Provided by: libcurl4-doc_7.55.1-1ubuntu2_all bug

NAME

       CURLOPT_HTTPPROXYTUNNEL - tunnel through HTTP proxy

SYNOPSIS

       #include <curl/curl.h>

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HTTPPROXYTUNNEL, long tunnel);

DESCRIPTION

       Set  the  tunnel  parameter  to  1L to make libcurl tunnel all operations through the HTTP
       proxy (set with CURLOPT_PROXY(3)). There is a big difference between using a proxy and  to
       tunnel through it.

       Tunneling  means that a HTTP CONNECT request is sent to the proxy, asking it to connect to
       a remote host on a specific port number and then the traffic is just  passed  through  the
       proxy.  Proxies tend to white-list specific port numbers it allows CONNECT requests to and
       often only port 80 and 443 are allowed.

       To   suppress   proxy   CONNECT    response    headers    from    user    callbacks    use
       CURLOPT_SUPPRESS_CONNECT_HEADERS(3).

       HTTP  proxies  can  generally  only  speak HTTP (for obvious reasons), which makes libcurl
       convert non-HTTP requests to HTTP when using an HTTP proxy without this tunnel option set.
       For  example, asking for an FTP URL and specifying an HTTP proxy will make libcurl send an
       FTP URL in a HTTP GET request to the proxy. By instead tunneling through  the  proxy,  you
       avoid that conversion (that rarely works through the proxy anyway).

DEFAULT

       0

PROTOCOLS

       All network protocols

EXAMPLE

       CURL *curl = curl_easy_init();
       if(curl) {
         curl_easy_setopt(curl, CURLOPT_URL, "ftp://example.com/file.txt");
         curl_easy_setopt(curl, CURLOPT_PROXY, "http://127.0.0.1:80");
         curl_easy_setopt(curl, CURLOPT_HTTPPROXYTUNNEL, 1L);
         curl_easy_perform(curl);
       }

AVAILABILITY

       Always

RETURN VALUE

       Returns CURLE_OK

SEE ALSO

       CURLOPT_PROXY(3), CURLOPT_PROXYTYPE(3), CURLOPT_PROXYPORT(3),