php判断用户浏览器类型与来自页面

function chkre(){
 global $_SERVER, $r_main;
 if(isset($_SERVER['HTTP_REFERER'])){
  $u=parse_url($_SERVER['HTTP_REFERER']);
  if($u['host']!=$_SERVER['HTTP_HOST'])return false;
 }
 return true;
}

function chkuag($a='MSIE'){
 global $_SERVER;
 if(isset($_SERVER['HTTP_USER_AGENT'])){
  $age=strtoupper($_SERVER['HTTP_USER_AGENT']);
  if(strstr($age, $a))return true;
 }
 return false;
}