CURLOPT_HEADEROPT(3) Library Functions Manual CURLOPT_HEADEROPT(3)
NAME
CURLOPT_HEADEROPT - send HTTP headers to both proxy and host or sepa-
rately
SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HEADEROPT, long bitmask);
DESCRIPTION
Pass a long that is a bitmask of options of how to deal with headers.
The two mutually exclusive options are:
CURLHEADER_UNIFIED - the headers specified in CURLOPT_HTTPHEADER(3) are
used in requests both to servers and proxies. With this option enabled,
CURLOPT_PROXYHEADER(3) does not have any effect.
CURLHEADER_SEPARATE - makes CURLOPT_HTTPHEADER(3) headers only get sent
to a server and not to a proxy. Proxy headers must be set with CUR-
LOPT_PROXYHEADER(3) 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 CURLOPT_PROXYHEADER(3) headers only to
the proxy and then CURLOPT_HTTPHEADER(3) headers only to the server.
DEFAULT
CURLHEADER_SEPARATE (changed in 7.42.1, used CURLHEADER_UNIFIED before
then)
PROTOCOLS
This functionality affects http only
EXAMPLE
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);
}
}
AVAILABILITY
Added in curl 7.37.0
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_HTTPHEADER(3), CURLOPT_PROXYHEADER(3)
libcurl 2026-07-12 CURLOPT_HEADEROPT(3)
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