2 This file is part of GNUnet.
3 (C) 2009, 2010 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.
10 GNUnet is distributed in the hope that it will be useful, but
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 library to access the DHT service
24 * @author Christian Grothoff
25 * @author Nathan Evans
29 #include "gnunet_util_lib.h"
30 #include "gnunet_constants.h"
31 #include "gnunet_arm_service.h"
32 #include "gnunet_hello_lib.h"
33 #include "gnunet_protocols.h"
34 #include "gnunet_dht_service.h"
37 #define DEBUG_DHT_API GNUNET_EXTRA_LOGGING
39 #define LOG(kind,...) GNUNET_log_from (kind, "dht-api",__VA_ARGS__)
42 * Entry in our list of messages to be (re-)transmitted.
47 * This is a doubly-linked list.
49 struct PendingMessage *prev;
52 * This is a doubly-linked list.
54 struct PendingMessage *next;
57 * Message that is pending, allocated at the end
60 const struct GNUNET_MessageHeader *msg;
63 * Handle to the DHT API context.
65 struct GNUNET_DHT_Handle *handle;
68 * Continuation to call when the request has been
69 * transmitted (for the first time) to the service; can be NULL.
71 GNUNET_SCHEDULER_Task cont;
79 * Timeout task for this message
81 GNUNET_SCHEDULER_TaskIdentifier timeout_task;
84 * Unique ID for this request
89 * Free the saved message once sent, set to GNUNET_YES for messages
90 * that do not receive responses; GNUNET_NO if this pending message
91 * is aliased from a 'struct GNUNET_DHT_RouteHandle' and will be freed
97 * GNUNET_YES if this message is in our pending queue right now.
105 * Handle to a GET request
107 struct GNUNET_DHT_GetHandle
111 * Iterator to call on data receipt
113 GNUNET_DHT_GetIterator iter;
116 * Closure for the iterator callback
121 * Main handle to this DHT api
123 struct GNUNET_DHT_Handle *dht_handle;
126 * The actual message sent for this request,
127 * used for retransmitting requests on service
128 * failure/reconnect. Freed on route_stop.
130 struct PendingMessage *message;
133 * Key that this get request is for
138 * Unique identifier for this request (for key collisions).
146 * Connection to the DHT service.
148 struct GNUNET_DHT_Handle
152 * Configuration to use.
154 const struct GNUNET_CONFIGURATION_Handle *cfg;
157 * Socket (if available).
159 struct GNUNET_CLIENT_Connection *client;
162 * Currently pending transmission request (or NULL).
164 struct GNUNET_CLIENT_TransmitHandle *th;
167 * Head of linked list of messages we would like to transmit.
169 struct PendingMessage *pending_head;
172 * Tail of linked list of messages we would like to transmit.
174 struct PendingMessage *pending_tail;
177 * Hash map containing the current outstanding unique requests
178 * (values are of type 'struct GNUNET_DHT_RouteHandle').
180 struct GNUNET_CONTAINER_MultiHashMap *active_requests;
183 * Task for trying to reconnect.
185 GNUNET_SCHEDULER_TaskIdentifier reconnect_task;
188 * How quickly should we retry? Used for exponential back-off on
191 struct GNUNET_TIME_Relative retry_time;
194 * Generator for unique ids.
202 * Handler for messages received from the DHT service
203 * a demultiplexer which handles numerous message types
207 service_message_handler (void *cls, const struct GNUNET_MessageHeader *msg);
211 * Try to (re)connect to the DHT service.
213 * @return GNUNET_YES on success, GNUNET_NO on failure.
216 try_connect (struct GNUNET_DHT_Handle *handle)
218 if (handle->client != NULL)
220 handle->client = GNUNET_CLIENT_connect ("dht", handle->cfg);
221 if (handle->client == NULL)
223 LOG (GNUNET_ERROR_TYPE_WARNING,
224 _("Failed to connect to the DHT service!\n"));
228 LOG (GNUNET_ERROR_TYPE_DEBUG, "Starting to process replies from DHT\n");
230 GNUNET_CLIENT_receive (handle->client, &service_message_handler, handle,
231 GNUNET_TIME_UNIT_FOREVER_REL);
237 * Add the request corresponding to the given route handle
238 * to the pending queue (if it is not already in there).
240 * @param cls the 'struct GNUNET_DHT_Handle*'
241 * @param key key for the request (not used)
242 * @param value the 'struct GNUNET_DHT_GetHandle*'
243 * @return GNUNET_YES (always)
246 add_request_to_pending (void *cls, const GNUNET_HashCode * key, void *value)
248 struct GNUNET_DHT_Handle *handle = cls;
249 struct GNUNET_DHT_GetHandle *rh = value;
251 if (GNUNET_NO == rh->message->in_pending_queue)
253 GNUNET_CONTAINER_DLL_insert (handle->pending_head, handle->pending_tail,
255 rh->message->in_pending_queue = GNUNET_YES;
262 * Try to send messages from list of messages to send
263 * @param handle DHT_Handle
266 process_pending_messages (struct GNUNET_DHT_Handle *handle);
270 * Try reconnecting to the dht service.
272 * @param cls GNUNET_DHT_Handle
273 * @param tc scheduler context
276 try_reconnect (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
278 struct GNUNET_DHT_Handle *handle = cls;
280 handle->reconnect_task = GNUNET_SCHEDULER_NO_TASK;
281 if (handle->retry_time.rel_value < GNUNET_CONSTANTS_SERVICE_RETRY.rel_value)
282 handle->retry_time = GNUNET_CONSTANTS_SERVICE_RETRY;
284 handle->retry_time = GNUNET_TIME_relative_multiply (handle->retry_time, 2);
285 if (handle->retry_time.rel_value > GNUNET_CONSTANTS_SERVICE_TIMEOUT.rel_value)
286 handle->retry_time = GNUNET_CONSTANTS_SERVICE_TIMEOUT;
287 handle->reconnect_task = GNUNET_SCHEDULER_NO_TASK;
288 handle->client = GNUNET_CLIENT_connect ("dht", handle->cfg);
289 if (handle->client == NULL)
291 LOG (GNUNET_ERROR_TYPE_DEBUG, "dht reconnect failed(!)\n");
294 GNUNET_CONTAINER_multihashmap_iterate (handle->active_requests,
295 &add_request_to_pending, handle);
296 process_pending_messages (handle);
301 * Try reconnecting to the DHT service.
303 * @param handle handle to dht to (possibly) disconnect and reconnect
306 do_disconnect (struct GNUNET_DHT_Handle *handle)
308 if (handle->client == NULL)
310 GNUNET_assert (handle->reconnect_task == GNUNET_SCHEDULER_NO_TASK);
311 if (NULL != handle->th)
312 GNUNET_CLIENT_notify_transmit_ready_cancel (handle->th);
314 GNUNET_CLIENT_disconnect (handle->client, GNUNET_NO);
315 handle->client = NULL;
316 handle->reconnect_task =
317 GNUNET_SCHEDULER_add_delayed (handle->retry_time, &try_reconnect, handle);
322 * Transmit the next pending message, called by notify_transmit_ready
325 transmit_pending (void *cls, size_t size, void *buf);
329 * Try to send messages from list of messages to send
332 process_pending_messages (struct GNUNET_DHT_Handle *handle)
334 struct PendingMessage *head;
336 if (handle->client == NULL)
338 do_disconnect (handle);
341 if (handle->th != NULL)
343 if (NULL == (head = handle->pending_head))
346 GNUNET_CLIENT_notify_transmit_ready (handle->client,
347 ntohs (head->msg->size),
348 GNUNET_TIME_UNIT_FOREVER_REL,
349 GNUNET_YES, &transmit_pending,
351 if (NULL != handle->th)
353 do_disconnect (handle);
358 * Transmit the next pending message, called by notify_transmit_ready
361 transmit_pending (void *cls, size_t size, void *buf)
363 struct GNUNET_DHT_Handle *handle = cls;
364 struct PendingMessage *head;
370 LOG (GNUNET_ERROR_TYPE_DEBUG,
371 "Transmission to DHT service failed! Reconnecting!\n");
372 do_disconnect (handle);
375 if (NULL == (head = handle->pending_head))
378 tsize = ntohs (head->msg->size);
381 process_pending_messages (handle);
384 memcpy (buf, head->msg, tsize);
385 GNUNET_CONTAINER_DLL_remove (handle->pending_head, handle->pending_tail,
387 if (head->timeout_task != GNUNET_SCHEDULER_NO_TASK)
389 GNUNET_SCHEDULER_cancel (head->timeout_task);
390 head->timeout_task = GNUNET_SCHEDULER_NO_TASK;
392 if (NULL != head->cont)
394 GNUNET_SCHEDULER_add_continuation (head->cont, head->cont_cls,
395 GNUNET_SCHEDULER_REASON_PREREQ_DONE);
397 head->cont_cls = NULL;
399 head->in_pending_queue = GNUNET_NO;
400 if (GNUNET_YES == head->free_on_send)
402 process_pending_messages (handle);
404 LOG (GNUNET_ERROR_TYPE_DEBUG,
405 "Forwarded request of %u bytes to DHT service\n", (unsigned int) tsize);
412 * Process a given reply that might match the given
415 * @param cls the 'struct GNUNET_DHT_ClientResultMessage'
416 * @param key query of the request
417 * @param value the 'struct GNUNET_DHT_RouteHandle' of a request matching the same key
418 * @return GNUNET_YES to continue to iterate over all results,
419 * GNUNET_NO if the reply is malformed
422 process_reply (void *cls, const GNUNET_HashCode * key, void *value)
424 const struct GNUNET_DHT_ClientResultMessage *dht_msg = cls;
425 struct GNUNET_DHT_GetHandle *get_handle = value;
426 const struct GNUNET_PeerIdentity *put_path;
427 const struct GNUNET_PeerIdentity *get_path;
428 uint32_t put_path_length;
429 uint32_t get_path_length;
435 if (dht_msg->unique_id != get_handle->unique_id)
438 LOG (GNUNET_ERROR_TYPE_DEBUG, "Ignoring reply (UID mismatch: %llu/%llu)\n",
439 dht_msg->unique_id, get_handle->unique_id);
442 msize = ntohs (dht_msg->header.size);
443 put_path_length = ntohl (dht_msg->put_path_length);
444 get_path_length = ntohl (dht_msg->get_path_length);
446 sizeof (struct GNUNET_DHT_ClientResultMessage) +
447 sizeof (struct GNUNET_PeerIdentity) * (get_path_length + put_path_length);
448 if ((msize < meta_length) ||
450 GNUNET_SERVER_MAX_MESSAGE_SIZE / sizeof (struct GNUNET_PeerIdentity)) ||
452 GNUNET_SERVER_MAX_MESSAGE_SIZE / sizeof (struct GNUNET_PeerIdentity)))
457 data_length = msize - meta_length;
458 put_path = (const struct GNUNET_PeerIdentity *) &dht_msg[1];
459 get_path = &put_path[put_path_length];
460 data = &get_path[get_path_length];
461 get_handle->iter (get_handle->iter_cls,
462 GNUNET_TIME_absolute_ntoh (dht_msg->expiration), key,
463 get_path, get_path_length, put_path, put_path_length,
464 ntohl (dht_msg->type), data_length, data);
470 * Handler for messages received from the DHT service
471 * a demultiplexer which handles numerous message types
473 * @param cls the 'struct GNUNET_DHT_Handle'
474 * @param msg the incoming message
477 service_message_handler (void *cls, const struct GNUNET_MessageHeader *msg)
479 struct GNUNET_DHT_Handle *handle = cls;
480 const struct GNUNET_DHT_ClientResultMessage *dht_msg;
484 LOG (GNUNET_ERROR_TYPE_DEBUG,
485 "Error receiving data from DHT service, reconnecting\n");
486 do_disconnect (handle);
489 if (ntohs (msg->type) != GNUNET_MESSAGE_TYPE_DHT_CLIENT_RESULT)
492 do_disconnect (handle);
495 if (ntohs (msg->size) < sizeof (struct GNUNET_DHT_ClientResultMessage))
498 do_disconnect (handle);
501 LOG (GNUNET_ERROR_TYPE_DEBUG, "Received reply from DHT service\n");
502 dht_msg = (const struct GNUNET_DHT_ClientResultMessage *) msg;
503 GNUNET_CONTAINER_multihashmap_get_multiple (handle->active_requests,
504 &dht_msg->key, &process_reply,
506 GNUNET_CLIENT_receive (handle->client, &service_message_handler, handle,
507 GNUNET_TIME_UNIT_FOREVER_REL);
512 * Initialize the connection with the DHT service.
514 * @param cfg configuration to use
515 * @param ht_len size of the internal hash table to use for
516 * processing multiple GET/FIND requests in parallel
518 * @return handle to the DHT service, or NULL on error
520 struct GNUNET_DHT_Handle *
521 GNUNET_DHT_connect (const struct GNUNET_CONFIGURATION_Handle *cfg,
524 struct GNUNET_DHT_Handle *handle;
526 handle = GNUNET_malloc (sizeof (struct GNUNET_DHT_Handle));
529 GNUNET_CRYPTO_random_u64 (GNUNET_CRYPTO_QUALITY_WEAK, UINT64_MAX);
530 handle->active_requests = GNUNET_CONTAINER_multihashmap_create (ht_len);
531 if (GNUNET_NO == try_connect (handle))
533 GNUNET_DHT_disconnect (handle);
541 * Shutdown connection with the DHT service.
543 * @param handle handle of the DHT connection to stop
546 GNUNET_DHT_disconnect (struct GNUNET_DHT_Handle *handle)
548 struct PendingMessage *pm;
550 GNUNET_assert (handle != NULL);
552 GNUNET_CONTAINER_multihashmap_size (handle->active_requests));
553 if (handle->th != NULL)
555 GNUNET_CLIENT_notify_transmit_ready_cancel (handle->th);
558 while (NULL != (pm = handle->pending_head))
560 GNUNET_CONTAINER_DLL_remove (handle->pending_head, handle->pending_tail,
562 GNUNET_assert (GNUNET_YES == pm->free_on_send);
563 if (GNUNET_SCHEDULER_NO_TASK != pm->timeout_task)
564 GNUNET_SCHEDULER_cancel (pm->timeout_task);
565 if (NULL != pm->cont)
566 GNUNET_SCHEDULER_add_continuation (pm->cont, pm->cont_cls,
567 GNUNET_SCHEDULER_REASON_TIMEOUT);
568 pm->in_pending_queue = GNUNET_NO;
571 if (handle->client != NULL)
573 GNUNET_CLIENT_disconnect (handle->client, GNUNET_YES);
574 handle->client = NULL;
576 if (handle->reconnect_task != GNUNET_SCHEDULER_NO_TASK)
577 GNUNET_SCHEDULER_cancel (handle->reconnect_task);
578 GNUNET_CONTAINER_multihashmap_destroy (handle->active_requests);
579 GNUNET_free (handle);
584 * Timeout for the transmission of a fire&forget-request. Clean it up.
586 * @param cls the 'struct PendingMessage'
587 * @param tc scheduler context
590 timeout_put_request (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
592 struct PendingMessage *pending = cls;
593 struct GNUNET_DHT_Handle *handle;
595 handle = pending->handle;
596 GNUNET_CONTAINER_DLL_remove (handle->pending_head, handle->pending_tail,
598 if (pending->cont != NULL)
599 pending->cont (pending->cont_cls, tc);
600 GNUNET_free (pending);
605 * Perform a PUT operation storing data in the DHT.
607 * @param handle handle to DHT service
608 * @param key the key to store under
609 * @param desired_replication_level estimate of how many
610 * nearest peers this request should reach
611 * @param options routing options for this message
612 * @param type type of the value
613 * @param size number of bytes in data; must be less than 64k
614 * @param data the data to store
615 * @param exp desired expiration time for the value
616 * @param timeout how long to wait for transmission of this request
617 * @param cont continuation to call when done (transmitting request to service)
618 * @param cont_cls closure for cont
621 GNUNET_DHT_put (struct GNUNET_DHT_Handle *handle, const GNUNET_HashCode * key,
622 uint32_t desired_replication_level,
623 enum GNUNET_DHT_RouteOption options,
624 enum GNUNET_BLOCK_Type type, size_t size, const char *data,
625 struct GNUNET_TIME_Absolute exp,
626 struct GNUNET_TIME_Relative timeout, GNUNET_SCHEDULER_Task cont,
629 struct GNUNET_DHT_ClientPutMessage *put_msg;
631 struct PendingMessage *pending;
633 msize = sizeof (struct GNUNET_DHT_ClientPutMessage) + size;
634 if ((msize >= GNUNET_SERVER_MAX_MESSAGE_SIZE) ||
635 (size >= GNUNET_SERVER_MAX_MESSAGE_SIZE))
639 cont (cont_cls, NULL);
642 pending = GNUNET_malloc (sizeof (struct PendingMessage) + msize);
643 put_msg = (struct GNUNET_DHT_ClientPutMessage *) &pending[1];
644 pending->msg = &put_msg->header;
645 pending->handle = handle;
646 pending->cont = cont;
647 pending->cont_cls = cont_cls;
648 pending->free_on_send = GNUNET_YES;
649 pending->timeout_task =
650 GNUNET_SCHEDULER_add_delayed (timeout, &timeout_put_request, pending);
651 put_msg->header.size = htons (msize);
652 put_msg->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_CLIENT_PUT);
653 put_msg->type = htonl (type);
654 put_msg->options = htonl ((uint32_t) options);
655 put_msg->desired_replication_level = htonl (desired_replication_level);
656 put_msg->expiration = GNUNET_TIME_absolute_hton (exp);
658 memcpy (&put_msg[1], data, size);
659 GNUNET_CONTAINER_DLL_insert (handle->pending_head, handle->pending_tail,
661 pending->in_pending_queue = GNUNET_YES;
662 process_pending_messages (handle);
667 * Perform an asynchronous GET operation on the DHT identified. See
668 * also "GNUNET_BLOCK_evaluate".
670 * @param handle handle to the DHT service
671 * @param timeout how long to wait for transmission of this request to the service
672 * @param type expected type of the response object
673 * @param key the key to look up
674 * @param desired_replication_level estimate of how many
675 nearest peers this request should reach
676 * @param options routing options for this message
677 * @param xquery extended query data (can be NULL, depending on type)
678 * @param xquery_size number of bytes in xquery
679 * @param iter function to call on each result
680 * @param iter_cls closure for iter
681 * @return handle to stop the async get
683 struct GNUNET_DHT_GetHandle *
684 GNUNET_DHT_get_start (struct GNUNET_DHT_Handle *handle,
685 struct GNUNET_TIME_Relative timeout,
686 enum GNUNET_BLOCK_Type type, const GNUNET_HashCode * key,
687 uint32_t desired_replication_level,
688 enum GNUNET_DHT_RouteOption options, const void *xquery,
689 size_t xquery_size, GNUNET_DHT_GetIterator iter,
692 struct GNUNET_DHT_ClientGetMessage *get_msg;
693 struct GNUNET_DHT_GetHandle *get_handle;
695 struct PendingMessage *pending;
697 msize = sizeof (struct GNUNET_DHT_ClientGetMessage) + xquery_size;
698 if ((msize >= GNUNET_SERVER_MAX_MESSAGE_SIZE) ||
699 (xquery_size >= GNUNET_SERVER_MAX_MESSAGE_SIZE))
704 pending = GNUNET_malloc (sizeof (struct PendingMessage) + msize);
705 get_msg = (struct GNUNET_DHT_ClientGetMessage *) &pending[1];
706 pending->msg = &get_msg->header;
707 pending->handle = handle;
708 pending->free_on_send = GNUNET_NO;
709 get_msg->header.size = htons (msize);
710 get_msg->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_CLIENT_GET);
711 get_msg->options = htonl ((uint32_t) options);
712 get_msg->desired_replication_level = htonl (desired_replication_level);
713 get_msg->type = htonl (type);
716 get_msg->unique_id = handle->uid_gen;
717 memcpy (&get_msg[1], xquery, xquery_size);
718 GNUNET_CONTAINER_DLL_insert (handle->pending_head, handle->pending_tail,
720 pending->in_pending_queue = GNUNET_YES;
721 get_handle = GNUNET_malloc (sizeof (struct GNUNET_DHT_GetHandle));
722 get_handle->iter = iter;
723 get_handle->iter_cls = iter_cls;
724 get_handle->message = pending;
725 get_handle->unique_id = get_msg->unique_id;
726 GNUNET_CONTAINER_multihashmap_put (handle->active_requests, key, get_handle,
727 GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE);
728 process_pending_messages (handle);
734 * Stop async DHT-get.
736 * @param get_handle handle to the GET operation to stop
739 GNUNET_DHT_get_stop (struct GNUNET_DHT_GetHandle *get_handle)
741 struct GNUNET_DHT_Handle *handle;
742 const struct GNUNET_DHT_ClientGetMessage *get_msg;
743 struct GNUNET_DHT_ClientGetStopMessage *stop_msg;
744 struct PendingMessage *pending;
746 handle = get_handle->message->handle;
748 (const struct GNUNET_DHT_ClientGetMessage *) get_handle->message->msg;
752 GNUNET_malloc (sizeof (struct PendingMessage) +
753 sizeof (struct GNUNET_DHT_ClientGetStopMessage));
754 stop_msg = (struct GNUNET_DHT_ClientGetStopMessage *) &pending[1];
755 pending->msg = &stop_msg->header;
756 pending->handle = handle;
757 pending->free_on_send = GNUNET_YES;
758 stop_msg->header.size =
759 htons (sizeof (struct GNUNET_DHT_ClientGetStopMessage));
760 stop_msg->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_CLIENT_GET_STOP);
761 stop_msg->reserved = htonl (0);
762 stop_msg->unique_id = get_msg->unique_id;
763 stop_msg->key = get_msg->key;
764 GNUNET_CONTAINER_DLL_insert (handle->pending_head, handle->pending_tail,
766 pending->in_pending_queue = GNUNET_YES;
768 /* remove 'GET' from active status */
769 GNUNET_assert (GNUNET_YES ==
770 GNUNET_CONTAINER_multihashmap_remove (handle->active_requests,
773 if (GNUNET_YES == get_handle->message->in_pending_queue)
775 GNUNET_CONTAINER_DLL_remove (handle->pending_head, handle->pending_tail,
776 get_handle->message);
777 get_handle->message->in_pending_queue = GNUNET_NO;
779 GNUNET_free (get_handle->message);
780 GNUNET_free (get_handle);
782 process_pending_messages (handle);
786 /* end of dht_api.c */