gnunet/src/testbed/gnunet-service-testbed_barriers.c

/*
  This file is part of GNUnet.
  Copyright (C) 2008--2016 GNUnet e.V.

  GNUnet is free software: you can redistribute it and/or modify it
  under the terms of the GNU Affero General Public License as published
  by the Free Software Foundation, either version 3 of the License,
  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
  Affero General Public License for more details.
 
  You should have received a copy of the GNU Affero General Public License
  along with this program.  If not, see <http://www.gnu.org/licenses/>.

     SPDX-License-Identifier: AGPL3.0-or-later
*/

/**
 * @file testbed/gnunet-service-testbed_barriers.c
 * @brief barrier handling at the testbed controller
 * @author Sree Harsha Totakura <sreeharsha@totakura.in>
 */

#include "gnunet-service-testbed.h"
#include "gnunet-service-testbed_barriers.h"
#include "testbed_api.h"


/**
 * timeout for outgoing message transmissions in seconds
 */
#define MESSAGE_SEND_TIMEOUT(s) \
  GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, s)


/**
 * Test to see if local peers have reached the required quorum of a barrier
 */
#define LOCAL_QUORUM_REACHED(barrier)           \
  ((barrier->quorum * GST_num_local_peers) <= (barrier->nreached * 100))


#ifdef LOG
#undef LOG
#endif

/**
 * Logging shorthand
 */
#define LOG(kind,...)                                           \
  GNUNET_log_from (kind, "testbed-barriers", __VA_ARGS__)


/**
 * Barrier
 */
struct Barrier;


/**
 * Context to be associated with each client
 */
struct ClientCtx
{
  /**
   * The barrier this client is waiting for
   */
  struct Barrier *barrier;

  /**
   * DLL next ptr
   */
  struct ClientCtx *next;

  /**
   * DLL prev ptr
   */
  struct ClientCtx *prev;

  /**
   * The client handle
   */
  struct GNUNET_SERVICE_Client *client;

};


/**
 * Wrapper around Barrier handle
 */
struct WBarrier
{
  /**
   * DLL next pointer
   */
  struct WBarrier *next;

  /**
   * DLL prev pointer
   */
  struct WBarrier *prev;

  /**
   * The local barrier associated with the creation of this wrapper
   */
  struct Barrier *barrier;

  /**
   * Handle to the slave controller where this wrapper creates a barrier
   */
  struct GNUNET_TESTBED_Controller *controller;

  /**
   * The barrier handle from API
   */
  struct GNUNET_TESTBED_Barrier *hbarrier;

  /**
   * Has this barrier been crossed?
   */
  uint8_t reached;
};


/**
 * Barrier
 */
struct Barrier
{
  /**
   * The hashcode of the barrier name
   */
  struct GNUNET_HashCode hash;

  /**
   * The client handle to the master controller
   */
  struct GNUNET_SERVICE_Client *mc;

  /**
   * The name of the barrier
   */
  char *name;

  /**
   * DLL head for the list of clients waiting for this barrier
   */
  struct ClientCtx *head;

  /**
   * DLL tail for the list of clients waiting for this barrier
   */
  struct ClientCtx *tail;

  /**
   * DLL head for the list of barrier handles
   */
  struct WBarrier *whead;

  /**
   * DLL tail for the list of barrier handles
   */
  struct WBarrier *wtail;

  /**
   * Identifier for the timeout task
   */
  struct GNUNET_SCHEDULER_Task *tout_task;

  /**
   * The status of this barrier
   */
  enum GNUNET_TESTBED_BarrierStatus status;

  /**
   * Number of barriers wrapped in the above DLL
   */
  unsigned int num_wbarriers;

  /**
   * Number of wrapped barriers reached so far
   */
  unsigned int num_wbarriers_reached;

  /**
   * Number of wrapped barrier initialised so far
   */
  unsigned int num_wbarriers_inited;

  /**
   * Number of peers which have reached this barrier
   */
  unsigned int nreached;

  /**
   * Number of slaves we have initialised this barrier
   */
  unsigned int nslaves;

  /**
   * Quorum percentage to be reached
   */
  uint8_t quorum;

};


/**
 * Hashtable handle for storing initialised barriers
 */
static struct GNUNET_CONTAINER_MultiHashMap *barrier_map;

/**
 * Service context
 */
static struct GNUNET_SERVICE_Handle *ctx;


/**
 * Function to remove a barrier from the barrier map and cleanup resources
 * occupied by a barrier
 *
 * @param barrier the barrier handle
 */
static void
remove_barrier (struct Barrier *barrier)
{
  struct ClientCtx *ctx;

  GNUNET_assert (GNUNET_YES ==
                 GNUNET_CONTAINER_multihashmap_remove (barrier_map,
                                                       &barrier->hash,
                                                       barrier));
  while (NULL != (ctx = barrier->head))
  {
    GNUNET_CONTAINER_DLL_remove (barrier->head,
                                 barrier->tail,
                                 ctx);
    ctx->barrier = NULL;
  }
  GNUNET_free (barrier->name);
  GNUNET_free (barrier);
}


/**
 * Cancels all subcontroller barrier handles
 *
 * @param barrier the local barrier
 */
static void
cancel_wrappers (struct Barrier *barrier)
{
  struct WBarrier *wrapper;

  while (NULL != (wrapper = barrier->whead))
  {
    GNUNET_TESTBED_barrier_cancel (wrapper->hbarrier);
    GNUNET_CONTAINER_DLL_remove (barrier->whead,
                                 barrier->wtail,
                                 wrapper);
    GNUNET_free (wrapper);
  }
}


/**
 * Send a status message about a barrier to the given client
 *
 * @param client the client to send the message to
 * @param name the barrier name
 * @param status the status of the barrier
 * @param emsg the error message; should be non-NULL for
 *   status=GNUNET_TESTBED_BARRIERSTATUS_ERROR
 */
static void
send_client_status_msg (struct GNUNET_SERVICE_Client *client,
                        const char *name,
                        enum GNUNET_TESTBED_BarrierStatus status,
                        const char *emsg)
{
  struct GNUNET_MQ_Envelope *env;
  struct GNUNET_TESTBED_BarrierStatusMsg *msg;
  size_t name_len;
  size_t err_len;

  GNUNET_assert ( (NULL == emsg) ||
                  (GNUNET_TESTBED_BARRIERSTATUS_ERROR == status) );
  name_len = strlen (name) + 1;
  err_len = ((NULL == emsg) ? 0 : (strlen (emsg) + 1));
  env = GNUNET_MQ_msg_extra (msg,
                             name_len + err_len,
                             GNUNET_MESSAGE_TYPE_TESTBED_BARRIER_STATUS);
  msg->status = htons (status);
  msg->name_len = htons ((uint16_t) name_len - 1);
  GNUNET_memcpy (msg->data,
                 name,
                 name_len);
  GNUNET_memcpy (msg->data + name_len,
                 emsg,
                 err_len);
  GNUNET_MQ_send (GNUNET_SERVICE_client_get_mq (client),
                  env);
}


/**
 * Sends a barrier failed message
 *
 * @param barrier the corresponding barrier
 * @param emsg the error message; should be non-NULL for
 *   status=GNUNET_TESTBED_BARRIERSTATUS_ERROR
 */
static void
send_barrier_status_msg (struct Barrier *barrier,
                         const char *emsg)
{
  GNUNET_assert (0 != barrier->status);
  send_client_status_msg (barrier->mc,
                          barrier->name,
                          barrier->status,
                          emsg);
}


/**
 * Check #GNUNET_MESSAGE_TYPE_TESTBED_BARRIER_WAIT messages.
 *
 * @param cls identification of the client
 * @param message the actual message
 */
static int
check_barrier_wait (void *cls,
                     const struct GNUNET_TESTBED_BarrierWait *msg)
{
  return GNUNET_OK; /* always well-formed */
}


/**
 * Message handler for #GNUNET_MESSAGE_TYPE_TESTBED_BARRIER_WAIT messages.  This
 * message should come from peers or a shared helper service using the
 * testbed-barrier client API (@see gnunet_testbed_barrier_service.h)
 *
 * This handler is queued in the main service and will handle the messages sent
 * either from the testbed driver or from a high level controller
 *
 * @param cls identification of the client
 * @param message the actual message
 */
static void
handle_barrier_wait (void *cls,
                     const struct GNUNET_TESTBED_BarrierWait *msg)
{
  struct ClientCtx *client_ctx = cls;
  struct Barrier *barrier;
  char *name;
  struct GNUNET_HashCode key;
  size_t name_len;
  uint16_t msize;

  msize = ntohs (msg->header.size);
  if (NULL == barrier_map)
  {
    GNUNET_break (0);
    GNUNET_SERVICE_client_drop (client_ctx->client);
    return;
  }
  name_len = msize - sizeof (struct GNUNET_TESTBED_BarrierWait);
  name = GNUNET_malloc (name_len + 1);
  name[name_len] = '\0';
  GNUNET_memcpy (name,
                 msg->name,
                 name_len);
  LOG_DEBUG ("Received BARRIER_WAIT for barrier `%s'\n",
             name);
  GNUNET_CRYPTO_hash (name,
                      name_len,
                      &key);
  GNUNET_free (name);
  if (NULL == (barrier = GNUNET_CONTAINER_multihashmap_get (barrier_map, &key)))
  {
    GNUNET_break (0);
    GNUNET_SERVICE_client_drop (client_ctx->client);
    return;
  }
  if (NULL != client_ctx->barrier)
  {
    GNUNET_break (0);
    GNUNET_SERVICE_client_drop (client_ctx->client);
    return;
  }
  client_ctx->barrier = barrier;
  GNUNET_CONTAINER_DLL_insert_tail (barrier->head,
                                    barrier->tail,
                                    client_ctx);
  barrier->nreached++;
  if ( (barrier->num_wbarriers_reached == barrier->num_wbarriers) &&
       (LOCAL_QUORUM_REACHED (barrier)) )
  {
    barrier->status = GNUNET_TESTBED_BARRIERSTATUS_CROSSED;
    send_barrier_status_msg (barrier,
                             NULL);
  }
  GNUNET_SERVICE_client_continue (client_ctx->client);
}


/**
 * Function called when a client connects to the testbed-barrier service.
 *
 * @param cls NULL
 * @param client the connecting client
 * @param mq queue to talk to @a client
 * @return our `struct ClientCtx`
 */
static void *
connect_cb (void *cls,
            struct GNUNET_SERVICE_Client *client,
            struct GNUNET_MQ_Handle *mq)
{
  struct ClientCtx *client_ctx;

  LOG_DEBUG ("Client connected to testbed-barrier service\n");
  client_ctx = GNUNET_new (struct ClientCtx);
  client_ctx->client = client;
  return client_ctx;
}


/**
 * Functions with this signature are called whenever a client
 * is disconnected on the network level.
 *
 * @param cls closure
 * @param client identification of the client; NULL
 *        for the last call when the server is destroyed
 */
static void
disconnect_cb (void *cls,
               struct GNUNET_SERVICE_Client *client,
               void *app_ctx)
{
  struct ClientCtx *client_ctx = app_ctx;
  struct Barrier *barrier = client_ctx->barrier;

  if (NULL != barrier)
  {
    GNUNET_CONTAINER_DLL_remove (barrier->head,
                                 barrier->tail,
                                 client_ctx);
    client_ctx->barrier = NULL;
  }
  GNUNET_free (client_ctx);
  LOG_DEBUG ("Client disconnected from testbed-barrier service\n");
}


/**
 * Function to initialise barrriers component
 *
 * @param cfg the configuration to use for initialisation
 */
void
GST_barriers_init (struct GNUNET_CONFIGURATION_Handle *cfg)
{
  struct GNUNET_MQ_MessageHandler message_handlers[] = {
    GNUNET_MQ_hd_var_size (barrier_wait,
                           GNUNET_MESSAGE_TYPE_TESTBED_BARRIER_WAIT,
                           struct GNUNET_TESTBED_BarrierWait,
                           NULL),
    GNUNET_MQ_handler_end ()
  };

  LOG_DEBUG ("Launching testbed-barrier service\n");
  barrier_map = GNUNET_CONTAINER_multihashmap_create (3,
                                                      GNUNET_YES);
  ctx = GNUNET_SERVICE_start ("testbed-barrier",
                              cfg,
                              &connect_cb,
                              &disconnect_cb,
                              NULL,
                              message_handlers);
}


/**
 * Iterator over hash map entries.
 *
 * @param cls closure
 * @param key current key code
 * @param value value in the hash map
 * @return #GNUNET_YES if we should continue to
 *         iterate,
 *         #GNUNET_NO if not.
 */
static int
barrier_destroy_iterator (void *cls,
                          const struct GNUNET_HashCode *key,
                          void *value)
{
  struct Barrier *barrier = value;

  GNUNET_assert (NULL != barrier);
  cancel_wrappers (barrier);
  remove_barrier (barrier);
  return GNUNET_YES;
}


/**
 * Function to stop the barrier service
 */
void
GST_barriers_destroy ()
{
  GNUNET_assert (NULL != barrier_map);
  GNUNET_assert (GNUNET_SYSERR !=
                 GNUNET_CONTAINER_multihashmap_iterate (barrier_map,
                                                        &barrier_destroy_iterator,
                                                        NULL));
  GNUNET_CONTAINER_multihashmap_destroy (barrier_map);
  GNUNET_assert (NULL != ctx);
  GNUNET_SERVICE_stop (ctx);
}


/**
 * Functions of this type are to be given as callback argument to
 * GNUNET_TESTBED_barrier_init().  The callback will be called when status
 * information is available for the barrier.
 *
 * @param cls the closure given to GNUNET_TESTBED_barrier_init()
 * @param name the name of the barrier
 * @param b_ the barrier handle
 * @param status status of the barrier; #GNUNET_OK if the barrier is crossed;
 *   #GNUNET_SYSERR upon error
 * @param emsg if the status were to be #GNUNET_SYSERR, this parameter has the
 *   error messsage
 */
static void
wbarrier_status_cb (void *cls,
                    const char *name,
                    struct GNUNET_TESTBED_Barrier *b_,
                    enum GNUNET_TESTBED_BarrierStatus status,
                    const char *emsg)
{
  struct WBarrier *wrapper = cls;
  struct Barrier *barrier = wrapper->barrier;

  GNUNET_assert (b_ == wrapper->hbarrier);
  switch (status)
  {
  case GNUNET_TESTBED_BARRIERSTATUS_ERROR:
    LOG (GNUNET_ERROR_TYPE_ERROR,
         "Initialising barrier `%s' failed at a sub-controller: %s\n",
         barrier->name,
         (NULL != emsg) ? emsg : "NULL");
    cancel_wrappers (barrier);
    if (NULL == emsg)
      emsg = "Initialisation failed at a sub-controller";
    barrier->status = GNUNET_TESTBED_BARRIERSTATUS_ERROR;
    send_barrier_status_msg (barrier, emsg);
    return;
  case GNUNET_TESTBED_BARRIERSTATUS_CROSSED:
    if (GNUNET_TESTBED_BARRIERSTATUS_INITIALISED != barrier->status)
    {
      GNUNET_break_op (0);
      return;
    }
    barrier->num_wbarriers_reached++;
    if ((barrier->num_wbarriers_reached == barrier->num_wbarriers)
        && (LOCAL_QUORUM_REACHED (barrier)))
    {
      barrier->status = GNUNET_TESTBED_BARRIERSTATUS_CROSSED;
      send_barrier_status_msg (barrier, NULL);
    }
    return;
  case GNUNET_TESTBED_BARRIERSTATUS_INITIALISED:
    if (0 != barrier->status)
    {
      GNUNET_break_op (0);
      return;
    }
    barrier->num_wbarriers_inited++;
    if (barrier->num_wbarriers_inited == barrier->num_wbarriers)
    {
      barrier->status = GNUNET_TESTBED_BARRIERSTATUS_INITIALISED;
      send_barrier_status_msg (barrier, NULL);
    }
    return;
  }
}


/**
 * Function called upon timeout while waiting for a response from the
 * subcontrollers to barrier init message
 *
 * @param cls barrier
 */
static void
fwd_tout_barrier_init (void *cls)
{
  struct Barrier *barrier = cls;

  cancel_wrappers (barrier);
  barrier->status = GNUNET_TESTBED_BARRIERSTATUS_ERROR;
  send_barrier_status_msg (barrier,
                           "Timedout while propagating barrier initialisation\n");
  remove_barrier (barrier);
}



/**
 * Check #GNUNET_MESSAGE_TYPE_TESTBED_BARRIER_INIT messages.
 *
 * @param cls identification of the client
 * @param msg the actual message
 * @return #GNUNET_OK if @a msg is well-formed
 */
int
check_barrier_init (void *cls,
                    const struct GNUNET_TESTBED_BarrierInit *msg)
{
  return GNUNET_OK; /* always well-formed */
}


/**
 * Message handler for #GNUNET_MESSAGE_TYPE_TESTBED_BARRIER_INIT messages.  This
 * message should always come from a parent controller or the testbed API if we
 * are the root controller.
 *
 * This handler is queued in the main service and will handle the messages sent
 * either from the testbed driver or from a high level controller
 *
 * @param cls identification of the client
 * @param msg the actual message
 */
void
handle_barrier_init (void *cls,
                     const struct GNUNET_TESTBED_BarrierInit *msg)
{
  struct GNUNET_SERVICE_Client *client = cls;
  char *name;
  struct Barrier *barrier;
  struct Slave *slave;
  struct WBarrier *wrapper;
  struct GNUNET_HashCode hash;
  size_t name_len;
  unsigned int cnt;
  uint16_t msize;

  if (NULL == GST_context)
  {
    GNUNET_break_op (0);
    GNUNET_SERVICE_client_drop (client);
    return;
  }
  if (client != GST_context->client)
  {
    GNUNET_break_op (0);
    GNUNET_SERVICE_client_drop (client);
    return;
  }
  msize = ntohs (msg->header.size);
  name_len = (size_t) msize - sizeof (struct GNUNET_TESTBED_BarrierInit);
  name = GNUNET_malloc (name_len + 1);
  GNUNET_memcpy (name, msg->name, name_len);
  GNUNET_CRYPTO_hash (name, name_len, &hash);
  LOG_DEBUG ("Received BARRIER_INIT for barrier `%s'\n",
             name);
  if (GNUNET_YES ==
      GNUNET_CONTAINER_multihashmap_contains (barrier_map,
                                              &hash))
  {
    send_client_status_msg (client,
                            name,
                            GNUNET_TESTBED_BARRIERSTATUS_ERROR,
                            "A barrier with the same name already exists");
    GNUNET_free (name);
    GNUNET_SERVICE_client_continue (client);
    return;
  }
  barrier = GNUNET_new (struct Barrier);
  barrier->hash = hash;
  barrier->quorum = msg->quorum;
  barrier->name = name;
  barrier->mc = client;
  GNUNET_assert (GNUNET_OK ==
                 GNUNET_CONTAINER_multihashmap_put (barrier_map,
                                                    &barrier->hash,
                                                    barrier,
                                                    GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST));
  GNUNET_SERVICE_client_continue (client);
  /* Propagate barrier init to subcontrollers */
  for (cnt = 0; cnt < GST_slave_list_size; cnt++)
  {
    if (NULL == (slave = GST_slave_list[cnt]))
      continue;
    if (NULL == slave->controller)
    {
      GNUNET_break (0);/* May happen when we are connecting to the controller */
      continue;
    }
    wrapper = GNUNET_new (struct WBarrier);
    wrapper->barrier = barrier;
    wrapper->controller = slave->controller;
    GNUNET_CONTAINER_DLL_insert_tail (barrier->whead,
                                      barrier->wtail,
                                      wrapper);
    barrier->num_wbarriers++;
    wrapper->hbarrier = GNUNET_TESTBED_barrier_init_ (wrapper->controller,
                                                      barrier->name,
                                                      barrier->quorum,
                                                      &wbarrier_status_cb,
                                                      wrapper,
                                                      GNUNET_NO);
  }
  if (NULL == barrier->whead)   /* No further propagation */
  {
    barrier->status = GNUNET_TESTBED_BARRIERSTATUS_INITIALISED;
    LOG_DEBUG ("Sending GNUNET_TESTBED_BARRIERSTATUS_INITIALISED for barrier `%s'\n",
               barrier->name);
    send_barrier_status_msg (barrier, NULL);
  }else
    barrier->tout_task = GNUNET_SCHEDULER_add_delayed (MESSAGE_SEND_TIMEOUT (30),
                                                       &fwd_tout_barrier_init,
                                                       barrier);
}


/**
 * Check #GNUNET_MESSAGE_TYPE_TESTBED_BARRIER_CANCEL messages.
 *
 * @param cls identification of the client
 * @param msg the actual message
 * @return #GNUNET_OK if @a msg is well-formed
 */
int
check_barrier_cancel (void *cls,
                      const struct GNUNET_TESTBED_BarrierCancel *msg)
{
  return GNUNET_OK; /* all are well-formed */
}


/**
 * Message handler for #GNUNET_MESSAGE_TYPE_TESTBED_BARRIER_CANCEL messages.  This
 * message should always come from a parent controller or the testbed API if we
 * are the root controller.
 *
 * This handler is queued in the main service and will handle the messages sent
 * either from the testbed driver or from a high level controller
 *
 * @param cls identification of the client
 * @param msg the actual message
 */
void
handle_barrier_cancel (void *cls,
                       const struct GNUNET_TESTBED_BarrierCancel *msg)
{
  struct GNUNET_SERVICE_Client *client = cls;
  char *name;
  struct Barrier *barrier;
  struct GNUNET_HashCode hash;
  size_t name_len;
  uint16_t msize;

  if (NULL == GST_context)
  {
    GNUNET_break_op (0);
    GNUNET_SERVICE_client_drop (client);
    return;
  }
  if (client != GST_context->client)
  {
    GNUNET_break_op (0);
    GNUNET_SERVICE_client_drop (client);
    return;
  }
  msize = ntohs (msg->header.size);
  name_len = msize - sizeof (struct GNUNET_TESTBED_BarrierCancel);
  name = GNUNET_malloc (name_len + 1);
  GNUNET_memcpy (name,
                 msg->name,
                 name_len);
  LOG_DEBUG ("Received BARRIER_CANCEL for barrier `%s'\n",
             name);
  GNUNET_CRYPTO_hash (name,
                      name_len,
                      &hash);
  if (GNUNET_NO ==
      GNUNET_CONTAINER_multihashmap_contains (barrier_map,
                                              &hash))
  {
    GNUNET_break_op (0);
    GNUNET_SERVICE_client_drop (client);
    return;
  }
  barrier = GNUNET_CONTAINER_multihashmap_get (barrier_map,
                                               &hash);
  GNUNET_assert (NULL != barrier);
  cancel_wrappers (barrier);
  remove_barrier (barrier);
  GNUNET_SERVICE_client_continue (client);
}


/**
 * Check #GNUNET_MESSAGE_TYPE_TESTBED_BARRIER_STATUS messages.
 *
 * @param cls identification of the client
 * @param msg the actual message
 * @return #GNUNET_OK if @a msg is well-formed
 */
int
check_barrier_status (void *cls,
                      const struct GNUNET_TESTBED_BarrierStatusMsg *msg)
{
  uint16_t msize;
  uint16_t name_len;
  const char *name;
  enum GNUNET_TESTBED_BarrierStatus status;

  msize = ntohs (msg->header.size) - sizeof (*msg);
  status = ntohs (msg->status);
  if (GNUNET_TESTBED_BARRIERSTATUS_CROSSED != status)
  {
    GNUNET_break_op (0);        /* current we only expect BARRIER_CROSSED
                                   status message this way */
    return GNUNET_SYSERR;
  }
  name = msg->data;
  name_len = ntohs (msg->name_len);
  if ((name_len + 1) != msize)
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  if ('\0' != name[name_len])
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  return GNUNET_OK;
}


/**
 * Message handler for #GNUNET_MESSAGE_TYPE_TESTBED_BARRIER_STATUS messages.
 * This handler is queued in the main service and will handle the messages sent
 * either from the testbed driver or from a high level controller
 *
 * @param cls identification of the client
 * @param msg the actual message
 */
void
handle_barrier_status (void *cls,
                       const struct GNUNET_TESTBED_BarrierStatusMsg *msg)
{
  struct GNUNET_SERVICE_Client *client = cls;
  struct Barrier *barrier;
  struct ClientCtx *client_ctx;
  struct WBarrier *wrapper;
  const char *name;
  struct GNUNET_HashCode key;
  uint16_t name_len;
  struct GNUNET_MQ_Envelope *env;

  if (NULL == GST_context)
  {
    GNUNET_break_op (0);
    GNUNET_SERVICE_client_drop (client);
    return;
  }
  if (client != GST_context->client)
  {
    GNUNET_break_op (0);
    GNUNET_SERVICE_client_drop (client);
    return;
  }
  name = msg->data;
  name_len = ntohs (msg->name_len);
  LOG_DEBUG ("Received BARRIER_STATUS for barrier `%s'\n",
             name);
  GNUNET_CRYPTO_hash (name,
                      name_len,
                      &key);
  barrier = GNUNET_CONTAINER_multihashmap_get (barrier_map,
                                               &key);
  if (NULL == barrier)
  {
    GNUNET_break_op (0);
    GNUNET_SERVICE_client_drop (client);
    return;
  }
  GNUNET_SERVICE_client_continue (client);
  for(client_ctx = barrier->head; NULL != client_ctx; client_ctx = client_ctx->next) /* Notify peers */
  {
    env = GNUNET_MQ_msg_copy (&msg->header);
    GNUNET_MQ_send (GNUNET_SERVICE_client_get_mq (client_ctx->client),
                    env);
  }
  /**
   * The wrapper barriers do not echo the barrier status, so we have to do it
   * here
   */
  for (wrapper = barrier->whead; NULL != wrapper; wrapper = wrapper->next)
  {
    GNUNET_TESTBED_queue_message_ (wrapper->controller,
                                   GNUNET_copy_message (&msg->header));
  }
}

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