2 This file is part of GNUnet.
3 (C) 2009, 2010, 2011 Christian Grothoff (and other contributing authors)
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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_protocols.h"
30 #include "gnunet_statistics_service.h"
31 #include "gnunet-service-dht.h"
32 #include "gnunet-service-dht_clients.h"
33 #include "gnunet-service-dht_datacache.h"
34 #include "gnunet-service-dht_neighbours.h"
39 * Linked list of messages to send to clients.
44 * Pointer to next item in the list
46 struct PendingMessage *next;
49 * Pointer to previous item in the list
51 struct PendingMessage *prev;
54 * Actual message to be sent, allocated at the end of the struct:
55 * // msg = (cast) &pm[1];
56 * // memcpy (&pm[1], data, len);
58 const struct GNUNET_MessageHeader *msg;
64 * Struct containing information about a client,
65 * handle to connect to it, and any pending messages
66 * that need to be sent to it.
71 * Linked list of active clients
73 struct ClientList *next;
76 * Linked list of active clients
78 struct ClientList *prev;
81 * The handle to this client
83 struct GNUNET_SERVER_Client *client_handle;
86 * Handle to the current transmission request, NULL
89 struct GNUNET_CONNECTION_TransmitHandle *transmit_handle;
92 * Linked list of pending messages for this client
94 struct PendingMessage *pending_head;
97 * Tail of linked list of pending messages for this client
99 struct PendingMessage *pending_tail;
105 * Entry in the DHT routing table for a client's GET request.
107 struct ClientQueryRecord
111 * The key this request was about
116 * Client responsible for the request.
118 struct ClientList *client;
121 * Extended query (see gnunet_block_lib.h), allocated at the end of this struct.
126 * Replies we have already seen for this request.
128 GNUNET_HashCode *seen_replies;
131 * Pointer to this nodes heap location in the retry-heap (for fast removal)
133 struct GNUNET_CONTAINER_HeapNode *hnode;
136 * What's the delay between re-try operations that we currently use for this
139 struct GNUNET_TIME_Relative retry_frequency;
142 * What's the next time we should re-try this request?
144 struct GNUNET_TIME_Absolute retry_time;
147 * The unique identifier of this request
152 * Number of bytes in xquery.
157 * Number of entries in 'seen_replies'.
159 unsigned int seen_replies_count;
162 * Desired replication level
164 uint32_t replication;
167 * Any message options for this request
169 uint32_t msg_options;
172 * The type for the data for the GET request.
174 enum GNUNET_BLOCK_Type type;
180 * List of active clients.
182 static struct ClientList *client_head;
185 * List of active clients.
187 static struct ClientList *client_tail;
190 * Hashmap for fast key based lookup, maps keys to 'struct ClientQueryRecord' entries.
192 static struct GNUNET_CONTAINER_MultiHashMap *forward_map;
195 * Heap with all of our client's request, sorted by retry time (earliest on top).
197 static struct GNUNET_CONTAINER_Heap *retry_heap;
200 * Task that re-transmits requests (using retry_heap).
202 static GNUNET_SCHEDULER_TaskIdentifier retry_task;
206 * Find a client if it exists, add it otherwise.
208 * @param client the server handle to the client
210 * @return the client if found, a new client otherwise
212 static struct ClientList *
213 find_active_client (struct GNUNET_SERVER_Client *client)
215 struct ClientList *pos = client_head;
216 struct ClientList *ret;
220 if (pos->client_handle == client)
224 ret = GNUNET_malloc (sizeof (struct ClientList));
225 ret->client_handle = client;
226 GNUNET_CONTAINER_DLL_insert (client_head,
234 * Iterator over hash map entries that frees all entries
235 * associated with the given client.
237 * @param cls client to search for in source routes
238 * @param key current key code (ignored)
239 * @param value value in the hash map, a ClientQueryRecord
240 * @return GNUNET_YES (we should continue to iterate)
243 remove_client_records (void *cls, const GNUNET_HashCode * key, void *value)
245 struct ClientList *client = cls;
246 struct ClientQueryRecord *record = value;
248 if (record->client != client)
250 GNUNET_assert (GNUNET_YES ==
251 GNUNET_CONTAINER_multihashmap_remove (forward_map,
253 GNUNET_CONTAINER_heap_remove_node (record->hnode);
254 GNUNET_array_append (record->seen_replies,
255 record->seen_replies_count,
257 GNUNET_free (record);
263 * Functions with this signature are called whenever a client
264 * is disconnected on the network level.
266 * @param cls closure (NULL for dht)
267 * @param client identification of the client; NULL
268 * for the last call when the server is destroyed
271 handle_client_disconnect (void *cls,
272 struct GNUNET_SERVER_Client *client)
274 struct ClientList *pos;
275 struct PendingMessage *reply;
277 pos = find_active_client (client);
278 GNUNET_CONTAINER_DLL_remove (client_head,
281 if (pos->transmit_handle != NULL)
282 GNUNET_CONNECTION_notify_transmit_ready_cancel (pos->transmit_handle);
283 while (NULL != (reply = pos->pending_head))
285 GNUNET_CONTAINER_DLL_remove (pos->pending_head, pos->pending_tail,
289 GNUNET_CONTAINER_multihashmap_iterate (forward_map,
290 &remove_client_records, pos);
296 * Route the given request via the DHT. This includes updating
297 * the bloom filter and retransmission times, building the P2P
298 * message and initiating the routing operation.
301 transmit_request (struct ClientQueryRecord *cqr)
303 int32_t reply_bf_mutator;
304 struct GNUNET_CONTAINER_BloomFilter *reply_bf;
306 reply_bf_mutator = (int32_t) GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK,
308 reply_bf = GNUNET_BLOCK_construct_bloomfilter (reply_bf_mutator,
310 cqr->seen_replies_count);
311 GDS_NEIGHBOURS_handle_get (cqr->type,
320 NULL /* no peers blocked initially */);
321 GNUNET_CONTAINER_bloomfilter_free (reply_bf);
323 /* exponential back-off for retries, max 1h */
324 cqr->retry_frequency =
325 GNUNET_TIME_relative_max (GNUNET_TIME_UNIT_HOURS,
326 GNUNET_TIME_relative_multiply (cqr->retry_frequency, 2));
327 cqr->retry_time = GNUNET_TIME_relative_to_absolute (cqr->retry_frequency);
332 * Task that looks at the 'retry_heap' and transmits all of the requests
333 * on the heap that are ready for transmission. Then re-schedules
334 * itself (unless the heap is empty).
337 * @param tc scheduler context
340 transmit_next_request_task (void *cls,
341 const struct GNUNET_SCHEDULER_TaskContext *tc)
343 struct ClientQueryRecord *cqr;
344 struct GNUNET_TIME_Relative delay;
346 retry_task = GNUNET_SCHEDULER_NO_TASK;
347 if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
349 while (NULL != (cqr = GNUNET_CONTAINER_heap_remove_root (retry_heap)))
352 delay = GNUNET_TIME_absolute_get_remaining (cqr->retry_time);
353 if (delay.rel_value > 0)
355 cqr->hnode = GNUNET_CONTAINER_heap_insert (retry_heap, cqr,
356 cqr->retry_time.abs_value);
357 retry_task = GNUNET_SCHEDULER_add_delayed (delay,
358 &transmit_next_request_task,
362 transmit_request (cqr);
368 * Handler for PUT messages.
370 * @param cls closure for the service
371 * @param client the client we received this message from
372 * @param message the actual message received
375 handle_dht_local_put (void *cls, struct GNUNET_SERVER_Client *client,
376 const struct GNUNET_MessageHeader *message)
378 const struct GNUNET_DHT_ClientPutMessage *dht_msg;
381 size = ntohs (message->size);
382 if (size < sizeof (struct GNUNET_DHT_ClientPutMessage))
385 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
387 dht_msg = (const struct GNUNET_DHT_ClientPutMessage *) message;
388 /* give to local clients */
389 GDS_CLIENT_handle_reply (GNUNET_TIME_absolute_ntoh (dht_msg->expiration),
393 ntohl (dht_msg->type),
394 size - sizeof (struct GNUNET_DHT_ClientPutMessage),
397 GDS_DATACACHE_handle_put (GNUNET_TIME_absolute_ntoh (dht_msg->expiration),
400 ntohl (dht_msg->type),
401 size - sizeof (struct GNUNET_DHT_ClientPutMessage),
403 /* route to other peers */
404 GDS_NEIGHBOURS_handle_put (ntohl (dht_msg->type),
405 ntohl (dht_msg->options),
406 ntohl (dht_msg->desired_replication_level),
407 GNUNET_TIME_absolute_ntoh (dht_msg->expiration),
409 NULL /* peer bloom filter */,
413 size - sizeof (struct GNUNET_DHT_ClientPutMessage));
414 GNUNET_SERVER_receive_done (client, GNUNET_OK);
419 * Handler for any generic DHT messages, calls the appropriate handler
420 * depending on message type, sends confirmation if responses aren't otherwise
423 * @param cls closure for the service
424 * @param client the client we received this message from
425 * @param message the actual message received
428 handle_dht_local_get (void *cls, struct GNUNET_SERVER_Client *client,
429 const struct GNUNET_MessageHeader *message)
431 const struct GNUNET_DHT_ClientGetMessage *get;
432 struct ClientQueryRecord *cqr;
437 size = ntohs (message->size);
438 if (size < sizeof (struct GNUNET_DHT_ClientGetMessage))
441 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
444 xquery_size = size - sizeof (struct GNUNET_DHT_ClientGetMessage);
445 get = (const struct GNUNET_DHT_ClientGetMessage *) message;
446 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->type = ntohl (get->type);
462 GNUNET_CONTAINER_multihashmap_put (forward_map, &get->key, cqr,
463 GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE);
464 /* start remote requests */
465 if (GNUNET_SCHEDULER_NO_TASK != retry_task)
466 GNUNET_SCHEDULER_cancel (retry_task);
467 retry_task = GNUNET_SCHEDULER_add_now (&transmit_next_request_task, NULL);
468 /* perform local lookup */
469 GDS_DATACACHE_handle_get (&get->key,
474 GNUNET_SERVER_receive_done (client, GNUNET_OK);
479 * Closure for 'remove_by_unique_id'.
481 struct RemoveByUniqueIdContext
484 * Client that issued the removal request.
486 struct ClientList *client;
489 * Unique ID of the request.
496 * Iterator over hash map entries that frees all entries
497 * that match the given client and unique ID.
499 * @param cls unique ID and client to search for in source routes
500 * @param key current key code
501 * @param value value in the hash map, a ClientQueryRecord
502 * @return GNUNET_YES (we should continue to iterate)
505 remove_by_unique_id (void *cls, const GNUNET_HashCode * key, void *value)
507 const struct RemoveByUniqueIdContext *ctx = cls;
508 struct ClientQueryRecord *record = value;
510 if (record->unique_id != ctx->unique_id)
512 return remove_client_records (ctx->client, key, record);
517 * Handler for any generic DHT stop messages, calls the appropriate handler
518 * depending on message type (if processed locally)
520 * @param cls closure for the service
521 * @param client the client we received this message from
522 * @param message the actual message received
526 handle_dht_local_get_stop (void *cls, struct GNUNET_SERVER_Client *client,
527 const struct GNUNET_MessageHeader *message)
529 const struct GNUNET_DHT_ClientGetStopMessage *dht_stop_msg =
530 (const struct GNUNET_DHT_ClientGetStopMessage *) message;
531 struct RemoveByUniqueIdContext ctx;
533 ctx.client = find_active_client (client);
534 ctx.unique_id = dht_stop_msg->unique_id;
535 GNUNET_CONTAINER_multihashmap_get_multiple (forward_map,
537 &remove_by_unique_id,
539 GNUNET_SERVER_receive_done (client, GNUNET_OK);
544 * Task run to check for messages that need to be sent to a client.
546 * @param client a ClientList, containing the client and any messages to be sent to it
549 process_pending_messages (struct ClientList *client);
553 * Callback called as a result of issuing a GNUNET_SERVER_notify_transmit_ready
554 * request. A ClientList is passed as closure, take the head of the list
555 * and copy it into buf, which has the result of sending the message to the
558 * @param cls closure to this call
559 * @param size maximum number of bytes available to send
560 * @param buf where to copy the actual message to
562 * @return the number of bytes actually copied, 0 indicates failure
565 send_reply_to_client (void *cls, size_t size, void *buf)
567 struct ClientList *client = cls;
569 struct PendingMessage *reply;
573 client->transmit_handle = NULL;
576 /* client disconnected */
580 while ((NULL != (reply = client->pending_head)) &&
581 (size >= off + (msize = ntohs (reply->msg->size))))
583 GNUNET_CONTAINER_DLL_remove (client->pending_head, client->pending_tail,
585 memcpy (&cbuf[off], reply->msg, msize);
589 process_pending_messages (client);
595 * Task run to check for messages that need to be sent to a client.
597 * @param client a ClientList, containing the client and any messages to be sent to it
600 process_pending_messages (struct ClientList *client)
602 if ((client->pending_head == NULL) || (client->transmit_handle != NULL))
604 client->transmit_handle =
605 GNUNET_SERVER_notify_transmit_ready (client->client_handle,
606 ntohs (client->pending_head->
608 GNUNET_TIME_UNIT_FOREVER_REL,
609 &send_reply_to_client, client);
614 * Add a PendingMessage to the clients list of messages to be sent
616 * @param client the active client to send the message to
617 * @param pending_message the actual message to send
620 add_pending_message (struct ClientList *client,
621 struct PendingMessage *pending_message)
623 GNUNET_CONTAINER_DLL_insert_tail (client->pending_head, client->pending_tail,
625 process_pending_messages (client);
630 * Closure for 'forward_reply'
632 struct ForwardReplyContext
636 * Actual message to send to matching clients.
638 struct PendingMessage *pm;
648 enum GNUNET_BLOCK_Type type;
651 * Number of bytes in data.
656 * Do we need to copy 'pm' because it was already used?
664 * Iterator over hash map entries that send a given reply to
665 * each of the matching clients. With some tricky recycling
668 * @param cls the 'struct ForwardReplyContext'
669 * @param key current key
670 * @param value value in the hash map, a ClientQueryRecord
671 * @return GNUNET_YES (we should continue to iterate),
672 * if the result is mal-formed, GNUNET_NO
675 forward_reply (void *cls, const GNUNET_HashCode * key, void *value)
677 struct ForwardReplyContext *frc = cls;
678 struct ClientQueryRecord *record = value;
679 struct PendingMessage *pm;
680 struct GNUNET_DHT_ClientResultMessage *reply;
681 enum GNUNET_BLOCK_EvaluationResult eval;
686 if ( (record->type != GNUNET_BLOCK_TYPE_ANY) &&
687 (record->type != frc->type) )
688 return GNUNET_YES; /* type mismatch */
689 GNUNET_CRYPTO_hash (frc->data,
692 for (i=0;i<record->seen_replies_count;i++)
693 if (0 == memcmp (&record->seen_replies[i],
695 sizeof (GNUNET_HashCode)))
696 return GNUNET_YES; /* duplicate */
698 GNUNET_BLOCK_evaluate (GDS_block_context,
707 case GNUNET_BLOCK_EVALUATION_OK_LAST:
708 do_free = GNUNET_YES;
710 case GNUNET_BLOCK_EVALUATION_OK_MORE:
711 GNUNET_array_append (record->seen_replies,
712 record->seen_replies_count,
716 case GNUNET_BLOCK_EVALUATION_OK_DUPLICATE:
717 /* should be impossible to encounter here */
720 case GNUNET_BLOCK_EVALUATION_RESULT_INVALID:
723 case GNUNET_BLOCK_EVALUATION_REQUEST_VALID:
726 case GNUNET_BLOCK_EVALUATION_REQUEST_INVALID:
729 case GNUNET_BLOCK_EVALUATION_TYPE_NOT_SUPPORTED:
730 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
731 "Unsupported block type (%u) in request!\n",
735 if (GNUNET_NO == frc->do_copy)
737 /* first time, we can use the original data */
739 frc->do_copy = GNUNET_YES;
743 /* two clients waiting for same reply, must copy for queueing */
744 pm = GNUNET_malloc (sizeof (struct PendingMessage) +
745 ntohs (frc->pm->msg->size));
747 sizeof (struct PendingMessage) + ntohs (frc->pm->msg->size));
748 pm->next = pm->prev = NULL;
750 reply = (struct GNUNET_DHT_ClientResultMessage*) &pm[1];
751 reply->unique_id = record->unique_id;
752 add_pending_message (record->client, pm);
753 if (GNUNET_YES == do_free)
754 remove_client_records (record->client, key, record);
760 * Handle a reply we've received from another peer. If the reply
761 * matches any of our pending queries, forward it to the respective
764 * @param expiration when will the reply expire
765 * @param key the query this reply is for
766 * @param get_path_length number of peers in 'get_path'
767 * @param get_path path the reply took on get
768 * @param put_path_length number of peers in 'put_path'
769 * @param put_path path the reply took on put
770 * @param type type of the reply
771 * @param data_size number of bytes in 'data'
772 * @param data application payload data
775 GDS_CLIENT_handle_reply (struct GNUNET_TIME_Absolute expiration,
776 const GNUNET_HashCode *key,
777 unsigned int get_path_length,
778 const struct GNUNET_PeerIdentity *get_path,
779 unsigned int put_path_length,
780 const struct GNUNET_PeerIdentity *put_path,
781 enum GNUNET_BLOCK_Type type,
785 struct ForwardReplyContext frc;
786 struct PendingMessage *pm;
787 struct GNUNET_DHT_ClientResultMessage *reply;
788 struct GNUNET_PeerIdentity *paths;
792 GNUNET_CONTAINER_multihashmap_get (forward_map, key))
793 return; /* no matching request, fast exit! */
794 msize = sizeof(struct GNUNET_DHT_ClientResultMessage) + data_size +
795 (get_path_length + put_path_length) * sizeof (struct GNUNET_PeerIdentity);
796 if (msize >= GNUNET_SERVER_MAX_MESSAGE_SIZE)
798 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
799 _("Could not pass reply to client, message too big!\n"));
802 pm = (struct PendingMessage *) GNUNET_malloc (msize + sizeof (struct PendingMessage));
803 reply = (struct GNUNET_DHT_ClientResultMessage*) &pm[1];
804 pm->msg = &reply->header;
805 reply->header.size = htons ((uint16_t) msize);
806 reply->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_CLIENT_RESULT);
807 reply->type = htonl (type);
808 reply->get_path_length = htonl (get_path_length);
809 reply->put_path_length = htonl (put_path_length);
810 reply->unique_id = 0; /* filled in later */
811 reply->expiration = GNUNET_TIME_absolute_hton (expiration);
813 paths = (struct GNUNET_PeerIdentity*) &reply[1];
814 memcpy (paths, get_path,
815 sizeof (struct GNUNET_PeerIdentity) * get_path_length);
816 memcpy (&paths[get_path_length],
817 put_path, sizeof (struct GNUNET_PeerIdentity) * put_path_length);
818 memcpy (&paths[get_path_length + put_path_length],
821 frc.do_copy = GNUNET_NO;
824 frc.data_size = data_size;
826 GNUNET_CONTAINER_multihashmap_get_multiple (forward_map, key,
829 if (GNUNET_NO == frc.do_copy)
831 /* did not match any of the requests, free! */
838 * Initialize client subsystem.
840 * @param server the initialized server
843 GDS_CLIENT_init (struct GNUNET_SERVER_Handle *server)
845 static struct GNUNET_SERVER_MessageHandler plugin_handlers[] = {
846 {&handle_dht_local_put, NULL,
847 GNUNET_MESSAGE_TYPE_DHT_CLIENT_PUT, 0},
848 {&handle_dht_local_get, NULL,
849 GNUNET_MESSAGE_TYPE_DHT_CLIENT_GET, 0},
850 {&handle_dht_local_get_stop, NULL,
851 GNUNET_MESSAGE_TYPE_DHT_CLIENT_GET_STOP,
852 sizeof (struct GNUNET_DHT_ClientGetStopMessage) },
855 forward_map = GNUNET_CONTAINER_multihashmap_create (1024);
856 retry_heap = GNUNET_CONTAINER_heap_create (GNUNET_CONTAINER_HEAP_ORDER_MIN);
857 GNUNET_SERVER_add_handlers (server, plugin_handlers);
858 GNUNET_SERVER_disconnect_notify (server, &handle_client_disconnect, NULL);
863 * Shutdown client subsystem.
868 GNUNET_assert (client_head == NULL);
869 GNUNET_assert (client_tail == NULL);
870 if (GNUNET_SCHEDULER_NO_TASK != retry_task)
872 GNUNET_SCHEDULER_cancel (retry_task);
873 retry_task = GNUNET_SCHEDULER_NO_TASK;
875 GNUNET_assert (0 == GNUNET_CONTAINER_heap_get_size (retry_heap));
876 GNUNET_CONTAINER_heap_destroy (retry_heap);
878 GNUNET_assert (0 == GNUNET_CONTAINER_multihashmap_size (forward_map));
879 GNUNET_CONTAINER_multihashmap_destroy (forward_map);
883 /* end of gnunet-service-dht_clients.c */