path: root/src/topology/gnunet-daemon-topology.c

/*
     This file is part of GNUnet.
     (C) 2007, 2008, 2009, 2010 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 topology/gnunet-daemon-topology.c
 * @brief code for maintaining the mesh topology
 * @author Christian Grothoff
 */
#include "platform.h"
#include "gnunet_constants.h"
#include "gnunet_core_service.h"
#include "gnunet_protocols.h"
#include "gnunet_peerinfo_service.h"
#include "gnunet_statistics_service.h"
#include "gnunet_transport_service.h"
#include "gnunet_util_lib.h"


/**
 * Minimum required delay between calls to GNUNET_TRANSPORT_try_connect.
 */
#define MAX_CONNECT_FREQUENCY_DELAY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MILLISECONDS, 250)

/**
 * For how long do we blacklist a peer after a failed connection
 * attempt?  This is the baseline factor which is then multiplied by
 * two to the power of the number of failed attempts.
 */
#define GREYLIST_AFTER_ATTEMPT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 1)

/**
 * For how long do we blacklist a friend after a failed connection
 * attempt?  This is the baseline factor which is then multiplied by
 * two to the power of the number of failed attempts.
 */
#define GREYLIST_AFTER_ATTEMPT_FRIEND GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 2)

/**
 * For how long do we blacklist anyone under any cirumstances at least after a failed connection
 * attempt?  This is the absolute minimum, regardless of what the calculation based on
 * exponential backoff returns.
 */
#define GREYLIST_AFTER_ATTEMPT_MIN GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 5)

/**
 * For how long do we blacklist anyone under any cirumstances at most after a failed connection
 * attempt?  This is the absolute maximum, regardless of what the calculation based on 
 * exponential back-off returns.
 */
#define GREYLIST_AFTER_ATTEMPT_MAX GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_HOURS, 1)

/**
 * At what frequency do we sent HELLOs to a peer?
 */
#define HELLO_ADVERTISEMENT_MIN_FREQUENCY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 5)

/**
 * After what time period do we expire the HELLO Bloom filter?
 */
#define HELLO_ADVERTISEMENT_MIN_REPEAT_FREQUENCY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_HOURS, 4)


/**
 * Record for neighbours, friends and blacklisted peers.
 */
struct Peer
{
  /**
   * Which peer is this entry about?
   */
  struct GNUNET_PeerIdentity pid;

  /**
   * Our handle for the request to transmit HELLOs to this peer; NULL
   * if no such request is pending.
   */
  struct GNUNET_CORE_TransmitHandle *hello_req;

  /**
   * Pointer to the HELLO message of this peer; can be NULL.
   */
  struct GNUNET_HELLO_Message *hello;

  /**
   * Bloom filter used to mark which peers already got the HELLO
   * from this peer.
   */
  struct GNUNET_CONTAINER_BloomFilter *filter;

  /**
   * Until what time should we not try to connect again
   * to this peer?
   */
  struct GNUNET_TIME_Absolute greylisted_until;

  /**
   * Next time we are allowed to transmit a HELLO to this peer?
   */
  struct GNUNET_TIME_Absolute next_hello_allowed;

  /**
   * When should we reset the bloom filter of this entry?
   */
  struct GNUNET_TIME_Absolute filter_expiration;

  /**
   * ID of task we use to wait for the time to send the next HELLO
   * to this peer.
   */
  GNUNET_SCHEDULER_TaskIdentifier hello_delay_task;

  /**
   * Task for issuing GNUNET_TRANSPORT_try_connect for this peer.
   */
  GNUNET_SCHEDULER_TaskIdentifier attempt_connect_task;

  /**
   * ID of task we use to clear peers from the greylist.
   */
  GNUNET_SCHEDULER_TaskIdentifier greylist_clean_task;

  /**
   * How often have we tried so far?
   */
  unsigned int connect_attempts;

  /**
   * Is this peer listed here because he is a friend?
   */
  int is_friend;

  /**