NAME

       CURLOPT_HEADEROPT - send HTTP headers to both proxy and host or separately

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 CURLOPT_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                                            2025-07-22                               CURLOPT_HEADEROPT(3)