src/dht/dht_api.c

   1 /*
   2      This file is part of GNUnet.
   3      (C) 2009, 2010 Christian Grothoff (and other contributing authors)
   4
   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.
   9
  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.
  14
  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.
  19 */
  20
  21 /**
  22  * @file dht/dht_api.c
  23  * @brief library to access the DHT service
  24  * @author Christian Grothoff
  25  * @author Nathan Evans
  26  */
  27
  28 #include "platform.h"
  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"
  39 #include "dht.h"
  40
  41 #define DEBUG_DHT_API GNUNET_NO
  42
  43 /**
  44  * Entry in our list of messages to be (re-)transmitted.
  45  */
  46 struct PendingMessage
  47 {
  48   /**
  49    * This is a doubly-linked list.
  50    */
  51   struct PendingMessage *prev;
  52
  53   /**
  54    * This is a doubly-linked list.
  55    */
  56   struct PendingMessage *next;
  57
  58   /**
  59    * Message that is pending, allocated at the end
  60    * of this struct.
  61    */
  62   const struct GNUNET_MessageHeader *msg;
  63
  64   /**
  65    * Handle to the DHT API context.
  66    */
  67   struct GNUNET_DHT_Handle *handle;
  68
  69   /**
  70    * Continuation to call when the request has been
  71    * transmitted (for the first time) to the service; can be NULL.
  72    */
  73   GNUNET_SCHEDULER_Task cont;
  74
  75   /**
  76    * Closure for 'cont'.
  77    */
  78   void *cont_cls;
  79
  80   /**
  81    * Timeout task for this message
  82    */
  83   GNUNET_SCHEDULER_TaskIdentifier timeout_task;
  84
  85   /**
  86    * Unique ID for this request
  87    */
  88   uint64_t unique_id;
  89
  90   /**
  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
  94    * from there.
  95    */
  96   int free_on_send;
  97
  98   /**
  99    * GNUNET_YES if this message is in our pending queue right now.
 100    */
 101   int in_pending_queue;
 102
 103 };
 104
 105
 106 /**
 107  * Handle to a route request
 108  */
 109 struct GNUNET_DHT_RouteHandle
 110 {
 111
 112   /**
 113    * Iterator to call on data receipt
 114    */
 115   GNUNET_DHT_ReplyProcessor iter;
 116
 117   /**
 118    * Closure for the iterator callback
 119    */
 120   void *iter_cls;
 121
 122   /**
 123    * Main handle to this DHT api
 124    */
 125   struct GNUNET_DHT_Handle *dht_handle;
 126
 127   /**
 128    * The actual message sent for this request,
 129    * used for retransmitting requests on service
 130    * failure/reconnect.  Freed on route_stop.
 131    */
 132   struct PendingMessage *message;
 133
 134   /**
 135    * Key that this get request is for
 136    */
 137   GNUNET_HashCode key;
 138
 139   /**
 140    * Unique identifier for this request (for key collisions)
 141    */
 142   uint64_t uid;
 143
 144 };
 145
 146
 147 /**
 148  * Connection to the DHT service.
 149  */
 150 struct GNUNET_DHT_Handle
 151 {
 152   /**
 153    * Our scheduler.
 154    */
 155   struct GNUNET_SCHEDULER_Handle *sched;
 156
 157   /**
 158    * Configuration to use.
 159    */
 160   const struct GNUNET_CONFIGURATION_Handle *cfg;
 161
 162   /**
 163    * Socket (if available).
 164    */
 165   struct GNUNET_CLIENT_Connection *client;
 166
 167   /**
 168    * Currently pending transmission request (or NULL).
 169    */
 170   struct GNUNET_CLIENT_TransmitHandle *th;
 171
 172   /**
 173    * Head of linked list of messages we would like to transmit.
 174    */
 175   struct PendingMessage *pending_head;
 176
 177   /**
 178    * Tail of linked list of messages we would like to transmit.
 179    */
 180   struct PendingMessage *pending_tail;
 181
 182   /**
 183    * Hash map containing the current outstanding unique requests
 184    * (values are of type 'struct GNUNET_DHT_RouteHandle').
 185    */
 186   struct GNUNET_CONTAINER_MultiHashMap *active_requests;
 187
 188   /**
 189    * Generator for unique ids.
 190    */
 191   uint64_t uid_gen;
 192
 193 };
 194
 195
 196 /**
 197  * Transmit the next pending message, called by notify_transmit_ready
 198  */
 199 static size_t
 200 transmit_pending (void *cls,
 201                   size_t size,
 202                   void *buf);
 203
 204
 205 /**
 206  * Handler for messages received from the DHT service
 207  * a demultiplexer which handles numerous message types
 208  *
 209  */
 210 static void
 211 service_message_handler (void *cls,
 212                          const struct GNUNET_MessageHeader *msg);
 213
 214
 215
 216
 217 /**
 218  * Try to (re)connect to the DHT service.
 219  *
 220  * @return GNUNET_YES on success, GNUNET_NO on failure.
 221  */
 222 static int
 223 try_connect (struct GNUNET_DHT_Handle *handle)
 224 {
 225   if (handle->client != NULL)
 226     return GNUNET_OK;
 227   handle->client = GNUNET_CLIENT_connect (handle->sched, "dht", handle->cfg);
 228   if (handle->client == NULL)
 229     {
 230       GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
 231                   _("Failed to connect to the DHT service!\n"));
 232       return GNUNET_NO;
 233     }
 234   GNUNET_CLIENT_receive (handle->client,
 235                          &service_message_handler,
 236                          handle,
 237                          GNUNET_TIME_UNIT_FOREVER_REL);
 238   return GNUNET_YES;
 239 }
 240
 241
 242 /**
 243  * Add the request corresponding to the given route handle
 244  * to the pending queue (if it is not already in there).
 245  *
 246  * @param cls the 'struct GNUNET_DHT_Handle*'
 247  * @param key key for the request (not used)
 248  * @param value the 'struct GNUNET_DHT_RouteHandle*'
 249  * @return GNUNET_YES (always)
 250  */
 251 static int
 252 add_request_to_pending (void *cls,
 253                         const GNUNET_HashCode *key,
 254                         void *value)
 255 {
 256   struct GNUNET_DHT_Handle *handle = cls;
 257   struct GNUNET_DHT_RouteHandle *rh = value;
 258
 259   if (GNUNET_NO == rh->message->in_pending_queue)
 260     {
 261       GNUNET_CONTAINER_DLL_insert (handle->pending_head,
 262                                    handle->pending_tail,
 263                                    rh->message);
 264       rh->message->in_pending_queue = GNUNET_YES;
 265     }
 266   return GNUNET_YES;
 267 }
 268
 269
 270 /**
 271  * Re-connect to the DHT, re-issue all pending requests if needed.
 272  */
 273 static void
 274 reconnect (struct GNUNET_DHT_Handle *handle)
 275 {
 276   if (handle->client != NULL)
 277     {
 278       GNUNET_CLIENT_disconnect (handle->client,
 279                                 GNUNET_NO);
 280       handle->client = NULL;
 281     }
 282   if (GNUNET_YES != try_connect (handle))
 283     return;
 284   GNUNET_CONTAINER_multihashmap_iterate (handle->active_requests,
 285                                          &add_request_to_pending,
 286                                          handle);
 287   if (handle->pending_head == NULL)
 288     return;
 289   GNUNET_CLIENT_notify_transmit_ready (handle->client,
 290                                        ntohs(handle->pending_head->msg->size),
 291                                        GNUNET_TIME_UNIT_FOREVER_REL,
 292                                        GNUNET_NO,
 293                                        &transmit_pending,
 294                                        handle);
 295
 296 }
 297
 298
 299 /**
 300  * Try to send messages from list of messages to send
 301  */
 302 static void
 303 process_pending_messages (struct GNUNET_DHT_Handle *handle)
 304 {
 305   struct PendingMessage *head;
 306
 307   if (GNUNET_YES != try_connect (handle))
 308     return;
 309   if (handle->th != NULL)
 310     return;
 311   if (NULL == (head = handle->pending_head))
 312     return;
 313   handle->th = GNUNET_CLIENT_notify_transmit_ready (handle->client,
 314                                                     ntohs (head->msg->size),
 315                                                     GNUNET_TIME_UNIT_FOREVER_REL,
 316                                                     GNUNET_YES,
 317                                                     &transmit_pending,
 318                                                     handle);
 319   if (NULL == handle->th)
 320     {
 321       reconnect (handle);
 322       return;
 323     }
 324 }
 325
 326
 327 /**
 328  * Transmit the next pending message, called by notify_transmit_ready
 329  */
 330 static size_t
 331 transmit_pending (void *cls,
 332                   size_t size,
 333                   void *buf)
 334 {
 335   struct GNUNET_DHT_Handle *handle = cls;
 336   struct PendingMessage *head;
 337   size_t tsize;
 338
 339   handle->th = NULL;
 340   if (buf == NULL)
 341     {
 342       reconnect (handle);
 343       return 0;
 344     }
 345   if (NULL == (head = handle->pending_head))
 346     return 0;
 347
 348   tsize = ntohs (head->msg->size);
 349   if (size < tsize)
 350     {
 351       process_pending_messages (handle);
 352       return 0;
 353     }
 354   memcpy (buf, head->msg, tsize);
 355   GNUNET_CONTAINER_DLL_remove (handle->pending_head,
 356                                handle->pending_tail,
 357                                head);
 358   if (head->timeout_task != GNUNET_SCHEDULER_NO_TASK)
 359     {
 360       GNUNET_SCHEDULER_cancel (handle->sched,
 361                                head->timeout_task);
 362       head->timeout_task = GNUNET_SCHEDULER_NO_TASK;
 363     }
 364   if (NULL != head->cont)
 365     {
 366       GNUNET_SCHEDULER_add_now (handle->sched,
 367                                 head->cont,
 368                                 head->cont_cls);
 369       head->cont = NULL;
 370       head->cont_cls = NULL;
 371     }
 372   head->in_pending_queue = GNUNET_NO;
 373   if (GNUNET_YES == head->free_on_send)
 374     GNUNET_free (head);
 375   process_pending_messages (handle);
 376   return tsize;
 377 }
 378
 379
 380
 381
 382 /**
 383  * Process a given reply that might match the given
 384  * request.
 385  */
 386 static int
 387 process_reply (void *cls,
 388                const GNUNET_HashCode *key,
 389                void *value)
 390 {
 391   const struct GNUNET_DHT_RouteResultMessage *dht_msg = cls;
 392   struct GNUNET_DHT_RouteHandle *rh = value;
 393   const struct GNUNET_MessageHeader *enc_msg;
 394   size_t enc_size;
 395   uint64_t uid;
 396
 397   uid = GNUNET_ntohll (dht_msg->unique_id);
 398   if (uid != rh->uid)
 399     return GNUNET_YES;
 400   enc_size = ntohs (dht_msg->header.size) - sizeof (struct GNUNET_DHT_RouteResultMessage);
 401   if (enc_size < sizeof (struct GNUNET_MessageHeader))
 402     {
 403       GNUNET_break (0);
 404       return GNUNET_NO;
 405     }
 406   enc_msg = (const struct GNUNET_MessageHeader *) &dht_msg[1];
 407   if (enc_size != ntohs (enc_msg->size))
 408     {
 409       GNUNET_break (0);
 410       return GNUNET_NO;
 411     }
 412   rh->iter (rh->iter_cls,
 413             &rh->key,
 414             enc_msg);
 415   return GNUNET_YES;
 416 }
 417
 418
 419 /**
 420  * Handler for messages received from the DHT service
 421  * a demultiplexer which handles numerous message types
 422  *
 423  * @param cls the 'struct GNUNET_DHT_Handle'
 424  * @param msg the incoming message
 425  */
 426 static void
 427 service_message_handler (void *cls,
 428                          const struct GNUNET_MessageHeader *msg)
 429 {
 430   struct GNUNET_DHT_Handle *handle = cls;
 431   const struct GNUNET_DHT_RouteResultMessage *dht_msg;
 432
 433   if (msg == NULL)
 434     {
 435       reconnect (handle);
 436       return;
 437     }
 438   if (ntohs (msg->type) != GNUNET_MESSAGE_TYPE_DHT_LOCAL_ROUTE_RESULT)
 439     {
 440       GNUNET_break (0);
 441       reconnect (handle);
 442       return;
 443     }
 444   if (ntohs (msg->size) < sizeof (struct GNUNET_DHT_RouteResultMessage))
 445     {
 446       GNUNET_break (0);
 447       reconnect (handle);
 448       return;
 449     }
 450   dht_msg = (const struct GNUNET_DHT_RouteResultMessage *) msg;
 451   GNUNET_CONTAINER_multihashmap_get_multiple (handle->active_requests,
 452                                               &dht_msg->key,
 453                                               &process_reply,
 454                                               (void*) dht_msg);
 455   GNUNET_CLIENT_receive (handle->client,
 456                          &service_message_handler,
 457                          handle, GNUNET_TIME_UNIT_FOREVER_REL);
 458
 459 }
 460
 461
 462 /**
 463  * Initialize the connection with the DHT service.
 464  *
 465  * @param sched scheduler to use
 466  * @param cfg configuration to use
 467  * @param ht_len size of the internal hash table to use for
 468  *               processing multiple GET/FIND requests in parallel
 469  *
 470  * @return handle to the DHT service, or NULL on error
 471  */
 472 struct GNUNET_DHT_Handle *
 473 GNUNET_DHT_connect (struct GNUNET_SCHEDULER_Handle *sched,
 474                     const struct GNUNET_CONFIGURATION_Handle *cfg,
 475                     unsigned int ht_len)
 476 {
 477   struct GNUNET_DHT_Handle *handle;
 478
 479   handle = GNUNET_malloc (sizeof (struct GNUNET_DHT_Handle));
 480   handle->cfg = cfg;
 481   handle->sched = sched;
 482   handle->uid_gen = GNUNET_CRYPTO_random_u64(GNUNET_CRYPTO_QUALITY_WEAK, UINT64_MAX);
 483   handle->active_requests = GNUNET_CONTAINER_multihashmap_create (ht_len);
 484   if (GNUNET_NO == try_connect (handle))
 485     {
 486       GNUNET_DHT_disconnect (handle);
 487       return NULL;
 488     }
 489   return handle;
 490 }
 491
 492
 493 /**
 494  * Shutdown connection with the DHT service.
 495  *
 496  * @param handle handle of the DHT connection to stop
 497  */
 498 void
 499 GNUNET_DHT_disconnect (struct GNUNET_DHT_Handle *handle)
 500 {
 501   struct PendingMessage *pm;
 502
 503   GNUNET_assert (0 == GNUNET_CONTAINER_multihashmap_size(handle->active_requests));
 504   if (handle->th != NULL)
 505     {
 506       GNUNET_CLIENT_notify_transmit_ready_cancel (handle->th);
 507       handle->th = NULL;
 508     }
 509   while (NULL != (pm = handle->pending_head))
 510     {
 511       GNUNET_CONTAINER_DLL_remove (handle->pending_head,
 512                                    handle->pending_tail,
 513                                    pm);
 514       GNUNET_assert (GNUNET_YES == pm->free_on_send);
 515       if (GNUNET_SCHEDULER_NO_TASK != pm->timeout_task)
 516         GNUNET_SCHEDULER_cancel (handle->sched,
 517                                  pm->timeout_task);
 518       if (NULL != pm->cont)
 519         GNUNET_SCHEDULER_add_continuation (handle->sched,
 520                                            pm->cont,
 521                                            pm->cont_cls,
 522                                            GNUNET_SCHEDULER_REASON_TIMEOUT);
 523       pm->in_pending_queue = GNUNET_NO;
 524       GNUNET_free (pm);
 525     }
 526   if (handle->client != NULL)
 527     {
 528       GNUNET_CLIENT_disconnect (handle->client, GNUNET_YES);
 529       handle->client = NULL;
 530     }
 531   GNUNET_CONTAINER_multihashmap_destroy(handle->active_requests);
 532   GNUNET_free (handle);
 533 }
 534
 535
 536
 537
 538 /* ***** Special low-level API providing generic routeing abstraction ***** */
 539
 540
 541 /**
 542  * Timeout for the transmission of a fire&forget-request.  Clean it up.
 543  *
 544  * @param cls the 'struct PendingMessage'
 545  * @param tc scheduler context
 546  */
 547 static void
 548 timeout_route_request (void *cls,
 549                        const struct GNUNET_SCHEDULER_TaskContext *tc)
 550 {
 551   struct PendingMessage *pending = cls;
 552   struct GNUNET_DHT_Handle *handle;
 553
 554   if (pending->free_on_send != GNUNET_YES)
 555     {
 556       /* timeouts should only apply to fire & forget requests! */
 557       GNUNET_break (0);
 558       return;
 559     }
 560   handle = pending->handle;
 561   GNUNET_CONTAINER_DLL_remove (handle->pending_head,
 562                                handle->pending_tail,
 563                                pending);
 564   if (pending->cont != NULL)
 565     pending->cont (pending->cont_cls,
 566                    tc);
 567   GNUNET_free (pending);
 568 }
 569
 570
 571 /**
 572  * Initiate a generic DHT route operation.
 573  *
 574  * @param handle handle to the DHT service
 575  * @param key the key to look up
 576  * @param desired_replication_level how many peers should ultimately receive
 577  *                this message (advisory only, target may be too high for the
 578  *                given DHT or not hit exactly).
 579  * @param options options for routing
 580  * @param enc send the encapsulated message to a peer close to the key
 581  * @param iter function to call on each result, NULL if no replies are expected
 582  * @param iter_cls closure for iter
 583  * @param timeout when to abort with an error if we fail to get
 584  *                a confirmation for the request (when necessary) or how long
 585  *                to wait for tramission to the service; only applies
 586  *                if 'iter' is NULL
 587  * @param cont continuation to call when the request has been transmitted
 588  *             the first time to the service
 589  * @param cont_cls closure for cont
 590  * @return handle to stop the request, NULL if the request is "fire and forget"
 591  */
 592 struct GNUNET_DHT_RouteHandle *
 593 GNUNET_DHT_route_start (struct GNUNET_DHT_Handle *handle,
 594                         const GNUNET_HashCode * key,
 595                         uint32_t desired_replication_level,
 596                         enum GNUNET_DHT_RouteOption options,
 597                         const struct GNUNET_MessageHeader *enc,
 598                         struct GNUNET_TIME_Relative timeout,
 599                         GNUNET_DHT_ReplyProcessor iter,
 600                         void *iter_cls,
 601                         GNUNET_SCHEDULER_Task cont,
 602                         void *cont_cls)
 603 {
 604   struct PendingMessage *pending;
 605   struct GNUNET_DHT_RouteMessage *message;
 606   struct GNUNET_DHT_RouteHandle *route_handle;
 607   uint16_t msize;
 608   uint16_t esize;
 609
 610   esize = ntohs (enc->size);
 611   if (sizeof (struct GNUNET_DHT_RouteMessage) + esize >= GNUNET_SERVER_MAX_MESSAGE_SIZE)
 612     {
 613       GNUNET_break (0);
 614       return NULL;
 615     }
 616   msize = sizeof (struct GNUNET_DHT_RouteMessage) + esize;
 617   pending = GNUNET_malloc (sizeof (struct PendingMessage) + msize);
 618   message = (struct GNUNET_DHT_RouteMessage*) &pending[1];
 619   pending->msg = &message->header;
 620   pending->handle = handle;
 621   pending->cont = cont;
 622   pending->cont_cls = cont_cls;
 623
 624   message->header.size = htons (msize);
 625   message->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_LOCAL_ROUTE);
 626   message->key = *key;
 627   message->options = htonl ((uint32_t) options);
 628   message->desired_replication_level = htonl (desired_replication_level);
 629   memcpy (&message[1], enc, esize);
 630   if (iter != NULL)
 631     {
 632       route_handle = GNUNET_malloc (sizeof (struct GNUNET_DHT_RouteHandle));
 633       route_handle->key = *key;
 634       route_handle->iter = iter;
 635       route_handle->iter_cls = iter_cls;
 636       route_handle->dht_handle = handle;
 637       route_handle->uid = handle->uid_gen++;
 638       route_handle->message = pending;
 639       message->unique_id = GNUNET_htonll (route_handle->uid);
 640       GNUNET_CONTAINER_multihashmap_put (handle->active_requests,
 641                                          key,
 642                                          route_handle,
 643                                          GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE);
 644     }
 645   else
 646     {
 647       route_handle = NULL;
 648       pending->free_on_send = GNUNET_YES;
 649       pending->timeout_task = GNUNET_SCHEDULER_add_delayed (handle->sched,
 650                                                             timeout,
 651                                                             &timeout_route_request,
 652                                                             pending);
 653     }
 654   GNUNET_CONTAINER_DLL_insert (handle->pending_head,
 655                                handle->pending_tail,
 656                                pending);
 657   pending->in_pending_queue = GNUNET_YES;
 658   process_pending_messages (handle);
 659   return route_handle;
 660 }
 661
 662
 663 /**
 664  * Stop a previously issued routing request
 665  *
 666  * @param route_handle handle to the request to stop
 667  */
 668 void
 669 GNUNET_DHT_route_stop (struct GNUNET_DHT_RouteHandle *route_handle)
 670 {
 671   struct GNUNET_DHT_Handle *handle;
 672   struct PendingMessage *pending;
 673   struct GNUNET_DHT_StopMessage *message;
 674   size_t msize;
 675
 676   handle = route_handle->dht_handle;
 677   if (GNUNET_NO == route_handle->message->in_pending_queue)
 678     {
 679       /* need to send stop message */
 680       msize = sizeof (struct GNUNET_DHT_StopMessage);
 681       pending = GNUNET_malloc (sizeof (struct PendingMessage) +
 682                                msize);
 683       message = (struct GNUNET_DHT_StopMessage*) &pending[1];
 684       pending->msg = &message->header;
 685       message->header.size = htons (msize);
 686       message->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_LOCAL_ROUTE_STOP);
 687       message->unique_id = GNUNET_htonll (route_handle->uid);
 688       message->key = route_handle->key;
 689       pending->handle = handle;
 690       pending->free_on_send = GNUNET_YES;
 691       pending->in_pending_queue = GNUNET_YES;
 692       GNUNET_CONTAINER_DLL_insert (handle->pending_head,
 693                                    handle->pending_tail,
 694                                    pending);
 695       process_pending_messages (handle);
 696     }
 697   else
 698     {
 699       /* simply remove pending request from message queue before
 700          transmission, no need to transmit STOP request! */
 701       GNUNET_CONTAINER_DLL_remove (handle->pending_head,
 702                                    handle->pending_tail,
 703                                    route_handle->message);
 704     }
 705   GNUNET_assert (GNUNET_YES ==
 706                  GNUNET_CONTAINER_multihashmap_remove (route_handle->dht_handle->active_requests,
 707                                                        &route_handle->key,
 708                                                        route_handle));
 709   GNUNET_free(route_handle->message);
 710   GNUNET_free(route_handle);
 711 }
 712
 713
 714
 715 /* ***** Special API for controlling DHT routing maintenance ******* */
 716
 717
 718 /**
 719  * Send a control message to the DHT.
 720  *
 721  * @param handle handle to the DHT service
 722  * @param command command
 723  * @param variable variable to the command
 724  * @param cont continuation to call when done (transmitting request to service)
 725  * @param cont_cls closure for cont
 726  */
 727 static void
 728 send_control_message (struct GNUNET_DHT_Handle *handle,
 729                       uint16_t command,
 730                       uint16_t variable,
 731                       GNUNET_SCHEDULER_Task cont,
 732                       void *cont_cls)
 733 {
 734   struct GNUNET_DHT_ControlMessage *msg;
 735   struct PendingMessage *pending;
 736
 737   pending = GNUNET_malloc (sizeof (struct PendingMessage) +
 738                            sizeof(struct GNUNET_DHT_ControlMessage));
 739   msg = (struct GNUNET_DHT_ControlMessage*) &pending[1];
 740   pending->msg = &msg->header;
 741   msg->header.size = htons (sizeof(struct GNUNET_DHT_ControlMessage));
 742   msg->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_CONTROL);
 743   msg->command = htons (command);
 744   msg->variable = htons (variable);
 745   pending->free_on_send = GNUNET_YES;
 746   pending->cont = cont;
 747   pending->cont_cls = cont_cls;
 748   pending->in_pending_queue = GNUNET_YES;
 749   GNUNET_CONTAINER_DLL_insert (handle->pending_head,
 750                                handle->pending_tail,
 751                                pending);
 752   process_pending_messages (handle);
 753 }
 754
 755
 756 /**
 757  * Send a message to the DHT telling it to issue a single find
 758  * peer request using the peers unique identifier as key.  This
 759  * is used to fill the routing table, and is normally controlled
 760  * by the DHT itself.  However, for testing and perhaps more
 761  * close control over the DHT, this can be explicitly managed.
 762  *
 763  * @param handle handle to the DHT service
 764  * @param cont continuation to call when done (transmitting request to service)
 765  * @param cont_cls closure for cont
 766  */
 767 void
 768 GNUNET_DHT_find_peers (struct GNUNET_DHT_Handle *handle,
 769                        GNUNET_SCHEDULER_Task cont,
 770                        void *cont_cls)
 771 {
 772   send_control_message (handle,
 773                         GNUNET_MESSAGE_TYPE_DHT_FIND_PEER, 0,
 774                         cont, cont_cls);
 775 }
 776
 777
 778
 779 #if HAVE_MALICIOUS
 780
 781 /**
 782  * Send a message to the DHT telling it to start issuing random GET
 783  * requests every 'frequency' milliseconds.
 784  *
 785  * @param handle handle to the DHT service
 786  * @param frequency delay between sending malicious messages
 787  */
 788 void
 789 GNUNET_DHT_set_malicious_getter (struct GNUNET_DHT_Handle *handle,
 790                                  struct GNUNET_TIME_Relative frequency)
 791 {
 792   if (frequency.value > UINT16_MAX)
 793     {
 794       GNUNET_break (0);
 795       return;
 796     }
 797   send_control_message (handle,
 798                         GNUNET_MESSAGE_TYPE_DHT_MALICIOUS_GET, frequency.value,
 799                         NULL, NULL);
 800 }
 801
 802 /**
 803  * Send a message to the DHT telling it to start issuing random PUT
 804  * requests every 'frequency' milliseconds.
 805  *
 806  * @param handle handle to the DHT service
 807  * @param frequency delay between sending malicious messages
 808  */
 809 void
 810 GNUNET_DHT_set_malicious_putter (struct GNUNET_DHT_Handle *handle,
 811                                  struct GNUNET_TIME_Relative frequency)
 812 {
 813   if (frequency.value > UINT16_MAX)
 814     {
 815       GNUNET_break (0);
 816       return;
 817     }
 818   send_control_message (handle,
 819                         GNUNET_MESSAGE_TYPE_DHT_MALICIOUS_PUT, frequency.value,
 820                         NULL, NULL);
 821 }
 822
 823
 824 /**
 825  * Send a message to the DHT telling it to start dropping
 826  * all requests received.
 827  *
 828  * @param handle handle to the DHT service
 829  */
 830 void
 831 GNUNET_DHT_set_malicious_dropper (struct GNUNET_DHT_Handle *handle)
 832 {
 833   send_control_message (handle,
 834                         GNUNET_MESSAGE_TYPE_DHT_MALICIOUS_DROP, 0,
 835                         NULL, NULL);
 836 }
 837
 838 #endif
 839
 840 /* end of dht_api.c */