convert fs publish to MQ
[oweals/gnunet.git] / src / core / core_api.c
index 3b5440135d41c9632927d7c916d30bde57fa4654..86c9d38a250eac210636b6131f9c3342d3bcbfa5 100644 (file)
@@ -1,6 +1,6 @@
 /*
      This file is part of GNUnet.
-     (C) 2009, 2010 Christian Grothoff (and other contributing authors)
+     Copyright (C) 2009-2016 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
 
      You should have received a copy of the GNU General Public License
      along with GNUnet; see the file COPYING.  If not, write to the
-     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
-     Boston, MA 02111-1307, USA.
+     Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+     Boston, MA 02110-1301, USA.
 */
-
 /**
  * @file core/core_api.c
  * @brief core service; this is the main API for encrypted P2P
  * @author Christian Grothoff
  */
 #include "platform.h"
+#include "gnunet_util_lib.h"
 #include "gnunet_constants.h"
 #include "gnunet_core_service.h"
 #include "core.h"
 
+#define LOG(kind,...) GNUNET_log_from (kind, "core-api",__VA_ARGS__)
+
 
 /**
- * Information we track for each peer.
+ * Handle for a transmission request.
  */
-struct PeerRecord
+struct GNUNET_CORE_TransmitHandle
 {
 
   /**
-   * We generally do NOT keep peer records in a DLL; this
-   * DLL is only used IF this peer's 'pending_head' message
-   * is ready for transmission.  
-   */
-  struct PeerRecord *prev;
-
-  /**
-   * We generally do NOT keep peer records in a DLL; this
-   * DLL is only used IF this peer's 'pending_head' message
-   * is ready for transmission. 
-   */
-  struct PeerRecord *next;
-
-  /**
-   * Peer the record is about.
+   * Corresponding peer record.
    */
-  struct GNUNET_PeerIdentity peer;
+  struct PeerRecord *peer;
 
   /**
-   * Corresponding core handle.
+   * Function that will be called to get the actual request
+   * (once we are ready to transmit this request to the core).
+   * The function will be called with a NULL buffer to signal
+   * timeout.
    */
-  struct GNUNET_CORE_Handle *ch;
+  GNUNET_CONNECTION_TransmitReadyNotify get_message;
 
   /**
-   * Head of doubly-linked list of pending requests.
-   * Requests are sorted by deadline *except* for HEAD,
-   * which is only modified upon transmission to core.
+   * Closure for @e get_message.
    */
-  struct GNUNET_CORE_TransmitHandle *pending_head;
+  void *get_message_cls;
 
   /**
-   * Tail of doubly-linked list of pending requests.
+   * Deadline for the transmission (the request does not get cancelled
+   * at this time, this is merely how soon the application wants this out).
    */
-  struct GNUNET_CORE_TransmitHandle *pending_tail;
+  struct GNUNET_TIME_Absolute deadline;
 
   /**
-   * Pending callback waiting for peer information, or NULL for none.
+   * When did this request get queued?
    */
-  GNUNET_CORE_PeerConfigurationInfoCallback pcic;
+  struct GNUNET_TIME_Absolute request_time;
 
   /**
-   * Closure for pcic.
+   * How important is this message?
    */
-  void *pcic_cls;
+  enum GNUNET_CORE_Priority priority;
 
   /**
-   * Request information ID for the given pcic (needed in case a
-   * request is cancelled after being submitted to core and a new
-   * one is generated; in this case, we need to avoid matching the
-   * reply to the first (cancelled) request to the second request).
+   * Is corking allowed?
    */
-  uint32_t rim_id;
+  int cork;
 
   /**
-   * ID of timeout task for the 'pending_head' handle
-   * which is the one with the smallest timeout. 
+   * Size of this request.
    */
-  GNUNET_SCHEDULER_TaskIdentifier timeout_task;
+  uint16_t msize;
 
   /**
-   * Current size of the queue of pending requests.
+   * Send message request ID for this request.
    */
-  unsigned int queue_size;
+  uint16_t smr_id;
 
-  /**
-   * SendMessageRequest ID generator for this peer.
-   */
-  uint16_t smr_id_gen;
-  
 };
 
 
 /**
- * Entry in a doubly-linked list of control messages to be transmitted
- * to the core service.  Control messages include traffic allocation,
- * connection requests and of course our initial 'init' request.
- * 
- * The actual message is allocated at the end of this struct.
+ * Information we track for each peer.
  */
-struct ControlMessage
+struct PeerRecord
 {
-  /**
-   * This is a doubly-linked list.
-   */
-  struct ControlMessage *next;
 
   /**
-   * This is a doubly-linked list.
+   * Corresponding CORE handle.
    */
-  struct ControlMessage *prev;
+  struct GNUNET_CORE_Handle *ch;
 
   /**
-   * Function to run after transmission failed/succeeded.
+   * Pending request, if any. 'th->peer' is set to NULL if the
+   * request is not active.
    */
-  GNUNET_CORE_ControlContinuation cont;
-  
+  struct GNUNET_CORE_TransmitHandle th;
+
   /**
-   * Closure for 'cont'.
+   * Peer the record is about.
    */
-  void *cont_cls;
+  struct GNUNET_PeerIdentity peer;
 
   /**
-   * Transmit handle (if one is associated with this ControlMessage), or NULL.
+   * SendMessageRequest ID generator for this peer.
    */
-  struct GNUNET_CORE_TransmitHandle *th;
-};
+  uint16_t smr_id_gen;
 
+};
 
 
 /**
@@ -177,11 +151,6 @@ struct GNUNET_CORE_Handle
    */
   GNUNET_CORE_DisconnectEventHandler disconnects;
 
-  /**
-   * Function to call whenever we're notified about a peer changing status.
-   */  
-  GNUNET_CORE_PeerStatusEventHandler status_events;
-  
   /**
    * Function to call whenever we receive an inbound message.
    */
@@ -195,45 +164,18 @@ struct GNUNET_CORE_Handle
   /**
    * Function handlers for messages of particular type.
    */
-  const struct GNUNET_CORE_MessageHandler *handlers;
+  struct GNUNET_CORE_MessageHandler *handlers;
 
   /**
-   * Our connection to the service.
+   * Our message queue for transmissions to the service.
    */
-  struct GNUNET_CLIENT_Connection *client;
-
-  /**
-   * Handle for our current transmission request.
-   */
-  struct GNUNET_CLIENT_TransmitHandle *cth;
-
-  /**
-   * Head of doubly-linked list of pending requests.
-   */
-  struct ControlMessage *control_pending_head;
-
-  /**
-   * Tail of doubly-linked list of pending requests.
-   */
-  struct ControlMessage *control_pending_tail;
-
-  /**
-   * Head of doubly-linked list of peers that are core-approved
-   * to send their next message.
-   */
-  struct PeerRecord *ready_peer_head;
-
-  /**
-   * Tail of doubly-linked list of peers that are core-approved
-   * to send their next message.
-   */
-  struct PeerRecord *ready_peer_tail;
+  struct GNUNET_MQ_Handle *mq;
 
   /**
    * Hash map listing all of the peers that we are currently
    * connected to.
    */
-  struct GNUNET_CONTAINER_MultiHashMap *peers;
+  struct GNUNET_CONTAINER_MultiPeerMap *peers;
 
   /**
    * Identity of this peer.
@@ -243,23 +185,13 @@ struct GNUNET_CORE_Handle
   /**
    * ID of reconnect task (if any).
    */
-  GNUNET_SCHEDULER_TaskIdentifier reconnect_task;
+  struct GNUNET_SCHEDULER_Task *reconnect_task;
 
   /**
    * Current delay we use for re-trying to connect to core.
    */
   struct GNUNET_TIME_Relative retry_backoff;
 
-  /**
-   * Request information ID generator.
-   */
-  uint32_t rim_id_gen;
-
-  /**
-   * Number of messages we are allowed to queue per target.
-   */
-  unsigned int queue_size;
-
   /**
    * Number of entries in the handlers array.
    */
@@ -283,73 +215,10 @@ struct GNUNET_CORE_Handle
    */
   int currently_down;
 
-};
-
-
-/**
- * Handle for a transmission request.
- */
-struct GNUNET_CORE_TransmitHandle
-{
-
-  /**
-   * We keep active transmit handles in a doubly-linked list.
-   */
-  struct GNUNET_CORE_TransmitHandle *next;
-
-  /**
-   * We keep active transmit handles in a doubly-linked list.
-   */
-  struct GNUNET_CORE_TransmitHandle *prev;
-
-  /**
-   * Corresponding peer record.
-   */
-  struct PeerRecord *peer;
-
-  /**
-   * Corresponding SEND_REQUEST message.  Only non-NULL 
-   * while SEND_REQUEST message is pending.
-   */
-  struct ControlMessage *cm;
-
-  /**
-   * Function that will be called to get the actual request
-   * (once we are ready to transmit this request to the core).
-   * The function will be called with a NULL buffer to signal
-   * timeout.
-   */
-  GNUNET_CONNECTION_TransmitReadyNotify get_message;
-
-  /**
-   * Closure for get_message.
-   */
-  void *get_message_cls;
-
-  /**
-   * Timeout for this handle.
-   */
-  struct GNUNET_TIME_Absolute timeout;
-
-  /**
-   * How important is this message?
-   */
-  uint32_t priority;
-
-  /**
-   * Size of this request.
-   */
-  uint16_t msize;
-
-  /**
-   * Send message request ID for this request.
-   */
-  uint16_t smr_id;
-
   /**
-   * Is corking allowed?
+   * Did we ever get INIT?
    */
-  int cork;
+  int have_init;
 
 };
 
@@ -367,90 +236,56 @@ reconnect (struct GNUNET_CORE_Handle *h);
 /**
  * Task schedule to try to re-connect to core.
  *
- * @param cls the 'struct GNUNET_CORE_Handle'
+ * @param cls the `struct GNUNET_CORE_Handle`
  * @param tc task context
  */
 static void
-reconnect_task (void *cls, 
-               const struct GNUNET_SCHEDULER_TaskContext *tc)
+reconnect_task (void *cls)
 {
   struct GNUNET_CORE_Handle *h = cls;
 
-  h->reconnect_task = GNUNET_SCHEDULER_NO_TASK;
-#if DEBUG_CORE
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-             "Connecting to CORE service after delay\n");
-#endif
+  h->reconnect_task = NULL;
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Connecting to CORE service after delay\n");
   reconnect (h);
 }
 
 
 /**
- * Notify clients about disconnect and free 
- * the entry for connected peer.
+ * Notify clients about disconnect and free the entry for connected
+ * peer.
  *
- * @param cls the 'struct GNUNET_CORE_Handle*'
+ * @param cls the `struct GNUNET_CORE_Handle *`
  * @param key the peer identity (not used)
- * @param value the 'struct PeerRecord' to free.
- * @return GNUNET_YES (continue)
+ * @param value the `struct PeerRecord` to free.
+ * @return #GNUNET_YES (continue)
  */
 static int
 disconnect_and_free_peer_entry (void *cls,
-                               const GNUNET_HashCode *key,
-                               void *value)
+                               const struct GNUNET_PeerIdentity *key,
+                                void *value)
 {
-  static struct GNUNET_BANDWIDTH_Value32NBO zero;
   struct GNUNET_CORE_Handle *h = cls;
   struct GNUNET_CORE_TransmitHandle *th;
   struct PeerRecord *pr = value;
-  GNUNET_CORE_PeerConfigurationInfoCallback pcic;
 
-  while (NULL != (th = pr->pending_head))
-    {
-      GNUNET_CONTAINER_DLL_remove (pr->pending_head,
-                                  pr->pending_tail,
-                                  th);
-      pr->queue_size--;
-      GNUNET_assert (0 == 
-                    th->get_message (th->get_message_cls,
-                                     0, NULL));
-      GNUNET_free (th);
-    }
-  if (NULL != (pcic = pr->pcic))
-    {
-      pr->pcic = NULL;
-      pcic (pr->pcic_cls,
-           &pr->peer,
-           zero,
-           0, 
-           GNUNET_TIME_UNIT_FOREVER_REL,
-           0);
-    }
-  if (pr->timeout_task != GNUNET_SCHEDULER_NO_TASK)
-    {
-      GNUNET_SCHEDULER_cancel (pr->timeout_task);
-      pr->timeout_task = GNUNET_SCHEDULER_NO_TASK;
-    }
-  GNUNET_assert (pr->queue_size == 0);
-  if ( (pr->prev != NULL) ||
-       (pr->next != NULL) ||
-       (h->ready_peer_head == pr) )
-    GNUNET_CONTAINER_DLL_remove (h->ready_peer_head,
-                                h->ready_peer_tail,
-                                pr);
-  if (h->disconnects != NULL)
+  if (NULL != h->disconnects)
     h->disconnects (h->cls,
-                   &pr->peer);    
+                    &pr->peer);
+  /* all requests should have been cancelled, clean up anyway, just in case */
+  th = &pr->th;
+  if (NULL != th->peer)
+  {
+    GNUNET_break (0);
+    th->peer = NULL;
+  }
+  /* done with 'voluntary' cleanups, now on to normal freeing */
   GNUNET_assert (GNUNET_YES ==
-                GNUNET_CONTAINER_multihashmap_remove (h->peers,
-                                                      key,
-                                                      pr));
-  GNUNET_assert (pr->pending_head == NULL);
-  GNUNET_assert (pr->pending_tail == NULL);
-  GNUNET_assert (pr->ch = h);
-  GNUNET_assert (pr->queue_size == 0);
-  GNUNET_assert (pr->timeout_task == GNUNET_SCHEDULER_NO_TASK);
-  GNUNET_free (pr);  
+                 GNUNET_CONTAINER_multipeermap_remove (h->peers,
+                                                       key,
+                                                       pr));
+  GNUNET_assert (pr->ch == h);
+  GNUNET_free (pr);
   return GNUNET_YES;
 }
 
@@ -464,938 +299,570 @@ disconnect_and_free_peer_entry (void *cls,
 static void
 reconnect_later (struct GNUNET_CORE_Handle *h)
 {
-  struct ControlMessage *cm;
-  struct PeerRecord *pr;
-
-  GNUNET_assert (h->reconnect_task == GNUNET_SCHEDULER_NO_TASK);
-  if (h->client != NULL)
-    {
-      GNUNET_CLIENT_disconnect (h->client, GNUNET_NO);
-      h->client = NULL;
-      h->cth = NULL;
-      GNUNET_CONTAINER_multihashmap_iterate (h->peers,
-                                            &disconnect_and_free_peer_entry,
-                                            h);
-    }
-  while (NULL != (pr = h->ready_peer_head))    
-    GNUNET_CONTAINER_DLL_remove (h->ready_peer_head,
-                                h->ready_peer_tail,
-                                pr);
+  GNUNET_assert (NULL == h->reconnect_task);
+  if (NULL != h->mq)
+  {
+    GNUNET_MQ_destroy (h->mq);
+    h->mq = NULL;
+  }
   h->currently_down = GNUNET_YES;
-  h->reconnect_task = GNUNET_SCHEDULER_add_delayed (h->retry_backoff,
-                                                   &reconnect_task,
-                                                   h);
-  while (NULL != (cm = h->control_pending_head))
-    {
-      GNUNET_CONTAINER_DLL_remove (h->control_pending_head,
-                                  h->control_pending_tail,
-                                  cm);
-      if (cm->th != NULL)
-       cm->th->cm = NULL; 
-      if (cm->cont != NULL)
-       cm->cont (cm->cont_cls, GNUNET_NO);
-      GNUNET_free (cm);
-    }
-  GNUNET_assert (h->control_pending_head == NULL);
-  h->retry_backoff = GNUNET_TIME_relative_min (GNUNET_TIME_UNIT_SECONDS,
-                                              h->retry_backoff);
-  h->retry_backoff = GNUNET_TIME_relative_multiply (h->retry_backoff, 2);
+  GNUNET_assert (h->reconnect_task == NULL);
+  h->reconnect_task =
+      GNUNET_SCHEDULER_add_delayed (h->retry_backoff,
+                                    &reconnect_task,
+                                    h);
+  GNUNET_CONTAINER_multipeermap_iterate (h->peers,
+                                         &disconnect_and_free_peer_entry,
+                                         h);
+  h->retry_backoff = GNUNET_TIME_STD_BACKOFF (h->retry_backoff);
 }
 
 
 /**
- * Check the list of pending requests, send the next
- * one to the core.
+ * Generic error handler, called with the appropriate error code and
+ * the same closure specified at the creation of the message queue.
+ * Not every message queue implementation supports an error handler.
  *
- * @param h core handle
- * @param ignore_currently_down transmit message even if not initialized?
+ * @param cls closure, a `struct GNUNET_CORE_Handle *`
+ * @param error error code
  */
 static void
-trigger_next_request (struct GNUNET_CORE_Handle *h,
-                     int ignore_currently_down);
-
+handle_mq_error (void *cls,
+                 enum GNUNET_MQ_Error error)
+{
+  struct GNUNET_CORE_Handle *h = cls;
 
-/**
- * The given request hit its timeout.  Remove from the
- * doubly-linked list and call the respective continuation.
- *
- * @param cls the transmit handle of the request that timed out
- * @param tc context, can be NULL (!)
- */
-static void
-transmission_timeout (void *cls, 
-                     const struct GNUNET_SCHEDULER_TaskContext *tc);
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "MQ ERROR: %d\n",
+              error);
+  reconnect_later (h);
+}
 
 
 /**
- * Send a control message to the peer asking for transmission
- * of the message in the given peer record.
+ * Handle  init  reply message  received  from  CORE service.   Notify
+ * application  that we  are now  connected  to the  CORE.  Also  fake
+ * loopback connection.
  *
- * @param pr peer to request transmission to
+ * @param cls the `struct GNUNET_CORE_Handle`
+ * @param m the init reply
  */
 static void
-request_next_transmission (struct PeerRecord *pr)
+handle_init_reply (void *cls,
+                   const struct InitReplyMessage *m)
 {
-  struct GNUNET_CORE_Handle *h = pr->ch;
-  struct ControlMessage *cm;
-  struct SendMessageRequest *smr;
-  struct GNUNET_CORE_TransmitHandle *th;
+  struct GNUNET_CORE_Handle *h = cls;
+  GNUNET_CORE_StartupCallback init;
+  struct PeerRecord *pr;
 
-  if (pr->timeout_task != GNUNET_SCHEDULER_NO_TASK)
+  GNUNET_break (0 == ntohl (m->reserved));
+  GNUNET_break (GNUNET_YES == h->currently_down);
+  h->currently_down = GNUNET_NO;
+  h->retry_backoff = GNUNET_TIME_UNIT_MILLISECONDS;
+  if (NULL != (init = h->init))
+  {
+    /* mark so we don't call init on reconnect */
+    h->init = NULL;
+    h->me = m->my_identity;
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Connected to core service of peer `%s'.\n",
+         GNUNET_i2s (&h->me));
+    h->have_init = GNUNET_YES;
+    init (h->cls,
+          &h->me);
+  }
+  else
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Successfully reconnected to core service.\n");
+    if (GNUNET_NO == h->have_init)
     {
-      GNUNET_SCHEDULER_cancel (pr->timeout_task);
-      pr->timeout_task = GNUNET_SCHEDULER_NO_TASK;
+      h->me = m->my_identity;
+      h->have_init = GNUNET_YES;
     }
-  if (NULL == (th = pr->pending_head))
+    else
     {
-      trigger_next_request (h, GNUNET_NO);
-      return;
+      GNUNET_break (0 == memcmp (&h->me,
+                                 &m->my_identity,
+                                 sizeof (struct GNUNET_PeerIdentity)));
     }
-  if (th->cm != NULL)
-    return; /* already done */
-  GNUNET_assert (pr->prev == NULL);
-  GNUNET_assert (pr->next == NULL);
-  pr->timeout_task = GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_absolute_get_remaining (th->timeout),
-                                                  &transmission_timeout,
-                                                  pr);
-  cm = GNUNET_malloc (sizeof (struct ControlMessage) + 
-                     sizeof (struct SendMessageRequest));
-  th->cm = cm;
-  cm->th = th;
-  smr = (struct SendMessageRequest*) &cm[1];
-  smr->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_SEND_REQUEST);
-  smr->header.size = htons (sizeof (struct SendMessageRequest));
-  smr->priority = htonl (th->priority);
-  smr->deadline = GNUNET_TIME_absolute_hton (th->timeout);
-  smr->peer = pr->peer;
-  smr->queue_size = htonl (pr->queue_size);
-  smr->size = htons (th->msize);
-  smr->smr_id = htons (th->smr_id = pr->smr_id_gen++);
-  GNUNET_CONTAINER_DLL_insert_after (h->control_pending_head,
-                                    h->control_pending_tail,
-                                    h->control_pending_tail,
-                                    cm);
-#if DEBUG_CORE
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-             "Adding SEND REQUEST for peer `%s' to message queue\n",
-             GNUNET_i2s (&pr->peer));
-#endif
-  trigger_next_request (h, GNUNET_NO);
+  }
+  /* fake 'connect to self' */
+  pr = GNUNET_new (struct PeerRecord);
+  pr->peer = h->me;
+  pr->ch = h;
+  GNUNET_assert (GNUNET_YES ==
+                 GNUNET_CONTAINER_multipeermap_put (h->peers,
+                                                    &h->me,
+                                                    pr,
+                                                    GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
+  if (NULL != h->connects)
+    h->connects (h->cls,
+                 &pr->peer);
 }
 
 
 /**
- * The given request hit its timeout.  Remove from the
- * doubly-linked list and call the respective continuation.
+ * Handle connect message received from CORE service.
+ * Notify the application about the new connection.
  *
- * @param cls the transmit handle of the request that timed out
- * @param tc context, can be NULL (!)
+ * @param cls the `struct GNUNET_CORE_Handle`
+ * @param cnm the connect message
  */
 static void
-transmission_timeout (void *cls, 
-                     const struct GNUNET_SCHEDULER_TaskContext *tc)
+handle_connect_notify (void *cls,
+                       const struct ConnectNotifyMessage *cnm)
 {
-  struct PeerRecord *pr = cls;
-  struct GNUNET_CORE_Handle *h = pr->ch;
-  struct GNUNET_CORE_TransmitHandle *th;
-  
-  pr->timeout_task = GNUNET_SCHEDULER_NO_TASK;
-  th = pr->pending_head;
-  GNUNET_CONTAINER_DLL_remove (pr->pending_head,
-                               pr->pending_tail,
-                               th);
-  pr->queue_size--;
-  if ( (pr->prev != NULL) ||
-       (pr->next != NULL) ||
-       (pr == h->ready_peer_head) )
-    {
-      /* the request that was 'approved' by core was
-        canceled before it could be transmitted; remove
-        us from the 'ready' list */
-      GNUNET_CONTAINER_DLL_remove (h->ready_peer_head,
-                                  h->ready_peer_tail,
-                                  pr);
-    }
-#if DEBUG_CORE
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-             "Signalling timeout of request for transmission to CORE service\n");
-#endif
-  GNUNET_assert (0 == th->get_message (th->get_message_cls, 0, NULL));
-  request_next_transmission (pr);
+  struct GNUNET_CORE_Handle *h = cls;
+  struct PeerRecord *pr;
+
+  GNUNET_break (GNUNET_NO == h->currently_down);
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Received notification about connection from `%s'.\n",
+       GNUNET_i2s (&cnm->peer));
+  if (0 == memcmp (&h->me,
+                   &cnm->peer,
+                   sizeof (struct GNUNET_PeerIdentity)))
+  {
+    /* connect to self!? */
+    GNUNET_break (0);
+    return;
+  }
+  pr = GNUNET_CONTAINER_multipeermap_get (h->peers,
+                                          &cnm->peer);
+  if (NULL != pr)
+  {
+    GNUNET_break (0);
+    reconnect_later (h);
+    return;
+  }
+  pr = GNUNET_new (struct PeerRecord);
+  pr->peer = cnm->peer;
+  pr->ch = h;
+  GNUNET_assert (GNUNET_YES ==
+                 GNUNET_CONTAINER_multipeermap_put (h->peers,
+                                                    &cnm->peer,
+                                                    pr,
+                                                    GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
+  if (NULL != h->connects)
+    h->connects (h->cls,
+                 &pr->peer);
 }
 
 
 /**
- * Transmit the next message to the core service.
+ * Handle disconnect message received from CORE service.
+ * Notify the application about the lost connection.
+ *
+ * @param cls the `struct GNUNET_CORE_Handle`
+ * @param dnm message about the disconnect event
  */
-static size_t
-transmit_message (void *cls,
-                 size_t size, 
-                 void *buf)
+static void
+handle_disconnect_notify (void *cls,
+                          const struct DisconnectNotifyMessage * dnm)
 {
   struct GNUNET_CORE_Handle *h = cls;
-  struct ControlMessage *cm;
-  struct GNUNET_CORE_TransmitHandle *th;
   struct PeerRecord *pr;
-  struct SendMessage *sm;
-  const struct GNUNET_MessageHeader *hdr;
-  uint16_t msize;
-  size_t ret;
 
-  GNUNET_assert (h->reconnect_task == GNUNET_SCHEDULER_NO_TASK);
-  h->cth = NULL;
-  if (buf == NULL)
-    {
-#if DEBUG_CORE
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                 "Transmission failed, initiating reconnect\n");
-#endif
-      reconnect_later (h);
-      return 0;
-    }
-  /* first check for control messages */
-  if (NULL != (cm = h->control_pending_head))
-    {
-      hdr = (const struct GNUNET_MessageHeader*) &cm[1];
-      msize = ntohs (hdr->size);
-      if (size < msize)
-       {
-         trigger_next_request (h, GNUNET_NO);
-         return 0;
-       }
-#if DEBUG_CORE
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                 "Transmitting control message with %u bytes of type %u to core.\n",
-                 (unsigned int) msize,
-                 (unsigned int) ntohs (hdr->type));
-#endif
-      memcpy (buf, hdr, msize);
-      GNUNET_CONTAINER_DLL_remove (h->control_pending_head,
-                                  h->control_pending_tail,
-                                  cm);     
-      if (cm->th != NULL)
-       cm->th->cm = NULL;
-      if (NULL != cm->cont)
-       cm->cont (cm->cont_cls, GNUNET_OK);
-      GNUNET_free (cm);
-      trigger_next_request (h, GNUNET_NO);
-      return msize;
-    }
-  /* now check for 'ready' P2P messages */
-  if (NULL != (pr = h->ready_peer_head))
-    {
-      GNUNET_assert (pr->pending_head != NULL);
-      th = pr->pending_head;
-      if (size < th->msize + sizeof (struct SendMessage))
-       {
-         trigger_next_request (h, GNUNET_NO);
-         return 0;
-       }
-      GNUNET_CONTAINER_DLL_remove (h->ready_peer_head,
-                                  h->ready_peer_tail,
-                                  pr);
-      GNUNET_CONTAINER_DLL_remove (pr->pending_head,
-                                  pr->pending_tail,
-                                  th);
-      pr->queue_size--;
-      if (pr->timeout_task != GNUNET_SCHEDULER_NO_TASK)
-       {
-         GNUNET_SCHEDULER_cancel (pr->timeout_task);
-         pr->timeout_task = GNUNET_SCHEDULER_NO_TASK;
-       }
-#if DEBUG_CORE
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                 "Transmitting SEND request to `%s' with %u bytes.\n",
-                 GNUNET_i2s (&pr->peer),
-                 (unsigned int) th->msize);
-#endif
-      sm = (struct SendMessage *) buf;
-      sm->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_SEND);
-      sm->priority = htonl (th->priority);
-      sm->deadline = GNUNET_TIME_absolute_hton (th->timeout);
-      sm->peer = pr->peer;
-      sm->cork = htonl ((uint32_t) th->cork);
-      sm->reserved = htonl (0);
-      ret = th->get_message (th->get_message_cls,
-                            size - sizeof (struct SendMessage),
-                            &sm[1]);
-
-      if (0 == ret)
-       {
-#if DEBUG_CORE
-         GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                     "Size of clients message to peer %s is 0!\n",
-                     GNUNET_i2s(&pr->peer));
-#endif
-         /* client decided to send nothing! */
-         request_next_transmission (pr);
-         return 0;       
-       }
-#if DEBUG_CORE
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                 "Produced SEND message to core with %u bytes payload\n",
-                 (unsigned int) ret);
-#endif
-      GNUNET_assert (ret >= sizeof (struct GNUNET_MessageHeader));
-      if (ret + sizeof (struct SendMessage) >= GNUNET_SERVER_MAX_MESSAGE_SIZE)
-       {
-         GNUNET_break (0);
-         request_next_transmission (pr);
-         return 0;
-       }
-      ret += sizeof (struct SendMessage);
-      sm->header.size = htons (ret);
-      GNUNET_assert (ret <= size);
-      GNUNET_free (th);
-      request_next_transmission (pr);
-      return ret;
-    }
-  return 0;
+  GNUNET_break (GNUNET_NO == h->currently_down);
+  if (0 == memcmp (&h->me,
+                   &dnm->peer,
+                   sizeof (struct GNUNET_PeerIdentity)))
+  {
+    /* connection to self!? */
+    GNUNET_break (0);
+    return;
+  }
+  GNUNET_break (0 == ntohl (dnm->reserved));
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Received notification about disconnect from `%s'.\n",
+       GNUNET_i2s (&dnm->peer));
+  pr = GNUNET_CONTAINER_multipeermap_get (h->peers,
+                                          &dnm->peer);
+  if (NULL == pr)
+  {
+    GNUNET_break (0);
+    reconnect_later (h);
+    return;
+  }
+  disconnect_and_free_peer_entry (h,
+                                  &dnm->peer,
+                                  pr);
 }
 
 
 /**
- * Check the list of pending requests, send the next
- * one to the core.
+ * Check that message received from CORE service is well-formed.
  *
- * @param h core handle
- * @param ignore_currently_down transmit message even if not initialized?
+ * @param cls the `struct GNUNET_CORE_Handle`
+ * @param ntm the message we got
+ * @return #GNUNET_OK if the message is well-formed
  */
-static void
-trigger_next_request (struct GNUNET_CORE_Handle *h,
-                     int ignore_currently_down)
+static int
+check_notify_inbound (void *cls,
+                      const struct NotifyTrafficMessage *ntm)
 {
+  struct GNUNET_CORE_Handle *h = cls;
   uint16_t msize;
+  const struct GNUNET_MessageHeader *em;
 
-  if ( (GNUNET_YES == h->currently_down) &&
-       (ignore_currently_down == GNUNET_NO) )
-    {
-#if DEBUG_CORE
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                 "Core connection down, not processing queue\n");
-#endif
-      return;
-    }
-  if (NULL != h->cth)
-    {
-#if DEBUG_CORE
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                 "Request pending, not processing queue\n");
-#endif
-      return;
-    }
-  if (h->control_pending_head != NULL)
-    msize = ntohs (((struct GNUNET_MessageHeader*) &h->control_pending_head[1])->size);    
-  else if (h->ready_peer_head != NULL) 
-    msize = h->ready_peer_head->pending_head->msize + sizeof (struct SendMessage);    
-  else
-    {
-#if DEBUG_CORE
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                 "Request queue empty, not processing queue\n");
-#endif
-      return; /* no pending message */
-    }
-  h->cth = GNUNET_CLIENT_notify_transmit_ready (h->client,
-                                               msize,
-                                               GNUNET_TIME_UNIT_FOREVER_REL,
-                                               GNUNET_NO,
-                                               &transmit_message, h);
+  GNUNET_break (GNUNET_NO == h->currently_down);
+  msize = ntohs (ntm->header.size) - sizeof (struct NotifyTrafficMessage);
+  if (msize < sizeof (struct GNUNET_MessageHeader))
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  em = (const struct GNUNET_MessageHeader *) &ntm[1];
+  if ( (GNUNET_NO == h->inbound_hdr_only) &&
+       (msize != ntohs (em->size)) )
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  return GNUNET_OK;
 }
 
 
 /**
- * Handler for notification messages received from the core.
+ * Handle inbound message received from CORE service.  If applicable,
+ * notify the application.
  *
- * @param cls our "struct GNUNET_CORE_Handle"
- * @param msg the message received from the core service
+ * @param cls the `struct GNUNET_CORE_Handle`
+ * @param ntm the message we got from CORE.
  */
 static void
-main_notify_handler (void *cls, 
-                    const struct GNUNET_MessageHeader *msg)
+handle_notify_inbound (void *cls,
+                       const struct NotifyTrafficMessage *ntm)
 {
   struct GNUNET_CORE_Handle *h = cls;
-  const struct InitReplyMessage *m;
-  const struct ConnectNotifyMessage *cnm;
-  const struct DisconnectNotifyMessage *dnm;
-  const struct NotifyTrafficMessage *ntm;
   const struct GNUNET_MessageHeader *em;
-  const struct ConfigurationInfoMessage *cim;
-  const struct PeerStatusNotifyMessage *psnm;
-  const struct SendMessageReady *smr;
-  const struct GNUNET_CORE_MessageHandler *mh;
-  GNUNET_CORE_StartupCallback init;
-  GNUNET_CORE_PeerConfigurationInfoCallback pcic;
   struct PeerRecord *pr;
-  struct GNUNET_CORE_TransmitHandle *th;
-  unsigned int hpos;
-  int trigger;
-  uint16_t msize;
   uint16_t et;
-  uint32_t ats_count;
 
-  if (msg == NULL)
+  GNUNET_break (GNUNET_NO == h->currently_down);
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Received inbound message from `%s'.\n",
+       GNUNET_i2s (&ntm->peer));
+  em = (const struct GNUNET_MessageHeader *) &ntm[1];
+  et = ntohs (em->type);
+  for (unsigned int hpos = 0; NULL != h->handlers[hpos].callback; hpos++)
+  {
+    const struct GNUNET_CORE_MessageHandler *mh;
+
+    mh = &h->handlers[hpos];
+    if (mh->type != et)
+      continue;
+    if ( (mh->expected_size != ntohs (em->size)) &&
+         (0 != mh->expected_size) )
+    {
+      LOG (GNUNET_ERROR_TYPE_ERROR,
+           "Unexpected message size %u for message of type %u from peer `%s'\n",
+           htons (em->size),
+           mh->type,
+           GNUNET_i2s (&ntm->peer));
+      GNUNET_break_op (0);
+      continue;
+    }
+    pr = GNUNET_CONTAINER_multipeermap_get (h->peers,
+                                            &ntm->peer);
+    if (NULL == pr)
     {
-      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
-                  _
-                  ("Client was disconnected from core service, trying to reconnect.\n"));
+      GNUNET_break (0);
       reconnect_later (h);
       return;
     }
-  msize = ntohs (msg->size);
-#if DEBUG_CORE
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-              "Processing message of type %u and size %u from core service\n",
-              ntohs (msg->type), msize);
-#endif
-  switch (ntohs (msg->type))
+    if (GNUNET_OK !=
+        h->handlers[hpos].callback (h->cls,
+                                    &ntm->peer,
+                                    em))
     {
-    case GNUNET_MESSAGE_TYPE_CORE_INIT_REPLY:
-      if (ntohs (msg->size) != sizeof (struct InitReplyMessage))
-       {
-         GNUNET_break (0);
-         reconnect_later (h);
-         return;
-       }
-      m = (const struct InitReplyMessage *) msg;
-      GNUNET_break (0 == ntohl (m->reserved));
-      /* start our message processing loop */
-      if (GNUNET_YES == h->currently_down)
-       {
-         h->currently_down = GNUNET_NO;
-         trigger_next_request (h, GNUNET_NO);
-       }
-      h->retry_backoff = GNUNET_TIME_UNIT_MILLISECONDS;
-      GNUNET_CRYPTO_hash (&m->publicKey,
-                         sizeof (struct
-                                 GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded),
-                         &h->me.hashPubKey);
-      if (NULL != (init = h->init))
-       {
-         /* mark so we don't call init on reconnect */
-         h->init = NULL;
-#if DEBUG_CORE
-         GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                     "Connected to core service of peer `%s'.\n",
-                     GNUNET_i2s (&h->me));
-#endif
-         init (h->cls, h, &h->me, &m->publicKey);
-       }
-      else
-       {
-#if DEBUG_CORE
-         GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                     "Successfully reconnected to core service.\n");
-#endif
-       }
-      /* fake 'connect to self' */
-      pr = GNUNET_CONTAINER_multihashmap_get (h->peers,
-                                             &h->me.hashPubKey);
-      GNUNET_assert (pr == NULL);
-      pr = GNUNET_malloc (sizeof (struct PeerRecord));
-      pr->peer = h->me;
-      pr->ch = h;
-      GNUNET_assert (GNUNET_YES ==
-                    GNUNET_CONTAINER_multihashmap_put (h->peers,
-                                                       &h->me.hashPubKey,
-                                                       pr,
-                                                       GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST));
-      if (NULL != h->connects)
-       h->connects (h->cls,
-                    &h->me,
-                    NULL);
-      break;
-    case GNUNET_MESSAGE_TYPE_CORE_NOTIFY_CONNECT:
-      if (msize < sizeof (struct ConnectNotifyMessage))
-        {
-          GNUNET_break (0);
-         reconnect_later (h);
-         return;
-        }
-      cnm = (const struct ConnectNotifyMessage *) msg;
-      ats_count = ntohl (cnm->ats_count);
-      if ( (msize != sizeof (struct ConnectNotifyMessage) + ats_count * sizeof (struct GNUNET_TRANSPORT_ATS_Information)) ||
-          (GNUNET_TRANSPORT_ATS_ARRAY_TERMINATOR != ntohl ((&cnm->ats)[ats_count].type)) )
-        {
-          GNUNET_break (0);
-         reconnect_later (h);
-         return;
-        }
-#if DEBUG_CORE
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                 "Received notification about connection from `%s'.\n",
-                 GNUNET_i2s (&cnm->peer));
-#endif
-      if (0 == memcmp (&h->me,
-                      &cnm->peer,
-                      sizeof (struct GNUNET_PeerIdentity)))
-       {
-         /* connect to self!? */
-         GNUNET_break (0);
-         return;
-       }
-      pr = GNUNET_CONTAINER_multihashmap_get (h->peers,
-                                             &cnm->peer.hashPubKey);
-      if (pr != NULL)
-       {
-         GNUNET_break (0);
-         reconnect_later (h);
-         return;
-       }
-      pr = GNUNET_malloc (sizeof (struct PeerRecord));
-      pr->peer = cnm->peer;
-      pr->ch = h;
-      GNUNET_assert (GNUNET_YES ==
-                    GNUNET_CONTAINER_multihashmap_put (h->peers,
-                                                       &cnm->peer.hashPubKey,
-                                                       pr,
-                                                       GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST));
-      if (NULL != h->connects)
-       h->connects (h->cls,
-                    &cnm->peer,
-                    &cnm->ats);
-      break;
-    case GNUNET_MESSAGE_TYPE_CORE_NOTIFY_DISCONNECT:
-      if (msize != sizeof (struct DisconnectNotifyMessage))
-        {
-          GNUNET_break (0);
-         reconnect_later (h);
-         return;
-        }
-      dnm = (const struct DisconnectNotifyMessage *) msg;
-      if (0 == memcmp (&h->me,
-                      &dnm->peer,
-                      sizeof (struct GNUNET_PeerIdentity)))
-       {
-         /* connection to self!? */
-         GNUNET_break (0);
-         return;
-       }
-      GNUNET_break (0 == ntohl (dnm->reserved));
-#if DEBUG_CORE
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                 "Received notification about disconnect from `%s'.\n",
-                 GNUNET_i2s (&dnm->peer));
-#endif
-      pr = GNUNET_CONTAINER_multihashmap_get (h->peers,
-                                             &dnm->peer.hashPubKey);
-      if (pr == NULL)
-       {
-         GNUNET_break (0);
-         reconnect_later (h);
-         return;
-       }
-      trigger = ( (pr->prev != NULL) ||
-                 (pr->next != NULL) ||
-                 (h->ready_peer_head == pr) );
-      disconnect_and_free_peer_entry (h, &dnm->peer.hashPubKey, pr);
-      if (trigger)
-       trigger_next_request (h, GNUNET_NO);
-      break;
-    case GNUNET_MESSAGE_TYPE_CORE_NOTIFY_STATUS_CHANGE:
-      if (NULL == h->status_events)
-        {
-          GNUNET_break (0);
-        }
-      if (msize < sizeof (struct PeerStatusNotifyMessage))
-        {
-          GNUNET_break (0);
-         reconnect_later (h);
-         return;
-        }
-      psnm = (const struct PeerStatusNotifyMessage *) msg;
-      if (0 == memcmp (&h->me,
-                      &psnm->peer,
-                      sizeof (struct GNUNET_PeerIdentity)))
-       {
-         /* self-change!? */
-         GNUNET_break (0);
-         return;
-       }
-      ats_count = ntohl (psnm->ats_count);
-      if ( (msize != sizeof (struct PeerStatusNotifyMessage) + ats_count * sizeof (struct GNUNET_TRANSPORT_ATS_Information)) ||
-          (GNUNET_TRANSPORT_ATS_ARRAY_TERMINATOR != ntohl ((&psnm->ats)[ats_count].type)) )
-        {
-          GNUNET_break (0);
-         reconnect_later (h);
-         return;
-        }
-#if DEBUG_CORE
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                 "Received notification about status change by `%s'.\n",
-                 GNUNET_i2s (&psnm->peer));
-#endif
-      pr = GNUNET_CONTAINER_multihashmap_get (h->peers,
-                                             &psnm->peer.hashPubKey);
-      if (pr == NULL)
-       {
-         GNUNET_break (0);
-         reconnect_later (h);
-         return;
-       }
-      h->status_events (h->cls,
-                       &psnm->peer,
-                       psnm->bandwidth_in,
-                       psnm->bandwidth_out,
-                       GNUNET_TIME_absolute_ntoh (psnm->timeout),
-                       &psnm->ats);
+      /* error in processing, do not process other messages! */
       break;
-    case GNUNET_MESSAGE_TYPE_CORE_NOTIFY_INBOUND:
-      if (msize < sizeof (struct NotifyTrafficMessage))
-        {
-          GNUNET_break (0);
-         reconnect_later (h);
-         return;
-        }
-      ntm = (const struct NotifyTrafficMessage *) msg;
-
-      ats_count = ntohl (ntm->ats_count);
-      if ( (msize < sizeof (struct NotifyTrafficMessage) + ats_count * sizeof (struct GNUNET_TRANSPORT_ATS_Information)
-           + sizeof (struct GNUNET_MessageHeader)) ||
-          (GNUNET_TRANSPORT_ATS_ARRAY_TERMINATOR != ntohl ((&ntm->ats)[ats_count].type)) )
-        {
-          GNUNET_break (0);
-         reconnect_later (h);
-         return;
-        }
-      em = (const struct GNUNET_MessageHeader *) &(&ntm->ats)[ats_count+1];
-#if DEBUG_CORE
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                  "Received message of type %u and size %u from peer `%4s'\n",
-                  ntohs (em->type), 
-                 ntohs (em->size),
-                 GNUNET_i2s (&ntm->peer));
-#endif
-      pr = GNUNET_CONTAINER_multihashmap_get (h->peers,
-                                             &ntm->peer.hashPubKey);
-      if (pr == NULL)
-       {
-         GNUNET_break (0);
-         reconnect_later (h);
-         return;
-       }
-      if ((GNUNET_NO == h->inbound_hdr_only) &&
-          (msize != ntohs (em->size) + sizeof (struct NotifyTrafficMessage) + 
-          + ats_count * sizeof (struct GNUNET_TRANSPORT_ATS_Information)) )
-        {
-          GNUNET_break (0);
-         reconnect_later (h);
-         return;
-        }
-      et = ntohs (em->type);
-      for (hpos = 0; hpos < h->hcnt; hpos++)
-        {
-          mh = &h->handlers[hpos];
-          if (mh->type != et)
-            continue;
-          if ((mh->expected_size != ntohs (em->size)) &&
-              (mh->expected_size != 0))
-            {
-              GNUNET_break (0);
-              continue;
-            }
-          if (GNUNET_OK !=
-              h->handlers[hpos].callback (h->cls, &ntm->peer, em,
-                                         &ntm->ats))
-            {
-              /* error in processing, do not process other messages! */
-              break;
-            }
-        }
-      if (NULL != h->inbound_notify)
-        h->inbound_notify (h->cls, &ntm->peer, em,
-                          &ntm->ats);
-      break;
-    case GNUNET_MESSAGE_TYPE_CORE_NOTIFY_OUTBOUND:
-      if (msize < sizeof (struct NotifyTrafficMessage))
-        {
-          GNUNET_break (0);
-         reconnect_later (h);
-         return;
-        }
-      ntm = (const struct NotifyTrafficMessage *) msg;
-      if (0 == memcmp (&h->me,
-                      &ntm->peer,
-                      sizeof (struct GNUNET_PeerIdentity)))
-       {
-         /* self-change!? */
-         GNUNET_break (0);
-         return;
-       }
-      ats_count = ntohl (ntm->ats_count);
-      if ( (msize < sizeof (struct NotifyTrafficMessage) + ats_count * sizeof (struct GNUNET_TRANSPORT_ATS_Information)
-           + sizeof (struct GNUNET_MessageHeader)) ||
-          (GNUNET_TRANSPORT_ATS_ARRAY_TERMINATOR != ntohl ((&ntm->ats)[ats_count].type)) )
-        {
-          GNUNET_break (0);
-         reconnect_later (h);
-         return;
-        }
-      em = (const struct GNUNET_MessageHeader *) &(&ntm->ats)[ats_count+1];
-      pr = GNUNET_CONTAINER_multihashmap_get (h->peers,
-                                             &ntm->peer.hashPubKey);
-      if (pr == NULL)
-       {
-         GNUNET_break (0);
-         reconnect_later (h);
-         return;
-       }
-#if DEBUG_CORE
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                 "Received notification about transmission to `%s'.\n",
-                 GNUNET_i2s (&ntm->peer));
-#endif
-      if ((GNUNET_NO == h->outbound_hdr_only) &&
-          (msize != ntohs (em->size) + sizeof (struct NotifyTrafficMessage) 
-          + ats_count * sizeof (struct GNUNET_TRANSPORT_ATS_Information)) )
-        {
-          GNUNET_break (0);
-         reconnect_later (h);
-         return;
-        }
-      if (NULL == h->outbound_notify)
-        {
-          GNUNET_break (0);
-          break;
-        }
-      h->outbound_notify (h->cls, &ntm->peer, em,
-                         &ntm->ats);
-      break;
-    case GNUNET_MESSAGE_TYPE_CORE_SEND_READY:
-      if (msize != sizeof (struct SendMessageReady))
-        {
-          GNUNET_break (0);
-         reconnect_later (h);
-         return;
-        }
-      smr = (const struct SendMessageReady *) msg;
-      pr = GNUNET_CONTAINER_multihashmap_get (h->peers,
-                                             &smr->peer.hashPubKey);
-      if (pr == NULL)
-       {
-         GNUNET_break (0);
-         reconnect_later (h);
-         return;
-       }
-#if DEBUG_CORE
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                 "Received notification about transmission readiness to `%s'.\n",
-                 GNUNET_i2s (&smr->peer));
-#endif
-      if (pr->pending_head == NULL)
-        {
-         /* request must have been cancelled between the original request
-            and the response from core, ignore core's readiness */
-          return;
-        }
-
-      th = pr->pending_head;
-      if (ntohs (smr->smr_id) != th->smr_id)
-       {
-         /* READY message is for expired or cancelled message,
-            ignore! (we should have already sent another request) */
-         break;
-       }
-      if ( (pr->prev != NULL) ||
-          (pr->next != NULL) ||
-          (h->ready_peer_head == pr) )
-       {
-         /* we should not already be on the ready list... */
-         GNUNET_break (0);
-         reconnect_later (h);
-         return;
-       }
-      GNUNET_CONTAINER_DLL_insert (h->ready_peer_head,
-                                  h->ready_peer_tail,
-                                  pr);
-      trigger_next_request (h, GNUNET_NO);
-      break;
-    case GNUNET_MESSAGE_TYPE_CORE_CONFIGURATION_INFO:
-      if (ntohs (msg->size) != sizeof (struct ConfigurationInfoMessage))
-       {
-         GNUNET_break (0);
-         reconnect_later (h);
-         return;
-       }
-      cim = (const struct ConfigurationInfoMessage*) msg;
-      if (0 == memcmp (&h->me,
-                      &cim->peer,
-                      sizeof (struct GNUNET_PeerIdentity)))
-       {
-         /* self-change!? */
-         GNUNET_break (0);
-         return;
-       }
-#if DEBUG_CORE
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                 "Received notification about configuration update for `%s'.\n",
-                 GNUNET_i2s (&cim->peer));
-#endif
-      pr = GNUNET_CONTAINER_multihashmap_get (h->peers,
-                                             &cim->peer.hashPubKey);
-      if (pr == NULL)
-       {
-         GNUNET_break (0);
-         reconnect_later (h);
-         return;
-       }
-      if (pr->rim_id != ntohl (cim->rim_id))
-       {
-#if DEBUG_CORE
-         GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                     "Reservation ID mismatch in notification...\n");
-#endif
-         break;
-       }
-      pcic = pr->pcic;
-      pr->pcic = NULL;
-      if (pcic != NULL)
-       pcic (pr->pcic_cls,
-             &pr->peer,
-             cim->bw_out,
-             ntohl (cim->reserved_amount),
-             GNUNET_TIME_relative_ntoh (cim->reserve_delay),
-             GNUNET_ntohll (cim->preference));
-      break;
-    default:
-      reconnect_later (h);
-      return;
     }
-  GNUNET_CLIENT_receive (h->client,
-                        &main_notify_handler, h, 
-                        GNUNET_TIME_UNIT_FOREVER_REL);
+  }
+  if (NULL != h->inbound_notify)
+    h->inbound_notify (h->cls,
+                       &ntm->peer,
+                       em);
+}
+
+
+/**
+ * Check that message received from CORE service is well-formed.
+ *
+ * @param cls the `struct GNUNET_CORE_Handle`
+ * @param ntm the message we got
+ * @return #GNUNET_OK if the message is well-formed
+ */
+static int
+check_notify_outbound (void *cls,
+                       const struct NotifyTrafficMessage *ntm)
+{
+  struct GNUNET_CORE_Handle *h = cls;
+  uint16_t msize;
+  const struct GNUNET_MessageHeader *em;
+
+  GNUNET_break (GNUNET_NO == h->currently_down);
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Received outbound message from `%s'.\n",
+       GNUNET_i2s (&ntm->peer));
+  msize = ntohs (ntm->header.size) - sizeof (struct NotifyTrafficMessage);
+  if (msize < sizeof (struct GNUNET_MessageHeader))
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  em = (const struct GNUNET_MessageHeader *) &ntm[1];
+  if ( (GNUNET_NO == h->outbound_hdr_only) &&
+       (msize != ntohs (em->size)) )
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  return GNUNET_OK;
 }
 
 
 /**
- * Task executed once we are done transmitting the INIT message.
- * Starts our 'receive' loop.
+ * Handle outbound message received from CORE service.  If applicable,
+ * notify the application.
  *
- * @param cls the 'struct GNUNET_CORE_Handle'
- * @param success were we successful
+ * @param cls the `struct GNUNET_CORE_Handle`
+ * @param ntm the message we got
  */
 static void
-init_done_task (void *cls, 
-               int success)
+handle_notify_outbound (void *cls,
+                        const struct NotifyTrafficMessage *ntm)
 {
   struct GNUNET_CORE_Handle *h = cls;
+  const struct GNUNET_MessageHeader *em;
 
-  if (success == GNUNET_SYSERR)
-    return; /* shutdown */
-  if (success == GNUNET_NO)
-    {
-#if DEBUG_CORE
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                 "Failed to exchange INIT with core, retrying\n");
-#endif
-      if (h->reconnect_task == GNUNET_SCHEDULER_NO_TASK)
-       reconnect_later (h);
-      return;
-    }
-  GNUNET_CLIENT_receive (h->client,
-                         &main_notify_handler, 
-                        h, 
-                        GNUNET_TIME_UNIT_FOREVER_REL);
+  GNUNET_break (GNUNET_NO == h->currently_down);
+  em = (const struct GNUNET_MessageHeader *) &ntm[1];
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Received notification about transmission to `%s'.\n",
+       GNUNET_i2s (&ntm->peer));
+  if (NULL == h->outbound_notify)
+  {
+    GNUNET_break (0);
+    return;
+  }
+  h->outbound_notify (h->cls,
+                      &ntm->peer,
+                      em);
 }
 
 
 /**
- * Our current client connection went down.  Clean it up
- * and try to reconnect!
+ * Handle message received from CORE service notifying us that we are
+ * now allowed to send a message to a peer.  If that message is still
+ * pending, put it into the queue to be transmitted.
+ *
+ * @param cls the `struct GNUNET_CORE_Handle`
+ * @param ntm the message we got
+ */
+static void
+handle_send_ready (void *cls,
+                   const struct SendMessageReady *smr)
+{
+  struct GNUNET_CORE_Handle *h = cls;
+  struct PeerRecord *pr;
+  struct GNUNET_CORE_TransmitHandle *th;
+  struct SendMessage *sm;
+  struct GNUNET_MQ_Envelope *env;
+  struct GNUNET_TIME_Relative delay;
+  struct GNUNET_TIME_Relative overdue;
+  unsigned int ret;
+
+  GNUNET_break (GNUNET_NO == h->currently_down);
+  pr = GNUNET_CONTAINER_multipeermap_get (h->peers,
+                                          &smr->peer);
+  if (NULL == pr)
+  {
+    GNUNET_break (0);
+    reconnect_later (h);
+    return;
+  }
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Received notification about transmission readiness to `%s'.\n",
+       GNUNET_i2s (&smr->peer));
+  if (NULL == pr->th.peer)
+  {
+    /* request must have been cancelled between the original request
+     * and the response from CORE, ignore CORE's readiness */
+    return;
+  }
+  th = &pr->th;
+  if (ntohs (smr->smr_id) != th->smr_id)
+  {
+    /* READY message is for expired or cancelled message,
+     * ignore! (we should have already sent another request) */
+    return;
+  }
+  /* ok, all good, send message out! */
+  th->peer = NULL;
+  env = GNUNET_MQ_msg_extra (sm,
+                             th->msize,
+                             GNUNET_MESSAGE_TYPE_CORE_SEND);
+  sm->priority = htonl ((uint32_t) th->priority);
+  sm->deadline = GNUNET_TIME_absolute_hton (th->deadline);
+  sm->peer = pr->peer;
+  sm->cork = htonl ((uint32_t) th->cork);
+  sm->reserved = htonl (0);
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Calling get_message with buffer of %u bytes\n",
+              (unsigned int) th->msize);
+  /* FIXME: this is ugly and a bit brutal, but "get_message"
+     may call GNUNET_CORE_notify_transmit_ready() which
+     may call GNUNET_MQ_send() as well, and we MUST get this
+     message out before the next SEND_REQUEST.  So we queue
+     it (even though incomplete) and then---relying on MQ being
+     nice and not actually touching 'env' until much later---
+     fill it afterwards.  This is horrible style, and once
+     the core_api abandons GNUNET_CORE_notify_transmit_ready
+     in favor of an MQ-style API, this hack should no longer
+     be required */
+  GNUNET_MQ_send (h->mq,
+                  env);
+  ret = th->get_message (th->get_message_cls,
+                         th->msize,
+                         &sm[1]);
+  sm->header.size = htons (ret + sizeof (struct SendMessage));
+  delay = GNUNET_TIME_absolute_get_duration (th->request_time);
+  overdue = GNUNET_TIME_absolute_get_duration (th->deadline);
+  if (overdue.rel_value_us > GNUNET_CONSTANTS_LATENCY_WARN.rel_value_us)
+    LOG (GNUNET_ERROR_TYPE_WARNING,
+         "Transmitting overdue %u bytes to `%s' at priority %u with %s delay %s\n",
+         ret,
+         GNUNET_i2s (&pr->peer),
+         (unsigned int) th->priority,
+         GNUNET_STRINGS_relative_time_to_string (delay,
+                                                 GNUNET_YES),
+         (th->cork) ? " (corked)" : "");
+  else
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Transmitting %u bytes to `%s' at priority %u with %s delay %s\n",
+         ret,
+         GNUNET_i2s (&pr->peer),
+         (unsigned int) th->priority,
+         GNUNET_STRINGS_relative_time_to_string (delay,
+                                                 GNUNET_YES),
+         (th->cork) ? " (corked)" : "");
+}
+
+
+/**
+ * Our current client connection went down.  Clean it up and try to
+ * reconnect!
  *
  * @param h our handle to the core service
  */
 static void
 reconnect (struct GNUNET_CORE_Handle *h)
 {
-  struct ControlMessage *cm;
+  GNUNET_MQ_hd_fixed_size (init_reply,
+                           GNUNET_MESSAGE_TYPE_CORE_INIT_REPLY,
+                           struct InitReplyMessage);
+  GNUNET_MQ_hd_fixed_size (connect_notify,
+                           GNUNET_MESSAGE_TYPE_CORE_NOTIFY_CONNECT,
+                           struct ConnectNotifyMessage);
+  GNUNET_MQ_hd_fixed_size (disconnect_notify,
+                           GNUNET_MESSAGE_TYPE_CORE_NOTIFY_DISCONNECT,
+                           struct DisconnectNotifyMessage);
+  GNUNET_MQ_hd_var_size (notify_inbound,
+                         GNUNET_MESSAGE_TYPE_CORE_NOTIFY_INBOUND,
+                         struct NotifyTrafficMessage);
+  GNUNET_MQ_hd_var_size (notify_outbound,
+                         GNUNET_MESSAGE_TYPE_CORE_NOTIFY_OUTBOUND,
+                         struct NotifyTrafficMessage);
+  GNUNET_MQ_hd_fixed_size (send_ready,
+                           GNUNET_MESSAGE_TYPE_CORE_SEND_READY,
+                           struct SendMessageReady);
+ struct GNUNET_MQ_MessageHandler handlers[] = {
+    make_init_reply_handler (h),
+    make_connect_notify_handler (h),
+    make_disconnect_notify_handler (h),
+    make_notify_inbound_handler (h),
+    make_notify_outbound_handler (h),
+    make_send_ready_handler (h),
+    GNUNET_MQ_handler_end ()
+  };
   struct InitMessage *init;
+  struct GNUNET_MQ_Envelope *env;
   uint32_t opt;
-  uint16_t msize;
   uint16_t *ts;
-  unsigned int hpos;
 
-#if DEBUG_CORE
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-             "Reconnecting to CORE service\n");
-#endif
-  GNUNET_assert (h->client == NULL);
-  GNUNET_assert (h->currently_down == GNUNET_YES);
-  h->client = GNUNET_CLIENT_connect ("core", h->cfg);
-  if (h->client == NULL)
-    {
-      reconnect_later (h);
-      return;
-    }
-  msize = h->hcnt * sizeof (uint16_t) + sizeof (struct InitMessage);
-  cm = GNUNET_malloc (sizeof (struct ControlMessage) +
-                     msize);
-  cm->cont = &init_done_task;
-  cm->cont_cls = h;
-  init = (struct InitMessage*) &cm[1];
-  init->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_INIT);
-  init->header.size = htons (msize);
-  opt = GNUNET_CORE_OPTION_SEND_CONNECT | GNUNET_CORE_OPTION_SEND_DISCONNECT;
-  if (h->status_events != NULL)
-    opt |= GNUNET_CORE_OPTION_SEND_STATUS_CHANGE;
-  if (h->inbound_notify != NULL)
-    {
-      if (h->inbound_hdr_only)
-        opt |= GNUNET_CORE_OPTION_SEND_HDR_INBOUND;
-      else
-        opt |= GNUNET_CORE_OPTION_SEND_FULL_INBOUND;
-    }
-  if (h->outbound_notify != NULL)
-    {
-      if (h->outbound_hdr_only)
-        opt |= GNUNET_CORE_OPTION_SEND_HDR_OUTBOUND;
-      else
-        opt |= GNUNET_CORE_OPTION_SEND_FULL_OUTBOUND;
-    }
+  GNUNET_assert (NULL == h->mq);
+  GNUNET_assert (GNUNET_YES == h->currently_down);
+  h->mq = GNUNET_CLIENT_connecT (h->cfg,
+                                 "core",
+                                 handlers,
+                                 &handle_mq_error,
+                                 h);
+  if (NULL == h->mq)
+  {
+    reconnect_later (h);
+    return;
+  }
+  env = GNUNET_MQ_msg_extra (init,
+                             sizeof (uint16_t) * h->hcnt,
+                             GNUNET_MESSAGE_TYPE_CORE_INIT);
+  opt = 0;
+  if (NULL != h->inbound_notify)
+  {
+    if (h->inbound_hdr_only)
+      opt |= GNUNET_CORE_OPTION_SEND_HDR_INBOUND;
+    else
+      opt |= GNUNET_CORE_OPTION_SEND_FULL_INBOUND;
+  }
+  if (NULL != h->outbound_notify)
+  {
+    if (h->outbound_hdr_only)
+      opt |= GNUNET_CORE_OPTION_SEND_HDR_OUTBOUND;
+    else
+      opt |= GNUNET_CORE_OPTION_SEND_FULL_OUTBOUND;
+  }
+  LOG (GNUNET_ERROR_TYPE_INFO,
+       "(Re)connecting to CORE service, monitoring messages of type %u\n",
+       opt);
   init->options = htonl (opt);
   ts = (uint16_t *) &init[1];
-  for (hpos = 0; hpos < h->hcnt; hpos++)
+  for (unsigned int hpos = 0; hpos < h->hcnt; hpos++)
     ts[hpos] = htons (h->handlers[hpos].type);
-  GNUNET_CONTAINER_DLL_insert (h->control_pending_head,
-                              h->control_pending_tail,
-                              cm);
-  trigger_next_request (h, GNUNET_YES);
+  GNUNET_MQ_send (h->mq,
+                  env);
 }
 
 
-
 /**
- * Connect to the core service.  Note that the connection may
- * complete (or fail) asynchronously.
+ * Connect to the core service.  Note that the connection may complete
+ * (or fail) asynchronously.
  *
  * @param cfg configuration to use
- * @param queue_size size of the per-peer message queue
  * @param cls closure for the various callbacks that follow (including handlers in the handlers array)
- * @param init callback to call on timeout or once we have successfully
- *        connected to the core service; note that timeout is only meaningful if init is not NULL
+ * @param init callback to call once we have successfully
+ *        connected to the core service
  * @param connects function to call on peer connect, can be NULL
  * @param disconnects function to call on peer disconnect / timeout, can be NULL
- * @param status_events function to call on changes to peer connection status, can be NULL
  * @param inbound_notify function to call for all inbound messages, can be NULL
- * @param inbound_hdr_only set to GNUNET_YES if inbound_notify will only read the
+ * @param inbound_hdr_only set to #GNUNET_YES if inbound_notify will only read the
  *                GNUNET_MessageHeader and hence we do not need to give it the full message;
- *                can be used to improve efficiency, ignored if inbound_notify is NULLL
+ *                can be used to improve efficiency, ignored if @a inbound_notify is NULL
  * @param outbound_notify function to call for all outbound messages, can be NULL
- * @param outbound_hdr_only set to GNUNET_YES if outbound_notify will only read the
+ * @param outbound_hdr_only set to #GNUNET_YES if outbound_notify will only read the
  *                GNUNET_MessageHeader and hence we do not need to give it the full message
- *                can be used to improve efficiency, ignored if outbound_notify is NULLL
+ *                can be used to improve efficiency, ignored if @a outbound_notify is NULL
  * @param handlers callbacks for messages we care about, NULL-terminated
- * @return handle to the core service (only useful for disconnect until 'init' is called);
+ * @return handle to the core service (only useful for disconnect until @a init is called);
  *                NULL on error (in this case, init is never called)
  */
 struct GNUNET_CORE_Handle *
 GNUNET_CORE_connect (const struct GNUNET_CONFIGURATION_Handle *cfg,
-                    unsigned int queue_size,
                      void *cls,
                      GNUNET_CORE_StartupCallback init,
                      GNUNET_CORE_ConnectEventHandler connects,
                      GNUNET_CORE_DisconnectEventHandler disconnects,
-                    GNUNET_CORE_PeerStatusEventHandler status_events,
                      GNUNET_CORE_MessageCallback inbound_notify,
                      int inbound_hdr_only,
                      GNUNET_CORE_MessageCallback outbound_notify,
@@ -1403,41 +870,49 @@ GNUNET_CORE_connect (const struct GNUNET_CONFIGURATION_Handle *cfg,
                      const struct GNUNET_CORE_MessageHandler *handlers)
 {
   struct GNUNET_CORE_Handle *h;
+  unsigned int hcnt;
 
-  h = GNUNET_malloc (sizeof (struct GNUNET_CORE_Handle));
+  h = GNUNET_new (struct GNUNET_CORE_Handle);
   h->cfg = cfg;
-  h->queue_size = queue_size;
   h->cls = cls;
   h->init = init;
   h->connects = connects;
   h->disconnects = disconnects;
-  h->status_events = status_events;
   h->inbound_notify = inbound_notify;
   h->outbound_notify = outbound_notify;
   h->inbound_hdr_only = inbound_hdr_only;
   h->outbound_hdr_only = outbound_hdr_only;
-  h->handlers = handlers;
-  h->hcnt = 0;
   h->currently_down = GNUNET_YES;
-  h->peers = GNUNET_CONTAINER_multihashmap_create (128);
-  h->retry_backoff = GNUNET_TIME_UNIT_MILLISECONDS;
-  while (handlers[h->hcnt].callback != NULL)
-    h->hcnt++;
-  GNUNET_assert (h->hcnt <
+  h->peers = GNUNET_CONTAINER_multipeermap_create (128, GNUNET_NO);
+  hcnt = 0;
+  if (NULL != handlers)
+    while (NULL != handlers[hcnt].callback)
+      hcnt++;
+  h->handlers = GNUNET_new_array (hcnt + 1,
+                                  struct GNUNET_CORE_MessageHandler);
+  if (NULL != handlers)
+    memcpy (h->handlers,
+            handlers,
+            hcnt * sizeof (struct GNUNET_CORE_MessageHandler));
+  h->hcnt = hcnt;
+  GNUNET_assert (hcnt <
                  (GNUNET_SERVER_MAX_MESSAGE_SIZE -
                   sizeof (struct InitMessage)) / sizeof (uint16_t));
-#if DEBUG_CORE
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-             "Connecting to CORE service\n");
-#endif
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Connecting to CORE service\n");
   reconnect (h);
+  if (NULL == h->mq)
+  {
+    GNUNET_CORE_disconnect (h);
+    return NULL;
+  }
   return h;
 }
 
 
 /**
- * Disconnect from the core service.  This function can only 
- * be called *after* all pending 'GNUNET_CORE_notify_transmit_ready'
+ * Disconnect from the core service.  This function can only
+ * be called *after* all pending #GNUNET_CORE_notify_transmit_ready()
  * requests have been explicitly canceled.
  *
  * @param handle connection to core to disconnect
@@ -1445,70 +920,57 @@ GNUNET_CORE_connect (const struct GNUNET_CONFIGURATION_Handle *cfg,
 void
 GNUNET_CORE_disconnect (struct GNUNET_CORE_Handle *handle)
 {
-  struct ControlMessage *cm;
-  
-#if DEBUG_CORE
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-             "Disconnecting from CORE service\n");
-#endif
-  if (handle->cth != NULL)
-    {
-      GNUNET_CLIENT_notify_transmit_ready_cancel (handle->cth);
-      handle->cth = NULL;
-    }
-  if (handle->client != NULL)
-    {
-      GNUNET_CLIENT_disconnect (handle->client, GNUNET_NO);
-      handle->client = NULL;
-    }
-  while (NULL != (cm = handle->control_pending_head))
-    {
-      GNUNET_CONTAINER_DLL_remove (handle->control_pending_head,
-                                  handle->control_pending_tail,
-                                  cm);
-      if (cm->th != NULL)
-       cm->th->cm = NULL;
-      if (cm->cont != NULL)
-       cm->cont (cm->cont_cls, GNUNET_SYSERR);
-      GNUNET_free (cm);
-    }
-  if (handle->reconnect_task != GNUNET_SCHEDULER_NO_TASK)
-    {
-      GNUNET_SCHEDULER_cancel (handle->reconnect_task);
-      handle->reconnect_task = GNUNET_SCHEDULER_NO_TASK;
-    }
-  GNUNET_CONTAINER_multihashmap_iterate (handle->peers,
-                                        &disconnect_and_free_peer_entry,
-                                        handle);
-  GNUNET_CONTAINER_multihashmap_destroy (handle->peers);
-  GNUNET_break (handle->ready_peer_head == NULL);
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Disconnecting from CORE service\n");
+  GNUNET_CONTAINER_multipeermap_iterate (handle->peers,
+                                         &disconnect_and_free_peer_entry,
+                                         handle);
+  GNUNET_CONTAINER_multipeermap_destroy (handle->peers);
+  handle->peers = NULL;
+  if (NULL != handle->reconnect_task)
+  {
+    GNUNET_SCHEDULER_cancel (handle->reconnect_task);
+    handle->reconnect_task = NULL;
+  }
+  if (NULL != handle->mq)
+  {
+    GNUNET_MQ_destroy (handle->mq);
+    handle->mq = NULL;
+  }
+  GNUNET_free (handle->handlers);
   GNUNET_free (handle);
 }
 
 
 /**
- * Ask the core to call "notify" once it is ready to transmit the
- * given number of bytes to the specified "target".    Must only be
+ * Ask the core to call @a notify once it is ready to transmit the
+ * given number of bytes to the specified @a target.  Must only be
  * called after a connection to the respective peer has been
- * established (and the client has been informed about this).
+ * established (and the client has been informed about this).  You may
+ * have one request of this type pending for each connected peer at
+ * any time.  If a peer disconnects, the application MUST call
+ * #GNUNET_CORE_notify_transmit_ready_cancel on the respective
+ * transmission request, if one such request is pending.
  *
  * @param handle connection to core service
  * @param cork is corking allowed for this transmission?
  * @param priority how important is the message?
- * @param maxdelay how long can the message wait?
- * @param target who should receive the message,
- *        use NULL for this peer (loopback)
- * @param notify_size how many bytes of buffer space does notify want?
- * @param notify function to call when buffer space is available
- * @param notify_cls closure for notify
+ * @param maxdelay how long can the message wait? Only effective if @a cork is #GNUNET_YES
+ * @param target who should receive the message, never NULL (can be this peer's identity for loopback)
+ * @param notify_size how many bytes of buffer space does @a notify want?
+ * @param notify function to call when buffer space is available;
+ *        will be called with NULL on timeout; clients MUST cancel
+ *        all pending transmission requests DURING the disconnect
+ *        handler
+ * @param notify_cls closure for @a notify
  * @return non-NULL if the notify callback was queued,
- *         NULL if we can not even queue the request (insufficient
- *         memory); if NULL is returned, "notify" will NOT be called.
+ *         NULL if we can not even queue the request (request already pending);
+ *         if NULL is returned, @a notify will NOT be called.
  */
 struct GNUNET_CORE_TransmitHandle *
 GNUNET_CORE_notify_transmit_ready (struct GNUNET_CORE_Handle *handle,
-                                  int cork,
-                                   uint32_t priority,
+                                   int cork,
+                                   enum GNUNET_CORE_Priority priority,
                                    struct GNUNET_TIME_Relative maxdelay,
                                    const struct GNUNET_PeerIdentity *target,
                                    size_t notify_size,
@@ -1517,100 +979,68 @@ GNUNET_CORE_notify_transmit_ready (struct GNUNET_CORE_Handle *handle,
 {
   struct PeerRecord *pr;
   struct GNUNET_CORE_TransmitHandle *th;
-  struct GNUNET_CORE_TransmitHandle *pos;
-  struct GNUNET_CORE_TransmitHandle *prev;
-  struct GNUNET_CORE_TransmitHandle *minp;
-
-  pr = GNUNET_CONTAINER_multihashmap_get (handle->peers,
-                                         &target->hashPubKey);
+  struct SendMessageRequest *smr;
+  struct GNUNET_MQ_Envelope *env;
+
+  if (NULL == handle->mq)
+  {
+    GNUNET_break (0); /* SEE #4588: do not call NTR from disconnect notification! */
+    return NULL;
+  }
+  GNUNET_assert (NULL != notify);
+  if ( (notify_size > GNUNET_CONSTANTS_MAX_ENCRYPTED_MESSAGE_SIZE) ||
+       (notify_size + sizeof (struct SendMessage) >= GNUNET_SERVER_MAX_MESSAGE_SIZE) )
+  {
+    GNUNET_break (0);
+    return NULL;
+  }
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Asking core for transmission of %u bytes to `%s'\n",
+       (unsigned int) notify_size,
+       GNUNET_i2s (target));
+  pr = GNUNET_CONTAINER_multipeermap_get (handle->peers,
+                                          target);
   if (NULL == pr)
-    {
-      /* attempt to send to peer that is not connected */
-      GNUNET_log(GNUNET_ERROR_TYPE_WARNING,
-                 "Attempting to send to peer `%s' from peer `%s', but not connected!\n",
-                 GNUNET_i2s(target), GNUNET_h2s(&handle->me.hashPubKey));
-      GNUNET_break (0);
-      return NULL;
-    }
-  GNUNET_assert (notify_size + sizeof (struct SendMessage) <
-                 GNUNET_SERVER_MAX_MESSAGE_SIZE);
-  th = GNUNET_malloc (sizeof (struct GNUNET_CORE_TransmitHandle));
+  {
+    /* attempt to send to peer that is not connected */
+    GNUNET_break (0);
+    return NULL;
+  }
+  if (NULL != pr->th.peer)
+  {
+    /* attempting to queue a second request for the same destination */
+    GNUNET_break (0);
+    return NULL;
+  }
+  th = &pr->th;
+  memset (th,
+          0,
+          sizeof (struct GNUNET_CORE_TransmitHandle));
   th->peer = pr;
-  GNUNET_assert(NULL != notify);
   th->get_message = notify;
   th->get_message_cls = notify_cls;
-  th->timeout = GNUNET_TIME_relative_to_absolute (maxdelay);
+  th->request_time = GNUNET_TIME_absolute_get ();
+  if (GNUNET_YES == cork)
+    th->deadline = GNUNET_TIME_relative_to_absolute (maxdelay);
+  else
+    th->deadline = th->request_time;
   th->priority = priority;
   th->msize = notify_size;
   th->cork = cork;
-  /* bound queue size */
-  if (pr->queue_size == handle->queue_size)
-    {
-      /* find lowest-priority entry, but skip the head of the list */
-      minp = pr->pending_head->next;
-      prev = minp;
-      while (prev != NULL)
-       {
-         if (prev->priority < minp->priority)
-           minp = prev;
-         prev = prev->next;
-       }
-      if (minp == NULL) 
-       {
-         GNUNET_break (handle->queue_size != 0);
-         GNUNET_break (pr->queue_size == 0);
-         GNUNET_free(th);
-         return NULL;
-       }
-      if (priority <= minp->priority)
-       {
-#if DEBUG_CORE
-         GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                     "Dropping transmission request: priority too low\n");
-#endif
-         return NULL; /* priority too low */
-       }
-      GNUNET_CONTAINER_DLL_remove (pr->pending_head,
-                                  pr->pending_tail,
-                                  minp);
-      pr->queue_size--;
-      GNUNET_assert (0 ==
-                    minp->get_message (minp->get_message_cls,
-                                       0, NULL));
-      GNUNET_free (minp);
-    }
-
-  /* Order entries by deadline, but SKIP 'HEAD' if
-     we're in the 'ready_peer_*' DLL */
-  pos = pr->pending_head;
-  if ( (pr->prev != NULL) ||
-       (pr->next != NULL) ||
-       (pr == handle->ready_peer_head) )
-    {
-      GNUNET_assert (pos != NULL);
-      pos = pos->next; /* skip head */
-    }
-
-  /* insertion sort */
-  prev = pos;
-  while ( (pos != NULL) &&
-         (pos->timeout.abs_value < th->timeout.abs_value) )      
-    {
-      prev = pos;
-      pos = pos->next;
-    }
-  GNUNET_CONTAINER_DLL_insert_after (pr->pending_head,
-                                    pr->pending_tail,
-                                    prev,
-                                    th);
-  pr->queue_size++;
-  /* was the request queue previously empty? */
-#if DEBUG_CORE
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-             "Transmission request added to queue\n");
-#endif
-  if (pr->pending_head == th) 
-    request_next_transmission (pr);
+  if (NULL == handle->mq)
+    return th; /* see #4588 (hack until we transition core fully to MQ) */
+  env = GNUNET_MQ_msg (smr,
+                       GNUNET_MESSAGE_TYPE_CORE_SEND_REQUEST);
+  smr->priority = htonl ((uint32_t) th->priority);
+  smr->deadline = GNUNET_TIME_absolute_hton (th->deadline);
+  smr->peer = pr->peer;
+  smr->reserved = htonl (0);
+  smr->size = htons (th->msize);
+  smr->smr_id = htons (th->smr_id = pr->smr_id_gen++);
+  GNUNET_MQ_send (handle->mq,
+                  env);
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Transmission request added to queue\n");
   return th;
 }
 
@@ -1618,339 +1048,42 @@ GNUNET_CORE_notify_transmit_ready (struct GNUNET_CORE_Handle *handle,
 /**
  * Cancel the specified transmission-ready notification.
  *
- * @param th handle that was returned by "notify_transmit_ready".
+ * @param th handle that was returned by #GNUNET_CORE_notify_transmit_ready().
  */
 void
-GNUNET_CORE_notify_transmit_ready_cancel (struct GNUNET_CORE_TransmitHandle
-                                          *th)
+GNUNET_CORE_notify_transmit_ready_cancel (struct GNUNET_CORE_TransmitHandle *th)
 {
   struct PeerRecord *pr = th->peer;
-  struct GNUNET_CORE_Handle *h = pr->ch;
-  int was_head;
-  
-  was_head = (pr->pending_head == th);
-  GNUNET_CONTAINER_DLL_remove (pr->pending_head,
-                              pr->pending_tail,
-                              th);    
-  pr->queue_size--;
-  if (th->cm != NULL)
-    {
-      /* we're currently in the control queue, remove */
-      GNUNET_CONTAINER_DLL_remove (h->control_pending_head,
-                                  h->control_pending_tail,
-                                  th->cm);
-      GNUNET_free (th->cm);      
-    }
-  GNUNET_free (th);
-  if (was_head)
-    {
-      if ( (pr->prev != NULL) ||
-          (pr->next != NULL) ||
-          (pr == h->ready_peer_head) )
-       {
-         /* the request that was 'approved' by core was
-            canceled before it could be transmitted; remove
-            us from the 'ready' list */
-         GNUNET_CONTAINER_DLL_remove (h->ready_peer_head,
-                                      h->ready_peer_tail,
-                                      pr);
-       }
-      request_next_transmission (pr);
-    }
-}
-
-
-/* ****************** GNUNET_CORE_peer_request_connect ******************** */
-
-/**
- * Handle for a request to the core to connect to
- * a particular peer.  Can be used to cancel the request
- * (before the 'cont'inuation is called).
- */
-struct GNUNET_CORE_PeerRequestHandle
-{
-
-  /**
-   * Link to control message.
-   */
-  struct ControlMessage *cm;
-
-  /**
-   * Core handle used.
-   */
-  struct GNUNET_CORE_Handle *h;
-
-  /**
-   * Continuation to run when done.
-   */
-  GNUNET_CORE_ControlContinuation cont;
-
-  /**
-   * Closure for 'cont'.
-   */
-  void *cont_cls;
-
-};
-
-
-/**
- * Continuation called when the control message was transmitted.
- * Calls the original continuation and frees the remaining
- * resources.
- *
- * @param cls the 'struct GNUNET_CORE_PeerRequestHandle'
- * @param success was the request transmitted?
- */
-static void
-peer_request_connect_cont (void *cls,
-                          int success)
-{
-  struct GNUNET_CORE_PeerRequestHandle *ret = cls;
-  
-  if (ret->cont != NULL)
-    ret->cont (ret->cont_cls, success);    
-  GNUNET_free (ret);
-}
-
-
-/**
- * Request that the core should try to connect to a particular peer.
- * Once the request has been transmitted to the core, the continuation
- * function will be called.  Note that this does NOT mean that a
- * connection was successfully established -- it only means that the
- * core will now try.  Successful establishment of the connection
- * will be signalled to the 'connects' callback argument of
- * 'GNUNET_CORE_connect' only.  If the core service does not respond
- * to our connection attempt within the given time frame, 'cont' will
- * be called with the TIMEOUT reason code.
- *
- * @param h core handle
- * @param timeout how long to try to talk to core
- * @param peer who should we connect to
- * @param cont function to call once the request has been completed (or timed out)
- * @param cont_cls closure for cont
- *
- * @return NULL on error or already connected,
- *         otherwise handle for cancellation
- */
-struct GNUNET_CORE_PeerRequestHandle *
-GNUNET_CORE_peer_request_connect (struct GNUNET_CORE_Handle *h,
-                                 struct GNUNET_TIME_Relative timeout,
-                                 const struct GNUNET_PeerIdentity * peer,
-                                 GNUNET_CORE_ControlContinuation cont,
-                                 void *cont_cls)
-{
-  struct GNUNET_CORE_PeerRequestHandle *ret;
-  struct ControlMessage *cm;
-  struct ConnectMessage *msg;
-
-  if (NULL != GNUNET_CONTAINER_multihashmap_get (h->peers,
-                                          &peer->hashPubKey))
-    {
-#if DEBUG_CORE
-      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Peers are already connected!\n");
-#endif
-      return NULL;
-    }
-  
-  cm = GNUNET_malloc (sizeof (struct ControlMessage) + 
-                     sizeof (struct ConnectMessage));
-  msg = (struct ConnectMessage*) &cm[1];
-  msg->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_REQUEST_CONNECT);
-  msg->header.size = htons (sizeof (struct ConnectMessage));
-  msg->reserved = htonl (0);
-  msg->timeout = GNUNET_TIME_relative_hton (timeout);
-  msg->peer = *peer;
-  GNUNET_CONTAINER_DLL_insert_tail (h->control_pending_head,
-                                   h->control_pending_tail,
-                                   cm);
-  ret = GNUNET_malloc (sizeof (struct GNUNET_CORE_PeerRequestHandle));
-  ret->h = h;
-  ret->cm = cm;
-  ret->cont = cont;
-  ret->cont_cls = cont_cls;
-  cm->cont = &peer_request_connect_cont;
-  cm->cont_cls = ret;
-#if DEBUG_CORE
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-             "Queueing REQUEST_CONNECT request\n");
-#endif
-  if (h->control_pending_head == cm)
-    trigger_next_request (h, GNUNET_NO);
-  return ret;
-}
-
-
-/**
- * Cancel a pending request to connect to a particular peer.  Must not
- * be called after the 'cont' function was invoked.
- *
- * @param req request handle that was returned for the original request
- */
-void
-GNUNET_CORE_peer_request_connect_cancel (struct GNUNET_CORE_PeerRequestHandle *req)
-{
-  struct GNUNET_CORE_Handle *h = req->h;
-  struct ControlMessage *cm = req->cm;
-
-  GNUNET_CONTAINER_DLL_remove (h->control_pending_head,
-                              h->control_pending_tail,
-                              cm);
-  GNUNET_free (cm);
-  GNUNET_free (req);
-}
-
-
-/* ****************** GNUNET_CORE_peer_change_preference ******************** */
-
-
-struct GNUNET_CORE_InformationRequestContext 
-{
-  
-  /**
-   * Our connection to the service.
-   */
-  struct GNUNET_CORE_Handle *h;
 
-  /**
-   * Link to control message, NULL if CM was sent.
-   */ 
-  struct ControlMessage *cm;
-
-  /**
-   * Link to peer record.
-   */
-  struct PeerRecord *pr;
-};
-
-
-/**
- * CM was sent, remove link so we don't double-free.
- *
- * @param cls the 'struct GNUNET_CORE_InformationRequestContext'
- * @param success were we successful?
- */
-static void
-change_preference_send_continuation (void *cls,
-                                    int success)
-{
-  struct GNUNET_CORE_InformationRequestContext *irc = cls;
-
-  irc->cm = NULL;
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Aborting transmission request to core for %u bytes to `%s'\n",
+       (unsigned int) th->msize,
+       GNUNET_i2s (&pr->peer));
+  th->peer = NULL;
 }
 
 
 /**
- * Obtain statistics and/or change preferences for the given peer.
+ * Check if the given peer is currently connected. This function is for special
+ * cirumstances (GNUNET_TESTBED uses it), normal users of the CORE API are
+ * expected to track which peers are connected based on the connect/disconnect
+ * callbacks from #GNUNET_CORE_connect().  This function is NOT part of the
+ * 'versioned', 'official' API. The difference between this function and the
+ * function GNUNET_CORE_is_peer_connected() is that this one returns
+ * synchronously after looking in the CORE API cache. The function
+ * GNUNET_CORE_is_peer_connected() sends a message to the CORE service and hence
+ * its response is given asynchronously.
  *
- * @param h core handle
- * @param peer identifies the peer
- * @param timeout after how long should we give up (and call "info" with NULL
- *                for "peer" to signal an error)?
- * @param bw_out set to the current bandwidth limit (sending) for this peer,
- *                caller should set "bw_out" to "-1" to avoid changing
- *                the current value; otherwise "bw_out" will be lowered to
- *                the specified value; passing a pointer to "0" can be used to force
- *                us to disconnect from the peer; "bw_out" might not increase
- *                as specified since the upper bound is generally
- *                determined by the other peer!
- * @param amount reserve N bytes for receiving, negative
- *                amounts can be used to undo a (recent) reservation;
- * @param preference increase incoming traffic share preference by this amount;
- *                in the absence of "amount" reservations, we use this
- *                preference value to assign proportional bandwidth shares
- *                to all connected peers
- * @param info function to call with the resulting configuration information
- * @param info_cls closure for info
- * @return NULL on error
+ * @param h the core handle
+ * @param pid the identity of the peer to check if it has been connected to us
+ * @return #GNUNET_YES if the peer is connected to us; #GNUNET_NO if not
  */
-struct GNUNET_CORE_InformationRequestContext *
-GNUNET_CORE_peer_change_preference (struct GNUNET_CORE_Handle *h,
-                                   const struct GNUNET_PeerIdentity *peer,
-                                   struct GNUNET_TIME_Relative timeout,
-                                   struct GNUNET_BANDWIDTH_Value32NBO bw_out,
-                                   int32_t amount,
-                                   uint64_t preference,
-                                   GNUNET_CORE_PeerConfigurationInfoCallback info,
-                                   void *info_cls)
+int
+GNUNET_CORE_is_peer_connected_sync (const struct GNUNET_CORE_Handle *h,
+                                    const struct GNUNET_PeerIdentity *pid)
 {
-  struct GNUNET_CORE_InformationRequestContext *irc;
-  struct PeerRecord *pr;
-  struct RequestInfoMessage *rim;
-  struct ControlMessage *cm;
-
-  pr = GNUNET_CONTAINER_multihashmap_get (h->peers,
-                                         &peer->hashPubKey);
-  if (NULL == pr)
-    {
-      /* attempt to change preference on peer that is not connected */
-      GNUNET_break (0);
-      return NULL;
-    }
-  if (pr->pcic != NULL)
-    {
-      /* second change before first one is done */
-      GNUNET_break (0);
-      return NULL;
-    }
-  irc = GNUNET_malloc (sizeof (struct GNUNET_CORE_InformationRequestContext));
-  irc->h = h;
-  irc->pr = pr;
-  cm = GNUNET_malloc (sizeof (struct ControlMessage) +
-                     sizeof (struct RequestInfoMessage));
-  cm->cont = &change_preference_send_continuation;
-  cm->cont_cls = irc;
-  irc->cm = cm;
-  rim = (struct RequestInfoMessage*) &cm[1];
-  rim->header.size = htons (sizeof (struct RequestInfoMessage));
-  rim->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_REQUEST_INFO);
-  rim->rim_id = htonl (pr->rim_id = h->rim_id_gen++);
-  rim->limit_outbound = bw_out;
-  rim->reserve_inbound = htonl (amount);
-  rim->preference_change = GNUNET_htonll(preference);
-  rim->peer = *peer;
-#if DEBUG_CORE
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-             "Queueing CHANGE PREFERENCE request\n");
-#endif
-  GNUNET_CONTAINER_DLL_insert_tail (h->control_pending_head,
-                                   h->control_pending_tail,
-                                   cm); 
-  pr->pcic = info;
-  pr->pcic_cls = info_cls;
-  if (h->control_pending_head == cm)
-    trigger_next_request (h, GNUNET_NO);
-  return irc;
-}
-
-
-/**
- * Cancel request for getting information about a peer.
- * Note that an eventual change in preference, trust or bandwidth
- * assignment MAY have already been committed at the time, 
- * so cancelling a request is NOT sure to undo the original
- * request.  The original request may or may not still commit.
- * The only thing cancellation ensures is that the callback
- * from the original request will no longer be called.
- *
- * @param irc context returned by the original GNUNET_CORE_peer_get_info call
- */
-void
-GNUNET_CORE_peer_change_preference_cancel (struct GNUNET_CORE_InformationRequestContext *irc)
-{
-  struct GNUNET_CORE_Handle *h = irc->h;
-  struct PeerRecord *pr = irc->pr;
-
-  if (irc->cm != NULL)
-    {
-      GNUNET_CONTAINER_DLL_remove (h->control_pending_head,
-                                  h->control_pending_tail,
-                                  irc->cm);
-      GNUNET_free (irc->cm);
-    }
-  pr->pcic = NULL;
-  pr->pcic_cls = NULL;
-  GNUNET_free (irc);
+  return GNUNET_CONTAINER_multipeermap_contains (h->peers,
+                                                 pid);
 }