CURLOPT_PRE_PROXY - set pre-proxy to use
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PRE_PROXY, char *preproxy);
Set the preproxy
to use for the upcoming request. The parameter should be
a char * to a zero 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
. 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
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
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!
All except file://. Note that some protocols don't do very well over proxy.
CURL *curl = curl_easy_init();
curl_easy_setopt(curl, CURLOPT_URL, "http://example.com/file.txt");
curl_easy_setopt(curl, CURLOPT_PREPROXY, "socks4://socks-proxy:1080");
curl_easy_setopt(curl, CURLOPT_PROXY, "http://proxy:80");
Added in 7.52.0
Returns CURLE_OK if proxies are supported, CURLE_UNKNOWN_OPTION if not, or
CURLE_OUT_OF_MEMORY if there was insufficient heap space.