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

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

SEE ALSO

       CURLOPT_HTTPPROXYTUNNEL(3), CURLOPT_PROXY(3)