Add a return value to prf_plus_t.get_bytes()

src/libstrongswan/crypto/prf_plus.h

@@ -36,8 +36,10 @@ struct prf_plus_t {
 	 *
 	 * @param length	number of bytes to get
 	 * @param buffer	pointer where the generated bytes will be written
+	 * @return			TRUE if bytes generated successfully
 	 */
-	void (*get_bytes) (prf_plus_t *this, size_t length, u_int8_t *buffer);
+	__attribute__((warn_unused_result))
+	bool (*get_bytes) (prf_plus_t *this, size_t length, u_int8_t *buffer);
 
 	/**
 	 * Allocate pseudo random bytes.