summaryrefslogtreecommitdiff
path: root/src/core/gnunet-service-core.c
blob: 0afc75addcf54f3e63cdafc41a8e7e2d368426a3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
/*
     This file is part of GNUnet.
     Copyright (C) 2009, 2010, 2011, 2016 GNUnet e.V.

     GNUnet is free software: you can redistribute it and/or modify it
     under the terms of the GNU Affero General Public License as published
     by the Free Software Foundation, either version 3 of the License,
     or (at your option) any later version.

     GNUnet is distributed in the hope that it will be useful, but
     WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     Affero General Public License for more details.
    
     You should have received a copy of the GNU Affero General Public License
     along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/**
 * @file core/gnunet-service-core.c
 * @brief high-level P2P messaging
 * @author Christian Grothoff
 */
#include "platform.h"
#include <gcrypt.h>
#include "gnunet_util_lib.h"
#include "gnunet-service-core.h"
#include "gnunet-service-core_kx.h"
#include "gnunet-service-core_sessions.h"
#include "gnunet-service-core_typemap.h"

/**
 * How many messages do we queue up at most for any client? This can
 * cause messages to be dropped if clients do not process them fast
 * enough!  Note that this is a soft limit; we try
 * to keep a few larger messages above the limit.
 */
#define SOFT_MAX_QUEUE 128

/**
 * How many messages do we queue up at most for any client? This can
 * cause messages to be dropped if clients do not process them fast
 * enough!  Note that this is the hard limit.
 */
#define HARD_MAX_QUEUE 256


/**
 * Data structure for each client connected to the CORE service.
 */
struct GSC_Client
{
  /**
   * Clients are kept in a linked list.
   */
  struct GSC_Client *next;

  /**
   * Clients are kept in a linked list.
   */
  struct GSC_Client *prev;

  /**
   * Handle for the client with the server API.
   */
  struct GNUNET_SERVICE_Client *client;

  /**
   * Message queue to talk to @e client.
   */
  struct GNUNET_MQ_Handle *mq;

  /**
   * Array of the types of messages this peer cares
   * about (with @e tcnt entries).  Allocated as part
   * of this client struct, do not free!
   */
  uint16_t *types;

  /**
   * Map of peer identities to active transmission requests of this
   * client to the peer (of type `struct GSC_ClientActiveRequest`).
   */
  struct GNUNET_CONTAINER_MultiPeerMap *requests;

  /**
   * Map containing all peers that this client knows we're connected to.
   */
  struct GNUNET_CONTAINER_MultiPeerMap *connectmap;

  /**
   * Options for messages this client cares about,
   * see GNUNET_CORE_OPTION_ values.
   */
  uint32_t options;

  /**
   * Have we gotten the #GNUNET_MESSAGE_TYPE_CORE_INIT message
   * from this client already?
   */
  int got_init;

  /**
   * Number of types of incoming messages this client
   * specifically cares about.  Size of the @e types array.
   */
  unsigned int tcnt;

};


/**
 * Our identity.
 */
struct GNUNET_PeerIdentity GSC_my_identity;

/**
 * Our configuration.
 */
const struct GNUNET_CONFIGURATION_Handle *GSC_cfg;

/**
 * For creating statistics.
 */
struct GNUNET_STATISTICS_Handle *GSC_stats;

/**
 * Big "or" of all client options.
 */
static uint32_t all_client_options;

/**
 * Head of linked list of our clients.
 */
static struct GSC_Client *client_head;

/**
 * Tail of linked list of our clients.
 */
static struct GSC_Client *client_tail;


/**
 * Test if the client is interested in messages of the given type.
 *
 * @param type message type
 * @param c client to test
 * @return #GNUNET_YES if @a c is interested, #GNUNET_NO if not.
 */
static int
type_match (uint16_t type,
	    struct GSC_Client *c)
{
  if ( (0 == c->tcnt) &&
       (0 != c->options) )
    return GNUNET_YES;          /* peer without handlers and inbound/outbond
				   callbacks matches ALL */
  if (NULL == c->types)
    return GNUNET_NO;
  for (unsigned int i = 0; i < c->tcnt; i++)
    if (type == c->types[i])
      return GNUNET_YES;
  return GNUNET_NO;
}


/**
 * Check #GNUNET_MESSAGE_TYPE_CORE_INIT request.
 *
 * @param cls client that sent #GNUNET_MESSAGE_TYPE_CORE_INIT
 * @param im the `struct InitMessage`
 * @return #GNUNET_OK if @a im is well-formed
 */
static int
check_client_init (void *cls,
		   const struct InitMessage *im)
{
  return GNUNET_OK;
}


/**
 * Handle #GNUNET_MESSAGE_TYPE_CORE_INIT request.
 *
 * @param cls client that sent #GNUNET_MESSAGE_TYPE_CORE_INIT
 * @param im the `struct InitMessage`
 */
static void
handle_client_init (void *cls,
                    const struct InitMessage *im)
{
  struct GSC_Client *c = cls;
  struct GNUNET_MQ_Envelope *env;
  struct InitReplyMessage *irm;
  uint16_t msize;
  const uint16_t *types;

  /* check that we don't have an entry already */
  msize = ntohs (im->header.size) - sizeof (struct InitMessage);
  types = (const uint16_t *) &im[1];
  c->tcnt = msize / sizeof (uint16_t);
  c->options = ntohl (im->options);
  c->got_init = GNUNET_YES;
  all_client_options |= c->options;
  c->types = GNUNET_malloc (msize);
  GNUNET_assert (GNUNET_YES ==
                 GNUNET_CONTAINER_multipeermap_put (c->connectmap,
                                                    &GSC_my_identity,
                                                    NULL,
                                                    GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
  for (unsigned int i = 0; i < c->tcnt; i++)
    c->types[i] = ntohs (types[i]);
  GSC_TYPEMAP_add (c->types,
		   c->tcnt);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Client connecting to core service is interested in %u message types\n",
              (unsigned int) c->tcnt);
  /* send init reply message */
  env = GNUNET_MQ_msg (irm,
		       GNUNET_MESSAGE_TYPE_CORE_INIT_REPLY);
  irm->reserved = htonl (0);
  irm->my_identity = GSC_my_identity;
  GNUNET_MQ_send (c->mq,
		  env);
  GSC_SESSIONS_notify_client_about_sessions (c);
  GNUNET_SERVICE_client_continue (c->client);
}


/**
 * We will never be ready to transmit the given message in (disconnect
 * or invalid request).  Frees resources associated with @a car.  We
 * don't explicitly tell the client, he'll learn with the disconnect
 * (or violated the protocol).
 *
 * @param car request that now permanently failed; the
 *        responsibility for the handle is now returned
 *        to CLIENTS (SESSIONS is done with it).
 * @param drop_client #GNUNET_YES if the client violated the protocol
 *        and we should thus drop the connection
 */
void
GSC_CLIENTS_reject_request (struct GSC_ClientActiveRequest *car,
                            int drop_client)
{
  GNUNET_assert (GNUNET_YES ==
                 GNUNET_CONTAINER_multipeermap_remove (car->
                                                       client_handle->requests,
                                                       &car->target,
                                                       car));
  if (GNUNET_YES == drop_client)
    GNUNET_SERVICE_client_drop (car->client_handle->client);
  GNUNET_free (car);
}


/**
 * Tell a client that we are ready to receive the message.
 *
 * @param car request that is now ready; the responsibility
 *        for the handle remains shared between CLIENTS
 *        and SESSIONS after this call.
 */
void
GSC_CLIENTS_solicit_request (struct GSC_ClientActiveRequest *car)
{
  struct GSC_Client *c;
  struct GNUNET_MQ_Envelope *env;
  struct SendMessageReady *smr;
  struct GNUNET_TIME_Relative delay;
  struct GNUNET_TIME_Relative left;

  c = car->client_handle;
  if (GNUNET_YES !=
      GNUNET_CONTAINER_multipeermap_contains (c->connectmap,
                                              &car->target))
  {
    /* connection has gone down since, drop request */
    GNUNET_assert (0 !=
                   memcmp (&car->target,
                           &GSC_my_identity,
                           sizeof (struct GNUNET_PeerIdentity)));
    GSC_SESSIONS_dequeue_request (car);
    GSC_CLIENTS_reject_request (car,
                                GNUNET_NO);
    return;
  }
  delay = GNUNET_TIME_absolute_get_duration (car->received_time);
  left = GNUNET_TIME_absolute_get_duration (car->deadline);
  if (delay.rel_value_us > GNUNET_CONSTANTS_LATENCY_WARN.rel_value_us)
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                "Client waited %s for permission to transmit to `%s'%s (priority %u)\n",
                GNUNET_STRINGS_relative_time_to_string (delay,
                                                        GNUNET_YES),
                GNUNET_i2s (&car->target),
                (0 == left.rel_value_us)
                ? " (past deadline)"
                : "",
                car->priority);
  env = GNUNET_MQ_msg (smr,
		       GNUNET_MESSAGE_TYPE_CORE_SEND_READY);
  smr->size = htons (car->msize);
  smr->smr_id = car->smr_id;
  smr->peer = car->target;
  GNUNET_MQ_send (c->mq,
		  env);
}


/**
 * Handle #GNUNET_MESSAGE_TYPE_CORE_SEND_REQUEST message.
 *
 * @param cls client that sent a #GNUNET_MESSAGE_TYPE_CORE_SEND_REQUEST
 * @param req the `struct SendMessageRequest`
 */
static void
handle_client_send_request (void *cls,
                            const struct SendMessageRequest *req)
{
  struct GSC_Client *c = cls;
  struct GSC_ClientActiveRequest *car;
  int is_loopback;

  if (NULL == c->requests)
    c->requests = GNUNET_CONTAINER_multipeermap_create (16,
                                                        GNUNET_NO);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Client asked for transmission to `%s'\n",
              GNUNET_i2s (&req->peer));
  is_loopback =
      (0 ==
       memcmp (&req->peer,
               &GSC_my_identity,
               sizeof (struct GNUNET_PeerIdentity)));
  if ((! is_loopback) &&
      (GNUNET_YES !=
       GNUNET_CONTAINER_multipeermap_contains (c->connectmap,
                                               &req->peer)))
  {
    /* neighbour must have disconnected since request was issued,
     * ignore (client will realize it once it processes the
     * disconnect notification) */
    GNUNET_STATISTICS_update (GSC_stats,
                              gettext_noop
                              ("# send requests dropped (disconnected)"), 1,
                              GNUNET_NO);
    GNUNET_SERVICE_client_continue (c->client);
    return;
  }

  car = GNUNET_CONTAINER_multipeermap_get (c->requests,
                                           &req->peer);
  if (NULL == car)
  {
    /* create new entry */
    car = GNUNET_new (struct GSC_ClientActiveRequest);
    GNUNET_assert (GNUNET_OK ==
                   GNUNET_CONTAINER_multipeermap_put (c->requests,
                                                      &req->peer,
                                                      car,
                                                      GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST));
    car->client_handle = c;
  }
  else
  {
    /* dequeue and recycle memory from pending request, there can only
       be at most one per client and peer */
    GNUNET_STATISTICS_update (GSC_stats,
                              gettext_noop ("# dequeuing CAR (duplicate request)"),
			      1,
                              GNUNET_NO);
    GSC_SESSIONS_dequeue_request (car);
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Transmission request to `%s' was a duplicate!\n",
                GNUNET_i2s (&req->peer));
  }
  car->target = req->peer;
  car->received_time = GNUNET_TIME_absolute_get ();
  car->deadline = GNUNET_TIME_absolute_ntoh (req->deadline);
  car->priority = (enum GNUNET_CORE_Priority) ntohl (req->priority);
  car->msize = ntohs (req->size);
  car->smr_id = req->smr_id;
  car->was_solicited = GNUNET_NO;
  GNUNET_SERVICE_client_continue (c->client);
  if (is_loopback)
  {
    /* loopback, satisfy immediately */
    GSC_CLIENTS_solicit_request (car);
    return;
  }
  GSC_SESSIONS_queue_request (car);
}


/**
 * Closure for the #client_tokenizer_callback().
 */
struct TokenizerContext
{

  /**
   * Active request handle for the message.
   */
  struct GSC_ClientActiveRequest *car;

  /**
   * How important is this message.
   */
  enum GNUNET_CORE_Priority priority;

  /**
   * Is corking allowed (set only once we have the real message).
   */
  int cork;

};


/**
 * Functions with this signature are called whenever a complete
 * message is received by the tokenizer.  Used by
 * #handle_client_send() for dispatching messages from clients to
 * either the SESSION subsystem or other CLIENT (for loopback).
 *
 * @param cls reservation request (`struct TokenizerContext`)
 * @param message the actual message
 * @return #GNUNET_OK on success,
 *    #GNUNET_NO to stop further processing (no error)
 *    #GNUNET_SYSERR to stop further processing with error
 */
static int
tokenized_cb (void *cls,
	      const struct GNUNET_MessageHeader *message)
{
  struct TokenizerContext *tc = cls;
  struct GSC_ClientActiveRequest *car = tc->car;
  char buf[92];

  GNUNET_snprintf (buf,
		   sizeof (buf),
		   gettext_noop ("# bytes of messages of type %u received"),
		   (unsigned int) ntohs (message->type));
  GNUNET_STATISTICS_update (GSC_stats,
                            buf,
                            ntohs (message->size),
                            GNUNET_NO);
  if (0 ==
      memcmp (&car->target,
              &GSC_my_identity,
              sizeof (struct GNUNET_PeerIdentity)))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Delivering message of type %u to myself\n",
                ntohs (message->type));
    GSC_CLIENTS_deliver_message (&GSC_my_identity,
				 message,
				 ntohs (message->size),
				 GNUNET_CORE_OPTION_SEND_FULL_OUTBOUND);
    GSC_CLIENTS_deliver_message (&GSC_my_identity,
				 message,
				 sizeof (struct GNUNET_MessageHeader),
				 GNUNET_CORE_OPTION_SEND_HDR_OUTBOUND);
    GSC_CLIENTS_deliver_message (&GSC_my_identity,
				 message,
				 ntohs (message->size),
				 GNUNET_CORE_OPTION_SEND_FULL_INBOUND);
    GSC_CLIENTS_deliver_message (&GSC_my_identity,
				 message,
				 sizeof (struct GNUNET_MessageHeader),
				 GNUNET_CORE_OPTION_SEND_HDR_INBOUND);
  }
  else
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Delivering message of type %u and size %u to %s\n",
                ntohs (message->type),
		ntohs (message->size),
                GNUNET_i2s (&car->target));
    GSC_CLIENTS_deliver_message (&car->target,
				 message,
				 ntohs (message->size),
				 GNUNET_CORE_OPTION_SEND_FULL_OUTBOUND);
    GSC_CLIENTS_deliver_message (&car->target,
				 message,
				 sizeof (struct GNUNET_MessageHeader),
				 GNUNET_CORE_OPTION_SEND_HDR_OUTBOUND);
    GSC_SESSIONS_transmit (car,
                           message,
                           tc->cork,
                           tc->priority);
  }
  return GNUNET_OK;
}


/**
 * Check #GNUNET_MESSAGE_TYPE_CORE_SEND request.
 *
 * @param cls the `struct GSC_Client`
 * @param sm the `struct SendMessage`
 * @return #GNUNET_OK if @a sm is well-formed
 */
static int
check_client_send (void *cls,
		   const struct SendMessage *sm)
{
  return GNUNET_OK;
}


/**
 * Handle #GNUNET_MESSAGE_TYPE_CORE_SEND request.
 *
 * @param cls the `struct GSC_Client`
 * @param sm the `struct SendMessage`
 */
static void
handle_client_send (void *cls,
		    const struct SendMessage *sm)
{
  struct GSC_Client *c = cls;
  struct TokenizerContext tc;
  uint16_t msize;
  struct GNUNET_TIME_Relative delay;
  struct GNUNET_MessageStreamTokenizer *mst;

  msize = ntohs (sm->header.size) - sizeof (struct SendMessage);
  GNUNET_break (0 == ntohl (sm->reserved));
  tc.car = GNUNET_CONTAINER_multipeermap_get (c->requests,
					      &sm->peer);
  if (NULL == tc.car)
  {
    /* Must have been that we first approved the request, then got disconnected
     * (which triggered removal of the 'car') and now the client gives us a message
     * just *before* the client learns about the disconnect.  Theoretically, we
     * might also now be *again* connected.  So this can happen (but should be
     * rare).  If it does happen, the message is discarded. */
    GNUNET_STATISTICS_update (GSC_stats,
                              gettext_noop ("# messages discarded (session disconnected)"),
                              1,
			      GNUNET_NO);
    GNUNET_SERVICE_client_continue (c->client);
    return;
  }
  delay = GNUNET_TIME_absolute_get_duration (tc.car->received_time);
  tc.cork = ntohl (sm->cork);
  tc.priority = (enum GNUNET_CORE_Priority) ntohl (sm->priority);
  if (delay.rel_value_us > GNUNET_CONSTANTS_LATENCY_WARN.rel_value_us)
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                "Client waited %s for transmission of %u bytes to `%s'%s\n",
                GNUNET_STRINGS_relative_time_to_string (delay,
                                                        GNUNET_YES),
                msize,
                GNUNET_i2s (&sm->peer),
                tc.cork ? " (cork)" : " (uncorked)");
  else
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Client waited %s for transmission of %u bytes to `%s'%s\n",
                GNUNET_STRINGS_relative_time_to_string (delay,
                                                        GNUNET_YES),
                msize,
                GNUNET_i2s (&sm->peer),
                tc.cork ? " (cork)" : " (uncorked)");

  GNUNET_assert (GNUNET_YES ==
                 GNUNET_CONTAINER_multipeermap_remove (c->requests,
                                                       &sm->peer,
                                                       tc.car));
  mst = GNUNET_MST_create (&tokenized_cb,
			   &tc);
  GNUNET_MST_from_buffer (mst,
			  (const char *) &sm[1],
			  msize,
			  GNUNET_YES,
			  GNUNET_NO);
  GNUNET_MST_destroy (mst);
  GSC_SESSIONS_dequeue_request (tc.car);
  GNUNET_free (tc.car);
  GNUNET_SERVICE_client_continue (c->client);
}


/**
 * Free client request records.
 *
 * @param cls NULL
 * @param key identity of peer for which this is an active request
 * @param value the `struct GSC_ClientActiveRequest` to free
 * @return #GNUNET_YES (continue iteration)
 */
static int
destroy_active_client_request (void *cls,
			       const struct GNUNET_PeerIdentity *key,
                               void *value)
{
  struct GSC_ClientActiveRequest *car = value;

  GNUNET_assert (GNUNET_YES ==
                 GNUNET_CONTAINER_multipeermap_remove (car->
                                                       client_handle->requests,
                                                       &car->target,
                                                       car));
  GSC_SESSIONS_dequeue_request (car);
  GNUNET_free (car);
  return GNUNET_YES;
}


/**
 * A client connected, set up.
 *
 * @param cls closure
 * @param client identification of the client
 * @param mq message queue to talk to @a client
 * @return our client handle
 */
static void *
client_connect_cb (void *cls,
		   struct GNUNET_SERVICE_Client *client,
		   struct GNUNET_MQ_Handle *mq)
{
  struct GSC_Client *c;

  c = GNUNET_new (struct GSC_Client);
  c->client = client;
  c->mq = mq;
  c->connectmap = GNUNET_CONTAINER_multipeermap_create (16,
							GNUNET_NO);
  GNUNET_CONTAINER_DLL_insert (client_head,
			       client_tail,
			       c);
  return c;
}


/**
 * A client disconnected, clean up.
 *
 * @param cls closure
 * @param client identification of the client
 * @param app_ctx our `struct GST_Client` for @a client
 */
static void
client_disconnect_cb (void *cls,
		      struct GNUNET_SERVICE_Client *client,
		      void *app_ctx)
{
  struct GSC_Client *c = app_ctx;

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Client %p has disconnected from core service.\n",
              client);
  GNUNET_CONTAINER_DLL_remove (client_head,
			       client_tail,
			       c);
  if (NULL != c->requests)
  {
    GNUNET_CONTAINER_multipeermap_iterate (c->requests,
                                           &destroy_active_client_request,
                                           NULL);
    GNUNET_CONTAINER_multipeermap_destroy (c->requests);
  }
  GNUNET_CONTAINER_multipeermap_destroy (c->connectmap);
  c->connectmap = NULL;
  if (NULL != c->types)
  {
    GSC_TYPEMAP_remove (c->types,
			c->tcnt);
    GNUNET_free (c->types);
  }
  GNUNET_free (c);

  /* recalculate 'all_client_options' */
  all_client_options = 0;
  for (c = client_head; NULL != c ; c = c->next)
    all_client_options |= c->options;
}


/**
 * Notify a particular client about a change to existing connection to
 * one of our neighbours (check if the client is interested).  Called
 * from #GSC_SESSIONS_notify_client_about_sessions().
 *
 * @param client client to notify
 * @param neighbour identity of the neighbour that changed status
 * @param tmap_old previous type map for the neighbour, NULL for connect
 * @param tmap_new updated type map for the neighbour, NULL for disconnect
 */
void
GSC_CLIENTS_notify_client_about_neighbour (struct GSC_Client *client,
                                           const struct GNUNET_PeerIdentity *neighbour,
                                           const struct GSC_TypeMap *tmap_old,
                                           const struct GSC_TypeMap *tmap_new)
{
  struct GNUNET_MQ_Envelope *env;
  int old_match;
  int new_match;

  if (GNUNET_YES != client->got_init)
    return;
  old_match = GSC_TYPEMAP_test_match (tmap_old,
				      client->types,
				      client->tcnt);
  new_match = GSC_TYPEMAP_test_match (tmap_new,
				      client->types,
				      client->tcnt);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Notifying client about neighbour %s (%d/%d)\n",
              GNUNET_i2s (neighbour),
              old_match,
              new_match);
  if (old_match == new_match)
  {
    GNUNET_assert (old_match ==
                   GNUNET_CONTAINER_multipeermap_contains (client->connectmap,
                                                           neighbour));
    return;                     /* no change */
  }
  if (GNUNET_NO == old_match)
  {
    struct ConnectNotifyMessage *cnm;

    /* send connect */
    GNUNET_assert (GNUNET_NO ==
                   GNUNET_CONTAINER_multipeermap_contains (client->connectmap,
                                                           neighbour));
    GNUNET_assert (GNUNET_YES ==
                   GNUNET_CONTAINER_multipeermap_put (client->connectmap,
                                                      neighbour,
                                                      NULL,
                                                      GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
    env = GNUNET_MQ_msg (cnm,
			 GNUNET_MESSAGE_TYPE_CORE_NOTIFY_CONNECT);
    cnm->reserved = htonl (0);
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Sending NOTIFY_CONNECT message about peer %s to client.\n",
                GNUNET_i2s (neighbour));
    cnm->peer = *neighbour;
    GNUNET_MQ_send (client->mq,
		    env);
  }
  else
  {
    struct DisconnectNotifyMessage *dcm;

    /* send disconnect */
    GNUNET_assert (GNUNET_YES ==
                   GNUNET_CONTAINER_multipeermap_contains (client->connectmap,
                                                           neighbour));
    GNUNET_assert (GNUNET_YES ==
                   GNUNET_CONTAINER_multipeermap_remove (client->connectmap,
                                                         neighbour,
                                                         NULL));
    env = GNUNET_MQ_msg (dcm,
			 GNUNET_MESSAGE_TYPE_CORE_NOTIFY_DISCONNECT);
    dcm->reserved = htonl (0);
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Sending NOTIFY_DISCONNECT message about peer %s to client.\n",
                GNUNET_i2s (neighbour));
    dcm->peer = *neighbour;
    GNUNET_MQ_send (client->mq,
		    env);
  }
}


/**
 * Notify all clients about a change to existing session.
 * Called from SESSIONS whenever there is a change in sessions
 * or types processed by the respective peer.
 *
 * @param neighbour identity of the neighbour that changed status
 * @param tmap_old previous type map for the neighbour, NULL for connect
 * @param tmap_new updated type map for the neighbour, NULL for disconnect
 */
void
GSC_CLIENTS_notify_clients_about_neighbour (const struct GNUNET_PeerIdentity *neighbour,
                                            const struct GSC_TypeMap *tmap_old,
                                            const struct GSC_TypeMap *tmap_new)
{
  struct GSC_Client *c;

  for (c = client_head; NULL != c; c = c->next)
    GSC_CLIENTS_notify_client_about_neighbour (c,
					       neighbour,
                                               tmap_old,
					       tmap_new);
}


/**
 * Deliver P2P message to interested clients.  Caller must have checked
 * that the sending peer actually lists the given message type as one
 * of its types.
 *
 * @param sender peer who sent us the message
 * @param msg the message
 * @param msize number of bytes to transmit
 * @param options options for checking which clients should
 *        receive the message
 */
void
GSC_CLIENTS_deliver_message (const struct GNUNET_PeerIdentity *sender,
                             const struct GNUNET_MessageHeader *msg,
                             uint16_t msize,
                             uint32_t options)
{
  size_t size = msize + sizeof (struct NotifyTrafficMessage);

  if (size >= GNUNET_MAX_MESSAGE_SIZE)
  {
    GNUNET_break (0);
    return;
  }
  if (! ( (0 != (all_client_options & options)) ||
	  (0 != (options & GNUNET_CORE_OPTION_SEND_FULL_INBOUND)) ))
    return; /* no client cares about this message notification */
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Core service passes message from `%s' of type %u to client.\n",
              GNUNET_i2s (sender),
              (unsigned int) ntohs (msg->type));
  GSC_SESSIONS_add_to_typemap (sender,
			       ntohs (msg->type));

  for (struct GSC_Client *c = client_head; NULL != c; c = c->next)
  {
    struct GNUNET_MQ_Envelope *env;
    struct NotifyTrafficMessage *ntm;
    uint16_t mtype;
    unsigned int qlen;
    int tm;

    tm = type_match (ntohs (msg->type),
		     c);
    if (! ( (0 != (c->options & options)) ||
	    ( (0 != (options & GNUNET_CORE_OPTION_SEND_FULL_INBOUND)) &&
	      (GNUNET_YES == tm) ) ) )
      continue;  /* neither options nor type match permit the message */
    if ( (0 != (options & GNUNET_CORE_OPTION_SEND_HDR_INBOUND)) &&
	 ( (0 != (c->options & GNUNET_CORE_OPTION_SEND_FULL_INBOUND)) ||
	   (GNUNET_YES == tm) ) )
      continue;
    if ( (0 != (options & GNUNET_CORE_OPTION_SEND_HDR_OUTBOUND)) &&
	 (0 != (c->options & GNUNET_CORE_OPTION_SEND_FULL_OUTBOUND)) )
      continue;

    /* Drop messages if:
       1) We are above the hard limit, or
       2) We are above the soft limit, and a coin toss limited
          to the message size (giving larger messages a
          proportionally higher chance of being queued) falls
          below the threshold. The threshold is based on where
          we are between the soft and the hard limit, scaled
          to match the range of message sizes we usually encounter
          (i.e. up to 32k); so a 64k message has a 50% chance of
          being kept if we are just barely below the hard max,
          and a 99% chance of being kept if we are at the soft max.
       The reason is to make it more likely to drop control traffic
       (ACK, queries) which may be cummulative or highly redundant,
       and cheap to drop than data traffic.  */
    qlen = GNUNET_MQ_get_length (c->mq);
    if ( (qlen >= HARD_MAX_QUEUE) ||
         ( (qlen > SOFT_MAX_QUEUE) &&
           ( (GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK,
                                        ntohs (msg->size)) ) <
             (qlen - SOFT_MAX_QUEUE) * 0x8000 /
             (HARD_MAX_QUEUE - SOFT_MAX_QUEUE) ) ) )
    {
      char buf[1024];

      GNUNET_log (GNUNET_ERROR_TYPE_INFO | GNUNET_ERROR_TYPE_BULK,
                  "Dropping decrypted message of type %u as client is too busy (queue full)\n",
                  (unsigned int) ntohs (msg->type));
      GNUNET_snprintf (buf,
                       sizeof (buf),
                       gettext_noop ("# messages of type %u discarded (client busy)"),
                       (unsigned int) ntohs (msg->type));
      GNUNET_STATISTICS_update (GSC_stats,
                                buf,
                                1,
                                GNUNET_NO);
      continue;
    }

    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Sending %u message with %u bytes to client interested in messages of type %u.\n",
		options,
		ntohs (msg->size),
                (unsigned int) ntohs (msg->type));

    if (0 != (options & (GNUNET_CORE_OPTION_SEND_FULL_INBOUND | GNUNET_CORE_OPTION_SEND_HDR_INBOUND)))
      mtype = GNUNET_MESSAGE_TYPE_CORE_NOTIFY_INBOUND;
    else
      mtype = GNUNET_MESSAGE_TYPE_CORE_NOTIFY_OUTBOUND;
    env = GNUNET_MQ_msg_extra (ntm,
			       msize,
			       mtype);
    ntm->peer = *sender;
    GNUNET_memcpy (&ntm[1],
		   msg,
		   msize);

    GNUNET_assert ( (0 == (c->options & GNUNET_CORE_OPTION_SEND_FULL_INBOUND)) ||
		    (GNUNET_YES != tm) ||
		    (GNUNET_YES ==
		     GNUNET_CONTAINER_multipeermap_contains (c->connectmap,
							     sender)) );
    GNUNET_MQ_send (c->mq,
		    env);
  }
}


/**
 * Last task run during shutdown.  Disconnects us from
 * the transport.
 *
 * @param cls NULL, unused
 */
static void
shutdown_task (void *cls)
{
  struct GSC_Client *c;

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Core service shutting down.\n");
  while (NULL != (c = client_head))
    GNUNET_SERVICE_client_drop (c->client);
  GSC_SESSIONS_done ();
  GSC_KX_done ();
  GSC_TYPEMAP_done ();
  if (NULL != GSC_stats)
  {
    GNUNET_STATISTICS_destroy (GSC_stats,
			       GNUNET_NO);
    GSC_stats = NULL;
  }
  GSC_cfg = NULL;
}


/**
 * Handle #GNUNET_MESSAGE_TYPE_CORE_MONITOR_PEERS request.  For this
 * request type, the client does not have to have transmitted an INIT
 * request.  All current peers are returned, regardless of which
 * message types they accept.
 *
 * @param cls client sending the iteration request
 * @param message iteration request message
 */
static void
handle_client_monitor_peers (void *cls,
			     const struct GNUNET_MessageHeader *message)
{
  struct GSC_Client *c = cls;

  GNUNET_SERVICE_client_continue (c->client);
  GSC_KX_handle_client_monitor_peers (c->mq);
}


/**
 * Initiate core service.
 *
 * @param cls closure
 * @param c configuration to use
 * @param service the initialized service
 */
static void
run (void *cls,
     const struct GNUNET_CONFIGURATION_Handle *c,
     struct GNUNET_SERVICE_Handle *service)
{
  struct GNUNET_CRYPTO_EddsaPrivateKey *pk;
  char *keyfile;

  GSC_cfg = c;
  if (GNUNET_OK !=
      GNUNET_CONFIGURATION_get_value_filename (GSC_cfg,
					       "PEER",
					       "PRIVATE_KEY",
                                               &keyfile))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                _("Core service is lacking HOSTKEY configuration setting.  Exiting.\n"));
    GNUNET_SCHEDULER_shutdown ();
    return;
  }
  GSC_stats = GNUNET_STATISTICS_create ("core",
					GSC_cfg);
  GNUNET_SCHEDULER_add_shutdown (&shutdown_task,
				 NULL);
  GNUNET_SERVICE_suspend (service);
  GSC_TYPEMAP_init ();
  pk = GNUNET_CRYPTO_eddsa_key_create_from_file (keyfile);
  GNUNET_free (keyfile);
  GNUNET_assert (NULL != pk);
  if (GNUNET_OK != GSC_KX_init (pk))
  {
    GNUNET_SCHEDULER_shutdown ();
    return;
  }
  GSC_SESSIONS_init ();
  GNUNET_SERVICE_resume (service);
  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              _("Core service of `%s' ready.\n"),
              GNUNET_i2s (&GSC_my_identity));
}


/**
 * Define "main" method using service macro.
 */
GNUNET_SERVICE_MAIN
("core",
 GNUNET_SERVICE_OPTION_NONE,
 &run,
 &client_connect_cb,
 &client_disconnect_cb,
 NULL,
 GNUNET_MQ_hd_var_size (client_init,
			GNUNET_MESSAGE_TYPE_CORE_INIT,
			struct InitMessage,
			NULL),
 GNUNET_MQ_hd_fixed_size (client_monitor_peers,
			  GNUNET_MESSAGE_TYPE_CORE_MONITOR_PEERS,
			  struct GNUNET_MessageHeader,
			  NULL),
 GNUNET_MQ_hd_fixed_size (client_send_request,
			  GNUNET_MESSAGE_TYPE_CORE_SEND_REQUEST,
			  struct SendMessageRequest,
			  NULL),
 GNUNET_MQ_hd_var_size (client_send,
			GNUNET_MESSAGE_TYPE_CORE_SEND,
			struct SendMessage,
			NULL),
 GNUNET_MQ_handler_end ());


/* end of gnunet-service-core.c */