curl/docs/libcurl/opts/CURLOPT_HAPROXY_CLIENT_IP.md
Daniel Stenberg 7e0a9b309c
CURLOPT_HAPROXY_CLIENT_IP.md: mention assuption on data format
The user is assumed to pass in correct data. I think we should start
clarifying this in more places.

Closes #21042
2026-03-21 14:46:55 +01:00

1.9 KiB

c SPDX-License-Identifier Title Section Source Protocol See-also Added-in
Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al. curl CURLOPT_HAPROXY_CLIENT_IP 3 libcurl
All
CURLOPT_HAPROXYPROTOCOL (3)
CURLOPT_PROXY (3)
8.2.0

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.

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%

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%

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).