headerapi.c

/***************************************************************************
 * _ _ ____ _
 * Project ___| | | | _ \| |
 * / __| | | | |_) | |
 * | (__| |_| | _ <| |___
 * \___|\___/|_| \_\_____|
 *
 * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at https://curl.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 * SPDX-License-Identifier: curl
 *
 ***************************************************************************/
/* <DESC>
 * Extract headers post transfer with the header API
 * </DESC>
 */
#include <stdio.h>
#include <curl/curl.h>
 
static size_t write_cb(char *data, size_t n, size_t l, void *userp)
{
 /* take care of the data here, ignored in this example */
 (void)data;
 (void)userp;
 return n*l;
}
 
int main(void)
{
 CURL *curl;
 
 CURLcode res = curl_global_init(CURL_GLOBAL_ALL);
 if(res)
 return (int)res;
 
 curl = curl_easy_init();
 if(curl) {
 struct curl_header *header;
 curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
 /* example.com is redirected, so we tell libcurl to follow redirection */
 curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
 
 /* this example just ignores the content */
 curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_cb);
 
 /* Perform the request, res gets the return code */
 res = curl_easy_perform(curl);
 /* Check for errors */
 if(res != CURLE_OK)
 fprintf(stderr, "curl_easy_perform() failed: %s\n",
 curl_easy_strerror(res));
 
 if(CURLHE_OK == curl_easy_header(curl, "Content-Type", 0, CURLH_HEADER,
 -1, &header))
 printf("Got content-type: %s\n", header->value);
 
 printf("All server headers:\n");
 {
 struct curl_header *h;
 struct curl_header *prev = NULL;
 do {
 h = curl_easy_nextheader(curl, CURLH_HEADER, -1, prev);
 if(h)
 printf(" %s: %s (%u)\n", h->name, h->value, (unsigned int)h->amount);
 prev = h;
 } while(h);
 
 }
 /* always cleanup */
 curl_easy_cleanup(curl);
 }
 curl_global_cleanup();
 return 0;
}

Notice