#include <curl/curl.h> CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SUPPRESS_CONNECT_HEADERS, long onoff);
Proxy CONNECT response headers can complicate header processing since it's essentially a separate set of headers. You can enable this option to suppress those headers.
For example let's assume an HTTPS URL is to be retrieved via CONNECT. On success there would normally be two sets of headers, and each header line sent to the header function and/or the write function. The data given to the callbacks would look like this:
HTTP/1.1 200 Connection established
{headers}...
HTTP/1.1 200 OK
Content-Type: application/json
{headers}...
{body}...
However by enabling this option the CONNECT response headers are suppressed, so the data given to the callbacks would look like this:
HTTP/1.1 200 OK
Content-Type: application/json
{headers}...
{body}...
CURL *curl = curl_easy_init();
if(curl) {
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
curl_easy_setopt(curl, CURLOPT_HEADER, 1L);
curl_easy_setopt(curl, CURLOPT_PROXY, "http://foo:3128");
curl_easy_setopt(curl, CURLOPT_HTTPPROXYTUNNEL, 1L);
curl_easy_setopt(curl, CURLOPT_SUPPRESS_CONNECT_HEADERS, 1L);
curl_easy_perform(curl);
/* always cleanup */
curl_easy_cleanup(curl);
}