X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=src%2Fset%2Fset_api.c;h=5b5b1b8eecfdd1d97d2d7eaf92c66a9cd100a08c;hb=237dd9f9c93cabd29015d0f5e3c8ceff8af3f071;hp=90cba446cbc1ada0924cb629ad9df68d35c4d92f;hpb=ce9b32618b6ee488352ef0eb506c744868145f82;p=oweals%2Fgnunet.git

diff --git a/src/set/set_api.c b/src/set/set_api.c
index 90cba446c..5b5b1b8ee 100644
--- a/src/set/set_api.c
+++ b/src/set/set_api.c
@@ -1,6 +1,6 @@
 /*
      This file is part of GNUnet.
-     (C) 2012, 2013 Christian Grothoff (and other contributing authors)
+     Copyright (C) 2012-2016 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
@@ -14,37 +14,42 @@
 
      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 set/set_api.c
  * @brief api for the set service
  * @author Florian Dold
+ * @author Christian Grothoff
  */
 #include "platform.h"
 #include "gnunet_util_lib.h"
 #include "gnunet_protocols.h"
-#include "gnunet_client_lib.h"
 #include "gnunet_set_service.h"
 #include "set.h"
 
 
 #define LOG(kind,...) GNUNET_log_from (kind, "set-api",__VA_ARGS__)
 
+struct SetCopyRequest
+{
+  struct SetCopyRequest *next;
+
+  struct SetCopyRequest *prev;
+
+  void *cls;
+
+  GNUNET_SET_CopyReadyCallback cb;
+};
+
 /**
  * Opaque handle to a set.
  */
 struct GNUNET_SET_Handle
 {
   /**
-   * Client connected to the set service.
-   */
-  struct GNUNET_CLIENT_Connection *client;
-
-  /**
-   * Message queue for 'client'.
+   * Message queue for @e client.
    */
   struct GNUNET_MQ_Handle *mq;
 
@@ -58,6 +63,17 @@ struct GNUNET_SET_Handle
    */
   struct GNUNET_SET_OperationHandle *ops_tail;
 
+  /**
+   * Callback for the current iteration over the set,
+   * NULL if no iterator is active.
+   */
+  GNUNET_SET_ElementIterator iterator;
+
+  /**
+   * Closure for @e iterator
+   */
+  void *iterator_cls;
+
   /**
    * Should the set be destroyed once all operations are gone?
    */
@@ -69,20 +85,30 @@ struct GNUNET_SET_Handle
   int invalid;
 
   /**
-   * Callback for the current iteration over the set,
-   * NULL if no iterator is active.
+   * Both client and service count the number of iterators
+   * created so far to match replies with iterators.
    */
-  GNUNET_SET_ElementIterator iterator;
+  uint16_t iteration_id;
 
   /**
-   * Closure for 'iterator'
+   * Configuration, needed when creating (lazy) copies.
    */
-  void *iterator_cls;
+  const struct GNUNET_CONFIGURATION_Handle *cfg;
+
+  /**
+   * Doubly linked list of copy requests.
+   */
+  struct SetCopyRequest *copy_req_head;
+
+  /**
+   * Doubly linked list of copy requests.
+   */
+  struct SetCopyRequest *copy_req_tail;
 };
 
 
 /**
- * Opaque handle to a set operation request from another peer.
+ * Handle for a set operation request from another peer.
  */
 struct GNUNET_SET_Request
 {
@@ -94,15 +120,14 @@ struct GNUNET_SET_Request
 
   /**
    * Has the request been accepted already?
-   * GNUNET_YES/GNUNET_NO
+   * #GNUNET_YES/#GNUNET_NO
    */
   int accepted;
 };
 
 
 /**
- * Handle to an operation.
- * Only known to the service after commiting
+ * Handle to an operation.  Only known to the service after committing
  * the handle with a set.
  */
 struct GNUNET_SET_OperationHandle
@@ -114,7 +139,7 @@ struct GNUNET_SET_OperationHandle
   GNUNET_SET_ResultIterator result_cb;
 
   /**
-   * Closure for result_cb.
+   * Closure for @e result_cb.
    */
   void *result_cls;
 
@@ -124,11 +149,6 @@ struct GNUNET_SET_OperationHandle
    */
   struct GNUNET_SET_Handle *set;
 
-  /**
-   * Request ID to identify the operation within the set.
-   */
-  uint32_t request_id;
-
   /**
    * Message sent to the server on calling conclude,
    * NULL if conclude has been called.
@@ -150,6 +170,11 @@ struct GNUNET_SET_OperationHandle
    * Handles are kept in a linked list.
    */
   struct GNUNET_SET_OperationHandle *next;
+
+  /**
+   * Request ID to identify the operation within the set.
+   */
+  uint32_t request_id;
 };
 
 
@@ -158,10 +183,6 @@ struct GNUNET_SET_OperationHandle
  */
 struct GNUNET_SET_ListenHandle
 {
-  /**
-   * Connection to the service.
-   */
-  struct GNUNET_CLIENT_Connection *client;
 
   /**
    * Message queue for the client.
@@ -182,15 +203,10 @@ struct GNUNET_SET_ListenHandle
   GNUNET_SET_ListenCallback listen_cb;
 
   /**
-   * Closure for listen_cb.
+   * Closure for @e listen_cb.
    */
   void *listen_cls;
 
-  /**
-   * Operation we listen for.
-   */
-  enum GNUNET_SET_OperationType operation;
-
   /**
    * Application ID we listen for.
    */
@@ -204,60 +220,151 @@ struct GNUNET_SET_ListenHandle
   /**
    * Task for reconnecting when the listener fails.
    */
-  GNUNET_SCHEDULER_TaskIdentifier reconnect_task;
+  struct GNUNET_SCHEDULER_Task *reconnect_task;
+
+  /**
+   * Operation we listen for.
+   */
+  enum GNUNET_SET_OperationType operation;
 };
 
 
-/* forward declaration */
+/* mutual recursion with handle_copy_lazy */
+static struct GNUNET_SET_Handle *
+create_internal (const struct GNUNET_CONFIGURATION_Handle *cfg,
+                 enum GNUNET_SET_OperationType op,
+                 const uint32_t *cookie);
+
+
+/**
+ * Handle element for iteration over the set.  Notifies the
+ * iterator and sends an acknowledgement to the service.
+ *
+ * @param cls the `struct GNUNET_SET_Handle *`
+ * @param msg the message
+ */
 static void
-listen_connect (void *cls,
-                const struct GNUNET_SCHEDULER_TaskContext *tc);
+handle_copy_lazy (void *cls,
+                  const struct GNUNET_SET_CopyLazyResponseMessage *msg)
+{
+  struct GNUNET_SET_Handle *set = cls;
+  struct SetCopyRequest *req;
+  struct GNUNET_SET_Handle *new_set;
+
+  req = set->copy_req_head;
+  if (NULL == req)
+  {
+    /* Service sent us unsolicited lazy copy response */
+    GNUNET_break (0);
+    return;
+  }
+
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Handling response to lazy copy\n");
+  GNUNET_CONTAINER_DLL_remove (set->copy_req_head,
+                               set->copy_req_tail,
+                               req);
+  // We pass none as operation here, since it doesn't matter when
+  // cloning.
+  new_set = create_internal (set->cfg,
+			     GNUNET_SET_OPERATION_NONE,
+			     &msg->cookie);
+  req->cb (req->cls, new_set);
+  GNUNET_free (req);
+}
 
 
 /**
- * Handle element for iteration over the set.
+ * Check that the given @a msg is well-formed.
  *
- * @param cls the set
+ * @param cls closure
+ * @param msg message to check
+ * @return #GNUNET_OK if message is well-formed
+ */
+static int
+check_iter_element (void *cls,
+		    const struct GNUNET_SET_IterResponseMessage *msg)
+{
+  /* minimum size was already checked, everything else is OK! */
+  return GNUNET_OK;
+}
+
+
+/**
+ * Handle element for iteration over the set.  Notifies the
+ * iterator and sends an acknowledgement to the service.
+ *
+ * @param cls the `struct GNUNET_SET_Handle *`
  * @param mh the message
  */
 static void
-handle_iter_element (void *cls, const struct GNUNET_MessageHeader *mh)
+handle_iter_element (void *cls,
+                     const struct GNUNET_SET_IterResponseMessage *msg)
 {
   struct GNUNET_SET_Handle *set = cls;
+  GNUNET_SET_ElementIterator iter = set->iterator;
   struct GNUNET_SET_Element element;
-  const struct GNUNET_SET_IterResponseMessage *msg =
-    (const struct GNUNET_SET_IterResponseMessage *) mh;
   struct GNUNET_SET_IterAckMessage *ack_msg;
   struct GNUNET_MQ_Envelope *ev;
+  uint16_t msize;
 
-  if (NULL == set->iterator)
-    return;
-
-  element.size = ntohs (mh->size) - sizeof (struct GNUNET_SET_IterResponseMessage);
-  element.element_type = htons (msg->element_type);
-  element.data = &msg[1];
-  set->iterator (set->iterator_cls, &element);
-  ev = GNUNET_MQ_msg (ack_msg, GNUNET_MESSAGE_TYPE_SET_ITER_ACK);
-  ack_msg->send_more = htonl (1);
+  msize = ntohs (msg->header.size);
+  if (set->iteration_id != ntohs (msg->iteration_id))
+  {
+    /* element from a previous iteration, skip! */
+    iter = NULL;
+  }
+  if (NULL != iter)
+  {
+    element.size = msize - sizeof (struct GNUNET_SET_IterResponseMessage);
+    element.element_type = ntohs (msg->element_type);
+    element.data = &msg[1];
+    iter (set->iterator_cls,
+          &element);
+  }
+  ev = GNUNET_MQ_msg (ack_msg,
+                      GNUNET_MESSAGE_TYPE_SET_ITER_ACK);
+  ack_msg->send_more = htonl ((NULL != iter));
   GNUNET_MQ_send (set->mq, ev);
 }
 
 
 /**
- * Handle element for iteration over the set.
+ * Handle message signalling conclusion of iteration over the set.
+ * Notifies the iterator that we are done.
  *
  * @param cls the set
  * @param mh the message
  */
 static void
-handle_iter_done (void *cls, const struct GNUNET_MessageHeader *mh)
+handle_iter_done (void *cls,
+                  const struct GNUNET_MessageHeader *mh)
 {
   struct GNUNET_SET_Handle *set = cls;
+  GNUNET_SET_ElementIterator iter = set->iterator;
 
-  if (NULL == set->iterator)
+  if (NULL == iter)
     return;
+  set->iterator = NULL;
+  set->iteration_id++;
+  iter (set->iterator_cls,
+        NULL);
+}
 
-  set->iterator (set->iterator_cls, NULL);
+
+/**
+ * Check that the given @a msg is well-formed.
+ *
+ * @param cls closure
+ * @param msg message to check
+ * @return #GNUNET_OK if message is well-formed
+ */
+static int
+check_result (void *cls,
+	      const struct GNUNET_SET_ResultMessage *msg)
+{
+  /* minimum size was already checked, everything else is OK! */
+  return GNUNET_OK;
 }
 
 
@@ -268,185 +375,114 @@ handle_iter_done (void *cls, const struct GNUNET_MessageHeader *mh)
  * @param mh the message
  */
 static void
-handle_result (void *cls, const struct GNUNET_MessageHeader *mh)
+handle_result (void *cls,
+               const struct GNUNET_SET_ResultMessage *msg)
 {
-  const struct GNUNET_SET_ResultMessage *msg;
   struct GNUNET_SET_Handle *set = cls;
   struct GNUNET_SET_OperationHandle *oh;
   struct GNUNET_SET_Element e;
   enum GNUNET_SET_Status result_status;
+  int destroy_set;
 
-  msg = (const struct GNUNET_SET_ResultMessage *) mh;
-  GNUNET_assert (NULL != set);
   GNUNET_assert (NULL != set->mq);
-
   result_status = ntohs (msg->result_status);
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Got result message with status %d\n",
+       result_status);
 
-  oh = GNUNET_MQ_assoc_get (set->mq, ntohl (msg->request_id));
-  // 'oh' can be NULL if we canceled the operation, but the service
-  // did not get the cancel message yet.
+  oh = GNUNET_MQ_assoc_get (set->mq,
+                            ntohl (msg->request_id));
   if (NULL == oh)
   {
-    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "ignoring result from canceled operation\n");
+    /* 'oh' can be NULL if we canceled the operation, but the service
+       did not get the cancel message yet. */
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "Ignoring result from canceled operation\n");
     return;
   }
-  /* status is not STATUS_OK => there's no attached element,
-   * and this is the last result message we get */
-  if (GNUNET_SET_STATUS_OK != result_status)
+
+  switch (result_status)
   {
-    GNUNET_MQ_assoc_remove (set->mq, ntohl (msg->request_id));
-    GNUNET_CONTAINER_DLL_remove (oh->set->ops_head, oh->set->ops_tail, oh);
-    if (GNUNET_YES == oh->set->destroy_requested)
-      GNUNET_SET_destroy (oh->set);
-    if (NULL != oh->result_cb)
-      oh->result_cb (oh->result_cls, NULL, result_status);
-    GNUNET_free (oh);
-    return;
+    case GNUNET_SET_STATUS_OK:
+    case GNUNET_SET_STATUS_ADD_LOCAL:
+    case GNUNET_SET_STATUS_ADD_REMOTE:
+      goto do_element;
+    case GNUNET_SET_STATUS_FAILURE:
+    case GNUNET_SET_STATUS_DONE:
+      goto do_final;
+    case GNUNET_SET_STATUS_HALF_DONE:
+      /* not used anymore */
+      GNUNET_assert (0);
   }
 
-  e.data = &msg[1];
-  e.size = ntohs (mh->size) - sizeof (struct GNUNET_SET_ResultMessage);
-  e.element_type = msg->element_type;
-  if (NULL != oh->result_cb)
-    oh->result_cb (oh->result_cls, &e, result_status);
-}
-
-
-/**
- * Handle request message for a listen operation
- *
- * @param cls the listen handle
- * @param mh the message
- */
-static void
-handle_request (void *cls,
-                const struct GNUNET_MessageHeader *mh)
-{
-  const struct GNUNET_SET_RequestMessage *msg = (const struct GNUNET_SET_RequestMessage *) mh;
-  struct GNUNET_SET_ListenHandle *lh = cls;
-  struct GNUNET_SET_Request *req;
-  const struct GNUNET_MessageHeader *context_msg;
-
+do_final:
   LOG (GNUNET_ERROR_TYPE_DEBUG,
-       "processing operation request\n");
-  req = GNUNET_new (struct GNUNET_SET_Request);
-  req->accept_id = ntohl (msg->accept_id);
-  context_msg = GNUNET_MQ_extract_nested_mh (msg);
-  /* calling #GNUNET_SET_accept() in the listen cb will set req->accepted */
-  lh->listen_cb (lh->listen_cls, &msg->peer_id, context_msg, req);
-
-  /* we got another request => reset the backoff */
-  lh->reconnect_backoff = GNUNET_TIME_UNIT_MILLISECONDS;
-
-  if (GNUNET_NO == req->accepted)
+       "Treating result as final status\n");
+  GNUNET_MQ_assoc_remove (set->mq,
+                          ntohl (msg->request_id));
+  GNUNET_CONTAINER_DLL_remove (set->ops_head,
+                               set->ops_tail,
+                               oh);
+  /* Need to do this calculation _before_ the result callback,
+     as IF the application still has a valid set handle, it
+     may trigger destruction of the set during the callback. */
+  destroy_set = (GNUNET_YES == set->destroy_requested) &&
+                (NULL == set->ops_head);
+  if (NULL != oh->result_cb)
+  {
+    oh->result_cb (oh->result_cls,
+                   NULL,
+                   GNUNET_ntohll (msg->current_size),
+                   result_status);
+  }
+  else
   {
-    struct GNUNET_MQ_Envelope *mqm;
-    struct GNUNET_SET_RejectMessage *rmsg;
-
-    mqm = GNUNET_MQ_msg (rmsg,
-                         GNUNET_MESSAGE_TYPE_SET_REJECT);
-    rmsg->accept_reject_id = msg->accept_id;
-    GNUNET_MQ_send (lh->mq, mqm);
     LOG (GNUNET_ERROR_TYPE_DEBUG,
-         "rejecting request\n");
+         "No callback for final status\n");
   }
-  GNUNET_free (req);
-
-  LOG (GNUNET_ERROR_TYPE_DEBUG,
-       "processed op request from service\n");
-
-  /* the accept-case is handled in GNUNET_SET_accept,
-   * as we have the accept message available there */
-}
-
-
-static void
-handle_client_listener_error (void *cls,
-                              enum GNUNET_MQ_Error error)
-{
-  struct GNUNET_SET_ListenHandle *lh = cls;
+  if (destroy_set)
+    GNUNET_SET_destroy (set);
+  GNUNET_free (oh);
+  return;
 
+do_element:
   LOG (GNUNET_ERROR_TYPE_DEBUG,
-       "listener broke down, re-connecting\n");
-  GNUNET_CLIENT_disconnect (lh->client);
-  lh->client = NULL;
-  GNUNET_MQ_destroy (lh->mq);
-  lh->mq = NULL;
-  lh->reconnect_task = GNUNET_SCHEDULER_add_delayed (lh->reconnect_backoff,
-                                                     &listen_connect, lh);
-  lh->reconnect_backoff = GNUNET_TIME_STD_BACKOFF (lh->reconnect_backoff);
-}
-
-
-/**
- * Destroy the set handle if no operations are left, mark the set
- * for destruction otherwise.
- *
- * @param set set handle to destroy
- */
-static int
-set_destroy (struct GNUNET_SET_Handle *set)
-{
-  if (NULL != set->ops_head)
-  {
-    set->destroy_requested = GNUNET_YES;
-    return GNUNET_NO;
-  }
-  LOG (GNUNET_ERROR_TYPE_DEBUG, "Really destroying set\n");
-  GNUNET_CLIENT_disconnect (set->client);
-  set->client = NULL;
-  GNUNET_MQ_destroy (set->mq);
-  set->mq = NULL;
-  GNUNET_free (set);
-  return GNUNET_YES;
+       "Treating result as element\n");
+  e.data = &msg[1];
+  e.size = ntohs (msg->header.size) - sizeof (struct GNUNET_SET_ResultMessage);
+  e.element_type = ntohs (msg->element_type);
+  if (NULL != oh->result_cb)
+    oh->result_cb (oh->result_cls,
+                   &e,
+                   GNUNET_ntohll (msg->current_size),
+                   result_status);
 }
 
 
 /**
- * Cancel the given set operation.  We need to send an explicit cancel message,
- * as all operations one one set communicate using one handle.
- *
- * In contrast to #GNUNET_SET_operation_cancel(), this function indicates whether
- * the set of the operation has been destroyed because all operations are done and
- * the set's destruction was requested before.
+ * Destroy the given set operation.
  *
- * @param oh set operation to cancel
- * @return #GNUNET_YES if the set of the operation was destroyed
+ * @param oh set operation to destroy
  */
-static int
-set_operation_cancel (struct GNUNET_SET_OperationHandle *oh)
+static void
+set_operation_destroy (struct GNUNET_SET_OperationHandle *oh)
 {
-  int ret = GNUNET_NO;
+  struct GNUNET_SET_Handle *set = oh->set;
+  struct GNUNET_SET_OperationHandle *h_assoc;
 
   if (NULL != oh->conclude_mqm)
     GNUNET_MQ_discard (oh->conclude_mqm);
-
   /* is the operation already commited? */
-  if (NULL != oh->set)
+  if (NULL != set)
   {
-    struct GNUNET_SET_OperationHandle *h_assoc;
-    struct GNUNET_SET_CancelMessage *m;
-    struct GNUNET_MQ_Envelope *mqm;
-
-    GNUNET_CONTAINER_DLL_remove (oh->set->ops_head,
-                                 oh->set->ops_tail,
+    GNUNET_CONTAINER_DLL_remove (set->ops_head,
+                                 set->ops_tail,
                                  oh);
-    h_assoc = GNUNET_MQ_assoc_remove (oh->set->mq,
+    h_assoc = GNUNET_MQ_assoc_remove (set->mq,
                                       oh->request_id);
-    GNUNET_assert ((h_assoc == NULL) || (h_assoc == oh));
-    mqm = GNUNET_MQ_msg (m, GNUNET_MESSAGE_TYPE_SET_CANCEL);
-    m->request_id = htonl (oh->request_id);
-    GNUNET_MQ_send (oh->set->mq, mqm);
-
-    if (GNUNET_YES == oh->set->destroy_requested)
-    {
-      LOG (GNUNET_ERROR_TYPE_DEBUG,
-           "Destroying set after operation cancel\n");
-      ret = set_destroy (oh->set);
-    }
+    GNUNET_assert ((NULL == h_assoc) || (h_assoc == oh));
   }
   GNUNET_free (oh);
-  return ret;
 }
 
 
@@ -460,27 +496,123 @@ set_operation_cancel (struct GNUNET_SET_OperationHandle *oh)
 void
 GNUNET_SET_operation_cancel (struct GNUNET_SET_OperationHandle *oh)
 {
-  (void) set_operation_cancel (oh);
+  struct GNUNET_SET_Handle *set = oh->set;
+  struct GNUNET_SET_CancelMessage *m;
+  struct GNUNET_MQ_Envelope *mqm;
+
+  if (NULL != set)
+  {
+    mqm = GNUNET_MQ_msg (m, GNUNET_MESSAGE_TYPE_SET_CANCEL);
+    m->request_id = htonl (oh->request_id);
+    GNUNET_MQ_send (set->mq, mqm);
+  }
+  set_operation_destroy (oh);
+  if ( (NULL != set) &&
+       (GNUNET_YES == set->destroy_requested) &&
+       (NULL == set->ops_head) )
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Destroying set after operation cancel\n");
+    GNUNET_SET_destroy (set);
+  }
 }
 
 
+/**
+ * We encountered an error communicating with the set service while
+ * performing a set operation. Report to the application.
+ *
+ * @param cls the `struct GNUNET_SET_Handle`
+ * @param error error code
+ */
 static void
-handle_client_set_error (void *cls, enum GNUNET_MQ_Error error)
+handle_client_set_error (void *cls,
+                         enum GNUNET_MQ_Error error)
 {
   struct GNUNET_SET_Handle *set = cls;
+  GNUNET_SET_ElementIterator iter = set->iterator;
 
-  LOG (GNUNET_ERROR_TYPE_DEBUG,
-       "handling client set error\n");
-
+  LOG (GNUNET_ERROR_TYPE_ERROR,
+       "Handling client set error %d\n",
+       error);
   while (NULL != set->ops_head)
   {
     if (NULL != set->ops_head->result_cb)
-      set->ops_head->result_cb (set->ops_head->result_cls, NULL,
+      set->ops_head->result_cb (set->ops_head->result_cls,
+                                NULL,
+                                0,
                                 GNUNET_SET_STATUS_FAILURE);
-    if (GNUNET_YES == set_operation_cancel (set->ops_head))
-      return; /* stop if the set is destroyed */
+    set_operation_destroy (set->ops_head);
   }
+  set->iterator = NULL;
+  set->iteration_id++;
   set->invalid = GNUNET_YES;
+  if (NULL != iter)
+    iter (set->iterator_cls,
+          NULL);
+}
+
+
+static struct GNUNET_SET_Handle *
+create_internal (const struct GNUNET_CONFIGURATION_Handle *cfg,
+                 enum GNUNET_SET_OperationType op,
+                 const uint32_t *cookie)
+{
+  struct GNUNET_SET_Handle *set = GNUNET_new (struct GNUNET_SET_Handle);
+  struct GNUNET_MQ_MessageHandler mq_handlers[] = {
+    GNUNET_MQ_hd_var_size (result,
+                           GNUNET_MESSAGE_TYPE_SET_RESULT,
+                           struct GNUNET_SET_ResultMessage,
+                           set),
+    GNUNET_MQ_hd_var_size (iter_element,
+                           GNUNET_MESSAGE_TYPE_SET_ITER_ELEMENT,
+                           struct GNUNET_SET_IterResponseMessage,
+                           set),
+    GNUNET_MQ_hd_fixed_size (iter_done,
+                             GNUNET_MESSAGE_TYPE_SET_ITER_DONE,
+                             struct GNUNET_MessageHeader,
+                             set),
+    GNUNET_MQ_hd_fixed_size (copy_lazy,
+                             GNUNET_MESSAGE_TYPE_SET_COPY_LAZY_RESPONSE,
+                             struct GNUNET_SET_CopyLazyResponseMessage,
+                             set),
+    GNUNET_MQ_handler_end ()
+  };
+  struct GNUNET_MQ_Envelope *mqm;
+  struct GNUNET_SET_CreateMessage *create_msg;
+  struct GNUNET_SET_CopyLazyConnectMessage *copy_msg;
+
+  set->cfg = cfg;
+  set->mq = GNUNET_CLIENT_connect (cfg,
+                                   "set",
+                                   mq_handlers,
+                                   &handle_client_set_error,
+                                   set);
+  if (NULL == set->mq)
+  {
+    GNUNET_free (set);
+    return NULL;
+  }
+  if (NULL == cookie)
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Creating new set (operation %u)\n",
+         op);
+    mqm = GNUNET_MQ_msg (create_msg,
+                         GNUNET_MESSAGE_TYPE_SET_CREATE);
+    create_msg->operation = htonl (op);
+  }
+  else
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Creating new set (lazy copy)\n",
+         op);
+    mqm = GNUNET_MQ_msg (copy_msg,
+                         GNUNET_MESSAGE_TYPE_SET_COPY_LAZY_CONNECT);
+    copy_msg->cookie = *cookie;
+  }
+  GNUNET_MQ_send (set->mq, mqm);
+  return set;
 }
 
 
@@ -499,35 +631,15 @@ struct GNUNET_SET_Handle *
 GNUNET_SET_create (const struct GNUNET_CONFIGURATION_Handle *cfg,
                    enum GNUNET_SET_OperationType op)
 {
-  static const struct GNUNET_MQ_MessageHandler mq_handlers[] = {
-    {handle_result, GNUNET_MESSAGE_TYPE_SET_RESULT, 0},
-    {handle_iter_element, GNUNET_MESSAGE_TYPE_SET_ITER_ELEMENT, 0},
-    {handle_iter_done, GNUNET_MESSAGE_TYPE_SET_ITER_DONE, 0},
-    GNUNET_MQ_HANDLERS_END
-  };
-  struct GNUNET_SET_Handle *set;
-  struct GNUNET_MQ_Envelope *mqm;
-  struct GNUNET_SET_CreateMessage *msg;
-
-  set = GNUNET_new (struct GNUNET_SET_Handle);
-  set->client = GNUNET_CLIENT_connect ("set", cfg);
-  LOG (GNUNET_ERROR_TYPE_DEBUG, "set client created\n");
-  GNUNET_assert (NULL != set->client);
-  set->mq = GNUNET_MQ_queue_for_connection_client (set->client, mq_handlers,
-                                                   handle_client_set_error, set);
-  GNUNET_assert (NULL != set->mq);
-  mqm = GNUNET_MQ_msg (msg, GNUNET_MESSAGE_TYPE_SET_CREATE);
-  msg->operation = htonl (op);
-  GNUNET_MQ_send (set->mq, mqm);
-  return set;
+  return create_internal (cfg, op, NULL);
 }
 
 
 /**
- * Add an element to the given set.
- * After the element has been added (in the sense of being
- * transmitted to the set service), cont will be called.
- * Calls to add_element can be queued
+ * Add an element to the given set.  After the element has been added
+ * (in the sense of being transmitted to the set service), @a cont
+ * will be called.  Multiple calls to GNUNET_SET_add_element() can be
+ * queued.
  *
  * @param set set to add element to
  * @param element element to add to the set
@@ -545,27 +657,33 @@ GNUNET_SET_add_element (struct GNUNET_SET_Handle *set,
   struct GNUNET_MQ_Envelope *mqm;
   struct GNUNET_SET_ElementMessage *msg;
 
+  LOG (GNUNET_ERROR_TYPE_INFO, "adding element of type %u\n", (unsigned) element->element_type);
+
   if (GNUNET_YES == set->invalid)
   {
     if (NULL != cont)
       cont (cont_cls);
     return GNUNET_SYSERR;
   }
-
-  mqm = GNUNET_MQ_msg_extra (msg, element->size, GNUNET_MESSAGE_TYPE_SET_ADD);
-  msg->element_type = element->element_type;
-  memcpy (&msg[1], element->data, element->size);
-  GNUNET_MQ_notify_sent (mqm, cont, cont_cls);
+  mqm = GNUNET_MQ_msg_extra (msg,
+                             element->size,
+                             GNUNET_MESSAGE_TYPE_SET_ADD);
+  msg->element_type = htons (element->element_type);
+  GNUNET_memcpy (&msg[1],
+                 element->data,
+                 element->size);
+  GNUNET_MQ_notify_sent (mqm,
+                         cont, cont_cls);
   GNUNET_MQ_send (set->mq, mqm);
   return GNUNET_OK;
 }
 
 
 /**
- * Remove an element to the given set.
- * After the element has been removed (in the sense of the
- * request being transmitted to the set service), cont will be called.
- * Calls to remove_element can be queued
+ * Remove an element to the given set.  After the element has been
+ * removed (in the sense of the request being transmitted to the set
+ * service), @a cont will be called.  Multiple calls to
+ * GNUNET_SET_remove_element() can be queued
  *
  * @param set set to remove element from
  * @param element element to remove from the set
@@ -589,27 +707,48 @@ GNUNET_SET_remove_element (struct GNUNET_SET_Handle *set,
       cont (cont_cls);
     return GNUNET_SYSERR;
   }
-
   mqm = GNUNET_MQ_msg_extra (msg,
                              element->size,
                              GNUNET_MESSAGE_TYPE_SET_REMOVE);
-  msg->element_type = element->element_type;
-  memcpy (&msg[1], element->data, element->size);
-  GNUNET_MQ_notify_sent (mqm, cont, cont_cls);
+  msg->element_type = htons (element->element_type);
+  GNUNET_memcpy (&msg[1],
+                 element->data,
+                 element->size);
+  GNUNET_MQ_notify_sent (mqm,
+                         cont, cont_cls);
   GNUNET_MQ_send (set->mq, mqm);
   return GNUNET_OK;
 }
 
 
 /**
- * Destroy the set handle, and free all associated resources.
+ * Destroy the set handle if no operations are left, mark the set
+ * for destruction otherwise.
  *
  * @param set set handle to destroy
  */
 void
 GNUNET_SET_destroy (struct GNUNET_SET_Handle *set)
 {
-  (void) set_destroy (set);
+  /* destroying set while iterator is active is currently
+     not supported; we should expand the API to allow
+     clients to explicitly cancel the iteration! */
+  GNUNET_assert (NULL == set->iterator);
+  if (NULL != set->ops_head)
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Set operations are pending, delaying set destruction\n");
+    set->destroy_requested = GNUNET_YES;
+    return;
+  }
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Really destroying set\n");
+  if (NULL != set->mq)
+  {
+    GNUNET_MQ_destroy (set->mq);
+    set->mq = NULL;
+  }
+  GNUNET_free (set);
 }
 
 
@@ -632,13 +771,18 @@ GNUNET_SET_prepare (const struct GNUNET_PeerIdentity *other_peer,
                     const struct GNUNET_HashCode *app_id,
                     const struct GNUNET_MessageHeader *context_msg,
                     enum GNUNET_SET_ResultMode result_mode,
+                    struct GNUNET_SET_Option options[],
                     GNUNET_SET_ResultIterator result_cb,
                     void *result_cls)
 {
   struct GNUNET_MQ_Envelope *mqm;
   struct GNUNET_SET_OperationHandle *oh;
   struct GNUNET_SET_EvaluateMessage *msg;
+  struct GNUNET_SET_Option *opt;
 
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Client prepares set operation (%d)\n",
+       result_mode);
   oh = GNUNET_new (struct GNUNET_SET_OperationHandle);
   oh->result_cb = result_cb;
   oh->result_cls = result_cls;
@@ -648,6 +792,25 @@ GNUNET_SET_prepare (const struct GNUNET_PeerIdentity *other_peer,
   msg->app_id = *app_id;
   msg->result_mode = htonl (result_mode);
   msg->target_peer = *other_peer;
+  for (opt = options; opt->type != 0; opt++)
+  {
+    switch (opt->type)
+    {
+      case GNUNET_SET_OPTION_BYZANTINE:
+        msg->byzantine = GNUNET_YES;
+        msg->byzantine_lower_bound = opt->v.num;
+        break;
+      case GNUNET_SET_OPTION_FORCE_FULL:
+        msg->force_full = GNUNET_YES;
+        break;
+      case GNUNET_SET_OPTION_FORCE_DELTA:
+        msg->force_delta = GNUNET_YES;
+        break;
+      default:
+        LOG (GNUNET_ERROR_TYPE_ERROR, 
+             "Option with type %d not recognized\n", (int) opt->type);
+    }
+  }
   oh->conclude_mqm = mqm;
   oh->request_id_addr = &msg->request_id;
 
@@ -656,47 +819,137 @@ GNUNET_SET_prepare (const struct GNUNET_PeerIdentity *other_peer,
 
 
 /**
- * Connect to the set service in order to listen
- * for request.
+ * Connect to the set service in order to listen for requests.
  *
- * @param cls the listen handle to connect
- * @param tc task context if invoked as a task, NULL otherwise
+ * @param cls the `struct GNUNET_SET_ListenHandle *` to connect
  */
 static void
-listen_connect (void *cls,
-                const struct GNUNET_SCHEDULER_TaskContext *tc)
+listen_connect (void *cls);
+
+
+/**
+ * Check validity of request message for a listen operation
+ *
+ * @param cls the listen handle
+ * @param msg the message
+ * @return #GNUNET_OK if the message is well-formed
+ */
+static int
+check_request (void *cls,
+	       const struct GNUNET_SET_RequestMessage *msg)
 {
-  struct GNUNET_MQ_Envelope *mqm;
-  struct GNUNET_SET_ListenMessage *msg;
-  struct GNUNET_SET_ListenHandle *lh = cls;
-  static const struct GNUNET_MQ_MessageHandler mq_handlers[] = {
-    {handle_request, GNUNET_MESSAGE_TYPE_SET_REQUEST},
-    GNUNET_MQ_HANDLERS_END
-  };
+  const struct GNUNET_MessageHeader *context_msg;
 
-  if ((tc != NULL) &&(tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN) != 0)
+  if (ntohs (msg->header.size) == sizeof (*msg))
+    return GNUNET_OK; /* no context message is OK */
+  context_msg = GNUNET_MQ_extract_nested_mh (msg);
+  if (NULL == context_msg)
   {
-    LOG (GNUNET_ERROR_TYPE_DEBUG, "listener not reconnecting due to shutdown\n");
-    return;
+    /* malformed context message is NOT ok */
+    GNUNET_break_op (0);
+    return GNUNET_SYSERR;
   }
+  return GNUNET_OK;
+}
 
-  lh->reconnect_task = GNUNET_SCHEDULER_NO_TASK;
 
-  GNUNET_assert (NULL == lh->client);
-  lh->client = GNUNET_CLIENT_connect ("set", lh->cfg);
-  if (NULL == lh->client)
-  {
-    LOG (GNUNET_ERROR_TYPE_ERROR,
-         "could not connect to set (wrong configuration?), giving up listening\n");
-    return;
-  }
+/**
+ * Handle request message for a listen operation
+ *
+ * @param cls the listen handle
+ * @param msg the message
+ */
+static void
+handle_request (void *cls,
+                const struct GNUNET_SET_RequestMessage *msg)
+{
+  struct GNUNET_SET_ListenHandle *lh = cls;
+  struct GNUNET_SET_Request req;
+  const struct GNUNET_MessageHeader *context_msg;
+  struct GNUNET_MQ_Envelope *mqm;
+  struct GNUNET_SET_RejectMessage *rmsg;
+
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Processing incoming operation request\n");
+  /* we got another valid request => reset the backoff */
+  lh->reconnect_backoff = GNUNET_TIME_UNIT_MILLISECONDS;
+  req.accept_id = ntohl (msg->accept_id);
+  req.accepted = GNUNET_NO;
+  context_msg = GNUNET_MQ_extract_nested_mh (msg);
+  /* calling #GNUNET_SET_accept() in the listen cb will set req->accepted */
+  lh->listen_cb (lh->listen_cls,
+                 &msg->peer_id,
+                 context_msg,
+                 &req);
+  if (GNUNET_YES == req.accepted)
+    return; /* the accept-case is handled in #GNUNET_SET_accept() */
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Rejecting request\n");
+  mqm = GNUNET_MQ_msg (rmsg,
+                       GNUNET_MESSAGE_TYPE_SET_REJECT);
+  rmsg->accept_reject_id = msg->accept_id;
+  GNUNET_MQ_send (lh->mq, mqm);
+}
+
+
+/**
+ * Our connection with the set service encountered an error,
+ * re-initialize with exponential back-off.
+ *
+ * @param cls the `struct GNUNET_SET_ListenHandle *`
+ * @param error reason for the disconnect
+ */
+static void
+handle_client_listener_error (void *cls,
+                              enum GNUNET_MQ_Error error)
+{
+  struct GNUNET_SET_ListenHandle *lh = cls;
+
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Listener broke down (%d), re-connecting\n",
+       (int) error);
+  GNUNET_MQ_destroy (lh->mq);
+  lh->mq = NULL;
+  lh->reconnect_task = GNUNET_SCHEDULER_add_delayed (lh->reconnect_backoff,
+                                                     &listen_connect,
+						     lh);
+  lh->reconnect_backoff = GNUNET_TIME_STD_BACKOFF (lh->reconnect_backoff);
+}
+
+
+/**
+ * Connect to the set service in order to listen for requests.
+ *
+ * @param cls the `struct GNUNET_SET_ListenHandle *` to connect
+ */
+static void
+listen_connect (void *cls)
+{
+  struct GNUNET_SET_ListenHandle *lh = cls;
+  struct GNUNET_MQ_MessageHandler mq_handlers[] = {
+    GNUNET_MQ_hd_var_size (request,
+                           GNUNET_MESSAGE_TYPE_SET_REQUEST,
+                           struct GNUNET_SET_RequestMessage,
+                           lh),
+    GNUNET_MQ_handler_end ()
+  };
+  struct GNUNET_MQ_Envelope *mqm;
+  struct GNUNET_SET_ListenMessage *msg;
+
+  lh->reconnect_task = NULL;
   GNUNET_assert (NULL == lh->mq);
-  lh->mq = GNUNET_MQ_queue_for_connection_client (lh->client, mq_handlers,
-                                                  handle_client_listener_error, lh);
+  lh->mq = GNUNET_CLIENT_connect (lh->cfg,
+                                  "set",
+                                  mq_handlers,
+                                  &handle_client_listener_error,
+                                  lh);
+  if (NULL == lh->mq)
+    return;
   mqm = GNUNET_MQ_msg (msg, GNUNET_MESSAGE_TYPE_SET_LISTEN);
   msg->operation = htonl (lh->operation);
   msg->app_id = lh->app_id;
-  GNUNET_MQ_send (lh->mq, mqm);
+  GNUNET_MQ_send (lh->mq,
+                  mqm);
 }
 
 
@@ -709,7 +962,7 @@ listen_connect (void *cls,
  * @param app_id id of the application that handles set operation requests
  * @param listen_cb called for each incoming request matching the operation
  *                  and application id
- * @param listen_cls handle for listen_cb
+ * @param listen_cls handle for @a listen_cb
  * @return a handle that can be used to cancel the listen operation
  */
 struct GNUNET_SET_ListenHandle *
@@ -728,7 +981,12 @@ GNUNET_SET_listen (const struct GNUNET_CONFIGURATION_Handle *cfg,
   lh->operation = operation;
   lh->app_id = *app_id;
   lh->reconnect_backoff = GNUNET_TIME_UNIT_MILLISECONDS;
-  listen_connect (lh, NULL);
+  listen_connect (lh);
+  if (NULL == lh->mq)
+  {
+    GNUNET_free (lh);
+    return NULL;
+  }
   return lh;
 }
 
@@ -741,22 +999,17 @@ GNUNET_SET_listen (const struct GNUNET_CONFIGURATION_Handle *cfg,
 void
 GNUNET_SET_listen_cancel (struct GNUNET_SET_ListenHandle *lh)
 {
-  LOG (GNUNET_ERROR_TYPE_DEBUG, "canceling listener\n");
-  /* listener's connection may have failed, thus mq/client could be NULL */
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Canceling listener\n");
   if (NULL != lh->mq)
   {
     GNUNET_MQ_destroy (lh->mq);
     lh->mq = NULL;
   }
-  if (NULL != lh->client)
-  {
-    GNUNET_CLIENT_disconnect (lh->client);
-    lh->client = NULL;
-  }
-  if (GNUNET_SCHEDULER_NO_TASK != lh->reconnect_task)
+  if (NULL != lh->reconnect_task)
   {
     GNUNET_SCHEDULER_cancel (lh->reconnect_task);
-    lh->reconnect_task = GNUNET_SCHEDULER_NO_TASK;
+    lh->reconnect_task = NULL;
   }
   GNUNET_free (lh);
 }
@@ -779,6 +1032,7 @@ GNUNET_SET_listen_cancel (struct GNUNET_SET_ListenHandle *lh)
 struct GNUNET_SET_OperationHandle *
 GNUNET_SET_accept (struct GNUNET_SET_Request *request,
                    enum GNUNET_SET_ResultMode result_mode,
+                   struct GNUNET_SET_Option options[],
                    GNUNET_SET_ResultIterator result_cb,
                    void *result_cls)
 {
@@ -786,21 +1040,19 @@ GNUNET_SET_accept (struct GNUNET_SET_Request *request,
   struct GNUNET_SET_OperationHandle *oh;
   struct GNUNET_SET_AcceptMessage *msg;
 
-  GNUNET_assert (NULL != request);
   GNUNET_assert (GNUNET_NO == request->accepted);
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Client accepts set operation (%d)\n",
+       result_mode);
   request->accepted = GNUNET_YES;
-
-  oh = GNUNET_new (struct GNUNET_SET_OperationHandle);
-  oh->result_cb = result_cb;
-  oh->result_cls = result_cls;
-
   mqm = GNUNET_MQ_msg (msg, GNUNET_MESSAGE_TYPE_SET_ACCEPT);
   msg->accept_reject_id = htonl (request->accept_id);
   msg->result_mode = htonl (result_mode);
-
+  oh = GNUNET_new (struct GNUNET_SET_OperationHandle);
+  oh->result_cb = result_cb;
+  oh->result_cls = result_cls;
   oh->conclude_mqm = mqm;
   oh->request_id_addr = &msg->request_id;
-
   return oh;
 }
 
@@ -822,17 +1074,27 @@ int
 GNUNET_SET_commit (struct GNUNET_SET_OperationHandle *oh,
                    struct GNUNET_SET_Handle *set)
 {
-  GNUNET_assert (NULL == oh->set);
+  if (NULL != oh->set)
+  {
+    /* Some other set was already commited for this
+     * operation, there is a logic bug in the client of this API */
+    GNUNET_break (0);
+    return GNUNET_OK;
+  }
   if (GNUNET_YES == set->invalid)
     return GNUNET_SYSERR;
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Client commits to SET\n");
   GNUNET_assert (NULL != oh->conclude_mqm);
   oh->set = set;
   GNUNET_CONTAINER_DLL_insert (set->ops_head,
                                set->ops_tail,
                                oh);
-  oh->request_id = GNUNET_MQ_assoc_add (set->mq, oh);
+  oh->request_id = GNUNET_MQ_assoc_add (set->mq,
+                                        oh);
   *oh->request_id_addr = htonl (oh->request_id);
-  GNUNET_MQ_send (set->mq, oh->conclude_mqm);
+  GNUNET_MQ_send (set->mq,
+                  oh->conclude_mqm);
   oh->conclude_mqm = NULL;
   oh->request_id_addr = NULL;
   return GNUNET_OK;
@@ -840,9 +1102,9 @@ GNUNET_SET_commit (struct GNUNET_SET_OperationHandle *oh,
 
 
 /**
- * Iterate over all elements in the given set.
- * Note that this operation involves transferring every element of the set
- * from the service to the client, and is thus costly.
+ * Iterate over all elements in the given set.  Note that this
+ * operation involves transferring every element of the set from the
+ * service to the client, and is thus costly.
  *
  * @param set the set to iterate over
  * @param iter the iterator to call for each element
@@ -858,15 +1120,13 @@ GNUNET_SET_iterate (struct GNUNET_SET_Handle *set,
 {
   struct GNUNET_MQ_Envelope *ev;
 
-
   GNUNET_assert (NULL != iter);
-
   if (GNUNET_YES == set->invalid)
     return GNUNET_SYSERR;
   if (NULL != set->iterator)
     return GNUNET_NO;
   LOG (GNUNET_ERROR_TYPE_DEBUG,
-       "iterating set\n");
+       "Iterating over set\n");
   set->iterator = iter;
   set->iterator_cls = iter_cls;
   ev = GNUNET_MQ_msg_header (GNUNET_MESSAGE_TYPE_SET_ITER_REQUEST);
@@ -874,4 +1134,69 @@ GNUNET_SET_iterate (struct GNUNET_SET_Handle *set,
   return GNUNET_YES;
 }
 
+
+void
+GNUNET_SET_copy_lazy (struct GNUNET_SET_Handle *set,
+                      GNUNET_SET_CopyReadyCallback cb,
+                      void *cls)
+{
+  struct GNUNET_MQ_Envelope *ev;
+  struct SetCopyRequest *req;
+
+  ev = GNUNET_MQ_msg_header (GNUNET_MESSAGE_TYPE_SET_COPY_LAZY_PREPARE);
+  GNUNET_MQ_send (set->mq, ev);
+
+  req = GNUNET_new (struct SetCopyRequest);
+  req->cb = cb;
+  req->cls = cls;
+  GNUNET_CONTAINER_DLL_insert (set->copy_req_head,
+                               set->copy_req_tail,
+                               req);
+}
+
+
+/**
+ * Create a copy of an element.  The copy
+ * must be GNUNET_free-d by the caller.
+ *
+ * @param element the element to copy
+ * @return the copied element
+ */
+struct GNUNET_SET_Element *
+GNUNET_SET_element_dup (const struct GNUNET_SET_Element *element)
+{
+  struct GNUNET_SET_Element *copy;
+
+  copy = GNUNET_malloc (element->size + sizeof (struct GNUNET_SET_Element));
+  copy->size = element->size;
+  copy->element_type = element->element_type;
+  copy->data = &copy[1];
+  GNUNET_memcpy (&copy[1],
+                 element->data,
+                 copy->size);
+  return copy;
+}
+
+
+/**
+ * Hash a set element.
+ *
+ * @param element the element that should be hashed
+ * @param[out] ret_hash a pointer to where the hash of @a element
+ *        should be stored
+ */
+void
+GNUNET_SET_element_hash (const struct GNUNET_SET_Element *element,
+			 struct GNUNET_HashCode *ret_hash)
+{
+  struct GNUNET_HashContext *ctx = GNUNET_CRYPTO_hash_context_start ();
+
+  /* It's not guaranteed that the element data is always after the element header,
+     so we need to hash the chunks separately. */
+  GNUNET_CRYPTO_hash_context_read (ctx, &element->size, sizeof (uint16_t));
+  GNUNET_CRYPTO_hash_context_read (ctx, &element->element_type, sizeof (uint16_t));
+  GNUNET_CRYPTO_hash_context_read (ctx, element->data, element->size);
+  GNUNET_CRYPTO_hash_context_finish (ctx, ret_hash);
+}
+
 /* end of set_api.c */