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libcares/ares_gethostbyname.c  view on Meta::CPAN

  switch (family) {
  case AF_INET:
  case AF_INET6:
  case AF_UNSPEC:
    break;
  default:
    callback(arg, ARES_ENOTIMP, 0, NULL);
    return;
  }

  /* Per RFC 7686, reject queries for ".onion" domain names with NXDOMAIN. */
  if (ares__is_onion_domain(name))
    {
      callback(arg, ARES_ENOTFOUND, 0, NULL);
      return;
    }

  if (fake_hostent(name, family, callback, arg))
    return;

  /* Allocate and fill in the host query structure. */
  hquery = ares_malloc(sizeof(struct host_query));
  if (!hquery)
    {
      callback(arg, ARES_ENOMEM, 0, NULL);
      return;
    }
  hquery->channel = channel;
  hquery->name = ares_strdup(name);
  hquery->want_family = family;
  hquery->sent_family = -1; /* nothing is sent yet */
  if (!hquery->name) {
    ares_free(hquery);
    callback(arg, ARES_ENOMEM, 0, NULL);
    return;
  }
  hquery->callback = callback;
  hquery->arg = arg;
  hquery->remaining_lookups = channel->lookups;
  hquery->timeouts = 0;

  /* Start performing lookups according to channel->lookups. */
  next_lookup(hquery, ARES_ECONNREFUSED /* initial error code */);
}

static void next_lookup(struct host_query *hquery, int status_code)
{
  const char *p;
  struct hostent *host;
  int status = status_code;

  for (p = hquery->remaining_lookups; *p; p++)
    {
      switch (*p)
        {
        case 'b':
          /* DNS lookup */
          hquery->remaining_lookups = p + 1;
          if ((hquery->want_family == AF_INET6) ||
              (hquery->want_family == AF_UNSPEC)) {
            /* if inet6 or unspec, start out with AAAA */
            hquery->sent_family = AF_INET6;
            ares_search(hquery->channel, hquery->name, C_IN, T_AAAA,
                        host_callback, hquery);
          }
          else {
            hquery->sent_family = AF_INET;
            ares_search(hquery->channel, hquery->name, C_IN, T_A,
                        host_callback, hquery);
          }
          return;

        case 'f':
          /* Host file lookup */
          status = file_lookup(hquery->name, hquery->want_family, &host);

          /* this status check below previously checked for !ARES_ENOTFOUND,
             but we should not assume that this single error code is the one
             that can occur, as that is in fact no longer the case */
          if (status == ARES_SUCCESS)
            {
              end_hquery(hquery, status, host);
              return;
            }
          status = status_code;   /* Use original status code */
          break;
        }
    }
  end_hquery(hquery, status, NULL);
}

static void host_callback(void *arg, int status, int timeouts,
                          unsigned char *abuf, int alen)
{
  struct host_query *hquery = (struct host_query *) arg;
  ares_channel channel = hquery->channel;
  struct hostent *host = NULL;

  hquery->timeouts += timeouts;
  if (status == ARES_SUCCESS)
    {
      if (hquery->sent_family == AF_INET)
        {
          status = ares_parse_a_reply(abuf, alen, &host, NULL, NULL);
          if (host && channel->nsort)
            sort_addresses(host, channel->sortlist, channel->nsort);
        }
      else if (hquery->sent_family == AF_INET6)
        {
          status = ares_parse_aaaa_reply(abuf, alen, &host, NULL, NULL);
          if ((status == ARES_ENODATA || status == ARES_EBADRESP ||
               (status == ARES_SUCCESS && host && host->h_addr_list[0] == NULL)) &&
                hquery->want_family == AF_UNSPEC) {
            /* The query returned something but either there were no AAAA
               records (e.g. just CNAME) or the response was malformed.  Try
               looking up A instead. */
            if (host)
              ares_free_hostent(host);
            hquery->sent_family = AF_INET;
            ares_search(hquery->channel, hquery->name, C_IN, T_A,
                        host_callback, hquery);