2 This file is part of GNUnet.
3 (C) 2009, 2010, 2011 Christian Grothoff (and other contributing authors)
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22 * @file dht/gnunet-service-dht_clients.c
23 * @brief GNUnet DHT service's client management code
24 * @author Christian Grothoff
25 * @author Nathan Evans
29 #include "gnunet_block_lib.h"
30 #include "gnunet_util_lib.h"
31 #include "gnunet_protocols.h"
32 #include "gnunet_nse_service.h"
33 #include "gnunet_core_service.h"
34 #include "gnunet_datacache_lib.h"
35 #include "gnunet_transport_service.h"
36 #include "gnunet_hello_lib.h"
37 #include "gnunet_dht_service.h"
38 #include "gnunet_statistics_service.h"
41 #include "gnunet-service-dht_clients.h"
42 #include "gnunet-service-dht_datacache.h"
43 #include "gnunet-service-dht_neighbours.h"
47 * Linked list of messages to send to clients.
52 * Pointer to next item in the list
54 struct PendingMessage *next;
57 * Pointer to previous item in the list
59 struct PendingMessage *prev;
62 * Actual message to be sent, allocated at the end of the struct:
63 * // msg = (cast) &pm[1];
64 * // memcpy (&pm[1], data, len);
66 const struct GNUNET_MessageHeader *msg;
72 * Struct containing information about a client,
73 * handle to connect to it, and any pending messages
74 * that need to be sent to it.
79 * Linked list of active clients
81 struct ClientList *next;
84 * Linked list of active clients
86 struct ClientList *prev;
89 * The handle to this client
91 struct GNUNET_SERVER_Client *client_handle;
94 * Handle to the current transmission request, NULL
97 struct GNUNET_CONNECTION_TransmitHandle *transmit_handle;
100 * Linked list of pending messages for this client
102 struct PendingMessage *pending_head;
105 * Tail of linked list of pending messages for this client
107 struct PendingMessage *pending_tail;
113 * Entry in the DHT routing table for a client's GET request.
115 struct ClientQueryRecord
119 * The key this request was about
124 * Client responsible for the request.
126 struct ClientList *client;
129 * Extended query (see gnunet_block_lib.h), allocated at the end of this struct.
134 * Replies we have already seen for this request.
136 GNUNET_HashCode *seen_replies;
139 * Pointer to this nodes heap location in the retry-heap (for fast removal)
141 struct GNUNET_CONTAINER_HeapNode *hnode;
144 * What's the delay between re-try operations that we currently use for this
147 struct GNUNET_TIME_Relative retry_frequency;
150 * What's the next time we should re-try this request?
152 struct GNUNET_TIME_Absolute retry_time;
155 * The unique identifier of this request
160 * Number of bytes in xquery.
165 * Number of entries in 'seen_replies'.
167 unsigned int seen_replies_count;
170 * Desired replication level
172 uint32_t replication;
175 * Any message options for this request
177 uint32_t msg_options;
180 * The type for the data for the GET request; actually an 'enum
181 * GNUNET_BLOCK_Type'.
189 * List of active clients.
191 static struct ClientList *client_head;
194 * List of active clients.
196 static struct ClientList *client_tail;
199 * Hashmap for fast key based lookup, maps keys to 'struct ClientQueryRecord' entries.
201 static struct GNUNET_CONTAINER_MultiHashMap *forward_map;
204 * Heap with all of our client's request, sorted by retry time (earliest on top).
206 static struct GNUNET_CONTAINER_Heap *retry_heap;
209 * Task that re-transmits requests (using retry_heap).
211 static GNUNET_SCHEDULER_TaskIdentifier retry_task;
215 * Find a client if it exists, add it otherwise.
217 * @param client the server handle to the client
219 * @return the client if found, a new client otherwise
221 static struct ClientList *
222 find_active_client (struct GNUNET_SERVER_Client *client)
224 struct ClientList *pos = client_list;
225 struct ClientList *ret;
229 if (pos->client_handle == client)
233 ret = GNUNET_malloc (sizeof (struct ClientList));
234 ret->client_handle = client;
235 GNUNET_CONTAINER_DLL_insert (client_head,
243 * Iterator over hash map entries that frees all entries
244 * associated with the given client.
246 * @param cls client to search for in source routes
247 * @param key current key code (ignored)
248 * @param value value in the hash map, a ClientQueryRecord
249 * @return GNUNET_YES (we should continue to iterate)
252 remove_client_records (void *cls, const GNUNET_HashCode * key, void *value)
254 struct ClientList *client = cls;
255 struct ClientQueryRecord *record = value;
257 if (record->client != client)
259 GNUNET_assert (GNUNET_YES ==
260 GNUNET_CONTAINER_multihashmap_remove (forward_map,
262 GNUNET_CONTAINER_heap_remove_node (record->hnode);
263 GNUNET_ARRAY_append (record->seen_replies,
264 record->seen_replies_count,
266 GNUNET_free (record);
272 * Functions with this signature are called whenever a client
273 * is disconnected on the network level.
275 * @param cls closure (NULL for dht)
276 * @param client identification of the client; NULL
277 * for the last call when the server is destroyed
280 handle_client_disconnect (void *cls,
281 struct GNUNET_SERVER_Client *client)
283 struct ClientList *pos = client_list;
284 struct ClientList *found;
285 struct PendingMessage *reply;
290 if (pos->client_handle == client)
292 GNUNET_CONTAINER_DLL_remove (client_head,
302 if (found->transmit_handle != NULL)
303 GNUNET_CONNECTION_notify_transmit_ready_cancel (found->transmit_handle);
304 while (NULL != (reply = found->pending_head))
306 GNUNET_CONTAINER_DLL_remove (found->pending_head, found->pending_tail,
310 GNUNET_CONTAINER_multihashmap_iterate (forward_list.hashmap,
311 &remove_client_records, found);
317 * Route the given request via the DHT. This includes updating
318 * the bloom filter and retransmission times, building the P2P
319 * message and initiating the routing operation.
322 transmit_request (struct ClientQueryRecord *cqr)
324 int32_t reply_bf_mutator;
326 reply_bf_mutator = (int32_t) GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK,
328 reply_bf = GNUNET_BLOCK_construct_bloomfilter (reply_bf_mutator,
330 cqr->seen_replies_count);
331 GST_NEIGHBOURS_handle_get (cqr->msg_type,
339 NULL /* no peers blocked initially */);
340 GNUNET_CONTAINER_bloomfilter_destroy (reply_bf);
342 /* exponential back-off for retries, max 1h */
343 cqr->retry_frequency =
344 GNUNET_TIME_relative_max (GNUNET_TIME_UNIT_HOURS,
345 GNUNET_TIME_relative_multiply (cqr->retry_frequency, 2));
346 cqr->retry_time = GNUNET_TIME_relative_to_absolute (cqr->retry_frequency);
351 * Task that looks at the 'retry_heap' and transmits all of the requests
352 * on the heap that are ready for transmission. Then re-schedules
353 * itself (unless the heap is empty).
356 * @param tc scheduler context
359 transmit_next_request_task (void *cls,
360 const struct GNUNET_SCHEDULER_TaskContext *tc)
362 struct ClientQueryRecord *cqr;
363 struct GNUNET_TIME_Relative delay;
365 retry_task = GNUNET_SCHEDULER_NO_TASK;
366 if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
368 while (NULL != (cqr = GNUNET_CONTAINER_heap_remove_root (retry_heap)))
371 delay = GNUNET_TIME_absolute_get_remaining (cqr->retry_time);
374 cqr->hnode = GNUNET_CONTAINER_heap_insert (retry_heap, cqr,
375 cqr->retry_time.abs_value);
376 retry_task = GNUNET_SCHEDULER_add_delayed (delay,
377 &transmit_next_request_task,
381 transmit_request (cqr);
387 * Handler for PUT messages.
389 * @param cls closure for the service
390 * @param client the client we received this message from
391 * @param message the actual message received
394 handle_dht_local_put (void *cls, struct GNUNET_SERVER_Client *client,
395 const struct GNUNET_MessageHeader *message)
397 const struct GNUNET_DHT_ClientPutMessage *dht_msg;
400 size = ntohs (message->size);
401 if (size < sizeof (struct GNUNET_DHT_ClientPutMessage))
404 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
406 dht_msg = (const struct GNUNET_DHT_ClientPutMessage *) message;
407 /* give to local clients */
408 GDS_CLIENT_handle_reply (GNUNET_TIME_absolute_ntoh (dht_msg->expiration),
412 ntohl (dht_msg->type),
413 size - sizeof (struct GNUNET_DHT_ClientPutMessage),
416 GST_DATACACHE_handle_put (GNUNET_TIME_absolute_ntoh (dht_msg->expiration),
419 ntohl (dht_msg->type),
420 size - sizeof (struct GNUNET_DHT_ClientPutMessage),
422 /* route to other peers */
423 GST_NEIGHBOURS_handle_put (ntohl (dht_msg->type),
424 ntohl (dht_msg->options),
425 ntohl (dht_msg->desired_replication_level),
426 GNUNET_TIME_absolute_ntoh (dht_msg->expiration),
429 size - sizeof (struct GNUNET_DHT_ClientPutMessage));
430 GNUNET_SERVER_receive_done (client, GNUNET_OK);
435 * Handler for any generic DHT messages, calls the appropriate handler
436 * depending on message type, sends confirmation if responses aren't otherwise
439 * @param cls closure for the service
440 * @param client the client we received this message from
441 * @param message the actual message received
444 handle_dht_local_get (void *cls, struct GNUNET_SERVER_Client *client,
445 const struct GNUNET_MessageHeader *message)
447 const struct GNUNET_DHT_ClientGetMessage *get;
448 const struct GNUNET_MessageHeader *enc_msg;
450 struct ClientQueryRecord *cqr;
455 size = ntohs (message->size);
456 if (size < sizeof (struct GNUNET_DHT_ClientGetMessage))
459 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
462 xquery_size = size - sizeof (struct GNUNET_DHT_ClientGetMessage);
463 get = (const struct GNUNET_DHT_ClientGetMessage *) message;
464 xquery = (const char*) &get[1];
467 cqr = GNUNET_malloc (sizeof (struct ClientQueryRecord) + xquery_size);
469 cqr->client = find_active_client (client);
470 cqr->xquery = (void*) &cqr[1];
471 memcpy (&cqr[1], xquery, xquery_size);
472 cqr->hnode = GNUNET_CONTAINER_heap_insert (retry_heap, cqr, 0);
473 cqr->retry_frequency = GNUNET_TIME_UNIT_MILLISECONDS;
474 cqr->retry_time = GNUNET_TIME_absolute_get ();
475 cqr->unique_id = get->unique_id;
476 cqr->xquery_size = xquery_size;
477 cqr->replication = ntohl (get->desired_replication_level);
478 cqr->msg_options = ntohl (get->options);
479 cqr->msg_type = ntohl (get->type);
480 GNUNET_CONTAINER_multihashmap_put (forward_map, KEY, cqr,
481 GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE);
482 /* start remote requests */
483 if (GNUNET_SCHEDULER_NO_TASK != retry_task)
484 GNUNET_SCHEDULER_cancel (retry_task);
485 retry_task = GNUNET_SCHEDULER_add_now (&transmit_next_request_task, NULL);
486 /* perform local lookup */
487 GDS_DATACACHE_handle_get (&get->key,
492 GNUNET_SERVER_receive_done (client, GNUNET_OK);
497 * Closure for 'remove_by_uid'.
499 struct RemoveByUidContext
502 * Client that issued the removal request.
504 struct ClientList *client;
507 * Unique ID of the request.
514 * Iterator over hash map entries that frees all entries
515 * that match the given client and UID.
517 * @param cls UID and client to search for in source routes
518 * @param key current key code
519 * @param value value in the hash map, a ClientQueryRecord
520 * @return GNUNET_YES (we should continue to iterate)
523 remove_by_uid (void *cls, const GNUNET_HashCode * key, void *value)
525 const struct RemoveByUidContext *ctx = cls;
526 struct ClientQueryRecord *record = value;
528 if (record->uid != ctx->uid)
530 return remove_client_records (ctx->client, key, record);
535 * Handler for any generic DHT stop messages, calls the appropriate handler
536 * depending on message type (if processed locally)
538 * @param cls closure for the service
539 * @param client the client we received this message from
540 * @param message the actual message received
544 handle_dht_local_get_stop (void *cls, struct GNUNET_SERVER_Client *client,
545 const struct GNUNET_MessageHeader *message)
547 const struct GNUNET_DHT_ClientGetStopMessage *dht_stop_msg =
548 (const struct GNUNET_DHT_ClientGetStopMessage *) message;
550 ctx.client = find_active_client (client);
551 ctx.uid = &dht_stop_msg.unique_id);
552 GNUNET_CONTAINER_multihashmap_get_multiple (forward_map,
556 GNUNET_SERVER_receive_done (client, GNUNET_OK);
561 * Task run to check for messages that need to be sent to a client.
563 * @param client a ClientList, containing the client and any messages to be sent to it
566 process_pending_messages (struct ClientList *client);
570 * Callback called as a result of issuing a GNUNET_SERVER_notify_transmit_ready
571 * request. A ClientList is passed as closure, take the head of the list
572 * and copy it into buf, which has the result of sending the message to the
575 * @param cls closure to this call
576 * @param size maximum number of bytes available to send
577 * @param buf where to copy the actual message to
579 * @return the number of bytes actually copied, 0 indicates failure
582 send_reply_to_client (void *cls, size_t size, void *buf)
584 struct ClientList *client = cls;
586 struct PendingMessage *reply;
590 client->transmit_handle = NULL;
593 /* client disconnected */
597 while ((NULL != (reply = client->pending_head)) &&
598 (size >= off + (msize = ntohs (reply->msg->size))))
600 GNUNET_CONTAINER_DLL_remove (client->pending_head, client->pending_tail,
602 memcpy (&cbuf[off], reply->msg, msize);
606 process_pending_messages (client);
612 * Task run to check for messages that need to be sent to a client.
614 * @param client a ClientList, containing the client and any messages to be sent to it
617 process_pending_messages (struct ClientList *client)
619 if ((client->pending_head == NULL) || (client->transmit_handle != NULL))
621 client->transmit_handle =
622 GNUNET_SERVER_notify_transmit_ready (client->client_handle,
623 ntohs (client->pending_head->
625 GNUNET_TIME_UNIT_FOREVER_REL,
626 &send_reply_to_client, client);
631 * Add a PendingMessage to the clients list of messages to be sent
633 * @param client the active client to send the message to
634 * @param pending_message the actual message to send
637 add_pending_message (struct ClientList *client,
638 struct PendingMessage *pending_message)
640 GNUNET_CONTAINER_DLL_insert_tail (client->pending_head, client->pending_tail,
642 process_pending_messages (client);
647 * Closure for 'forward_reply'
649 struct ForwardReplyContext
653 * Actual message to send to matching clients.
655 struct PendingMessage *pm;
668 * Number of bytes in data.
673 * Do we need to copy 'pm' because it was already used?
681 * Iterator over hash map entries that send a given reply to
682 * each of the matching clients. With some tricky recycling
685 * @param cls the 'struct ForwardReplyContext'
686 * @param key current key
687 * @param value value in the hash map, a ClientQueryRecord
688 * @return GNUNET_YES (we should continue to iterate),
689 * if the result is mal-formed, GNUNET_NO
692 forward_reply (void *cls, const GNUNET_HashCode * key, void *value)
694 struct ForwardReplyContext *frc = cls;
695 struct ClientQueryRecord *record = value;
696 struct PendingMessage *pm;
697 struct ReplyMessage *reply;
698 enum GNUNET_BLOCK_EvaluationResult eval;
703 if ( (record->type != GNUNET_BLOCK_TYPE_ANY) &&
704 (record->type != frc->type) )
705 return GNUNET_YES; /* type mismatch */
706 GNUNET_CRYPTO_hash (frc->data,
709 for (i=0;i<record->seen_replies_count;i++)
710 if (0 == memcmp (&record->seen_replies[i],
712 sizeof (GNUNET_HashCode)))
713 return GNUNET_YES; /* duplicate */
715 GNUNET_BLOCK_evaluate (GDS_block_context,
724 case GNUNET_BLOCK_EVALUATION_OK_LAST:
725 do_free = GNUNET_YES;
727 case GNUNET_BLOCK_EVALUATION_OK_MORE:
728 GNUNET_ARRAY_append (record->seen_replies,
729 record->seen_replies_count,
733 case GNUNET_BLOCK_EVALUATION_OK_DUPLICATE:
734 /* should be impossible to encounter here */
737 case GNUNET_BLOCK_EVALUATION_RESULT_INVALID:
740 case GNUNET_BLOCK_EVALUATION_REQUEST_VALID:
743 case GNUNET_BLOCK_EVALUATION_REQUEST_INVALID:
746 case GNUNET_BLOCK_EVALUATION_TYPE_NOT_SUPPORTED:
747 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
748 "Unsupported block type (%u) in request!\n",
752 if (GNUNET_NO == frc->do_copy)
754 /* first time, we can use the original data */
756 frc->do_copy = GNUNET_YES;
760 /* two clients waiting for same reply, must copy for queueing */
761 pm = GNUNET_malloc (sizeof (struct PendingMessage) +
762 ntohs (frc->pm->msg->size));
764 sizeof (struct PendingMessage) + ntohs (frc->pm->msg->size));
765 pm->next = pm->prev = NULL;
767 reply = (struct ReplyMessage*) &pm[1];
768 reply->unique_id = record->unique_id;
769 add_pending_message (record->client, pm);
770 if (GNUNET_YES == do_free)
771 remove_client_records (record->client, key, record);
777 * Handle a reply we've received from another peer. If the reply
778 * matches any of our pending queries, forward it to the respective
781 * @param expiration when will the reply expire
782 * @param key the query this reply is for
783 * @param get_path_length number of peers in 'get_path'
784 * @param get_path path the reply took on get
785 * @param put_path_length number of peers in 'put_path'
786 * @param put_path path the reply took on put
787 * @param type type of the reply
788 * @param data_size number of bytes in 'data'
789 * @param data application payload data
792 GDS_CLIENT_handle_reply (struct GNUNET_TIME_Absolute expiration,
793 const GNUNET_HashCode *key,
794 unsigned int get_path_length,
795 const struct GNUNET_PeerIdentity *get_path,
796 unsigned int put_path_length,
797 const struct GNUNET_PeerIdentity *put_path,
802 struct ForwardReplyContext frc;
803 struct PendingMessage *pm;
804 struct ReplyMessage *reply;
805 struct GNUNET_PeerIdentity *paths;
809 GNUNET_CONTAINER_multihashmap_get (foward_map, key))
810 return; /* no matching request, fast exit! */
811 msize = sizeof(struct ReplyMessage) + data_size +
812 (get_path_length + put_path_length) * sizeof (struct GNUNET_PeerIdentity);
813 if (msize >= GNUNET_SERVER_MAX_MESSAGE_SIZE)
815 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
816 _("Could not pass reply to client, message too big!\n"));
819 pm = (struct PendingMessage *) GNUNET_malloc (msize + sizeof (struct PendingMessage));
820 reply = (struct ReplyMessage*) &pm[1];
821 pm->msg = &reply->header;
822 reply->header.size = htons ((uint16_t) msize);
823 reply->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_CLIENT_RESULT);
824 reply->type = htonl (type);
825 reply->get_path_length = htonl (get_path_length);
826 reply->put_path_length = htonl (put_path_length);
827 reply->unique_id = 0; /* filled in later */
828 reply->expiration = GNUNET_TIME_absolute_hton (expiration);
830 paths = (struct GNUNET_PeerIdentity*) &reply[1];
831 mempcy (paths, get_path,
832 sizeof (struct GNUNET_PeerIdentity) * get_path_length);
833 mempcy (&paths[get_path_length],
834 put_path, sizeof (struct GNUNET_PeerIdentity) * put_path_length);
835 memcpy (&paths[get_path_length + put_path_length],
838 frc.do_copy = GNUNET_NO;
841 frc.data_size = data_size;
843 GNUNET_CONTAINER_multihashmap_get_multiple (foward_map, key,
846 if (GNUNET_NO == frc.do_copy)
848 /* did not match any of the requests, free! */
855 * Initialize client subsystem.
857 * @param server the initialized server
860 GDS_CLIENT_init (struct GNUNET_SERVER_Handle *server)
862 static struct GNUNET_SERVER_MessageHandler plugin_handlers[] = {
863 {&handle_dht_local_put, NULL,
864 GNUNET_MESSAGE_TYPE_DHT_CLIENT_PUT, 0},
865 {&handle_dht_local_get, NULL,
866 GNUNET_MESSAGE_TYPE_DHT_CLIENT_GET, 0},
867 {&handle_dht_local_get_stop, NULL,
868 GNUNET_MESSAGE_TYPE_DHT_CLIENT_GET_STOP,
869 sizeof (struct GNUNET_DHT_StopMessage) },
872 forward_map = GNUNET_CONTAINER_multihashmap_create (1024);
873 retry_heap = GNUNET_CONTAINER_heap_create (GNUNET_CONTAINER_HEAP_ORDER_MIN);
874 GNUNET_SERVER_add_handlers (server, plugin_handlers);
875 GNUNET_SERVER_disconnect_notify (server, &handle_client_disconnect, NULL);
880 * Shutdown client subsystem.
885 GNUNET_assert (client_head == NULL);
886 GNUNET_assert (client_tail == NULL);
887 if (GNUNET_SCHEDULER_NO_TASK != retry_task)
889 GNUNET_SCHEDULER_cancel (retry_task);
890 retry_task = GNUNET_SCHEDULER_NO_TASK;
892 GNUNET_assert (0 == GNUNET_CONTAINER_heap_get_size (retry_heap));
893 GNUNET_CONTAINER_heap_destroy (retry_heap);
895 GNUNET_assert (0 == GNUNET_CONTAINER_multihashmap_size (forward_map));
896 GNUNET_CONTAINER_multihashmap_destroy (forward_map);
900 /* end of gnunet-service-dht_clients.c */