libekmfweb: Add, change and delete key tags

Allow to add, change and delete custom tags of a key. Custom tags
can be used store any kind of textual information with a key. Tags
have a name and a value.

Signed-off-by: Ingo Franzki <ifranzki@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

libekmfweb/utilities.h

@@ -18,6 +18,7 @@
 #include <openssl/evp.h>
 
 #include <json-c/json.h>
+#include <curl/curl.h>
 
 #include "ekmfweb/ekmfweb.h"
 
@@ -78,6 +79,8 @@ int clone_key_info(const struct ekmf_key_info *src,
 		   struct ekmf_key_info *dest);
 void free_key_info(struct ekmf_key_info *key);
 
+char *get_http_header_value(const struct curl_slist *headers, const char *name);
+
 size_t ecc_get_curve_prime_bits(int curve_nid);
 size_t ecc_get_curve_prime_length(int curve_nid);
 const char *ecc_get_curve_id(int curve_nid);