.\" generated by cd2nroff 0.1 from CURLOPT_HEADEROPT.md
.TH CURLOPT_HEADEROPT 3 "2025-06-27" libcurl
.SH NAME
CURLOPT_HEADEROPT \- send HTTP headers to both proxy and host or separately
.SH SYNOPSIS
.nf
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HEADEROPT, long bitmask);
.fi
.SH DESCRIPTION
Pass a long that is a bitmask of options of how to deal with headers. The two
mutually exclusive options are:

\fBCURLHEADER_UNIFIED\fP \- the headers specified in
\fICURLOPT_HTTPHEADER(3)\fP are used in requests both to servers and
proxies. With this option enabled, \fICURLOPT_PROXYHEADER(3)\fP does not have
any effect.

\fBCURLHEADER_SEPARATE\fP \- makes \fICURLOPT_HTTPHEADER(3)\fP headers only get
sent to a server and not to a proxy. Proxy headers must be set with
\fICURLOPT_PROXYHEADER(3)\fP to get used. Note that if a non\-CONNECT request
is sent to a proxy, libcurl sends both server headers and proxy headers. When
doing CONNECT, libcurl sends \fICURLOPT_PROXYHEADER(3)\fP headers only to the
proxy and then \fICURLOPT_HTTPHEADER(3)\fP headers only to the server.
.SH DEFAULT
CURLHEADER_SEPARATE (changed in 7.42.1, used CURLHEADER_UNIFIED before then)
.SH PROTOCOLS
This functionality affects http only
.SH EXAMPLE
.nf
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode ret;
    struct curl_slist *list;
    list = curl_slist_append(NULL, "Shoesize: 10");
    list = curl_slist_append(list, "Accept:");
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
    curl_easy_setopt(curl, CURLOPT_PROXY, "http://localhost:8080");
    curl_easy_setopt(curl, CURLOPT_HTTPHEADER, list);

    /* HTTPS over a proxy makes a separate CONNECT to the proxy, so tell
       libcurl to not send the custom headers to the proxy. Keep them
       separate. */
    curl_easy_setopt(curl, CURLOPT_HEADEROPT, (long)CURLHEADER_SEPARATE);
    ret = curl_easy_perform(curl);
    curl_slist_free_all(list);
    curl_easy_cleanup(curl);
  }
}
.fi
.SH AVAILABILITY
Added in curl 7.37.0
.SH RETURN VALUE
\fIcurl_easy_setopt(3)\fP returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non\-zero means an error occurred, see
\fIlibcurl\-errors(3)\fP.
.SH SEE ALSO
.BR CURLOPT_HTTPHEADER (3),
.BR CURLOPT_PROXYHEADER (3)