2 This file is part of GNUnet.
3 (C) 2012, 2013 Christian Grothoff (and other contributing authors)
5 GNUnet is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published
7 by the Free Software Foundation; either version 3, or (at your
8 option) any later version.
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11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with GNUnet; see the file COPYING. If not, write to the
17 Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 Boston, MA 02111-1307, USA.
23 * @brief api for the set service
24 * @author Florian Dold
27 #include "gnunet_util_lib.h"
28 #include "gnunet_protocols.h"
29 #include "gnunet_client_lib.h"
30 #include "gnunet_set_service.h"
34 #define LOG(kind,...) GNUNET_log_from (kind, "set-api",__VA_ARGS__)
37 * Opaque handle to a set.
39 struct GNUNET_SET_Handle
42 * Client connected to the set service.
44 struct GNUNET_CLIENT_Connection *client;
47 * Message queue for 'client'.
49 struct GNUNET_MQ_Handle *mq;
52 * Linked list of operations on the set.
54 struct GNUNET_SET_OperationHandle *ops_head;
57 * Linked list of operations on the set.
59 struct GNUNET_SET_OperationHandle *ops_tail;
62 * Should the set be destroyed once all operations are gone?
64 int destroy_requested;
67 * Has the set become invalid (e.g. service died)?
72 * Callback for the current iteration over the set,
73 * NULL if no iterator is active.
75 GNUNET_SET_ElementIterator iterator;
78 * Closure for 'iterator'
85 * Opaque handle to a set operation request from another peer.
87 struct GNUNET_SET_Request
90 * Id of the request, used to identify the request when
91 * accepting/rejecting it.
96 * Has the request been accepted already?
97 * GNUNET_YES/GNUNET_NO
104 * Handle to an operation.
105 * Only known to the service after commiting
106 * the handle with a set.
108 struct GNUNET_SET_OperationHandle
111 * Function to be called when we have a result,
114 GNUNET_SET_ResultIterator result_cb;
117 * Closure for result_cb.
122 * Local set used for the operation,
123 * NULL if no set has been provided by conclude yet.
125 struct GNUNET_SET_Handle *set;
128 * Request ID to identify the operation within the set.
133 * Message sent to the server on calling conclude,
134 * NULL if conclude has been called.
136 struct GNUNET_MQ_Envelope *conclude_mqm;
139 * Address of the request if in the conclude message,
140 * used to patch the request id into the message when the set is known.
142 uint32_t *request_id_addr;
145 * Handles are kept in a linked list.
147 struct GNUNET_SET_OperationHandle *prev;
150 * Handles are kept in a linked list.
152 struct GNUNET_SET_OperationHandle *next;
157 * Opaque handle to a listen operation.
159 struct GNUNET_SET_ListenHandle
162 * Connection to the service.
164 struct GNUNET_CLIENT_Connection *client;
167 * Message queue for the client.
169 struct GNUNET_MQ_Handle* mq;
172 * Configuration handle for the listener, stored
173 * here to be able to reconnect transparently on
174 * connection failure.
176 const struct GNUNET_CONFIGURATION_Handle *cfg;
179 * Function to call on a new incoming request,
182 GNUNET_SET_ListenCallback listen_cb;
185 * Closure for listen_cb.
190 * Operation we listen for.
192 enum GNUNET_SET_OperationType operation;
195 * Application ID we listen for.
197 struct GNUNET_HashCode app_id;
200 * Time to wait until we try to reconnect on failure.
202 struct GNUNET_TIME_Relative reconnect_backoff;
205 * Task for reconnecting when the listener fails.
207 GNUNET_SCHEDULER_TaskIdentifier reconnect_task;
211 /* forward declaration */
213 listen_connect (void *cls,
214 const struct GNUNET_SCHEDULER_TaskContext *tc);
218 * Handle element for iteration over the set.
221 * @param mh the message
224 handle_iter_element (void *cls, const struct GNUNET_MessageHeader *mh)
226 struct GNUNET_SET_Handle *set = cls;
227 struct GNUNET_SET_Element element;
228 const struct GNUNET_SET_IterResponseMessage *msg =
229 (const struct GNUNET_SET_IterResponseMessage *) mh;
230 struct GNUNET_SET_IterAckMessage *ack_msg;
231 struct GNUNET_MQ_Envelope *ev;
233 if (NULL == set->iterator)
236 element.size = ntohs (mh->size) - sizeof (struct GNUNET_SET_IterResponseMessage);
237 element.type = htons (msg->element_type);
238 element.data = &msg[1];
239 set->iterator (set->iterator_cls, &element);
240 ev = GNUNET_MQ_msg (ack_msg, GNUNET_MESSAGE_TYPE_SET_ITER_ACK);
241 ack_msg->send_more = htonl (1);
242 GNUNET_MQ_send (set->mq, ev);
247 * Handle element for iteration over the set.
250 * @param mh the message
253 handle_iter_done (void *cls, const struct GNUNET_MessageHeader *mh)
255 struct GNUNET_SET_Handle *set = cls;
257 if (NULL == set->iterator)
260 set->iterator (set->iterator_cls, NULL);
265 * Handle result message for a set operation.
268 * @param mh the message
271 handle_result (void *cls, const struct GNUNET_MessageHeader *mh)
273 const struct GNUNET_SET_ResultMessage *msg;
274 struct GNUNET_SET_Handle *set = cls;
275 struct GNUNET_SET_OperationHandle *oh;
276 struct GNUNET_SET_Element e;
277 enum GNUNET_SET_Status result_status;
279 msg = (const struct GNUNET_SET_ResultMessage *) mh;
280 GNUNET_assert (NULL != set);
281 GNUNET_assert (NULL != set->mq);
283 result_status = ntohs (msg->result_status);
285 oh = GNUNET_MQ_assoc_get (set->mq, ntohl (msg->request_id));
286 GNUNET_assert (NULL != oh);
287 /* status is not STATUS_OK => there's no attached element,
288 * and this is the last result message we get */
289 if (GNUNET_SET_STATUS_OK != result_status)
291 GNUNET_MQ_assoc_remove (set->mq, ntohl (msg->request_id));
292 GNUNET_CONTAINER_DLL_remove (oh->set->ops_head, oh->set->ops_tail, oh);
293 if (GNUNET_YES == oh->set->destroy_requested)
294 GNUNET_SET_destroy (oh->set);
295 if (NULL != oh->result_cb)
296 oh->result_cb (oh->result_cls, NULL, result_status);
302 e.size = ntohs (mh->size) - sizeof (struct GNUNET_SET_ResultMessage);
303 e.type = msg->element_type;
304 if (NULL != oh->result_cb)
305 oh->result_cb (oh->result_cls, &e, result_status);
310 * Handle request message for a listen operation
312 * @param cls the listen handle
313 * @param mh the message
316 handle_request (void *cls, const struct GNUNET_MessageHeader *mh)
318 const struct GNUNET_SET_RequestMessage *msg = (const struct GNUNET_SET_RequestMessage *) mh;
319 struct GNUNET_SET_ListenHandle *lh = cls;
320 struct GNUNET_SET_Request *req;
321 struct GNUNET_MessageHeader *context_msg;
323 LOG (GNUNET_ERROR_TYPE_DEBUG, "processing operation request\n");
324 req = GNUNET_new (struct GNUNET_SET_Request);
325 req->accept_id = ntohl (msg->accept_id);
326 context_msg = GNUNET_MQ_extract_nested_mh (msg);
327 /* calling GNUNET_SET_accept in the listen cb will set req->accepted */
328 lh->listen_cb (lh->listen_cls, &msg->peer_id, context_msg, req);
330 /* we got another request => reset the backoff */
331 lh->reconnect_backoff = GNUNET_TIME_UNIT_MILLISECONDS;
333 if (GNUNET_NO == req->accepted)
335 struct GNUNET_MQ_Envelope *mqm;
336 struct GNUNET_SET_AcceptRejectMessage *amsg;
338 mqm = GNUNET_MQ_msg (amsg, GNUNET_MESSAGE_TYPE_SET_REJECT);
339 /* no request id, as we refused */
340 amsg->request_id = htonl (0);
341 amsg->accept_reject_id = msg->accept_id;
342 GNUNET_MQ_send (lh->mq, mqm);
343 LOG (GNUNET_ERROR_TYPE_DEBUG, "rejecting request\n");
347 LOG (GNUNET_ERROR_TYPE_DEBUG, "processed op request from service\n");
349 /* the accept-case is handled in GNUNET_SET_accept,
350 * as we have the accept message available there */
355 handle_client_listener_error (void *cls, enum GNUNET_MQ_Error error)
357 struct GNUNET_SET_ListenHandle *lh = cls;
359 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "listener broke down, re-connecting\n");
360 GNUNET_CLIENT_disconnect (lh->client);
362 GNUNET_MQ_destroy (lh->mq);
365 lh->reconnect_task = GNUNET_SCHEDULER_add_delayed (lh->reconnect_backoff, listen_connect, lh);
366 lh->reconnect_backoff = GNUNET_TIME_STD_BACKOFF (lh->reconnect_backoff);
371 * Destroy the set handle if no operations are left, mark the set
372 * for destruction otherwise.
374 * @param set set handle to destroy
377 set_destroy (struct GNUNET_SET_Handle *set)
379 if (NULL != set->ops_head)
381 set->destroy_requested = GNUNET_YES;
384 GNUNET_CLIENT_disconnect (set->client);
386 GNUNET_MQ_destroy (set->mq);
396 * Cancel the given set operation. We need to send an explicit cancel message,
397 * as all operations one one set communicate using one handle.
399 * In contrast to GNUNET_SET_operation_cancel, this function indicates whether
400 * the set of the operation has been destroyed because all operations are done and
401 * the set's destruction was requested before.
403 * @param oh set operation to cancel
404 * @return GNUNET_YES if the set of the operation was destroyed
407 set_operation_cancel (struct GNUNET_SET_OperationHandle *oh)
411 if (NULL != oh->conclude_mqm)
412 GNUNET_MQ_discard (oh->conclude_mqm);
414 /* is the operation already commited? */
417 struct GNUNET_SET_OperationHandle *h_assoc;
418 struct GNUNET_MQ_Envelope *mqm;
420 GNUNET_CONTAINER_DLL_remove (oh->set->ops_head, oh->set->ops_tail, oh);
421 h_assoc = GNUNET_MQ_assoc_remove (oh->set->mq, oh->request_id);
422 GNUNET_assert ((h_assoc == NULL) || (h_assoc == oh));
423 mqm = GNUNET_MQ_msg_header (GNUNET_MESSAGE_TYPE_SET_CANCEL);
424 GNUNET_MQ_send (oh->set->mq, mqm);
426 if (GNUNET_YES == oh->set->destroy_requested)
427 ret = set_destroy (oh->set);
437 * Cancel the given set operation. We need to send an explicit cancel message,
438 * as all operations one one set communicate using one handle.
440 * @param oh set operation to cancel
443 GNUNET_SET_operation_cancel (struct GNUNET_SET_OperationHandle *oh)
445 (void) set_operation_cancel (oh);
450 handle_client_set_error (void *cls, enum GNUNET_MQ_Error error)
452 struct GNUNET_SET_Handle *set = cls;
454 while (NULL != set->ops_head)
456 if (NULL != set->ops_head->result_cb)
457 set->ops_head->result_cb (set->ops_head->result_cls, NULL,
458 GNUNET_SET_STATUS_FAILURE);
459 if (GNUNET_YES == set_operation_cancel (set->ops_head))
460 return; /* stop if the set is destroyed */
462 set->invalid = GNUNET_YES;
467 * Create an empty set, supporting the specified operation.
469 * @param cfg configuration to use for connecting to the
471 * @param op operation supported by the set
472 * Note that the operation has to be specified
473 * beforehand, as certain set operations need to maintain
474 * data structures spefific to the operation
475 * @return a handle to the set
477 struct GNUNET_SET_Handle *
478 GNUNET_SET_create (const struct GNUNET_CONFIGURATION_Handle *cfg,
479 enum GNUNET_SET_OperationType op)
481 struct GNUNET_SET_Handle *set;
482 struct GNUNET_MQ_Envelope *mqm;
483 struct GNUNET_SET_CreateMessage *msg;
484 static const struct GNUNET_MQ_MessageHandler mq_handlers[] = {
485 {handle_result, GNUNET_MESSAGE_TYPE_SET_RESULT, 0},
486 {handle_iter_element, GNUNET_MESSAGE_TYPE_SET_ITER_ELEMENT, 0},
487 {handle_iter_done, GNUNET_MESSAGE_TYPE_SET_ITER_DONE, 0},
488 GNUNET_MQ_HANDLERS_END
491 set = GNUNET_new (struct GNUNET_SET_Handle);
492 set->client = GNUNET_CLIENT_connect ("set", cfg);
493 LOG (GNUNET_ERROR_TYPE_DEBUG, "set client created\n");
494 GNUNET_assert (NULL != set->client);
495 set->mq = GNUNET_MQ_queue_for_connection_client (set->client, mq_handlers,
496 handle_client_set_error, set);
497 GNUNET_assert (NULL != set->mq);
498 mqm = GNUNET_MQ_msg (msg, GNUNET_MESSAGE_TYPE_SET_CREATE);
499 msg->operation = htons (op);
500 GNUNET_MQ_send (set->mq, mqm);
506 * Add an element to the given set.
507 * After the element has been added (in the sense of being
508 * transmitted to the set service), cont will be called.
509 * Calls to add_element can be queued
511 * @param set set to add element to
512 * @param element element to add to the set
513 * @param cont continuation called after the element has been added
514 * @param cont_cls closure for @a cont
515 * @return #GNUNET_OK on success, #GNUNET_SYSERR if the
516 * set is invalid (e.g. the set service crashed)
519 GNUNET_SET_add_element (struct GNUNET_SET_Handle *set,
520 const struct GNUNET_SET_Element *element,
521 GNUNET_SET_Continuation cont,
524 struct GNUNET_MQ_Envelope *mqm;
525 struct GNUNET_SET_ElementMessage *msg;
527 if (GNUNET_YES == set->invalid)
531 return GNUNET_SYSERR;
534 mqm = GNUNET_MQ_msg_extra (msg, element->size, GNUNET_MESSAGE_TYPE_SET_ADD);
535 msg->element_type = element->type;
536 memcpy (&msg[1], element->data, element->size);
537 GNUNET_MQ_notify_sent (mqm, cont, cont_cls);
538 GNUNET_MQ_send (set->mq, mqm);
544 * Remove an element to the given set.
545 * After the element has been removed (in the sense of the
546 * request being transmitted to the set service), cont will be called.
547 * Calls to remove_element can be queued
549 * @param set set to remove element from
550 * @param element element to remove from the set
551 * @param cont continuation called after the element has been removed
552 * @param cont_cls closure for cont
553 * @return GNUNET_OK on success, GNUNET_SYSERR if the
554 * set is invalid (e.g. the set service crashed)
557 GNUNET_SET_remove_element (struct GNUNET_SET_Handle *set,
558 const struct GNUNET_SET_Element *element,
559 GNUNET_SET_Continuation cont,
562 struct GNUNET_MQ_Envelope *mqm;
563 struct GNUNET_SET_ElementMessage *msg;
565 if (GNUNET_YES == set->invalid)
569 return GNUNET_SYSERR;
572 mqm = GNUNET_MQ_msg_extra (msg, element->size, GNUNET_MESSAGE_TYPE_SET_REMOVE);
573 msg->element_type = element->type;
574 memcpy (&msg[1], element->data, element->size);
575 GNUNET_MQ_notify_sent (mqm, cont, cont_cls);
576 GNUNET_MQ_send (set->mq, mqm);
582 * Destroy the set handle, and free all associated resources.
584 * @param set set handle to destroy
587 GNUNET_SET_destroy (struct GNUNET_SET_Handle *set)
589 (void) set_destroy (set);
594 * Prepare a set operation to be evaluated with another peer.
595 * The evaluation will not start until the client provides
596 * a local set with GNUNET_SET_commit.
598 * @param other_peer peer with the other set
599 * @param app_id hash for the application using the set
600 * @param context_msg additional information for the request
601 * @param salt salt used for the set operation; sometimes set operations
602 * fail due to hash collisions, using a different salt for each operation
603 * makes it harder for an attacker to exploit this
604 * @param result_mode specified how results will be returned,
605 * see 'GNUNET_SET_ResultMode'.
606 * @param result_cb called on error or success
607 * @param result_cls closure for result_cb
608 * @return a handle to cancel the operation
610 struct GNUNET_SET_OperationHandle *
611 GNUNET_SET_prepare (const struct GNUNET_PeerIdentity *other_peer,
612 const struct GNUNET_HashCode *app_id,
613 const struct GNUNET_MessageHeader *context_msg,
615 enum GNUNET_SET_ResultMode result_mode,
616 GNUNET_SET_ResultIterator result_cb,
619 struct GNUNET_MQ_Envelope *mqm;
620 struct GNUNET_SET_OperationHandle *oh;
621 struct GNUNET_SET_EvaluateMessage *msg;
623 oh = GNUNET_new (struct GNUNET_SET_OperationHandle);
624 oh->result_cb = result_cb;
625 oh->result_cls = result_cls;
627 mqm = GNUNET_MQ_msg_nested_mh (msg, GNUNET_MESSAGE_TYPE_SET_EVALUATE, context_msg);
629 msg->app_id = *app_id;
630 msg->result_mode = htons (result_mode);
631 msg->target_peer = *other_peer;
633 oh->conclude_mqm = mqm;
634 oh->request_id_addr = &msg->request_id;
641 * Connect to the set service in order to listen
644 * @param cls the listen handle to connect
645 * @param tc task context if invoked as a task, NULL otherwise
648 listen_connect (void *cls,
649 const struct GNUNET_SCHEDULER_TaskContext *tc)
651 struct GNUNET_MQ_Envelope *mqm;
652 struct GNUNET_SET_ListenMessage *msg;
653 struct GNUNET_SET_ListenHandle *lh = cls;
654 static const struct GNUNET_MQ_MessageHandler mq_handlers[] = {
655 {handle_request, GNUNET_MESSAGE_TYPE_SET_REQUEST},
656 GNUNET_MQ_HANDLERS_END
659 if ((tc != NULL) &&(tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN) != 0)
661 LOG (GNUNET_ERROR_TYPE_DEBUG, "listener not reconnecting due to shutdown\n");
665 lh->reconnect_task = GNUNET_SCHEDULER_NO_TASK;
667 GNUNET_assert (NULL == lh->client);
668 lh->client = GNUNET_CLIENT_connect ("set", lh->cfg);
669 if (NULL == lh->client)
671 LOG (GNUNET_ERROR_TYPE_ERROR,
672 "could not connect to set (wrong configuration?), giving up listening\n");
675 GNUNET_assert (NULL == lh->mq);
676 lh->mq = GNUNET_MQ_queue_for_connection_client (lh->client, mq_handlers,
677 handle_client_listener_error, lh);
678 mqm = GNUNET_MQ_msg (msg, GNUNET_MESSAGE_TYPE_SET_LISTEN);
679 msg->operation = htonl (lh->operation);
680 msg->app_id = lh->app_id;
681 GNUNET_MQ_send (lh->mq, mqm);
686 * Wait for set operation requests for the given application id
688 * @param cfg configuration to use for connecting to
689 * the set service, needs to be valid for the lifetime of the listen handle
690 * @param operation operation we want to listen for
691 * @param app_id id of the application that handles set operation requests
692 * @param listen_cb called for each incoming request matching the operation
694 * @param listen_cls handle for listen_cb
695 * @return a handle that can be used to cancel the listen operation
697 struct GNUNET_SET_ListenHandle *
698 GNUNET_SET_listen (const struct GNUNET_CONFIGURATION_Handle *cfg,
699 enum GNUNET_SET_OperationType operation,
700 const struct GNUNET_HashCode *app_id,
701 GNUNET_SET_ListenCallback listen_cb,
704 struct GNUNET_SET_ListenHandle *lh;
706 lh = GNUNET_new (struct GNUNET_SET_ListenHandle);
707 lh->listen_cb = listen_cb;
708 lh->listen_cls = listen_cls;
710 lh->operation = operation;
711 lh->app_id = *app_id;
712 lh->reconnect_backoff = GNUNET_TIME_UNIT_MILLISECONDS;
713 listen_connect (lh, NULL);
719 * Cancel the given listen operation.
721 * @param lh handle for the listen operation
724 GNUNET_SET_listen_cancel (struct GNUNET_SET_ListenHandle *lh)
726 LOG (GNUNET_ERROR_TYPE_DEBUG, "canceling listener\n");
727 /* listener's connection may have failed, thus mq/client could be NULL */
730 GNUNET_MQ_destroy (lh->mq);
733 if (NULL != lh->client)
735 GNUNET_CLIENT_disconnect (lh->client);
738 if (GNUNET_SCHEDULER_NO_TASK != lh->reconnect_task)
740 GNUNET_SCHEDULER_cancel (lh->reconnect_task);
741 lh->reconnect_task = GNUNET_SCHEDULER_NO_TASK;
748 * Accept a request we got via #GNUNET_SET_listen. Must be called during
749 * #GNUNET_SET_listen, as the 'struct GNUNET_SET_Request' becomes invalid
751 * Call #GNUNET_SET_commit to provide the local set to use for the operation,
752 * and to begin the exchange with the remote peer.
754 * @param request request to accept
755 * @param result_mode specified how results will be returned,
756 * see 'GNUNET_SET_ResultMode'.
757 * @param result_cb callback for the results
758 * @param result_cls closure for result_cb
759 * @return a handle to cancel the operation
761 struct GNUNET_SET_OperationHandle *
762 GNUNET_SET_accept (struct GNUNET_SET_Request *request,
763 enum GNUNET_SET_ResultMode result_mode,
764 GNUNET_SET_ResultIterator result_cb,
767 struct GNUNET_MQ_Envelope *mqm;
768 struct GNUNET_SET_OperationHandle *oh;
769 struct GNUNET_SET_AcceptRejectMessage *msg;
771 GNUNET_assert (NULL != request);
772 GNUNET_assert (GNUNET_NO == request->accepted);
773 request->accepted = GNUNET_YES;
775 oh = GNUNET_new (struct GNUNET_SET_OperationHandle);
776 oh->result_cb = result_cb;
777 oh->result_cls = result_cls;
779 mqm = GNUNET_MQ_msg (msg, GNUNET_MESSAGE_TYPE_SET_ACCEPT);
780 msg->accept_reject_id = htonl (request->accept_id);
781 msg->result_mode = htons (result_mode);
783 oh->conclude_mqm = mqm;
784 oh->request_id_addr = &msg->request_id;
791 * Commit a set to be used with a set operation.
792 * This function is called once we have fully constructed
793 * the set that we want to use for the operation. At this
794 * time, the P2P protocol can then begin to exchange the
795 * set information and call the result callback with the
796 * result information.
798 * @param oh handle to the set operation
799 * @param set the set to use for the operation
800 * @return #GNUNET_OK on success, #GNUNET_SYSERR if the
801 * set is invalid (e.g. the set service crashed)
804 GNUNET_SET_commit (struct GNUNET_SET_OperationHandle *oh,
805 struct GNUNET_SET_Handle *set)
807 GNUNET_assert (NULL == oh->set);
808 if (GNUNET_YES == set->invalid)
809 return GNUNET_SYSERR;
810 GNUNET_assert (NULL != oh->conclude_mqm);
812 GNUNET_CONTAINER_DLL_insert (set->ops_head, set->ops_tail, oh);
813 oh->request_id = GNUNET_MQ_assoc_add (set->mq, oh);
814 *oh->request_id_addr = htonl (oh->request_id);
815 GNUNET_MQ_send (set->mq, oh->conclude_mqm);
816 oh->conclude_mqm = NULL;
817 oh->request_id_addr = NULL;
823 * Iterate over all elements in the given set.
824 * Note that this operation involves transferring every element of the set
825 * from the service to the client, and is thus costly.
827 * @param set the set to iterate over
828 * @param iter the iterator to call for each element
829 * @param cls closure for @a iter
830 * @return #GNUNET_YES if the iteration started successfuly,
831 * #GNUNET_NO if another iteration is active
832 * #GNUNET_SYSERR if the set is invalid (e.g. the server crashed, disconnected)
835 GNUNET_SET_iterate (struct GNUNET_SET_Handle *set, GNUNET_SET_ElementIterator iter, void *cls)
837 struct GNUNET_MQ_Envelope *ev;
839 GNUNET_assert (NULL != iter);
841 if (GNUNET_YES == set->invalid)
842 return GNUNET_SYSERR;
843 if (NULL != set->iterator)
846 set->iterator = iter;
847 set->iterator_cls = cls;
848 ev = GNUNET_MQ_msg_header (GNUNET_MESSAGE_TYPE_SET_ITER_REQUEST);
849 GNUNET_MQ_send (set->mq, ev);
853 /* end of set_api.c */