function get_origin(headers) {
	const protocol = (protocol_header && headers[protocol_header]) || 'https';
	const host = headers[host_header];
	const port = port_header && headers[port_header];
	if (port) {
		return `${protocol}://${host}:${port}`;
	} else {
		return `${protocol}://${host}`;
	}
}
@param {import('http').IncomingHttpHeaders} headers
@returns