int _gnutls_set_datum(gnutls_datum_t * dat, const void *data,
size_t data_size);
+int _gnutls_set_strdatum(gnutls_datum_t * dat, const void *data,
+ size_t data_size);
+
int _gnutls_datum_append(gnutls_datum_t * dat, const void *data,
size_t data_size);