php curl获取网页内容(IPV6下超时)的解决办法

<?php
/**
* IPV6下curl超时问题
*/
$ch = curl_init();
curl_setopt ($ch, CURLOPT_URL, $url);
curl_setopt ($ch, CURLOPT_RETURNTRANSFER, true);
//设置curl默认访问为IPv4
if(defined('CURLOPT_IPRESOLVE') && defined('CURL_IPRESOLVE_V4')){
curl_setopt($ch, CURLOPT_IPRESOLVE, CURL_IPRESOLVE_V4);
}
//设置curl请求连接时的最长秒数，如果设置为0，则无限
curl_setopt ($ch, CURLOPT_CONNECTTIMEOUT, $timeout);
//设置curl总执行动作的最长秒数，如果设置为0，则无限
curl_setopt ($ch, CURLOPT_TIMEOUT,$timeout*3);
$file_contents = curl_exec($ch);
curl_close($ch);