aboutsummaryrefslogtreecommitdiff
path: root/src/util/mq.c
blob: 8749d5d210fdd7bb1d4049173c58ce73c6da0bd4 (plain) (blame)
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
/*
     This file is part of GNUnet.
     Copyright (C) 2012-2019 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/>.

     SPDX-License-Identifier: AGPL3.0-or-later
 */

/**
 * @author Florian Dold
 * @file util/mq.c
 * @brief general purpose request queue
 */
#include "platform.h"
#include "gnunet_util_lib.h"

#define LOG(kind, ...) GNUNET_log_from (kind, "util-mq", __VA_ARGS__)


struct GNUNET_MQ_Envelope
{
  /**
   * Messages are stored in a linked list.
   * Each queue has its own list of envelopes.
   */
  struct GNUNET_MQ_Envelope *next;

  /**
   * Messages are stored in a linked list
   * Each queue has its own list of envelopes.
   */
  struct GNUNET_MQ_Envelope *prev;

  /**
   * Actual allocated message header.
   * The GNUNET_MQ_Envelope header is allocated at
   * the end of the message.
   */
  struct GNUNET_MessageHeader *mh;

  /**
   * Queue the message is queued in, NULL if message is not queued.
   */
  struct GNUNET_MQ_Handle *parent_queue;

  /**
   * Called after the message was sent irrevocably.
   */
  GNUNET_SCHEDULER_TaskCallback sent_cb;

  /**
   * Closure for @e send_cb
   */
  void *sent_cls;

  /**
   * Flags that were set for this envelope by
   * #GNUNET_MQ_env_set_options().   Only valid if
   * @e have_custom_options is set.
   */
  enum GNUNET_MQ_PriorityPreferences priority;

  /**
   * Did the application call #GNUNET_MQ_env_set_options()?
   */
  int have_custom_options;
};


/**
 * Handle to a message queue.
 */
struct GNUNET_MQ_Handle
{
  /**
   * Handlers array, or NULL if the queue should not receive messages
   */
  struct GNUNET_MQ_MessageHandler *handlers;

  /**
   * Actual implementation of message sending,
   * called when a message is added
   */
  GNUNET_MQ_SendImpl send_impl;

  /**
   * Implementation-dependent queue destruction function
   */
  GNUNET_MQ_DestroyImpl destroy_impl;

  /**
   * Implementation-dependent send cancel function
   */
  GNUNET_MQ_CancelImpl cancel_impl;

  /**
   * Implementation-specific state
   */
  void *impl_state;

  /**
   * Callback will be called when an error occurs.
   */
  GNUNET_MQ_ErrorHandler error_handler;

  /**
   * Closure for the error handler.
   */
  void *error_handler_cls;

  /**
   * Task to asynchronously run #impl_send_continue().
   */
  struct GNUNET_SCHEDULER_Task *send_task;

  /**
   * Linked list of messages pending to be sent
   */
  struct GNUNET_MQ_Envelope *envelope_head;

  /**
   * Linked list of messages pending to be sent
   */
  struct GNUNET_MQ_Envelope *envelope_tail;

  /**
   * Message that is currently scheduled to be
   * sent. Not the head of the message queue, as the implementation
   * needs to know if sending has been already scheduled or not.
   */
  struct GNUNET_MQ_Envelope *current_envelope;

  /**
   * Map of associations, lazily allocated
   */
  struct GNUNET_CONTAINER_MultiHashMap32 *assoc_map;

  /**
   * Functions to call on queue destruction; kept in a DLL.
   */
  struct GNUNET_MQ_DestroyNotificationHandle *dnh_head;

  /**
   * Functions to call on queue destruction; kept in a DLL.
   */
  struct GNUNET_MQ_DestroyNotificationHandle *dnh_tail;

  /**
   * Flags that were set for this queue by
   * #GNUNET_MQ_set_options().   Default is 0.
   */
  enum GNUNET_MQ_PriorityPreferences priority;

  /**
   * Next id that should be used for the @e assoc_map,
   * initialized lazily to a random value together with
   * @e assoc_map
   */
  uint32_t assoc_id;

  /**
   * Number of entries we have in the envelope-DLL.
   */
  unsigned int queue_length;

  /**
   * True if GNUNET_MQ_impl_send_in_flight() was called.
   */
  bool in_flight;
};


void
GNUNET_MQ_inject_message (struct GNUNET_MQ_Handle *mq,
                          const struct GNUNET_MessageHeader *mh)
{
  enum GNUNET_GenericReturnValue ret;

  ret = GNUNET_MQ_handle_message (mq->handlers,
                                  mh);
  if (GNUNET_SYSERR == ret)
  {
    GNUNET_MQ_inject_error (mq,
                            GNUNET_MQ_ERROR_MALFORMED);
    return;
  }
}


enum GNUNET_GenericReturnValue
GNUNET_MQ_handle_message (const struct GNUNET_MQ_MessageHandler *handlers,
                          const struct GNUNET_MessageHeader *mh)
{
  bool handled = false;
  uint16_t msize = ntohs (mh->size);
  uint16_t mtype = ntohs (mh->type);

  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Received message of type %u and size %u\n",
       mtype,
       msize);
  if (NULL == handlers)
    goto done;
  for (const struct GNUNET_MQ_MessageHandler *handler = handlers;
       NULL != handler->cb;
       handler++)
  {
    if (handler->type == mtype)
    {
      handled = true;
      if ( (handler->expected_size > msize) ||
           ( (handler->expected_size != msize) &&
             (NULL == handler->mv) ) )
      {
        /* Too small, or not an exact size and
           no 'mv' handler to check rest */
        LOG (GNUNET_ERROR_TYPE_ERROR,
             "Received malformed message of type %u\n",
             (unsigned int) handler->type);
        return GNUNET_SYSERR;
      }
      if ( (NULL == handler->mv) ||
           (GNUNET_OK ==
            handler->mv (handler->cls,
                         mh)) )
      {
        /* message well-formed, pass to handler */
        handler->cb (handler->cls, mh);
      }
      else
      {
        /* Message rejected by check routine */
        LOG (GNUNET_ERROR_TYPE_ERROR,
             "Received malformed message of type %u\n",
             (unsigned int) handler->type);
        return GNUNET_SYSERR;
      }
      break;
    }
  }
done:
  if (! handled)
  {
    LOG (GNUNET_ERROR_TYPE_INFO,
         "No handler for message of type %u and size %u\n",
         mtype,
         msize);
    return GNUNET_NO;
  }
  return GNUNET_OK;
}


void
GNUNET_MQ_inject_error (struct GNUNET_MQ_Handle *mq,
                        enum GNUNET_MQ_Error error)
{
  if (NULL == mq->error_handler)
  {
    LOG (GNUNET_ERROR_TYPE_WARNING,
         "Got error %d, but no handler installed\n",
         (int) error);
    return;
  }
  mq->error_handler (mq->error_handler_cls,
                     error);
}


void
GNUNET_MQ_discard (struct GNUNET_MQ_Envelope *ev)
{
  GNUNET_assert (NULL == ev->parent_queue);
  GNUNET_free (ev);
}


unsigned int
GNUNET_MQ_get_length (struct GNUNET_MQ_Handle *mq)
{
  if (! mq->in_flight)
  {
    return mq->queue_length;
  }
  return mq->queue_length - 1;
}


void
GNUNET_MQ_send (struct GNUNET_MQ_Handle *mq,
                struct GNUNET_MQ_Envelope *ev)
{
  if (NULL == mq)
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "mq is NUll when sending message of type %u\n",
                (unsigned int) ntohs (ev->mh->type));
  GNUNET_assert (NULL != mq);
  GNUNET_assert (NULL == ev->parent_queue);

  mq->queue_length++;
  if (mq->queue_length >= 10000000)
  {
    /* This would seem like a bug... */
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "MQ with %u entries extended by message of type %u (FC broken?)\n",
                (unsigned int) mq->queue_length,
                (unsigned int) ntohs (ev->mh->type));
  }
  ev->parent_queue = mq;
  /* is the implementation busy? queue it! */
  if ((NULL != mq->current_envelope) || (NULL != mq->send_task))
  {
    GNUNET_CONTAINER_DLL_insert_tail (mq->envelope_head,
                                      mq->envelope_tail,
                                      ev);
    return;
  }
  GNUNET_assert (NULL == mq->envelope_head);
  mq->current_envelope = ev;

  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "sending message of type %u and size %u, queue empty (MQ: %p)\n",
       ntohs (ev->mh->type),
       ntohs (ev->mh->size),
       mq);

  mq->send_impl (mq,
                 ev->mh,
                 mq->impl_state);
}


struct GNUNET_MQ_Envelope *
GNUNET_MQ_unsent_head (struct GNUNET_MQ_Handle *mq)
{
  struct GNUNET_MQ_Envelope *env;

  env = mq->envelope_head;
  GNUNET_CONTAINER_DLL_remove (mq->envelope_head,
                               mq->envelope_tail,
                               env);
  mq->queue_length--;
  env->parent_queue = NULL;
  return env;
}


struct GNUNET_MQ_Envelope *
GNUNET_MQ_env_copy (struct GNUNET_MQ_Envelope *env)
{
  GNUNET_assert (NULL == env->next);
  GNUNET_assert (NULL == env->parent_queue);
  GNUNET_assert (NULL == env->sent_cb);
  GNUNET_assert (GNUNET_NO == env->have_custom_options);
  return GNUNET_MQ_msg_copy (env->mh);
}


void
GNUNET_MQ_send_copy (struct GNUNET_MQ_Handle *mq,
                     const struct GNUNET_MQ_Envelope *ev)
{
  struct GNUNET_MQ_Envelope *env;
  uint16_t msize;

  msize = ntohs (ev->mh->size);
  env = GNUNET_malloc (sizeof(struct GNUNET_MQ_Envelope) + msize);
  env->mh = (struct GNUNET_MessageHeader *) &env[1];
  env->sent_cb = ev->sent_cb;
  env->sent_cls = ev->sent_cls;
  GNUNET_memcpy (&env[1], ev->mh, msize);
  GNUNET_MQ_send (mq, env);
}


/**
 * Task run to call the send implementation for the next queued
 * message, if any.  Only useful for implementing message queues,
 * results in undefined behavior if not used carefully.
 *
 * @param cls message queue to send the next message with
 */
static void
impl_send_continue (void *cls)
{
  struct GNUNET_MQ_Handle *mq = cls;

  mq->send_task = NULL;
  /* call is only valid if we're actually currently sending
   * a message */
  if (NULL == mq->envelope_head)
    return;
  mq->current_envelope = mq->envelope_head;
  GNUNET_CONTAINER_DLL_remove (mq->envelope_head,
                               mq->envelope_tail,
                               mq->current_envelope);

  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "sending message of type %u and size %u from queue (MQ: %p)\n",
       ntohs (mq->current_envelope->mh->type),
       ntohs (mq->current_envelope->mh->size),
       mq);

  mq->send_impl (mq,
                 mq->current_envelope->mh,
                 mq->impl_state);
}


void
GNUNET_MQ_impl_send_continue (struct GNUNET_MQ_Handle *mq)
{
  struct GNUNET_MQ_Envelope *current_envelope;
  GNUNET_SCHEDULER_TaskCallback cb;

  GNUNET_assert (0 < mq->queue_length);
  mq->queue_length--;
  mq->in_flight = false;
  current_envelope = mq->current_envelope;
  current_envelope->parent_queue = NULL;
  mq->current_envelope = NULL;
  GNUNET_assert (NULL == mq->send_task);
  mq->send_task = GNUNET_SCHEDULER_add_now (&impl_send_continue, mq);
  if (NULL != (cb = current_envelope->sent_cb))
  {
    current_envelope->sent_cb = NULL;
    cb (current_envelope->sent_cls);
  }
  GNUNET_free (current_envelope);
}


void
GNUNET_MQ_impl_send_in_flight (struct GNUNET_MQ_Handle *mq)
{
  struct GNUNET_MQ_Envelope *current_envelope;
  GNUNET_SCHEDULER_TaskCallback cb;

  mq->in_flight = true;
  /* call is only valid if we're actually currently sending
   * a message */
  current_envelope = mq->current_envelope;
  GNUNET_assert (NULL != current_envelope);
  /* can't call cancel from now on anymore */
  current_envelope->parent_queue = NULL;
  if (NULL != (cb = current_envelope->sent_cb))
  {
    current_envelope->sent_cb = NULL;
    cb (current_envelope->sent_cls);
  }
}


struct GNUNET_MQ_Handle *
GNUNET_MQ_queue_for_callbacks (GNUNET_MQ_SendImpl send,
                               GNUNET_MQ_DestroyImpl destroy,
                               GNUNET_MQ_CancelImpl cancel,
                               void *impl_state,
                               const struct GNUNET_MQ_MessageHandler *handlers,
                               GNUNET_MQ_ErrorHandler error_handler,
                               void *error_handler_cls)
{
  struct GNUNET_MQ_Handle *mq;

  mq = GNUNET_new (struct GNUNET_MQ_Handle);
  mq->send_impl = send;
  mq->destroy_impl = destroy;
  mq->cancel_impl = cancel;
  mq->handlers = GNUNET_MQ_copy_handlers (handlers);
  mq->error_handler = error_handler;
  mq->error_handler_cls = error_handler_cls;
  mq->impl_state = impl_state;

  return mq;
}


void
GNUNET_MQ_set_handlers_closure (struct GNUNET_MQ_Handle *mq,
                                void *handlers_cls)
{
  if (NULL == mq->handlers)
    return;
  for (unsigned int i = 0; NULL != mq->handlers[i].cb; i++)
    mq->handlers[i].cls = handlers_cls;
}


const struct GNUNET_MessageHeader *
GNUNET_MQ_impl_current (struct GNUNET_MQ_Handle *mq)
{
  GNUNET_assert (NULL != mq->current_envelope);
  GNUNET_assert (NULL != mq->current_envelope->mh);
  return mq->current_envelope->mh;
}


void *
GNUNET_MQ_impl_state (struct GNUNET_MQ_Handle *mq)
{
  return mq->impl_state;
}


struct GNUNET_MQ_Envelope *
GNUNET_MQ_msg_ (struct GNUNET_MessageHeader **mhp,
                uint16_t size,
                uint16_t type)
{
  struct GNUNET_MQ_Envelope *ev;

  ev = GNUNET_malloc (size + sizeof(struct GNUNET_MQ_Envelope));
  ev->mh = (struct GNUNET_MessageHeader *) &ev[1];
  ev->mh->size = htons (size);
  ev->mh->type = htons (type);
  if (NULL != mhp)
    *mhp = ev->mh;
  return ev;
}


struct GNUNET_MQ_Envelope *
GNUNET_MQ_msg_copy (const struct GNUNET_MessageHeader *hdr)
{
  struct GNUNET_MQ_Envelope *mqm;
  uint16_t size = ntohs (hdr->size);

  mqm = GNUNET_malloc (sizeof(*mqm) + size);
  mqm->mh = (struct GNUNET_MessageHeader *) &mqm[1];
  GNUNET_memcpy (mqm->mh,
                 hdr,
                 size);
  return mqm;
}


struct GNUNET_MQ_Envelope *
GNUNET_MQ_msg_nested_mh_ (struct GNUNET_MessageHeader **mhp,
                          uint16_t base_size,
                          uint16_t type,
                          const struct GNUNET_MessageHeader *nested_mh)
{
  struct GNUNET_MQ_Envelope *mqm;
  uint16_t size;

  if (NULL == nested_mh)
    return GNUNET_MQ_msg_ (mhp,
                           base_size,
                           type);
  size = base_size + ntohs (nested_mh->size);
  /* check for uint16_t overflow */
  if (size < base_size)
    return NULL;
  mqm = GNUNET_MQ_msg_ (mhp,
                        size,
                        type);
  GNUNET_memcpy ((char *) mqm->mh + base_size,
                 nested_mh,
                 ntohs (nested_mh->size));
  return mqm;
}


uint32_t
GNUNET_MQ_assoc_add (struct GNUNET_MQ_Handle *mq,
                     void *assoc_data)
{
  uint32_t id;

  if (NULL == mq->assoc_map)
  {
    mq->assoc_map = GNUNET_CONTAINER_multihashmap32_create (8);
    mq->assoc_id = 1;
  }
  id = mq->assoc_id++;
  GNUNET_assert (GNUNET_OK ==
                 GNUNET_CONTAINER_multihashmap32_put (
                   mq->assoc_map,
                   id,
                   assoc_data,
                   GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
  return id;
}


/**
 * Get the data associated with a @a request_id in a queue
 *
 * @param mq the message queue with the association
 * @param request_id the request id we are interested in
 * @return the associated data
 */
void *
GNUNET_MQ_assoc_get (struct GNUNET_MQ_Handle *mq,
                     uint32_t request_id)
{
  if (NULL == mq->assoc_map)
    return NULL;
  return GNUNET_CONTAINER_multihashmap32_get (mq->assoc_map,
                                              request_id);
}


/**
 * Remove the association for a @a request_id
 *
 * @param mq the message queue with the association
 * @param request_id the request id we want to remove
 * @return the associated data
 */
void *
GNUNET_MQ_assoc_remove (struct GNUNET_MQ_Handle *mq,
                        uint32_t request_id)
{
  void *val;

  if (NULL == mq->assoc_map)
    return NULL;
  val = GNUNET_CONTAINER_multihashmap32_get (mq->assoc_map,
                                             request_id);
  GNUNET_CONTAINER_multihashmap32_remove_all (mq->assoc_map,
                                              request_id);
  return val;
}


void
GNUNET_MQ_notify_sent (struct GNUNET_MQ_Envelope *ev,
                       GNUNET_SCHEDULER_TaskCallback cb,
                       void *cb_cls)
{
  /* allow setting *OR* clearing callback */
  GNUNET_assert ((NULL == ev->sent_cb) || (NULL == cb));
  ev->sent_cb = cb;
  ev->sent_cls = cb_cls;
}


/**
 * Handle we return for callbacks registered to be
 * notified when #GNUNET_MQ_destroy() is called on a queue.
 */
struct GNUNET_MQ_DestroyNotificationHandle
{
  /**
   * Kept in a DLL.
   */
  struct GNUNET_MQ_DestroyNotificationHandle *prev;

  /**
   * Kept in a DLL.
   */
  struct GNUNET_MQ_DestroyNotificationHandle *next;

  /**
   * Queue to notify about.
   */
  struct GNUNET_MQ_Handle *mq;

  /**
   * Function to call.
   */
  GNUNET_SCHEDULER_TaskCallback cb;

  /**
   * Closure for @e cb.
   */
  void *cb_cls;
};


void
GNUNET_MQ_destroy (struct GNUNET_MQ_Handle *mq)
{
  struct GNUNET_MQ_DestroyNotificationHandle *dnh;

  if (NULL != mq->destroy_impl)
  {
    mq->destroy_impl (mq, mq->impl_state);
  }
  if (NULL != mq->send_task)
  {
    GNUNET_SCHEDULER_cancel (mq->send_task);
    mq->send_task = NULL;
  }
  while (NULL != mq->envelope_head)
  {
    struct GNUNET_MQ_Envelope *ev;

    ev = mq->envelope_head;
    ev->parent_queue = NULL;
    GNUNET_CONTAINER_DLL_remove (mq->envelope_head, mq->envelope_tail, ev);
    GNUNET_assert (0 < mq->queue_length);
    mq->queue_length--;
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "MQ destroy drops message of type %u\n",
         ntohs (ev->mh->type));
    GNUNET_MQ_discard (ev);
  }
  if (NULL != mq->current_envelope)
  {
    /* we can only discard envelopes that
     * are not queued! */
    mq->current_envelope->parent_queue = NULL;
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "MQ destroy drops current message of type %u\n",
         ntohs (mq->current_envelope->mh->type));
    GNUNET_MQ_discard (mq->current_envelope);
    mq->current_envelope = NULL;
    GNUNET_assert (0 < mq->queue_length);
    mq->queue_length--;
  }
  GNUNET_assert (0 == mq->queue_length);
  while (NULL != (dnh = mq->dnh_head))
  {
    dnh->cb (dnh->cb_cls);
    GNUNET_MQ_destroy_notify_cancel (dnh);
  }
  if (NULL != mq->assoc_map)
  {
    GNUNET_CONTAINER_multihashmap32_destroy (mq->assoc_map);
    mq->assoc_map = NULL;
  }
  GNUNET_free (mq->handlers);
  GNUNET_free (mq);
}


const struct GNUNET_MessageHeader *
GNUNET_MQ_extract_nested_mh_ (const struct GNUNET_MessageHeader *mh,
                              uint16_t base_size)
{
  uint16_t whole_size;
  uint16_t nested_size;
  const struct GNUNET_MessageHeader *nested_msg;

  whole_size = ntohs (mh->size);
  GNUNET_assert (whole_size >= base_size);
  nested_size = whole_size - base_size;
  if (0 == nested_size)
    return NULL;
  if (nested_size < sizeof(struct GNUNET_MessageHeader))
  {
    GNUNET_break_op (0);
    return NULL;
  }
  nested_msg = (const struct GNUNET_MessageHeader *) ((char *) mh + base_size);
  if (ntohs (nested_msg->size) != nested_size)
  {
    GNUNET_break_op (0);
    return NULL;
  }
  return nested_msg;
}


void
GNUNET_MQ_send_cancel (struct GNUNET_MQ_Envelope *ev)
{
  struct GNUNET_MQ_Handle *mq = ev->parent_queue;

  GNUNET_assert (NULL != mq);
  GNUNET_assert (NULL != mq->cancel_impl);
  GNUNET_assert (0 < mq->queue_length);
  mq->queue_length--;
  if (mq->current_envelope == ev)
  {
    /* complex case, we already started with transmitting
       the message using the callbacks. */
    GNUNET_assert (! mq->in_flight);
    mq->cancel_impl (mq,
                     mq->impl_state);
    /* continue sending the next message, if any */
    mq->current_envelope = mq->envelope_head;
    if (NULL != mq->current_envelope)
    {
      GNUNET_CONTAINER_DLL_remove (mq->envelope_head,
                                   mq->envelope_tail,
                                   mq->current_envelope);
      LOG (GNUNET_ERROR_TYPE_DEBUG,
           "sending canceled message of type %u queue\n",
           ntohs (ev->mh->type));
      mq->send_impl (mq,
                     mq->current_envelope->mh,
                     mq->impl_state);
    }
  }
  else
  {
    /* simple case, message is still waiting in the queue */
    GNUNET_CONTAINER_DLL_remove (mq->envelope_head,
                                 mq->envelope_tail,
                                 ev);
  }
  ev->parent_queue = NULL;
  ev->mh = NULL;
  /* also frees ev */
  GNUNET_free (ev);
}


struct GNUNET_MQ_Envelope *
GNUNET_MQ_get_current_envelope (struct GNUNET_MQ_Handle *mq)
{
  return mq->current_envelope;
}


struct GNUNET_MQ_Envelope *
GNUNET_MQ_get_last_envelope (struct GNUNET_MQ_Handle *mq)
{
  if (NULL != mq->envelope_tail)
    return mq->envelope_tail;

  return mq->current_envelope;
}


void
GNUNET_MQ_env_set_options (struct GNUNET_MQ_Envelope *env,
                           enum GNUNET_MQ_PriorityPreferences pp)
{
  env->priority = pp;
  env->have_custom_options = GNUNET_YES;
}


enum GNUNET_MQ_PriorityPreferences
GNUNET_MQ_env_get_options (struct GNUNET_MQ_Envelope *env)
{
  struct GNUNET_MQ_Handle *mq = env->parent_queue;

  if (GNUNET_YES == env->have_custom_options)
    return env->priority;
  if (NULL == mq)
    return 0;
  return mq->priority;
}


enum GNUNET_MQ_PriorityPreferences
GNUNET_MQ_env_combine_options (enum GNUNET_MQ_PriorityPreferences p1,
                               enum GNUNET_MQ_PriorityPreferences p2)
{
  enum GNUNET_MQ_PriorityPreferences ret;

  ret = GNUNET_MAX (p1 & GNUNET_MQ_PRIORITY_MASK, p2 & GNUNET_MQ_PRIORITY_MASK);
  ret |= ((p1 & GNUNET_MQ_PREF_UNRELIABLE) & (p2 & GNUNET_MQ_PREF_UNRELIABLE));
  ret |=
    ((p1 & GNUNET_MQ_PREF_LOW_LATENCY) | (p2 & GNUNET_MQ_PREF_LOW_LATENCY));
  ret |=
    ((p1 & GNUNET_MQ_PREF_CORK_ALLOWED) & (p2 & GNUNET_MQ_PREF_CORK_ALLOWED));
  ret |= ((p1 & GNUNET_MQ_PREF_GOODPUT) & (p2 & GNUNET_MQ_PREF_GOODPUT));
  ret |=
    ((p1 & GNUNET_MQ_PREF_OUT_OF_ORDER) & (p2 & GNUNET_MQ_PREF_OUT_OF_ORDER));
  return ret;
}


void
GNUNET_MQ_set_options (struct GNUNET_MQ_Handle *mq,
                       enum GNUNET_MQ_PriorityPreferences pp)
{
  mq->priority = pp;
}


const struct GNUNET_MessageHeader *
GNUNET_MQ_env_get_msg (const struct GNUNET_MQ_Envelope *env)
{
  return env->mh;
}


const struct GNUNET_MQ_Envelope *
GNUNET_MQ_env_next (const struct GNUNET_MQ_Envelope *env)
{
  return env->next;
}


struct GNUNET_MQ_DestroyNotificationHandle *
GNUNET_MQ_destroy_notify (struct GNUNET_MQ_Handle *mq,
                          GNUNET_SCHEDULER_TaskCallback cb,
                          void *cb_cls)
{
  struct GNUNET_MQ_DestroyNotificationHandle *dnh;

  dnh = GNUNET_new (struct GNUNET_MQ_DestroyNotificationHandle);
  dnh->mq = mq;
  dnh->cb = cb;
  dnh->cb_cls = cb_cls;
  GNUNET_CONTAINER_DLL_insert (mq->dnh_head,
                               mq->dnh_tail,
                               dnh);
  return dnh;
}


void
GNUNET_MQ_destroy_notify_cancel (
  struct GNUNET_MQ_DestroyNotificationHandle *dnh)
{
  struct GNUNET_MQ_Handle *mq = dnh->mq;

  GNUNET_CONTAINER_DLL_remove (mq->dnh_head,
                               mq->dnh_tail,
                               dnh);
  GNUNET_free (dnh);
}


void
GNUNET_MQ_dll_insert_head (struct GNUNET_MQ_Envelope **env_head,
                           struct GNUNET_MQ_Envelope **env_tail,
                           struct GNUNET_MQ_Envelope *env)
{
  GNUNET_CONTAINER_DLL_insert (*env_head,
                               *env_tail,
                               env);
}


void
GNUNET_MQ_dll_insert_tail (struct GNUNET_MQ_Envelope **env_head,
                           struct GNUNET_MQ_Envelope **env_tail,
                           struct GNUNET_MQ_Envelope *env)
{
  GNUNET_CONTAINER_DLL_insert_tail (*env_head,
                                    *env_tail,
                                    env);
}


void
GNUNET_MQ_dll_remove (struct GNUNET_MQ_Envelope **env_head,
                      struct GNUNET_MQ_Envelope **env_tail,
                      struct GNUNET_MQ_Envelope *env)
{
  GNUNET_CONTAINER_DLL_remove (*env_head,
                               *env_tail,
                               env);
}


struct GNUNET_MQ_MessageHandler *
GNUNET_MQ_copy_handlers (const struct GNUNET_MQ_MessageHandler *handlers)
{
  struct GNUNET_MQ_MessageHandler *copy;
  unsigned int count;

  if (NULL == handlers)
    return NULL;
  count = GNUNET_MQ_count_handlers (handlers);
  copy = GNUNET_new_array (count + 1,
                           struct GNUNET_MQ_MessageHandler);
  GNUNET_memcpy (copy,
                 handlers,
                 count * sizeof(struct GNUNET_MQ_MessageHandler));
  return copy;
}


struct GNUNET_MQ_MessageHandler *
GNUNET_MQ_copy_handlers2 (const struct GNUNET_MQ_MessageHandler *handlers,
                          GNUNET_MQ_MessageCallback agpl_handler,
                          void *agpl_cls)
{
  struct GNUNET_MQ_MessageHandler *copy;
  unsigned int count;

  if (NULL == handlers)
    return NULL;
  count = GNUNET_MQ_count_handlers (handlers);
  copy = GNUNET_new_array (count + 2,
                           struct GNUNET_MQ_MessageHandler);
  GNUNET_memcpy (copy,
                 handlers,
                 count * sizeof(struct GNUNET_MQ_MessageHandler));
  copy[count].mv = NULL;
  copy[count].cb = agpl_handler;
  copy[count].cls = agpl_cls;
  copy[count].type = GNUNET_MESSAGE_TYPE_REQUEST_AGPL;
  copy[count].expected_size = sizeof(struct GNUNET_MessageHeader);
  return copy;
}


unsigned int
GNUNET_MQ_count_handlers (const struct GNUNET_MQ_MessageHandler *handlers)
{
  unsigned int i;

  if (NULL == handlers)
    return 0;
  for (i = 0; NULL != handlers[i].cb; i++)
    ;
  return i;
}


const char *
GNUNET_MQ_preference_to_string (enum GNUNET_MQ_PreferenceKind type)
{
  switch (type)
  {
  case GNUNET_MQ_PREFERENCE_NONE:
    return "NONE";
  case GNUNET_MQ_PREFERENCE_BANDWIDTH:
    return "BANDWIDTH";
  case GNUNET_MQ_PREFERENCE_LATENCY:
    return "LATENCY";
  case GNUNET_MQ_PREFERENCE_RELIABILITY:
    return "RELIABILITY";
  }
  return NULL;
}


/* end of mq.c */