code: func GetAbsURL(req *http.Request) url.URL {
  	var result url.URL
  
  	if req.URL.IsAbs() {
  		return *req.URL
  	}
  
  	if domain := req.Header.Get("Origin"); domain != "" {
  		parseResult, _ := url.Parse(domain)
  		result = *parseResult
  	}
  
  	result.Parse(req.RequestURI)
  	return result
  }
docs: // GetAbsURL get absolute URL from request, refer: https://stackoverflow.com/questions/6899069/why-are-request-url-host-and-scheme-blank-in-the-development-server