even nicer indentation, thanks to LRN's indent patch

[oweals/gnunet.git] / src / core / gnunet-service-core.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 core/gnunet-service-core.c
 * @brief high-level P2P messaging
 * @author Christian Grothoff
 *
 * Type map implementation:
 * - track type maps for neighbours (can wait)
 * - only notify clients about peers with matching type maps (can wait)
 *
 * Considerations for later:
 * - check that hostkey used by transport (for HELLOs) is the
 *   same as the hostkey that we are using!
 */
#include "platform.h"
#include <zlib.h>
#include "gnunet_constants.h"
#include "gnunet_util_lib.h"
#include "gnunet_hello_lib.h"
#include "gnunet_peerinfo_service.h"
#include "gnunet_protocols.h"
#include "gnunet_signatures.h"
#include "gnunet_statistics_service.h"
#include "gnunet_transport_service.h"
#include "core.h"


#define DEBUG_HANDSHAKE GNUNET_NO

#define DEBUG_CORE_QUOTA GNUNET_NO

/**
 * Receive and send buffer windows grow over time.  For
 * how long can 'unused' bandwidth accumulate before we
 * need to cap it?  (specified in seconds).
 */
#define MAX_WINDOW_TIME_S (5 * 60)

/**
 * How many messages do we queue up at most for optional
 * notifications to a client?  (this can cause notifications
 * about outgoing messages to be dropped).
 */
#define MAX_NOTIFY_QUEUE 1024

/**
 * Minimum bandwidth (out) to assign to any connected peer.
 * Should be rather low; values larger than DEFAULT_BW_IN_OUT make no
 * sense.
 */
#define MIN_BANDWIDTH_PER_PEER GNUNET_CONSTANTS_DEFAULT_BW_IN_OUT

/**
 * After how much time past the "official" expiration time do
 * we discard messages?  Should not be zero since we may 
 * intentionally defer transmission until close to the deadline
 * and then may be slightly past the deadline due to inaccuracy
 * in sleep and our own CPU consumption.
 */
#define PAST_EXPIRATION_DISCARD_TIME GNUNET_TIME_UNIT_SECONDS

/**
 * What is the maximum delay for a SET_KEY message?
 */
#define MAX_SET_KEY_DELAY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 10)

/**
 * How long do we wait for SET_KEY confirmation initially?
 */
#define INITIAL_SET_KEY_RETRY_FREQUENCY GNUNET_TIME_relative_multiply (MAX_SET_KEY_DELAY, 1)

/**
 * What is the maximum delay for a PING message?
 */
#define MAX_PING_DELAY GNUNET_TIME_relative_multiply (MAX_SET_KEY_DELAY, 2)

/**
 * What is the maximum delay for a PONG message?
 */
#define MAX_PONG_DELAY GNUNET_TIME_relative_multiply (MAX_PING_DELAY, 2)

/**
 * What is the minimum frequency for a PING message?
 */
#define MIN_PING_FREQUENCY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 5)

/**
 * How often do we recalculate bandwidth quotas?
 */
#define QUOTA_UPDATE_FREQUENCY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 5)

/**
 * What is the priority for a SET_KEY message?
 */
#define SET_KEY_PRIORITY 0xFFFFFF

/**
 * What is the priority for a PING message?
 */
#define PING_PRIORITY 0xFFFFFF

/**
 * What is the priority for a PONG message?
 */
#define PONG_PRIORITY 0xFFFFFF

/**
 * How many messages do we queue per peer at most?  Must be at
 * least two.
 */
#define MAX_PEER_QUEUE_SIZE 16

/**
 * How many non-mandatory messages do we queue per client at most?
 */
#define MAX_CLIENT_QUEUE_SIZE 32

/**
 * What is the maximum age of a message for us to consider
 * processing it?  Note that this looks at the timestamp used
 * by the other peer, so clock skew between machines does
 * come into play here.  So this should be picked high enough
 * so that a little bit of clock skew does not prevent peers
 * from connecting to us.
 */
#define MAX_MESSAGE_AGE GNUNET_TIME_UNIT_DAYS


/**
 * State machine for our P2P encryption handshake.  Everyone starts in
 * "DOWN", if we receive the other peer's key (other peer initiated)
 * we start in state RECEIVED (since we will immediately send our
 * own); otherwise we start in SENT.  If we get back a PONG from
 * within either state, we move up to CONFIRMED (the PONG will always
 * be sent back encrypted with the key we sent to the other peer).
 */
enum PeerStateMachine
{
  /**
   * No handshake yet.
   */
  PEER_STATE_DOWN,

  /**
   * We've sent our session key.
   */
  PEER_STATE_KEY_SENT,

  /**
   * We've received the other peers session key.
   */
  PEER_STATE_KEY_RECEIVED,

  /**
   * The other peer has confirmed our session key with a message
   * encrypted with his session key (which we got).  Session is now fully up.
   */
  PEER_STATE_KEY_CONFIRMED
};


/**
 * Encapsulation for encrypted messages exchanged between
 * peers.  Followed by the actual encrypted data.
 */
struct EncryptedMessage
{
  /**
   * Message type is either CORE_ENCRYPTED_MESSAGE.
   */
  struct GNUNET_MessageHeader header;

  /**
   * Random value used for IV generation.
   */
  uint32_t iv_seed GNUNET_PACKED;

  /**
   * MAC of the encrypted message (starting at 'sequence_number'),
   * used to verify message integrity. Everything after this value
   * (excluding this value itself) will be encrypted and authenticated.
   * ENCRYPTED_HEADER_SIZE must be set to the offset of the *next* field.
   */
  GNUNET_HashCode hmac;

  /**
   * Sequence number, in network byte order.  This field
   * must be the first encrypted/decrypted field
   */
  uint32_t sequence_number GNUNET_PACKED;

  /**
   * Desired bandwidth (how much we should send to this peer / how
   * much is the sender willing to receive)?
   */
  struct GNUNET_BANDWIDTH_Value32NBO inbound_bw_limit;

  /**
   * Timestamp.  Used to prevent reply of ancient messages
   * (recent messages are caught with the sequence number).
   */
  struct GNUNET_TIME_AbsoluteNBO timestamp;

};


/**
 * Number of bytes (at the beginning) of "struct EncryptedMessage"
 * that are NOT encrypted.
 */
#define ENCRYPTED_HEADER_SIZE (offsetof(struct EncryptedMessage, sequence_number))


/**
 * We're sending an (encrypted) PING to the other peer to check if he
 * can decrypt.  The other peer should respond with a PONG with the
 * same content, except this time encrypted with the receiver's key.
 */
struct PingMessage
{
  /**
   * Message type is CORE_PING.
   */
  struct GNUNET_MessageHeader header;

  /**
   * Seed for the IV
   */
  uint32_t iv_seed GNUNET_PACKED;

  /**
   * Intended target of the PING, used primarily to check
   * that decryption actually worked.
   */
  struct GNUNET_PeerIdentity target;

  /**
   * Random number chosen to make reply harder.
   */
  uint32_t challenge GNUNET_PACKED;
};



/**
 * Response to a PING.  Includes data from the original PING
 * plus initial bandwidth quota information.
 */
struct PongMessage
{
  /**
   * Message type is CORE_PONG.
   */
  struct GNUNET_MessageHeader header;

  /**
   * Seed for the IV
   */
  uint32_t iv_seed GNUNET_PACKED;

  /**
   * Random number to make faking the reply harder.  Must be
   * first field after header (this is where we start to encrypt!).
   */
  uint32_t challenge GNUNET_PACKED;

  /**
   * Desired bandwidth (how much we should send to this
   * peer / how much is the sender willing to receive).
   */
  struct GNUNET_BANDWIDTH_Value32NBO inbound_bw_limit;

  /**
   * Intended target of the PING, used primarily to check
   * that decryption actually worked.
   */
  struct GNUNET_PeerIdentity target;
};


/**
 * Message transmitted to set (or update) a session key.
 */
struct SetKeyMessage
{

  /**
   * Message type is either CORE_SET_KEY.
   */
  struct GNUNET_MessageHeader header;

  /**
   * Status of the sender (should be in "enum PeerStateMachine"), nbo.
   */
  int32_t sender_status GNUNET_PACKED;

  /**
   * Purpose of the signature, will be
   * GNUNET_SIGNATURE_PURPOSE_SET_KEY.
   */
  struct GNUNET_CRYPTO_RsaSignaturePurpose purpose;

  /**
   * At what time was this key created?
   */
  struct GNUNET_TIME_AbsoluteNBO creation_time;

  /**
   * The encrypted session key.
   */
  struct GNUNET_CRYPTO_RsaEncryptedData encrypted_key;

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

  /**
   * Signature of the stuff above (starting at purpose).
   */
  struct GNUNET_CRYPTO_RsaSignature signature;

};


/**
 * Message waiting for transmission. This struct
 * is followed by the actual content of the message.
 */
struct MessageEntry
{

  /**
   * We keep messages in a doubly linked list.
   */
  struct MessageEntry *next;

  /**
   * We keep messages in a doubly linked list.
   */
  struct MessageEntry *prev;

  /**
   * By when are we supposed to transmit this message?
   */
  struct GNUNET_TIME_Absolute deadline;

  /**
   * By when are we supposed to transmit this message (after
   * giving slack)?
   */
  struct GNUNET_TIME_Absolute slack_deadline;

  /**
   * How important is this message to us?
   */
  unsigned int priority;

  /**
   * If this is a SET_KEY message, what was our connection status when this
   * message was queued?
   */
  enum PeerStateMachine sender_status;

  /**
   * Is this a SET_KEY message?
   */
  int is_setkey;

  /**
   * How long is the message? (number of bytes following
   * the "struct MessageEntry", but not including the
   * size of "struct MessageEntry" itself!)
   */
  uint16_t size;

  /**
   * Was this message selected for transmission in the
   * current round? GNUNET_YES or GNUNET_NO.
   */
  int8_t do_transmit;

  /**
   * Did we give this message some slack (delayed sending) previously
   * (and hence should not give it any more slack)? GNUNET_YES or
   * GNUNET_NO.
   */
  int8_t got_slack;

};


/**
 * Record kept for each request for transmission issued by a 
 * client that is still pending.
 */
struct ClientActiveRequest;

/**
 * Data kept per neighbouring peer.
 */
struct Neighbour
{

  /**
   * Unencrypted messages destined for this peer.
   */
  struct MessageEntry *messages;

  /**
   * Head of the batched, encrypted message queue (already ordered,
   * transmit starting with the head).
   */
  struct MessageEntry *encrypted_head;

  /**
   * Tail of the batched, encrypted message queue (already ordered,
   * append new messages to tail)
   */
  struct MessageEntry *encrypted_tail;

  /**
   * Head of list of requests from clients for transmission to 
   * this peer.
   */
  struct ClientActiveRequest *active_client_request_head;

  /**
   * Tail of list of requests from clients for transmission to 
   * this peer.
   */
  struct ClientActiveRequest *active_client_request_tail;

  /**
   * Handle for pending requests for transmission to this peer
   * with the transport service.  NULL if no request is pending.
   */
  struct GNUNET_TRANSPORT_TransmitHandle *th;

  /**
   * Public key of the neighbour, NULL if we don't have it yet.
   */
  struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded *public_key;

  /**
   * We received a PING message before we got the "public_key"
   * (or the SET_KEY).  We keep it here until we have a key
   * to decrypt it.  NULL if no PING is pending.
   */
  struct PingMessage *pending_ping;

  /**
   * We received a PONG message before we got the "public_key"
   * (or the SET_KEY).  We keep it here until we have a key
   * to decrypt it.  NULL if no PONG is pending.
   */
  struct PongMessage *pending_pong;

  /**
   * Non-NULL if we are currently looking up HELLOs for this peer.
   * for this peer.
   */
  struct GNUNET_PEERINFO_IteratorContext *pitr;

  /**
   * SetKeyMessage to transmit, NULL if we are not currently trying
   * to send one.
   */
  struct SetKeyMessage *skm;

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

  /**
   * Identity of the neighbour.
   */
  struct GNUNET_PeerIdentity peer;

  /**
   * Key we use to encrypt our messages for the other peer
   * (initialized by us when we do the handshake).
   */
  struct GNUNET_CRYPTO_AesSessionKey encrypt_key;

  /**
   * Key we use to decrypt messages from the other peer
   * (given to us by the other peer during the handshake).
   */
  struct GNUNET_CRYPTO_AesSessionKey decrypt_key;

  /**
   * ID of task used for re-trying plaintext scheduling.
   */
  GNUNET_SCHEDULER_TaskIdentifier retry_plaintext_task;

  /**
   * ID of task used for re-trying SET_KEY and PING message.
   */
  GNUNET_SCHEDULER_TaskIdentifier retry_set_key_task;

  /**
   * ID of task used for updating bandwidth quota for this neighbour.
   */
  GNUNET_SCHEDULER_TaskIdentifier quota_update_task;

  /**
   * ID of task used for sending keep-alive pings.
   */
  GNUNET_SCHEDULER_TaskIdentifier keep_alive_task;

  /**
   * ID of task used for cleaning up dead neighbour entries.
   */
  GNUNET_SCHEDULER_TaskIdentifier dead_clean_task;

  /**
   * At what time did we generate our encryption key?
   */
  struct GNUNET_TIME_Absolute encrypt_key_created;

  /**
   * At what time did the other peer generate the decryption key?
   */
  struct GNUNET_TIME_Absolute decrypt_key_created;

  /**
   * At what time did we initially establish (as in, complete session
   * key handshake) this connection?  Should be zero if status != KEY_CONFIRMED.
   */
  struct GNUNET_TIME_Absolute time_established;

  /**
   * At what time did we last receive an encrypted message from the
   * other peer?  Should be zero if status != KEY_CONFIRMED.
   */
  struct GNUNET_TIME_Absolute last_activity;

  /**
   * At what frequency are we currently re-trying SET_KEY messages?
   */
  struct GNUNET_TIME_Relative set_key_retry_frequency;

  /**
   * Tracking bandwidth for sending to this peer.
   */
  struct GNUNET_BANDWIDTH_Tracker available_send_window;

  /**
   * Tracking bandwidth for receiving from this peer.
   */
  struct GNUNET_BANDWIDTH_Tracker available_recv_window;

  /**
   * How valueable were the messages of this peer recently?
   */
  unsigned long long current_preference;

  /**
   * Number of entries in 'ats'.
   */
  unsigned int ats_count;

  /**
   * Bit map indicating which of the 32 sequence numbers before the last
   * were received (good for accepting out-of-order packets and
   * estimating reliability of the connection)
   */
  unsigned int last_packets_bitmap;

  /**
   * last sequence number received on this connection (highest)
   */
  uint32_t last_sequence_number_received;

  /**
   * last sequence number transmitted
   */
  uint32_t last_sequence_number_sent;

  /**
   * Available bandwidth in for this peer (current target).
   */
  struct GNUNET_BANDWIDTH_Value32NBO bw_in;

  /**
   * Available bandwidth out for this peer (current target).
   */
  struct GNUNET_BANDWIDTH_Value32NBO bw_out;

  /**
   * Internal bandwidth limit set for this peer (initially typically
   * set to "-1").  Actual "bw_out" is MIN of
   * "bpm_out_internal_limit" and "bw_out_external_limit".
   */
  struct GNUNET_BANDWIDTH_Value32NBO bw_out_internal_limit;

  /**
   * External bandwidth limit set for this peer by the
   * peer that we are communicating with.  "bw_out" is MIN of
   * "bw_out_internal_limit" and "bw_out_external_limit".
   */
  struct GNUNET_BANDWIDTH_Value32NBO bw_out_external_limit;

  /**
   * What was our PING challenge number (for this peer)?
   */
  uint32_t ping_challenge;

  /**
   * What is our connection status?
   */
  enum PeerStateMachine status;

  /**
   * Are we currently connected to this neighbour?
   */
  int is_connected;

};


/**
 * Data structure for each client connected to the core service.
 */
struct Client
{
  /**
   * Clients are kept in a linked list.
   */
  struct Client *next;

  /**
   * Handle for the client with the server API.
   */
  struct GNUNET_SERVER_Client *client_handle;

  /**
   * Array of the types of messages this peer cares
   * about (with "tcnt" entries).  Allocated as part
   * of this client struct, do not free!
   */
  const uint16_t *types;

  /**
   * Map of peer identities to active transmission requests of this
   * client to the peer (of type 'struct ClientActiveRequest').
   */
  struct GNUNET_CONTAINER_MultiHashMap *requests;

  /**
   * Options for messages this client cares about,
   * see GNUNET_CORE_OPTION_ values.
   */
  uint32_t options;

  /**
   * Number of types of incoming messages this client
   * specifically cares about.  Size of the "types" array.
   */
  unsigned int tcnt;

};


/**
 * Record kept for each request for transmission issued by a 
 * client that is still pending.
 */
struct ClientActiveRequest
{

  /**
   * Active requests are kept in a doubly-linked list of
   * the respective target peer.
   */
  struct ClientActiveRequest *next;

  /**
   * Active requests are kept in a doubly-linked list of
   * the respective target peer.
   */
  struct ClientActiveRequest *prev;

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

  /**
   * By what time would the client want to see this message out?
   */
  struct GNUNET_TIME_Absolute deadline;

  /**
   * How important is this request.
   */
  uint32_t priority;

  /**
   * How many more requests does this client have?
   */
  uint32_t queue_size;

  /**
   * How many bytes does the client intend to send?
   */
  uint16_t msize;

  /**
   * Unique request ID (in big endian).
   */
  uint16_t smr_id;

};



/**
 * 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;

/**
 * Bitmap of message types this peer is able to handle.
 */
static uint32_t my_type_map[(UINT16_MAX + 1) / 32];

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

/**
 * Our message stream tokenizer (for encrypted payload).
 */
static struct GNUNET_SERVER_MessageStreamTokenizer *mst;

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

/**
 * Transport service.
 */
static struct GNUNET_TRANSPORT_Handle *transport;

/**
 * Linked list of our clients.
 */
static struct Client *clients;

/**
 * Context for notifications we need to send to our clients.
 */
static struct GNUNET_SERVER_NotificationContext *notifier;

/**
 * Map of peer identities to 'struct Neighbour'.
 */
static struct GNUNET_CONTAINER_MultiHashMap *neighbours;

/**
 * Neighbour entry for "this" peer.
 */
static struct Neighbour self;

/**
 * For creating statistics.
 */
static struct GNUNET_STATISTICS_Handle *stats;

/**
 * Sum of all preferences among all neighbours.
 */
static unsigned long long preference_sum;

/**
 * How much inbound bandwidth are we supposed to be using per second?
 */
static unsigned long long bandwidth_target_in_bps;

/**
 * How much outbound bandwidth are we supposed to be using per second?
 */
static unsigned long long bandwidth_target_out_bps;

/**
 * Derive an authentication key from "set key" information
 */
static void
derive_auth_key (struct GNUNET_CRYPTO_AuthKey *akey,
                 const struct GNUNET_CRYPTO_AesSessionKey *skey, uint32_t seed,
                 struct GNUNET_TIME_Absolute creation_time)
{
  static const char ctx[] = "authentication key";
  struct GNUNET_TIME_AbsoluteNBO ctbe;


  ctbe = GNUNET_TIME_absolute_hton (creation_time);
  GNUNET_CRYPTO_hmac_derive_key (akey, skey, &seed, sizeof (seed), &skey->key,
                                 sizeof (skey->key), &ctbe, sizeof (ctbe), ctx,
                                 sizeof (ctx), NULL);
}


/**
 * Derive an IV from packet information
 */
static void
derive_iv (struct GNUNET_CRYPTO_AesInitializationVector *iv,
           const struct GNUNET_CRYPTO_AesSessionKey *skey, uint32_t seed,
           const struct GNUNET_PeerIdentity *identity)
{
  static const char ctx[] = "initialization vector";

  GNUNET_CRYPTO_aes_derive_iv (iv, skey, &seed, sizeof (seed),
                               &identity->hashPubKey.bits,
                               sizeof (identity->hashPubKey.bits), ctx,
                               sizeof (ctx), NULL);
}

/**
 * Derive an IV from pong packet information
 */
static void
derive_pong_iv (struct GNUNET_CRYPTO_AesInitializationVector *iv,
                const struct GNUNET_CRYPTO_AesSessionKey *skey, uint32_t seed,
                uint32_t challenge, const struct GNUNET_PeerIdentity *identity)
{
  static const char ctx[] = "pong initialization vector";

  GNUNET_CRYPTO_aes_derive_iv (iv, skey, &seed, sizeof (seed),
                               &identity->hashPubKey.bits,
                               sizeof (identity->hashPubKey.bits), &challenge,
                               sizeof (challenge), ctx, sizeof (ctx), NULL);
}


/**
 * At what time should the connection to the given neighbour
 * time out (given no further activity?)
 *
 * @param n neighbour in question
 * @return absolute timeout
 */
static struct GNUNET_TIME_Absolute
get_neighbour_timeout (struct Neighbour *n)
{
  return GNUNET_TIME_absolute_add (n->last_activity,
                                   GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT);
}


/**
 * Helper function for update_preference_sum.
 */
static int
update_preference (void *cls, const GNUNET_HashCode * key, void *value)
{
  unsigned long long *ps = cls;
  struct Neighbour *n = value;

  n->current_preference /= 2;
  *ps += n->current_preference;
  return GNUNET_OK;
}


/**
 * A preference value for a neighbour was update.  Update
 * the preference sum accordingly.
 *
 * @param inc how much was a preference value increased?
 */
static void
update_preference_sum (unsigned long long inc)
{
  unsigned long long os;

  os = preference_sum;
  preference_sum += inc;
  if (preference_sum >= os)
    return;                     /* done! */
  /* overflow! compensate by cutting all values in half! */
  preference_sum = 0;
  GNUNET_CONTAINER_multihashmap_iterate (neighbours, &update_preference,
                                         &preference_sum);
  GNUNET_STATISTICS_set (stats, gettext_noop ("# total peer preference"),
                         preference_sum, GNUNET_NO);
}


/**
 * Find the entry for the given neighbour.
 *
 * @param peer identity of the neighbour
 * @return NULL if we are not connected, otherwise the
 *         neighbour's entry.
 */
static struct Neighbour *
find_neighbour (const struct GNUNET_PeerIdentity *peer)
{
  return GNUNET_CONTAINER_multihashmap_get (neighbours, &peer->hashPubKey);
}


/**
 * Send a message to one of our clients.
 *
 * @param client target for the message
 * @param msg message to transmit
 * @param can_drop could this message be dropped if the
 *        client's queue is getting too large?
 */
static void
send_to_client (struct Client *client, const struct GNUNET_MessageHeader *msg,
                int can_drop)
{
#if DEBUG_CORE_CLIENT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Preparing to send %u bytes of message of type %u to client.\n",
              (unsigned int) ntohs (msg->size),
              (unsigned int) ntohs (msg->type));
#endif
  GNUNET_SERVER_notification_context_unicast (notifier, client->client_handle,
                                              msg, can_drop);
}


/**
 * Send a message to all of our current clients that have
 * the right options set.
 * 
 * @param msg message to multicast
 * @param can_drop can this message be discarded if the queue is too long
 * @param options mask to use 
 */
static void
send_to_all_clients (const struct GNUNET_MessageHeader *msg, int can_drop,
                     int options)
{
  struct Client *c;

  c = clients;
  while (c != NULL)
  {
    if (0 != (c->options & options))
    {
#if DEBUG_CORE_CLIENT > 1
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Sending message of type %u to client.\n",
                  (unsigned int) ntohs (msg->type));
#endif
      send_to_client (c, msg, can_drop);
    }
    c = c->next;
  }
}


/**
 * Function called by transport telling us that a peer
 * changed status.
 *
 * @param n the peer that changed status
 */
static void
handle_peer_status_change (struct Neighbour *n)
{
  struct PeerStatusNotifyMessage *psnm;
  char buf[GNUNET_SERVER_MAX_MESSAGE_SIZE - 1];
  struct GNUNET_TRANSPORT_ATS_Information *ats;
  size_t size;

  if ((!n->is_connected) || (n->status != PEER_STATE_KEY_CONFIRMED))
    return;
#if DEBUG_CORE > 1
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Peer `%4s' changed status\n",
              GNUNET_i2s (&n->peer));
#endif
  size =
      sizeof (struct PeerStatusNotifyMessage) +
      n->ats_count * sizeof (struct GNUNET_TRANSPORT_ATS_Information);
  if (size >= GNUNET_SERVER_MAX_MESSAGE_SIZE)
  {
    GNUNET_break (0);
    /* recovery strategy: throw away performance data */
    GNUNET_array_grow (n->ats, n->ats_count, 0);
    size =
        sizeof (struct PeerStatusNotifyMessage) +
        n->ats_count * sizeof (struct GNUNET_TRANSPORT_ATS_Information);
  }
  psnm = (struct PeerStatusNotifyMessage *) buf;
  psnm->header.size = htons (size);
  psnm->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_NOTIFY_STATUS_CHANGE);
  psnm->timeout = GNUNET_TIME_absolute_hton (get_neighbour_timeout (n));
  psnm->bandwidth_in = n->bw_in;
  psnm->bandwidth_out = n->bw_out;
  psnm->peer = n->peer;
  psnm->ats_count = htonl (n->ats_count);
  ats = &psnm->ats;
  memcpy (ats, n->ats,
          n->ats_count * sizeof (struct GNUNET_TRANSPORT_ATS_Information));
  ats[n->ats_count].type = htonl (0);
  ats[n->ats_count].value = htonl (0);
  send_to_all_clients (&psnm->header, GNUNET_YES,
                       GNUNET_CORE_OPTION_SEND_STATUS_CHANGE);
  GNUNET_STATISTICS_update (stats, gettext_noop ("# peer status changes"), 1,
                            GNUNET_NO);
}


/**
 * Go over our message queue and if it is not too long, go
 * over the pending requests from clients for this
 * neighbour and send some clients a 'READY' notification.
 *
 * @param n which peer to process
 */
static void
schedule_peer_messages (struct Neighbour *n)
{
  struct SendMessageReady smr;
  struct ClientActiveRequest *car;
  struct ClientActiveRequest *pos;
  struct Client *c;
  struct MessageEntry *mqe;
  unsigned int queue_size;

  /* check if neighbour queue is empty enough! */
  if (n != &self)
  {
    queue_size = 0;
    mqe = n->messages;
    while (mqe != NULL)
    {
      queue_size++;
      mqe = mqe->next;
    }
    if (queue_size >= MAX_PEER_QUEUE_SIZE)
    {
#if DEBUG_CORE_CLIENT
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Not considering client transmission requests: queue full\n");
#endif
      return;                   /* queue still full */
    }
    /* find highest priority request */
    pos = n->active_client_request_head;
    car = NULL;
    while (pos != NULL)
    {
      if ((car == NULL) || (pos->priority > car->priority))
        car = pos;
      pos = pos->next;
    }
  }
  else
  {
    car = n->active_client_request_head;
  }
  if (car == NULL)
    return;                     /* no pending requests */
#if DEBUG_CORE_CLIENT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Permitting client transmission request to `%s'\n",
              GNUNET_i2s (&n->peer));
#endif
  c = car->client;
  GNUNET_CONTAINER_DLL_remove (n->active_client_request_head,
                               n->active_client_request_tail, car);
  GNUNET_assert (GNUNET_YES ==
                 GNUNET_CONTAINER_multihashmap_remove (c->requests,
                                                       &n->peer.hashPubKey,
                                                       car));
  smr.header.size = htons (sizeof (struct SendMessageReady));
  smr.header.type = htons (GNUNET_MESSAGE_TYPE_CORE_SEND_READY);
  smr.size = htons (car->msize);
  smr.smr_id = car->smr_id;
  smr.peer = n->peer;
  send_to_client (c, &smr.header, GNUNET_NO);
  GNUNET_free (car);
}


/**
 * Compute a type map message for this peer.
 *
 * @return this peers current type map message.
 */
static struct GNUNET_MessageHeader *
compute_type_map_message ()
{
  char *tmp;
  uLongf dlen;
  struct GNUNET_MessageHeader *hdr;

#ifdef compressBound
  dlen = compressBound (sizeof (my_type_map));
#else
  dlen = sizeof (my_type_map) + (sizeof (my_type_map) / 100) + 20;
  /* documentation says 100.1% oldSize + 12 bytes, but we
   * should be able to overshoot by more to be safe */
#endif
  hdr = GNUNET_malloc (dlen + sizeof (struct GNUNET_MessageHeader));
  hdr->size = htons ((uint16_t) dlen + sizeof (struct GNUNET_MessageHeader));
  tmp = (char *) &hdr[1];
  if ((Z_OK !=
       compress2 ((Bytef *) tmp, &dlen, (const Bytef *) my_type_map,
                  sizeof (my_type_map), 9)) || (dlen >= sizeof (my_type_map)))
  {
    dlen = sizeof (my_type_map);
    memcpy (tmp, my_type_map, sizeof (my_type_map));
    hdr->type = htons (GNUNET_MESSAGE_TYPE_CORE_BINARY_TYPE_MAP);
  }
  else
  {
    hdr->type = htons (GNUNET_MESSAGE_TYPE_CORE_COMPRESSED_TYPE_MAP);
  }
  return hdr;
}


/**
 * Send a type map message to the neighbour.
 *
 * @param cls the type map message
 * @param key neighbour's identity
 * @param value 'struct Neighbour' of the target
 * @return always GNUNET_OK
 */
static int
send_type_map_to_neighbour (void *cls, const GNUNET_HashCode * key, void *value)
{
  struct GNUNET_MessageHeader *hdr = cls;
  struct Neighbour *n = value;
  struct MessageEntry *m;
  uint16_t size;

  if (n == &self)
    return GNUNET_OK;
  size = ntohs (hdr->size);
  m = GNUNET_malloc (sizeof (struct MessageEntry) + size);
  memcpy (&m[1], hdr, size);
  m->deadline = GNUNET_TIME_UNIT_FOREVER_ABS;
  m->slack_deadline = GNUNET_TIME_UNIT_FOREVER_ABS;
  m->priority = UINT_MAX;
  m->sender_status = n->status;
  m->size = size;
  m->next = n->messages;
  n->messages = m;
  return GNUNET_OK;
}



/**
 * Send my type map to all connected peers (it got changed).
 */
static void
broadcast_my_type_map ()
{
  struct GNUNET_MessageHeader *hdr;

  if (NULL == neighbours)
    return;
  hdr = compute_type_map_message ();
  GNUNET_CONTAINER_multihashmap_iterate (neighbours,
                                         &send_type_map_to_neighbour, hdr);
  GNUNET_free (hdr);
}


/**
 * Handle CORE_SEND_REQUEST message.
 */
static void
handle_client_send_request (void *cls, struct GNUNET_SERVER_Client *client,
                            const struct GNUNET_MessageHeader *message)
{
  const struct SendMessageRequest *req;
  struct Neighbour *n;
  struct Client *c;
  struct ClientActiveRequest *car;

  req = (const struct SendMessageRequest *) message;
  if (0 ==
      memcmp (&req->peer, &my_identity, sizeof (struct GNUNET_PeerIdentity)))
    n = &self;
  else
    n = find_neighbour (&req->peer);
  if ((n == NULL) || (GNUNET_YES != n->is_connected) ||
      (n->status != PEER_STATE_KEY_CONFIRMED))
  {
    /* neighbour must have disconnected since request was issued,
     * ignore (client will realize it once it processes the 
     * disconnect notification) */
#if DEBUG_CORE_CLIENT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Dropped client request for transmission (am disconnected)\n");
#endif
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# send requests dropped (disconnected)"), 1,
                              GNUNET_NO);
    GNUNET_SERVER_receive_done (client, GNUNET_OK);
    return;
  }
  c = clients;
  while ((c != NULL) && (c->client_handle != client))
    c = c->next;
  if (c == NULL)
  {
    /* client did not send INIT first! */
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  if (c->requests == NULL)
    c->requests = GNUNET_CONTAINER_multihashmap_create (16);
#if DEBUG_CORE_CLIENT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Received client transmission request. queueing\n");
#endif
  car = GNUNET_CONTAINER_multihashmap_get (c->requests, &req->peer.hashPubKey);
  if (car == NULL)
  {
    /* create new entry */
    car = GNUNET_malloc (sizeof (struct ClientActiveRequest));
    GNUNET_assert (GNUNET_OK ==
                   GNUNET_CONTAINER_multihashmap_put (c->requests,
                                                      &req->peer.hashPubKey,
                                                      car,
                                                      GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST));
    GNUNET_CONTAINER_DLL_insert (n->active_client_request_head,
                                 n->active_client_request_tail, car);
    car->client = c;
  }
  car->deadline = GNUNET_TIME_absolute_ntoh (req->deadline);
  car->priority = ntohl (req->priority);
  car->queue_size = ntohl (req->queue_size);
  car->msize = ntohs (req->size);
  car->smr_id = req->smr_id;
  schedule_peer_messages (n);
  GNUNET_SERVER_receive_done (client, GNUNET_OK);
}


/**
 * Notify client about an existing connection to one of our neighbours.
 */
static int
notify_client_about_neighbour (void *cls, const GNUNET_HashCode * key,
                               void *value)
{
  struct Client *c = cls;
  struct Neighbour *n = value;
  size_t size;
  char buf[GNUNET_SERVER_MAX_MESSAGE_SIZE - 1];
  struct GNUNET_TRANSPORT_ATS_Information *ats;
  struct ConnectNotifyMessage *cnm;

  size =
      sizeof (struct ConnectNotifyMessage) +
      (n->ats_count) * sizeof (struct GNUNET_TRANSPORT_ATS_Information);
  if (size >= GNUNET_SERVER_MAX_MESSAGE_SIZE)
  {
    GNUNET_break (0);
    /* recovery strategy: throw away performance data */
    GNUNET_array_grow (n->ats, n->ats_count, 0);
    size =
        sizeof (struct ConnectNotifyMessage) +
        (n->ats_count) * sizeof (struct GNUNET_TRANSPORT_ATS_Information);
  }
  cnm = (struct ConnectNotifyMessage *) buf;
  cnm->header.size = htons (size);
  cnm->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_NOTIFY_CONNECT);
  cnm->ats_count = htonl (n->ats_count);
  ats = &cnm->ats;
  memcpy (ats, n->ats,
          sizeof (struct GNUNET_TRANSPORT_ATS_Information) * n->ats_count);
  ats[n->ats_count].type = htonl (GNUNET_TRANSPORT_ATS_ARRAY_TERMINATOR);
  ats[n->ats_count].value = htonl (0);
  if (n->status == PEER_STATE_KEY_CONFIRMED)
  {
#if DEBUG_CORE_CLIENT
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Sending `%s' message to client.\n",
                "NOTIFY_CONNECT");
#endif
    cnm->peer = n->peer;
    send_to_client (c, &cnm->header, GNUNET_NO);
  }
  return GNUNET_OK;
}



/**
 * Handle CORE_INIT request.
 */
static void
handle_client_init (void *cls, struct GNUNET_SERVER_Client *client,
                    const struct GNUNET_MessageHeader *message)
{
  const struct InitMessage *im;
  struct InitReplyMessage irm;
  struct Client *c;
  uint16_t msize;
  const uint16_t *types;
  uint16_t *wtypes;
  unsigned int i;

#if DEBUG_CORE_CLIENT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Client connecting to core service with `%s' message\n", "INIT");
#endif
  /* check that we don't have an entry already */
  c = clients;
  while (c != NULL)
  {
    if (client == c->client_handle)
    {
      GNUNET_break (0);
      GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
      return;
    }
    c = c->next;
  }
  msize = ntohs (message->size);
  if (msize < sizeof (struct InitMessage))
  {
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  GNUNET_SERVER_notification_context_add (notifier, client);
  im = (const struct InitMessage *) message;
  types = (const uint16_t *) &im[1];
  msize -= sizeof (struct InitMessage);
  c = GNUNET_malloc (sizeof (struct Client) + msize);
  c->client_handle = client;
  c->next = clients;
  clients = c;
  c->tcnt = msize / sizeof (uint16_t);
  c->types = (const uint16_t *) &c[1];
  wtypes = (uint16_t *) & c[1];
  for (i = 0; i < c->tcnt; i++)
  {
    wtypes[i] = ntohs (types[i]);
    my_type_map[wtypes[i] / 32] |= (1 << (wtypes[i] % 32));
  }
  if (c->tcnt > 0)
    broadcast_my_type_map ();
  c->options = ntohl (im->options);
#if DEBUG_CORE_CLIENT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Client %p is interested in %u message types\n", c,
              (unsigned int) c->tcnt);
#endif
  /* send init reply message */
  irm.header.size = htons (sizeof (struct InitReplyMessage));
  irm.header.type = htons (GNUNET_MESSAGE_TYPE_CORE_INIT_REPLY);
  irm.reserved = htonl (0);
  memcpy (&irm.publicKey, &my_public_key,
          sizeof (struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded));
#if DEBUG_CORE_CLIENT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Sending `%s' message to client.\n",
              "INIT_REPLY");
#endif
  send_to_client (c, &irm.header, GNUNET_NO);
  if (0 != (c->options & GNUNET_CORE_OPTION_SEND_CONNECT))
  {
    /* notify new client about existing neighbours */
    GNUNET_CONTAINER_multihashmap_iterate (neighbours,
                                           &notify_client_about_neighbour, c);
  }
  GNUNET_SERVER_receive_done (client, GNUNET_OK);
}


/**
 * Free client request records.
 *
 * @param cls NULL
 * @param key identity of peer for which this is an active request
 * @param value the 'struct ClientActiveRequest' to free
 * @return GNUNET_YES (continue iteration)
 */
static int
destroy_active_client_request (void *cls, const GNUNET_HashCode * key,
                               void *value)
{
  struct ClientActiveRequest *car = value;
  struct Neighbour *n;
  struct GNUNET_PeerIdentity peer;

  peer.hashPubKey = *key;
  n = find_neighbour (&peer);
  GNUNET_assert (NULL != n);
  GNUNET_CONTAINER_DLL_remove (n->active_client_request_head,
                               n->active_client_request_tail, car);
  GNUNET_free (car);
  return GNUNET_YES;
}


/**
 * A client disconnected, clean up.
 *
 * @param cls closure
 * @param client identification of the client
 */
static void
handle_client_disconnect (void *cls, struct GNUNET_SERVER_Client *client)
{
  struct Client *pos;
  struct Client *prev;
  unsigned int i;
  const uint16_t *wtypes;

  if (client == NULL)
    return;
#if DEBUG_CORE_CLIENT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Client %p has disconnected from core service.\n", client);
#endif
  prev = NULL;
  pos = clients;
  while (pos != NULL)
  {
    if (client == pos->client_handle)
      break;
    prev = pos;
    pos = pos->next;
  }
  if (pos == NULL)
  {
    /* client never sent INIT */
    return;
  }
  if (prev == NULL)
    clients = pos->next;
  else
    prev->next = pos->next;
  if (pos->requests != NULL)
  {
    GNUNET_CONTAINER_multihashmap_iterate (pos->requests,
                                           &destroy_active_client_request,
                                           NULL);
    GNUNET_CONTAINER_multihashmap_destroy (pos->requests);
  }
  GNUNET_free (pos);

  /* rebuild my_type_map */
  memset (my_type_map, 0, sizeof (my_type_map));
  for (pos = clients; NULL != pos; pos = pos->next)
  {
    wtypes = (const uint16_t *) &pos[1];
    for (i = 0; i < pos->tcnt; i++)
      my_type_map[wtypes[i] / 32] |= (1 << (wtypes[i] % 32));
  }
  broadcast_my_type_map ();
}


/**
 * Helper function for handle_client_iterate_peers.
 *
 * @param cls the 'struct GNUNET_SERVER_TransmitContext' to queue replies
 * @param key identity of the connected peer
 * @param value the 'struct Neighbour' for the peer
 * @return GNUNET_OK (continue to iterate)
 */
static int
queue_connect_message (void *cls, const GNUNET_HashCode * key, void *value)
{
  struct GNUNET_SERVER_TransmitContext *tc = cls;
  struct Neighbour *n = value;
  char buf[GNUNET_SERVER_MAX_MESSAGE_SIZE - 1];
  struct GNUNET_TRANSPORT_ATS_Information *ats;
  size_t size;
  struct ConnectNotifyMessage *cnm;

  cnm = (struct ConnectNotifyMessage *) buf;
  if (n->status != PEER_STATE_KEY_CONFIRMED)
    return GNUNET_OK;
  size =
      sizeof (struct ConnectNotifyMessage) +
      (n->ats_count) * sizeof (struct GNUNET_TRANSPORT_ATS_Information);
  if (size >= GNUNET_SERVER_MAX_MESSAGE_SIZE)
  {
    GNUNET_break (0);
    /* recovery strategy: throw away performance data */
    GNUNET_array_grow (n->ats, n->ats_count, 0);
    size =
        sizeof (struct PeerStatusNotifyMessage) +
        n->ats_count * sizeof (struct GNUNET_TRANSPORT_ATS_Information);
  }
  cnm = (struct ConnectNotifyMessage *) buf;
  cnm->header.size = htons (size);
  cnm->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_NOTIFY_CONNECT);
  cnm->ats_count = htonl (n->ats_count);
  ats = &cnm->ats;
  memcpy (ats, n->ats,
          n->ats_count * sizeof (struct GNUNET_TRANSPORT_ATS_Information));
  ats[n->ats_count].type = htonl (GNUNET_TRANSPORT_ATS_ARRAY_TERMINATOR);
  ats[n->ats_count].value = htonl (0);
#if DEBUG_CORE_CLIENT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Sending `%s' message to client.\n",
              "NOTIFY_CONNECT");
#endif
  cnm->peer = n->peer;
  GNUNET_SERVER_transmit_context_append_message (tc, &cnm->header);
  return GNUNET_OK;
}


/**
 * Handle CORE_ITERATE_PEERS request.
 *
 * @param cls unused
 * @param client client sending the iteration request
 * @param message iteration request message
 */
static void
handle_client_iterate_peers (void *cls, struct GNUNET_SERVER_Client *client,
                             const struct GNUNET_MessageHeader *message)
{
  struct GNUNET_MessageHeader done_msg;
  struct GNUNET_SERVER_TransmitContext *tc;
  int msize;

  /* notify new client about existing neighbours */

  msize = ntohs (message->size);
  tc = GNUNET_SERVER_transmit_context_create (client);
  if (msize == sizeof (struct GNUNET_MessageHeader))
    GNUNET_CONTAINER_multihashmap_iterate (neighbours, &queue_connect_message,
                                           tc);
  else
    GNUNET_break (0);

  done_msg.size = htons (sizeof (struct GNUNET_MessageHeader));
  done_msg.type = htons (GNUNET_MESSAGE_TYPE_CORE_ITERATE_PEERS_END);
  GNUNET_SERVER_transmit_context_append_message (tc, &done_msg);
  GNUNET_SERVER_transmit_context_run (tc, GNUNET_TIME_UNIT_FOREVER_REL);
}


/**
 * Handle CORE_PEER_CONNECTED request.  Notify client about existing neighbours.
 *
 * @param cls unused
 * @param client client sending the iteration request
 * @param message iteration request message
 */
static void
handle_client_have_peer (void *cls, struct GNUNET_SERVER_Client *client,
                         const struct GNUNET_MessageHeader *message)
{
  struct GNUNET_MessageHeader done_msg;
  struct GNUNET_SERVER_TransmitContext *tc;
  struct GNUNET_PeerIdentity *peer;

  tc = GNUNET_SERVER_transmit_context_create (client);
  peer = (struct GNUNET_PeerIdentity *) &message[1];
  GNUNET_CONTAINER_multihashmap_get_multiple (neighbours, &peer->hashPubKey,
                                              &queue_connect_message, tc);
  done_msg.size = htons (sizeof (struct GNUNET_MessageHeader));
  done_msg.type = htons (GNUNET_MESSAGE_TYPE_CORE_ITERATE_PEERS_END);
  GNUNET_SERVER_transmit_context_append_message (tc, &done_msg);
  GNUNET_SERVER_transmit_context_run (tc, GNUNET_TIME_UNIT_FOREVER_REL);
}


/**
 * Handle REQUEST_INFO request.
 *
 * @param cls unused
 * @param client client sending the request
 * @param message iteration request message
 */
static void
handle_client_request_info (void *cls, struct GNUNET_SERVER_Client *client,
                            const struct GNUNET_MessageHeader *message)
{
  const struct RequestInfoMessage *rcm;
  struct Client *pos;
  struct Neighbour *n;
  struct ConfigurationInfoMessage cim;
  int32_t want_reserv;
  int32_t got_reserv;
  unsigned long long old_preference;
  struct GNUNET_TIME_Relative rdelay;

  rdelay = GNUNET_TIME_relative_get_zero ();
#if DEBUG_CORE_CLIENT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Core service receives `%s' request.\n",
              "REQUEST_INFO");
#endif
  pos = clients;
  while (pos != NULL)
  {
    if (client == pos->client_handle)
      break;
    pos = pos->next;
  }
  if (pos == NULL)
  {
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }

  rcm = (const struct RequestInfoMessage *) message;
  n = find_neighbour (&rcm->peer);
  memset (&cim, 0, sizeof (cim));
  if ((n != NULL) && (GNUNET_YES == n->is_connected))
  {
    want_reserv = ntohl (rcm->reserve_inbound);
    if (n->bw_out_internal_limit.value__ != rcm->limit_outbound.value__)
    {
      n->bw_out_internal_limit = rcm->limit_outbound;
      if (n->bw_out.value__ !=
          GNUNET_BANDWIDTH_value_min (n->bw_out_internal_limit,
                                      n->bw_out_external_limit).value__)
      {
        n->bw_out =
            GNUNET_BANDWIDTH_value_min (n->bw_out_internal_limit,
                                        n->bw_out_external_limit);
        GNUNET_BANDWIDTH_tracker_update_quota (&n->available_recv_window,
                                               n->bw_out);
        GNUNET_TRANSPORT_set_quota (transport, &n->peer, n->bw_in, n->bw_out);
        handle_peer_status_change (n);
      }
    }
    if (want_reserv < 0)
    {
      got_reserv = want_reserv;
    }
    else if (want_reserv > 0)
    {
      rdelay =
          GNUNET_BANDWIDTH_tracker_get_delay (&n->available_recv_window,
                                              want_reserv);
      if (rdelay.rel_value == 0)
        got_reserv = want_reserv;
      else
        got_reserv = 0;         /* all or nothing */
    }
    else
      got_reserv = 0;
    GNUNET_BANDWIDTH_tracker_consume (&n->available_recv_window, got_reserv);
    old_preference = n->current_preference;
    n->current_preference += GNUNET_ntohll (rcm->preference_change);
    if (old_preference > n->current_preference)
    {
      /* overflow; cap at maximum value */
      n->current_preference = ULLONG_MAX;
    }
    update_preference_sum (n->current_preference - old_preference);
#if DEBUG_CORE_QUOTA
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Received reservation request for %d bytes for peer `%4s', reserved %d bytes, suggesting delay of %llu ms\n",
                (int) want_reserv, GNUNET_i2s (&rcm->peer), (int) got_reserv,
                (unsigned long long) rdelay.rel_value);
#endif
    cim.reserved_amount = htonl (got_reserv);
    cim.reserve_delay = GNUNET_TIME_relative_hton (rdelay);
    cim.bw_out = n->bw_out;
    cim.preference = n->current_preference;
  }
  else
  {
    /* Technically, this COULD happen (due to asynchronous behavior),
     * but it should be rare, so we should generate an info event 
     * to help diagnosis of serious errors that might be masked by this */
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                _
                ("Client asked for preference change with peer `%s', which is not connected!\n"),
                GNUNET_i2s (&rcm->peer));
    GNUNET_SERVER_receive_done (client, GNUNET_OK);
    return;
  }
  cim.header.size = htons (sizeof (struct ConfigurationInfoMessage));
  cim.header.type = htons (GNUNET_MESSAGE_TYPE_CORE_CONFIGURATION_INFO);
  cim.peer = rcm->peer;
  cim.rim_id = rcm->rim_id;
#if DEBUG_CORE_CLIENT
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Sending `%s' message to client.\n",
              "CONFIGURATION_INFO");
#endif
  send_to_client (pos, &cim.header, GNUNET_NO);
  GNUNET_SERVER_receive_done (client, GNUNET_OK);
}


/**
 * Free the given entry for the neighbour (it has
 * already been removed from the list at this point).
 *
 * @param n neighbour to free
 */
static void
free_neighbour (struct Neighbour *n)
{
  struct MessageEntry *m;
  struct ClientActiveRequest *car;

#if DEBUG_CORE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Destroying neighbour entry for peer `%4s'\n",
              GNUNET_i2s (&n->peer));
#endif
  if (n->pitr != NULL)
  {
    GNUNET_PEERINFO_iterate_cancel (n->pitr);
    n->pitr = NULL;
  }
  if (n->skm != NULL)
  {
    GNUNET_free (n->skm);
    n->skm = NULL;
  }
  while (NULL != (m = n->messages))
  {
    n->messages = m->next;
    GNUNET_free (m);
  }
  while (NULL != (m = n->encrypted_head))
  {
    GNUNET_CONTAINER_DLL_remove (n->encrypted_head, n->encrypted_tail, m);
    GNUNET_free (m);
  }
  while (NULL != (car = n->active_client_request_head))
  {
    GNUNET_CONTAINER_DLL_remove (n->active_client_request_head,
                                 n->active_client_request_tail, car);
    GNUNET_assert (GNUNET_YES ==
                   GNUNET_CONTAINER_multihashmap_remove (car->client->requests,
                                                         &n->peer.hashPubKey,
                                                         car));
    GNUNET_free (car);
  }
  if (NULL != n->th)
  {
    GNUNET_TRANSPORT_notify_transmit_ready_cancel (n->th);
    n->th = NULL;
  }
  if (n->retry_plaintext_task != GNUNET_SCHEDULER_NO_TASK)
    GNUNET_SCHEDULER_cancel (n->retry_plaintext_task);
  if (n->retry_set_key_task != GNUNET_SCHEDULER_NO_TASK)
    GNUNET_SCHEDULER_cancel (n->retry_set_key_task);
  if (n->quota_update_task != GNUNET_SCHEDULER_NO_TASK)
    GNUNET_SCHEDULER_cancel (n->quota_update_task);
  if (n->dead_clean_task != GNUNET_SCHEDULER_NO_TASK)
    GNUNET_SCHEDULER_cancel (n->dead_clean_task);
  if (n->keep_alive_task != GNUNET_SCHEDULER_NO_TASK)
    GNUNET_SCHEDULER_cancel (n->keep_alive_task);
  if (n->status == PEER_STATE_KEY_CONFIRMED)
    GNUNET_STATISTICS_update (stats, gettext_noop ("# established sessions"),
                              -1, GNUNET_NO);
  GNUNET_array_grow (n->ats, n->ats_count, 0);
  GNUNET_free_non_null (n->public_key);
  GNUNET_free_non_null (n->pending_ping);
  GNUNET_free_non_null (n->pending_pong);
  GNUNET_free (n);
}


/**
 * Check if we have encrypted messages for the specified neighbour
 * pending, and if so, check with the transport about sending them
 * out.
 *
 * @param n neighbour to check.
 */
static void
process_encrypted_neighbour_queue (struct Neighbour *n);


/**
 * Encrypt size bytes from in and write the result to out.  Use the
 * key for outbound traffic of the given neighbour.
 *
 * @param n neighbour we are sending to
 * @param iv initialization vector to use
 * @param in ciphertext
 * @param out plaintext
 * @param size size of in/out
 * @return GNUNET_OK on success
 */
static int
do_encrypt (struct Neighbour *n,
            const struct GNUNET_CRYPTO_AesInitializationVector *iv,
            const void *in, void *out, size_t size)
{
  if (size != (uint16_t) size)
  {
    GNUNET_break (0);
    return GNUNET_NO;
  }
  GNUNET_assert (size ==
                 GNUNET_CRYPTO_aes_encrypt (in, (uint16_t) size,
                                            &n->encrypt_key, iv, out));
  GNUNET_STATISTICS_update (stats, gettext_noop ("# bytes encrypted"), size,
                            GNUNET_NO);
#if DEBUG_CORE > 2
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Encrypted %u bytes for `%4s' using key %u, IV %u\n",
              (unsigned int) size, GNUNET_i2s (&n->peer),
              (unsigned int) n->encrypt_key.crc32, GNUNET_CRYPTO_crc32_n (iv,
                                                                          sizeof
                                                                          (iv)));
#endif
  return GNUNET_OK;
}


/**
 * Consider freeing the given neighbour since we may not need
 * to keep it around anymore.
 *
 * @param n neighbour to consider discarding
 */
static void
consider_free_neighbour (struct Neighbour *n);


/**
 * Task triggered when a neighbour entry is about to time out 
 * (and we should prevent this by sending a PING).
 *
 * @param cls the 'struct Neighbour'
 * @param tc scheduler context (not used)
 */
static void
send_keep_alive (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct Neighbour *n = cls;
  struct GNUNET_TIME_Relative retry;
  struct GNUNET_TIME_Relative left;
  struct MessageEntry *me;
  struct PingMessage pp;
  struct PingMessage *pm;
  struct GNUNET_CRYPTO_AesInitializationVector iv;

  n->keep_alive_task = GNUNET_SCHEDULER_NO_TASK;
  /* send PING */
  me = GNUNET_malloc (sizeof (struct MessageEntry) +
                      sizeof (struct PingMessage));
  me->deadline = GNUNET_TIME_relative_to_absolute (MAX_PING_DELAY);
  me->priority = PING_PRIORITY;
  me->size = sizeof (struct PingMessage);
  GNUNET_CONTAINER_DLL_insert_after (n->encrypted_head, n->encrypted_tail,
                                     n->encrypted_tail, me);
  pm = (struct PingMessage *) &me[1];
  pm->header.size = htons (sizeof (struct PingMessage));
  pm->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_PING);
  pm->iv_seed =
      GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX);
  derive_iv (&iv, &n->encrypt_key, pm->iv_seed, &n->peer);
  pp.challenge = n->ping_challenge;
  pp.target = n->peer;
#if DEBUG_HANDSHAKE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Encrypting `%s' message with challenge %u for `%4s' using key %u, IV %u (salt %u).\n",
              "PING", (unsigned int) n->ping_challenge, GNUNET_i2s (&n->peer),
              (unsigned int) n->encrypt_key.crc32, GNUNET_CRYPTO_crc32_n (&iv,
                                                                          sizeof
                                                                          (iv)),
              pm->iv_seed);
#endif
  do_encrypt (n, &iv, &pp.target, &pm->target,
              sizeof (struct PingMessage) - ((void *) &pm->target -
                                             (void *) pm));
  process_encrypted_neighbour_queue (n);
  /* reschedule PING job */
  left = GNUNET_TIME_absolute_get_remaining (get_neighbour_timeout (n));
  retry =
      GNUNET_TIME_relative_max (GNUNET_TIME_relative_divide (left, 2),
                                MIN_PING_FREQUENCY);
  n->keep_alive_task =
      GNUNET_SCHEDULER_add_delayed (retry, &send_keep_alive, n);

}


/**
 * Task triggered when a neighbour entry might have gotten stale.
 *
 * @param cls the 'struct Neighbour'
 * @param tc scheduler context (not used)
 */
static void
consider_free_task (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct Neighbour *n = cls;

  n->dead_clean_task = GNUNET_SCHEDULER_NO_TASK;
  consider_free_neighbour (n);
}


/**
 * Consider freeing the given neighbour since we may not need
 * to keep it around anymore.
 *
 * @param n neighbour to consider discarding
 */
static void
consider_free_neighbour (struct Neighbour *n)
{
  struct GNUNET_TIME_Relative left;

  if ((n->th != NULL) || (n->pitr != NULL) || (GNUNET_YES == n->is_connected))
    return;                     /* no chance */

  left = GNUNET_TIME_absolute_get_remaining (get_neighbour_timeout (n));
  if (left.rel_value > 0)
  {
    if (n->dead_clean_task != GNUNET_SCHEDULER_NO_TASK)
      GNUNET_SCHEDULER_cancel (n->dead_clean_task);
    n->dead_clean_task =
        GNUNET_SCHEDULER_add_delayed (left, &consider_free_task, n);
    return;
  }
  /* actually free the neighbour... */
  GNUNET_assert (GNUNET_YES ==
                 GNUNET_CONTAINER_multihashmap_remove (neighbours,
                                                       &n->peer.hashPubKey, n));
  GNUNET_STATISTICS_set (stats, gettext_noop ("# neighbour entries allocated"),
                         GNUNET_CONTAINER_multihashmap_size (neighbours),
                         GNUNET_NO);
  free_neighbour (n);
}


/**
 * Function called when the transport service is ready to
 * receive an encrypted message for the respective peer
 *
 * @param cls neighbour to use message from
 * @param size number of bytes we can transmit
 * @param buf where to copy the message
 * @return number of bytes transmitted
 */
static size_t
notify_encrypted_transmit_ready (void *cls, size_t size, void *buf)
{
  struct Neighbour *n = cls;
  struct MessageEntry *m;
  size_t ret;
  char *cbuf;

  n->th = NULL;
  m = n->encrypted_head;
  if (m == NULL)
  {
#if DEBUG_CORE
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Encrypted message queue empty, no messages added to buffer for `%4s'\n",
                GNUNET_i2s (&n->peer));
#endif
    return 0;
  }
  GNUNET_CONTAINER_DLL_remove (n->encrypted_head, n->encrypted_tail, m);
  ret = 0;
  cbuf = buf;
  if (buf != NULL)
  {
    GNUNET_assert (size >= m->size);
    memcpy (cbuf, &m[1], m->size);
    ret = m->size;
    GNUNET_BANDWIDTH_tracker_consume (&n->available_send_window, m->size);
#if DEBUG_CORE
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Copied message of type %u and size %u into transport buffer for `%4s'\n",
                (unsigned int)
                ntohs (((struct GNUNET_MessageHeader *) &m[1])->type),
                (unsigned int) ret, GNUNET_i2s (&n->peer));
#endif
    process_encrypted_neighbour_queue (n);
  }
  else
  {
#if DEBUG_CORE
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Transmission of message of type %u and size %u failed\n",
                (unsigned int)
                ntohs (((struct GNUNET_MessageHeader *) &m[1])->type),
                (unsigned int) m->size);
#endif
  }
  GNUNET_free (m);
  consider_free_neighbour (n);
  GNUNET_STATISTICS_update (stats,
                            gettext_noop
                            ("# encrypted bytes given to transport"), ret,
                            GNUNET_NO);
  return ret;
}


/**
 * Check if we have plaintext messages for the specified neighbour
 * pending, and if so, consider batching and encrypting them (and
 * then trigger processing of the encrypted queue if needed).
 *
 * @param n neighbour to check.
 */
static void
process_plaintext_neighbour_queue (struct Neighbour *n);


/**
 * Check if we have encrypted messages for the specified neighbour
 * pending, and if so, check with the transport about sending them
 * out.
 *
 * @param n neighbour to check.
 */
static void
process_encrypted_neighbour_queue (struct Neighbour *n)
{
  struct MessageEntry *m;

  if (n->th != NULL)
    return;                     /* request already pending */
  if (GNUNET_YES != n->is_connected)
  {
    GNUNET_break (0);
    return;
  }
  m = n->encrypted_head;
  if (m == NULL)
  {
    /* encrypted queue empty, try plaintext instead */
    process_plaintext_neighbour_queue (n);
    return;
  }
#if DEBUG_CORE > 1
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Asking transport for transmission of %u bytes to `%4s' in next %llu ms\n",
              (unsigned int) m->size, GNUNET_i2s (&n->peer),
              (unsigned long long)
              GNUNET_TIME_absolute_get_remaining (m->deadline).rel_value);
#endif
  n->th =
      GNUNET_TRANSPORT_notify_transmit_ready (transport, &n->peer, m->size,
                                              m->priority,
                                              GNUNET_TIME_absolute_get_remaining
                                              (m->deadline),
                                              &notify_encrypted_transmit_ready,
                                              n);
  if (n->th == NULL)
  {
    /* message request too large or duplicate request */
    GNUNET_break (0);
    /* discard encrypted message */
    GNUNET_CONTAINER_DLL_remove (n->encrypted_head, n->encrypted_tail, m);
    GNUNET_free (m);
    process_encrypted_neighbour_queue (n);
  }
}


/**
 * Decrypt size bytes from in and write the result to out.  Use the
 * key for inbound traffic of the given neighbour.  This function does
 * NOT do any integrity-checks on the result.
 *
 * @param n neighbour we are receiving from
 * @param iv initialization vector to use
 * @param in ciphertext
 * @param out plaintext
 * @param size size of in/out
 * @return GNUNET_OK on success
 */
static int
do_decrypt (struct Neighbour *n,
            const struct GNUNET_CRYPTO_AesInitializationVector *iv,
            const void *in, void *out, size_t size)
{
  if (size != (uint16_t) size)
  {
    GNUNET_break (0);
    return GNUNET_NO;
  }
  if ((n->status != PEER_STATE_KEY_RECEIVED) &&
      (n->status != PEER_STATE_KEY_CONFIRMED))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  if (size !=
      GNUNET_CRYPTO_aes_decrypt (in, (uint16_t) size, &n->decrypt_key, iv, out))
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  GNUNET_STATISTICS_update (stats, gettext_noop ("# bytes decrypted"), size,
                            GNUNET_NO);
#if DEBUG_CORE > 1
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Decrypted %u bytes from `%4s' using key %u, IV %u\n",
              (unsigned int) size, GNUNET_i2s (&n->peer),
              (unsigned int) n->decrypt_key.crc32, GNUNET_CRYPTO_crc32_n (iv,
                                                                          sizeof
                                                                          (*iv)));
#endif
  return GNUNET_OK;
}


/**
 * Select messages for transmission.  This heuristic uses a combination
 * of earliest deadline first (EDF) scheduling (with bounded horizon)
 * and priority-based discard (in case no feasible schedule exist) and
 * speculative optimization (defer any kind of transmission until
 * we either create a batch of significant size, 25% of max, or until
 * we are close to a deadline).  Furthermore, when scheduling the
 * heuristic also packs as many messages into the batch as possible,
 * starting with those with the earliest deadline.  Yes, this is fun.
 *
 * @param n neighbour to select messages from
 * @param size number of bytes to select for transmission
 * @param retry_time set to the time when we should try again
 *        (only valid if this function returns zero)
 * @return number of bytes selected, or 0 if we decided to
 *         defer scheduling overall; in that case, retry_time is set.
 */
static size_t
select_messages (struct Neighbour *n, size_t size,
                 struct GNUNET_TIME_Relative *retry_time)
{
  struct MessageEntry *pos;
  struct MessageEntry *min;
  struct MessageEntry *last;
  unsigned int min_prio;
  struct GNUNET_TIME_Absolute t;
  struct GNUNET_TIME_Absolute now;
  struct GNUNET_TIME_Relative delta;
  uint64_t avail;
  struct GNUNET_TIME_Relative slack;    /* how long could we wait before missing deadlines? */
  size_t off;
  uint64_t tsize;
  unsigned int queue_size;
  int discard_low_prio;

  GNUNET_assert (NULL != n->messages);
  now = GNUNET_TIME_absolute_get ();
  /* last entry in linked list of messages processed */
  last = NULL;
  /* should we remove the entry with the lowest
   * priority from consideration for scheduling at the
   * end of the loop? */
  queue_size = 0;
  tsize = 0;
  pos = n->messages;
  while (pos != NULL)
  {
    queue_size++;
    tsize += pos->size;
    pos = pos->next;
  }
  discard_low_prio = GNUNET_YES;
  while (GNUNET_YES == discard_low_prio)
  {
    min = NULL;
    min_prio = UINT_MAX;
    discard_low_prio = GNUNET_NO;
    /* calculate number of bytes available for transmission at time "t" */
    avail = GNUNET_BANDWIDTH_tracker_get_available (&n->available_send_window);
    t = now;
    /* how many bytes have we (hypothetically) scheduled so far */
    off = 0;
    /* maximum time we can wait before transmitting anything
     * and still make all of our deadlines */
    slack = GNUNET_TIME_UNIT_FOREVER_REL;
    pos = n->messages;
    /* note that we use "*2" here because we want to look
     * a bit further into the future; much more makes no
     * sense since new message might be scheduled in the
     * meantime... */
    while ((pos != NULL) && (off < size * 2))
    {
      if (pos->do_transmit == GNUNET_YES)
      {
        /* already removed from consideration */
        pos = pos->next;
        continue;
      }
      if (discard_low_prio == GNUNET_NO)
      {
        delta = GNUNET_TIME_absolute_get_difference (t, pos->deadline);
        if (delta.rel_value > 0)
        {
          // FIXME: HUH? Check!
          t = pos->deadline;
          avail +=
              GNUNET_BANDWIDTH_value_get_available_until (n->bw_out, delta);
        }
        if (avail < pos->size)
        {
          // FIXME: HUH? Check!
          discard_low_prio = GNUNET_YES;        /* we could not schedule this one! */
        }
        else
        {
          avail -= pos->size;
          /* update slack, considering both its absolute deadline
           * and relative deadlines caused by other messages
           * with their respective load */
          slack =
              GNUNET_TIME_relative_min (slack,
                                        GNUNET_BANDWIDTH_value_get_delay_for
                                        (n->bw_out, avail));
          if (pos->deadline.abs_value <= now.abs_value)
          {
            /* now or never */
            slack = GNUNET_TIME_UNIT_ZERO;
          }
          else if (GNUNET_YES == pos->got_slack)
          {
            /* should be soon now! */
            slack =
                GNUNET_TIME_relative_min (slack,
                                          GNUNET_TIME_absolute_get_remaining
                                          (pos->slack_deadline));
          }
          else
          {
            slack =
                GNUNET_TIME_relative_min (slack,
                                          GNUNET_TIME_absolute_get_difference
                                          (now, pos->deadline));
            pos->got_slack = GNUNET_YES;
            pos->slack_deadline =
                GNUNET_TIME_absolute_min (pos->deadline,
                                          GNUNET_TIME_relative_to_absolute
                                          (GNUNET_CONSTANTS_MAX_CORK_DELAY));
          }
        }
      }
      off += pos->size;
      t = GNUNET_TIME_absolute_max (pos->deadline, t);  // HUH? Check!
      if (pos->priority <= min_prio)
      {
        /* update min for discard */
        min_prio = pos->priority;
        min = pos;
      }
      pos = pos->next;
    }
    if (discard_low_prio)
    {
      GNUNET_assert (min != NULL);
      /* remove lowest-priority entry from consideration */
      min->do_transmit = GNUNET_YES;    /* means: discard (for now) */
    }
    last = pos;
  }
  /* guard against sending "tiny" messages with large headers without
   * urgent deadlines */
  if ((slack.rel_value > GNUNET_CONSTANTS_MAX_CORK_DELAY.rel_value) &&
      (size > 4 * off) && (queue_size <= MAX_PEER_QUEUE_SIZE - 2))
  {
    /* less than 25% of message would be filled with deadlines still
     * being met if we delay by one second or more; so just wait for
     * more data; but do not wait longer than 1s (since we don't want
     * to delay messages for a really long time either). */
    *retry_time = GNUNET_CONSTANTS_MAX_CORK_DELAY;
    /* reset do_transmit values for next time */
    while (pos != last)
    {
      pos->do_transmit = GNUNET_NO;
      pos = pos->next;
    }
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# transmissions delayed due to corking"), 1,
                              GNUNET_NO);
#if DEBUG_CORE
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Deferring transmission for %llums due to underfull message buffer size (%u/%u)\n",
                (unsigned long long) retry_time->rel_value, (unsigned int) off,
                (unsigned int) size);
#endif
    return 0;
  }
  /* select marked messages (up to size) for transmission */
  off = 0;
  pos = n->messages;
  while (pos != last)
  {
    if ((pos->size <= size) && (pos->do_transmit == GNUNET_NO))
    {
      pos->do_transmit = GNUNET_YES;    /* mark for transmission */
      off += pos->size;
      size -= pos->size;
#if DEBUG_CORE > 1
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Selecting message of size %u for transmission\n",
                  (unsigned int) pos->size);
#endif
    }
    else
    {
#if DEBUG_CORE > 1
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Not selecting message of size %u for transmission at this time (maximum is %u)\n",
                  (unsigned int) pos->size, size);
#endif
      pos->do_transmit = GNUNET_NO;     /* mark for not transmitting! */
    }
    pos = pos->next;
  }
#if DEBUG_CORE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Selected %llu/%llu bytes of %u/%u plaintext messages for transmission to `%4s'.\n",
              (unsigned long long) off, (unsigned long long) tsize, queue_size,
              (unsigned int) MAX_PEER_QUEUE_SIZE, GNUNET_i2s (&n->peer));
#endif
  return off;
}


/**
 * Batch multiple messages into a larger buffer.
 *
 * @param n neighbour to take messages from
 * @param buf target buffer
 * @param size size of buf
 * @param deadline set to transmission deadline for the result
 * @param retry_time set to the time when we should try again
 *        (only valid if this function returns zero)
 * @param priority set to the priority of the batch
 * @return number of bytes written to buf (can be zero)
 */
static size_t
batch_message (struct Neighbour *n, char *buf, size_t size,
               struct GNUNET_TIME_Absolute *deadline,
               struct GNUNET_TIME_Relative *retry_time, unsigned int *priority)
{
  char ntmb[GNUNET_SERVER_MAX_MESSAGE_SIZE - 1];
  struct NotifyTrafficMessage *ntm = (struct NotifyTrafficMessage *) ntmb;
  struct MessageEntry *pos;
  struct MessageEntry *prev;
  struct MessageEntry *next;
  size_t ret;

  ret = 0;
  *priority = 0;
  *deadline = GNUNET_TIME_UNIT_FOREVER_ABS;
  *retry_time = GNUNET_TIME_UNIT_FOREVER_REL;
  if (0 == select_messages (n, size, retry_time))
  {
#if DEBUG_CORE
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "No messages selected, will try again in %llu ms\n",
                retry_time->rel_value);
#endif
    return 0;
  }
  ntm->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_NOTIFY_OUTBOUND);
  ntm->ats_count = htonl (0);
  ntm->ats.type = htonl (0);
  ntm->ats.value = htonl (0);
  ntm->peer = n->peer;
  pos = n->messages;
  prev = NULL;
  while ((pos != NULL) && (size >= sizeof (struct GNUNET_MessageHeader)))
  {
    next = pos->next;
    if (GNUNET_YES == pos->do_transmit)
    {
      GNUNET_assert (pos->size <= size);
      /* do notifications */
      /* FIXME: track if we have *any* client that wants
       * full notifications and only do this if that is
       * actually true */
      if (pos->size <
          GNUNET_SERVER_MAX_MESSAGE_SIZE - sizeof (struct NotifyTrafficMessage))
      {
        memcpy (&ntm[1], &pos[1], pos->size);
        ntm->header.size =
            htons (sizeof (struct NotifyTrafficMessage) +
                   sizeof (struct GNUNET_MessageHeader));
        send_to_all_clients (&ntm->header, GNUNET_YES,
                             GNUNET_CORE_OPTION_SEND_HDR_OUTBOUND);
      }
      else
      {
        /* message too large for 'full' notifications, we do at
         * least the 'hdr' type */
        memcpy (&ntm[1], &pos[1], sizeof (struct GNUNET_MessageHeader));
      }
      ntm->header.size =
          htons (sizeof (struct NotifyTrafficMessage) + pos->size);
      send_to_all_clients (&ntm->header, GNUNET_YES,
                           GNUNET_CORE_OPTION_SEND_FULL_OUTBOUND);
#if DEBUG_HANDSHAKE
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Encrypting %u bytes with message of type %u and size %u\n",
                  pos->size,
                  (unsigned int)
                  ntohs (((const struct GNUNET_MessageHeader *) &pos[1])->type),
                  (unsigned int)
                  ntohs (((const struct GNUNET_MessageHeader *)
                          &pos[1])->size));
#endif
      /* copy for encrypted transmission */
      memcpy (&buf[ret], &pos[1], pos->size);
      ret += pos->size;
      size -= pos->size;
      *priority += pos->priority;
#if DEBUG_CORE > 1
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Adding plaintext message of size %u with deadline %llu ms to batch\n",
                  (unsigned int) pos->size,
                  (unsigned long long)
                  GNUNET_TIME_absolute_get_remaining (pos->deadline).rel_value);
#endif
      deadline->abs_value =
          GNUNET_MIN (deadline->abs_value, pos->deadline.abs_value);
      GNUNET_free (pos);
      if (prev == NULL)
        n->messages = next;
      else
        prev->next = next;
    }
    else
    {
      prev = pos;
    }
    pos = next;
  }
#if DEBUG_CORE > 1
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Deadline for message batch is %llu ms\n",
              GNUNET_TIME_absolute_get_remaining (*deadline).rel_value);
#endif
  return ret;
}


/**
 * Remove messages with deadlines that have long expired from
 * the queue.
 *
 * @param n neighbour to inspect
 */
static void
discard_expired_messages (struct Neighbour *n)
{
  struct MessageEntry *prev;
  struct MessageEntry *next;
  struct MessageEntry *pos;
  struct GNUNET_TIME_Absolute now;
  struct GNUNET_TIME_Relative delta;
  int disc;

  disc = GNUNET_NO;
  now = GNUNET_TIME_absolute_get ();
  prev = NULL;
  pos = n->messages;
  while (pos != NULL)
  {
    next = pos->next;
    delta = GNUNET_TIME_absolute_get_difference (pos->deadline, now);
    if (delta.rel_value > PAST_EXPIRATION_DISCARD_TIME.rel_value)
    {
#if DEBUG_CORE
      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                  "Message is %llu ms past due, discarding.\n",
                  delta.rel_value);
#endif
      if (prev == NULL)
        n->messages = next;
      else
        prev->next = next;
      GNUNET_STATISTICS_update (stats,
                                gettext_noop
                                ("# messages discarded (expired prior to transmission)"),
                                1, GNUNET_NO);
      disc = GNUNET_YES;
      GNUNET_free (pos);
    }
    else
      prev = pos;
    pos = next;
  }
  if (GNUNET_YES == disc)
    schedule_peer_messages (n);
}


/**
 * Signature of the main function of a task.
 *
 * @param cls closure
 * @param tc context information (why was this task triggered now)
 */
static void
retry_plaintext_processing (void *cls,
                            const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct Neighbour *n = cls;

  n->retry_plaintext_task = GNUNET_SCHEDULER_NO_TASK;
  process_plaintext_neighbour_queue (n);
}


/**
 * Send our key (and encrypted PING) to the other peer.
 *
 * @param n the other peer
 */
static void
send_key (struct Neighbour *n);

/**
 * Task that will retry "send_key" if our previous attempt failed
 * to yield a PONG.
 */
static void
set_key_retry_task (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct Neighbour *n = cls;

#if DEBUG_CORE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Retrying key transmission to `%4s'\n",
              GNUNET_i2s (&n->peer));
#endif
  n->retry_set_key_task = GNUNET_SCHEDULER_NO_TASK;
  n->set_key_retry_frequency =
      GNUNET_TIME_relative_multiply (n->set_key_retry_frequency, 2);
  send_key (n);
}


/**
 * Check if we have plaintext messages for the specified neighbour
 * pending, and if so, consider batching and encrypting them (and
 * then trigger processing of the encrypted queue if needed).
 *
 * @param n neighbour to check.
 */
static void
process_plaintext_neighbour_queue (struct Neighbour *n)
{
  char pbuf[GNUNET_CONSTANTS_MAX_ENCRYPTED_MESSAGE_SIZE + sizeof (struct EncryptedMessage)];    /* plaintext */
  size_t used;
  struct EncryptedMessage *em;  /* encrypted message */
  struct EncryptedMessage *ph;  /* plaintext header */
  struct MessageEntry *me;
  unsigned int priority;
  struct GNUNET_TIME_Absolute deadline;
  struct GNUNET_TIME_Relative retry_time;
  struct GNUNET_CRYPTO_AesInitializationVector iv;
  struct GNUNET_CRYPTO_AuthKey auth_key;

  if (n->retry_plaintext_task != GNUNET_SCHEDULER_NO_TASK)
  {
    GNUNET_SCHEDULER_cancel (n->retry_plaintext_task);
    n->retry_plaintext_task = GNUNET_SCHEDULER_NO_TASK;
  }
  switch (n->status)
  {
  case PEER_STATE_DOWN:
    send_key (n);
#if DEBUG_CORE
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Not yet connected to `%4s', deferring processing of plaintext messages.\n",
                GNUNET_i2s (&n->peer));
#endif
    return;
  case PEER_STATE_KEY_SENT:
    if (n->retry_set_key_task == GNUNET_SCHEDULER_NO_TASK)
      n->retry_set_key_task =
          GNUNET_SCHEDULER_add_delayed (n->set_key_retry_frequency,
                                        &set_key_retry_task, n);
#if DEBUG_CORE
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Not yet connected to `%4s', deferring processing of plaintext messages.\n",
                GNUNET_i2s (&n->peer));
#endif
    return;
  case PEER_STATE_KEY_RECEIVED:
    if (n->retry_set_key_task == GNUNET_SCHEDULER_NO_TASK)
      n->retry_set_key_task =
          GNUNET_SCHEDULER_add_delayed (n->set_key_retry_frequency,
                                        &set_key_retry_task, n);
#if DEBUG_CORE
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Not yet connected to `%4s', deferring processing of plaintext messages.\n",
                GNUNET_i2s (&n->peer));
#endif
    return;
  case PEER_STATE_KEY_CONFIRMED:
    /* ready to continue */
    break;
  }
  discard_expired_messages (n);
  if (n->messages == NULL)
  {
#if DEBUG_CORE
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Plaintext message queue for `%4s' is empty.\n",
                GNUNET_i2s (&n->peer));
#endif
    return;                     /* no pending messages */
  }
  if (n->encrypted_head != NULL)
  {
#if DEBUG_CORE > 2
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Encrypted message queue for `%4s' is still full, delaying plaintext processing.\n",
                GNUNET_i2s (&n->peer));
#endif
    return;                     /* wait for messages already encrypted to be
                                 * processed first! */
  }
  ph = (struct EncryptedMessage *) pbuf;
  deadline = GNUNET_TIME_UNIT_FOREVER_ABS;
  priority = 0;
  used = sizeof (struct EncryptedMessage);
  used +=
      batch_message (n, &pbuf[used],
                     GNUNET_CONSTANTS_MAX_ENCRYPTED_MESSAGE_SIZE, &deadline,
                     &retry_time, &priority);
  if (used == sizeof (struct EncryptedMessage))
  {
#if DEBUG_CORE > 1
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "No messages selected for transmission to `%4s' at this time, will try again later.\n",
                GNUNET_i2s (&n->peer));
#endif
    /* no messages selected for sending, try again later... */
    n->retry_plaintext_task =
        GNUNET_SCHEDULER_add_delayed (retry_time, &retry_plaintext_processing,
                                      n);
    return;
  }
#if DEBUG_CORE_QUOTA
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Sending %u b/s as new limit to peer `%4s'\n",
              (unsigned int) ntohl (n->bw_in.value__), GNUNET_i2s (&n->peer));
#endif
  ph->iv_seed =
      htonl (GNUNET_CRYPTO_random_u32
             (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX));
  ph->sequence_number = htonl (++n->last_sequence_number_sent);
  ph->inbound_bw_limit = n->bw_in;
  ph->timestamp = GNUNET_TIME_absolute_hton (GNUNET_TIME_absolute_get ());

  /* setup encryption message header */
  me = GNUNET_malloc (sizeof (struct MessageEntry) + used);
  me->deadline = deadline;
  me->priority = priority;
  me->size = used;
  em = (struct EncryptedMessage *) &me[1];
  em->header.size = htons (used);
  em->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_ENCRYPTED_MESSAGE);
  em->iv_seed = ph->iv_seed;
  derive_iv (&iv, &n->encrypt_key, ph->iv_seed, &n->peer);
  /* encrypt */
#if DEBUG_HANDSHAKE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Encrypting %u bytes of plaintext messages for `%4s' for transmission in %llums.\n",
              (unsigned int) used - ENCRYPTED_HEADER_SIZE,
              GNUNET_i2s (&n->peer),
              (unsigned long long)
              GNUNET_TIME_absolute_get_remaining (deadline).rel_value);
#endif
  GNUNET_assert (GNUNET_OK ==
                 do_encrypt (n, &iv, &ph->sequence_number, &em->sequence_number,
                             used - ENCRYPTED_HEADER_SIZE));
  derive_auth_key (&auth_key, &n->encrypt_key, ph->iv_seed,
                   n->encrypt_key_created);
  GNUNET_CRYPTO_hmac (&auth_key, &em->sequence_number,
                      used - ENCRYPTED_HEADER_SIZE, &em->hmac);
#if DEBUG_HANDSHAKE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Authenticated %u bytes of ciphertext %u: `%s'\n",
              used - ENCRYPTED_HEADER_SIZE,
              GNUNET_CRYPTO_crc32_n (&em->sequence_number,
                                     used - ENCRYPTED_HEADER_SIZE),
              GNUNET_h2s (&em->hmac));
#endif
  /* append to transmission list */
  GNUNET_CONTAINER_DLL_insert_after (n->encrypted_head, n->encrypted_tail,
                                     n->encrypted_tail, me);
  process_encrypted_neighbour_queue (n);
  schedule_peer_messages (n);
}


/**
 * Function that recalculates the bandwidth quota for the
 * given neighbour and transmits it to the transport service.
 * 
 * @param cls neighbour for the quota update
 * @param tc context
 */
static void
neighbour_quota_update (void *cls,
                        const struct GNUNET_SCHEDULER_TaskContext *tc);


/**
 * Schedule the task that will recalculate the bandwidth
 * quota for this peer (and possibly force a disconnect of
 * idle peers by calculating a bandwidth of zero).
 */
static void
schedule_quota_update (struct Neighbour *n)
{
  GNUNET_assert (n->quota_update_task == GNUNET_SCHEDULER_NO_TASK);
  n->quota_update_task =
      GNUNET_SCHEDULER_add_delayed (QUOTA_UPDATE_FREQUENCY,
                                    &neighbour_quota_update, n);
}


/**
 * Initialize a new 'struct Neighbour'.
 *
 * @param pid ID of the new neighbour
 * @return handle for the new neighbour
 */
static struct Neighbour *
create_neighbour (const struct GNUNET_PeerIdentity *pid)
{
  struct Neighbour *n;
  struct GNUNET_TIME_Absolute now;

#if DEBUG_CORE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Creating neighbour entry for peer `%4s'\n", GNUNET_i2s (pid));
#endif
  n = GNUNET_malloc (sizeof (struct Neighbour));
  n->peer = *pid;
  GNUNET_CRYPTO_aes_create_session_key (&n->encrypt_key);
  now = GNUNET_TIME_absolute_get ();
  n->encrypt_key_created = now;
  n->last_activity = now;
  n->set_key_retry_frequency = INITIAL_SET_KEY_RETRY_FREQUENCY;
  n->bw_in = GNUNET_CONSTANTS_DEFAULT_BW_IN_OUT;
  n->bw_out = GNUNET_CONSTANTS_DEFAULT_BW_IN_OUT;
  n->bw_out_internal_limit = GNUNET_BANDWIDTH_value_init (UINT32_MAX);
  n->bw_out_external_limit = GNUNET_CONSTANTS_DEFAULT_BW_IN_OUT;
  n->ping_challenge =
      GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX);
  GNUNET_assert (GNUNET_OK ==
                 GNUNET_CONTAINER_multihashmap_put (neighbours,
                                                    &n->peer.hashPubKey, n,
                                                    GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
  GNUNET_STATISTICS_set (stats, gettext_noop ("# neighbour entries allocated"),
                         GNUNET_CONTAINER_multihashmap_size (neighbours),
                         GNUNET_NO);
  neighbour_quota_update (n, NULL);
  consider_free_neighbour (n);
  return n;
}


/**
 * Handle CORE_SEND request.
 *
 * @param cls unused
 * @param client the client issuing the request
 * @param message the "struct SendMessage"
 */
static void
handle_client_send (void *cls, struct GNUNET_SERVER_Client *client,
                    const struct GNUNET_MessageHeader *message)
{
  const struct SendMessage *sm;
  struct Neighbour *n;
  struct MessageEntry *prev;
  struct MessageEntry *pos;
  struct MessageEntry *e;
  struct MessageEntry *min_prio_entry;
  struct MessageEntry *min_prio_prev;
  unsigned int min_prio;
  unsigned int queue_size;
  uint16_t msize;

  msize = ntohs (message->size);
  if (msize <
      sizeof (struct SendMessage) + sizeof (struct GNUNET_MessageHeader))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "msize is %u, should be at least %u (in %s:%d)\n", msize,
                sizeof (struct SendMessage) +
                sizeof (struct GNUNET_MessageHeader), __FILE__, __LINE__);
    GNUNET_break (0);
    if (client != NULL)
      GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  sm = (const struct SendMessage *) message;
  msize -= sizeof (struct SendMessage);
  if (0 ==
      memcmp (&sm->peer, &my_identity, sizeof (struct GNUNET_PeerIdentity)))
  {
    /* loopback */
    GNUNET_SERVER_mst_receive (mst, &self, (const char *) &sm[1], msize,
                               GNUNET_YES, GNUNET_NO);
    if (client != NULL)
      GNUNET_SERVER_receive_done (client, GNUNET_OK);
    return;
  }
  n = find_neighbour (&sm->peer);
  if ((n == NULL) || (GNUNET_YES != n->is_connected) ||
      (n->status != PEER_STATE_KEY_CONFIRMED))
  {
    /* attempt to send message to peer that is not connected anymore 
     * (can happen due to asynchrony) */
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# messages discarded (disconnected)"), 1,
                              GNUNET_NO);
    if (client != NULL)
      GNUNET_SERVER_receive_done (client, GNUNET_OK);
    return;
  }
#if DEBUG_CORE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Core received `%s' request, queueing %u bytes of plaintext data for transmission to `%4s'.\n",
              "SEND", (unsigned int) msize, GNUNET_i2s (&sm->peer));
#endif
  discard_expired_messages (n);
  /* bound queue size */
  /* NOTE: this entire block to bound the queue size should be
   * obsolete with the new client-request code and the
   * 'schedule_peer_messages' mechanism; we still have this code in
   * here for now as a sanity check for the new mechanmism;
   * ultimately, we should probably simply reject SEND messages that
   * are not 'approved' (or provide a new core API for very unreliable
   * delivery that always sends with priority 0).  Food for thought. */
  min_prio = UINT32_MAX;
  min_prio_entry = NULL;
  min_prio_prev = NULL;
  queue_size = 0;
  prev = NULL;
  pos = n->messages;
  while (pos != NULL)
  {
    if (pos->priority <= min_prio)
    {
      min_prio_entry = pos;
      min_prio_prev = prev;
      min_prio = pos->priority;
    }
    queue_size++;
    prev = pos;
    pos = pos->next;
  }
  if (queue_size >= MAX_PEER_QUEUE_SIZE)
  {
    /* queue full */
    if (ntohl (sm->priority) <= min_prio)
    {
      /* discard new entry; this should no longer happen! */
      GNUNET_break (0);
#if DEBUG_CORE
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Queue full (%u/%u), discarding new request (%u bytes of type %u)\n",
                  queue_size, (unsigned int) MAX_PEER_QUEUE_SIZE,
                  (unsigned int) msize, (unsigned int) ntohs (message->type));
#endif
      GNUNET_STATISTICS_update (stats,
                                gettext_noop ("# discarded CORE_SEND requests"),
                                1, GNUNET_NO);

      if (client != NULL)
        GNUNET_SERVER_receive_done (client, GNUNET_OK);
      return;
    }
    GNUNET_assert (min_prio_entry != NULL);
    /* discard "min_prio_entry" */
#if DEBUG_CORE
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Queue full, discarding existing older request\n");
#endif
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# discarded lower priority CORE_SEND requests"),
                              1, GNUNET_NO);
    if (min_prio_prev == NULL)
      n->messages = min_prio_entry->next;
    else
      min_prio_prev->next = min_prio_entry->next;
    GNUNET_free (min_prio_entry);
  }

#if DEBUG_CORE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Adding transmission request for `%4s' of size %u to queue\n",
              GNUNET_i2s (&sm->peer), (unsigned int) msize);
#endif
  GNUNET_break (0 == ntohl (sm->reserved));
  e = GNUNET_malloc (sizeof (struct MessageEntry) + msize);
  e->deadline = GNUNET_TIME_absolute_ntoh (sm->deadline);
  e->priority = ntohl (sm->priority);
  e->size = msize;
  if (GNUNET_YES != (int) ntohl (sm->cork))
    e->got_slack = GNUNET_YES;
  memcpy (&e[1], &sm[1], msize);

  /* insert, keep list sorted by deadline */
  prev = NULL;
  pos = n->messages;
  while ((pos != NULL) && (pos->deadline.abs_value < e->deadline.abs_value))
  {
    prev = pos;
    pos = pos->next;
  }
  if (prev == NULL)
    n->messages = e;
  else
    prev->next = e;
  e->next = pos;

  /* consider scheduling now */
  process_plaintext_neighbour_queue (n);
  if (client != NULL)
    GNUNET_SERVER_receive_done (client, GNUNET_OK);
}


/**
 * Handle CORE_REQUEST_CONNECT request.
 *
 * @param cls unused
 * @param client the client issuing the request
 * @param message the "struct ConnectMessage"
 */
static void
handle_client_request_connect (void *cls, struct GNUNET_SERVER_Client *client,
                               const struct GNUNET_MessageHeader *message)
{
  const struct ConnectMessage *cm = (const struct ConnectMessage *) message;
  struct Neighbour *n;

  if (0 ==
      memcmp (&cm->peer, &my_identity, sizeof (struct GNUNET_PeerIdentity)))
  {
    /* In this case a client has asked us to connect to ourselves, not really an error! */
    GNUNET_SERVER_receive_done (client, GNUNET_OK);
    return;
  }
  GNUNET_break (ntohl (cm->reserved) == 0);
#if DEBUG_CORE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Core received `%s' request for `%4s', will try to establish connection\n",
              "REQUEST_CONNECT", GNUNET_i2s (&cm->peer));
#endif
  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# connection requests received"), 1,
                            GNUNET_NO);
  GNUNET_SERVER_receive_done (client, GNUNET_OK);
  n = find_neighbour (&cm->peer);
  if ((n == NULL) || (GNUNET_YES != n->is_connected))
  {
    GNUNET_TRANSPORT_try_connect (transport, &cm->peer);
  }
  else
  {
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# connection requests ignored (already connected)"),
                              1, GNUNET_NO);
  }
}


/**
 * PEERINFO is giving us a HELLO for a peer.  Add the public key to
 * the neighbour's struct and retry send_key.  Or, if we did not get a
 * HELLO, just do nothing.
 *
 * @param cls the 'struct Neighbour' to retry sending the key for
 * @param peer the peer for which this is the HELLO
 * @param hello HELLO message of that peer
 * @param err_msg NULL if successful, otherwise contains error message
 */
static void
process_hello_retry_send_key (void *cls, const struct GNUNET_PeerIdentity *peer,
                              const struct GNUNET_HELLO_Message *hello,
                              const char *err_msg)
{
  struct Neighbour *n = cls;

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

  if (peer == NULL)
  {
#if DEBUG_CORE
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Entered `%s' and `%s' is NULL!\n",
                "process_hello_retry_send_key", "peer");
#endif
    n->pitr = NULL;
    if (n->public_key != NULL)
    {
      if (n->retry_set_key_task != GNUNET_SCHEDULER_NO_TASK)
      {
        GNUNET_SCHEDULER_cancel (n->retry_set_key_task);
        n->retry_set_key_task = GNUNET_SCHEDULER_NO_TASK;
      }
      GNUNET_STATISTICS_update (stats,
                                gettext_noop
                                ("# SET_KEY messages deferred (need public key)"),
                                -1, GNUNET_NO);
      send_key (n);
    }
    else
    {
#if DEBUG_CORE
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Failed to obtain public key for peer `%4s', delaying processing of SET_KEY\n",
                  GNUNET_i2s (&n->peer));
#endif
      GNUNET_STATISTICS_update (stats,
                                gettext_noop
                                ("# Delayed connecting due to lack of public key"),
                                1, GNUNET_NO);
      if (GNUNET_SCHEDULER_NO_TASK == n->retry_set_key_task)
        n->retry_set_key_task =
            GNUNET_SCHEDULER_add_delayed (n->set_key_retry_frequency,
                                          &set_key_retry_task, n);
    }
    return;
  }

#if DEBUG_CORE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Entered `%s' for peer `%4s'\n",
              "process_hello_retry_send_key", GNUNET_i2s (peer));
#endif
  if (n->public_key != NULL)
  {
    /* already have public key, why are we here? */
    GNUNET_break (0);
    return;
  }

#if DEBUG_CORE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Received new `%s' message for `%4s', initiating key exchange.\n",
              "HELLO", GNUNET_i2s (peer));
#endif
  n->public_key =
      GNUNET_malloc (sizeof (struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded));
  if (GNUNET_OK != GNUNET_HELLO_get_key (hello, n->public_key))
  {
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# Error extracting public key from HELLO"), 1,
                              GNUNET_NO);
    GNUNET_free (n->public_key);
    n->public_key = NULL;
#if DEBUG_CORE
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "GNUNET_HELLO_get_key returned awfully\n");
#endif
    return;
  }
}


/**
 * Send our key (and encrypted PING) to the other peer.
 *
 * @param n the other peer
 */
static void
send_key (struct Neighbour *n)
{
  struct MessageEntry *pos;
  struct SetKeyMessage *sm;
  struct MessageEntry *me;
  struct PingMessage pp;
  struct PingMessage *pm;
  struct GNUNET_CRYPTO_AesInitializationVector iv;

  if (n->retry_set_key_task != GNUNET_SCHEDULER_NO_TASK)
  {
    GNUNET_SCHEDULER_cancel (n->retry_set_key_task);
    n->retry_set_key_task = GNUNET_SCHEDULER_NO_TASK;
  }
  if (n->pitr != NULL)
  {
#if DEBUG_CORE
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Key exchange in progress with `%4s'.\n",
                GNUNET_i2s (&n->peer));
#endif
    return;                     /* already in progress */
  }
  if (GNUNET_YES != n->is_connected)
  {
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# Asking transport to connect (for SET_KEY)"),
                              1, GNUNET_NO);
    GNUNET_TRANSPORT_try_connect (transport, &n->peer);
    return;
  }
#if DEBUG_CORE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Asked to perform key exchange with `%4s'.\n",
              GNUNET_i2s (&n->peer));
#endif
  if (n->public_key == NULL)
  {
    /* lookup n's public key, then try again */
#if DEBUG_CORE
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Lacking public key for `%4s', trying to obtain one (send_key).\n",
                GNUNET_i2s (&n->peer));
#endif
    GNUNET_assert (n->pitr == NULL);
    n->pitr =
        GNUNET_PEERINFO_iterate (peerinfo, &n->peer,
                                 GNUNET_TIME_relative_multiply
                                 (GNUNET_TIME_UNIT_SECONDS, 20),
                                 &process_hello_retry_send_key, n);
    return;
  }
  pos = n->encrypted_head;
  while (pos != NULL)
  {
    if (GNUNET_YES == pos->is_setkey)
    {
      if (pos->sender_status == n->status)
      {
#if DEBUG_CORE
        GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                    "`%s' message for `%4s' queued already\n", "SET_KEY",
                    GNUNET_i2s (&n->peer));
#endif
        goto trigger_processing;
      }
      GNUNET_CONTAINER_DLL_remove (n->encrypted_head, n->encrypted_tail, pos);
      GNUNET_free (pos);
#if DEBUG_CORE
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Removing queued `%s' message for `%4s', will create a new one\n",
                  "SET_KEY", GNUNET_i2s (&n->peer));
#endif
      break;
    }
    pos = pos->next;
  }

  /* update status */
  switch (n->status)
  {
  case PEER_STATE_DOWN:
    n->status = PEER_STATE_KEY_SENT;
    break;
  case PEER_STATE_KEY_SENT:
    break;
  case PEER_STATE_KEY_RECEIVED:
    break;
  case PEER_STATE_KEY_CONFIRMED:
    break;
  default:
    GNUNET_break (0);
    break;
  }


  /* first, set key message */
  me = GNUNET_malloc (sizeof (struct MessageEntry) +
                      sizeof (struct SetKeyMessage) +
                      sizeof (struct PingMessage));
  me->deadline = GNUNET_TIME_relative_to_absolute (MAX_SET_KEY_DELAY);
  me->priority = SET_KEY_PRIORITY;
  me->size = sizeof (struct SetKeyMessage) + sizeof (struct PingMessage);
  me->is_setkey = GNUNET_YES;
  me->got_slack = GNUNET_YES;   /* do not defer this one! */
  me->sender_status = n->status;
  GNUNET_CONTAINER_DLL_insert_after (n->encrypted_head, n->encrypted_tail,
                                     n->encrypted_tail, me);
  sm = (struct SetKeyMessage *) &me[1];
  sm->header.size = htons (sizeof (struct SetKeyMessage));
  sm->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_SET_KEY);
  sm->sender_status =
      htonl ((int32_t)
             ((n->status ==
               PEER_STATE_DOWN) ? PEER_STATE_KEY_SENT : n->status));
  sm->purpose.size =
      htonl (sizeof (struct GNUNET_CRYPTO_RsaSignaturePurpose) +
             sizeof (struct GNUNET_TIME_AbsoluteNBO) +
             sizeof (struct GNUNET_CRYPTO_RsaEncryptedData) +
             sizeof (struct GNUNET_PeerIdentity));
  sm->purpose.purpose = htonl (GNUNET_SIGNATURE_PURPOSE_SET_KEY);
  sm->creation_time = GNUNET_TIME_absolute_hton (n->encrypt_key_created);
  sm->target = n->peer;
  GNUNET_assert (GNUNET_OK ==
                 GNUNET_CRYPTO_rsa_encrypt (&n->encrypt_key,
                                            sizeof (struct
                                                    GNUNET_CRYPTO_AesSessionKey),
                                            n->public_key, &sm->encrypted_key));
  GNUNET_assert (GNUNET_OK ==
                 GNUNET_CRYPTO_rsa_sign (my_private_key, &sm->purpose,
                                         &sm->signature));
  pm = (struct PingMessage *) &sm[1];
  pm->header.size = htons (sizeof (struct PingMessage));
  pm->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_PING);
  pm->iv_seed =
      GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX);
  derive_iv (&iv, &n->encrypt_key, pm->iv_seed, &n->peer);
  pp.challenge = n->ping_challenge;
  pp.target = n->peer;
#if DEBUG_HANDSHAKE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Encrypting `%s' and `%s' messages with challenge %u for `%4s' using key %u, IV %u (salt %u).\n",
              "SET_KEY", "PING", (unsigned int) n->ping_challenge,
              GNUNET_i2s (&n->peer), (unsigned int) n->encrypt_key.crc32,
              GNUNET_CRYPTO_crc32_n (&iv, sizeof (iv)), pm->iv_seed);
#endif
  do_encrypt (n, &iv, &pp.target, &pm->target,
              sizeof (struct PingMessage) - ((void *) &pm->target -
                                             (void *) pm));
  GNUNET_STATISTICS_update (stats,
                            gettext_noop
                            ("# SET_KEY and PING messages created"), 1,
                            GNUNET_NO);
#if DEBUG_CORE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Have %llu ms left for `%s' transmission.\n",
              (unsigned long long)
              GNUNET_TIME_absolute_get_remaining (me->deadline).rel_value,
              "SET_KEY");
#endif
trigger_processing:
  /* trigger queue processing */
  process_encrypted_neighbour_queue (n);
  if ((n->status != PEER_STATE_KEY_CONFIRMED) &&
      (GNUNET_SCHEDULER_NO_TASK == n->retry_set_key_task))
    n->retry_set_key_task =
        GNUNET_SCHEDULER_add_delayed (n->set_key_retry_frequency,
                                      &set_key_retry_task, n);
}


/**
 * We received a SET_KEY message.  Validate and update
 * our key material and status.
 *
 * @param n the neighbour from which we received message m
 * @param m the set key message we received
 * @param ats performance data
 * @param ats_count number of entries in ats (excluding 0-termination)
 */
static void
handle_set_key (struct Neighbour *n, const struct SetKeyMessage *m,
                const struct GNUNET_TRANSPORT_ATS_Information *ats,
                uint32_t ats_count);



/**
 * PEERINFO is giving us a HELLO for a peer.  Add the public key to
 * the neighbour's struct and retry handling the set_key message.  Or,
 * if we did not get a HELLO, just free the set key message.
 *
 * @param cls pointer to the set key message
 * @param peer the peer for which this is the HELLO
 * @param hello HELLO message of that peer
 * @param err_msg NULL if successful, otherwise contains error message
 */
static void
process_hello_retry_handle_set_key (void *cls,
                                    const struct GNUNET_PeerIdentity *peer,
                                    const struct GNUNET_HELLO_Message *hello,
                                    const char *err_msg)
{
  struct Neighbour *n = cls;
  struct SetKeyMessage *sm = n->skm;

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

  if (peer == NULL)
  {
    n->skm = NULL;
    n->pitr = NULL;
    if (n->public_key != NULL)
    {
#if DEBUG_CORE
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Received `%s' for `%4s', continuing processing of `%s' message.\n",
                  "HELLO", GNUNET_i2s (&n->peer), "SET_KEY");
#endif
      handle_set_key (n, sm, NULL, 0);
    }
    else
    {
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  _
                  ("Ignoring `%s' message due to lack of public key for peer `%4s' (failed to obtain one).\n"),
                  "SET_KEY", GNUNET_i2s (&n->peer));
    }
    GNUNET_free (sm);
    return;
  }
  if (n->public_key != NULL)
    return;                     /* multiple HELLOs match!? */
  n->public_key =
      GNUNET_malloc (sizeof (struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded));
  if (GNUNET_OK != GNUNET_HELLO_get_key (hello, n->public_key))
  {
    GNUNET_break_op (0);
    GNUNET_free (n->public_key);
    n->public_key = NULL;
  }
}


/**
 * Merge the given performance data with the data we currently
 * track for the given neighbour.
 *
 * @param n neighbour
 * @param ats new performance data
 * @param ats_count number of records in ats
 */
static void
update_neighbour_performance (struct Neighbour *n,
                              const struct GNUNET_TRANSPORT_ATS_Information
                              *ats, uint32_t ats_count)
{
  uint32_t i;
  unsigned int j;

  if (ats_count == 0)
    return;
  for (i = 0; i < ats_count; i++)
  {
    for (j = 0; j < n->ats_count; j++)
    {
      if (n->ats[j].type == ats[i].type)
      {
        n->ats[j].value = ats[i].value;
        break;
      }
    }
    if (j == n->ats_count)
    {
      GNUNET_array_append (n->ats, n->ats_count, ats[i]);
    }
  }
}


/**
 * We received a PING message.  Validate and transmit
 * PONG.
 *
 * @param n sender of the PING
 * @param m the encrypted PING message itself
 * @param ats performance data
 * @param ats_count number of entries in ats (excluding 0-termination)
 */
static void
handle_ping (struct Neighbour *n, const struct PingMessage *m,
             const struct GNUNET_TRANSPORT_ATS_Information *ats,
             uint32_t ats_count)
{
  struct PingMessage t;
  struct PongMessage tx;
  struct PongMessage *tp;
  struct MessageEntry *me;
  struct GNUNET_CRYPTO_AesInitializationVector iv;

#if DEBUG_CORE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Core service receives `%s' request from `%4s'.\n", "PING",
              GNUNET_i2s (&n->peer));
#endif
  derive_iv (&iv, &n->decrypt_key, m->iv_seed, &my_identity);
  if (GNUNET_OK !=
      do_decrypt (n, &iv, &m->target, &t.target,
                  sizeof (struct PingMessage) - ((void *) &m->target -
                                                 (void *) m)))
    return;
#if DEBUG_HANDSHAKE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Decrypted `%s' to `%4s' with challenge %u decrypted using key %u, IV %u (salt %u)\n",
              "PING", GNUNET_i2s (&t.target), (unsigned int) t.challenge,
              (unsigned int) n->decrypt_key.crc32, GNUNET_CRYPTO_crc32_n (&iv,
                                                                          sizeof
                                                                          (iv)),
              m->iv_seed);
#endif
  GNUNET_STATISTICS_update (stats, gettext_noop ("# PING messages decrypted"),
                            1, GNUNET_NO);
  if (0 !=
      memcmp (&t.target, &my_identity, sizeof (struct GNUNET_PeerIdentity)))
  {
    char sender[9];
    char peer[9];

    GNUNET_snprintf (sender, sizeof (sender), "%8s", GNUNET_i2s (&n->peer));
    GNUNET_snprintf (peer, sizeof (peer), "%8s", GNUNET_i2s (&t.target));
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                _
                ("Received PING from `%s' for different identity: I am `%s', PONG identity: `%s'\n"),
                sender, GNUNET_i2s (&my_identity), peer);
    GNUNET_break_op (0);
    return;
  }
  update_neighbour_performance (n, ats, ats_count);
  me = GNUNET_malloc (sizeof (struct MessageEntry) +
                      sizeof (struct PongMessage));
  GNUNET_CONTAINER_DLL_insert_after (n->encrypted_head, n->encrypted_tail,
                                     n->encrypted_tail, me);
  me->deadline = GNUNET_TIME_relative_to_absolute (MAX_PONG_DELAY);
  me->priority = PONG_PRIORITY;
  me->size = sizeof (struct PongMessage);
  tx.inbound_bw_limit = n->bw_in;
  tx.challenge = t.challenge;
  tx.target = t.target;
  tp = (struct PongMessage *) &me[1];
  tp->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_PONG);
  tp->header.size = htons (sizeof (struct PongMessage));
  tp->iv_seed =
      GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX);
  derive_pong_iv (&iv, &n->encrypt_key, tp->iv_seed, t.challenge, &n->peer);
  do_encrypt (n, &iv, &tx.challenge, &tp->challenge,
              sizeof (struct PongMessage) - ((void *) &tp->challenge -
                                             (void *) tp));
  GNUNET_STATISTICS_update (stats, gettext_noop ("# PONG messages created"), 1,
                            GNUNET_NO);
#if DEBUG_HANDSHAKE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Encrypting `%s' with challenge %u using key %u, IV %u (salt %u)\n",
              "PONG", (unsigned int) t.challenge,
              (unsigned int) n->encrypt_key.crc32, GNUNET_CRYPTO_crc32_n (&iv,
                                                                          sizeof
                                                                          (iv)),
              tp->iv_seed);
#endif
  /* trigger queue processing */
  process_encrypted_neighbour_queue (n);
}


/**
 * We received a PONG message.  Validate and update our status.
 *
 * @param n sender of the PONG
 * @param m the encrypted PONG message itself
 * @param ats performance data
 * @param ats_count number of entries in ats (excluding 0-termination)
 */
static void
handle_pong (struct Neighbour *n, const struct PongMessage *m,
             const struct GNUNET_TRANSPORT_ATS_Information *ats,
             uint32_t ats_count)
{
  struct PongMessage t;
  struct ConnectNotifyMessage *cnm;
  struct GNUNET_CRYPTO_AesInitializationVector iv;
  char buf[GNUNET_SERVER_MAX_MESSAGE_SIZE - 1];
  struct GNUNET_TRANSPORT_ATS_Information *mats;
  size_t size;

#if DEBUG_HANDSHAKE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Core service receives `%s' response from `%4s'.\n", "PONG",
              GNUNET_i2s (&n->peer));
#endif
  /* mark as garbage, just to be sure */
  memset (&t, 255, sizeof (t));
  derive_pong_iv (&iv, &n->decrypt_key, m->iv_seed, n->ping_challenge,
                  &my_identity);
  if (GNUNET_OK !=
      do_decrypt (n, &iv, &m->challenge, &t.challenge,
                  sizeof (struct PongMessage) - ((void *) &m->challenge -
                                                 (void *) m)))
  {
    GNUNET_break_op (0);
    return;
  }
  GNUNET_STATISTICS_update (stats, gettext_noop ("# PONG messages decrypted"),
                            1, GNUNET_NO);
#if DEBUG_HANDSHAKE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Decrypted `%s' from `%4s' with challenge %u using key %u, IV %u (salt %u)\n",
              "PONG", GNUNET_i2s (&t.target), (unsigned int) t.challenge,
              (unsigned int) n->decrypt_key.crc32, GNUNET_CRYPTO_crc32_n (&iv,
                                                                          sizeof
                                                                          (iv)),
              m->iv_seed);
#endif
  if ((0 != memcmp (&t.target, &n->peer, sizeof (struct GNUNET_PeerIdentity)))
      || (n->ping_challenge != t.challenge))
  {
    /* PONG malformed */
#if DEBUG_CORE
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Received malformed `%s' wanted sender `%4s' with challenge %u\n",
                "PONG", GNUNET_i2s (&n->peer),
                (unsigned int) n->ping_challenge);
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Received malformed `%s' received from `%4s' with challenge %u\n",
                "PONG", GNUNET_i2s (&t.target), (unsigned int) t.challenge);
#endif
    GNUNET_break_op (n->ping_challenge != t.challenge);
    return;
  }
  switch (n->status)
  {
  case PEER_STATE_DOWN:
    GNUNET_break (0);           /* should be impossible */
    return;
  case PEER_STATE_KEY_SENT:
    GNUNET_break (0);           /* should be impossible, how did we decrypt? */
    return;
  case PEER_STATE_KEY_RECEIVED:
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# Session keys confirmed via PONG"), 1,
                              GNUNET_NO);
    n->status = PEER_STATE_KEY_CONFIRMED;
    {
      struct GNUNET_MessageHeader *hdr;

      hdr = compute_type_map_message ();
      send_type_map_to_neighbour (hdr, &n->peer.hashPubKey, n);
      GNUNET_free (hdr);
    }
    if (n->bw_out_external_limit.value__ != t.inbound_bw_limit.value__)
    {
      n->bw_out_external_limit = t.inbound_bw_limit;
      n->bw_out =
          GNUNET_BANDWIDTH_value_min (n->bw_out_external_limit,
                                      n->bw_out_internal_limit);
      GNUNET_BANDWIDTH_tracker_update_quota (&n->available_send_window,
                                             n->bw_out);
      GNUNET_TRANSPORT_set_quota (transport, &n->peer, n->bw_in, n->bw_out);
    }
#if DEBUG_CORE
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Confirmed key via `%s' message for peer `%4s'\n", "PONG",
                GNUNET_i2s (&n->peer));
#endif
    if (n->retry_set_key_task != GNUNET_SCHEDULER_NO_TASK)
    {
      GNUNET_SCHEDULER_cancel (n->retry_set_key_task);
      n->retry_set_key_task = GNUNET_SCHEDULER_NO_TASK;
    }
    update_neighbour_performance (n, ats, ats_count);
    size =
        sizeof (struct ConnectNotifyMessage) +
        (n->ats_count) * sizeof (struct GNUNET_TRANSPORT_ATS_Information);
    if (size >= GNUNET_SERVER_MAX_MESSAGE_SIZE)
    {
      GNUNET_break (0);
      /* recovery strategy: throw away performance data */
      GNUNET_array_grow (n->ats, n->ats_count, 0);
      size =
          sizeof (struct PeerStatusNotifyMessage) +
          n->ats_count * sizeof (struct GNUNET_TRANSPORT_ATS_Information);
    }
    cnm = (struct ConnectNotifyMessage *) buf;
    cnm->header.size = htons (size);
    cnm->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_NOTIFY_CONNECT);
    cnm->ats_count = htonl (n->ats_count);
    cnm->peer = n->peer;
    mats = &cnm->ats;
    memcpy (mats, n->ats,
            n->ats_count * sizeof (struct GNUNET_TRANSPORT_ATS_Information));
    mats[n->ats_count].type = htonl (GNUNET_TRANSPORT_ATS_ARRAY_TERMINATOR);
    mats[n->ats_count].value = htonl (0);
    send_to_all_clients (&cnm->header, GNUNET_NO,
                         GNUNET_CORE_OPTION_SEND_CONNECT);
    process_encrypted_neighbour_queue (n);
    /* fall-through! */
  case PEER_STATE_KEY_CONFIRMED:
    n->last_activity = GNUNET_TIME_absolute_get ();
    if (n->keep_alive_task != GNUNET_SCHEDULER_NO_TASK)
      GNUNET_SCHEDULER_cancel (n->keep_alive_task);
    n->keep_alive_task =
        GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_relative_divide
                                      (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT,
                                       2), &send_keep_alive, n);
    handle_peer_status_change (n);
    break;
  default:
    GNUNET_break (0);
    break;
  }
}


/**
 * We received a SET_KEY message.  Validate and update
 * our key material and status.
 *
 * @param n the neighbour from which we received message m
 * @param m the set key message we received
 * @param ats performance data
 * @param ats_count number of entries in ats (excluding 0-termination)
 */
static void
handle_set_key (struct Neighbour *n, const struct SetKeyMessage *m,
                const struct GNUNET_TRANSPORT_ATS_Information *ats,
                uint32_t ats_count)
{
  struct SetKeyMessage *m_cpy;
  struct GNUNET_TIME_Absolute t;
  struct GNUNET_CRYPTO_AesSessionKey k;
  struct PingMessage *ping;
  struct PongMessage *pong;
  enum PeerStateMachine sender_status;

#if DEBUG_CORE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Core service receives `%s' request from `%4s'.\n", "SET_KEY",
              GNUNET_i2s (&n->peer));
#endif
  if (n->public_key == NULL)
  {
    if (n->pitr != NULL)
    {
#if DEBUG_CORE
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Ignoring `%s' message due to lack of public key for peer (still trying to obtain one).\n",
                  "SET_KEY");
#endif
      return;
    }
#if DEBUG_CORE
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Lacking public key for peer, trying to obtain one (handle_set_key).\n");
#endif
    m_cpy = GNUNET_malloc (sizeof (struct SetKeyMessage));
    memcpy (m_cpy, m, sizeof (struct SetKeyMessage));
    /* lookup n's public key, then try again */
    GNUNET_assert (n->skm == NULL);
    n->skm = m_cpy;
    n->pitr =
        GNUNET_PEERINFO_iterate (peerinfo, &n->peer, GNUNET_TIME_UNIT_MINUTES,
                                 &process_hello_retry_handle_set_key, n);
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# SET_KEY messages deferred (need public key)"),
                              1, GNUNET_NO);
    return;
  }
  if (0 !=
      memcmp (&m->target, &my_identity, sizeof (struct GNUNET_PeerIdentity)))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                _
                ("Received `%s' message that was for `%s', not for me.  Ignoring.\n"),
                "SET_KEY", GNUNET_i2s (&m->target));
    return;
  }
  if ((ntohl (m->purpose.size) !=
       sizeof (struct GNUNET_CRYPTO_RsaSignaturePurpose) +
       sizeof (struct GNUNET_TIME_AbsoluteNBO) +
       sizeof (struct GNUNET_CRYPTO_RsaEncryptedData) +
       sizeof (struct GNUNET_PeerIdentity)) ||
      (GNUNET_OK !=
       GNUNET_CRYPTO_rsa_verify (GNUNET_SIGNATURE_PURPOSE_SET_KEY, &m->purpose,
                                 &m->signature, n->public_key)))
  {
    /* invalid signature */
    GNUNET_break_op (0);
    return;
  }
  t = GNUNET_TIME_absolute_ntoh (m->creation_time);
  if (((n->status == PEER_STATE_KEY_RECEIVED) ||
       (n->status == PEER_STATE_KEY_CONFIRMED)) &&
      (t.abs_value < n->decrypt_key_created.abs_value))
  {
    /* this could rarely happen due to massive re-ordering of
     * messages on the network level, but is most likely either
     * a bug or some adversary messing with us.  Report. */
    GNUNET_break_op (0);
    return;
  }
#if DEBUG_CORE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Decrypting key material.\n");
#endif
  if ((GNUNET_CRYPTO_rsa_decrypt
       (my_private_key, &m->encrypted_key, &k,
        sizeof (struct GNUNET_CRYPTO_AesSessionKey)) !=
       sizeof (struct GNUNET_CRYPTO_AesSessionKey)) ||
      (GNUNET_OK != GNUNET_CRYPTO_aes_check_session_key (&k)))
  {
    /* failed to decrypt !? */
    GNUNET_break_op (0);
    return;
  }
  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# SET_KEY messages decrypted"), 1,
                            GNUNET_NO);
  n->decrypt_key = k;
  if (n->decrypt_key_created.abs_value != t.abs_value)
  {
    /* fresh key, reset sequence numbers */
    n->last_sequence_number_received = 0;
    n->last_packets_bitmap = 0;
    n->decrypt_key_created = t;
  }
  update_neighbour_performance (n, ats, ats_count);
  sender_status = (enum PeerStateMachine) ntohl (m->sender_status);
  switch (n->status)
  {
  case PEER_STATE_DOWN:
    n->status = PEER_STATE_KEY_RECEIVED;
#if DEBUG_CORE
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Responding to `%s' with my own key.\n", "SET_KEY");
#endif
    send_key (n);
    break;
  case PEER_STATE_KEY_SENT:
  case PEER_STATE_KEY_RECEIVED:
    n->status = PEER_STATE_KEY_RECEIVED;
    if ((sender_status != PEER_STATE_KEY_RECEIVED) &&
        (sender_status != PEER_STATE_KEY_CONFIRMED))
    {
#if DEBUG_CORE
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Responding to `%s' with my own key (other peer has status %u).\n",
                  "SET_KEY", (unsigned int) sender_status);
#endif
      send_key (n);
    }
    break;
  case PEER_STATE_KEY_CONFIRMED:
    if ((sender_status != PEER_STATE_KEY_RECEIVED) &&
        (sender_status != PEER_STATE_KEY_CONFIRMED))
    {
#if DEBUG_CORE
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Responding to `%s' with my own key (other peer has status %u), I was already fully up.\n",
                  "SET_KEY", (unsigned int) sender_status);
#endif
      send_key (n);
    }
    break;
  default:
    GNUNET_break (0);
    break;
  }
  if (n->pending_ping != NULL)
  {
    ping = n->pending_ping;
    n->pending_ping = NULL;
    handle_ping (n, ping, NULL, 0);
    GNUNET_free (ping);
  }
  if (n->pending_pong != NULL)
  {
    pong = n->pending_pong;
    n->pending_pong = NULL;
    handle_pong (n, pong, NULL, 0);
    GNUNET_free (pong);
  }
}


/**
 * Send a P2P message to a client.
 *
 * @param sender who sent us the message?
 * @param client who should we give the message to?
 * @param m contains the message to transmit
 * @param msize number of bytes in buf to transmit
 */
static void
send_p2p_message_to_client (struct Neighbour *sender, struct Client *client,
                            const void *m, size_t msize)
{
  size_t size =
      msize + sizeof (struct NotifyTrafficMessage) +
      (sender->ats_count) * sizeof (struct GNUNET_TRANSPORT_ATS_Information);
  char buf[size];
  struct NotifyTrafficMessage *ntm;
  struct GNUNET_TRANSPORT_ATS_Information *ats;

  GNUNET_assert (GNUNET_YES == sender->is_connected);
  if (size >= GNUNET_SERVER_MAX_MESSAGE_SIZE)
  {
    GNUNET_break (0);
    /* recovery strategy: throw performance data away... */
    GNUNET_array_grow (sender->ats, sender->ats_count, 0);
    size =
        msize + sizeof (struct NotifyTrafficMessage) +
        (sender->ats_count) * sizeof (struct GNUNET_TRANSPORT_ATS_Information);
  }
#if DEBUG_CORE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Core service passes message from `%4s' of type %u to client.\n",
              GNUNET_i2s (&sender->peer),
              (unsigned int)
              ntohs (((const struct GNUNET_MessageHeader *) m)->type));
#endif
  ntm = (struct NotifyTrafficMessage *) buf;
  ntm->header.size = htons (size);
  ntm->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_NOTIFY_INBOUND);
  ntm->ats_count = htonl (sender->ats_count);
  ntm->peer = sender->peer;
  ats = &ntm->ats;
  memcpy (ats, sender->ats,
          sizeof (struct GNUNET_TRANSPORT_ATS_Information) * sender->ats_count);
  ats[sender->ats_count].type = htonl (GNUNET_TRANSPORT_ATS_ARRAY_TERMINATOR);
  ats[sender->ats_count].value = htonl (0);
  memcpy (&ats[sender->ats_count + 1], m, msize);
  send_to_client (client, &ntm->header, GNUNET_YES);
}


/**
 * Deliver P2P message to interested clients.
 *
 * @param cls always NULL
 * @param client who sent us the message (struct Neighbour)
 * @param m the message
 */
static void
deliver_message (void *cls, void *client, const struct GNUNET_MessageHeader *m)
{
  struct Neighbour *sender = client;
  size_t msize = ntohs (m->size);
  char buf[256];
  struct Client *cpos;
  uint16_t type;
  unsigned int tpos;
  int deliver_full;
  int dropped;

  type = ntohs (m->type);
#if DEBUG_CORE > 1
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Received encapsulated message of type %u and size %u from `%4s'\n",
              (unsigned int) type, ntohs (m->size), GNUNET_i2s (&sender->peer));
#endif
  GNUNET_snprintf (buf, sizeof (buf),
                   gettext_noop ("# bytes of messages of type %u received"),
                   (unsigned int) type);
  GNUNET_STATISTICS_update (stats, buf, msize, GNUNET_NO);
  if ((GNUNET_MESSAGE_TYPE_CORE_BINARY_TYPE_MAP == type) ||
      (GNUNET_MESSAGE_TYPE_CORE_COMPRESSED_TYPE_MAP == type))
  {
    /* FIXME: update message type map for 'Neighbour' */
    return;
  }
  dropped = GNUNET_YES;
  cpos = clients;
  while (cpos != NULL)
  {
    deliver_full = GNUNET_NO;
    if (0 != (cpos->options & GNUNET_CORE_OPTION_SEND_FULL_INBOUND))
      deliver_full = GNUNET_YES;
    else
    {
      for (tpos = 0; tpos < cpos->tcnt; tpos++)
      {
        if (type != cpos->types[tpos])
          continue;
        deliver_full = GNUNET_YES;
        break;
      }
    }
    if (GNUNET_YES == deliver_full)
    {
      send_p2p_message_to_client (sender, cpos, m, msize);
      dropped = GNUNET_NO;
    }
    else if (cpos->options & GNUNET_CORE_OPTION_SEND_HDR_INBOUND)
    {
      send_p2p_message_to_client (sender, cpos, m,
                                  sizeof (struct GNUNET_MessageHeader));
    }
    cpos = cpos->next;
  }
  if (dropped == GNUNET_YES)
  {
#if DEBUG_CORE
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Message of type %u from `%4s' not delivered to any client.\n",
                (unsigned int) type, GNUNET_i2s (&sender->peer));
#endif
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# messages not delivered to any client"), 1,
                              GNUNET_NO);
  }
}


/**
 * We received an encrypted message.  Decrypt, validate and
 * pass on to the appropriate clients.
 *
 * @param n target of the message
 * @param m encrypted message
 * @param ats performance data
 * @param ats_count number of entries in ats (excluding 0-termination)
 */
static void
handle_encrypted_message (struct Neighbour *n, const struct EncryptedMessage *m,
                          const struct GNUNET_TRANSPORT_ATS_Information *ats,
                          uint32_t ats_count)
{
  size_t size = ntohs (m->header.size);
  char buf[size];
  struct EncryptedMessage *pt;  /* plaintext */
  GNUNET_HashCode ph;
  uint32_t snum;
  struct GNUNET_TIME_Absolute t;
  struct GNUNET_CRYPTO_AesInitializationVector iv;
  struct GNUNET_CRYPTO_AuthKey auth_key;

#if DEBUG_CORE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Core service receives `%s' request from `%4s'.\n",
              "ENCRYPTED_MESSAGE", GNUNET_i2s (&n->peer));
#endif
  /* validate hash */
  derive_auth_key (&auth_key, &n->decrypt_key, m->iv_seed,
                   n->decrypt_key_created);
  GNUNET_CRYPTO_hmac (&auth_key, &m->sequence_number,
                      size - ENCRYPTED_HEADER_SIZE, &ph);
#if DEBUG_HANDSHAKE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Re-Authenticated %u bytes of ciphertext (`%u'): `%s'\n",
              (unsigned int) size - ENCRYPTED_HEADER_SIZE,
              GNUNET_CRYPTO_crc32_n (&m->sequence_number,
                                     size - ENCRYPTED_HEADER_SIZE),
              GNUNET_h2s (&ph));
#endif

  if (0 != memcmp (&ph, &m->hmac, sizeof (GNUNET_HashCode)))
  {
    /* checksum failed */
    GNUNET_break_op (0);
    return;
  }
  derive_iv (&iv, &n->decrypt_key, m->iv_seed, &my_identity);
  /* decrypt */
  if (GNUNET_OK !=
      do_decrypt (n, &iv, &m->sequence_number, &buf[ENCRYPTED_HEADER_SIZE],
                  size - ENCRYPTED_HEADER_SIZE))
    return;
  pt = (struct EncryptedMessage *) buf;

  /* validate sequence number */
  snum = ntohl (pt->sequence_number);
  if (n->last_sequence_number_received == snum)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                "Received duplicate message, ignoring.\n");
    /* duplicate, ignore */
    GNUNET_STATISTICS_update (stats,
                              gettext_noop ("# bytes dropped (duplicates)"),
                              size, GNUNET_NO);
    return;
  }
  if ((n->last_sequence_number_received > snum) &&
      (n->last_sequence_number_received - snum > 32))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                "Received ancient out of sequence message, ignoring.\n");
    /* ancient out of sequence, ignore */
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# bytes dropped (out of sequence)"), size,
                              GNUNET_NO);
    return;
  }
  if (n->last_sequence_number_received > snum)
  {
    unsigned int rotbit = 1 << (n->last_sequence_number_received - snum - 1);

    if ((n->last_packets_bitmap & rotbit) != 0)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                  "Received duplicate message, ignoring.\n");
      GNUNET_STATISTICS_update (stats,
                                gettext_noop ("# bytes dropped (duplicates)"),
                                size, GNUNET_NO);
      /* duplicate, ignore */
      return;
    }
    n->last_packets_bitmap |= rotbit;
  }
  if (n->last_sequence_number_received < snum)
  {
    int shift = (snum - n->last_sequence_number_received);

    if (shift >= 8 * sizeof (n->last_packets_bitmap))
      n->last_packets_bitmap = 0;
    else
      n->last_packets_bitmap <<= shift;
    n->last_sequence_number_received = snum;
  }

  /* check timestamp */
  t = GNUNET_TIME_absolute_ntoh (pt->timestamp);
  if (GNUNET_TIME_absolute_get_duration (t).rel_value >
      MAX_MESSAGE_AGE.rel_value)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                _("Message received far too old (%llu ms). Content ignored.\n"),
                GNUNET_TIME_absolute_get_duration (t).rel_value);
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("# bytes dropped (ancient message)"), size,
                              GNUNET_NO);
    return;
  }

  /* process decrypted message(s) */
  if (n->bw_out_external_limit.value__ != pt->inbound_bw_limit.value__)
  {
#if DEBUG_CORE_SET_QUOTA
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Received %u b/s as new inbound limit for peer `%4s'\n",
                (unsigned int) ntohl (pt->inbound_bw_limit.value__),
                GNUNET_i2s (&n->peer));
#endif
    n->bw_out_external_limit = pt->inbound_bw_limit;
    n->bw_out =
        GNUNET_BANDWIDTH_value_min (n->bw_out_external_limit,
                                    n->bw_out_internal_limit);
    GNUNET_BANDWIDTH_tracker_update_quota (&n->available_send_window,
                                           n->bw_out);
    GNUNET_TRANSPORT_set_quota (transport, &n->peer, n->bw_in, n->bw_out);
  }
  n->last_activity = GNUNET_TIME_absolute_get ();
  if (n->keep_alive_task != GNUNET_SCHEDULER_NO_TASK)
    GNUNET_SCHEDULER_cancel (n->keep_alive_task);
  n->keep_alive_task =
      GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_relative_divide
                                    (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT,
                                     2), &send_keep_alive, n);
  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# bytes of payload decrypted"),
                            size - sizeof (struct EncryptedMessage), GNUNET_NO);
  handle_peer_status_change (n);
  update_neighbour_performance (n, ats, ats_count);
  if (GNUNET_OK !=
      GNUNET_SERVER_mst_receive (mst, n, &buf[sizeof (struct EncryptedMessage)],
                                 size - sizeof (struct EncryptedMessage),
                                 GNUNET_YES, GNUNET_NO))
    GNUNET_break_op (0);
}


/**
 * Function called by the transport for each received message.
 *
 * @param cls closure
 * @param peer (claimed) identity of the other peer
 * @param message the message
 * @param ats performance data
 * @param ats_count number of entries in ats (excluding 0-termination)
 */
static void
handle_transport_receive (void *cls, const struct GNUNET_PeerIdentity *peer,
                          const struct GNUNET_MessageHeader *message,
                          const struct GNUNET_TRANSPORT_ATS_Information *ats,
                          uint32_t ats_count)
{
  struct Neighbour *n;
  struct GNUNET_TIME_Absolute now;
  int up;
  uint16_t type;
  uint16_t size;
  int changed;

#if DEBUG_CORE > 1
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Received message of type %u from `%4s', demultiplexing.\n",
              (unsigned int) ntohs (message->type), GNUNET_i2s (peer));
#endif
  if (0 == memcmp (peer, &my_identity, sizeof (struct GNUNET_PeerIdentity)))
  {
    GNUNET_break (0);
    return;
  }
  n = find_neighbour (peer);
  if ((n == NULL) || (GNUNET_NO == n->is_connected))
  {
    /* received message from peer that is not connected!? */
    GNUNET_break (0);
    return;
  }
  changed = GNUNET_NO;
  up = (n->status == PEER_STATE_KEY_CONFIRMED);
  type = ntohs (message->type);
  size = ntohs (message->size);
  switch (type)
  {
  case GNUNET_MESSAGE_TYPE_CORE_SET_KEY:
    if (size != sizeof (struct SetKeyMessage))
    {
      GNUNET_break_op (0);
      return;
    }
    GNUNET_STATISTICS_update (stats, gettext_noop ("# session keys received"),
                              1, GNUNET_NO);
    handle_set_key (n, (const struct SetKeyMessage *) message, ats, ats_count);
    break;
  case GNUNET_MESSAGE_TYPE_CORE_ENCRYPTED_MESSAGE:
    if (size <
        sizeof (struct EncryptedMessage) + sizeof (struct GNUNET_MessageHeader))
    {
      GNUNET_break_op (0);
      return;
    }
    if ((n->status != PEER_STATE_KEY_RECEIVED) &&
        (n->status != PEER_STATE_KEY_CONFIRMED))
    {
      GNUNET_STATISTICS_update (stats,
                                gettext_noop
                                ("# failed to decrypt message (no session key)"),
                                1, GNUNET_NO);
      send_key (n);
      return;
    }
    handle_encrypted_message (n, (const struct EncryptedMessage *) message, ats,
                              ats_count);
    break;
  case GNUNET_MESSAGE_TYPE_CORE_PING:
    if (size != sizeof (struct PingMessage))
    {
      GNUNET_break_op (0);
      return;
    }
    GNUNET_STATISTICS_update (stats, gettext_noop ("# PING messages received"),
                              1, GNUNET_NO);
    if ((n->status != PEER_STATE_KEY_RECEIVED) &&
        (n->status != PEER_STATE_KEY_CONFIRMED))
    {
#if DEBUG_CORE > 1
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Core service receives `%s' request from `%4s' but have not processed key; marking as pending.\n",
                  "PING", GNUNET_i2s (&n->peer));
#endif
      GNUNET_free_non_null (n->pending_ping);
      n->pending_ping = GNUNET_malloc (sizeof (struct PingMessage));
      memcpy (n->pending_ping, message, sizeof (struct PingMessage));
      return;
    }
    handle_ping (n, (const struct PingMessage *) message, ats, ats_count);
    break;
  case GNUNET_MESSAGE_TYPE_CORE_PONG:
    if (size != sizeof (struct PongMessage))
    {
      GNUNET_break_op (0);
      return;
    }
    GNUNET_STATISTICS_update (stats, gettext_noop ("# PONG messages received"),
                              1, GNUNET_NO);
    if ((n->status != PEER_STATE_KEY_RECEIVED) &&
        (n->status != PEER_STATE_KEY_CONFIRMED))
    {
#if DEBUG_CORE > 1
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Core service receives `%s' request from `%4s' but have not processed key; marking as pending.\n",
                  "PONG", GNUNET_i2s (&n->peer));
#endif
      GNUNET_free_non_null (n->pending_pong);
      n->pending_pong = GNUNET_malloc (sizeof (struct PongMessage));
      memcpy (n->pending_pong, message, sizeof (struct PongMessage));
      return;
    }
    handle_pong (n, (const struct PongMessage *) message, ats, ats_count);
    break;
  default:
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                _("Unsupported message of type %u received.\n"),
                (unsigned int) type);
    return;
  }
  if (n->status == PEER_STATE_KEY_CONFIRMED)
  {
    now = GNUNET_TIME_absolute_get ();
    n->last_activity = now;
    changed = GNUNET_YES;
    if (!up)
    {
      GNUNET_STATISTICS_update (stats, gettext_noop ("# established sessions"),
                                1, GNUNET_NO);
      n->time_established = now;
    }
    if (n->keep_alive_task != GNUNET_SCHEDULER_NO_TASK)
      GNUNET_SCHEDULER_cancel (n->keep_alive_task);
    n->keep_alive_task =
        GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_relative_divide
                                      (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT,
                                       2), &send_keep_alive, n);
  }
  if (changed)
    handle_peer_status_change (n);
}


/**
 * Function that recalculates the bandwidth quota for the
 * given neighbour and transmits it to the transport service.
 * 
 * @param cls neighbour for the quota update
 * @param tc context
 */
static void
neighbour_quota_update (void *cls,
                        const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct Neighbour *n = cls;
  struct GNUNET_BANDWIDTH_Value32NBO q_in;
  struct GNUNET_BANDWIDTH_Value32NBO q_out;
  struct GNUNET_BANDWIDTH_Value32NBO q_out_min;
  double pref_rel;
  double share;
  unsigned long long distributable;
  uint64_t need_per_peer;
  uint64_t need_per_second;
  unsigned int neighbour_count;

#if DEBUG_CORE > 1
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Neighbour quota update calculation running for peer `%4s'\n",
              GNUNET_i2s (&n->peer));
#endif
  n->quota_update_task = GNUNET_SCHEDULER_NO_TASK;
  /* calculate relative preference among all neighbours;
   * divides by a bit more to avoid division by zero AND to
   * account for possibility of new neighbours joining any time 
   * AND to convert to double... */
  neighbour_count = GNUNET_CONTAINER_multihashmap_size (neighbours);
  if (neighbour_count == 0)
    return;
  if (preference_sum == 0)
  {
    pref_rel = 1.0 / (double) neighbour_count;
  }
  else
  {
    pref_rel = (double) n->current_preference / preference_sum;
  }
  need_per_peer =
      GNUNET_BANDWIDTH_value_get_available_until (MIN_BANDWIDTH_PER_PEER,
                                                  GNUNET_TIME_UNIT_SECONDS);
  need_per_second = need_per_peer * neighbour_count;

  /* calculate inbound bandwidth per peer */
  distributable = 0;
  if (bandwidth_target_in_bps > need_per_second)
    distributable = bandwidth_target_in_bps - need_per_second;
  share = distributable * pref_rel;
  if (share + need_per_peer > UINT32_MAX)
    q_in = GNUNET_BANDWIDTH_value_init (UINT32_MAX);
  else
    q_in = GNUNET_BANDWIDTH_value_init (need_per_peer + (uint32_t) share);

  /* calculate outbound bandwidth per peer */
  distributable = 0;
  if (bandwidth_target_out_bps > need_per_second)
    distributable = bandwidth_target_out_bps - need_per_second;
  share = distributable * pref_rel;
  if (share + need_per_peer > UINT32_MAX)
    q_out = GNUNET_BANDWIDTH_value_init (UINT32_MAX);
  else
    q_out = GNUNET_BANDWIDTH_value_init (need_per_peer + (uint32_t) share);
  n->bw_out_internal_limit = q_out;

  q_out_min =
      GNUNET_BANDWIDTH_value_min (n->bw_out_external_limit,
                                  n->bw_out_internal_limit);
  GNUNET_BANDWIDTH_tracker_update_quota (&n->available_send_window, n->bw_out);

  /* check if we want to disconnect for good due to inactivity */
  if ((GNUNET_TIME_absolute_get_duration (get_neighbour_timeout (n)).rel_value >
       0) &&
      (GNUNET_TIME_absolute_get_duration (n->time_established).rel_value >
       GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT.rel_value))
  {
#if DEBUG_CORE
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Forcing disconnect of `%4s' due to inactivity\n",
                GNUNET_i2s (&n->peer));
#endif
    q_in = GNUNET_BANDWIDTH_value_init (0);     /* force disconnect */
  }
#if DEBUG_CORE_QUOTA
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Current quota for `%4s' is %u/%llu b/s in (old: %u b/s) / %u out (%u internal)\n",
              GNUNET_i2s (&n->peer), (unsigned int) ntohl (q_in.value__),
              bandwidth_target_out_bps, (unsigned int) ntohl (n->bw_in.value__),
              (unsigned int) ntohl (n->bw_out.value__),
              (unsigned int) ntohl (n->bw_out_internal_limit.value__));
#endif
  if ((n->bw_in.value__ != q_in.value__) ||
      (n->bw_out.value__ != q_out_min.value__))
  {
    if (n->bw_in.value__ != q_in.value__)
      n->bw_in = q_in;
    if (n->bw_out.value__ != q_out_min.value__)
      n->bw_out = q_out_min;
    if (GNUNET_YES == n->is_connected)
      GNUNET_TRANSPORT_set_quota (transport, &n->peer, n->bw_in, n->bw_out);
    handle_peer_status_change (n);
  }
  schedule_quota_update (n);
}


/**
 * Function called by transport to notify us that
 * a peer connected to us (on the network level).
 *
 * @param cls closure
 * @param peer the peer that connected
 * @param ats performance data
 * @param ats_count number of entries in ats (excluding 0-termination)
 */
static void
handle_transport_notify_connect (void *cls,
                                 const struct GNUNET_PeerIdentity *peer,
                                 const struct GNUNET_TRANSPORT_ATS_Information
                                 *ats, uint32_t ats_count)
{
  struct Neighbour *n;

  if (0 == memcmp (peer, &my_identity, sizeof (struct GNUNET_PeerIdentity)))
  {
    GNUNET_break (0);
    return;
  }
  n = find_neighbour (peer);
  if (n != NULL)
  {
    if (GNUNET_YES == n->is_connected)
    {
      /* duplicate connect notification!? */
      GNUNET_break (0);
      return;
    }
  }
  else
  {
    n = create_neighbour (peer);
  }
  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# peers connected (transport)"), 1,
                            GNUNET_NO);
  n->is_connected = GNUNET_YES;
  update_neighbour_performance (n, ats, ats_count);
  GNUNET_BANDWIDTH_tracker_init (&n->available_send_window, n->bw_out,
                                 MAX_WINDOW_TIME_S);
  GNUNET_BANDWIDTH_tracker_init (&n->available_recv_window, n->bw_in,
                                 MAX_WINDOW_TIME_S);
#if DEBUG_CORE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Received connection from `%4s'.\n",
              GNUNET_i2s (&n->peer));
#endif
  GNUNET_TRANSPORT_set_quota (transport, &n->peer, n->bw_in, n->bw_out);
  send_key (n);
}


/**
 * Function called by transport telling us that a peer
 * disconnected.
 *
 * @param cls closure
 * @param peer the peer that disconnected
 */
static void
handle_transport_notify_disconnect (void *cls,
                                    const struct GNUNET_PeerIdentity *peer)
{
  struct DisconnectNotifyMessage cnm;
  struct Neighbour *n;
  struct ClientActiveRequest *car;
  struct GNUNET_TIME_Relative left;

#if DEBUG_CORE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Peer `%4s' disconnected from us; received notification from transport.\n",
              GNUNET_i2s (peer));
#endif
  n = find_neighbour (peer);
  if (n == NULL)
  {
    GNUNET_break (0);
    return;
  }
  GNUNET_break (n->is_connected == GNUNET_YES);
  if (n->status == PEER_STATE_KEY_CONFIRMED)
  {
    cnm.header.size = htons (sizeof (struct DisconnectNotifyMessage));
    cnm.header.type = htons (GNUNET_MESSAGE_TYPE_CORE_NOTIFY_DISCONNECT);
    cnm.reserved = htonl (0);
    cnm.peer = *peer;
    send_to_all_clients (&cnm.header, GNUNET_NO,
                         GNUNET_CORE_OPTION_SEND_DISCONNECT);
    GNUNET_STATISTICS_update (stats, gettext_noop ("# established sessions"),
                              -1, GNUNET_NO);
  }

  /* On transport disconnect transport doesn't cancel requests, so must do so here. */
  if (n->th != NULL)
  {
    GNUNET_TRANSPORT_notify_transmit_ready_cancel (n->th);
    n->th = NULL;
  }
  if (GNUNET_SCHEDULER_NO_TASK != n->keep_alive_task)
  {
    GNUNET_SCHEDULER_cancel (n->keep_alive_task);
    n->keep_alive_task = GNUNET_SCHEDULER_NO_TASK;
  }
  n->is_connected = GNUNET_NO;
  n->status = PEER_STATE_DOWN;
  while (NULL != (car = n->active_client_request_head))
  {
    GNUNET_CONTAINER_DLL_remove (n->active_client_request_head,
                                 n->active_client_request_tail, car);
    GNUNET_assert (GNUNET_YES ==
                   GNUNET_CONTAINER_multihashmap_remove (car->client->requests,
                                                         &n->peer.hashPubKey,
                                                         car));
    GNUNET_free (car);
  }

  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# peers connected (transport)"), -1,
                            GNUNET_NO);
  if (n->dead_clean_task != GNUNET_SCHEDULER_NO_TASK)
    GNUNET_SCHEDULER_cancel (n->dead_clean_task);
  left =
      GNUNET_TIME_relative_subtract (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT,
                                     GNUNET_CONSTANTS_DISCONNECT_SESSION_TIMEOUT);
  n->last_activity =
      GNUNET_TIME_absolute_subtract (GNUNET_TIME_absolute_get (), left);
  n->dead_clean_task =
      GNUNET_SCHEDULER_add_delayed (GNUNET_CONSTANTS_DISCONNECT_SESSION_TIMEOUT,
                                    &consider_free_task, n);
}


/**
 * Wrapper around 'free_neighbour'; helper for 'cleaning_task'.
 */
static int
free_neighbour_helper (void *cls, const GNUNET_HashCode * key, void *value)
{
  struct Neighbour *n = value;

  free_neighbour (n);
  return GNUNET_OK;
}


/**
 * Last task run during shutdown.  Disconnects us from
 * the transport.
 */
static void
cleaning_task (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct Client *c;

#if DEBUG_CORE
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Core service shutting down.\n");
#endif
  GNUNET_assert (transport != NULL);
  GNUNET_TRANSPORT_disconnect (transport);
  transport = NULL;
  GNUNET_CONTAINER_multihashmap_iterate (neighbours, &free_neighbour_helper,
                                         NULL);
  GNUNET_CONTAINER_multihashmap_destroy (neighbours);
  neighbours = NULL;
  GNUNET_STATISTICS_set (stats, gettext_noop ("# neighbour entries allocated"),
                         0, GNUNET_NO);
  GNUNET_SERVER_notification_context_destroy (notifier);
  notifier = NULL;
  while (NULL != (c = clients))
    handle_client_disconnect (NULL, c->client_handle);
  if (my_private_key != NULL)
    GNUNET_CRYPTO_rsa_key_free (my_private_key);
  if (stats != NULL)
    GNUNET_STATISTICS_destroy (stats, GNUNET_NO);
  if (peerinfo != NULL)
    GNUNET_PEERINFO_disconnect (peerinfo);
  if (mst != NULL)
    GNUNET_SERVER_mst_destroy (mst);
}


/**
 * Initiate core 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_client_init, NULL,
     GNUNET_MESSAGE_TYPE_CORE_INIT, 0},
    {&handle_client_iterate_peers, NULL,
     GNUNET_MESSAGE_TYPE_CORE_ITERATE_PEERS,
     sizeof (struct GNUNET_MessageHeader)},
    {&handle_client_have_peer, NULL,
     GNUNET_MESSAGE_TYPE_CORE_PEER_CONNECTED,
     sizeof (struct GNUNET_MessageHeader) +
     sizeof (struct GNUNET_PeerIdentity)},
    {&handle_client_request_info, NULL,
     GNUNET_MESSAGE_TYPE_CORE_REQUEST_INFO,
     sizeof (struct RequestInfoMessage)},
    {&handle_client_send_request, NULL,
     GNUNET_MESSAGE_TYPE_CORE_SEND_REQUEST,
     sizeof (struct SendMessageRequest)},
    {&handle_client_send, NULL,
     GNUNET_MESSAGE_TYPE_CORE_SEND, 0},
    {&handle_client_request_connect, NULL,
     GNUNET_MESSAGE_TYPE_CORE_REQUEST_CONNECT,
     sizeof (struct ConnectMessage)},
    {NULL, NULL, 0, 0}
  };
  char *keyfile;

  cfg = c;
  /* parse configuration */
  if ((GNUNET_OK !=
       GNUNET_CONFIGURATION_get_value_number (c, "CORE", "TOTAL_QUOTA_IN",
                                              &bandwidth_target_in_bps)) ||
      (GNUNET_OK !=
       GNUNET_CONFIGURATION_get_value_number (c, "CORE", "TOTAL_QUOTA_OUT",
                                              &bandwidth_target_out_bps)) ||
      (GNUNET_OK !=
       GNUNET_CONFIGURATION_get_value_filename (c, "GNUNETD", "HOSTKEY",
                                                &keyfile)))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                _
                ("Core service is lacking key configuration settings.  Exiting.\n"));
    GNUNET_SCHEDULER_shutdown ();
    return;
  }
  peerinfo = GNUNET_PEERINFO_connect (cfg);
  if (NULL == peerinfo)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                _("Could not access PEERINFO service.  Exiting.\n"));
    GNUNET_SCHEDULER_shutdown ();
    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,
                _("Core service could not access hostkey.  Exiting.\n"));
    GNUNET_PEERINFO_disconnect (peerinfo);
    GNUNET_SCHEDULER_shutdown ();
    return;
  }
  neighbours = GNUNET_CONTAINER_multihashmap_create (128);
  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);
  self.public_key = &my_public_key;
  self.peer = my_identity;
  self.last_activity = GNUNET_TIME_UNIT_FOREVER_ABS;
  self.status = PEER_STATE_KEY_CONFIRMED;
  self.is_connected = GNUNET_YES;
  /* setup notification */
  notifier =
      GNUNET_SERVER_notification_context_create (server, MAX_NOTIFY_QUEUE);
  GNUNET_SERVER_disconnect_notify (server, &handle_client_disconnect, NULL);
  /* setup transport connection */
  transport =
      GNUNET_TRANSPORT_connect (cfg, &my_identity, NULL,
                                &handle_transport_receive,
                                &handle_transport_notify_connect,
                                &handle_transport_notify_disconnect);
  GNUNET_assert (NULL != transport);
  stats = GNUNET_STATISTICS_create ("core", cfg);

  GNUNET_STATISTICS_set (stats, gettext_noop ("# discarded CORE_SEND requests"),
                         0, GNUNET_NO);
  GNUNET_STATISTICS_set (stats,
                         gettext_noop
                         ("# discarded lower priority CORE_SEND requests"), 0,
                         GNUNET_NO);

  mst = GNUNET_SERVER_mst_create (&deliver_message, NULL);
  GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_FOREVER_REL, &cleaning_task,
                                NULL);
  /* process client requests */
  GNUNET_SERVER_add_handlers (server, handlers);
  GNUNET_log (GNUNET_ERROR_TYPE_INFO, _("Core service of `%4s' ready.\n"),
              GNUNET_i2s (&my_identity));
}



/**
 * 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)
{
  return (GNUNET_OK ==
          GNUNET_SERVICE_run (argc, argv, "core", GNUNET_SERVICE_OPTION_NONE,
                              &run, NULL)) ? 0 : 1;
}

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