CURLOPT_PRE_PROXY(3)       curl_easy_setopt options       CURLOPT_PRE_PROXY(3)

NAME
       CURLOPT_PRE_PROXY - set pre-proxy 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 host name 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 _PROXYPORT&section=3">CURLOPT_PROXYPORT(3). If not specified, libcurl will
       default 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 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) will explicitly
       disable 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 host name to use, do not assume that there's any
       particular single port number used widely for proxies. Specify it!

PROTOCOLS
       All except file://. Note that some protocols don't do very well over
       proxy.

EXAMPLE
       CURL *curl = curl_easy_init();
       if(curl) {
         curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/file.txt");
         curl_easy_setopt(curl, CURLOPT_PREPROXY, "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.

SEE ALSO
       CURLOPT_PROXY(3), CURLOPT_HTTPPROXYTUNNEL(3),

libcurl 7.77.0                 November 4, 2020           CURLOPT_PRE_PROXY(3)