path: root/src/nat/nat.c

/*
     This file is part of GNUnet.
     (C) 2009, 2010, 2011 Christian Grothoff (and other contributing authors)

     GNUnet is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published
     by the Free Software Foundation; either version 3, 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
     General Public License for more details.

     You should have received a copy of the GNU General Public License
     along with GNUnet; see the file COPYING.  If not, write to the
     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
     Boston, MA 02111-1307, USA.
*/

/**
 * @file nat/nat.c
 * @brief Library handling UPnP and NAT-PMP port forwarding and
 *     external IP address retrieval
 * @author Milan Bouchet-Valat
 * @author Christian Grothoff
 */
#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_resolver_service.h"
#include "gnunet_nat_lib.h"
#include "nat.h"

#define LOG(kind,...) GNUNET_log_from (kind, "nat", __VA_ARGS__)

/**
 * How often do we scan for changes in our IP address from our local
 * interfaces?
 */
#define IFC_SCAN_FREQUENCY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 15)

/**
 * How often do we scan for changes in how our hostname resolves?
 */
#define HOSTNAME_DNS_FREQUENCY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 20)


/**
 * How often do we scan for changes in how our external (dyndns) hostname resolves?
 */
#define DYNDNS_FREQUENCY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 7)

/**
 * How long until we give up trying to resolve our own hostname?
 */
#define HOSTNAME_RESOLVE_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 1)


/**
 * Where did the given local address originate from?
 * To be used for debugging as well as in the future
 * to remove all addresses from a certain source when
 * we reevaluate the source.
 */
enum LocalAddressSource
{
    /**
     * Address was obtained by DNS resolution of the external hostname
     * given in the configuration (i.e. hole-punched DynDNS setup).
     */
  LAL_EXTERNAL_IP,

    /**
     * Address was obtained by looking up our own hostname in DNS.
     */
  LAL_HOSTNAME_DNS,

    /**
     * Address was obtained by scanning our hosts's network interfaces
     * and taking their address (no DNS involved).
     */
  LAL_INTERFACE_ADDRESS,

    /**
     * Addresses we were explicitly bound to.
     */
  LAL_BINDTO_ADDRESS,

    /**
     * Addresses from UPnP or PMP
     */
  LAL_UPNP,

    /**
     * End of the list.
     */
  LAL_END
};


/**
 * List of local addresses that we currently deem valid.  Actual
 * struct is followed by the 'struct sockaddr'.  Note that the code
 * intentionally makes no attempt to ensure that a particular address
 * is only listed once (especially since it may come from different
 * sources, and the source is an "internal" construct).
 */
struct LocalAddressList
{
  /**
   * This is a linked list.
   */
  struct LocalAddressList *next;

  /**
   * Previous entry.
   */
  struct LocalAddressList *prev;

  /**
   * Number of bytes of address that follow.
   */
  socklen_t addrlen;

  /**
   * Origin of the local address.
   */
  enum LocalAddressSource source;
};


/**
 * Handle for miniupnp-based NAT traversal actions.
 */
struct MiniList
{

  /**
   * Doubly-linked list.
   */
  struct MiniList *next;

  /**
   * Doubly-linked list.
   */
  struct MiniList *prev;

  /**
   * Handle to mini-action.
   */
  struct GNUNET_NAT_MiniHandle *mini;

  /**
   * Local port number that was mapped.
   */
  uint16_t port