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

/*
     This file is part of GNUnet.
     Copyright (C) 2007-2016 GNUnet e.V.

     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., 51 Franklin Street, Fifth Floor,
     Boston, MA 02110-1301, USA.
*/

/**
 * @file topology/gnunet-daemon-topology.c
 * @brief code for maintaining the overlay topology
 * @author Christian Grothoff
 *
 * This daemon combines three functions:
 * - suggesting to ATS which peers we might want to connect to
 * - enforcing the F2F restrictions (by blacklisting)
 * - gossping HELLOs
 *
 * All three require similar information (who are our friends
 * impacts connectivity suggestions; connectivity suggestions
 * should consider blacklisting; connectivity suggestions
 * should consider available/known HELLOs; gossip requires
 * connectivity data; connectivity suggestions require
 * connectivity data), which is why they are combined in this
 * program.
 */
#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_friends_lib.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_ats_service.h"


/**
 * 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 transmitting to this peer; NULL
   * if peer is not connected.
   */
  struct GNUNET_MQ_Handle *mq;

  /**
   * 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;

  /**
   * 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.
   */
  struct GNUNET_SCHEDULER_Task *hello_delay_task;

  /**
   * Handle for our connectivity suggestion for this peer.
   */
  struct GNUNET_ATS_ConnectivitySuggestHandle *sh;

  /**
   * How much would we like to connect to this peer?
   */
  uint32_t strength;

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

};


/**
 * Our peerinfo notification context.  We use notification
 * to instantly learn about new peers as they are discovered.
 */
static struct GNUNET_PEERINFO_NotifyContext *peerinfo_notify;

/**
 * Our configuration.
 */
static const struct GNUNET_CONFIGURATION_Handle *cfg;

/**
 * Handle to the CORE service.
 */
static struct GNUNET_CORE_Handle *handle;

/**
 * Handle to the PEERINFO service.
 */
static struct GNUNET_PEERINFO_Handle *pi;

/**
 * Handle to the ATS service.
 */
static struct GNUNET_ATS_ConnectivityHandle *ats;

/**
 * Identity of this peer.
 */
static struct GNUNET_PeerIdentity my_identity;

/**
 * All of our friends, all of our current neighbours and all peers for
 * which we have HELLOs.  So pretty much everyone.  Maps peer identities
 * to `struct Peer *` values.
 */
static struct GNUNET_CONTAINER_MultiPeerMap *peers;

/**
 * Handle for reporting statistics.
 */
static struct GNUNET_STATISTICS_Handle *stats;

/**
 * Blacklist (NULL if we have none).
 */
static struct GNUNET_TRANSPORT_Blacklist *blacklist;

/**
 * Task scheduled to asynchronously reconsider adding/removing
 * peer connectivity suggestions.
 */
static struct GNUNET_SCHEDULER_Task *add_task;

/**
 * Active HELLO offering to transport service.
 */
static struct GNUNET_TRANSPORT_OfferHelloHandle *oh;

/**
 * Flag to disallow non-friend connections (pure F2F mode).
 */
static int friends_only;

/**
 * Minimum number of friends to have in the
 * connection set before we allow non-friends.
 */
static unsigned int minimum_friend_count;

/**
 * Number of peers (friends and others) that we are currently connected to.
 */
static unsigned int connection_count