/*
     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 2, 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 dht/dht_api.c
 * @brief library to access the DHT service
 * @author Christian Grothoff
 * @author Nathan Evans
 *
 */

#include "platform.h"
#include "gnunet_bandwidth_lib.h"
#include "gnunet_client_lib.h"
#include "gnunet_constants.h"
#include "gnunet_container_lib.h"
#include "gnunet_arm_service.h"
#include "gnunet_hello_lib.h"
#include "gnunet_protocols.h"
#include "gnunet_server_lib.h"
#include "gnunet_time_lib.h"
#include "gnunet_dht_service.h"
#include "dht.h"

#define DEBUG_DHT_API GNUNET_YES

#define DEFAULT_DHT_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 5)

struct PendingMessage
{
  /**
   * Message that is pending
   */
  struct GNUNET_MessageHeader *msg;

  /**
   * Timeout for this message
   */
  struct GNUNET_TIME_Relative timeout;

  /**
   * Continuation to call on message send
   * or message receipt confirmation
   */
  GNUNET_SCHEDULER_Task cont;

  /**
   * Continuation closure
   */
  void *cont_cls;

  /**
   * Whether or not to await verification the message
   * was received by the service
   */
  size_t is_unique;

  /**
   * Unique ID for this request
   */
  uint64_t unique_id;

};

struct GNUNET_DHT_GetContext
{
  /**
   * Iterator to call on data receipt
   */
  GNUNET_DHT_GetIterator iter;

  /**
   * Closure for the iterator callback
   */
  void *iter_cls;

};

struct GNUNET_DHT_FindPeerContext
{
  /**
   * Iterator to call on data receipt
   */
  GNUNET_DHT_FindPeerProcessor proc;

  /**
   * Closure for the iterator callback
   */
  void *proc_cls;

};

/**
 * Handle to control a unique operation (one that is
 * expected to return results)
 */
struct GNUNET_DHT_RouteHandle
{

  /**
   * Unique identifier for this request (for key collisions)
   */
  uint64_t uid;

  /**
   * Key that this get request is for
   */
  GNUNET_HashCode key;

  /**
   * Iterator to call on data receipt
   */
  GNUNET_DHT_ReplyProcessor iter;

  /**
   * Closure for the iterator callback
   */
  void *iter_cls;

  /**
   * Main handle to this DHT api
   */
  struct GNUNET_DHT_Handle *dht_handle;
};

/**
 * Handle for a non unique request, holds callback
 * which needs to be called before we allow other
 * messages to be processed and sent to the DHT service
 */
struct GNUNET_DHT_NonUniqueHandle
{
  /**
   * Key that this get request is for
   */
  GNUNET_HashCode key;

  /**
   * Type of data get request was for
   */
  uint32_t type;

  /**
   * Continuation to call on service
   * confirmation of message receipt.
   */
  GNUNET_SCHEDULER_Task cont;

  /**
   * Send continuation cls
   */
  void *cont_cls;
};

/**
 * Handle to control a get operation.
 */
struct GNUNET_DHT_GetHandle
{
  /**
   * Handle to the actual route operation for the get
   */
  struct GNUNET_DHT_RouteHandle *route_handle;

  /**
   * The context of the get request
   */
  struct GNUNET_DHT_GetContext get_context;
};

/**
 * Handle to control a find peer operation.
 */
struct GNUNET_DHT_FindPeerHandle
{
  /**
     * Handle to the actual route operation for the request
     */
  struct GNUNET_DHT_RouteHandle *route_handle;

    /**
     * The context of the get request
     */
  struct GNUNET_DHT_FindPeerContext find_peer_context;
};


/**
 * Connection to the DHT service.
 */
struct GNUNET_DHT_Handle
{
  /**
   * Our scheduler.
   */
  struct GNUNET_SCHEDULER_Handle *sched;

  /**
   * Configuration to use.
   */
  const struct GNUNET_CONFIGURATION_Handle *cfg;

  /**
   * Socket (if available).
   */
  struct GNUNET_CLIENT_Connection *client;

  /**
   * Currently pending transmission request.
   */
  struct GNUNET_CLIENT_TransmitHandle *th;

  /**
   * Message we are currently sending, only allow
   * a single message to be queued.  If not unique
   * (typically a put request), await a confirmation
   * from the service that the message was received.
   * If unique, just fire and forget.
   */
  struct PendingMessage *current;

  /**
   * Hash map containing the current outstanding unique requests
   */
  struct GNUNET_CONTAINER_MultiHashMap *outstanding_requests;

  /**
   * Non unique handle.  If set don't schedule another non
   * unique request.
   */
  struct GNUNET_DHT_NonUniqueHandle *non_unique_request;

  /**
   * Kill off the connection and any pending messages.
   */
  int do_destroy;

};

static struct GNUNET_TIME_Relative default_request_timeout;

/* Forward declaration */
static void process_pending_message (struct GNUNET_DHT_Handle *handle);

static GNUNET_HashCode *
hash_from_uid (uint64_t uid)
{
  int count;
  int remaining;
  GNUNET_HashCode *hash;
  hash = GNUNET_malloc (sizeof (GNUNET_HashCode));
  count = 0;

  while (count < sizeof (GNUNET_HashCode))
    {
      remaining = sizeof (GNUNET_HashCode) - count;
      if (remaining > sizeof (uid))
        remaining = sizeof (uid);

      memcpy (hash, &uid, remaining);
      count += remaining;
    }

  return hash;
}

/**
 * Handler for messages received from the DHT service
 * a demultiplexer which handles numerous message types
 *
 */
void
service_message_handler (void *cls, const struct GNUNET_MessageHeader *msg)
{
  struct GNUNET_DHT_Handle *handle = cls;
  struct GNUNET_DHT_Message *dht_msg;
  struct GNUNET_DHT_StopMessage *stop_msg;
  struct GNUNET_MessageHeader *enc_msg;
  struct GNUNET_DHT_RouteHandle *route_handle;
  uint64_t uid;
  GNUNET_HashCode *uid_hash;
  size_t enc_size;
  /* TODO: find out message type, handle callbacks for different types of messages.
   * Should be a non unique acknowledgment, or unique result. */

  if (msg == NULL)
    {
#if DEBUG_DHT_API
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "`%s': Received NULL from server, connection down?\n",
                  "DHT API");
#endif
      return;
    }

  switch (ntohs (msg->type))
    {
    case GNUNET_MESSAGE_TYPE_DHT:
      {
        dht_msg = (struct GNUNET_DHT_Message *) msg;
        uid = GNUNET_ntohll (dht_msg->unique_id);
#if DEBUG_DHT_API
        GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                    "`%s': Received response to message (uid %llu)\n",
                    "DHT API", uid);
#endif
        if (ntohs (dht_msg->unique))
          {
            uid_hash = hash_from_uid (uid);
            route_handle =
              GNUNET_CONTAINER_multihashmap_get (handle->outstanding_requests,
                                                 uid_hash);
            GNUNET_free (uid_hash);
            if (route_handle == NULL)   /* We have no recollection of this request */
              {
#if DEBUG_DHT_API
                GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                            "`%s': Received response to message (uid %llu), but have no recollection of it!\n",
                            "DHT API", uid);
#endif
              }
            else
              {
                enc_size =
                  ntohs (dht_msg->header.size) -
                  sizeof (struct GNUNET_DHT_Message);
                GNUNET_assert (enc_size > 0);
                enc_msg = (struct GNUNET_MessageHeader *) &dht_msg[1];
                route_handle->iter (route_handle->iter_cls, enc_msg);

              }
          }
        break;
      }
    case GNUNET_MESSAGE_TYPE_DHT_STOP:
      {
        stop_msg = (struct GNUNET_DHT_StopMessage *) msg;
        uid = GNUNET_ntohll (stop_msg->unique_id);
#if DEBUG_DHT_API
        GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                    "`%s': Received response to message (uid %llu), current uid %llu\n",
                    "DHT API", uid, handle->current->unique_id);
#endif
        if (handle->current->unique_id == uid)
          {
#if DEBUG_DHT_API
            GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                        "`%s': Have pending confirmation for this message!\n",
                        "DHT API", uid);
#endif
            if (handle->current->cont != NULL)
              GNUNET_SCHEDULER_add_continuation (handle->sched,
                                                 handle->current->cont,
                                                 handle->current->cont_cls,
                                                 GNUNET_SCHEDULER_REASON_PREREQ_DONE);

            GNUNET_free (handle->current->msg);
            GNUNET_free (handle->current);
            handle->current = NULL;
          }
        break;
      }
    default:
      {
        GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                    "`%s': Received unknown message type %d\n", "DHT API",
                    ntohs (msg->type));
      }
    }
  GNUNET_CLIENT_receive (handle->client,
                         &service_message_handler,
                         handle, GNUNET_TIME_UNIT_FOREVER_REL);

}


/**
 * Initialize the connection with the DHT service.
 *
 * @param sched scheduler to use
 * @param cfg configuration to use
 * @param ht_len size of the internal hash table to use for
 *               processing multiple GET/FIND requests in parallel
 *
 * @return handle to the DHT service, or NULL on error
 */
struct GNUNET_DHT_Handle *
GNUNET_DHT_connect (struct GNUNET_SCHEDULER_Handle *sched,
                    const struct GNUNET_CONFIGURATION_Handle *cfg,
                    unsigned int ht_len)
{
  struct GNUNET_DHT_Handle *handle;

  handle = GNUNET_malloc (sizeof (struct GNUNET_DHT_Handle));

  default_request_timeout =
    GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 5);
  handle->cfg = cfg;
  handle->sched = sched;

  handle->current = NULL;
  handle->do_destroy = GNUNET_NO;
  handle->th = NULL;

  handle->client = GNUNET_CLIENT_connect (sched, "dht", cfg);
  handle->outstanding_requests =
    GNUNET_CONTAINER_multihashmap_create (ht_len);

  if (handle->client == NULL)
    {
      GNUNET_free (handle);
      return NULL;
    }
#if DEBUG_DHT_API
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "`%s': Connection to service in progress\n", "DHT API");
#endif
  GNUNET_CLIENT_receive (handle->client,
                         &service_message_handler,
                         handle, GNUNET_TIME_UNIT_FOREVER_REL);

  return handle;
}


/**
 * Shutdown connection with the DHT service.
 *
 * @param handle handle of the DHT connection to stop
 */
void
GNUNET_DHT_disconnect (struct GNUNET_DHT_Handle *handle)
{
#if DEBUG_DHT_API
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "`%s': Called GNUNET_DHT_disconnect\n", "DHT API");
#endif
  GNUNET_assert (handle != NULL);

  if (handle->th != NULL)       /* We have a live transmit request in the Aether */
    {
      GNUNET_CLIENT_notify_transmit_ready_cancel (handle->th);
      handle->th = NULL;
    }
  if (handle->current != NULL)  /* We are trying to send something now, clean it up */
    GNUNET_free (handle->current);

  if (handle->client != NULL)   /* Finally, disconnect from the service */
    {
      GNUNET_CLIENT_disconnect (handle->client, GNUNET_NO);
      handle->client = NULL;
    }

  GNUNET_free (handle);
}


/**
 * Send complete (or failed), schedule next (or don't)
 */
static void
finish (struct GNUNET_DHT_Handle *handle, int code)
{
  /* TODO: if code is not GNUNET_OK, do something! */
  struct PendingMessage *pos = handle->current;
#if DEBUG_DHT_API
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "`%s': Finish called!\n", "DHT API");
#endif
  GNUNET_assert (pos != NULL);

  if (pos->is_unique)
    {
      if (pos->cont != NULL)
        {
          if (code == GNUNET_SYSERR)
            GNUNET_SCHEDULER_add_continuation (handle->sched, pos->cont,
                                               pos->cont_cls,
                                               GNUNET_SCHEDULER_REASON_TIMEOUT);
          else
            GNUNET_SCHEDULER_add_continuation (handle->sched, pos->cont,
                                               pos->cont_cls,
                                               GNUNET_SCHEDULER_REASON_PREREQ_DONE);
        }

      GNUNET_free (pos->msg);
      handle->current = NULL;
      GNUNET_free (pos);
    }
  /* Otherwise we need to wait for a response to this message! */
}

/**
 * Transmit the next pending message, called by notify_transmit_ready
 */
static size_t
transmit_pending (void *cls, size_t size, void *buf)
{
  struct GNUNET_DHT_Handle *handle = cls;
  size_t tsize;

#if DEBUG_DHT_API
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "`%s': In transmit_pending\n", "DHT API");
#endif
  if (buf == NULL)
    {
#if DEBUG_DHT_API
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "`%s': In transmit_pending buf is NULL\n", "DHT API");
#endif
      /* FIXME: free associated resources or summat */
      finish (handle, GNUNET_SYSERR);
      return 0;
    }

  handle->th = NULL;

  if (handle->current != NULL)
    {
      tsize = ntohs (handle->current->msg->size);
      if (size >= tsize)
        {
#if DEBUG_DHT_API
          GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                      "`%s': Sending message size %d\n", "DHT API", tsize);
#endif
          memcpy (buf, handle->current->msg, tsize);
          finish (handle, GNUNET_OK);
          return tsize;
        }
      else
        {
          return 0;
        }
    }
  /* Have no pending request */
  return 0;
}


/**
 * Try to (re)connect to the dht service.
 *
 * @return GNUNET_YES on success, GNUNET_NO on failure.
 */
static int
try_connect (struct GNUNET_DHT_Handle *handle)
{
  if (handle->client != NULL)
    return GNUNET_OK;
  handle->client = GNUNET_CLIENT_connect (handle->sched, "dht", handle->cfg);
  if (handle->client != NULL)
    return GNUNET_YES;
#if DEBUG_STATISTICS
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              _("Failed to connect to the dht service!\n"));
#endif
  return GNUNET_NO;
}


/**
 * Try to send messages from list of messages to send
 */
static void
process_pending_message (struct GNUNET_DHT_Handle *handle)
{

  if (handle->current == NULL)
    return;                     /* action already pending */
  if (GNUNET_YES != try_connect (handle))
    {
      finish (handle, GNUNET_SYSERR);
      return;
    }

  /* TODO: set do_destroy somewhere's, see what needs to happen in that case! */
  if (handle->do_destroy)
    {
      //GNUNET_DHT_disconnect (handle); /* FIXME: replace with proper disconnect stuffs */
    }


  if (NULL ==
      (handle->th = GNUNET_CLIENT_notify_transmit_ready (handle->client,
                                                         ntohs (handle->
                                                                current->msg->
                                                                size),
                                                         handle->current->
                                                         timeout, GNUNET_YES,
                                                         &transmit_pending,
                                                         handle)))
    {
#if DEBUG_DHT_API
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Failed to transmit request to dht service.\n");
#endif
      finish (handle, GNUNET_SYSERR);
    }
#if DEBUG_DHT_API
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "`%s': Scheduled sending message of size %d to service\n",
              "DHT API", ntohs (handle->current->msg->size));
#endif
}

/**
 * Iterator called on each result obtained from a generic route
 * operation
 */
void
get_reply_iterator (void *cls, const struct GNUNET_MessageHeader *reply)
{
  struct GNUNET_DHT_GetHandle *get_handle = cls;
  struct GNUNET_DHT_GetResultMessage *result;
  size_t data_size;
  char *result_data;

  if (ntohs (reply->type) != GNUNET_MESSAGE_TYPE_DHT_GET_RESULT)
    return;

  GNUNET_assert (ntohs (reply->size) >=
                 sizeof (struct GNUNET_DHT_GetResultMessage));
  result = (struct GNUNET_DHT_GetResultMessage *) reply;
  data_size = ntohs (result->data_size);
  GNUNET_assert (ntohs (reply->size) ==
                 sizeof (struct GNUNET_DHT_GetResultMessage) + data_size);
  result_data = (char *) &result[1];    /* Set data pointer to end of message */

  get_handle->get_context.iter (get_handle->get_context.iter_cls,
                                result->expiration, &result->key,
                                ntohs (result->type), data_size, result_data);
}


/**
 * Iterator called on each result obtained from a generic route
 * operation
 */
void
find_peer_reply_iterator (void *cls, const struct GNUNET_MessageHeader *reply)
{
  struct GNUNET_DHT_FindPeerHandle *find_peer_handle = cls;
  struct GNUNET_DHT_FindPeerResultMessage *result;
  size_t data_size;
  struct GNUNET_MessageHeader *result_data;

  if (ntohs (reply->type) != GNUNET_MESSAGE_TYPE_DHT_FIND_PEER_RESULT)
    return;

  GNUNET_assert (ntohs (reply->size) >=
                 sizeof (struct GNUNET_DHT_FindPeerResultMessage));
  result = (struct GNUNET_DHT_FindPeerResultMessage *) reply;
  data_size = ntohs (result->data_size);
  GNUNET_assert (ntohs (reply->size) ==
                 sizeof (struct GNUNET_DHT_GetResultMessage) + data_size);

  if (data_size > 0)
    result_data = (struct GNUNET_MessageHeader *) &result[1];   /* Set data pointer to end of message */
  else
    result_data = NULL;

  find_peer_handle->find_peer_context.proc (find_peer_handle->
                                            find_peer_context.proc_cls,
                                            &result->peer, result_data);
}

/**
 * Perform an asynchronous FIND_PEER operation on the DHT.
 *
 * @param handle handle to the DHT service
 * @param key the key to look up
 * @param desired_replication_level how many peers should ultimately receive
 *                this message (advisory only, target may be too high for the
 *                given DHT or not hit exactly).
 * @param options options for routing
 * @param enc send the encapsulated message to a peer close to the key
 * @param iter function to call on each result, NULL if no replies are expected
 * @param iter_cls closure for iter
 * @param timeout when to abort with an error if we fail to get
 *                a confirmation for the request (when necessary) or how long
 *                to wait for tramission to the service
 * @param cont continuation to call when done;
 *             reason will be TIMEOUT on error,
 *             reason will be PREREQ_DONE on success
 * @param cont_cls closure for cont
 *
 * @return handle to stop the request, NULL if the request is "fire and forget"
 */
struct GNUNET_DHT_RouteHandle *
GNUNET_DHT_route_start (struct GNUNET_DHT_Handle *handle,
                        const GNUNET_HashCode * key,
                        unsigned int desired_replication_level,
                        enum GNUNET_DHT_RouteOption options,
                        const struct GNUNET_MessageHeader *enc,
                        struct GNUNET_TIME_Relative timeout,
                        GNUNET_DHT_ReplyProcessor iter,
                        void *iter_cls,
                        GNUNET_SCHEDULER_Task cont, void *cont_cls)
{
  struct GNUNET_DHT_RouteHandle *route_handle;
  struct PendingMessage *pending;
  struct GNUNET_DHT_Message *message;
  size_t is_unique;
  size_t msize;
  GNUNET_HashCode *uid_key;
  uint64_t uid;

  is_unique = GNUNET_YES;
  if (iter == NULL)
    is_unique = GNUNET_NO;

  route_handle = NULL;
  uid_key = NULL;

  do
    {
      GNUNET_free_non_null (uid_key);
      uid = GNUNET_CRYPTO_random_u64 (GNUNET_CRYPTO_QUALITY_WEAK, -1);
      uid_key = hash_from_uid (uid);
    }
  while (GNUNET_CONTAINER_multihashmap_contains
         (handle->outstanding_requests, uid_key) == GNUNET_YES);

  if (is_unique)
    {
      route_handle = GNUNET_malloc (sizeof (struct GNUNET_DHT_RouteHandle));
      memcpy (&route_handle->key, key, sizeof (GNUNET_HashCode));
      route_handle->iter = iter;
      route_handle->iter_cls = iter_cls;
      route_handle->dht_handle = handle;
      route_handle->uid = uid;
#if DEBUG_DHT_API
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "`%s': Unique ID is %llu\n", "DHT API", uid);
#endif
      /**
       * Store based on random identifier!
       */
      GNUNET_CONTAINER_multihashmap_put (handle->outstanding_requests,
                                         uid_key, route_handle,
                                         GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE);
      msize = sizeof (struct GNUNET_DHT_Message) + ntohs (enc->size);

    }
  else
    {
      msize = sizeof (struct GNUNET_DHT_Message) + ntohs (enc->size);
    }

  GNUNET_free (uid_key);
  message = GNUNET_malloc (msize);
  message->header.size = htons (msize);
  message->header.type = htons (GNUNET_MESSAGE_TYPE_DHT);
  memcpy (&message->key, key, sizeof (GNUNET_HashCode));
  message->options = htons (options);
  message->desired_replication_level = htons (options);
  message->unique = htons (is_unique);
  message->unique_id = GNUNET_htonll (uid);
  memcpy (&message[1], enc, ntohs (enc->size));

  pending = GNUNET_malloc (sizeof (struct PendingMessage));
  pending->msg = &message->header;
  pending->timeout = timeout;
  pending->cont = cont;
  pending->cont_cls = cont_cls;
  pending->is_unique = is_unique;
  pending->unique_id = uid;

  GNUNET_assert (handle->current == NULL);

  handle->current = pending;

  process_pending_message (handle);

  return route_handle;
}

void
GNUNET_DHT_route_stop (struct GNUNET_DHT_RouteHandle *route_handle,
                       GNUNET_SCHEDULER_Task cont, void *cont_cls);

/**
 * Perform an asynchronous GET operation on the DHT identified.
 *
 * @param handle handle to the DHT service
 * @param timeout how long to wait for transmission of this request to the service
 * @param type expected type of the response object
 * @param key the key to look up
 * @param iter function to call on each result
 * @param iter_cls closure for iter
 * @param cont continuation to call once message sent
 * @param cont_cls closure for continuation
 *
 * @return handle to stop the async get
 */
struct GNUNET_DHT_GetHandle *
GNUNET_DHT_get_start (struct GNUNET_DHT_Handle *handle,
                      struct GNUNET_TIME_Relative timeout,
                      uint32_t type,
                      const GNUNET_HashCode * key,
                      GNUNET_DHT_GetIterator iter,
                      void *iter_cls,
                      GNUNET_SCHEDULER_Task cont, void *cont_cls)
{
  struct GNUNET_DHT_GetHandle *get_handle;
  struct GNUNET_DHT_GetMessage *get_msg;

  if (handle->current != NULL)  /* Can't send right now, we have a pending message... */
    return NULL;

  get_handle = GNUNET_malloc (sizeof (struct GNUNET_DHT_GetHandle));
  get_handle->get_context.iter = iter;
  get_handle->get_context.iter_cls = iter_cls;

#if DEBUG_DHT_API
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "`%s': Inserting pending get request with key %s\n", "DHT API",
              GNUNET_h2s (key));
#endif

  get_msg = GNUNET_malloc (sizeof (struct GNUNET_DHT_GetMessage));
  get_msg->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_GET);
  get_msg->header.size = htons (sizeof (struct GNUNET_DHT_GetMessage));
  get_msg->type = htonl (type);

  get_handle->route_handle =
    GNUNET_DHT_route_start (handle, key, 0, 0, &get_msg->header, timeout,
                            &get_reply_iterator, get_handle, cont, cont_cls);
  return get_handle;
}

/**
 * Stop a previously issued routing request
 *
 * @param route_handle handle to the request to stop
 * @param cont continuation to call once this message is sent to the service or times out
 * @param cont_cls closure for the continuation
 *
 */
void
GNUNET_DHT_route_stop (struct GNUNET_DHT_RouteHandle *route_handle,
                       GNUNET_SCHEDULER_Task cont, void *cont_cls)
{
  struct PendingMessage *pending;
  struct GNUNET_DHT_StopMessage *message;
  size_t msize;
  GNUNET_HashCode *uid_key;

  msize = sizeof (struct GNUNET_DHT_StopMessage);

  message = GNUNET_malloc (msize);
  message->header.size = htons (msize);
  message->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_STOP);
#if DEBUG_DHT_API
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "`%s': Remove outstanding request for uid %llu\n", "DHT API",
              route_handle->uid);
#endif
  message->unique_id = GNUNET_htonll (route_handle->uid);

  GNUNET_assert (route_handle->dht_handle->current == NULL);

  pending = GNUNET_malloc (sizeof (struct PendingMessage));
  pending->msg = (struct GNUNET_MessageHeader *) message;
  pending->timeout = DEFAULT_DHT_TIMEOUT;
  pending->cont = cont;
  pending->cont_cls = cont_cls;
  pending->is_unique = GNUNET_NO;
  pending->unique_id = route_handle->uid;

  GNUNET_assert (route_handle->dht_handle->current == NULL);

  route_handle->dht_handle->current = pending;

  process_pending_message (route_handle->dht_handle);

  uid_key = hash_from_uid (route_handle->uid);

  if (GNUNET_CONTAINER_multihashmap_remove
      (route_handle->dht_handle->outstanding_requests, uid_key,
       route_handle) != GNUNET_YES)
    {
#if DEBUG_DHT_API
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "`%s': Remove outstanding request from hashmap failed for key %s, uid %llu\n",
                  "DHT API", GNUNET_h2s (uid_key), route_handle->uid);
#endif
    }
  GNUNET_free (uid_key);
  return;
}


/**
 * Stop async DHT-get.
 *
 * @param get_handle handle to the GET operation to stop
 * @param cont continuation to call once this message is sent to the service or times out
 * @param cont_cls closure for the continuation
 */
void
GNUNET_DHT_get_stop (struct GNUNET_DHT_GetHandle *get_handle,
                     GNUNET_SCHEDULER_Task cont, void *cont_cls)
{
#if DEBUG_DHT_API
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "`%s': Removing pending get request with key %s, uid %llu\n",
              "DHT API", GNUNET_h2s (&get_handle->route_handle->key),
              get_handle->route_handle->uid);
#endif
  GNUNET_DHT_route_stop (get_handle->route_handle, cont, cont_cls);
  GNUNET_free (get_handle);

}


/**
 * Perform an asynchronous FIND PEER operation on the DHT.
 *
 * @param handle handle to the DHT service
 * @param timeout timeout for this request to be sent to the
 *        service
 * @param options routing options for this message
 * @param message a message to inject at found peers (may be null)
 * @param key the key to look up
 * @param proc function to call on each result
 * @param proc_cls closure for proc
 * @param cont continuation to call once message sent
 * @param cont_cls closure for continuation
 *
 * @return handle to stop the async get, NULL on error
 */
struct GNUNET_DHT_FindPeerHandle *
GNUNET_DHT_find_peer_start (struct GNUNET_DHT_Handle *handle,
                            struct GNUNET_TIME_Relative timeout,
                            enum GNUNET_DHT_RouteOption options,
                            struct GNUNET_MessageHeader *message,
                            const GNUNET_HashCode * key,
                            GNUNET_DHT_FindPeerProcessor proc,
                            void *proc_cls,
                            GNUNET_SCHEDULER_Task cont, void *cont_cls)
{
  struct GNUNET_DHT_FindPeerHandle *find_peer_handle;
  struct GNUNET_DHT_FindPeerMessage *find_peer_msg;
  size_t msize;

  if (handle->current != NULL)  /* Can't send right now, we have a pending message... */
    return NULL;

  if (message != NULL)
    msize = ntohs (message->size);
  else
    msize = 0;

  find_peer_handle =
    GNUNET_malloc (sizeof (struct GNUNET_DHT_FindPeerHandle));
  find_peer_handle->find_peer_context.proc = proc;
  find_peer_handle->find_peer_context.proc_cls = proc_cls;

#if DEBUG_DHT_API
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "`%s': Inserting pending `%s' request with key %s\n", "DHT API",
              "FIND PEER", GNUNET_h2s (key));
#endif

  find_peer_msg =
    GNUNET_malloc (sizeof (struct GNUNET_DHT_FindPeerMessage) + msize);
  find_peer_msg->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_FIND_PEER);
  find_peer_msg->header.size =
    htons (sizeof (struct GNUNET_DHT_FindPeerMessage));
  find_peer_msg->msg_len = msize;

  if (message != NULL)
    {
      memcpy (&find_peer_msg[1], message, msize);
    }

  find_peer_handle->route_handle =
    GNUNET_DHT_route_start (handle, key, 0, options, &find_peer_msg->header,
                            timeout, &find_peer_reply_iterator,
                            find_peer_handle, cont, cont_cls);
  return find_peer_handle;
}

/**
 * Stop async find peer.  Frees associated resources.
 *
 * @param find_peer_handle GET operation to stop.
 * @param cont continuation to call once this message is sent to the service or times out
 * @param cont_cls closure for the continuation
 */
void
GNUNET_DHT_find_peer_stop (struct GNUNET_DHT_FindPeerHandle *find_peer_handle,
                           GNUNET_SCHEDULER_Task cont, void *cont_cls)
{
#if DEBUG_DHT_API
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "`%s': Removing pending `%s' request with key %s, uid %llu\n",
              "DHT API", "FIND PEER",
              GNUNET_h2s (&find_peer_handle->route_handle->key),
              find_peer_handle->route_handle->uid);
#endif
  GNUNET_DHT_route_stop (find_peer_handle->route_handle, cont, cont_cls);
  GNUNET_free (find_peer_handle);

}


/**
 * Perform a PUT operation storing data in the DHT.
 *
 * @param h handle to DHT service
 * @param key the key to store under
 * @param type type of the value
 * @param size number of bytes in data; must be less than 64k
 * @param data the data to store
 * @param exp desired expiration time for the value
 * @param cont continuation to call when done;
 *             reason will be TIMEOUT on error,
 *             reason will be PREREQ_DONE on success
 * @param cont_cls closure for cont
 *
 * @return GNUNET_YES if put message is queued for transmission
 */
void
GNUNET_DHT_put (struct GNUNET_DHT_Handle *handle,
                const GNUNET_HashCode * key,
                uint32_t type,
                uint32_t size,
                const char *data,
                struct GNUNET_TIME_Absolute exp,
                struct GNUNET_TIME_Relative timeout,
                GNUNET_SCHEDULER_Task cont, void *cont_cls)
{
  struct GNUNET_DHT_PutMessage *put_msg;
  size_t msize;

  if (handle->current != NULL)
    {
      GNUNET_SCHEDULER_add_continuation (handle->sched, cont, cont_cls,
                                         GNUNET_SCHEDULER_REASON_TIMEOUT);
      return;
    }

#if DEBUG_DHT_API
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "`%s': Inserting pending put request with key %s\n", "DHT API",
              GNUNET_h2s (key));
#endif

  msize = sizeof (struct GNUNET_DHT_PutMessage) + size;
  put_msg = GNUNET_malloc (msize);
  put_msg->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_PUT);
  put_msg->header.size = htons (msize);
  put_msg->type = htonl (type);
  put_msg->data_size = htons (size);
  put_msg->expiration = exp;
  memcpy (&put_msg[1], data, size);

  GNUNET_DHT_route_start (handle, key, 0, 0, &put_msg->header, timeout, NULL,
                          NULL, cont, cont_cls);

  GNUNET_free (put_msg);
}