NAME

       CURLOPT_HTTPHEADER - set custom HTTP headers

SYNOPSIS

       #include <curl/curl.h>

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HTTPHEADER, struct curl_slist *headers);

DESCRIPTION

       Pass  a pointer to a linked list of HTTP headers to pass to the server and/or proxy in your HTTP request.
       The same list can be used for both host and proxy requests!

       The linked list should be a fully valid list  of  struct  curl_slist  structs  properly  filled  in.  Use
       curl_slist_append(3) to create the list and curl_slist_free_all(3) to clean up an entire list. If you add
       a header that is otherwise generated and used by libcurl internally, your added one will be used instead.
       If  you  add  a  header  with  no  content  as in 'Accept:' (no data on the right side of the colon), the
       internally used header will get disabled. With this option you can  add  new  headers,  replace  internal
       headers  and  remove  internal headers. To add a header with no content (nothing to the right side of the
       colon), use the form 'MyHeader;' (note the ending semicolon).

       The headers included in the linked list must not be CRLF-terminated, because libcurl adds CRLF after each
       header  item. Failure to comply with this will result in strange bugs because the server will most likely
       ignore part of the headers you specified.

       The first line in a request (containing the method, usually a GET or POST) is not a header and cannot  be
       replaced  using  this  option.  Only the lines following the request-line are headers. Adding this method
       line  in  this  list  of  headers  will  only  cause  your  request  to  send  an  invalid  header.   Use
       CURLOPT_CUSTOMREQUEST(3) to change the method.

       When this option is passed to curl_easy_setopt(3), libcurl will not copy the entire list so you must keep
       it around until you no longer use this handle for a transfer before you  call  curl_slist_free_all(3)  on
       the list.

       Pass a NULL to this option to reset back to no custom headers.

       The   most   commonly   replaced   headers   have   "shortcuts"   in   the   options   CURLOPT_COOKIE(3),
       CURLOPT_USERAGENT(3) and CURLOPT_REFERER(3). We recommend using those.

       There's an alternative option that sets or replaces headers only for requests that are sent with  CONNECT
       to a proxy: CURLOPT_PROXYHEADER(3). Use CURLOPT_HEADEROPT(3) to control the behavior.

       Custom  headers are sent in all requests done by the easy handles, which implies that if you tell libcurl
       to follow redirects (CURLOPT_FOLLOWLOCATION(3)), the same set of custom  headers  will  be  sent  in  the
       subsequent  request.  Redirects  can  of course go to other hosts and thus those servers will get all the
       contents of your custom headers too.

       Starting in 7.58.0, libcurl will specifically prevent "Authorization:" headers from being sent  to  other
       hosts  than  the  first  used  one,  unless  specifically permitted with the CURLOPT_UNRESTRICTED_AUTH(3)
       option.

SECURITY CONCERNS

       By default, this option makes libcurl send the given headers in all HTTP requests done  by  this  handle.
       You  should  therefore use this option with caution if you for example connect to the remote site using a
       proxy and a CONNECT request, you should to consider if that proxy is supposed to also  get  the  headers.
       They may be private or otherwise sensitive to leak.

       Use CURLOPT_HEADEROPT(3) to make the headers only get sent to where you intend them to get sent.

DEFAULT

       NULL

PROTOCOLS

       HTTP

EXAMPLE

       CURL *curl = curl_easy_init();

       struct curl_slist *list = NULL;

       if(curl) {
         curl_easy_setopt(curl, CURLOPT_URL, "http://example.com");

         list = curl_slist_append(list, "Shoesize: 10");
         list = curl_slist_append(list, "Accept:");

         curl_easy_setopt(curl, CURLOPT_HTTPHEADER, list);

         curl_easy_perform(curl);

         curl_slist_free_all(list); /* free the list again */
       }

AVAILABILITY

       As long as HTTP is enabled

RETURN VALUE

       Returns CURLE_OK if HTTP is supported, and CURLE_UNKNOWN_OPTION if not.

SEE ALSO

       CURLOPT_CUSTOMREQUEST(3), CURLOPT_HEADEROPT(3), CURLOPT_PROXYHEADER(3), CURLOPT_HEADER(3)