plucky (3) curl_easy_nextheader.3.gz

NAME

       curl_easy_nextheader - get the next HTTP header

SYNOPSIS

       #include <curl/curl.h>

       struct curl_header *curl_easy_nextheader(CURL *easy,
                                                unsigned int origin,
                                                int request,
                                                struct curl_header *prev);

DESCRIPTION

       This function lets an application iterate over all previously received HTTP headers.

       The  origin  argument is for specifying which headers to receive, as a single HTTP transfer might provide
       headers from several different places and they may then have different importance to the user and headers
       using  the  same  name  might  be used. The origin is a bitmask for what header sources you want. See the
       curl_easy_header(3) man page for the origin descriptions.

       The request argument tells libcurl from which request you want headers  from.  A  single  transfer  might
       consist  of  a  series  of  HTTP  requests and this argument lets you specify which particular individual
       request you want the headers from. 0 being the first request and then the number  increases  for  further
       redirects  or  when multi-state authentication is used. Passing in -1 is a shortcut to "the last" request
       in the series, independently of the actual amount of requests used.

       It is suggested that you pass in the same origin and request when iterating over a range  of  headers  as
       changing the value mid-loop might give you unexpected results.

       If  prev  is  NULL,  this  function  returns  a pointer to the first header stored within the given scope
       (origin + request).

       If prev is a pointer to a previously returned header struct, curl_easy_nextheader(3)  returns  a  pointer
       the  next  header  stored within the given scope. This way, an application can iterate over all available
       headers.

       The memory for the struct this points to, is owned and managed by libcurl and is associated with the easy
       handle.  Applications must copy the data if they want it to survive subsequent API calls or the life-time
       of the easy handle.

PROTOCOLS

       This functionality affects http only

EXAMPLE

       int main(void)
       {
         struct curl_header *prev = NULL;
         struct curl_header *h;

         CURL *curl = curl_easy_init();
         if(curl) {
           curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
           curl_easy_perform(curl);

           /* extract the normal headers from the first request */
           while((h = curl_easy_nextheader(curl, CURLH_HEADER, 0, prev))) {
             printf("%s: %s\n", h->name, h->value);
             prev = h;
           }

           /* extract the normal headers + 1xx + trailers from the last request */
           unsigned int origin = CURLH_HEADER| CURLH_1XX | CURLH_TRAILER;
           while((h = curl_easy_nextheader(curl, origin, -1, prev))) {
             printf("%s: %s\n", h->name, h->value);
             prev = h;
           }
         }
       }

AVAILABILITY

       Added in curl 7.83.0

RETURN VALUE

       This function returns the next header, or NULL when there are no more  (matching)  headers  or  an  error
       occurred.

       If  this  function returns NULL when prev was set to NULL, then there are no headers available within the
       scope to return.

SEE ALSO

       curl_easy_header(3), curl_easy_perform(3)