indentation

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

/*
     This file is part of GNUnet.
     (C) 2009, 2010 Christian Grothoff (and other contributing authors)

     GNUnet is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published
     by the Free Software Foundation; either version 3, or (at your
     option) any later version.

     GNUnet is distributed in the hope that it will be useful, but
     WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     General Public License for more details.

     You should have received a copy of the GNU General Public License
     along with GNUnet; see the file COPYING.  If not, write to the
     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
     Boston, MA 02111-1307, USA.
*/

/**
 * @file transport/gnunet-service-transport.c
 * @brief low-level P2P messaging
 * @author Christian Grothoff
 *
 */
#include "platform.h"
#include "gnunet_client_lib.h"
#include "gnunet_container_lib.h"
#include "gnunet_constants.h"
#include "gnunet_getopt_lib.h"
#include "gnunet_hello_lib.h"
#include "gnunet_os_lib.h"
#include "gnunet_peerinfo_service.h"
#include "gnunet_plugin_lib.h"
#include "gnunet_protocols.h"
#include "gnunet_service_lib.h"
#include "gnunet_signatures.h"
#include "gnunet_transport_plugin.h"
#include "gnunet-service-transport_ats.h"
#include "transport.h"



#define DEBUG_BLACKLIST GNUNET_NO

#define DEBUG_PING_PONG GNUNET_NO

#define DEBUG_TRANSPORT_HELLO GNUNET_NO

#define DEBUG_INBOUND GNUNET_NO

/**
 * Should we do some additional checks (to validate behavior
 * of clients)?
 */
#define EXTRA_CHECKS GNUNET_YES

/**
 * How many messages can we have pending for a given client process
 * before we start to drop incoming messages?  We typically should
 * have only one client and so this would be the primary buffer for
  * messages, so the number should be chosen rather generously.
 *
 * The expectation here is that most of the time the queue is large
 * enough so that a drop is virtually never required.  Note that
 * this value must be about as large as 'TOTAL_MSGS' in the
 * 'test_transport_api_reliability.c', otherwise that testcase may
 * fail.
 */
#define MAX_PENDING (128 * 1024)

/**
 * Size of the per-transport blacklist hash maps.
 */
#define TRANSPORT_BLACKLIST_HT_SIZE 16

/**
 * How often should we try to reconnect to a peer using a particular
 * transport plugin before giving up?  Note that the plugin may be
 * added back to the list after PLUGIN_RETRY_FREQUENCY expires.
 */
#define MAX_CONNECT_RETRY 3

/**
 * Limit on the number of ready-to-run tasks when validating
 * HELLOs.  If more tasks are ready to run, we will drop
 * HELLOs instead of validating them.
 */
#define MAX_HELLO_LOAD 4

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

/**
 * How long until a HELLO verification attempt should time out?
 * Must be rather small, otherwise a partially successful HELLO
 * validation (some addresses working) might not be available
 * before a client's request for a connection fails for good.
 * Besides, if a single request to an address takes a long time,
 * then the peer is unlikely worthwhile anyway.
 */
#define HELLO_VERIFICATION_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 15)

/**
 * How long is a PONG signature valid?  We'll recycle a signature until
 * 1/4 of this time is remaining.  PONGs should expire so that if our
 * external addresses change an adversary cannot replay them indefinitely.
 * OTOH, we don't want to spend too much time generating PONG signatures,
 * so they must have some lifetime to reduce our CPU usage.
 */
#define PONG_SIGNATURE_LIFETIME GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_HOURS, 1)

/**
 * Priority to use for PONG messages.
 */
#define TRANSPORT_PONG_PRIORITY 4

/**
 * How often do we re-add (cheaper) plugins to our list of plugins
 * to try for a given connected peer?
 */
#define PLUGIN_RETRY_FREQUENCY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 15)

/**
 * After how long do we expire an address in a HELLO that we just
 * validated?  This value is also used for our own addresses when we
 * create a HELLO.
 */
#define HELLO_ADDRESS_EXPIRATION GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_HOURS, 12)


/**
 * How long before an existing address expires should we again try to
 * validate it?  Must be (significantly) smaller than
 * HELLO_ADDRESS_EXPIRATION.
 */
#define HELLO_REVALIDATION_START_TIME GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_HOURS, 1)

/**
 * List of addresses of other peers
 */
struct ForeignAddressList
{
  /**
   * This is a linked list.
   */
  struct ForeignAddressList *next;

  /**
   * Which ready list does this entry belong to.
   */
  struct ReadyList *ready_list;

  /**
   * How long until we auto-expire this address (unless it is
   * re-confirmed by the transport)?
   */
  struct GNUNET_TIME_Absolute expires;

  /**
   * Task used to re-validate addresses, updates latencies and
   * verifies liveness.
   */
  GNUNET_SCHEDULER_TaskIdentifier revalidate_task;

  /**
   * The address.
   */
  const void *addr;

  /**
   * Session (or NULL if no valid session currently exists or if the
   * plugin does not use sessions).
   */
  struct Session *session;

  struct ATS_ressource_entry *ressources;

  struct ATS_quality_entry *quality;

  /**
   * What was the last latency observed for this address, plugin and peer?
   */
  struct GNUNET_TIME_Relative latency;

  /**
   * If we did not successfully transmit a message to the given peer
   * via this connection during the specified time, we should consider
   * the connection to be dead.  This is used in the case that a TCP
   * transport simply stalls writing to the stream but does not
   * formerly get a signal that the other peer died.
   */
  struct GNUNET_TIME_Absolute timeout;

  /**
   * How often have we tried to connect using this plugin?  Used to
   * discriminate against addresses that do not work well.
   * FIXME: not yet used, but should be!
   */
  unsigned int connect_attempts;

  /**
   * DV distance to this peer (1 if no DV is used).
   * FIXME: need to set this from transport plugins!
   */
  uint32_t distance;

  /**
   * Length of addr.
   */
  uint16_t addrlen;

  /**
   * Have we ever estimated the latency of this address?  Used to
   * ensure that the first time we add an address, we immediately
   * probe its latency.
   */
  int8_t estimated;

  /**
   * Are we currently connected via this address?  The first time we
   * successfully transmit or receive data to a peer via a particular
   * address, we set this to GNUNET_YES.  If we later get an error
   * (disconnect notification, transmission failure, timeout), we set
   * it back to GNUNET_NO.
   */
  int8_t connected;

  /**
   * Is this plugin currently busy transmitting to the specific target?
   * GNUNET_NO if not (initial, default state is GNUNET_NO).   Internal
   * messages do not count as 'in transmit'.
   */
  int8_t in_transmit;

  /**
   * Has this address been validated yet?
   */
  int8_t validated;

};


/**
 * Entry in linked list of network addresses for ourselves.  Also
 * includes a cached signature for 'struct TransportPongMessage's.
 */
struct OwnAddressList
{
  /**
   * This is a linked list.
   */
  struct OwnAddressList *next;

  /**
   * How long until the current signature expires? (ZERO if the
   * signature was never created).
   */
  struct GNUNET_TIME_Absolute pong_sig_expires;

  /**
   * Signature for a 'struct TransportPongMessage' for this address.
   */
  struct GNUNET_CRYPTO_RsaSignature pong_signature;

  /**
   * Length of addr.
   */
  uint32_t addrlen;

};


/**
 * Entry in linked list of all of our plugins.
 */
struct TransportPlugin
{
  /**
   * This is a linked list.
   */
  struct TransportPlugin *next;

  /**
   * API of the transport as returned by the plugin's
   * initialization function.
   */
  struct GNUNET_TRANSPORT_PluginFunctions *api;

  /**
   * Short name for the plugin (i.e. "tcp").
   */
  char *short_name;

  /**
   * Name of the library (i.e. "gnunet_plugin_transport_tcp").
   */
  char *lib_name;

  /**
   * List of our known addresses for this transport.
   */
  struct OwnAddressList *addresses;

  /**
   * Environment this transport service is using
   * for this plugin.
   */
  struct GNUNET_TRANSPORT_PluginEnvironment env;

  /**
   * ID of task that is used to clean up expired addresses.
   */
  GNUNET_SCHEDULER_TaskIdentifier address_update_task;

  /**
   * Set to GNUNET_YES if we need to scrap the existing list of
   * "addresses" and start fresh when we receive the next address
   * update from a transport.  Set to GNUNET_NO if we should just add
   * the new address to the list and wait for the commit call.
   */
  int rebuild;

  struct ATS_plugin *rc;

  /**
   * Hashmap of blacklisted peers for this particular transport.
   */
  struct GNUNET_CONTAINER_MultiHashMap *blacklist;
};

struct NeighbourMapEntry;

/**
 * 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;

  /**
   * 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;

  /**
   * Client responsible for queueing the message;
   * used to check that a client has no two messages
   * pending for the same target.  Can be NULL.
   */
  struct TransportClient *client;

  /**
   * Using which specific address should we send this message?
   */
  struct ForeignAddressList *specific_address;

  /**
   * Peer ID of the Neighbour this entry belongs to.
   */
  struct GNUNET_PeerIdentity neighbour_id;

  /**
   * Plugin that we used for the transmission.
   * NULL until we scheduled a transmission.
   */
  struct TransportPlugin *plugin;

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

  /**
   * Internal message of the transport system that should not be
   * included in the usual SEND-SEND_OK transmission confirmation
   * traffic management scheme.  Typically, "internal_msg" will
   * be set whenever "client" is NULL (but it is not strictly
   * required).
   */
  int internal_msg;

  /**
   * How important is the message?
   */
  unsigned int priority;

};


/**
 * For a given Neighbour, which plugins are available
 * to talk to this peer and what are their costs?
 */
struct ReadyList
{
  /**
   * This is a linked list.
   */
  struct ReadyList *next;

  /**
   * Which of our transport plugins does this entry
   * represent?
   */
  struct TransportPlugin *plugin;

  /**
   * Transport addresses, latency, and readiness for
   * this particular plugin.
   */
  struct ForeignAddressList *addresses;

  /**
   * To which neighbour does this ready list belong to?
   */
  struct NeighbourMapEntry *neighbour;
};


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

  /**
   * Which of our transports is connected to this peer
   * and what is their status?
   */
  struct ReadyList *plugins;

  /**
   * 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;

  /**
   * Head of list of messages of messages we expected the continuation
   * to be called to destroy the message
   */
  struct MessageQueue *cont_head;

  /**
   * Tail of list of messages of messages we expected the continuation
   * to be called to destroy the message
   */
  struct MessageQueue *cont_tail;

  /**
   * Buffer for at most one payload message used when we receive
   * payload data before our PING-PONG has succeeded.  We then
   * store such messages in this intermediary buffer until the
   * connection is fully up.
   */
  struct GNUNET_MessageHeader *pre_connect_message_buffer;

  /**
   * Context for peerinfo iteration.
   * NULL after we are done processing peerinfo's information.
   */
  struct GNUNET_PEERINFO_IteratorContext *piter;

  /**
   * Public key for this peer.   Valid only if the respective flag is set below.
   */
  struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded publicKey;

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

  /**
   * ID of task scheduled to run when this peer is about to
   * time out (will free resources associated with the peer).
   */
  GNUNET_SCHEDULER_TaskIdentifier timeout_task;

  /**
   * ID of task scheduled to run when we should retry transmitting
   * the head of the message queue.  Actually triggered when the
   * transmission is timing out (we trigger instantly when we have
   * a chance of success).
   */
  GNUNET_SCHEDULER_TaskIdentifier retry_task;

  /**
   * How long until we should consider this peer dead
   * (if we don't receive another message in the
   * meantime)?
   */
  struct GNUNET_TIME_Absolute peer_timeout;

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

  /**
   * The latency we have seen for this particular address for
   * this particular peer.  This latency may have been calculated
   * over multiple transports.  This value reflects how long it took
   * us to receive a response when SENDING via this particular
   * transport/neighbour/address combination!
   *
   * FIXME: we need to periodically send PINGs to update this
   * latency (at least more often than the current "huge" (11h?)
   * update interval).
   */
  struct GNUNET_TIME_Relative latency;

  /**
   * 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;

  /**
   * DV distance to this peer (1 if no DV is used).
   */
  uint32_t distance;

  /**
   * Have we seen an PONG from this neighbour in the past (and
   * not had a disconnect since)?
   */
  int received_pong;

  /**
   * Do we have a valid public key for this neighbour?
   */
  int public_key_valid;

  /**
   * Are we already in the process of disconnecting this neighbour?
   */
  int in_disconnect;

  /**
   * Performance data for the peer.
   */
  struct GNUNET_TRANSPORT_ATS_Information *ats;
};

/**
 * Message used to ask a peer to validate receipt (to check an address
 * from a HELLO).  Followed by the address we are trying to validate,
 * or an empty address if we are just sending a PING to confirm that a
 * connection which the receiver (of the PING) initiated is still valid.
 */
struct TransportPingMessage
{

  /**
   * Type will be GNUNET_MESSAGE_TYPE_TRANSPORT_PING
   */
  struct GNUNET_MessageHeader header;

  /**
   * Challenge code (to ensure fresh reply).
   */
  uint32_t challenge GNUNET_PACKED;

  /**
   * Who is the intended recipient?
   */
  struct GNUNET_PeerIdentity target;

};


/**
 * Message used to validate a HELLO.  The challenge is included in the
 * confirmation to make matching of replies to requests possible.  The
 * signature signs our public key, an expiration time and our address.<p>
 *
 * This message is followed by our transport address that the PING tried
 * to confirm (if we liked it).  The address can be empty (zero bytes)
 * if the PING had not address either (and we received the request via
 * a connection that we initiated).
 */
struct TransportPongMessage
{

  /**
   * Type will be GNUNET_MESSAGE_TYPE_TRANSPORT_PONG
   */
  struct GNUNET_MessageHeader header;

  /**
   * Challenge code from PING (showing freshness).  Not part of what
   * is signed so that we can re-use signatures.
   */
  uint32_t challenge GNUNET_PACKED;

  /**
   * Signature.
   */
  struct GNUNET_CRYPTO_RsaSignature signature;

  /**
   * What are we signing and why?  Two possible reason codes can be here:
   * GNUNET_SIGNATURE_PURPOSE_TRANSPORT_PONG_OWN to confirm that this is a
   * plausible address for this peer (pid is set to identity of signer); or
   * GNUNET_SIGNATURE_PURPOSE_TRANSPORT_PONG_USING to confirm that this is
   * an address we used to connect to the peer with the given pid.
   */
  struct GNUNET_CRYPTO_RsaSignaturePurpose purpose;

  /**
   * When does this signature expire?
   */
  struct GNUNET_TIME_AbsoluteNBO expiration;

  /**
   * Either the identity of the peer Who signed this message, or the
   * identity of the peer that we're connected to using the given
   * address (depending on purpose.type).
   */
  struct GNUNET_PeerIdentity pid;

  /**
   * Size of address appended to this message (part of what is
   * being signed, hence not redundant).
   */
  uint32_t addrlen;

};


/**
 * Linked list of messages to be transmitted to the client.  Each
 * entry is followed by the actual message.
 */
struct ClientMessageQueueEntry
{
  /**
   * This is a doubly-linked list.
   */
  struct ClientMessageQueueEntry *next;

  /**
   * This is a doubly-linked list.
   */
  struct ClientMessageQueueEntry *prev;
};


/**
 * Client connected to the transport service.
 */
struct TransportClient
{

  /**
   * This is a linked list.
   */
  struct TransportClient *next;

  /**
   * Handle to the client.
   */
  struct GNUNET_SERVER_Client *client;

  /**
   * Linked list of messages yet to be transmitted to
   * the client.
   */
  struct ClientMessageQueueEntry *message_queue_head;

  /**
   * Tail of linked list of messages yet to be transmitted to the
   * client.
   */
  struct ClientMessageQueueEntry *message_queue_tail;

  /**
   * Current transmit request handle.
   */
  struct GNUNET_CONNECTION_TransmitHandle *th;

  /**
   * Is a call to "transmit_send_continuation" pending?  If so, we
   * must not free this struct (even if the corresponding client
   * disconnects) and instead only remove it from the linked list and
   * set the "client" field to NULL.
   */
  int tcs_pending;

  /**
   * Length of the list of messages pending for this client.
   */
  unsigned int message_count;

};


/**
 * Context of currently active requests to peerinfo
 * for validation of HELLOs.
 */
struct CheckHelloValidatedContext;


/**
 * Entry in map of all HELLOs awaiting validation.
 */
struct ValidationEntry
{

  /**
   * NULL if this entry is not part of a larger HELLO validation.
   */
  struct CheckHelloValidatedContext *chvc;

  /**
   * The address, actually a pointer to the end
   * of this struct.  Do not free!
   */
  const void *addr;

  /**
   * Name of the transport.
   */
  char *transport_name;

  /**
   * The public key of the peer.
   */
  struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded publicKey;

  /**
   * ID of task that will clean up this entry if we don't succeed
   * with the validation first.
   */
  GNUNET_SCHEDULER_TaskIdentifier timeout_task;

  /**
   * At what time did we send this validation?
   */
  struct GNUNET_TIME_Absolute send_time;

  /**
   * Session being validated (or NULL for none).
   */
  struct Session *session;

  /**
   * Challenge number we used.
   */
  uint32_t challenge;

  /**
   * Length of addr.
   */
  uint16_t addrlen;

};


/**
 * Context of currently active requests to peerinfo
 * for validation of HELLOs.
 */
struct CheckHelloValidatedContext
{

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

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

  /**
   * Hello that we are validating.
   */
  const struct GNUNET_HELLO_Message *hello;

  /**
   * Context for peerinfo iteration.
   * NULL after we are done processing peerinfo's information.
   */
  struct GNUNET_PEERINFO_IteratorContext *piter;

  /**
   * Was a HELLO known for this peer to peerinfo?
   */
  int hello_known;

  /**
   * Number of validation entries currently referring to this
   * CHVC.
   */
  unsigned int ve_count;
};


/**
 * All zero hash for comparison.
 */
static GNUNET_HashCode null_hash;

/**
 * Our HELLO message.
 */
static struct GNUNET_HELLO_Message *our_hello;

/**
 * Our public key.
 */
static struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded my_public_key;

/**
 * Our identity.
 */
static struct GNUNET_PeerIdentity my_identity;

/**
 * Our private key.
 */
static struct GNUNET_CRYPTO_RsaPrivateKey *my_private_key;

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

/**
 * Linked list of all clients to this service.
 */
static struct TransportClient *clients;

/**
 * All loaded plugins.
 */
static struct TransportPlugin *plugins;

/**
 * Handle to peerinfo service.
 */
static struct GNUNET_PEERINFO_Handle *peerinfo;

/**
 * All known neighbours and their HELLOs.
 */
static struct GNUNET_CONTAINER_MultiHashMap *neighbours;

/**
 * Number of neighbours we'd like to have.
 */
static uint32_t max_connect_per_transport;

/**
 * Head of linked list.
 */
static struct CheckHelloValidatedContext *chvc_head;

/**
 * Tail of linked list.
 */
static struct CheckHelloValidatedContext *chvc_tail;

/**
 * Map of PeerIdentities to 'struct ValidationEntry*'s (addresses
 * of the given peer that we are currently validating).
 */
static struct GNUNET_CONTAINER_MultiHashMap *validation_map;

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

/**
 * Identifier of 'refresh_hello' task.
 */
static GNUNET_SCHEDULER_TaskIdentifier hello_task;

/**
 * Identifier of ats scheduler task.
 */
static GNUNET_SCHEDULER_TaskIdentifier ats_task;

/**
 * Is transport service shutting down ?
 */
static int shutdown_in_progress;

/**
 * Handle for ats information
 */
static struct ATS_Handle *ats;

/**
 * Time of last ats execution
 */
struct GNUNET_TIME_Absolute last_ats_execution;

/**
 * Minimum interval between two ATS executions
 */
struct GNUNET_TIME_Relative ats_minimum_interval;

/**
 * Regular interval when ATS execution is triggered
 */
struct GNUNET_TIME_Relative ats_regular_interval;

/**
 * The peer specified by the given neighbour has timed-out or a plugin
 * has disconnected.  We may either need to do nothing (other plugins
 * still up), or trigger a full disconnect and clean up.  This
 * function updates our state and do the necessary notifications.
 * Also notifies our clients that the neighbour is now officially
 * gone.
 *
 * @param n the neighbour list entry for the peer
 * @param check should we just check if all plugins
 *        disconnected or must we ask all plugins to
 *        disconnect?
 */
static void disconnect_neighbour (struct NeighbourMapEntry *n, int check);

/**
 * Check the ready list for the given neighbour and if a plugin is
 * ready for transmission (and if we have a message), do so!
 *
 * @param nexi target peer for which to transmit
 */
static void try_transmission_to_peer (struct NeighbourMapEntry *n);

struct ForeignAddressList *get_preferred_ats_address (struct NeighbourMapEntry
                                                      *n);

/**
 * Find an entry in the neighbour list for a particular peer.
 *
 * @return NULL if not found.
 */
static struct NeighbourMapEntry *
find_neighbour (const struct GNUNET_PeerIdentity *key)
{
  return GNUNET_CONTAINER_multihashmap_get (neighbours, &key->hashPubKey);
}

static int
update_addr_value (struct ForeignAddressList *fal, uint32_t value,
                   int ats_index)
{
  int c;
  int set = GNUNET_NO;

  for (c = 0; c < available_quality_metrics; c++)
  {
    if (ats_index == qm[c].atis_index)
    {
      fal->quality[c].values[0] = fal->quality[c].values[1];
      fal->quality[c].values[1] = fal->quality[c].values[2];
      fal->quality[c].values[2] = value;
      set = GNUNET_YES;
#if HAVE_LIBGLPK
      ats_modify_problem_state (ats, ATS_QUALITY_UPDATED);
#endif
    }
  }
  if (set == GNUNET_NO)
  {
    for (c = 0; c < available_ressources; c++)
    {
      if (ats_index == ressources[c].atis_index)
      {
        fal->ressources[c].c = value;
        set = GNUNET_YES;
#if HAVE_LIBGLPK
        ats_modify_problem_state (ats, ATS_COST_UPDATED);
#endif
      }
    }
  }
  return set;
}

static int
update_addr_ats (struct ForeignAddressList *fal,
                 const struct GNUNET_TRANSPORT_ATS_Information *ats_data,
                 int ats_count)
{
  int c1, set;

  set = GNUNET_NO;
  for (c1 = 0; c1 < ats_count; c1++)
  {
    set =
        update_addr_value (fal, ntohl (ats_data[c1].value),
                           ntohl (ats_data[c1].type));
  }
  return set;
}

/**
 * Find an entry in the transport list for a particular transport.
 *
 * @return NULL if not found.
 */
static struct TransportPlugin *
find_transport (const char *short_name)
{
  struct TransportPlugin *head = plugins;

  while ((head != NULL) && (0 != strcmp (short_name, head->short_name)))
    head = head->next;
  return head;
}

/**
 * Is a particular peer blacklisted for a particular transport?
 *
 * @param peer the peer to check for
 * @param plugin the plugin used to connect to the peer
 *
 * @return GNUNET_YES if the peer is blacklisted, GNUNET_NO if not
 */
static int
is_blacklisted (const struct GNUNET_PeerIdentity *peer,
                struct TransportPlugin *plugin)
{

  if (plugin->blacklist != NULL)
  {
    if (GNUNET_CONTAINER_multihashmap_contains
        (plugin->blacklist, &peer->hashPubKey) == GNUNET_YES)
    {
#if DEBUG_BLACKLIST
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Peer `%s:%s' is blacklisted!\n",
                  plugin->short_name, GNUNET_i2s (peer));
#endif
      if (stats != NULL)
        GNUNET_STATISTICS_update (stats, "# blacklisted peers refused", 1,
                                  GNUNET_NO);
      return GNUNET_YES;
    }
  }

  return GNUNET_NO;
}


static void
add_peer_to_blacklist (struct GNUNET_PeerIdentity *peer, char *transport_name)
{
  struct TransportPlugin *plugin;

  plugin = find_transport (transport_name);
  if (plugin == NULL)           /* Nothing to do */
    return;
#if DEBUG_TRANSPORT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Adding peer `%s' with plugin `%s' to blacklist\n",
              GNUNET_i2s (peer), transport_name);
#endif
  if (plugin->blacklist == NULL)
    plugin->blacklist =
        GNUNET_CONTAINER_multihashmap_create (TRANSPORT_BLACKLIST_HT_SIZE);
  GNUNET_assert (plugin->blacklist != NULL);
  GNUNET_CONTAINER_multihashmap_put (plugin->blacklist, &peer->hashPubKey,
                                     NULL,
                                     GNUNET_CONTAINER_MULTIHASHMAPOPTION_REPLACE);
}


/**
 * Read the blacklist file, containing transport:peer entries.
 * Provided the transport is loaded, set up hashmap with these
 * entries to blacklist peers by transport.
 *
 */
static void
read_blacklist_file (const struct GNUNET_CONFIGURATION_Handle *cfg)
{
  char *fn;
  char *data;
  size_t pos;
  size_t colon_pos;
  int tsize;
  struct GNUNET_PeerIdentity pid;
  struct stat frstat;
  struct GNUNET_CRYPTO_HashAsciiEncoded enc;
  unsigned int entries_found;
  char *transport_name;

  if (GNUNET_OK !=
      GNUNET_CONFIGURATION_get_value_filename (cfg,
                                               "TRANSPORT",
                                               "BLACKLIST_FILE", &fn))
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Option `%s' in section `%s' not specified!\n",
                "BLACKLIST_FILE", "TRANSPORT");
#endif
    return;
  }
  if (GNUNET_OK != GNUNET_DISK_file_test (fn))
    GNUNET_DISK_fn_write (fn, NULL, 0, GNUNET_DISK_PERM_USER_READ
                          | GNUNET_DISK_PERM_USER_WRITE);
  if (0 != STAT (fn, &frstat))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                _("Could not read blacklist file `%s'\n"), fn);
    GNUNET_free (fn);
    return;
  }
  if (frstat.st_size == 0)
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                _("Blacklist file `%s' is empty.\n"), fn);
#endif
    GNUNET_free (fn);
    return;
  }
  /* FIXME: use mmap */
  data = GNUNET_malloc_large (frstat.st_size);
  GNUNET_assert (data != NULL);
  if (frstat.st_size != GNUNET_DISK_fn_read (fn, data, frstat.st_size))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                _("Failed to read blacklist from `%s'\n"), fn);
    GNUNET_free (fn);
    GNUNET_free (data);
    return;
  }
  entries_found = 0;
  pos = 0;
  while ((pos < frstat.st_size) && isspace ((unsigned char) data[pos]))
    pos++;
  while ((frstat.st_size >= sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded)) &&
         (pos <=
          frstat.st_size - sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded)))
  {
    colon_pos = pos;
    while ((colon_pos < frstat.st_size) && (data[colon_pos] != ':') &&
           !isspace ((unsigned char) data[colon_pos]))
      colon_pos++;

    if (colon_pos >= frstat.st_size)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                  _
                  ("Syntax error in blacklist file at offset %llu, giving up!\n"),
                  (unsigned long long) colon_pos);
      GNUNET_free (fn);
      GNUNET_free (data);
      return;
    }

    if (isspace ((unsigned char) data[colon_pos]))
    {
      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                  _
                  ("Syntax error in blacklist file at offset %llu, skipping bytes.\n"),
                  (unsigned long long) colon_pos);
      pos = colon_pos;
      while ((pos < frstat.st_size) && isspace ((unsigned char) data[pos]))
        pos++;
      continue;
    }
    tsize = colon_pos - pos;
    if ((pos >= frstat.st_size) || (pos + tsize >= frstat.st_size) ||
        (tsize == 0))
    {
      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                  _
                  ("Syntax error in blacklist file at offset %llu, giving up!\n"),
                  (unsigned long long) colon_pos);
      GNUNET_free (fn);
      GNUNET_free (data);
      return;
    }

    if (tsize < 1)
      continue;

    transport_name = GNUNET_malloc (tsize + 1);
    memcpy (transport_name, &data[pos], tsize);
    pos = colon_pos + 1;
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Read transport name %s in blacklist file.\n", transport_name);
#endif
    memcpy (&enc, &data[pos], sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded));
    if (!isspace
        ((unsigned char)
         enc.encoding[sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded) - 1]))
    {
      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                  _
                  ("Syntax error in blacklist file at offset %llu, skipping bytes.\n"),
                  (unsigned long long) pos);
      pos++;
      while ((pos < frstat.st_size) && (!isspace ((unsigned char) data[pos])))
        pos++;
      GNUNET_free_non_null (transport_name);
      continue;
    }
    enc.encoding[sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded) - 1] = '\0';
    if (GNUNET_OK !=
        GNUNET_CRYPTO_hash_from_string ((char *) &enc, &pid.hashPubKey))
    {
      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                  _
                  ("Syntax error in blacklist file at offset %llu, skipping bytes `%s'.\n"),
                  (unsigned long long) pos, &enc);
    }
    else
    {
      if (0 != memcmp (&pid, &my_identity, sizeof (struct GNUNET_PeerIdentity)))
      {
        entries_found++;
        add_peer_to_blacklist (&pid, transport_name);
      }
      else
      {
        GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                    _("Found myself `%s' in blacklist (useless, ignored)\n"),
                    GNUNET_i2s (&pid));
      }
    }
    pos = pos + sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded);
    GNUNET_free_non_null (transport_name);
    while ((pos < frstat.st_size) && isspace ((unsigned char) data[pos]))
      pos++;
  }
  GNUNET_STATISTICS_update (stats, "# Transport entries blacklisted",
                            entries_found, GNUNET_NO);
  GNUNET_free (data);
  GNUNET_free (fn);
}


/**
 * Function called to notify a client about the socket being ready to
 * queue more data.  "buf" will be NULL and "size" zero if the socket
 * was closed for writing in the meantime.
 *
 * @param cls closure
 * @param size number of bytes available in buf
 * @param buf where the callee should write the message
 * @return number of bytes written to buf
 */
static size_t
transmit_to_client_callback (void *cls, size_t size, void *buf)
{
  struct TransportClient *client = cls;
  struct ClientMessageQueueEntry *q;
  uint16_t msize;
  size_t tsize;
  const struct GNUNET_MessageHeader *msg;
  char *cbuf;

  client->th = NULL;
  if (buf == NULL)
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Transmission to client failed, closing connection.\n");
#endif
    /* fatal error with client, free message queue! */
    while (NULL != (q = client->message_queue_head))
    {
      GNUNET_STATISTICS_update (stats,
                                gettext_noop
                                ("# bytes discarded (could not transmit to client)"),
                                ntohs (((const struct GNUNET_MessageHeader *)
                                        &q[1])->size), GNUNET_NO);
      GNUNET_CONTAINER_DLL_remove (client->message_queue_head,
                                   client->message_queue_tail, q);
      GNUNET_free (q);
    }
    client->message_count = 0;
    return 0;
  }
  cbuf = buf;
  tsize = 0;
  while (NULL != (q = client->message_queue_head))
  {
    msg = (const struct GNUNET_MessageHeader *) &q[1];
    msize = ntohs (msg->size);
    if (msize + tsize > size)
      break;
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Transmitting message of type %u to client.\n",
                ntohs (msg->type));
#endif
    GNUNET_CONTAINER_DLL_remove (client->message_queue_head,
                                 client->message_queue_tail, q);
    memcpy (&cbuf[tsize], msg, msize);
    tsize += msize;
    GNUNET_free (q);
    client->message_count--;
  }
  if (NULL != q)
  {
    GNUNET_assert (msize >= sizeof (struct GNUNET_MessageHeader));
    client->th = GNUNET_SERVER_notify_transmit_ready (client->client,
                                                      msize,
                                                      GNUNET_TIME_UNIT_FOREVER_REL,
                                                      &transmit_to_client_callback,
                                                      client);
    GNUNET_assert (client->th != NULL);
  }
  return tsize;
}


/**
 * Convert an address to a string.
 *
 * @param plugin name of the plugin responsible for the address
 * @param addr binary address
 * @param addr_len number of bytes in addr
 * @return NULL on error, otherwise address string
 */
static const char *
a2s (const char *plugin, const void *addr, uint16_t addr_len)
{
  struct TransportPlugin *p;

  if (plugin == NULL)
    return NULL;
  p = find_transport (plugin);
  if ((p == NULL) || (addr_len == 0) || (addr == NULL))
    return NULL;
  return p->api->address_to_string (NULL, addr, addr_len);
}




/**
 * Iterator to free entries in the validation_map.
 *
 * @param cls closure (unused)
 * @param key current key code
 * @param value value in the hash map (validation to abort)
 * @return GNUNET_YES (always)
 */
static int
abort_validation (void *cls, const GNUNET_HashCode * key, void *value)
{
  struct ValidationEntry *va = value;

  if (GNUNET_SCHEDULER_NO_TASK != va->timeout_task)
    GNUNET_SCHEDULER_cancel (va->timeout_task);
  GNUNET_free (va->transport_name);
  if (va->chvc != NULL)
  {
    va->chvc->ve_count--;
    if (va->chvc->ve_count == 0)
    {
      GNUNET_CONTAINER_DLL_remove (chvc_head, chvc_tail, va->chvc);
      GNUNET_free (va->chvc);
    }
    va->chvc = NULL;
  }
  GNUNET_free (va);
  return GNUNET_YES;
}


/**
 * HELLO validation cleanup task (validation failed).
 *
 * @param cls the 'struct ValidationEntry' that failed
 * @param tc scheduler context (unused)
 */
static void
timeout_hello_validation (void *cls,
                          const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct ValidationEntry *va = cls;
  struct GNUNET_PeerIdentity pid;

  va->timeout_task = GNUNET_SCHEDULER_NO_TASK;
  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# address validation timeouts"),
                            1, GNUNET_NO);
  GNUNET_CRYPTO_hash (&va->publicKey,
                      sizeof (struct
                              GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded),
                      &pid.hashPubKey);
  GNUNET_break (GNUNET_OK ==
                GNUNET_CONTAINER_multihashmap_remove (validation_map,
                                                      &pid.hashPubKey, va));
  abort_validation (NULL, NULL, va);
}



/**
 * Send the specified message to the specified client.  Since multiple
 * messages may be pending for the same client at a time, this code
 * makes sure that no message is lost.
 *
 * @param client client to transmit the message to
 * @param msg the message to send
 * @param may_drop can this message be dropped if the
 *        message queue for this client is getting far too large?
 */
static void
transmit_to_client (struct TransportClient *client,
                    const struct GNUNET_MessageHeader *msg, int may_drop)
{
  struct ClientMessageQueueEntry *q;
  uint16_t msize;

  /* Client==NULL when GNUNET_SERVER_Client disconnected and was
   * freed in client_disconnect_notification
   */
  if (client->client == NULL)
  {
    GNUNET_break (0);
    return;
  }

  if ((client->message_count >= MAX_PENDING) && (GNUNET_YES == may_drop))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                _
                ("Dropping message of type %u and size %u, have %u messages pending (%u is the soft limit)\n"),
                ntohs (msg->type),
                ntohs (msg->size), client->message_count, MAX_PENDING);
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# messages dropped due to slow client"), 1,
                              GNUNET_NO);
    return;
  }
  msize = ntohs (msg->size);
  GNUNET_assert (msize >= sizeof (struct GNUNET_MessageHeader));
  q = GNUNET_malloc (sizeof (struct ClientMessageQueueEntry) + msize);
  memcpy (&q[1], msg, msize);
  GNUNET_CONTAINER_DLL_insert_tail (client->message_queue_head,
                                    client->message_queue_tail, q);
  client->message_count++;
  if (client->th == NULL)
  {
    client->th = GNUNET_SERVER_notify_transmit_ready (client->client,
                                                      msize,
                                                      GNUNET_TIME_UNIT_FOREVER_REL,
                                                      &transmit_to_client_callback,
                                                      client);
    GNUNET_assert (client->th != NULL);
  }
}


/**
 * Transmit a 'SEND_OK' notification to the given client for the
 * given neighbour.
 *
 * @param client who to notify
 * @param n neighbour to notify about, can be NULL (on failure)
 * @param target target of the transmission
 * @param result status code for the transmission request
 */
static void
transmit_send_ok (struct TransportClient *client,
                  struct NeighbourMapEntry *n,
                  const struct GNUNET_PeerIdentity *target, int result)
{
  struct SendOkMessage send_ok_msg;

  send_ok_msg.header.size = htons (sizeof (send_ok_msg));
  send_ok_msg.header.type = htons (GNUNET_MESSAGE_TYPE_TRANSPORT_SEND_OK);
  send_ok_msg.success = htonl (result);
  if (n != NULL)
    send_ok_msg.latency = GNUNET_TIME_relative_hton (n->latency);
  else
    send_ok_msg.latency =
        GNUNET_TIME_relative_hton (GNUNET_TIME_UNIT_FOREVER_REL);
  send_ok_msg.peer = *target;
  transmit_to_client (client, &send_ok_msg.header, GNUNET_NO);
}


/**
 * Mark the given FAL entry as 'connected' (and hence preferred for
 * sending); also mark all others for the same peer as 'not connected'
 * (since only one can be preferred).
 *
 * @param fal address to set to 'connected'
 */
static void mark_address_connected (struct ForeignAddressList *fal);



/**
 * We should re-try transmitting to the given peer,
 * hopefully we've learned something in the meantime.
 */
static void
retry_transmission_task (void *cls,
                         const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct NeighbourMapEntry *n = cls;

  n->retry_task = GNUNET_SCHEDULER_NO_TASK;
  try_transmission_to_peer (n);
}


/**
 * Function called by the GNUNET_TRANSPORT_TransmitFunction
 * upon "completion" of a send request.  This tells the API
 * that it is now legal to send another message to the given
 * peer.
 *
 * @param cls closure, identifies the entry on the
 *            message queue that was transmitted and the
 *            client responsible for queuing the message
 * @param target the peer receiving the message
 * @param result GNUNET_OK on success, if the transmission
 *           failed, we should not tell the client to transmit
 *           more messages
 */
static void
transmit_send_continuation (void *cls,
                            const struct GNUNET_PeerIdentity *target,
                            int result)
{
  struct MessageQueue *mq = cls;
  struct NeighbourMapEntry *n;

  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# bytes pending with plugins"),
                            -(int64_t) mq->message_buf_size, GNUNET_NO);
  if (result == GNUNET_OK)
  {
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# bytes successfully transmitted by plugins"),
                              mq->message_buf_size, GNUNET_NO);
  }
  else
  {
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# bytes with transmission failure by plugins"),
                              mq->message_buf_size, GNUNET_NO);
  }
  if (mq->specific_address != NULL)
  {
    if (result == GNUNET_OK)
    {
      mq->specific_address->timeout =
          GNUNET_TIME_relative_to_absolute
          (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT);
      if (mq->specific_address->validated == GNUNET_YES)
        mark_address_connected (mq->specific_address);
    }
    else
    {
      if (mq->specific_address->connected == GNUNET_YES)
      {
#if DEBUG_TRANSPORT
        GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                    "Marking address `%s' as no longer connected (due to transmission problem)\n",
                    a2s (mq->specific_address->ready_list->plugin->short_name,
                         mq->specific_address->addr,
                         mq->specific_address->addrlen));
#endif
        GNUNET_STATISTICS_update (stats,
                                  gettext_noop ("# connected addresses"),
                                  -1, GNUNET_NO);
        mq->specific_address->connected = GNUNET_NO;
      }
    }
    if (!mq->internal_msg)
      mq->specific_address->in_transmit = GNUNET_NO;
  }
  n = find_neighbour (&mq->neighbour_id);
  if (mq->client != NULL)
    transmit_send_ok (mq->client, n, target, result);
  GNUNET_assert (n != NULL);
  GNUNET_CONTAINER_DLL_remove (n->cont_head, n->cont_tail, mq);
  GNUNET_free (mq);
  if (result == GNUNET_OK)
    try_transmission_to_peer (n);
  else if (GNUNET_SCHEDULER_NO_TASK == n->retry_task)
    n->retry_task = GNUNET_SCHEDULER_add_now (&retry_transmission_task, n);
}


/**
 * Check the ready list for the given neighbour and if a plugin is
 * ready for transmission (and if we have a message), do so!
 *
 * @param neighbour target peer for which to transmit
 */
static void
try_transmission_to_peer (struct NeighbourMapEntry *n)
{
  struct ReadyList *rl;
  struct MessageQueue *mq;
  struct GNUNET_TIME_Relative timeout;
  ssize_t ret;
  int force_address;

  if (n->messages_head == NULL)
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Transmission queue for `%4s' is empty\n", GNUNET_i2s (&n->id));
#endif
    return;                     /* nothing to do */
  }
  rl = NULL;
  mq = n->messages_head;
  force_address = GNUNET_YES;
  if (mq->specific_address == NULL)
  {
    /* TODO: ADD ATS */
    mq->specific_address = get_preferred_ats_address (n);
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# transport selected peer address freely"), 1,
                              GNUNET_NO);
    force_address = GNUNET_NO;
  }
  if (mq->specific_address == NULL)
  {
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# transport failed to selected peer address"),
                              1, GNUNET_NO);
    timeout = GNUNET_TIME_absolute_get_remaining (mq->timeout);
    if (timeout.rel_value == 0)
    {
#if DEBUG_TRANSPORT
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "No destination address available to transmit message of size %u to peer `%4s'\n",
                  mq->message_buf_size, GNUNET_i2s (&mq->neighbour_id));
#endif
      GNUNET_STATISTICS_update (stats,
                                gettext_noop
                                ("# bytes in message queue for other peers"),
                                -(int64_t) mq->message_buf_size, GNUNET_NO);
      GNUNET_STATISTICS_update (stats,
                                gettext_noop
                                ("# bytes discarded (no destination address available)"),
                                mq->message_buf_size, GNUNET_NO);
      if (mq->client != NULL)
        transmit_send_ok (mq->client, n, &n->id, GNUNET_NO);
      GNUNET_CONTAINER_DLL_remove (n->messages_head, n->messages_tail, mq);
      GNUNET_free (mq);
      return;                   /* nobody ready */
    }
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# message delivery deferred (no address)"), 1,
                              GNUNET_NO);
    if (n->retry_task != GNUNET_SCHEDULER_NO_TASK)
      GNUNET_SCHEDULER_cancel (n->retry_task);
    n->retry_task = GNUNET_SCHEDULER_add_delayed (timeout,
                                                  &retry_transmission_task, n);
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "No validated destination address available to transmit message of size %u to peer `%4s', will wait %llums to find an address.\n",
                mq->message_buf_size,
                GNUNET_i2s (&mq->neighbour_id), timeout.rel_value);
#endif
    /* FIXME: might want to trigger peerinfo lookup here
     * (unless that's already pending...) */
    return;
  }
  GNUNET_CONTAINER_DLL_remove (n->messages_head, n->messages_tail, mq);
  if (mq->specific_address->connected == GNUNET_NO)
    mq->specific_address->connect_attempts++;
  rl = mq->specific_address->ready_list;
  mq->plugin = rl->plugin;
  if (!mq->internal_msg)
    mq->specific_address->in_transmit = GNUNET_YES;
#if DEBUG_TRANSPORT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Sending message of size %u for `%4s' to `%s' via plugin `%s'\n",
              mq->message_buf_size,
              GNUNET_i2s (&n->id),
              (mq->specific_address->addr != NULL)
              ? a2s (mq->plugin->short_name,
                     mq->specific_address->addr,
                     mq->specific_address->addrlen)
              : "<inbound>", rl->plugin->short_name);
#endif
  GNUNET_STATISTICS_update (stats,
                            gettext_noop
                            ("# bytes in message queue for other peers"),
                            -(int64_t) mq->message_buf_size, GNUNET_NO);
  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# bytes pending with plugins"),
                            mq->message_buf_size, GNUNET_NO);

  GNUNET_CONTAINER_DLL_insert (n->cont_head, n->cont_tail, mq);

  ret = rl->plugin->api->send (rl->plugin->api->cls,
                               &mq->neighbour_id,
                               mq->message_buf,
                               mq->message_buf_size,
                               mq->priority,
                               GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT,
                               mq->specific_address->session,
                               mq->specific_address->addr,
                               mq->specific_address->addrlen,
                               force_address, &transmit_send_continuation, mq);
  if (ret == -1)
  {
    /* failure, but 'send' would not call continuation in this case,
     * so we need to do it here! */
    transmit_send_continuation (mq, &mq->neighbour_id, GNUNET_SYSERR);
  }
}


/**
 * Send the specified message to the specified peer.
 *
 * @param client source of the transmission request (can be NULL)
 * @param peer_address ForeignAddressList where we should send this message
 * @param priority how important is the message
 * @param timeout how long do we have to transmit?
 * @param message_buf message(s) to send GNUNET_MessageHeader(s)
 * @param message_buf_size total size of all messages in message_buf
 * @param is_internal is this an internal message; these are pre-pended and
 *                    also do not count for plugins being "ready" to transmit
 * @param neighbour handle to the neighbour for transmission
 */
static void
transmit_to_peer (struct TransportClient *client,
                  struct ForeignAddressList *peer_address,
                  unsigned int priority,
                  struct GNUNET_TIME_Relative timeout,
                  const char *message_buf,
                  size_t message_buf_size,
                  int is_internal, struct NeighbourMapEntry *neighbour)
{
  struct MessageQueue *mq;

#if EXTRA_CHECKS
  if (client != NULL)
  {
    /* check for duplicate submission */
    mq = neighbour->messages_head;
    while (NULL != mq)
    {
      if (mq->client == client)
      {
        /* client transmitted to same peer twice
         * before getting SEND_OK! */
        GNUNET_break (0);
        return;
      }
      mq = mq->next;
    }
  }
#endif
  GNUNET_STATISTICS_update (stats,
                            gettext_noop
                            ("# bytes in message queue for other peers"),
                            message_buf_size, GNUNET_NO);
  mq = GNUNET_malloc (sizeof (struct MessageQueue) + message_buf_size);
  mq->specific_address = peer_address;
  mq->client = client;
  /* FIXME: this memcpy can be up to 7% of our total runtime! */
  memcpy (&mq[1], message_buf, message_buf_size);
  mq->message_buf = (const char *) &mq[1];
  mq->message_buf_size = message_buf_size;
  memcpy (&mq->neighbour_id, &neighbour->id,
          sizeof (struct GNUNET_PeerIdentity));
  mq->internal_msg = is_internal;
  mq->priority = priority;
  mq->timeout = GNUNET_TIME_relative_to_absolute (timeout);
  if (is_internal)
    GNUNET_CONTAINER_DLL_insert (neighbour->messages_head,
                                 neighbour->messages_tail, mq);
  else
    GNUNET_CONTAINER_DLL_insert_after (neighbour->messages_head,
                                       neighbour->messages_tail,
                                       neighbour->messages_tail, mq);
  try_transmission_to_peer (neighbour);
}


/**
 * Send a plain PING (without address or our HELLO) to the given
 * foreign address to try to establish a connection (and validate
 * that the other peer is really who he claimed he is).
 *
 * @param n neighbour to PING
 */
static void
transmit_plain_ping (struct NeighbourMapEntry *n)
{
  struct ValidationEntry *ve;
  struct TransportPingMessage ping;
  struct ReadyList *rl;
  struct TransportPlugin *plugin;
  struct ForeignAddressList *fal;

  if (!n->public_key_valid)
  {
    /* This should not happen since the other peer
     * should send us a HELLO prior to sending his
     * PING */
    GNUNET_break_op (0);
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Could not transmit plain PING to `%s': public key not known\n",
                GNUNET_i2s (&n->id));
    return;
  }
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Looking for addresses to transmit plain PING to `%s'\n",
              GNUNET_i2s (&n->id));
  for (rl = n->plugins; rl != NULL; rl = rl->next)
  {
    plugin = rl->plugin;
    for (fal = rl->addresses; fal != NULL; fal = fal->next)
    {
      if (!fal->connected)
        continue;
      ve = GNUNET_malloc (sizeof (struct ValidationEntry));
      ve->transport_name = GNUNET_strdup (plugin->short_name);
      ve->challenge = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE,
                                                UINT_MAX);
      ve->send_time = GNUNET_TIME_absolute_get ();
      ve->session = fal->session;
      memcpy (&ve->publicKey,
              &n->publicKey,
              sizeof (struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded));
      ve->timeout_task =
          GNUNET_SCHEDULER_add_delayed (HELLO_VERIFICATION_TIMEOUT,
                                        &timeout_hello_validation, ve);
      GNUNET_CONTAINER_multihashmap_put (validation_map, &n->id.hashPubKey, ve,
                                         GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE);
      ping.header.size = htons (sizeof (struct TransportPingMessage));
      ping.header.type = htons (GNUNET_MESSAGE_TYPE_TRANSPORT_PING);
      ping.challenge = htonl (ve->challenge);
      memcpy (&ping.target, &n->id, sizeof (struct GNUNET_PeerIdentity));
      GNUNET_STATISTICS_update (stats,
                                gettext_noop
                                ("# PING without HELLO messages sent"), 1,
                                GNUNET_NO);
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Transmitting plain PING to `%s'\n",
                  GNUNET_i2s (&n->id));
      transmit_to_peer (NULL, fal, GNUNET_SCHEDULER_PRIORITY_DEFAULT,
                        HELLO_VERIFICATION_TIMEOUT, (const char *) &ping,
                        sizeof (ping), GNUNET_YES, n);
    }
  }
}


/**
 * Mark the given FAL entry as 'connected' (and hence preferred for
 * sending); also mark all others for the same peer as 'not connected'
 * (since only one can be preferred).
 *
 * @param fal address to set to 'connected'
 */
static void
mark_address_connected (struct ForeignAddressList *fal)
{
  struct ForeignAddressList *pos;
  struct ForeignAddressList *inbound;
  struct ForeignAddressList *outbound;

  GNUNET_assert (GNUNET_YES == fal->validated);
  if (fal->connected == GNUNET_YES)
    return;                     /* nothing to do */
  inbound = NULL;
  outbound = NULL;

  pos = fal->ready_list->addresses;
  while (pos != NULL)
  {
    /* Already have inbound address, and this is also an inbound address, don't switch!! */
    if ((GNUNET_YES == pos->connected) &&
        (0 == pos->addrlen) && (0 == fal->addrlen))
      return;
    if ((0 == pos->addrlen) && (GNUNET_YES == pos->connected))
      inbound = pos;
    pos = pos->next;
  }

  pos = fal->ready_list->addresses;
  while (pos != NULL)
  {
    /* Already have outbound address, and this is also an outbound address, don't switch!! */
    if ((GNUNET_YES == pos->connected) &&
        (0 < pos->addrlen) && (0 < fal->addrlen))
      return;
    if ((0 < pos->addrlen) && (GNUNET_YES == pos->connected))
      outbound = pos;
    pos = pos->next;
  }

#if DEBUG_INBOUND
  if (inbound != NULL)
    fprintf (stderr, "Peer: %s, have inbound connection.\n",
             GNUNET_i2s (&my_identity));
  if (outbound != NULL)
    fprintf (stderr, "Peer: %s, have outbound connection.\n",
             GNUNET_i2s (&my_identity));
#endif

  /* Have an inbound connection to this peer which is valid; our id is lower, ignore outbound connection! */
  if ((inbound != NULL) && (0 != fal->addrlen) && (1
                                                   ==
                                                   GNUNET_CRYPTO_hash_xorcmp
                                                   (&inbound->
                                                    ready_list->neighbour->id.
                                                    hashPubKey,
                                                    &my_identity.hashPubKey,
                                                    &null_hash)))
  {
#if DEBUG_INBOUND
    fprintf (stderr, "Peer: %s, had inbound connection, ignoring outbound!\n",
             GNUNET_i2s (&my_identity));
#endif
    return;
  }
  else if ((outbound != NULL) && (0 == fal->addrlen) && ((-1
                                                          ==
                                                          GNUNET_CRYPTO_hash_xorcmp
                                                          (&outbound->ready_list->neighbour->
                                                           id.hashPubKey,
                                                           &my_identity.hashPubKey,
                                                           &null_hash))))
  {
#if DEBUG_INBOUND
    fprintf (stderr, "Peer: %s, have outbound connection, ignoring inbound!\n",
             GNUNET_i2s (&my_identity));
#endif
    return;
  }

  pos = fal->ready_list->addresses;
  while (pos != NULL)
  {
    if ((GNUNET_YES == pos->connected) && (0 < pos->addrlen))
    {
#if DEBUG_TRANSPORT
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Marking address `%s' as no longer connected (due to connect on other address)\n",
                  a2s (pos->ready_list->plugin->short_name, pos->addr,
                       pos->addrlen));
#endif
#if DEBUG_INBOUND
      fprintf (stderr,
               "Peer: %s, setting %s connection to disconnected.\n",
               GNUNET_i2s (&my_identity),
               (0 == pos->addrlen) ? "INBOUND" : "OUTBOUND");
#endif
      pos->connected = GNUNET_NO;
      GNUNET_STATISTICS_update (stats,
                                gettext_noop ("# connected addresses"), -1,
                                GNUNET_NO);
    }
    pos = pos->next;
  }
  GNUNET_assert (GNUNET_NO == fal->connected);
  fal->connected = GNUNET_YES;
  GNUNET_STATISTICS_update (stats, gettext_noop ("# connected addresses"),
                            1, GNUNET_NO);
}


/**
 * Find an address in any of the available transports for
 * the given neighbour that would be good for message
 * transmission.  This is essentially the transport selection
 * routine.
 *
 * @param neighbour for whom to select an address
 * @return selected address, NULL if we have none
 */
struct ForeignAddressList *
find_ready_address (struct NeighbourMapEntry *neighbour)
{
  struct ReadyList *head = neighbour->plugins;
  struct ForeignAddressList *addresses;
  struct GNUNET_TIME_Absolute now = GNUNET_TIME_absolute_get ();
  struct ForeignAddressList *best_address;

  /* Hack to prefer unix domain sockets */
  struct ForeignAddressList *unix_address = NULL;

  best_address = NULL;
  while (head != NULL)
  {
    addresses = head->addresses;
    while (addresses != NULL)
    {
      if ((addresses->timeout.abs_value < now.abs_value) &&
          (addresses->connected == GNUNET_YES))
      {
#if DEBUG_TRANSPORT
        GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                    "Marking long-time inactive connection to `%4s' as down.\n",
                    GNUNET_i2s (&neighbour->id));
#endif
        GNUNET_STATISTICS_update (stats,
                                  gettext_noop ("# connected addresses"),
                                  -1, GNUNET_NO);
        addresses->connected = GNUNET_NO;
      }
      addresses = addresses->next;
    }

    addresses = head->addresses;
    while (addresses != NULL)
    {
#if DEBUG_TRANSPORT
      if (addresses->addr != NULL)
        GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                    "Have address `%s' for peer `%4s' (status: %d, %d, %d, %u, %llums, %u)\n",
                    a2s (head->plugin->short_name,
                         addresses->addr,
                         addresses->addrlen),
                    GNUNET_i2s (&neighbour->id),
                    addresses->connected,
                    addresses->in_transmit,
                    addresses->validated,
                    addresses->connect_attempts,
                    (unsigned long long) addresses->timeout.abs_value,
                    (unsigned int) addresses->distance);
#endif
      if (0 == strcmp (head->plugin->short_name, "unix"))
      {
        if ((unix_address == NULL) ||
            ((unix_address != NULL) &&
             (addresses->latency.rel_value < unix_address->latency.rel_value)))
          unix_address = addresses;
      }
      if (((best_address == NULL) ||
           (addresses->connected == GNUNET_YES) ||
           (best_address->connected == GNUNET_NO)) &&
          (addresses->in_transmit == GNUNET_NO) &&
          ((best_address == NULL) ||
           (addresses->latency.rel_value < best_address->latency.rel_value)))
        best_address = addresses;
      /* FIXME: also give lower-latency addresses that are not
       * connected a chance some times... */
      addresses = addresses->next;
    }
    if (unix_address != NULL)
      break;
    head = head->next;
  }
  if (unix_address != NULL)
  {
    best_address = unix_address;
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Found UNIX address, forced this address\n");
#endif
  }
  if (best_address != NULL)
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Best address found (`%s') has latency of %llu ms.\n",
                (best_address->addrlen > 0)
                ? a2s (best_address->ready_list->plugin->short_name,
                       best_address->addr,
                       best_address->addrlen)
                : "<inbound>", best_address->latency.rel_value);
#endif
  }
  else
  {
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# transmission attempts failed (no address)"),
                              1, GNUNET_NO);
  }

  return best_address;
}


/**
 * FIXME: document.
 */
struct GeneratorContext
{
  struct TransportPlugin *plug_pos;
  struct OwnAddressList *addr_pos;
  struct GNUNET_TIME_Absolute expiration;
};


/**
 * FIXME: document.
 */
static size_t
address_generator (void *cls, size_t max, void *buf)
{
  struct GeneratorContext *gc = cls;
  size_t ret;

  while ((gc->addr_pos == NULL) && (gc->plug_pos != NULL))
  {
    gc->plug_pos = gc->plug_pos->next;
    gc->addr_pos = (gc->plug_pos != NULL) ? gc->plug_pos->addresses : NULL;
  }
  if (NULL == gc->plug_pos)
  {

    return 0;
  }
  ret = GNUNET_HELLO_add_address (gc->plug_pos->short_name,
                                  gc->expiration,
                                  &gc->addr_pos[1],
                                  gc->addr_pos->addrlen, buf, max);
  gc->addr_pos = gc->addr_pos->next;
  return ret;
}



static int
transmit_our_hello_if_pong (void *cls, const GNUNET_HashCode * key, void *value)
{
  struct NeighbourMapEntry *npos = value;

  if (GNUNET_YES != npos->received_pong)
    return GNUNET_OK;
#if DEBUG_TRANSPORT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG | GNUNET_ERROR_TYPE_BULK,
              "Transmitting updated `%s' to neighbour `%4s'\n",
              "HELLO", GNUNET_i2s (&npos->id));
#endif
  GNUNET_STATISTICS_update (stats,
                            gettext_noop
                            ("# transmitted my HELLO to other peers"), 1,
                            GNUNET_NO);
  transmit_to_peer (NULL, NULL, 0, HELLO_ADDRESS_EXPIRATION,
                    (const char *) our_hello, GNUNET_HELLO_size (our_hello),
                    GNUNET_NO, npos);
  return GNUNET_OK;
}


/**
 * Construct our HELLO message from all of the addresses of
 * all of the transports.
 *
 * @param cls unused
 * @param tc scheduler context
 */
static void
refresh_hello_task (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct GNUNET_HELLO_Message *hello;
  struct TransportClient *cpos;
  struct GeneratorContext gc;

  hello_task = GNUNET_SCHEDULER_NO_TASK;
  gc.plug_pos = plugins;
  gc.addr_pos = plugins != NULL ? plugins->addresses : NULL;
  gc.expiration = GNUNET_TIME_relative_to_absolute (HELLO_ADDRESS_EXPIRATION);
  hello = GNUNET_HELLO_create (&my_public_key, &address_generator, &gc);
#if DEBUG_TRANSPORT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG | GNUNET_ERROR_TYPE_BULK,
              "Refreshed my `%s', new size is %d\n", "HELLO",
              GNUNET_HELLO_size (hello));
#endif
  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# refreshed my HELLO"),
                            1, GNUNET_NO);
  cpos = clients;
  while (cpos != NULL)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Transmitting my HELLO to client!\n");
    transmit_to_client (cpos,
                        (const struct GNUNET_MessageHeader *) hello, GNUNET_NO);
    cpos = cpos->next;
  }

  GNUNET_free_non_null (our_hello);
  our_hello = hello;
  GNUNET_PEERINFO_add_peer (peerinfo, our_hello);
  GNUNET_CONTAINER_multihashmap_iterate (neighbours,
                                         &transmit_our_hello_if_pong, NULL);
}


/**
 * Schedule task to refresh hello (unless such a
 * task exists already).
 */
static void
refresh_hello ()
{
#if DEBUG_TRANSPORT_HELLO
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "refresh_hello() called!\n");
#endif
  if (hello_task != GNUNET_SCHEDULER_NO_TASK)
    return;
  hello_task = GNUNET_SCHEDULER_add_now (&refresh_hello_task, NULL);
}


/**
 * Iterator over hash map entries that NULLs the session of validation
 * entries that match the given session.
 *
 * @param cls closure (the 'struct Session*' to match against)
 * @param key current key code (peer ID, not used)
 * @param value value in the hash map ('struct ValidationEntry*')
 * @return GNUNET_YES (we should continue to iterate)
 */
static int
remove_session_validations (void *cls, const GNUNET_HashCode * key, void *value)
{
  struct Session *session = cls;
  struct ValidationEntry *ve = value;

  if (session == ve->session)
    ve->session = NULL;
  return GNUNET_YES;
}


/**
 * We've been disconnected from the other peer (for some
 * connection-oriented transport).  Either quickly
 * re-establish the connection or signal the disconnect
 * to the CORE.
 *
 * Only signal CORE level disconnect if ALL addresses
 * for the peer are exhausted.
 *
 * @param p overall plugin context
 * @param nl neighbour that was disconnected
 */
static void
try_fast_reconnect (struct TransportPlugin *p, struct NeighbourMapEntry *nl)
{
  /* FIXME-MW: fast reconnect / transport switching not implemented... */
  GNUNET_log (GNUNET_ERROR_TYPE_INFO, "try_fast_reconnect not implemented!\n");
  /* Note: the idea here is to hide problems with transports (or
   * switching between plugins) from the core to eliminate the need to
   * re-negotiate session keys and the like; OTOH, we should tell core
   * quickly (much faster than timeout) `if a connection was lost and
   * could not be re-established (i.e. other peer went down or is
   * unable / refuses to communicate);
   * 
   * So we should consider:
   * 1) ideally: our own willingness / need to connect
   * 2) prior failures to connect to this peer (by plugin)
   * 3) ideally: reasons why other peer terminated (as far as knowable)
   * 
   * Most importantly, it must be POSSIBLE for another peer to terminate
   * a connection for a while (without us instantly re-establishing it).
   * Similarly, if another peer is gone we should quickly notify CORE.
   * OTOH, if there was a minor glitch (i.e. crash of gnunet-service-transport
   * on the other end), we should reconnect in such a way that BOTH CORE
   * services never even notice.
   * Furthermore, the same mechanism (or small variation) could be used
   * to switch to a better-performing plugin (ATS).
   * 
   * Finally, this needs to be tested throughly... */

  /*
   * GNUNET_NO in the call below makes transport disconnect the peer,
   * even if only a single address (out of say, six) went away.  This
   * function must be careful to ONLY disconnect if the peer is gone,
   * not just a specific address.
   *
   * More specifically, half the places it was used had it WRONG.
   */

  /* No reconnect, signal disconnect instead! */
#if DEBUG_TRANSPORT
#endif
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Disconnecting peer `%4s', %s\n", GNUNET_i2s (&nl->id),
              "try_fast_reconnect");

  GNUNET_STATISTICS_update (stats,
                            gettext_noop
                            ("# disconnects due to try_fast_reconnect"), 1,
                            GNUNET_NO);
#if DISCONNECT || 1
  disconnect_neighbour (nl, GNUNET_YES);
#endif
}


/**
 * Function that will be called whenever the plugin internally
 * cleans up a session pointer and hence the service needs to
 * discard all of those sessions as well.  Plugins that do not
 * use sessions can simply omit calling this function and always
 * use NULL wherever a session pointer is needed.
 *
 * @param cls closure
 * @param peer which peer was the session for
 * @param session which session is being destoyed
 */
static void
plugin_env_session_end (void *cls,
                        const struct GNUNET_PeerIdentity *peer,
                        struct Session *session)
{
  struct TransportPlugin *p = cls;
  struct NeighbourMapEntry *nl;
  struct ReadyList *rl;
  struct ForeignAddressList *pos;
  struct ForeignAddressList *prev;

#if DEBUG_TRANSPORT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Session ended with peer `%4s', %s\n",
              GNUNET_i2s (peer), "plugin_env_session_end");
#endif
  GNUNET_CONTAINER_multihashmap_iterate (validation_map,
                                         &remove_session_validations, session);
  nl = find_neighbour (peer);
  if (nl == NULL)
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "No neighbour record found for peer `%4s'\n",
                GNUNET_i2s (peer));
#endif
    return;                     /* was never marked as connected */
  }
  rl = nl->plugins;
  while (rl != NULL)
  {
    if (rl->plugin == p)
      break;
    rl = rl->next;
  }
  if (rl == NULL)
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Plugin was associated with peer `%4s'\n", GNUNET_i2s (peer));
#endif
    GNUNET_STATISTICS_update (stats,
                              gettext_noop ("# disconnects due to session end"),
                              1, GNUNET_NO);
    disconnect_neighbour (nl, GNUNET_YES);
    return;
  }
  prev = NULL;
  pos = rl->addresses;
  while ((pos != NULL) && (pos->session != session))
  {
    prev = pos;
    pos = pos->next;
  }
  if (pos == NULL)
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Session was never marked as ready for peer `%4s'\n",
                GNUNET_i2s (peer));
#endif

    int validations_pending =
        GNUNET_CONTAINER_multihashmap_contains (validation_map,
                                                &peer->hashPubKey);

    /* No session was marked as ready, but we have pending validations so do not disconnect from neighbour */
    if (validations_pending == GNUNET_YES)
    {
#if DEBUG_TRANSPORT
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Not disconnecting from peer `%4s due to pending address validations\n",
                  GNUNET_i2s (peer));
#endif
      return;
    }

    //FIXME: This conflicts with inbound tcp connections and tcp nat ... debugging in progress
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# disconnects due to unready session"), 1,
                              GNUNET_NO);

    disconnect_neighbour (nl, GNUNET_YES);
    return;                     /* was never marked as connected */
  }
  pos->session = NULL;
  if (GNUNET_YES == pos->connected)
  {
    pos->connected = GNUNET_NO;
    GNUNET_STATISTICS_update (stats,
                              gettext_noop ("# connected addresses"),
                              -1, GNUNET_NO);
  }
  if (GNUNET_SCHEDULER_NO_TASK != pos->revalidate_task)
  {
    GNUNET_SCHEDULER_cancel (pos->revalidate_task);
    pos->revalidate_task = GNUNET_SCHEDULER_NO_TASK;
  }

  if (pos->addrlen != 0)
  {
    if (nl->received_pong != GNUNET_NO)
    {
      GNUNET_STATISTICS_update (stats,
                                gettext_noop
                                ("# try_fast_reconnect thanks to plugin_env_session_end"),
                                1, GNUNET_NO);
      if (GNUNET_YES == pos->connected)
        try_fast_reconnect (p, nl);
    }
    else
    {
      GNUNET_STATISTICS_update (stats,
                                gettext_noop
                                ("# disconnects due to missing pong"), 1,
                                GNUNET_NO);
      /* FIXME this is never true?! See: line 2416 */
      if (GNUNET_YES == pos->connected)
        disconnect_neighbour (nl, GNUNET_YES);
    }
    return;
  }

  /* was inbound connection, free 'pos' */
  if (prev == NULL)
    rl->addresses = pos->next;
  else
    prev->next = pos->next;
  if (GNUNET_SCHEDULER_NO_TASK != pos->revalidate_task)
  {
    GNUNET_SCHEDULER_cancel (pos->revalidate_task);
    pos->revalidate_task = GNUNET_SCHEDULER_NO_TASK;
  }
  GNUNET_free_non_null (pos->ressources);
  GNUNET_free_non_null (pos->quality);
#if HAVE_LIBGLPK
  ats_modify_problem_state (ats, ATS_MODIFIED);
#endif
  if (GNUNET_YES != pos->connected)
  {
    /* nothing else to do, connection was never up... */
    GNUNET_free (pos);
    return;
  }
  pos->connected = GNUNET_NO;
  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# connected addresses"),
                            -1, GNUNET_NO);
  GNUNET_free (pos);

  if (nl->received_pong == GNUNET_NO)
  {
    GNUNET_STATISTICS_update (stats,
                              gettext_noop ("# disconnects due to NO pong"),
                              1, GNUNET_NO);
    disconnect_neighbour (nl, GNUNET_YES);
    return;                     /* nothing to do, never connected... */
  }
  /* check if we have any validated addresses left */
  pos = rl->addresses;
  while (pos != NULL)
  {
    if (GNUNET_YES == pos->validated)
    {
      GNUNET_STATISTICS_update (stats,
                                gettext_noop
                                ("# try_fast_reconnect thanks to validated_address"),
                                1, GNUNET_NO);
      try_fast_reconnect (p, nl);
      return;
    }
    pos = pos->next;
  }
  /* no valid addresses left, signal disconnect! */

#if DEBUG_TRANSPORT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Disconnecting peer `%4s', %s\n",
              GNUNET_i2s (peer), "plugin_env_session_end");
#endif
  /* FIXME: This doesn't mean there are no addresses left for this PEER,
   * it means there aren't any left for this PLUGIN/PEER combination! So
   * calling disconnect_neighbour here with GNUNET_NO forces disconnect
   * when it isn't necessary. Using GNUNET_YES at least checks to see
   * if there are any addresses that work first, so as not to overdo it.
   * --NE
   */
  GNUNET_STATISTICS_update (stats,
                            gettext_noop
                            ("# disconnects due to plugin_env_session_end"), 1,
                            GNUNET_NO);
  disconnect_neighbour (nl, GNUNET_YES);
}


/**
 * Function that must be called by each plugin to notify the
 * transport service about the addresses under which the transport
 * provided by the plugin can be reached.
 *
 * @param cls closure
 * @param add_remove GNUNET_YES to add, GNUNET_NO to remove the address
 * @param addr one of the addresses of the host, NULL for the last address
 *        the specific address format depends on the transport
 * @param addrlen length of the address
 */
static void
plugin_env_notify_address (void *cls,
                           int add_remove, const void *addr, size_t addrlen)
{
  struct TransportPlugin *p = cls;
  struct OwnAddressList *al;
  struct OwnAddressList *prev;

  GNUNET_assert (p->api != NULL);
#if DEBUG_TRANSPORT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              (add_remove == GNUNET_YES)
              ? "Adding `%s':%s to the set of our addresses\n"
              : "Removing `%s':%s from the set of our addresses\n",
              a2s (p->short_name, addr, addrlen), p->short_name);
#endif
  GNUNET_assert (addr != NULL);
  if (GNUNET_NO == add_remove)
  {
    prev = NULL;
    al = p->addresses;
    while (al != NULL)
    {
      if ((addrlen == al->addrlen) && (0 == memcmp (addr, &al[1], addrlen)))
      {
        if (prev == NULL)
          p->addresses = al->next;
        else
          prev->next = al->next;
        GNUNET_free (al);
        refresh_hello ();
        return;
      }
      prev = al;
      al = al->next;
    }
    GNUNET_break (0);
    return;
  }
  al = GNUNET_malloc (sizeof (struct OwnAddressList) + addrlen);
  al->next = p->addresses;
  p->addresses = al;
  al->addrlen = addrlen;
  memcpy (&al[1], addr, addrlen);
  refresh_hello ();
}


/**
 * Notify all of our clients about a peer connecting.
 */
static void
notify_clients_connect (const struct GNUNET_PeerIdentity *peer,
                        struct GNUNET_TIME_Relative latency, uint32_t distance)
{
  struct ConnectInfoMessage *cim;
  struct TransportClient *cpos;
  uint32_t ats_count;
  size_t size;

  if (0 == memcmp (peer, &my_identity, sizeof (struct GNUNET_PeerIdentity)))
  {
    GNUNET_break (0);
    return;
  }
#if DEBUG_TRANSPORT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Notifying clients about connection with `%s'\n",
              GNUNET_i2s (peer));
#endif
  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# peers connected"), 1, GNUNET_NO);

  ats_count = 2;
  size =
      sizeof (struct ConnectInfoMessage) +
      ats_count * sizeof (struct GNUNET_TRANSPORT_ATS_Information);
  GNUNET_assert (size < GNUNET_SERVER_MAX_MESSAGE_SIZE);
  cim = GNUNET_malloc (size);
  cim->header.size = htons (size);
  cim->header.type = htons (GNUNET_MESSAGE_TYPE_TRANSPORT_CONNECT);
  cim->ats_count = htonl (2);
  (&cim->ats)[0].type = htonl (GNUNET_TRANSPORT_ATS_QUALITY_NET_DISTANCE);
  (&cim->ats)[0].value = htonl (distance);
  (&cim->ats)[1].type = htonl (GNUNET_TRANSPORT_ATS_QUALITY_NET_DELAY);
  (&cim->ats)[1].value = htonl ((uint32_t) latency.rel_value);
  (&cim->ats)[2].type = htonl (GNUNET_TRANSPORT_ATS_ARRAY_TERMINATOR);
  (&cim->ats)[2].value = htonl (0);
  memcpy (&cim->id, peer, sizeof (struct GNUNET_PeerIdentity));

  /* notify ats about connecting peer */
  if ((ats != NULL) && (shutdown_in_progress == GNUNET_NO))
  {
#if HAVE_LIBGLPK
    ats_modify_problem_state (ats, ATS_MODIFIED);
    ats_calculate_bandwidth_distribution (ats);
#endif
  }
  cpos = clients;
  while (cpos != NULL)
  {
    transmit_to_client (cpos, &cim->header, GNUNET_NO);
    cpos = cpos->next;
  }
  GNUNET_free (cim);
}


/**
 * Notify all of our clients about a peer disconnecting.
 */
static void
notify_clients_disconnect (const struct GNUNET_PeerIdentity *peer)
{
  struct DisconnectInfoMessage dim;
  struct TransportClient *cpos;

  if (0 == memcmp (peer, &my_identity, sizeof (struct GNUNET_PeerIdentity)))
  {
    GNUNET_break (0);
    return;
  }
#if DEBUG_TRANSPORT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Notifying clients about lost connection to `%s'\n",
              GNUNET_i2s (peer));
#endif
  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# peers connected"), -1, GNUNET_NO);
  dim.header.size = htons (sizeof (struct DisconnectInfoMessage));
  dim.header.type = htons (GNUNET_MESSAGE_TYPE_TRANSPORT_DISCONNECT);
  dim.reserved = htonl (0);
  memcpy (&dim.peer, peer, sizeof (struct GNUNET_PeerIdentity));

  /* notify ats about connecting peer */
  if ((ats != NULL) && (shutdown_in_progress == GNUNET_NO))
  {
#if HAVE_LIBGLPK
    ats_modify_problem_state (ats, ATS_MODIFIED);
    ats_calculate_bandwidth_distribution (ats);
#endif
  }

  cpos = clients;
  while (cpos != NULL)
  {
    transmit_to_client (cpos, &dim.header, GNUNET_NO);
    cpos = cpos->next;
  }
}


/**
 * Find a ForeignAddressList entry for the given neighbour
 * that matches the given address and transport.
 *
 * @param neighbour which peer we care about
 * @param tname name of the transport plugin
 * @param session session to look for, NULL for 'any'; otherwise
 *        can be used for the service to "learn" this session ID
 *        if 'addr' matches
 * @param addr binary address
 * @param addrlen length of addr
 * @return NULL if no such entry exists
 */
static struct ForeignAddressList *
find_peer_address (struct NeighbourMapEntry *neighbour,
                   const char *tname,
                   struct Session *session, const char *addr, uint16_t addrlen)
{
  struct ReadyList *head;
  struct ForeignAddressList *pos;

  head = neighbour->plugins;
  while (head != NULL)
  {
    if (0 == strcmp (tname, head->plugin->short_name))
      break;
    head = head->next;
  }
  if (head == NULL)
    return NULL;
  pos = head->addresses;
  while ((pos != NULL) &&
         ((pos->addrlen != addrlen) ||
          (memcmp (pos->addr, addr, addrlen) != 0)))
  {
    if ((session != NULL) && (pos->session == session))
      return pos;
    pos = pos->next;
  }
  if ((session != NULL) && (pos != NULL))
    pos->session = session;     /* learn it! */
  return pos;
}


/**
 * Get the peer address struct for the given neighbour and
 * address.  If it doesn't yet exist, create it.
 *
 * @param neighbour which peer we care about
 * @param tname name of the transport plugin
 * @param session session of the plugin, or NULL for none
 * @param addr binary address
 * @param addrlen length of addr
 * @return NULL if we do not have a transport plugin for 'tname'
 */
static struct ForeignAddressList *
add_peer_address (struct NeighbourMapEntry *neighbour,
                  const char *tname,
                  struct Session *session, const char *addr, uint16_t addrlen)
{
  struct ReadyList *head;
  struct ForeignAddressList *ret;
  int c;

  ret = find_peer_address (neighbour, tname, session, addr, addrlen);
  if (ret != NULL)
    return ret;
  head = neighbour->plugins;

  while (head != NULL)
  {
    if (0 == strcmp (tname, head->plugin->short_name))
      break;
    head = head->next;
  }
  if (head == NULL)
    return NULL;
  ret = GNUNET_malloc (sizeof (struct ForeignAddressList) + addrlen);
  ret->session = session;
  if ((addrlen > 0) && (addr != NULL))
  {
    ret->addr = (const char *) &ret[1];
    memcpy (&ret[1], addr, addrlen);
  }
  else
  {
    ret->addr = NULL;
  }

  ret->ressources =
      GNUNET_malloc (available_ressources *
                     sizeof (struct ATS_ressource_entry));
  for (c = 0; c < available_ressources; c++)
  {
    struct ATS_ressource_entry *r = ret->ressources;

    r[c].index = c;
    r[c].atis_index = ressources[c].atis_index;
    if (0 == strcmp (neighbour->plugins->plugin->short_name, "unix"))
    {
      r[c].c = ressources[c].c_unix;
    }
    else if (0 == strcmp (neighbour->plugins->plugin->short_name, "udp"))
    {
      r[c].c = ressources[c].c_udp;
    }
    else if (0 == strcmp (neighbour->plugins->plugin->short_name, "tcp"))
    {
      r[c].c = ressources[c].c_tcp;
    }
    else if (0 == strcmp (neighbour->plugins->plugin->short_name, "http"))
    {
      r[c].c = ressources[c].c_http;
    }
    else if (0 == strcmp (neighbour->plugins->plugin->short_name, "https"))
    {
      r[c].c = ressources[c].c_https;
    }
    else if (0 == strcmp (neighbour->plugins->plugin->short_name, "wlan"))
    {
      r[c].c = ressources[c].c_wlan;
    }
    else
    {
      r[c].c = ressources[c].c_default;
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                  "Assigning default cost to peer `%s' addr plugin `%s'! This should not happen!\n",
                  GNUNET_i2s (&neighbour->id),
                  neighbour->plugins->plugin->short_name);
    }
  }

  ret->quality =
      GNUNET_malloc (available_quality_metrics *
                     sizeof (struct ATS_quality_entry));
  ret->addrlen = addrlen;
  ret->expires = GNUNET_TIME_relative_to_absolute
      (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT);
  ret->latency = GNUNET_TIME_relative_get_forever ();
  ret->distance = -1;
  ret->timeout = GNUNET_TIME_relative_to_absolute
      (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT);
  ret->ready_list = head;
  ret->next = head->addresses;
  head->addresses = ret;
  return ret;
}


/**
 * Closure for 'add_validated_address'.
 */
struct AddValidatedAddressContext
{
  /**
   * Entry that has been validated.
   */
  const struct ValidationEntry *ve;

  /**
   * Flag set after we have added the address so
   * that we terminate the iteration next time.
   */
  int done;
};


/**
 * Callback function used to fill a buffer of max bytes with a list of
 * addresses in the format used by HELLOs.  Should use
 * "GNUNET_HELLO_add_address" as a helper function.
 *
 * @param cls the 'struct AddValidatedAddressContext' with the validated address
 * @param max maximum number of bytes that can be written to buf
 * @param buf where to write the address information
 * @return number of bytes written, 0 to signal the
 *         end of the iteration.
 */
static size_t
add_validated_address (void *cls, size_t max, void *buf)
{
  struct AddValidatedAddressContext *avac = cls;
  const struct ValidationEntry *ve = avac->ve;

  if (GNUNET_YES == avac->done)
    return 0;
  avac->done = GNUNET_YES;
  return GNUNET_HELLO_add_address (ve->transport_name,
                                   GNUNET_TIME_relative_to_absolute
                                   (HELLO_ADDRESS_EXPIRATION), ve->addr,
                                   ve->addrlen, buf, max);
}



/**
 * Closure for 'check_address_exists'.
 */
struct CheckAddressExistsClosure
{
  /**
   * Address to check for.
   */
  const void *addr;

  /**
   * Name of the transport.
   */
  const char *tname;

  /**
   * Session, or NULL.
   */
  struct Session *session;

  /**
   * Set to GNUNET_YES if the address exists.
   */
  int exists;

  /**
   * Length of addr.
   */
  uint16_t addrlen;

};


/**
 * Iterator over hash map entries.  Checks if the given
 * validation entry is for the same address as what is given
 * in the closure.
 *
 * @param cls the 'struct CheckAddressExistsClosure*'
 * @param key current key code (ignored)
 * @param value value in the hash map ('struct ValidationEntry')
 * @return GNUNET_YES if we should continue to
 *         iterate (mismatch), GNUNET_NO if not (entry matched)
 */
static int
check_address_exists (void *cls, const GNUNET_HashCode * key, void *value)
{
  struct CheckAddressExistsClosure *caec = cls;
  struct ValidationEntry *ve = value;

  if ((0 == strcmp (caec->tname,
                    ve->transport_name)) &&
      (caec->addrlen == ve->addrlen) &&
      (0 == memcmp (caec->addr, ve->addr, caec->addrlen)))
  {
    caec->exists = GNUNET_YES;
    return GNUNET_NO;
  }
  if ((ve->session != NULL) && (caec->session == ve->session))
  {
    caec->exists = GNUNET_YES;
    return GNUNET_NO;
  }
  return GNUNET_YES;
}


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

#if DEBUG_TRANSPORT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG | GNUNET_ERROR_TYPE_BULK,
              "Neighbour `%4s' has timed out!\n", GNUNET_i2s (&n->id));
#endif
  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# disconnects due to timeout"),
                            1, GNUNET_NO);
  n->timeout_task = GNUNET_SCHEDULER_NO_TASK;
  disconnect_neighbour (n, GNUNET_NO);
}


/**
 * Schedule the job that will cause us to send a PING to the
 * foreign address to evaluate its validity and latency.
 *
 * @param fal address to PING
 */
static void schedule_next_ping (struct ForeignAddressList *fal);


/**
 * Add the given address to the list of foreign addresses
 * available for the given peer (check for duplicates).
 *
 * @param cls the respective 'struct NeighbourMapEntry' to update
 * @param tname name of the transport
 * @param expiration expiration time
 * @param addr the address
 * @param addrlen length of the address
 * @return GNUNET_OK (always)
 */
static int
add_to_foreign_address_list (void *cls,
                             const char *tname,
                             struct GNUNET_TIME_Absolute expiration,
                             const void *addr, uint16_t addrlen)
{
  struct NeighbourMapEntry *n = cls;
  struct ForeignAddressList *fal;
  int try;

  GNUNET_STATISTICS_update (stats,
                            gettext_noop
                            ("# valid peer addresses returned by PEERINFO"), 1,
                            GNUNET_NO);
  try = GNUNET_NO;
  fal = find_peer_address (n, tname, NULL, addr, addrlen);
  if (fal == NULL)
  {
#if DEBUG_TRANSPORT_HELLO
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Adding address `%s' (%s) for peer `%4s' due to PEERINFO data for %llums.\n",
                a2s (tname, addr, addrlen),
                tname, GNUNET_i2s (&n->id), expiration.abs_value);
#endif
    fal = add_peer_address (n, tname, NULL, addr, addrlen);
    if (fal == NULL)
    {
      GNUNET_STATISTICS_update (stats,
                                gettext_noop
                                ("# previously validated addresses lacking transport"),
                                1, GNUNET_NO);
    }
    else
    {
      fal->expires = GNUNET_TIME_absolute_max (expiration, fal->expires);
      schedule_next_ping (fal);
    }
    try = GNUNET_YES;
  }
  else
  {
    fal->expires = GNUNET_TIME_absolute_max (expiration, fal->expires);
  }
  if (fal == NULL)
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Failed to add new address for `%4s'\n", GNUNET_i2s (&n->id));
#endif
    return GNUNET_OK;
  }
  if (fal->validated == GNUNET_NO)
  {
    fal->validated = GNUNET_YES;
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# peer addresses considered valid"), 1,
                              GNUNET_NO);
  }
  if (try == GNUNET_YES)
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Have new addresses, will try to trigger transmissions.\n");
#endif
    try_transmission_to_peer (n);
  }
  return GNUNET_OK;
}


/**
 * Add addresses in validated HELLO "h" to the set of addresses
 * we have for this peer.
 *
 * @param cls closure ('struct NeighbourMapEntry*')
 * @param peer id of the peer, NULL for last call
 * @param h hello message for the peer (can be NULL)
 * @param err_msg NULL if successful, otherwise contains error message
 */
static void
add_hello_for_peer (void *cls,
                    const struct GNUNET_PeerIdentity *peer,
                    const struct GNUNET_HELLO_Message *h, const char *err_msg)
{
  struct NeighbourMapEntry *n = cls;

  if (err_msg != NULL)
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                _("Error in communication with PEERINFO service: %s\n"),
                err_msg);
#endif
    /* return; */
  }
  if (peer == NULL)
  {
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# outstanding peerinfo iterate requests"), -1,
                              GNUNET_NO);
    n->piter = NULL;
    return;
  }
  if (h == NULL)
    return;                     /* no HELLO available */
#if DEBUG_TRANSPORT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Peerinfo had `%s' message for peer `%4s', adding existing addresses.\n",
              "HELLO", GNUNET_i2s (peer));
#endif
  if (GNUNET_YES != n->public_key_valid)
  {
    GNUNET_HELLO_get_key (h, &n->publicKey);
    n->public_key_valid = GNUNET_YES;
  }
  GNUNET_HELLO_iterate_addresses (h,
                                  GNUNET_NO, &add_to_foreign_address_list, n);
}


/**
 * Create a fresh entry in our neighbour list for the given peer.
 * Will try to transmit our current HELLO to the new neighbour.
 * Do not call this function directly, use 'setup_peer_check_blacklist.
 *
 * @param peer the peer for which we create the entry
 * @param do_hello should we schedule transmitting a HELLO
 * @return the new neighbour list entry
 */
static struct NeighbourMapEntry *
setup_new_neighbour (const struct GNUNET_PeerIdentity *peer, int do_hello)
{
  struct NeighbourMapEntry *n;
  struct TransportPlugin *tp;
  struct ReadyList *rl;

  GNUNET_assert (0 != memcmp (peer,
                              &my_identity,
                              sizeof (struct GNUNET_PeerIdentity)));
#if DEBUG_TRANSPORT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Setting up state for neighbour `%4s'\n", GNUNET_i2s (peer));
#endif
  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# active neighbours"), 1, GNUNET_NO);
  n = GNUNET_malloc (sizeof (struct NeighbourMapEntry));
  n->id = *peer;
  n->peer_timeout =
      GNUNET_TIME_relative_to_absolute
      (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT);
  GNUNET_BANDWIDTH_tracker_init (&n->in_tracker,
                                 GNUNET_CONSTANTS_DEFAULT_BW_IN_OUT,
                                 MAX_BANDWIDTH_CARRY_S);
  tp = plugins;
  while (tp != NULL)
  {
    if ((tp->api->send != NULL) && (!is_blacklisted (peer, tp)))
    {
      rl = GNUNET_malloc (sizeof (struct ReadyList));
      rl->neighbour = n;
      rl->next = n->plugins;
      n->plugins = rl;
      rl->plugin = tp;
      rl->addresses = NULL;
    }
    tp = tp->next;
  }
  n->latency = GNUNET_TIME_UNIT_FOREVER_REL;
  n->distance = -1;
  n->timeout_task =
      GNUNET_SCHEDULER_add_delayed (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT,
                                    &neighbour_timeout_task, n);
  GNUNET_CONTAINER_multihashmap_put (neighbours, &n->id.hashPubKey, n,
                                     GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY);
  if (do_hello)
  {
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# peerinfo new neighbor iterate requests"), 1,
                              GNUNET_NO);
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# outstanding peerinfo iterate requests"), 1,
                              GNUNET_NO);
    n->piter =
        GNUNET_PEERINFO_iterate (peerinfo, peer, GNUNET_TIME_UNIT_FOREVER_REL,
                                 &add_hello_for_peer, n);

    GNUNET_STATISTICS_update (stats,
                              gettext_noop ("# HELLO's sent to new neighbors"),
                              1, GNUNET_NO);
    if (NULL != our_hello)
      transmit_to_peer (NULL, NULL, 0,
                        HELLO_ADDRESS_EXPIRATION,
                        (const char *) our_hello, GNUNET_HELLO_size (our_hello),
                        GNUNET_NO, n);
  }
  return n;
}


/**
 * Function called after we have checked if communicating
 * with a given peer is acceptable.
 *
 * @param cls closure
 * @param n NULL if communication is not acceptable
 */
typedef void (*SetupContinuation) (void *cls, struct NeighbourMapEntry * n);


/**
 * Information kept for each client registered to perform
 * blacklisting.
 */
struct Blacklisters
{
  /**
   * This is a linked list.
   */
  struct Blacklisters *next;

  /**
   * This is a linked list.
   */
  struct Blacklisters *prev;

  /**
   * Client responsible for this entry.
   */
  struct GNUNET_SERVER_Client *client;

  /**
   * Blacklist check that we're currently performing.
   */
  struct BlacklistCheck *bc;

};


/**
 * Head of DLL of blacklisting clients.
 */
static struct Blacklisters *bl_head;

/**
 * Tail of DLL of blacklisting clients.
 */
static struct Blacklisters *bl_tail;


/**
 * Context we use when performing a blacklist check.
 */
struct BlacklistCheck
{

  /**
   * This is a linked list.
   */
  struct BlacklistCheck *next;

  /**
   * This is a linked list.
   */
  struct BlacklistCheck *prev;

  /**
   * Peer being checked.
   */
  struct GNUNET_PeerIdentity peer;

  /**
   * Option for setup neighbour afterwards.
   */
  int do_hello;

  /**
   * Continuation to call with the result.
   */
  SetupContinuation cont;

  /**
   * Closure for cont.
   */
  void *cont_cls;

  /**
   * Current transmission request handle for this client, or NULL if no
   * request is pending.
   */
  struct GNUNET_CONNECTION_TransmitHandle *th;

  /**
   * Our current position in the blacklisters list.
   */
  struct Blacklisters *bl_pos;

  /**
   * Current task performing the check.
   */
  GNUNET_SCHEDULER_TaskIdentifier task;

};

/**
 * Head of DLL of active blacklisting queries.
 */
static struct BlacklistCheck *bc_head;

/**
 * Tail of DLL of active blacklisting queries.
 */
static struct BlacklistCheck *bc_tail;


/**
 * Perform next action in the blacklist check.
 *
 * @param cls the 'struct BlacklistCheck*'
 * @param tc unused
 */
static void
do_blacklist_check (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc);

/**
 * Transmit blacklist query to the client.
 *
 * @param cls the 'struct BlacklistCheck'
 * @param size number of bytes allowed
 * @param buf where to copy the message
 * @return number of bytes copied to buf
 */
static size_t
transmit_blacklist_message (void *cls, size_t size, void *buf)
{
  struct BlacklistCheck *bc = cls;
  struct Blacklisters *bl;
  struct BlacklistMessage bm;

  bc->th = NULL;
  if (size == 0)
  {
    GNUNET_assert (bc->task == GNUNET_SCHEDULER_NO_TASK);
    bc->task = GNUNET_SCHEDULER_add_now (&do_blacklist_check, bc);
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                "Failed to send blacklist test for peer `%s' to client\n",
                GNUNET_i2s (&bc->peer));
    return 0;
  }
#if DEBUG_TRANSPORT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Sending blacklist test for peer `%s' to client\n",
              GNUNET_i2s (&bc->peer));
#endif
  bl = bc->bl_pos;
  bm.header.size = htons (sizeof (struct BlacklistMessage));
  bm.header.type = htons (GNUNET_MESSAGE_TYPE_TRANSPORT_BLACKLIST_QUERY);
  bm.is_allowed = htonl (0);
  bm.peer = bc->peer;
  memcpy (buf, &bm, sizeof (bm));
  GNUNET_SERVER_receive_done (bl->client, GNUNET_OK);
  return sizeof (bm);
}


/**
 * Perform next action in the blacklist check.
 *
 * @param cls the 'struct BlacklistCheck*'
 * @param tc unused
 */
static void
do_blacklist_check (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct BlacklistCheck *bc = cls;
  struct Blacklisters *bl;

  bc->task = GNUNET_SCHEDULER_NO_TASK;
  bl = bc->bl_pos;
  if (bl == NULL)
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "No blacklist clients active, will now setup neighbour record for peer `%s'\n",
                GNUNET_i2s (&bc->peer));
#endif
    bc->cont (bc->cont_cls, setup_new_neighbour (&bc->peer, bc->do_hello));
    GNUNET_free (bc);
    return;
  }
  if (bl->bc == NULL)
  {
    bl->bc = bc;
    bc->th = GNUNET_SERVER_notify_transmit_ready (bl->client,
                                                  sizeof (struct
                                                          BlacklistMessage),
                                                  GNUNET_TIME_UNIT_FOREVER_REL,
                                                  &transmit_blacklist_message,
                                                  bc);
  }
}


/**
 * Obtain a 'struct NeighbourMapEntry' for the given peer.  If such an entry
 * does not yet exist, check the blacklist.  If the blacklist says creating
 * one is acceptable, create one and call the continuation; otherwise
 * call the continuation with NULL.
 *
 * @param peer peer to setup or look up a struct NeighbourMapEntry for
 * @param do_hello should we also schedule sending our HELLO to the peer
 *        if this is a new record
 * @param cont function to call with the 'struct NeigbhbourList*'
 * @param cont_cls closure for cont
 */
static void
setup_peer_check_blacklist (const struct GNUNET_PeerIdentity *peer,
                            int do_hello,
                            SetupContinuation cont, void *cont_cls)
{
  struct NeighbourMapEntry *n;
  struct BlacklistCheck *bc;

  n = find_neighbour (peer);
  if (n != NULL)
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Neighbour record exists for peer `%s'\n", GNUNET_i2s (peer));
#endif
    if (cont != NULL)
      cont (cont_cls, n);
    return;
  }
  if (bl_head == NULL)
  {
    if (cont != NULL)
      cont (cont_cls, setup_new_neighbour (peer, do_hello));
    else
      setup_new_neighbour (peer, do_hello);
    return;
  }
  bc = GNUNET_malloc (sizeof (struct BlacklistCheck));
  GNUNET_CONTAINER_DLL_insert (bc_head, bc_tail, bc);
  bc->peer = *peer;
  bc->do_hello = do_hello;
  bc->cont = cont;
  bc->cont_cls = cont_cls;
  bc->bl_pos = bl_head;
  bc->task = GNUNET_SCHEDULER_add_now (&do_blacklist_check, bc);
}


/**
 * Function called with the result of querying a new blacklister about
 * it being allowed (or not) to continue to talk to an existing neighbour.
 *
 * @param cls the original 'struct NeighbourMapEntry'
 * @param n NULL if we need to disconnect
 */
static void
confirm_or_drop_neighbour (void *cls, struct NeighbourMapEntry *n)
{
  struct NeighbourMapEntry *orig = cls;

  if (n == NULL)
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Disconnecting peer `%4s', %s\n", GNUNET_i2s (&orig->id),
                "confirm_or_drop_neighboUr");
#endif
    GNUNET_STATISTICS_update (stats,
                              gettext_noop ("# disconnects due to blacklist"),
                              1, GNUNET_NO);
    disconnect_neighbour (orig, GNUNET_NO);
  }
}


struct TestConnectionContext
{
  int first;

  struct Blacklisters *bl;
};


static int
test_connection_ok (void *cls, const GNUNET_HashCode * key, void *value)
{
  struct TestConnectionContext *tcc = cls;
  struct NeighbourMapEntry *n = value;
  struct BlacklistCheck *bc;


  bc = GNUNET_malloc (sizeof (struct BlacklistCheck));
  GNUNET_CONTAINER_DLL_insert (bc_head, bc_tail, bc);
  bc->peer = n->id;
  bc->do_hello = GNUNET_NO;
  bc->cont = &confirm_or_drop_neighbour;
  bc->cont_cls = n;
  bc->bl_pos = tcc->bl;
  if (GNUNET_YES == tcc->first)
  {
    /* all would wait for the same client, no need to
     * create more than just the first task right now */
    bc->task = GNUNET_SCHEDULER_add_now (&do_blacklist_check, bc);
    tcc->first = GNUNET_NO;
  }
  return GNUNET_OK;
}


/**
 * Handle a request to start a blacklist.
 *
 * @param cls closure (always NULL)
 * @param client identification of the client
 * @param message the actual message
 */
static void
handle_blacklist_init (void *cls,
                       struct GNUNET_SERVER_Client *client,
                       const struct GNUNET_MessageHeader *message)
{
  struct Blacklisters *bl;
  struct TestConnectionContext tcc;

  bl = bl_head;
  while (bl != NULL)
  {
    if (bl->client == client)
    {
      GNUNET_break (0);
      GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
      return;
    }
    bl = bl->next;
  }
  bl = GNUNET_malloc (sizeof (struct Blacklisters));
  bl->client = client;
  GNUNET_SERVER_client_keep (client);
  GNUNET_CONTAINER_DLL_insert_after (bl_head, bl_tail, bl_tail, bl);
  /* confirm that all existing connections are OK! */
  tcc.bl = bl;
  tcc.first = GNUNET_YES;
  GNUNET_CONTAINER_multihashmap_iterate (neighbours, &test_connection_ok, &tcc);
}


/**
 * Handle a request to blacklist a peer.
 *
 * @param cls closure (always NULL)
 * @param client identification of the client
 * @param message the actual message
 */
static void
handle_blacklist_reply (void *cls,
                        struct GNUNET_SERVER_Client *client,
                        const struct GNUNET_MessageHeader *message)
{
  const struct BlacklistMessage *msg =
      (const struct BlacklistMessage *) message;
  struct Blacklisters *bl;
  struct BlacklistCheck *bc;

  bl = bl_head;
  while ((bl != NULL) && (bl->client != client))
    bl = bl->next;
  if (bl == NULL)
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Blacklist client disconnected\n");
#endif
    /* FIXME: other error handling here!? */
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  bc = bl->bc;
  bl->bc = NULL;
  if (ntohl (msg->is_allowed) == GNUNET_SYSERR)
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Blacklist check failed, peer not allowed\n");
#endif
    bc->cont (bc->cont_cls, NULL);
    GNUNET_CONTAINER_DLL_remove (bc_head, bc_tail, bc);
    GNUNET_free (bc);
  }
  else
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Blacklist check succeeded, continuing with checks\n");
#endif
    bc->bl_pos = bc->bl_pos->next;
    bc->task = GNUNET_SCHEDULER_add_now (&do_blacklist_check, bc);
  }
  /* check if any other bc's are waiting for this blacklister */
  bc = bc_head;
  while (bc != NULL)
  {
    if ((bc->bl_pos == bl) && (GNUNET_SCHEDULER_NO_TASK == bc->task))
      bc->task = GNUNET_SCHEDULER_add_now (&do_blacklist_check, bc);
    bc = bc->next;
  }
}


/**
 * Send periodic PING messages to a given foreign address.
 *
 * @param cls our 'struct PeriodicValidationContext*'
 * @param tc task context
 */
static void
send_periodic_ping (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct ForeignAddressList *peer_address = cls;
  struct TransportPlugin *tp;
  struct ValidationEntry *va;
  struct NeighbourMapEntry *neighbour;
  struct TransportPingMessage ping;
  struct CheckAddressExistsClosure caec;
  char *message_buf;
  uint16_t hello_size;
  size_t slen;
  size_t tsize;

  peer_address->revalidate_task = GNUNET_SCHEDULER_NO_TASK;
  if ((tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN) != 0)
    return;
  GNUNET_assert (peer_address != NULL);
  tp = peer_address->ready_list->plugin;
  neighbour = peer_address->ready_list->neighbour;
  if (GNUNET_YES != neighbour->public_key_valid)
  {
    /* no public key yet, try again later */
    schedule_next_ping (peer_address);
    return;
  }
  caec.addr = peer_address->addr;
  caec.addrlen = peer_address->addrlen;
  caec.tname = tp->short_name;
  caec.session = peer_address->session;
  caec.exists = GNUNET_NO;

  GNUNET_CONTAINER_multihashmap_iterate (validation_map,
                                         &check_address_exists, &caec);
  if (caec.exists == GNUNET_YES)
  {
    /* During validation attempts we will likely trigger the other
     * peer trying to validate our address which in turn will cause
     * it to send us its HELLO, so we expect to hit this case rather
     * frequently.  Only print something if we are very verbose. */
#if DEBUG_TRANSPORT > 1
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Some validation of address `%s' via `%s' for peer `%4s' already in progress.\n",
                (peer_address->addr != NULL)
                ? a2s (tp->short_name,
                       peer_address->addr,
                       peer_address->addrlen)
                : "<inbound>", tp->short_name, GNUNET_i2s (&neighbour->id));
#endif
    schedule_next_ping (peer_address);
    return;
  }
  va = GNUNET_malloc (sizeof (struct ValidationEntry) + peer_address->addrlen);
  va->transport_name = GNUNET_strdup (tp->short_name);
  va->challenge = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE,
                                            UINT_MAX);
  va->send_time = GNUNET_TIME_absolute_get ();
  va->session = peer_address->session;
  if (peer_address->addr != NULL)
  {
    va->addr = (const void *) &va[1];
    memcpy (&va[1], peer_address->addr, peer_address->addrlen);
    va->addrlen = peer_address->addrlen;
  }
  memcpy (&va->publicKey,
          &neighbour->publicKey,
          sizeof (struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded));

  va->timeout_task = GNUNET_SCHEDULER_add_delayed (HELLO_VERIFICATION_TIMEOUT,
                                                   &timeout_hello_validation,
                                                   va);
  GNUNET_CONTAINER_multihashmap_put (validation_map,
                                     &neighbour->id.hashPubKey,
                                     va,
                                     GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE);

  if (peer_address->validated != GNUNET_YES)
    hello_size = GNUNET_HELLO_size (our_hello);
  else
    hello_size = 0;

  tsize = sizeof (struct TransportPingMessage) + hello_size;

  if (peer_address->addr != NULL)
  {
    slen = strlen (tp->short_name) + 1;
    tsize += slen + peer_address->addrlen;
  }
  else
  {
    slen = 0;                   /* make gcc happy */
  }
  message_buf = GNUNET_malloc (tsize);
  ping.header.type = htons (GNUNET_MESSAGE_TYPE_TRANSPORT_PING);
  ping.challenge = htonl (va->challenge);
  memcpy (&ping.target, &neighbour->id, sizeof (struct GNUNET_PeerIdentity));
  if (peer_address->validated != GNUNET_YES)
  {
    memcpy (message_buf, our_hello, hello_size);
  }

  if (peer_address->addr != NULL)
  {
    ping.header.size = htons (sizeof (struct TransportPingMessage) +
                              peer_address->addrlen + slen);
    memcpy (&message_buf[hello_size + sizeof (struct TransportPingMessage)],
            tp->short_name, slen);
    memcpy (&message_buf
            [hello_size + sizeof (struct TransportPingMessage) + slen],
            peer_address->addr, peer_address->addrlen);
  }
  else
  {
    ping.header.size = htons (sizeof (struct TransportPingMessage));
  }

  memcpy (&message_buf[hello_size],
          &ping, sizeof (struct TransportPingMessage));

#if DEBUG_TRANSPORT_REVALIDATION
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Performing re-validation of address `%s' via `%s' for peer `%4s' sending `%s' (%u bytes) and `%s'\n",
              (peer_address->addr != NULL)
              ? a2s (peer_address->plugin->short_name,
                     peer_address->addr,
                     peer_address->addrlen)
              : "<inbound>",
              tp->short_name,
              GNUNET_i2s (&neighbour->id), "HELLO", hello_size, "PING");
#endif
  if (peer_address->validated != GNUNET_YES)
    GNUNET_STATISTICS_update (stats,
                              gettext_noop ("# PING with HELLO messages sent"),
                              1, GNUNET_NO);
  else
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# PING without HELLO messages sent"), 1,
                              GNUNET_NO);
  GNUNET_STATISTICS_update (stats,
                            gettext_noop
                            ("# PING messages sent for re-validation"), 1,
                            GNUNET_NO);
  transmit_to_peer (NULL, peer_address, GNUNET_SCHEDULER_PRIORITY_DEFAULT,
                    HELLO_VERIFICATION_TIMEOUT, message_buf, tsize, GNUNET_YES,
                    neighbour);
  GNUNET_free (message_buf);
  schedule_next_ping (peer_address);
}


/**
 * Schedule the job that will cause us to send a PING to the
 * foreign address to evaluate its validity and latency.
 *
 * @param fal address to PING
 */
static void
schedule_next_ping (struct ForeignAddressList *fal)
{
  struct GNUNET_TIME_Relative delay;

  if (fal->revalidate_task != GNUNET_SCHEDULER_NO_TASK)
  {
    GNUNET_SCHEDULER_cancel (fal->revalidate_task);
    fal->revalidate_task = GNUNET_SCHEDULER_NO_TASK;
  }
  delay = GNUNET_TIME_absolute_get_remaining (fal->expires);
  delay.rel_value /= 2;         /* do before expiration */
  delay = GNUNET_TIME_relative_min (delay, LATENCY_EVALUATION_MAX_DELAY);
  if (GNUNET_YES != fal->estimated)
  {
    delay = GNUNET_TIME_UNIT_ZERO;
    fal->estimated = GNUNET_YES;
  }

  if (GNUNET_YES == fal->connected)
  {
    delay = GNUNET_TIME_relative_min (delay,
                                      CONNECTED_LATENCY_EVALUATION_MAX_DELAY);
  }
  /* FIXME: also adjust delay based on how close the last
   * observed latency is to the latency of the best alternative */
  /* bound how fast we can go */
  delay = GNUNET_TIME_relative_max (delay, GNUNET_TIME_UNIT_SECONDS);
  /* randomize a bit (to avoid doing all at the same time) */
  delay.rel_value +=
      GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, 1000);

  GNUNET_assert (fal->revalidate_task == GNUNET_SCHEDULER_NO_TASK);
  fal->revalidate_task = GNUNET_SCHEDULER_add_delayed (delay,
                                                       &send_periodic_ping,
                                                       fal);
}




/**
 * Function that will be called if we receive some payload
 * from another peer.
 *
 * @param message the payload
 * @param n peer who claimed to be the sender
 */
static void
handle_payload_message (const struct GNUNET_MessageHeader *message,
                        struct NeighbourMapEntry *n)
{
  struct InboundMessage *im;
  struct TransportClient *cpos;
  uint16_t msize;

  msize = ntohs (message->size);
  if (n->received_pong == GNUNET_NO)
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Received message of type %u and size %u from `%4s', but no pong yet!\n",
                ntohs (message->type),
                ntohs (message->size), GNUNET_i2s (&n->id));
#endif
    GNUNET_free_non_null (n->pre_connect_message_buffer);
    n->pre_connect_message_buffer = GNUNET_malloc (msize);
    memcpy (n->pre_connect_message_buffer, message, msize);
    return;
  }

#if DEBUG_TRANSPORT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Received message of type %u and size %u from `%4s', sending to all clients.\n",
              ntohs (message->type),
              ntohs (message->size), GNUNET_i2s (&n->id));
#endif
  if (GNUNET_YES == GNUNET_BANDWIDTH_tracker_consume (&n->in_tracker,
                                                      (ssize_t) msize))
  {
    n->quota_violation_count++;
#if DEBUG_TRANSPORT
    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);
#endif
    /* 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--;
    }
  }
  GNUNET_STATISTICS_update (stats,
                            gettext_noop
                            ("# payload received from other peers"), msize,
                            GNUNET_NO);
  /* transmit message to all clients */
  uint32_t ats_count = 2;
  size_t size =
      sizeof (struct InboundMessage) +
      ats_count * sizeof (struct GNUNET_TRANSPORT_ATS_Information) + msize;
  if (size > GNUNET_SERVER_MAX_MESSAGE_SIZE)
    GNUNET_break (0);

  im = GNUNET_malloc (size);
  im->header.size = htons (size);
  im->header.type = htons (GNUNET_MESSAGE_TYPE_TRANSPORT_RECV);
  im->peer = n->id;
  im->ats_count = htonl (ats_count);
  /* Setting ATS data */
  (&(im->ats))[0].type = htonl (GNUNET_TRANSPORT_ATS_QUALITY_NET_DISTANCE);
  (&(im->ats))[0].value = htonl (n->distance);
  (&(im->ats))[1].type = htonl (GNUNET_TRANSPORT_ATS_QUALITY_NET_DELAY);
  (&(im->ats))[1].value = htonl ((uint32_t) n->latency.rel_value);
  (&(im->ats))[ats_count].type = htonl (GNUNET_TRANSPORT_ATS_ARRAY_TERMINATOR);
  (&(im->ats))[ats_count].value = htonl (0);

  memcpy (&((&(im->ats))[ats_count + 1]), message, msize);
  cpos = clients;
  while (cpos != NULL)
  {
    transmit_to_client (cpos, &im->header, GNUNET_YES);
    cpos = cpos->next;
  }
  GNUNET_free (im);
}


/**
 * Iterator over hash map entries.  Checks if the given validation
 * entry is for the same challenge as what is given in the PONG.
 *
 * @param cls the 'struct TransportPongMessage*'
 * @param key peer identity
 * @param value value in the hash map ('struct ValidationEntry')
 * @return GNUNET_YES if we should continue to
 *         iterate (mismatch), GNUNET_NO if not (entry matched)
 */
static int
check_pending_validation (void *cls, const GNUNET_HashCode * key, void *value)
{
  const struct TransportPongMessage *pong = cls;
  struct ValidationEntry *ve = value;
  struct AddValidatedAddressContext avac;
  unsigned int challenge = ntohl (pong->challenge);
  struct GNUNET_HELLO_Message *hello;
  struct GNUNET_PeerIdentity target;
  struct NeighbourMapEntry *n;
  struct ForeignAddressList *fal;
  struct OwnAddressList *oal;
  struct TransportPlugin *tp;
  struct GNUNET_MessageHeader *prem;
  uint16_t ps;
  const char *addr;
  size_t slen;
  size_t alen;

  ps = ntohs (pong->header.size);
  if (ps < sizeof (struct TransportPongMessage))
  {
    GNUNET_break_op (0);
    return GNUNET_NO;
  }
  addr = (const char *) &pong[1];
  slen = strlen (ve->transport_name) + 1;
  if ((ps - sizeof (struct TransportPongMessage) < slen) ||
      (ve->challenge != challenge) ||
      (addr[slen - 1] != '\0') ||
      (0 != strcmp (addr, ve->transport_name)) ||
      (ntohl (pong->purpose.size)
       != sizeof (struct GNUNET_CRYPTO_RsaSignaturePurpose) +
       sizeof (uint32_t) +
       sizeof (struct GNUNET_TIME_AbsoluteNBO) +
       sizeof (struct GNUNET_PeerIdentity) + ps -
       sizeof (struct TransportPongMessage)))
  {
    return GNUNET_YES;
  }

  alen = ps - sizeof (struct TransportPongMessage) - slen;
  switch (ntohl (pong->purpose.purpose))
  {
  case GNUNET_SIGNATURE_PURPOSE_TRANSPORT_PONG_OWN:
    if ((ve->addrlen + slen != ntohl (pong->addrlen)) ||
        (0 != memcmp (&addr[slen], ve->addr, ve->addrlen)))
    {
      return GNUNET_YES;        /* different entry, keep trying! */
    }
    if (0 != memcmp (&pong->pid, key, sizeof (struct GNUNET_PeerIdentity)))
    {
      GNUNET_break_op (0);
      return GNUNET_NO;
    }
    if (GNUNET_OK !=
        GNUNET_CRYPTO_rsa_verify (GNUNET_SIGNATURE_PURPOSE_TRANSPORT_PONG_OWN,
                                  &pong->purpose,
                                  &pong->signature, &ve->publicKey))
    {
      GNUNET_break_op (0);
      return GNUNET_NO;
    }

#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Confirmed validity of address, peer `%4s' has address `%s' (%s).\n",
                GNUNET_h2s (key),
                a2s (ve->transport_name,
                     (const struct sockaddr *) ve->addr,
                     ve->addrlen), ve->transport_name);
#endif
    break;
  case GNUNET_SIGNATURE_PURPOSE_TRANSPORT_PONG_USING:
    if (0 != memcmp (&pong->pid,
                     &my_identity, sizeof (struct GNUNET_PeerIdentity)))
    {
      char *peer;

      GNUNET_asprintf (&peer, "%s", GNUNET_i2s (&pong->pid));
#if DEBUG_TRANSPORT
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Received PONG for different identity: I am `%s', PONG identity: `%s'\n",
                  GNUNET_i2s (&my_identity), peer);
#endif
      GNUNET_free (peer);
      return GNUNET_NO;
    }
    if (ve->addrlen != 0)
    {
      /* must have been for a different validation entry */
      return GNUNET_YES;
    }
    tp = find_transport (ve->transport_name);
    if (tp == NULL)
    {
      GNUNET_break (0);
      return GNUNET_YES;
    }
    oal = tp->addresses;
    while (NULL != oal)
    {
      if ((oal->addrlen == alen) && (0 == memcmp (&oal[1], &addr[slen], alen)))
        break;
      oal = oal->next;
    }
    if (oal == NULL)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                  _
                  ("Not accepting PONG from `%s' with address `%s' since I cannot confirm using this address.\n"),
                  GNUNET_i2s (&pong->pid), a2s (ve->transport_name, &addr[slen],
                                                alen));
      /* FIXME: since the sender of the PONG currently uses the
       * wrong address (see FIMXE there!), we cannot run a 
       * proper check here... */
#if FIXME_URGENT
      return GNUNET_NO;
#endif
    }
    if (GNUNET_OK !=
        GNUNET_CRYPTO_rsa_verify (GNUNET_SIGNATURE_PURPOSE_TRANSPORT_PONG_USING,
                                  &pong->purpose,
                                  &pong->signature, &ve->publicKey))
    {
      GNUNET_break_op (0);
      return GNUNET_NO;
    }

#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Confirmed that peer `%4s' is talking to us using address `%s' (%s) for us.\n",
                GNUNET_h2s (key),
                a2s (ve->transport_name,
                     &addr[slen], alen), ve->transport_name);
#endif
    break;
  default:
    GNUNET_break_op (0);
    return GNUNET_NO;
  }
  if (GNUNET_TIME_absolute_get_remaining
      (GNUNET_TIME_absolute_ntoh (pong->expiration)).rel_value == 0)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                _("Received expired signature.  Check system time.\n"));
    return GNUNET_NO;
  }
  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# address validation successes"),
                            1, GNUNET_NO);
  /* create the updated HELLO */
  GNUNET_CRYPTO_hash (&ve->publicKey,
                      sizeof (struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded),
                      &target.hashPubKey);
  if (ve->addr != NULL)
  {
    avac.done = GNUNET_NO;
    avac.ve = ve;
    hello = GNUNET_HELLO_create (&ve->publicKey, &add_validated_address, &avac);
    GNUNET_PEERINFO_add_peer (peerinfo, hello);
    GNUNET_free (hello);
  }
  n = find_neighbour (&target);
  if (n != NULL)
  {
    n->publicKey = ve->publicKey;
    n->public_key_valid = GNUNET_YES;
    fal = add_peer_address (n,
                            ve->transport_name,
                            ve->session, ve->addr, ve->addrlen);
    GNUNET_assert (fal != NULL);
    fal->expires = GNUNET_TIME_relative_to_absolute (HELLO_ADDRESS_EXPIRATION);
    fal->validated = GNUNET_YES;
    mark_address_connected (fal);
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# peer addresses considered valid"), 1,
                              GNUNET_NO);
    fal->latency = GNUNET_TIME_absolute_get_duration (ve->send_time);
    update_addr_value (fal,
                       GNUNET_TIME_absolute_get_duration (ve->
                                                          send_time).rel_value,
                       GNUNET_TRANSPORT_ATS_QUALITY_NET_DELAY);

    schedule_next_ping (fal);
    if (n->latency.rel_value == GNUNET_TIME_UNIT_FOREVER_REL.rel_value)
      n->latency = fal->latency;
    else
      n->latency.rel_value =
          (fal->latency.rel_value + n->latency.rel_value) / 2;

    n->distance = fal->distance;
    if (GNUNET_NO == n->received_pong)
    {
      n->received_pong = GNUNET_YES;
      notify_clients_connect (&target, n->latency, n->distance);
      if (NULL != (prem = n->pre_connect_message_buffer))
      {
        n->pre_connect_message_buffer = NULL;
        handle_payload_message (prem, n);
        GNUNET_free (prem);
      }
    }
    if (n->retry_task != GNUNET_SCHEDULER_NO_TASK)
    {
      GNUNET_SCHEDULER_cancel (n->retry_task);
      n->retry_task = GNUNET_SCHEDULER_NO_TASK;
      try_transmission_to_peer (n);
    }
  }

  /* clean up validation entry */
  GNUNET_assert (GNUNET_YES ==
                 GNUNET_CONTAINER_multihashmap_remove (validation_map,
                                                       key, ve));
  abort_validation (NULL, NULL, ve);
  return GNUNET_NO;
}


/**
 * Function that will be called if we receive a validation
 * of an address challenge that we transmitted to another
 * peer.  Note that the validation should only be considered
 * acceptable if the challenge matches AND if the sender
 * address is at least a plausible address for this peer
 * (otherwise we may be seeing a MiM attack).
 *
 * @param cls closure
 * @param message the pong message
 * @param peer who responded to our challenge
 * @param sender_address string describing our sender address (as observed
 *         by the other peer in binary format)
 * @param sender_address_len number of bytes in 'sender_address'
 */
static void
handle_pong (void *cls, const struct GNUNET_MessageHeader *message,
             const struct GNUNET_PeerIdentity *peer,
             const char *sender_address, size_t sender_address_len)
{
  if (0 == memcmp (peer, &my_identity, sizeof (struct GNUNET_PeerIdentity)))
  {
    /* PONG send to self, ignore */
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Receiving `%s' message from myself\n", "PONG");
    return;
  }
#if DEBUG_TRANSPORT > 1
  /* we get tons of these that just get discarded, only log
   * if we are quite verbose */
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Receiving `%s' message from `%4s'.\n", "PONG",
              GNUNET_i2s (peer));
#endif
  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# PONG messages received"),
                            1, GNUNET_NO);
  if (GNUNET_SYSERR !=
      GNUNET_CONTAINER_multihashmap_get_multiple (validation_map,
                                                  &peer->hashPubKey,
                                                  &check_pending_validation,
                                                  (void *) message))
  {
    /* This is *expected* to happen a lot since we send
     * PONGs to *all* known addresses of the sender of
     * the PING, so most likely we get multiple PONGs
     * per PING, and all but the first PONG will end up
     * here. So really we should not print anything here
     * unless we want to be very, very verbose... */
#if DEBUG_TRANSPORT > 2
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Received `%s' message from `%4s' but have no record of a matching `%s' message. Ignoring.\n",
                "PONG", GNUNET_i2s (peer), "PING");
#endif
    return;
  }

}


/**
 * Try to validate a neighbour's address by sending him our HELLO and a PING.
 *
 * @param cls the 'struct ValidationEntry*'
 * @param neighbour neighbour to validate, NULL if validation failed
 */
static void
transmit_hello_and_ping (void *cls, struct NeighbourMapEntry *neighbour)
{
  struct ValidationEntry *va = cls;
  struct ForeignAddressList *peer_address;
  struct TransportPingMessage ping;
  uint16_t hello_size;
  size_t tsize;
  char *message_buf;
  struct GNUNET_PeerIdentity id;
  size_t slen;

  GNUNET_CRYPTO_hash (&va->publicKey,
                      sizeof (struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded),
                      &id.hashPubKey);
  if (neighbour == NULL)
  {
    /* FIXME: stats... */
    GNUNET_break (GNUNET_OK ==
                  GNUNET_CONTAINER_multihashmap_remove (validation_map,
                                                        &id.hashPubKey, va));
    abort_validation (NULL, NULL, va);
    return;
  }
  neighbour->publicKey = va->publicKey;
  neighbour->public_key_valid = GNUNET_YES;
  peer_address = add_peer_address (neighbour,
                                   va->transport_name, NULL,
                                   (const void *) &va[1], va->addrlen);
  if (peer_address == NULL)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                "Failed to add peer `%4s' for plugin `%s'\n",
                GNUNET_i2s (&neighbour->id), va->transport_name);
    GNUNET_break (GNUNET_OK ==
                  GNUNET_CONTAINER_multihashmap_remove (validation_map,
                                                        &id.hashPubKey, va));
    abort_validation (NULL, NULL, va);
    return;
  }
  if (NULL == our_hello)
    refresh_hello_task (NULL, NULL);
  hello_size = GNUNET_HELLO_size (our_hello);
  slen = strlen (va->transport_name) + 1;
  tsize =
      sizeof (struct TransportPingMessage) + hello_size + va->addrlen + slen;
  message_buf = GNUNET_malloc (tsize);
  ping.challenge = htonl (va->challenge);
  ping.header.size =
      htons (sizeof (struct TransportPingMessage) + slen + va->addrlen);
  ping.header.type = htons (GNUNET_MESSAGE_TYPE_TRANSPORT_PING);
  memcpy (&ping.target, &neighbour->id, sizeof (struct GNUNET_PeerIdentity));
  memcpy (message_buf, our_hello, hello_size);
  memcpy (&message_buf[hello_size],
          &ping, sizeof (struct TransportPingMessage));
  memcpy (&message_buf[hello_size + sizeof (struct TransportPingMessage)],
          va->transport_name, slen);
  memcpy (&message_buf
          [hello_size + sizeof (struct TransportPingMessage) + slen], &va[1],
          va->addrlen);
#if DEBUG_TRANSPORT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Performing validation of address `%s' via `%s' for peer `%4s' sending `%s' (%u bytes) and `%s' (%u bytes)\n",
              (va->addrlen == 0)
              ? "<inbound>"
              : a2s (va->transport_name,
                     (const void *) &va[1], va->addrlen),
              va->transport_name,
              GNUNET_i2s (&neighbour->id),
              "HELLO", hello_size,
              "PING",
              sizeof (struct TransportPingMessage) + va->addrlen + slen);
#endif

  GNUNET_STATISTICS_update (stats,
                            gettext_noop
                            ("# PING messages sent for initial validation"), 1,
                            GNUNET_NO);
  transmit_to_peer (NULL, peer_address, GNUNET_SCHEDULER_PRIORITY_DEFAULT,
                    HELLO_VERIFICATION_TIMEOUT, message_buf, tsize, GNUNET_YES,
                    neighbour);
  GNUNET_free (message_buf);
}


/**
 * Check if the given address is already being validated; if not,
 * append the given address to the list of entries that are being be
 * validated and initiate validation.
 *
 * @param cls closure ('struct CheckHelloValidatedContext *')
 * @param tname name of the transport
 * @param expiration expiration time
 * @param addr the address
 * @param addrlen length of the address
 * @return GNUNET_OK (always)
 */
static int
run_validation (void *cls,
                const char *tname,
                struct GNUNET_TIME_Absolute expiration,
                const void *addr, uint16_t addrlen)
{
  struct CheckHelloValidatedContext *chvc = cls;
  struct GNUNET_PeerIdentity id;
  struct TransportPlugin *tp;
  struct ValidationEntry *va;
  struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded pk;
  struct CheckAddressExistsClosure caec;
  struct OwnAddressList *oal;

  GNUNET_assert (addr != NULL);

  GNUNET_STATISTICS_update (stats,
                            gettext_noop
                            ("# peer addresses scheduled for validation"), 1,
                            GNUNET_NO);
  tp = find_transport (tname);
  if (tp == NULL)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_INFO |
                GNUNET_ERROR_TYPE_BULK,
                _
                ("Transport `%s' not loaded, will not try to validate peer address using this transport.\n"),
                tname);
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# peer addresses not validated (plugin not available)"),
                              1, GNUNET_NO);
    return GNUNET_OK;
  }
  /* check if this is one of our own addresses */
  oal = tp->addresses;
  while (NULL != oal)
  {
    if ((oal->addrlen == addrlen) && (0 == memcmp (&oal[1], addr, addrlen)))
    {
      /* not plausible, this address is equivalent to our own address! */
      GNUNET_STATISTICS_update (stats,
                                gettext_noop
                                ("# peer addresses not validated (loopback)"),
                                1, GNUNET_NO);
      return GNUNET_OK;
    }
    oal = oal->next;
  }
  GNUNET_HELLO_get_key (chvc->hello, &pk);
  GNUNET_CRYPTO_hash (&pk,
                      sizeof (struct
                              GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded),
                      &id.hashPubKey);

  if (is_blacklisted (&id, tp))
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Attempted to validate blacklisted peer `%s' using `%s'!\n",
                GNUNET_i2s (&id), tname);
#endif
    return GNUNET_OK;
  }

  caec.addr = addr;
  caec.addrlen = addrlen;
  caec.session = NULL;
  caec.tname = tname;
  caec.exists = GNUNET_NO;
  GNUNET_CONTAINER_multihashmap_iterate (validation_map,
                                         &check_address_exists, &caec);
  if (caec.exists == GNUNET_YES)
  {
    /* During validation attempts we will likely trigger the other
     * peer trying to validate our address which in turn will cause
     * it to send us its HELLO, so we expect to hit this case rather
     * frequently.  Only print something if we are very verbose. */
#if DEBUG_TRANSPORT > 1
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Validation of address `%s' via `%s' for peer `%4s' already in progress.\n",
                a2s (tname, addr, addrlen), tname, GNUNET_i2s (&id));
#endif
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# peer addresses not validated (in progress)"),
                              1, GNUNET_NO);
    return GNUNET_OK;
  }
  va = GNUNET_malloc (sizeof (struct ValidationEntry) + addrlen);
  va->chvc = chvc;
  chvc->ve_count++;
  va->transport_name = GNUNET_strdup (tname);
  va->challenge = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE,
                                            UINT_MAX);
  va->send_time = GNUNET_TIME_absolute_get ();
  va->addr = (const void *) &va[1];
  memcpy (&va[1], addr, addrlen);
  va->addrlen = addrlen;
  GNUNET_HELLO_get_key (chvc->hello, &va->publicKey);
  va->timeout_task = GNUNET_SCHEDULER_add_delayed (HELLO_VERIFICATION_TIMEOUT,
                                                   &timeout_hello_validation,
                                                   va);
  GNUNET_CONTAINER_multihashmap_put (validation_map,
                                     &id.hashPubKey,
                                     va,
                                     GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE);
  setup_peer_check_blacklist (&id, GNUNET_NO, &transmit_hello_and_ping, va);
  return GNUNET_OK;
}


/**
 * Check if addresses in validated hello "h" overlap with
 * those in "chvc->hello" and validate the rest.
 *
 * @param cls closure
 * @param peer id of the peer, NULL for last call
 * @param h hello message for the peer (can be NULL)
 * @param err_msg NULL if successful, otherwise contains error message
 */
static void
check_hello_validated (void *cls,
                       const struct GNUNET_PeerIdentity *peer,
                       const struct GNUNET_HELLO_Message *h,
                       const char *err_msg)
{
  struct CheckHelloValidatedContext *chvc = cls;
  struct GNUNET_HELLO_Message *plain_hello;
  struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded pk;
  struct GNUNET_PeerIdentity target;
  struct NeighbourMapEntry *n;

  if (err_msg != NULL)
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                _("Error in communication with PEERINFO service: %s\n"),
                err_msg);
#endif
    /* return; */
  }

  if (peer == NULL)
  {
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# outstanding peerinfo iterate requests"), -1,
                              GNUNET_NO);
    chvc->piter = NULL;
    if (GNUNET_NO == chvc->hello_known)
    {
      /* notify PEERINFO about the peer now, so that we at least
       * have the public key if some other component needs it */
      GNUNET_HELLO_get_key (chvc->hello, &pk);
      GNUNET_CRYPTO_hash (&pk,
                          sizeof (struct
                                  GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded),
                          &target.hashPubKey);
      plain_hello = GNUNET_HELLO_create (&pk, NULL, NULL);
      GNUNET_PEERINFO_add_peer (peerinfo, plain_hello);
      GNUNET_free (plain_hello);
#if DEBUG_TRANSPORT_HELLO
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "PEERINFO had no `%s' message for peer `%4s', full validation needed.\n",
                  "HELLO", GNUNET_i2s (&target));
#endif
      GNUNET_STATISTICS_update (stats,
                                gettext_noop
                                ("# new HELLOs requiring full validation"), 1,
                                GNUNET_NO);
      GNUNET_HELLO_iterate_addresses (chvc->hello, GNUNET_NO, &run_validation,
                                      chvc);
    }
    else
    {
      GNUNET_STATISTICS_update (stats,
                                gettext_noop ("# duplicate HELLO (peer known)"),
                                1, GNUNET_NO);
    }
    chvc->ve_count--;
    if (chvc->ve_count == 0)
    {
      GNUNET_CONTAINER_DLL_remove (chvc_head, chvc_tail, chvc);
      GNUNET_free (chvc);
    }
    return;
  }
  if (h == NULL)
    return;
#if DEBUG_TRANSPORT_HELLO
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "PEERINFO had `%s' message for peer `%4s', validating only new addresses.\n",
              "HELLO", GNUNET_i2s (peer));
#endif
  chvc->hello_known = GNUNET_YES;
  n = find_neighbour (peer);
  if (n != NULL)
  {
#if DEBUG_TRANSPORT_HELLO
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Calling hello_iterate_addresses for %s!\n", GNUNET_i2s (peer));
#endif
    GNUNET_HELLO_iterate_addresses (h,
                                    GNUNET_NO, &add_to_foreign_address_list, n);
    try_transmission_to_peer (n);
  }
  else
  {
#if DEBUG_TRANSPORT_HELLO
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "No existing neighbor record for %s!\n", GNUNET_i2s (peer));
#endif
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# no existing neighbour record (validating HELLO)"),
                              1, GNUNET_NO);
  }
  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# HELLO validations (update case)"),
                            1, GNUNET_NO);
  GNUNET_HELLO_iterate_new_addresses (chvc->hello,
                                      h,
                                      GNUNET_TIME_relative_to_absolute
                                      (HELLO_REVALIDATION_START_TIME),
                                      &run_validation, chvc);
}


/**
 * Process HELLO-message.
 *
 * @param plugin transport involved, may be NULL
 * @param message the actual message
 * @return GNUNET_OK if the HELLO was well-formed, GNUNET_SYSERR otherwise
 */
static int
process_hello (struct TransportPlugin *plugin,
               const struct GNUNET_MessageHeader *message)
{
  uint16_t hsize;
  struct GNUNET_PeerIdentity target;
  const struct GNUNET_HELLO_Message *hello;
  struct CheckHelloValidatedContext *chvc;
  struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded publicKey;
  struct NeighbourMapEntry *n;

#if DEBUG_TRANSPORT_HELLO > 2
  char *my_id;
#endif

  hsize = ntohs (message->size);
  if ((ntohs (message->type) != GNUNET_MESSAGE_TYPE_HELLO) ||
      (hsize < sizeof (struct GNUNET_MessageHeader)))
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# HELLOs received for validation"),
                            1, GNUNET_NO);

  hello = (const struct GNUNET_HELLO_Message *) message;
  if (GNUNET_OK != GNUNET_HELLO_get_key (hello, &publicKey))
  {
#if DEBUG_TRANSPORT_HELLO
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Unable to get public key from `%s' for `%4s'!\n",
                "HELLO", GNUNET_i2s (&target));
#endif
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  GNUNET_CRYPTO_hash (&publicKey,
                      sizeof (struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded),
                      &target.hashPubKey);

#if DEBUG_TRANSPORT_HELLO
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Received `%s' message for `%4s'\n",
              "HELLO", GNUNET_i2s (&target));
#endif
  if (0 == memcmp (&my_identity, &target, sizeof (struct GNUNET_PeerIdentity)))
  {
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# HELLOs ignored for validation (is my own HELLO)"),
                              1, GNUNET_NO);
    return GNUNET_OK;
  }
  n = find_neighbour (&target);
  if ((NULL != n) && (!n->public_key_valid))
  {
    GNUNET_HELLO_get_key (hello, &n->publicKey);
    n->public_key_valid = GNUNET_YES;
  }

  /* check if load is too high before doing expensive stuff */
  if (GNUNET_SCHEDULER_get_load (GNUNET_SCHEDULER_PRIORITY_BACKGROUND) >
      MAX_HELLO_LOAD)
  {
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# HELLOs ignored due to high load"), 1,
                              GNUNET_NO);
#if DEBUG_TRANSPORT_HELLO
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Ignoring `%s' for `%4s', load too high.\n",
                "HELLO", GNUNET_i2s (&target));
#endif
    return GNUNET_OK;
  }


  chvc = chvc_head;
  while (NULL != chvc)
  {
    if (GNUNET_HELLO_equals (hello,
                             chvc->hello,
                             GNUNET_TIME_absolute_get ()).abs_value > 0)
    {
#if DEBUG_TRANSPORT_HELLO > 2
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Received duplicate `%s' message for `%4s'; ignored\n",
                  "HELLO", GNUNET_i2s (&target));
#endif
      return GNUNET_OK;         /* validation already pending */
    }
    if (GNUNET_HELLO_size (hello) == GNUNET_HELLO_size (chvc->hello))
      GNUNET_break (0 != memcmp (hello, chvc->hello,
                                 GNUNET_HELLO_size (hello)));
    chvc = chvc->next;
  }

#if BREAK_TESTS
  struct NeighbourMapEntry *temp_neighbor = find_neighbour (&target);

  if ((NULL != temp_neighbor))
  {
    fprintf (stderr, "Already know peer, ignoring hello\n");
    return GNUNET_OK;
  }
#endif

#if DEBUG_TRANSPORT_HELLO > 2
  if (plugin != NULL)
  {
#if DEBUG_TRANSPORT
    my_id = GNUNET_strdup (GNUNET_i2s (plugin->env.my_identity));
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "%s: Starting validation of `%s' message for `%4s' via '%s' of size %u\n",
                my_id,
                "HELLO",
                GNUNET_i2s (&target),
                plugin->short_name, GNUNET_HELLO_size (hello));
    GNUNET_free (my_id);
#endif
  }
#endif
  chvc = GNUNET_malloc (sizeof (struct CheckHelloValidatedContext) + hsize);
  chvc->ve_count = 1;
  chvc->hello = (const struct GNUNET_HELLO_Message *) &chvc[1];
  memcpy (&chvc[1], hello, hsize);
  GNUNET_CONTAINER_DLL_insert (chvc_head, chvc_tail, chvc);
  /* finally, check if HELLO was previously validated
   * (continuation will then schedule actual validation) */
  GNUNET_STATISTICS_update (stats,
                            gettext_noop
                            ("# peerinfo process hello iterate requests"), 1,
                            GNUNET_NO);
  GNUNET_STATISTICS_update (stats,
                            gettext_noop
                            ("# outstanding peerinfo iterate requests"), 1,
                            GNUNET_NO);
  chvc->piter =
      GNUNET_PEERINFO_iterate (peerinfo, &target, HELLO_VERIFICATION_TIMEOUT,
                               &check_hello_validated, chvc);
  return GNUNET_OK;
}


/**
 * The peer specified by the given neighbour has timed-out or a plugin
 * has disconnected.  We may either need to do nothing (other plugins
 * still up), or trigger a full disconnect and clean up.  This
 * function updates our state and does the necessary notifications.
 * Also notifies our clients that the neighbour is now officially
 * gone.
 *
 * @param n the neighbour list entry for the peer
 * @param check GNUNET_YES to check if ALL addresses for this peer
 *              are gone, GNUNET_NO to force a disconnect of the peer
 *              regardless of whether other addresses exist.
 */
static void
disconnect_neighbour (struct NeighbourMapEntry *n, int check)
{
  struct ReadyList *rpos;
  struct MessageQueue *mq;
  struct ForeignAddressList *peer_addresses;
  struct ForeignAddressList *peer_pos;

  if (GNUNET_YES == n->in_disconnect)
    return;
  if (GNUNET_YES == check)
  {
    rpos = n->plugins;
    while (NULL != rpos)
    {
      peer_addresses = rpos->addresses;
      while (peer_addresses != NULL)
      {
        /* Do not disconnect if: an address is connected or an inbound address exists */
        if ((GNUNET_YES == peer_addresses->connected) ||
            (peer_addresses->addrlen == 0))
        {
#if DEBUG_TRANSPORT
          GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                      "NOT Disconnecting from `%4s', still have live address `%s'!\n",
                      GNUNET_i2s (&n->id),
                      a2s (peer_addresses->ready_list->plugin->short_name,
                           peer_addresses->addr, peer_addresses->addrlen));
#endif
          return;               /* still connected */
        }
        peer_addresses = peer_addresses->next;
      }
      rpos = rpos->next;
    }
  }
#if DEBUG_TRANSPORT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG | GNUNET_ERROR_TYPE_BULK,
              "Disconnecting from `%4s'\n", GNUNET_i2s (&n->id));
#endif
  n->in_disconnect = GNUNET_YES;        /* prevent recursive entry */

  /* notify all clients about disconnect */
  if (GNUNET_YES == n->received_pong)
  {
    n->received_pong = GNUNET_NO;
    notify_clients_disconnect (&n->id);
  }
#if HAVE_LIBGLPK
  ats_modify_problem_state (ats, ATS_MODIFIED);
#endif
  /* clean up all plugins, cancel connections and pending transmissions */
  while (NULL != (rpos = n->plugins))
  {
    n->plugins = rpos->next;
    rpos->plugin->api->disconnect (rpos->plugin->api->cls, &n->id);
    while (rpos->addresses != NULL)
    {
      peer_pos = rpos->addresses;
      rpos->addresses = peer_pos->next;
      if (peer_pos->connected == GNUNET_YES)
      {
        GNUNET_STATISTICS_update (stats,
                                  gettext_noop ("# connected addresses"),
                                  -1, GNUNET_NO);
        peer_pos->connected = GNUNET_NO;
      }
      if (GNUNET_YES == peer_pos->validated)
        GNUNET_STATISTICS_update (stats,
                                  gettext_noop
                                  ("# peer addresses considered valid"), -1,
                                  GNUNET_NO);
      if (GNUNET_SCHEDULER_NO_TASK != peer_pos->revalidate_task)
      {
        GNUNET_SCHEDULER_cancel (peer_pos->revalidate_task);
        peer_pos->revalidate_task = GNUNET_SCHEDULER_NO_TASK;
      }
      GNUNET_free (peer_pos->ressources);
      peer_pos->ressources = NULL;
      GNUNET_free (peer_pos->quality);
      peer_pos->ressources = NULL;
      GNUNET_free (peer_pos);
    }
    GNUNET_free (rpos);
  }

  /* free all messages on the queue */
  while (NULL != (mq = n->messages_head))
  {
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# bytes in message queue for other peers"),
                              -(int64_t) mq->message_buf_size, GNUNET_NO);
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# bytes discarded due to disconnect"),
                              mq->message_buf_size, GNUNET_NO);
    GNUNET_CONTAINER_DLL_remove (n->messages_head, n->messages_tail, mq);
    GNUNET_assert (0 == memcmp (&mq->neighbour_id,
                                &n->id, sizeof (struct GNUNET_PeerIdentity)));
    GNUNET_free (mq);
  }

  while (NULL != (mq = n->cont_head))
  {

    GNUNET_CONTAINER_DLL_remove (n->cont_head, n->cont_tail, mq);
    GNUNET_assert (0 == memcmp (&mq->neighbour_id,
                                &n->id, sizeof (struct GNUNET_PeerIdentity)));
    GNUNET_free (mq);
  }

  if (n->timeout_task != GNUNET_SCHEDULER_NO_TASK)
  {
    GNUNET_SCHEDULER_cancel (n->timeout_task);
    n->timeout_task = GNUNET_SCHEDULER_NO_TASK;
  }
  if (n->retry_task != GNUNET_SCHEDULER_NO_TASK)
  {
    GNUNET_SCHEDULER_cancel (n->retry_task);
    n->retry_task = GNUNET_SCHEDULER_NO_TASK;
  }
  if (n->piter != NULL)
  {
    GNUNET_PEERINFO_iterate_cancel (n->piter);
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# outstanding peerinfo iterate requests"), -1,
                              GNUNET_NO);
    n->piter = NULL;
  }

  GNUNET_assert (GNUNET_OK ==
                 GNUNET_CONTAINER_multihashmap_remove (neighbours,
                                                       &n->id.hashPubKey, n));
  /* finally, free n itself */
  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# active neighbours"),
                            -1, GNUNET_NO);
  GNUNET_free_non_null (n->pre_connect_message_buffer);
  GNUNET_free (n);
}


/**
 * We have received a PING message from someone.  Need to send a PONG message
 * in response to the peer by any means necessary.
 */
static int
handle_ping (void *cls, const struct GNUNET_MessageHeader *message,
             const struct GNUNET_PeerIdentity *peer,
             struct Session *session,
             const char *sender_address, uint16_t sender_address_len)
{
  struct TransportPlugin *plugin = cls;
  struct SessionHeader *session_header = (struct SessionHeader *) session;
  struct TransportPingMessage *ping;
  struct TransportPongMessage *pong;
  struct NeighbourMapEntry *n;
  struct ReadyList *rl;
  struct ForeignAddressList *fal;
  struct OwnAddressList *oal;
  const char *addr;
  size_t alen;
  size_t slen;
  int did_pong;

  if (ntohs (message->size) < sizeof (struct TransportPingMessage))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }

  ping = (struct TransportPingMessage *) message;
  if (0 != memcmp (&ping->target,
                   plugin->env.my_identity,
                   sizeof (struct GNUNET_PeerIdentity)))
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                _
                ("Received `%s' message from `%s' destined for `%s' which is not me!\n"),
                "PING", (sender_address != NULL) ? a2s (plugin->short_name,
                                                        (const struct sockaddr
                                                         *) sender_address,
                                                        sender_address_len) :
                "<inbound>", GNUNET_i2s (&ping->target));
#endif
    return GNUNET_SYSERR;
  }
#if DEBUG_PING_PONG
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG | GNUNET_ERROR_TYPE_BULK,
              "Processing `%s' from `%s'\n",
              "PING",
              (sender_address != NULL)
              ? a2s (plugin->short_name,
                     (const struct sockaddr *) sender_address,
                     sender_address_len) : "<inbound>");
#endif
  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# PING messages received"),
                            1, GNUNET_NO);
  addr = (const char *) &ping[1];
  alen = ntohs (message->size) - sizeof (struct TransportPingMessage);
  slen = strlen (plugin->short_name) + 1;
  if (alen == 0)
  {
    /* peer wants to confirm that we have an outbound connection to him */
    if (session == NULL)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                  _
                  ("Refusing to create PONG since I do not have a session with `%s'.\n"),
                  GNUNET_i2s (peer));
      return GNUNET_SYSERR;
    }
    /* FIXME-urg: the use of 'sender_address' in the code below is doubly-wrong:
     * 1) it is NULL when we need to have a real value
     * 2) it is documented to be the address of the sender (source-IP), where
     * what we actually want is our LISTEN IP (what we 'bound' to); which we don't even
     * have...
     */
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Creating PONG indicating that we received a connection at our address `%s' from `%s'.\n",
                a2s (plugin->short_name,
                     sender_address, sender_address_len), GNUNET_i2s (peer));

    pong =
        GNUNET_malloc (sizeof (struct TransportPongMessage) +
                       sender_address_len + slen);
    pong->header.size =
        htons (sizeof (struct TransportPongMessage) + sender_address_len +
               slen);
    pong->header.type = htons (GNUNET_MESSAGE_TYPE_TRANSPORT_PONG);
    pong->purpose.size =
        htonl (sizeof (struct GNUNET_CRYPTO_RsaSignaturePurpose) +
               sizeof (uint32_t) +
               sizeof (struct GNUNET_TIME_AbsoluteNBO) +
               sizeof (struct GNUNET_PeerIdentity) + sender_address_len + slen);
    pong->purpose.purpose =
        htonl (GNUNET_SIGNATURE_PURPOSE_TRANSPORT_PONG_USING);
    pong->challenge = ping->challenge;
    pong->addrlen = htonl (sender_address_len + slen);
    memcpy (&pong->pid, peer, sizeof (struct GNUNET_PeerIdentity));
    memcpy (&pong[1], plugin->short_name, slen);
    if ((sender_address != NULL) && (sender_address_len > 0))
      memcpy (&((char *) &pong[1])[slen], sender_address, sender_address_len);
    if (GNUNET_TIME_absolute_get_remaining
        (session_header->pong_sig_expires).rel_value <
        PONG_SIGNATURE_LIFETIME.rel_value / 4)
    {
      /* create / update cached sig */
#if DEBUG_TRANSPORT
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Creating PONG signature to indicate active connection.\n");
#endif
      session_header->pong_sig_expires =
          GNUNET_TIME_relative_to_absolute (PONG_SIGNATURE_LIFETIME);
      pong->expiration =
          GNUNET_TIME_absolute_hton (session_header->pong_sig_expires);
      GNUNET_assert (GNUNET_OK ==
                     GNUNET_CRYPTO_rsa_sign (my_private_key, &pong->purpose,
                                             &session_header->pong_signature));
    }
    else
    {
      pong->expiration =
          GNUNET_TIME_absolute_hton (session_header->pong_sig_expires);
    }
    memcpy (&pong->signature,
            &session_header->pong_signature,
            sizeof (struct GNUNET_CRYPTO_RsaSignature));


  }
  else
  {
    /* peer wants to confirm that this is one of our addresses */
    addr += slen;
    alen -= slen;
    if (GNUNET_OK != plugin->api->check_address (plugin->api->cls, addr, alen))
    {
      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                  _
                  ("Not confirming PING with address `%s' since I cannot confirm having this address.\n"),
                  a2s (plugin->short_name, addr, alen));
      return GNUNET_NO;
    }
    oal = plugin->addresses;
    while (NULL != oal)
    {
      if ((oal->addrlen == alen) && (0 == memcmp (addr, &oal[1], alen)))
        break;
      oal = oal->next;
    }
    pong = GNUNET_malloc (sizeof (struct TransportPongMessage) + alen + slen);
    pong->header.size =
        htons (sizeof (struct TransportPongMessage) + alen + slen);
    pong->header.type = htons (GNUNET_MESSAGE_TYPE_TRANSPORT_PONG);
    pong->purpose.size =
        htonl (sizeof (struct GNUNET_CRYPTO_RsaSignaturePurpose) +
               sizeof (uint32_t) +
               sizeof (struct GNUNET_TIME_AbsoluteNBO) +
               sizeof (struct GNUNET_PeerIdentity) + alen + slen);
    pong->purpose.purpose = htonl (GNUNET_SIGNATURE_PURPOSE_TRANSPORT_PONG_OWN);
    pong->challenge = ping->challenge;
    pong->addrlen = htonl (alen + slen);
    memcpy (&pong->pid, &my_identity, sizeof (struct GNUNET_PeerIdentity));
    memcpy (&pong[1], plugin->short_name, slen);
    memcpy (&((char *) &pong[1])[slen], addr, alen);
    if ((oal != NULL) &&
        (GNUNET_TIME_absolute_get_remaining (oal->pong_sig_expires).rel_value <
         PONG_SIGNATURE_LIFETIME.rel_value / 4))
    {
      /* create / update cached sig */
#if DEBUG_TRANSPORT
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Creating PONG signature to indicate ownership.\n");
#endif
      oal->pong_sig_expires =
          GNUNET_TIME_relative_to_absolute (PONG_SIGNATURE_LIFETIME);
      pong->expiration = GNUNET_TIME_absolute_hton (oal->pong_sig_expires);
      GNUNET_assert (GNUNET_OK ==
                     GNUNET_CRYPTO_rsa_sign (my_private_key,
                                             &pong->purpose,
                                             &oal->pong_signature));
      memcpy (&pong->signature,
              &oal->pong_signature, sizeof (struct GNUNET_CRYPTO_RsaSignature));
    }
    else if (oal == NULL)
    {
      /* not using cache (typically DV-only) */
      pong->expiration =
          GNUNET_TIME_absolute_hton (GNUNET_TIME_relative_to_absolute
                                     (PONG_SIGNATURE_LIFETIME));
      GNUNET_assert (GNUNET_OK ==
                     GNUNET_CRYPTO_rsa_sign (my_private_key, &pong->purpose,
                                             &pong->signature));
    }
    else
    {
      /* can used cached version */
      pong->expiration = GNUNET_TIME_absolute_hton (oal->pong_sig_expires);
      memcpy (&pong->signature,
              &oal->pong_signature, sizeof (struct GNUNET_CRYPTO_RsaSignature));
    }
  }
  n = find_neighbour (peer);
  GNUNET_assert (n != NULL);
  did_pong = GNUNET_NO;
  /* first try reliable response transmission */
  rl = n->plugins;
  while (rl != NULL)
  {
    fal = rl->addresses;
    while (fal != NULL)
    {
      if (-1 != rl->plugin->api->send (rl->plugin->api->cls,
                                       peer,
                                       (const char *) pong,
                                       ntohs (pong->header.size),
                                       TRANSPORT_PONG_PRIORITY,
                                       HELLO_VERIFICATION_TIMEOUT,
                                       fal->session,
                                       fal->addr,
                                       fal->addrlen, GNUNET_SYSERR, NULL, NULL))
      {
        GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                    "Transmitted PONG to `%s' via reliable mechanism\n",
                    GNUNET_i2s (peer));
        /* done! */
        GNUNET_STATISTICS_update (stats,
                                  gettext_noop
                                  ("# PONGs unicast via reliable transport"), 1,
                                  GNUNET_NO);
        GNUNET_free (pong);
        return GNUNET_OK;
      }
      did_pong = GNUNET_YES;
      fal = fal->next;
    }
    rl = rl->next;
  }
  /* no reliable method found, do multicast */
  GNUNET_STATISTICS_update (stats,
                            gettext_noop
                            ("# PONGs multicast to all available addresses"), 1,
                            GNUNET_NO);
  rl = n->plugins;
  while (rl != NULL)
  {
    fal = rl->addresses;
    while (fal != NULL)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Transmitting PONG to `%s' via unreliable mechanism `%s':%s\n",
                  GNUNET_i2s (peer),
                  a2s (rl->plugin->short_name,
                       fal->addr, fal->addrlen), rl->plugin->short_name);
      transmit_to_peer (NULL, fal,
                        TRANSPORT_PONG_PRIORITY,
                        HELLO_VERIFICATION_TIMEOUT,
                        (const char *) pong,
                        ntohs (pong->header.size), GNUNET_YES, n);
      did_pong = GNUNET_YES;
      fal = fal->next;
    }
    rl = rl->next;
  }
  GNUNET_free (pong);
  if (GNUNET_YES != did_pong)
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                _("Could not send PONG to `%s': no address available\n"),
                GNUNET_i2s (peer));
  return GNUNET_OK;
}


/**
 * Function called by the plugin for each received message.  Update
 * data volumes, possibly notify plugins about reducing the rate at
 * which they read from the socket and generally forward to our
 * receive callback.
 *
 * @param cls the "struct TransportPlugin *" we gave to the plugin
 * @param peer (claimed) identity of the other peer
 * @param message the message, NULL if we only care about
 *                learning about the delay until we should receive again
 * @param ats_data information for automatic transport selection
 * @param ats_count number of elements in ats not including 0-terminator
 * @param session identifier used for this session (can be NULL)
 * @param sender_address binary address of the sender (if observed)
 * @param sender_address_len number of bytes in sender_address
 * @return how long in ms the plugin should wait until receiving more data
 *         (plugins that do not support this, can ignore the return value)
 */
static struct GNUNET_TIME_Relative
plugin_env_receive (void *cls, const struct GNUNET_PeerIdentity *peer,
                    const struct GNUNET_MessageHeader *message,
                    const struct GNUNET_TRANSPORT_ATS_Information *ats_data,
                    uint32_t ats_count,
                    struct Session *session,
                    const char *sender_address, uint16_t sender_address_len)
{
  struct TransportPlugin *plugin = cls;
  struct ReadyList *service_context;
  struct ForeignAddressList *peer_address;
  uint16_t msize;
  struct NeighbourMapEntry *n;
  struct GNUNET_TIME_Relative ret;
  uint32_t distance;
  int c;

  if (0 == memcmp (peer, &my_identity, sizeof (struct GNUNET_PeerIdentity)))
  {
    /* refuse to receive from myself */
    GNUNET_break (0);
    return GNUNET_TIME_UNIT_FOREVER_REL;
  }
  if (is_blacklisted (peer, plugin))
    return GNUNET_TIME_UNIT_FOREVER_REL;
  n = find_neighbour (peer);
  if (n == NULL)
    n = setup_new_neighbour (peer, GNUNET_YES);
  service_context = n->plugins;
  while ((service_context != NULL) && (plugin != service_context->plugin))
    service_context = service_context->next;
  GNUNET_assert ((plugin->api->send == NULL) || (service_context != NULL));
  peer_address = NULL;
  distance = 1;

  for (c = 0; c < ats_count; c++)
    if (ntohl (ats_data[c].type) == GNUNET_TRANSPORT_ATS_QUALITY_NET_DISTANCE)
      distance = ntohl (ats_data[c].value);


  if (message != NULL)
  {
    if ((session != NULL) || (sender_address != NULL))
      peer_address = add_peer_address (n,
                                       plugin->short_name,
                                       session,
                                       sender_address, sender_address_len);
    if (peer_address != NULL)
    {
      update_addr_ats (peer_address, ats_data, ats_count);
      update_addr_value (peer_address, distance,
                         GNUNET_TRANSPORT_ATS_QUALITY_NET_DISTANCE);

      peer_address->distance = distance;
      if (GNUNET_YES == peer_address->validated)
      {
        mark_address_connected (peer_address);
        schedule_next_ping (peer_address);
      }
      else
      {
#if DEBUG_TRANSPORT
        GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                    "New address is unvalidated, trying to validate it now\n");
#endif
        if (peer_address->revalidate_task != GNUNET_SCHEDULER_NO_TASK)
        {
          GNUNET_SCHEDULER_cancel (peer_address->revalidate_task);
          peer_address->revalidate_task = GNUNET_SCHEDULER_NO_TASK;
        }
        peer_address->revalidate_task =
            GNUNET_SCHEDULER_add_now (&send_periodic_ping, peer_address);

      }
      peer_address->timeout
          =
          GNUNET_TIME_relative_to_absolute
          (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT);
    }
    /* update traffic received amount ... */
    msize = ntohs (message->size);

    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# bytes received from other peers"), msize,
                              GNUNET_NO);
    n->distance = distance;
    n->peer_timeout =
        GNUNET_TIME_relative_to_absolute
        (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT);
    GNUNET_SCHEDULER_cancel (n->timeout_task);
    n->timeout_task =
        GNUNET_SCHEDULER_add_delayed (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT,
                                      &neighbour_timeout_task, n);
    if (n->quota_violation_count > QUOTA_VIOLATION_DROP_THRESHOLD)
    {
      /* dropping message due to frequent inbound volume violations! */
      GNUNET_log (GNUNET_ERROR_TYPE_WARNING |
                  GNUNET_ERROR_TYPE_BULK,
                  _
                  ("Dropping incoming message due to repeated bandwidth quota (%u b/s) violations (total of %u).\n"),
                  n->in_tracker.available_bytes_per_s__,
                  n->quota_violation_count);
      GNUNET_STATISTICS_update (stats,
                                gettext_noop
                                ("# bandwidth quota violations by other peers"),
                                1, GNUNET_NO);
      return GNUNET_CONSTANTS_QUOTA_VIOLATION_TIMEOUT;
    }
    if ((ntohs (message->type) == GNUNET_MESSAGE_TYPE_TRANSPORT_ATS) &&
        (ntohs (message->size) ==
         (sizeof (struct GNUNET_MessageHeader) + sizeof (uint32_t))))
    {
#if HAVE_LIBGLPK
      uint32_t value = ntohl (*((uint32_t *) & message[1]));

      //GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "GNUNET_MESSAGE_TYPE_TRANSPORT_ATS: %i \n", value);
      /* Force ressource and quality update */
      if ((value == 4) && (ats != NULL))
        ats_modify_problem_state (ats, ATS_QUALITY_COST_UPDATED);
      /* Force cost update */
      if ((value == 3) && (ats != NULL))
        ats_modify_problem_state (ats, ATS_COST_UPDATED);
      /* Force quality update */
      if ((value == 2) && (ats != NULL))
        ats_modify_problem_state (ats, ATS_QUALITY_UPDATED);
      /* Force full rebuild */
      if ((value == 1) && (ats != NULL))
        ats_modify_problem_state (ats, ATS_MODIFIED);
#endif
    }

#if DEBUG_PING_PONG
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Received message of type %u and size %u from `%4s', sending to all clients.\n",
                ntohs (message->type),
                ntohs (message->size), GNUNET_i2s (peer));
#endif
    switch (ntohs (message->type))
    {
    case GNUNET_MESSAGE_TYPE_HELLO:
      GNUNET_STATISTICS_update (stats,
                                gettext_noop
                                ("# HELLO messages received from other peers"),
                                1, GNUNET_NO);
      process_hello (plugin, message);
      break;
    case GNUNET_MESSAGE_TYPE_TRANSPORT_PING:
      handle_ping (plugin, message, peer, session, sender_address,
                   sender_address_len);
      if (GNUNET_YES != n->received_pong)
        transmit_plain_ping (n);
      break;
    case GNUNET_MESSAGE_TYPE_TRANSPORT_PONG:
      handle_pong (plugin, message, peer, sender_address, sender_address_len);
      break;
    case GNUNET_MESSAGE_TYPE_TRANSPORT_ATS:
      break;
    default:
      handle_payload_message (message, n);
      break;
    }
  }
  ret = GNUNET_BANDWIDTH_tracker_get_delay (&n->in_tracker, 0);
  if (ret.rel_value > 0)
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Throttling read (%llu bytes excess at %u b/s), waiting %llu ms before reading more.\n",
                (unsigned long long) n->
                in_tracker.consumption_since_last_update__,
                (unsigned int) n->in_tracker.available_bytes_per_s__,
                (unsigned long long) ret.rel_value);
#endif
    GNUNET_STATISTICS_update (stats,
                              gettext_noop ("# ms throttling suggested"),
                              (int64_t) ret.rel_value, GNUNET_NO);
  }
  return ret;
}


static int
notify_client_about_neighbour (void *cls,
                               const GNUNET_HashCode * key, void *value)
{
  struct TransportClient *c = cls;
  struct NeighbourMapEntry *n = value;
  struct ConnectInfoMessage *cim;
  uint32_t ats_count;
  size_t size;

  if (GNUNET_YES != n->received_pong)
    return GNUNET_OK;

  ats_count = 2;
  size =
      sizeof (struct ConnectInfoMessage) +
      ats_count * sizeof (struct GNUNET_TRANSPORT_ATS_Information);
  GNUNET_assert (size < GNUNET_SERVER_MAX_MESSAGE_SIZE);
  cim = GNUNET_malloc (size);
  cim->header.size = htons (size);
  cim->header.type = htons (GNUNET_MESSAGE_TYPE_TRANSPORT_CONNECT);
  cim->ats_count = htonl (ats_count);
  (&(cim->ats))[2].type = htonl (GNUNET_TRANSPORT_ATS_ARRAY_TERMINATOR);
  (&(cim->ats))[2].value = htonl (0);
  if (GNUNET_YES == n->received_pong)
  {
    (&cim->ats)[0].type = htonl (GNUNET_TRANSPORT_ATS_QUALITY_NET_DISTANCE);
    (&cim->ats)[0].value = htonl (n->distance);
    (&cim->ats)[1].type = htonl (GNUNET_TRANSPORT_ATS_QUALITY_NET_DELAY);
    (&cim->ats)[1].value = htonl ((uint32_t) n->latency.rel_value);
    cim->id = n->id;
    transmit_to_client (c, &cim->header, GNUNET_NO);
  }
  GNUNET_free (cim);
  return GNUNET_OK;
}


/**
 * Handle START-message.  This is the first message sent to us
 * by any client which causes us to add it to our list.
 *
 * @param cls closure (always NULL)
 * @param client identification of the client
 * @param message the actual message
 */
static void
handle_start (void *cls,
              struct GNUNET_SERVER_Client *client,
              const struct GNUNET_MessageHeader *message)
{
  const struct StartMessage *start;
  struct TransportClient *c;

  start = (const struct StartMessage *) message;
#if DEBUG_TRANSPORT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Received `%s' request from client\n", "START");
#endif
  c = clients;
  while (c != NULL)
  {
    if (c->client == client)
    {
      /* client already on our list! */
      GNUNET_break (0);
      GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
      return;
    }
    c = c->next;
  }
  if ((GNUNET_NO != ntohl (start->do_check)) &&
      (0 != memcmp (&start->self,
                    &my_identity, sizeof (struct GNUNET_PeerIdentity))))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                _
                ("Rejecting control connection from peer `%s', which is not me!\n"),
                GNUNET_i2s (&start->self));
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  c = GNUNET_malloc (sizeof (struct TransportClient));
  c->next = clients;
  clients = c;
  c->client = client;
  if (our_hello != NULL)
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Sending our own `%s' to new client\n", "HELLO");
#endif
    transmit_to_client (c,
                        (const struct GNUNET_MessageHeader *) our_hello,
                        GNUNET_NO);
    /* tell new client about all existing connections */
    GNUNET_CONTAINER_multihashmap_iterate (neighbours,
                                           &notify_client_about_neighbour, c);
  }
  else
  {
#if DEBUG_TRANSPORT_HELLO
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "No HELLO created yet, will transmit HELLO to client later!\n");
#endif
    refresh_hello ();
  }
  GNUNET_SERVER_receive_done (client, GNUNET_OK);
}


/**
 * Handle HELLO-message.
 *
 * @param cls closure (always NULL)
 * @param client identification of the client
 * @param message the actual message
 */
static void
handle_hello (void *cls,
              struct GNUNET_SERVER_Client *client,
              const struct GNUNET_MessageHeader *message)
{
  int ret;

  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# HELLOs received from clients"),
                            1, GNUNET_NO);
  ret = process_hello (NULL, message);
  GNUNET_SERVER_receive_done (client, ret);
}


/**
 * Closure for 'transmit_client_message'; followed by
 * 'msize' bytes of the actual message.
 */
struct TransmitClientMessageContext
{
  /**
   * Client on whom's behalf we are sending.
   */
  struct GNUNET_SERVER_Client *client;

  /**
   * Timeout for the transmission.
   */
  struct GNUNET_TIME_Absolute timeout;

  /**
   * Message priority.
   */
  uint32_t priority;

  /**
   * Size of the message in bytes.
   */
  uint16_t msize;
};


/**
 * Schedule transmission of a message we got from a client to a peer.
 *
 * @param cls the 'struct TransmitClientMessageContext*'
 * @param n destination, or NULL on error (in that case, drop the message)
 */
static void
transmit_client_message (void *cls, struct NeighbourMapEntry *n)
{
  struct TransmitClientMessageContext *tcmc = cls;
  struct TransportClient *tc;

  tc = clients;
  while ((tc != NULL) && (tc->client != tcmc->client))
    tc = tc->next;

  if (n != NULL)
  {
    transmit_to_peer (tc, NULL, tcmc->priority,
                      GNUNET_TIME_absolute_get_remaining (tcmc->timeout),
                      (char *) &tcmc[1], tcmc->msize, GNUNET_NO, n);
  }
  GNUNET_SERVER_receive_done (tcmc->client, GNUNET_OK);
  GNUNET_SERVER_client_drop (tcmc->client);
  GNUNET_free (tcmc);
}


/**
 * Handle SEND-message.
 *
 * @param cls closure (always NULL)
 * @param client identification of the client
 * @param message the actual message
 */
static void
handle_send (void *cls,
             struct GNUNET_SERVER_Client *client,
             const struct GNUNET_MessageHeader *message)
{
  const struct OutboundMessage *obm;
  const struct GNUNET_MessageHeader *obmm;
  struct TransmitClientMessageContext *tcmc;
  uint16_t size;
  uint16_t msize;

  size = ntohs (message->size);
  if (size <
      sizeof (struct OutboundMessage) + sizeof (struct GNUNET_MessageHeader))
  {
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# payload received for other peers"),
                            size, GNUNET_NO);
  obm = (const struct OutboundMessage *) message;
  obmm = (const struct GNUNET_MessageHeader *) &obm[1];
  msize = size - sizeof (struct OutboundMessage);
#if DEBUG_TRANSPORT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Received `%s' request from client with target `%4s' and message of type %u and size %u\n",
              "SEND", GNUNET_i2s (&obm->peer), ntohs (obmm->type), msize);
#endif
  tcmc = GNUNET_malloc (sizeof (struct TransmitClientMessageContext) + msize);
  tcmc->client = client;
  tcmc->priority = ntohl (obm->priority);
  tcmc->timeout =
      GNUNET_TIME_relative_to_absolute (GNUNET_TIME_relative_ntoh
                                        (obm->timeout));
  tcmc->msize = msize;
  /* FIXME: this memcpy can be up to 7% of our total runtime */
  memcpy (&tcmc[1], obmm, msize);
  GNUNET_SERVER_client_keep (client);
  setup_peer_check_blacklist (&obm->peer, GNUNET_YES,
                              &transmit_client_message, tcmc);
}


/**
 * Handle request connect message
 *
 * @param cls closure (always NULL)
 * @param client identification of the client
 * @param message the actual message
 */
static void
handle_request_connect (void *cls,
                        struct GNUNET_SERVER_Client *client,
                        const struct GNUNET_MessageHeader *message)
{
  const struct TransportRequestConnectMessage *trcm =
      (const struct TransportRequestConnectMessage *) message;

  GNUNET_STATISTICS_update (stats,
                            gettext_noop
                            ("# REQUEST CONNECT messages received"), 1,
                            GNUNET_NO);
#if DEBUG_TRANSPORT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Received a request connect message for peer `%s'\n",
              GNUNET_i2s (&trcm->peer));
#endif
  setup_peer_check_blacklist (&trcm->peer, GNUNET_YES, NULL, NULL);
  GNUNET_SERVER_receive_done (client, GNUNET_OK);
}


/**
 * Handle SET_QUOTA-message.
 *
 * @param cls closure (always NULL)
 * @param client identification of the client
 * @param message the actual message
 */
static void
handle_set_quota (void *cls,
                  struct GNUNET_SERVER_Client *client,
                  const struct GNUNET_MessageHeader *message)
{
  const struct QuotaSetMessage *qsm = (const struct QuotaSetMessage *) message;
  struct NeighbourMapEntry *n;

  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# SET QUOTA messages received"),
                            1, GNUNET_NO);
  n = find_neighbour (&qsm->peer);
  if (n == NULL)
  {
    GNUNET_SERVER_receive_done (client, GNUNET_OK);
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# SET QUOTA messages ignored (no such peer)"),
                              1, GNUNET_NO);
    return;
  }
#if DEBUG_TRANSPORT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Received `%s' request (new quota %u, old quota %u) from client for peer `%4s'\n",
              "SET_QUOTA",
              (unsigned int) ntohl (qsm->quota.value__),
              (unsigned int) n->in_tracker.available_bytes_per_s__,
              GNUNET_i2s (&qsm->peer));
#endif
  GNUNET_BANDWIDTH_tracker_update_quota (&n->in_tracker, qsm->quota);
  if (0 == ntohl (qsm->quota.value__))
  {
#if DEBUG_TRANSPORT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Disconnecting peer `%4s', %s\n", GNUNET_i2s (&n->id),
                "SET_QUOTA");
#endif
    GNUNET_STATISTICS_update (stats,
                              gettext_noop ("# disconnects due to quota of 0"),
                              1, GNUNET_NO);
    disconnect_neighbour (n, GNUNET_NO);
  }
  GNUNET_SERVER_receive_done (client, GNUNET_OK);
}


/**
 * Take the given address and append it to the set of results sent back to
 * the client.
 *
 * @param cls the transmission context used ('struct GNUNET_SERVER_TransmitContext*')
 * @param address the resolved name, NULL to indicate the last response
 */
static void
transmit_address_to_client (void *cls, const char *address)
{
  struct GNUNET_SERVER_TransmitContext *tc = cls;
  size_t slen;

  if (NULL != address)
  {
    slen = strlen (address) + 1;
    GNUNET_SERVER_transmit_context_append_data (tc, address, slen,
                                                GNUNET_MESSAGE_TYPE_TRANSPORT_ADDRESS_REPLY);
  }
  else
  {
    GNUNET_SERVER_transmit_context_append_data (tc, NULL, 0,
                                                GNUNET_MESSAGE_TYPE_TRANSPORT_ADDRESS_REPLY);
    GNUNET_SERVER_transmit_context_run (tc, GNUNET_TIME_UNIT_FOREVER_REL);
  }
}


/**
 * Handle AddressLookup-message.
 *
 * @param cls closure (always NULL)
 * @param client identification of the client
 * @param message the actual message
 */
static void
handle_address_lookup (void *cls,
                       struct GNUNET_SERVER_Client *client,
                       const struct GNUNET_MessageHeader *message)
{
  const struct AddressLookupMessage *alum;
  struct TransportPlugin *lsPlugin;
  const char *nameTransport;
  const char *address;
  uint16_t size;
  struct GNUNET_SERVER_TransmitContext *tc;
  struct GNUNET_TIME_Relative rtimeout;
  int32_t numeric;

  size = ntohs (message->size);
  if (size < sizeof (struct AddressLookupMessage))
  {
    GNUNET_break_op (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  alum = (const struct AddressLookupMessage *) message;
  uint32_t addressLen = ntohl (alum->addrlen);

  if (size <= sizeof (struct AddressLookupMessage) + addressLen)
  {
    GNUNET_break_op (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  address = (const char *) &alum[1];
  nameTransport = (const char *) &address[addressLen];
  if (nameTransport
      [size - sizeof (struct AddressLookupMessage) - addressLen - 1] != '\0')
  {
    GNUNET_break_op (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  rtimeout = GNUNET_TIME_relative_ntoh (alum->timeout);
  numeric = ntohl (alum->numeric_only);
  lsPlugin = find_transport (nameTransport);
  if (NULL == lsPlugin)
  {
    tc = GNUNET_SERVER_transmit_context_create (client);
    GNUNET_SERVER_transmit_context_append_data (tc, NULL, 0,
                                                GNUNET_MESSAGE_TYPE_TRANSPORT_ADDRESS_REPLY);
    GNUNET_SERVER_transmit_context_run (tc, rtimeout);
    return;
  }
  GNUNET_SERVER_disable_receive_done_warning (client);
  tc = GNUNET_SERVER_transmit_context_create (client);
  lsPlugin->api->address_pretty_printer (lsPlugin->api->cls,
                                         nameTransport,
                                         address, addressLen,
                                         numeric,
                                         rtimeout,
                                         &transmit_address_to_client, tc);
}

/**
 * Handle PeerAddressLookupMessage.
 *
 * @param cls closure (always NULL)
 * @param client identification of the client
 * @param message the actual message
 */
static void
handle_peer_address_lookup (void *cls,
                            struct GNUNET_SERVER_Client *client,
                            const struct GNUNET_MessageHeader *message)
{
  const struct PeerAddressLookupMessage *peer_address_lookup;
  struct NeighbourMapEntry *neighbor_iterator;
  struct ReadyList *ready_iterator;
  struct ForeignAddressList *foreign_address_iterator;
  struct TransportPlugin *transport_plugin;

  uint16_t size;
  struct GNUNET_SERVER_TransmitContext *tc;
  struct GNUNET_TIME_Relative rtimeout;
  char *addr_buf;

  size = ntohs (message->size);
  if (size < sizeof (struct PeerAddressLookupMessage))
  {
    GNUNET_break_op (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  peer_address_lookup = (const struct PeerAddressLookupMessage *) message;

  rtimeout = GNUNET_TIME_relative_ntoh (peer_address_lookup->timeout);

  neighbor_iterator = find_neighbour (&peer_address_lookup->peer);

  /* Found no neighbor matching this peer id (shouldn't be possible, but...) */
  if (neighbor_iterator == NULL)
  {
    GNUNET_break (0);
    tc = GNUNET_SERVER_transmit_context_create (client);
    GNUNET_SERVER_transmit_context_append_data (tc, NULL, 0,
                                                GNUNET_MESSAGE_TYPE_TRANSPORT_ADDRESS_REPLY);
    GNUNET_SERVER_transmit_context_run (tc, rtimeout);
    return;
  }

  ready_iterator = neighbor_iterator->plugins;
  GNUNET_SERVER_disable_receive_done_warning (client);
  tc = GNUNET_SERVER_transmit_context_create (client);
  while (ready_iterator != NULL)
  {
    foreign_address_iterator = ready_iterator->addresses;
    while (foreign_address_iterator != NULL)
    {
      transport_plugin = foreign_address_iterator->ready_list->plugin;
      if (foreign_address_iterator->addr != NULL)
      {
        GNUNET_asprintf (&addr_buf, "%s --- %s, %s",
                         a2s (transport_plugin->short_name,
                              foreign_address_iterator->addr,
                              foreign_address_iterator->addrlen),
                         (foreign_address_iterator->connected
                          == GNUNET_YES) ? "CONNECTED"
                         : "DISCONNECTED",
                         (foreign_address_iterator->validated
                          == GNUNET_YES) ? "VALIDATED" : "UNVALIDATED");
        transmit_address_to_client (tc, addr_buf);
        GNUNET_free (addr_buf);
      }
      else if (foreign_address_iterator->addrlen == 0)
      {
        GNUNET_asprintf (&addr_buf, "%s --- %s, %s", "<inbound>",
                         (foreign_address_iterator->connected
                          == GNUNET_YES) ? "CONNECTED"
                         : "DISCONNECTED",
                         (foreign_address_iterator->validated
                          == GNUNET_YES) ? "VALIDATED" : "UNVALIDATED");
        transmit_address_to_client (tc, addr_buf);
        GNUNET_free (addr_buf);
      }

      foreign_address_iterator = foreign_address_iterator->next;
    }
    ready_iterator = ready_iterator->next;
  }
  GNUNET_SERVER_transmit_context_append_data (tc, NULL, 0,
                                              GNUNET_MESSAGE_TYPE_TRANSPORT_ADDRESS_REPLY);
  GNUNET_SERVER_transmit_context_run (tc, GNUNET_TIME_UNIT_FOREVER_REL);
}



static int
output_addresses (void *cls, const GNUNET_HashCode * key, void *value)
{
  struct GNUNET_SERVER_TransmitContext *tc = cls;
  struct NeighbourMapEntry *neighbor_iterator = value;
  struct ForeignAddressList *foreign_address_iterator;
  struct TransportPlugin *transport_plugin;
  struct ReadyList *ready_iterator;
  char *addr_buf;

  ready_iterator = neighbor_iterator->plugins;
  while (ready_iterator != NULL)
  {
    foreign_address_iterator = ready_iterator->addresses;
    while (foreign_address_iterator != NULL)
    {
      transport_plugin = foreign_address_iterator->ready_list->plugin;
      if (foreign_address_iterator->addr != NULL)
      {
        GNUNET_asprintf (&addr_buf, "%s:%s --- %s, %s",
                         GNUNET_i2s (&neighbor_iterator->id),
                         a2s (transport_plugin->short_name,
                              foreign_address_iterator->addr,
                              foreign_address_iterator->addrlen),
                         (foreign_address_iterator->connected
                          == GNUNET_YES) ? "CONNECTED"
                         : "DISCONNECTED",
                         (foreign_address_iterator->validated
                          == GNUNET_YES) ? "VALIDATED" : "UNVALIDATED");
        transmit_address_to_client (tc, addr_buf);
        GNUNET_free (addr_buf);
      }
      else if (foreign_address_iterator->addrlen == 0)
      {
        GNUNET_asprintf (&addr_buf, "%s:%s --- %s, %s",
                         GNUNET_i2s (&neighbor_iterator->id),
                         "<inbound>",
                         (foreign_address_iterator->connected
                          == GNUNET_YES) ? "CONNECTED"
                         : "DISCONNECTED",
                         (foreign_address_iterator->validated
                          == GNUNET_YES) ? "VALIDATED" : "UNVALIDATED");
        transmit_address_to_client (tc, addr_buf);
        GNUNET_free (addr_buf);
      }

      foreign_address_iterator = foreign_address_iterator->next;
    }
    ready_iterator = ready_iterator->next;
  }
  return GNUNET_OK;
}


/**
 * Handle AddressIterateMessage
 *
 * @param cls closure (always NULL)
 * @param client identification of the client
 * @param message the actual message
 */
static void
handle_address_iterate (void *cls,
                        struct GNUNET_SERVER_Client *client,
                        const struct GNUNET_MessageHeader *message)
{
  struct GNUNET_SERVER_TransmitContext *tc;
  uint16_t size;

  size = ntohs (message->size);
  if (size < sizeof (struct AddressIterateMessage))
  {
    GNUNET_break_op (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  GNUNET_SERVER_disable_receive_done_warning (client);
  tc = GNUNET_SERVER_transmit_context_create (client);
  GNUNET_CONTAINER_multihashmap_iterate (neighbours, &output_addresses, tc);
  GNUNET_SERVER_transmit_context_append_data (tc, NULL, 0,
                                              GNUNET_MESSAGE_TYPE_TRANSPORT_ADDRESS_REPLY);
  GNUNET_SERVER_transmit_context_run (tc, GNUNET_TIME_UNIT_FOREVER_REL);
}


static const struct GNUNET_MessageHeader *
do_get_our_hello ()
{
  return (const struct GNUNET_MessageHeader *) our_hello;
}


/**
 * Setup the environment for this plugin.
 */
static void
create_environment (struct TransportPlugin *plug)
{
  plug->env.cfg = cfg;
  plug->env.my_identity = &my_identity;
  plug->env.get_our_hello = &do_get_our_hello;
  plug->env.cls = plug;
  plug->env.receive = &plugin_env_receive;
  plug->env.notify_address = &plugin_env_notify_address;
  plug->env.session_end = &plugin_env_session_end;
  plug->env.max_connections = max_connect_per_transport;
  plug->env.stats = stats;
}


/**
 * Start the specified transport (load the plugin).
 */
static void
start_transport (struct GNUNET_SERVER_Handle *server, const char *name)
{
  struct TransportPlugin *plug;
  char *libname;

  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              _("Loading `%s' transport plugin\n"), name);
  GNUNET_asprintf (&libname, "libgnunet_plugin_transport_%s", name);
  plug = GNUNET_malloc (sizeof (struct TransportPlugin));
  create_environment (plug);
  plug->short_name = GNUNET_strdup (name);
  plug->lib_name = libname;
  plug->next = plugins;
  plugins = plug;
  plug->api = GNUNET_PLUGIN_load (libname, &plug->env);
  if (plug->api == NULL)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                _("Failed to load transport plugin for `%s'\n"), name);
    GNUNET_free (plug->short_name);
    plugins = plug->next;
    GNUNET_free (libname);
    GNUNET_free (plug);
  }
}


static int
null_mq_client_pointers (void *cls, const GNUNET_HashCode * key, void *value)
{
  struct TransportClient *pos = cls;
  struct NeighbourMapEntry *n = value;
  struct MessageQueue *mq;

  for (mq = n->messages_head; mq != NULL; mq = mq->next)
  {
    if (mq->client == pos)
      mq->client = NULL;        /* do not use anymore! */
  }
  return GNUNET_OK;
}


/**
 * Called whenever a client is disconnected.  Frees our
 * resources associated with that client.
 *
 * @param cls closure
 * @param client identification of the client
 */
static void
client_disconnect_notification (void *cls, struct GNUNET_SERVER_Client *client)
{
  struct TransportClient *pos;
  struct TransportClient *prev;
  struct ClientMessageQueueEntry *mqe;
  struct Blacklisters *bl;
  struct BlacklistCheck *bc;

  if (client == NULL)
    return;
#if DEBUG_TRANSPORT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG | GNUNET_ERROR_TYPE_BULK,
              "Client disconnected, cleaning up.\n");
#endif
  /* clean up blacklister */
  bl = bl_head;
  while (bl != NULL)
  {
    if (bl->client == client)
    {
      bc = bc_head;
      while (bc != NULL)
      {
        if (bc->bl_pos == bl)
        {
          bc->bl_pos = bl->next;
          if (bc->th != NULL)
          {
            GNUNET_CONNECTION_notify_transmit_ready_cancel (bc->th);
            bc->th = NULL;
          }
          if (bc->task == GNUNET_SCHEDULER_NO_TASK)
            bc->task = GNUNET_SCHEDULER_add_now (&do_blacklist_check, bc);
          break;
        }
        bc = bc->next;
      }
      GNUNET_CONTAINER_DLL_remove (bl_head, bl_tail, bl);
      GNUNET_SERVER_client_drop (bl->client);
      GNUNET_free (bl);
      break;
    }
    bl = bl->next;
  }
  /* clean up 'normal' clients */
  prev = NULL;
  pos = clients;
  while ((pos != NULL) && (pos->client != client))
  {
    prev = pos;
    pos = pos->next;
  }
  if (pos == NULL)
    return;
  while (NULL != (mqe = pos->message_queue_head))
  {
    GNUNET_CONTAINER_DLL_remove (pos->message_queue_head,
                                 pos->message_queue_tail, mqe);
    pos->message_count--;
    GNUNET_free (mqe);
  }
  if (NULL != neighbours)
    GNUNET_CONTAINER_multihashmap_iterate (neighbours,
                                           &null_mq_client_pointers, pos);
  if (prev == NULL)
    clients = pos->next;
  else
    prev->next = pos->next;
  if (GNUNET_YES == pos->tcs_pending)
  {
    pos->client = NULL;
    return;
  }
  if (pos->th != NULL)
  {
    GNUNET_CONNECTION_notify_transmit_ready_cancel (pos->th);
    pos->th = NULL;
  }
  GNUNET_break (0 == pos->message_count);
  GNUNET_free (pos);
}


static int
disconnect_all_neighbours (void *cls, const GNUNET_HashCode * key, void *value)
{
  struct NeighbourMapEntry *n = value;

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


/**
 * Function called when the service shuts down.  Unloads our plugins
 * and cancels pending validations.
 *
 * @param cls closure, unused
 * @param tc task context (unused)
 */
static void
shutdown_task (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct TransportPlugin *plug;
  struct OwnAddressList *al;
  struct CheckHelloValidatedContext *chvc;

  shutdown_in_progress = GNUNET_YES;
  GNUNET_CONTAINER_multihashmap_iterate (neighbours,
                                         &disconnect_all_neighbours, NULL);
#if DEBUG_TRANSPORT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Transport service is unloading plugins...\n");
#endif
  while (NULL != (plug = plugins))
  {
    if (plug->address_update_task != GNUNET_SCHEDULER_NO_TASK)
    {
      GNUNET_SCHEDULER_cancel (plug->address_update_task);
      plug->address_update_task = GNUNET_SCHEDULER_NO_TASK;
    }
    GNUNET_break (NULL == GNUNET_PLUGIN_unload (plug->lib_name, plug->api));
    GNUNET_free (plug->lib_name);
    GNUNET_free (plug->short_name);
    while (NULL != (al = plug->addresses))
    {
      plug->addresses = al->next;
      GNUNET_free (al);
    }
    plugins = plug->next;
    GNUNET_free (plug);
  }
  if (my_private_key != NULL)
    GNUNET_CRYPTO_rsa_key_free (my_private_key);
  GNUNET_free_non_null (our_hello);

  GNUNET_CONTAINER_multihashmap_iterate (validation_map,
                                         &abort_validation, NULL);
  GNUNET_CONTAINER_multihashmap_destroy (validation_map);
  validation_map = NULL;


  if (ats_task != GNUNET_SCHEDULER_NO_TASK)
  {
    GNUNET_SCHEDULER_cancel (ats_task);
    ats_task = GNUNET_SCHEDULER_NO_TASK;
  }
#if HAVE_LIBGLPK
  if (ats != NULL)
    ats_shutdown (ats);
#endif

  /* free 'chvc' data structure */
  while (NULL != (chvc = chvc_head))
  {
    chvc_head = chvc->next;
    if (chvc->piter != NULL)
    {
      GNUNET_PEERINFO_iterate_cancel (chvc->piter);
      GNUNET_STATISTICS_update (stats,
                                gettext_noop
                                ("# outstanding peerinfo iterate requests"), -1,
                                GNUNET_NO);
      chvc->ve_count--;
    }
    else
      GNUNET_break (0);
    GNUNET_assert (chvc->ve_count == 0);
    GNUNET_free (chvc);
  }
  chvc_tail = NULL;

  if (stats != NULL)
  {
    GNUNET_STATISTICS_destroy (stats, GNUNET_NO);
    stats = NULL;
  }
  if (peerinfo != NULL)
  {
    GNUNET_PEERINFO_disconnect (peerinfo);
    peerinfo = NULL;
  }
  if (GNUNET_SCHEDULER_NO_TASK != hello_task)
  {
    GNUNET_SCHEDULER_cancel (hello_task);
    hello_task = GNUNET_SCHEDULER_NO_TASK;
  }
  /* Can we assume those are gone by now, or do we need to clean up
   * explicitly!? */
  GNUNET_break (bl_head == NULL);
  GNUNET_break (bc_head == NULL);
  GNUNET_CONTAINER_multihashmap_destroy (neighbours);
  neighbours = NULL;
}


void
ats_result_cb ()
{
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "ATS Result callback\n");
}


#if HAVE_LIBGLPK
struct AtsBuildContext
{
  struct ATS_mechanism *mechanisms;
  struct ATS_peer *peers;
  int c_peers;
  int c_mechs;
};


static int
find_and_count_addresses (void *cls, const GNUNET_HashCode * key, void *value)
{
  struct AtsBuildContext *abc = cls;
  struct NeighbourMapEntry *next = value;
  int found_addresses = GNUNET_NO;

  struct ReadyList *r_next = next->plugins;

  while (r_next != NULL)
  {
    struct ForeignAddressList *a_next = r_next->addresses;

    while (a_next != NULL)
    {
      abc->c_mechs++;
      found_addresses = GNUNET_YES;
      a_next = a_next->next;
    }
    r_next = r_next->next;
  }
  if (found_addresses)
    abc->c_peers++;
  return GNUNET_OK;
}


static int
setup_ats_problem (void *cls, const GNUNET_HashCode * key, void *value)
{
  struct AtsBuildContext *abc = cls;
  struct NeighbourMapEntry *next = value;

  int found_addresses = GNUNET_NO;
  struct ReadyList *r_next = next->plugins;

  while (r_next != NULL)
  {
    struct ForeignAddressList *a_next = r_next->addresses;

    while (a_next != NULL)
    {
      if (found_addresses == GNUNET_NO)
      {
        abc->peers[abc->c_peers].peer = next->id;
        abc->peers[abc->c_peers].m_head = NULL;
        abc->peers[abc->c_peers].m_tail = NULL;
        abc->peers[abc->c_peers].f = 1.0 / abc->c_mechs;
      }
      abc->mechanisms[abc->c_mechs].addr = a_next;
      abc->mechanisms[abc->c_mechs].col_index = abc->c_mechs;
      abc->mechanisms[abc->c_mechs].peer = &abc->peers[abc->c_peers];
      abc->mechanisms[abc->c_mechs].next = NULL;
      abc->mechanisms[abc->c_mechs].plugin = r_next->plugin;
      abc->mechanisms[abc->c_mechs].ressources = a_next->ressources;
      abc->mechanisms[abc->c_mechs].quality = a_next->quality;
      GNUNET_CONTAINER_DLL_insert_tail (abc->peers[abc->c_peers].m_head,
                                        abc->peers[abc->c_peers].m_tail,
                                        &abc->mechanisms[abc->c_mechs]);
      found_addresses = GNUNET_YES;
      abc->c_mechs++;
      a_next = a_next->next;
    }
    r_next = r_next->next;
  }
  if (found_addresses == GNUNET_YES)
    abc->c_peers++;
  return GNUNET_OK;
}


static void
create_ats_information (struct ATS_peer **p,
                        int *c_p, struct ATS_mechanism **m, int *c_m)
{
  struct AtsBuildContext abc;

#if VERBOSE_ATS
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "ATS requires clean address information\n");
#endif
  abc.c_peers = 0;
  abc.c_mechs = 0;
  GNUNET_CONTAINER_multihashmap_iterate (neighbours,
                                         &find_and_count_addresses, &abc);
#if VERBOSE_ATS
  GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
              "Found %u peers with % u transport mechanisms\n", c_peers,
              c_mechs);
#endif

  if ((abc.c_peers == 0) && (abc.c_mechs == 0))
  {
    *p = NULL;
    (*c_p) = 0;
    *m = NULL;
    (*c_m) = 0;
    return;
  }

  abc.mechanisms =
      GNUNET_malloc ((1 + abc.c_mechs) * sizeof (struct ATS_mechanism));
  abc.peers = GNUNET_malloc ((1 + abc.c_peers) * sizeof (struct ATS_peer));
  abc.c_mechs = 1;
  abc.c_peers = 1;
  GNUNET_CONTAINER_multihashmap_iterate (neighbours, &setup_ats_problem, &abc);
  abc.c_mechs--;
  abc.c_peers--;
  (*c_m) = abc.c_mechs;
  (*c_p) = abc.c_peers;
  (*p) = abc.peers;
  (*m) = abc.mechanisms;
}


static void
schedule_ats (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct ATS_Handle *ats = (struct ATS_Handle *) cls;

  if (ats == NULL)
    return;

  ats_task = GNUNET_SCHEDULER_NO_TASK;
  if ((tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN) != 0)
    return;

  if (shutdown_in_progress == GNUNET_YES)
    return;

  struct GNUNET_TIME_Relative delta =
      GNUNET_TIME_absolute_get_difference (last_ats_execution,
                                           GNUNET_TIME_absolute_get ());

  if (delta.rel_value < ats_minimum_interval.rel_value)
  {
#if DEBUG_ATS
    GNUNET_log (GNUNET_ERROR_TYPE_BULK,
                "Minimum time between cycles not reached\n");
#endif
    return;
  }

#if DEBUG_ATS
  GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Running scheduled calculation\n");
#endif
#if HAVE_LIBGLPK
  ats_calculate_bandwidth_distribution (ats);
#endif
  last_ats_execution = GNUNET_TIME_absolute_get ();

  ats_task = GNUNET_SCHEDULER_add_delayed (ats_regular_interval,
                                           &schedule_ats, ats);
}
#endif


struct ForeignAddressList *
get_preferred_ats_address (struct NeighbourMapEntry *n)
{
  // TODO get ATS prefered address
  return find_ready_address (n);
}

/**
 * Initiate transport service.
 *
 * @param cls closure
 * @param server the initialized server
 * @param c configuration to use
 */
static void
run (void *cls,
     struct GNUNET_SERVER_Handle *server,
     const struct GNUNET_CONFIGURATION_Handle *c)
{
  static const struct GNUNET_SERVER_MessageHandler handlers[] = {
    {&handle_start, NULL,
     GNUNET_MESSAGE_TYPE_TRANSPORT_START, sizeof (struct StartMessage)},
    {&handle_hello, NULL,
     GNUNET_MESSAGE_TYPE_HELLO, 0},
    {&handle_send, NULL,
     GNUNET_MESSAGE_TYPE_TRANSPORT_SEND, 0},
    {&handle_request_connect, NULL,
     GNUNET_MESSAGE_TYPE_TRANSPORT_REQUEST_CONNECT,
     sizeof (struct TransportRequestConnectMessage)},
    {&handle_set_quota, NULL,
     GNUNET_MESSAGE_TYPE_TRANSPORT_SET_QUOTA, sizeof (struct QuotaSetMessage)},
    {&handle_address_lookup, NULL,
     GNUNET_MESSAGE_TYPE_TRANSPORT_ADDRESS_LOOKUP,
     0},
    {&handle_peer_address_lookup, NULL,
     GNUNET_MESSAGE_TYPE_TRANSPORT_PEER_ADDRESS_LOOKUP,
     0},
    {&handle_address_iterate, NULL,
     GNUNET_MESSAGE_TYPE_TRANSPORT_ADDRESS_ITERATE,
     0},
    {&handle_blacklist_init, NULL,
     GNUNET_MESSAGE_TYPE_TRANSPORT_BLACKLIST_INIT,
     sizeof (struct GNUNET_MessageHeader)},
    {&handle_blacklist_reply, NULL,
     GNUNET_MESSAGE_TYPE_TRANSPORT_BLACKLIST_REPLY,
     sizeof (struct BlacklistMessage)},
    {NULL, NULL, 0, 0}
  };
  char *plugs;
  char *pos;
  int no_transports;
  unsigned long long tneigh;
  char *keyfile;

  shutdown_in_progress = GNUNET_NO;
  cfg = c;
  stats = GNUNET_STATISTICS_create ("transport", cfg);
  validation_map = GNUNET_CONTAINER_multihashmap_create (64);
  neighbours = GNUNET_CONTAINER_multihashmap_create (256);
  /* parse configuration */
  if ((GNUNET_OK !=
       GNUNET_CONFIGURATION_get_value_number (c,
                                              "TRANSPORT",
                                              "NEIGHBOUR_LIMIT",
                                              &tneigh)) ||
      (GNUNET_OK !=
       GNUNET_CONFIGURATION_get_value_filename (c,
                                                "GNUNETD",
                                                "HOSTKEY", &keyfile)))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                _
                ("Transport service is lacking key configuration settings.  Exiting.\n"));
    GNUNET_SCHEDULER_shutdown ();
    if (stats != NULL)
    {
      GNUNET_STATISTICS_destroy (stats, GNUNET_NO);
      stats = NULL;
    }
    GNUNET_CONTAINER_multihashmap_destroy (validation_map);
    validation_map = NULL;
    GNUNET_CONTAINER_multihashmap_destroy (neighbours);
    neighbours = NULL;
    return;
  }

  max_connect_per_transport = (uint32_t) tneigh;
  peerinfo = GNUNET_PEERINFO_connect (cfg);
  if (peerinfo == NULL)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                _("Could not access PEERINFO service.  Exiting.\n"));
    GNUNET_SCHEDULER_shutdown ();
    if (stats != NULL)
    {
      GNUNET_STATISTICS_destroy (stats, GNUNET_NO);
      stats = NULL;
    }
    GNUNET_CONTAINER_multihashmap_destroy (validation_map);
    validation_map = NULL;
    GNUNET_CONTAINER_multihashmap_destroy (neighbours);
    neighbours = NULL;
    GNUNET_free (keyfile);
    return;
  }
  my_private_key = GNUNET_CRYPTO_rsa_key_create_from_file (keyfile);
  GNUNET_free (keyfile);
  if (my_private_key == NULL)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                _("Transport service could not access hostkey.  Exiting.\n"));
    GNUNET_SCHEDULER_shutdown ();
    if (stats != NULL)
    {
      GNUNET_STATISTICS_destroy (stats, GNUNET_NO);
      stats = NULL;
    }
    GNUNET_CONTAINER_multihashmap_destroy (validation_map);
    validation_map = NULL;
    GNUNET_CONTAINER_multihashmap_destroy (neighbours);
    neighbours = NULL;
    return;
  }
  GNUNET_CRYPTO_rsa_key_get_public (my_private_key, &my_public_key);
  GNUNET_CRYPTO_hash (&my_public_key,
                      sizeof (my_public_key), &my_identity.hashPubKey);
  /* setup notification */
  GNUNET_SERVER_disconnect_notify (server,
                                   &client_disconnect_notification, NULL);
  /* load plugins... */
  no_transports = 1;
  if (GNUNET_OK ==
      GNUNET_CONFIGURATION_get_value_string (c, "TRANSPORT", "PLUGINS", &plugs))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                _("Starting transport plugins `%s'\n"), plugs);
    pos = strtok (plugs, " ");
    while (pos != NULL)
    {
      start_transport (server, pos);
      no_transports = 0;
      pos = strtok (NULL, " ");
    }
    GNUNET_free (plugs);
  }
  GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_FOREVER_REL,
                                &shutdown_task, NULL);
  if (no_transports)
    refresh_hello ();

  /* Initializing ATS */
  int co;
  char *section;
  unsigned long long value;

#if HAVE_LIBGLPK
  double D = 1.0;
  double U = 1.0;
  double R = 1.0;
  int v_b_min = 64000;
  int v_n_min = 5;
#endif

  ats_minimum_interval = ATS_MIN_INTERVAL;
  ats_regular_interval = ATS_EXEC_INTERVAL;

  /* loading cost ressources */
  for (co = 0; co < available_ressources; co++)
  {
    GNUNET_asprintf (&section, "%s_UP", ressources[co].cfg_param);
    if (GNUNET_CONFIGURATION_have_value (cfg, "transport", section))
    {
      if (GNUNET_OK == GNUNET_CONFIGURATION_get_value_number (cfg,
                                                              "transport",
                                                              section, &value))
      {
#if DEBUG_ATS
        GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                    "Found ressource cost: [%s] = %llu\n", section, value);
#endif
        ressources[co].c_max = value;
      }
    }
    GNUNET_free (section);
    GNUNET_asprintf (&section, "%s_DOWN", ressources[co].cfg_param);
    if (GNUNET_CONFIGURATION_have_value (cfg, "transport", section))
    {
      if (GNUNET_OK == GNUNET_CONFIGURATION_get_value_number (cfg,
                                                              "transport",
                                                              section, &value))
      {
#if DEBUG_ATS
        GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                    "Found ressource cost: [%s] = %llu\n", section, value);
#endif
        ressources[co].c_min = value;
      }
    }
    GNUNET_free (section);
  }
#if HAVE_LIBGLPK
  ats = ats_init (D, U, R, v_b_min, v_n_min,
                  ATS_MAX_ITERATIONS, ATS_MAX_EXEC_DURATION,
                  &create_ats_information, ats_result_cb);
  ats_set_logging_options (ats, stats, cfg);
  GNUNET_break (GNUNET_OK ==
                GNUNET_CONFIGURATION_get_value_time (cfg,
                                                     "transport",
                                                     "ATS_EXEC_INTERVAL",
                                                     &ats_regular_interval));
  GNUNET_break (GNUNET_OK ==
                GNUNET_CONFIGURATION_get_value_time (cfg,
                                                     "transport",
                                                     "ATS_MIN_INTERVAL",
                                                     &ats_minimum_interval));
  if (ats != NULL)
    ats_task = GNUNET_SCHEDULER_add_now (&schedule_ats, ats);
#endif


#if DEBUG_TRANSPORT
  GNUNET_log (GNUNET_ERROR_TYPE_INFO, _("Transport service ready.\n"));
#endif
  /* If we have a blacklist file, read from it */
  read_blacklist_file (cfg);
  /* process client requests */
  GNUNET_SERVER_add_handlers (server, handlers);
}


/**
 * The main function for the transport service.
 *
 * @param argc number of arguments from the command line
 * @param argv command line arguments
 * @return 0 ok, 1 on error
 */
int
main (int argc, char *const *argv)
{
  a2s (NULL, NULL, 0);          /* make compiler happy */
  return (GNUNET_OK ==
          GNUNET_SERVICE_run (argc,
                              argv,
                              "transport",
                              GNUNET_SERVICE_OPTION_NONE, &run, NULL)) ? 0 : 1;
}

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