php 根据网址获ip

<?php 

if(isset($_GET['url'])){ 
 
$myWebSite = ($_GET['url']); 

$ip = gethostbyname($myWebSite); 

$result = '<?xml version="1.0" encoding="gb2312"?>
<xml><item><domain>'.$myWebSite.'</domain><IP>'.$ip.'</IP></item></xml>';
echo $result;
}else{ 

    echo"输入网站域名订阅域名对应IP"; 
    echo"<form action='' method='get'>"; 
    echo "域名 : <input name='url' value=''>"; 
    echo"<input type='submit' name='Submit' value='订阅'>"; 
    echo"</form>"; 
}  
?>