curl / libcurl / API / curl_easy_setopt / CURLOPT_HEADEROPT

CURLOPT_HEADEROPT explained

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 will be used in requests both to servers and proxies. With this option enabled, CURLOPT_PROXYHEADER will not have any effect.

CURLHEADER_SEPARATE - makes CURLOPT_HTTPHEADER headers only get sent to a server and not to a proxy. Proxy headers must be set with CURLOPT_PROXYHEADER to get used. Note that if a non-CONNECT request is sent to a proxy, libcurl will send both server headers and proxy headers. When doing CONNECT, libcurl will send CURLOPT_PROXYHEADER headers only to the proxy and then CURLOPT_HTTPHEADER headers only to the server.

Default

CURLHEADER_SEPARATE (changed in 7.42.1, used CURLHEADER_UNIFIED before then)

Protocols

HTTP

Example

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, CURLHEADER_SEPARATE);
  ret = curl_easy_perform(curl);
  curl_slist_free_all(list);
  curl_easy_cleanup(curl);
}

Availability

Added in 7.37.0

Return value

Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.