detecting duplicate connects

[oweals/gnunet.git] / src / transport / gnunet-service-transport_neighbours.c

/*
     This file is part of GNUnet.
     (C) 2010-2013 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 transport/gnunet-service-transport_neighbours.c
 * @brief neighbour management
 * @author Christian Grothoff
 */
#include "platform.h"
#include "gnunet_ats_service.h"
#include "gnunet-service-transport_neighbours.h"
#include "gnunet-service-transport_plugins.h"
#include "gnunet-service-transport_validation.h"
#include "gnunet-service-transport_clients.h"
#include "gnunet-service-transport.h"
#include "gnunet_peerinfo_service.h"
#include "gnunet-service-transport_blacklist.h"
#include "gnunet_constants.h"
#include "transport.h"



/**
 * Size of the neighbour hash map.
 */
#define NEIGHBOUR_TABLE_SIZE 256

/**
 * Time we give plugin to transmit DISCONNECT message before the
 * neighbour entry self-destructs.
 */
#define DISCONNECT_SENT_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MILLISECONDS, 500)

/**
 * How often must a peer violate bandwidth quotas before we start
 * to simply drop its messages?
 */
#define QUOTA_VIOLATION_DROP_THRESHOLD 10

/**
 * How long are we willing to wait for a response from ATS before timing out?
 */
#define ATS_RESPONSE_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MILLISECONDS, 5000)

/**
 * How long are we willing to wait for an ACK from the other peer before
 * giving up on our connect operation?
 */
#define SETUP_CONNECTION_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 15)

/**
 * How long are we willing to wait for a successful reconnect if
 * an existing connection went down?  Much shorter than the
 * usual SETUP_CONNECTION_TIMEOUT as we do not inform the
 * higher layers about the disconnect during this period.
 */
#define FAST_RECONNECT_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 1)

/**
 * How long are we willing to wait for a response from the blacklist
 * subsystem before timing out?
 */
#define BLACKLIST_RESPONSE_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MILLISECONDS, 500)

/**
 * Interval to send utilization data
 */
#define UTIL_TRANSMISSION_INTERVAL GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 1)

/**
 * State describing which kind a reply this neighbour should send
 */
enum GST_ACK_State
{
  /**
   * We did not receive a CONNECT message for this neighbour
   */
  ACK_UNDEFINED = 0,

  /* The neighbour received a CONNECT message and has to send a CONNECT_ACK
   * as reply */
  ACK_SEND_CONNECT_ACK = 1,

  /* The neighbour sent a CONNECT_ACK message and has to send a SESSION_ACK
   * as reply */
  ACK_SEND_SESSION_ACK = 2
};


GNUNET_NETWORK_STRUCT_BEGIN

/**
 * Message a peer sends to another to indicate that it intends to
 * setup a connection/session for data exchange.  A 'SESSION_CONNECT'
 * should be answered with a 'SESSION_CONNECT_ACK' with the same body
 * to confirm.  A 'SESSION_CONNECT_ACK' should then be followed with
 * a 'SESSION_ACK'.  Once the 'SESSION_ACK' is received, both peers
 * should be connected.
 */
struct SessionConnectMessage
{
  /**
   * Header of type #GNUNET_MESSAGE_TYPE_TRANSPORT_SESSION_CONNECT
   * or #GNUNET_MESSAGE_TYPE_TRANSPORT_SESSION_CONNECT_ACK
   */
  struct GNUNET_MessageHeader header;

  /**
   * Always zero.
   */
  uint32_t reserved GNUNET_PACKED;

  /**
   * Absolute time at the sender.  Only the most recent connect
   * message implies which session is preferred by the sender.
   */
  struct GNUNET_TIME_AbsoluteNBO timestamp;

};


/**
 * Message a peer sends to another when connected to indicate that a
 * session is in use and the peer is still alive or to respond to a keep alive.
 * A peer sends a message with type #GNUNET_MESSAGE_TYPE_TRANSPORT_SESSION_KEEPALIVE
 * to request a message with #GNUNET_MESSAGE_TYPE_TRANSPORT_SESSION_KEEPALIVE_RESPONSE.
 * When the keep alive response with type is received, transport service
 * will call the respective plugin to update the session timeout
 */
struct SessionKeepAliveMessage
{
  /**
   * Header of type #GNUNET_MESSAGE_TYPE_TRANSPORT_SESSION_KEEPALIVE or
   * #GNUNET_MESSAGE_TYPE_TRANSPORT_SESSION_KEEPALIVE_RESPONSE.
   */
  struct GNUNET_MessageHeader header;

  /**
   * A nonce to identify the session the keep alive is used for
   */
  uint32_t nonce GNUNET_PACKED;
};

/**
 * Message we send to the other peer to notify him that we intentionally
 * are disconnecting (to reduce timeouts).  This is just a friendly
 * notification, peers must not rely on always receiving disconnect
 * messages.
 */
struct SessionDisconnectMessage
{
  /**
   * Header of type #GNUNET_MESSAGE_TYPE_TRANSPORT_SESSION_DISCONNECT
   */
  struct GNUNET_MessageHeader header;

  /**
   * Always zero.
   */
  uint32_t reserved GNUNET_PACKED;

  /**
   * Purpose of the signature.  Extends over the timestamp.
   * Purpose should be #GNUNET_SIGNATURE_PURPOSE_TRANSPORT_DISCONNECT.
   */
  struct GNUNET_CRYPTO_EccSignaturePurpose purpose;

  /**
   * Absolute time at the sender.  Only the most recent connect
   * message implies which session is preferred by the sender.
   */
  struct GNUNET_TIME_AbsoluteNBO timestamp;

  /**
   * Public key of the sender.
   */
  struct GNUNET_CRYPTO_EddsaPublicKey public_key;

  /**
   * Signature of the peer that sends us the disconnect.  Only
   * valid if the timestamp is AFTER the timestamp from the
   * corresponding 'CONNECT' message.
   */
  struct GNUNET_CRYPTO_EddsaSignature signature;

};

GNUNET_NETWORK_STRUCT_END


/**
 * For each neighbour we keep a list of messages
 * that we still want to transmit to the neighbour.
 */
struct MessageQueue
{

  /**
   * This is a doubly linked list.
   */
  struct MessageQueue *next;

  /**
   * This is a doubly linked list.
   */
  struct MessageQueue *prev;

  /**
   * Function to call once we're done.
   */
  GST_NeighbourSendContinuation cont;

  /**
   * Closure for @e cont
   */
  void *cont_cls;

  /**
   * The message(s) we want to transmit, GNUNET_MessageHeader(s)
   * stuck together in memory.  Allocated at the end of this struct.
   */
  const char *message_buf;

  /**
   * Size of the message buf
   */
  size_t message_buf_size;

  /**
   * At what time should we fail?
   */
  struct GNUNET_TIME_Absolute timeout;

};




/**
 * A possible address we could use to communicate with a neighbour.
 */
struct NeighbourAddress
{

  /**
   * Active session for this address.
   */
  struct Session *session;

  /**
   * Network-level address information.
   */
  struct GNUNET_HELLO_Address *address;

  /**
   * Timestamp of the 'SESSION_CONNECT' message we sent to the other
   * peer for this address.  Use to check that the ACK is in response
   * to our most recent 'CONNECT'.
   */
  struct GNUNET_TIME_Absolute connect_timestamp;

  /**
   * Inbound bandwidth from ATS for this address.
   */
  struct GNUNET_BANDWIDTH_Value32NBO bandwidth_in;

  /**
   * Outbound bandwidth from ATS for this address.
   */
  struct GNUNET_BANDWIDTH_Value32NBO bandwidth_out;

  /**
   * Did we tell ATS that this is our 'active' address?
   */
  int ats_active;

  /**
   * The current nonce sent in the last keep alive messages
   */
  uint32_t keep_alive_nonce;
};

/**
 * Entry in neighbours.
 */
struct NeighbourMapEntry
{

  /**
   * Head of list of messages we would like to send to this peer;
   * must contain at most one message per client.
   */
  struct MessageQueue *messages_head;

  /**
   * Tail of list of messages we would like to send to this peer; must
   * contain at most one message per client.
   */
  struct MessageQueue *messages_tail;

  /**
   * Are we currently trying to send a message? If so, which one?
   */
  struct MessageQueue *is_active;

  /**
   * Primary address we currently use to communicate with the neighbour.
   */
  struct NeighbourAddress primary_address;

  /**
   * Alternative address currently under consideration for communicating
   * with the neighbour.
   */
  struct NeighbourAddress alternative_address;

  /**
   * Identity of this neighbour.
   */
  struct GNUNET_PeerIdentity id;

  /**
   * Main task that drives this peer (timeouts, keepalives, etc.).
   * Always runs the 'master_task'.
   */
  GNUNET_SCHEDULER_TaskIdentifier task;

  /**
   * Task to disconnect neighbour after we received a DISCONNECT message
   */
  GNUNET_SCHEDULER_TaskIdentifier delayed_disconnect_task;

  /**
   * At what time should we sent the next keep-alive message?
   */
  struct GNUNET_TIME_Absolute keep_alive_time;

  /**
   * At what time did we sent the last keep-alive message?  Used
   * to calculate round-trip time ("latency").
   */
  struct GNUNET_TIME_Absolute last_keep_alive_time;

  /**
   * Timestamp we should include in our next CONNECT_ACK message.
   * (only valid if 'send_connect_ack' is #GNUNET_YES).  Used to build
   * our CONNECT_ACK message.
   */
  struct GNUNET_TIME_Absolute connect_ack_timestamp;

  /**
   * ATS address suggest handle
   */
  struct GNUNET_ATS_SuggestHandle *suggest_handle;

  /**
   * Time where we should cut the connection (timeout) if we don't
   * make progress in the state machine (or get a KEEPALIVE_RESPONSE
   * if we are in S_CONNECTED).
   */
  struct GNUNET_TIME_Absolute timeout;

  /**
   * Latest calculated latency value
   */
  struct GNUNET_TIME_Relative latency;

  /**
   * Tracker for inbound bandwidth.
   */
  struct GNUNET_BANDWIDTH_Tracker in_tracker;

  /**
   * How often has the other peer (recently) violated the inbound
   * traffic limit?  Incremented by 10 per violation, decremented by 1
   * per non-violation (for each time interval).
   */
  unsigned int quota_violation_count;

  /**
   * The current state of the peer.
   */
  enum GNUNET_TRANSPORT_PeerState state;

  /**
   * Did we sent an KEEP_ALIVE message and are we expecting a response?
   */
  int expect_latency_response;

  /**
   * When a peer wants to connect we have to reply to the 1st CONNECT message
   * with a CONNECT_ACK message. But sometime we cannot send this message
   * immediately since we do not have an address and then we have to remember
   * to send this message as soon as we have an address.
   *
   * Flag to set if we still need to send a CONNECT_ACK message to the other peer
   * (once we have an address to use and the peer has been allowed by our
   * blacklist).  Initially set to #ACK_UNDEFINED. Set to #ACK_SEND_CONNECT_ACK
   * if we need to send a CONNECT_ACK.  Set to #ACK_SEND_SESSION_ACK if we did
   * send a CONNECT_ACK and should go to 'S_CONNECTED' upon receiving a
   * 'SESSION_ACK' (regardless of what our own state machine might say).
   */
  enum GST_ACK_State ack_state;

  /**
   * Tracking utilization of outbound bandwidth
   */
  uint32_t util_payload_bytes_sent;

  /**
   * Tracking utilization of inbound bandwidth
   */
  uint32_t util_payload_bytes_recv;

  /**
   * Tracking utilization of outbound bandwidth
   */
  uint32_t util_total_bytes_sent;

  /**
   * Tracking utilization of inbound bandwidth
   */
  uint32_t util_total_bytes_recv;

  /**
   * Date of last utilization transmission
   */
  struct GNUNET_TIME_Absolute last_util_transmission;
};


/**
 * Context for blacklist checks and the #try_connect_bl_check_cont()
 * function.  Stores information about ongoing blacklist checks.
 */
struct BlackListCheckContext
{

  /**
   * We keep blacklist checks in a DLL.
   */
  struct BlackListCheckContext *next;

  /**
   * We keep blacklist checks in a DLL.
   */
  struct BlackListCheckContext *prev;

  /**
   * Address that is being checked.
   */
  struct NeighbourAddress na;

  /**
   * Handle to the ongoing blacklist check.
   */
  struct GST_BlacklistCheck *bc;
};


/**
 * Hash map from peer identities to the respective 'struct NeighbourMapEntry'.
 */
static struct GNUNET_CONTAINER_MultiPeerMap *neighbours;

/**
 * We keep blacklist checks in a DLL so that we can find
 * the 'sessions' in their 'struct NeighbourAddress' if
 * a session goes down.
 */
static struct BlackListCheckContext *bc_head;

/**
 * We keep blacklist checks in a DLL.
 */
static struct BlackListCheckContext *bc_tail;

/**
 * List of pending blacklist checks: head
 */
static struct BlacklistCheckSwitchContext *pending_bc_head;

/**
 * List of pending blacklist checks: tail
 */
static struct BlacklistCheckSwitchContext *pending_bc_tail;

/**
 * Closure for #connect_notify_cb, #disconnect_notify_cb and #neighbour_change_cb
 */
static void *callback_cls;

/**
 * Function to call when we connected to a neighbour.
 */
static NotifyConnect connect_notify_cb;

/**
 * Function to call when we disconnected from a neighbour.
 */
static GNUNET_TRANSPORT_NotifyDisconnect disconnect_notify_cb;

/**
 * Function to call when a neighbour changed address, state or bandwidth.
 */
static GNUNET_TRANSPORT_NeighbourChangeCallback neighbour_change_cb;

/**
 * counter for connected neighbours
 */
static unsigned int neighbours_connected;

/**
 * Number of bytes we have currently queued for transmission.
 */
static unsigned long long bytes_in_send_queue;

/**
 * Task transmitting utilization data
 */
static GNUNET_SCHEDULER_TaskIdentifier util_transmission_tk;


static struct GNUNET_CONTAINER_MultiPeerMap *registered_quota_notifications;

static char *
print_ack_state (enum GST_ACK_State s)
{
  switch (s) {
    case ACK_UNDEFINED:
      return "UNDEFINED";
    case ACK_SEND_CONNECT_ACK:
      return "SEND_CONNECT_ACK";
    case ACK_SEND_SESSION_ACK:
      return "SEND_SESSION_ACK";
    default:
      GNUNET_break (0);
      return "N/A";
  }
}

/**
 * Lookup a neighbour entry in the neighbours hash map.
 *
 * @param pid identity of the peer to look up
 * @return the entry, NULL if there is no existing record
 */
static struct NeighbourMapEntry *
lookup_neighbour (const struct GNUNET_PeerIdentity *pid)
{
  if (NULL == neighbours)
    return NULL;
  return GNUNET_CONTAINER_multipeermap_get (neighbours, pid);
}


/**
 * Test if we're connected to the given peer.
 *
 * @param n neighbour entry of peer to test
 * @return #GNUNET_YES if we are connected, #GNUNET_NO if not
 */
static int
test_connected (struct NeighbourMapEntry *n)
{
  if (NULL == n)
    return GNUNET_NO;
  return GNUNET_TRANSPORT_is_connected (n->state);
}

/**
 * Send information about a new outbound quota to our clients.
 *
 * @param target affected peer
 * @param quota new quota
 */
static void
send_outbound_quota (const struct GNUNET_PeerIdentity *target,
                     struct GNUNET_BANDWIDTH_Value32NBO quota)
{
  struct QuotaSetMessage q_msg;

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Sending outbound quota of %u Bps for peer `%s' to all clients\n",
              ntohl (quota.value__), GNUNET_i2s (target));
  q_msg.header.size = htons (sizeof (struct QuotaSetMessage));
  q_msg.header.type = htons (GNUNET_MESSAGE_TYPE_TRANSPORT_SET_QUOTA);
  q_msg.quota = quota;
  q_msg.peer = (*target);
  GST_clients_broadcast (&q_msg.header, GNUNET_NO);
}


/**
 * We don't need a given neighbour address any more.
 * Release its resources and give appropriate notifications
 * to ATS and other subsystems.
 *
 * @param na address we are done with; @a na itself must NOT be 'free'd, only the contents!
 */
static void
free_address (struct NeighbourAddress *na)
{
  if (GNUNET_YES == na->ats_active)
  {
    GST_validation_set_address_use (na->address, na->session, GNUNET_NO);
    GNUNET_ATS_address_in_use (GST_ats, na->address, na->session, GNUNET_NO);
  }

  na->bandwidth_in = GNUNET_BANDWIDTH_value_init (0);
  na->bandwidth_out = GNUNET_BANDWIDTH_value_init (0);
  na->ats_active = GNUNET_NO;
  na->keep_alive_nonce = 0;
  if (NULL != na->address)
  {
    GNUNET_HELLO_address_free (na->address);
    na->address = NULL;
  }
  na->session = NULL;
}


/**
 * Set net state for this neighbour and notify monitoring
 *
 * @param n the respective neighbour
 * @param s the new state
 */
static void
set_state (struct NeighbourMapEntry *n, enum GNUNET_TRANSPORT_PeerState s)
{
  n->state = s;
  GNUNET_log (GNUNET_ERROR_TYPE_INFO, "Neighbour `%s' changed state to %s\n",
      GNUNET_i2s (&n->id),
      GNUNET_TRANSPORT_ps2s(s));
  neighbour_change_cb (callback_cls,
      &n->id,
      n->primary_address.address,
      n->state, n->timeout,
      n->primary_address.bandwidth_in,
      n->primary_address.bandwidth_out);
}


/**
 * Set net state and state timeout for this neighbour and notify monitoring
 *
 * @param n the respective neighbour
 * @param s the new state
 * @param timeout the new timeout
 */
static void
set_state_and_timeout (struct NeighbourMapEntry *n,
    enum GNUNET_TRANSPORT_PeerState s,
    struct GNUNET_TIME_Absolute timeout)
{
  n->state = s;
  n->timeout = timeout;
  GNUNET_log (GNUNET_ERROR_TYPE_INFO, "Neighbour `%s' changed state to %s with timeout %s\n",
      GNUNET_i2s (&n->id),
      GNUNET_TRANSPORT_ps2s(s),
      GNUNET_STRINGS_absolute_time_to_string (timeout));
  neighbour_change_cb (callback_cls,
      &n->id,
      n->primary_address.address,
      n->state, n->timeout,
      n->primary_address.bandwidth_in,
      n->primary_address.bandwidth_out);
}


/**
 * Set new state timeout for this neighbour and notify monitoring
 *
 * @param n the respective neighbour
 * @param timeout the new timeout
 */
static void
set_timeout (struct NeighbourMapEntry *n,
    struct GNUNET_TIME_Absolute timeout)
{
  n->timeout = timeout;
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Neighbour `%s' changed timeout %s\n",
      GNUNET_i2s (&n->id),
      GNUNET_STRINGS_absolute_time_to_string (timeout));
  neighbour_change_cb (callback_cls,
      &n->id,
      n->primary_address.address,
      n->state, n->timeout,
      n->primary_address.bandwidth_in,
      n->primary_address.bandwidth_out);
}


/**
 * Initialize the alternative address of a neighbour
 *
 * @param n the neighbour
 * @param address address of the other peer, NULL if other peer
 *                       connected to us
 * @param session session to use (or NULL, in which case an
 *        address must be setup)
 * @param bandwidth_in inbound quota to be used when connection is up
 * @param bandwidth_out outbound quota to be used when connection is up
 */
static void
set_alternative_address (struct NeighbourMapEntry *n,
             const struct GNUNET_HELLO_Address *address,
             struct Session *session,
             struct GNUNET_BANDWIDTH_Value32NBO bandwidth_in,
             struct GNUNET_BANDWIDTH_Value32NBO bandwidth_out)
{
  struct GNUNET_TRANSPORT_PluginFunctions *papi;
  if (NULL == (papi = GST_plugins_find (address->transport_name)))
  {
    GNUNET_break (0);
    return;
  }
  if (session == n->alternative_address.session)
  {
    n->alternative_address.bandwidth_in = bandwidth_in;
    n->alternative_address.bandwidth_out = bandwidth_out;
    return;
  }
  free_address (&n->alternative_address);
  if (NULL == session)
    session = papi->get_session (papi->cls, address);
  if (NULL == session)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Failed to obtain new session for peer `%s' and  address '%s'\n",
                GNUNET_i2s (&address->peer), GST_plugins_a2s (address));
    GNUNET_ATS_address_destroyed (GST_ats, address, NULL);
    return;
  }

  GNUNET_log (GNUNET_ERROR_TYPE_INFO, "Neighbour `%s' configured alternative address %s\n",
      GNUNET_i2s (&n->id),
      GST_plugins_a2s(address));

  n->alternative_address.address = GNUNET_HELLO_address_copy (address);
  n->alternative_address.bandwidth_in = bandwidth_in;
  n->alternative_address.bandwidth_out = bandwidth_out;
  n->alternative_address.session = session;
  n->alternative_address.ats_active = GNUNET_NO;
  n->alternative_address.keep_alive_nonce = 0;
}

static void
set_quotas ()
{

}


/**
 * Initialize the primary address of a neighbour
 *
 * @param n the neighbour
 * @param address address of the other peer, NULL if other peer
 *                       connected to us
 * @param session session to use (or NULL, in which case an
 *        address must be setup)
 * @param bandwidth_in inbound quota to be used when connection is up
 * @param bandwidth_out outbound quota to be used when connection is up
 * @param is_active #GNUNET_YES to mark this as the active address with ATS
 */
static void
set_primary_address (struct NeighbourMapEntry *n,
             const struct GNUNET_HELLO_Address *address,
             struct Session *session,
             struct GNUNET_BANDWIDTH_Value32NBO bandwidth_in,
             struct GNUNET_BANDWIDTH_Value32NBO bandwidth_out,
             int is_active)
{
  struct GNUNET_TRANSPORT_PluginFunctions *papi;

  if (NULL == (papi = GST_plugins_find (address->transport_name)))
  {
    GNUNET_break (0);
    return;
  }
  if (session == n->primary_address.session)
  {
    n->primary_address.bandwidth_in = bandwidth_in;
    n->primary_address.bandwidth_out = bandwidth_out;
    if (is_active != n->primary_address.ats_active)
    {
      n->primary_address.ats_active = is_active;
      GNUNET_ATS_address_in_use (GST_ats, n->primary_address.address, n->primary_address.session, is_active);
      GST_validation_set_address_use (n->primary_address.address, n->primary_address.session, is_active);
    }
    if (GNUNET_YES == is_active)
    {
      GST_neighbours_set_incoming_quota (&address->peer, bandwidth_in);
      send_outbound_quota (&address->peer, bandwidth_out);
    }
    return;
  }
  free_address (&n->primary_address);
  if (NULL == session)
    session = papi->get_session (papi->cls, address);
  if (NULL == session)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Failed to obtain new session for peer `%s' and  address '%s'\n",
                GNUNET_i2s (&address->peer), GST_plugins_a2s (address));
    GNUNET_ATS_address_destroyed (GST_ats, address, NULL);
    return;
  }

  n->primary_address.address = GNUNET_HELLO_address_copy (address);
  n->primary_address.bandwidth_in = bandwidth_in;
  n->primary_address.bandwidth_out = bandwidth_out;
  n->primary_address.session = session;
  n->primary_address.ats_active = is_active;
  n->primary_address.keep_alive_nonce = 0;
  if (GNUNET_YES == is_active)
  {
    /* Telling ATS about new session */
    GNUNET_ATS_address_in_use (GST_ats, n->primary_address.address, n->primary_address.session, GNUNET_YES);
    GST_validation_set_address_use (n->primary_address.address, n->primary_address.session, GNUNET_YES);
    GST_neighbours_set_incoming_quota (&address->peer, bandwidth_in);
    send_outbound_quota (&address->peer, bandwidth_out);
  }

  GNUNET_log (GNUNET_ERROR_TYPE_INFO, "Neighbour `%s' switched to address `%s'\n",
      GNUNET_i2s (&n->id),
      GST_plugins_a2s(address));

  neighbour_change_cb (callback_cls,
      &n->id,
      n->primary_address.address,
      n->state, n->timeout,
      n->primary_address.bandwidth_in,
      n->primary_address.bandwidth_out);
}

/**
 * Clear the primary address of a neighbour since this address is not
 * valid anymore and notify monitoring about it
 *
 * @param n the neighbour
 */
static void
unset_primary_address (struct NeighbourMapEntry *n)
{
  /* Unset primary address */
  free_address (&n->primary_address);

  /* Notify monitoring about it */
  neighbour_change_cb (callback_cls,
      &n->id,
      NULL,
      n->state, n->timeout,
      n->primary_address.bandwidth_in,
      n->primary_address.bandwidth_out);
}

/**
 * Clear the alternative address of a neighbour since this address is not
 * valid anymore
 *
 * @param n the neighbour
 */
static void
unset_alternative_address (struct NeighbourMapEntry *n)
{
  /* Unset primary address */
  free_address (&n->alternative_address);
}

/**
 * Free a neighbour map entry.
 *
 * @param n entry to free
 * @param keep_sessions #GNUNET_NO to tell plugin to terminate sessions,
 *                      #GNUNET_YES to keep all sessions
 */
static void
free_neighbour (struct NeighbourMapEntry *n,
                int keep_sessions)
{
  struct MessageQueue *mq;
  struct GNUNET_TRANSPORT_PluginFunctions *papi;
  struct GNUNET_HELLO_Address *backup_primary;

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Freeing neighbour state of peer `%s'\n",
              GNUNET_i2s (&n->id));
  n->is_active = NULL; /* always free'd by its own continuation! */

  /* fail messages currently in the queue */
  while (NULL != (mq = n->messages_head))
  {
    GNUNET_CONTAINER_DLL_remove (n->messages_head, n->messages_tail, mq);
    if (NULL != mq->cont)
      mq->cont (mq->cont_cls, GNUNET_SYSERR, mq->message_buf_size, 0);
    GNUNET_free (mq);
  }
  /* It is too late to send other peer disconnect notifications, but at
     least internally we need to get clean... */
  if (GNUNET_YES == test_connected (n))
  {
    GNUNET_STATISTICS_set (GST_stats,
                           gettext_noop ("# peers connected"),
                           --neighbours_connected,
                           GNUNET_NO);
    disconnect_notify_cb (callback_cls, &n->id);
  }

  /* Mark peer as disconnected */
  set_state (n, GNUNET_TRANSPORT_PS_DISCONNECT_FINISHED);

  if (NULL != n->primary_address.address)
    backup_primary = GNUNET_HELLO_address_copy (n->primary_address.address);
  else
    backup_primary = NULL;

  /* free addresses and mark as unused */
  unset_primary_address (n);
  free_address (&n->alternative_address);

  /* cut all transport-level connection for this peer */
  if ((GNUNET_NO == keep_sessions) &&
      (NULL != backup_primary) &&
      (NULL != (papi = GST_plugins_find (backup_primary->transport_name))))
    papi->disconnect_peer (papi->cls, &n->id);

  if (NULL != backup_primary)
    GNUNET_HELLO_address_free (backup_primary);
  GNUNET_assert (GNUNET_YES ==
                 GNUNET_CONTAINER_multipeermap_remove (neighbours,
                                                       &n->id, n));

  /* Cancel address requests for this peer */
  if (NULL != n->suggest_handle)
  {
    GNUNET_ATS_suggest_address_cancel (GST_ats, &n->id);
    n->suggest_handle = NULL;
  }

  /* Cancel the disconnect task */
  if (GNUNET_SCHEDULER_NO_TASK != n->delayed_disconnect_task)
  {
    GNUNET_SCHEDULER_cancel (n->delayed_disconnect_task);
    n->delayed_disconnect_task = GNUNET_SCHEDULER_NO_TASK;
  }

  /* Cancel the master task */
  if (GNUNET_SCHEDULER_NO_TASK != n->task)
  {
    GNUNET_SCHEDULER_cancel (n->task);
    n->task = GNUNET_SCHEDULER_NO_TASK;
  }
  /* free rest of memory */
  GNUNET_free (n);
}


/**
 * Transmit a message using the current session of the given
 * neighbour.
 *
 * @param n entry for the recipient
 * @param msgbuf buffer to transmit
 * @param msgbuf_size number of bytes in @a msgbuf buffer
 * @param priority transmission priority
 * @param timeout transmission timeout
 * @param use_keepalive_timeout #GNUNET_YES to use plugin-specific keep-alive
 *        timeout (@a timeout is ignored in that case), #GNUNET_NO otherwise
 * @param cont continuation to call when finished (can be NULL)
 * @param cont_cls closure for @a cont
 * @return timeout (copy of @a timeout or a calculated one if
 *         @a use_keepalive_timeout is #GNUNET_YES.
 */
static struct GNUNET_TIME_Relative
send_with_session (struct NeighbourMapEntry *n,
                   const char *msgbuf, size_t msgbuf_size,
                   uint32_t priority,
                   struct GNUNET_TIME_Relative timeout,
                   unsigned int use_keepalive_timeout,
                   GNUNET_TRANSPORT_TransmitContinuation cont,
                   void *cont_cls)
{
  struct GNUNET_TRANSPORT_PluginFunctions *papi;
  struct GNUNET_TIME_Relative result = GNUNET_TIME_UNIT_FOREVER_REL;

  GNUNET_assert (n->primary_address.session != NULL);
  if ( ((NULL == (papi = GST_plugins_find (n->primary_address.address->transport_name)) ||
         (-1 == papi->send (papi->cls,
                            n->primary_address.session,
                            msgbuf, msgbuf_size,
                            priority,
                            (result = (GNUNET_NO == use_keepalive_timeout) ? timeout :
                                GNUNET_TIME_relative_divide (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT,
                                                             papi->query_keepalive_factor (papi->cls))),
                            cont, cont_cls)))) &&
       (NULL != cont))
    cont (cont_cls, &n->id, GNUNET_SYSERR, msgbuf_size, 0);
  GST_neighbours_notify_data_sent (&n->id,
      n->primary_address.address, n->primary_address.session, msgbuf_size);
  GNUNET_break (NULL != papi);
  return result;
}


/**
 * Master task run for every neighbour.  Performs all of the time-related
 * activities (keep alive, send next message, disconnect if idle, finish
 * clean up after disconnect).
 *
 * @param cls the `struct NeighbourMapEntry` for which we are running
 * @param tc scheduler context (unused)
 */
static void
master_task (void *cls,
             const struct GNUNET_SCHEDULER_TaskContext *tc);


/**
 * Function called when the 'DISCONNECT' message has been sent by the
 * plugin.  Frees the neighbour --- if the entry still exists.
 *
 * @param cls NULL
 * @param target identity of the neighbour that was disconnected
 * @param result #GNUNET_OK if the disconnect got out successfully
 * @param payload bytes payload
 * @param physical bytes physical
 */
static void
send_disconnect_cont (void *cls, const struct GNUNET_PeerIdentity *target,
                      int result, size_t payload, size_t physical)
{
  struct NeighbourMapEntry *n;

  n = lookup_neighbour (target);
  if (NULL == n)
    return; /* already gone */
  if (GNUNET_TRANSPORT_PS_DISCONNECT != n->state)
    return; /* have created a fresh entry since */
  if (GNUNET_SCHEDULER_NO_TASK != n->task)
    GNUNET_SCHEDULER_cancel (n->task);
  n->task = GNUNET_SCHEDULER_add_now (&master_task, n);
}


/**
 * Transmit a DISCONNECT message to the other peer.
 *
 * @param n neighbour to send DISCONNECT message.
 */
static void
send_disconnect (struct NeighbourMapEntry *n)
{
  struct SessionDisconnectMessage disconnect_msg;

  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Sending DISCONNECT message to peer `%4s'\n",
              GNUNET_i2s (&n->id));
  disconnect_msg.header.size = htons (sizeof (struct SessionDisconnectMessage));
  disconnect_msg.header.type =
      htons (GNUNET_MESSAGE_TYPE_TRANSPORT_SESSION_DISCONNECT);
  disconnect_msg.reserved = htonl (0);
  disconnect_msg.purpose.size =
      htonl (sizeof (struct GNUNET_CRYPTO_EccSignaturePurpose) +
             sizeof (struct GNUNET_CRYPTO_EddsaPublicKey) +
             sizeof (struct GNUNET_TIME_AbsoluteNBO));
  disconnect_msg.purpose.purpose =
      htonl (GNUNET_MESSAGE_TYPE_TRANSPORT_SESSION_DISCONNECT);
  disconnect_msg.timestamp =
      GNUNET_TIME_absolute_hton (GNUNET_TIME_absolute_get ());
  disconnect_msg.public_key = GST_my_identity.public_key;
  GNUNET_assert (GNUNET_OK ==
                 GNUNET_CRYPTO_eddsa_sign (GST_my_private_key,
                                         &disconnect_msg.purpose,
                                         &disconnect_msg.signature));

  (void) send_with_session (n, (const char *) &disconnect_msg,
      sizeof (disconnect_msg), UINT32_MAX, GNUNET_TIME_UNIT_FOREVER_REL,
      GNUNET_NO, &send_disconnect_cont, NULL );
  GNUNET_STATISTICS_update (GST_stats,
                            gettext_noop
                            ("# DISCONNECT messages sent"), 1,
                            GNUNET_NO);
}


/**
 * Disconnect from the given neighbour, clean up the record.
 *
 * @param n neighbour to disconnect from
 */
static void
disconnect_neighbour (struct NeighbourMapEntry *n)
{
  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Disconnecting from peer %s in state %s\n",
              GNUNET_i2s (&n->id),
              GNUNET_TRANSPORT_ps2s (n->state));
  /* depending on state, notify neighbour and/or upper layers of this peer
     about disconnect */
  switch (n->state)
  {
  case GNUNET_TRANSPORT_PS_NOT_CONNECTED:
  case GNUNET_TRANSPORT_PS_INIT_ATS:
    /* other peer is completely unaware of us, no need to send DISCONNECT */
    free_neighbour (n, GNUNET_NO);
    return;
  case GNUNET_TRANSPORT_PS_CONNECT_SENT:
    send_disconnect (n);
    set_state (n, GNUNET_TRANSPORT_PS_DISCONNECT);
    break;
  case GNUNET_TRANSPORT_PS_CONNECT_RECV_ATS:
    /* we never ACK'ed the other peer's request, no need to send DISCONNECT */
    free_neighbour (n, GNUNET_NO);
    return;
  case GNUNET_TRANSPORT_PS_CONNECT_RECV_ACK:
    /* we DID ACK the other peer's request, must send DISCONNECT */
    send_disconnect (n);
    set_state (n, GNUNET_TRANSPORT_PS_DISCONNECT);
    break;
  case GNUNET_TRANSPORT_PS_CONNECTED_SWITCHING_CONNECT_SENT:
  case GNUNET_TRANSPORT_PS_CONNECTED:
  case GNUNET_TRANSPORT_PS_RECONNECT_SENT:
    /* we are currently connected, need to send disconnect and do
       internal notifications and update statistics */
    send_disconnect (n);
    GNUNET_STATISTICS_set (GST_stats,
                           gettext_noop ("# peers connected"),
                           --neighbours_connected,
                           GNUNET_NO);
    disconnect_notify_cb (callback_cls, &n->id);
    set_state (n, GNUNET_TRANSPORT_PS_DISCONNECT);
    break;
  case GNUNET_TRANSPORT_PS_RECONNECT_ATS:
    /* Disconnecting while waiting for an ATS address to reconnect,
     * cannot send DISCONNECT */
    free_neighbour (n, GNUNET_NO);
    return;
  case GNUNET_TRANSPORT_PS_DISCONNECT:
    /* already disconnected, ignore */
    break;
  case GNUNET_TRANSPORT_PS_DISCONNECT_FINISHED:
    /* already cleaned up, how did we get here!? */
    GNUNET_assert (0);
    break;
  default:
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Unhandled state `%s'\n",
                GNUNET_TRANSPORT_ps2s (n->state));
    GNUNET_break (0);
    break;
  }
  /* schedule timeout to clean up */
  if (GNUNET_SCHEDULER_NO_TASK != n->task)
    GNUNET_SCHEDULER_cancel (n->task);
  n->task = GNUNET_SCHEDULER_add_delayed (DISCONNECT_SENT_TIMEOUT,
                                          &master_task, n);
}


/**
 * We're done with our transmission attempt, continue processing.
 *
 * @param cls the `struct MessageQueue` of the message
 * @param receiver intended receiver
 * @param success whether it worked or not
 * @param size_payload bytes payload sent
 * @param physical bytes sent on wire
 */
static void
transmit_send_continuation (void *cls,
                            const struct GNUNET_PeerIdentity *receiver,
                            int success, size_t size_payload, size_t physical)
{
  struct MessageQueue *mq = cls;
  struct NeighbourMapEntry *n;

  if (NULL == (n = lookup_neighbour (receiver)))
  {
    GNUNET_free (mq);
    return; /* disconnect or other error while transmitting, can happen */
  }
  if (n->is_active == mq)
  {
    /* this is still "our" neighbour, remove us from its queue
       and allow it to send the next message now */
    n->is_active = NULL;
    if (GNUNET_SCHEDULER_NO_TASK != n->task)
      GNUNET_SCHEDULER_cancel (n->task);
    n->task = GNUNET_SCHEDULER_add_now (&master_task, n);
  }
  if (bytes_in_send_queue < mq->message_buf_size)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Bytes_in_send_queue `%u', Message_size %u, result: %s, payload %u, on wire %u\n",
                bytes_in_send_queue, mq->message_buf_size,
                (GNUNET_OK == success) ? "OK" : "FAIL",
                size_payload, physical);
    GNUNET_break (0);
  }


  GNUNET_break (size_payload == mq->message_buf_size);
  bytes_in_send_queue -= mq->message_buf_size;
  GNUNET_STATISTICS_set (GST_stats,
                        gettext_noop
                         ("# bytes in message queue for other peers"),
                         bytes_in_send_queue, GNUNET_NO);
  if (GNUNET_OK == success)
    GNUNET_STATISTICS_update (GST_stats,
                              gettext_noop
                              ("# messages transmitted to other peers"),
                              1, GNUNET_NO);
  else
    GNUNET_STATISTICS_update (GST_stats,
                              gettext_noop
                              ("# transmission failures for messages to other peers"),
                              1, GNUNET_NO);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Sending message to `%s' of type %u with %u bytes was a %s\n",
              GNUNET_i2s (receiver),
              ntohs (((struct GNUNET_MessageHeader *) mq->message_buf)->type),
              mq->message_buf_size,
              (success == GNUNET_OK) ? "success" : "FAILURE");
  if (NULL != mq->cont)
    mq->cont (mq->cont_cls, success, size_payload, physical);
  GNUNET_free (mq);
}


/**
 * Check the message list for the given neighbour and if we can
 * send a message, do so.  This function should only be called
 * if the connection is at least generally ready for transmission.
 * While we will only send one message at a time, no bandwidth
 * quota management is performed here.  If a message was given to
 * the plugin, the continuation will automatically re-schedule
 * the 'master' task once the next message might be transmitted.
 *
 * @param n target peer for which to transmit
 */
static void
try_transmission_to_peer (struct NeighbourMapEntry *n)
{
  struct MessageQueue *mq;
  struct GNUNET_TIME_Relative timeout;

  if (NULL == n->primary_address.address)
  {
    /* no address, why are we here? */
    GNUNET_break (0);
    return;
  }
  if ((0 == n->primary_address.address->address_length) &&
      (NULL == n->primary_address.session))
  {
    /* no address, why are we here? */
    GNUNET_break (0);
    return;
  }
  if (NULL != n->is_active)
  {
    /* transmission already pending */
    return;
  }

  /* timeout messages from the queue that are past their due date */
  while (NULL != (mq = n->messages_head))
  {
    timeout = GNUNET_TIME_absolute_get_remaining (mq->timeout);
    if (timeout.rel_value_us > 0)
      break;
    GNUNET_STATISTICS_update (GST_stats,
                              gettext_noop
                              ("# messages timed out while in transport queue"),
                              1, GNUNET_NO);
    GNUNET_CONTAINER_DLL_remove (n->messages_head, n->messages_tail, mq);
    n->is_active = mq;
    transmit_send_continuation (mq, &n->id,
                                GNUNET_SYSERR,
                                mq->message_buf_size, 0);     /* timeout */
  }
  if (NULL == mq)
    return;                     /* no more messages */
  GNUNET_CONTAINER_DLL_remove (n->messages_head, n->messages_tail, mq);
  n->is_active = mq;

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
      "Giving message with %u bytes to plugin session %p\n",
      mq->message_buf_size, n->primary_address.session);

  (void) send_with_session (n,
                            mq->message_buf, mq->message_buf_size,
                            0 /* priority */, timeout, GNUNET_NO,
                            &transmit_send_continuation, mq);
}


/**
 * Send keepalive message to the neighbour.  Must only be called
 * if we are on 'connected' state or while trying to switch addresses.
 * Will internally determine if a keepalive is truly needed (so can
 * always be called).
 *
 * @param n neighbour that went idle and needs a keepalive
 */
static void
send_keepalive (struct NeighbourMapEntry *n)
{
  struct SessionKeepAliveMessage m;
  struct GNUNET_TIME_Relative timeout;
  uint32_t nonce;

  GNUNET_assert ((GNUNET_TRANSPORT_PS_CONNECTED == n->state) ||
                 (GNUNET_TRANSPORT_PS_CONNECTED_SWITCHING_CONNECT_SENT));
  if (GNUNET_TIME_absolute_get_remaining (n->keep_alive_time).rel_value_us > 0)
    return; /* no keepalive needed at this time */

  nonce = 0; /* 0 indicates 'not set' */
  while (0 == nonce)
    nonce = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX);

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
      "Sending keep alive to peer `%s' with nonce %u\n",
      GNUNET_i2s (&n->id), nonce);

  m.header.size = htons (sizeof (struct SessionKeepAliveMessage));
  m.header.type = htons (GNUNET_MESSAGE_TYPE_TRANSPORT_SESSION_KEEPALIVE);
  m.nonce = htonl (nonce);

  timeout = send_with_session (n,
                               (const void *) &m, sizeof (m),
                               UINT32_MAX /* priority */,
                               GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES,
                               NULL, NULL);
  GNUNET_STATISTICS_update (GST_stats, gettext_noop ("# keepalives sent"), 1,
                            GNUNET_NO);
  n->primary_address.keep_alive_nonce = nonce;
  n->expect_latency_response = GNUNET_YES;
  n->last_keep_alive_time = GNUNET_TIME_absolute_get ();
  n->keep_alive_time = GNUNET_TIME_relative_to_absolute (timeout);

}


/**
 * Keep the connection to the given neighbour alive longer,
 * we received a KEEPALIVE (or equivalent); send a response.
 *
 * @param neighbour neighbour to keep alive (by sending keep alive response)
 * @param m the keep alive message containing the nonce to respond to
 */
void
GST_neighbours_keepalive (const struct GNUNET_PeerIdentity *neighbour,
    const struct GNUNET_MessageHeader *m)
{
  struct NeighbourMapEntry *n;
  const struct SessionKeepAliveMessage *msg_in;
  struct SessionKeepAliveMessage msg;

  if (sizeof (struct SessionKeepAliveMessage) != ntohs (m->size))
    return;

  msg_in = (struct SessionKeepAliveMessage *) m;
  if (NULL == (n = lookup_neighbour (neighbour)))
  {
    GNUNET_STATISTICS_update (GST_stats,
                              gettext_noop
                              ("# KEEPALIVE messages discarded (peer unknown)"),
                              1, GNUNET_NO);
    return;
  }
  if (NULL == n->primary_address.session)
  {
    GNUNET_STATISTICS_update (GST_stats,
                              gettext_noop
                              ("# KEEPALIVE messages discarded (no session)"),
                              1, GNUNET_NO);
    return;
  }

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
      "Received keep alive request from peer `%s' with nonce %u\n",
      GNUNET_i2s (&n->id), ntohl (msg_in->nonce));

  /* send reply to allow neighbour to measure latency */
  msg.header.size = htons (sizeof (struct SessionKeepAliveMessage));
  msg.header.type = htons (GNUNET_MESSAGE_TYPE_TRANSPORT_SESSION_KEEPALIVE_RESPONSE);
  msg.nonce = msg_in->nonce;
  (void) send_with_session(n,
                           (const void *) &msg, sizeof (struct SessionKeepAliveMessage),
                           UINT32_MAX /* priority */,
                           GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES,
                           NULL, NULL);
}


/**
 * We received a KEEP_ALIVE_RESPONSE message and use this to calculate
 * latency to this peer.  Pass the updated information (existing ats
 * plus calculated latency) to ATS.
 *
 * @param neighbour neighbour to keep alive
 * @param m the message containing the keep alive response
 */
void
GST_neighbours_keepalive_response (const struct GNUNET_PeerIdentity *neighbour,
    const struct GNUNET_MessageHeader *m)
{
  struct NeighbourMapEntry *n;
  const struct SessionKeepAliveMessage *msg;
  struct GNUNET_TRANSPORT_PluginFunctions *papi;
  uint32_t latency;
  struct GNUNET_ATS_Information ats;

  if (sizeof (struct SessionKeepAliveMessage) != ntohs (m->size))
    return;

  msg = (const struct SessionKeepAliveMessage *) m;
  if (NULL == (n = lookup_neighbour (neighbour)))
  {
    GNUNET_STATISTICS_update (GST_stats,
                              gettext_noop
                              ("# KEEPALIVE_RESPONSE messages discarded (not connected)"),
                              1, GNUNET_NO);
    return;
  }
  if ( (GNUNET_TRANSPORT_PS_CONNECTED != n->state) ||
       (GNUNET_YES != n->expect_latency_response) )
  {
    GNUNET_STATISTICS_update (GST_stats,
                              gettext_noop
                              ("# KEEPALIVE_RESPONSE messages discarded (not expected)"),
                              1, GNUNET_NO);
    return;
  }
  if (NULL == n->primary_address.address)
  {
    GNUNET_STATISTICS_update (GST_stats,
                              gettext_noop
                              ("# KEEPALIVE_RESPONSE messages discarded (address changed)"),
                              1, GNUNET_NO);
    return;
  }
  if (n->primary_address.keep_alive_nonce != ntohl (msg->nonce))
  {
    GNUNET_STATISTICS_update (GST_stats,
                              gettext_noop
                              ("# KEEPALIVE_RESPONSE messages discarded (wrong nonce)"),
                              1, GNUNET_NO);
    return;
  }
  else
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
        "Received keep alive response from peer `%s' for session %p\n",
        GNUNET_i2s (&n->id), n->primary_address.session);

  }

  /* Update session timeout here */
  if (NULL != (papi = GST_plugins_find (n->primary_address.address->transport_name)))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
        "Updating session for peer `%s' for session %p\n",
        GNUNET_i2s (&n->id), n->primary_address.session);
    papi->update_session_timeout (papi->cls, &n->id, n->primary_address.session);
  }
  else
  {
    GNUNET_break (0);
  }

  n->primary_address.keep_alive_nonce = 0;
  n->expect_latency_response = GNUNET_NO;
  n->latency = GNUNET_TIME_absolute_get_duration (n->last_keep_alive_time);
  set_timeout (n, GNUNET_TIME_relative_to_absolute (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT));

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Latency for peer `%s' is %s\n",
              GNUNET_i2s (&n->id),
              GNUNET_STRINGS_relative_time_to_string (n->latency,
                                                      GNUNET_YES));
  /* append latency */
  ats.type = htonl (GNUNET_ATS_QUALITY_NET_DELAY);
  if (n->latency.rel_value_us > UINT32_MAX)
    latency = UINT32_MAX;
  else
    latency = n->latency.rel_value_us;
  ats.value = htonl (latency);
  GST_ats_update_metrics (&n->id, n->primary_address.address,
      n->primary_address.session, &ats, 1);
}


/**
 * We have received a message from the given sender.  How long should
 * we delay before receiving more?  (Also used to keep the peer marked
 * as live).
 *
 * @param sender sender of the message
 * @param size size of the message
 * @param do_forward set to #GNUNET_YES if the message should be forwarded to clients
 *                   #GNUNET_NO if the neighbour is not connected or violates the quota,
 *                   #GNUNET_SYSERR if the connection is not fully up yet
 * @return how long to wait before reading more from this sender
 */
struct GNUNET_TIME_Relative
GST_neighbours_calculate_receive_delay (const struct GNUNET_PeerIdentity
                                        *sender, ssize_t size, int *do_forward)
{
  struct NeighbourMapEntry *n;
  struct GNUNET_TIME_Relative ret;

  if (NULL == neighbours)
  {
    *do_forward = GNUNET_NO;
    return GNUNET_TIME_UNIT_FOREVER_REL; /* This can happen during shutdown */
  }
  if (NULL == (n = lookup_neighbour (sender)))
  {
    GST_neighbours_try_connect (sender);
    if (NULL == (n = lookup_neighbour (sender)))
    {
      GNUNET_STATISTICS_update (GST_stats,
                                gettext_noop
                                ("# messages discarded due to lack of neighbour record"),
                                1, GNUNET_NO);
      *do_forward = GNUNET_NO;
      return GNUNET_TIME_UNIT_ZERO;
    }
  }
  if (! test_connected (n))
  {
    *do_forward = GNUNET_SYSERR;
    return GNUNET_TIME_UNIT_ZERO;
  }
  if (GNUNET_YES == GNUNET_BANDWIDTH_tracker_consume (&n->in_tracker, size))
  {
    n->quota_violation_count++;
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Bandwidth quota (%u b/s) violation detected (total of %u).\n",
                n->in_tracker.available_bytes_per_s__,
                n->quota_violation_count);
    /* Discount 32k per violation */
    GNUNET_BANDWIDTH_tracker_consume (&n->in_tracker, -32 * 1024);
  }
  else
  {
    if (n->quota_violation_count > 0)
    {
      /* try to add 32k back */
      GNUNET_BANDWIDTH_tracker_consume (&n->in_tracker, 32 * 1024);
      n->quota_violation_count--;
    }
  }
  if (n->quota_violation_count > QUOTA_VIOLATION_DROP_THRESHOLD)
  {
    GNUNET_STATISTICS_update (GST_stats,
                              gettext_noop
                              ("# bandwidth quota violations by other peers"),
                              1, GNUNET_NO);
    *do_forward = GNUNET_NO;
    return GNUNET_CONSTANTS_QUOTA_VIOLATION_TIMEOUT;
  }
  *do_forward = GNUNET_YES;
  ret = GNUNET_BANDWIDTH_tracker_get_delay (&n->in_tracker, 32 * 1024);
  if (ret.rel_value_us > 0)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Throttling read (%llu bytes excess at %u b/s), waiting %s before reading more.\n",
                (unsigned long long) n->in_tracker.
                consumption_since_last_update__,
                (unsigned int) n->in_tracker.available_bytes_per_s__,
                GNUNET_STRINGS_relative_time_to_string (ret, GNUNET_YES));
    GNUNET_STATISTICS_update (GST_stats,
                              gettext_noop ("# ms throttling suggested"),
                              (int64_t) ret.rel_value_us / 1000LL,
                              GNUNET_NO);
  }
  return ret;
}


/**
 * Transmit a message to the given target using the active connection.
 *
 * @param target destination
 * @param msg message to send
 * @param msg_size number of bytes in msg
 * @param timeout when to fail with timeout
 * @param cont function to call when done
 * @param cont_cls closure for 'cont'
 */
void
GST_neighbours_send (const struct GNUNET_PeerIdentity *target, const void *msg,
                     size_t msg_size, struct GNUNET_TIME_Relative timeout,
                     GST_NeighbourSendContinuation cont, void *cont_cls)
{
  struct NeighbourMapEntry *n;
  struct MessageQueue *mq;

  /* All ove these cases should never happen; they are all API violations.
     But we check anyway, just to be sure. */
  if (NULL == (n = lookup_neighbour (target)))
  {
    GNUNET_break (0);
    if (NULL != cont)
      cont (cont_cls, GNUNET_SYSERR, msg_size, 0);
    return;
  }
  if (GNUNET_YES != test_connected (n))
  {
    GNUNET_break (0);
    if (NULL != cont)
      cont (cont_cls, GNUNET_SYSERR, msg_size, 0);
    return;
  }
  bytes_in_send_queue += msg_size;
  GNUNET_STATISTICS_set (GST_stats,
                         gettext_noop
                         ("# bytes in message queue for other peers"),
                         bytes_in_send_queue, GNUNET_NO);
  mq = GNUNET_malloc (sizeof (struct MessageQueue) + msg_size);
  mq->cont = cont;
  mq->cont_cls = cont_cls;
  memcpy (&mq[1], msg, msg_size);
  mq->message_buf = (const char *) &mq[1];
  mq->message_buf_size = msg_size;
  mq->timeout = GNUNET_TIME_relative_to_absolute (timeout);

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Enqueueing %u bytes to send to peer %s\n",
      msg_size, GNUNET_i2s (target));

  GNUNET_CONTAINER_DLL_insert_tail (n->messages_head, n->messages_tail, mq);
  if (GNUNET_SCHEDULER_NO_TASK != n->task)
    GNUNET_SCHEDULER_cancel (n->task);
  n->task = GNUNET_SCHEDULER_add_now (&master_task, n);
}

static void
send_session_connect_cont (void *cls,
                      const struct GNUNET_PeerIdentity *target,
                      int result,
                      size_t size_payload,
                      size_t size_on_wire)
{
  struct NeighbourMapEntry *n;

  n = lookup_neighbour (target);
  if (NULL == n)
  {
    /* CONNECT continuation was called after neighbor was freed,
     * for example due to a time out for the state or the session
     * used was already terminated: nothing to do here... */
    return;
  }

  if ( (GNUNET_TRANSPORT_PS_CONNECT_SENT != n->state) &&
       (GNUNET_TRANSPORT_PS_RECONNECT_SENT != n->state) &&
       (GNUNET_TRANSPORT_PS_CONNECTED_SWITCHING_CONNECT_SENT != n->state))
  {
    /* CONNECT continuation was called after neighbor changed state,
     * for example due to a time out for the state or the session
     * used was already terminated: nothing to do here... */
    return;
  }
  if (GNUNET_OK == result)
    return;

  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
            _("Failed to send CONNECT message to peer `%s' using address `%s' session %p\n"),
            GNUNET_i2s (target),
            GST_plugins_a2s (n->primary_address.address),
            n->primary_address.session);

  switch (n->state) {
  case GNUNET_TRANSPORT_PS_CONNECT_SENT:
    /* Remove address and request and additional one */
    GNUNET_ATS_address_destroyed (GST_ats, n->primary_address.address,
        n->primary_address.session);
    GNUNET_ATS_address_destroyed (GST_ats, n->primary_address.address, NULL );
    unset_primary_address (n);
    set_state_and_timeout (n, GNUNET_TRANSPORT_PS_INIT_ATS,
        GNUNET_TIME_relative_to_absolute (FAST_RECONNECT_TIMEOUT));
    break;
  case GNUNET_TRANSPORT_PS_RECONNECT_SENT:
    /* Remove address and request and additional one */
    GNUNET_ATS_address_destroyed (GST_ats, n->primary_address.address,
        n->primary_address.session);
    GNUNET_ATS_address_destroyed (GST_ats, n->primary_address.address, NULL );
    unset_primary_address (n);
    set_state_and_timeout (n, GNUNET_TRANSPORT_PS_RECONNECT_ATS,
        GNUNET_TIME_relative_to_absolute (ATS_RESPONSE_TIMEOUT));
    break;
  case GNUNET_TRANSPORT_PS_CONNECTED_SWITCHING_CONNECT_SENT:
    /* Remove address and request and go back to primary address */
    GNUNET_STATISTICS_update (GST_stats, gettext_noop
        ("# Failed attempts to switch addresses (failed to send CONNECT CONT)"), 1, GNUNET_NO);
    GNUNET_ATS_address_destroyed (GST_ats, n->alternative_address.address,
        n->alternative_address.session);
    GNUNET_ATS_address_destroyed (GST_ats, n->alternative_address.address,
        NULL );
    unset_alternative_address (n);
    set_state_and_timeout (n, GNUNET_TRANSPORT_PS_CONNECTED,
        GNUNET_TIME_relative_to_absolute (ATS_RESPONSE_TIMEOUT));
    break;
  default:
    disconnect_neighbour (n);
    break;
  }
}

/**
 * Send a SESSION_CONNECT message via the given address.
 *
 * @param na address to use
 */
static void
send_session_connect (struct NeighbourAddress *na)
{
  struct GNUNET_TRANSPORT_PluginFunctions *papi;
  struct SessionConnectMessage connect_msg;
  struct NeighbourMapEntry *n;

  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Sending SESSION_CONNECT message to peer `%s'\n",
              GNUNET_i2s (&na->address->peer));

  if (NULL == (papi = GST_plugins_find (na->address->transport_name)))
  {
    GNUNET_break (0);
    return;
  }
  if (NULL == na->session)
    na->session = papi->get_session (papi->cls, na->address);
  if (NULL == na->session)
  {
    GNUNET_break (0);
    return;
  }
  GNUNET_STATISTICS_update (GST_stats,
                            gettext_noop
                            ("# SESSION_CONNECT messages sent"),
                            1, GNUNET_NO);
  na->connect_timestamp = GNUNET_TIME_absolute_get ();
  connect_msg.header.size = htons (sizeof (struct SessionConnectMessage));
  connect_msg.header.type = htons (GNUNET_MESSAGE_TYPE_TRANSPORT_SESSION_CONNECT);
  connect_msg.reserved = htonl (0);
  connect_msg.timestamp = GNUNET_TIME_absolute_hton (na->connect_timestamp);
  if (-1 ==
      papi->send (papi->cls,
                  na->session,
                  (const char *) &connect_msg, sizeof (struct SessionConnectMessage),
                  UINT_MAX,
                  SETUP_CONNECTION_TIMEOUT,
                  send_session_connect_cont, NULL))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                _("Failed to transmit CONNECT message via plugin to %s\n"),
                GST_plugins_a2s (na->address));

    n = lookup_neighbour (&na->address->peer);
    if (NULL == n)
    {
      GNUNET_break (0);
      return;
    }

    switch (n->state) {
      case GNUNET_TRANSPORT_PS_CONNECT_SENT:
        /* Remove address and request and additional one */
        unset_primary_address (n);
        set_state_and_timeout (n, GNUNET_TRANSPORT_PS_INIT_ATS,
          GNUNET_TIME_relative_to_absolute (FAST_RECONNECT_TIMEOUT));
        /* Hard failure to send the CONNECT message with this address:
           Destroy address and session */
        break;
      case GNUNET_TRANSPORT_PS_RECONNECT_SENT:
        /* Remove address and request and additional one */
        unset_primary_address (n);
        set_state_and_timeout (n, GNUNET_TRANSPORT_PS_RECONNECT_ATS,
          GNUNET_TIME_relative_to_absolute (ATS_RESPONSE_TIMEOUT));
        break;
      case GNUNET_TRANSPORT_PS_CONNECTED_SWITCHING_CONNECT_SENT:
        GNUNET_STATISTICS_update (GST_stats, gettext_noop
            ("# Failed attempts to switch addresses (failed to send CONNECT)"), 1, GNUNET_NO);
        /* Remove address and request and additional one */
        unset_alternative_address (n);
        set_state_and_timeout (n, GNUNET_TRANSPORT_PS_CONNECTED,
          GNUNET_TIME_relative_to_absolute (ATS_RESPONSE_TIMEOUT));
        break;
      default:
        disconnect_neighbour (n);
        break;
    }
    GNUNET_ATS_address_destroyed (GST_ats, na->address, na->session);
    GNUNET_ATS_address_destroyed (GST_ats, na->address, NULL);
  }
  GST_neighbours_notify_data_sent (&na->address->peer,
                                   na->address,
                                   na->session,
                                   sizeof (struct SessionConnectMessage));
}


static void
send_session_connect_ack_cont (void *cls,
                      const struct GNUNET_PeerIdentity *target,
                      int result,
                      size_t size_payload,
                      size_t size_on_wire)
{
  struct NeighbourMapEntry *n;

  n = lookup_neighbour (target);
  if (NULL == n)
  {
    /* CONNECT_ACK continuation was called after neighbor was freed,
     * for example due to a time out for the state or the session
     * used was already terminated: nothing to do here... */
    return;
  }

  if (GNUNET_TRANSPORT_PS_CONNECT_RECV_ACK != n->state)
  {
    /* CONNECT_ACK continuation was called after neighbor changed state,
     * for example due to a time out for the state or the session
     * used was already terminated: nothing to do here... */
    return;
  }
  if (GNUNET_OK == result)
    return;

  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
            _("Failed to send CONNECT_ACK message to peer `%s' using address `%s' session %p\n"),
            GNUNET_i2s (target),
            GST_plugins_a2s (n->primary_address.address),
            n->primary_address.session);

  /* Failed to send CONNECT_ACK message with this address */
  GNUNET_ATS_address_destroyed (GST_ats, n->primary_address.address,
      n->primary_address.session);
  GNUNET_ATS_address_destroyed (GST_ats, n->primary_address.address,
      NULL);

  /* Remove address and request and additional one */
  unset_primary_address (n);
  n->ack_state = ACK_SEND_CONNECT_ACK;
  set_state_and_timeout (n, GNUNET_TRANSPORT_PS_CONNECT_RECV_ATS,
      GNUNET_TIME_relative_to_absolute (ATS_RESPONSE_TIMEOUT));
  return;
}


/**
 * Send a CONNECT_ACK message via the given address.
 *
 * @param address address to use
 * @param session session to use
 * @param timestamp timestamp to use for the ACK message
 * @return GNUNET_SYSERR if sending immediately failed, GNUNET_OK otherwise
 */
static void
send_connect_ack_message (const struct GNUNET_HELLO_Address *address,
                                  struct Session *session,
                                  struct GNUNET_TIME_Absolute timestamp)
{
  struct GNUNET_TRANSPORT_PluginFunctions *papi;
  struct SessionConnectMessage connect_msg;
  struct NeighbourMapEntry *n;

  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Sending CONNECT_ACK to peer `%s'\n",
              GNUNET_i2s (&address->peer));

  if (NULL == (papi = GST_plugins_find (address->transport_name)))
  {
    GNUNET_break (0);
    return;
  }
  if (NULL == session)
    session = papi->get_session (papi->cls, address);
  if (NULL == session)
  {
    GNUNET_break (0);
    return;
  }
  GNUNET_STATISTICS_update (GST_stats,
                            gettext_noop
                            ("# CONNECT_ACK messages sent"),
                            1, GNUNET_NO);
  connect_msg.header.size = htons (sizeof (struct SessionConnectMessage));
  connect_msg.header.type = htons (GNUNET_MESSAGE_TYPE_TRANSPORT_SESSION_CONNECT_ACK);
  connect_msg.reserved = htonl (0);
  connect_msg.timestamp = GNUNET_TIME_absolute_hton (timestamp);

  if (GNUNET_SYSERR == papi->send (papi->cls,
                     session,
                     (const char *) &connect_msg, sizeof (struct SessionConnectMessage),
                     UINT_MAX,
                     GNUNET_TIME_UNIT_FOREVER_REL,
                     send_session_connect_ack_cont, NULL))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                _("Failed to transmit CONNECT_ACK message via plugin to %s\n"),
                GST_plugins_a2s (address));

    n = lookup_neighbour (&address->peer);
    if (NULL == n)
    {
      GNUNET_break (0);
      return;
    }
    /* Hard failure to send the CONNECT_ACK message with this address:
       Destroy session (and address)  */
    if (GNUNET_YES == GNUNET_HELLO_address_check_option(address,
        GNUNET_HELLO_ADDRESS_INFO_INBOUND))
    {
      GNUNET_ATS_address_destroyed (GST_ats, address, session);
      GNUNET_ATS_address_destroyed (GST_ats, address, NULL);
    }
    else
      GNUNET_ATS_address_destroyed (GST_ats, address, session);

    /* Remove address and request and additional one */
    unset_primary_address (n);
    n->ack_state = ACK_SEND_CONNECT_ACK;
    set_state_and_timeout (n, GNUNET_TRANSPORT_PS_CONNECT_RECV_ATS,
        GNUNET_TIME_relative_to_absolute (ATS_RESPONSE_TIMEOUT));
    return;
  }

}

struct QuotaNotificationRequest
{
  struct GNUNET_PeerIdentity peer;
  struct Session *session;
  char *plugin;
};

struct QNR_LookContext
{
  struct GNUNET_PeerIdentity peer;
  struct Session *session;
  const char *plugin;

  struct QuotaNotificationRequest *res;
};

static int
find_notification_request (void *cls, const struct GNUNET_PeerIdentity *key, void *value)
{
  struct QNR_LookContext *qnr_ctx = cls;
  struct QuotaNotificationRequest *qnr = value;

  if ((qnr->session == qnr_ctx->session) &&
      (0 == memcmp (&qnr->peer, &qnr_ctx->peer, sizeof (struct GNUNET_PeerIdentity))) &&
      (0 == strcmp(qnr_ctx->plugin, qnr->plugin)))
  {
    qnr_ctx->res = value;
    return GNUNET_NO;
  }
  return GNUNET_YES;
}

void
GST_neighbours_register_quota_notification(void *cls,
    const struct GNUNET_PeerIdentity *peer, const char *plugin,
    struct Session *session)
{
  struct QuotaNotificationRequest *qnr;
  struct QNR_LookContext qnr_ctx;

  if (NULL == registered_quota_notifications)
  {
    return; /* init or shutdown */
  }

  qnr_ctx.peer = (*peer);
  qnr_ctx.plugin = plugin;
  qnr_ctx.session = session;
  qnr_ctx.res = NULL;

  GNUNET_CONTAINER_multipeermap_get_multiple (registered_quota_notifications,
      peer, &find_notification_request, &qnr_ctx);
  if (NULL != qnr_ctx.res)
  {
    GNUNET_break(0);
    return;
  }

  qnr = GNUNET_new (struct QuotaNotificationRequest);
  qnr->peer =  (*peer);
  qnr->plugin = GNUNET_strdup (plugin);
  qnr->session = session;

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
      "Adding notification for peer `%s' plugin `%s' session %p \n",
      GNUNET_i2s (peer), plugin, session);

  GNUNET_CONTAINER_multipeermap_put (registered_quota_notifications, peer,
      qnr, GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE);
}


void
GST_neighbours_unregister_quota_notification(void *cls,
    const struct GNUNET_PeerIdentity *peer, const char *plugin, struct Session *session)
{
  struct QNR_LookContext qnr_ctx;

  if (NULL == registered_quota_notifications)
  {
    return; /* init or shutdown */
  }

  qnr_ctx.peer = (*peer);
  qnr_ctx.plugin = plugin;
  qnr_ctx.session = session;
  qnr_ctx.res = NULL;

  GNUNET_CONTAINER_multipeermap_iterate (registered_quota_notifications,
      &find_notification_request, &qnr_ctx);
  if (NULL == qnr_ctx.res)
  {
    GNUNET_break(0);
    return;
  }

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
      "Removing notification for peer `%s' plugin `%s' session %p \n",
      GNUNET_i2s (peer), plugin, session);

  GNUNET_CONTAINER_multipeermap_remove (registered_quota_notifications, peer,
      qnr_ctx.res);
  GNUNET_free (qnr_ctx.res->plugin);
  GNUNET_free (qnr_ctx.res);
}

static int
notification_cb(void *cls, const struct GNUNET_PeerIdentity *key, void *value)
{
  /* struct NeighbourMapEntry *n = cls; */
  struct QuotaNotificationRequest *qnr = value;
  struct GNUNET_TRANSPORT_PluginFunctions *papi;
  struct GNUNET_TIME_Relative delay;
  int do_forward;

  papi = GST_plugins_find(qnr->plugin);
  if (NULL == papi)
  {
    GNUNET_break (0);
    return GNUNET_OK;
  }

  delay = GST_neighbours_calculate_receive_delay (key, 0, &do_forward);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
      "New inbound delay for peer `%s' is %llu ms\n", GNUNET_i2s (key),
      delay.rel_value_us / 1000);

  if (NULL != papi->update_inbound_delay)
    papi->update_inbound_delay (papi->cls, key, qnr->session, delay);
  return GNUNET_OK;
}

static int
free_notification_cb(void *cls, const struct GNUNET_PeerIdentity *key,
    void *value)
{
  /* struct NeighbourMapEntry *n = cls; */
  struct QuotaNotificationRequest *qnr = value;

  GNUNET_break (GNUNET_OK == GNUNET_CONTAINER_multipeermap_remove (registered_quota_notifications, key,
      qnr));
  GNUNET_free(qnr->plugin);
  GNUNET_free(qnr);

  return GNUNET_OK;
}

static void
inbound_bw_tracker_update(void *cls)
{
  struct NeighbourMapEntry *n = cls;

  /* Quota was updated, tell plugins to update the time to receive next */
  GNUNET_CONTAINER_multipeermap_get_multiple (registered_quota_notifications,
      &n->id, &notification_cb, n);
}


/**
 * Create a fresh entry in the neighbour map for the given peer
 *
 * @param peer peer to create an entry for
 * @return new neighbour map entry
 */
static struct NeighbourMapEntry *
setup_neighbour (const struct GNUNET_PeerIdentity *peer)
{
  struct NeighbourMapEntry *n;

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Creating new neighbour entry for `%s'\n",
              GNUNET_i2s (peer));
  n = GNUNET_new (struct NeighbourMapEntry);
  n->id = *peer;
  n->ack_state = ACK_UNDEFINED;
  n->latency = GNUNET_TIME_UNIT_FOREVER_REL;
  n->last_util_transmission = GNUNET_TIME_absolute_get();
  n->util_payload_bytes_recv = 0;
  n->util_payload_bytes_sent = 0;
  n->util_total_bytes_recv = 0;
  n->util_total_bytes_sent = 0;
  GNUNET_BANDWIDTH_tracker_init (&n->in_tracker, &inbound_bw_tracker_update, n,
                                 GNUNET_CONSTANTS_DEFAULT_BW_IN_OUT,
                                 MAX_BANDWIDTH_CARRY_S);
  n->task = GNUNET_SCHEDULER_add_now (&master_task, n);
  set_state_and_timeout (n, GNUNET_TRANSPORT_PS_NOT_CONNECTED, GNUNET_TIME_UNIT_FOREVER_ABS);
  GNUNET_assert (GNUNET_OK ==
                 GNUNET_CONTAINER_multipeermap_put (neighbours,
                                                    &n->id, n,
                                                    GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
  return n;
}

/* We received a address suggestion after requesting an address in
 * try_connect or after receiving a connect, switch to address
 */
static void
address_suggest_cont (void *cls,
    const struct GNUNET_PeerIdentity *peer,
    const struct GNUNET_HELLO_Address *address, struct Session *session,
    struct GNUNET_BANDWIDTH_Value32NBO bandwidth_out,
    struct GNUNET_BANDWIDTH_Value32NBO bandwidth_in,
    const struct GNUNET_ATS_Information *ats, uint32_t ats_count)
{
  GST_neighbours_switch_to_address(peer, address, session, ats, ats_count,
      bandwidth_in, bandwidth_out);
}


struct BlacklistCheckSwitchContext
{
  struct BlacklistCheckSwitchContext *prev;
  struct BlacklistCheckSwitchContext *next;


  struct GST_BlacklistCheck *blc;

  struct GNUNET_HELLO_Address *address;
  struct Session *session;
  struct GNUNET_ATS_Information *ats;
  uint32_t ats_count;

  struct GNUNET_BANDWIDTH_Value32NBO bandwidth_in;
  struct GNUNET_BANDWIDTH_Value32NBO bandwidth_out;
};

/**
 * Black list check result for try_connect call
 * If connection to the peer is allowed request adddress and
 *
 * @param cls blc_ctx bl context
 * @param peer the peer
 * @param result the result
 */
static void
try_connect_bl_check_cont (void *cls,
    const struct GNUNET_PeerIdentity *peer, int result)
{
  struct BlacklistCheckSwitchContext *blc_ctx = cls;
  struct NeighbourMapEntry *n;

  GNUNET_CONTAINER_DLL_remove (pending_bc_head, pending_bc_tail, blc_ctx);
  GNUNET_free (blc_ctx);

  if (GNUNET_OK != result)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
        _("Blacklisting disapproved to connect to peer `%s'\n"),
        GNUNET_i2s (peer));
    return;
  }

  /* Setup a new neighbour */
  n = setup_neighbour (peer);

  /* Request address suggestions for this peer */
  set_state_and_timeout (n, GNUNET_TRANSPORT_PS_INIT_ATS,
      GNUNET_TIME_relative_to_absolute (ATS_RESPONSE_TIMEOUT));
  GNUNET_ATS_reset_backoff (GST_ats, peer);
  n->suggest_handle = GNUNET_ATS_suggest_address (GST_ats, peer,
      &address_suggest_cont, n);
}



/**
 * Try to create a connection to the given target (eventually).
 *
 * @param target peer to try to connect to
 */
void
GST_neighbours_try_connect (const struct GNUNET_PeerIdentity *target)
{
  struct NeighbourMapEntry *n;
  struct GST_BlacklistCheck *blc;
  struct BlacklistCheckSwitchContext *blc_ctx;

  if (NULL == neighbours)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Asked to connect to peer `%s' during shutdown\n",
                GNUNET_i2s (target));
    return; /* during shutdown, do nothing */
  }
  n = lookup_neighbour (target);
  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Asked to connect to peer `%s' (state: %s)\n",
              GNUNET_i2s (target),
              (NULL != n) ? GNUNET_TRANSPORT_ps2s(n->state) : "NEW PEER");
  if (NULL != n)
  {
    switch (n->state)
    {
    case GNUNET_TRANSPORT_PS_NOT_CONNECTED:
      /* this should not be possible */
      GNUNET_break (0);
      free_neighbour (n, GNUNET_NO);
      break;
    case GNUNET_TRANSPORT_PS_INIT_ATS:
    case GNUNET_TRANSPORT_PS_CONNECT_SENT:
    case GNUNET_TRANSPORT_PS_CONNECT_RECV_ATS:
    case GNUNET_TRANSPORT_PS_CONNECT_RECV_ACK:
      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                  "Ignoring request to try to connect to `%s', already trying!\n",
                  GNUNET_i2s (target));
      return; /* already trying */
    case GNUNET_TRANSPORT_PS_CONNECTED:
    case GNUNET_TRANSPORT_PS_RECONNECT_ATS:
    case GNUNET_TRANSPORT_PS_RECONNECT_SENT:
    case GNUNET_TRANSPORT_PS_CONNECTED_SWITCHING_CONNECT_SENT:
      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                  "Ignoring request to try to connect, already connected to `%s'!\n",
                  GNUNET_i2s (target));
      return; /* already connected */
    case GNUNET_TRANSPORT_PS_DISCONNECT:
      /* get rid of remains, ready to re-try immediately */
      free_neighbour (n, GNUNET_NO);
      break;
    case GNUNET_TRANSPORT_PS_DISCONNECT_FINISHED:
      /* should not be possible */
      GNUNET_assert (0);
      return;
    default:
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                  "Unhandled state `%s'\n",
                  GNUNET_TRANSPORT_ps2s (n->state));
      GNUNET_break (0);
      free_neighbour (n, GNUNET_NO);
      break;
    }
  }

  /* Do blacklist check if connecting to this peer is allowed */
  blc_ctx = GNUNET_new (struct BlacklistCheckSwitchContext);
  GNUNET_CONTAINER_DLL_insert (pending_bc_head, pending_bc_tail, blc_ctx);

  if (NULL != (blc = GST_blacklist_test_allowed (target, NULL,
        &try_connect_bl_check_cont, blc_ctx)))
  {
    blc_ctx->blc = blc;
  }
}


/**
 * We received a 'SESSION_CONNECT' message from the other peer.
 * Consider switching to it.
 *
 * @param message possibly a 'struct SessionConnectMessage' (check format)
 * @param peer identity of the peer to switch the address for
 * @return #GNUNET_OK if the message was fine, #GNUNET_SYSERR on serious error
 */
int
GST_neighbours_handle_connect (const struct GNUNET_MessageHeader *message,
                               const struct GNUNET_PeerIdentity *peer)
{
  const struct SessionConnectMessage *scm;
  struct NeighbourMapEntry *n;
  struct GNUNET_TIME_Absolute ts;

  if (ntohs (message->size) != sizeof (struct SessionConnectMessage))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  GNUNET_STATISTICS_update (GST_stats,
                            gettext_noop
                            ("# CONNECT messages received"),
                            1, GNUNET_NO);
  if (NULL == neighbours)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                _("CONNECT request from peer `%s' ignored due impending shutdown\n"),
                GNUNET_i2s (peer));
    return GNUNET_OK; /* we're shutting down */
  }
  scm = (const struct SessionConnectMessage *) message;
  GNUNET_break_op (0 == ntohl (scm->reserved));
  ts = GNUNET_TIME_absolute_ntoh (scm->timestamp);
  n = lookup_neighbour (peer);
  if (NULL == n)
  {
    /* This is a new neighbour and set to not connected */
    n = setup_neighbour (peer);
  }

  /* Remember this CONNECT message in neighbour */
  n->ack_state = ACK_SEND_CONNECT_ACK;
  n->connect_ack_timestamp = ts;

  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Received CONNECT for peer `%s' in state %s/%s\n",
              GNUNET_i2s (peer),
              GNUNET_TRANSPORT_ps2s (n->state),
              print_ack_state (n->ack_state));

  switch (n->state)
  {
  case GNUNET_TRANSPORT_PS_NOT_CONNECTED:
    /* Request an address from ATS to send CONNECT_ACK to this peer */
    set_state_and_timeout (n, GNUNET_TRANSPORT_PS_CONNECT_RECV_ATS,
        GNUNET_TIME_relative_to_absolute (ATS_RESPONSE_TIMEOUT));
    if (NULL == n->suggest_handle)
      GNUNET_ATS_suggest_address (GST_ats, peer, address_suggest_cont, n);
    break;
  case GNUNET_TRANSPORT_PS_INIT_ATS:
    /* CONNECT message takes priority over us asking ATS for address:
     * Wait for ATS to suggest an address and send CONNECT_ACK */
    set_state_and_timeout (n, GNUNET_TRANSPORT_PS_CONNECT_RECV_ATS,
        GNUNET_TIME_relative_to_absolute (ATS_RESPONSE_TIMEOUT));
    break;
  case GNUNET_TRANSPORT_PS_CONNECT_RECV_ATS:
    /* We already wait for an address to send an CONNECT_ACK */
    break;
  case GNUNET_TRANSPORT_PS_CONNECT_SENT:
  case GNUNET_TRANSPORT_PS_CONNECT_RECV_ACK:
    /* Send ACK immediately */
    n->ack_state = ACK_SEND_SESSION_ACK;
    send_connect_ack_message (n->primary_address.address,
                              n->primary_address.session, ts);
    break;
  case GNUNET_TRANSPORT_PS_CONNECTED:
    /* we are already connected and can thus send the ACK immediately */
    GNUNET_assert (NULL != n->primary_address.address);
    GNUNET_assert (NULL != n->primary_address.session);
    n->ack_state = ACK_SEND_SESSION_ACK;
    send_connect_ack_message (n->primary_address.address,
                              n->primary_address.session, ts);
    break;
  case GNUNET_TRANSPORT_PS_RECONNECT_ATS:
    /* We wait for ATS address suggestion */
    break;
  case GNUNET_TRANSPORT_PS_RECONNECT_SENT:
    /* We received a CONNECT message while waiting for a CONNECT_ACK in fast
     * reconnect. Send CONNECT_ACK immediately */
    n->ack_state = ACK_SEND_SESSION_ACK;
    send_connect_ack_message (n->primary_address.address,
        n->primary_address.session, n->connect_ack_timestamp);
    break;
  case GNUNET_TRANSPORT_PS_CONNECTED_SWITCHING_CONNECT_SENT:
    /* We are already connected and can thus send the ACK immediately;
       still, it can never hurt to have an alternative address, so also
       tell ATS  about it */
    GNUNET_assert (NULL != n->primary_address.address);
    GNUNET_assert (NULL != n->primary_address.session);
    n->ack_state = ACK_SEND_SESSION_ACK;
    send_connect_ack_message (n->primary_address.address,
        n->primary_address.session, ts);
    break;
  case GNUNET_TRANSPORT_PS_DISCONNECT:
    /* Get rid of remains without terminating sessions, ready to re-try */
    free_neighbour (n, GNUNET_YES);
    n = setup_neighbour (peer);
    /* Remember the CONNECT time stamp for ACK message */
    n->ack_state = ACK_SEND_CONNECT_ACK;
    n->connect_ack_timestamp = ts;
    /* Request an address for the peer */
    GNUNET_ATS_suggest_address (GST_ats, peer, address_suggest_cont, n);
    GNUNET_ATS_reset_backoff (GST_ats, peer);
    set_state (n, GNUNET_TRANSPORT_PS_CONNECT_RECV_ATS);
    break;
  case GNUNET_TRANSPORT_PS_DISCONNECT_FINISHED:
    /* should not be possible */
    GNUNET_assert (0);
    break;
  default:
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Unhandled state `%s'\n",
                GNUNET_TRANSPORT_ps2s (n->state));
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  return GNUNET_OK;
}

static void
switch_address_bl_check_cont (void *cls,
    const struct GNUNET_PeerIdentity *peer, int result)
{
  struct BlacklistCheckSwitchContext *blc_ctx = cls;
  struct GNUNET_TRANSPORT_PluginFunctions *papi;
  struct NeighbourMapEntry *n;

  papi = GST_plugins_find (blc_ctx->address->transport_name);

  if ( (NULL == (n = lookup_neighbour (peer))) || (result == GNUNET_NO) ||
       (NULL == (papi)) )
  {
    if (NULL == n)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Peer %s is unknown, suggestion ignored\n",
                  GNUNET_i2s (peer));
    }
    if (result == GNUNET_NO)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
          "Blacklist denied to switch to suggested address `%s' session %p for peer `%s'\n",
          GST_plugins_a2s (blc_ctx->address),
          blc_ctx->session,
          GNUNET_i2s (&blc_ctx->address->peer));
    }
    if (NULL == papi)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
          "Plugin `%s' for suggested address `%s' session %p for peer `%s' is not available\n",
          blc_ctx->address->transport_name,
          GST_plugins_a2s (blc_ctx->address),
          blc_ctx->session,
          GNUNET_i2s (&blc_ctx->address->peer));
    }

    /* This address is blacklisted, delete address and session (if existing) in ATS */
    GNUNET_ATS_address_destroyed (GST_ats, blc_ctx->address, blc_ctx->session);

    if ( (GNUNET_YES == (GNUNET_HELLO_address_check_option (blc_ctx->address,
          GNUNET_HELLO_ADDRESS_INFO_INBOUND))) && (NULL != blc_ctx->session))
    {
      /* This is an inbound address, destroy full  address */
      GNUNET_ATS_address_destroyed (GST_ats, blc_ctx->address, NULL );
    }

    /* Remove blacklist check and clean up */
    GNUNET_CONTAINER_DLL_remove (pending_bc_head, pending_bc_tail, blc_ctx);
    GNUNET_HELLO_address_free (blc_ctx->address);
    GNUNET_free_non_null (blc_ctx->ats);
    GNUNET_free (blc_ctx);
    return;
  }

  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
      "Blacklist accepted address `%s' session %p for peer `%s'\n",
      GST_plugins_a2s (blc_ctx->address),
      blc_ctx->session,
      GNUNET_i2s (&blc_ctx->address->peer));

  if (NULL == blc_ctx->session)
  {
    blc_ctx->session = papi->get_session (papi->cls, blc_ctx->address);
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Obtained new session for peer `%s' and  address '%s': %p\n",
                GNUNET_i2s (&blc_ctx->address->peer), GST_plugins_a2s (blc_ctx->address), blc_ctx->session);
  }
  if (NULL == blc_ctx->session)
  {
    /* No session could be obtained, remove blacklist check and clean up */
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Failed to obtain new session for peer `%s' and  address '%s'\n",
                GNUNET_i2s (&blc_ctx->address->peer),
                GST_plugins_a2s (blc_ctx->address));
    /* Delete address in ATS */
    GNUNET_ATS_address_destroyed (GST_ats, blc_ctx->address, NULL);

    GNUNET_CONTAINER_DLL_remove (pending_bc_head, pending_bc_tail, blc_ctx);
    GNUNET_HELLO_address_free (blc_ctx->address);
    GNUNET_free_non_null (blc_ctx->ats);
    GNUNET_free (blc_ctx);
    return;
  }

  if ( (NULL != n->primary_address.address) &&
       (0 == GNUNET_HELLO_address_cmp(blc_ctx->address, n->primary_address.address)) )
  {
    if (blc_ctx->session == n->primary_address.session)
    {
      /* Same address, update only quotas */
      GNUNET_log (GNUNET_ERROR_TYPE_INFO, "Update with same address!\n");
    }
  }

  switch (n->state)
  {
  case GNUNET_TRANSPORT_PS_NOT_CONNECTED:
    GNUNET_break (0);
    free_neighbour (n, GNUNET_NO);
    return;
  case GNUNET_TRANSPORT_PS_INIT_ATS:
    /* We requested an address and ATS suggests one:
     * set primary address and send CONNECT message*/
    set_primary_address (n, blc_ctx->address, blc_ctx->session,
        blc_ctx->bandwidth_in, blc_ctx->bandwidth_out, GNUNET_NO);
    if ( (ACK_SEND_CONNECT_ACK == n->ack_state) )
    {
      /* Send pending CONNECT_ACK message */
      n->ack_state = ACK_SEND_SESSION_ACK;
      send_connect_ack_message (n->primary_address.address,
          n->primary_address.session, n->connect_ack_timestamp);
    }
    set_state_and_timeout (n, GNUNET_TRANSPORT_PS_CONNECT_SENT,
        GNUNET_TIME_relative_to_absolute (SETUP_CONNECTION_TIMEOUT));
    send_session_connect (&n->primary_address);
    break;
  case GNUNET_TRANSPORT_PS_CONNECT_SENT:
    /* ATS suggested a new address while waiting for an CONNECT_ACK:
     * Switch and send new CONNECT */
    /* ATS suggests a different address, switch again */
    set_primary_address (n, blc_ctx->address, blc_ctx->session,
        blc_ctx->bandwidth_in, blc_ctx->bandwidth_out, GNUNET_NO);
    if (ACK_SEND_CONNECT_ACK == n->ack_state)
    {
      /* Send pending CONNECT_ACK message */
      n->ack_state = ACK_SEND_SESSION_ACK;
      send_connect_ack_message (n->primary_address.address,
          n->primary_address.session, n->connect_ack_timestamp);
    }
    set_state_and_timeout (n, GNUNET_TRANSPORT_PS_CONNECT_SENT,
        GNUNET_TIME_relative_to_absolute (SETUP_CONNECTION_TIMEOUT));
    send_session_connect (&n->primary_address);
    break;
  case GNUNET_TRANSPORT_PS_CONNECT_RECV_ATS:
    /* We requested an address and ATS suggests one:
     * set primary address and send CONNECT_ACK message*/
    set_primary_address (n, blc_ctx->address, blc_ctx->session,
        blc_ctx->bandwidth_in, blc_ctx->bandwidth_out, GNUNET_NO);
    /* Send an ACK message as a response to the CONNECT msg */
    set_state_and_timeout (n, GNUNET_TRANSPORT_PS_CONNECT_RECV_ACK,
        GNUNET_TIME_relative_to_absolute (SETUP_CONNECTION_TIMEOUT));
    send_connect_ack_message (n->primary_address.address,
                              n->primary_address.session,
                              n->connect_ack_timestamp);
    if ( (ACK_SEND_CONNECT_ACK == n->ack_state) ||
         (ACK_UNDEFINED == n->ack_state) )
      n->ack_state = ACK_SEND_SESSION_ACK;
    break;
  case GNUNET_TRANSPORT_PS_CONNECT_RECV_ACK:
    /* ATS asks us to switch while we were trying to connect; switch to new
       address and check blacklist again */
    if ( (ACK_SEND_CONNECT_ACK == n->ack_state) )
    {
      n->ack_state = ACK_SEND_SESSION_ACK;
      send_connect_ack_message (n->primary_address.address,
          n->primary_address.session, n->connect_ack_timestamp);
    }
    set_primary_address (n, blc_ctx->address, blc_ctx->session,
        blc_ctx->bandwidth_in, blc_ctx->bandwidth_out, GNUNET_NO);
    set_state_and_timeout (n, GNUNET_TRANSPORT_PS_CONNECT_RECV_ACK,
        GNUNET_TIME_relative_to_absolute (SETUP_CONNECTION_TIMEOUT));
    break;
  case GNUNET_TRANSPORT_PS_CONNECTED:
    GNUNET_assert (NULL != n->primary_address.address);
    GNUNET_assert (NULL != n->primary_address.session);
    if (n->primary_address.session == blc_ctx->session)
    {
      /* not an address change, just a quota change */
      set_primary_address (n, blc_ctx->address, blc_ctx->session,
          blc_ctx->bandwidth_in, blc_ctx->bandwidth_out, GNUNET_YES);
      break;
    }
    /* ATS asks us to switch a life connection; see if we can get
       a CONNECT_ACK on it before we actually do this! */
    set_alternative_address (n, blc_ctx->address, blc_ctx->session,
        blc_ctx->bandwidth_in, blc_ctx->bandwidth_out);
    set_state_and_timeout (n, GNUNET_TRANSPORT_PS_CONNECTED_SWITCHING_CONNECT_SENT,
        GNUNET_TIME_relative_to_absolute (SETUP_CONNECTION_TIMEOUT));
    GNUNET_STATISTICS_update (GST_stats, gettext_noop
        ("# Attempts to switch addresses"), 1, GNUNET_NO);
    send_session_connect (&n->alternative_address);
    break;
  case GNUNET_TRANSPORT_PS_RECONNECT_ATS:
    set_primary_address (n, blc_ctx->address, blc_ctx->session,
        blc_ctx->bandwidth_in, blc_ctx->bandwidth_out, GNUNET_NO);
    if ( (ACK_SEND_CONNECT_ACK == n->ack_state) )
    {
      /* Send pending CONNECT_ACK message */
      n->ack_state = ACK_SEND_SESSION_ACK;
      send_connect_ack_message (n->primary_address.address,
          n->primary_address.session, n->connect_ack_timestamp);
    }
    set_state_and_timeout (n, GNUNET_TRANSPORT_PS_RECONNECT_SENT,
        GNUNET_TIME_relative_to_absolute (FAST_RECONNECT_TIMEOUT));
    send_session_connect (&n->primary_address);
    break;
  case GNUNET_TRANSPORT_PS_RECONNECT_SENT:
    /* ATS asks us to switch while we were trying to reconnect; switch to new
       address and send CONNECT again */
    set_primary_address (n, blc_ctx->address, blc_ctx->session,
        blc_ctx->bandwidth_in, blc_ctx->bandwidth_out, GNUNET_NO);
    set_state_and_timeout (n, GNUNET_TRANSPORT_PS_RECONNECT_SENT,
        GNUNET_TIME_relative_to_absolute (FAST_RECONNECT_TIMEOUT));
    send_session_connect (&n->primary_address);
    break;
  case GNUNET_TRANSPORT_PS_CONNECTED_SWITCHING_CONNECT_SENT:
    if ( (0 == GNUNET_HELLO_address_cmp(n->primary_address.address,
        blc_ctx->address) && n->primary_address.session == blc_ctx->session) )
    {
      /* ATS switches back to still-active session */
      free_address (&n->alternative_address);
      set_state (n, GNUNET_TRANSPORT_PS_CONNECTED);
      break;
    }
    /* ATS asks us to switch a life connection, send */
    set_alternative_address (n, blc_ctx->address, blc_ctx->session,
        blc_ctx->bandwidth_in, blc_ctx->bandwidth_out);
    set_state_and_timeout (n, GNUNET_TRANSPORT_PS_CONNECTED_SWITCHING_CONNECT_SENT,
        GNUNET_TIME_relative_to_absolute (SETUP_CONNECTION_TIMEOUT));
    send_session_connect (&n->alternative_address);
    break;
  case GNUNET_TRANSPORT_PS_DISCONNECT:
    /* not going to switch addresses while disconnecting */
    return;
  case GNUNET_TRANSPORT_PS_DISCONNECT_FINISHED:
    GNUNET_assert (0);
    break;
  default:
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Unhandled state `%s'\n",
                GNUNET_TRANSPORT_ps2s (n->state));
    GNUNET_break (0);
    break;
  }

  GNUNET_CONTAINER_DLL_remove (pending_bc_head, pending_bc_tail, blc_ctx);
  GNUNET_HELLO_address_free(blc_ctx->address);
  GNUNET_free_non_null (blc_ctx->ats);
  GNUNET_free (blc_ctx);
  return;
}


/**
 * For the given peer, switch to this address.
 *
 * Before accepting this addresses and actively using it, a blacklist check
 * is performed. If this blacklist check fails the address will be destroyed.
 *
 * @param peer identity of the peer to switch the address for
 * @param address address of the other peer,
 * @param session session to use or NULL if transport should initiate a session
 * @param ats performance data
 * @param ats_count number of entries in ats
 * @param bandwidth_in inbound quota to be used when connection is up,
 *      0 to disconnect from peer
 * @param bandwidth_out outbound quota to be used when connection is up,
 *      0 to disconnect from peer
 */
void
GST_neighbours_switch_to_address (const struct GNUNET_PeerIdentity *peer,
                                  const struct GNUNET_HELLO_Address *address,
                                  struct Session *session,
                                  const struct GNUNET_ATS_Information *ats,
                                  uint32_t ats_count,
                                  struct GNUNET_BANDWIDTH_Value32NBO bandwidth_in,
                                  struct GNUNET_BANDWIDTH_Value32NBO bandwidth_out)
{
  struct NeighbourMapEntry *n;
  struct GST_BlacklistCheck *blc;
  struct BlacklistCheckSwitchContext *blc_ctx;
  int c;

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "ATS has decided on an address for peer %s\n",
              GNUNET_i2s (peer));
  GNUNET_assert (NULL != address->transport_name);
  if (NULL == (n = lookup_neighbour (peer)))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Peer %s is unknown, suggestion ignored\n",
                GNUNET_i2s (peer));
    return;
  }

  /* Check if plugin is available */
  if (NULL == (GST_plugins_find (address->transport_name)))
  {
    /* we don't have the plugin for this address */
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Plugin `%s' is unknown, suggestion for peer %s ignored\n",
                address->transport_name,
                GNUNET_i2s (peer));
    GNUNET_ATS_address_destroyed (GST_ats, address, NULL);
    return;
  }
  if ((NULL == session) &&
      (GNUNET_HELLO_address_check_option (address, GNUNET_HELLO_ADDRESS_INFO_INBOUND)))
  {
    /* This is a inbound address and we do not have a session to use! */
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Inbound address without session `%s'! Destroying address...\n",
                GST_plugins_a2s (address));
    GNUNET_ATS_address_destroyed (GST_ats, address, NULL);
    return;
  }

  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
    "ATS suggests %s address '%s' session %p for "
    "peer `%s' in state %s/%s \n",
    GNUNET_HELLO_address_check_option (address,
        GNUNET_HELLO_ADDRESS_INFO_INBOUND) ? "inbound" : "outbound",
    GST_plugins_a2s (address), session, GNUNET_i2s (peer),
    GNUNET_TRANSPORT_ps2s (n->state), print_ack_state (n->ack_state));

  /* Perform blacklist check */
  blc_ctx = GNUNET_new (struct BlacklistCheckSwitchContext);
  blc_ctx->address = GNUNET_HELLO_address_copy (address);
  blc_ctx->session = session;
  blc_ctx->bandwidth_in = bandwidth_in;
  blc_ctx->bandwidth_out = bandwidth_out;
  blc_ctx->ats_count = ats_count;
  blc_ctx->ats = NULL;
  if (ats_count > 0)
  {
    blc_ctx->ats = GNUNET_malloc (ats_count * sizeof (struct GNUNET_ATS_Information));
    for (c = 0; c < ats_count; c++)
    {
      blc_ctx->ats[c].type = ats[c].type;
      blc_ctx->ats[c].value = ats[c].value;
    }
  }

  GNUNET_CONTAINER_DLL_insert (pending_bc_head, pending_bc_tail, blc_ctx);
  if (NULL != (blc = GST_blacklist_test_allowed (peer, address->transport_name,
      &switch_address_bl_check_cont, blc_ctx)))
  {
    blc_ctx->blc = blc;
  }
}


static int
send_utilization_data (void *cls,
                       const struct GNUNET_PeerIdentity *key,
                       void *value)
{
  struct NeighbourMapEntry *n = value;
  struct GNUNET_ATS_Information atsi[4];
  uint32_t bps_pl_in;
  uint32_t bps_pl_out;
  uint32_t bps_in;
  uint32_t bps_out;
  struct GNUNET_TIME_Relative delta;

  delta = GNUNET_TIME_absolute_get_difference (n->last_util_transmission,
                                               GNUNET_TIME_absolute_get ());

  bps_pl_in = 0;

  if ((0 != n->util_payload_bytes_recv) && (0 != delta.rel_value_us))
    bps_pl_in =  (1000LL * 1000LL *  n->util_payload_bytes_recv) / (delta.rel_value_us);
  bps_pl_out = 0;
  if ((0 != n->util_payload_bytes_sent) && (0 != delta.rel_value_us))
    bps_pl_out = (1000LL * 1000LL * n->util_payload_bytes_sent) / delta.rel_value_us;
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "`%s' payload: received %u Bytes/s, sent %u Bytes/s\n",
              GNUNET_i2s (key),
              bps_pl_in,
              bps_pl_out);
  bps_in = 0;
  if ((0 != n->util_total_bytes_recv) && (0 != delta.rel_value_us))
    bps_in =  (1000LL * 1000LL *  n->util_total_bytes_recv) / (delta.rel_value_us);
  bps_out = 0;
  if ((0 != n->util_total_bytes_sent) && (0 != delta.rel_value_us))
    bps_out = (1000LL * 1000LL * n->util_total_bytes_sent) / delta.rel_value_us;


  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "`%s' total: received %u Bytes/s, sent %u Bytes/s\n",
              GNUNET_i2s (key),
              bps_in,
              bps_out);
  atsi[0].type = htonl (GNUNET_ATS_UTILIZATION_OUT);
  atsi[0].value = htonl (bps_out);
  atsi[1].type = htonl (GNUNET_ATS_UTILIZATION_IN);
  atsi[1].value = htonl (bps_in);

  atsi[2].type = htonl (GNUNET_ATS_UTILIZATION_PAYLOAD_OUT);
  atsi[2].value = htonl (bps_pl_out);
  atsi[3].type = htonl (GNUNET_ATS_UTILIZATION_PAYLOAD_IN);
  atsi[3].value = htonl (bps_pl_in);

  GST_ats_update_metrics (key, n->primary_address.address,
      n->primary_address.session, atsi, 4);
  n->util_payload_bytes_recv = 0;
  n->util_payload_bytes_sent = 0;
  n->util_total_bytes_recv = 0;
  n->util_total_bytes_sent = 0;
  n->last_util_transmission = GNUNET_TIME_absolute_get();
  return GNUNET_OK;
}


/**
 * Task transmitting utilization in a regular interval
 *
 * @param cls the 'struct NeighbourMapEntry' for which we are running
 * @param tc scheduler context (unused)
 */
static void
utilization_transmission (void *cls,
                          const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  util_transmission_tk = GNUNET_SCHEDULER_NO_TASK;

  if (0 < GNUNET_CONTAINER_multipeermap_size (neighbours))
    GNUNET_CONTAINER_multipeermap_iterate (neighbours, send_utilization_data, NULL);

  util_transmission_tk = GNUNET_SCHEDULER_add_delayed (UTIL_TRANSMISSION_INTERVAL,
      utilization_transmission, NULL);

}


void
GST_neighbours_notify_data_recv (const struct GNUNET_PeerIdentity *peer,
                                 const struct GNUNET_HELLO_Address *address,
                                 struct Session *session,
                                 const struct GNUNET_MessageHeader *message)
{
  struct NeighbourMapEntry *n;

  n = lookup_neighbour (peer);
  if (NULL == n)
    return;
  n->util_total_bytes_recv += ntohs(message->size);
}


void
GST_neighbours_notify_payload_recv (const struct GNUNET_PeerIdentity *peer,
                                    const struct GNUNET_HELLO_Address *address,
                                    struct Session *session,
                                    const struct GNUNET_MessageHeader *message)
{
  struct NeighbourMapEntry *n;
  n = lookup_neighbour (peer);
  if (NULL == n)
    return;
  n->util_payload_bytes_recv += ntohs(message->size);
}


void
GST_neighbours_notify_data_sent (const struct GNUNET_PeerIdentity *peer,
                                 const struct GNUNET_HELLO_Address *address,
                                 struct Session *session,
                                 size_t size)
{
  struct NeighbourMapEntry *n;
  n = lookup_neighbour (peer);
  if (NULL == n)
      return;
  if (n->primary_address.session != session)
    return;
  n->util_total_bytes_sent += size;
}


void
GST_neighbours_notify_payload_sent (const struct GNUNET_PeerIdentity *peer,
                                    size_t size)
{
  struct NeighbourMapEntry *n;
  n = lookup_neighbour (peer);
  if (NULL == n)
    return;
  n->util_payload_bytes_sent += size;
}


/**
 * Master task run for every neighbour.  Performs all of the time-related
 * activities (keep alive, send next message, disconnect if idle, finish
 * clean up after disconnect).
 *
 * @param cls the 'struct NeighbourMapEntry' for which we are running
 * @param tc scheduler context (unused)
 */
static void
master_task (void *cls,
             const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct NeighbourMapEntry *n = cls;
  struct GNUNET_TIME_Relative delay;

  n->task = GNUNET_SCHEDULER_NO_TASK;
  delay = GNUNET_TIME_absolute_get_remaining (n->timeout);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Master task runs for neighbour `%s' in state %s with timeout in %s\n",
              GNUNET_i2s (&n->id),
              GNUNET_TRANSPORT_ps2s(n->state),
              GNUNET_STRINGS_relative_time_to_string (delay,
                                                      GNUNET_YES));
  switch (n->state)
  {
  case GNUNET_TRANSPORT_PS_NOT_CONNECTED:
    /* invalid state for master task, clean up */
    GNUNET_break (0);
    free_neighbour (n, GNUNET_NO);
    return;
  case GNUNET_TRANSPORT_PS_INIT_ATS:
    if (0 == delay.rel_value_us)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                  "Connection to `%s' timed out waiting for ATS to provide address\n",
                  GNUNET_i2s (&n->id));
      free_neighbour (n, GNUNET_NO);
      return;
    }
    break;
  case GNUNET_TRANSPORT_PS_CONNECT_SENT:
    if (0 == delay.rel_value_us)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                  "Connection to `%s' timed out waiting for other peer to send CONNECT_ACK\n",
                  GNUNET_i2s (&n->id));
      /* We could not send to this address, delete address and session */
      if (NULL != n->primary_address.session)
        GNUNET_ATS_address_destroyed (GST_ats, n->primary_address.address,
            n->primary_address.session);
      GNUNET_ATS_address_destroyed (GST_ats, n->primary_address.address, NULL);

      /* Remove address and request and additional one */
      unset_primary_address (n);
      set_state_and_timeout (n, GNUNET_TRANSPORT_PS_INIT_ATS,
          GNUNET_TIME_relative_to_absolute (ATS_RESPONSE_TIMEOUT));
      return;
    }
    break;
  case GNUNET_TRANSPORT_PS_CONNECT_RECV_ATS:
    if (0 == delay.rel_value_us)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                  "Connection to `%s' timed out waiting ATS to provide address to use for CONNECT_ACK\n",
                  GNUNET_i2s (&n->id));
      free_neighbour (n, GNUNET_NO);
      return;
    }
    break;
  case GNUNET_TRANSPORT_PS_CONNECT_RECV_ACK:
    if (0 == delay.rel_value_us)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                  "Connection to `%s' timed out waiting for other peer to send SESSION_ACK\n",
                  GNUNET_i2s (&n->id));
      disconnect_neighbour (n);
      return;
    }
    break;
  case GNUNET_TRANSPORT_PS_CONNECTED:
    if (0 == delay.rel_value_us)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                  "Connection to `%s' timed out, missing KEEPALIVE_RESPONSEs\n",
                  GNUNET_i2s (&n->id));
      disconnect_neighbour (n);
      return;
    }
    try_transmission_to_peer (n);
    send_keepalive (n);
    break;
  case GNUNET_TRANSPORT_PS_RECONNECT_ATS:
    if (0 == delay.rel_value_us)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                  "Connection to `%s' timed out, waiting for ATS replacement address\n",
                  GNUNET_i2s (&n->id));
      disconnect_neighbour (n);
      return;
    }
    break;
  case GNUNET_TRANSPORT_PS_RECONNECT_SENT:
    if (0 == delay.rel_value_us)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                  "Connection to `%s' timed out, waiting for other peer to CONNECT_ACK replacement address\n",
                  GNUNET_i2s (&n->id));
      disconnect_neighbour (n);
      return;
    }
    break;
  case GNUNET_TRANSPORT_PS_CONNECTED_SWITCHING_CONNECT_SENT:
    if (0 == delay.rel_value_us)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                  "Connection to `%s' timed out, missing KEEPALIVE_RESPONSEs (after trying to CONNECT on alternative address)\n",
                  GNUNET_i2s (&n->id));
      GNUNET_STATISTICS_update (GST_stats, gettext_noop
          ("# Failed attempts to switch addresses (no response)"), 1, GNUNET_NO);
      disconnect_neighbour (n);
      return;
    }
    try_transmission_to_peer (n);
    send_keepalive (n);
    break;
  case GNUNET_TRANSPORT_PS_DISCONNECT:
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                "Cleaning up connection to `%s' after sending DISCONNECT\n",
                GNUNET_i2s (&n->id));
    free_neighbour (n, GNUNET_NO);
    return;
  case GNUNET_TRANSPORT_PS_DISCONNECT_FINISHED:
    /* how did we get here!? */
    GNUNET_assert (0);
    break;
  default:
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Unhandled state `%s'\n",
                GNUNET_TRANSPORT_ps2s (n->state));
    GNUNET_break (0);
    break;
  }
  if ( (GNUNET_TRANSPORT_PS_CONNECTED_SWITCHING_CONNECT_SENT == n->state) ||
       (GNUNET_TRANSPORT_PS_CONNECTED == n->state) )
  {
    /* if we are *now* in one of the two states, we're sending
       keep alive messages, so we need to consider the keepalive
       delay, not just the connection timeout */
    delay = GNUNET_TIME_relative_min (GNUNET_TIME_absolute_get_remaining (n->keep_alive_time),
                                      delay);
  }
  if (GNUNET_SCHEDULER_NO_TASK == n->task)
    n->task = GNUNET_SCHEDULER_add_delayed (delay,
                                            &master_task,
                                            n);
}


/**
 * Send a SESSION_ACK message to the neighbour to confirm that we
 * got his CONNECT_ACK.
 *
 * @param n neighbour to send the SESSION_ACK to
 */
static void
send_session_ack_message (struct NeighbourMapEntry *n)
{
  struct GNUNET_MessageHeader msg;

  GNUNET_log (GNUNET_ERROR_TYPE_INFO, "Sending SESSION_ACK message to peer `%s'\n",
              GNUNET_i2s (&n->id));

  msg.size = htons (sizeof (struct GNUNET_MessageHeader));
  msg.type = htons (GNUNET_MESSAGE_TYPE_TRANSPORT_SESSION_ACK);
  (void) send_with_session(n,
                           (const char *) &msg, sizeof (struct GNUNET_MessageHeader),
                           UINT32_MAX, GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_NO,
                           NULL, NULL);
}


/**
 * We received a 'SESSION_CONNECT_ACK' message from the other peer.
 * Consider switching to it.
 *
 * @param message possibly a 'struct SessionConnectMessage' (check format)
 * @param peer identity of the peer to switch the address for
 * @param address address of the other peer, NULL if other peer
 *                       connected to us
 * @param session session to use (or NULL)
 * @return #GNUNET_OK if the message was fine, #GNUNET_SYSERR on serious error
 */
int
GST_neighbours_handle_connect_ack (const struct GNUNET_MessageHeader *message,
                                   const struct GNUNET_PeerIdentity *peer,
                                   const struct GNUNET_HELLO_Address *address,
                                   struct Session *session)
{
  const struct SessionConnectMessage *scm;
  struct GNUNET_TIME_Absolute ts;
  struct NeighbourMapEntry *n;

  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Received CONNECT_ACK message from peer `%s'\n",
              GNUNET_i2s (peer));

  if (ntohs (message->size) != sizeof (struct SessionConnectMessage))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  GNUNET_STATISTICS_update (GST_stats,
                            gettext_noop
                            ("# CONNECT_ACK messages received"),
                            1, GNUNET_NO);
  scm = (const struct SessionConnectMessage *) message;
  GNUNET_break_op (ntohl (scm->reserved) == 0);
  if (NULL == (n = lookup_neighbour (peer)))
  {
    GNUNET_STATISTICS_update (GST_stats,
                              gettext_noop
                              ("# unexpected CONNECT_ACK messages (no peer)"),
                              1, GNUNET_NO);
    return GNUNET_SYSERR;
  }
  ts = GNUNET_TIME_absolute_ntoh (scm->timestamp);
  switch (n->state)
  {
  case GNUNET_TRANSPORT_PS_NOT_CONNECTED:
    GNUNET_break (0);
    free_neighbour (n, GNUNET_NO);
    return GNUNET_SYSERR;
  case GNUNET_TRANSPORT_PS_INIT_ATS:
    GNUNET_STATISTICS_update (GST_stats,
                              gettext_noop
                              ("# unexpected CONNECT_ACK messages (not ready)"),
                              1, GNUNET_NO);
    break;
  case GNUNET_TRANSPORT_PS_CONNECT_SENT:
    if (ts.abs_value_us != n->primary_address.connect_timestamp.abs_value_us)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                  "CONNECT_ACK ignored as the timestamp does not match our CONNECT request\n");
      return GNUNET_OK;
    }
    set_state_and_timeout (n, GNUNET_TRANSPORT_PS_CONNECTED,
        GNUNET_TIME_relative_to_absolute (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT));
    GNUNET_STATISTICS_set (GST_stats,
                           gettext_noop ("# peers connected"),
                           ++neighbours_connected,
                           GNUNET_NO);
    connect_notify_cb (callback_cls, &n->id,
                       n->primary_address.bandwidth_in,
                       n->primary_address.bandwidth_out);
    /* Tell ATS that the outbound session we created to send CONNECT was successful */
    GST_ats_add_address (n->primary_address.address,
                         n->primary_address.session,
                         NULL, 0);
    set_primary_address (n,
                 n->primary_address.address,
                 n->primary_address.session,
                 n->primary_address.bandwidth_in,
                 n->primary_address.bandwidth_out,
                 GNUNET_YES);
    send_session_ack_message (n);
    break;
  case GNUNET_TRANSPORT_PS_CONNECT_RECV_ATS:
  case GNUNET_TRANSPORT_PS_CONNECT_RECV_ACK:
    GNUNET_STATISTICS_update (GST_stats,
                              gettext_noop
                              ("# unexpected CONNECT_ACK messages (not ready)"),
                              1, GNUNET_NO);
    break;
  case GNUNET_TRANSPORT_PS_CONNECTED:
    /* duplicate CONNECT_ACK, let's answer by duplicate SESSION_ACK just in case */
    send_session_ack_message (n);
    break;
  case GNUNET_TRANSPORT_PS_RECONNECT_ATS:
    /* we didn't expect any CONNECT_ACK, as we are waiting for ATS
       to give us a new address... */
    GNUNET_STATISTICS_update (GST_stats,
                              gettext_noop
                              ("# unexpected CONNECT_ACK messages (waiting on ATS)"),
                              1, GNUNET_NO);
    break;
  case GNUNET_TRANSPORT_PS_RECONNECT_SENT:
    /* Reconnecting with new address address worked; go back to connected! */
    set_state_and_timeout (n, GNUNET_TRANSPORT_PS_CONNECTED,
        GNUNET_TIME_relative_to_absolute (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT));
    send_session_ack_message (n);
    break;
  case GNUNET_TRANSPORT_PS_CONNECTED_SWITCHING_CONNECT_SENT:
    /* new address worked; adopt it and go back to connected! */
    set_state_and_timeout (n, GNUNET_TRANSPORT_PS_CONNECTED,
        GNUNET_TIME_relative_to_absolute (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT));
    GNUNET_break (GNUNET_NO == n->alternative_address.ats_active);

    /* Notify about session... perhaps we obtained it */
    GST_ats_add_address (n->alternative_address.address,
        n->alternative_address.session, NULL, 0);
    /* Set primary addresses */
    set_primary_address (n, n->alternative_address.address,
        n->alternative_address.session, n->alternative_address.bandwidth_in,
        n->alternative_address.bandwidth_out, GNUNET_YES);
    GNUNET_STATISTICS_update (GST_stats, gettext_noop
        ("# Successful attempts to switch addresses"), 1, GNUNET_NO);

    free_address (&n->alternative_address);
    send_session_ack_message (n);
    break;
  case GNUNET_TRANSPORT_PS_DISCONNECT:
    GNUNET_STATISTICS_update (GST_stats,
                              gettext_noop
                              ("# unexpected CONNECT_ACK messages (disconnecting)"),
                              1, GNUNET_NO);
    return GNUNET_SYSERR;
  case GNUNET_TRANSPORT_PS_DISCONNECT_FINISHED:
    GNUNET_assert (0);
    break;
  default:
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Unhandled state `%s'\n",
                GNUNET_TRANSPORT_ps2s (n->state));
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  return GNUNET_OK;
}


/**
 * A session was terminated. Take note; if needed, try to get
 * an alternative address from ATS.
 *
 * @param peer identity of the peer where the session died
 * @param session session that is gone
 * @return #GNUNET_YES if this was a session used, #GNUNET_NO if
 *        this session was not in use
 */
int
GST_neighbours_session_terminated (const struct GNUNET_PeerIdentity *peer,
                                   struct Session *session)
{
  struct NeighbourMapEntry *n;
  struct BlackListCheckContext *bcc;
  struct BlackListCheckContext *bcc_next;

  /* make sure to cancel all ongoing blacklist checks involving 'session' */
  bcc_next = bc_head;
  while (NULL != (bcc = bcc_next))
  {
    bcc_next = bcc->next;
    if (bcc->na.session == session)
    {
      if (NULL != bcc->bc)
        GST_blacklist_test_cancel (bcc->bc);
      GNUNET_HELLO_address_free (bcc->na.address);
      GNUNET_CONTAINER_DLL_remove (bc_head,
                                   bc_tail,
                                   bcc);
      GNUNET_free (bcc);
    }
  }
  if (NULL == (n = lookup_neighbour (peer)))
    return GNUNET_NO; /* can't affect us */
  if (session != n->primary_address.session)
  {
    if (session == n->alternative_address.session)
    {
      if ( (GNUNET_TRANSPORT_PS_CONNECTED_SWITCHING_CONNECT_SENT == n->state) )
        set_state (n, GNUNET_TRANSPORT_PS_CONNECTED);
      else
        free_address (&n->alternative_address);
    }
    return GNUNET_NO; /* doesn't affect us further */
  }

  n->expect_latency_response = GNUNET_NO;
  /* The session for neighbour's primary address died */
  switch (n->state)
  {
  case GNUNET_TRANSPORT_PS_NOT_CONNECTED:
    GNUNET_break (0);
    free_neighbour (n, GNUNET_NO);
    return GNUNET_YES;
  case GNUNET_TRANSPORT_PS_INIT_ATS:
    GNUNET_break (0);
    free_neighbour (n, GNUNET_NO);
    return GNUNET_YES;
  case GNUNET_TRANSPORT_PS_CONNECT_SENT:
    /* The session used to send the CONNECT terminated:
     * this implies a connect error*/
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                "Failed to send CONNECT in %s with `%s' %p: session terminated\n",
                "CONNECT_SENT",
                GST_plugins_a2s (n->primary_address.address),
                n->primary_address.session,
                GNUNET_i2s (peer));

    /* Destroy the address since it cannot be used */
    GNUNET_ATS_address_destroyed (GST_ats, n->primary_address.address, NULL);
    unset_primary_address (n);
    set_state_and_timeout (n, GNUNET_TRANSPORT_PS_INIT_ATS,
        GNUNET_TIME_relative_to_absolute (ATS_RESPONSE_TIMEOUT));
    break;
  case GNUNET_TRANSPORT_PS_CONNECT_RECV_ATS:
  case GNUNET_TRANSPORT_PS_CONNECT_RECV_ACK:
    /* error on inbound session; free neighbour entirely */
    free_address (&n->primary_address);
    free_neighbour (n, GNUNET_NO);
    return GNUNET_YES;
  case GNUNET_TRANSPORT_PS_CONNECTED:
    /* Our primary connection died, try a fast reconnect */
    unset_primary_address (n);
    set_state_and_timeout (n, GNUNET_TRANSPORT_PS_RECONNECT_ATS,
        GNUNET_TIME_relative_to_absolute (ATS_RESPONSE_TIMEOUT));
    break;
  case GNUNET_TRANSPORT_PS_RECONNECT_ATS:
    /* we don't have an address, how can it go down? */
    GNUNET_break (0);
    break;
  case GNUNET_TRANSPORT_PS_RECONNECT_SENT:
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                "Failed to send CONNECT in %s with `%s' %p: session terminated\n",
                "RECONNECT_SENT",
                GST_plugins_a2s (n->primary_address.address),
                n->primary_address.session,
                GNUNET_i2s (peer));

    /* Destroy the address since it cannot be used */
    GNUNET_ATS_address_destroyed (GST_ats, n->primary_address.address, NULL);
    unset_primary_address (n);
    set_state_and_timeout (n, GNUNET_TRANSPORT_PS_RECONNECT_ATS,
        GNUNET_TIME_relative_to_absolute (ATS_RESPONSE_TIMEOUT));
    break;
  case GNUNET_TRANSPORT_PS_CONNECTED_SWITCHING_CONNECT_SENT:
    /* primary went down while we were waiting for CONNECT_ACK on secondary;
       secondary as primary */

    /* Destroy the inbound address since it cannot be used */
    if (GNUNET_YES
        == GNUNET_HELLO_address_check_option (n->primary_address.address,
            GNUNET_HELLO_ADDRESS_INFO_INBOUND))
      GNUNET_ATS_address_destroyed (GST_ats, n->primary_address.address, NULL);
    free_address (&n->primary_address);
    n->primary_address = n->alternative_address;
    memset (&n->alternative_address, 0, sizeof (struct NeighbourAddress));
    set_state_and_timeout (n, GNUNET_TRANSPORT_PS_RECONNECT_ATS,
        GNUNET_TIME_relative_to_absolute (FAST_RECONNECT_TIMEOUT));
    break;
  case GNUNET_TRANSPORT_PS_DISCONNECT:
    free_address (&n->primary_address);
    break;
  case GNUNET_TRANSPORT_PS_DISCONNECT_FINISHED:
    /* neighbour was freed and plugins told to terminate session */
    return GNUNET_NO;
    break;
  default:
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Unhandled state `%s'\n",
                GNUNET_TRANSPORT_ps2s (n->state));
    GNUNET_break (0);
    break;
  }
  if (GNUNET_SCHEDULER_NO_TASK != n->task)
    GNUNET_SCHEDULER_cancel (n->task);
  n->task = GNUNET_SCHEDULER_add_now (&master_task, n);
  return GNUNET_YES;
}


/**
 * We received a 'SESSION_ACK' message from the other peer.
 * If we sent a 'CONNECT_ACK' last, this means we are now
 * connected.  Otherwise, do nothing.
 *
 * @param message possibly a 'struct SessionConnectMessage' (check format)
 * @param peer identity of the peer to switch the address for
 * @param address address of the other peer, NULL if other peer
 *                       connected to us
 * @param session session to use (or NULL)
 * @return #GNUNET_OK if the message was fine, #GNUNET_SYSERR on serious error
 */
int
GST_neighbours_handle_session_ack (const struct GNUNET_MessageHeader *message,
                                   const struct GNUNET_PeerIdentity *peer,
                                   const struct GNUNET_HELLO_Address *address,
                                   struct Session *session)
{
  struct NeighbourMapEntry *n;

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Received SESSION_ACK message from peer `%s'\n",
              GNUNET_i2s (peer));
  if (ntohs (message->size) != sizeof (struct GNUNET_MessageHeader))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  GNUNET_STATISTICS_update (GST_stats,
                            gettext_noop
                            ("# SESSION_ACK messages received"),
                            1, GNUNET_NO);
  if (NULL == (n = lookup_neighbour (peer)))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }

  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Received %s for peer `%s' in state %s/%s\n",
              "SESSION_ACK",
              GNUNET_i2s (peer),
              GNUNET_TRANSPORT_ps2s (n->state),
              print_ack_state (n->ack_state));

  /* Check if we are in a plausible state for having sent
     a CONNECT_ACK.  If not, return, otherwise break.

     The remote peers sends a SESSION_ACK as a response for a CONNECT_ACK
     message.

     We expect a SESSION_ACK:
     - If a remote peer has sent a CONNECT, we responded with a CONNECT_ACK and
     now wait for the ACK to finally be connected
     - If we sent a CONNECT_ACK to this peer before */

  if (   (GNUNET_TRANSPORT_PS_CONNECT_RECV_ACK != n->state) &&
         (ACK_SEND_SESSION_ACK != n->ack_state))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                "Received unexpected SESSION_ACK message from peer `%s' in state %s/%s\n",
                GNUNET_i2s (peer),
                GNUNET_TRANSPORT_ps2s (n->state),
                print_ack_state (n->ack_state));

    GNUNET_STATISTICS_update (GST_stats,
                              gettext_noop ("# unexpected SESSION_ACK messages"), 1,
                              GNUNET_NO);
    return GNUNET_OK;
  }

  /* We are connected */
  if (GNUNET_NO == GST_neighbours_test_connected(&n->id))
  {
    /* Notify about connection */
    connect_notify_cb (callback_cls, &n->id,
                     n->primary_address.bandwidth_in,
                     n->primary_address.bandwidth_out);\

     GNUNET_STATISTICS_set (GST_stats,
                            gettext_noop ("# peers connected"),
                            ++neighbours_connected,
                            GNUNET_NO);
  }

  if (GNUNET_TRANSPORT_PS_CONNECTED_SWITCHING_CONNECT_SENT == n->state)
  {
    /* We tried to switch addresses while being connect. We explicitly wait
     * for a CONNECT_ACK before going to GNUNET_TRANSPORT_PS_CONNECTED,
     * so we do not want to set the address as in use! */
    return GNUNET_OK;
  }

  set_state_and_timeout (n, GNUNET_TRANSPORT_PS_CONNECTED,
    GNUNET_TIME_relative_to_absolute (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT));

  /* Add session to ATS since no session was given (NULL) and we may have
   * obtained a new session */
  GST_ats_add_address (n->primary_address.address, n->primary_address.session,
      NULL, 0);

  /* Set primary address to used */
  set_primary_address (n,
               n->primary_address.address,
               n->primary_address.session,
               n->primary_address.bandwidth_in,
               n->primary_address.bandwidth_out,
               GNUNET_YES);
  return GNUNET_OK;
}


/**
 * Test if we're connected to the given peer.
 *
 * @param target peer to test
 * @return #GNUNET_YES if we are connected, #GNUNET_NO if not
 */
int
GST_neighbours_test_connected (const struct GNUNET_PeerIdentity *target)
{
  return test_connected (lookup_neighbour (target));
}

/**
 * Change the incoming quota for the given peer.
 *
 * @param neighbour identity of peer to change qutoa for
 * @param quota new quota
 */
void
GST_neighbours_set_incoming_quota (const struct GNUNET_PeerIdentity *neighbour,
                                   struct GNUNET_BANDWIDTH_Value32NBO quota)
{
  struct NeighbourMapEntry *n;

  if (NULL == (n = lookup_neighbour (neighbour)))
  {
    GNUNET_STATISTICS_update (GST_stats,
                              gettext_noop
                              ("# SET QUOTA messages ignored (no such peer)"),
                              1, GNUNET_NO);
    return;
  }
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Setting inbound quota of %u Bps for peer `%s' to all clients\n",
              ntohl (quota.value__), GNUNET_i2s (&n->id));
  GNUNET_BANDWIDTH_tracker_update_quota (&n->in_tracker, quota);
  if (0 != ntohl (quota.value__))
    return;
  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Disconnecting peer `%4s' due to SET_QUOTA\n",
              GNUNET_i2s (&n->id));
  if (GNUNET_YES == test_connected (n))
    GNUNET_STATISTICS_update (GST_stats,
                              gettext_noop ("# disconnects due to quota of 0"),
                              1, GNUNET_NO);
  disconnect_neighbour (n);
}

void delayed_disconnect (void *cls,
    const struct GNUNET_SCHEDULER_TaskContext* tc)
{
  struct NeighbourMapEntry *n = cls;

  n->delayed_disconnect_task = GNUNET_SCHEDULER_NO_TASK;
  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Disconnecting by request from peer %s\n",
              GNUNET_i2s (&n->id));
  free_neighbour (n, GNUNET_NO);
}


/**
 * We received a disconnect message from the given peer,
 * validate and process.
 *
 * @param peer sender of the message
 * @param msg the disconnect message
 */
void
GST_neighbours_handle_disconnect_message (const struct GNUNET_PeerIdentity *peer,
                                          const struct GNUNET_MessageHeader *msg)
{
  struct NeighbourMapEntry *n;
  const struct SessionDisconnectMessage *sdm;

  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Received DISCONNECT message from peer `%s'\n",
              GNUNET_i2s (peer));
  if (ntohs (msg->size) != sizeof (struct SessionDisconnectMessage))
  {
    GNUNET_break_op (0);
    GNUNET_STATISTICS_update (GST_stats,
                              gettext_noop
                              ("# disconnect messages ignored (malformed)"), 1,
                              GNUNET_NO);
    return;
  }
  GNUNET_STATISTICS_update (GST_stats,
                            gettext_noop
                            ("# DISCONNECT messages received"),
                            1, GNUNET_NO);
  sdm = (const struct SessionDisconnectMessage *) msg;
  if (NULL == (n = lookup_neighbour (peer)))
    return;                     /* gone already */
  if (GNUNET_TIME_absolute_ntoh (sdm->timestamp).abs_value_us <= n->connect_ack_timestamp.abs_value_us)
  {
    GNUNET_STATISTICS_update (GST_stats,
                              gettext_noop
                              ("# disconnect messages ignored (timestamp)"), 1,
                              GNUNET_NO);
    return;
  }
  if (0 != memcmp (peer, &sdm->public_key, sizeof (struct GNUNET_PeerIdentity)))
  {
    GNUNET_break_op (0);
    return;
  }
  if (ntohl (sdm->purpose.size) !=
      sizeof (struct GNUNET_CRYPTO_EccSignaturePurpose) +
      sizeof (struct GNUNET_CRYPTO_EddsaPublicKey) +
      sizeof (struct GNUNET_TIME_AbsoluteNBO))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                "%s message from peer `%s' has invalid size \n",
                "DISCONNECT",
                GNUNET_i2s (peer));
    GNUNET_break_op (0);
    return;
  }
  if (GNUNET_OK !=
      GNUNET_CRYPTO_eddsa_verify
      (GNUNET_MESSAGE_TYPE_TRANSPORT_SESSION_DISCONNECT, &sdm->purpose,
       &sdm->signature, &sdm->public_key))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                "%s message from peer `%s' cannot be verified \n",
                "DISCONNECT",
                GNUNET_i2s (peer));
    GNUNET_break_op (0);
    return;
  }
  n->delayed_disconnect_task = GNUNET_SCHEDULER_add_now (&delayed_disconnect, n);
}


/**
 * Closure for the neighbours_iterate function.
 */
struct IteratorContext
{
  /**
   * Function to call on each connected neighbour.
   */
  GST_NeighbourIterator cb;

  /**
   * Closure for 'cb'.
   */
  void *cb_cls;
};


/**
 * Call the callback from the closure for each neighbour.
 *
 * @param cls the `struct IteratorContext`
 * @param key the hash of the public key of the neighbour
 * @param value the `struct NeighbourMapEntry`
 * @return #GNUNET_OK (continue to iterate)
 */
static int
neighbours_iterate (void *cls,
                    const struct GNUNET_PeerIdentity *key,
                    void *value)
{
  struct IteratorContext *ic = cls;
  struct NeighbourMapEntry *n = value;
  struct GNUNET_BANDWIDTH_Value32NBO bandwidth_in;
  struct GNUNET_BANDWIDTH_Value32NBO bandwidth_out;


  if (NULL != n->primary_address.address)
  {
    bandwidth_in = n->primary_address.bandwidth_in;
    bandwidth_out = n->primary_address.bandwidth_out;
  }
  else
  {
    bandwidth_in = GNUNET_CONSTANTS_DEFAULT_BW_IN_OUT;
    bandwidth_out = GNUNET_CONSTANTS_DEFAULT_BW_IN_OUT;
  }
  ic->cb (ic->cb_cls,
          &n->id,
          n->primary_address.address,
          n->state,
          n->timeout,
          bandwidth_in, bandwidth_out);
  return GNUNET_OK;
}


/**
 * Iterate over all connected neighbours.
 *
 * @param cb function to call
 * @param cb_cls closure for cb
 */
void
GST_neighbours_iterate (GST_NeighbourIterator cb, void *cb_cls)
{
  struct IteratorContext ic;

  if (NULL == neighbours)
    return; /* can happen during shutdown */
  ic.cb = cb;
  ic.cb_cls = cb_cls;
  GNUNET_CONTAINER_multipeermap_iterate (neighbours, &neighbours_iterate, &ic);
}


/**
 * If we have an active connection to the given target, it must be shutdown.
 *
 * @param target peer to disconnect from
 */
void
GST_neighbours_force_disconnect (const struct GNUNET_PeerIdentity *target)
{
  struct NeighbourMapEntry *n;

  if (NULL == (n = lookup_neighbour (target)))
    return;  /* not active */
  if (GNUNET_YES == test_connected (n))
    GNUNET_STATISTICS_update (GST_stats,
                              gettext_noop
                              ("# disconnected from peer upon explicit request"), 1,
                              GNUNET_NO);
  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Forced disconnect from peer %s\n",
              GNUNET_i2s (target));
  disconnect_neighbour (n);
}


/**
 * Obtain current latency information for the given neighbour.
 *
 * @param peer to get the latency for
 * @return observed latency of the address, FOREVER if the
 *         the connection is not up
 */
struct GNUNET_TIME_Relative
GST_neighbour_get_latency (const struct GNUNET_PeerIdentity *peer)
{
  struct NeighbourMapEntry *n;

  n = lookup_neighbour (peer);
  if (NULL == n)
    return GNUNET_TIME_UNIT_FOREVER_REL;
  switch (n->state)
  {
  case GNUNET_TRANSPORT_PS_CONNECTED:
  case GNUNET_TRANSPORT_PS_CONNECTED_SWITCHING_CONNECT_SENT:
  case GNUNET_TRANSPORT_PS_RECONNECT_SENT:
  case GNUNET_TRANSPORT_PS_RECONNECT_ATS:
    return n->latency;
  case GNUNET_TRANSPORT_PS_NOT_CONNECTED:
  case GNUNET_TRANSPORT_PS_INIT_ATS:
  case GNUNET_TRANSPORT_PS_CONNECT_RECV_ATS:
  case GNUNET_TRANSPORT_PS_CONNECT_RECV_ACK:
  case GNUNET_TRANSPORT_PS_CONNECT_SENT:
  case GNUNET_TRANSPORT_PS_DISCONNECT:
  case GNUNET_TRANSPORT_PS_DISCONNECT_FINISHED:
    return GNUNET_TIME_UNIT_FOREVER_REL;
  default:
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Unhandled state `%s'\n",
                GNUNET_TRANSPORT_ps2s (n->state));
    GNUNET_break (0);
    break;
  }
  return GNUNET_TIME_UNIT_FOREVER_REL;
}


/**
 * Obtain current address information for the given neighbour.
 *
 * @param peer
 * @return address currently used
 */
struct GNUNET_HELLO_Address *
GST_neighbour_get_current_address (const struct GNUNET_PeerIdentity *peer)
{
  struct NeighbourMapEntry *n;

  n = lookup_neighbour (peer);
  if (NULL == n)
    return NULL;
  return n->primary_address.address;
}


/**
 * Initialize the neighbours subsystem.
 *
 * @param cls closure for callbacks
 * @param connect_cb function to call if we connect to a peer
 * @param disconnect_cb function to call if we disconnect from a peer
 * @param peer_address_cb function to call if we change an active address
 *                   of a neighbour
 * @param max_fds maximum number of fds to use
 */
void
GST_neighbours_start (void *cls,
                      NotifyConnect connect_cb,
                      GNUNET_TRANSPORT_NotifyDisconnect disconnect_cb,
                      GNUNET_TRANSPORT_NeighbourChangeCallback peer_address_cb,
                      unsigned int max_fds)
{
  callback_cls = cls;
  connect_notify_cb = connect_cb;
  disconnect_notify_cb = disconnect_cb;
  neighbour_change_cb = peer_address_cb;
  neighbours = GNUNET_CONTAINER_multipeermap_create (NEIGHBOUR_TABLE_SIZE, GNUNET_NO);
  registered_quota_notifications = GNUNET_CONTAINER_multipeermap_create (NEIGHBOUR_TABLE_SIZE, GNUNET_NO);
  util_transmission_tk = GNUNET_SCHEDULER_add_delayed (UTIL_TRANSMISSION_INTERVAL,
      utilization_transmission, NULL);
}


/**
 * Disconnect from the given neighbour.
 *
 * @param cls unused
 * @param key hash of neighbour's public key (not used)
 * @param value the 'struct NeighbourMapEntry' of the neighbour
 * @return #GNUNET_OK (continue to iterate)
 */
static int
disconnect_all_neighbours (void *cls,
                           const struct GNUNET_PeerIdentity *key,
                           void *value)
{
  struct NeighbourMapEntry *n = value;

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Disconnecting peer `%4s', %s\n",
              GNUNET_i2s (&n->id), "SHUTDOWN_TASK");
  free_neighbour (n, GNUNET_NO);
  return GNUNET_OK;
}


/**
 * Cleanup the neighbours subsystem.
 */
void
GST_neighbours_stop ()
{
  struct BlacklistCheckSwitchContext *cur;
  struct BlacklistCheckSwitchContext *next;

  if (NULL == neighbours)
    return;
  if (GNUNET_SCHEDULER_NO_TASK != util_transmission_tk)
  {
    GNUNET_SCHEDULER_cancel (util_transmission_tk);
    util_transmission_tk = GNUNET_SCHEDULER_NO_TASK;
  }

  GNUNET_CONTAINER_multipeermap_iterate (neighbours, &disconnect_all_neighbours,
      NULL );
  GNUNET_CONTAINER_multipeermap_destroy (neighbours);

  next = pending_bc_head;
  for (cur = next; NULL != cur; cur = next )
  {
    next = cur->next;
    GNUNET_CONTAINER_DLL_remove (pending_bc_head, pending_bc_tail, cur);

    if (NULL != cur->blc)
    {
      GST_blacklist_test_cancel (cur->blc);
      cur->blc = NULL;
    }
    if (NULL != cur->address)
      GNUNET_HELLO_address_free (cur->address);
    GNUNET_free_non_null (cur->ats);
    GNUNET_free (cur);
  }

  GNUNET_CONTAINER_multipeermap_iterate (registered_quota_notifications,
      &free_notification_cb, NULL);
  GNUNET_CONTAINER_multipeermap_destroy (registered_quota_notifications);
  registered_quota_notifications = NULL;

  neighbours = NULL;
  callback_cls = NULL;
  connect_notify_cb = NULL;
  disconnect_notify_cb = NULL;
  neighbour_change_cb = NULL;
}


/* end of file gnunet-service-transport_neighbours.c */