Tribblix: manual page: CURLOPT_PRE

CURLOPT_PRE_PROXY(3) Introduction to Library Functions CURLOPT_PRE_PROXY(3)

NAME

CURLOPT_PRE_PROXY - pre-proxy host to use

SYNOPSIS

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PRE_PROXY, char *preproxy);

DESCRIPTION

Set the preproxy to use for the upcoming request. The parameter
should be a char * to a null-terminated string holding the hostname
or dotted numerical IP address. A numerical IPv6 address must be
written within [brackets].

To specify port number in this string, append :[port] to the end of
the host name. The proxy's port number may optionally be specified
with the separate option CURLOPT_PROXYPORT(3). If not specified,
libcurl defaults to using port 1080 for proxies.

A pre proxy is a SOCKS proxy that curl connects to before it connects
to the HTTP(S) proxy specified in the CURLOPT_PROXY(3) option. The
pre proxy can only be a SOCKS proxy.

The pre proxy string should be prefixed with [scheme]:// to specify
which kind of socks is used. Use socks4://, socks4a://, socks5:// or
socks5h:// (the last one to enable socks5 and asking the proxy to do
the resolving, also known as CURLPROXY_SOCKS5_HOSTNAME type) to
request the specific SOCKS version to be used. Otherwise SOCKS4 is
used as default.

Setting the pre proxy string to "" (an empty string) explicitly
disables the use of a pre proxy.

When you set a hostname to use, do not assume that there is any
particular single port number used widely for proxies. Specify it.

The application does not have to keep the string around after setting
this option.

Using this option multiple times makes the last set string override
the previous ones. Set it to NULL to disable its use again.

DEFAULT

NULL

PROTOCOLS

This functionality affects all supported protocols

EXAMPLE

int main(void)
{
CURL *curl = curl_easy_init();
if(curl) {
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/file.txt");
curl_easy_setopt(curl, CURLOPT_PRE_PROXY, "socks4://socks-proxy:1080");
curl_easy_setopt(curl, CURLOPT_PROXY, "http://proxy:80");
curl_easy_perform(curl);
}
}

AVAILABILITY

Added in curl 7.52.0

RETURN VALUE

curl_easy_setopt(3) returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error
occurred, see libcurl-errors(3).