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 **get_path;
 402   const struct GNUNET_PeerIdentity **put_path;
 403   const struct GNUNET_PeerIdentity *pos;
 404   uint16_t gpl;
 405   uint16_t ppl;
 406   unsigned int i;
 407
 408   uid = GNUNET_ntohll (dht_msg->unique_id);
 409   if (uid != rh->uid)
 410     {
 411       GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 412                   "Reply UID did not match request UID\n");
 413       return GNUNET_YES;
 414     }
 415   enc_size = ntohs (dht_msg->header.size) - sizeof (struct GNUNET_DHT_RouteResultMessage);
 416   if (enc_size < sizeof (struct GNUNET_MessageHeader))
 417     {
 418       GNUNET_break (0);
 419       return GNUNET_NO;
 420     }
 421   pos = (const struct GNUNET_PeerIdentity *) &dht_msg[1];
 422   ppl = ntohs (dht_msg->put_path_length);
 423   gpl = ntohs (dht_msg->get_path_length);
 424   if ( (ppl + gpl) * sizeof (struct GNUNET_PeerIdentity) > enc_size)
 425     {
 426       GNUNET_break (0);
 427       return GNUNET_NO;
 428     }
 429   if (ppl > 0)
 430     {
 431       put_path = GNUNET_malloc ((ppl+1) * sizeof (struct GNUNET_PeerIdentity*));
 432       for (i=0;i<ppl;i++)
 433         {
 434           put_path[i] = pos;
 435           pos++;
 436         }
 437       put_path[ppl] = NULL;
 438     }
 439   else
 440     put_path = NULL;
 441   if (gpl > 0)
 442     {
 443       get_path = GNUNET_malloc ((gpl+1) * sizeof (struct GNUNET_PeerIdentity*));
 444       for (i=0;i<gpl;i++)
 445         {
 446           get_path[i] = pos;
 447           pos++;
 448         }
 449       get_path[gpl] = NULL;
 450     }
 451   else
 452     get_path = NULL;
 453   enc_size -= (ppl + gpl) * sizeof (struct GNUNET_PeerIdentity);
 454   enc_msg = (const struct GNUNET_MessageHeader *) pos;
 455   if (enc_size != ntohs (enc_msg->size))
 456     {
 457       GNUNET_break (0);
 458       GNUNET_free_non_null (get_path);
 459       GNUNET_free_non_null (put_path);
 460       return GNUNET_NO;
 461     }
 462   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 463               "Processing reply.\n");
 464   rh->iter (rh->iter_cls,
 465             &rh->key,
 466             get_path,
 467             put_path,
 468             enc_msg);
 469   GNUNET_free_non_null (get_path);
 470   GNUNET_free_non_null (put_path);
 471   return GNUNET_YES;
 472 }
 473
 474
 475 /**
 476  * Handler for messages received from the DHT service
 477  * a demultiplexer which handles numerous message types
 478  *
 479  * @param cls the 'struct GNUNET_DHT_Handle'
 480  * @param msg the incoming message
 481  */
 482 static void
 483 service_message_handler (void *cls,
 484                          const struct GNUNET_MessageHeader *msg)
 485 {
 486   struct GNUNET_DHT_Handle *handle = cls;
 487   const struct GNUNET_DHT_RouteResultMessage *dht_msg;
 488
 489   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 490               "%s called\n",
 491               __FUNCTION__);
 492   if (msg == NULL)
 493     {
 494       GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 495                   "Error receiving data from DHT service, reconnecting\n");
 496       reconnect (handle);
 497       return;
 498     }
 499   if (ntohs (msg->type) != GNUNET_MESSAGE_TYPE_DHT_LOCAL_ROUTE_RESULT)
 500     {
 501       GNUNET_break (0);
 502       reconnect (handle);
 503       return;
 504     }
 505   if (ntohs (msg->size) < sizeof (struct GNUNET_DHT_RouteResultMessage))
 506     {
 507       GNUNET_break (0);
 508       reconnect (handle);
 509       return;
 510     }
 511   dht_msg = (const struct GNUNET_DHT_RouteResultMessage *) msg;
 512   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 513               "Comparing reply `%s' against %u pending requests.\n",
 514               GNUNET_h2s (&dht_msg->key),
 515               GNUNET_CONTAINER_multihashmap_size (handle->active_requests));
 516   GNUNET_CONTAINER_multihashmap_get_multiple (handle->active_requests,
 517                                               &dht_msg->key,
 518                                               &process_reply,
 519                                               (void*) dht_msg);
 520   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 521               "Continuing to process replies from DHT\n");
 522   GNUNET_CLIENT_receive (handle->client,
 523                          &service_message_handler,
 524                          handle, GNUNET_TIME_UNIT_FOREVER_REL);
 525
 526 }
 527
 528
 529 /**
 530  * Initialize the connection with the DHT service.
 531  *
 532  * @param sched scheduler to use
 533  * @param cfg configuration to use
 534  * @param ht_len size of the internal hash table to use for
 535  *               processing multiple GET/FIND requests in parallel
 536  *
 537  * @return handle to the DHT service, or NULL on error
 538  */
 539 struct GNUNET_DHT_Handle *
 540 GNUNET_DHT_connect (struct GNUNET_SCHEDULER_Handle *sched,
 541                     const struct GNUNET_CONFIGURATION_Handle *cfg,
 542                     unsigned int ht_len)
 543 {
 544   struct GNUNET_DHT_Handle *handle;
 545
 546   handle = GNUNET_malloc (sizeof (struct GNUNET_DHT_Handle));
 547   handle->cfg = cfg;
 548   handle->sched = sched;
 549   handle->uid_gen = GNUNET_CRYPTO_random_u64(GNUNET_CRYPTO_QUALITY_WEAK, UINT64_MAX);
 550   handle->active_requests = GNUNET_CONTAINER_multihashmap_create (ht_len);
 551   if (GNUNET_NO == try_connect (handle))
 552     {
 553       GNUNET_DHT_disconnect (handle);
 554       return NULL;
 555     }
 556   return handle;
 557 }
 558
 559
 560 /**
 561  * Shutdown connection with the DHT service.
 562  *
 563  * @param handle handle of the DHT connection to stop
 564  */
 565 void
 566 GNUNET_DHT_disconnect (struct GNUNET_DHT_Handle *handle)
 567 {
 568   struct PendingMessage *pm;
 569
 570   GNUNET_assert (0 == GNUNET_CONTAINER_multihashmap_size(handle->active_requests));
 571   if (handle->th != NULL)
 572     {
 573       GNUNET_CLIENT_notify_transmit_ready_cancel (handle->th);
 574       handle->th = NULL;
 575     }
 576   while (NULL != (pm = handle->pending_head))
 577     {
 578       GNUNET_CONTAINER_DLL_remove (handle->pending_head,
 579                                    handle->pending_tail,
 580                                    pm);
 581       GNUNET_assert (GNUNET_YES == pm->free_on_send);
 582       if (GNUNET_SCHEDULER_NO_TASK != pm->timeout_task)
 583         GNUNET_SCHEDULER_cancel (handle->sched,
 584                                  pm->timeout_task);
 585       if (NULL != pm->cont)
 586         GNUNET_SCHEDULER_add_continuation (handle->sched,
 587                                            pm->cont,
 588                                            pm->cont_cls,
 589                                            GNUNET_SCHEDULER_REASON_TIMEOUT);
 590       pm->in_pending_queue = GNUNET_NO;
 591       GNUNET_free (pm);
 592     }
 593   if (handle->client != NULL)
 594     {
 595       GNUNET_CLIENT_disconnect (handle->client, GNUNET_YES);
 596       handle->client = NULL;
 597     }
 598   GNUNET_CONTAINER_multihashmap_destroy(handle->active_requests);
 599   GNUNET_free (handle);
 600 }
 601
 602
 603
 604
 605 /* ***** Special low-level API providing generic routeing abstraction ***** */
 606
 607
 608 /**
 609  * Timeout for the transmission of a fire&forget-request.  Clean it up.
 610  *
 611  * @param cls the 'struct PendingMessage'
 612  * @param tc scheduler context
 613  */
 614 static void
 615 timeout_route_request (void *cls,
 616                        const struct GNUNET_SCHEDULER_TaskContext *tc)
 617 {
 618   struct PendingMessage *pending = cls;
 619   struct GNUNET_DHT_Handle *handle;
 620
 621   if (pending->free_on_send != GNUNET_YES)
 622     {
 623       /* timeouts should only apply to fire & forget requests! */
 624       GNUNET_break (0);
 625       return;
 626     }
 627   handle = pending->handle;
 628   GNUNET_CONTAINER_DLL_remove (handle->pending_head,
 629                                handle->pending_tail,
 630                                pending);
 631   if (pending->cont != NULL)
 632     pending->cont (pending->cont_cls,
 633                    tc);
 634   GNUNET_free (pending);
 635 }
 636
 637
 638 /**
 639  * Initiate a generic DHT route operation.
 640  *
 641  * @param handle handle to the DHT service
 642  * @param key the key to look up
 643  * @param desired_replication_level how many peers should ultimately receive
 644  *                this message (advisory only, target may be too high for the
 645  *                given DHT or not hit exactly).
 646  * @param options options for routing
 647  * @param enc send the encapsulated message to a peer close to the key
 648  * @param iter function to call on each result, NULL if no replies are expected
 649  * @param iter_cls closure for iter
 650  * @param timeout when to abort with an error if we fail to get
 651  *                a confirmation for the request (when necessary) or how long
 652  *                to wait for tramission to the service; only applies
 653  *                if 'iter' is NULL
 654  * @param cont continuation to call when the request has been transmitted
 655  *             the first time to the service
 656  * @param cont_cls closure for cont
 657  * @return handle to stop the request, NULL if the request is "fire and forget"
 658  */
 659 struct GNUNET_DHT_RouteHandle *
 660 GNUNET_DHT_route_start (struct GNUNET_DHT_Handle *handle,
 661                         const GNUNET_HashCode *key,
 662                         uint32_t desired_replication_level,
 663                         enum GNUNET_DHT_RouteOption options,
 664                         const struct GNUNET_MessageHeader *enc,
 665                         struct GNUNET_TIME_Relative timeout,
 666                         GNUNET_DHT_ReplyProcessor iter,
 667                         void *iter_cls,
 668                         GNUNET_SCHEDULER_Task cont,
 669                         void *cont_cls)
 670 {
 671   struct PendingMessage *pending;
 672   struct GNUNET_DHT_RouteMessage *message;
 673   struct GNUNET_DHT_RouteHandle *route_handle;
 674   uint16_t msize;
 675   uint16_t esize;
 676
 677   esize = ntohs (enc->size);
 678   if (sizeof (struct GNUNET_DHT_RouteMessage) + esize >= GNUNET_SERVER_MAX_MESSAGE_SIZE)
 679     {
 680       GNUNET_break (0);
 681       return NULL;
 682     }
 683   msize = sizeof (struct GNUNET_DHT_RouteMessage) + esize;
 684   pending = GNUNET_malloc (sizeof (struct PendingMessage) + msize);
 685   message = (struct GNUNET_DHT_RouteMessage*) &pending[1];
 686   pending->msg = &message->header;
 687   pending->handle = handle;
 688   pending->cont = cont;
 689   pending->cont_cls = cont_cls;
 690
 691   message->header.size = htons (msize);
 692   message->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_LOCAL_ROUTE);
 693   message->key = *key;
 694   message->options = htonl ((uint32_t) options);
 695   message->desired_replication_level = htonl (desired_replication_level);
 696   memcpy (&message[1], enc, esize);
 697   if (iter != NULL)
 698     {
 699       route_handle = GNUNET_malloc (sizeof (struct GNUNET_DHT_RouteHandle));
 700       route_handle->key = *key;
 701       route_handle->iter = iter;
 702       route_handle->iter_cls = iter_cls;
 703       route_handle->dht_handle = handle;
 704       route_handle->uid = handle->uid_gen++;
 705       route_handle->message = pending;
 706       message->unique_id = GNUNET_htonll (route_handle->uid);
 707       GNUNET_CONTAINER_multihashmap_put (handle->active_requests,
 708                                          key,
 709                                          route_handle,
 710                                          GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE);
 711     }
 712   else
 713     {
 714       route_handle = NULL;
 715       pending->free_on_send = GNUNET_YES;
 716       pending->timeout_task = GNUNET_SCHEDULER_add_delayed (handle->sched,
 717                                                             timeout,
 718                                                             &timeout_route_request,
 719                                                             pending);
 720     }
 721   GNUNET_CONTAINER_DLL_insert (handle->pending_head,
 722                                handle->pending_tail,
 723                                pending);
 724   pending->in_pending_queue = GNUNET_YES;
 725   process_pending_messages (handle);
 726   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 727               "DHT route start request processed, returning %p\n",
 728               route_handle);
 729   return route_handle;
 730 }
 731
 732
 733 /**
 734  * Stop a previously issued routing request
 735  *
 736  * @param route_handle handle to the request to stop
 737  */
 738 void
 739 GNUNET_DHT_route_stop (struct GNUNET_DHT_RouteHandle *route_handle)
 740 {
 741   struct GNUNET_DHT_Handle *handle;
 742   struct PendingMessage *pending;
 743   struct GNUNET_DHT_StopMessage *message;
 744   size_t msize;
 745
 746   handle = route_handle->dht_handle;
 747   if (GNUNET_NO == route_handle->message->in_pending_queue)
 748     {
 749       /* need to send stop message */
 750       msize = sizeof (struct GNUNET_DHT_StopMessage);
 751       pending = GNUNET_malloc (sizeof (struct PendingMessage) +
 752                                msize);
 753       message = (struct GNUNET_DHT_StopMessage*) &pending[1];
 754       pending->msg = &message->header;
 755       message->header.size = htons (msize);
 756       message->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_LOCAL_ROUTE_STOP);
 757       message->unique_id = GNUNET_htonll (route_handle->uid);
 758       message->key = route_handle->key;
 759       pending->handle = handle;
 760       pending->free_on_send = GNUNET_YES;
 761       pending->in_pending_queue = GNUNET_YES;
 762       GNUNET_CONTAINER_DLL_insert (handle->pending_head,
 763                                    handle->pending_tail,
 764                                    pending);
 765       process_pending_messages (handle);
 766     }
 767   else
 768     {
 769       /* simply remove pending request from message queue before
 770          transmission, no need to transmit STOP request! */
 771       GNUNET_CONTAINER_DLL_remove (handle->pending_head,
 772                                    handle->pending_tail,
 773                                    route_handle->message);
 774     }
 775   GNUNET_assert (GNUNET_YES ==
 776                  GNUNET_CONTAINER_multihashmap_remove (route_handle->dht_handle->active_requests,
 777                                                        &route_handle->key,
 778                                                        route_handle));
 779   GNUNET_free(route_handle->message);
 780   GNUNET_free(route_handle);
 781   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 782               "DHT route stop request processed\n");
 783 }
 784
 785
 786
 787 /* ***** Special API for controlling DHT routing maintenance ******* */
 788
 789
 790 /**
 791  * Send a control message to the DHT.
 792  *
 793  * @param handle handle to the DHT service
 794  * @param command command
 795  * @param variable variable to the command
 796  * @param cont continuation to call when done (transmitting request to service)
 797  * @param cont_cls closure for cont
 798  */
 799 static void
 800 send_control_message (struct GNUNET_DHT_Handle *handle,
 801                       uint16_t command,
 802                       uint16_t variable,
 803                       GNUNET_SCHEDULER_Task cont,
 804                       void *cont_cls)
 805 {
 806   struct GNUNET_DHT_ControlMessage *msg;
 807   struct PendingMessage *pending;
 808
 809   pending = GNUNET_malloc (sizeof (struct PendingMessage) +
 810                            sizeof(struct GNUNET_DHT_ControlMessage));
 811   msg = (struct GNUNET_DHT_ControlMessage*) &pending[1];
 812   pending->msg = &msg->header;
 813   msg->header.size = htons (sizeof(struct GNUNET_DHT_ControlMessage));
 814   msg->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_CONTROL);
 815   msg->command = htons (command);
 816   msg->variable = htons (variable);
 817   pending->free_on_send = GNUNET_YES;
 818   pending->cont = cont;
 819   pending->cont_cls = cont_cls;
 820   pending->in_pending_queue = GNUNET_YES;
 821   GNUNET_CONTAINER_DLL_insert (handle->pending_head,
 822                                handle->pending_tail,
 823                                pending);
 824   process_pending_messages (handle);
 825 }
 826
 827
 828 /**
 829  * Send a message to the DHT telling it to issue a single find
 830  * peer request using the peers unique identifier as key.  This
 831  * is used to fill the routing table, and is normally controlled
 832  * by the DHT itself.  However, for testing and perhaps more
 833  * close control over the DHT, this can be explicitly managed.
 834  *
 835  * @param handle handle to the DHT service
 836  * @param cont continuation to call when done (transmitting request to service)
 837  * @param cont_cls closure for cont
 838  */
 839 void
 840 GNUNET_DHT_find_peers (struct GNUNET_DHT_Handle *handle,
 841                        GNUNET_SCHEDULER_Task cont,
 842                        void *cont_cls)
 843 {
 844   send_control_message (handle,
 845                         GNUNET_MESSAGE_TYPE_DHT_FIND_PEER, 0,
 846                         cont, cont_cls);
 847 }
 848
 849
 850
 851 #if HAVE_MALICIOUS
 852
 853 /**
 854  * Send a message to the DHT telling it to start issuing random GET
 855  * requests every 'frequency' milliseconds.
 856  *
 857  * @param handle handle to the DHT service
 858  * @param frequency delay between sending malicious messages
 859  */
 860 void
 861 GNUNET_DHT_set_malicious_getter (struct GNUNET_DHT_Handle *handle,
 862                                  struct GNUNET_TIME_Relative frequency)
 863 {
 864   if (frequency.value > UINT16_MAX)
 865     {
 866       GNUNET_break (0);
 867       return;
 868     }
 869   send_control_message (handle,
 870                         GNUNET_MESSAGE_TYPE_DHT_MALICIOUS_GET, frequency.value,
 871                         NULL, NULL);
 872 }
 873
 874 /**
 875  * Send a message to the DHT telling it to start issuing random PUT
 876  * requests every 'frequency' milliseconds.
 877  *
 878  * @param handle handle to the DHT service
 879  * @param frequency delay between sending malicious messages
 880  */
 881 void
 882 GNUNET_DHT_set_malicious_putter (struct GNUNET_DHT_Handle *handle,
 883                                  struct GNUNET_TIME_Relative frequency)
 884 {
 885   if (frequency.value > UINT16_MAX)
 886     {
 887       GNUNET_break (0);
 888       return;
 889     }
 890   send_control_message (handle,
 891                         GNUNET_MESSAGE_TYPE_DHT_MALICIOUS_PUT, frequency.value,
 892                         NULL, NULL);
 893 }
 894
 895
 896 /**
 897  * Send a message to the DHT telling it to start dropping
 898  * all requests received.
 899  *
 900  * @param handle handle to the DHT service
 901  */
 902 void
 903 GNUNET_DHT_set_malicious_dropper (struct GNUNET_DHT_Handle *handle)
 904 {
 905   send_control_message (handle,
 906                         GNUNET_MESSAGE_TYPE_DHT_MALICIOUS_DROP, 0,
 907                         NULL, NULL);
 908 }
 909
 910 #endif
 911
 912 /* end of dht_api.c */