path: root/src/util/resolver_api.c

/*
     This file is part of GNUnet.
     Copyright (C) 2009-2018 GNUnet e.V.

     GNUnet is free software: you can redistribute it and/or modify it
     under the terms of the GNU Affero General Public License as published
     by the Free Software Foundation, either version 3 of the License,
     or (at your option) any later version.

     GNUnet is distributed in the hope that it will be useful, but
     WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     Affero General Public License for more details.
    
     You should have received a copy of the GNU Affero General Public License
     along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/**
 * @file util/resolver_api.c
 * @brief resolver for writing a tool
 * @author Christian Grothoff
 */
#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_protocols.h"
#include "gnunet_resolver_service.h"
#include "resolver.h"

#define LOG(kind,...) GNUNET_log_from (kind, "util-resolver-api", __VA_ARGS__)

#define LOG_STRERROR(kind,syscall) GNUNET_log_from_strerror (kind, "util-resolver-api", syscall)

/**
 * Maximum supported length for a hostname
 */
#define MAX_HOSTNAME 1024


/**
 * Possible hostnames for "loopback".
 */
static const char *loopback[] = {
  "localhost",
  "ip6-localnet",
  NULL
};


/**
 * Configuration.
 */
static const struct GNUNET_CONFIGURATION_Handle *resolver_cfg;

/**
 * Our connection to the resolver service, created on-demand, but then
 * persists until error or shutdown.
 */
static struct GNUNET_MQ_Handle *mq;

/**
 * Head of DLL of requests.
 */
static struct GNUNET_RESOLVER_RequestHandle *req_head;

/**
 * Tail of DLL of requests.
 */
static struct GNUNET_RESOLVER_RequestHandle *req_tail;

/**
 * How long should we wait to reconnect?
 */
static struct GNUNET_TIME_Relative backoff;

/**
 * Task for reconnecting.
 */
static struct GNUNET_SCHEDULER_Task *r_task;

/**
 * Task ID of shutdown task; only present while we have a
 * connection to the resolver service.
 */
static struct GNUNET_SCHEDULER_Task *s_task;


/**
 * Handle to a request given to the resolver.  Can be used to cancel
 * the request prior to the timeout or successful execution.  Also
 * used to track our internal state for the request.
 */
struct GNUNET_RESOLVER_RequestHandle
{

  /**
   * Next entry in DLL of requests.
   */
  struct GNUNET_RESOLVER_RequestHandle *next;

  /**
   * Previous entry in DLL of requests.
   */
  struct GNUNET_RESOLVER_RequestHandle *prev;

  /**
   * Callback if this is an name resolution request,
   * otherwise NULL.
   */
  GNUNET_RESOLVER_AddressCallback addr_callback;

  /**
   * Callback if this is a reverse lookup request,
   * otherwise NULL.
   */
  GNUNET_RESOLVER_HostnameCallback name_callback;

  /**
   * Closure for the callbacks.
   */
  void *cls;

  /**
   * When should this request time out?
   */
  struct GNUNET_TIME_Absolute timeout;

  /**
   * Task handle for making reply callbacks in numeric lookups
   * asynchronous, and for timeout handling.
   */
  struct GNUNET_SCHEDULER_Task *task;

  /**
   * Desired address family.
   */
  int af;

  /**
   * Has this request been transmitted to the service?
   * #GNUNET_YES if transmitted
   * #GNUNET_YES if not transmitted
   * #GNUNET_SYSERR when request was canceled
   */
  int was_transmitted;

  /**
   * Did we add this request to the queue?
   */
  int was_queued;

  /**
   * Desired direction (IP to name or name to IP)
   */
  int direction;

  /**
   * #GNUNET_YES if a response was received
   */
  int received_response;

  /**
   * Length of the data that follows this struct.
   */
  size_t data_len;
};


/**
 * Check that the resolver service runs on localhost
 * (or equivalent).
 *
 * @return #GNUNET_OK if the resolver is properly configured,
 *         #GNUNET_SYSERR otherwise.
 */
static int
check_config ()
{
  char *hostname;
  struct sockaddr_in v4;
  struct sockaddr_in6 v6;

  memset (&v4, 0, sizeof (v4));
  v4.sin_addr.s_addr = htonl (INADDR_LOOPBACK);
  v4.sin_family = AF_INET;
#if HAVE_SOCKADDR_IN_SIN_LEN
  v4.sin_len = sizeof (v4);
#endif
  memset (&v6, 0, sizeof (v6));
  v6.sin6_family = AF_INET6;
#if HAVE_SOCKADDR_IN_SIN_LEN
  v6.sin6_len = sizeof (v6);
#endif
  if (GNUNET_OK !=