如何使用curl和php连接到安全（https）代理？

现代浏览器支持可通过PAC文件连接的HTTPS代理（请参阅 https://www.igvita.com/2012/06/25/spdy-and-secure-proxy-support-in-google-chrome/ （如果您不熟悉） ）。

Modern browsers support HTTPS proxies that can be connected to via a PAC file (see https://www.igvita.com/2012/06/25/spdy-and-secure-proxy-support-in-google-chrome/ if you're not familiar).

我试图复制同样的东西，并通过php CURL连接到这样的代理，但我只是得到一个空响应，没有标题或内容。

I'm trying to replicate the same thing and connect to such a proxy via php CURL, but I'm simply getting a blank response, no headers or content.

我的代码如下：

$url = "http://checkip.dyndns.com";
$proxy = "proxy.domain.com:443";

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_TIMEOUT, 10);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_HEADER, 1);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 0);
curl_setopt($ch, CURLOPT_HTTPPROXYTUNNEL , 1);
curl_setopt($ch, CURLOPT_PROXY, $proxy);
curl_setopt($ch, CURLOPT_PROXYUSERPWD, 'test:test');
curl_setopt($ch, CURLOPT_PROXYTYPE, "CURLPROXY_HTTP");
$response = curl_exec($ch);
curl_close($ch);

echo $response;

任何想法？