 }