2 This file is part of GNUnet.
3 (C) 2009, 2010 Christian Grothoff (and other contributing authors)
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23 * @brief library to access the DHT service
24 * @author Christian Grothoff
25 * @author Nathan Evans
29 #include "gnunet_bandwidth_lib.h"
30 #include "gnunet_client_lib.h"
31 #include "gnunet_constants.h"
32 #include "gnunet_container_lib.h"
33 #include "gnunet_arm_service.h"
34 #include "gnunet_hello_lib.h"
35 #include "gnunet_protocols.h"
36 #include "gnunet_server_lib.h"
37 #include "gnunet_time_lib.h"
38 #include "gnunet_dht_service.h"
41 #define DEBUG_DHT_API GNUNET_NO
44 * Entry in our list of messages to be (re-)transmitted.
49 * This is a doubly-linked list.
51 struct PendingMessage *prev;
54 * This is a doubly-linked list.
56 struct PendingMessage *next;
59 * Message that is pending, allocated at the end
62 const struct GNUNET_MessageHeader *msg;
65 * Handle to the DHT API context.
67 struct GNUNET_DHT_Handle *handle;
70 * Continuation to call when the request has been
71 * transmitted (for the first time) to the service; can be NULL.
73 GNUNET_SCHEDULER_Task cont;
81 * Timeout task for this message
83 GNUNET_SCHEDULER_TaskIdentifier timeout_task;
86 * Unique ID for this request
91 * Free the saved message once sent, set to GNUNET_YES for messages
92 * that do not receive responses; GNUNET_NO if this pending message
93 * is aliased from a 'struct GNUNET_DHT_RouteHandle' and will be freed
99 * GNUNET_YES if this message is in our pending queue right now.
101 int in_pending_queue;
107 * Handle to a route request
109 struct GNUNET_DHT_RouteHandle
113 * Iterator to call on data receipt
115 GNUNET_DHT_ReplyProcessor iter;
118 * Closure for the iterator callback
123 * Main handle to this DHT api
125 struct GNUNET_DHT_Handle *dht_handle;
128 * The actual message sent for this request,
129 * used for retransmitting requests on service
130 * failure/reconnect. Freed on route_stop.
132 struct PendingMessage *message;
135 * Key that this get request is for
140 * Unique identifier for this request (for key collisions). FIXME: redundant!?
148 * Connection to the DHT service.
150 struct GNUNET_DHT_Handle
155 struct GNUNET_SCHEDULER_Handle *sched;
158 * Configuration to use.
160 const struct GNUNET_CONFIGURATION_Handle *cfg;
163 * Socket (if available).
165 struct GNUNET_CLIENT_Connection *client;
168 * Currently pending transmission request (or NULL).
170 struct GNUNET_CLIENT_TransmitHandle *th;
173 * Head of linked list of messages we would like to transmit.
175 struct PendingMessage *pending_head;
178 * Tail of linked list of messages we would like to transmit.
180 struct PendingMessage *pending_tail;
183 * Hash map containing the current outstanding unique requests
184 * (values are of type 'struct GNUNET_DHT_RouteHandle').
186 struct GNUNET_CONTAINER_MultiHashMap *active_requests;
189 * Generator for unique ids.
197 * Transmit the next pending message, called by notify_transmit_ready
200 transmit_pending (void *cls,
206 * Handler for messages received from the DHT service
207 * a demultiplexer which handles numerous message types
211 service_message_handler (void *cls,
212 const struct GNUNET_MessageHeader *msg);
218 * Try to (re)connect to the DHT service.
220 * @return GNUNET_YES on success, GNUNET_NO on failure.
223 try_connect (struct GNUNET_DHT_Handle *handle)
225 if (handle->client != NULL)
227 handle->client = GNUNET_CLIENT_connect (handle->sched, "dht", handle->cfg);
228 if (handle->client == NULL)
230 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
231 _("Failed to connect to the DHT service!\n"));
234 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
235 "Starting to process replies from DHT\n");
236 GNUNET_CLIENT_receive (handle->client,
237 &service_message_handler,
239 GNUNET_TIME_UNIT_FOREVER_REL);
245 * Add the request corresponding to the given route handle
246 * to the pending queue (if it is not already in there).
248 * @param cls the 'struct GNUNET_DHT_Handle*'
249 * @param key key for the request (not used)
250 * @param value the 'struct GNUNET_DHT_RouteHandle*'
251 * @return GNUNET_YES (always)
254 add_request_to_pending (void *cls,
255 const GNUNET_HashCode *key,
258 struct GNUNET_DHT_Handle *handle = cls;
259 struct GNUNET_DHT_RouteHandle *rh = value;
261 if (GNUNET_NO == rh->message->in_pending_queue)
263 GNUNET_CONTAINER_DLL_insert (handle->pending_head,
264 handle->pending_tail,
266 rh->message->in_pending_queue = GNUNET_YES;
273 * Re-connect to the DHT, re-issue all pending requests if needed.
276 reconnect (struct GNUNET_DHT_Handle *handle)
278 if (handle->client != NULL)
280 GNUNET_CLIENT_disconnect (handle->client,
282 handle->client = NULL;
284 if (GNUNET_YES != try_connect (handle))
286 GNUNET_CONTAINER_multihashmap_iterate (handle->active_requests,
287 &add_request_to_pending,
289 if (handle->pending_head == NULL)
291 GNUNET_CLIENT_notify_transmit_ready (handle->client,
292 ntohs(handle->pending_head->msg->size),
293 GNUNET_TIME_UNIT_FOREVER_REL,
302 * Try to send messages from list of messages to send
305 process_pending_messages (struct GNUNET_DHT_Handle *handle)
307 struct PendingMessage *head;
309 if (GNUNET_YES != try_connect (handle))
311 if (handle->th != NULL)
313 if (NULL == (head = handle->pending_head))
315 handle->th = GNUNET_CLIENT_notify_transmit_ready (handle->client,
316 ntohs (head->msg->size),
317 GNUNET_TIME_UNIT_FOREVER_REL,
321 if (NULL == handle->th)
330 * Transmit the next pending message, called by notify_transmit_ready
333 transmit_pending (void *cls,
337 struct GNUNET_DHT_Handle *handle = cls;
338 struct PendingMessage *head;
347 if (NULL == (head = handle->pending_head))
350 tsize = ntohs (head->msg->size);
353 process_pending_messages (handle);
356 memcpy (buf, head->msg, tsize);
357 GNUNET_CONTAINER_DLL_remove (handle->pending_head,
358 handle->pending_tail,
360 if (head->timeout_task != GNUNET_SCHEDULER_NO_TASK)
362 GNUNET_SCHEDULER_cancel (handle->sched,
364 head->timeout_task = GNUNET_SCHEDULER_NO_TASK;
366 if (NULL != head->cont)
368 GNUNET_SCHEDULER_add_continuation (handle->sched,
371 GNUNET_SCHEDULER_REASON_PREREQ_DONE);
373 head->cont_cls = NULL;
375 head->in_pending_queue = GNUNET_NO;
376 if (GNUNET_YES == head->free_on_send)
378 process_pending_messages (handle);
379 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
380 "Forwarded request of %u bytes to DHT service\n",
381 (unsigned int) tsize);
389 * Process a given reply that might match the given
393 process_reply (void *cls,
394 const GNUNET_HashCode *key,
397 const struct GNUNET_DHT_RouteResultMessage *dht_msg = cls;
398 struct GNUNET_DHT_RouteHandle *rh = value;
399 const struct GNUNET_MessageHeader *enc_msg;
402 const struct GNUNET_PeerIdentity **get_path;
403 const struct GNUNET_PeerIdentity **put_path;
404 const struct GNUNET_PeerIdentity *pos;
409 uid = GNUNET_ntohll (dht_msg->unique_id);
412 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
413 "Reply UID did not match request UID\n");
416 enc_size = ntohs (dht_msg->header.size) - sizeof (struct GNUNET_DHT_RouteResultMessage);
417 if (enc_size < sizeof (struct GNUNET_MessageHeader))
422 pos = (const struct GNUNET_PeerIdentity *) &dht_msg[1];
423 ppl = ntohs (dht_msg->put_path_length);
424 gpl = ntohs (dht_msg->get_path_length);
425 if ( (ppl + gpl) * sizeof (struct GNUNET_PeerIdentity) > enc_size)
432 put_path = GNUNET_malloc ((ppl+1) * sizeof (struct GNUNET_PeerIdentity*));
438 put_path[ppl] = NULL;
444 get_path = GNUNET_malloc ((gpl+1) * sizeof (struct GNUNET_PeerIdentity*));
450 get_path[gpl] = NULL;
454 enc_size -= (ppl + gpl) * sizeof (struct GNUNET_PeerIdentity);
455 enc_msg = (const struct GNUNET_MessageHeader *) pos;
456 if (enc_size != ntohs (enc_msg->size))
459 GNUNET_free_non_null (get_path);
460 GNUNET_free_non_null (put_path);
463 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
464 "Processing reply.\n");
465 rh->iter (rh->iter_cls,
470 GNUNET_free_non_null (get_path);
471 GNUNET_free_non_null (put_path);
477 * Handler for messages received from the DHT service
478 * a demultiplexer which handles numerous message types
480 * @param cls the 'struct GNUNET_DHT_Handle'
481 * @param msg the incoming message
484 service_message_handler (void *cls,
485 const struct GNUNET_MessageHeader *msg)
487 struct GNUNET_DHT_Handle *handle = cls;
488 const struct GNUNET_DHT_RouteResultMessage *dht_msg;
492 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
493 "Error receiving data from DHT service, reconnecting\n");
497 if (ntohs (msg->type) != GNUNET_MESSAGE_TYPE_DHT_LOCAL_ROUTE_RESULT)
503 if (ntohs (msg->size) < sizeof (struct GNUNET_DHT_RouteResultMessage))
509 dht_msg = (const struct GNUNET_DHT_RouteResultMessage *) msg;
510 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
511 "Comparing reply `%s' against %u pending requests.\n",
512 GNUNET_h2s (&dht_msg->key),
513 GNUNET_CONTAINER_multihashmap_size (handle->active_requests));
514 GNUNET_CONTAINER_multihashmap_get_multiple (handle->active_requests,
518 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
519 "Continuing to process replies from DHT\n");
520 GNUNET_CLIENT_receive (handle->client,
521 &service_message_handler,
522 handle, GNUNET_TIME_UNIT_FOREVER_REL);
528 * Initialize the connection with the DHT service.
530 * @param sched scheduler to use
531 * @param cfg configuration to use
532 * @param ht_len size of the internal hash table to use for
533 * processing multiple GET/FIND requests in parallel
535 * @return handle to the DHT service, or NULL on error
537 struct GNUNET_DHT_Handle *
538 GNUNET_DHT_connect (struct GNUNET_SCHEDULER_Handle *sched,
539 const struct GNUNET_CONFIGURATION_Handle *cfg,
542 struct GNUNET_DHT_Handle *handle;
544 handle = GNUNET_malloc (sizeof (struct GNUNET_DHT_Handle));
546 handle->sched = sched;
547 handle->uid_gen = GNUNET_CRYPTO_random_u64(GNUNET_CRYPTO_QUALITY_WEAK, UINT64_MAX);
548 handle->active_requests = GNUNET_CONTAINER_multihashmap_create (ht_len);
549 if (GNUNET_NO == try_connect (handle))
551 GNUNET_DHT_disconnect (handle);
559 * Shutdown connection with the DHT service.
561 * @param handle handle of the DHT connection to stop
564 GNUNET_DHT_disconnect (struct GNUNET_DHT_Handle *handle)
566 struct PendingMessage *pm;
568 GNUNET_assert (0 == GNUNET_CONTAINER_multihashmap_size(handle->active_requests));
569 if (handle->th != NULL)
571 GNUNET_CLIENT_notify_transmit_ready_cancel (handle->th);
574 while (NULL != (pm = handle->pending_head))
576 GNUNET_CONTAINER_DLL_remove (handle->pending_head,
577 handle->pending_tail,
579 GNUNET_assert (GNUNET_YES == pm->free_on_send);
580 if (GNUNET_SCHEDULER_NO_TASK != pm->timeout_task)
581 GNUNET_SCHEDULER_cancel (handle->sched,
583 if (NULL != pm->cont)
584 GNUNET_SCHEDULER_add_continuation (handle->sched,
587 GNUNET_SCHEDULER_REASON_TIMEOUT);
588 pm->in_pending_queue = GNUNET_NO;
591 if (handle->client != NULL)
593 GNUNET_CLIENT_disconnect (handle->client, GNUNET_YES);
594 handle->client = NULL;
596 GNUNET_CONTAINER_multihashmap_destroy(handle->active_requests);
597 GNUNET_free (handle);
603 /* ***** Special low-level API providing generic routing abstraction ***** */
607 * Timeout for the transmission of a fire&forget-request. Clean it up.
609 * @param cls the 'struct PendingMessage'
610 * @param tc scheduler context
613 timeout_route_request (void *cls,
614 const struct GNUNET_SCHEDULER_TaskContext *tc)
616 struct PendingMessage *pending = cls;
617 struct GNUNET_DHT_Handle *handle;
619 if (pending->free_on_send != GNUNET_YES)
621 /* timeouts should only apply to fire & forget requests! */
625 handle = pending->handle;
626 GNUNET_CONTAINER_DLL_remove (handle->pending_head,
627 handle->pending_tail,
629 if (pending->cont != NULL)
630 pending->cont (pending->cont_cls,
632 GNUNET_free (pending);
637 * Initiate a generic DHT route operation.
639 * @param handle handle to the DHT service
640 * @param key the key to look up
641 * @param desired_replication_level how many peers should ultimately receive
642 * this message (advisory only, target may be too high for the
643 * given DHT or not hit exactly).
644 * @param options options for routing
645 * @param enc send the encapsulated message to a peer close to the key
646 * @param iter function to call on each result, NULL if no replies are expected
647 * @param iter_cls closure for iter
648 * @param timeout when to abort with an error if we fail to get
649 * a confirmation for the request (when necessary) or how long
650 * to wait for tramission to the service; only applies
652 * @param cont continuation to call when the request has been transmitted
653 * the first time to the service
654 * @param cont_cls closure for cont
655 * @return handle to stop the request, NULL if the request is "fire and forget"
657 struct GNUNET_DHT_RouteHandle *
658 GNUNET_DHT_route_start (struct GNUNET_DHT_Handle *handle,
659 const GNUNET_HashCode *key,
660 uint32_t desired_replication_level,
661 enum GNUNET_DHT_RouteOption options,
662 const struct GNUNET_MessageHeader *enc,
663 struct GNUNET_TIME_Relative timeout,
664 GNUNET_DHT_ReplyProcessor iter,
666 GNUNET_SCHEDULER_Task cont,
669 struct PendingMessage *pending;
670 struct GNUNET_DHT_RouteMessage *message;
671 struct GNUNET_DHT_RouteHandle *route_handle;
675 esize = ntohs (enc->size);
676 if (sizeof (struct GNUNET_DHT_RouteMessage) + esize >= GNUNET_SERVER_MAX_MESSAGE_SIZE)
681 msize = sizeof (struct GNUNET_DHT_RouteMessage) + esize;
682 pending = GNUNET_malloc (sizeof (struct PendingMessage) + msize);
683 message = (struct GNUNET_DHT_RouteMessage*) &pending[1];
684 pending->msg = &message->header;
685 pending->handle = handle;
686 pending->cont = cont;
687 pending->cont_cls = cont_cls;
689 message->header.size = htons (msize);
690 message->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_LOCAL_ROUTE);
692 message->options = htonl ((uint32_t) options);
693 message->desired_replication_level = htonl (desired_replication_level);
695 message->unique_id = GNUNET_htonll (handle->uid_gen);
696 memcpy (&message[1], enc, esize);
700 route_handle = GNUNET_malloc (sizeof (struct GNUNET_DHT_RouteHandle));
701 route_handle->key = *key;
702 route_handle->iter = iter;
703 route_handle->iter_cls = iter_cls;
704 route_handle->dht_handle = handle;
705 route_handle->uid = handle->uid_gen;
706 route_handle->message = pending;
707 GNUNET_CONTAINER_multihashmap_put (handle->active_requests,
710 GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE);
715 pending->free_on_send = GNUNET_YES;
716 pending->timeout_task = GNUNET_SCHEDULER_add_delayed (handle->sched,
718 &timeout_route_request,
721 GNUNET_CONTAINER_DLL_insert (handle->pending_head,
722 handle->pending_tail,
724 pending->in_pending_queue = GNUNET_YES;
725 process_pending_messages (handle);
726 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
727 "DHT route start request processed, returning %p\n",
734 * Stop a previously issued routing request
736 * @param route_handle handle to the request to stop
739 GNUNET_DHT_route_stop (struct GNUNET_DHT_RouteHandle *route_handle)
741 struct GNUNET_DHT_Handle *handle;
742 struct PendingMessage *pending;
743 struct GNUNET_DHT_StopMessage *message;
746 handle = route_handle->dht_handle;
747 if (GNUNET_NO == route_handle->message->in_pending_queue)
749 /* need to send stop message */
750 msize = sizeof (struct GNUNET_DHT_StopMessage);
751 pending = GNUNET_malloc (sizeof (struct PendingMessage) +
753 message = (struct GNUNET_DHT_StopMessage*) &pending[1];
754 pending->msg = &message->header;
755 message->header.size = htons (msize);
756 message->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_LOCAL_ROUTE_STOP);
757 message->unique_id = GNUNET_htonll (route_handle->uid);
758 message->key = route_handle->key;
759 pending->handle = handle;
760 pending->free_on_send = GNUNET_YES;
761 pending->in_pending_queue = GNUNET_YES;
762 GNUNET_CONTAINER_DLL_insert (handle->pending_head,
763 handle->pending_tail,
765 process_pending_messages (handle);
769 /* simply remove pending request from message queue before
770 transmission, no need to transmit STOP request! */
771 GNUNET_CONTAINER_DLL_remove (handle->pending_head,
772 handle->pending_tail,
773 route_handle->message);
775 GNUNET_assert (GNUNET_YES ==
776 GNUNET_CONTAINER_multihashmap_remove (route_handle->dht_handle->active_requests,
779 GNUNET_free(route_handle->message);
780 GNUNET_free(route_handle);
781 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
782 "DHT route stop request processed\n");
787 /* ***** Special API for controlling DHT routing maintenance ******* */
791 * Send a control message to the DHT.
793 * @param handle handle to the DHT service
794 * @param command command
795 * @param variable variable to the command
796 * @param cont continuation to call when done (transmitting request to service)
797 * @param cont_cls closure for cont
800 send_control_message (struct GNUNET_DHT_Handle *handle,
803 GNUNET_SCHEDULER_Task cont,
806 struct GNUNET_DHT_ControlMessage *msg;
807 struct PendingMessage *pending;
809 pending = GNUNET_malloc (sizeof (struct PendingMessage) +
810 sizeof(struct GNUNET_DHT_ControlMessage));
811 msg = (struct GNUNET_DHT_ControlMessage*) &pending[1];
812 pending->msg = &msg->header;
813 msg->header.size = htons (sizeof(struct GNUNET_DHT_ControlMessage));
814 msg->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_CONTROL);
815 msg->command = htons (command);
816 msg->variable = htons (variable);
817 pending->free_on_send = GNUNET_YES;
818 pending->cont = cont;
819 pending->cont_cls = cont_cls;
820 pending->in_pending_queue = GNUNET_YES;
821 GNUNET_CONTAINER_DLL_insert (handle->pending_head,
822 handle->pending_tail,
824 process_pending_messages (handle);
829 * Send a message to the DHT telling it to issue a single find
830 * peer request using the peers unique identifier as key. This
831 * is used to fill the routing table, and is normally controlled
832 * by the DHT itself. However, for testing and perhaps more
833 * close control over the DHT, this can be explicitly managed.
835 * @param handle handle to the DHT service
836 * @param cont continuation to call when done (transmitting request to service)
837 * @param cont_cls closure for cont
840 GNUNET_DHT_find_peers (struct GNUNET_DHT_Handle *handle,
841 GNUNET_SCHEDULER_Task cont,
844 send_control_message (handle,
845 GNUNET_MESSAGE_TYPE_DHT_FIND_PEER, 0,
854 * Send a message to the DHT telling it to start issuing random GET
855 * requests every 'frequency' milliseconds.
857 * @param handle handle to the DHT service
858 * @param frequency delay between sending malicious messages
861 GNUNET_DHT_set_malicious_getter (struct GNUNET_DHT_Handle *handle,
862 struct GNUNET_TIME_Relative frequency)
864 if (frequency.rel_value > UINT16_MAX)
869 send_control_message (handle,
870 GNUNET_MESSAGE_TYPE_DHT_MALICIOUS_GET, frequency.rel_value,
875 * Send a message to the DHT telling it to start issuing random PUT
876 * requests every 'frequency' milliseconds.
878 * @param handle handle to the DHT service
879 * @param frequency delay between sending malicious messages
882 GNUNET_DHT_set_malicious_putter (struct GNUNET_DHT_Handle *handle,
883 struct GNUNET_TIME_Relative frequency)
885 if (frequency.rel_value > UINT16_MAX)
891 send_control_message (handle,
892 GNUNET_MESSAGE_TYPE_DHT_MALICIOUS_PUT, frequency.rel_value,
898 * Send a message to the DHT telling it to start dropping
899 * all requests received.
901 * @param handle handle to the DHT service
904 GNUNET_DHT_set_malicious_dropper (struct GNUNET_DHT_Handle *handle)
906 send_control_message (handle,
907 GNUNET_MESSAGE_TYPE_DHT_MALICIOUS_DROP, 0,
913 /* end of dht_api.c */