[oweals/gnunet.git] / src / transport / plugin_transport_wlan.c

/*
 This file is part of GNUnet
 (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 Christian Grothoff (and other contributing authors)

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

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

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

/**
 * @file transport/plugin_transport_wlan.c
 * @brief transport plugin for wlan
 * @author David Brodski
 */

#include "platform.h"
#include "gnunet_hello_lib.h"
#include "gnunet_protocols.h"
#include "gnunet_util_lib.h"
#include "gnunet_statistics_service.h"
#include "gnunet_transport_service.h"
#include "gnunet_transport_plugin.h"
#include "plugin_transport_wlan.h"
#include "gnunet_common.h"
#include "gnunet_crypto_lib.h"

#define PROTOCOL_PREFIX "wlan"

/**
 * Max size of packet from helper
 */
#define WLAN_MTU 3000

/**
 * Time until retransmission of a fragment in ms
 */
#define FRAGMENT_TIMEOUT GNUNET_TIME_UNIT_SECONDS

#define FRAGMENT_QUEUE_SIZE 10
#define FRAGMENT_QUEUE_MESSAGES_OUT_PER_SESSION 1

#define MESSAGE_IN_TIMEOUT GNUNET_TIME_UNIT_SECONDS

#define MESSAGES_IN_QUEUE_SIZE 10
#define MESSAGES_IN_QUEUE_PER_SESSION 1

#define HALLO_BEACON_SCALING_FACTOR 900

#define DEBUG_wlan GNUNET_YES

#define MESSAGE_LENGHT_UNKNOWN -1
//#define NO_MESSAGE_OR_MESSAGE_FINISHED -2

/**
 * After how long do we expire an address that we
 * learned from another peer if it is not reconfirmed
 * by anyone?
 */
#define LEARNED_ADDRESS_EXPIRATION GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_HOURS, 6)

/**
 * Initial handshake message for a session.
 */
struct WelcomeMessage
{
  /**
   * Type is GNUNET_MESSAGE_TYPE_TRANSPORT_TCP_WELCOME.
   */
  struct GNUNET_MessageHeader header;

  /**
   * Identit*mac_y of the node connecting (TCP client)
   */
  struct GNUNET_PeerIdentity clientIdentity;

};

/**
 * Encapsulation of all of the state of the plugin.
 */
struct Plugin
{
  /**
   * Our environment.
   */
  struct GNUNET_TRANSPORT_PluginEnvironment *env;

  /**
   * List of open sessions. head
   */
  struct Sessionqueue *sessions;

  /**
   * List of open sessions. tail
   */
  struct Sessionqueue *sessions_tail;

  /**
   * Number of sessions
   */

  int session_count;

  /**
   * encapsulation of data from the local wlan helper program
   */

  struct GNUNET_SERVER_MessageStreamTokenizer * suid_tokenizer;

  /**
   * encapsulation of packets received
   */

  struct GNUNET_SERVER_MessageStreamTokenizer * data_tokenizer;

  /**
   * stdout pipe handle for the gnunet-wlan-helper process
   */
  struct GNUNET_DISK_PipeHandle *server_stdout;

  /**
   * stdout file handle for the gnunet-wlan-helper process
   */
  const struct GNUNET_DISK_FileHandle *server_stdout_handle;

  /**
   * stdin pipe handle for the gnunet-wlan-helper process
   */
  struct GNUNET_DISK_PipeHandle *server_stdin;

  /**
   * stdin file handle for the gnunet-wlan-helper process
   */
  const struct GNUNET_DISK_FileHandle *server_stdin_handle;

  /**
   * ID of the gnunet-wlan-server std read task
   */
  GNUNET_SCHEDULER_TaskIdentifier server_read_task;

  /**
   * ID of the gnunet-wlan-server std read task
   */
  GNUNET_SCHEDULER_TaskIdentifier server_write_task;

  /**
   * ID of the delay task for writing
   */
  GNUNET_SCHEDULER_TaskIdentifier server_write_delay_task;

  /**
   * The process id of the wlan process
   */
  struct GNUNET_OS_Process *server_proc;

  /**
   * The interface of the wlan card given to us by the user.
   */
  char *interface;

  /**
   * The mac_address of the wlan card given to us by the helper.
   */
  struct MacAddress mac_address;

  /**
   * Sessions currently pending for transmission
   * to this peer, if any.
   */
  struct Sessionqueue * pending_Sessions;

  /**
   * Sessions currently pending for transmission
   * to this peer (tail), if any.
   */
  struct Sessionqueue * pending_Sessions_tail;

  /**
   * number of pending sessions
   */
  unsigned int pendingsessions;

  /**
   * Messages in the fragmentation queue, head
   */

  struct FragmentMessage * pending_Fragment_Messages_head;

  /**
   * Messages in the fragmentation queue, tail
   */

  struct FragmentMessage * pending_Fragment_Messages_tail;

  /**
   * number of pending fragment message
   */

  unsigned int pending_fragment_messages;

  /**
   * Messages in the in Queue, head
   */

  struct Receive_Message_Queue * receive_messages_head;

  /**
   * Messages in the in Queue, tail
   */

  struct Receive_Message_Queue * receive_messages_teil;

  /**
   * number of messages in the in queue
   */

  unsigned int pending_receive_messages;

  /**
   * time of the next "hello-beacon"
   */

  struct GNUNET_TIME_Absolute beacon_time;

  /**
   * queue to send acks for received fragments (head)
   */

  struct AckSendQueue * ack_send_queue_head;

  /**
   * queue to send acks for received fragments (tail)
   */

  struct AckSendQueue * ack_send_queue_tail;

};

/**
 * Struct to store data if file write did not accept the whole packet
 */
struct Finish_send
{
  struct Plugin * plugin;
  char * msgheader;
  struct GNUNET_MessageHeader * msgstart;
  ssize_t size;
};

/**
 * Queue of sessions, for the general session queue and the pending session queue
 */

struct Sessionqueue
{
  struct Sessionqueue * next;
  struct Sessionqueue * prev;
  struct Session * content;
};

/**
 * Queue for the fragments received
 */

struct Receive_Fragment_Queue
{
  struct Receive_Fragment_Queue * next;
  struct Receive_Fragment_Queue * prev;
  uint16_t num;
  const char * msg;
  uint16_t size;
};

/**
 * Queue for the fragments received
 */

struct Receive_Message_Queue
{
  struct Receive_Message_Queue * next;

  struct Receive_Message_Queue * prev;

  /**
   * current number for message incoming, to distinguish between the messages
   */
  uint32_t message_id_in;

  /**
   * size of the message received,
   * MESSAGE_LENGHT_UNKNOWN means that the size is not known,
   * NO_MESSAGE_OR_MESSAGE_FINISHED means no message received
   */

  int rec_size;

  /**
   * Sorted queue with the fragments received; head
   */

  struct Receive_Fragment_Queue * frag_head;

  /**
   * Sorted queue with the fragments received; tail
   */

  struct Receive_Fragment_Queue * frag_tail;

  /**
   * Session this fragment belongs to
   */

  struct Session * session;

  /**
   * Timeout value for the pending message.
   */
  struct GNUNET_TIME_Absolute timeout;

  /**
   * Bitfield of received fragments
   */

  uint64_t received_fragments;
};

/**
 * Information kept for each message that is yet to
 * be transmitted.
 */
struct PendingMessage
{

  /**
   * The pending message
   */
  char *msg;

  /**
   * Size of the message
   */
  size_t message_size;

  /**
   * Continuation function to call once the message
   * has been sent.  Can be NULL if there is no
   * continuation to call.
   */
  GNUNET_TRANSPORT_TransmitContinuation transmit_cont;

  /**
   * Cls for transmit_cont
   */
  void * transmit_cont_cls;

  /**
   * Timeout value for the pending message.
   */
  struct GNUNET_TIME_Absolute timeout;

};

/**
 * Queue for acks to send for fragments recived
 */
//TODO comments
struct AckSendQueue
{

  struct AckSendQueue * next;
  struct AckSendQueue * prev;

  struct Session * session;
  /**
   * ID of message, to distinguish between the messages, picked randomly.
   */
  uint32_t message_id;

  /**
   * Bit field for received fragments
   */
  uint64_t fragments_field;

};

/**
 * Session infos gathered from a messages
 */

struct Session_light
{
  /**
   * the session this message belongs to
   */
  struct Session * session;
  /**
   * peer mac address
   */
  uint8_t addr[6];
};

/**
 * Session handle for connections.
 */
struct Session
{

  /**
   * API requirement.
   */
  struct SessionHeader header;

  /**
   * Pointer to the global plugin struct.
   */
  struct Plugin *plugin;

  /**
   * Message currently pending for transmission
   * to this peer, if any.
   */
  struct PendingMessage *pending_message;

  /**
   * Message currently pending for transmission
   * to this peer, if any.
   */
  struct PendingMessage *pending_message2;

  /**
   * To whom are we talking to (set to our identity
   * if we are still waiting for the welcome message)
   */
  struct GNUNET_PeerIdentity target;

  /**
   * peer mac address
   */
  char addr[6];

  /**
   * Address of the other peer (either based on our 'connect'
   * call or on our 'accept' call).
   */
  void *connect_addr;

  /**
   * Last activity on this connection.  Used to select preferred
   * connection.
   */
  struct GNUNET_TIME_Absolute last_activity;

  /**
   * count of messages in the fragment out queue for this session
   */

  int fragment_messages_out_count;

  /**
   * count of messages in the fragment in queue for this session
   */

  int fragment_messages_in_count;

};

/**
 * Struct for Messages in the fragment queue
 */

struct FragmentMessage
{
  /**
   * Session this message belongs to
   */

  struct Session *session;

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

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

  /**
   * The pending message
   */
  char *msg;

  /**
   * Timeout value for the pending message.
   */
  struct GNUNET_TIME_Absolute timeout;

  /**
   * Timeout value for the pending fragments.
   * Stores the time when the next msg fragment ack has to be received
   */
  struct GNUNET_TIME_Absolute next_ack;

  /**
   * bitfield with all acks received for this message
   */
  uint64_t ack_bitfield;

  /**
   * Size of the message
   */
  size_t message_size;

  /**
   * pos / next fragment number in the message, for fragmentation/segmentation,
   * some acks can be missing but there is still time
   */
  uint32_t message_pos;

  /**
   * current number for message outgoing, to distinguish between the messages
   */
  uint32_t message_id_out;
};

/**
 * Header for messages which need fragmentation
 */
struct WlanHeader
{

  struct GNUNET_MessageHeader header;

  /**
   * checksum/error correction
   */
  uint32_t crc GNUNET_PACKED;

  /**
   * To whom are we talking to (set to our identity
   * if we are still waiting for the welcome message)
   */
  struct GNUNET_PeerIdentity target;

// followed by payload

};

/**
 * Header for messages which need fragmentation
 */
struct FragmentationHeader
{

  struct GNUNET_MessageHeader header;

  /**
   * ID of message, to distinguish between the messages, picked randomly.
   */
  uint32_t message_id GNUNET_PACKED;

  /**
   * Offset or number of this fragment, for fragmentation/segmentation (design choice, TBD)
   */
  uint16_t fragment_off_or_num GNUNET_PACKED;

  /**
   * CRC of fragment (for error checking)
   */
  uint16_t message_crc GNUNET_PACKED;

// followed by payload

};

/**
 * Header for messages which need fragmentation
 */
struct FragmentationAckHeader
{

  struct GNUNET_MessageHeader header;

  /**
   * ID of message, to distinguish between the messages, picked randomly.
   */
  uint32_t message_id GNUNET_PACKED;

  /**
   * Offset or number of this fragment, for fragmentation/segmentation (design choice, TBD)
   */
  uint64_t fragment_field GNUNET_PACKED;

};

int
getRadiotapHeader(struct RadiotapHeader * Header);

int
getWlanHeader(struct IeeeHeader * Header, const char * to_mac_addr,
    struct Plugin * plugin);

static int
wlan_plugin_address_suggested(void *cls, const void *addr, size_t addrlen);

uint16_t
getcrc16(const char *msgbuf, size_t msgbuf_size);

static void
do_transmit(void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc);

static void
check_fragment_queue(struct Plugin * plugin);

uint32_t
getcrc32(const char *msgbuf, size_t msgbuf_size);

static void
free_receive_message(struct Plugin* plugin,
    struct Receive_Message_Queue * rec_message);

struct Receive_Message_Queue *
get_receive_message_from_session(struct Plugin * plugin,
    struct Session * session);

static void
wlan_data_helper(void *cls, struct Session_light * session_light,
    const struct GNUNET_MessageHeader * hdr);

static void
wlan_process_helper(void *cls, void *client,
    const struct GNUNET_MessageHeader *hdr);

static void
finish_sending(void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc);

static void
wlan_data_massage_handler(struct Plugin * plugin,
    struct Session_light * session_light,
    const struct GNUNET_MessageHeader * hdr);

static const char *
wlan_plugin_address_to_string(void *cls, const void *addr, size_t addrlen);

struct Receive_Message_Queue *
get_receive_message(struct Plugin * plugin, struct Session * session,
    uint32_t message_id);

static uint64_t
htonll(uint64_t input)
{
  return input;
}

static uint64_t
ntohll(uint64_t input)
{
  return input;
}

/**
 * Sets a bit active in the bitArray. Increment bit-specific
 * usage counter on disk only if below 4bit max (==15).
 *
 * @param bitArray memory area to set the bit in
 * @param bitIdx which bit to set
 */
static void
setBit(char *bitArray, unsigned int bitIdx)
{
  size_t arraySlot;
  unsigned int targetBit;

  arraySlot = bitIdx / 8;
  targetBit = (1L << (bitIdx % 8));
  bitArray[arraySlot] |= targetBit;
}

/**
 * Clears a bit from bitArray. Bit is cleared from the array
 * only if the respective usage counter on the disk hits/is zero.
 *
 * @param bitArray memory area to set the bit in
 * @param bitIdx which bit to unset
 */
/*static void
clearBit(char *bitArray, unsigned int bitIdx)
{
  size_t slot;
  unsigned int targetBit;

  slot = bitIdx / 8;
  targetBit = (1L << (bitIdx % 8));
  bitArray[slot] = bitArray[slot] & (~targetBit);
}*/

/**
 * Checks if a bit is active in the bitArray
 *
 * @param bitArray memory area to set the bit in
 * @param bitIdx which bit to test
 * @return GNUNET_YES if the bit is set, GNUNET_NO if not.
 */
static int
testBit(char *bitArray, unsigned int bitIdx)
{
  size_t slot;
  unsigned int targetBit;

  slot = bitIdx / 8;
  targetBit = (1L << (bitIdx % 8));
  if (bitArray[slot] & targetBit)
    return GNUNET_YES;
  else
    return GNUNET_NO;
}

/**
 * Sets a bit active in the bitArray.
 *
 * @param bitArray memory area to set the bit in
 * @param bitIdx which bit to set
 */
/*static uint64_t
 setBit (uint64_t bitArray, unsigned int bitIdx)
 {
 uint64_t targetBit;

 targetBit = (1ULL << bitIdx);
 return bitArray | targetBit;
 }
 */
/**
 * Clears a bit from bitArray.
 *
 * @param bitArray memory area to set the bit in
 * @param bitIdx which bit to unset
 */
/*static uint64_t
 clearBit (uint64_t bitArray, unsigned int bitIdx)
 {
 uint64_t targetBit;

 targetBit = (1ULL << bitIdx);
 return bitArray & (~targetBit);
 }
 */
/**
 * Checks if a bit is active in the bitArray
 *
 * @param bitArray memory area to set the bit in
 * @param bitIdx which bit to test
 * @return GNUNET_YES if the bit is set, GNUNET_NO if not.
 */
/*static int
 testBit (uint64_t bitArray, unsigned int bitIdx)
 {
 uint64_t targetBit;


 targetBit = (1ULL << bitIdx);
 if (bitArray & targetBit)
 return GNUNET_YES;
 else
 return GNUNET_NO;
 }
 */
/**
 * get the next message number, at the moment just a random one
 * @return returns the next valid message-number for sending packets
 */
uint32_t
get_next_message_id()
{
  return GNUNET_CRYPTO_random_u32(GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX);
}

/**
 * start next message number generator
 * (not necessary at the moment)
 */
void
start_next_message_id()
{
  //GNUNET_CRYPTO_random_init;
}

/**
 * search for a session with the addr
 *
 * @param plugin pointer to the plugin struct
 * @param addr pointer to the mac address of the peer
 * @return returns the session
 */

static struct Session *
search_session(struct Plugin *plugin, const uint8_t * addr)
{
  struct Sessionqueue * queue = plugin->sessions;
  struct Sessionqueue * lastitem = NULL;

  //just look at all the session for the needed one
  while (queue != NULL)
    {
      // content is never NULL
      GNUNET_assert (queue->content != NULL);
      char * addr2 = queue->content->addr;
      if (memcmp(addr, addr2, 6) == 0)
        {
          //sesion found
          return queue->content;
        }
      // try next
      lastitem = queue;
      queue = queue->next;
    }
  return NULL;
}

/**
 * create a new session
 *
 * @param plugin pointer to the plugin struct
 * @param addr pointer to the mac address of the peer
 * @return returns the session
 */

static struct Session *
create_session(struct Plugin *plugin, const uint8_t * addr)
{
  struct Sessionqueue * queue = GNUNET_malloc (sizeof (struct Sessionqueue));

  GNUNET_CONTAINER_DLL_insert_tail(plugin->sessions, plugin->sessions_tail, queue);

  queue->content = GNUNET_malloc (sizeof (struct Session));
  queue->content->plugin = plugin;
  memcpy(queue->content->addr, addr, 6);
  queue->content->fragment_messages_out_count = 0;
  queue->content->fragment_messages_in_count = 0;

  plugin->session_count++;

#if DEBUG_wlan
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "New session %p with %s\n",
      queue->content, wlan_plugin_address_to_string(NULL, addr, 6));
#endif

  return queue->content;
}

/**
 * get Session from address, create if no session exists
 *
 * @param plugin pointer to the plugin struct
 * @param addr pointer to the mac address of the peer
 * @return returns the session
 */
//TODO add other possibilities to find the right session (are there other?)
static struct Session *
get_Session(struct Plugin *plugin, const uint8_t * addr)
{
  struct Session * session = search_session(plugin, addr);
  if (session != NULL)
    {
      return session;
    }
  // new session
  return create_session(plugin, addr);

  /* -- not needed, layer above already has it--
   //queue welcome message for new sessions, not realy needed
   //struct WelcomeMessage welcome;
   struct PendingMessage *pm;
   pm = GNUNET_malloc (sizeof (struct PendingMessage));
   pm->msg = GNUNET_malloc(GNUNET_HELLO_size(* (plugin->env->our_hello)));
   pm->message_size = GNUNET_HELLO_size(* (plugin->env->our_hello));
   //welcome.header.size = htons (GNUNET_HELLO_size(* (plugin->env->our_hello)));
   //welcome.header.type = htons (GNUNET_MESSAGE_TYPE_WLAN_ADVERTISEMENT);
   //welcome.clientIdentity = *plugin->env->my_identity;
   memcpy ( (pm->msg), * plugin->env->our_hello, GNUNET_HELLO_size(* (plugin->env->our_hello)));
   pm->timeout = GNUNET_TIME_UNIT_FOREVER_ABS;
   queue->content->pending_message = pm;
   plugin->pendingsessions ++;
   GNUNET_CONTAINER_DLL_insert_tail(plugin->pending_Sessions, plugin->pending_Sessions_tail, queue);

   check_fragment_queue(plugin);
   */
}

/**
 * Queue the session to send data
 */
//TODO doxigen
static void
queue_Session(struct Plugin *plugin, struct Session * session)
{
  struct Sessionqueue * queue = plugin->pending_Sessions;
  struct Sessionqueue * lastitem = NULL;

  while (queue != NULL)
    {
      // content is never NULL
      GNUNET_assert (queue->content != NULL);
      // is session already in queue?
      if (session == queue->content)
        {
          return;
        }
      // try next
      lastitem = queue;
      queue = queue->next;
    }

  // Session is not in the queue

  queue = GNUNET_malloc (sizeof (struct Sessionqueue));
  queue->content = session;

  //insert at the tail
  GNUNET_CONTAINER_DLL_insert_after (plugin->pending_Sessions,
      plugin->pending_Sessions_tail,
      plugin->pending_Sessions_tail, queue);
  plugin->pendingsessions++;

}

//TODO doxigen
/**
 * Function to schedule the write task, executed after a delay
 */
static void
delay_fragment_task(void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct Plugin * plugin = cls;
  plugin->server_write_delay_task = GNUNET_SCHEDULER_NO_TASK;

  if (tc->reason == GNUNET_SCHEDULER_REASON_SHUTDOWN)
    return;

  // GNUNET_TIME_UNIT_FOREVER_REL is needed to clean up old msg
  if (plugin->server_write_task == GNUNET_SCHEDULER_NO_TASK)
    {
      plugin->server_write_task = GNUNET_SCHEDULER_add_write_file(
          GNUNET_TIME_UNIT_FOREVER_REL, plugin->server_stdin_handle,
          &do_transmit, plugin);
    }
}

//TODO doxigen
/**
 * Function to calculate the time of the next periodic "hello-beacon"
 */
static void
set_next_beacon_time(struct Plugin * const plugin)
{
  //under 10 known peers: once a second
  if (plugin->session_count < 10)
    {
      plugin->beacon_time = GNUNET_TIME_absolute_add(
          GNUNET_TIME_absolute_get(), GNUNET_TIME_relative_multiply(
              GNUNET_TIME_UNIT_SECONDS, HALLO_BEACON_SCALING_FACTOR));
    }
  //under 30 known peers: every 10 seconds
  else if (plugin->session_count < 30)
    {
      plugin->beacon_time = GNUNET_TIME_absolute_add(
          GNUNET_TIME_absolute_get(), GNUNET_TIME_relative_multiply(
              GNUNET_TIME_UNIT_SECONDS, 10 * HALLO_BEACON_SCALING_FACTOR));
    }
  //over 30 known peers: once a minute
  else
    {
      plugin->beacon_time = GNUNET_TIME_absolute_add(
          GNUNET_TIME_absolute_get(), GNUNET_TIME_relative_multiply(
              GNUNET_TIME_UNIT_MINUTES, HALLO_BEACON_SCALING_FACTOR));
    }
}

//TODO doxigen
struct GNUNET_TIME_Relative
get_next_frag_timeout(struct FragmentMessage * fm)
{
  return GNUNET_TIME_relative_min(GNUNET_TIME_absolute_get_remaining(
      fm->next_ack), GNUNET_TIME_absolute_get_remaining(fm->timeout));
}

//TODO doxigen
/**
 * Function to get the timeout value for acks for this session
 */

struct GNUNET_TIME_Relative
get_ack_timeout(struct FragmentMessage * fm)
{
  return FRAGMENT_TIMEOUT;
}

/**
 * Function to set the timer for the next timeout of the fragment queue
 * @param plugin the handle to the plugin struct
 */
static void
check_next_fragment_timeout(struct Plugin * const plugin)
{
  struct FragmentMessage * fm;
  struct GNUNET_TIME_Relative next_send;

  next_send = GNUNET_TIME_absolute_get_remaining(plugin->beacon_time);

  //cancel old task
  if (plugin->server_write_delay_task != GNUNET_SCHEDULER_NO_TASK)
    {
      GNUNET_SCHEDULER_cancel(plugin->server_write_delay_task);
      plugin->server_write_delay_task = GNUNET_SCHEDULER_NO_TASK;
    }
  fm = plugin->pending_Fragment_Messages_head;

  GNUNET_assert(plugin->server_write_delay_task == GNUNET_SCHEDULER_NO_TASK);

  //check if some acks are in the queue
  if (plugin->ack_send_queue_head != NULL)
    {
      next_send = GNUNET_TIME_relative_get_zero();
    }
  //check if there are some fragments in the queue
  else if (fm != NULL)
    {
      next_send
          = GNUNET_TIME_relative_min(next_send, get_next_frag_timeout(fm));
    }
  plugin->server_write_delay_task = GNUNET_SCHEDULER_add_delayed(next_send,
      &delay_fragment_task, plugin);
}

//TODO doxigen
/**
 * Function to get the next queued Session, removes the session from the queue
 */

static struct Session *
get_next_queue_Session(struct Plugin * plugin)
{
  struct Session * session;
  struct Sessionqueue * sessionqueue;
  struct Sessionqueue * sessionqueue_alt;
  struct PendingMessage * pm;
  sessionqueue = plugin->pending_Sessions;
  while (sessionqueue != NULL)
    {
      session = sessionqueue->content;

      pm = session->pending_message;
      if (pm == NULL){
#if DEBUG_wlan
      GNUNET_log(GNUNET_ERROR_TYPE_ERROR,
          "pending message is empty, should not happen. session %p\n", session);
#endif
      }
      GNUNET_assert(pm != NULL);

      //check for message timeout
      if (GNUNET_TIME_absolute_get_remaining(pm->timeout).rel_value > 0)
        {
          //check if session has no message in the fragment queue
          if (session->fragment_messages_out_count
              < FRAGMENT_QUEUE_MESSAGES_OUT_PER_SESSION)
            {
              plugin->pendingsessions--;
              GNUNET_CONTAINER_DLL_remove (plugin->pending_Sessions,
                  plugin->pending_Sessions_tail, sessionqueue);
              GNUNET_free(sessionqueue);

              return session;
            }
          else
            {
              sessionqueue = sessionqueue->next;
            }
        }
      else
        {

          session->pending_message = session->pending_message2;
          session->pending_message2 = NULL;

          //call the cont func that it did not work
          if (pm->transmit_cont != NULL)
            pm->transmit_cont(pm->transmit_cont_cls, &(session->target),
                GNUNET_SYSERR);
          GNUNET_free(pm->msg);
          GNUNET_free(pm);

          if (session->pending_message == NULL)
            {
              sessionqueue_alt = sessionqueue;
              sessionqueue = sessionqueue->next;
              plugin->pendingsessions--;
              GNUNET_CONTAINER_DLL_remove (plugin->pending_Sessions,
                  plugin->pending_Sessions_tail, sessionqueue_alt);

              GNUNET_free(sessionqueue_alt);
            }

        }

    }
  return NULL;
}

/**
 * Function to sort the message into the message fragment queue
 * @param plugin the plugin struct
 * @param fm message to sort into the queue
 */
static void
sort_fragment_into_queue(struct Plugin * plugin, struct FragmentMessage * fm)
{
  struct FragmentMessage * fm2;
  //sort into the list at the right position

  fm2 = plugin->pending_Fragment_Messages_head;

  while (fm2 != NULL)
    {
      if (GNUNET_TIME_absolute_get_difference(fm2->next_ack, fm->next_ack).rel_value
          == 0)
        {
          break;
        }
      else
        {
          fm2 = fm2->next;
        }
    }

  GNUNET_CONTAINER_DLL_insert_after(plugin->pending_Fragment_Messages_head,
      plugin->pending_Fragment_Messages_tail,fm2,fm);
}

/**
 * frees the space of a message in the fragment queue (send queue)
 * @param plugin the plugin struct
 * @param fm message to free
 */
static void
free_fragment_message(struct Plugin * plugin, struct FragmentMessage * fm)
{
  if (fm != NULL)
    {
      (fm->session->fragment_messages_out_count)--;
      GNUNET_free_non_null(fm->msg);
      GNUNET_CONTAINER_DLL_remove (plugin->pending_Fragment_Messages_head,
          plugin->pending_Fragment_Messages_tail, fm);
      GNUNET_free(fm);
      plugin->pending_fragment_messages--;

#if DEBUG_wlan
      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
          "free pending fragment messages, pending messages remaining %u\n",
          plugin->pending_fragment_messages);
#endif
    }
}

/**
 * Function to check if there is some space in the fragment queue
 * inserts a message if space is available
 * @param plugin the plugin struct
 */

static void
check_fragment_queue(struct Plugin * plugin)
{
  struct Session * session;
  struct FragmentMessage * fm;
  struct GNUNET_PeerIdentity pid;

  struct PendingMessage * pm;

  if (plugin->pending_fragment_messages < FRAGMENT_QUEUE_SIZE)
    {
      session = get_next_queue_Session(plugin);
      if (session != NULL)
        {
          pm = session->pending_message;
          session->pending_message = NULL;
          session->fragment_messages_out_count++;
          GNUNET_assert(pm != NULL);

          fm = GNUNET_malloc(sizeof(struct FragmentMessage));
          fm->message_size = pm->message_size;
          fm->msg = pm->msg;
          fm->session = session;
          fm->timeout.abs_value = pm->timeout.abs_value;
          fm->message_pos = 0;
          fm->next_ack = GNUNET_TIME_absolute_get();
          fm->message_id_out = get_next_message_id();
          fm->ack_bitfield = 0;

          sort_fragment_into_queue(plugin, fm);
          plugin->pending_fragment_messages++;

          if (pm->transmit_cont != NULL)
            {
              pid = session->target;
              pm->transmit_cont(pm->transmit_cont_cls, &pid, GNUNET_OK);
#if DEBUG_wlan
              GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
                  "called pm->transmit_cont for %p\n", session);
#endif
            }
          else
            {
#if DEBUG_wlan
              GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
                  "no pm->transmit_cont for %p\n", session);
#endif
            }
          GNUNET_free(pm);

          if (session->pending_message2 != NULL){
            session->pending_message = session->pending_message2;
            session->pending_message2 = NULL;
            //requeue session
            queue_Session(plugin, session);
          }

          //check if timeout changed
          check_next_fragment_timeout(plugin);
        }
    }
}

/**
 * Funktion to check if all fragments where send and the acks received
 * frees the space if finished
 * @param plugin the plugin struct
 * @param fm the message to check
 */
static void
check_finished_fragment(struct Plugin * plugin, struct FragmentMessage * fm)
{
  //maxack = size of message / max packet size, eg 12 / 5 = 2 start at 0 so ack numbers are 0,1,2
  unsigned int maxack = 63 - ((fm->message_size - 1) / (WLAN_MTU
      - sizeof(struct FragmentationHeader)));
  uint64_t tmpfield = 0xFFFFFFFFFFFFFFFF;
  tmpfield = tmpfield >> maxack;

  //#if DEBUG_wlan
  if (maxack != 63)
    GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
        "Test bitfields %X and %X, maxack is %u, fm size %u\n",
        fm->ack_bitfield, tmpfield, maxack, fm->message_size);
  //#endif

  if (fm->ack_bitfield == tmpfield)
    {

      free_fragment_message(plugin, fm);

#if DEBUG_wlan
      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
          "Finished sending and got all acks for a fragmented message\n");
#endif

      check_next_fragment_timeout(plugin);
      check_fragment_queue(plugin);

    }
}

/**
 * Function to set the next fragment number
 * @param fm use this FragmentMessage
 */

void
set_next_message_fragment_pos(struct FragmentMessage * fm)
{

  //check if retransmit is needed
  if (GNUNET_TIME_absolute_get_remaining(fm->next_ack).rel_value == 0)
    {

      // be positive and try again later :-D
      fm->next_ack = GNUNET_TIME_relative_to_absolute(get_ack_timeout(fm));
      // find first missing fragment

      fm->message_pos = 0;
    }

  //test if ack 0 (or X) was already received
  while (testBit((char*) &fm->ack_bitfield, fm->message_pos) == GNUNET_YES)
    {
      fm->message_pos++;
    }

}

void
send_hello_beacon(struct Plugin * plugin)
{

#if DEBUG_wlan
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Sending hello beacon\n");
#endif

  uint16_t size = 0;
  ssize_t bytes;
  struct GNUNET_MessageHeader * msgheader = NULL;
  struct IeeeHeader * ieeewlanheader = NULL;
  struct RadiotapHeader * radioHeader = NULL;
  struct GNUNET_MessageHeader * msgheader2 = NULL;

  GNUNET_assert(sizeof(struct WlanHeader) + GNUNET_HELLO_size(
          *(plugin->env->our_hello)) <= WLAN_MTU);
  size = sizeof(struct GNUNET_MessageHeader) + sizeof(struct RadiotapHeader)
      + sizeof(struct IeeeHeader) + sizeof(struct GNUNET_MessageHeader)
      + GNUNET_HELLO_size(*(plugin->env->our_hello));

  msgheader = GNUNET_malloc(size);
  msgheader->size = htons(size);
  msgheader->type = htons(GNUNET_MESSAGE_TYPE_WLAN_HELPER_DATA);

  radioHeader = (struct RadiotapHeader*) &msgheader[1];
  getRadiotapHeader(radioHeader);
  ieeewlanheader = (struct IeeeHeader*) &radioHeader[1];
  getWlanHeader(ieeewlanheader, bc_all_mac, plugin);

  msgheader2 = (struct GNUNET_MessageHeader*) &ieeewlanheader[1];
  msgheader2->size = htons(GNUNET_HELLO_size(*(plugin->env->our_hello))
      + sizeof(struct GNUNET_MessageHeader));

  msgheader2->type = htons(GNUNET_MESSAGE_TYPE_WLAN_ADVERTISEMENT);
  memcpy(&msgheader2[1], *plugin->env->our_hello, GNUNET_HELLO_size(
      *(plugin->env->our_hello)));

  bytes = GNUNET_DISK_file_write(plugin->server_stdin_handle, msgheader, size);

  if (bytes == GNUNET_SYSERR)
    {
      GNUNET_log(GNUNET_ERROR_TYPE_ERROR,
          _("Error writing to wlan healper. errno == %d, ERROR: %s\n"),
          errno, strerror(errno));

    }
  GNUNET_assert(bytes != GNUNET_SYSERR);
  GNUNET_assert(bytes == size);
  GNUNET_free(msgheader);

  set_next_beacon_time(plugin);
  check_next_fragment_timeout(plugin);
}

static void
send_ack(struct Plugin * plugin, struct AckSendQueue * ack)
{

  uint16_t size = 0;
  ssize_t bytes;
  struct GNUNET_MessageHeader * msgheader = NULL;
  struct IeeeHeader * ieeewlanheader = NULL;
  struct RadiotapHeader * radioHeader = NULL;
  struct FragmentationAckHeader * msgheader2 = NULL;

  GNUNET_assert(sizeof(struct FragmentationAckHeader) <= WLAN_MTU);

#if DEBUG_wlan
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
      "Sending ack for message_id %u with fragment field %u\n",
      ack->message_id, ack->fragments_field);
#endif

  size = sizeof(struct GNUNET_MessageHeader) + sizeof(struct RadiotapHeader)
      + sizeof(struct IeeeHeader) + sizeof(struct FragmentationAckHeader);
  msgheader = GNUNET_malloc(size);
  msgheader->size = htons(size);
  msgheader->type = htons(GNUNET_MESSAGE_TYPE_WLAN_HELPER_DATA);

  radioHeader = (struct RadiotapHeader*) &msgheader[1];
  getRadiotapHeader(radioHeader);
  ieeewlanheader = (struct IeeeHeader*) &radioHeader[1];
  getWlanHeader(ieeewlanheader, ack->session->addr, plugin);

  msgheader2 = (struct FragmentationAckHeader*) &ieeewlanheader[1];
  msgheader2->header.size = htons(sizeof(struct FragmentationAckHeader));
  msgheader2->header.type = htons(GNUNET_MESSAGE_TYPE_WLAN_FRAGMENT_ACK);
  msgheader2->message_id = htonl(ack->message_id);
  msgheader2->fragment_field = htonll(ack->fragments_field);

  bytes = GNUNET_DISK_file_write(plugin->server_stdin_handle, msgheader, size);
  if (bytes == GNUNET_SYSERR)
    {
      GNUNET_log(GNUNET_ERROR_TYPE_ERROR,
          _("Error writing to wlan healper. errno == %d, ERROR: %s\n"),
          errno, strerror(errno));

    }
  GNUNET_assert(bytes != GNUNET_SYSERR);
  GNUNET_assert(bytes == size);
  GNUNET_free(msgheader);
  check_next_fragment_timeout(plugin);
}

/**
 * Function called when wlan helper is ready to get some data
 *
 * @param cls closure
 * @param tc GNUNET_SCHEDULER_TaskContext
 */

static void
do_transmit(void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
{

  struct Plugin * plugin = cls;
  plugin->server_write_task = GNUNET_SCHEDULER_NO_TASK;

  if (tc->reason == GNUNET_SCHEDULER_REASON_SHUTDOWN)
    return;

  struct Session * session = NULL;
  struct FragmentMessage * fm = NULL;
  struct IeeeHeader * ieeewlanheader = NULL;
  struct RadiotapHeader * radioHeader = NULL;
  struct GNUNET_MessageHeader * msgheader = NULL;

  struct FragmentationHeader fragheader;
  struct FragmentationHeader * fragheaderptr = NULL;
  struct Finish_send * finish = NULL;
  struct AckSendQueue * ack;
  uint16_t size = 0;
  ssize_t bytes;
  const char * copystart = NULL;
  uint16_t copysize = 0;
  uint copyoffset = 0;

  if (plugin->ack_send_queue_head != NULL)
    {
      ack = plugin->ack_send_queue_head;
      GNUNET_CONTAINER_DLL_remove(plugin->ack_send_queue_head,
          plugin->ack_send_queue_tail, ack);
      send_ack(plugin, ack);
      GNUNET_free(ack);
      return;
    }

  //test if a "hello-beacon" has to be send
  if (GNUNET_TIME_absolute_get_remaining(plugin->beacon_time).rel_value == 0)
    {
      send_hello_beacon(plugin);

      return;

    }

  fm = plugin->pending_Fragment_Messages_head;
  if (fm != NULL)
    {
      session = fm->session;
      GNUNET_assert(session != NULL);

      // test if message timed out
      if (GNUNET_TIME_absolute_get_remaining(fm->timeout).rel_value == 0)
        {
#if DEBUG_wlan
          GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "message timeout\n");
#endif

          check_fragment_queue(plugin);
          free_fragment_message(plugin, fm);

        }
      else
        {

          //if (fm->message_size > WLAN_MTU)
          // {
          size += sizeof(struct FragmentationHeader);

          set_next_message_fragment_pos(fm);

          copyoffset = (WLAN_MTU - sizeof(struct FragmentationHeader))
              * fm->message_pos;

#if DEBUG_wlan
          GNUNET_log(
              GNUNET_ERROR_TYPE_DEBUG,
              "Sending GNUNET_MESSAGE_TYPE_WLAN_FRAGMENT with message_id %u with fragment number %i, size: %u, offset %u, time until timeout %u\n",
              fm->message_id_out, fm->message_pos, copysize
                  + sizeof(struct FragmentationHeader), copyoffset,
              GNUNET_TIME_absolute_get_remaining(fm->timeout));
#endif

          fragheader.fragment_off_or_num = htons(fm->message_pos);
          fragheader.message_id = htonl(fm->message_id_out);
          copystart = fm->msg + copyoffset;
          copysize = GNUNET_MIN(fm->message_size - copyoffset,
              WLAN_MTU - sizeof(struct FragmentationHeader));

          if (copyoffset >= fm->message_size)
            {
              GNUNET_log(
                  GNUNET_ERROR_TYPE_ERROR,
                  "offset in message for fragment too large, offset %u, size %u, max size %u, copysize %u, message_pos %u,\n",
                  copyoffset, fm->message_size, WLAN_MTU
                      - sizeof(struct FragmentationHeader), copysize,
                  fm->message_pos);
            }
          GNUNET_assert(copyoffset < fm->message_size);
          //FIXME remove later
          GNUNET_assert(copystart < fm->msg + fm->message_size);

          fragheader.header.size = htons(copysize
              + sizeof(struct FragmentationHeader));
          fragheader.header.type = htons(GNUNET_MESSAGE_TYPE_WLAN_FRAGMENT);

          /* }
           else
           {
           // there is no need to split
           copystart = fm->msg;
           copysize = fm->message_size;
           }*/

          size += copysize;
          size += sizeof(struct RadiotapHeader) + sizeof(struct IeeeHeader)
              + sizeof(struct GNUNET_MessageHeader);
          msgheader = GNUNET_malloc(size);
          msgheader->size = htons(size);
          msgheader->type = htons(GNUNET_MESSAGE_TYPE_WLAN_HELPER_DATA);

          radioHeader = (struct RadiotapHeader*) &msgheader[1];
          getRadiotapHeader(radioHeader);

          ieeewlanheader = (struct IeeeHeader *) &radioHeader[1];
          getWlanHeader(ieeewlanheader, fm->session->addr, plugin);

          //could be faster if content is just send and not copyed before
          //fragmentheader is needed
          //if (fm->message_size > WLAN_MTU)
          // {
          fragheader.message_crc = htons(getcrc16(copystart, copysize));
          memcpy(&ieeewlanheader[1], &fragheader,
              sizeof(struct FragmentationHeader));
          fragheaderptr = (struct FragmentationHeader *) &ieeewlanheader[1];
          memcpy(&fragheaderptr[1], copystart, copysize);
          /* }
           else
           {
           memcpy(&ieeewlanheader[1], copystart, copysize);
           }*/

          bytes = GNUNET_DISK_file_write(plugin->server_stdin_handle,
              msgheader, size);
          if (bytes == GNUNET_SYSERR)
            {
              GNUNET_log(
                  GNUNET_ERROR_TYPE_ERROR,
                  _("Error writing to wlan healper. errno == %d, ERROR: %s\n"),
                  errno, strerror(errno));

            }
          GNUNET_assert(bytes != GNUNET_SYSERR);

          if (bytes != size)
            {
              finish = GNUNET_malloc(sizeof( struct Finish_send));
              finish->plugin = plugin;
              finish->msgheader = (char *) msgheader + bytes;
              finish->size = size - bytes;
              finish->msgstart = msgheader;

              GNUNET_assert(plugin->server_write_task == GNUNET_SCHEDULER_NO_TASK);

              plugin->server_write_task = GNUNET_SCHEDULER_add_write_file(
                  GNUNET_TIME_UNIT_FOREVER_REL, plugin->server_stdin_handle,
                  &finish_sending, finish);

            }
          else
            {
              GNUNET_assert(bytes == size);

              GNUNET_free(msgheader);
              check_next_fragment_timeout(plugin);
            }

          //check if this was the last fragment of this message, if true then queue at the end of the list
          if (copysize + copyoffset >= fm->message_size)
            {
              GNUNET_assert(copysize + copyoffset == fm->message_size);

              GNUNET_CONTAINER_DLL_remove (plugin->pending_Fragment_Messages_head,
                  plugin->pending_Fragment_Messages_tail, fm);

              GNUNET_CONTAINER_DLL_insert_tail(plugin->pending_Fragment_Messages_head,
                  plugin->pending_Fragment_Messages_tail, fm);
              // if fragments have opimized timeouts
              //sort_fragment_into_queue(plugin,fm);

            }

        }
      return;
    }
  GNUNET_log(GNUNET_ERROR_TYPE_WARNING,
      "do_transmit did nothing, should not happen!\n");
}

static void
finish_sending(void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct Finish_send * finish;
  struct Plugin * plugin;
  ssize_t bytes;

  finish = cls;
  plugin = finish->plugin;

  plugin->server_write_task = GNUNET_SCHEDULER_NO_TASK;

  bytes = GNUNET_DISK_file_write(plugin->server_stdin_handle,
      finish->msgheader, finish->size);
  GNUNET_assert(bytes != GNUNET_SYSERR);

  GNUNET_assert(plugin->server_write_task == GNUNET_SCHEDULER_NO_TASK);
  if (bytes != finish->size)
    {

      finish->plugin = plugin;
      finish->msgheader = finish->msgheader + bytes;
      finish->size = finish->size - bytes;
      plugin->server_write_task = GNUNET_SCHEDULER_add_write_file(
          GNUNET_TIME_UNIT_FOREVER_REL, plugin->server_stdin_handle,
          &finish_sending, finish);
    }
  else
    {
      GNUNET_free(finish->msgstart);
      GNUNET_free(finish);
      check_next_fragment_timeout(plugin);
    }

}

int
getRadiotapHeader(struct RadiotapHeader * Header)
{
  return GNUNET_YES;
}
;

/**
 * function to generate the wlan hardware header for one packet
 * @param Header address to write the header to
 * @param to_mac_addr address of the recipient
 * @param plugin pointer to the plugin struct
 * @return GNUNET_YES if there was no error
 */

int
getWlanHeader(struct IeeeHeader * Header, const char * const to_mac_addr,
    struct Plugin * plugin)
{
  memcpy(&Header->mac2, macbc, sizeof(macbc));
  memcpy(&Header->mac3, plugin->mac_address.mac, sizeof(plugin->mac_address));
  memcpy(&Header->mac1, to_mac_addr, sizeof(plugin->mac_address));
  return GNUNET_YES;
}

/**
 * 32bit CRC
 *
 * @param msgbuf pointer tor the data
 * @param msgbuf_size size of the data
 *
 * @return 32bit crc value
 */

uint32_t
getcrc32(const char *msgbuf, size_t msgbuf_size)
{
  //TODO calc some crc
  return 0;
}

/**
 * 16bit CRC
 *
 * @param msgbuf pointer tor the data
 * @param msgbuf_size size of the data
 *
 * @return 16bit crc value
 */

uint16_t
getcrc16(const char *msgbuf, size_t msgbuf_size)
{
  //TODO calc some crc
  return 0;
}

/**
 * Function that can be used by the transport service to transmit
 * a message using the plugin.
 *
 * @param cls closure
 * @param target who should receive this message
 * @param priority how important is the message
 * @param msgbuf the message to transmit
 * @param msgbuf_size number of bytes in 'msgbuf'
 * @param timeout when should we time out 
 * @param session which session must be used (or NULL for "any")
 * @param addr the address to use (can be NULL if the plugin
 *                is "on its own" (i.e. re-use existing TCP connection))
 * @param addrlen length of the address in bytes
 * @param force_address GNUNET_YES if the plugin MUST use the given address,
 *                otherwise the plugin may use other addresses or
 *                existing connections (if available)
 * @param cont continuation to call once the message has
 *        been transmitted (or if the transport is ready
 *        for the next transmission call; or if the
 *        peer disconnected...)
 * @param cont_cls closure for cont
 * @return number of bytes used (on the physical network, with overheads);
 *         -1 on hard errors (i.e. address invalid); 0 is a legal value
 *         and does NOT mean that the message was not transmitted (DV)
 */
static ssize_t
wlan_plugin_send(void *cls, const struct GNUNET_PeerIdentity * target,
    const char *msgbuf, size_t msgbuf_size, unsigned int priority,
    struct GNUNET_TIME_Relative timeout, struct Session *session,
    const void *addr, size_t addrlen, int force_address,
    GNUNET_TRANSPORT_TransmitContinuation cont, void *cont_cls)
{
  struct Plugin * plugin = cls;
  struct PendingMessage * newmsg = NULL;
  struct WlanHeader * wlanheader = NULL;

  //check if msglen > 0
  GNUNET_assert(msgbuf_size > 0);

  //get session if needed
  if (session == NULL)
    {
      if (wlan_plugin_address_suggested(plugin, addr, addrlen) == GNUNET_OK)
        {
          session = get_Session(plugin, addr);
        }
      else
        {
          GNUNET_log(GNUNET_ERROR_TYPE_ERROR,
              _("Wlan Address len %d is wrong\n"), addrlen);
          return -1;
        }
    }

  //TODO target "problem" not solved
  //if (session->target != NULL){
  //  GNUNET_assert(session->target == *target);
  //} else {
    session->target = *target;
  //}


  //queue message:

  //queue message in session
  //test if there is no other message in the "queue"
  //FIXME: to many send requests
  //GNUNET_assert (session->pending_message == NULL);
  if (session->pending_message != NULL)
    {
      newmsg = session->pending_message;
      GNUNET_log(
          GNUNET_ERROR_TYPE_ERROR,
          "wlan_plugin_send: a pending message is already in the queue for this client\n remaining time to send this message is %u, queued fragment messages %u\n",
          GNUNET_TIME_absolute_get_remaining(newmsg->timeout).rel_value,
          session->fragment_messages_out_count);
      if (session->pending_message2 != NULL)
        {
          GNUNET_log(
              GNUNET_ERROR_TYPE_ERROR,
              "wlan_plugin_send: two pending messages are already in the queue for this client\n");
          return -1;
        }
    }

  newmsg = GNUNET_malloc(sizeof(struct PendingMessage));
  (newmsg->msg) = GNUNET_malloc(msgbuf_size + sizeof(struct WlanHeader));
  wlanheader = (struct WlanHeader *) newmsg->msg;
  //copy msg to buffer, not fragmented / segmented yet, but with message header
  wlanheader->header.size = htons(msgbuf_size + sizeof(struct WlanHeader));
  wlanheader->header.type = htons(GNUNET_MESSAGE_TYPE_WLAN_DATA);
  memcpy(&(wlanheader->target), target, sizeof(struct GNUNET_PeerIdentity));
  wlanheader->crc = htonl(getcrc32(msgbuf, msgbuf_size));
  memcpy(&wlanheader[1], msgbuf, msgbuf_size);
  newmsg->transmit_cont = cont;
  newmsg->transmit_cont_cls = cont_cls;
  newmsg->timeout = GNUNET_TIME_relative_to_absolute(timeout);

  newmsg->timeout.abs_value = newmsg->timeout.abs_value - 500;

  newmsg->message_size = msgbuf_size + sizeof(struct WlanHeader);

  if (session->pending_message == NULL)
    {
      session->pending_message = newmsg;
    }
  else
    {
      session->pending_message2 = newmsg;
    }

#if DEBUG_wlan
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
      "New message for %p with size (incl wlan header) %u added\n", session,
      newmsg->message_size);
#endif


  //queue session
  queue_Session(plugin, session);

  check_fragment_queue(plugin);
  //FIXME not the correct size
  return msgbuf_size;

}

/**
 * function to get the first message in the fragement queue (out) of a session
 * @param session pointer to the session
 * @return pointer to the struct FragmentMessage
 */
static struct FragmentMessage *
get_fragment_message_from_session(struct Session * session)
{
  struct FragmentMessage * fm = session->plugin->pending_Fragment_Messages_head;
  while (fm != NULL)
    {
      if (fm->session == session)
        {
          return fm;
        }
      fm = fm->next;
    }
  return NULL;
}

/**
 * function to get the message in the fragement queue (out) of a session with a specific id
 * @param session pointer to the session
 * @param message_id id of the message
 * @return pointer to the struct FragmentMessage
 */
static struct FragmentMessage *
get_fragment_message_from_session_and_id(struct Session * session,
    uint32_t message_id)
{
  struct FragmentMessage * fm = session->plugin->pending_Fragment_Messages_head;
  while (fm != NULL)
    {
      if ((fm->session == session) && (fm->message_id_out == message_id))
        {
          return fm;
        }
      fm = fm->next;
    }
  return NULL;
}

/**
 * Function that can be used to force the plugin to disconnect
 * from the given peer and cancel all previous transmissions
 * (and their continuation).
 *
 * @param cls closure
 * @param target peer from which to disconnect
 */
static void
wlan_plugin_disconnect(void *cls, const struct GNUNET_PeerIdentity *target)
{
  struct Plugin *plugin = cls;
  struct Sessionqueue * queue = plugin->sessions;
  struct Sessionqueue * pendingsession = plugin->pending_Sessions;
  struct PendingMessage * pm = NULL;
  struct FragmentMessage * fm;
  struct Receive_Message_Queue * receive_queue;

  // just look at all the session for the needed one
  while (queue != NULL)
    {
      // content is never NULL
      GNUNET_assert (queue->content != NULL);
      if (memcmp(target, &(queue->content->target),
          sizeof(struct GNUNET_PeerIdentity)) == 0)
        {
          //session found
          //is this session pending for send
          while (pendingsession != NULL)
            {
              if (pendingsession->content == queue->content)
                {
                  plugin->pendingsessions--;
                  GNUNET_CONTAINER_DLL_remove (plugin->pending_Sessions,
                      plugin->pending_Sessions_tail, pendingsession);
                  GNUNET_free(pendingsession);
                  break;
                }
              pendingsession = pendingsession->next;
            }

          //is something of this session in the fragment queue?
          fm = get_fragment_message_from_session(queue->content);
          while (fm != NULL)
            {
              free_fragment_message(plugin, fm);
              fm = get_fragment_message_from_session(queue->content);
            }
          check_next_fragment_timeout(plugin);

          //dispose all received fragments
          receive_queue = get_receive_message_from_session(plugin,
              queue->content);
          while (receive_queue != NULL)
            {
              free_receive_message(plugin, receive_queue);
              receive_queue = get_receive_message_from_session(plugin,
                  queue->content);
            }

          // remove PendingMessage
          pm = queue->content->pending_message;
          if (pm != NULL)
            {
              GNUNET_free_non_null(pm->msg);
              GNUNET_free(pm);
            }

          GNUNET_free(queue->content);
          GNUNET_CONTAINER_DLL_remove(plugin->sessions, plugin->sessions_tail, queue);
          GNUNET_free(queue);
          plugin->session_count--;

          return;
        }
      // try next
      queue = queue->next;
    }
}

/**
 * Convert the transports address to a nice, human-readable
 * format.
 *
 * @param cls closure
 * @param type name of the transport that generated the address
 * @param addr one of the addresses of the host, NULL for the last address
 *        the specific address format depends on the transport
 * @param addrlen length of the address
 * @param numeric should (IP) addresses be displayed in numeric form?
 * @param timeout after how long should we give up?
 * @param asc function to call on each string
 * @param asc_cls closure for asc
 */
static void
wlan_plugin_address_pretty_printer(void *cls, const char *type,
    const void *addr, size_t addrlen, int numeric,
    struct GNUNET_TIME_Relative timeout,
    GNUNET_TRANSPORT_AddressStringCallback asc, void *asc_cls)
{
  char ret[92];
  const unsigned char * input;

  //GNUNET_assert(cls !=NULL);
  if (addrlen != 6)
    {
      /* invalid address (MAC addresses have 6 bytes) */
      GNUNET_break (0);
      asc(asc_cls, NULL);
      return;
    }
  input = (const unsigned char*) addr;
  GNUNET_snprintf(ret, sizeof(ret),
      "%s Mac-Address %.2X:%.2X:%.2X:%.2X:%.2X:%.2X", PROTOCOL_PREFIX,
      input[0], input[1], input[2], input[3], input[4], input[5]);
  asc(asc_cls, ret);
}

/**
 * Another peer has suggested an address for this
 * peer and transport plugin.  Check that this could be a valid
 * address.  If so, consider adding it to the list
 * of addresses.
 *
 * @param cls closure
 * @param addr pointer to the address
 * @param addrlen length of addr
 * @return GNUNET_OK if this is a plausible address for this peer
 *         and transport
 */

static int
wlan_plugin_address_suggested(void *cls, const void *addr, size_t addrlen)
{
  //struct Plugin *plugin = cls;

  /* check if the address is plausible; if so,
   add it to our list! */

  GNUNET_assert(cls !=NULL);
  //FIXME mitm is not checked
  //Mac Address has 6 bytes
  if (addrlen == 6)
    {
      /* TODO check for bad addresses like multicast, broadcast, etc */
      return GNUNET_OK;
    }
  else
    {
      return GNUNET_SYSERR;
    }

  return GNUNET_SYSERR;
}

/**
 * Function called for a quick conversion of the binary address to
 * a numeric address.  Note that the caller must not free the 
 * address and that the next call to this function is allowed
 * to override the address again.
 *
 * @param cls closure
 * @param addr binary address
 * @param addrlen length of the address
 * @return string representing the same address 
 */
static const char*
wlan_plugin_address_to_string(void *cls, const void *addr, size_t addrlen)
{
  static char ret[40];
  const unsigned char * input;

  //GNUNET_assert(cls !=NULL);
  if (addrlen != 6)
    {
      /* invalid address (MAC addresses have 6 bytes) */
      GNUNET_break (0);
      return NULL;
    }
  input = (const unsigned char*) addr;
  GNUNET_snprintf(ret, sizeof(ret),
      "%s Mac-Address %.2X:%.2X:%.2X:%.2X:%.2X:%.2X", PROTOCOL_PREFIX,
      input[0], input[1], input[2], input[3], input[4], input[5]);
  return ret;
}

/**
 * function to check if bitfield is representation of fragments of the message
 * @param rec_message message to check
 */

void
check_message_fragment_bitfield(struct Receive_Message_Queue * rec_message)
{
  uint64_t checkfragments = 0;
  struct Receive_Fragment_Queue * rec_queue = rec_message->frag_head;

  while (rec_queue != NULL)
    {
      setBit((char*) &checkfragments, rec_queue->num);
      rec_queue = rec_queue->next;

    }
  GNUNET_assert(checkfragments == rec_message->received_fragments);
}

/**
 * Function to test if fragment number already exists in the fragments received
 *
 * @param rec_message message this fragment belongs to
 * @param fh Fragmentheader of the fragment
 * @return GNUNET_YES if fragment exists already, GNUNET_NO if it does not exists in the queue of the session
 */

static const int
is_double_msg(struct Receive_Message_Queue * rec_message,
    struct FragmentationHeader * fh)
{
  //test if bitfield is okay
#if DEBUG_wlan
  check_message_fragment_bitfield(rec_message);
#endif

  return testBit((char *) &rec_message->received_fragments, ntohs(
      fh->fragment_off_or_num));

}

/**
 * Function to insert a fragment in a queue of a message
 * @param session session the fragment belongs to
 * @param rec_queue fragment to add
 */

static void
insert_fragment_in_queue(struct Receive_Message_Queue * rec_message,
    struct Receive_Fragment_Queue * rec_queue)
{
  struct Receive_Fragment_Queue * rec_queue2 = rec_message->frag_head;
  struct WlanHeader * wlanheader = NULL;

  GNUNET_assert(rec_message != NULL);
  GNUNET_assert(rec_queue != NULL);

  //this is the first fragment of the message (fragment id 0)
  if (rec_queue->num == 0)
    {
      wlanheader = (struct WlanHeader *) rec_queue->msg;
      rec_message->rec_size = ntohs(wlanheader->header.size);
    }

  //sort into list
  while (rec_queue2 != NULL)
    {
      if (rec_queue2->num > rec_queue->num)
        {
          //next element number is grater than the current num
          GNUNET_CONTAINER_DLL_insert_before(rec_message->frag_head, rec_message->frag_tail, rec_queue2, rec_queue);
          setBit((char *) &rec_message->received_fragments, rec_queue->num);
          return;
        }
      rec_queue = rec_queue->next;
    }
  //no element has a grater number
  GNUNET_CONTAINER_DLL_insert_tail(rec_message->frag_head, rec_message->frag_tail, rec_queue);

  setBit((char *) &rec_message->received_fragments, rec_queue->num);
}

/**
 * Function to dispose the fragments received for a message and the message
 * @param session session to free the fragments from
 */

static void
free_receive_message(struct Plugin* plugin,
    struct Receive_Message_Queue * rec_message)
{
  GNUNET_assert(rec_message !=NULL);
  struct Receive_Fragment_Queue * rec_queue = rec_message->frag_head;
  struct Receive_Fragment_Queue * rec_queue2;

  while (rec_queue != NULL)
    {
      rec_queue2 = rec_queue;
      rec_queue = rec_queue->next;
      GNUNET_free(rec_queue2);
    }

  GNUNET_CONTAINER_DLL_remove(plugin->receive_messages_head,plugin->receive_messages_teil, rec_message);

  GNUNET_assert(plugin->pending_receive_messages > 0);
  GNUNET_assert(rec_message->session->fragment_messages_in_count > 0);

  plugin->pending_receive_messages--;
  rec_message->session->fragment_messages_in_count--;
  GNUNET_free(rec_message);
}

/**
 * Function to check if all fragments of a message have been received
 * @param plugin the plugin handle
 * @param session_light information of the message sender
 * @param session session the message belongs to
 */

static void
check_rec_finished_msg(struct Plugin* plugin,
    struct Session_light * session_light, struct Session * session,
    struct Receive_Message_Queue * rec_message)
{
  struct Receive_Fragment_Queue * rec_queue = rec_message->frag_head;
  int packetsize = rec_message->rec_size;
  int sum = 0;
  int aktnum = 0;
  uint64_t bitfield = 0;
  char * msg;

  GNUNET_assert(rec_message !=NULL);
  //check if first fragment is present
  if (packetsize == MESSAGE_LENGHT_UNKNOWN)
    {
      return;
    }
#if DEBUG_wlan
  check_message_fragment_bitfield(rec_message);
#endif

  bitfield = ~bitfield;
  bitfield = bitfield >> (63 - rec_message->frag_tail->num);
  if (rec_message->received_fragments == bitfield)
    {

      while (rec_queue != NULL)
        {
          sum += rec_queue->size;
          rec_queue = rec_queue->next;
        }
      //sum should always be smaller or equal of
      GNUNET_assert(sum <= packetsize);
      if (sum == packetsize)
        {

#if DEBUG_wlan
          GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
              "check_rec_finished_msg: A message for %p is complete\n", session);
#endif

          //TODO use mst
          //copy fragments together
          msg = GNUNET_malloc(packetsize);
          rec_queue = rec_message->frag_head;
          aktnum = 0;
          while (rec_queue != NULL)
            {
              //TODO SAVE SOME COPY OPS AND CHECK CRC WITHOUT COPY
              memcpy(msg + aktnum, rec_queue->msg, rec_queue->size);
              aktnum += rec_queue->size;
              rec_queue = rec_queue->next;
            }
          free_receive_message(plugin, rec_message);
          //call wlan_process_helper to process the message
          wlan_data_massage_handler(plugin, session_light,
              (struct GNUNET_MessageHeader*) msg);
          //wlan_data_helper (plugin, session_light, (struct GNUNET_MessageHeader*) msg);

          GNUNET_free(msg);
        }
    }
}

static void
process_data(void *cls, void *client, const struct GNUNET_MessageHeader *hdr)
{

  GNUNET_assert(client != NULL);
  GNUNET_assert(cls != NULL);
  struct Session * session = (struct Session *) client;
  struct Plugin * plugin = (struct Plugin *) cls;

  struct GNUNET_TRANSPORT_ATS_Information distance[2];
  distance[0].type = htonl(GNUNET_TRANSPORT_ATS_QUALITY_NET_DISTANCE);
  distance[0].value = htonl(1);
  distance[1].type = htonl(GNUNET_TRANSPORT_ATS_ARRAY_TERMINATOR);
  distance[1].value = htonl(0);

#if DEBUG_wlan
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
      "Calling plugin->env->receive for session %p; %s\n", session,
      wlan_plugin_address_to_string(NULL, session->addr, 6));
#endif

  plugin->env->receive(plugin->env->cls, &(session->target), hdr,
      (const struct GNUNET_TRANSPORT_ATS_Information *) &distance, 2, session,
      session->addr, sizeof(session->addr));
}

/**
 * handels the data after all fragments are put together
 * @param plugin
 * @param session_light
 * @param hdr pointer to the data
 */
static void
wlan_data_massage_handler(struct Plugin * plugin,
    struct Session_light * session_light,
    const struct GNUNET_MessageHeader * hdr)
{
  struct WlanHeader * wlanheader = NULL;
  struct Session * session = NULL;
  const char * tempmsg = NULL;
  const struct GNUNET_MessageHeader * temp_hdr = NULL;
  struct GNUNET_PeerIdentity tmptarget;

  if (ntohs(hdr->type) == GNUNET_MESSAGE_TYPE_WLAN_DATA)
    {

#if DEBUG_wlan
      GNUNET_log(
          GNUNET_ERROR_TYPE_DEBUG,
          "Func wlan_data_massage_handler got GNUNET_MESSAGE_TYPE_WLAN_DATA size: %u\n",
          ntohs(hdr->size));
#endif

      GNUNET_assert(session_light != NULL);
      if (session_light->session == NULL)
        {
          session_light->session = search_session(plugin, session_light->addr);
        }
      session = session_light->session;
      wlanheader = (struct WlanHeader *) hdr;
      tempmsg = (char*) &wlanheader[1];
      temp_hdr = (const struct GNUNET_MessageHeader *) &wlanheader[1];

      if (getcrc32(tempmsg, ntohs(wlanheader->header.size)) != ntohl(
          wlanheader->crc))
        {
          //wrong crc, dispose message
          GNUNET_log(GNUNET_ERROR_TYPE_INFO,
              "Wlan message Header crc was wrong\n");
          return;
        }

      //if not in session list
      if (session == NULL)
        {
#if DEBUG_wlan
          GNUNET_log(
              GNUNET_ERROR_TYPE_DEBUG,
              "WLAN client not in session list: packet size = %u, inner size = %u, header size = %u\n",
              ntohs(wlanheader->header.size), ntohs(temp_hdr->size),
              sizeof(struct WlanHeader));
#endif
          //try if it is a hello message
          if (ntohs(wlanheader->header.size) >= ntohs(temp_hdr->size)
              + sizeof(struct WlanHeader))
            {
              if (ntohs(temp_hdr->type) == GNUNET_MESSAGE_TYPE_HELLO)
                {
                  if (GNUNET_HELLO_get_id(
                      (const struct GNUNET_HELLO_Message *) temp_hdr,
                      &tmptarget) == GNUNET_OK)
                    {
                      session = create_session(plugin, session_light->addr);
                      session_light->session = session;
                      memcpy(&session->target, &tmptarget,
                          sizeof(struct GNUNET_PeerIdentity));
                    }
                  else
                    {
                      GNUNET_log(GNUNET_ERROR_TYPE_WARNING,
                          "WLAN client not in session list and hello message not okay\n");
                      return;
                    }

                }
              else
                {
                  GNUNET_log(GNUNET_ERROR_TYPE_WARNING,
                      "WLAN client not in session list and not a hello message\n");
                  return;
                }
            }
          else
            {
              GNUNET_log(
                  GNUNET_ERROR_TYPE_WARNING,
                  "WLAN client not in session list and message size in does not fit\npacket size = %u, inner size = %u, header size = %u\n",
                  ntohs(wlanheader->header.size), ntohs(temp_hdr->size),
                  sizeof(struct WlanHeader));
              return;
            }
        }

      //"receive" the message


      GNUNET_SERVER_mst_receive(plugin->data_tokenizer, session,
          (const char *) temp_hdr,
          ntohs(hdr->size) - sizeof(struct WlanHeader), GNUNET_YES, GNUNET_NO);

      return;
    }
  else
    {
      GNUNET_log(GNUNET_ERROR_TYPE_WARNING,
          "wlan_data_massage_handler got wrong message type\n");
      return;
    }
}

/**
 * function to add an ack to send it for a received fragment
 * @param plugin pointer to the global plugin structure
 * @param session pointer to the session this ack belongs to
 * @param fh pointer to the fragmentation header which we would like to acknolage
 */

void
add_ack_for_send(struct Plugin * plugin, struct Session * session,
    uint64_t bitfield, struct FragmentationHeader * fh)
{
  struct AckSendQueue * ack;

  GNUNET_assert(plugin != NULL);
  GNUNET_assert(session != NULL);
  GNUNET_assert(fh != NULL);

  ack = GNUNET_malloc(sizeof(struct AckSendQueue));
  ack->fragments_field = bitfield;
  ack->message_id = ntohl(fh->message_id);
  ack->session = session;

  GNUNET_CONTAINER_DLL_insert_tail(plugin->ack_send_queue_head,
      plugin->ack_send_queue_tail, ack);

}

/**
 * function to get the receive message from the message id and the session
 * @param plugin pointer to the plugin struct
 * @param session session this fragment belongs to
 * @param message_id id of the message
 */

struct Receive_Message_Queue *
get_receive_message(struct Plugin * plugin, struct Session * session,
    uint32_t message_id)
{
  struct Receive_Message_Queue * rec_message = plugin->receive_messages_head;
  while (rec_message != NULL)
    {
      if ((rec_message->message_id_in == message_id) && (rec_message->session
          == session))
        {
          return rec_message;
        }
      rec_message = rec_message->next;
    }
  return NULL;
}

/**
 * function to get the receive message of a session
 * @param plugin pointer to the plugin struct
 * @param session session this fragment belongs to
 */

struct Receive_Message_Queue *
get_receive_message_from_session(struct Plugin * plugin,
    struct Session * session)
{
  struct Receive_Message_Queue * rec_message = plugin->receive_messages_head;
  while (rec_message != NULL)
    {
      if (rec_message->session == session)
        {
          return rec_message;
        }
      rec_message = rec_message->next;
    }
  return NULL;
}

/**
 * function to insert a received fragment into the right fragment queue of the right message
 * @param plugin pointer to the plugin struct
 * @param session session this fragment belongs to
 * @param fh pointer to the header of the fragment
 * @return new fragment bitfield for the message
 */

uint64_t
insert_fragment_in_in_message_queue(struct Plugin * plugin,
    struct Session_light * session_light, struct Session * session,
    struct FragmentationHeader * fh)
{
  struct Receive_Fragment_Queue * rec_queue = NULL;
  struct Receive_Message_Queue * rec_message;
  const char * tempmsg = (char*) &fh[1];
  uint64_t retval = 0;

  //TODO fragments do not timeout
  //check if message_id is right or it is a new msg
  GNUNET_assert(fh != NULL);

  rec_message = get_receive_message(plugin, session, ntohs(fh->message_id));

  if (rec_message == NULL)
    {
      if (session->fragment_messages_in_count < MESSAGES_IN_QUEUE_PER_SESSION)
        {

          //new message incoming
          rec_message = GNUNET_malloc(sizeof (struct Receive_Message_Queue));
          rec_message->message_id_in = ntohs(fh->message_id);
          rec_message->rec_size = MESSAGE_LENGHT_UNKNOWN;
          rec_message->session = session;
          rec_message->timeout = GNUNET_TIME_absolute_add(
              GNUNET_TIME_absolute_get(), MESSAGE_IN_TIMEOUT);
          rec_message->received_fragments = 0;

          GNUNET_CONTAINER_DLL_insert(plugin->receive_messages_head, plugin->receive_messages_teil, rec_message);

          session->fragment_messages_in_count++;
          plugin->pending_receive_messages++;

#if DEBUG_wlan
          GNUNET_log(
              GNUNET_ERROR_TYPE_DEBUG,
              "New fragmented message started: message id %u, messages in for this session %u, messages in %u\n",
              rec_message->message_id_in, session->fragment_messages_in_count,
              plugin->pending_receive_messages);
#endif
        }
      else
        {

          GNUNET_log(
              GNUNET_ERROR_TYPE_INFO,
              "WLAN fragment message_id and session message_id do not exist, max MESSAGES_IN_QUEUE_PER_SESSION reached\n");
          setBit((char *) &retval, ntohs(fh->fragment_off_or_num));
          return retval;
        }
    }

  if (is_double_msg(rec_message, fh) != GNUNET_YES)
    {

      //report size
      rec_queue = GNUNET_malloc(sizeof (struct Receive_Fragment_Queue) +
          ntohs(fh->header.size) - sizeof(struct FragmentationHeader));
      rec_queue->size = ntohs(fh->header.size)
          - sizeof(struct FragmentationHeader);
      rec_queue->num = ntohs(fh->fragment_off_or_num);
      rec_queue->msg = (char*) &(rec_queue[1]);
      //copy msg to buffer
      memcpy(rec_queue->msg, tempmsg, rec_queue->size);
      insert_fragment_in_queue(rec_message, rec_queue);
      //save bitfield
      retval = rec_message->received_fragments;

#if DEBUG_wlan
      GNUNET_log(
          GNUNET_ERROR_TYPE_DEBUG,
          "New fragment:  size %u, fragsize %u, message id %u, bitfield %X, session %u\n",
          rec_message->rec_size, rec_queue->size,
          rec_message->received_fragments, rec_message->message_id_in, session);
#endif

      check_rec_finished_msg(plugin, session_light, session, rec_message);
    }
  else
    {
      GNUNET_log(GNUNET_ERROR_TYPE_INFO, "WLAN fragment is a clone\n");
      retval = rec_message->received_fragments;

    }
  return retval;

}

/**
 * Function used for to process the data received from the wlan interface
 *
 * @param cls the plugin handle
 * @param session_light FIXME: document
 * @param hdr hdr of the GNUNET_MessageHeader
 */
static void
wlan_data_helper(void *cls, struct Session_light * session_light,
    const struct GNUNET_MessageHeader * hdr)
{
  struct Plugin *plugin = cls;
  struct Session * session = NULL;

  struct FragmentationHeader * fh = NULL;
  struct FragmentationAckHeader * fah = NULL;
  struct FragmentMessage * fm = NULL;

  const char * tempmsg = NULL;

  uint64_t fragment_bitfield = 0;

  //ADVERTISEMENT
  if (ntohs(hdr->type) == GNUNET_MESSAGE_TYPE_WLAN_ADVERTISEMENT)
    {

      //TODO better DOS protection, error handling
      //TODO test first than create session
      GNUNET_assert(session_light != NULL);

#if DEBUG_wlan
      GNUNET_log(
          GNUNET_ERROR_TYPE_DEBUG,
          "Func wlan_data_helper got GNUNET_MESSAGE_TYPE_WLAN_ADVERTISEMENT size: %u; %s\n",
          ntohs(hdr->size), wlan_plugin_address_to_string(NULL,
              session_light->addr, 6));
#endif

      if (session_light->session == NULL)
        {
          session_light->session = get_Session(plugin, session_light->addr);
        }
      GNUNET_assert(GNUNET_HELLO_get_id(
              (const struct GNUNET_HELLO_Message *) &hdr[1],
              &(session_light->session->target) ) != GNUNET_SYSERR);

    }

  //FRAGMENT
  else if (ntohs(hdr->type) == GNUNET_MESSAGE_TYPE_WLAN_FRAGMENT)
    {

      GNUNET_assert(session_light != NULL);
      if (session_light->session == NULL)
        {
          session_light->session = search_session(plugin, session_light->addr);
        }
      session = session_light->session;

      fh = (struct FragmentationHeader *) hdr;
      tempmsg = (char*) &fh[1];

#if DEBUG_wlan
      GNUNET_log(
          GNUNET_ERROR_TYPE_DEBUG,
          "Func wlan_data_helper got GNUNET_MESSAGE_TYPE_WLAN_FRAGMENT with message_id %u with fragment number %i, size: %u; %s\n",
          ntohl(fh->message_id), ntohs(fh->fragment_off_or_num), ntohs(
              hdr->size), wlan_plugin_address_to_string(NULL,
              session_light->addr, 6));
#endif

      if (getcrc16(tempmsg, ntohs(fh->header.size)) != ntohs(fh->message_crc))
        {
          //wrong crc, dispose message
          GNUNET_log(GNUNET_ERROR_TYPE_INFO, "WLAN fragment crc was wrong\n");
          return;
        }

      //if in the session list
      if (session != NULL)
        {
          fragment_bitfield = insert_fragment_in_in_message_queue(plugin,
              session_light, session, fh);
        }
      else
        {
          // new session
          GNUNET_log(
              GNUNET_ERROR_TYPE_INFO,
              "WLAN client not in session list, fragment num %u, message id %u\n",
              ntohs(fh->fragment_off_or_num), ntohs(fh->message_id));
          wlan_data_massage_handler(plugin, session_light,
              (struct GNUNET_MessageHeader *) tempmsg);
          session = session_light->session;
          //test if a session was created
          if (session == NULL)
            {
              return;
            }
          setBit((char *) &fragment_bitfield, ntohs(fh->fragment_off_or_num));
        }

      add_ack_for_send(plugin, session, fragment_bitfield, fh);
      check_next_fragment_timeout(plugin);

    }

  //ACK
  else if (ntohs(hdr->type) == GNUNET_MESSAGE_TYPE_WLAN_FRAGMENT_ACK)
    {

#if DEBUG_wlan
      GNUNET_log(
          GNUNET_ERROR_TYPE_DEBUG,
          "Func wlan_data_helper got GNUNET_MESSAGE_TYPE_WLAN_FRAGMENT_ACK size: %u; %s\n",
          ntohs(hdr->size), wlan_plugin_address_to_string(NULL,
              session_light->addr, 6));
#endif

      GNUNET_assert(session_light != NULL);
      if (session_light->session == NULL)
        {
          session_light->session = search_session(plugin, session_light->addr);
          GNUNET_assert(session_light->session != NULL);
        }
      session = session_light->session;
      fah = (struct FragmentationAckHeader *) hdr;
      fm = get_fragment_message_from_session_and_id(session, ntohl(
          fah->message_id));
      if (fm != NULL)
        {

          fm->ack_bitfield = fm->ack_bitfield | ntohll(fah->fragment_field);
          check_finished_fragment(plugin, fm);
        }
      else
        {
          GNUNET_log(GNUNET_ERROR_TYPE_WARNING,
              "WLAN fragment not in fragment list with id %u of ack\n", ntohl(
                  fh->message_id));
          return;
        }

    }
  else
    {
      // TODO Wrong data?
      GNUNET_log(GNUNET_ERROR_TYPE_INFO,
          "WLAN packet inside the WLAN helper packet has not the right type\n");
      return;
    }

#if 0
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
      "Helper finished\n");
#endif

}

char *
macprinter(struct MacAddress macx)
{
  static char macstr[20];
  char * mac = macx.mac;
  sprintf(macstr, "%.2X:%.2X:%.2X:%.2X:%.2X:%.2X", mac[0], mac[1], mac[2],
      mac[3], mac[4], mac[5]);
  return macstr;
}

/**
 * Function used for to process the data from the suid process
 *
 * @param cls the plugin handle
 * @param client client that send the data (not used)
 * @param hdr header of the GNUNET_MessageHeader
 */

static void
wlan_process_helper(void *cls, void *client,
    const struct GNUNET_MessageHeader *hdr)
{
  struct Plugin *plugin = cls;
  struct IeeeHeader * wlanIeeeHeader = NULL;
  struct Session_light * session_light = NULL;
  const struct GNUNET_MessageHeader * temp_hdr = NULL;

  int datasize = 0;
  int pos = 0;

  if (ntohs(hdr->type) == GNUNET_MESSAGE_TYPE_WLAN_HELPER_DATA)
    {
#if DEBUG_wlan
      GNUNET_log(
          GNUNET_ERROR_TYPE_DEBUG,
          "Func wlan_process_helper got  GNUNET_MESSAGE_TYPE_WLAN_HELPER_DATA size: %u\n",
          ntohs(hdr->size));
#endif

      //call wlan_process_helper with the message inside, later with wlan: analyze signal
      GNUNET_assert(ntohs(hdr->size) >= sizeof(struct IeeeHeader) + sizeof(struct GNUNET_MessageHeader));
      wlanIeeeHeader = (struct IeeeHeader *) &hdr[1];

      //process only if it is an broadcast or for this computer both with the gnunet bssid

      //check for bssid
      if (memcmp(&(wlanIeeeHeader->mac2), macbc, sizeof(struct MacAddress))
          == 0)
        {
          //check for broadcast or mac
          if (memcmp(&(wlanIeeeHeader->mac1), bc_all_mac,
              sizeof(struct MacAddress) == 0) || memcmp(
              &(wlanIeeeHeader->mac1), &(plugin->mac_address),
              sizeof(struct MacAddress)) == 0)
            {

              // process the inner data


              datasize = ntohs(hdr->size) - sizeof(struct IeeeHeader)
                  - sizeof(struct GNUNET_MessageHeader);

              session_light = GNUNET_malloc(sizeof(struct Session_light));
              memcpy(session_light->addr, &(wlanIeeeHeader->mac3),
                  sizeof(struct MacAddress));
              //session_light->session = search_session(plugin,session_light->addr);

              pos = 0;
              temp_hdr = (struct GNUNET_MessageHeader *) &wlanIeeeHeader[1];
              while (pos < datasize)
                {
                  temp_hdr = (struct GNUNET_MessageHeader *) &wlanIeeeHeader[1]
                      + pos;

                  wlan_data_helper(plugin, session_light, temp_hdr);
                  pos += ntohs(temp_hdr->size);

                }

              //clean up
              GNUNET_free(session_light);
            }
          else
            {
#if DEBUG_wlan
              GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
                  "Func wlan_process_helper got wrong MAC: %s\n", macprinter(
                      wlanIeeeHeader->mac1));
#endif
            }
        }
      else
        {
#if DEBUG_wlan
          GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
              "Func wlan_process_helper got wrong BSSID: %s\n", macprinter(
                  wlanIeeeHeader->mac2));
#endif
        }

    }

  else if (ntohs(hdr->type) == GNUNET_MESSAGE_TYPE_WLAN_HELPER_CONTROL)
    {

#if DEBUG_wlan
      GNUNET_log(
          GNUNET_ERROR_TYPE_DEBUG,
          "Func wlan_process_helper got  GNUNET_MESSAGE_TYPE_WLAN_HELPER_CONTROL size: %u\n",
          ntohs(hdr->size));
#endif

      //TODO more control messages
      //TODO use struct wlan_helper_control
      if (ntohs(hdr->size) == sizeof(struct Wlan_Helper_Control_Message))
        {
          //plugin->mac_address = GNUNET_malloc(sizeof(struct MacAddress));
          memcpy(&(plugin->mac_address), &hdr[1], sizeof(struct MacAddress));
          GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
              "Notifying transport of address %s\n",
              wlan_plugin_address_to_string(cls, &(plugin->mac_address), ntohs(
                  hdr->size) - sizeof(struct GNUNET_MessageHeader)));
          plugin->env->notify_address(plugin->env->cls, "wlan",
              &plugin->mac_address, sizeof(struct MacAddress),
              GNUNET_TIME_UNIT_FOREVER_REL);
        }
      else
        {
          GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Wrong wlan mac address %s\n",
              macprinter(plugin->mac_address));
        }

    }

  else
    {
      // TODO Wrong data?
      GNUNET_log(GNUNET_ERROR_TYPE_INFO,
          "WLAN helper packet has not the right type\n");
      return;
    }
}

/**
 * We have been notified that wlan-helper has written something to stdout.
 * Handle the output, then reschedule this function to be called again once
 * more is available.
 *
 * @param cls the plugin handle
 * @param tc the scheduling context
 */

static void
wlan_plugin_helper_read(void *cls,
    const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct Plugin *plugin = cls;
  plugin->server_read_task = GNUNET_SCHEDULER_NO_TASK;

  /*
   #if DEBUG_wlan
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
   "Start reading from STDIN\n");
   #endif
   */
  if (tc->reason == GNUNET_SCHEDULER_REASON_SHUTDOWN)
    return;

  char mybuf[WLAN_MTU + sizeof(struct GNUNET_MessageHeader)];
  ssize_t bytes;

  bytes = GNUNET_DISK_file_read(plugin->server_stdout_handle, mybuf,
      sizeof(mybuf));
  if (bytes <= 0)
    {
#if DEBUG_wlan
      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
          _("Finished reading from wlan-helper stdout with code: %d\n"),
          bytes);
#endif
      return;
    }
  GNUNET_SERVER_mst_receive(plugin->suid_tokenizer, NULL, mybuf, bytes,
      GNUNET_NO, GNUNET_NO);

  GNUNET_assert(plugin->server_read_task == GNUNET_SCHEDULER_NO_TASK);
  plugin->server_read_task = GNUNET_SCHEDULER_add_read_file(
      GNUNET_TIME_UNIT_FOREVER_REL, plugin->server_stdout_handle,
      &wlan_plugin_helper_read, plugin);
}

/**
 * Start the gnunet-wlan-helper process.
 *
 * @param plugin the transport plugin
 * @param testmode should we use the dummy driver for testing?
 * @return GNUNET_YES if process was started, GNUNET_SYSERR on error
 */
static int
wlan_transport_start_wlan_helper(struct Plugin *plugin, int testmode)
{
  const char * filename = "gnunet-transport-wlan-helper";
  plugin->server_stdout = GNUNET_DISK_pipe(GNUNET_YES, GNUNET_NO, GNUNET_YES);
  if (plugin->server_stdout == NULL)
    return GNUNET_SYSERR;

  plugin->server_stdin = GNUNET_DISK_pipe(GNUNET_YES, GNUNET_YES, GNUNET_NO);
  if (plugin->server_stdin == NULL)
    return GNUNET_SYSERR;

#if DEBUG_wlan
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
      "Starting gnunet-wlan-helper process cmd: %s %s %i\n", filename,
      plugin->interface, testmode);
#endif
  /* Start the server process */

  plugin->server_proc = GNUNET_OS_start_process(plugin->server_stdin,
      plugin->server_stdout, filename, filename, plugin->interface, ((testmode
          == 1) ? "1" : (testmode == 2) ? "2" : "0"), NULL);
  if (plugin->server_proc == NULL)
    {
#if DEBUG_wlan
      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
          "Failed to start gnunet-wlan-helper process\n");
#endif
      return GNUNET_SYSERR;
    }

  /* Close the write end of the read pipe */
  GNUNET_DISK_pipe_close_end(plugin->server_stdout, GNUNET_DISK_PIPE_END_WRITE);

  /* Close the read end of the write pipe */
  GNUNET_DISK_pipe_close_end(plugin->server_stdin, GNUNET_DISK_PIPE_END_READ);

  plugin->server_stdout_handle = GNUNET_DISK_pipe_handle(plugin->server_stdout,
      GNUNET_DISK_PIPE_END_READ);
  plugin->server_stdin_handle = GNUNET_DISK_pipe_handle(plugin->server_stdin,
      GNUNET_DISK_PIPE_END_WRITE);

  GNUNET_assert(plugin->server_read_task == GNUNET_SCHEDULER_NO_TASK);

#if DEBUG_wlan
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
      "Adding server_read_task for the wlan-helper\n");
#endif

  sleep(2);

  plugin->server_read_task = GNUNET_SCHEDULER_add_read_file(
      GNUNET_TIME_UNIT_FOREVER_REL, plugin->server_stdout_handle,
      &wlan_plugin_helper_read, plugin);

  return GNUNET_YES;
}

/**
 * Exit point from the plugin.
 * @param cls pointer to the api struct
 */

//FIXME cleanup
void *
libgnunet_plugin_transport_wlan_done(void *cls)
{
  struct GNUNET_TRANSPORT_PluginFunctions *api = cls;
  struct Plugin *plugin = api->cls;

#if DEBUG_wlan
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
      "libgnunet_plugin_transport_wlan_done started\n");
#endif

  GNUNET_assert(cls !=NULL);

  if (plugin->suid_tokenizer != NULL)
    GNUNET_SERVER_mst_destroy(plugin->suid_tokenizer);

  if (plugin->data_tokenizer != NULL)
    GNUNET_SERVER_mst_destroy(plugin->data_tokenizer);

  GNUNET_free_non_null(plugin->interface);
  GNUNET_free (plugin);
  GNUNET_free (api);
  return NULL;
}

/**
 * Entry point for the plugin.
 *
 * @param cls closure, the 'struct GNUNET_TRANSPORT_PluginEnvironment*'
 * @return the 'struct GNUNET_TRANSPORT_PluginFunctions*' or NULL on error
 */
void *
libgnunet_plugin_transport_wlan_init(void *cls)
{
  //struct GNUNET_SERVICE_Context *service;
  struct GNUNET_TRANSPORT_PluginEnvironment *env = cls;
  struct GNUNET_TRANSPORT_PluginFunctions *api;
  struct Plugin *plugin;
  static unsigned long long testmode = 0;

  GNUNET_assert(cls !=NULL);

  plugin = GNUNET_malloc (sizeof (struct Plugin));
  plugin->env = env;
  plugin->pendingsessions = 0;
  plugin->session_count = 0;
  plugin->server_write_task = GNUNET_SCHEDULER_NO_TASK;
  plugin->server_read_task = GNUNET_SCHEDULER_NO_TASK;
  plugin->server_write_delay_task = GNUNET_SCHEDULER_NO_TASK;

  set_next_beacon_time(plugin);

  if (GNUNET_CONFIGURATION_have_value(env->cfg, "transport-wlan", "TESTMODE"))
    {
      if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_number(env->cfg,
          "transport-wlan", "TESTMODE", &testmode))
        return NULL;
    }

  if (GNUNET_CONFIGURATION_have_value(env->cfg, "transport-wlan", "INTERFACE"))
    {
      if (GNUNET_CONFIGURATION_get_value_string(env->cfg, "transport-wlan",
          "INTERFACE", &(plugin->interface)) != GNUNET_YES)
        {
          libgnunet_plugin_transport_wlan_done(plugin);
          return NULL;
        }
    }

  wlan_transport_start_wlan_helper(plugin, testmode);
  plugin->suid_tokenizer = GNUNET_SERVER_mst_create(&wlan_process_helper,
      plugin);

  plugin->data_tokenizer = GNUNET_SERVER_mst_create(&process_data, plugin);

  //plugin->sessions = GNUNET_malloc (sizeof (struct Sessionqueue));
  //plugin->pending_Sessions = GNUNET_malloc (sizeof (struct Sessionqueue));

  api = GNUNET_malloc (sizeof (struct GNUNET_TRANSPORT_PluginFunctions));
  api->cls = plugin;
  api->send = &wlan_plugin_send;
  api->disconnect = &wlan_plugin_disconnect;
  api->address_pretty_printer = &wlan_plugin_address_pretty_printer;
  api->check_address = &wlan_plugin_address_suggested;
  api->address_to_string = &wlan_plugin_address_to_string;

  start_next_message_id();

#if DEBUG_wlan
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "wlan init finished\n");
#endif

  return api;
}

/* end of plugin_transport_wlan.c */