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_log (GNUNET_ERROR_TYPE_DEBUG,
 235               "Starting to process replies from DHT\n");
 236   GNUNET_CLIENT_receive (handle->client,
 237                          &service_message_handler,
 238                          handle,
 239                          GNUNET_TIME_UNIT_FOREVER_REL);
 240   return GNUNET_YES;
 241 }
 242
 243
 244 /**
 245  * Add the request corresponding to the given route handle
 246  * to the pending queue (if it is not already in there).
 247  *
 248  * @param cls the 'struct GNUNET_DHT_Handle*'
 249  * @param key key for the request (not used)
 250  * @param value the 'struct GNUNET_DHT_RouteHandle*'
 251  * @return GNUNET_YES (always)
 252  */
 253 static int
 254 add_request_to_pending (void *cls,
 255                         const GNUNET_HashCode *key,
 256                         void *value)
 257 {
 258   struct GNUNET_DHT_Handle *handle = cls;
 259   struct GNUNET_DHT_RouteHandle *rh = value;
 260
 261   if (GNUNET_NO == rh->message->in_pending_queue)
 262     {
 263       GNUNET_CONTAINER_DLL_insert (handle->pending_head,
 264                                    handle->pending_tail,
 265                                    rh->message);
 266       rh->message->in_pending_queue = GNUNET_YES;
 267     }
 268   return GNUNET_YES;
 269 }
 270
 271
 272 /**
 273  * Re-connect to the DHT, re-issue all pending requests if needed.
 274  */
 275 static void
 276 reconnect (struct GNUNET_DHT_Handle *handle)
 277 {
 278   if (handle->client != NULL)
 279     {
 280       GNUNET_CLIENT_disconnect (handle->client,
 281                                 GNUNET_NO);
 282       handle->client = NULL;
 283     }
 284   if (GNUNET_YES != try_connect (handle))
 285     return;
 286   GNUNET_CONTAINER_multihashmap_iterate (handle->active_requests,
 287                                          &add_request_to_pending,
 288                                          handle);
 289   if (handle->pending_head == NULL)
 290     return;
 291   GNUNET_CLIENT_notify_transmit_ready (handle->client,
 292                                        ntohs(handle->pending_head->msg->size),
 293                                        GNUNET_TIME_UNIT_FOREVER_REL,
 294                                        GNUNET_NO,
 295                                        &transmit_pending,
 296                                        handle);
 297
 298 }
 299
 300
 301 /**
 302  * Try to send messages from list of messages to send
 303  */
 304 static void
 305 process_pending_messages (struct GNUNET_DHT_Handle *handle)
 306 {
 307   struct PendingMessage *head;
 308
 309   if (GNUNET_YES != try_connect (handle))
 310     return;
 311   if (handle->th != NULL)
 312     return;
 313   if (NULL == (head = handle->pending_head))
 314     return;
 315   handle->th = GNUNET_CLIENT_notify_transmit_ready (handle->client,
 316                                                     ntohs (head->msg->size),
 317                                                     GNUNET_TIME_UNIT_FOREVER_REL,
 318                                                     GNUNET_YES,
 319                                                     &transmit_pending,
 320                                                     handle);
 321   if (NULL == handle->th)
 322     {
 323       reconnect (handle);
 324       return;
 325     }
 326 }
 327
 328
 329 /**
 330  * Transmit the next pending message, called by notify_transmit_ready
 331  */
 332 static size_t
 333 transmit_pending (void *cls,
 334                   size_t size,
 335                   void *buf)
 336 {
 337   struct GNUNET_DHT_Handle *handle = cls;
 338   struct PendingMessage *head;
 339   size_t tsize;
 340
 341   handle->th = NULL;
 342   if (buf == NULL)
 343     {
 344       reconnect (handle);
 345       return 0;
 346     }
 347   if (NULL == (head = handle->pending_head))
 348     return 0;
 349
 350   tsize = ntohs (head->msg->size);
 351   if (size < tsize)
 352     {
 353       process_pending_messages (handle);
 354       return 0;
 355     }
 356   memcpy (buf, head->msg, tsize);
 357   GNUNET_CONTAINER_DLL_remove (handle->pending_head,
 358                                handle->pending_tail,
 359                                head);
 360   if (head->timeout_task != GNUNET_SCHEDULER_NO_TASK)
 361     {
 362       GNUNET_SCHEDULER_cancel (handle->sched,
 363                                head->timeout_task);
 364       head->timeout_task = GNUNET_SCHEDULER_NO_TASK;
 365     }
 366   if (NULL != head->cont)
 367     {
 368       GNUNET_SCHEDULER_add_now (handle->sched,
 369                                 head->cont,
 370                                 head->cont_cls);
 371       head->cont = NULL;
 372       head->cont_cls = NULL;
 373     }
 374   head->in_pending_queue = GNUNET_NO;
 375   if (GNUNET_YES == head->free_on_send)
 376     GNUNET_free (head);
 377   process_pending_messages (handle);
 378   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 379               "Forwarded request of %u bytes to DHT service\n",
 380               (unsigned int) tsize);
 381   return tsize;
 382 }
 383
 384
 385
 386
 387 /**
 388  * Process a given reply that might match the given
 389  * request.
 390  */
 391 static int
 392 process_reply (void *cls,
 393                const GNUNET_HashCode *key,
 394                void *value)
 395 {
 396   const struct GNUNET_DHT_RouteResultMessage *dht_msg = cls;
 397   struct GNUNET_DHT_RouteHandle *rh = value;
 398   const struct GNUNET_MessageHeader *enc_msg;
 399   size_t enc_size;
 400   uint64_t uid;
 401   const struct GNUNET_PeerIdentity *const*get_path;
 402   const struct GNUNET_PeerIdentity *const*put_path;
 403
 404   uid = GNUNET_ntohll (dht_msg->unique_id);
 405   if (uid != rh->uid)
 406     {
 407       GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 408                   "Reply UID did not match request UID\n");
 409       return GNUNET_YES;
 410     }
 411   enc_size = ntohs (dht_msg->header.size) - sizeof (struct GNUNET_DHT_RouteResultMessage);
 412   if (enc_size < sizeof (struct GNUNET_MessageHeader))
 413     {
 414       GNUNET_break (0);
 415       return GNUNET_NO;
 416     }
 417   enc_msg = (const struct GNUNET_MessageHeader *) &dht_msg[1];
 418   if (enc_size != ntohs (enc_msg->size))
 419     {
 420       GNUNET_break (0);
 421       return GNUNET_NO;
 422     }
 423   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 424               "Processing reply.\n");
 425   get_path = NULL; // FIXME: parse path info!
 426   put_path = NULL; // FIXME: parse path info!
 427   rh->iter (rh->iter_cls,
 428             &rh->key,
 429             get_path,
 430             put_path,
 431             enc_msg);
 432   return GNUNET_YES;
 433 }
 434
 435
 436 /**
 437  * Handler for messages received from the DHT service
 438  * a demultiplexer which handles numerous message types
 439  *
 440  * @param cls the 'struct GNUNET_DHT_Handle'
 441  * @param msg the incoming message
 442  */
 443 static void
 444 service_message_handler (void *cls,
 445                          const struct GNUNET_MessageHeader *msg)
 446 {
 447   struct GNUNET_DHT_Handle *handle = cls;
 448   const struct GNUNET_DHT_RouteResultMessage *dht_msg;
 449
 450   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 451               "%s called\n",
 452               __FUNCTION__);
 453   if (msg == NULL)
 454     {
 455       GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 456                   "Error receiving data from DHT service, reconnecting\n");
 457       reconnect (handle);
 458       return;
 459     }
 460   if (ntohs (msg->type) != GNUNET_MESSAGE_TYPE_DHT_LOCAL_ROUTE_RESULT)
 461     {
 462       GNUNET_break (0);
 463       reconnect (handle);
 464       return;
 465     }
 466   if (ntohs (msg->size) < sizeof (struct GNUNET_DHT_RouteResultMessage))
 467     {
 468       GNUNET_break (0);
 469       reconnect (handle);
 470       return;
 471     }
 472   dht_msg = (const struct GNUNET_DHT_RouteResultMessage *) msg;
 473   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 474               "Comparing reply `%s' against %u pending requests.\n",
 475               GNUNET_h2s (&dht_msg->key),
 476               GNUNET_CONTAINER_multihashmap_size (handle->active_requests));
 477   GNUNET_CONTAINER_multihashmap_get_multiple (handle->active_requests,
 478                                               &dht_msg->key,
 479                                               &process_reply,
 480                                               (void*) dht_msg);
 481   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 482               "Continuing to process replies from DHT\n");
 483   GNUNET_CLIENT_receive (handle->client,
 484                          &service_message_handler,
 485                          handle, GNUNET_TIME_UNIT_FOREVER_REL);
 486
 487 }
 488
 489
 490 /**
 491  * Initialize the connection with the DHT service.
 492  *
 493  * @param sched scheduler to use
 494  * @param cfg configuration to use
 495  * @param ht_len size of the internal hash table to use for
 496  *               processing multiple GET/FIND requests in parallel
 497  *
 498  * @return handle to the DHT service, or NULL on error
 499  */
 500 struct GNUNET_DHT_Handle *
 501 GNUNET_DHT_connect (struct GNUNET_SCHEDULER_Handle *sched,
 502                     const struct GNUNET_CONFIGURATION_Handle *cfg,
 503                     unsigned int ht_len)
 504 {
 505   struct GNUNET_DHT_Handle *handle;
 506
 507   handle = GNUNET_malloc (sizeof (struct GNUNET_DHT_Handle));
 508   handle->cfg = cfg;
 509   handle->sched = sched;
 510   handle->uid_gen = GNUNET_CRYPTO_random_u64(GNUNET_CRYPTO_QUALITY_WEAK, UINT64_MAX);
 511   handle->active_requests = GNUNET_CONTAINER_multihashmap_create (ht_len);
 512   if (GNUNET_NO == try_connect (handle))
 513     {
 514       GNUNET_DHT_disconnect (handle);
 515       return NULL;
 516     }
 517   return handle;
 518 }
 519
 520
 521 /**
 522  * Shutdown connection with the DHT service.
 523  *
 524  * @param handle handle of the DHT connection to stop
 525  */
 526 void
 527 GNUNET_DHT_disconnect (struct GNUNET_DHT_Handle *handle)
 528 {
 529   struct PendingMessage *pm;
 530
 531   GNUNET_assert (0 == GNUNET_CONTAINER_multihashmap_size(handle->active_requests));
 532   if (handle->th != NULL)
 533     {
 534       GNUNET_CLIENT_notify_transmit_ready_cancel (handle->th);
 535       handle->th = NULL;
 536     }
 537   while (NULL != (pm = handle->pending_head))
 538     {
 539       GNUNET_CONTAINER_DLL_remove (handle->pending_head,
 540                                    handle->pending_tail,
 541                                    pm);
 542       GNUNET_assert (GNUNET_YES == pm->free_on_send);
 543       if (GNUNET_SCHEDULER_NO_TASK != pm->timeout_task)
 544         GNUNET_SCHEDULER_cancel (handle->sched,
 545                                  pm->timeout_task);
 546       if (NULL != pm->cont)
 547         GNUNET_SCHEDULER_add_continuation (handle->sched,
 548                                            pm->cont,
 549                                            pm->cont_cls,
 550                                            GNUNET_SCHEDULER_REASON_TIMEOUT);
 551       pm->in_pending_queue = GNUNET_NO;
 552       GNUNET_free (pm);
 553     }
 554   if (handle->client != NULL)
 555     {
 556       GNUNET_CLIENT_disconnect (handle->client, GNUNET_YES);
 557       handle->client = NULL;
 558     }
 559   GNUNET_CONTAINER_multihashmap_destroy(handle->active_requests);
 560   GNUNET_free (handle);
 561 }
 562
 563
 564
 565
 566 /* ***** Special low-level API providing generic routeing abstraction ***** */
 567
 568
 569 /**
 570  * Timeout for the transmission of a fire&forget-request.  Clean it up.
 571  *
 572  * @param cls the 'struct PendingMessage'
 573  * @param tc scheduler context
 574  */
 575 static void
 576 timeout_route_request (void *cls,
 577                        const struct GNUNET_SCHEDULER_TaskContext *tc)
 578 {
 579   struct PendingMessage *pending = cls;
 580   struct GNUNET_DHT_Handle *handle;
 581
 582   if (pending->free_on_send != GNUNET_YES)
 583     {
 584       /* timeouts should only apply to fire & forget requests! */
 585       GNUNET_break (0);
 586       return;
 587     }
 588   handle = pending->handle;
 589   GNUNET_CONTAINER_DLL_remove (handle->pending_head,
 590                                handle->pending_tail,
 591                                pending);
 592   if (pending->cont != NULL)
 593     pending->cont (pending->cont_cls,
 594                    tc);
 595   GNUNET_free (pending);
 596 }
 597
 598
 599 /**
 600  * Initiate a generic DHT route operation.
 601  *
 602  * @param handle handle to the DHT service
 603  * @param key the key to look up
 604  * @param desired_replication_level how many peers should ultimately receive
 605  *                this message (advisory only, target may be too high for the
 606  *                given DHT or not hit exactly).
 607  * @param options options for routing
 608  * @param enc send the encapsulated message to a peer close to the key
 609  * @param iter function to call on each result, NULL if no replies are expected
 610  * @param iter_cls closure for iter
 611  * @param timeout when to abort with an error if we fail to get
 612  *                a confirmation for the request (when necessary) or how long
 613  *                to wait for tramission to the service; only applies
 614  *                if 'iter' is NULL
 615  * @param cont continuation to call when the request has been transmitted
 616  *             the first time to the service
 617  * @param cont_cls closure for cont
 618  * @return handle to stop the request, NULL if the request is "fire and forget"
 619  */
 620 struct GNUNET_DHT_RouteHandle *
 621 GNUNET_DHT_route_start (struct GNUNET_DHT_Handle *handle,
 622                         const GNUNET_HashCode *key,
 623                         uint32_t desired_replication_level,
 624                         enum GNUNET_DHT_RouteOption options,
 625                         const struct GNUNET_MessageHeader *enc,
 626                         struct GNUNET_TIME_Relative timeout,
 627                         GNUNET_DHT_ReplyProcessor iter,
 628                         void *iter_cls,
 629                         GNUNET_SCHEDULER_Task cont,
 630                         void *cont_cls)
 631 {
 632   struct PendingMessage *pending;
 633   struct GNUNET_DHT_RouteMessage *message;
 634   struct GNUNET_DHT_RouteHandle *route_handle;
 635   uint16_t msize;
 636   uint16_t esize;
 637
 638   esize = ntohs (enc->size);
 639   if (sizeof (struct GNUNET_DHT_RouteMessage) + esize >= GNUNET_SERVER_MAX_MESSAGE_SIZE)
 640     {
 641       GNUNET_break (0);
 642       return NULL;
 643     }
 644   msize = sizeof (struct GNUNET_DHT_RouteMessage) + esize;
 645   pending = GNUNET_malloc (sizeof (struct PendingMessage) + msize);
 646   message = (struct GNUNET_DHT_RouteMessage*) &pending[1];
 647   pending->msg = &message->header;
 648   pending->handle = handle;
 649   pending->cont = cont;
 650   pending->cont_cls = cont_cls;
 651
 652   message->header.size = htons (msize);
 653   message->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_LOCAL_ROUTE);
 654   message->key = *key;
 655   message->options = htonl ((uint32_t) options);
 656   message->desired_replication_level = htonl (desired_replication_level);
 657   memcpy (&message[1], enc, esize);
 658   if (iter != NULL)
 659     {
 660       route_handle = GNUNET_malloc (sizeof (struct GNUNET_DHT_RouteHandle));
 661       route_handle->key = *key;
 662       route_handle->iter = iter;
 663       route_handle->iter_cls = iter_cls;
 664       route_handle->dht_handle = handle;
 665       route_handle->uid = handle->uid_gen++;
 666       route_handle->message = pending;
 667       message->unique_id = GNUNET_htonll (route_handle->uid);
 668       GNUNET_CONTAINER_multihashmap_put (handle->active_requests,
 669                                          key,
 670                                          route_handle,
 671                                          GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE);
 672     }
 673   else
 674     {
 675       route_handle = NULL;
 676       pending->free_on_send = GNUNET_YES;
 677       pending->timeout_task = GNUNET_SCHEDULER_add_delayed (handle->sched,
 678                                                             timeout,
 679                                                             &timeout_route_request,
 680                                                             pending);
 681     }
 682   GNUNET_CONTAINER_DLL_insert (handle->pending_head,
 683                                handle->pending_tail,
 684                                pending);
 685   pending->in_pending_queue = GNUNET_YES;
 686   process_pending_messages (handle);
 687   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 688               "DHT route start request processed, returning %p\n",
 689               route_handle);
 690   return route_handle;
 691 }
 692
 693
 694 /**
 695  * Stop a previously issued routing request
 696  *
 697  * @param route_handle handle to the request to stop
 698  */
 699 void
 700 GNUNET_DHT_route_stop (struct GNUNET_DHT_RouteHandle *route_handle)
 701 {
 702   struct GNUNET_DHT_Handle *handle;
 703   struct PendingMessage *pending;
 704   struct GNUNET_DHT_StopMessage *message;
 705   size_t msize;
 706
 707   handle = route_handle->dht_handle;
 708   if (GNUNET_NO == route_handle->message->in_pending_queue)
 709     {
 710       /* need to send stop message */
 711       msize = sizeof (struct GNUNET_DHT_StopMessage);
 712       pending = GNUNET_malloc (sizeof (struct PendingMessage) +
 713                                msize);
 714       message = (struct GNUNET_DHT_StopMessage*) &pending[1];
 715       pending->msg = &message->header;
 716       message->header.size = htons (msize);
 717       message->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_LOCAL_ROUTE_STOP);
 718       message->unique_id = GNUNET_htonll (route_handle->uid);
 719       message->key = route_handle->key;
 720       pending->handle = handle;
 721       pending->free_on_send = GNUNET_YES;
 722       pending->in_pending_queue = GNUNET_YES;
 723       GNUNET_CONTAINER_DLL_insert (handle->pending_head,
 724                                    handle->pending_tail,
 725                                    pending);
 726       process_pending_messages (handle);
 727     }
 728   else
 729     {
 730       /* simply remove pending request from message queue before
 731          transmission, no need to transmit STOP request! */
 732       GNUNET_CONTAINER_DLL_remove (handle->pending_head,
 733                                    handle->pending_tail,
 734                                    route_handle->message);
 735     }
 736   GNUNET_assert (GNUNET_YES ==
 737                  GNUNET_CONTAINER_multihashmap_remove (route_handle->dht_handle->active_requests,
 738                                                        &route_handle->key,
 739                                                        route_handle));
 740   GNUNET_free(route_handle->message);
 741   GNUNET_free(route_handle);
 742   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 743               "DHT route stop request processed\n");
 744 }
 745
 746
 747
 748 /* ***** Special API for controlling DHT routing maintenance ******* */
 749
 750
 751 /**
 752  * Send a control message to the DHT.
 753  *
 754  * @param handle handle to the DHT service
 755  * @param command command
 756  * @param variable variable to the command
 757  * @param cont continuation to call when done (transmitting request to service)
 758  * @param cont_cls closure for cont
 759  */
 760 static void
 761 send_control_message (struct GNUNET_DHT_Handle *handle,
 762                       uint16_t command,
 763                       uint16_t variable,
 764                       GNUNET_SCHEDULER_Task cont,
 765                       void *cont_cls)
 766 {
 767   struct GNUNET_DHT_ControlMessage *msg;
 768   struct PendingMessage *pending;
 769
 770   pending = GNUNET_malloc (sizeof (struct PendingMessage) +
 771                            sizeof(struct GNUNET_DHT_ControlMessage));
 772   msg = (struct GNUNET_DHT_ControlMessage*) &pending[1];
 773   pending->msg = &msg->header;
 774   msg->header.size = htons (sizeof(struct GNUNET_DHT_ControlMessage));
 775   msg->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_CONTROL);
 776   msg->command = htons (command);
 777   msg->variable = htons (variable);
 778   pending->free_on_send = GNUNET_YES;
 779   pending->cont = cont;
 780   pending->cont_cls = cont_cls;
 781   pending->in_pending_queue = GNUNET_YES;
 782   GNUNET_CONTAINER_DLL_insert (handle->pending_head,
 783                                handle->pending_tail,
 784                                pending);
 785   process_pending_messages (handle);
 786 }
 787
 788
 789 /**
 790  * Send a message to the DHT telling it to issue a single find
 791  * peer request using the peers unique identifier as key.  This
 792  * is used to fill the routing table, and is normally controlled
 793  * by the DHT itself.  However, for testing and perhaps more
 794  * close control over the DHT, this can be explicitly managed.
 795  *
 796  * @param handle handle to the DHT service
 797  * @param cont continuation to call when done (transmitting request to service)
 798  * @param cont_cls closure for cont
 799  */
 800 void
 801 GNUNET_DHT_find_peers (struct GNUNET_DHT_Handle *handle,
 802                        GNUNET_SCHEDULER_Task cont,
 803                        void *cont_cls)
 804 {
 805   send_control_message (handle,
 806                         GNUNET_MESSAGE_TYPE_DHT_FIND_PEER, 0,
 807                         cont, cont_cls);
 808 }
 809
 810
 811
 812 #if HAVE_MALICIOUS
 813
 814 /**
 815  * Send a message to the DHT telling it to start issuing random GET
 816  * requests every 'frequency' milliseconds.
 817  *
 818  * @param handle handle to the DHT service
 819  * @param frequency delay between sending malicious messages
 820  */
 821 void
 822 GNUNET_DHT_set_malicious_getter (struct GNUNET_DHT_Handle *handle,
 823                                  struct GNUNET_TIME_Relative frequency)
 824 {
 825   if (frequency.value > UINT16_MAX)
 826     {
 827       GNUNET_break (0);
 828       return;
 829     }
 830   send_control_message (handle,
 831                         GNUNET_MESSAGE_TYPE_DHT_MALICIOUS_GET, frequency.value,
 832                         NULL, NULL);
 833 }
 834
 835 /**
 836  * Send a message to the DHT telling it to start issuing random PUT
 837  * requests every 'frequency' milliseconds.
 838  *
 839  * @param handle handle to the DHT service
 840  * @param frequency delay between sending malicious messages
 841  */
 842 void
 843 GNUNET_DHT_set_malicious_putter (struct GNUNET_DHT_Handle *handle,
 844                                  struct GNUNET_TIME_Relative frequency)
 845 {
 846   if (frequency.value > UINT16_MAX)
 847     {
 848       GNUNET_break (0);
 849       return;
 850     }
 851   send_control_message (handle,
 852                         GNUNET_MESSAGE_TYPE_DHT_MALICIOUS_PUT, frequency.value,
 853                         NULL, NULL);
 854 }
 855
 856
 857 /**
 858  * Send a message to the DHT telling it to start dropping
 859  * all requests received.
 860  *
 861  * @param handle handle to the DHT service
 862  */
 863 void
 864 GNUNET_DHT_set_malicious_dropper (struct GNUNET_DHT_Handle *handle)
 865 {
 866   send_control_message (handle,
 867                         GNUNET_MESSAGE_TYPE_DHT_MALICIOUS_DROP, 0,
 868                         NULL, NULL);
 869 }
 870
 871 #endif
 872
 873 /* end of dht_api.c */