// should probably check for OPTIONS, HEAD, and TRACE
if (context.request.method !== "GET") {
  const originHeader = request.headers.get("Origin");
  const hostHeader = request.headers.get("Header");
  if (!originHeader || !hostHeader) {
    return new Response(null, {
     status: 403
    });
  }
  const originHostname = safeParseURL(originHeader).hostname;
  const hostHostname = safeParseURL(hostHeader).hostname;
  if (!originHostname || !hostHostname || originHostname !== hostHostname) {
    return new Response(null, {
     status: 403
    });  
  }
}