[...]
#ifdef HAVE_LIBCAPSICUM
  if (nflag) {
    capcas = NULL;
    capdns = NULL;
  } else {
    capcas = cap_init();
    if (capcas == NULL)
      error("unable to contact Casper");
    capdns = cap_service_open(capcas, "system.dns");
    if (capdns == NULL)
      error("unable to open system.dns service");
    /*Limit system.dns to rev. DNS lookups.*/
    limits = nvlist_create(0);
    nvlist_add_string(limits,"type", "ADDR");
    nvlist_add_number(limits,"family", (uint64_t)AF_INET);
    nvlist_add_number(limits, "family", (uint64_t)AF_INET6);
    if (cap_limit_set(capdns, limits) < 0)
      error("unable to limit access to system.dns service");
    nvlist_destroy(limits);
    / * Casper capability no longer needed. * /
    cap_close(capcas);
  }
#endif  /* HAVE_LIBCAPSICUM */
[...]