php短域名转换为实际域名函数

$url = "http://sinaurl.cn/hbdsU5"; 
echo unshorten($url); 
function unshorten($url) { 
$url = trim($url); 
$headers = get_headers($url); 
$location = $url; 
$short = false; 
foreach($headers as $head) { 
if($head=="HTTP/1.1 302 Found") $short = true; 
if($short && startwith($head,"Location: ")) { 
$location = substr($head,10); 
} 
} 
return $location; 
} 
function startwith($Haystack, $Needle){ 
return strpos($Haystack, $Needle) === 0; 
}