src/dht/gnunet-service-wdht_neighbours.c

   1 /*
   2      This file is part of GNUnet.
   3      Copyright (C) 2009-2015 GNUnet e.V.
   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., 51 Franklin Street, Fifth Floor,
  18      Boston, MA 02110-1301, USA.
  19 */
  20 /**
  21  * @file dht/gnunet-service-wdht_neighbours.c
  22  * @brief GNUnet DHT service's finger and friend table management code
  23  * @author Supriti Singh
  24  * @author Christian Grothoff
  25  * @author Arthur Dewarumez
  26  *
  27  * TODO:
  28  * - initiate finding of successors
  29  */
  30 #include "platform.h"
  31 #include "gnunet_util_lib.h"
  32 #include "gnunet_block_lib.h"
  33 #include "gnunet_hello_lib.h"
  34 #include "gnunet_constants.h"
  35 #include "gnunet_protocols.h"
  36 #include "gnunet_ats_service.h"
  37 #include "gnunet_core_service.h"
  38 #include "gnunet_datacache_lib.h"
  39 #include "gnunet_transport_service.h"
  40 #include "gnunet_dht_service.h"
  41 #include "gnunet_statistics_service.h"
  42 #include "gnunet-service-wdht.h"
  43 #include "gnunet-service-wdht_clients.h"
  44 #include "gnunet-service-wdht_datacache.h"
  45 #include "gnunet-service-wdht_neighbours.h"
  46 #include "gnunet-service-wdht_nse.h"
  47 #include "dht.h"
  48
  49 #define DEBUG(...)                                           \
  50   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, __VA_ARGS__)
  51
  52 /**
  53  * Trail timeout. After what time do trails always die?
  54  */
  55 #define TRAIL_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 42)
  56
  57 /**
  58  * Random walk delay. How often do we walk the overlay?
  59  */
  60 #define RANDOM_WALK_DELAY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 42)
  61
  62 /**
  63  * The number of layered ID to use.
  64  */
  65 #define NUMBER_LAYERED_ID 8
  66
  67 /**
  68  * The number of random walk to launch at the beginning of the initialization
  69  */
  70 /* FIXME: find a better value */
  71 #define NUMBER_RANDOM_WALK 20
  72
  73
  74 /******************* The db structure and related functions *******************/
  75
  76 /**
  77  * Entry in #friends_peermap.
  78  */
  79 struct FriendInfo;
  80
  81 /**
  82  *
  83  */
  84 struct FingerTable;
  85
  86 /**
  87  * Information we keep per trail.
  88  */
  89 struct Trail
  90 {
  91
  92   /**
  93    * Identifier of the trail with the predecessor.
  94    */
  95   struct GNUNET_HashCode pred_id;
  96
  97   /**
  98    * Identifier of the trail with the successor.
  99    */
 100   struct GNUNET_HashCode succ_id;
 101
 102   /**
 103    * When does this trail expire.
 104    */
 105   struct GNUNET_TIME_Absolute expiration_time;
 106
 107   /**
 108    * MDLL entry in the list of all trails with the same predecessor.
 109    */
 110   struct Trail *prev_succ;
 111
 112   /**
 113    * MDLL entry in the list of all trails with the same predecessor.
 114    */
 115   struct Trail *next_succ;
 116
 117   /**
 118    * MDLL entry in the list of all trails with the same predecessor.
 119    */
 120   struct Trail *prev_pred;
 121
 122   /**
 123    * MDLL entry in the list of all trails with the same predecessor.
 124    */
 125   struct Trail *next_pred;
 126
 127   /**
 128    * Our predecessor in the trail, NULL if we are initiator (?).
 129    */
 130   struct FriendInfo *pred;
 131
 132   /**
 133    * Our successor in the trail, NULL if we are the last peer.
 134    */
 135   struct FriendInfo *succ;
 136
 137   /**
 138    * Location of this trail in the heap.
 139    */
 140   struct GNUNET_CONTAINER_HeapNode *hn;
 141
 142   /**
 143    * If this peer started the to create a Finger (and thus @e pred is
 144    * NULL), this is the finger table of the finger we are trying to
 145    * intialize.
 146    */
 147   struct FingerTable *ft;
 148
 149   /**
 150    * If this peer started the trail to create a Finger (and thus @e
 151    * pred is NULL), this is the offset of the finger we are trying to
 152    * intialize in the unsorted array.
 153    */
 154   unsigned int finger_off;
 155
 156 };
 157
 158
 159 /**
 160  *  Entry in #friends_peermap.
 161  */
 162 struct FriendInfo
 163 {
 164   /**
 165    * Friend Identity
 166    */
 167   struct GNUNET_PeerIdentity id;
 168
 169   /**
 170    *
 171    */
 172   struct Trail *pred_head;
 173
 174   /**
 175    *
 176    */
 177   struct Trail *pred_tail;
 178
 179   /**
 180    *
 181    */
 182   struct Trail *succ_head;
 183
 184   /**
 185    *
 186    */
 187   struct Trail *succ_tail;
 188
 189   /**
 190    * Core handle for sending messages to this friend.
 191    */
 192   struct GNUNET_MQ_Handle *mq;
 193
 194 };
 195
 196
 197 /**
 198  *
 199  */
 200 struct Finger
 201 {
 202   /**
 203    *
 204    */
 205   struct Trail *trail;
 206
 207   /**
 208    *
 209    */
 210   struct FingerTable *ft;
 211
 212   /**
 213    *
 214    */
 215   struct GNUNET_HashCode destination;
 216
 217   /**
 218    * #GNUNET_YES if a response has been received. Otherwise #GNUNET_NO.
 219    */
 220   int valid;
 221 };
 222
 223
 224 struct FingerTable
 225 {
 226   /**
 227    * Array of our fingers, unsorted.
 228    */
 229   struct Finger **fingers;
 230
 231   /**
 232    * Size of the finger array.
 233    */
 234   unsigned int finger_array_size;
 235
 236   /**
 237    * Number of valid entries in @e fingers
 238    */
 239   unsigned int number_valid_fingers;
 240
 241   /**
 242    * Which offset in @e fingers will we redo next.
 243    */
 244   unsigned int walk_offset;
 245
 246   /**
 247    * Is the finger array sorted?
 248    */
 249   int is_sorted;
 250
 251 };
 252
 253
 254 /***********************  end of the db structure part  ***********************/
 255
 256
 257 GNUNET_NETWORK_STRUCT_BEGIN
 258
 259 /**
 260  * Setup a finger using the underlay topology ("social network").
 261  */
 262 struct RandomWalkMessage
 263 {
 264   /**
 265    * Type: #GNUNET_MESSAGE_TYPE_WDHT_RANDOM_WALK
 266    */
 267   struct GNUNET_MessageHeader header;
 268
 269   /**
 270    * Number of hops this message has taken so far, we stop at
 271    * log(NSE), in NBO.
 272    */
 273   uint16_t hops_taken GNUNET_PACKED;
 274
 275   /**
 276    * Layer for the request, in NBO.
 277    */
 278   uint16_t layer GNUNET_PACKED;
 279
 280   /**
 281    * Unique (random) identifier this peer will use to
 282    * identify the trail (in future messages).
 283    */
 284   struct GNUNET_HashCode trail_id;
 285
 286 };
 287
 288 /**
 289  * Response to a `struct RandomWalkMessage`.
 290  */
 291 struct RandomWalkResponseMessage
 292 {
 293   /**
 294    * Type: #GNUNET_MESSAGE_TYPE_WDHT_RANDOM_WALK_RESPONSE
 295    */
 296   struct GNUNET_MessageHeader header;
 297
 298   /**
 299    * Zero, for alignment.
 300    */
 301   uint32_t reserved GNUNET_PACKED;
 302
 303   /**
 304    * Unique (random) identifier from the
 305    * `struct RandomWalkMessage`.
 306    */
 307   struct GNUNET_HashCode trail_id;
 308
 309   /**
 310    * Random location in the respective layer where the
 311    * random path of the finger setup terminated.
 312    */
 313   struct GNUNET_HashCode location;
 314
 315 };
 316
 317 /**
 318  * Response to an event that causes a trail to die.
 319  */
 320 struct TrailDestroyMessage
 321 {
 322   /**
 323    * Type: #GNUNET_MESSAGE_TYPE_WDHT_TRAIL_DESTROY
 324    */
 325   struct GNUNET_MessageHeader header;
 326
 327   /**
 328    * Zero, for alignment.
 329    */
 330   uint32_t reserved GNUNET_PACKED;
 331
 332   /**
 333    * Unique (random) identifier this peer will use to
 334    * identify the finger (in future messages).
 335    */
 336   struct GNUNET_HashCode trail_id;
 337
 338 };
 339
 340
 341 /**
 342  * Send a message along a trail.
 343  */
 344 struct FindSuccessorMessage
 345 {
 346   /**
 347    * Type: #GNUNET_MESSAGE_TYPE_WDHT_SUCCESSOR_FIND
 348    */
 349   struct GNUNET_MessageHeader header;
 350
 351   /**
 352    * Zero, for alignment.
 353    */
 354   uint32_t reserved GNUNET_PACKED;
 355
 356   /**
 357    * Key for which we would like close values returned.
 358    * identify the finger (in future messages).
 359    */
 360   struct GNUNET_HashCode key;
 361
 362 };
 363
 364
 365 /**
 366  * Send a message along a trail.
 367  */
 368 struct TrailRouteMessage
 369 {
 370   /**
 371    * Type: #GNUNET_MESSAGE_TYPE_WDHT_TRAIL_ROUTE
 372    */
 373   struct GNUNET_MessageHeader header;
 374
 375   /**
 376    * #GNUNET_YES if the path should be recorded, #GNUNET_NO if not; in NBO.
 377    */
 378   uint16_t record_path GNUNET_PACKED;
 379
 380   /**
 381    * Length of the recorded trail, 0 if @e record_path is #GNUNET_NO; in NBO.
 382    */
 383   uint16_t path_length GNUNET_PACKED;
 384
 385   /**
 386    * Unique (random) identifier this peer will use to
 387    * identify the finger (in future messages).
 388    */
 389   struct GNUNET_HashCode trail_id;
 390
 391   /**
 392    * Path the message has taken so far (excluding sender).
 393    */
 394   /* struct GNUNET_PeerIdentity path[path_length]; */
 395
 396   /* followed by payload (another `struct GNUNET_MessageHeader`) to
 397      send along the trail */
 398 };
 399
 400
 401 /**
 402  * P2P PUT message
 403  */
 404 struct PeerPutMessage
 405 {
 406   /**
 407    * Type: #GNUNET_MESSAGE_TYPE_WDHT_PUT
 408    */
 409   struct GNUNET_MessageHeader header;
 410
 411   /**
 412    * Processing options
 413    */
 414   uint32_t options GNUNET_PACKED;
 415
 416   /**
 417    * Content type.
 418    */
 419   uint32_t block_type GNUNET_PACKED;
 420
 421   /**
 422    * Hop count
 423    */
 424   uint32_t hop_count GNUNET_PACKED;
 425
 426   /**
 427    * Replication level for this message
 428    * In the current implementation, this value is not used.
 429    */
 430   uint32_t desired_replication_level GNUNET_PACKED;
 431
 432   /**
 433    * Length of the PUT path that follows (if tracked).
 434    */
 435   uint32_t put_path_length GNUNET_PACKED;
 436
 437   /**
 438    * When does the content expire?
 439    */
 440   struct GNUNET_TIME_AbsoluteNBO expiration_time;
 441
 442   /**
 443    * The key to store the value under.
 444    */
 445   struct GNUNET_HashCode key GNUNET_PACKED;
 446
 447   /* put path (if tracked) */
 448
 449   /* Payload */
 450
 451 };
 452
 453 /**
 454  * P2P GET message
 455  */
 456 struct PeerGetMessage
 457 {
 458   /**
 459    * Type: #GNUNET_MESSAGE_TYPE_WDHT_GET
 460    */
 461   struct GNUNET_MessageHeader header;
 462
 463   /**
 464    * Processing options
 465    */
 466   uint32_t options GNUNET_PACKED;
 467
 468   /**
 469    * Desired content type.
 470    */
 471   uint32_t block_type GNUNET_PACKED;
 472
 473   /**
 474    * Hop count
 475    */
 476   uint32_t hop_count GNUNET_PACKED;
 477
 478   /**
 479    * Desired replication level for this request.
 480    * In the current implementation, this value is not used.
 481    */
 482   uint32_t desired_replication_level GNUNET_PACKED;
 483
 484   /**
 485    * Total number of peers in get path.
 486    */
 487   unsigned int get_path_length;
 488
 489   /**
 490    * The key we are looking for.
 491    */
 492   struct GNUNET_HashCode key;
 493
 494   /* Get path. */
 495   /* struct GNUNET_PeerIdentity[]*/
 496 };
 497
 498
 499 /**
 500  * P2P Result message
 501  */
 502 struct PeerGetResultMessage
 503 {
 504   /**
 505    * Type: #GNUNET_MESSAGE_TYPE_WDHT_GET_RESULT
 506    */
 507   struct GNUNET_MessageHeader header;
 508
 509   /**
 510    * The type for the data in NBO.
 511    */
 512   uint32_t type GNUNET_PACKED;
 513
 514   /**
 515    * Number of peers recorded in the outgoing path from source to the
 516    * stored location of this message.
 517    */
 518   uint32_t put_path_length GNUNET_PACKED;
 519
 520   /**
 521    * When does the content expire?
 522    */
 523   struct GNUNET_TIME_AbsoluteNBO expiration_time;
 524
 525   /**
 526    * The key of the corresponding GET request.
 527    */
 528   struct GNUNET_HashCode key;
 529
 530   /* put path (if tracked) */
 531
 532   /* Payload */
 533
 534 };
 535
 536 GNUNET_NETWORK_STRUCT_END
 537
 538
 539 /**
 540  * Contains all the layered IDs of this peer.
 541  */
 542 struct GNUNET_PeerIdentity layered_id[NUMBER_LAYERED_ID];
 543
 544 /**
 545  * Task to timeout trails that have expired.
 546  */
 547 static struct GNUNET_SCHEDULER_Task *trail_timeout_task;
 548
 549 /**
 550  * Task to perform random walks.
 551  */
 552 static struct GNUNET_SCHEDULER_Task *random_walk_task;
 553
 554 /**
 555  * Identity of this peer.
 556  */
 557 static struct GNUNET_PeerIdentity my_identity;
 558
 559 /**
 560  * Peer map of all the friends of a peer
 561  */
 562 static struct GNUNET_CONTAINER_MultiPeerMap *friends_peermap;
 563
 564 /**
 565  * Fingers per layer.
 566  */
 567 static struct FingerTable fingers[NUMBER_LAYERED_ID];
 568
 569 /**
 570  * Tail map, mapping tail identifiers to `struct Trail`s
 571  */
 572 static struct GNUNET_CONTAINER_MultiHashMap *trail_map;
 573
 574 /**
 575  * Tail heap, organizing trails by expiration time.
 576  */
 577 static struct GNUNET_CONTAINER_Heap *trail_heap;
 578
 579 /**
 580  * Handle to CORE.
 581  */
 582 static struct GNUNET_CORE_Handle *core_api;
 583
 584
 585 /**
 586  * Handle the put request from the client.
 587  *
 588  * @param key Key for the content
 589  * @param block_type Type of the block
 590  * @param options Routing options
 591  * @param desired_replication_level Desired replication count
 592  * @param expiration_time When does the content expire
 593  * @param data Content to store
 594  * @param data_size Size of content @a data in bytes
 595  */
 596 void
 597 GDS_NEIGHBOURS_handle_put (const struct GNUNET_HashCode *key,
 598                            enum GNUNET_BLOCK_Type block_type,
 599                            enum GNUNET_DHT_RouteOption options,
 600                            uint32_t desired_replication_level,
 601                            struct GNUNET_TIME_Absolute expiration_time,
 602                            const void *data,
 603                            size_t data_size)
 604 {
 605   GDS_DATACACHE_handle_put (expiration_time,
 606                             key,
 607                             0, NULL,
 608                             0, NULL,
 609                             block_type,
 610                             data_size,
 611                             data);
 612   GDS_CLIENTS_process_put (options,
 613                            block_type,
 614                            0, 0,
 615                            0, NULL,
 616                            expiration_time,
 617                            key,
 618                            data,
 619                            data_size);
 620 }
 621
 622
 623 /**
 624  * Handle the get request from the client file. If I am destination do
 625  * datacache put and return. Else find the target friend and forward message
 626  * to it.
 627  *
 628  * @param key Key for the content
 629  * @param block_type Type of the block
 630  * @param options Routing options
 631  * @param desired_replication_level Desired replication count
 632  */
 633 void
 634 GDS_NEIGHBOURS_handle_get (const struct GNUNET_HashCode *key,
 635                            enum GNUNET_BLOCK_Type block_type,
 636                            enum GNUNET_DHT_RouteOption options,
 637                            uint32_t desired_replication_level)
 638 {
 639   // find closest finger(s) on all layers
 640   // use TrailRoute with PeerGetMessage embedded to contact peer
 641   // NOTE: actually more complicated, see paper!
 642 }
 643
 644
 645 /**
 646  * Delete a trail, it died (timeout, link failure, etc.).
 647  *
 648  * @param trail trail to delete from all data structures
 649  * @param inform_pred should we notify the predecessor?
 650  * @param inform_succ should we inform the successor?
 651  */
 652 static void
 653 delete_trail (struct Trail *trail,
 654               int inform_pred,
 655               int inform_succ)
 656 {
 657   struct FriendInfo *friend;
 658   struct GNUNET_MQ_Envelope *env;
 659   struct TrailDestroyMessage *tdm;
 660   struct Finger *finger;
 661
 662   friend = trail->pred;
 663   if (NULL != friend)
 664   {
 665     if (GNUNET_YES == inform_pred)
 666     {
 667       env = GNUNET_MQ_msg (tdm,
 668                            GNUNET_MESSAGE_TYPE_WDHT_TRAIL_DESTROY);
 669       tdm->trail_id = trail->pred_id;
 670       GNUNET_MQ_send (friend->mq,
 671                       env);
 672     }
 673     GNUNET_CONTAINER_MDLL_remove (pred,
 674                                   friend->pred_head,
 675                                   friend->pred_tail,
 676                                   trail);
 677   }
 678   friend = trail->succ;
 679   if (NULL != friend)
 680   {
 681     if (GNUNET_YES == inform_succ)
 682     {
 683       env = GNUNET_MQ_msg (tdm,
 684                            GNUNET_MESSAGE_TYPE_WDHT_TRAIL_DESTROY);
 685       tdm->trail_id = trail->pred_id;
 686       GNUNET_MQ_send (friend->mq,
 687                       env);
 688     }
 689     GNUNET_CONTAINER_MDLL_remove (succ,
 690                                   friend->pred_head,
 691                                   friend->pred_tail,
 692                                   trail);
 693   }
 694   GNUNET_break (trail ==
 695                 GNUNET_CONTAINER_heap_remove_node (trail->hn));
 696   finger = trail->ft->fingers[trail->finger_off];
 697   if (NULL != finger)
 698   {
 699     trail->ft->fingers[trail->finger_off] = NULL;
 700     trail->ft->number_valid_fingers--;
 701     GNUNET_free (finger);
 702   }
 703   GNUNET_free (trail);
 704 }
 705
 706
 707 /**
 708  * Forward the given payload message along the trail.
 709  *
 710  * @param next_target which direction along the trail should we forward
 711  * @param trail_id which trail should we forward along
 712  * @param have_path do we track the forwarding path?
 713  * @param predecessor which peer do we tack on to the path?
 714  * @param path path the message has taken so far along the trail
 715  * @param path_length number of entries in @a path
 716  * @param payload payload of the message
 717  */
 718 static void
 719 forward_message_on_trail (struct FriendInfo *next_target,
 720                           const struct GNUNET_HashCode *trail_id,
 721                           int have_path,
 722                           const struct GNUNET_PeerIdentity *predecessor,
 723                           const struct GNUNET_PeerIdentity *path,
 724                           uint16_t path_length,
 725                           const struct GNUNET_MessageHeader *payload)
 726 {
 727   struct GNUNET_MQ_Envelope *env;
 728   struct TrailRouteMessage *trm;
 729   struct GNUNET_PeerIdentity *new_path;
 730   unsigned int plen;
 731   uint16_t payload_len;
 732
 733   payload_len = ntohs (payload->size);
 734   if (have_path)
 735   {
 736     plen = path_length + 1;
 737     if (plen >= (GNUNET_SERVER_MAX_MESSAGE_SIZE
 738                  - payload_len
 739                  - sizeof (struct TrailRouteMessage))
 740         / sizeof (struct GNUNET_PeerIdentity))
 741     {
 742       /* Should really not have paths this long... */
 743       GNUNET_break_op (0);
 744       plen = 0;
 745       have_path = 0;
 746     }
 747   }
 748   else
 749   {
 750     GNUNET_break_op (0 == path_length);
 751     path_length = 0;
 752     plen = 0;
 753   }
 754   env = GNUNET_MQ_msg_extra (trm,
 755                              payload_len +
 756                              plen * sizeof (struct GNUNET_PeerIdentity),
 757                              GNUNET_MESSAGE_TYPE_WDHT_TRAIL_ROUTE);
 758   trm->record_path = htons (have_path);
 759   trm->path_length = htons (plen);
 760   trm->trail_id = *trail_id;
 761   new_path = (struct GNUNET_PeerIdentity *) &trm[1];
 762   if (have_path)
 763   {
 764     memcpy (new_path,
 765             path,
 766             path_length * sizeof (struct GNUNET_PeerIdentity));
 767     new_path[path_length] = *predecessor;
 768   }
 769   memcpy (&new_path[plen],
 770           payload,
 771           payload_len);
 772   GNUNET_MQ_send (next_target->mq,
 773                   env);
 774 }
 775
 776
 777 /**
 778  * Send the get result to requesting client.
 779  *
 780  * @param trail_id trail identifying where to send the result to, NULL for us
 781  * @param options routing options (from GET request)
 782  * @param key Key of the requested data.
 783  * @param type Block type
 784  * @param put_path_length Number of peers in @a put_path
 785  * @param put_path Path taken to put the data at its stored location.
 786  * @param expiration When will this result expire?
 787  * @param data Payload to store
 788  * @param data_size Size of the @a data
 789  */
 790 void
 791 GDS_NEIGHBOURS_send_get_result (const struct GNUNET_HashCode *trail_id,
 792                                 enum GNUNET_DHT_RouteOption options,
 793                                 const struct GNUNET_HashCode *key,
 794                                 enum GNUNET_BLOCK_Type type,
 795                                 unsigned int put_path_length,
 796                                 const struct GNUNET_PeerIdentity *put_path,
 797                                 struct GNUNET_TIME_Absolute expiration,
 798                                 const void *data,
 799                                 size_t data_size)
 800 {
 801   struct GNUNET_MessageHeader *payload;
 802   struct Trail *trail;
 803
 804   trail = GNUNET_CONTAINER_multihashmap_get (trail_map,
 805                                              trail_id);
 806   if (NULL == trail)
 807   {
 808     /* TODO: inform statistics */
 809     return;
 810   }
 811   if (NULL == trail->pred)
 812   {
 813     /* result is for *us* (local client) */
 814     GDS_CLIENTS_handle_reply (expiration,
 815                               key,
 816                               0, NULL,
 817                               put_path_length, put_path,
 818                               type,
 819                               data_size,
 820                               data);
 821     return;
 822   }
 823
 824   payload = GNUNET_malloc(sizeof(struct GNUNET_MessageHeader) + data_size);
 825   payload->size = data_size;
 826   payload->type = GNUNET_MESSAGE_TYPE_WDHT_GET_RESULT;
 827
 828   forward_message_on_trail (trail->pred,
 829                             trail_id,
 830                             0 != (options & GNUNET_DHT_RO_RECORD_ROUTE),
 831                             &my_identity,
 832                             NULL, 0,
 833                             payload);
 834   GNUNET_free (payload);
 835 }
 836
 837
 838 /**
 839  * Method called whenever a peer disconnects.
 840  *
 841  * @param cls closure
 842  * @param peer peer identity this notification is about
 843  */
 844 static void
 845 handle_core_disconnect (void *cls,
 846                         const struct GNUNET_PeerIdentity *peer)
 847 {
 848   struct FriendInfo *remove_friend;
 849   struct Trail *t;
 850
 851   /* If disconnected to own identity, then return. */
 852   if (0 == memcmp (&my_identity,
 853                    peer,
 854                    sizeof (struct GNUNET_PeerIdentity)))
 855     return;
 856
 857   if (NULL == (remove_friend =
 858                GNUNET_CONTAINER_multipeermap_get (friends_peermap,
 859                                                   peer)))
 860   {
 861     GNUNET_break (0);
 862     return;
 863   }
 864
 865   GNUNET_assert (GNUNET_YES ==
 866                  GNUNET_CONTAINER_multipeermap_remove (friends_peermap,
 867                                                        peer,
 868                                                        remove_friend));
 869   while (NULL != (t = remove_friend->succ_head))
 870     delete_trail (t,
 871                   GNUNET_YES,
 872                   GNUNET_NO);
 873   while (NULL != (t = remove_friend->pred_head))
 874     delete_trail (t,
 875                   GNUNET_NO,
 876                   GNUNET_YES);
 877   GNUNET_MQ_destroy (remove_friend->mq);
 878   GNUNET_free (remove_friend);
 879   if (0 ==
 880       GNUNET_CONTAINER_multipeermap_size (friends_peermap))
 881   {
 882     GNUNET_SCHEDULER_cancel (random_walk_task);
 883     random_walk_task = NULL;
 884   }
 885 }
 886
 887
 888 /**
 889  * Function called with a random friend to be returned.
 890  *
 891  * @param cls a `struct FriendInfo **` with where to store the result
 892  * @param peer the peer identity of the friend (ignored)
 893  * @param value the `struct FriendInfo *` that was selected at random
 894  * @return #GNUNET_OK (all good)
 895  */
 896 static int
 897 pick_random_helper (void *cls,
 898                     const struct GNUNET_PeerIdentity *peer,
 899                     void *value)
 900 {
 901   struct FriendInfo **fi = cls;
 902   struct FriendInfo *v = value;
 903
 904   *fi = v;
 905   return GNUNET_OK;
 906 }
 907
 908
 909 /**
 910  * Pick random friend from friends for random walk.
 911  *
 912  * @return NULL if we have no friends
 913  */
 914 static struct FriendInfo *
 915 pick_random_friend ()
 916 {
 917   struct FriendInfo *ret;
 918
 919   ret = NULL;
 920   if (0 ==
 921       GNUNET_CONTAINER_multipeermap_get_random (friends_peermap,
 922                                                 &pick_random_helper,
 923                                                 &ret))
 924     return NULL;
 925   return ret;
 926 }
 927
 928
 929 /**
 930  * One of our trails might have timed out, check and
 931  * possibly initiate cleanup.
 932  *
 933  * @param cls NULL
 934  */
 935 static void
 936 trail_timeout_callback (void *cls)
 937 {
 938   struct Trail *trail;
 939   struct GNUNET_TIME_Relative left;
 940
 941   trail_timeout_task = NULL;
 942   while (NULL != (trail = GNUNET_CONTAINER_heap_peek (trail_heap)))
 943   {
 944     left = GNUNET_TIME_absolute_get_remaining (trail->expiration_time);
 945     if (0 != left.rel_value_us)
 946       break;
 947     delete_trail (trail,
 948                   GNUNET_YES,
 949                   GNUNET_YES);
 950   }
 951   if (NULL != trail)
 952     trail_timeout_task = GNUNET_SCHEDULER_add_delayed (left,
 953                                                        &trail_timeout_callback,
 954                                                        NULL);
 955 }
 956
 957
 958 /**
 959  * Compute how big our finger arrays should be (at least).
 960  *
 961  * @return size of the finger array, never 0
 962  */
 963 static unsigned int
 964 get_desired_finger_array_size ()
 965 {
 966   /* FIXME: This is just a stub... */
 967   return 64;
 968 }
 969
 970
 971 /**
 972  * Initiate a random walk.
 973  *
 974  * @param cls NULL
 975  */
 976 static void
 977 do_random_walk (void *cls)
 978 {
 979   static unsigned int walk_layer;
 980   struct FriendInfo *friend;
 981   struct GNUNET_MQ_Envelope *env;
 982   struct RandomWalkMessage *rwm;
 983   struct FingerTable *ft;
 984   struct Finger *finger;
 985   struct Trail *trail;
 986   unsigned int nsize;
 987
 988   random_walk_task = NULL;
 989   friend = pick_random_friend ();
 990
 991   trail = GNUNET_new (struct Trail);
 992   /* We create the random walk so, no predecessor */
 993   trail->succ = friend;
 994   GNUNET_CRYPTO_hash_create_random (GNUNET_CRYPTO_QUALITY_NONCE,
 995                                     &trail->succ_id);
 996   if (GNUNET_OK !=
 997       GNUNET_CONTAINER_multihashmap_put (trail_map,
 998                                          &trail->succ_id,
 999                                          trail,
1000                                          GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY))
1001   {
1002     GNUNET_break (0);
1003     GNUNET_free (trail);
1004     return;
1005   }
1006   GNUNET_CONTAINER_MDLL_insert (succ,
1007                                 friend->succ_head,
1008                                 friend->succ_tail,
1009                                 trail);
1010   trail->expiration_time = GNUNET_TIME_relative_to_absolute (TRAIL_TIMEOUT);
1011   trail->hn = GNUNET_CONTAINER_heap_insert (trail_heap,
1012                                             trail,
1013                                             trail->expiration_time.abs_value_us);
1014   if (NULL == trail_timeout_task)
1015     trail_timeout_task = GNUNET_SCHEDULER_add_delayed (TRAIL_TIMEOUT,
1016                                                        &trail_timeout_callback,
1017                                                        NULL);
1018   env = GNUNET_MQ_msg (rwm,
1019                        GNUNET_MESSAGE_TYPE_WDHT_RANDOM_WALK);
1020   rwm->hops_taken = htonl (0);
1021   rwm->trail_id = trail->succ_id;
1022   GNUNET_MQ_send (friend->mq,
1023                   env);
1024   /* clean up 'old' entry (implicitly via trail cleanup) */
1025   ft = &fingers[walk_layer];
1026
1027   if ( (NULL != ft->fingers) &&
1028        (NULL != (finger = ft->fingers[ft->walk_offset])) )
1029     delete_trail (finger->trail,
1030                   GNUNET_NO,
1031                   GNUNET_YES);
1032   if (ft->finger_array_size < (nsize = get_desired_finger_array_size()) )
1033     GNUNET_array_grow (ft->fingers,
1034                        ft->finger_array_size,
1035                        nsize);
1036   GNUNET_assert (NULL == ft->fingers[ft->walk_offset]);
1037   trail->ft = ft;
1038   trail->finger_off = ft->walk_offset;
1039   finger = GNUNET_new (struct Finger);
1040   finger->trail = trail;
1041   finger->ft = ft;
1042   ft->fingers[ft->walk_offset] = finger;
1043   ft->is_sorted = GNUNET_NO;
1044   ft->number_valid_fingers++;
1045   ft->walk_offset = (ft->walk_offset + 1) % ft->finger_array_size;
1046
1047   walk_layer = (walk_layer + 1) % NUMBER_LAYERED_ID;
1048   random_walk_task = GNUNET_SCHEDULER_add_delayed (RANDOM_WALK_DELAY,
1049                                                    &do_random_walk,
1050                                                    NULL);
1051 }
1052
1053
1054 /**
1055  * Method called whenever a peer connects.
1056  *
1057  * @param cls closure
1058  * @param peer_identity peer identity this notification is about
1059  */
1060 static void
1061 handle_core_connect (void *cls,
1062                      const struct GNUNET_PeerIdentity *peer_identity)
1063 {
1064   struct FriendInfo *friend;
1065
1066   /* Check for connect to self message */
1067   if (0 == memcmp (&my_identity,
1068                    peer_identity,
1069                    sizeof (struct GNUNET_PeerIdentity)))
1070     return;
1071
1072   /* If peer already exists in our friend_peermap, then exit. */
1073   if (GNUNET_YES ==
1074       GNUNET_CONTAINER_multipeermap_contains (friends_peermap,
1075                                               peer_identity))
1076   {
1077     GNUNET_break (0);
1078     return;
1079   }
1080
1081   friend = GNUNET_new (struct FriendInfo);
1082   friend->id = *peer_identity;
1083   friend->mq = GNUNET_CORE_mq_create (core_api,
1084                                       peer_identity);
1085   GNUNET_assert (GNUNET_OK ==
1086                  GNUNET_CONTAINER_multipeermap_put (friends_peermap,
1087                                                     peer_identity,
1088                                                     friend,
1089                                                     GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
1090   if (NULL == random_walk_task)
1091   {
1092     /* random walk needs to be started -- we have a first connection */
1093     random_walk_task = GNUNET_SCHEDULER_add_now (&do_random_walk,
1094                                                  NULL);
1095   }
1096 }
1097
1098
1099 /**
1100  * To be called on core init/fail.
1101  *
1102  * @param cls service closure
1103  * @param identity the public identity of this peer
1104  */
1105 static void
1106 core_init (void *cls,
1107            const struct GNUNET_PeerIdentity *identity)
1108 {
1109   my_identity = *identity;
1110 }
1111
1112
1113 /**
1114  * Handle a `struct RandomWalkMessage` from a
1115  * #GNUNET_MESSAGE_TYPE_WDHT_RANDOM_WALK message.
1116  *
1117  * @param cls closure (NULL)
1118  * @param peer sender identity
1119  * @param message the setup message
1120  * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
1121  */
1122 static int
1123 handle_dht_p2p_random_walk (void *cls,
1124                             const struct GNUNET_PeerIdentity *peer,
1125                             const struct GNUNET_MessageHeader *message)
1126 {
1127   const struct RandomWalkMessage *m;
1128   struct Trail *t;
1129   struct FriendInfo *pred;
1130   uint16_t layer;
1131
1132   m = (const struct RandomWalkMessage *) message;
1133   layer = ntohs (m->layer);
1134   if (layer > NUMBER_LAYERED_ID)
1135   {
1136     GNUNET_break_op (0);
1137     return GNUNET_SYSERR;
1138   }
1139   pred = GNUNET_CONTAINER_multipeermap_get (friends_peermap,
1140                                             peer);
1141   t = GNUNET_new (struct Trail);
1142   t->pred_id = m->trail_id;
1143   t->pred = pred;
1144   if (GNUNET_OK !=
1145       GNUNET_CONTAINER_multihashmap_put (trail_map,
1146                                          &t->pred_id,
1147                                          t,
1148                                          GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY))
1149   {
1150     GNUNET_break_op (0);
1151     GNUNET_free (t);
1152     return GNUNET_SYSERR;
1153   }
1154   GNUNET_CONTAINER_MDLL_insert (pred,
1155                                 pred->pred_head,
1156                                 pred->pred_tail,
1157                                 t);
1158   t->expiration_time = GNUNET_TIME_relative_to_absolute (TRAIL_TIMEOUT);
1159   t->hn = GNUNET_CONTAINER_heap_insert (trail_heap,
1160                                         t,
1161                                         t->expiration_time.abs_value_us);
1162   if (NULL == trail_timeout_task)
1163     trail_timeout_task = GNUNET_SCHEDULER_add_delayed (TRAIL_TIMEOUT,
1164                                                        &trail_timeout_callback,
1165                                                        NULL);
1166
1167   if (ntohl (m->hops_taken) > GDS_NSE_get ())
1168   {
1169     /* We are the last hop, generate response */
1170     struct GNUNET_MQ_Envelope *env;
1171     struct RandomWalkResponseMessage *rwrm;
1172
1173     env = GNUNET_MQ_msg (rwrm,
1174                          GNUNET_MESSAGE_TYPE_WDHT_RANDOM_WALK_RESPONSE);
1175     rwrm->reserved = htonl (0);
1176     rwrm->trail_id = m->trail_id;
1177     if (0 == layer)
1178       (void) GDS_DATACACHE_get_random_key (&rwrm->location);
1179     else
1180     {
1181       struct FingerTable *ft;
1182
1183       ft = &fingers[layer-1];
1184       if (0 == ft->number_valid_fingers)
1185       {
1186         GNUNET_CRYPTO_hash_create_random (GNUNET_CRYPTO_QUALITY_NONCE,
1187                                           &rwrm->location);
1188       }
1189       else
1190       {
1191         struct Finger *f;
1192         unsigned int off;
1193         unsigned int i;
1194
1195         off = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE,
1196                                         ft->number_valid_fingers);
1197         for (i=0; (NULL == (f = ft->fingers[i])) || (off > 0); i++)
1198           if (NULL != f) off--;
1199         rwrm->location = f->destination;
1200       }
1201     }
1202     GNUNET_MQ_send (pred->mq,
1203                     env);
1204   }
1205   else
1206   {
1207     struct GNUNET_MQ_Envelope *env;
1208     struct RandomWalkMessage *rwm;
1209     struct FriendInfo *succ;
1210
1211     /* extend the trail by another random hop */
1212     succ = pick_random_friend ();
1213     GNUNET_CRYPTO_hash_create_random (GNUNET_CRYPTO_QUALITY_NONCE,
1214                                       &t->succ_id);
1215     t->succ = succ;
1216     if (GNUNET_OK !=
1217         GNUNET_CONTAINER_multihashmap_put (trail_map,
1218                                            &t->succ_id,
1219                                            t,
1220                                            GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY))
1221     {
1222       GNUNET_break (0);
1223       GNUNET_CONTAINER_MDLL_remove (pred,
1224                                     pred->pred_head,
1225                                     pred->pred_tail,
1226                                     t);
1227       GNUNET_free (t);
1228       return GNUNET_OK;
1229     }
1230     GNUNET_CONTAINER_MDLL_insert (succ,
1231                                   succ->succ_head,
1232                                   succ->succ_tail,
1233                                   t);
1234     env = GNUNET_MQ_msg (rwm,
1235                          GNUNET_MESSAGE_TYPE_WDHT_RANDOM_WALK);
1236     rwm->hops_taken = htons (1 + ntohs (m->hops_taken));
1237     rwm->layer = m->layer;
1238     rwm->trail_id = t->succ_id;
1239     GNUNET_MQ_send (succ->mq,
1240                     env);
1241   }
1242   return GNUNET_OK;
1243 }
1244
1245
1246 /**
1247  * Handle a `struct RandomWalkResponseMessage`.
1248  *
1249  * @param cls closure (NULL)
1250  * @param peer sender identity
1251  * @param message the setup response message
1252  * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
1253  */
1254 static int
1255 handle_dht_p2p_random_walk_response (void *cls,
1256                                      const struct GNUNET_PeerIdentity *peer,
1257                                      const struct GNUNET_MessageHeader *message)
1258 {
1259   const struct RandomWalkResponseMessage *rwrm;
1260   struct Trail *trail;
1261   struct FriendInfo *pred;
1262   struct FingerTable *ft;
1263   struct Finger *finger;
1264
1265   rwrm = (const struct RandomWalkResponseMessage *) message;
1266   trail = GNUNET_CONTAINER_multihashmap_get (trail_map,
1267                                              &rwrm->trail_id);
1268   if (NULL == trail)
1269   {
1270     /* TODO: log/statistics: we didn't find the trail (can happen) */
1271     return GNUNET_OK;
1272   }
1273   if (NULL != (pred = trail->pred))
1274   {
1275     /* We are not the first hop, keep forwarding */
1276     struct GNUNET_MQ_Envelope *env;
1277     struct RandomWalkResponseMessage *rwrm2;
1278
1279     env = GNUNET_MQ_msg (rwrm2,
1280                          GNUNET_MESSAGE_TYPE_WDHT_RANDOM_WALK_RESPONSE);
1281     rwrm2->reserved = htonl (0);
1282     rwrm2->location = rwrm->location;
1283     rwrm2->trail_id = trail->pred_id;
1284     GNUNET_MQ_send (pred->mq,
1285                     env);
1286     return GNUNET_OK;
1287   }
1288   /* We are the first hop, complete finger */
1289   if (NULL == (ft = trail->ft))
1290   {
1291     /* Eh, why did we create the trail if we have no FT? */
1292     GNUNET_break (0);
1293     delete_trail (trail,
1294                   GNUNET_NO,
1295                   GNUNET_YES);
1296     return GNUNET_OK;
1297   }
1298   if (NULL == (finger = ft->fingers[trail->finger_off]))
1299   {
1300     /* Eh, finger got deleted, but why not the trail as well? */
1301     GNUNET_break (0);
1302     delete_trail (trail,
1303                   GNUNET_NO,
1304                   GNUNET_YES);
1305     return GNUNET_OK;
1306   }
1307
1308
1309   // 1) lookup trail => find Finger entry => fill in 'destination' and mark valid, move to end of sorted array,
1310   //mark unsorted, update links from 'trails'
1311   /*
1312    * Steps :
1313    *  1 check if we are the correct layer
1314    *  1.a if true : add the returned value (finger) in the db structure
1315    *  1.b if true : do nothing
1316    */
1317   /* FIXME: add the value in db structure 1.a */
1318
1319   return GNUNET_OK;
1320 }
1321
1322
1323 /**
1324  * Handle a `struct TrailDestroyMessage`.
1325  *
1326  * @param cls closure (NULL)
1327  * @param peer sender identity
1328  * @param message the finger destroy message
1329  * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
1330  */
1331 static int
1332 handle_dht_p2p_trail_destroy (void *cls,
1333                              const struct GNUNET_PeerIdentity *peer,
1334                              const struct GNUNET_MessageHeader *message)
1335 {
1336   const struct TrailDestroyMessage *tdm;
1337   struct Trail *trail;
1338
1339   tdm = (const struct TrailDestroyMessage *) message;
1340   trail = GNUNET_CONTAINER_multihashmap_get (trail_map,
1341                                              &tdm->trail_id);
1342   delete_trail (trail,
1343                 ( (NULL != trail->succ) &&
1344                   (0 == memcmp (peer,
1345                                 &trail->succ->id,
1346                                 sizeof (struct GNUNET_PeerIdentity))) ),
1347                 ( (NULL != trail->pred) &&
1348                   (0 == memcmp (peer,
1349                                 &trail->pred->id,
1350                                 sizeof (struct GNUNET_PeerIdentity))) ));
1351   return GNUNET_OK;
1352 }
1353
1354
1355 /**
1356  * Handle a `struct FindSuccessorMessage` from a #GNUNET_MESSAGE_TYPE_WDHT_SUCCESSOR_FIND
1357  * message.
1358  *
1359  * @param cls closure (NULL)
1360  * @param trail_id path to the originator
1361  * @param trail_path path the message took on the trail, if available
1362  * @param trail_path_length number of entries on the @a trail_path
1363  * @param message the finger setup message
1364  * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
1365  */
1366 static int
1367 handle_dht_p2p_successor_find (void *cls,
1368                                const struct GNUNET_HashCode *trail_id,
1369                                const struct GNUNET_PeerIdentity *trail_path,
1370                                unsigned int trail_path_length,
1371                                const struct GNUNET_MessageHeader *message)
1372 {
1373   const struct FindSuccessorMessage *fsm;
1374
1375   /* We do not expect to track trails for the forward-direction
1376      of successor finding... */
1377   GNUNET_break_op (0 == trail_path_length);
1378   fsm = (const struct FindSuccessorMessage *) message;
1379   GDS_DATACACHE_get_successors (trail_id,
1380                                 &fsm->key);
1381   return GNUNET_OK;
1382 }
1383
1384
1385 /**
1386  * Handle a `struct PeerGetMessage`.
1387  *
1388  * @param cls closure (NULL)
1389  * @param trail_id path to the originator
1390  * @param trail_path path the message took on the trail, if available
1391  * @param trail_path_length number of entries on the @a trail_path
1392  * @param message the peer get message
1393  * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
1394  */
1395 static int
1396 handle_dht_p2p_peer_get (void *cls,
1397                          const struct GNUNET_HashCode *trail_id,
1398                          const struct GNUNET_PeerIdentity *trail_path,
1399                          unsigned int trail_path_length,
1400                          const struct GNUNET_MessageHeader *message)
1401 {
1402   const struct PeerGetMessage *pgm;
1403
1404   // FIXME: note: never called like this, message embedded with trail route!
1405   pgm = (const struct PeerGetMessage *) message;
1406   // -> lookup in datacache (figure out way to remember trail!)
1407      /*
1408     * steps :
1409     *   1 extract the result
1410     *   2 save the peer
1411     *   3 send it using the good trail
1412     *
1413     * What do i do when i don't have the key/value?
1414     */
1415
1416   return GNUNET_OK;
1417 }
1418
1419
1420 /**
1421  * Handle a `struct PeerGetResultMessage`.
1422  *
1423  * @param cls closure (NULL)
1424  * @param trail_id path to the originator
1425  * @param trail_path path the message took on the trail, if available
1426  * @param trail_path_length number of entries on the @a trail_path
1427  * @param message the peer get result message
1428  * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
1429  */
1430 static int
1431 handle_dht_p2p_peer_get_result (void *cls,
1432                                 const struct GNUNET_HashCode *trail_id,
1433                                 const struct GNUNET_PeerIdentity *trail_path,
1434                                 unsigned int trail_path_length,
1435                                 const struct GNUNET_MessageHeader *message)
1436 {
1437   const struct PeerGetResultMessage *pgrm;
1438
1439   pgrm = (const struct PeerGetResultMessage *) message;
1440   // pretty much: parse, & pass to client (there is some call for that...)
1441
1442 #if 0
1443   GDS_CLIENTS_process_get (options,
1444                            type,
1445                            0, 0,
1446                            path_length, path,
1447                            key);
1448   (void) GDS_DATACACHE_handle_get (trail_id,
1449                                    key,
1450                                    type,
1451                                    xquery,
1452                                    xquery_size,
1453                                    &reply_bf,
1454                                    reply_bf_mutator);
1455 #endif
1456   return GNUNET_OK;
1457 }
1458
1459
1460 /**
1461  * Handle a `struct PeerPutMessage`.
1462  *
1463  * @param cls closure (NULL)
1464  * @param trail_id path to the originator
1465  * @param trail_path path the message took on the trail, if available
1466  * @param trail_path_length number of entries on the @a trail_path
1467  * @param message the peer put message
1468  * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
1469  */
1470 static int
1471 handle_dht_p2p_peer_put (void *cls,
1472                          const struct GNUNET_HashCode *trail_id,
1473                          const struct GNUNET_PeerIdentity *trail_path,
1474                          unsigned int trail_path_length,
1475                          const struct GNUNET_MessageHeader *message)
1476 {
1477   const struct PeerGetResultMessage *pgrm;
1478
1479   pgrm = (const struct PeerGetResultMessage *) message;
1480   // parse & store in datacache, this is in response to us asking for successors.
1481   /*
1482    * steps :
1483    * 1 check the size of the message
1484    * 2 use the API to add the value in the "database". Check on the xdht file, how to do it.
1485    * 3 Did i a have to return a notification or did i have to return GNUNET_[OK|SYSERR]?
1486    */
1487 #if 0
1488   GDS_DATACACHE_handle_put (expiration_time,
1489                             key,
1490                             combined_path_length, combined_path,
1491                             block_type,
1492                             data_size,
1493                             data);
1494   GDS_CLIENTS_process_put (options,
1495                            block_type,
1496                            0, 0,
1497                            combined_path_length, combined_path,
1498                            expiration_time,
1499                            key,
1500                            data,
1501                            data_size);
1502 #endif
1503   return GNUNET_OK;
1504 }
1505
1506
1507 /**
1508  * Handler for a message we received along some trail.
1509  *
1510  * @param cls closure
1511  * @param trail_id trail identifier
1512  * @param trail_path path the message took on the trail, if available
1513  * @param trail_path_length number of entries on the @a trail_path
1514  * @param message the message we got
1515  * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
1516  */
1517 typedef int
1518 (*TrailHandlerCallback)(void *cls,
1519                         const struct GNUNET_HashCode *trail_id,
1520                         const struct GNUNET_PeerIdentity *trail_path,
1521                         unsigned int trail_path_length,
1522                         const struct GNUNET_MessageHeader *message);
1523
1524
1525 /**
1526  * Definition of a handler for a message received along some trail.
1527  */
1528 struct TrailHandler
1529 {
1530   /**
1531    * NULL for end-of-list.
1532    */
1533   TrailHandlerCallback callback;
1534
1535   /**
1536    * Closure for @e callback.
1537    */
1538   void *cls;
1539
1540   /**
1541    * Message type this handler addresses.
1542    */
1543   uint16_t message_type;
1544
1545   /**
1546    * Use 0 for variable-size.
1547    */
1548   uint16_t message_size;
1549 };
1550
1551
1552 /**
1553  * Handle a `struct TrailRouteMessage`.
1554  *
1555  * @param cls closure (NULL)
1556  * @param peer sender identity
1557  * @param message the finger destroy message
1558  * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
1559  */
1560 static int
1561 handle_dht_p2p_trail_route (void *cls,
1562                             const struct GNUNET_PeerIdentity *peer,
1563                             const struct GNUNET_MessageHeader *message)
1564 {
1565   static const struct TrailHandler handlers[] = {
1566     { &handle_dht_p2p_successor_find, NULL,
1567       GNUNET_MESSAGE_TYPE_WDHT_SUCCESSOR_FIND,
1568       sizeof (struct FindSuccessorMessage) },
1569     { &handle_dht_p2p_peer_get, NULL,
1570       GNUNET_MESSAGE_TYPE_WDHT_GET,
1571       0 },
1572     { &handle_dht_p2p_peer_get_result, NULL,
1573       GNUNET_MESSAGE_TYPE_WDHT_GET_RESULT,
1574       0 },
1575     { &handle_dht_p2p_peer_put, NULL,
1576       GNUNET_MESSAGE_TYPE_WDHT_PUT,
1577       0 },
1578     { NULL, NULL, 0, 0 }
1579   };
1580   unsigned int i;
1581   const struct TrailRouteMessage *trm;
1582   const struct GNUNET_PeerIdentity *path;
1583   uint16_t path_length;
1584   const struct GNUNET_MessageHeader *payload;
1585   const struct TrailHandler *th;
1586   struct Trail *trail;
1587   size_t msize;
1588
1589   /* Parse and check message is well-formed */
1590   msize = ntohs (message->size);
1591   if (msize < sizeof (struct TrailRouteMessage))
1592   {
1593     GNUNET_break_op (0);
1594     return GNUNET_YES;
1595   }
1596   trm = (const struct TrailRouteMessage *) message;
1597   path_length = ntohs (trm->path_length);
1598   if (msize < sizeof (struct TrailRouteMessage) +
1599       path_length * sizeof (struct GNUNET_PeerIdentity) +
1600       sizeof (struct GNUNET_MessageHeader) )
1601   {
1602     GNUNET_break_op (0);
1603     return GNUNET_YES;
1604   }
1605   path = (const struct GNUNET_PeerIdentity *) &trm[1];
1606   payload = (const struct GNUNET_MessageHeader *) &path[path_length];
1607   if (msize != (ntohs (payload->size) +
1608                 sizeof (struct TrailRouteMessage) +
1609                 path_length * sizeof (struct GNUNET_PeerIdentity)))
1610   {
1611     GNUNET_break_op (0);
1612     return GNUNET_YES;
1613   }
1614
1615   /* Is this message for us? */
1616   trail = GNUNET_CONTAINER_multihashmap_get (trail_map,
1617                                              &trm->trail_id);
1618   if ( (NULL != trail->pred) &&
1619        (0 == memcmp (peer,
1620                      &trail->pred->id,
1621                      sizeof (struct GNUNET_PeerIdentity))) )
1622   {
1623     /* forward to 'successor' */
1624     if (NULL != trail->succ)
1625     {
1626       forward_message_on_trail (trail->succ,
1627                                 &trail->succ_id,
1628                                 ntohs (trm->record_path),
1629                                 peer,
1630                                 path,
1631                                 path_length,
1632                                 payload);
1633       return GNUNET_OK;
1634     }
1635   }
1636   else
1637   {
1638     /* forward to 'predecessor' */
1639     GNUNET_break_op ( (NULL != trail->succ) &&
1640                       (0 == memcmp (peer,
1641                                     &trail->succ->id,
1642                                     sizeof (struct GNUNET_PeerIdentity))) );
1643     if (NULL != trail->pred)
1644     {
1645       forward_message_on_trail (trail->pred,
1646                                 &trail->pred_id,
1647                                 ntohs (trm->record_path),
1648                                 peer,
1649                                 path,
1650                                 path_length,
1651                                 payload);
1652       return GNUNET_OK;
1653     }
1654   }
1655
1656   /* Message is for us, dispatch to handler */
1657   th = NULL;
1658   for (i=0; NULL != handlers[i].callback; i++)
1659   {
1660     th = &handlers[i];
1661     if (ntohs (payload->type) == th->message_type)
1662     {
1663       if ( (0 == th->message_size) ||
1664            (ntohs (payload->size) == th->message_size) )
1665         th->callback (th->cls,
1666                       &trm->trail_id,
1667                       path,
1668                       path_length,
1669                       payload);
1670       else
1671         GNUNET_break_op (0);
1672       break;
1673     }
1674   }
1675   GNUNET_break_op (NULL != th);
1676   return GNUNET_OK;
1677 }
1678
1679
1680 /**
1681  * Initialize neighbours subsystem.
1682  *
1683  * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
1684  */
1685 int
1686 GDS_NEIGHBOURS_init (void)
1687 {
1688   static const struct GNUNET_CORE_MessageHandler core_handlers[] = {
1689     { &handle_dht_p2p_random_walk,
1690       GNUNET_MESSAGE_TYPE_WDHT_RANDOM_WALK,
1691       sizeof (struct RandomWalkMessage) },
1692     { &handle_dht_p2p_random_walk_response,
1693       GNUNET_MESSAGE_TYPE_WDHT_RANDOM_WALK_RESPONSE,
1694       sizeof (struct RandomWalkResponseMessage) },
1695     { &handle_dht_p2p_trail_destroy,
1696       GNUNET_MESSAGE_TYPE_WDHT_TRAIL_DESTROY,
1697       sizeof (struct TrailDestroyMessage) },
1698     { &handle_dht_p2p_trail_route,
1699       GNUNET_MESSAGE_TYPE_WDHT_TRAIL_ROUTE,
1700       0},
1701     {NULL, 0, 0}
1702   };
1703
1704   core_api =
1705     GNUNET_CORE_connect (GDS_cfg, NULL,
1706                          &core_init,
1707                          &handle_core_connect,
1708                          &handle_core_disconnect,
1709                          NULL, GNUNET_NO,
1710                          NULL, GNUNET_NO,
1711                          core_handlers);
1712
1713   if (NULL == core_api)
1714     return GNUNET_SYSERR;
1715   friends_peermap = GNUNET_CONTAINER_multipeermap_create (256, GNUNET_NO);
1716   trail_map = GNUNET_CONTAINER_multihashmap_create (1024, GNUNET_YES);
1717   trail_heap = GNUNET_CONTAINER_heap_create (GNUNET_CONTAINER_HEAP_ORDER_MIN);
1718   return GNUNET_OK;
1719 }
1720
1721
1722 /**
1723  * Shutdown neighbours subsystem.
1724  */
1725 void
1726 GDS_NEIGHBOURS_done (void)
1727 {
1728   if (NULL == core_api)
1729     return;
1730   GNUNET_CORE_disconnect (core_api);
1731   core_api = NULL;
1732   GNUNET_assert (0 == GNUNET_CONTAINER_multipeermap_size (friends_peermap));
1733   GNUNET_CONTAINER_multipeermap_destroy (friends_peermap);
1734   friends_peermap = NULL;
1735   GNUNET_assert (0 == GNUNET_CONTAINER_multihashmap_size (trail_map));
1736   GNUNET_CONTAINER_multihashmap_destroy (trail_map);
1737   trail_map = NULL;
1738   GNUNET_CONTAINER_heap_destroy (trail_heap);
1739   trail_heap = NULL;
1740   if (NULL != trail_timeout_task)
1741   {
1742     GNUNET_SCHEDULER_cancel (trail_timeout_task);
1743     trail_timeout_task = NULL;
1744   }
1745 }
1746
1747
1748 /**
1749  * Get my identity
1750  *
1751  * @return my identity
1752  */
1753 struct GNUNET_PeerIdentity
1754 GDS_NEIGHBOURS_get_my_id (void)
1755 {
1756   return my_identity;
1757 }
1758
1759 /* end of gnunet-service-wdht_neighbours.c */