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curl_easy_nextheader(3)             libcurl            curl_easy_nextheader(3)


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.


EXAMPLE

       struct curl_header *prev = NULL;
       struct curl_header *h;

       /* extract the normal headers from the first request */
       while((h = curl_easy_nextheader(easy, CURLH_HEADER, 0, prev))) {
          print "%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(easy, origin, -1, prev))) {
          print "%s: %s\n", h->name, h->value);
          prev = h;
       }


AVAILABILITY

       Added in 7.83.0. Officially supported since 7.84.0.


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)

libcurl 8.1.2                   April 26, 2023         curl_easy_nextheader(3)

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