CURLOPT_HAPROXY_CLIENT_IP(3) Library Functions Manual
NAME
CURLOPT_HAPROXY_CLIENT_IP - set HAProxy PROXY protocol client IP
SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HAPROXY_CLIENT_IP,
char *client_ip);
DESCRIPTION
When this parameter is set to a valid IPv4 or IPv6 numerical address in
its printable ASCII string version, the library sends this as the
client address in the HAProxy PROXY protocol v1 header at beginning of
the connection.
The client address is reported upstream as the source and destination
address of the non-existing client connection (since 8.20.0).
This option is an alternative to CURLOPT_HAPROXYPROTOCOL(3) as that one
cannot use a specified address.
Using this option multiple times makes the last set string override the
previous ones. Set it to NULL to disable its use again.
The application does not have to keep the string around after setting
this option.
As with most libcurl options, the user of this option must make sure
that the correct data (address) is passed on. libcurl does little to no
verification.
Note that if you want to send a different HAProxy client IP in a
subsequent request, you need to make sure that it is done over a fresh
connection as libcurl does not send it again while reusing connections.
DEFAULT
NULL, no HAProxy header is sent
PROTOCOLS
This functionality affects all supported protocols
EXAMPLE
int main(void)
{
CURL *curl = curl_easy_init();
if(curl) {
CURLcode result;
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
curl_easy_setopt(curl, CURLOPT_HAPROXY_CLIENT_IP, "1.1.1.1");
result = curl_easy_perform(curl);
}
}
AVAILABILITY
Added in curl 8.2.0
RETURN VALUE
curl_easy_setopt(3) returns a CURLcode indicating success or error.
CURLE_OK (0) means everything was OK, non-zero means an error occurred,
see libcurl-errors(3).
SEE ALSO
CURLOPT_HAPROXYPROTOCOL(3), CURLOPT_PROXY(3)
libcurl 2026-06-09 CURLOPT_HAPROXY_CLIENT_IP(3)
curl 8.20.0 - Generated Tue Jun 9 15:48:11 CDT 2026