-merge

8 files changed, 1017 insertions, 659 deletions

diff --git a/src/util/client.c b/src/util/client.c
index 3d74bff33..e5bf7e176 100644
--- a/src/util/client.c
+++ b/src/util/client.c
@@ -261,14 +261,27 @@ transmit_ready (void *cls)
   pos = (const char *) cstate->msg;
   len = ntohs (cstate->msg->size);
   GNUNET_assert (cstate->msg_off < len);
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "client: message of type %u trying to send with socket %p (MQ: %p\n",
+              ntohs(cstate->msg->type),
+              cstate->sock,
+              cstate->mq);
+
  RETRY:
   ret = GNUNET_NETWORK_socket_send (cstate->sock,
                                     &pos[cstate->msg_off],
                                     len - cstate->msg_off);
   if (-1 == ret)
   {
-    if (EINTR == errno)
+    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                "client: error during sending message of type %u\n",
+                ntohs(cstate->msg->type));
+    if (EINTR == errno){
+      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                  "client: retrying message of type %u\n",
+                  ntohs(cstate->msg->type));
       goto RETRY;
+    }
     GNUNET_MQ_inject_error (cstate->mq,
                             GNUNET_MQ_ERROR_WRITE);
     return;
@@ -277,6 +290,9 @@ transmit_ready (void *cls)
   cstate->msg_off += ret;
   if (cstate->msg_off < len)
   {
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "client: rescheduling message of type %u\n",
+                ntohs(cstate->msg->type));
     cstate->send_task
       = GNUNET_SCHEDULER_add_write_net (GNUNET_TIME_UNIT_FOREVER_REL,
                                         cstate->sock,
@@ -286,6 +302,9 @@ transmit_ready (void *cls)
       GNUNET_MQ_impl_send_in_flight (cstate->mq);
     return;
   }
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "client: sending message of type %u successful\n",
+              ntohs(cstate->msg->type));
   cstate->msg = NULL;
   GNUNET_MQ_impl_send_continue (cstate->mq);
 }
@@ -297,7 +316,9 @@ transmit_ready (void *cls)
  *
  * @param cls the `struct ClientState`
  * @param msg message we received.
- * @return #GNUNET_OK on success, #GNUNET_SYSERR to stop further processing
+ * @return #GNUNET_OK on success,
+ *     #GNUNET_NO to stop further processing due to disconnect (no error)
+ *     #GNUNET_SYSERR to stop further processing due to error
  */
 static int
 recv_message (void *cls,
@@ -306,7 +327,7 @@ recv_message (void *cls,
   struct ClientState *cstate = cls;
 
   if (GNUNET_YES == cstate->in_destroy)
-    return GNUNET_SYSERR;
+    return GNUNET_NO;
   LOG (GNUNET_ERROR_TYPE_DEBUG,
        "Received message of type %u and size %u from %s\n",
        ntohs (msg->type),
@@ -315,7 +336,7 @@ recv_message (void *cls,
   GNUNET_MQ_inject_message (cstate->mq,
                             msg);
   if (GNUNET_YES == cstate->in_destroy)
-    return GNUNET_SYSERR;
+    return GNUNET_NO;
   return GNUNET_OK;
 }
 
@@ -371,8 +392,12 @@ connection_client_destroy_impl (struct GNUNET_MQ_Handle *mq,
     GNUNET_SCHEDULER_cancel (cstate->recv_task);
   if (NULL != cstate->retry_task)
     GNUNET_SCHEDULER_cancel (cstate->retry_task);
-  if (NULL != cstate->sock)
+  if (NULL != cstate->sock){
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "client: destroying socket: %p\n",
+                cstate->sock);
     GNUNET_NETWORK_socket_close (cstate->sock);
+  }
   cancel_aps (cstate);
   GNUNET_free (cstate->service_name);
   GNUNET_free_non_null (cstate->hostname);
@@ -794,8 +819,12 @@ connection_client_send_impl (struct GNUNET_MQ_Handle *mq,
   GNUNET_assert (NULL == cstate->send_task);
   cstate->msg = msg;
   cstate->msg_off = 0;
-  if (NULL == cstate->sock)
+  if (NULL == cstate->sock){
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "client: message of type %u waiting for socket\n",
+                ntohs(msg->type));
     return; /* still waiting for connection */
+   }
   cstate->send_task
     = GNUNET_SCHEDULER_add_write_net (GNUNET_TIME_UNIT_FOREVER_REL,
                                       cstate->sock,
diff --git a/src/util/mq.c b/src/util/mq.c
index 90b2aa968..8d71359ac 100644
--- a/src/util/mq.c
+++ b/src/util/mq.c
@@ -357,6 +357,12 @@ GNUNET_MQ_send (struct GNUNET_MQ_Handle *mq,
   }
   GNUNET_assert (NULL == mq->envelope_head);
   mq->current_envelope = ev;
+
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "mq: sending message of type %u, queue empty (MQ: %p)\n",
+              ntohs(ev->mh->type),
+              mq);
+
   mq->send_impl (mq,
                  ev->mh,
                  mq->impl_state);
@@ -452,6 +458,11 @@ impl_send_continue (void *cls)
   GNUNET_CONTAINER_DLL_remove (mq->envelope_head,
                                mq->envelope_tail,
                                mq->current_envelope);
+
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "mq: sending message of type %u from queue\n",
+              ntohs(mq->current_envelope->mh->type));
+
   mq->send_impl (mq,
                  mq->current_envelope->mh,
                  mq->impl_state);
@@ -840,6 +851,9 @@ GNUNET_MQ_destroy (struct GNUNET_MQ_Handle *mq)
                                  ev);
     GNUNET_assert (0 < mq->queue_length);
     mq->queue_length--;
+    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                "MQ destroy drops message of type %u\n",
+                ntohs (ev->mh->type));
     GNUNET_MQ_discard (ev);
   }
   if (NULL != mq->current_envelope)
@@ -847,6 +861,9 @@ GNUNET_MQ_destroy (struct GNUNET_MQ_Handle *mq)
     /* we can only discard envelopes that
      * are not queued! */
     mq->current_envelope->parent_queue = NULL;
+    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                "MQ destroy drops current message of type %u\n",
+                ntohs (mq->current_envelope->mh->type));
     GNUNET_MQ_discard (mq->current_envelope);
     mq->current_envelope = NULL;
     GNUNET_assert (0 < mq->queue_length);
@@ -928,6 +945,11 @@ GNUNET_MQ_send_cancel (struct GNUNET_MQ_Envelope *ev)
       GNUNET_CONTAINER_DLL_remove (mq->envelope_head,
                                    mq->envelope_tail,
                                    mq->current_envelope);
+
+      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                  "mq: sending canceled message of type %u queue\n",
+                  ntohs(ev->mh->type));
+
       mq->send_impl (mq,
                      mq->current_envelope->mh,
                      mq->impl_state);
diff --git a/src/util/mst.c b/src/util/mst.c
index 0d90c5d10..5e472965f 100644
--- a/src/util/mst.c
+++ b/src/util/mst.c
@@ -1,6 +1,6 @@
 /*
      This file is part of GNUnet.
-     Copyright (C) 2010, 2016 GNUnet e.V.
+     Copyright (C) 2010, 2016, 2017 GNUnet e.V.
 
      GNUnet is free software; you can redistribute it and/or modify
      it under the terms of the GNU General Public License as published
@@ -126,6 +126,7 @@ GNUNET_MST_from_buffer (struct GNUNET_MessageStreamTokenizer *mst,
   int need_align;
   unsigned long offset;
   int ret;
+  int cbret;
 
   GNUNET_assert (mst->off <= mst->pos);
   GNUNET_assert (mst->pos <= mst->curr_buf);
@@ -229,9 +230,17 @@ do_align:
     if (one_shot == GNUNET_YES)
       one_shot = GNUNET_SYSERR;
     mst->off += want;
-  if (GNUNET_SYSERR == mst->cb (mst->cb_cls,
-                                hdr))
+    if (GNUNET_OK !=
+        (cbret = mst->cb (mst->cb_cls,
+                           hdr)))
+    {
+      if (GNUNET_SYSERR == cbret)
+        GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                    "Failure processing message of type %u and size %u\n",
+                    ntohs (hdr->type),
+                    ntohs (hdr->size));
       return GNUNET_SYSERR;
+    }
     if (mst->off == mst->pos)
     {
       /* reset to beginning of buffer, it's free right now! */
@@ -271,9 +280,17 @@ do_align:
       }
       if (one_shot == GNUNET_YES)
         one_shot = GNUNET_SYSERR;
-      if (GNUNET_SYSERR == mst->cb (mst->cb_cls,
-                                    hdr))
+      if (GNUNET_OK !=
+          (cbret = mst->cb (mst->cb_cls,
+                            hdr)))
+      {
+        if (GNUNET_SYSERR == cbret)
+          GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                      "Failure processing message of type %u and size %u\n",
+                      ntohs (hdr->type),
+                      ntohs (hdr->size));
         return GNUNET_SYSERR;
+      }
       buf += want;
       size -= want;
     }
diff --git a/src/util/network.c b/src/util/network.c
index 942288613..cf5ef3e00 100644
--- a/src/util/network.c
+++ b/src/util/network.c
@@ -1223,7 +1223,7 @@ GNUNET_NETWORK_fdset_copy (struct GNUNET_NETWORK_FDSet *to,
  * @return POSIX file descriptor
  */
 int
-GNUNET_NETWORK_get_fd (struct GNUNET_NETWORK_Handle *desc)
+GNUNET_NETWORK_get_fd (const struct GNUNET_NETWORK_Handle *desc)
 {
   return desc->fd;
 }
@@ -1236,7 +1236,7 @@ GNUNET_NETWORK_get_fd (struct GNUNET_NETWORK_Handle *desc)
  * @return sockaddr
  */
 struct sockaddr*
-GNUNET_NETWORK_get_addr (struct GNUNET_NETWORK_Handle *desc)
+GNUNET_NETWORK_get_addr (const struct GNUNET_NETWORK_Handle *desc)
 {
   return desc->addr;
 }
@@ -1249,7 +1249,7 @@ GNUNET_NETWORK_get_addr (struct GNUNET_NETWORK_Handle *desc)
  * @return socklen_t for sockaddr
  */
 socklen_t
-GNUNET_NETWORK_get_addrlen (struct GNUNET_NETWORK_Handle *desc)
+GNUNET_NETWORK_get_addrlen (const struct GNUNET_NETWORK_Handle *desc)
 {
   return desc->addrlen;
 }
diff --git a/src/util/program.c b/src/util/program.c
index 92a9750f3..233792387 100644
--- a/src/util/program.c
+++ b/src/util/program.c
@@ -69,6 +69,16 @@ struct CommandContext
 
 
 /**
+ * task run when the scheduler shuts down
+ */
+static void
+shutdown_task (void *cls)
+{
+  GNUNET_SPEEDUP_stop_ ();
+}
+
+
+/**
  * Initial task called by the scheduler for each
  * program.  Runs the program-specific main task.
  */
@@ -78,6 +88,7 @@ program_main (void *cls)
   struct CommandContext *cc = cls;
 
   GNUNET_SPEEDUP_start_(cc->cfg);
+  GNUNET_SCHEDULER_add_shutdown (&shutdown_task, NULL);
   GNUNET_RESOLVER_connect (cc->cfg);
   cc->task (cc->task_cls, cc->args, cc->cfgfile, cc->cfg);
 }
@@ -306,7 +317,6 @@ GNUNET_PROGRAM_run2 (int argc, char *const *argv, const char *binaryName,
   }
   ret = GNUNET_OK;
  cleanup:
-  GNUNET_SPEEDUP_stop_ ();
   GNUNET_CONFIGURATION_destroy (cfg);
   GNUNET_free_non_null (cc.cfgfile);
   GNUNET_free (cfg_fn);
diff --git a/src/util/scheduler.c b/src/util/scheduler.c
index 540a60557..b96e4e6c4 100644
--- a/src/util/scheduler.c
+++ b/src/util/scheduler.c
@@ -89,12 +89,6 @@ struct GNUNET_SCHEDULER_Handle
    * @deprecated
    */
   struct GNUNET_NETWORK_FDSet *ws;
-
-  /**
-   * Driver we used for the event loop.
-   */
-  const struct GNUNET_SCHEDULER_Driver *driver;
-
 };
 
 
@@ -124,36 +118,40 @@ struct GNUNET_SCHEDULER_Task
   void *callback_cls;
 
   /**
-   * Handle to the scheduler's state.
+   * Information about which FDs are ready for this task (and why).
    */
-  const struct GNUNET_SCHEDULER_Handle *sh;
+  struct GNUNET_SCHEDULER_FdInfo *fds;
 
   /**
-   * Set of file descriptors this task is waiting
-   * for for reading.  Once ready, this is updated
-   * to reflect the set of file descriptors ready
-   * for operation.
+   * Storage location used for @e fds if we want to avoid
+   * a separate malloc() call in the common case that this
+   * task is only about a single FD.
    */
-  struct GNUNET_NETWORK_FDSet *read_set;
+  struct GNUNET_SCHEDULER_FdInfo fdx;
 
   /**
-   * Set of file descriptors this task is waiting for for writing.
-   * Once ready, this is updated to reflect the set of file
-   * descriptors ready for operation.
+   * Size of the @e fds array.
    */
-  struct GNUNET_NETWORK_FDSet *write_set;
+  unsigned int fds_len;
 
   /**
-   * Information about which FDs are ready for this task (and why).
+   * if this task is related to multiple FDs this array contains
+   * all FdInfo structs that were marked as ready by calling
+   * #GNUNET_SCHEDULER_task_ready
    */
-  const struct GNUNET_SCHEDULER_FdInfo *fds;
+  struct GNUNET_SCHEDULER_FdInfo *ready_fds;
 
   /**
-   * Storage location used for @e fds if we want to avoid
-   * a separate malloc() call in the common case that this
-   * task is only about a single FD.
+   * Size of the @e ready_fds array
    */
-  struct GNUNET_SCHEDULER_FdInfo fdx;
+  unsigned int ready_fds_len;
+
+  /**
+   * Do we own the network and file handles referenced by the FdInfo
+   * structs in the fds array. This will only be GNUNET_YES if the
+   * task was created by the #GNUNET_SCHEDULER_add_select function.
+   */
+  int own_handles;
 
   /**
    * Absolute timeout value for the task, or
@@ -169,11 +167,6 @@ struct GNUNET_SCHEDULER_Task
 #endif
 
   /**
-   * Size of the @e fds array.
-   */
-  unsigned int fds_len;
-
-  /**
    * Why is the task ready?  Set after task is added to ready queue.
    * Initially set to zero.  All reasons that have already been
    * satisfied (i.e.  read or write ready) will be set over time.
@@ -224,11 +217,72 @@ struct GNUNET_SCHEDULER_Task
   int num_backtrace_strings;
 #endif
 
+};
+
+
+/**
+ * A struct representing an event the select driver is waiting for
+ */
+struct Scheduled
+{
+  struct Scheduled *prev;
+
+  struct Scheduled *next;
+
+  /**
+   * the task, the event is related to
+   */
+  struct GNUNET_SCHEDULER_Task *task;
+
+  /**
+   * information about the network socket / file descriptor where
+   * the event is expected to occur
+   */
+  struct GNUNET_SCHEDULER_FdInfo *fdi;
+
+  /**
+   * the event types (multiple event types can be ORed) the select
+   * driver is expected to wait for
+   */
+  enum GNUNET_SCHEDULER_EventType et;
+};
+
+
+/**
+ * Driver context used by GNUNET_SCHEDULER_run
+ */
+struct DriverContext
+{
+  /**
+   * the head of a DLL containing information about the events the
+   * select driver is waiting for
+   */
+  struct Scheduled *scheduled_head;
 
+  /**
+   * the tail of a DLL containing information about the events the
+   * select driver is waiting for
+   */
+  struct Scheduled *scheduled_tail;
+
+  /**
+   * the time until the select driver will wake up again (after
+   * calling select)
+   */
+  struct GNUNET_TIME_Relative timeout;
 };
 
 
 /**
+ * The driver used for the event loop. Will be handed over to
+ * the scheduler in #GNUNET_SCHEDULER_run_from_driver(), peristed
+ * there in this variable for later use in functions like
+ * #GNUNET_SCHEDULER_add_select(), #add_without_sets() and
+ * #GNUNET_SCHEDULER_cancel().
+ */
+static const struct GNUNET_SCHEDULER_Driver *scheduler_driver;
+
+/**
  * Head of list of tasks waiting for an event.
  */
 static struct GNUNET_SCHEDULER_Task *pending_head;
@@ -330,6 +384,11 @@ static struct GNUNET_SCHEDULER_TaskContext tc;
  */
 static void *scheduler_select_cls;
 
+/**
+ * Scheduler handle used for the driver functions
+ */
+static struct GNUNET_SCHEDULER_Handle sh;
+
 
 /**
  * Sets the select function to use in the scheduler (scheduler_select).
@@ -364,115 +423,44 @@ check_priority (enum GNUNET_SCHEDULER_Priority p)
 
 
 /**
- * Update all sets and timeout for select.
- *
- * @param rs read-set, set to all FDs we would like to read (updated)
- * @param ws write-set, set to all FDs we would like to write (updated)
- * @param timeout next timeout (updated)
+ * chooses the nearest timeout from all pending tasks, to be used
+ * to tell the driver the next wakeup time (using its set_wakeup
+ * callback)
  */
-static void
-update_sets (struct GNUNET_NETWORK_FDSet *rs,
-             struct GNUNET_NETWORK_FDSet *ws,
-             struct GNUNET_TIME_Relative *timeout)
+struct GNUNET_TIME_Absolute
+get_timeout ()
 {
   struct GNUNET_SCHEDULER_Task *pos;
   struct GNUNET_TIME_Absolute now;
-  struct GNUNET_TIME_Relative to;
+  struct GNUNET_TIME_Absolute timeout;
 
-  now = GNUNET_TIME_absolute_get ();
   pos = pending_timeout_head;
+  now = GNUNET_TIME_absolute_get ();
+  timeout = GNUNET_TIME_UNIT_FOREVER_ABS;
   if (NULL != pos)
   {
-    to = GNUNET_TIME_absolute_get_difference (now, pos->timeout);
-    if (timeout->rel_value_us > to.rel_value_us)
-      *timeout = to;
     if (0 != pos->reason)
-      *timeout = GNUNET_TIME_UNIT_ZERO;
+    {
+      timeout = now;
+    }
+    else
+    {
+      timeout = pos->timeout;
+    }
   }
   for (pos = pending_head; NULL != pos; pos = pos->next)
   {
-    if (pos->timeout.abs_value_us != GNUNET_TIME_UNIT_FOREVER_ABS.abs_value_us)
+    if (0 != pos->reason)
     {
-      to = GNUNET_TIME_absolute_get_difference (now, pos->timeout);
-      if (timeout->rel_value_us > to.rel_value_us)
-        *timeout = to;
+      timeout = now;
+    }
+    else if ((pos->timeout.abs_value_us != GNUNET_TIME_UNIT_FOREVER_ABS.abs_value_us) &&
+             (timeout.abs_value_us > pos->timeout.abs_value_us))
+    {
+      timeout = pos->timeout;
     }
-    if (-1 != pos->read_fd)
-      GNUNET_NETWORK_fdset_set_native (rs, pos->read_fd);
-    if (-1 != pos->write_fd)
-      GNUNET_NETWORK_fdset_set_native (ws, pos->write_fd);
-    if (NULL != pos->read_set)
-      GNUNET_NETWORK_fdset_add (rs, pos->read_set);
-    if (NULL != pos->write_set)
-      GNUNET_NETWORK_fdset_add (ws, pos->write_set);
-    if (0 != pos->reason)
-      *timeout = GNUNET_TIME_UNIT_ZERO;
-  }
-}
-
-
-/**
- * Check if the ready set overlaps with the set we want to have ready.
- * If so, update the want set (set all FDs that are ready).  If not,
- * return #GNUNET_NO.
- *
- * @param ready set that is ready
- * @param want set that we want to be ready
- * @return #GNUNET_YES if there was some overlap
- */
-static int
-set_overlaps (const struct GNUNET_NETWORK_FDSet *ready,
-              struct GNUNET_NETWORK_FDSet *want)
-{
-  if ((NULL == want) || (NULL == ready))
-    return GNUNET_NO;
-  if (GNUNET_NETWORK_fdset_overlap (ready, want))
-  {
-    /* copy all over (yes, there maybe unrelated bits,
-     * but this should not hurt well-written clients) */
-    GNUNET_NETWORK_fdset_copy (want, ready);
-    return GNUNET_YES;
   }
-  return GNUNET_NO;
-}
-
-
-/**
- * Check if the given task is eligible to run now.
- * Also set the reason why it is eligible.
- *
- * @param task task to check if it is ready
- * @param now the current time
- * @param rs set of FDs ready for reading
- * @param ws set of FDs ready for writing
- * @return #GNUNET_YES if we can run it, #GNUNET_NO if not.
- */
-static int
-is_ready (struct GNUNET_SCHEDULER_Task *task,
-          struct GNUNET_TIME_Absolute now,
-          const struct GNUNET_NETWORK_FDSet *rs,
-          const struct GNUNET_NETWORK_FDSet *ws)
-{
-  enum GNUNET_SCHEDULER_Reason reason;
-
-  reason = task->reason;
-  if (now.abs_value_us >= task->timeout.abs_value_us)
-    reason |= GNUNET_SCHEDULER_REASON_TIMEOUT;
-  if ((0 == (reason & GNUNET_SCHEDULER_REASON_READ_READY)) &&
-      (((task->read_fd != -1) &&
-        (GNUNET_YES == GNUNET_NETWORK_fdset_test_native (rs, task->read_fd))) ||
-       (set_overlaps (rs, task->read_set))))
-    reason |= GNUNET_SCHEDULER_REASON_READ_READY;
-  if ((0 == (reason & GNUNET_SCHEDULER_REASON_WRITE_READY)) &&
-      (((task->write_fd != -1) &&
-        (GNUNET_YES == GNUNET_NETWORK_fdset_test_native (ws, task->write_fd)))
-       || (set_overlaps (ws, task->write_set))))
-    reason |= GNUNET_SCHEDULER_REASON_WRITE_READY;
-  if (0 == reason)
-    return GNUNET_NO;           /* not ready */
-  reason |= GNUNET_SCHEDULER_REASON_PREREQ_DONE;
-  task->reason = reason;
-  return GNUNET_YES;
+  return timeout;
 }
 
 
@@ -495,51 +483,6 @@ queue_ready_task (struct GNUNET_SCHEDULER_Task *task)
 
 
 /**
- * Check which tasks are ready and move them
- * to the respective ready queue.
- *
- * @param rs FDs ready for reading
- * @param ws FDs ready for writing
- */
-static void
-check_ready (const struct GNUNET_NETWORK_FDSet *rs,
-             const struct GNUNET_NETWORK_FDSet *ws)
-{
-  struct GNUNET_SCHEDULER_Task *pos;
-  struct GNUNET_SCHEDULER_Task *next;
-  struct GNUNET_TIME_Absolute now;
-
-  now = GNUNET_TIME_absolute_get ();
-  while (NULL != (pos = pending_timeout_head))
-  {
-    if (now.abs_value_us >= pos->timeout.abs_value_us)
-      pos->reason |= GNUNET_SCHEDULER_REASON_TIMEOUT;
-    if (0 == pos->reason)
-      break;
-    GNUNET_CONTAINER_DLL_remove (pending_timeout_head,
-                                 pending_timeout_tail,
-                                 pos);
-    if (pending_timeout_last == pos)
-      pending_timeout_last = NULL;
-    queue_ready_task (pos);
-  }
-  pos = pending_head;
-  while (NULL != pos)
-  {
-    next = pos->next;
-    if (GNUNET_YES == is_ready (pos, now, rs, ws))
-    {
-      GNUNET_CONTAINER_DLL_remove (pending_head,
-                                   pending_tail,
-                                   pos);
-      queue_ready_task (pos);
-    }
-    pos = next;
-  }
-}
-
-
-/**
  * Request the shutdown of a scheduler.  Marks all tasks
  * awaiting shutdown as ready. Note that tasks
  * scheduled with #GNUNET_SCHEDULER_add_shutdown() AFTER this call
@@ -562,25 +505,6 @@ GNUNET_SCHEDULER_shutdown ()
 
 
 /**
- * Destroy a task (release associated resources)
- *
- * @param t task to destroy
- */
-static void
-destroy_task (struct GNUNET_SCHEDULER_Task *t)
-{
-  if (NULL != t->read_set)
-    GNUNET_NETWORK_fdset_destroy (t->read_set);
-  if (NULL != t->write_set)
-    GNUNET_NETWORK_fdset_destroy (t->write_set);
-#if EXECINFO
-  GNUNET_free (t->backtrace_strings);
-#endif
-  GNUNET_free (t);
-}
-
-
-/**
  * Output stack trace of task @a t.
  *
  * @param t task to dump stack trace of
@@ -592,88 +516,59 @@ dump_backtrace (struct GNUNET_SCHEDULER_Task *t)
   unsigned int i;
 
   for (i = 0; i < t->num_backtrace_strings; i++)
-    LOG (GNUNET_ERROR_TYPE_DEBUG,
-         "Task %p trace %u: %s\n",
-         t,
-         i,
-         t->backtrace_strings[i]);
+    LOG (GNUNET_ERROR_TYPE_WARNING,
+   "Task %p trace %u: %s\n",
+   t,
+   i,
+   t->backtrace_strings[i]);
 #endif
 }
 
 
 /**
- * Run at least one task in the highest-priority queue that is not
- * empty.  Keep running tasks until we are either no longer running
- * "URGENT" tasks or until we have at least one "pending" task (which
- * may become ready, hence we should select on it).  Naturally, if
- * there are no more ready tasks, we also return.
+ * Destroy a task (release associated resources)
  *
- * @param rs FDs ready for reading
- * @param ws FDs ready for writing
+ * @param t task to destroy
  */
 static void
-run_ready (struct GNUNET_NETWORK_FDSet *rs,
-           struct GNUNET_NETWORK_FDSet *ws)
+destroy_task (struct GNUNET_SCHEDULER_Task *t)
 {
-  enum GNUNET_SCHEDULER_Priority p;
-  struct GNUNET_SCHEDULER_Task *pos;
+  unsigned int i;
 
-  max_priority_added = GNUNET_SCHEDULER_PRIORITY_KEEP;
-  do
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "destroying task %p\n",
+       t);
+
+  if (GNUNET_YES == t->own_handles)
   {
-    if (0 == ready_count)
-      return;
-    GNUNET_assert (NULL == ready_head[GNUNET_SCHEDULER_PRIORITY_KEEP]);
-    /* yes, p>0 is correct, 0 is "KEEP" which should
-     * always be an empty queue (see assertion)! */
-    for (p = GNUNET_SCHEDULER_PRIORITY_COUNT - 1; p > 0; p--)
-    {
-      pos = ready_head[p];
-      if (NULL != pos)
-        break;
-    }
-    GNUNET_assert (NULL != pos);        /* ready_count wrong? */
-    GNUNET_CONTAINER_DLL_remove (ready_head[p],
-                                 ready_tail[p],
-                                 pos);
-    ready_count--;
-    current_priority = pos->priority;
-    current_lifeness = pos->lifeness;
-    active_task = pos;
-#if PROFILE_DELAYS
-    if (GNUNET_TIME_absolute_get_duration (pos->start_time).rel_value_us >
-        DELAY_THRESHOLD.rel_value_us)
+    for (i = 0; i != t->fds_len; ++i)
     {
-      LOG (GNUNET_ERROR_TYPE_DEBUG,
-           "Task %p took %s to be scheduled\n",
-           pos,
-           GNUNET_STRINGS_relative_time_to_string (GNUNET_TIME_absolute_get_duration (pos->start_time),
-                                                   GNUNET_YES));
+      const struct GNUNET_NETWORK_Handle *fd = t->fds[i].fd;
+      const struct GNUNET_DISK_FileHandle *fh = t->fds[i].fh;
+      if (fd)
+      {
+        GNUNET_NETWORK_socket_free_memory_only_ ((struct GNUNET_NETWORK_Handle *) fd);
+      }
+      if (fh)
+      {
+        // FIXME: on WIN32 this is not enough! A function
+        // GNUNET_DISK_file_free_memory_only would be nice
+        GNUNET_free ((void *) fh);
+      }
     }
-#endif
-    tc.reason = pos->reason;
-    tc.read_ready = (NULL == pos->read_set) ? rs : pos->read_set;
-    if ((-1 != pos->read_fd) &&
-        (0 != (pos->reason & GNUNET_SCHEDULER_REASON_READ_READY)))
-      GNUNET_NETWORK_fdset_set_native (rs, pos->read_fd);
-    tc.write_ready = (NULL == pos->write_set) ? ws : pos->write_set;
-    if ((-1 != pos->write_fd) &&
-        (0 != (pos->reason & GNUNET_SCHEDULER_REASON_WRITE_READY)))
-      GNUNET_NETWORK_fdset_set_native (ws, pos->write_fd);
-    if ((0 != (tc.reason & GNUNET_SCHEDULER_REASON_WRITE_READY)) &&
-        (-1 != pos->write_fd) &&
-        (!GNUNET_NETWORK_fdset_test_native (ws, pos->write_fd)))
-      GNUNET_assert (0);          // added to ready in previous select loop!
-    LOG (GNUNET_ERROR_TYPE_DEBUG,
-         "Running task: %p\n",
-         pos);
-    pos->callback (pos->callback_cls);
-    dump_backtrace (pos);
-    active_task = NULL;
-    destroy_task (pos);
-    tasks_run++;
   }
-  while ((NULL == pending_head) || (p >= max_priority_added));
+  if (t->fds_len > 1)
+  {
+    GNUNET_array_grow (t->fds, t->fds_len, 0);
+  }
+  if (t->ready_fds_len > 0)
+  {
+    GNUNET_array_grow (t->ready_fds, t->ready_fds_len, 0);
+  }
+#if EXECINFO
+  GNUNET_free (t->backtrace_strings);
+#endif
+  GNUNET_free (t);
 }
 
 
@@ -700,22 +595,22 @@ sighandler_pipe ()
 #endif
 
 
-/**
- * Wait for a short time.
- * Sleeps for @a ms ms (as that should be long enough for virtually all
- * modern systems to context switch and allow another process to do
- * some 'real' work).
- *
- * @param ms how many ms to wait
- */
-static void
-short_wait (unsigned int ms)
-{
-  struct GNUNET_TIME_Relative timeout;
-
-  timeout = GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MILLISECONDS, ms);
-  (void) GNUNET_NETWORK_socket_select (NULL, NULL, NULL, timeout);
-}
+///**
+// * Wait for a short time.
+// * Sleeps for @a ms ms (as that should be long enough for virtually all
+// * modern systems to context switch and allow another process to do
+// * some 'real' work).
+// *
+// * @param ms how many ms to wait
+// */
+//static void
+//short_wait (unsigned int ms)
+//{
+//  struct GNUNET_TIME_Relative timeout;
+//
+//  timeout = GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MILLISECONDS, ms);
+//  (void) GNUNET_NETWORK_socket_select (NULL, NULL, NULL, timeout);
+//}
 
 
 /**
@@ -737,35 +632,31 @@ sighandler_shutdown ()
 }
 
 
-/**
- * Check if the system is still alive. Trigger shutdown if we
- * have tasks, but none of them give us lifeness.
- *
- * @return #GNUNET_OK to continue the main loop,
- *         #GNUNET_NO to exit
- */
-static int
-check_lifeness ()
+void
+shutdown_if_no_lifeness ()
 {
   struct GNUNET_SCHEDULER_Task *t;
 
   if (ready_count > 0)
-    return GNUNET_OK;
+    return;
   for (t = pending_head; NULL != t; t = t->next)
-    if (t->lifeness == GNUNET_YES)
-      return GNUNET_OK;
+    if (GNUNET_YES == t->lifeness)
+      return;
   for (t = shutdown_head; NULL != t; t = t->next)
-    if (t->lifeness == GNUNET_YES)
-      return GNUNET_OK;
+    if (GNUNET_YES == t->lifeness)
+      return;
   for (t = pending_timeout_head; NULL != t; t = t->next)
-    if (t->lifeness == GNUNET_YES)
-      return GNUNET_OK;
-  if (NULL != shutdown_head)
+    if (GNUNET_YES == t->lifeness)
+      return;
+  /* No lifeness! Cancel all pending tasks the driver knows about and shutdown */
+  t = pending_head;
+  while (NULL != t)
   {
-    GNUNET_SCHEDULER_shutdown ();
-    return GNUNET_OK;
+    struct GNUNET_SCHEDULER_Task *next = t->next;
+    GNUNET_SCHEDULER_cancel (t);
+    t = next;
   }
-  return GNUNET_NO;
+  GNUNET_SCHEDULER_shutdown ();
 }
 
 
@@ -787,204 +678,17 @@ void
 GNUNET_SCHEDULER_run (GNUNET_SCHEDULER_TaskCallback task,
                       void *task_cls)
 {
-    GNUNET_SCHEDULER_run_with_optional_signals(GNUNET_YES, task, task_cls);
-}
-
-void
-GNUNET_SCHEDULER_run_with_optional_signals (int install_signals,
-                                            GNUNET_SCHEDULER_TaskCallback task,
-                                            void *task_cls)
-{
-  struct GNUNET_NETWORK_FDSet *rs;
-  struct GNUNET_NETWORK_FDSet *ws;
-  struct GNUNET_TIME_Relative timeout;
-  int ret;
-  struct GNUNET_SIGNAL_Context *shc_int;
-  struct GNUNET_SIGNAL_Context *shc_term;
-#if (SIGTERM != GNUNET_TERM_SIG)
-  struct GNUNET_SIGNAL_Context *shc_gterm;
-#endif
-
-#ifndef MINGW
-  struct GNUNET_SIGNAL_Context *shc_quit;
-  struct GNUNET_SIGNAL_Context *shc_hup;
-  struct GNUNET_SIGNAL_Context *shc_pipe;
-#endif
-  unsigned long long last_tr;
-  unsigned int busy_wait_warning;
-  const struct GNUNET_DISK_FileHandle *pr;
-  char c;
-
-  GNUNET_assert (NULL == active_task);
-  rs = GNUNET_NETWORK_fdset_create ();
-  ws = GNUNET_NETWORK_fdset_create ();
-  GNUNET_assert (NULL == shutdown_pipe_handle);
-  shutdown_pipe_handle = GNUNET_DISK_pipe (GNUNET_NO,
-                                           GNUNET_NO,
-                                           GNUNET_NO,
-                                           GNUNET_NO);
-  GNUNET_assert (NULL != shutdown_pipe_handle);
-  pr = GNUNET_DISK_pipe_handle (shutdown_pipe_handle,
-                                GNUNET_DISK_PIPE_END_READ);
-  GNUNET_assert (NULL != pr);
-  my_pid = getpid ();
-
-  if (GNUNET_YES == install_signals)
-  {
-    LOG (GNUNET_ERROR_TYPE_DEBUG,
-         "Registering signal handlers\n");
-    shc_int = GNUNET_SIGNAL_handler_install (SIGINT,
-                                           &sighandler_shutdown);
-    shc_term = GNUNET_SIGNAL_handler_install (SIGTERM,
-                                           &sighandler_shutdown);
-#if (SIGTERM != GNUNET_TERM_SIG)
-    shc_gterm = GNUNET_SIGNAL_handler_install (GNUNET_TERM_SIG,
-                                             &sighandler_shutdown);
-#endif
-#ifndef MINGW
-    shc_pipe = GNUNET_SIGNAL_handler_install (SIGPIPE,
-                                            &sighandler_pipe);
-    shc_quit = GNUNET_SIGNAL_handler_install (SIGQUIT,
-                                            &sighandler_shutdown);
-    shc_hup = GNUNET_SIGNAL_handler_install (SIGHUP,
-                                           &sighandler_shutdown);
-#endif
-  }
-
-  current_priority = GNUNET_SCHEDULER_PRIORITY_DEFAULT;
-  current_lifeness = GNUNET_YES;
-  GNUNET_SCHEDULER_add_with_reason_and_priority (task,
-                                                 task_cls,
-                                                 GNUNET_SCHEDULER_REASON_STARTUP,
-                                                 GNUNET_SCHEDULER_PRIORITY_DEFAULT);
-  active_task = (void *) (long) -1;     /* force passing of sanity check */
-  GNUNET_SCHEDULER_add_now_with_lifeness (GNUNET_NO,
-                                          &GNUNET_OS_install_parent_control_handler,
-                                          NULL);
-  active_task = NULL;
-  last_tr = 0;
-  busy_wait_warning = 0;
-  while (GNUNET_OK == check_lifeness ())
-  {
-    GNUNET_NETWORK_fdset_zero (rs);
-    GNUNET_NETWORK_fdset_zero (ws);
-    timeout = GNUNET_TIME_UNIT_FOREVER_REL;
-    update_sets (rs, ws, &timeout);
-    GNUNET_NETWORK_fdset_handle_set (rs, pr);
-    if (ready_count > 0)
-    {
-      /* no blocking, more work already ready! */
-      timeout = GNUNET_TIME_UNIT_ZERO;
-    }
-    if (NULL == scheduler_select)
-      ret = GNUNET_NETWORK_socket_select (rs,
-                                          ws,
-                                          NULL,
-                                          timeout);
-    else
-      ret = scheduler_select (scheduler_select_cls,
-                              rs,
-                              ws,
-                              NULL,
-                              timeout);
-    if (ret == GNUNET_SYSERR)
-    {
-      if (errno == EINTR)
-        continue;
-
-      LOG_STRERROR (GNUNET_ERROR_TYPE_ERROR, "select");
-#ifndef MINGW
-#if USE_LSOF
-      char lsof[512];
-
-      snprintf (lsof, sizeof (lsof), "lsof -p %d", getpid ());
-      (void) close (1);
-      (void) dup2 (2, 1);
-      if (0 != system (lsof))
-        LOG_STRERROR (GNUNET_ERROR_TYPE_WARNING,
-                      "system");
-#endif
-#endif
-#if DEBUG_FDS
-      struct GNUNET_SCHEDULER_Task *t;
-
-      for (t = pending_head; NULL != t; t = t->next)
-      {
-        if (-1 != t->read_fd)
-        {
-          int flags = fcntl (t->read_fd, F_GETFD);
-          if ((flags == -1) && (errno == EBADF))
-            {
-              LOG (GNUNET_ERROR_TYPE_ERROR,
-                   "Got invalid file descriptor %d!\n",
-                   t->read_fd);
-              dump_backtrace (t);
-            }
-        }
-        if (-1 != t->write_fd)
-          {
-            int flags = fcntl (t->write_fd, F_GETFD);
-            if ((flags == -1) && (errno == EBADF))
-              {
-                LOG (GNUNET_ERROR_TYPE_ERROR,
-                     "Got invalid file descriptor %d!\n",
-                     t->write_fd);
-                dump_backtrace (t);
-              }
-          }
-      }
-#endif
-      GNUNET_assert (0);
-      break;
-    }
-
-    if ( (0 == ret) &&
-         (0 == timeout.rel_value_us) &&
-         (busy_wait_warning > 16) )
-    {
-      LOG (GNUNET_ERROR_TYPE_WARNING,
-           "Looks like we're busy waiting...\n");
-      short_wait (100);                /* mitigate */
-    }
-    check_ready (rs, ws);
-    run_ready (rs, ws);
-    if (GNUNET_NETWORK_fdset_handle_isset (rs, pr))
-    {
-      /* consume the signal */
-      GNUNET_DISK_file_read (pr, &c, sizeof (c));
-      /* mark all active tasks as ready due to shutdown */
-      GNUNET_SCHEDULER_shutdown ();
-    }
-    if (last_tr == tasks_run)
-    {
-      short_wait (1);
-      busy_wait_warning++;
-    }
-    else
-    {
-      last_tr = tasks_run;
-      busy_wait_warning = 0;
-    }
-  }
-
-  if (GNUNET_YES == install_signals)
-  {
-    GNUNET_SIGNAL_handler_uninstall (shc_int);
-    GNUNET_SIGNAL_handler_uninstall (shc_term);
-#if (SIGTERM != GNUNET_TERM_SIG)
-    GNUNET_SIGNAL_handler_uninstall (shc_gterm);
-#endif
-#ifndef MINGW
-    GNUNET_SIGNAL_handler_uninstall (shc_pipe);
-    GNUNET_SIGNAL_handler_uninstall (shc_quit);
-    GNUNET_SIGNAL_handler_uninstall (shc_hup);
-#endif
-  }
-
-  GNUNET_DISK_pipe_close (shutdown_pipe_handle);
-  shutdown_pipe_handle = NULL;
-  GNUNET_NETWORK_fdset_destroy (rs);
-  GNUNET_NETWORK_fdset_destroy (ws);
+  struct GNUNET_SCHEDULER_Driver *driver;
+  struct DriverContext context = {.scheduled_head = NULL,
+                                  .scheduled_tail = NULL,
+                                  .timeout = GNUNET_TIME_UNIT_FOREVER_REL};
+  
+  driver = GNUNET_SCHEDULER_driver_select ();
+  driver->cls = &context;
+
+  GNUNET_SCHEDULER_run_with_driver (driver, task, task_cls);
+  
+  GNUNET_free (driver);
 }
 
 
@@ -1029,9 +733,164 @@ GNUNET_SCHEDULER_get_load (enum GNUNET_SCHEDULER_Priority p)
 }
 
 
+void
+init_fd_info (struct GNUNET_SCHEDULER_Task *t,
+              const struct GNUNET_NETWORK_Handle *const *read_nh,
+              unsigned int read_nh_len,
+              const struct GNUNET_NETWORK_Handle *const *write_nh,
+              unsigned int write_nh_len,
+              const struct GNUNET_DISK_FileHandle *const *read_fh,
+              unsigned int read_fh_len,
+              const struct GNUNET_DISK_FileHandle *const *write_fh,
+              unsigned int write_fh_len)
+{
+  // FIXME: if we have exactly two network handles / exactly two file handles
+  // and they are equal, we can make one FdInfo with both
+  // GNUNET_SCHEDULER_ET_IN and GNUNET_SCHEDULER_ET_OUT set.
+  struct GNUNET_SCHEDULER_FdInfo *fdi;
+
+  t->fds_len = read_nh_len + write_nh_len + read_fh_len + write_fh_len;
+  if (1 == t->fds_len)
+  {
+    fdi = &t->fdx;
+    t->fds = fdi;
+    if (1 == read_nh_len)
+    {
+      fdi->fd = *read_nh;
+      GNUNET_assert (NULL != fdi->fd);
+      fdi->et = GNUNET_SCHEDULER_ET_IN;
+      fdi->sock = GNUNET_NETWORK_get_fd (*read_nh);
+      t->read_fd = fdi->sock;
+      t->write_fd = -1;
+    }
+    else if (1 == write_nh_len)
+    {
+      fdi->fd = *write_nh;
+      GNUNET_assert (NULL != fdi->fd);
+      fdi->et = GNUNET_SCHEDULER_ET_OUT;
+      fdi->sock = GNUNET_NETWORK_get_fd (*write_nh);
+      t->read_fd = -1;
+      t->write_fd = fdi->sock;
+    }
+    else if (1 == read_fh_len)
+    {
+      fdi->fh = *read_fh;
+      GNUNET_assert (NULL != fdi->fh);
+      fdi->et = GNUNET_SCHEDULER_ET_IN;
+      fdi->sock = (*read_fh)->fd; // FIXME: does not work under WIN32
+      t->read_fd = fdi->sock;
+      t->write_fd = -1;
+    }
+    else
+    {
+      fdi->fh = *write_fh;
+      GNUNET_assert (NULL != fdi->fh);
+      fdi->et = GNUNET_SCHEDULER_ET_OUT;
+      fdi->sock = (*write_fh)->fd; // FIXME: does not work under WIN32
+      t->read_fd = -1;
+      t->write_fd = fdi->sock;
+    }
+  }
+  else
+  {
+    fdi = GNUNET_new_array (t->fds_len, struct GNUNET_SCHEDULER_FdInfo);
+    t->fds = fdi;
+    t->read_fd = -1;
+    t->write_fd = -1;
+    unsigned int i;
+    for (i = 0; i != read_nh_len; ++i)
+    {
+      fdi->fd = read_nh[i];
+      GNUNET_assert (NULL != fdi->fd);
+      fdi->et = GNUNET_SCHEDULER_ET_IN;
+      fdi->sock = GNUNET_NETWORK_get_fd (read_nh[i]);
+      ++fdi;
+    }
+    for (i = 0; i != write_nh_len; ++i)
+    {
+      fdi->fd = write_nh[i];
+      GNUNET_assert (NULL != fdi->fd);
+      fdi->et = GNUNET_SCHEDULER_ET_OUT;
+      fdi->sock = GNUNET_NETWORK_get_fd (write_nh[i]);
+      ++fdi;
+    }
+    for (i = 0; i != read_fh_len; ++i)
+    {
+      fdi->fh = read_fh[i];
+      GNUNET_assert (NULL != fdi->fh);
+      fdi->et = GNUNET_SCHEDULER_ET_IN;
+      fdi->sock = (read_fh[i])->fd; // FIXME: does not work under WIN32
+      ++fdi;
+    }
+    for (i = 0; i != write_fh_len; ++i)
+    {
+      fdi->fh = write_fh[i];
+      GNUNET_assert (NULL != fdi->fh);
+      fdi->et = GNUNET_SCHEDULER_ET_OUT;
+      fdi->sock = (write_fh[i])->fd; // FIXME: does not work under WIN32
+      ++fdi;
+    }
+  }
+}
+
+
+/**
+ * calls the given function @a func on each FdInfo related to @a t.
+ * Optionally updates the event type field in each FdInfo after calling
+ * @a func.
+ *
+ * @param t the task
+ * @param driver_func the function to call with each FdInfo contained in
+ *                    in @a t
+ * @param if_not_ready only call @a driver_func on FdInfos that are not
+ *                     ready
+ * @param et the event type to be set in each FdInfo after calling
+ *           @a driver_func on it, or -1 if no updating not desired.
+ */
+void driver_add_multiple (struct GNUNET_SCHEDULER_Task *t,
+                          enum GNUNET_SCHEDULER_EventType et)
+{
+  struct GNUNET_SCHEDULER_FdInfo *fdi;
+  int success = GNUNET_YES;
+
+  for (int i = 0; i != t->fds_len; ++i)
+  {
+    fdi = &t->fds[i];
+    success = scheduler_driver->add (scheduler_driver->cls, t, fdi) && success;
+    if (et != -1)
+    {
+      fdi->et = et;
+    }
+  }
+  if (GNUNET_YES != success)
+  {
+    LOG (GNUNET_ERROR_TYPE_ERROR,
+         "driver could not add task\n");
+  }
+}
+
+
+void
+shutdown_cb (void *cls)
+{
+  char c;
+  const struct GNUNET_DISK_FileHandle *pr;
+
+  pr = GNUNET_DISK_pipe_handle (shutdown_pipe_handle,
+                                GNUNET_DISK_PIPE_END_READ);
+  GNUNET_assert (! GNUNET_DISK_handle_invalid (pr));
+  /* consume the signal */
+  GNUNET_DISK_file_read (pr, &c, sizeof (c));
+  /* mark all active tasks as ready due to shutdown */
+  GNUNET_SCHEDULER_shutdown ();
+}
+
+
 /**
  * Cancel the task with the specified identifier.
- * The task must not yet have run.
+ * The task must not yet have run. Only allowed to be called as long as the
+ * scheduler is running (#GNUNET_SCHEDULER_run or
+ * #GNUNET_SCHEDULER_run_with_driver has been called and has not returned yet).
  *
  * @param task id of the task to cancel
  * @return original closure of the task
@@ -1040,34 +899,50 @@ void *
 GNUNET_SCHEDULER_cancel (struct GNUNET_SCHEDULER_Task *task)
 {
   enum GNUNET_SCHEDULER_Priority p;
+  int is_fd_task;
   void *ret;
 
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "canceling task %p\n",
+       task);
+
+  /* scheduler must be running */
+  GNUNET_assert (NULL != scheduler_driver);
   GNUNET_assert ( (NULL != active_task) ||
-                  (GNUNET_NO == task->lifeness) );
-  if (! task->in_ready_list)
+      (GNUNET_NO == task->lifeness) );
+  is_fd_task = (NULL != task->fds);
+  if (is_fd_task)
   {
-    if ( (-1 == task->read_fd) &&
-         (-1 == task->write_fd) &&
-         (NULL == task->read_set) &&
-         (NULL == task->write_set) )
+    int del_result = scheduler_driver->del (scheduler_driver->cls, task);
+    if (GNUNET_OK != del_result)
     {
-      if (GNUNET_YES == task->on_shutdown)
-        GNUNET_CONTAINER_DLL_remove (shutdown_head,
-                                     shutdown_tail,
-                                     task);
-      else
-        GNUNET_CONTAINER_DLL_remove (pending_timeout_head,
-                                     pending_timeout_tail,
-                                     task);
-      if (task == pending_timeout_last)
-        pending_timeout_last = NULL;
+      LOG (GNUNET_ERROR_TYPE_ERROR,
+           "driver could not delete task\n");
+      GNUNET_assert (0);
     }
-    else
+  }
+  if (! task->in_ready_list)
+  {
+    if (is_fd_task)
     {
       GNUNET_CONTAINER_DLL_remove (pending_head,
                                    pending_tail,
                                    task);
     }
+    else if (GNUNET_YES == task->on_shutdown)
+    {
+      GNUNET_CONTAINER_DLL_remove (shutdown_head,
+                                   shutdown_tail,
+                                   task);
+    }
+    else
+    {
+      GNUNET_CONTAINER_DLL_remove (pending_timeout_head,
+                                   pending_timeout_tail,
+                                   task);
+      if (pending_timeout_last == task)
+        pending_timeout_last = NULL;
+    }
   }
   else
   {
@@ -1078,9 +953,6 @@ GNUNET_SCHEDULER_cancel (struct GNUNET_SCHEDULER_Task *task)
     ready_count--;
   }
   ret = task->callback_cls;
-  LOG (GNUNET_ERROR_TYPE_DEBUG,
-       "Canceling task %p\n",
-       task);
   destroy_task (task);
   return ret;
 }
@@ -1101,7 +973,7 @@ init_backtrace (struct GNUNET_SCHEDULER_Task *t)
     = backtrace (backtrace_array, MAX_TRACE_DEPTH);
   t->backtrace_strings =
       backtrace_symbols (backtrace_array,
-                         t->num_backtrace_strings);
+       t->num_backtrace_strings);
   dump_backtrace (t);
 #endif
 }
@@ -1218,7 +1090,7 @@ GNUNET_SCHEDULER_add_at_with_priority (struct GNUNET_TIME_Absolute at,
   pending_timeout_last = t;
 
   LOG (GNUNET_ERROR_TYPE_DEBUG,
-       "Adding task: %p\n",
+       "Adding task %p\n",
        t);
   init_backtrace (t);
   return t;
@@ -1238,8 +1110,8 @@ GNUNET_SCHEDULER_add_at_with_priority (struct GNUNET_TIME_Absolute at,
  */
 struct GNUNET_SCHEDULER_Task *
 GNUNET_SCHEDULER_add_delayed_with_priority (struct GNUNET_TIME_Relative delay,
-                                            enum GNUNET_SCHEDULER_Priority priority,
-                                            GNUNET_SCHEDULER_TaskCallback task,
+              enum GNUNET_SCHEDULER_Priority priority,
+              GNUNET_SCHEDULER_TaskCallback task,
                                             void *task_cls)
 {
   return GNUNET_SCHEDULER_add_at_with_priority (GNUNET_TIME_relative_to_absolute (delay),
@@ -1307,12 +1179,12 @@ GNUNET_SCHEDULER_add_at (struct GNUNET_TIME_Absolute at,
 struct GNUNET_SCHEDULER_Task *
 GNUNET_SCHEDULER_add_delayed (struct GNUNET_TIME_Relative delay,
                               GNUNET_SCHEDULER_TaskCallback task,
-                              void *task_cls)
+                              void *task_cls)
 {
   return GNUNET_SCHEDULER_add_delayed_with_priority (delay,
-                                                     GNUNET_SCHEDULER_PRIORITY_DEFAULT,
-                                                     task,
-                                                     task_cls);
+                 GNUNET_SCHEDULER_PRIORITY_DEFAULT,
+                 task,
+                 task_cls);
 }
 
 
@@ -1333,11 +1205,11 @@ GNUNET_SCHEDULER_add_delayed (struct GNUNET_TIME_Relative delay,
  */
 struct GNUNET_SCHEDULER_Task *
 GNUNET_SCHEDULER_add_now (GNUNET_SCHEDULER_TaskCallback task,
-                          void *task_cls)
+                          void *task_cls)
 {
   return GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_ZERO,
-                                       task,
-                                       task_cls);
+                                       task,
+                                       task_cls);
 }
 
 
@@ -1353,7 +1225,7 @@ GNUNET_SCHEDULER_add_now (GNUNET_SCHEDULER_TaskCallback task,
  */
 struct GNUNET_SCHEDULER_Task *
 GNUNET_SCHEDULER_add_shutdown (GNUNET_SCHEDULER_TaskCallback task,
-                               void *task_cls)
+                               void *task_cls)
 {
   struct GNUNET_SCHEDULER_Task *t;
 
@@ -1370,12 +1242,12 @@ GNUNET_SCHEDULER_add_shutdown (GNUNET_SCHEDULER_TaskCallback task,
   t->timeout = GNUNET_TIME_UNIT_FOREVER_ABS;
   t->priority = GNUNET_SCHEDULER_PRIORITY_SHUTDOWN;
   t->on_shutdown = GNUNET_YES;
-  t->lifeness = GNUNET_YES;
+  t->lifeness = GNUNET_NO;
   GNUNET_CONTAINER_DLL_insert (shutdown_head,
-                               shutdown_tail,
-                               t);
+                               shutdown_tail,
+                               t);
   LOG (GNUNET_ERROR_TYPE_DEBUG,
-       "Adding task: %p\n",
+       "Adding shutdown task %p\n",
        t);
   init_backtrace (t);
   return t;
@@ -1409,6 +1281,33 @@ GNUNET_SCHEDULER_add_now_with_lifeness (int lifeness,
 }
 
 
+#if DEBUG_FDS
+/**
+ * check a raw file descriptor and abort if it is bad (for debugging purposes)
+ *
+ * @param t the task related to the file descriptor
+ * @param raw_fd the raw file descriptor to check
+ */
+void
+check_fd (struct GNUNET_SCHEDULER_Task *t, int raw_fd)
+{
+  if (-1 != raw_fd)
+  {
+    int flags = fcntl (raw_fd, F_GETFD);
+
+    if ((flags == -1) && (errno == EBADF))
+    {
+      LOG (GNUNET_ERROR_TYPE_ERROR,
+           "Got invalid file descriptor %d!\n",
+           raw_fd);
+      init_backtrace (t);
+      GNUNET_assert (0);
+    }
+  }
+}
+#endif
+
+
 /**
  * Schedule a new task to be run with a specified delay or when any of
  * the specified file descriptor sets is ready.  The delay can be used
@@ -1437,9 +1336,11 @@ GNUNET_SCHEDULER_add_now_with_lifeness (int lifeness,
 #ifndef MINGW
 static struct GNUNET_SCHEDULER_Task *
 add_without_sets (struct GNUNET_TIME_Relative delay,
-                  enum GNUNET_SCHEDULER_Priority priority,
-                  int rfd,
-                  int wfd,
+                  enum GNUNET_SCHEDULER_Priority priority,
+                  const struct GNUNET_NETWORK_Handle *read_nh,
+                  const struct GNUNET_NETWORK_Handle *write_nh,
+                  const struct GNUNET_DISK_FileHandle *read_fh,
+                  const struct GNUNET_DISK_FileHandle *write_fh,
                   GNUNET_SCHEDULER_TaskCallback task,
                   void *task_cls)
 {
@@ -1448,39 +1349,23 @@ add_without_sets (struct GNUNET_TIME_Relative delay,
   GNUNET_assert (NULL != active_task);
   GNUNET_assert (NULL != task);
   t = GNUNET_new (struct GNUNET_SCHEDULER_Task);
+  init_fd_info (t,
+                &read_nh,
+                read_nh ? 1 : 0,
+                &write_nh,
+                write_nh ? 1 : 0,
+                &read_fh,
+                read_fh ? 1 : 0,
+                &write_fh,
+                write_fh ? 1 : 0);
   t->callback = task;
   t->callback_cls = task_cls;
 #if DEBUG_FDS
-  if (-1 != rfd)
-  {
-    int flags = fcntl (rfd, F_GETFD);
-
-    if ((flags == -1) && (errno == EBADF))
-    {
-      LOG (GNUNET_ERROR_TYPE_ERROR,
-           "Got invalid file descriptor %d!\n",
-           rfd);
-      init_backtrace (t);
-      GNUNET_assert (0);
-    }
-  }
-  if (-1 != wfd)
-  {
-    int flags = fcntl (wfd, F_GETFD);
-
-    if (flags == -1 && errno == EBADF)
-    {
-      LOG (GNUNET_ERROR_TYPE_ERROR,
-           "Got invalid file descriptor %d!\n",
-           wfd);
-      init_backtrace (t);
-      GNUNET_assert (0);
-    }
-  }
+  check_fd (t, NULL != read_nh ? GNUNET_NETWORK_get_fd (read_nh) : -1);
+  check_fd (t, NULL != write_nh ? GNUNET_NETWORK_get_fd (write_nh) : -1);
+  check_fd (t, NULL != read_fh ? read_fh->fd : -1);
+  check_fd (t, NULL != write_fh ? write_fh->fd : -1);
 #endif
-  t->read_fd = rfd;
-  GNUNET_assert (wfd >= -1);
-  t->write_fd = wfd;
 #if PROFILE_DELAYS
   t->start_time = GNUNET_TIME_absolute_get ();
 #endif
@@ -1490,11 +1375,9 @@ add_without_sets (struct GNUNET_TIME_Relative delay,
   GNUNET_CONTAINER_DLL_insert (pending_head,
                                pending_tail,
                                t);
+  driver_add_multiple (t, GNUNET_SCHEDULER_ET_NONE);
   max_priority_added = GNUNET_MAX (max_priority_added,
                                    t->priority);
-  LOG (GNUNET_ERROR_TYPE_DEBUG,
-       "Adding task %p\n",
-       t);
   init_backtrace (t);
   return t;
 }
@@ -1507,6 +1390,9 @@ add_without_sets (struct GNUNET_TIME_Relative delay,
  * used as a timeout on the socket being ready.  The task will be
  * scheduled for execution once either the delay has expired or the
  * socket operation is ready.  It will be run with the DEFAULT priority.
+ * Only allowed to be called as long as the scheduler is running
+ * (#GNUNET_SCHEDULER_run or #GNUNET_SCHEDULER_run_with_driver has been
+ * called and has not returned yet).
  *
  * @param delay when should this operation time out?
  * @param rfd read file-descriptor
@@ -1522,8 +1408,8 @@ GNUNET_SCHEDULER_add_read_net (struct GNUNET_TIME_Relative delay,
                                void *task_cls)
 {
   return GNUNET_SCHEDULER_add_read_net_with_priority (delay,
-                                                      GNUNET_SCHEDULER_PRIORITY_DEFAULT,
-                                                      rfd, task, task_cls);
+                  GNUNET_SCHEDULER_PRIORITY_DEFAULT,
+                  rfd, task, task_cls);
 }
 
 
@@ -1534,6 +1420,9 @@ GNUNET_SCHEDULER_add_read_net (struct GNUNET_TIME_Relative delay,
  * socket being ready.  The task will be scheduled for execution once
  * either the delay has expired or the socket operation is ready.  It
  * will be run with the DEFAULT priority.
+ * Only allowed to be called as long as the scheduler is running
+ * (#GNUNET_SCHEDULER_run or #GNUNET_SCHEDULER_run_with_driver has been
+ * called and has not returned yet).
  *
  * @param delay when should this operation time out?
  * @param priority priority to use for the task
@@ -1545,9 +1434,9 @@ GNUNET_SCHEDULER_add_read_net (struct GNUNET_TIME_Relative delay,
  */
 struct GNUNET_SCHEDULER_Task *
 GNUNET_SCHEDULER_add_read_net_with_priority (struct GNUNET_TIME_Relative delay,
-                                             enum GNUNET_SCHEDULER_Priority priority,
-                                             struct GNUNET_NETWORK_Handle *rfd,
-                                             GNUNET_SCHEDULER_TaskCallback task,
+               enum GNUNET_SCHEDULER_Priority priority,
+               struct GNUNET_NETWORK_Handle *rfd,
+               GNUNET_SCHEDULER_TaskCallback task,
                                              void *task_cls)
 {
   return GNUNET_SCHEDULER_add_net_with_priority (delay, priority,
@@ -1565,6 +1454,9 @@ GNUNET_SCHEDULER_add_read_net_with_priority (struct GNUNET_TIME_Relative delay,
  * scheduled for execution once either the delay has expired or the
  * socket operation is ready.  It will be run with the priority of
  * the calling task.
+ * Only allowed to be called as long as the scheduler is running
+ * (#GNUNET_SCHEDULER_run or #GNUNET_SCHEDULER_run_with_driver has been
+ * called and has not returned yet).
  *
  * @param delay when should this operation time out?
  * @param wfd write file-descriptor
@@ -1592,6 +1484,9 @@ GNUNET_SCHEDULER_add_write_net (struct GNUNET_TIME_Relative delay,
  * used as a timeout on the socket being ready.  The task will be
  * scheduled for execution once either the delay has expired or the
  * socket operation is ready.
+ * Only allowed to be called as long as the scheduler is running
+ * (#GNUNET_SCHEDULER_run or #GNUNET_SCHEDULER_run_with_driver has been
+ * called and has not returned yet).
  *
  * @param delay when should this operation time out?
  * @param priority priority of the task
@@ -1612,6 +1507,9 @@ GNUNET_SCHEDULER_add_net_with_priority  (struct GNUNET_TIME_Relative delay,
                                          GNUNET_SCHEDULER_TaskCallback task,
                                          void *task_cls)
 {
+  /* scheduler must be running */
+  GNUNET_assert (NULL != scheduler_driver);
+
 #if MINGW
   struct GNUNET_NETWORK_FDSet *s;
   struct GNUNET_SCHEDULER_Task * ret;
@@ -1627,10 +1525,13 @@ GNUNET_SCHEDULER_add_net_with_priority  (struct GNUNET_TIME_Relative delay,
   GNUNET_NETWORK_fdset_destroy (s);
   return ret;
 #else
+  GNUNET_assert (on_read || on_write);
   GNUNET_assert (GNUNET_NETWORK_get_fd (fd) >= 0);
   return add_without_sets (delay, priority,
-                           on_read  ? GNUNET_NETWORK_get_fd (fd) : -1,
-                           on_write ? GNUNET_NETWORK_get_fd (fd) : -1,
+                           on_read  ? fd : NULL,
+                           on_write ? fd : NULL,
+                           NULL,
+                           NULL,
                            task, task_cls);
 #endif
 }
@@ -1642,6 +1543,9 @@ GNUNET_SCHEDULER_add_net_with_priority  (struct GNUNET_TIME_Relative delay,
  * used as a timeout on the socket being ready.  The task will be
  * scheduled for execution once either the delay has expired or the
  * socket operation is ready. It will be run with the DEFAULT priority.
+ * Only allowed to be called as long as the scheduler is running
+ * (#GNUNET_SCHEDULER_run or #GNUNET_SCHEDULER_run_with_driver has been
+ * called and has not returned yet).
  *
  * @param delay when should this operation time out?
  * @param rfd read file-descriptor
@@ -1668,6 +1572,9 @@ GNUNET_SCHEDULER_add_read_file (struct GNUNET_TIME_Relative delay,
  * used as a timeout on the socket being ready.  The task will be
  * scheduled for execution once either the delay has expired or the
  * socket operation is ready. It will be run with the DEFAULT priority.
+ * Only allowed to be called as long as the scheduler is running
+ * (#GNUNET_SCHEDULER_run or #GNUNET_SCHEDULER_run_with_driver has been
+ * called and has not returned yet).
  *
  * @param delay when should this operation time out?
  * @param wfd write file-descriptor
@@ -1694,6 +1601,9 @@ GNUNET_SCHEDULER_add_write_file (struct GNUNET_TIME_Relative delay,
  * used as a timeout on the socket being ready.  The task will be
  * scheduled for execution once either the delay has expired or the
  * socket operation is ready.
+ * Only allowed to be called as long as the scheduler is running
+ * (#GNUNET_SCHEDULER_run or #GNUNET_SCHEDULER_run_with_driver has been
+ * called and has not returned yet).
  *
  * @param delay when should this operation time out?
  * @param priority priority of the task
@@ -1712,6 +1622,9 @@ GNUNET_SCHEDULER_add_file_with_priority (struct GNUNET_TIME_Relative delay,
                                          int on_read, int on_write,
                                          GNUNET_SCHEDULER_TaskCallback task, void *task_cls)
 {
+  /* scheduler must be running */
+  GNUNET_assert (NULL != scheduler_driver);
+
 #if MINGW
   struct GNUNET_NETWORK_FDSet *s;
   struct GNUNET_SCHEDULER_Task * ret;
@@ -1727,19 +1640,70 @@ GNUNET_SCHEDULER_add_file_with_priority (struct GNUNET_TIME_Relative delay,
   GNUNET_NETWORK_fdset_destroy (s);
   return ret;
 #else
-  int real_fd;
-
-  GNUNET_DISK_internal_file_handle_ (fd, &real_fd, sizeof (int));
-  GNUNET_assert (real_fd >= 0);
-  return add_without_sets (
-      delay, priority,
-      on_read  ? real_fd : -1,
-      on_write ? real_fd : -1,
-      task, task_cls);
+  GNUNET_assert (on_read || on_write);
+  GNUNET_assert (fd->fd >= 0);
+  return add_without_sets (delay, priority,
+                           NULL,
+                           NULL,
+                           on_read ? fd : NULL,
+                           on_write ? fd : NULL,
+                           task, task_cls);
 #endif
 }
 
 
+void
+extract_handles (struct GNUNET_SCHEDULER_Task *t,
+                 const struct GNUNET_NETWORK_FDSet *fdset,
+                 const struct GNUNET_NETWORK_Handle ***ntarget,
+                 unsigned int *extracted_nhandles,
+                 const struct GNUNET_DISK_FileHandle ***ftarget,
+                 unsigned int *extracted_fhandles)
+{
+  // FIXME: this implementation only works for unix, for WIN32 the file handles
+  // in fdset must be handled separately
+  const struct GNUNET_NETWORK_Handle **nhandles;
+  const struct GNUNET_DISK_FileHandle **fhandles;
+  unsigned int nhandles_len, fhandles_len;
+  int sock;
+
+  nhandles = NULL;
+  fhandles = NULL;
+  nhandles_len = 0;
+  fhandles_len = 0;
+  for (sock = 0; sock != fdset->nsds; ++sock)
+  {
+    if (GNUNET_YES == GNUNET_NETWORK_fdset_test_native (fdset, sock))
+    {
+      struct GNUNET_NETWORK_Handle *nhandle;
+      struct GNUNET_DISK_FileHandle *fhandle;
+
+      nhandle = GNUNET_NETWORK_socket_box_native (sock);
+      if (NULL != nhandle)
+      {
+        GNUNET_array_append (nhandles, nhandles_len, nhandle);
+      }
+      else
+      {
+        fhandle = GNUNET_DISK_get_handle_from_int_fd (sock);
+        if (NULL != fhandle)
+        {
+          GNUNET_array_append (fhandles, fhandles_len, fhandle);
+        }
+        else
+        {
+          GNUNET_assert (0);
+        }
+      }
+    }
+  }
+  *ntarget = nhandles_len > 0 ? nhandles : NULL;
+  *ftarget = fhandles_len > 0 ? fhandles : NULL;
+  *extracted_nhandles = nhandles_len;
+  *extracted_fhandles = fhandles_len;
+}
+
+
 /**
  * Schedule a new task to be run with a specified delay or when any of
  * the specified file descriptor sets is ready.  The delay can be used
@@ -1755,6 +1719,9 @@ GNUNET_SCHEDULER_add_file_with_priority (struct GNUNET_TIME_Relative delay,
  *     || any-rs-ready
  *     || any-ws-ready) )
  * </code>
+ * Only allowed to be called as long as the scheduler is running
+ * (#GNUNET_SCHEDULER_run or #GNUNET_SCHEDULER_run_with_driver has been
+ * called and has not returned yet).
  *
  * @param prio how important is this task?
  * @param delay how long should we wait?
@@ -1774,13 +1741,20 @@ GNUNET_SCHEDULER_add_select (enum GNUNET_SCHEDULER_Priority prio,
                              void *task_cls)
 {
   struct GNUNET_SCHEDULER_Task *t;
-
-  if ( (NULL == rs) &&
-       (NULL == ws) )
+  const struct GNUNET_NETWORK_Handle **read_nhandles;
+  const struct GNUNET_NETWORK_Handle **write_nhandles;
+  const struct GNUNET_DISK_FileHandle **read_fhandles;
+  const struct GNUNET_DISK_FileHandle **write_fhandles;
+  unsigned int read_nhandles_len, write_nhandles_len,
+               read_fhandles_len, write_fhandles_len;
+
+  if (((NULL == rs) && (NULL == ws)) || ((0 == rs->nsds) && (0 == ws->nsds)))
     return GNUNET_SCHEDULER_add_delayed_with_priority (delay,
                                                        prio,
                                                        task,
                                                        task_cls);
+  /* scheduler must be running */
+  GNUNET_assert (NULL != scheduler_driver);
   GNUNET_assert (NULL != active_task);
   GNUNET_assert (NULL != task);
   t = GNUNET_new (struct GNUNET_SCHEDULER_Task);
@@ -1788,16 +1762,48 @@ GNUNET_SCHEDULER_add_select (enum GNUNET_SCHEDULER_Priority prio,
   t->callback_cls = task_cls;
   t->read_fd = -1;
   t->write_fd = -1;
+  t->own_handles = GNUNET_YES;
+  read_nhandles = NULL;
+  write_nhandles = NULL;
+  read_fhandles = NULL;
+  write_fhandles = NULL;
+  read_nhandles_len = 0;
+  write_nhandles_len = 0;
+  read_fhandles_len = 0;
+  write_fhandles_len = 0;
   if (NULL != rs)
   {
-    t->read_set = GNUNET_NETWORK_fdset_create ();
-    GNUNET_NETWORK_fdset_copy (t->read_set, rs);
+    extract_handles (t,
+                     rs,
+                     &read_nhandles,
+                     &read_nhandles_len,
+                     &read_fhandles,
+                     &read_fhandles_len);
   }
   if (NULL != ws)
   {
-    t->write_set = GNUNET_NETWORK_fdset_create ();
-    GNUNET_NETWORK_fdset_copy (t->write_set, ws);
+    extract_handles (t,
+                     ws,
+                     &write_nhandles,
+                     &write_nhandles_len,
+                     &write_fhandles,
+                     &write_fhandles_len);
   }
+  init_fd_info (t,
+                read_nhandles,
+                read_nhandles_len,
+                write_nhandles,
+                write_nhandles_len,
+                read_fhandles,
+                read_fhandles_len,
+                write_fhandles,
+                write_fhandles_len);
+  /* free the arrays of pointers to network / file handles, the actual
+   * handles will be freed in destroy_task */
+  GNUNET_array_grow (read_nhandles, read_nhandles_len, 0);
+  GNUNET_array_grow (write_nhandles, write_nhandles_len, 0);
+  GNUNET_array_grow (read_fhandles, read_fhandles_len, 0);
+  GNUNET_array_grow (write_fhandles, write_fhandles_len, 0);
 #if PROFILE_DELAYS
   t->start_time = GNUNET_TIME_absolute_get ();
 #endif
@@ -1810,8 +1816,9 @@ GNUNET_SCHEDULER_add_select (enum GNUNET_SCHEDULER_Priority prio,
   GNUNET_CONTAINER_DLL_insert (pending_head,
                                pending_tail,
                                t);
+  driver_add_multiple (t, GNUNET_SCHEDULER_ET_NONE);
   max_priority_added = GNUNET_MAX (max_priority_added,
-                                   t->priority);
+           t->priority);
   LOG (GNUNET_ERROR_TYPE_DEBUG,
        "Adding task %p\n",
        t);
@@ -1822,17 +1829,18 @@ GNUNET_SCHEDULER_add_select (enum GNUNET_SCHEDULER_Priority prio,
 
 /**
  * Function used by event-loop implementations to signal the scheduler
- * that a particular @a task is ready due to an event of type @a et.
+ * that a particular @a task is ready due to an event specified in the
+ * et field of @a fdi.
  *
  * This function will then queue the task to notify the application
  * that the task is ready (with the respective priority).
  *
- * @param task the task that is ready, NULL for wake up calls
- * @param et information about why the task is ready
+ * @param task the task that is ready
+ * @param fdi information about the related FD
  */
 void
 GNUNET_SCHEDULER_task_ready (struct GNUNET_SCHEDULER_Task *task,
-                             enum GNUNET_SCHEDULER_EventType et)
+                             struct GNUNET_SCHEDULER_FdInfo *fdi)
 {
   enum GNUNET_SCHEDULER_Reason reason;
   struct GNUNET_TIME_Absolute now;
@@ -1842,17 +1850,20 @@ GNUNET_SCHEDULER_task_ready (struct GNUNET_SCHEDULER_Task *task,
   if (now.abs_value_us >= task->timeout.abs_value_us)
     reason |= GNUNET_SCHEDULER_REASON_TIMEOUT;
   if ( (0 == (reason & GNUNET_SCHEDULER_REASON_READ_READY)) &&
-       (0 != (GNUNET_SCHEDULER_ET_IN & et)) )
+       (0 != (GNUNET_SCHEDULER_ET_IN & fdi->et)) )
     reason |= GNUNET_SCHEDULER_REASON_READ_READY;
   if ( (0 == (reason & GNUNET_SCHEDULER_REASON_WRITE_READY)) &&
-       (0 != (GNUNET_SCHEDULER_ET_OUT & et)) )
+       (0 != (GNUNET_SCHEDULER_ET_OUT & fdi->et)) )
     reason |= GNUNET_SCHEDULER_REASON_WRITE_READY;
   reason |= GNUNET_SCHEDULER_REASON_PREREQ_DONE;
   task->reason = reason;
-  task->fds = &task->fdx;
-  task->fdx.et = et;
-  task->fds_len = 1;
-  queue_ready_task (task);
+  if (GNUNET_NO == task->in_ready_list)
+  {
+    GNUNET_CONTAINER_DLL_remove (pending_head,
+                                 pending_tail,
+                                 task);
+    queue_ready_task (task);
+  }
 }
 
 
@@ -1862,15 +1873,16 @@ GNUNET_SCHEDULER_task_ready (struct GNUNET_SCHEDULER_Task *task,
  * there are tasks left to run just to give other tasks a chance as
  * well.  If we return #GNUNET_YES, the driver should call this
  * function again as soon as possible, while if we return #GNUNET_NO
- * it must block until the operating system has more work as the
- * scheduler has no more work to do right now.
+ * it must block until either the operating system has more work (the
+ * scheduler has no more work to do right now) or the timeout set by
+ * the scheduler (using the set_wakeup callback) is reached.
  *
  * @param sh scheduler handle that was given to the `loop`
  * @return #GNUNET_OK if there are more tasks that are ready,
  *          and thus we would like to run more (yield to avoid
  *          blocking other activities for too long)
  *         #GNUNET_NO if we are done running tasks (yield to block)
- *         #GNUNET_SYSERR on error
+ *         #GNUNET_SYSERR on error, e.g. no tasks were ready
  */
 int
 GNUNET_SCHEDULER_run_from_driver (struct GNUNET_SCHEDULER_Handle *sh)
@@ -1894,9 +1906,27 @@ GNUNET_SCHEDULER_run_from_driver (struct GNUNET_SCHEDULER_Handle *sh)
       pending_timeout_last = NULL;
     queue_ready_task (pos);
   }
+  pos = pending_head;
+  while (NULL != pos)
+  {
+    struct GNUNET_SCHEDULER_Task *next = pos->next;
+    if (now.abs_value_us >= pos->timeout.abs_value_us)
+    {
+      pos->reason |= GNUNET_SCHEDULER_REASON_TIMEOUT;
+      GNUNET_CONTAINER_DLL_remove (pending_head,
+                                   pending_tail,
+                                   pos);
+      queue_ready_task (pos);
+    }
+    pos = next;
+  }
 
   if (0 == ready_count)
-    return GNUNET_NO;
+  {
+    LOG (GNUNET_ERROR_TYPE_ERROR,
+         "GNUNET_SCHEDULER_run_from_driver was called, but no tasks are ready!\n");
+    return GNUNET_SYSERR;
+  }
 
   /* find out which task priority level we are going to
      process this time */
@@ -1916,49 +1946,74 @@ GNUNET_SCHEDULER_run_from_driver (struct GNUNET_SCHEDULER_Handle *sh)
   while (NULL != (pos = ready_head[p]))
   {
     GNUNET_CONTAINER_DLL_remove (ready_head[p],
-                                 ready_tail[p],
-                                 pos);
+         ready_tail[p],
+         pos);
     ready_count--;
     current_priority = pos->priority;
     current_lifeness = pos->lifeness;
     active_task = pos;
 #if PROFILE_DELAYS
     if (GNUNET_TIME_absolute_get_duration (pos->start_time).rel_value_us >
-        DELAY_THRESHOLD.rel_value_us)
+        DELAY_THRESHOLD.rel_value_us)
     {
       LOG (GNUNET_ERROR_TYPE_DEBUG,
-           "Task %p took %s to be scheduled\n",
-           pos,
-           GNUNET_STRINGS_relative_time_to_string (GNUNET_TIME_absolute_get_duration (pos->start_time),
-                                                   GNUNET_YES));
+           "Task %p took %s to be scheduled\n",
+           pos,
+           GNUNET_STRINGS_relative_time_to_string (GNUNET_TIME_absolute_get_duration (pos->start_time),
+                                                   GNUNET_YES));
     }
 #endif
     tc.reason = pos->reason;
     GNUNET_NETWORK_fdset_zero (sh->rs);
     GNUNET_NETWORK_fdset_zero (sh->ws);
+    // FIXME: do we have to remove FdInfos from fds if they are not ready?
     tc.fds_len = pos->fds_len;
     tc.fds = pos->fds;
-    tc.read_ready = (NULL == pos->read_set) ? sh->rs : pos->read_set;
-    if ( (-1 != pos->read_fd) &&
-         (0 != (pos->reason & GNUNET_SCHEDULER_REASON_READ_READY)) )
-      GNUNET_NETWORK_fdset_set_native (sh->rs,
-                                       pos->read_fd);
-    tc.write_ready = (NULL == pos->write_set) ? sh->ws : pos->write_set;
-    if ((-1 != pos->write_fd) &&
-        (0 != (pos->reason & GNUNET_SCHEDULER_REASON_WRITE_READY)))
-      GNUNET_NETWORK_fdset_set_native (sh->ws,
-                                       pos->write_fd);
+    for (int i = 0; i != pos->fds_len; ++i)
+    {
+      struct GNUNET_SCHEDULER_FdInfo *fdi = &pos->fds[i];
+      if (0 != (GNUNET_SCHEDULER_ET_IN & fdi->et))
+      {
+        GNUNET_NETWORK_fdset_set_native (sh->rs,
+                                         fdi->sock);
+      }
+      if (0 != (GNUNET_SCHEDULER_ET_OUT & fdi->et))
+      {
+        GNUNET_NETWORK_fdset_set_native (sh->ws,
+                                         fdi->sock);
+      }
+    }
+    tc.read_ready = sh->rs;
+    tc.write_ready = sh->ws;
     LOG (GNUNET_ERROR_TYPE_DEBUG,
-         "Running task: %p\n",
-         pos);
+         "Running task %p\n",
+         pos);
+    GNUNET_assert (NULL != pos->callback);
     pos->callback (pos->callback_cls);
+    if (NULL != pos->fds)
+    {
+      int del_result = scheduler_driver->del (scheduler_driver->cls, pos);
+      if (GNUNET_OK != del_result)
+      {
+        LOG (GNUNET_ERROR_TYPE_ERROR,
+             "driver could not delete task\n");
+        GNUNET_assert (0);
+      }
+    }
     active_task = NULL;
     dump_backtrace (pos);
     destroy_task (pos);
     tasks_run++;
   }
+  shutdown_if_no_lifeness ();
   if (0 == ready_count)
+  {
+    scheduler_driver->set_wakeup (scheduler_driver->cls,
+                                  get_timeout ());
     return GNUNET_NO;
+  }
+  scheduler_driver->set_wakeup (scheduler_driver->cls,
+                                GNUNET_TIME_absolute_get ()); 
   return GNUNET_OK;
 }
 
@@ -1981,8 +2036,8 @@ GNUNET_SCHEDULER_run_from_driver (struct GNUNET_SCHEDULER_Handle *sh)
  */
 int
 GNUNET_SCHEDULER_run_with_driver (const struct GNUNET_SCHEDULER_Driver *driver,
-                                  GNUNET_SCHEDULER_TaskCallback task,
-                                  void *task_cls)
+                                  GNUNET_SCHEDULER_TaskCallback task,
+                                  void *task_cls)
 {
   int ret;
   struct GNUNET_SIGNAL_Context *shc_int;
@@ -1997,7 +2052,6 @@ GNUNET_SCHEDULER_run_with_driver (const struct GNUNET_SCHEDULER_Driver *driver,
 #endif
   struct GNUNET_SCHEDULER_Task tsk;
   const struct GNUNET_DISK_FileHandle *pr;
-  struct GNUNET_SCHEDULER_Handle sh;
 
   /* general set-up */
   GNUNET_assert (NULL == active_task);
@@ -2009,54 +2063,56 @@ GNUNET_SCHEDULER_run_with_driver (const struct GNUNET_SCHEDULER_Driver *driver,
   GNUNET_assert (NULL != shutdown_pipe_handle);
   pr = GNUNET_DISK_pipe_handle (shutdown_pipe_handle,
                                 GNUNET_DISK_PIPE_END_READ);
-  GNUNET_assert (NULL != pr);
   my_pid = getpid ();
+  scheduler_driver = driver;
 
   /* install signal handlers */
   LOG (GNUNET_ERROR_TYPE_DEBUG,
        "Registering signal handlers\n");
   shc_int = GNUNET_SIGNAL_handler_install (SIGINT,
-                                           &sighandler_shutdown);
+             &sighandler_shutdown);
   shc_term = GNUNET_SIGNAL_handler_install (SIGTERM,
-                                            &sighandler_shutdown);
+              &sighandler_shutdown);
 #if (SIGTERM != GNUNET_TERM_SIG)
   shc_gterm = GNUNET_SIGNAL_handler_install (GNUNET_TERM_SIG,
-                                             &sighandler_shutdown);
+               &sighandler_shutdown);
 #endif
 #ifndef MINGW
   shc_pipe = GNUNET_SIGNAL_handler_install (SIGPIPE,
-                                            &sighandler_pipe);
+              &sighandler_pipe);
   shc_quit = GNUNET_SIGNAL_handler_install (SIGQUIT,
-                                            &sighandler_shutdown);
+              &sighandler_shutdown);
   shc_hup = GNUNET_SIGNAL_handler_install (SIGHUP,
-                                           &sighandler_shutdown);
+             &sighandler_shutdown);
 #endif
 
   /* Setup initial tasks */
   current_priority = GNUNET_SCHEDULER_PRIORITY_DEFAULT;
-  current_lifeness = GNUNET_YES;
+  current_lifeness = GNUNET_NO;
   memset (&tsk,
-          0,
-          sizeof (tsk));
+    0,
+    sizeof (tsk));
   active_task = &tsk;
-  tsk.sh = &sh;
+  GNUNET_SCHEDULER_add_now (&GNUNET_OS_install_parent_control_handler,
+                            NULL);
+  GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
+                                  pr,
+                                  &shutdown_cb,
+                                  NULL);
+  current_lifeness = GNUNET_YES;
   GNUNET_SCHEDULER_add_with_reason_and_priority (task,
                                                  task_cls,
                                                  GNUNET_SCHEDULER_REASON_STARTUP,
                                                  GNUNET_SCHEDULER_PRIORITY_DEFAULT);
-  GNUNET_SCHEDULER_add_now_with_lifeness (GNUNET_NO,
-                                          &GNUNET_OS_install_parent_control_handler,
-                                          NULL);
   active_task = NULL;
-  driver->set_wakeup (driver->cls,
-                      GNUNET_TIME_absolute_get ());
-
+  scheduler_driver->set_wakeup (scheduler_driver->cls,
+                                get_timeout ());
   /* begin main event loop */
   sh.rs = GNUNET_NETWORK_fdset_create ();
   sh.ws = GNUNET_NETWORK_fdset_create ();
-  sh.driver = driver;
+  GNUNET_NETWORK_fdset_handle_set (sh.rs, pr);
   ret = driver->loop (driver->cls,
-                      &sh);
+                      &sh);
   GNUNET_NETWORK_fdset_destroy (sh.rs);
   GNUNET_NETWORK_fdset_destroy (sh.ws);
 
@@ -2073,20 +2129,215 @@ GNUNET_SCHEDULER_run_with_driver (const struct GNUNET_SCHEDULER_Driver *driver,
 #endif
   GNUNET_DISK_pipe_close (shutdown_pipe_handle);
   shutdown_pipe_handle = NULL;
+  scheduler_driver = NULL;
   return ret;
 }
 
 
+int
+select_add (void *cls,
+            struct GNUNET_SCHEDULER_Task *task,
+            struct GNUNET_SCHEDULER_FdInfo *fdi)
+{
+  struct DriverContext *context = cls;
+  GNUNET_assert (NULL != context);
+  GNUNET_assert (NULL != task);
+  GNUNET_assert (NULL != fdi);
+  GNUNET_assert (0 != (GNUNET_SCHEDULER_ET_IN & fdi->et) ||
+                 0 != (GNUNET_SCHEDULER_ET_OUT & fdi->et));
+
+  if (!((NULL != fdi->fd) ^ (NULL != fdi->fh)) || (fdi->sock < 0))
+  {
+    /* exactly one out of {fd, hf} must be != NULL and the OS handle must be valid */
+    return GNUNET_SYSERR;
+  }
+
+  struct Scheduled *scheduled = GNUNET_new (struct Scheduled);
+  scheduled->task = task;
+  scheduled->fdi = fdi;
+  scheduled->et = fdi->et;
+
+  GNUNET_CONTAINER_DLL_insert (context->scheduled_head,
+                               context->scheduled_tail,
+                               scheduled);
+  return GNUNET_OK;
+}
+
+
+int
+select_del (void *cls,
+            struct GNUNET_SCHEDULER_Task *task)
+{
+  struct DriverContext *context;
+  struct Scheduled *pos;
+  int ret;
+
+  GNUNET_assert (NULL != cls);
+
+  context = cls;
+  ret = GNUNET_SYSERR;
+  pos = context->scheduled_head;
+  while (NULL != pos)
+  {
+    struct Scheduled *next = pos->next;
+    if (pos->task == task)
+    {
+      GNUNET_CONTAINER_DLL_remove (context->scheduled_head,
+                                   context->scheduled_tail,
+                                   pos);
+      GNUNET_free (pos);
+      ret = GNUNET_OK;
+    }
+    pos = next;
+  }
+  return ret;
+}
+
+
+int
+select_loop (void *cls,
+             struct GNUNET_SCHEDULER_Handle *sh)
+{
+  struct GNUNET_NETWORK_FDSet *rs;
+  struct GNUNET_NETWORK_FDSet *ws;
+  struct DriverContext *context;
+  int select_result;
+  int tasks_ready;
+ 
+  context = cls;
+  GNUNET_assert (NULL != context);
+  rs = GNUNET_NETWORK_fdset_create ();
+  ws = GNUNET_NETWORK_fdset_create ();
+  tasks_ready = GNUNET_NO;
+  while (NULL != context->scheduled_head ||
+         GNUNET_TIME_UNIT_FOREVER_REL.rel_value_us != context->timeout.rel_value_us)
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "select timeout = %s\n",
+         GNUNET_STRINGS_relative_time_to_string (context->timeout, GNUNET_NO));
+
+    GNUNET_NETWORK_fdset_zero (rs);
+    GNUNET_NETWORK_fdset_zero (ws);
+    struct Scheduled *pos;
+    for (pos = context->scheduled_head; NULL != pos; pos = pos->next)
+    {
+      if (0 != (GNUNET_SCHEDULER_ET_IN & pos->et))
+      {
+        GNUNET_NETWORK_fdset_set_native (rs, pos->fdi->sock);
+      }
+      if (0 != (GNUNET_SCHEDULER_ET_OUT & pos->et))
+      {
+        GNUNET_NETWORK_fdset_set_native (ws, pos->fdi->sock);
+      }
+    }
+    if (NULL == scheduler_select)
+    {
+      select_result = GNUNET_NETWORK_socket_select (rs,
+                                                    ws,
+                                                    NULL,
+                                                    context->timeout);
+    }
+    else
+    {
+      select_result = scheduler_select (scheduler_select_cls,
+                                        rs,
+                                        ws,
+                                        NULL,
+                                        context->timeout);
+    }
+    if (select_result == GNUNET_SYSERR)
+    {
+      if (errno == EINTR)
+        continue;
+
+      LOG_STRERROR (GNUNET_ERROR_TYPE_ERROR, "select");
+#ifndef MINGW
+#if USE_LSOF
+      char lsof[512];
+
+      snprintf (lsof, sizeof (lsof), "lsof -p %d", getpid ());
+      (void) close (1);
+      (void) dup2 (2, 1);
+      if (0 != system (lsof))
+        LOG_STRERROR (GNUNET_ERROR_TYPE_WARNING,
+                      "system");
+#endif
+#endif
+#if DEBUG_FDS
+      struct Scheduled *s;
+      for (s = context->scheduled_head; NULL != s; s = s->next)
+      {
+        int flags = fcntl (s->fdi->sock, F_GETFD);
+        if ((flags == -1) && (errno == EBADF))
+        {
+          LOG (GNUNET_ERROR_TYPE_ERROR,
+               "Got invalid file descriptor %d!\n",
+               s->fdi->sock);
+        }
+      }
+#endif
+      GNUNET_assert (0);
+      GNUNET_NETWORK_fdset_destroy (rs);
+      GNUNET_NETWORK_fdset_destroy (ws);
+      return GNUNET_SYSERR;
+    }
+    for (pos = context->scheduled_head; NULL != pos; pos = pos->next)
+    {
+      int is_ready = GNUNET_NO;
+      if (0 != (GNUNET_SCHEDULER_ET_IN & pos->et) &&
+          GNUNET_YES == GNUNET_NETWORK_fdset_test_native (rs, pos->fdi->sock))
+      {
+        pos->fdi->et |= GNUNET_SCHEDULER_ET_IN;
+        is_ready = GNUNET_YES;
+      }
+      if (0 != (GNUNET_SCHEDULER_ET_OUT & pos->et) &&
+          GNUNET_YES == GNUNET_NETWORK_fdset_test_native (ws, pos->fdi->sock))
+      {
+        pos->fdi->et |= GNUNET_SCHEDULER_ET_OUT;
+        is_ready = GNUNET_YES;
+      }
+      if (GNUNET_YES == is_ready)
+      {
+        GNUNET_SCHEDULER_task_ready (pos->task, pos->fdi);
+      }
+    }
+    tasks_ready = GNUNET_SCHEDULER_run_from_driver (sh);
+    GNUNET_assert (GNUNET_SYSERR != tasks_ready);
+  }
+  GNUNET_NETWORK_fdset_destroy (rs);
+  GNUNET_NETWORK_fdset_destroy (ws);
+  return GNUNET_OK; 
+}
+
+
+void
+select_set_wakeup(void *cls,
+                  struct GNUNET_TIME_Absolute dt)
+{
+  struct DriverContext *context = cls;
+  GNUNET_assert (NULL != context);
+ 
+  context->timeout = GNUNET_TIME_absolute_get_remaining (dt);
+}
+
+
 /**
  * Obtain the driver for using select() as the event loop.
  *
  * @return NULL on error
  */
-const struct GNUNET_SCHEDULER_Driver *
+struct GNUNET_SCHEDULER_Driver *
 GNUNET_SCHEDULER_driver_select ()
 {
-  GNUNET_break (0); // not implemented
-  return NULL;
+  struct GNUNET_SCHEDULER_Driver *select_driver;
+  select_driver = GNUNET_new (struct GNUNET_SCHEDULER_Driver);
+
+  select_driver->loop = &select_loop;
+  select_driver->add = &select_add;
+  select_driver->del = &select_del;
+  select_driver->set_wakeup = &select_set_wakeup;
+
+  return select_driver;
 }
 
 
diff --git a/src/util/service.c b/src/util/service.c
index fcdf45a51..b4eb33caa 100644
--- a/src/util/service.c
+++ b/src/util/service.c
@@ -1932,6 +1932,11 @@ do_send (void *cls)
   size_t left;
   const char *buf;
 
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "service: sending message with type %u",
+       ntohs(client->msg->type));
+
+
   client->send_task = NULL;
   buf = (const char *) client->msg;
   left = ntohs (client->msg->size) - client->msg_pos;
@@ -1941,6 +1946,8 @@ do_send (void *cls)
   GNUNET_assert (ret <= (ssize_t) left);
   if (0 == ret)
   {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "no data send");
     GNUNET_MQ_inject_error (client->mq,
                             GNUNET_MQ_ERROR_WRITE);
     return;
@@ -1958,6 +1965,9 @@ do_send (void *cls)
       if (EPIPE != errno)
         GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING,
                              "send");
+      LOG (GNUNET_ERROR_TYPE_DEBUG,
+           "socket send returned with error code %i",
+           errno);
       GNUNET_MQ_inject_error (client->mq,
                               GNUNET_MQ_ERROR_WRITE);
       return;
@@ -2402,7 +2412,7 @@ resume_client_receive (void *cls)
                          GNUNET_YES);
   if (GNUNET_SYSERR == ret)
   {
-    if (NULL != c->drop_task)
+    if (NULL == c->drop_task)
       GNUNET_SERVICE_client_drop (c);
     return;
   }
@@ -2431,6 +2441,7 @@ resume_client_receive (void *cls)
 void
 GNUNET_SERVICE_client_continue (struct GNUNET_SERVICE_Client *c)
 {
+  GNUNET_assert (NULL == c->drop_task);
   GNUNET_assert (GNUNET_YES == c->needs_continue);
   GNUNET_assert (NULL == c->recv_task);
   c->needs_continue = GNUNET_NO;
@@ -2513,6 +2524,24 @@ GNUNET_SERVICE_client_drop (struct GNUNET_SERVICE_Client *c)
 {
   struct GNUNET_SERVICE_Handle *sh = c->sh;
 
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Client dropped: %p (MQ: %p)\n",
+              c,
+              c->mq);
+
+#if EXECINFO
+  void *backtrace_array[MAX_TRACE_DEPTH];
+  int num_backtrace_strings = backtrace (backtrace_array, MAX_TRACE_DEPTH);
+    char **backtrace_strings =
+        backtrace_symbols (backtrace_array,
+         t->num_backtrace_strings);
+    for (unsigned int i = 0; i < num_backtrace_strings; i++)
+      LOG (GNUNET_ERROR_TYPE_DEBUG,
+     "client drop trace %u: %s\n",
+     i,
+     backtrace_strings[i]);
+#endif
+
   if (NULL != c->drop_task)
   {
     /* asked to drop twice! */
diff --git a/src/util/time.c b/src/util/time.c
index 19100ac36..5ffb19ec1 100644
--- a/src/util/time.c
+++ b/src/util/time.c
@@ -693,7 +693,7 @@ GNUNET_TIME_year_to_time (unsigned int year)
   }
   t.tm_year = year - 1900;
   t.tm_mday = 1;
-  t.tm_mon = 1;
+  t.tm_mon = 0;
   t.tm_wday = 1;
   t.tm_yday = 1;
   tp = mktime (&t);