php中用于检测一个地理IP地址是否可用的代码

/******************************************** 
* 
* 函数名：curl_string ($url,$proxy) 
* 作 用：检测代理IP地址 
* 作 者：李飞麟 
* 日 期：2011-11-09 
* 
********************************************/ 
function curl_string ($url,$proxy) 
{ 
$user_agent = "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh- CN; rv:1.9.0.5) Gecko/2008120122 Firefox/3.0.5 FirePHP/0.2.1"; 
$ch = curl_init(); 
curl_setopt ($ch, CURLOPT_PROXY, $proxy); 
curl_setopt ($ch, CURLOPT_URL, $url);//设置要访问的IP 
curl_setopt ($ch, CURLOPT_USERAGENT, $user_agent);//模拟用户使用的浏览器 
@curl_setopt ( $ch, CURLOPT_FOLLOWLOCATION, 1 ); // 使用自动跳转 
curl_setopt ( $ch, CURLOPT_TIMEOUT, 120 ); //设置超时时间 
curl_setopt ( $ch, CURLOPT_AUTOREFERER, 1 ); // 自动设置Referer curl_setopt ($ch, CURLOPT_COOKIEJAR, 'c:\cookie.txt'); 
curl_setopt ($ch, CURLOPT_HEADER, 1); 
curl_setopt ($ch, CURLOPT_RETURNTRANSFER, 1); 
curl_setopt ($ch, CURLOPT_FOLLOWLOCATION, 1); 
curl_setopt ($ch, CURLOPT_TIMEOUT, 10); 
$result = curl_exec($ch); 
// Check if any error occured 
if( $result === false) 
{ 
error_log(date("H:i:s") . ' Curl 失败: ' . curl_error($ch) ." -- ". $proxy."\n", 3, MYMEDIA.'/log/'.date('Y-m-d').'_Err.log'); 
}else{ 
error_log(date("H:i:s") . ' Curl 成功: ' . $proxy."\n", 3, MYMEDIA.'/log/'.date('Y-m-d').'_OK.log'); 
} 
curl_close($ch); 
return $result; 
}