curl/docs/libcurl/opts/CURLOPT_PRE_PROXY.md
Daniel Stenberg e3fe020089
docs/libcurl: generate PROTOCOLS from meta-data
Remove the PROTOCOLS section from the source files completely and
instead generate them based on the header data in the curldown files.

It also generates TLS backend information for options marked for TLS as
protocol.

Closes #13175
2024-03-23 18:13:03 +01:00

2.3 KiB

c SPDX-License-Identifier Title Section Source See-also Protocol
Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al. curl CURLOPT_PRE_PROXY 3 libcurl
CURLOPT_HTTPPROXYTUNNEL (3)
CURLOPT_PROXY (3)
All

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.

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

DEFAULT

Default is NULL, meaning no pre proxy is used.

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

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 7.52.0

RETURN VALUE

Returns CURLE_OK if proxies are supported, CURLE_UNKNOWN_OPTION if not, or CURLE_OUT_OF_MEMORY if there was insufficient heap space.