gnunet-service-cadet_peer.c

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/*
     This file is part of GNUnet.
     Copyright (C) 2001-2017 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/>.
 
     SPDX-License-Identifier: AGPL3.0-or-later
 */
 
#include "platform.h"
#include "gnunet_time_lib.h"
#include "gnunet_util_lib.h"
#include "gnunet_hello_lib.h"
#include "gnunet_signatures.h"
#include "gnunet_transport_service.h"
#include "gnunet_ats_service.h"
#include "gnunet_core_service.h"
#include "gnunet_statistics_service.h"
#include "gnunet-service-cadet_peer.h"
#include "gnunet-service-cadet.h"
#include "gnunet-service-cadet_connection.h"
#include "gnunet-service-cadet_dht.h"
#include "gnunet-service-cadet_paths.h"
#include "gnunet-service-cadet_tunnels.h"
 
 
#define LOG(level, ...) GNUNET_log_from (level, "cadet-per", __VA_ARGS__)
 
 
#define IDLE_PEER_TIMEOUT GNUNET_TIME_relative_multiply ( \
    GNUNET_TIME_UNIT_MINUTES, 5)
 
#define IDLE_PATH_TIMEOUT GNUNET_TIME_relative_multiply ( \
    GNUNET_TIME_UNIT_MINUTES, 2)
 
#define MAX_OOO_QUEUE_SIZE  100
 
struct GCP_MessageQueueManager
{
  struct GCP_MessageQueueManager *next;
 
  struct GCP_MessageQueueManager *prev;
 
  GCP_MessageQueueNotificationCallback cb;
 
  void *cb_cls;
 
  struct CadetPeer *cp;
 
  struct GNUNET_MQ_Envelope *env;
};
 
 
struct CadetPeer
{
  struct GNUNET_PeerIdentity pid;
 
  struct GNUNET_TIME_Absolute last_connection_create;
 
  struct CadetPeerPathEntry **path_heads;
 
  struct CadetPeerPathEntry **path_tails;
 
  struct GCP_MessageQueueManager *mqm_head;
 
  struct GCP_MessageQueueManager *mqm_tail;
 
  struct GCP_MessageQueueManager *mqm_ready_ptr;
 
  struct GNUNET_CONTAINER_Heap *path_heap;
 
  struct GCD_search_handle *search_h;
 
  struct GNUNET_SCHEDULER_Task *heap_cleanup_task;
 
  struct GNUNET_SCHEDULER_Task *destroy_task;
 
  struct CadetTunnel *t;
 
  struct GNUNET_CONTAINER_MultiShortmap *connections;
 
  struct GNUNET_MQ_Handle *core_mq;
 
  struct GNUNET_HELLO_Message *hello;
 
  struct GNUNET_TRANSPORT_OfferHelloHandle *hello_offer;
 
  struct GNUNET_ATS_ConnectivitySuggestHandle *connectivity_suggestion;
 
  unsigned int queue_n;
 
  unsigned int num_paths;
 
  unsigned int off_sum;
 
  unsigned int mqm_ready_counter;
 
  unsigned int path_dll_length;
};
 
 
const char *
GCP_2s (const struct CadetPeer *cp)
{
  static char buf[5];
  char *ret;
 
  if ((NULL == cp) ||
      (GNUNET_YES == GNUNET_is_zero (&cp->pid.public_key)))
    return "NULL";
 
  ret = GNUNET_CRYPTO_eddsa_public_key_to_string (&cp->pid.public_key);
  if (NULL == ret)
    return "NULL";
 
  GNUNET_strlcpy (buf,
                  ret,
                  sizeof(buf));
  GNUNET_free (ret);
  return buf;
}
 
 
double
GCP_get_desirability_of_path (struct CadetPeer *cp,
                              unsigned int off)
{
  unsigned int num_alts = cp->num_paths;
  unsigned int off_sum;
  double avg_sum;
  double path_delta;
  double weight_alts;
 
  GNUNET_assert (num_alts >= 1);  /* 'path' should be in there! */
  GNUNET_assert (0 != cp->path_dll_length);
 
  /* We maintain 'off_sum' in 'peer' and thereby
     avoid the SLOW recalculation each time. Kept here
     just to document what is going on. */
#if SLOW
  off_sum = 0;
  for (unsigned int j = 0; j < cp->path_dll_length; j++)
    for (struct CadetPeerPathEntry *pe = cp->path_heads[j];
         NULL != pe;
         pe = pe->next)
      off_sum += j;
  GNUNET_assert (off_sum == cp->off_sum);
#else
  off_sum = cp->off_sum;
#endif
  avg_sum = off_sum * 1.0 / cp->path_dll_length;
  path_delta = off - avg_sum;
  /* path_delta positive: path off of peer above average (bad path for peer),
     path_delta negative: path off of peer below average (good path for peer) */
  if (path_delta <= -1.0)
    weight_alts = -num_alts / path_delta;  /* discount alternative paths */
  else if (path_delta >= 1.0)
    weight_alts = num_alts * path_delta; /* overcount alternative paths */
  else
    weight_alts = num_alts; /* count alternative paths normally */
 
 
  /* off+1: long paths are generally harder to find and thus count
     a bit more as they get longer.  However, above-average paths
     still need to count less, hence the squaring of that factor. */
  return (off + 1.0) / (weight_alts * weight_alts);
}
 
 
static void
destroy_peer (void *cls)
{
  struct CadetPeer *cp = cls;
 
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Destroying state about peer %s\n",
       GCP_2s (cp));
  cp->destroy_task = NULL;
  GNUNET_assert (NULL == cp->t);
  GNUNET_assert (NULL == cp->core_mq);
  GNUNET_assert (0 == cp->num_paths);
  for (unsigned int i = 0; i < cp->path_dll_length; i++)
    GNUNET_assert (NULL == cp->path_heads[i]);
  GNUNET_assert (0 == GNUNET_CONTAINER_multishortmap_size (cp->connections));
  GNUNET_assert (GNUNET_YES ==
                 GNUNET_CONTAINER_multipeermap_remove (peers,
                                                       &cp->pid,
                                                       cp));
  GNUNET_free (cp->path_heads);
  GNUNET_free (cp->path_tails);
  cp->path_dll_length = 0;
  if (NULL != cp->search_h)
  {
    GCD_search_stop (cp->search_h);
    cp->search_h = NULL;
  }
  /* FIXME: clean up search_delayedXXX! */
 
  if (NULL != cp->hello_offer)
  {
    GNUNET_TRANSPORT_offer_hello_cancel (cp->hello_offer);
    cp->hello_offer = NULL;
  }
  if (NULL != cp->connectivity_suggestion)
  {
    GNUNET_ATS_connectivity_suggest_cancel (cp->connectivity_suggestion);
    cp->connectivity_suggestion = NULL;
  }
  GNUNET_CONTAINER_multishortmap_destroy (cp->connections);
  if (NULL != cp->path_heap)
  {
    GNUNET_CONTAINER_heap_destroy (cp->path_heap);
    cp->path_heap = NULL;
  }
  if (NULL != cp->heap_cleanup_task)
  {
    GNUNET_SCHEDULER_cancel (cp->heap_cleanup_task);
    cp->heap_cleanup_task = NULL;
  }
  GNUNET_free (cp->hello);
  /* Peer should not be freed if paths exist; if there are no paths,
     there ought to be no connections, and without connections, no
     notifications. Thus we can assert that mqm_head is empty at this
     point. */
  GNUNET_assert (NULL == cp->mqm_head);
  GNUNET_assert (NULL == cp->mqm_ready_ptr);
  GNUNET_free (cp);
}
 
 
static void
consider_peer_activate (struct CadetPeer *cp)
{
  uint32_t strength;
 
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Updating peer %s activation state (%u connections)%s%s\n",
       GCP_2s (cp),
       GNUNET_CONTAINER_multishortmap_size (cp->connections),
       (NULL == cp->t) ? "" : " with tunnel",
       (NULL == cp->core_mq) ? "" : " with CORE link");
  if (NULL != cp->destroy_task)
  {
    /* It's active, do not destroy! */
    GNUNET_SCHEDULER_cancel (cp->destroy_task);
    cp->destroy_task = NULL;
  }
  if ((0 == GNUNET_CONTAINER_multishortmap_size (cp->connections)) &&
      (NULL == cp->t))
  {
    /* We're just on a path or directly connected; don't bother too much */
    if (NULL != cp->connectivity_suggestion)
    {
      GNUNET_ATS_connectivity_suggest_cancel (cp->connectivity_suggestion);
      cp->connectivity_suggestion = NULL;
    }
    if (NULL != cp->search_h)
    {
      GCD_search_stop (cp->search_h);
      cp->search_h = NULL;
    }
    return;
  }
  if (NULL == cp->core_mq)
  {
    /* Lacks direct connection, try to create one by querying the DHT */
    if ((NULL == cp->search_h) &&
        (DESIRED_CONNECTIONS_PER_TUNNEL > cp->num_paths))
      cp->search_h
        = GCD_search (&cp->pid);
  }
  else
  {
    /* Have direct connection, stop DHT search if active */
    if (NULL != cp->search_h)
    {
      GCD_search_stop (cp->search_h);
      cp->search_h = NULL;
    }
  }
 
  /* If we have a tunnel, our urge for connections is much bigger */
  strength = (NULL != cp->t) ? 32 : 1;
  if (NULL != cp->connectivity_suggestion)
    GNUNET_ATS_connectivity_suggest_cancel (cp->connectivity_suggestion);
  cp->connectivity_suggestion
    = GNUNET_ATS_connectivity_suggest (ats_ch,
                                       &cp->pid,
                                       strength);
}
 
 
static void
consider_peer_destroy (struct CadetPeer *cp);
 
 
static void
drop_paths (void *cls)
{
  struct CadetPeer *cp = cls;
  struct CadetPeerPath *path;
 
  cp->destroy_task = NULL;
  while (NULL != (path = GNUNET_CONTAINER_heap_remove_root (cp->path_heap)))
    GCPP_release (path);
  consider_peer_destroy (cp);
}
 
 
static void
consider_peer_destroy (struct CadetPeer *cp)
{
  struct GNUNET_TIME_Relative exp;
 
  if (NULL != cp->destroy_task)
  {
    GNUNET_SCHEDULER_cancel (cp->destroy_task);
    cp->destroy_task = NULL;
  }
  if (NULL != cp->t)
    return; /* still relevant! */
  if (NULL != cp->core_mq)
    return; /* still relevant! */
  if (0 != GNUNET_CONTAINER_multishortmap_size (cp->connections))
    return; /* still relevant! */
  if ((NULL != cp->path_heap) &&
      (0 < GNUNET_CONTAINER_heap_get_size (cp->path_heap)))
  {
    cp->destroy_task = GNUNET_SCHEDULER_add_delayed (IDLE_PATH_TIMEOUT,
                                                     &drop_paths,
                                                     cp);
    return;
  }
  if (0 != cp->num_paths)
    return; /* still relevant! */
  if (NULL != cp->hello)
  {
    /* relevant only until HELLO expires */
    exp = GNUNET_TIME_absolute_get_remaining (GNUNET_HELLO_get_last_expiration (
                                                cp->hello));
    cp->destroy_task = GNUNET_SCHEDULER_add_delayed (exp,
                                                     &destroy_peer,
                                                     cp);
    return;
  }
  cp->destroy_task = GNUNET_SCHEDULER_add_delayed (IDLE_PEER_TIMEOUT,
                                                   &destroy_peer,
                                                   cp);
}
 
 
void
GCP_set_mq (struct CadetPeer *cp,
            struct GNUNET_MQ_Handle *mq)
{
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Message queue for peer %s is now %p\n",
       GCP_2s (cp),
       mq);
  cp->core_mq = mq;
  for (struct GCP_MessageQueueManager *mqm = cp->mqm_head, *next;
       NULL != mqm;
       mqm = next)
  {
    /* Save next pointer in case mqm gets freed by the callback */
    next = mqm->next;
    if (NULL == mq)
    {
      if (NULL != mqm->env)
      {
        GNUNET_MQ_discard (mqm->env);
        mqm->env = NULL;
        mqm->cb (mqm->cb_cls,
                 GNUNET_SYSERR);
      }
      else
      {
        mqm->cb (mqm->cb_cls,
                 GNUNET_NO);
      }
    }
    else
    {
      GNUNET_assert (NULL == mqm->env);
      mqm->cb (mqm->cb_cls,
               GNUNET_YES);
    }
  }
  if ((NULL != mq) ||
      (NULL != cp->t))
    consider_peer_activate (cp);
  else
    consider_peer_destroy (cp);
 
  if ((NULL != mq) &&
      (NULL != cp->t))
  {
    /* have a new, direct path to the target, notify tunnel */
    struct CadetPeerPath *path;
 
    path = GCPP_get_path_from_route (1,
                                     &cp->pid);
    GCT_consider_path (cp->t,
                       path,
                       0);
  }
}
 
 
static int
should_I_drop (void)
{
  if (0 == drop_percent)
    return GNUNET_NO;
  if (GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK,
                                101) < drop_percent)
    return GNUNET_YES;
  return GNUNET_NO;
}
 
 
static void
mqm_send_done (void *cls);
 
 
static void
mqm_execute (struct GCP_MessageQueueManager *mqm)
{
  struct CadetPeer *cp = mqm->cp;
 
  /* Move ready pointer to the next entry that might be ready. */
  if ((mqm == cp->mqm_ready_ptr) &&
      (NULL != mqm->next))
    cp->mqm_ready_ptr = mqm->next;
  /* Move entry to the end of the DLL, to be fair. */
  if (mqm != cp->mqm_tail)
  {
    GNUNET_CONTAINER_DLL_remove (cp->mqm_head,
                                 cp->mqm_tail,
                                 mqm);
    GNUNET_CONTAINER_DLL_insert_tail (cp->mqm_head,
                                      cp->mqm_tail,
                                      mqm);
  }
  cp->mqm_ready_counter--;
  if (GNUNET_YES == should_I_drop ())
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "DROPPING message to peer %s from MQM %p\n",
         GCP_2s (cp),
         mqm);
    GNUNET_MQ_discard (mqm->env);
    mqm->env = NULL;
    mqm_send_done (cp);
  }
  else
  {
    {
      const struct GNUNET_MessageHeader *mh;
 
      mh = GNUNET_MQ_env_get_msg (mqm->env);
      switch (ntohs (mh->type))
      {
      case GNUNET_MESSAGE_TYPE_CADET_TUNNEL_KX:
        {
          const struct GNUNET_CADET_TunnelKeyExchangeMessage *msg
            = (const struct GNUNET_CADET_TunnelKeyExchangeMessage *) mh;
          LOG (GNUNET_ERROR_TYPE_DEBUG,
               "P2P forwarding KX with ephemeral %s to %s on CID %s\n",
               GNUNET_e2s (&msg->ephemeral_key),
               GCP_2s (cp),
               GNUNET_sh2s (&msg->cid.connection_of_tunnel));
        }
        break;
 
      default:
        break;
      }
    }
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Sending to peer %s from MQM %p\n",
         GCP_2s (cp),
         mqm);
    GNUNET_MQ_send (cp->core_mq,
                    mqm->env);
    mqm->env = NULL;
  }
  mqm->cb (mqm->cb_cls,
           GNUNET_YES);
}
 
 
static void
send_next_ready (struct CadetPeer *cp)
{
  struct GCP_MessageQueueManager *mqm;
 
  if (0 == cp->mqm_ready_counter)
    return;
  while ((NULL != (mqm = cp->mqm_ready_ptr)) &&
         (NULL == mqm->env))
    cp->mqm_ready_ptr = mqm->next;
  if (NULL == mqm)
    return; /* nothing to do */
  mqm_execute (mqm);
}
 
 
static void
mqm_send_done (void *cls)
{
  struct CadetPeer *cp = cls;
 
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Sending to peer %s completed\n",
       GCP_2s (cp));
  send_next_ready (cp);
}
 
 
void
GCP_send (struct GCP_MessageQueueManager *mqm,
          struct GNUNET_MQ_Envelope *env)
{
  struct CadetPeer *cp = mqm->cp;
 
  GNUNET_assert (NULL != env);
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Queueing message to peer %s in MQM %p\n",
       GCP_2s (cp),
       mqm);
  GNUNET_assert (NULL != cp->core_mq);
  GNUNET_assert (NULL == mqm->env);
  GNUNET_MQ_notify_sent (env,
                         &mqm_send_done,
                         cp);
  mqm->env = env;
  cp->mqm_ready_counter++;
  if (mqm != cp->mqm_ready_ptr)
    cp->mqm_ready_ptr = cp->mqm_head;
  if (1 == cp->mqm_ready_counter)
    cp->mqm_ready_ptr = mqm;
  if (0 != GNUNET_MQ_get_length (cp->core_mq))
    return;
  send_next_ready (cp);
}
 
 
static int
destroy_iterator_cb (void *cls,
                     const struct GNUNET_PeerIdentity *pid,
                     void *value)
{
  struct CadetPeer *cp = value;
 
  if (NULL != cp->destroy_task)
  {
    GNUNET_SCHEDULER_cancel (cp->destroy_task);
    cp->destroy_task = NULL;
  }
  destroy_peer (cp);
  return GNUNET_OK;
}
 
 
void
GCP_destroy_all_peers ()
{
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Destroying all peers now\n");
  GNUNET_CONTAINER_multipeermap_iterate (peers,
                                         &destroy_iterator_cb,
                                         NULL);
}
 
 
void
GCP_drop_owned_paths (struct CadetPeer *cp)
{
  struct CadetPeerPath *path;
 
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Destroying all paths to %s\n",
       GCP_2s (cp));
  while (NULL != (path =
                    GNUNET_CONTAINER_heap_remove_root (cp->path_heap)))
    GCPP_release (path);
  GNUNET_CONTAINER_heap_destroy (cp->path_heap);
  cp->path_heap = NULL;
}
 
 
void
GCP_path_entry_add (struct CadetPeer *cp,
                    struct CadetPeerPathEntry *entry,
                    unsigned int off)
{
  GNUNET_assert (cp == GCPP_get_peer_at_offset (entry->path,
                                                off));
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Discovered that peer %s is on path %s at offset %u\n",
       GCP_2s (cp),
       GCPP_2s (entry->path),
       off);
  if (off >= cp->path_dll_length)
  {
    unsigned int len = cp->path_dll_length;
 
    GNUNET_array_grow (cp->path_heads,
                       len,
                       off + 4);
    GNUNET_array_grow (cp->path_tails,
                       cp->path_dll_length,
                       off + 4);
  }
  GNUNET_CONTAINER_DLL_insert (cp->path_heads[off],
                               cp->path_tails[off],
                               entry);
  cp->off_sum += off;
  cp->num_paths++;
 
  /* If we have a tunnel to this peer, tell the tunnel that there is a
     new path available. */
  if (NULL != cp->t)
    GCT_consider_path (cp->t,
                       entry->path,
                       off);
 
  if ((NULL != cp->search_h) &&
      (DESIRED_CONNECTIONS_PER_TUNNEL <= cp->num_paths))
  {
    /* Now I have enough paths, stop search */
    GCD_search_stop (cp->search_h);
    cp->search_h = NULL;
  }
  if (NULL != cp->destroy_task)
  {
    /* paths changed, this resets the destroy timeout counter
       and aborts a destroy task that may no longer be valid
       to have (as we now have more paths via this peer). */
    consider_peer_destroy (cp);
  }
}
 
 
void
GCP_path_entry_remove (struct CadetPeer *cp,
                       struct CadetPeerPathEntry *entry,
                       unsigned int off)
{
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Removing knowledge about peer %s beging on path %s at offset %u\n",
       GCP_2s (cp),
       GCPP_2s (entry->path),
       off);
  GNUNET_CONTAINER_DLL_remove (cp->path_heads[off],
                               cp->path_tails[off],
                               entry);
  GNUNET_assert (0 < cp->num_paths);
  cp->off_sum -= off;
  cp->num_paths--;
  if ((NULL == cp->core_mq) &&
      (NULL != cp->t) &&
      (NULL == cp->search_h) &&
      (DESIRED_CONNECTIONS_PER_TUNNEL > cp->num_paths))
    cp->search_h
      = GCD_search (&cp->pid);
  if (NULL == cp->destroy_task)
  {
    /* paths changed, we might now be ready for destruction, check again */
    consider_peer_destroy (cp);
  }
}
 
 
static void
path_heap_cleanup (void *cls)
{
  struct CadetPeer *cp = cls;
  struct CadetPeerPath *root;
 
  cp->heap_cleanup_task = NULL;
  while (GNUNET_CONTAINER_heap_get_size (cp->path_heap) >=
         2 * DESIRED_CONNECTIONS_PER_TUNNEL)
  {
    /* Now we have way too many, drop least desirable UNLESS it is in use!
       (Note that this intentionally keeps highly desirable, but currently
       unused paths around in the hope that we might be able to switch, even
       if the number of paths exceeds the threshold.) */
    root = GNUNET_CONTAINER_heap_peek (cp->path_heap);
    GNUNET_assert (NULL != root);
    if (NULL !=
        GCPP_get_connection (root,
                             cp,
                             GCPP_get_length (root) - 1))
      break;   /* can't fix */
    /* Got plenty of paths to this destination, and this is a low-quality
       one that we don't care about. Allow it to die. */
    GNUNET_assert (root ==
                   GNUNET_CONTAINER_heap_remove_root (cp->path_heap));
    GCPP_release (root);
  }
}
 
 
struct GNUNET_CONTAINER_HeapNode *
GCP_attach_path (struct CadetPeer *cp,
                 struct CadetPeerPath *path,
                 unsigned int off,
                 int force)
{
  GNUNET_CONTAINER_HeapCostType desirability;
  struct CadetPeerPath *root;
  GNUNET_CONTAINER_HeapCostType root_desirability;
  struct GNUNET_CONTAINER_HeapNode *hn;
 
  GNUNET_assert (off == GCPP_get_length (path) - 1);
  GNUNET_assert (cp == GCPP_get_peer_at_offset (path,
                                                off));
  if (NULL == cp->path_heap)
  {
    /* #GCP_drop_owned_paths() was already called, we cannot take new ones! */
    GNUNET_assert (GNUNET_NO == force);
    return NULL;
  }
  desirability = GCPP_get_desirability (path);
  if (GNUNET_NO == force)
  {
    /* FIXME: desirability is not yet initialized; tricky! */
    if (GNUNET_NO ==
        GNUNET_CONTAINER_heap_peek2 (cp->path_heap,
                                     (void **) &root,
                                     &root_desirability))
    {
      root = NULL;
      root_desirability = 0;
    }
 
    if ((DESIRED_CONNECTIONS_PER_TUNNEL > cp->num_paths) &&
        (desirability < root_desirability))
    {
      LOG (GNUNET_ERROR_TYPE_DEBUG,
           "Decided to not attach path %s to peer %s due to undesirability\n",
           GCPP_2s (path),
           GCP_2s (cp));
      return NULL;
    }
  }
 
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Attaching path %s to peer %s (%s)\n",
       GCPP_2s (path),
       GCP_2s (cp),
       (GNUNET_NO == force) ? "desirable" : "forced");
 
  /* Yes, we'd like to add this path, add to our heap */
  hn = GNUNET_CONTAINER_heap_insert (cp->path_heap,
                                     path,
                                     desirability);
 
  /* Consider maybe dropping other paths because of the new one */
  if ((GNUNET_CONTAINER_heap_get_size (cp->path_heap) >=
       2 * DESIRED_CONNECTIONS_PER_TUNNEL) &&
      (NULL != cp->heap_cleanup_task))
    cp->heap_cleanup_task = GNUNET_SCHEDULER_add_now (&path_heap_cleanup,
                                                      cp);
  return hn;
}
 
 
void
GCP_detach_path (struct CadetPeer *cp,
                 struct CadetPeerPath *path,
                 struct GNUNET_CONTAINER_HeapNode *hn)
{
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Detaching path %s from peer %s\n",
       GCPP_2s (path),
       GCP_2s (cp));
  GNUNET_assert (path ==
                 GNUNET_CONTAINER_heap_remove_node (hn));
}
 
 
void
GCP_add_connection (struct CadetPeer *cp,
                    struct CadetConnection *cc)
{
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Adding %s to peer %s\n",
       GCC_2s (cc),
       GCP_2s (cp));
  GNUNET_assert (GNUNET_OK ==
                 GNUNET_CONTAINER_multishortmap_put (cp->connections,
                                                     &GCC_get_id (
                                                       cc)->connection_of_tunnel,
                                                     cc,
                                                     GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
  if (NULL != cp->destroy_task)
  {
    GNUNET_SCHEDULER_cancel (cp->destroy_task);
    cp->destroy_task = NULL;
  }
}
 
 
void
GCP_remove_connection (struct CadetPeer *cp,
                       struct CadetConnection *cc)
{
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Removing connection %s from peer %s\n",
       GCC_2s (cc),
       GCP_2s (cp));
  GNUNET_assert (GNUNET_YES ==
                 GNUNET_CONTAINER_multishortmap_remove (cp->connections,
                                                        &GCC_get_id (
                                                          cc)->
                                                        connection_of_tunnel,
                                                        cc));
  consider_peer_destroy (cp);
}
 
 
struct CadetPeer *
GCP_get (const struct GNUNET_PeerIdentity *peer_id,
         int create)
{
  struct CadetPeer *cp;
 
  cp = GNUNET_CONTAINER_multipeermap_get (peers,
                                          peer_id);
  if (NULL != cp)
    return cp;
  if (GNUNET_NO == create)
    return NULL;
  cp = GNUNET_new (struct CadetPeer);
  cp->pid = *peer_id;
  cp->connections = GNUNET_CONTAINER_multishortmap_create (32,
                                                           GNUNET_YES);
  cp->path_heap = GNUNET_CONTAINER_heap_create (
    GNUNET_CONTAINER_HEAP_ORDER_MIN);
  GNUNET_assert (GNUNET_YES ==
                 GNUNET_CONTAINER_multipeermap_put (peers,
                                                    &cp->pid,
                                                    cp,
                                                    GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Creating peer %s\n",
       GCP_2s (cp));
  return cp;
}
 
 
const struct GNUNET_PeerIdentity *
GCP_get_id (struct CadetPeer *cp)
{
  return &cp->pid;
}
 
 
void
GCP_iterate_all (GNUNET_CONTAINER_PeerMapIterator iter,
                 void *cls)
{
  GNUNET_CONTAINER_multipeermap_iterate (peers,
                                         iter,
                                         cls);
}
 
 
unsigned int
GCP_count_paths (const struct CadetPeer *cp)
{
  return cp->num_paths;
}
 
 
unsigned int
GCP_iterate_paths (struct CadetPeer *cp,
                   GCP_PathIterator callback,
                   void *callback_cls)
{
  unsigned int ret = 0;
 
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Iterating over paths to peer %s%s\n",
       GCP_2s (cp),
       (NULL == cp->core_mq) ? "" : " including direct link");
  if (NULL != cp->core_mq)
  {
    /* FIXME: this branch seems to duplicate the
       i=0 case below (direct link). Leave out!??? -CG */
    struct CadetPeerPath *path;
 
    path = GCPP_get_path_from_route (1,
                                     &cp->pid);
    ret++;
    if (GNUNET_NO ==
        callback (callback_cls,
                  path,
                  0))
      return ret;
  }
  for (unsigned int i = 0; i < cp->path_dll_length; i++)
  {
    for (struct CadetPeerPathEntry *pe = cp->path_heads[i];
         NULL != pe;
         pe = pe->next)
    {
      ret++;
      if (GNUNET_NO ==
          callback (callback_cls,
                    pe->path,
                    i))
        return ret;
    }
  }
  return ret;
}
 
 
unsigned int
GCP_iterate_indirect_paths (struct CadetPeer *cp,
                            GCP_PathIterator callback,
                            void *callback_cls)
{
  unsigned int ret = 0;
 
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Iterating over paths to peer %s without direct link\n",
       GCP_2s (cp));
  for (unsigned int i = 1; i < cp->path_dll_length; i++)
  {
    for (struct CadetPeerPathEntry *pe = cp->path_heads[i];
         NULL != pe;
         pe = pe->next)
    {
      ret++;
      if (GNUNET_NO ==
          callback (callback_cls,
                    pe->path,
                    i))
        return ret;
    }
  }
  return ret;
}
 
 
unsigned int
GCP_iterate_paths_at (struct CadetPeer *cp,
                      unsigned int dist,
                      GCP_PathIterator callback,
                      void *callback_cls)
{
  unsigned int ret = 0;
 
  if (dist >= cp->path_dll_length)
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Asked to look for paths at distance %u, but maximum for me is < %u\n",
         dist,
         cp->path_dll_length);
    return 0;
  }
  for (struct CadetPeerPathEntry *pe = cp->path_heads[dist];
       NULL != pe;
       pe = pe->next)
  {
    if (GNUNET_NO ==
        callback (callback_cls,
                  pe->path,
                  dist))
      return ret;
    ret++;
  }
  return ret;
}
 
 
struct CadetTunnel *
GCP_get_tunnel (struct CadetPeer *cp,
                int create)
{
  if (NULL == cp)
    return NULL;
  if ((NULL != cp->t) ||
      (GNUNET_NO == create))
    return cp->t;
  cp->t = GCT_create_tunnel (cp);
  consider_peer_activate (cp);
  return cp->t;
}
 
 
static void
hello_offer_done (void *cls)
{
  struct CadetPeer *cp = cls;
 
  cp->hello_offer = NULL;
}
 
 
void
GCP_set_hello (struct CadetPeer *cp,
               const struct GNUNET_HELLO_Message *hello)
{
  struct GNUNET_HELLO_Message *mrg;
 
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Got %u byte HELLO for peer %s\n",
       (unsigned int) GNUNET_HELLO_size (hello),
       GCP_2s (cp));
  if (NULL != cp->hello_offer)
  {
    GNUNET_TRANSPORT_offer_hello_cancel (cp->hello_offer);
    cp->hello_offer = NULL;
  }
  if (NULL != cp->hello)
  {
    mrg = GNUNET_HELLO_merge (hello,
                              cp->hello);
    GNUNET_free (cp->hello);
    cp->hello = mrg;
  }
  else
  {
    cp->hello = GNUNET_memdup (hello,
                               GNUNET_HELLO_size (hello));
  }
  cp->hello_offer
    = GNUNET_TRANSPORT_offer_hello (cfg,
                                    GNUNET_HELLO_get_header (cp->hello),
                                    &hello_offer_done,
                                    cp);
  /* New HELLO means cp's destruction time may change... */
  consider_peer_destroy (cp);
}
 
 
void
GCP_drop_tunnel (struct CadetPeer *cp,
                 struct CadetTunnel *t)
{
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Dropping tunnel %s to peer %s\n",
       GCT_2s (t),
       GCP_2s (cp));
  GNUNET_assert (cp->t == t);
  cp->t = NULL;
  consider_peer_destroy (cp);
}
 
 
int
GCP_has_core_connection (struct CadetPeer *cp)
{
  return (NULL != cp->core_mq) ? GNUNET_YES : GNUNET_NO;
}
 
 
struct GCP_MessageQueueManager *
GCP_request_mq (struct CadetPeer *cp,
                GCP_MessageQueueNotificationCallback cb,
                void *cb_cls)
{
  struct GCP_MessageQueueManager *mqm;
 
  mqm = GNUNET_new (struct GCP_MessageQueueManager);
  mqm->cb = cb;
  mqm->cb_cls = cb_cls;
  mqm->cp = cp;
  GNUNET_CONTAINER_DLL_insert (cp->mqm_head,
                               cp->mqm_tail,
                               mqm);
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Creating MQM %p for peer %s\n",
       mqm,
       GCP_2s (cp));
  if (NULL != cp->core_mq)
    cb (cb_cls,
        GNUNET_YES);
  return mqm;
}
 
 
void
GCP_request_mq_cancel (struct GCP_MessageQueueManager *mqm,
                       struct GNUNET_MQ_Envelope *last_env)
{
  struct CadetPeer *cp = mqm->cp;
 
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Destroying MQM %p for peer %s%s\n",
       mqm,
       GCP_2s (cp),
       (NULL == last_env) ? "" : " with last ditch transmission");
  if (NULL != mqm->env)
    GNUNET_MQ_discard (mqm->env);
  if (NULL != last_env)
  {
    if (NULL != cp->core_mq)
    {
      GNUNET_MQ_notify_sent (last_env,
                             &mqm_send_done,
                             cp);
      GNUNET_MQ_send (cp->core_mq,
                      last_env);
    }
    else
    {
      GNUNET_MQ_discard (last_env);
    }
  }
  if (cp->mqm_ready_ptr == mqm)
    cp->mqm_ready_ptr = mqm->next;
  GNUNET_CONTAINER_DLL_remove (cp->mqm_head,
                               cp->mqm_tail,
                               mqm);
  GNUNET_free (mqm);
}
 
 
void
GCP_send_ooo (struct CadetPeer *cp,
              struct GNUNET_MQ_Envelope *env)
{
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Sending message to %s out of management\n",
       GCP_2s (cp));
  if (NULL == cp->core_mq)
  {
    GNUNET_MQ_discard (env);
    return;
  }
  if (GNUNET_MQ_get_length (cp->core_mq) > MAX_OOO_QUEUE_SIZE)
  {
    GNUNET_MQ_discard (env);
    return;
  }
  GNUNET_MQ_notify_sent (env,
                         &mqm_send_done,
                         cp);
  GNUNET_MQ_send (cp->core_mq,
                  env);
}
 
 
int
GCP_check_and_update_monotime (struct CadetPeer *peer,
                               struct GNUNET_TIME_AbsoluteNBO monotime)
{
 
  struct GNUNET_TIME_Absolute mt = GNUNET_TIME_absolute_ntoh (monotime);
 
  if (mt.abs_value_us > *(&peer->last_connection_create.abs_value_us))
  {
    peer->last_connection_create = mt;
    return GNUNET_YES;
  }
  return GNUNET_NO;
}
 
 
int
GCP_check_monotime_sig (struct CadetPeer *peer,
                        const struct GNUNET_CADET_ConnectionCreateMessage *msg)
{
  struct CadetConnectionCreatePS cp = { .purpose.purpose = htonl (
                                          GNUNET_SIGNATURE_PURPOSE_CADET_CONNECTION_INITIATOR),
                                        .purpose.size = htonl (sizeof(cp)),
                                        .monotonic_time = msg->monotime};
 
  if (GNUNET_OK !=
      GNUNET_CRYPTO_eddsa_verify (
        GNUNET_SIGNATURE_PURPOSE_CADET_CONNECTION_INITIATOR,
        &cp,
        &msg->monotime_sig,
        &peer->pid.public_key))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  return GNUNET_OK;
}
 
 
/* end of gnunet-service-cadet-new_peer.c */