Function SendJoin

federationapi/routing/join.go:180–433

SendJoin implements the /send_join API The make-join send-join dance makes much more sense as a single flow so the cyclomatic complexity is high: nolint:gocyclo

(
	httpReq *http.Request,
	request *gomatrixserverlib.FederationRequest,
	cfg *config.FederationAPI,
	rsAPI api.FederationRoomserverAPI,
	keys gomatrixserverlib.JSONVerifier,
	roomID, eventID string,
)

// flow so the cyclomatic complexity is high:
// nolint:gocyclo
func SendJoin(
	httpReq *http.Request,
	request *gomatrixserverlib.FederationRequest,
	cfg *config.FederationAPI,
	rsAPI api.FederationRoomserverAPI,
	keys gomatrixserverlib.JSONVerifier,
	roomID, eventID string,
) util.JSONResponse {
	verReq := api.QueryRoomVersionForRoomRequest{RoomID: roomID}
	verRes := api.QueryRoomVersionForRoomResponse{}
	if err := rsAPI.QueryRoomVersionForRoom(httpReq.Context(), &verReq, &verRes); err != nil {
		util.GetLogger(httpReq.Context()).WithError(err).Error("rsAPI.QueryRoomVersionForRoom failed")
		return util.JSONResponse{
			Code: http.StatusInternalServerError,
			JSON: jsonerror.InternalServerError(),
		}
	}

	event, err := gomatrixserverlib.NewEventFromUntrustedJSON(request.Content(), verRes.RoomVersion)
	if err != nil {
		return util.JSONResponse{
			Code: http.StatusBadRequest,
			JSON: jsonerror.BadJSON("The request body could not be decoded into valid JSON: " + err.Error()),
		}
	}

	// Check that the event is from the server sending the request.
	if event.Origin() != request.Origin() {
		return util.JSONResponse{
			Code: http.StatusForbidden,
			JSON: jsonerror.Forbidden("The join must be sent by the server it originated on"),
		}
	}

	// Check that a state key is provided.
	if event.StateKey() == nil || event.StateKeyEquals("") {
		return util.JSONResponse{
			Code: http.StatusBadRequest,
			JSON: jsonerror.BadJSON("No state key was provided in the join event."),
		}
	}
	if !event.StateKeyEquals(event.Sender()) {
		return util.JSONResponse{
			Code: http.StatusBadRequest,
			JSON: jsonerror.BadJSON("Event state key must match the event sender."),
		}
	}

	// 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.
	var domain gomatrixserverlib.ServerName
	if _, domain, err = gomatrixserverlib.SplitID('@', event.Sender()); err != nil {
		return util.JSONResponse{
			Code: http.StatusForbidden,
			JSON: jsonerror.Forbidden("The sender of the join is invalid"),
		}
	} else if domain != request.Origin() {