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). FIXME: redundant!?
 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   /**
 154    * Configuration to use.
 155    */
 156   const struct GNUNET_CONFIGURATION_Handle *cfg;
 157
 158   /**
 159    * Socket (if available).
 160    */
 161   struct GNUNET_CLIENT_Connection *client;
 162
 163   /**
 164    * Currently pending transmission request (or NULL).
 165    */
 166   struct GNUNET_CLIENT_TransmitHandle *th;
 167
 168   /**
 169    * Head of linked list of messages we would like to transmit.
 170    */
 171   struct PendingMessage *pending_head;
 172
 173   /**
 174    * Tail of linked list of messages we would like to transmit.
 175    */
 176   struct PendingMessage *pending_tail;
 177
 178   /**
 179    * Hash map containing the current outstanding unique requests
 180    * (values are of type 'struct GNUNET_DHT_RouteHandle').
 181    */
 182   struct GNUNET_CONTAINER_MultiHashMap *active_requests;
 183
 184   /**
 185    * Task for trying to reconnect.
 186    */
 187   GNUNET_SCHEDULER_TaskIdentifier reconnect_task;
 188
 189   /**
 190    * How quickly should we retry?  Used for exponential back-off on
 191    * connect-errors.
 192    */
 193   struct GNUNET_TIME_Relative retry_time;
 194
 195   /**
 196    * Generator for unique ids.
 197    */
 198   uint64_t uid_gen;
 199
 200 };
 201
 202
 203 /**
 204  * Transmit the next pending message, called by notify_transmit_ready
 205  */
 206 static size_t
 207 transmit_pending (void *cls,
 208                   size_t size,
 209                   void *buf);
 210
 211
 212 /**
 213  * Handler for messages received from the DHT service
 214  * a demultiplexer which handles numerous message types
 215  *
 216  */
 217 static void
 218 service_message_handler (void *cls,
 219                          const struct GNUNET_MessageHeader *msg);
 220
 221
 222
 223
 224 /**
 225  * Try to (re)connect to the DHT service.
 226  *
 227  * @return GNUNET_YES on success, GNUNET_NO on failure.
 228  */
 229 static int
 230 try_connect (struct GNUNET_DHT_Handle *handle)
 231 {
 232   if (handle->client != NULL)
 233     return GNUNET_OK;
 234   handle->client = GNUNET_CLIENT_connect ("dht", handle->cfg);
 235   if (handle->client == NULL)
 236     {
 237       GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
 238                   _("Failed to connect to the DHT service!\n"));
 239       return GNUNET_NO;
 240     }
 241 #if DEBUG_DHT
 242   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 243               "Starting to process replies from DHT\n");
 244 #endif
 245   GNUNET_CLIENT_receive (handle->client,
 246                          &service_message_handler,
 247                          handle,
 248                          GNUNET_TIME_UNIT_FOREVER_REL);
 249   return GNUNET_YES;
 250 }
 251
 252
 253 /**
 254  * Add the request corresponding to the given route handle
 255  * to the pending queue (if it is not already in there).
 256  *
 257  * @param cls the 'struct GNUNET_DHT_Handle*'
 258  * @param key key for the request (not used)
 259  * @param value the 'struct GNUNET_DHT_RouteHandle*'
 260  * @return GNUNET_YES (always)
 261  */
 262 static int
 263 add_request_to_pending (void *cls,
 264                         const GNUNET_HashCode *key,
 265                         void *value)
 266 {
 267   struct GNUNET_DHT_Handle *handle = cls;
 268   struct GNUNET_DHT_RouteHandle *rh = value;
 269
 270   if (GNUNET_NO == rh->message->in_pending_queue)
 271     {
 272       GNUNET_CONTAINER_DLL_insert (handle->pending_head,
 273                                    handle->pending_tail,
 274                                    rh->message);
 275       rh->message->in_pending_queue = GNUNET_YES;
 276     }
 277   return GNUNET_YES;
 278 }
 279
 280
 281 /**
 282  * Try to send messages from list of messages to send
 283  * @param handle DHT_Handle
 284  */
 285 static void
 286 process_pending_messages (struct GNUNET_DHT_Handle *handle);
 287
 288
 289 /**
 290  * Try reconnecting to the dht service.
 291  *
 292  * @param cls GNUNET_DHT_Handle
 293  * @param tc scheduler context
 294  */
 295 static void
 296 try_reconnect (void *cls,
 297                const struct GNUNET_SCHEDULER_TaskContext *tc)
 298 {
 299   struct GNUNET_DHT_Handle *handle = cls;
 300
 301   handle->reconnect_task = GNUNET_SCHEDULER_NO_TASK;
 302   if (handle->retry_time.rel_value < GNUNET_CONSTANTS_SERVICE_RETRY.rel_value)
 303     handle->retry_time = GNUNET_CONSTANTS_SERVICE_RETRY;
 304   else
 305     handle->retry_time = GNUNET_TIME_relative_multiply (handle->retry_time, 2);
 306   if (handle->retry_time.rel_value > GNUNET_CONSTANTS_SERVICE_TIMEOUT.rel_value)
 307     handle->retry_time = GNUNET_CONSTANTS_SERVICE_TIMEOUT;
 308   handle->reconnect_task = GNUNET_SCHEDULER_NO_TASK;
 309   handle->client = GNUNET_CLIENT_connect ("dht", handle->cfg);
 310   if (handle->client == NULL)
 311     {
 312       GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 313                   "dht reconnect failed(!)\n");
 314       return;
 315     }
 316   GNUNET_CONTAINER_multihashmap_iterate (handle->active_requests,
 317                                          &add_request_to_pending,
 318                                          handle);
 319   process_pending_messages (handle);
 320 }
 321
 322
 323 /**
 324  * Try reconnecting to the DHT service.
 325  *
 326  * @param handle handle to dht to (possibly) disconnect and reconnect
 327  */
 328 static void
 329 do_disconnect (struct GNUNET_DHT_Handle *handle)
 330 {
 331   if (handle->client == NULL)
 332     return;
 333   GNUNET_assert(handle->reconnect_task == GNUNET_SCHEDULER_NO_TASK);
 334   GNUNET_CLIENT_disconnect (handle->client, GNUNET_NO);
 335   handle->client = NULL;
 336   handle->reconnect_task = GNUNET_SCHEDULER_add_delayed (handle->retry_time,
 337                                                          &try_reconnect,
 338                                                          handle);
 339 }
 340
 341
 342 /**
 343  * Try to send messages from list of messages to send
 344  */
 345 static void
 346 process_pending_messages (struct GNUNET_DHT_Handle *handle)
 347 {
 348   struct PendingMessage *head;
 349
 350   if (handle->client == NULL)
 351     {
 352       do_disconnect(handle);
 353       return;
 354     }
 355   if (handle->th != NULL)
 356     return;
 357   if (NULL == (head = handle->pending_head))
 358     return;
 359   handle->th = GNUNET_CLIENT_notify_transmit_ready (handle->client,
 360                                                     ntohs (head->msg->size),
 361                                                     GNUNET_TIME_UNIT_FOREVER_REL,
 362                                                     GNUNET_YES,
 363                                                     &transmit_pending,
 364                                                     handle);
 365   if (NULL == handle->th)
 366     {
 367       do_disconnect (handle);
 368       return;
 369     }
 370 }
 371
 372
 373 /**
 374  * Transmit the next pending message, called by notify_transmit_ready
 375  */
 376 static size_t
 377 transmit_pending (void *cls,
 378                   size_t size,
 379                   void *buf)
 380 {
 381   struct GNUNET_DHT_Handle *handle = cls;
 382   struct PendingMessage *head;
 383   size_t tsize;
 384
 385   handle->th = NULL;
 386   if (buf == NULL)
 387     {
 388       GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Transmission to DHT service failed!  Reconnecting!\n");
 389       do_disconnect (handle);
 390       return 0;
 391     }
 392   if (NULL == (head = handle->pending_head))
 393     return 0;
 394
 395   tsize = ntohs (head->msg->size);
 396   if (size < tsize)
 397     {
 398       process_pending_messages (handle);
 399       return 0;
 400     }
 401   memcpy (buf, head->msg, tsize);
 402   GNUNET_CONTAINER_DLL_remove (handle->pending_head,
 403                                handle->pending_tail,
 404                                head);
 405   if (head->timeout_task != GNUNET_SCHEDULER_NO_TASK)
 406     {
 407       GNUNET_SCHEDULER_cancel (head->timeout_task);
 408       head->timeout_task = GNUNET_SCHEDULER_NO_TASK;
 409     }
 410   if (NULL != head->cont)
 411     {
 412       GNUNET_SCHEDULER_add_continuation (head->cont,
 413                                          head->cont_cls,
 414                                          GNUNET_SCHEDULER_REASON_PREREQ_DONE);
 415       head->cont = NULL;
 416       head->cont_cls = NULL;
 417     }
 418   head->in_pending_queue = GNUNET_NO;
 419   if (GNUNET_YES == head->free_on_send)
 420     GNUNET_free (head);
 421   process_pending_messages (handle);
 422   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 423               "Forwarded request of %u bytes to DHT service\n",
 424               (unsigned int) tsize);
 425   return tsize;
 426 }
 427
 428
 429 /**
 430  * Process a given reply that might match the given
 431  * request.
 432  */
 433 static int
 434 process_reply (void *cls,
 435                const GNUNET_HashCode *key,
 436                void *value)
 437 {
 438   const struct GNUNET_DHT_RouteResultMessage *dht_msg = cls;
 439   struct GNUNET_DHT_RouteHandle *rh = value;
 440   const struct GNUNET_MessageHeader *enc_msg;
 441   size_t enc_size;
 442   uint64_t uid;
 443   const struct GNUNET_PeerIdentity **outgoing_path;
 444   const struct GNUNET_PeerIdentity *pos;
 445   uint32_t outgoing_path_length;
 446   unsigned int i;
 447   char *path_offset;
 448
 449   uid = GNUNET_ntohll (dht_msg->unique_id);
 450   if (uid != rh->uid)
 451     {
 452       GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 453                   "Reply UID did not match request UID\n");
 454       return GNUNET_YES;
 455     }
 456   enc_msg = (const struct GNUNET_MessageHeader *)&dht_msg[1];
 457   enc_size = ntohs (enc_msg->size);
 458   if (enc_size < sizeof (struct GNUNET_MessageHeader))
 459     {
 460       GNUNET_break (0);
 461       return GNUNET_NO;
 462     }
 463   path_offset = (char *)&dht_msg[1];
 464   path_offset += enc_size;
 465   pos = (const struct GNUNET_PeerIdentity *) path_offset;
 466   outgoing_path_length = ntohl (dht_msg->outgoing_path_length);
 467   if (outgoing_path_length * sizeof (struct GNUNET_PeerIdentity) > ntohs(dht_msg->header.size) - enc_size)
 468     {
 469       GNUNET_break (0);
 470       return GNUNET_NO;
 471     }
 472
 473   if (outgoing_path_length > 0)
 474     {
 475       outgoing_path = GNUNET_malloc ((outgoing_path_length + 1) * sizeof (struct GNUNET_PeerIdentity*));
 476       for (i = 0; i < outgoing_path_length; i++)
 477         {
 478           outgoing_path[i] = pos;
 479           pos++;
 480         }
 481       outgoing_path[outgoing_path_length] = NULL;
 482     }
 483   else
 484     outgoing_path = NULL;
 485
 486   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 487               "Processing reply.\n");
 488   rh->iter (rh->iter_cls,
 489             &rh->key,
 490             outgoing_path,
 491             enc_msg);
 492   GNUNET_free_non_null (outgoing_path);
 493   return GNUNET_YES;
 494 }
 495
 496
 497 /**
 498  * Handler for messages received from the DHT service
 499  * a demultiplexer which handles numerous message types
 500  *
 501  * @param cls the 'struct GNUNET_DHT_Handle'
 502  * @param msg the incoming message
 503  */
 504 static void
 505 service_message_handler (void *cls,
 506                          const struct GNUNET_MessageHeader *msg)
 507 {
 508   struct GNUNET_DHT_Handle *handle = cls;
 509   const struct GNUNET_DHT_RouteResultMessage *dht_msg;
 510
 511   if (msg == NULL)
 512     {
 513       GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 514                   "Error receiving data from DHT service, reconnecting\n");
 515       do_disconnect (handle);
 516       return;
 517     }
 518   if (ntohs (msg->type) != GNUNET_MESSAGE_TYPE_DHT_LOCAL_ROUTE_RESULT)
 519     {
 520       GNUNET_break (0);
 521       do_disconnect (handle);
 522       return;
 523     }
 524   if (ntohs (msg->size) < sizeof (struct GNUNET_DHT_RouteResultMessage))
 525     {
 526       GNUNET_break (0);
 527       do_disconnect (handle);
 528       return;
 529     }
 530   dht_msg = (const struct GNUNET_DHT_RouteResultMessage *) msg;
 531   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 532               "Comparing reply `%s' against %u pending requests.\n",
 533               GNUNET_h2s (&dht_msg->key),
 534               GNUNET_CONTAINER_multihashmap_size (handle->active_requests));
 535   GNUNET_CONTAINER_multihashmap_get_multiple (handle->active_requests,
 536                                               &dht_msg->key,
 537                                               &process_reply,
 538                                               (void*) dht_msg);
 539   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 540               "Continuing to process replies from DHT\n");
 541   GNUNET_CLIENT_receive (handle->client,
 542                          &service_message_handler,
 543                          handle, GNUNET_TIME_UNIT_FOREVER_REL);
 544
 545 }
 546
 547
 548 /**
 549  * Initialize the connection with the DHT service.
 550  *
 551  * @param cfg configuration to use
 552  * @param ht_len size of the internal hash table to use for
 553  *               processing multiple GET/FIND requests in parallel
 554  *
 555  * @return handle to the DHT service, or NULL on error
 556  */
 557 struct GNUNET_DHT_Handle *
 558 GNUNET_DHT_connect (const struct GNUNET_CONFIGURATION_Handle *cfg,
 559                     unsigned int ht_len)
 560 {
 561   struct GNUNET_DHT_Handle *handle;
 562
 563   handle = GNUNET_malloc (sizeof (struct GNUNET_DHT_Handle));
 564   handle->cfg = cfg;
 565   handle->uid_gen = GNUNET_CRYPTO_random_u64(GNUNET_CRYPTO_QUALITY_WEAK, UINT64_MAX);
 566   handle->active_requests = GNUNET_CONTAINER_multihashmap_create (ht_len);
 567   if (GNUNET_NO == try_connect (handle))
 568     {
 569       GNUNET_DHT_disconnect (handle);
 570       return NULL;
 571     }
 572   return handle;
 573 }
 574
 575
 576 /**
 577  * Shutdown connection with the DHT service.
 578  *
 579  * @param handle handle of the DHT connection to stop
 580  */
 581 void
 582 GNUNET_DHT_disconnect (struct GNUNET_DHT_Handle *handle)
 583 {
 584   struct PendingMessage *pm;
 585   GNUNET_assert(handle != NULL);
 586   GNUNET_assert (0 == GNUNET_CONTAINER_multihashmap_size(handle->active_requests));
 587   if (handle->th != NULL)
 588     {
 589       GNUNET_CLIENT_notify_transmit_ready_cancel (handle->th);
 590       handle->th = NULL;
 591     }
 592   while (NULL != (pm = handle->pending_head))
 593     {
 594       GNUNET_CONTAINER_DLL_remove (handle->pending_head,
 595                                    handle->pending_tail,
 596                                    pm);
 597       GNUNET_assert (GNUNET_YES == pm->free_on_send);
 598       if (GNUNET_SCHEDULER_NO_TASK != pm->timeout_task)
 599         GNUNET_SCHEDULER_cancel (pm->timeout_task);
 600       if (NULL != pm->cont)
 601         GNUNET_SCHEDULER_add_continuation (pm->cont,
 602                                            pm->cont_cls,
 603                                            GNUNET_SCHEDULER_REASON_TIMEOUT);
 604       pm->in_pending_queue = GNUNET_NO;
 605       GNUNET_free (pm);
 606     }
 607   if (handle->client != NULL)
 608     {
 609       GNUNET_CLIENT_disconnect (handle->client, GNUNET_YES);
 610       handle->client = NULL;
 611     }
 612   if (handle->reconnect_task != GNUNET_SCHEDULER_NO_TASK)
 613     GNUNET_SCHEDULER_cancel(handle->reconnect_task);
 614   GNUNET_CONTAINER_multihashmap_destroy(handle->active_requests);
 615   GNUNET_free (handle);
 616 }
 617
 618
 619
 620
 621 /* ***** Special low-level API providing generic routing abstraction ***** */
 622
 623
 624 /**
 625  * Timeout for the transmission of a fire&forget-request.  Clean it up.
 626  *
 627  * @param cls the 'struct PendingMessage'
 628  * @param tc scheduler context
 629  */
 630 static void
 631 timeout_route_request (void *cls,
 632                        const struct GNUNET_SCHEDULER_TaskContext *tc)
 633 {
 634   struct PendingMessage *pending = cls;
 635   struct GNUNET_DHT_Handle *handle;
 636
 637   if (pending->free_on_send != GNUNET_YES)
 638     {
 639       /* timeouts should only apply to fire & forget requests! */
 640       GNUNET_break (0);
 641       return;
 642     }
 643   handle = pending->handle;
 644   GNUNET_CONTAINER_DLL_remove (handle->pending_head,
 645                                handle->pending_tail,
 646                                pending);
 647   if (pending->cont != NULL)
 648     pending->cont (pending->cont_cls,
 649                    tc);
 650   GNUNET_free (pending);
 651 }
 652
 653
 654 /**
 655  * Initiate a generic DHT route operation.
 656  *
 657  * @param handle handle to the DHT service
 658  * @param key the key to look up
 659  * @param desired_replication_level how many peers should ultimately receive
 660  *                this message (advisory only, target may be too high for the
 661  *                given DHT or not hit exactly).
 662  * @param options options for routing
 663  * @param enc send the encapsulated message to a peer close to the key
 664  * @param iter function to call on each result, NULL if no replies are expected
 665  * @param iter_cls closure for iter
 666  * @param timeout when to abort with an error if we fail to get
 667  *                a confirmation for the request (when necessary) or how long
 668  *                to wait for tramission to the service; only applies
 669  *                if 'iter' is NULL
 670  * @param cont continuation to call when the request has been transmitted
 671  *             the first time to the service
 672  * @param cont_cls closure for cont
 673  * @return handle to stop the request, NULL if the request is "fire and forget"
 674  */
 675 struct GNUNET_DHT_RouteHandle *
 676 GNUNET_DHT_route_start (struct GNUNET_DHT_Handle *handle,
 677                         const GNUNET_HashCode *key,
 678                         uint32_t desired_replication_level,
 679                         enum GNUNET_DHT_RouteOption options,
 680                         const struct GNUNET_MessageHeader *enc,
 681                         struct GNUNET_TIME_Relative timeout,
 682                         GNUNET_DHT_ReplyProcessor iter,
 683                         void *iter_cls,
 684                         GNUNET_SCHEDULER_Task cont,
 685                         void *cont_cls)
 686 {
 687   struct PendingMessage *pending;
 688   struct GNUNET_DHT_RouteMessage *message;
 689   struct GNUNET_DHT_RouteHandle *route_handle;
 690   uint16_t msize;
 691   uint16_t esize;
 692
 693   esize = ntohs (enc->size);
 694   if (sizeof (struct GNUNET_DHT_RouteMessage) + esize >= GNUNET_SERVER_MAX_MESSAGE_SIZE)
 695     {
 696       GNUNET_break (0);
 697       return NULL;
 698     }
 699   msize = sizeof (struct GNUNET_DHT_RouteMessage) + esize;
 700   pending = GNUNET_malloc (sizeof (struct PendingMessage) + msize);
 701   message = (struct GNUNET_DHT_RouteMessage*) &pending[1];
 702   pending->msg = &message->header;
 703   pending->handle = handle;
 704   pending->cont = cont;
 705   pending->cont_cls = cont_cls;
 706
 707   message->header.size = htons (msize);
 708   message->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_LOCAL_ROUTE);
 709   message->options = htonl ((uint32_t) options);
 710   message->desired_replication_level = htonl (desired_replication_level);
 711   message->reserved = 0;
 712   message->key = *key;
 713   handle->uid_gen++;
 714   message->unique_id = GNUNET_htonll (handle->uid_gen);
 715   memcpy (&message[1], enc, esize);
 716
 717   if (iter != NULL)
 718     {
 719       route_handle = GNUNET_malloc (sizeof (struct GNUNET_DHT_RouteHandle));
 720       route_handle->key = *key;
 721       route_handle->iter = iter;
 722       route_handle->iter_cls = iter_cls;
 723       route_handle->dht_handle = handle;
 724       route_handle->uid = handle->uid_gen;
 725       route_handle->message = pending;
 726       GNUNET_CONTAINER_multihashmap_put (handle->active_requests,
 727                                          key,
 728                                          route_handle,
 729                                          GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE);
 730     }
 731   else
 732     {
 733       route_handle = NULL;
 734       pending->free_on_send = GNUNET_YES;
 735       pending->timeout_task = GNUNET_SCHEDULER_add_delayed (timeout,
 736                                                             &timeout_route_request,
 737                                                             pending);
 738     }
 739   GNUNET_CONTAINER_DLL_insert (handle->pending_head,
 740                                handle->pending_tail,
 741                                pending);
 742   pending->in_pending_queue = GNUNET_YES;
 743   process_pending_messages (handle);
 744   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 745               "DHT route start request processed, returning %p\n",
 746               route_handle);
 747   return route_handle;
 748 }
 749
 750
 751 /**
 752  * Stop a previously issued routing request
 753  *
 754  * @param route_handle handle to the request to stop
 755  */
 756 void
 757 GNUNET_DHT_route_stop (struct GNUNET_DHT_RouteHandle *route_handle)
 758 {
 759   struct GNUNET_DHT_Handle *handle;
 760   struct PendingMessage *pending;
 761   struct GNUNET_DHT_StopMessage *message;
 762   size_t msize;
 763
 764   handle = route_handle->dht_handle;
 765   if (GNUNET_NO == route_handle->message->in_pending_queue)
 766     {
 767       /* need to send stop message */
 768       msize = sizeof (struct GNUNET_DHT_StopMessage);
 769       pending = GNUNET_malloc (sizeof (struct PendingMessage) +
 770                                msize);
 771       message = (struct GNUNET_DHT_StopMessage*) &pending[1];
 772       pending->msg = &message->header;
 773       message->header.size = htons (msize);
 774       message->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_LOCAL_ROUTE_STOP);
 775       message->reserved = 0;
 776       message->unique_id = GNUNET_htonll (route_handle->uid);
 777       message->key = route_handle->key;
 778       pending->handle = handle;
 779       pending->free_on_send = GNUNET_YES;
 780       pending->in_pending_queue = GNUNET_YES;
 781       GNUNET_CONTAINER_DLL_insert (handle->pending_head,
 782                                    handle->pending_tail,
 783                                    pending);
 784       process_pending_messages (handle);
 785     }
 786   else
 787     {
 788       /* simply remove pending request from message queue before
 789          transmission, no need to transmit STOP request! */
 790       GNUNET_CONTAINER_DLL_remove (handle->pending_head,
 791                                    handle->pending_tail,
 792                                    route_handle->message);
 793     }
 794   GNUNET_assert (GNUNET_YES ==
 795                  GNUNET_CONTAINER_multihashmap_remove (route_handle->dht_handle->active_requests,
 796                                                        &route_handle->key,
 797                                                        route_handle));
 798   GNUNET_free(route_handle->message);
 799   GNUNET_free(route_handle);
 800   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 801               "DHT route stop request processed\n");
 802 }
 803
 804
 805
 806 /* ***** Special API for controlling DHT routing maintenance ******* */
 807
 808
 809 /**
 810  * Send a control message to the DHT.
 811  *
 812  * @param handle handle to the DHT service
 813  * @param command command
 814  * @param variable variable to the command
 815  * @param cont continuation to call when done (transmitting request to service)
 816  * @param cont_cls closure for cont
 817  */
 818 static void
 819 send_control_message (struct GNUNET_DHT_Handle *handle,
 820                       uint16_t command,
 821                       uint16_t variable,
 822                       GNUNET_SCHEDULER_Task cont,
 823                       void *cont_cls)
 824 {
 825   struct GNUNET_DHT_ControlMessage *msg;
 826   struct PendingMessage *pending;
 827
 828   pending = GNUNET_malloc (sizeof (struct PendingMessage) +
 829                            sizeof(struct GNUNET_DHT_ControlMessage));
 830   msg = (struct GNUNET_DHT_ControlMessage*) &pending[1];
 831   pending->msg = &msg->header;
 832   msg->header.size = htons (sizeof(struct GNUNET_DHT_ControlMessage));
 833   msg->header.type = htons (GNUNET_MESSAGE_TYPE_DHT_CONTROL);
 834   msg->command = htons (command);
 835   msg->variable = htons (variable);
 836   pending->free_on_send = GNUNET_YES;
 837   pending->cont = cont;
 838   pending->cont_cls = cont_cls;
 839   pending->in_pending_queue = GNUNET_YES;
 840   GNUNET_CONTAINER_DLL_insert (handle->pending_head,
 841                                handle->pending_tail,
 842                                pending);
 843   process_pending_messages (handle);
 844 }
 845
 846
 847 /**
 848  * Send a message to the DHT telling it to issue a single find
 849  * peer request using the peers unique identifier as key.  This
 850  * is used to fill the routing table, and is normally controlled
 851  * by the DHT itself.  However, for testing and perhaps more
 852  * close control over the DHT, this can be explicitly managed.
 853  *
 854  * @param handle handle to the DHT service
 855  * @param cont continuation to call when done (transmitting request to service)
 856  * @param cont_cls closure for cont
 857  */
 858 void
 859 GNUNET_DHT_find_peers (struct GNUNET_DHT_Handle *handle,
 860                        GNUNET_SCHEDULER_Task cont,
 861                        void *cont_cls)
 862 {
 863   send_control_message (handle,
 864                         GNUNET_MESSAGE_TYPE_DHT_FIND_PEER, 0,
 865                         cont, cont_cls);
 866 }
 867
 868
 869
 870 #if HAVE_MALICIOUS
 871
 872 /**
 873  * Send a message to the DHT telling it to start issuing random GET
 874  * requests every 'frequency' milliseconds.
 875  *
 876  * @param handle handle to the DHT service
 877  * @param frequency delay between sending malicious messages
 878  * @param cont continuation to call when done (transmitting request to service)
 879  * @param cont_cls closure for cont
 880  */
 881 void
 882 GNUNET_DHT_set_malicious_getter (struct GNUNET_DHT_Handle *handle,
 883                                  struct GNUNET_TIME_Relative frequency, GNUNET_SCHEDULER_Task cont,
 884                             void *cont_cls)
 885 {
 886   if (frequency.rel_value > UINT16_MAX)
 887     {
 888       GNUNET_break (0);
 889       return;
 890     }
 891   send_control_message (handle,
 892                         GNUNET_MESSAGE_TYPE_DHT_MALICIOUS_GET, frequency.rel_value,
 893                         cont, cont_cls);
 894 }
 895
 896 /**
 897  * Send a message to the DHT telling it to start issuing random PUT
 898  * requests every 'frequency' milliseconds.
 899  *
 900  * @param handle handle to the DHT service
 901  * @param frequency delay between sending malicious messages
 902  * @param cont continuation to call when done (transmitting request to service)
 903  * @param cont_cls closure for cont
 904  */
 905 void
 906 GNUNET_DHT_set_malicious_putter (struct GNUNET_DHT_Handle *handle,
 907                                  struct GNUNET_TIME_Relative frequency, GNUNET_SCHEDULER_Task cont,
 908                             void *cont_cls)
 909 {
 910   if (frequency.rel_value > UINT16_MAX)
 911     {
 912       GNUNET_break (0);
 913       return;
 914     }
 915
 916   send_control_message (handle,
 917                         GNUNET_MESSAGE_TYPE_DHT_MALICIOUS_PUT, frequency.rel_value,
 918                         cont, cont_cls);
 919 }
 920
 921
 922 /**
 923  * Send a message to the DHT telling it to start dropping
 924  * all requests received.
 925  *
 926  * @param handle handle to the DHT service
 927  * @param cont continuation to call when done (transmitting request to service)
 928  * @param cont_cls closure for cont
 929  *
 930  */
 931 void
 932 GNUNET_DHT_set_malicious_dropper (struct GNUNET_DHT_Handle *handle, GNUNET_SCHEDULER_Task cont,
 933     void *cont_cls)
 934 {
 935   send_control_message (handle,
 936                         GNUNET_MESSAGE_TYPE_DHT_MALICIOUS_DROP, 0,
 937                         cont, cont_cls);
 938 }
 939
 940 #endif
 941
 942 /* end of dht_api.c */