php中XMLHttpRequest(Ajax)不能设置自定义的Referer的解决方法

<?php
$dn = $_get['dn']; // 域名, 不包括www
$ex = $_get['ex']; // *域名, 如 .com, .cn, 包括最前面的.
// 查询域名是否已经注册
$url = 'http://pandavip.www.net.cn/check/check_ac1.cgi';
$ch = curl_init($url);
curl_setopt($ch, curlopt_post, true); // post
curl_setopt($ch, curlopt_postfields, 'domain='.$dn.$ex);
curl_setopt($ch, curlopt_useragent, 'mozilla/5.0 (windows nt 6.1; wow64; rv:8.0) gecko/20100101 firefox/8.0');
curl_setopt($ch, curlopt_cookie, '__utma=1.1486902564.1322109246.1322109246.1322109246.1; __utmz=1.1322109246.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); adsource=google%u641c%u7d22; adwordid=gg96011009070005; __utmc=1');
curl_setopt($ch, curlopt_httpheader, array(
'x-requested-with' => 'xmlhttprequest', // 设置为ajax方式
'referer' => 'http://pandavip.www.net.cn/cgi-bin/check.cgi?querytype=0&domain1='.$dn.'&image.x=0&image.y=0&domain='.$dn.'&big5=n&sign=2&url=www.net.cn&'.trim($ex, '.').'=yes' // 冒名顶替, 嘿嘿
));
curl_exec($ch); // 将查询结果返回前端, 用js处理