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.

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)