Check token Golang middleware

checktoken.go

// ChkTok is middleware that validates that the required
// security token is present.
func ChkTok(handler http.HandlerFunc) http.HandlerFunc {
	return func(rw http.ResponseWriter, req *http.Request) {
		sessionid := req.Header.Get(AUTHTOKEN)
		if sessionid == "" {
			util.WriteNewWebError(rw, http.StatusForbidden, "U-107", "x-anet-token is required.")
			return
		}
		handler(rw, req)
	}
}