使用libcurl和ntml时出现错误http 407

我正在开发一个小型应用程序。为了测试目的，我试图在ntlm代理后面使用libcurl"ping"谷歌。这是我的c++代码：

CURLcode testConnection(void)
{
    CURL *curl;
    CURLcode res = CURLE_OK;
    res = curl_global_init(CURL_GLOBAL_ALL);
    curl = curl_easy_init();
    if (curl)
    {
        cout << "Url: " << curl_easy_strerror(curl_easy_setopt(curl, CURLOPT_URL, "http://www.google.com")) << "n";
        cout << "T-out: " << curl_easy_strerror(curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, 3)) << "n";
        cout << "No_body: " << curl_easy_strerror(curl_easy_setopt(curl, CURLOPT_NOBODY, true)) << "n";
        cout << "Proxy Url: " << curl_easy_strerror(curl_easy_setopt(curl, CURLOPT_PROXY, "proxyrm.wind.root.it")) << "n";
        cout << "Proxy Port: " << curl_easy_strerror(curl_easy_setopt(curl, CURLOPT_PROXYPORT, 8080)) << "n";
        cout << "Ntml: " << curl_easy_strerror(curl_easy_setopt(curl, CURLOPT_HTTPAUTH, CURLAUTH_NTLM)) << "n";
        cout << "Verbose: " << curl_easy_strerror(curl_easy_setopt(curl, CURLOPT_VERBOSE, true)) << "n";
        res = curl_easy_perform(curl);
        curl_easy_cleanup(curl);
    }
    else
        res = CURLE_FAILED_INIT;
    curl_global_cleanup();
    return res;
}

所有这些都很好，因为详细的输出如下。

Url: No error
T-out: No error
No_body: No error
Proxy Url: No error
Proxy Port: No error
Ntml: No error
Verbose: No error
* About to connect() to proxy myroxy  port 8080 (#0)
*   Trying IP...
* Connected to myroxy   (IP) port 8080 (#0)
> HEAD http://www.google.com HTTP/1.1
Host: www.google.com
Accept: */*
Proxy-Connection: Keep-Alive
< HTTP/1.1 407 Proxy Authentication Required
< Proxy-Authenticate: NTLM
< Proxy-Authenticate: BASIC realm="windroot"
< Cache-Control: no-cache
< Pragma: no-cache
< Content-Type: text/html; charset=utf-8
* HTTP/1.1 proxy connection set close!
< Proxy-Connection: close
< Set-Cookie: BCSI-CS-602d36a7505d346e=2; Path=/
< Connection: close
< Content-Length: 989
<
* Closing connection 0
Curl Final: No error

但是，如果我尝试pinghttps://google.com结果变成这个

Url: No error
T-out: No error
No_body: No error
Proxy Url: No error
Proxy Port: No error
Ntml: No error
Ntml: No error
Ntml: No error
Verbose: No error
* About to connect() to proxy myroxy port 8080 (#0
*   Trying IP...
* Connected to myroxy  (IP) port 8080 (#0)
* Establish HTTP proxy tunnel to www.google.com:443
> CONNECT www.google.com:443 HTTP/1.1
Host: www.google.com:443
Proxy-Connection: Keep-Alive
< HTTP/1.1 407 Proxy Authentication Required
< Proxy-Authenticate: NTLM
< Proxy-Authenticate: BASIC realm="windroot"
< Cache-Control: no-cache
< Pragma: no-cache
< Content-Type: text/html; charset=utf-8
< Proxy-Connection: close
< Set-Cookie: BCSI-CS-602d36a7505d346e=2; Path=/
< Connection: close
< Content-Length: 1135
<
* Ignore 1135 bytes of response-body
* Received HTTP code 407 from proxy after CONNECT
* Connection #0 to host myroxy left intact
Curl Final: Failure when receiving data from the peer

在命令行中使用curl可以ping https（我必须指定-k参数），但我不知道这是否真的相关。有人能帮我弄清楚发生了什么？如何避免这种情况？