CURLOPT_HTTPPROXYTUNNEL(3) curl_easy_setopt options CURLOPT_HTTPPROXYTUNNEL(3)
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 dif-
ference between using a proxy and to tunnel through it.
Tunneling means that an HTTP CONNECT request is sent to the proxy, ask-
ing 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 CUR-
LOPT_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
an 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),
libcurl 7.81.0 November 26, 2021 CURLOPT_HTTPPROXYTUNNEL(3)
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