访问 CSDN的下载频道-->我的资源 的时候，需要发送cookie，以下代码在本地搭建的php环境中，可以成功发送cookie信息，并获取网页源码。
但在访问CSDN的页面时候，无法返回数据，但是响应code是200，不清楚怎么回事，希望会的朋友帮忙看下。
注：我搞了一整天了，也百度google了好久，还是没法解决！
根据@ 依云 兄和 暗夜 网友的提示，使用http analyzer软件抓到了数据包，和火狐抓到的数据包对比如下：

网页访问的时候，抓到的数据包：

软件访问的时候，抓到的数据包（无法获取返回信息，代码贴在下方）：

注：对比可以发现，发送到服务端的数据包应该没错的~是不是代码哪里错了呢，我还是没检查出来呀

代码如下

 long writer(void *data, int size, int nmemb, string &content)
{
    long sizes = size * nmemb;
    string temp((char*)data,sizes);
    content += temp;
    return sizes;
}

int _tmain(int argc, _TCHAR* argv[])
{
    CURL *curl;
    CURLcode res;
    curl_global_init(CURL_GLOBAL_ALL);
    curl = curl_easy_init();
    if (curl) {
        curl_easy_setopt(curl,CURLOPT_VERBOSE,1);       //输出请求头和响应头
        curl_easy_setopt(curl,CURLOPT_HEADER,1);
        curl_easy_setopt(curl,CURLOPT_URL, "http://download.csdn.net/my/downloads/1");

        //curl_easy_setopt(curl,CURLOPT_ACCEPT_ENCODING, "gzip");//采用gzip压缩

        //http请求头
        struct curl_slist *headers = NULL;
        headers = curl_slist_append(headers,"Host: download.csdn.net");
        headers = curl_slist_append(headers,"User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:25.0) Gecko/20100101 Firefox/25.0");
        headers = curl_slist_append(headers,"Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");
        headers = curl_slist_append(headers,"Accept-Language: zh-cn,zh;q=0.8,en-us;q=0.5,en;q=0.3");
        //headers = curl_slist_append(headers,"Accept-Encoding: gzip, deflate");
        headers = curl_slist_append(headers,"Referer: http://www.csdn.net/");
        headers = curl_slist_append(headers,"Cookie: UserName=用户名; UserInfo=该cookie信息从浏览器就可以获取;");
        headers = curl_slist_append(headers,"Connection: keep-alive");
        headers = curl_slist_append(headers,"Cache-Control: max-age=0");

        curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);

        string error,content;
        //writer:回调函数
        res = curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writer);
        if (res != CURLE_OK)
            printf( "Failed to set writer [%s]\n", error);

        //回调函数的参数：content
        res = curl_easy_setopt(curl, CURLOPT_WRITEDATA, &content);
        if (res != CURLE_OK)
            printf( "Failed to set write data [%s]\n",error);

        res = curl_easy_perform(curl);
        if (res != CURLE_OK) {
            fprintf(stderr, "Curl perform failed: %s\n", curl_easy_strerror(res));
            return 1;
        }
        double length = 0;
        res = curl_easy_getinfo(curl, CURLINFO_CONTENT_LENGTH_DOWNLOAD , &length);

        FILE * file = fopen("test.html","wb");
        fseek(file,0,SEEK_SET);
        fwrite(content.c_str(),1,length,file);
        fclose(file);

        //释放资源
        curl_slist_free_all(headers);
    }
    curl_global_cleanup();
    getchar();
    return 0;
}