PHP site source code (for search engines)

function get_referer(){ 
$se = 0; 
$url = $_SERVER["HTTP_REFERER"]; //Gets the full source URL
$str = str_replace("http://","",$url); //Remove the HTTP: __
$strdomain = explode("/",$str); //Split into an array with /
$domain = $strdomain[0]; //Take the character before the first "/"
if(strstr($domain,'baidu.com')){ 
$se = 1; 
} 
else if(strstr($domain,'google.cn')){ 
$se = 1; 
} 
return $se; 
}