path: root/src/core/core_api.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/core_api.c
 * @brief core service; this is the main API for encrypted P2P
 *        communications
 * @author Christian Grothoff
 */
#include "platform.h"
#include "gnunet_constants.h"
#include "gnunet_core_service.h"
#include "core.h"

#define LOG(kind,...) GNUNET_log_from (kind, "core-api",__VA_ARGS__)


/**
 * Handle for a transmission request.
 */
struct GNUNET_CORE_TransmitHandle
{

  /**
   * Corresponding peer record.
   */
  struct PeerRecord *peer;

  /**
   * Corresponding SEND_REQUEST message.  Only non-NULL
   * while SEND_REQUEST message is pending.
   */
  struct ControlMessage *cm;

  /**
   * Function that will be called to get the actual request
   * (once we are ready to transmit this request to the core).
   * The function will be called with a NULL buffer to signal
   * timeout.
   */
  GNUNET_CONNECTION_TransmitReadyNotify get_message;

  /**
   * Closure for get_message.
   */
  void *get_message_cls;

  /**
   * Timeout for this handle.
   */
  struct GNUNET_TIME_Absolute timeout;

  /**
   * How important is this message?
   */
  uint32_t priority;

  /**
   * Size of this request.
   */
  uint16_t msize;

  /**
   * Send message request ID for this request.
   */
  uint16_t smr_id;

  /**
   * Is corking allowed?
   */
  int cork;

};


/**
 * Information we track for each peer.
 */
struct PeerRecord
{

  /**
   * We generally do NOT keep peer records in a DLL; this
   * DLL is only used IF this peer's 'pending_head' message
   * is ready for transmission.
   */
  struct PeerRecord *prev;

  /**
   * We generally do NOT keep peer records in a DLL; this
   * DLL is only used IF this peer's 'pending_head' message
   * is ready for transmission.
   */
  struct PeerRecord *next;

  /**
   * Peer the record is about.
   */
  struct GNUNET_PeerIdentity peer;

  /**
   * Corresponding core handle.
   */
  struct GNUNET_CORE_Handle *ch;

  /**
   * Pending request, if any.  'th->peer' is set to NULL if the
   * request is not active.
   */
  struct GNUNET_CORE_TransmitHandle th;

  /**
   * ID of timeout task for the 'pending_head' handle
   * which is the one with the smallest timeout.
   */
  GNUNET_SCHEDULER_TaskIdentifier timeout_task;

  /**
   * ID of task to run 'next_request_transmission'.
   */
  GNUNET_SCHEDULER_TaskIdentifier ntr_task;

  /**
   * SendMessageRequest ID generator for this peer.
   */
  uint16_t smr_id_gen;

};


/**
 * Type of function called upon completion.
 *
 * @param cls closure
 * @param success GNUNET_OK on success (which for request_connect
 *        ONLY means that we transmitted the connect request to CORE,
 *        it does not mean that we are actually now connected!);
 *        GNUNET_NO on timeout,
 *        GNUNET_SYSERR if core was shut down
 */
typedef void (*GNUNET_CORE_ControlContinuation) (void *cls, int success);


/**
 * Entry in a doubly-linked list of control messages to be transmitted
 * to the core service.  Control messages include traffic allocation,
 * connection requests and of course our initial 'init' request.
 *
 * The actual message is allocated at the end of this struct.
 */
struct ControlMessage
{
  /**
   * This is a doubly-linked list.
   */
  struct ControlMessage *next;

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

  /**
   * Function to run after transmission failed/succeeded.
   */
  GNUNET_CORE_ControlContinuation cont;

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

  /**
   * Transmit handle (if one is associated with this ControlMessage), or NULL.
   */
  struct GNUNET_CORE_TransmitHandle *th;
};



/**
 * Context for the core service connection.
 */
struct GNUNET_CORE_Handle
{

  /**
   * Configuration we're using.
   */
  const struct GNUNET_CONFIGURATION_Handle *cfg;

  /**
   * Closure for the various callbacks.
   */
  void *cls;

  /**
   * Function to call once we've handshaked with the core service.
   */
  GNUNET_CORE_StartupCallback init;

  /**
   * Function to call whenever we're notified about a peer connecting.
   */
  GNUNET_CORE_ConnectEventHandler connects;

  /**
   * Function to call whenever we're notified about a peer disconnecting.
   */
  GNUNET_CORE_DisconnectEventHandler disconnects;

  /**
   * Function to call whenever we receive an inbound message.
   */
  GNUNET_CORE_MessageCallback inbound_notify;

  /**
   * Function to call whenever we receive an outbound message.
   */
  GNUNET_CORE_MessageCallback outbound_notify;

  /**
   * Function handlers for messages of particular type.
   */
  const struct GNUNET_CORE_MessageHandler *handlers;

  /**
   * Our connection to the service.
   */
  struct GNUNET_CLIENT_Connection *client;

  /**
   * Handle for our current transmission request.
   */
  struct GNUNET_CLIENT_TransmitHandle *cth;

  /**
   * Head of doubly-linked list of pending requests.
   */
  struct ControlMessage *control_pending_head;

  /**
   * Tail of doubly-linked list of pending requests.
   */
  struct ControlMessage *control_pending_tail;

  /**
   * Head of doubly-linked list of peers that are core-approved
   * to send their next message.
   */
  struct PeerRecord *ready_peer_head;

  /**
   * Tail of doubly-linked list of peers that are core-approved
   * to send their next message.
   */
  struct PeerRecord *ready_peer_tail;

  /**
   * Hash map listing all of the peers that we are currently
   * connected to.
   */
  struct GNUNET_CONTAINER_MultiHashMap *peers;

  /**
   * Identity of this peer.
   */
  struct GNUNET_PeerIdentity me;

  /**
   * ID of reconnect task (if any).
   */
  GNUNET_SCHEDULER_TaskIdentifier reconnect_task;

  /**
   * Current delay we use for re-trying to connect to core.
   */
  struct GNUNET_TIME_Relative retry_backoff;

  /**
   * Number of entries in the handlers array.
   */
  unsigned int hcnt;

  /**
   * For inbound notifications without a specific handler, do
   * we expect to only receive headers?
   */
  int inbound_hdr_only;

  /**
   * For outbound notifications without a specific handler, do
   * we expect to only receive headers?
   */
  int outbound_hdr_only;

  /**
   * Are we currently disconnected and hence unable to forward
   * requests?
   */
  int currently_down;

};


/**
 * Our current client connection went down.  Clean it up
 * and try to reconnect!
 *
 * @param h our handle to the core service
 */
static void
reconnect (struct GNUNET_CORE_Handle *h);


/**
 * Task schedule to try to re-connect to core.
 *
 * @param cls the 'struct GNUNET_CORE_Handle'
 * @param tc task context
 */
static void
reconnect_task (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct GNUNET_CORE_Handle *h = cls;

  h->reconnect_task = GNUNET_SCHEDULER_NO_TASK;
  LOG (GNUNET_ERROR_TYPE_DEBUG, "Connecting to CORE service after delay\n");
  reconnect (h);
}


/**
 * Notify clients about disconnect and free
 * the entry for connected peer.
 *
 * @param cls the 'struct GNUNET_CORE_Handle*'
 * @param key the peer identity (not used)
 * @param value the 'struct PeerRecord' to free.
 * @return GNUNET_YES (continue)
 */
static int
disconnect_and_free_peer_entry (void *cls, const struct GNUNET_HashCode * key,
                                void *value)
{
  struct GNUNET_CORE_Handle *h = cls;
  struct GNUNET_CORE_TransmitHandle *th;
  struct PeerRecord *pr = value;

  if (GNUNET_SCHEDULER_NO_TASK != pr->timeout_task)
  {
    GNUNET_SCHEDULER_cancel (pr->timeout_task);
    pr->timeout_task = GNUNET_SCHEDULER_NO_TASK;
  }
  if (GNUNET_SCHEDULER_NO_TASK != pr->ntr_task)
  {
    GNUNET_SCHEDULER_cancel (pr->ntr_task);
    pr->ntr_task = GNUNET_SCHEDULER_NO_TASK;
  }
  if ((NULL != pr->prev) || (NULL != pr->next) || (h->ready_peer_head == pr))
    GNUNET_CONTAINER_DLL_remove (h->ready_peer_head, h->ready_peer_tail, pr);
  if (NULL != h->disconnects)
    h->disconnects (h->cls, &pr->peer);
  /* all requests should have been cancelled, clean up anyway, just in case */
  th = &pr->th;
  if (NULL != th->peer)
  {
    GNUNET_break (0);
    th->peer = NULL;
    if (NULL != th->cm)
      th->cm->th = NULL;
  }
  /* done with 'voluntary' cleanups, now on to normal freeing */
  GNUNET_assert (GNUNET_YES ==
                 GNUNET_CONTAINER_multihashmap_remove (h->peers, key, pr));
  GNUNET_assert (pr->ch == h);
  GNUNET_assert (GNUNET_SCHEDULER_NO_TASK == pr->timeout_task);
  GNUNET_assert (GNUNET_SCHEDULER_NO_TASK == pr->ntr_task);
  GNUNET_free (pr);
  return GNUNET_YES;
}


/**
 * Close down any existing connection to the CORE service and
 * try re-establishing it later.
 *
 * @param h our handle
 */
static void
reconnect_later (struct GNUNET_CORE_Handle *h)
{
  struct ControlMessage *cm;
  struct PeerRecord *pr;

  GNUNET_assert (GNUNET_SCHEDULER_NO_TASK == h->reconnect_task);
  if (NULL != h->cth)
  {
    GNUNET_CLIENT_notify_transmit_ready_cancel (h->cth);
    h->cth = NULL;
  }
  if (NULL != h->client)
  {
    GNUNET_CLIENT_disconnect (h->client);
    h->client = NULL;
  }
  h->currently_down = GNUNET_YES;
  GNUNET_assert (h->reconnect_task == GNUNET_SCHEDULER_NO_TASK);
  h->reconnect_task =
      GNUNET_SCHEDULER_add_delayed (h->retry_backoff, &reconnect_task, h);
  while (NULL != (cm = h->control_pending_head))
  {
    GNUNET_CONTAINER_DLL_remove (h->control_pending_head,
                                 h->control_pending_tail, cm);
    if (NULL != cm->th)
      cm->th->cm = NULL;
    if (NULL != cm->cont)
      cm->cont (cm->cont_cls, GNUNET_NO);
    GNUNET_free (cm);
  }
  GNUNET_CONTAINER_multihashmap_iterate (h->peers,
                                         &disconnect_and_free_peer_entry, h);
  while (NULL != (pr = h->ready_peer_head))
    GNUNET_CONTAINER_DLL_remove (h->ready_peer_head, h->ready_peer_tail, pr);
  GNUNET_assert (h->control_pending_head == NULL);
  h->retry_backoff = GNUNET_TIME_STD_BACKOFF (h->retry_backoff);
}


/**
 * Check the list of pending requests, send the next
 * one to the core.
 *
 * @param h core handle
 * @param ignore_currently_down transmit message even if not initialized?
 */
static void
trigger_next_request (struct GNUNET_CORE_Handle *h, int ignore_currently_down);


/**
 * The given request hit its timeout.  Remove from the
 * doubly-linked list and call the respective continuation.
 *
 * @param cls the transmit handle of the request that timed out
 * @param tc context, can be NULL (!)
 */
static void
transmission_timeout (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc);


/**
 * Send a control message to the peer asking for transmission
 * of the message in the given peer record.
 *
 * @param pr peer to request transmission to
 */
static void
request_next_transmission (struct PeerRecord *pr)
{
  struct GNUNET_CORE_Handle *h = pr->ch;
  struct ControlMessage *cm;
  struct SendMessageRequest *smr;
  struct GNUNET_CORE_TransmitHandle *th;

  if (pr->timeout_task != GNUNET_SCHEDULER_NO_TASK)
  {
    GNUNET_SCHEDULER_cancel (pr->timeout_task);
    pr->timeout_task = GNUNET_SCHEDULER_NO_TASK;
  }
  th = &pr->th;
  if (NULL == th->peer)
  {
    trigger_next_request (h, GNUNET_NO);
    return;
  }
  if (th->cm != NULL)
    return;                     /* already done */
  GNUNET_assert (pr->prev == NULL);
  GNUNET_assert (pr->next == NULL);
  pr->timeout_task =
      GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_absolute_get_remaining
                                    (th->timeout), &transmission_timeout, pr);
  cm = GNUNET_malloc (sizeof (struct ControlMessage) +
                      sizeof (struct SendMessageRequest));
  th->cm = cm;
  cm->th = th;
  smr = (struct SendMessageRequest *) &cm[1];
  smr->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_SEND_REQUEST);
  smr->header.size = htons (sizeof (struct SendMessageRequest));
  smr->priority = htonl (th->priority);
  smr->deadline = GNUNET_TIME_absolute_hton (th->timeout);
  smr->peer = pr->peer;
  smr->reserved = htonl (0);
  smr->size = htons (th->msize);
  smr->smr_id = htons (th->smr_id = pr->smr_id_gen++);
  GNUNET_CONTAINER_DLL_insert_tail (h->control_pending_head,
                                    h->control_pending_tail, cm);
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Adding SEND REQUEST for peer `%s' to message queue\n",
       GNUNET_i2s (&pr->peer));
  trigger_next_request (h, GNUNET_NO);
}


/**
 * The given request hit its timeout.  Remove from the
 * doubly-linked list and call the respective continuation.
 *
 * @param cls the transmit handle of the request that timed out
 * @param tc context, can be NULL (!)
 */
static void
transmission_timeout (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct PeerRecord *pr = cls;
  struct GNUNET_CORE_Handle *h = pr->ch;
  struct GNUNET_CORE_TransmitHandle *th;

  pr->timeout_task = GNUNET_SCHEDULER_NO_TASK;
  if (GNUNET_SCHEDULER_NO_TASK != pr->ntr_task)
  {
    GNUNET_SCHEDULER_cancel (pr->ntr_task);
    pr->ntr_task = GNUNET_SCHEDULER_NO_TASK;
  }
  th = &pr->th;
  th->peer = NULL;
  if ((NULL != pr->prev) || (NULL != pr->next) || (pr == h->ready_peer_head))
  {
    /* the request that was 'approved' by core was
     * canceled before it could be transmitted; remove
     * us from the 'ready' list */
    GNUNET_CONTAINER_DLL_remove (h->ready_peer_head, h->ready_peer_tail, pr);
  }
  if (NULL != th->cm)
  {
     /* we're currently in the control queue, remove */
    GNUNET_CONTAINER_DLL_remove (h->control_pending_head,
                                 h->control_pending_tail, th->cm);
    GNUNET_free (th->cm);
  }
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Signalling timeout of request for transmission to peer `%s' via CORE\n",
       GNUNET_i2s (&pr->peer));
  trigger_next_request (h, GNUNET_NO);

  GNUNET_assert (0 == th->get_message (th->get_message_cls, 0, NULL));
}


/**
 * Transmit the next message to the core service.
 *
 * @param cls closure with the 'struct GNUNET_CORE_Handle'
 * @param size number of bytes available in buf
 * @param buf where the callee should write the message
 * @return number of bytes written to buf 
 */
static size_t
transmit_message (void *cls, size_t size, void *buf)
{
  struct GNUNET_CORE_Handle *h = cls;
  struct ControlMessage *cm;
  struct GNUNET_CORE_TransmitHandle *th;
  struct PeerRecord *pr;
  struct SendMessage *sm;
  const struct GNUNET_MessageHeader *hdr;
  uint16_t msize;
  size_t ret;

  GNUNET_assert (h->reconnect_task == GNUNET_SCHEDULER_NO_TASK);
  h->cth = NULL;
  if (NULL == buf)
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Transmission failed, initiating reconnect\n");
    reconnect_later (h);
    return 0;
  }
  /* first check for control messages */
  if (NULL != (cm = h->control_pending_head))
  {
    hdr = (const struct GNUNET_MessageHeader *) &cm[1];
    msize = ntohs (hdr->size);
    if (size < msize)
    {
      trigger_next_request (h, GNUNET_NO);
      return 0;
    }
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Transmitting control message with %u bytes of type %u to core.\n",
         (unsigned int) msize, (unsigned int) ntohs (hdr->type));
    memcpy (buf, hdr, msize);
    GNUNET_CONTAINER_DLL_remove (h->control_pending_head,
                                 h->control_pending_tail, cm);
    if (NULL != cm->th)
      cm->th->cm = NULL;
    if (NULL != cm->cont)
      cm->cont (cm->cont_cls, GNUNET_OK);
    GNUNET_free (cm);
    trigger_next_request (h, GNUNET_NO);
    return msize;
  }
  /* now check for 'ready' P2P messages */
  if (NULL == (pr = h->ready_peer_head))
    return 0;
  GNUNET_assert (NULL != pr->th.peer);
  th = &pr->th;
  if (size < th->msize + sizeof (struct SendMessage))
  {
    trigger_next_request (h, GNUNET_NO);
    return 0;
  }
  GNUNET_CONTAINER_DLL_remove (h->ready_peer_head, h->ready_peer_tail, pr);
  th->peer = NULL;
  if (GNUNET_SCHEDULER_NO_TASK != pr->timeout_task)
  {
    GNUNET_SCHEDULER_cancel (pr->timeout_task);
    pr->timeout_task = GNUNET_SCHEDULER_NO_TASK;
  }
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Transmitting SEND request to `%s' with %u bytes.\n",
       GNUNET_i2s (&pr->peer), (unsigned int) th->msize);
  sm = (struct SendMessage *) buf;
  sm->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_SEND);
  sm->priority = htonl (th->priority);
  sm->deadline = GNUNET_TIME_absolute_hton (th->timeout);
  sm->peer = pr->peer;
  sm->cork = htonl ((uint32_t) th->cork);
  sm->reserved = htonl (0);
  ret =
    th->get_message (th->get_message_cls,
		     size - sizeof (struct SendMessage), &sm[1]);
  
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Transmitting SEND request to `%s' yielded %u bytes.\n",
       GNUNET_i2s (&pr->peer), ret);
  if (0 == ret)
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
	 "Size of clients message to peer %s is 0!\n",
	 GNUNET_i2s (&pr->peer));
    /* client decided to send nothing! */
    request_next_transmission (pr);
    return 0;
  }
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Produced SEND message to core with %u bytes payload\n",
       (unsigned int) ret);
  GNUNET_assert (ret >= sizeof (struct GNUNET_MessageHeader));
  if (ret + sizeof (struct SendMessage) >= GNUNET_SERVER_MAX_MESSAGE_SIZE)
  {
    GNUNET_break (0);
    request_next_transmission (pr);
    return 0;
  }
  ret += sizeof (struct SendMessage);
  sm->header.size = htons (ret);
  GNUNET_assert (ret <= size);
  request_next_transmission (pr);
  return ret;
}


/**
 * Check the list of pending requests, send the next
 * one to the core.
 *
 * @param h core handle
 * @param ignore_currently_down transmit message even if not initialized?
 */
static void
trigger_next_request (struct GNUNET_CORE_Handle *h, int ignore_currently_down)
{
  uint16_t msize;

  if ((GNUNET_YES == h->currently_down) && (ignore_currently_down == GNUNET_NO))
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Core connection down, not processing queue\n");
    return;
  }
  if (NULL != h->cth)
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG, "Request pending, not processing queue\n");
    return;
  }
  if (NULL != h->control_pending_head)
    msize =
        ntohs (((struct GNUNET_MessageHeader *) &h->
                control_pending_head[1])->size);
  else if (h->ready_peer_head != NULL)
    msize =
      h->ready_peer_head->th.msize + sizeof (struct SendMessage);
  else
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Request queue empty, not processing queue\n");
    return;                     /* no pending message */
  }
  h->cth =
      GNUNET_CLIENT_notify_transmit_ready (h->client, msize,
                                           GNUNET_TIME_UNIT_FOREVER_REL,
                                           GNUNET_NO, &transmit_message, h);
}


/**
 * Handler for notification messages received from the core.
 *
 * @param cls our "struct GNUNET_CORE_Handle"
 * @param msg the message received from the core service
 */
static void
main_notify_handler (void *cls, const struct GNUNET_MessageHeader *msg)
{
  struct GNUNET_CORE_Handle *h = cls;
  const struct InitReplyMessage *m;
  const struct ConnectNotifyMessage *cnm;
  const struct DisconnectNotifyMessage *dnm;
  const struct NotifyTrafficMessage *ntm;
  const struct GNUNET_MessageHeader *em;
  const struct SendMessageReady *smr;
  const struct GNUNET_CORE_MessageHandler *mh;
  const struct GNUNET_ATS_Information *ats;
  GNUNET_CORE_StartupCallback init;
  struct PeerRecord *pr;
  struct GNUNET_CORE_TransmitHandle *th;
  unsigned int hpos;
  int trigger;
  uint16_t msize;
  uint16_t et;
  uint32_t ats_count;

  if (NULL == msg)
  {
    LOG (GNUNET_ERROR_TYPE_INFO,
         _("Client was disconnected from core service, trying to reconnect.\n"));
    reconnect_later (h);
    return;
  }
  msize = ntohs (msg->size);
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Processing message of type %u and size %u from core service\n",
       ntohs (msg->type), msize);
  switch (ntohs (msg->type))
  {
  case GNUNET_MESSAGE_TYPE_CORE_INIT_REPLY:
    if (ntohs (msg->size) != sizeof (struct InitReplyMessage))
    {
      GNUNET_break (0);
      reconnect_later (h);
      return;
    }
    m = (const struct InitReplyMessage *) msg;
    GNUNET_break (0 == ntohl (m->reserved));
    /* start our message processing loop */
    if (GNUNET_YES == h->currently_down)
    {
      h->currently_down = GNUNET_NO;
      trigger_next_request (h, GNUNET_NO);
    }
    h->retry_backoff = GNUNET_TIME_UNIT_MILLISECONDS;
    h->me = m->my_identity;
    if (NULL != (init = h->init))
    {
      /* mark so we don't call init on reconnect */
      h->init = NULL;
      LOG (GNUNET_ERROR_TYPE_DEBUG, "Connected to core service of peer `%s'.\n",
           GNUNET_i2s (&h->me));
      init (h->cls, h, &h->me);
    }
    else
    {
      LOG (GNUNET_ERROR_TYPE_DEBUG,
           "Successfully reconnected to core service.\n");
    }
    /* fake 'connect to self' */
    pr = GNUNET_CONTAINER_multihashmap_get (h->peers, &h->me.hashPubKey);
    GNUNET_assert (NULL == pr);
    pr = GNUNET_malloc (sizeof (struct PeerRecord));
    pr->peer = h->me;
    pr->ch = h;
    GNUNET_assert (GNUNET_YES ==
                   GNUNET_CONTAINER_multihashmap_put (h->peers,
                                                      &h->me.hashPubKey, pr,
                                                      GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST));
    if (NULL != h->connects)
      h->connects (h->cls, &h->me, NULL, 0);
    break;
  case GNUNET_MESSAGE_TYPE_CORE_NOTIFY_CONNECT:
    if (msize < sizeof (struct ConnectNotifyMessage))
    {
      GNUNET_break (0);
      reconnect_later (h);
      return;
    }
    cnm = (const struct ConnectNotifyMessage *) msg;
    ats_count = ntohl (cnm->ats_count);
    if (msize !=
        sizeof (struct ConnectNotifyMessage) +
        ats_count * sizeof (struct GNUNET_ATS_Information))
    {
      GNUNET_break (0);
      reconnect_later (h);
      return;
    }
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Received notification about connection from `%s'.\n",
         GNUNET_i2s (&cnm->peer));
    if (0 == memcmp (&h->me, &cnm->peer, sizeof (struct GNUNET_PeerIdentity)))
    {
      /* connect to self!? */
      GNUNET_break (0);
      return;
    }
    pr = GNUNET_CONTAINER_multihashmap_get (h->peers, &cnm->peer.hashPubKey);
    if (NULL != pr)
    {
      GNUNET_break (0);
      reconnect_later (h);
      return;
    }
    pr = GNUNET_malloc (sizeof (struct PeerRecord));
    pr->peer = cnm->peer;
    pr->ch = h;
    GNUNET_assert (GNUNET_YES ==
                   GNUNET_CONTAINER_multihashmap_put (h->peers,
                                                      &cnm->peer.hashPubKey, pr,
                                                      GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST));
    ats = (const struct GNUNET_ATS_Information *) &cnm[1];
    if (NULL != h->connects)
      h->connects (h->cls, &cnm->peer, ats, ats_count);
    break;
  case GNUNET_MESSAGE_TYPE_CORE_NOTIFY_DISCONNECT:
    if (msize != sizeof (struct DisconnectNotifyMessage))
    {
      GNUNET_break (0);
      reconnect_later (h);
      return;
    }
    dnm = (const struct DisconnectNotifyMessage *) msg;
    if (0 == memcmp (&h->me, &dnm->peer, sizeof (struct GNUNET_PeerIdentity)))
    {
      /* connection to self!? */
      GNUNET_break (0);
      return;
    }
    GNUNET_break (0 == ntohl (dnm->reserved));
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Received notification about disconnect from `%s'.\n",
         GNUNET_i2s (&dnm->peer));
    pr = GNUNET_CONTAINER_multihashmap_get (h->peers, &dnm->peer.hashPubKey);
    if (NULL == pr)
    {
      GNUNET_break (0);
      reconnect_later (h);
      return;
    }
    trigger = ((pr->prev != NULL) || (pr->next != NULL) ||
               (h->ready_peer_head == pr));
    disconnect_and_free_peer_entry (h, &dnm->peer.hashPubKey, pr);
    if (trigger)
      trigger_next_request (h, GNUNET_NO);
    break;
  case GNUNET_MESSAGE_TYPE_CORE_NOTIFY_INBOUND:
    if (msize < sizeof (struct NotifyTrafficMessage))
    {
      GNUNET_break (0);
      reconnect_later (h);
      return;
    }
    ntm = (const struct NotifyTrafficMessage *) msg;
    ats_count = ntohl (ntm->ats_count);
    if ((msize <
         sizeof (struct NotifyTrafficMessage) +
         ats_count * sizeof (struct GNUNET_ATS_Information) +
         sizeof (struct GNUNET_MessageHeader)) )
    {
      GNUNET_break (0);
      reconnect_later (h);
      return;
    }
    ats = (const struct GNUNET_ATS_Information*) &ntm[1];
    em = (const struct GNUNET_MessageHeader *) &ats[ats_count];
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Received message of type %u and size %u from peer `%4s'\n",
         ntohs (em->type), ntohs (em->size), GNUNET_i2s (&ntm->peer));
    if ((GNUNET_NO == h->inbound_hdr_only) &&
        (msize !=
         ntohs (em->size) + sizeof (struct NotifyTrafficMessage) +
         +ats_count * sizeof (struct GNUNET_ATS_Information)))
    {
      GNUNET_break (0);
      reconnect_later (h);
      return;
    }
    et = ntohs (em->type);
    for (hpos = 0; hpos < h->hcnt; hpos++)
    {
      mh = &h->handlers[hpos];
      if (mh->type != et)
        continue;
      if ((mh->expected_size != ntohs (em->size)) && (mh->expected_size != 0))
      {
        LOG (GNUNET_ERROR_TYPE_ERROR,
	     "Unexpected message size %u for message of type %u from peer `%4s'\n",
	     htons (em->size), mh->type, GNUNET_i2s (&ntm->peer));
        GNUNET_break_op (0);
        continue;
      }
      pr = GNUNET_CONTAINER_multihashmap_get (h->peers, &ntm->peer.hashPubKey);
      if (NULL == pr)
      {
	GNUNET_break (0);
	reconnect_later (h);
	return;
      }
      if (GNUNET_OK !=
          h->handlers[hpos].callback (h->cls, &ntm->peer, em, ats,
                                      ats_count))
      {
        /* error in processing, do not process other messages! */
        break;
      }
    }
    if (NULL != h->inbound_notify)
      h->inbound_notify (h->cls, &ntm->peer, em, ats, ats_count);
    break;
  case GNUNET_MESSAGE_TYPE_CORE_NOTIFY_OUTBOUND:
    if (msize < sizeof (struct NotifyTrafficMessage))
    {
      GNUNET_break (0);
      reconnect_later (h);
      return;
    }
    ntm = (const struct NotifyTrafficMessage *) msg;
    ats_count = ntohl (ntm->ats_count);
    if ((msize <
         sizeof (struct NotifyTrafficMessage) +
         ats_count * sizeof (struct GNUNET_ATS_Information) +
         sizeof (struct GNUNET_MessageHeader)) )
    {
      GNUNET_break (0);
      reconnect_later (h);
      return;
    }
    ats = (const struct GNUNET_ATS_Information*) &ntm[1];    
    em = (const struct GNUNET_MessageHeader *) &ats[ats_count];
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Received notification about transmission to `%s'.\n",
         GNUNET_i2s (&ntm->peer));
    if ((GNUNET_NO == h->outbound_hdr_only) &&
        (msize !=
         ntohs (em->size) + sizeof (struct NotifyTrafficMessage) +
         ats_count * sizeof (struct GNUNET_ATS_Information)))
    {
      GNUNET_break (0);
      reconnect_later (h);
      return;
    }
    if (NULL == h->outbound_notify)
    {
      GNUNET_break (0);
      break;
    }
    h->outbound_notify (h->cls, &ntm->peer, em, ats, ats_count);
    break;
  case GNUNET_MESSAGE_TYPE_CORE_SEND_READY:
    if (msize != sizeof (struct SendMessageReady))
    {
      GNUNET_break (0);
      reconnect_later (h);
      return;
    }
    smr = (const struct SendMessageReady *) msg;
    pr = GNUNET_CONTAINER_multihashmap_get (h->peers, &smr->peer.hashPubKey);
    if (NULL == pr)
    {
      GNUNET_break (0);
      reconnect_later (h);
      return;
    }
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Received notification about transmission readiness to `%s'.\n",
         GNUNET_i2s (&smr->peer));
    if (NULL == pr->th.peer)
    {
      /* request must have been cancelled between the original request
       * and the response from core, ignore core's readiness */
      break;
    }

    th = &pr->th;
    if (ntohs (smr->smr_id) != th->smr_id)
    {
      /* READY message is for expired or cancelled message,
       * ignore! (we should have already sent another request) */
      break;
    }
    if ((NULL != pr->prev) || (NULL != pr->next) || (h->ready_peer_head == pr))
    {
      /* we should not already be on the ready list... */
      GNUNET_break (0);
      reconnect_later (h);
      return;
    }
    GNUNET_CONTAINER_DLL_insert (h->ready_peer_head, h->ready_peer_tail, pr);
    trigger_next_request (h, GNUNET_NO);
    break;
  default:
    reconnect_later (h);
    return;
  }
  GNUNET_CLIENT_receive (h->client, &main_notify_handler, h,
                         GNUNET_TIME_UNIT_FOREVER_REL);
}


/**
 * Task executed once we are done transmitting the INIT message.
 * Starts our 'receive' loop.
 *
 * @param cls the 'struct GNUNET_CORE_Handle'
 * @param success were we successful
 */
static void
init_done_task (void *cls, int success)
{
  struct GNUNET_CORE_Handle *h = cls;

  if (GNUNET_SYSERR == success)
    return;                     /* shutdown */
  if (GNUNET_NO == success)
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Failed to exchange INIT with core, retrying\n");
    if (h->reconnect_task == GNUNET_SCHEDULER_NO_TASK)
      reconnect_later (h);
    return;
  }
  GNUNET_CLIENT_receive (h->client, &main_notify_handler, h,
                         GNUNET_TIME_UNIT_FOREVER_REL);
}


/**
 * Our current client connection went down.  Clean it up
 * and try to reconnect!
 *
 * @param h our handle to the core service
 */
static void
reconnect (struct GNUNET_CORE_Handle *h)
{
  struct ControlMessage *cm;
  struct InitMessage *init;
  uint32_t opt;
  uint16_t msize;
  uint16_t *ts;
  unsigned int hpos;

  GNUNET_assert (NULL == h->client);
  GNUNET_assert (h->currently_down == GNUNET_YES);
  h->client = GNUNET_CLIENT_connect ("core", h->cfg);
  if (NULL == h->client)
  {
    reconnect_later (h);
    return;
  }
  msize = h->hcnt * sizeof (uint16_t) + sizeof (struct InitMessage);
  cm = GNUNET_malloc (sizeof (struct ControlMessage) + msize);
  cm->cont = &init_done_task;
  cm->cont_cls = h;
  init = (struct InitMessage *) &cm[1];
  init->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_INIT);
  init->header.size = htons (msize);
  opt = 0;
  if (h->inbound_notify != NULL)
  {
    if (h->inbound_hdr_only)
      opt |= GNUNET_CORE_OPTION_SEND_HDR_INBOUND;
    else
      opt |= GNUNET_CORE_OPTION_SEND_FULL_INBOUND;
  }
  if (h->outbound_notify != NULL)
  {
    if (h->outbound_hdr_only)
      opt |= GNUNET_CORE_OPTION_SEND_HDR_OUTBOUND;
    else
      opt |= GNUNET_CORE_OPTION_SEND_FULL_OUTBOUND;
  }
  LOG (GNUNET_ERROR_TYPE_INFO, 
       "(Re)connecting to CORE service, monitoring messages of type %u\n",
       opt);

  init->options = htonl (opt);
  ts = (uint16_t *) & init[1];
  for (hpos = 0; hpos < h->hcnt; hpos++)
    ts[hpos] = htons (h->handlers[hpos].type);
  GNUNET_CONTAINER_DLL_insert (h->control_pending_head, h->control_pending_tail,
                               cm);
  trigger_next_request (h, GNUNET_YES);
}



/**
 * Connect to the core service.  Note that the connection may
 * complete (or fail) asynchronously.
 *
 * @param cfg configuration to use
 * @param cls closure for the various callbacks that follow (including handlers in the handlers array)
 * @param init callback to call once we have successfully
 *        connected to the core service
 * @param connects function to call on peer connect, can be NULL
 * @param disconnects function to call on peer disconnect / timeout, can be NULL
 * @param inbound_notify function to call for all inbound messages, can be NULL
 * @param inbound_hdr_only set to GNUNET_YES if inbound_notify will only read the
 *                GNUNET_MessageHeader and hence we do not need to give it the full message;
 *                can be used to improve efficiency, ignored if inbound_notify is NULLL
 * @param outbound_notify function to call for all outbound messages, can be NULL
 * @param outbound_hdr_only set to GNUNET_YES if outbound_notify will only read the
 *                GNUNET_MessageHeader and hence we do not need to give it the full message
 *                can be used to improve efficiency, ignored if outbound_notify is NULLL
 * @param handlers callbacks for messages we care about, NULL-terminated
 * @return handle to the core service (only useful for disconnect until 'init' is called);
 *                NULL on error (in this case, init is never called)
 */
struct GNUNET_CORE_Handle *
GNUNET_CORE_connect (const struct GNUNET_CONFIGURATION_Handle *cfg,
                     void *cls,
                     GNUNET_CORE_StartupCallback init,
                     GNUNET_CORE_ConnectEventHandler connects,
                     GNUNET_CORE_DisconnectEventHandler disconnects,
                     GNUNET_CORE_MessageCallback inbound_notify,
                     int inbound_hdr_only,
                     GNUNET_CORE_MessageCallback outbound_notify,
                     int outbound_hdr_only,
                     const struct GNUNET_CORE_MessageHandler *handlers)
{
  struct GNUNET_CORE_Handle *h;

  h = GNUNET_malloc (sizeof (struct GNUNET_CORE_Handle));
  h->cfg = cfg;
  h->cls = cls;
  h->init = init;
  h->connects = connects;
  h->disconnects = disconnects;
  h->inbound_notify = inbound_notify;
  h->outbound_notify = outbound_notify;
  h->inbound_hdr_only = inbound_hdr_only;
  h->outbound_hdr_only = outbound_hdr_only;
  h->handlers = handlers;
  h->hcnt = 0;
  h->currently_down = GNUNET_YES;
  h->peers = GNUNET_CONTAINER_multihashmap_create (128, GNUNET_NO);
  if (NULL != handlers)
    while (handlers[h->hcnt].callback != NULL)
      h->hcnt++;
  GNUNET_assert (h->hcnt <
                 (GNUNET_SERVER_MAX_MESSAGE_SIZE -
                  sizeof (struct InitMessage)) / sizeof (uint16_t));
  LOG (GNUNET_ERROR_TYPE_DEBUG, "Connecting to CORE service\n");
  reconnect (h);
  return h;
}


/**
 * Disconnect from the core service.  This function can only
 * be called *after* all pending 'GNUNET_CORE_notify_transmit_ready'
 * requests have been explicitly canceled.
 *
 * @param handle connection to core to disconnect
 */
void
GNUNET_CORE_disconnect (struct GNUNET_CORE_Handle *handle)
{
  struct ControlMessage *cm;

  LOG (GNUNET_ERROR_TYPE_DEBUG, "Disconnecting from CORE service\n");
  if (NULL != handle->cth)
  {
    GNUNET_CLIENT_notify_transmit_ready_cancel (handle->cth);
    handle->cth = NULL;
  }
  while (NULL != (cm = handle->control_pending_head))
  {
    GNUNET_CONTAINER_DLL_remove (handle->control_pending_head,
                                 handle->control_pending_tail, cm);
    if (NULL != cm->th)
      cm->th->cm = NULL;
    if (NULL != cm->cont)
      cm->cont (cm->cont_cls, GNUNET_SYSERR);
    GNUNET_free (cm);
  }
  if (NULL != handle->client)
  {
    GNUNET_CLIENT_disconnect (handle->client);
    handle->client = NULL;
  }
  GNUNET_CONTAINER_multihashmap_iterate (handle->peers,
                                         &disconnect_and_free_peer_entry,
                                         handle);
  if (handle->reconnect_task != GNUNET_SCHEDULER_NO_TASK)
  {
    GNUNET_SCHEDULER_cancel (handle->reconnect_task);
    handle->reconnect_task = GNUNET_SCHEDULER_NO_TASK;
  }
  GNUNET_CONTAINER_multihashmap_destroy (handle->peers);
  handle->peers = NULL;
  GNUNET_break (handle->ready_peer_head == NULL);
  GNUNET_free (handle);
}


/**
 * Task that calls 'request_next_transmission'.
 *
 * @param cls the 'struct PeerRecord*'
 * @param tc scheduler context
 */
static void
run_request_next_transmission (void *cls,
                               const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct PeerRecord *pr = cls;

  pr->ntr_task = GNUNET_SCHEDULER_NO_TASK;
  request_next_transmission (pr);
}


/**
 * Ask the core to call "notify" once it is ready to transmit the
 * given number of bytes to the specified "target".  Must only be
 * called after a connection to the respective peer has been
 * established (and the client has been informed about this).  You may
 * have one request of this type pending for each connected peer at
 * any time.  If a peer disconnects, the application MUST call
 * "GNUNET_CORE_notify_transmit_ready_cancel" on the respective
 * transmission request, if one such request is pending.
 *
 * @param handle connection to core service
 * @param cork is corking allowed for this transmission?
 * @param priority how important is the message?
 * @param maxdelay how long can the message wait?
 * @param target who should receive the message, never NULL (can be this peer's identity for loopback)
 * @param notify_size how many bytes of buffer space does notify want?
 * @param notify function to call when buffer space is available;
 *        will be called with NULL on timeout; clients MUST cancel
 *        all pending transmission requests DURING the disconnect
 *        handler
 * @param notify_cls closure for notify
 * @return non-NULL if the notify callback was queued,
 *         NULL if we can not even queue the request (request already pending);
 *         if NULL is returned, "notify" will NOT be called.
 */
struct GNUNET_CORE_TransmitHandle *
GNUNET_CORE_notify_transmit_ready (struct GNUNET_CORE_Handle *handle, int cork,
                                   uint32_t priority,
                                   struct GNUNET_TIME_Relative maxdelay,
                                   const struct GNUNET_PeerIdentity *target,
                                   size_t notify_size,
                                   GNUNET_CONNECTION_TransmitReadyNotify notify,
                                   void *notify_cls)
{
  struct PeerRecord *pr;
  struct GNUNET_CORE_TransmitHandle *th;

  if (notify_size > GNUNET_CONSTANTS_MAX_ENCRYPTED_MESSAGE_SIZE)
  {
     GNUNET_break (0);
     return NULL;
  }
  GNUNET_assert (NULL != notify);
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Asking core for transmission of %u bytes to `%s'\n",
       (unsigned int) notify_size,
       GNUNET_i2s (target));
  pr = GNUNET_CONTAINER_multihashmap_get (handle->peers, &target->hashPubKey);
  if (NULL == pr)
  {
    /* attempt to send to peer that is not connected */
    GNUNET_break (0);
    return NULL;
  }
  if (NULL != pr->th.peer)
  {
    /* attempting to queue a second request for the same destination */
    GNUNET_break (0);
    return NULL;
  }
  GNUNET_assert (notify_size + sizeof (struct SendMessage) <
                 GNUNET_SERVER_MAX_MESSAGE_SIZE);
  th = &pr->th;
  memset (th, 0, sizeof (struct GNUNET_CORE_TransmitHandle));
  th->peer = pr;
  th->get_message = notify;
  th->get_message_cls = notify_cls;
  th->timeout = GNUNET_TIME_relative_to_absolute (maxdelay);
  th->priority = priority;
  th->msize = notify_size;
  th->cork = cork;
  GNUNET_assert (GNUNET_SCHEDULER_NO_TASK == pr->ntr_task);
  pr->ntr_task =
    GNUNET_SCHEDULER_add_now (&run_request_next_transmission, pr);
  LOG (GNUNET_ERROR_TYPE_DEBUG, "Transmission request added to queue\n");
  return th;
}


/**
 * Cancel the specified transmission-ready notification.
 *
 * @param th handle that was returned by "notify_transmit_ready".
 */
void
GNUNET_CORE_notify_transmit_ready_cancel (struct GNUNET_CORE_TransmitHandle *th)
{
  struct PeerRecord *pr = th->peer;
  struct GNUNET_CORE_Handle *h;

  GNUNET_assert (NULL != pr);
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Aborting transmission request to core for %u bytes to `%s'\n",
       (unsigned int) th->msize,
       GNUNET_i2s (&pr->peer));
  th->peer = NULL;
  h = pr->ch;
  if (NULL != th->cm)
  {
    /* we're currently in the control queue, remove */
    GNUNET_CONTAINER_DLL_remove (h->control_pending_head,
                                 h->control_pending_tail, th->cm);
    GNUNET_free (th->cm);
    th->cm = NULL;
  }
  if ((NULL != pr->prev) || (NULL != pr->next) || (pr == h->ready_peer_head))
  {
    /* the request that was 'approved' by core was
     * canceled before it could be transmitted; remove
     * us from the 'ready' list */
    GNUNET_CONTAINER_DLL_remove (h->ready_peer_head, h->ready_peer_tail, pr);
  }
  if (GNUNET_SCHEDULER_NO_TASK != pr->ntr_task)
  {
    GNUNET_SCHEDULER_cancel (pr->ntr_task);
    pr->ntr_task = GNUNET_SCHEDULER_NO_TASK;
  }
}


/**
 * Check if the given peer is currently connected. This function is for special
 * cirumstances (GNUNET_TESTBED uses it), normal users of the CORE API are
 * expected to track which peers are connected based on the connect/disconnect
 * callbacks from GNUNET_CORE_connect.  This function is NOT part of the
 * 'versioned', 'official' API. The difference between this function and the
 * function GNUNET_CORE_is_peer_connected() is that this one returns
 * synchronously after looking in the CORE API cache. The function
 * GNUNET_CORE_is_peer_connected() sends a message to the CORE service and hence
 * its response is given asynchronously.
 *
 * @param h the core handle
 * @param pid the identity of the peer to check if it has been connected to us
 * @return GNUNET_YES if the peer is connected to us; GNUNET_NO if not
 */
int
GNUNET_CORE_is_peer_connected_sync (const struct GNUNET_CORE_Handle *h,
                                    const struct GNUNET_PeerIdentity *pid)
{
  GNUNET_assert (NULL != h);
  GNUNET_assert (NULL != pid);
  return GNUNET_CONTAINER_multihashmap_contains (h->peers, &pid->hashPubKey);
}


/* end of core_api.c */