Esempio n. 1
0
int ares_init_options(ares_channel *channelptr, struct ares_options *options,
		      int optmask)
{
  ares_channel channel;
  int i, status;
  struct server_state *server;
  struct timeval tv;

  channel = malloc(sizeof(struct ares_channeldata));
  if (!channel)
    return ARES_ENOMEM;

  /* Set everything to distinguished values so we know they haven't
   * been set yet.
   */
  channel->flags = -1;
  channel->timeout = -1;
  channel->tries = -1;
  channel->ndots = -1;
  channel->udp_port = -1;
  channel->tcp_port = -1;
  channel->nservers = -1;
  channel->ndomains = -1;
  channel->nsort = -1;
  channel->lookups = NULL;

  /* Initialize configuration by each of the four sources, from highest
   * precedence to lowest.
   */
  status = init_by_options(channel, options, optmask);
  if (status == ARES_SUCCESS)
    status = init_by_environment(channel);
  if (status == ARES_SUCCESS)
    status = init_by_resolv_conf(channel);
  if (status == ARES_SUCCESS)
    status = init_by_defaults(channel);
  if (status != ARES_SUCCESS)
    {
      /* Something failed; clean up memory we may have allocated. */
      if (channel->nservers != -1)
	free(channel->servers);
      if (channel->ndomains != -1)
	{
	  for (i = 0; i < channel->ndomains; i++)
	    free(channel->domains[i]);
	  free(channel->domains);
	}
      if (channel->nsort != -1)
	free(channel->sortlist);
      free(channel->lookups);
      free(channel);
      return status;
    }

  /* Trim to one server if ARES_FLAG_PRIMARY is set. */
  if ((channel->flags & ARES_FLAG_PRIMARY) && channel->nservers > 1)
    channel->nservers = 1;

  /* Initialize server states. */
  for (i = 0; i < channel->nservers; i++)
    {
      server = &channel->servers[i];
      server->udp_socket = -1;
      server->tcp_socket = -1;
      server->tcp_lenbuf_pos = 0;
      server->tcp_buffer = NULL;
      server->qhead = NULL;
      server->qtail = NULL;
    }

  /* Choose a somewhat random query ID.  The main point is to avoid
   * collisions with stale queries.  An attacker trying to spoof a DNS
   * answer also has to guess the query ID, but it's only a 16-bit
   * field, so there's not much to be done about that.
   */
  gettimeofday(&tv, NULL);
  channel->next_id = (tv.tv_sec ^ tv.tv_usec ^ getpid()) & 0xffff;

  channel->queries = NULL;

  *channelptr = channel;
  return ARES_SUCCESS;
}
Esempio n. 2
0
int ares_init_options(ares_channel *channelptr, struct ares_options *options,
                      int optmask)
{
  ares_channel channel;
  int i;
  int status = ARES_SUCCESS;
  struct timeval now;

#ifdef CURLDEBUG
  const char *env = getenv("CARES_MEMDEBUG");

  if (env)
    curl_memdebug(env);
  env = getenv("CARES_MEMLIMIT");
  if (env) {
    char *endptr;
    long num = strtol(env, &endptr, 10);
    if((endptr != env) && (endptr == env + strlen(env)) && (num > 0))
      curl_memlimit(num);
  }
#endif

  if (ares_library_initialized() != ARES_SUCCESS)
    return ARES_ENOTINITIALIZED;

  channel = malloc(sizeof(struct ares_channeldata));
  if (!channel) {
    *channelptr = NULL;
    return ARES_ENOMEM;
  }

  now = ares__tvnow();

  /* Set everything to distinguished values so we know they haven't
   * been set yet.
   */
  channel->flags = -1;
  channel->timeout = -1;
  channel->tries = -1;
  channel->ndots = -1;
  channel->rotate = -1;
  channel->udp_port = -1;
  channel->tcp_port = -1;
  channel->socket_send_buffer_size = -1;
  channel->socket_receive_buffer_size = -1;
  channel->nservers = -1;
  channel->ndomains = -1;
  channel->nsort = -1;
  channel->tcp_connection_generation = 0;
  channel->lookups = NULL;
  channel->domains = NULL;
  channel->sortlist = NULL;
  channel->servers = NULL;
  channel->sock_state_cb = NULL;
  channel->sock_state_cb_data = NULL;
  channel->sock_create_cb = NULL;
  channel->sock_create_cb_data = NULL;

  channel->last_server = 0;
  channel->last_timeout_processed = (time_t)now.tv_sec;

  memset(&channel->local_dev_name, 0, sizeof(channel->local_dev_name));
  channel->local_ip4 = 0;
  memset(&channel->local_ip6, 0, sizeof(channel->local_ip6));

  /* Initialize our lists of queries */
  ares__init_list_head(&(channel->all_queries));
  for (i = 0; i < ARES_QID_TABLE_SIZE; i++)
    {
      ares__init_list_head(&(channel->queries_by_qid[i]));
    }
  for (i = 0; i < ARES_TIMEOUT_TABLE_SIZE; i++)
    {
      ares__init_list_head(&(channel->queries_by_timeout[i]));
    }

  /* Initialize configuration by each of the four sources, from highest
   * precedence to lowest.
   */

  if (status == ARES_SUCCESS) {
    status = init_by_options(channel, options, optmask);
    if (status != ARES_SUCCESS)
      DEBUGF(fprintf(stderr, "Error: init_by_options failed: %s\n",
                     ares_strerror(status)));
  }
  if (status == ARES_SUCCESS) {
    status = init_by_environment(channel);
    if (status != ARES_SUCCESS)
      DEBUGF(fprintf(stderr, "Error: init_by_environment failed: %s\n",
                     ares_strerror(status)));
  }
  if (status == ARES_SUCCESS) {
    status = init_by_resolv_conf(channel);
    if (status != ARES_SUCCESS)
      DEBUGF(fprintf(stderr, "Error: init_by_resolv_conf failed: %s\n",
                     ares_strerror(status)));
  }

  /*
   * No matter what failed or succeeded, seed defaults to provide
   * useful behavior for things that we missed.
   */
  status = init_by_defaults(channel);
  if (status != ARES_SUCCESS)
    DEBUGF(fprintf(stderr, "Error: init_by_defaults failed: %s\n",
                   ares_strerror(status)));

  /* Generate random key */

  if (status == ARES_SUCCESS) {
    status = init_id_key(&channel->id_key, ARES_ID_KEY_LEN);
    if (status == ARES_SUCCESS)
      channel->next_id = ares__generate_new_id(&channel->id_key);
    else
      DEBUGF(fprintf(stderr, "Error: init_id_key failed: %s\n",
                     ares_strerror(status)));
  }

  if (status != ARES_SUCCESS)
    {
      /* Something failed; clean up memory we may have allocated. */
      if (channel->servers)
        free(channel->servers);
      if (channel->domains)
        {
          for (i = 0; i < channel->ndomains; i++)
            free(channel->domains[i]);
          free(channel->domains);
        }
      if (channel->sortlist)
        free(channel->sortlist);
      if(channel->lookups)
        free(channel->lookups);
      free(channel);
      return status;
    }

  /* Trim to one server if ARES_FLAG_PRIMARY is set. */
  if ((channel->flags & ARES_FLAG_PRIMARY) && channel->nservers > 1)
    channel->nservers = 1;

  ares__init_servers_state(channel);

  *channelptr = channel;
  return ARES_SUCCESS;
}