2 This file is part of GNUnet.
3 (C) 2009, 2010, 2011 Christian Grothoff (and other contributing authors)
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6 it under the terms of the GNU General Public License as published
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13 General Public License for more details.
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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_neighbours.h"
46 * Linked list of messages to send to clients.
51 * Pointer to next item in the list
53 struct PendingMessage *next;
56 * Pointer to previous item in the list
58 struct PendingMessage *prev;
61 * Actual message to be sent, allocated at the end of the struct:
62 * // msg = (cast) &pm[1];
63 * // memcpy (&pm[1], data, len);
65 const struct GNUNET_MessageHeader *msg;
71 * Struct containing information about a client,
72 * handle to connect to it, and any pending messages
73 * that need to be sent to it.
78 * Linked list of active clients
80 struct ClientList *next;
83 * Linked list of active clients
85 struct ClientList *prev;
88 * The handle to this client
90 struct GNUNET_SERVER_Client *client_handle;
93 * Handle to the current transmission request, NULL
96 struct GNUNET_CONNECTION_TransmitHandle *transmit_handle;
99 * Linked list of pending messages for this client
101 struct PendingMessage *pending_head;
104 * Tail of linked list of pending messages for this client
106 struct PendingMessage *pending_tail;
112 * Entry in the DHT routing table for a client's GET request.
114 struct ClientQueryRecord
118 * The key this request was about
123 * Client responsible for the request.
125 struct ClientList *client;
128 * Extended query (see gnunet_block_lib.h), allocated at the end of this struct.
133 * Replies we have already seen for this request.
135 GNUNET_HashCode *seen_replies;
138 * Pointer to this nodes heap location in the retry-heap (for fast removal)
140 struct GNUNET_CONTAINER_HeapNode *hnode;
143 * What's the delay between re-try operations that we currently use for this
146 struct GNUNET_TIME_Relative retry_frequency;
149 * What's the next time we should re-try this request?
151 struct GNUNET_TIME_Absolute retry_time;
154 * The unique identifier of this request
159 * Number of bytes in xquery.
164 * Number of entries in 'seen_replies'.
166 unsigned int seen_replies_count;
169 * Desired replication level
171 uint32_t replication;
174 * Any message options for this request
176 uint32_t msg_options;
179 * The type for the data for the GET request; actually an 'enum
180 * GNUNET_BLOCK_Type'.
188 * List of active clients.
190 static struct ClientList *client_head;
193 * List of active clients.
195 static struct ClientList *client_tail;
198 * Hashmap for fast key based lookup, maps keys to 'struct ClientQueryRecord' entries.
200 static struct GNUNET_CONTAINER_MultiHashMap *forward_map;
203 * Heap with all of our client's request, sorted by retry time (earliest on top).
205 static struct GNUNET_CONTAINER_Heap *retry_heap;
208 * Task that re-transmits requests (using retry_heap).
210 static GNUNET_SCHEDULER_TaskIdentifier retry_task;
214 * Find a client if it exists, add it otherwise.
216 * @param client the server handle to the client
218 * @return the client if found, a new client otherwise
220 static struct ClientList *
221 find_active_client (struct GNUNET_SERVER_Client *client)
223 struct ClientList *pos = client_list;
224 struct ClientList *ret;
228 if (pos->client_handle == client)
232 ret = GNUNET_malloc (sizeof (struct ClientList));
233 ret->client_handle = client;
234 GNUNET_CONTAINER_DLL_insert (client_head,
242 * Iterator over hash map entries that frees all entries
243 * associated with the given client.
245 * @param cls client to search for in source routes
246 * @param key current key code (ignored)
247 * @param value value in the hash map, a ClientQueryRecord
248 * @return GNUNET_YES (we should continue to iterate)
251 remove_client_records (void *cls, const GNUNET_HashCode * key, void *value)
253 struct ClientList *client = cls;
254 struct ClientQueryRecord *record = value;
256 if (record->client != client)
258 GNUNET_assert (GNUNET_YES ==
259 GNUNET_CONTAINER_multihashmap_remove (forward_map,
261 GNUNET_CONTAINER_heap_remove_node (record->hnode);
262 GNUNET_ARRAY_append (record->seen_replies,
263 record->seen_replies_count,
265 GNUNET_free (record);
271 * Functions with this signature are called whenever a client
272 * is disconnected on the network level.
274 * @param cls closure (NULL for dht)
275 * @param client identification of the client; NULL
276 * for the last call when the server is destroyed
279 handle_client_disconnect (void *cls,
280 struct GNUNET_SERVER_Client *client)
282 struct ClientList *pos = client_list;
283 struct ClientList *found;
284 struct PendingMessage *reply;
289 if (pos->client_handle == client)
291 GNUNET_CONTAINER_DLL_remove (client_head,
301 if (found->transmit_handle != NULL)
302 GNUNET_CONNECTION_notify_transmit_ready_cancel (found->transmit_handle);
303 while (NULL != (reply = found->pending_head))
305 GNUNET_CONTAINER_DLL_remove (found->pending_head, found->pending_tail,
309 GNUNET_CONTAINER_multihashmap_iterate (forward_list.hashmap,
310 &remove_client_records, found);
316 * Route the given request via the DHT. This includes updating
317 * the bloom filter and retransmission times, building the P2P
318 * message and initiating the routing operation.
321 transmit_request (struct ClientQueryRecord *cqr)
323 int32_t reply_bf_mutator;
325 reply_bf_mutator = (int32_t) GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK,
327 reply_bf = GNUNET_BLOCK_construct_bloomfilter (reply_bf_mutator,
329 cqr->seen_replies_count);
330 GST_NEIGHBOURS_handle_get (cqr->msg_type,
338 NULL /* no peers blocked initially */);
339 GNUNET_CONTAINER_bloomfilter_destroy (reply_bf);
341 /* exponential back-off for retries, max 1h */
342 cqr->retry_frequency =
343 GNUNET_TIME_relative_max (GNUNET_TIME_UNIT_HOURS,
344 GNUNET_TIME_relative_multiply (cqr->retry_frequency, 2));
345 cqr->retry_time = GNUNET_TIME_relative_to_absolute (cqr->retry_frequency);
350 * Task that looks at the 'retry_heap' and transmits all of the requests
351 * on the heap that are ready for transmission. Then re-schedules
352 * itself (unless the heap is empty).
355 * @param tc scheduler context
358 transmit_next_request_task (void *cls,
359 const struct GNUNET_SCHEDULER_TaskContext *tc)
361 struct ClientQueryRecord *cqr;
362 struct GNUNET_TIME_Relative delay;
364 retry_task = GNUNET_SCHEDULER_NO_TASK;
365 if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
367 while (NULL != (cqr = GNUNET_CONTAINER_heap_remove_root (retry_heap)))
370 delay = GNUNET_TIME_absolute_get_remaining (cqr->retry_time);
373 cqr->hnode = GNUNET_CONTAINER_heap_insert (retry_heap, cqr,
374 cqr->retry_time.abs_value);
375 retry_task = GNUNET_SCHEDULER_add_delayed (delay,
376 &transmit_next_request_task,
380 transmit_request (cqr);
386 * Handler for PUT messages.
388 * @param cls closure for the service
389 * @param client the client we received this message from
390 * @param message the actual message received
393 handle_dht_local_put (void *cls, struct GNUNET_SERVER_Client *client,
394 const struct GNUNET_MessageHeader *message)
396 const struct GNUNET_DHT_ClientPutMessage *dht_msg;
399 size = ntohs (message->size);
400 if (size < sizeof (struct GNUNET_DHT_ClientPutMessage))
403 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
405 dht_msg = (const struct GNUNET_DHT_ClientPutMessage *) message;
406 GST_NEIGHBOURS_handle_put (ntohl (dht_msg->type),
407 ntohl (dht_msg->options),
408 ntohl (dht_msg->desired_replication_level),
409 GNUNET_TIME_absolute_ntoh (dht_msg->expiration),
412 size - sizeof (struct GNUNET_DHT_ClientPutMessage));
413 GNUNET_SERVER_receive_done (client, GNUNET_OK);
418 * Handler for any generic DHT messages, calls the appropriate handler
419 * depending on message type, sends confirmation if responses aren't otherwise
422 * @param cls closure for the service
423 * @param client the client we received this message from
424 * @param message the actual message received
427 handle_dht_local_get (void *cls, struct GNUNET_SERVER_Client *client,
428 const struct GNUNET_MessageHeader *message)
430 const struct GNUNET_DHT_ClientGetMessage *get;
431 const struct GNUNET_MessageHeader *enc_msg;
433 struct ClientQueryRecord *cqr;
438 size = ntohs (message->size);
439 if (size < sizeof (struct GNUNET_DHT_ClientGetMessage))
442 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
445 xquery_size = size - sizeof (struct GNUNET_DHT_ClientGetMessage);
446 get = (const struct GNUNET_DHT_ClientGetMessage *) message;
447 xquery = (const char*) &get[1];
449 cqr = GNUNET_malloc (sizeof (struct ClientQueryRecord) + xquery_size);
451 cqr->client = find_active_client (client);
452 cqr->xquery = (void*) &cqr[1];
453 memcpy (&cqr[1], xquery, xquery_size);
454 cqr->hnode = GNUNET_CONTAINER_heap_insert (retry_heap, cqr, 0);
455 cqr->retry_frequency = GNUNET_TIME_UNIT_MILLISECONDS;
456 cqr->retry_time = GNUNET_TIME_absolute_get ();
457 cqr->unique_id = get->unique_id;
458 cqr->xquery_size = xquery_size;
459 cqr->replication = ntohl (get->desired_replication_level);
460 cqr->msg_options = ntohl (get->options);
461 cqr->msg_type = ntohl (get->type);
462 GNUNET_CONTAINER_multihashmap_put (forward_map, KEY, cqr,
463 GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE);
464 if (GNUNET_SCHEDULER_NO_TASK != retry_task)
465 GNUNET_SCHEDULER_cancel (retry_task);
466 retry_task = GNUNET_SCHEDULER_add_now (&transmit_next_request_task, NULL);
467 GNUNET_SERVER_receive_done (client, GNUNET_OK);
472 * Closure for 'remove_by_uid'.
474 struct RemoveByUidContext
477 * Client that issued the removal request.
479 struct ClientList *client;
482 * Unique ID of the request.
489 * Iterator over hash map entries that frees all entries
490 * that match the given client and UID.
492 * @param cls UID and client to search for in source routes
493 * @param key current key code
494 * @param value value in the hash map, a ClientQueryRecord
495 * @return GNUNET_YES (we should continue to iterate)
498 remove_by_uid (void *cls, const GNUNET_HashCode * key, void *value)
500 const struct RemoveByUidContext *ctx = cls;
501 struct ClientQueryRecord *record = value;
503 if (record->uid != ctx->uid)
505 return remove_client_records (ctx->client, key, record);
510 * Handler for any generic DHT stop messages, calls the appropriate handler
511 * depending on message type (if processed locally)
513 * @param cls closure for the service
514 * @param client the client we received this message from
515 * @param message the actual message received
519 handle_dht_local_get_stop (void *cls, struct GNUNET_SERVER_Client *client,
520 const struct GNUNET_MessageHeader *message)
522 const struct GNUNET_DHT_ClientGetStopMessage *dht_stop_msg =
523 (const struct GNUNET_DHT_ClientGetStopMessage *) message;
525 ctx.client = find_active_client (client);
526 ctx.uid = &dht_stop_msg.unique_id);
527 GNUNET_CONTAINER_multihashmap_get_multiple (forward_map,
531 GNUNET_SERVER_receive_done (client, GNUNET_OK);
536 * Task run to check for messages that need to be sent to a client.
538 * @param client a ClientList, containing the client and any messages to be sent to it
541 process_pending_messages (struct ClientList *client);
545 * Callback called as a result of issuing a GNUNET_SERVER_notify_transmit_ready
546 * request. A ClientList is passed as closure, take the head of the list
547 * and copy it into buf, which has the result of sending the message to the
550 * @param cls closure to this call
551 * @param size maximum number of bytes available to send
552 * @param buf where to copy the actual message to
554 * @return the number of bytes actually copied, 0 indicates failure
557 send_reply_to_client (void *cls, size_t size, void *buf)
559 struct ClientList *client = cls;
561 struct PendingMessage *reply;
565 client->transmit_handle = NULL;
568 /* client disconnected */
572 while ((NULL != (reply = client->pending_head)) &&
573 (size >= off + (msize = ntohs (reply->msg->size))))
575 GNUNET_CONTAINER_DLL_remove (client->pending_head, client->pending_tail,
577 memcpy (&cbuf[off], reply->msg, msize);
581 process_pending_messages (client);
587 * Task run to check for messages that need to be sent to a client.
589 * @param client a ClientList, containing the client and any messages to be sent to it
592 process_pending_messages (struct ClientList *client)
594 if ((client->pending_head == NULL) || (client->transmit_handle != NULL))
596 client->transmit_handle =
597 GNUNET_SERVER_notify_transmit_ready (client->client_handle,
598 ntohs (client->pending_head->
600 GNUNET_TIME_UNIT_FOREVER_REL,
601 &send_reply_to_client, client);
606 * Add a PendingMessage to the clients list of messages to be sent
608 * @param client the active client to send the message to
609 * @param pending_message the actual message to send
612 add_pending_message (struct ClientList *client,
613 struct PendingMessage *pending_message)
615 GNUNET_CONTAINER_DLL_insert_tail (client->pending_head, client->pending_tail,
617 process_pending_messages (client);
622 * Closure for 'forward_reply'
624 struct ForwardReplyContext
628 * Actual message to send to matching clients.
630 struct PendingMessage *pm;
643 * Number of bytes in data.
648 * Do we need to copy 'pm' because it was already used?
656 * Iterator over hash map entries that send a given reply to
657 * each of the matching clients. With some tricky recycling
660 * @param cls the 'struct ForwardReplyContext'
661 * @param key current key
662 * @param value value in the hash map, a ClientQueryRecord
663 * @return GNUNET_YES (we should continue to iterate),
664 * if the result is mal-formed, GNUNET_NO
667 forward_reply (void *cls, const GNUNET_HashCode * key, void *value)
669 struct ForwardReplyContext *frc = cls;
670 struct ClientQueryRecord *record = value;
671 struct PendingMessage *pm;
672 struct ReplyMessage *reply;
673 enum GNUNET_BLOCK_EvaluationResult eval;
678 if ( (record->type != GNUNET_BLOCK_TYPE_ANY) &&
679 (record->type != frc->type) )
680 return GNUNET_YES; /* type mismatch */
681 GNUNET_CRYPTO_hash (frc->data,
684 for (i=0;i<record->seen_replies_count;i++)
685 if (0 == memcmp (&record->seen_replies[i],
687 sizeof (GNUNET_HashCode)))
688 return GNUNET_YES; /* duplicate */
690 GNUNET_BLOCK_evaluate (GDS_block_context,
699 case GNUNET_BLOCK_EVALUATION_OK_LAST:
700 do_free = GNUNET_YES;
702 case GNUNET_BLOCK_EVALUATION_OK_MORE:
703 GNUNET_ARRAY_append (record->seen_replies,
704 record->seen_replies_count,
708 case GNUNET_BLOCK_EVALUATION_OK_DUPLICATE:
709 /* should be impossible to encounter here */
712 case GNUNET_BLOCK_EVALUATION_RESULT_INVALID:
715 case GNUNET_BLOCK_EVALUATION_REQUEST_VALID:
718 case GNUNET_BLOCK_EVALUATION_REQUEST_INVALID:
721 case GNUNET_BLOCK_EVALUATION_TYPE_NOT_SUPPORTED:
722 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
723 "Unsupported block type (%u) in request!\n",
727 if (GNUNET_NO == frc->do_copy)
729 /* first time, we can use the original data */
731 frc->do_copy = GNUNET_YES;
735 /* two clients waiting for same reply, must copy for queueing */
736 pm = GNUNET_malloc (sizeof (struct PendingMessage) +
737 ntohs (frc->pm->msg->size));
739 sizeof (struct PendingMessage) + ntohs (frc->pm->msg->size));
740 pm->next = pm->prev = NULL;
742 reply = (struct ReplyMessage*) &pm[1];
743 reply->unique_id = record->unique_id;
744 add_pending_message (record->client, pm);
745 if (GNUNET_YES == do_free)
746 remove_client_records (record->client, key, record);
752 * Handle a reply we've received from another peer. If the reply
753 * matches any of our pending queries, forward it to the respective
756 * @param expiration when will the reply expire
757 * @param key the query this reply is for
758 * @param get_path_length number of peers in 'get_path'
759 * @param get_path path the reply took on get
760 * @param put_path_length number of peers in 'put_path'
761 * @param put_path path the reply took on put
762 * @param type type of the reply
763 * @param data_size number of bytes in 'data'
764 * @param data application payload data
767 GDS_CLIENT_handle_reply (struct GNUNET_TIME_Absolute expiration,
768 const GNUNET_HashCode *key,
769 unsigned int get_path_length,
770 const struct GNUNET_PeerIdentity *get_path,
771 unsigned int put_path_length,
772 const struct GNUNET_PeerIdentity *put_path,
777 struct ForwardReplyContext frc;
778 struct PendingMessage *pm;
779 struct ReplyMessage *reply;
780 struct GNUNET_PeerIdentity *paths;
784 GNUNET_CONTAINER_multihashmap_get (foward_map, key))
785 return; /* no matching request, fast exit! */
786 msize = sizeof(struct ReplyMessage) + data_size +
787 (get_path_length + put_path_length) * sizeof (struct GNUNET_PeerIdentity);
788 if (msize >= GNUNET_SERVER_MAX_MESSAGE_SIZE)
790 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
791 _("Could not pass reply to client, message too big!\n"));
794 pm = (struct PendingMessage *) GNUNET_malloc (msize + sizeof (struct PendingMessage));
795 reply = (struct ReplyMessage*) &pm[1];
796 pm->msg = &reply->header;
797 reply->header.size = htons ((uint16_t) msize);
798 reply->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_CLIENT_RESULT);
799 reply->type = htonl (type);
800 reply->get_path_length = htonl (get_path_length);
801 reply->put_path_length = htonl (put_path_length);
802 reply->unique_id = 0; /* filled in later */
803 reply->expiration = GNUNET_TIME_absolute_hton (expiration);
805 paths = (struct GNUNET_PeerIdentity*) &reply[1];
806 mempcy (paths, get_path,
807 sizeof (struct GNUNET_PeerIdentity) * get_path_length);
808 mempcy (&paths[get_path_length],
809 put_path, sizeof (struct GNUNET_PeerIdentity) * put_path_length);
810 memcpy (&paths[get_path_length + put_path_length],
813 frc.do_copy = GNUNET_NO;
816 frc.data_size = data_size;
818 GNUNET_CONTAINER_multihashmap_get_multiple (foward_map, key,
821 if (GNUNET_NO == frc.do_copy)
823 /* did not match any of the requests, free! */
830 * Initialize client subsystem.
832 * @param server the initialized server
835 GDS_CLIENT_init (struct GNUNET_SERVER_Handle *server)
837 static struct GNUNET_SERVER_MessageHandler plugin_handlers[] = {
838 {&handle_dht_local_put, NULL,
839 GNUNET_MESSAGE_TYPE_DHT_CLIENT_PUT, 0},
840 {&handle_dht_local_get, NULL,
841 GNUNET_MESSAGE_TYPE_DHT_CLIENT_GET, 0},
842 {&handle_dht_local_get_stop, NULL,
843 GNUNET_MESSAGE_TYPE_DHT_CLIENT_GET_STOP,
844 sizeof (struct GNUNET_DHT_StopMessage) },
847 forward_map = GNUNET_CONTAINER_multihashmap_create (1024);
848 retry_heap = GNUNET_CONTAINER_heap_create (GNUNET_CONTAINER_HEAP_ORDER_MIN);
849 GNUNET_SERVER_add_handlers (server, plugin_handlers);
850 GNUNET_SERVER_disconnect_notify (server, &handle_client_disconnect, NULL);
855 * Shutdown client subsystem.
860 GNUNET_assert (client_head == NULL);
861 GNUNET_assert (client_tail == NULL);
862 if (GNUNET_SCHEDULER_NO_TASK != retry_task)
864 GNUNET_SCHEDULER_cancel (retry_task);
865 retry_task = GNUNET_SCHEDULER_NO_TASK;
867 GNUNET_assert (0 == GNUNET_CONTAINER_heap_get_size (retry_heap));
868 GNUNET_CONTAINER_heap_destroy (retry_heap);
870 GNUNET_assert (0 == GNUNET_CONTAINER_multihashmap_size (forward_map));
871 GNUNET_CONTAINER_multihashmap_destroy (forward_map);
875 /* end of gnunet-service-dht_clients.c */