IAKERB_TOK_PROXY
k5_input_get_uint16_be(&in) != IAKERB_TOK_PROXY) {
g_make_token_header(&buf, gss_mech_iakerb, data->length, IAKERB_TOK_PROXY);
k5_input_get_uint16_be(&in) == IAKERB_TOK_PROXY;