Nonce: Let get_nonce, allocate_nonce return boolean

src/libstrongswan/crypto/nonce_gen.h

@@ -35,16 +35,18 @@ struct nonce_gen_t {
 	 *
 	 * @param size		size of nonce in bytes
 	 * @param buffer	pointer where the generated nonce will be written
+	 * @return              TRUE if nonce allocation was succesful, FALSE otherwise
 	 */
-	void (*get_nonce) (nonce_gen_t *this, size_t size, u_int8_t *buffer);
+	bool (*get_nonce) (nonce_gen_t *this, size_t size, u_int8_t *buffer);
 
 	/**
 	 * Generates a nonce and allocates space for it.
 	 *
 	 * @param size		size of nonce in bytes
 	 * @param chunk		chunk which will hold the generated nonce
+	 * @return		TRUE if nonce allocation was succesful, FALSE otherwise
 	 */
-	void (*allocate_nonce) (nonce_gen_t *this, size_t size, chunk_t *chunk);
+	bool (*allocate_nonce) (nonce_gen_t *this, size_t size, chunk_t *chunk);
 
 	/**
 	 * Destroys a nonce generator object.