gnunet/src/dht/gnunet-service-xdht_routing.c

/*
     This file is part of GNUnet.
     (C) 2011 - 2014 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 dht/gnunet-service-xdht_routing.c
 * @brief GNUnet DHT tracking of requests for routing replies
 * @author Supriti Singh
 */
#include "platform.h"
#include "gnunet-service-xdht_neighbours.h"
#include "gnunet-service-xdht_routing.h"
#include "gnunet-service-xdht.h"


/**
 * FIXME: Check if its better to store pointer to friend rather than storing
 * peer identity next_hop or prev_hop.
 * keep entries in destnation and source peer also. so when we send the trail
 * teardown message then we don't know the source but if source gets the message
 * then it shold remove that trail id from its finger table. But how does
 * source know what is the desination finger ? It will whenevr contact a trail
 * will do a lookup in routing table and if no trail id present the remove
 * that trail of the finger and if only one trail then remove the finger.
 * because of this use case of trail teardown I think trail compression
 * and trail teardown should not be merged.
 * 2. store a pointer to friendInfo in place o peer identity.
 */
/**
 * Maximum number of entries in routing table.
 */
#define ROUTING_TABLE_THRESHOLD 80000

/**
 * FIXME: Store friend pointer instead of peer identifier.
 * Routing table entry .
 */
struct RoutingTrail
{
  /**
   * Global Unique identifier of the trail.
   */
  struct GNUNET_HashCode trail_id;

  /**
   * The peer to which this request should be passed to.
   */
  struct GNUNET_PeerIdentity next_hop;

  /**
   * Peer just before next hop in the trail.
   */
  struct GNUNET_PeerIdentity prev_hop;
};

/**
 * Routing table of the peer
 */
static struct GNUNET_CONTAINER_MultiHashMap *routing_table;

/**
 * Update the prev. hop of the trail. Call made by trail compression where
 * if you are the first friend now in the trail then you need to update
 * your prev. hop.
 * @param trail_id
 * @return #GNUNET_OK success
 *         #GNUNET_SYSERR in case no matching entry found in routing table.
 */
int
GDS_ROUTING_update_trail_prev_hop (const struct GNUNET_HashCode trail_id,
                                   struct GNUNET_PeerIdentity prev_hop)
{
  struct RoutingTrail *trail;

  trail = GNUNET_CONTAINER_multihashmap_get (routing_table, &trail_id);

  if (NULL == trail)
    return GNUNET_SYSERR;

  trail->prev_hop = prev_hop;
  return GNUNET_OK;
}

/**
 * Update the next hop of the trail. Call made by trail compression where
 * if you are source of the trail and now you have a new first friend, then
 * you should update the trail.
 * @param trail_id
 * @return #GNUNET_OK success
 *         #GNUNET_SYSERR in case no matching entry found in routing table.
 */
int
GDS_ROUTING_update_trail_next_hop (const struct GNUNET_HashCode trail_id,
                                   struct GNUNET_PeerIdentity next_hop)
{
  struct RoutingTrail *trail;

  trail = GNUNET_CONTAINER_multihashmap_get (routing_table, &trail_id);

  if (NULL == trail)

    return GNUNET_SYSERR;

  trail->next_hop = next_hop;
  return GNUNET_OK;
}

/**
 * Get the next hop for trail corresponding to trail_id
 * @param trail_id Trail id to be searched.
 * @return Next_hop if found
 *         NULL If next hop not found.
 */
struct GNUNET_PeerIdentity *
GDS_ROUTING_get_next_hop (const struct GNUNET_HashCode trail_id,
                          enum GDS_ROUTING_trail_direction trail_direction)
{
  struct RoutingTrail *trail;

  trail = GNUNET_CONTAINER_multihashmap_get (routing_table, &trail_id);
  if (NULL == trail)
  {
    /* If a friend got disconnected and we removed all the entry from the
     routing table, then trail will be deleted and my identity will not know
     and when it tries to reach to that finger it fails. thats why
     assertion always fails in*/
    return NULL;
  }
  switch (trail_direction)
  {
    case GDS_ROUTING_SRC_TO_DEST:
      return &(trail->next_hop);
    case GDS_ROUTING_DEST_TO_SRC:
      return &(trail->prev_hop);
  }
  return NULL;
}


/**
 * Remove trail with trail_id
 * @param trail_id Trail id to be removed
 * @return #GNUNET_YES success
 *         #GNUNET_NO if entry not found.
 */
int
GDS_ROUTING_remove_trail (const struct GNUNET_HashCode remove_trail_id)
{
  struct RoutingTrail *remove_entry;

  remove_entry = GNUNET_CONTAINER_multihashmap_get (routing_table, &remove_trail_id);
  if (NULL == remove_entry)
    return GNUNET_NO;

  if (GNUNET_YES == GNUNET_CONTAINER_multihashmap_remove (routing_table,
                                                          &remove_trail_id,
                                                          remove_entry))
  {
    GNUNET_free (remove_entry);
    return GNUNET_YES;
  }

  return GNUNET_NO;
}


/**
 * Iterate over routing table and remove entries with value as part of any trail.
 *
 * @param cls closure
 * @param key current public key
 * @param value value in the hash map
 * @return #GNUNET_YES if we should continue to iterate,
 *         #GNUNET_NO if not.
 */
static int remove_matching_trails (void *cls,
                                   const struct GNUNET_HashCode *key,
                                   void *value)
{
  struct RoutingTrail *remove_trail = value;
  struct GNUNET_PeerIdentity *disconnected_peer = cls;
  struct GNUNET_HashCode trail_id = *key;
  struct GNUNET_PeerIdentity my_identity;

  /* If disconnected_peer is next_hop, then send a trail teardown message through
   * prev_hop in direction from destination to source. */
  if (0 == GNUNET_CRYPTO_cmp_peer_identity (&remove_trail->next_hop,
                                            disconnected_peer))
  {
    my_identity = GDS_NEIGHBOURS_get_my_id ();
    if (0 != GNUNET_CRYPTO_cmp_peer_identity (&my_identity,
                                              &remove_trail->prev_hop))
    {
      GDS_NEIGHBOURS_send_trail_teardown (&trail_id,
                                          GDS_ROUTING_DEST_TO_SRC,
                                          &remove_trail->prev_hop);
    }
  }

  /* If disconnected_peer is prev_hop, then send a trail teardown through
   * next_hop in direction from Source to Destination. */
  if (0 == GNUNET_CRYPTO_cmp_peer_identity (&remove_trail->prev_hop,
                                            disconnected_peer))
  {
    my_identity = GDS_NEIGHBOURS_get_my_id ();

    if (0 != GNUNET_CRYPTO_cmp_peer_identity (&my_identity,
                                              &remove_trail->next_hop))
    {
      GDS_NEIGHBOURS_send_trail_teardown (&trail_id,
                                          GDS_ROUTING_SRC_TO_DEST,
                                          &remove_trail->next_hop);
    }
  }

  GNUNET_assert (GNUNET_YES ==
                   GNUNET_CONTAINER_multihashmap_remove (routing_table,
                                                         &trail_id,
                                                         remove_trail));
  GNUNET_free (remove_trail);
  return GNUNET_YES;
}

#if 0
/**
 * TEST FUNCTION
 * Remove after using.
 */
void
GDS_ROUTING_test_print (void)
{
  struct GNUNET_CONTAINER_MultiHashMapIterator *iter;
  struct RoutingTrail *trail;
  struct GNUNET_PeerIdentity print_peer;
  struct GNUNET_HashCode key_ret;
  int i;

  struct GNUNET_PeerIdentity my_identity = GDS_NEIGHBOURS_get_my_id();
  print_peer = my_identity;
   FPRINTF (stderr,_("\nSUPU ***PRINTING ROUTING TABLE ***** of =%s"),GNUNET_i2s(&print_peer));
  iter =GNUNET_CONTAINER_multihashmap_iterator_create (routing_table);
  for (i = 0; i < GNUNET_CONTAINER_multihashmap_size(routing_table); i++)
  {
    if(GNUNET_YES == GNUNET_CONTAINER_multihashmap_iterator_next (iter,
                                                                  &key_ret,
                                                                  (const void **)&trail))
    {
      FPRINTF (stderr,_("\nSUPU %s, %s, %d, trail->trail_id = %s"),
              __FILE__, __func__,__LINE__, GNUNET_h2s(&trail->trail_id));
      memcpy (&print_peer, &trail->next_hop, sizeof (struct GNUNET_PeerIdentity));
      FPRINTF (stderr,_("\nSUPU %s, %s, %d, trail->next_hop = %s"),
              __FILE__, __func__,__LINE__, GNUNET_i2s(&print_peer));
      memcpy (&print_peer, &trail->prev_hop, sizeof (struct GNUNET_PeerIdentity));
      FPRINTF (stderr,_("\nSUPU %s, %s, %d, trail->prev_hop = %s"),
              __FILE__, __func__,__LINE__, GNUNET_i2s(&print_peer));
    }
  }
}
#endif

/**
 * Remove every trail where peer is either next_hop or prev_hop. Also send a
 * trail teardown message in direction of hop which is not disconnected.
 * @param peer Peer identity. Trail containing this peer should be removed.
 */
int
GDS_ROUTING_remove_trail_by_peer (const struct GNUNET_PeerIdentity *peer)
{
  int ret;


  /* No entries in my routing table. */
  if (0 == GNUNET_CONTAINER_multihashmap_size(routing_table))
    return GNUNET_YES;

  ret = GNUNET_CONTAINER_multihashmap_iterate (routing_table,
                                               &remove_matching_trails,
                                               (void *)peer);
  return ret;
}


/**
 * Add a new entry in routing table
 * @param new_trail_id
 * @param prev_hop
 * @param next_hop
 * @return #GNUNET_OK success
 *         #GNUNET_SYSERR in case new_trail_id already exists in the network
 *                         but with different prev_hop/next_hop
 */
int
GDS_ROUTING_add (struct GNUNET_HashCode new_trail_id,
                 struct GNUNET_PeerIdentity prev_hop,
                 struct GNUNET_PeerIdentity next_hop)
{
  struct RoutingTrail *new_entry;

  new_entry = GNUNET_new (struct RoutingTrail);
  new_entry->trail_id = new_trail_id;
  new_entry->next_hop = next_hop;
  new_entry->prev_hop = prev_hop;


  return GNUNET_CONTAINER_multihashmap_put (routing_table,
                                            &new_trail_id, new_entry,
                                            GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY);

}


/**
 * Check if the size of routing table has crossed ROUTING_TABLE_THRESHOLD.
 * It means that I don't have any more space in my routing table and I can not
 * be part of any more trails till there is free space in my routing table.
 * @return #GNUNET_YES, if threshold crossed else #GNUNET_NO.
 */
int
GDS_ROUTING_threshold_reached (void)
{
  return (GNUNET_CONTAINER_multihashmap_size(routing_table) >
          ROUTING_TABLE_THRESHOLD) ? GNUNET_YES:GNUNET_NO;
}


/**
 * Initialize routing subsystem.
 */
void
GDS_ROUTING_init (void)
{
  routing_table = GNUNET_CONTAINER_multihashmap_create (ROUTING_TABLE_THRESHOLD * 4 / 3,
                                                        GNUNET_NO);
}


/**
 * Shutdown routing subsystem.
 */
void
GDS_ROUTING_done (void)
{
  GNUNET_assert (0 == GNUNET_CONTAINER_multihashmap_size (routing_table));
  GNUNET_CONTAINER_multihashmap_destroy (routing_table);
}

/* end of gnunet-service-xdht_routing.c */