PHP jump function and obtain the URL address of the current page

function url_this(){ 
        $url = "http://".$_server ["http_host"].$_server["request_uri"]; 
        $return_url = "<a href="//m.sbmmt.com/">; 
        return $return_url; 
    } 
 
//跳转函数 
function url_redirect($url,$delay=&#39;&#39;){ 
 if($delay == &#39;&#39;){ 
  echo "<script>window.location.href="//m.sbmmt.com/">; 
 }else{//开源代码phpfensi.com 
  echo "<meta http-equiv=&#39;refresh&#39; content=&#39;$delay;url=$url&#39; />"; 
 } 
 
} 
 
} //end func