Implement MSC2946 over federation (#1722)

* Add fedsender dep on msc2946

* Add MSC2946Spaces to fsAPI

* Add exclude_rooms impl

* Implement fed spaces handler

* Use stripped state not room version

* Call federated spaces at the right time

4 files changed, 69 insertions, 0 deletions

diff --git a/federationsender/api/api.go b/federationsender/api/api.go
index e4d176b1..dfc2dd8a 100644
--- a/federationsender/api/api.go
+++ b/federationsender/api/api.go
@@ -22,6 +22,7 @@ type FederationClient interface {
 	GetEvent(ctx context.Context, s gomatrixserverlib.ServerName, eventID string) (res gomatrixserverlib.Transaction, err error)
 	GetServerKeys(ctx context.Context, matrixServer gomatrixserverlib.ServerName) (gomatrixserverlib.ServerKeys, error)
 	MSC2836EventRelationships(ctx context.Context, dst gomatrixserverlib.ServerName, r gomatrixserverlib.MSC2836EventRelationshipsRequest, roomVersion gomatrixserverlib.RoomVersion) (res gomatrixserverlib.MSC2836EventRelationshipsResponse, err error)
+	MSC2946Spaces(ctx context.Context, dst gomatrixserverlib.ServerName, roomID string, r gomatrixserverlib.MSC2946SpacesRequest) (res gomatrixserverlib.MSC2946SpacesResponse, err error)
 	LookupServerKeys(ctx context.Context, s gomatrixserverlib.ServerName, keyRequests map[gomatrixserverlib.PublicKeyLookupRequest]gomatrixserverlib.Timestamp) ([]gomatrixserverlib.ServerKeys, error)
 }
 
diff --git a/federationsender/internal/api.go b/federationsender/internal/api.go
index 407e7ffe..1de774ef 100644
--- a/federationsender/internal/api.go
+++ b/federationsender/internal/api.go
@@ -244,3 +244,17 @@ func (a *FederationSenderInternalAPI) MSC2836EventRelationships(
 	}
 	return ires.(gomatrixserverlib.MSC2836EventRelationshipsResponse), nil
 }
+
+func (a *FederationSenderInternalAPI) MSC2946Spaces(
+	ctx context.Context, s gomatrixserverlib.ServerName, roomID string, r gomatrixserverlib.MSC2946SpacesRequest,
+) (res gomatrixserverlib.MSC2946SpacesResponse, err error) {
+	ctx, cancel := context.WithTimeout(ctx, time.Minute)
+	defer cancel()
+	ires, err := a.doRequest(s, func() (interface{}, error) {
+		return a.federation.MSC2946Spaces(ctx, s, roomID, r)
+	})
+	if err != nil {
+		return res, err
+	}
+	return ires.(gomatrixserverlib.MSC2946SpacesResponse), nil
+}
diff --git a/federationsender/inthttp/client.go b/federationsender/inthttp/client.go
index fe98ff33..81d3fc51 100644
--- a/federationsender/inthttp/client.go
+++ b/federationsender/inthttp/client.go
@@ -33,6 +33,7 @@ const (
 	FederationSenderGetServerKeysPath      = "/federationsender/client/getServerKeys"
 	FederationSenderLookupServerKeysPath   = "/federationsender/client/lookupServerKeys"
 	FederationSenderEventRelationshipsPath = "/federationsender/client/msc2836eventRelationships"
+	FederationSenderSpacesSummaryPath      = "/federationsender/client/msc2946spacesSummary"
 )
 
 // NewFederationSenderClient creates a FederationSenderInternalAPI implemented by talking to a HTTP POST API.
@@ -449,3 +450,34 @@ func (h *httpFederationSenderInternalAPI) MSC2836EventRelationships(
 	}
 	return response.Res, nil
 }
+
+type spacesReq struct {
+	S      gomatrixserverlib.ServerName
+	Req    gomatrixserverlib.MSC2946SpacesRequest
+	RoomID string
+	Res    gomatrixserverlib.MSC2946SpacesResponse
+	Err    *api.FederationClientError
+}
+
+func (h *httpFederationSenderInternalAPI) MSC2946Spaces(
+	ctx context.Context, dst gomatrixserverlib.ServerName, roomID string, r gomatrixserverlib.MSC2946SpacesRequest,
+) (res gomatrixserverlib.MSC2946SpacesResponse, err error) {
+	span, ctx := opentracing.StartSpanFromContext(ctx, "MSC2946Spaces")
+	defer span.Finish()
+
+	request := spacesReq{
+		S:      dst,
+		Req:    r,
+		RoomID: roomID,
+	}
+	var response spacesReq
+	apiURL := h.federationSenderURL + FederationSenderSpacesSummaryPath
+	err = httputil.PostJSON(ctx, span, h.httpClient, apiURL, &request, &response)
+	if err != nil {
+		return res, err
+	}
+	if response.Err != nil {
+		return res, response.Err
+	}
+	return response.Res, nil
+}
diff --git a/federationsender/inthttp/server.go b/federationsender/inthttp/server.go
index 293fb420..be995111 100644
--- a/federationsender/inthttp/server.go
+++ b/federationsender/inthttp/server.go
@@ -329,4 +329,26 @@ func AddRoutes(intAPI api.FederationSenderInternalAPI, internalAPIMux *mux.Route
 			return util.JSONResponse{Code: http.StatusOK, JSON: request}
 		}),
 	)
+	internalAPIMux.Handle(
+		FederationSenderSpacesSummaryPath,
+		httputil.MakeInternalAPI("MSC2946SpacesSummary", func(req *http.Request) util.JSONResponse {
+			var request spacesReq
+			if err := json.NewDecoder(req.Body).Decode(&request); err != nil {
+				return util.MessageResponse(http.StatusBadRequest, err.Error())
+			}
+			res, err := intAPI.MSC2946Spaces(req.Context(), request.S, request.RoomID, request.Req)
+			if err != nil {
+				ferr, ok := err.(*api.FederationClientError)
+				if ok {
+					request.Err = ferr
+				} else {
+					request.Err = &api.FederationClientError{
+						Err: err.Error(),
+					}
+				}
+			}
+			request.Res = res
+			return util.JSONResponse{Code: http.StatusOK, JSON: request}
+		}),
+	)
 }