aboutsummaryrefslogtreecommitdiff
path: root/src/psycutil/psyc_message.c
blob: 3dba05b3f672ed1fe47ae48dacd655735cda428a (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
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
/*
 * This file is part of GNUnet
 * Copyright (C) 2013 GNUnet e.V.
 *
 * GNUnet is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 3, 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
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with GNUnet; see the file COPYING.  If not, write to the
 * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

/**
 * @file psycstore/psyc_util_lib.c
 * @brief PSYC utilities; receiving/transmitting/logging PSYC messages.
 * @author Gabor X Toth
 */

#include <inttypes.h>

#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_psyc_util_lib.h"
#include "gnunet_psyc_service.h"

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


struct GNUNET_PSYC_TransmitHandle
{
  /**
   * Client connection to service.
   */
  struct GNUNET_CLIENT_MANAGER_Connection *client;

  /**
   * Message currently being received from the client.
   */
  struct GNUNET_MessageHeader *msg;

  /**
   * Callback to request next modifier from client.
   */
  GNUNET_PSYC_TransmitNotifyModifier notify_mod;

  /**
   * Closure for the notify callbacks.
   */
  void *notify_mod_cls;

  /**
   * Callback to request next data fragment from client.
   */
  GNUNET_PSYC_TransmitNotifyData notify_data;

  /**
   * Closure for the notify callbacks.
   */
  void *notify_data_cls;

  /**
   * Modifier of the environment that is currently being transmitted.
   */
  struct GNUNET_PSYC_Modifier *mod;

  /**
   *
   */
  const char *mod_value;

  /**
   * Number of bytes remaining to be transmitted from the current modifier value.
   */
  uint32_t mod_value_remaining;

  /**
   * State of the current message being received from client.
   */
  enum GNUNET_PSYC_MessageState state;

  /**
   * Number of PSYC_TRANSMIT_ACK messages we are still waiting for.
   */
  uint8_t acks_pending;

  /**
   * Is transmission paused?
   */
  uint8_t paused;

  /**
   * Are we currently transmitting a message?
   */
  uint8_t in_transmit;

  /**
   * Notify callback is currently being called.
   */
  uint8_t in_notify;

};



struct GNUNET_PSYC_ReceiveHandle
{
  /**
   * Message callback.
   */
  GNUNET_PSYC_MessageCallback message_cb;

  /**
   * Message part callback.
   */
  GNUNET_PSYC_MessagePartCallback message_part_cb;

  /**
   * Closure for the callbacks.
   */
  void *cb_cls;

  /**
   * ID of the message being received from the PSYC service.
   */
  uint64_t message_id;

  /**
   * Public key of the slave from which a message is being received.
   */
  struct GNUNET_CRYPTO_EcdsaPublicKey slave_pub_key;

  /**
   * State of the currently being received message from the PSYC service.
   */
  enum GNUNET_PSYC_MessageState state;

  /**
   * Flags for the currently being received message from the PSYC service.
   */
  enum GNUNET_PSYC_MessageFlags flags;

  /**
   * Expected value size for the modifier being received from the PSYC service.
   */
  uint32_t mod_value_size_expected;

  /**
   * Actual value size for the modifier being received from the PSYC service.
   */
  uint32_t mod_value_size;
};


/**** Messages ****/


/**
 * Create a PSYC message.
 *
 * @param method_name
 *        PSYC method for the message.
 * @param env
 *        Environment for the message.
 * @param data
 *        Data payload for the message.
 * @param data_size
 *        Size of @a data.
 *
 * @return Message header with size information,
 *         followed by the message parts.
 */
struct GNUNET_PSYC_Message *
GNUNET_PSYC_message_create (const char *method_name,
                            const struct GNUNET_PSYC_Environment *env,
                            const void *data,
                            size_t data_size)
{
  struct GNUNET_PSYC_Modifier *mod = NULL;
  struct GNUNET_PSYC_MessageMethod *pmeth = NULL;
  struct GNUNET_PSYC_MessageModifier *pmod = NULL;
  struct GNUNET_MessageHeader *pmsg = NULL;
  uint16_t env_size = 0;
  if (NULL != env)
  {
    mod = GNUNET_PSYC_env_head (env);
    while (NULL != mod)
    {
      env_size += sizeof (*pmod) + strlen (mod->name) + 1 + mod->value_size;
      mod = mod->next;
    }
  }

  struct GNUNET_PSYC_Message *msg;
  uint16_t method_name_size = strlen (method_name) + 1;
  if (method_name_size == 1)
    return NULL;

  uint16_t msg_size = sizeof (*msg)                      /* header */
    + sizeof (*pmeth) + method_name_size                 /* method */
    + env_size                                           /* modifiers */
    + ((0 < data_size) ? sizeof (*pmsg) + data_size : 0) /* data */
    + sizeof (*pmsg);                                    /* end of message */
  msg = GNUNET_malloc (msg_size);
  msg->header.size = htons (msg_size);
  msg->header.type = htons (GNUNET_MESSAGE_TYPE_PSYC_MESSAGE); /* FIXME */

  pmeth = (struct GNUNET_PSYC_MessageMethod *) &msg[1];
  pmeth->header.type = htons (GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_METHOD);
  pmeth->header.size = htons (sizeof (*pmeth) + method_name_size);
  memcpy (&pmeth[1], method_name, method_name_size);

  uint16_t p = sizeof (*msg) + sizeof (*pmeth) + method_name_size;
  if (NULL != env)
  {
    mod = GNUNET_PSYC_env_head (env);
    while (NULL != mod)
    {
      uint16_t mod_name_size = strlen (mod->name) + 1;
      pmod = (struct GNUNET_PSYC_MessageModifier *) ((char *) msg + p);
      pmod->header.type = htons (GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_MODIFIER);
      pmod->header.size = sizeof (*pmod) + mod_name_size + mod->value_size;
      p += pmod->header.size;
      pmod->header.size = htons (pmod->header.size);

      pmod->oper = mod->oper;
      pmod->name_size = htons (mod_name_size);
      pmod->value_size = htonl (mod->value_size);

      memcpy (&pmod[1], mod->name, mod_name_size);
      if (0 < mod->value_size)
        memcpy ((char *) &pmod[1] + mod_name_size, mod->value, mod->value_size);

      mod = mod->next;
    }
  }

  if (0 < data_size)
  {
    pmsg = (struct GNUNET_MessageHeader *) ((char *) msg + p);
    pmsg->size = sizeof (*pmsg) + data_size;
    p += pmsg->size;
    pmsg->size = htons (pmsg->size);
    pmsg->type = htons (GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_DATA);
    memcpy (&pmsg[1], data, data_size);
  }

  pmsg = (struct GNUNET_MessageHeader *) ((char *) msg + p);
  pmsg->size = htons (sizeof (*pmsg));
  pmsg->type = htons (GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_END);

  GNUNET_assert (p + sizeof (*pmsg) == msg_size);
  return msg;
}


void
GNUNET_PSYC_log_message (enum GNUNET_ErrorType kind,
                         const struct GNUNET_MessageHeader *msg)
{
  uint16_t size = ntohs (msg->size);
  uint16_t type = ntohs (msg->type);
  GNUNET_log (kind, "Message of type %d and size %u:\n", type, size);
  switch (type)
  {
  case GNUNET_MESSAGE_TYPE_PSYC_MESSAGE:
  {
    struct GNUNET_PSYC_MessageHeader *pmsg
      = (struct GNUNET_PSYC_MessageHeader *) msg;
    GNUNET_log (kind, "\tID: %" PRIu64 "\tflags: %x" PRIu32 "\n",
                GNUNET_ntohll (pmsg->message_id), ntohl (pmsg->flags));
    break;
  }
  case GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_METHOD:
  {
    struct GNUNET_PSYC_MessageMethod *meth
      = (struct GNUNET_PSYC_MessageMethod *) msg;
    GNUNET_log (kind,
                "\t%.*s\n",
                (int) (size - sizeof (*meth)),
                &meth[1]);
    break;
  }
  case GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_MODIFIER:
  {
    struct GNUNET_PSYC_MessageModifier *mod
      = (struct GNUNET_PSYC_MessageModifier *) msg;
    uint16_t name_size = ntohs (mod->name_size);
    char oper = ' ' < mod->oper ? mod->oper : ' ';
    GNUNET_log (kind,
                "\t%c%.*s\t%.*s\n",
                oper,
                (int) name_size,
                &mod[1],
                (int) (size - sizeof (*mod) - name_size),
                ((char *) &mod[1]) + name_size);
    break;
  }
  case GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_MOD_CONT:
  case GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_DATA:
    GNUNET_log (kind, "\t%.*s\n", size - sizeof (*msg), &msg[1]);
    break;
  }
}


/**** Transmitting messages ****/


/**
 * Create a transmission handle.
 */
struct GNUNET_PSYC_TransmitHandle *
GNUNET_PSYC_transmit_create (struct GNUNET_CLIENT_MANAGER_Connection *client)
{
  struct GNUNET_PSYC_TransmitHandle *tmit = GNUNET_malloc (sizeof (*tmit));
  tmit->client = client;
  return tmit;
}


/**
 * Destroy a transmission handle.
 */
void
GNUNET_PSYC_transmit_destroy (struct GNUNET_PSYC_TransmitHandle *tmit)
{
  GNUNET_free (tmit);
}


/**
 * Queue a message part for transmission.
 *
 * The message part is added to the current message buffer.
 * When this buffer is full, it is added to the transmission queue.
 *
 * @param tmit
 *        Transmission handle.
 * @param msg
 *        Message part, or NULL.
 * @param tmit_now
 *        Transmit message now, or wait for buffer to fill up?
 *        #GNUNET_YES or #GNUNET_NO.
 */
static void
transmit_queue_insert (struct GNUNET_PSYC_TransmitHandle *tmit,
                       const struct GNUNET_MessageHeader *msg,
                       uint8_t tmit_now)
{
  uint16_t size = (NULL != msg) ? ntohs (msg->size) : 0;

  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Queueing message part of type %u and size %u (tmit_now: %u)).\n",
       NULL != msg ? ntohs (msg->type) : 0, size, tmit_now);

  if (NULL != tmit->msg)
  {
    if (NULL == msg
        || GNUNET_MULTICAST_FRAGMENT_MAX_PAYLOAD < tmit->msg->size + size)
    {
      /* End of message or buffer is full, add it to transmission queue
       * and start with empty buffer */
      tmit->msg->type = htons (GNUNET_MESSAGE_TYPE_PSYC_MESSAGE);
      tmit->msg->size = htons (tmit->msg->size);
      GNUNET_CLIENT_MANAGER_transmit (tmit->client, tmit->msg);
      tmit->msg = NULL;
      tmit->acks_pending++;
    }
    else
    {
      /* Message fits in current buffer, append */
      tmit->msg = GNUNET_realloc (tmit->msg, tmit->msg->size + size);
      memcpy ((char *) tmit->msg + tmit->msg->size, msg, size);
      tmit->msg->size += size;
    }
  }

  if (NULL == tmit->msg && NULL != msg)
  {
    /* Empty buffer, copy over message. */
    tmit->msg = GNUNET_malloc (sizeof (*tmit->msg) + size);
    tmit->msg->size = sizeof (*tmit->msg) + size;
    memcpy (&tmit->msg[1], msg, size);
  }

  if (NULL != tmit->msg
      && (GNUNET_YES == tmit_now
          || (GNUNET_MULTICAST_FRAGMENT_MAX_PAYLOAD
              < tmit->msg->size + sizeof (struct GNUNET_MessageHeader))))
  {
    /* End of message or buffer is full, add it to transmission queue. */
    tmit->msg->type = htons (GNUNET_MESSAGE_TYPE_PSYC_MESSAGE);
    tmit->msg->size = htons (tmit->msg->size);
    GNUNET_CLIENT_MANAGER_transmit (tmit->client, tmit->msg);
    tmit->msg = NULL;
    tmit->acks_pending++;
  }
}


/**
 * Request data from client to transmit.
 *
 * @param tmit  Transmission handle.
 */
static void
transmit_data (struct GNUNET_PSYC_TransmitHandle *tmit)
{
  int notify_ret = GNUNET_YES;
  uint16_t data_size = 0;
  char data[GNUNET_MULTICAST_FRAGMENT_MAX_PAYLOAD] = "";
  struct GNUNET_MessageHeader *msg = (struct GNUNET_MessageHeader *) data;
  msg->type = htons (GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_DATA);

  if (NULL != tmit->notify_data)
  {
    data_size = GNUNET_PSYC_DATA_MAX_PAYLOAD;
    tmit->in_notify = GNUNET_YES;
    notify_ret = tmit->notify_data (tmit->notify_data_cls, &data_size, &msg[1]);
    tmit->in_notify = GNUNET_NO;
  }
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "transmit_data (ret: %d, size: %u): %.*s\n",
       notify_ret, data_size, data_size, &msg[1]);
  switch (notify_ret)
  {
  case GNUNET_NO:
    if (0 == data_size)
    {
      /* Transmission paused, nothing to send. */
      tmit->paused = GNUNET_YES;
      return;
    }
    break;

  case GNUNET_YES:
    tmit->state = GNUNET_PSYC_MESSAGE_STATE_END;
    break;

  default:
    LOG (GNUNET_ERROR_TYPE_ERROR,
         "TransmitNotifyData callback returned error when requesting data.\n");

    tmit->state = GNUNET_PSYC_MESSAGE_STATE_CANCEL;
    msg->type = htons (GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_CANCEL);
    msg->size = htons (sizeof (*msg));
    transmit_queue_insert (tmit, msg, GNUNET_YES);
    tmit->in_transmit = GNUNET_NO;
    return;
  }

  if (0 < data_size)
  {
    GNUNET_assert (data_size <= GNUNET_PSYC_DATA_MAX_PAYLOAD);
    msg->size = htons (sizeof (*msg) + data_size);
    transmit_queue_insert (tmit, msg, !notify_ret);
  }

  /* End of message. */
  if (GNUNET_YES == notify_ret)
  {
    msg->type = htons (GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_END);
    msg->size = htons (sizeof (*msg));
    transmit_queue_insert (tmit, msg, GNUNET_YES);
    /* FIXME: wait for ACK before setting in_transmit to no */
    tmit->in_transmit = GNUNET_NO;
  }
}


/**
 * Request a modifier from a client to transmit.
 *
 * @param tmit  Transmission handle.
 */
static void
transmit_mod (struct GNUNET_PSYC_TransmitHandle *tmit)
{
  uint16_t max_data_size = 0;
  uint16_t data_size = 0;
  char data[GNUNET_MULTICAST_FRAGMENT_MAX_PAYLOAD] = "";
  struct GNUNET_MessageHeader *msg = (struct GNUNET_MessageHeader *) data;
  int notify_ret = GNUNET_YES;

  switch (tmit->state)
  {
  case GNUNET_PSYC_MESSAGE_STATE_MODIFIER:
  {
    struct GNUNET_PSYC_MessageModifier *mod
      = (struct GNUNET_PSYC_MessageModifier *) msg;
    msg->type = htons (GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_MODIFIER);
    msg->size = sizeof (struct GNUNET_PSYC_MessageModifier);

    if (NULL != tmit->notify_mod)
    {
      max_data_size = GNUNET_PSYC_MODIFIER_MAX_PAYLOAD;
      data_size = max_data_size;
      tmit->in_notify = GNUNET_YES;
      notify_ret = tmit->notify_mod (tmit->notify_mod_cls, &data_size, &mod[1],
                                     &mod->oper, &mod->value_size);
      tmit->in_notify = GNUNET_NO;
    }

    mod->name_size = strnlen ((char *) &mod[1], data_size) + 1;
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "transmit_mod (ret: %d, size: %u + %u): %.*s\n",
         notify_ret, mod->name_size, mod->value_size, data_size, &mod[1]);
    if (mod->name_size < data_size)
    {
      tmit->mod_value_remaining
        = mod->value_size - (data_size - mod->name_size);
      mod->value_size = htonl (mod->value_size);
      mod->name_size = htons (mod->name_size);
    }
    else if (0 < data_size)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Got invalid modifier name.\n");
      notify_ret = GNUNET_SYSERR;
    }
    break;
  }
  case GNUNET_PSYC_MESSAGE_STATE_MOD_CONT:
  {
    msg->type = htons (GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_MOD_CONT);
    msg->size = sizeof (struct GNUNET_MessageHeader);

    if (NULL != tmit->notify_mod)
    {
      max_data_size = GNUNET_PSYC_MOD_CONT_MAX_PAYLOAD;
      data_size = max_data_size;
      tmit->in_notify = GNUNET_YES;
      notify_ret = tmit->notify_mod (tmit->notify_mod_cls,
                                     &data_size, &msg[1], NULL, NULL);
      tmit->in_notify = GNUNET_NO;
    }
    tmit->mod_value_remaining -= data_size;
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "transmit_mod (ret: %d, size: %u): %.*s\n",
         notify_ret, data_size, data_size, &msg[1]);
    break;
  }
  default:
    GNUNET_assert (0);
  }

  switch (notify_ret)
  {
  case GNUNET_NO:
    if (0 == data_size)
    { /* Transmission paused, nothing to send. */
      tmit->paused = GNUNET_YES;
      return;
    }
    tmit->state
      = (0 == tmit->mod_value_remaining)
      ? GNUNET_PSYC_MESSAGE_STATE_MODIFIER
      : GNUNET_PSYC_MESSAGE_STATE_MOD_CONT;
    break;

  case GNUNET_YES: /* End of modifiers. */
    GNUNET_assert (0 == tmit->mod_value_remaining);
    break;

  default:
    LOG (GNUNET_ERROR_TYPE_ERROR,
         "TransmitNotifyModifier callback returned with error.\n");

    tmit->state = GNUNET_PSYC_MESSAGE_STATE_CANCEL;
    msg->type = htons (GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_CANCEL);
    msg->size = htons (sizeof (*msg));
    transmit_queue_insert (tmit, msg, GNUNET_YES);
    tmit->in_transmit = GNUNET_NO;
    return;
  }

  if (0 < data_size)
  {
    GNUNET_assert (data_size <= max_data_size);
    msg->size = htons (msg->size + data_size);
    transmit_queue_insert (tmit, msg, GNUNET_NO);
  }

  if (GNUNET_YES == notify_ret)
  {
    tmit->state = GNUNET_PSYC_MESSAGE_STATE_DATA;
    if (0 == tmit->acks_pending)
      transmit_data (tmit);
  }
  else
  {
    transmit_mod (tmit);
  }
}


int
transmit_notify_env (void *cls, uint16_t *data_size, void *data, uint8_t *oper,
                     uint32_t *full_value_size)

{
  struct GNUNET_PSYC_TransmitHandle *tmit = cls;
  uint16_t name_size = 0;
  uint32_t value_size = 0;
  const char *value = NULL;

  if (NULL != oper)
  { /* New modifier */
    if (NULL != tmit->mod)
      tmit->mod = tmit->mod->next;
    if (NULL == tmit->mod)
    { /* No more modifiers, continue with data */
      *data_size = 0;
      return GNUNET_YES;
    }

    GNUNET_assert (tmit->mod->value_size < UINT32_MAX);
    *full_value_size = tmit->mod->value_size;
    *oper = tmit->mod->oper;
    name_size = strlen (tmit->mod->name) + 1;

    if (name_size + tmit->mod->value_size <= *data_size)
    {
      value_size = tmit->mod->value_size;
      *data_size = name_size + value_size;
    }
    else /* full modifier does not fit in data, continuation needed */
    {
      value_size = *data_size - name_size;
      tmit->mod_value = tmit->mod->value + value_size;
    }

    memcpy (data, tmit->mod->name, name_size);
    memcpy ((char *)data + name_size, tmit->mod->value, value_size);
    return GNUNET_NO;
  }
  else
  { /* Modifier continuation */
    GNUNET_assert (NULL != tmit->mod_value && 0 < tmit->mod_value_remaining);
    value = tmit->mod_value;
    if (tmit->mod_value_remaining <= *data_size)
    {
      value_size = tmit->mod_value_remaining;
      tmit->mod_value = NULL;
    }
    else
    {
      value_size = *data_size;
      tmit->mod_value += value_size;
    }

    if (*data_size < value_size)
    {
      LOG (GNUNET_ERROR_TYPE_DEBUG,
           "Value in environment larger than buffer: %u < %zu\n",
           *data_size, value_size);
      *data_size = 0;
      return GNUNET_NO;
    }

    *data_size = value_size;
    memcpy (data, value, value_size);
    return (NULL == tmit->mod_value) ? GNUNET_YES : GNUNET_NO;
  }
}


/**
 * Transmit a message.
 *
 * @param tmit
 *        Transmission handle.
 * @param method_name
 *        Which method should be invoked.
 * @param env
 *        Environment for the message.
 *        Should stay available until the first call to notify_data.
 *        Can be NULL if there are no modifiers or @a notify_mod is
 *        provided instead.
 * @param notify_mod
 *        Function to call to obtain modifiers.
 *        Can be NULL if there are no modifiers or @a env is provided instead.
 * @param notify_data
 *        Function to call to obtain fragments of the data.
 * @param notify_cls
 *        Closure for @a notify_mod and @a notify_data.
 * @param flags
 *        Flags for the message being transmitted.
 *
 * @return #GNUNET_OK if the transmission was started.
 *         #GNUNET_SYSERR if another transmission is already going on.
 */
int
GNUNET_PSYC_transmit_message (struct GNUNET_PSYC_TransmitHandle *tmit,
                              const char *method_name,
                              const struct GNUNET_PSYC_Environment *env,
                              GNUNET_PSYC_TransmitNotifyModifier notify_mod,
                              GNUNET_PSYC_TransmitNotifyData notify_data,
                              void *notify_cls,
                              uint32_t flags)
{
  if (GNUNET_NO != tmit->in_transmit)
    return GNUNET_SYSERR;
  tmit->in_transmit = GNUNET_YES;

  size_t size = strlen (method_name) + 1;
  struct GNUNET_PSYC_MessageMethod *pmeth;
  tmit->msg = GNUNET_malloc (sizeof (*tmit->msg) + sizeof (*pmeth) + size);
  tmit->msg->size = sizeof (*tmit->msg) + sizeof (*pmeth) + size;

  if (NULL != notify_mod)
  {
    tmit->notify_mod = notify_mod;
    tmit->notify_mod_cls = notify_cls;
  }
  else
  {
    tmit->notify_mod = &transmit_notify_env;
    tmit->notify_mod_cls = tmit;
    if (NULL != env)
    {
      struct GNUNET_PSYC_Modifier mod = {};
      mod.next = GNUNET_PSYC_env_head (env);
      tmit->mod = &mod;

      struct GNUNET_PSYC_Modifier *m = tmit->mod;
      while (NULL != (m = m->next))
      {
        if (m->oper != GNUNET_PSYC_OP_SET)
          flags |= GNUNET_PSYC_MASTER_TRANSMIT_STATE_MODIFY;
      }
    }
    else
    {
      tmit->mod = NULL;
    }
  }

  pmeth = (struct GNUNET_PSYC_MessageMethod *) &tmit->msg[1];
  pmeth->header.type = htons (GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_METHOD);
  pmeth->header.size = htons (sizeof (*pmeth) + size);
  pmeth->flags = htonl (flags);
  memcpy (&pmeth[1], method_name, size);

  tmit->state = GNUNET_PSYC_MESSAGE_STATE_MODIFIER;
  tmit->notify_data = notify_data;
  tmit->notify_data_cls = notify_cls;

  transmit_mod (tmit);
  return GNUNET_OK;
}


/**
 * Resume transmission.
 *
 * @param tmit  Transmission handle.
 */
void
GNUNET_PSYC_transmit_resume (struct GNUNET_PSYC_TransmitHandle *tmit)
{
  if (GNUNET_YES != tmit->in_transmit || GNUNET_NO != tmit->in_notify)
    return;

  if (0 == tmit->acks_pending)
  {
    tmit->paused = GNUNET_NO;
    transmit_data (tmit);
  }
}


/**
 * Abort transmission request.
 *
 * @param tmit  Transmission handle.
 */
void
GNUNET_PSYC_transmit_cancel (struct GNUNET_PSYC_TransmitHandle *tmit)
{
  if (GNUNET_NO == tmit->in_transmit)
    return;

  tmit->state = GNUNET_PSYC_MESSAGE_STATE_CANCEL;
  tmit->in_transmit = GNUNET_NO;
  tmit->paused = GNUNET_NO;

  /* FIXME */
  struct GNUNET_MessageHeader msg;
  msg.type = htons (GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_DATA);
  msg.type = htons (GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_CANCEL);
  msg.size = htons (sizeof (msg));
  transmit_queue_insert (tmit, &msg, GNUNET_YES);
}


/**
 * Got acknowledgement of a transmitted message part, continue transmission.
 *
 * @param tmit  Transmission handle.
 */
void
GNUNET_PSYC_transmit_got_ack (struct GNUNET_PSYC_TransmitHandle *tmit)
{
  if (0 == tmit->acks_pending)
  {
    LOG (GNUNET_ERROR_TYPE_WARNING, "Ignoring extraneous message ACK\n");
    GNUNET_break (0);
    return;
  }
  tmit->acks_pending--;

  switch (tmit->state)
  {
  case GNUNET_PSYC_MESSAGE_STATE_MODIFIER:
  case GNUNET_PSYC_MESSAGE_STATE_MOD_CONT:
    transmit_mod (tmit);
    break;

  case GNUNET_PSYC_MESSAGE_STATE_DATA:
    transmit_data (tmit);
    break;

  case GNUNET_PSYC_MESSAGE_STATE_END:
  case GNUNET_PSYC_MESSAGE_STATE_CANCEL:
    break;

  default:
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Ignoring message ACK in state %u.\n", tmit->state);
  }
}


/**** Receiving messages ****/


/**
 * Create handle for receiving messages.
 */
struct GNUNET_PSYC_ReceiveHandle *
GNUNET_PSYC_receive_create (GNUNET_PSYC_MessageCallback message_cb,
                            GNUNET_PSYC_MessagePartCallback message_part_cb,
                            void *cb_cls)
{
  struct GNUNET_PSYC_ReceiveHandle *recv = GNUNET_malloc (sizeof (*recv));
  recv->message_cb = message_cb;
  recv->message_part_cb = message_part_cb;
  recv->cb_cls = cb_cls;
  return recv;
}


/**
 * Destroy handle for receiving messages.
 */
void
GNUNET_PSYC_receive_destroy (struct GNUNET_PSYC_ReceiveHandle *recv)
{
  GNUNET_free (recv);
}


/**
 * Reset stored data related to the last received message.
 */
void
GNUNET_PSYC_receive_reset (struct GNUNET_PSYC_ReceiveHandle *recv)
{
  recv->state = GNUNET_PSYC_MESSAGE_STATE_START;
  recv->flags = 0;
  recv->message_id = 0;
  recv->mod_value_size = 0;
  recv->mod_value_size_expected = 0;
}


static void
recv_error (struct GNUNET_PSYC_ReceiveHandle *recv)
{
  if (NULL != recv->message_part_cb)
    recv->message_part_cb (recv->cb_cls, NULL, NULL);

  if (NULL != recv->message_cb)
    recv->message_cb (recv->cb_cls, NULL);

  GNUNET_PSYC_receive_reset (recv);
}


/**
 * Handle incoming PSYC message.
 *
 * @param recv  Receive handle.
 * @param msg   The message.
 *
 * @return #GNUNET_OK on success,
 *         #GNUNET_SYSERR on receive error.
 */
int
GNUNET_PSYC_receive_message (struct GNUNET_PSYC_ReceiveHandle *recv,
                             const struct GNUNET_PSYC_MessageHeader *msg)
{
  uint16_t size = ntohs (msg->header.size);
  uint32_t flags = ntohl (msg->flags);

  GNUNET_PSYC_log_message (GNUNET_ERROR_TYPE_DEBUG,
                           (struct GNUNET_MessageHeader *) msg);

  if (GNUNET_PSYC_MESSAGE_STATE_START == recv->state)
  {
    recv->message_id = GNUNET_ntohll (msg->message_id);
    recv->flags = flags;
    recv->slave_pub_key = msg->slave_pub_key;
    recv->mod_value_size = 0;
    recv->mod_value_size_expected = 0;
  }
  else if (GNUNET_ntohll (msg->message_id) != recv->message_id)
  {
    // FIXME
    LOG (GNUNET_ERROR_TYPE_WARNING,
         "Unexpected message ID. Got: %" PRIu64 ", expected: %" PRIu64 "\n",
         GNUNET_ntohll (msg->message_id), recv->message_id);
    GNUNET_break_op (0);
    recv_error (recv);
    return GNUNET_SYSERR;
  }
  else if (flags != recv->flags)
  {
    LOG (GNUNET_ERROR_TYPE_WARNING,
         "Unexpected message flags. Got: %lu, expected: %lu\n",
         flags, recv->flags);
    GNUNET_break_op (0);
    recv_error (recv);
    return GNUNET_SYSERR;
  }

  uint16_t pos = 0, psize = 0, ptype, size_eq, size_min;

  for (pos = 0; sizeof (*msg) + pos < size; pos += psize)
  {
    const struct GNUNET_MessageHeader *pmsg
      = (const struct GNUNET_MessageHeader *) ((char *) &msg[1] + pos);
    psize = ntohs (pmsg->size);
    ptype = ntohs (pmsg->type);
    size_eq = size_min = 0;

    if (psize < sizeof (*pmsg) || sizeof (*msg) + pos + psize > size)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                  "Dropping message of type %u with invalid size %u.\n",
                  ptype, psize);
      recv_error (recv);
      return GNUNET_SYSERR;
    }

    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Received message part of type %u and size %u from PSYC.\n",
                ptype, psize);
    GNUNET_PSYC_log_message (GNUNET_ERROR_TYPE_DEBUG, pmsg);

    switch (ptype)
    {
    case GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_METHOD:
      size_min = sizeof (struct GNUNET_PSYC_MessageMethod);
      break;
    case GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_MODIFIER:
      size_min = sizeof (struct GNUNET_PSYC_MessageModifier);
      break;
    case GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_MOD_CONT:
    case GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_DATA:
      size_min = sizeof (struct GNUNET_MessageHeader);
      break;
    case GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_END:
    case GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_CANCEL:
      size_eq = sizeof (struct GNUNET_MessageHeader);
      break;
    default:
      GNUNET_break_op (0);
      recv_error (recv);
      return GNUNET_SYSERR;
    }

    if (! ((0 < size_eq && psize == size_eq)
           || (0 < size_min && size_min <= psize)))
    {
      GNUNET_break_op (0);
      recv_error (recv);
      return GNUNET_SYSERR;
    }

    switch (ptype)
    {
    case GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_METHOD:
    {
      struct GNUNET_PSYC_MessageMethod *meth
        = (struct GNUNET_PSYC_MessageMethod *) pmsg;

      if (GNUNET_PSYC_MESSAGE_STATE_START != recv->state)
      {
        LOG (GNUNET_ERROR_TYPE_WARNING,
             "Dropping out of order message method (%u).\n",
             recv->state);
        /* It is normal to receive an incomplete message right after connecting,
         * but should not happen later.
         * FIXME: add a check for this condition.
         */
        GNUNET_break_op (0);
        recv_error (recv);
        return GNUNET_SYSERR;
      }

      if ('\0' != *((char *) meth + psize - 1))
      {
        LOG (GNUNET_ERROR_TYPE_WARNING,
             "Dropping message with malformed method. "
             "Message ID: %" PRIu64 "\n", recv->message_id);
        GNUNET_break_op (0);
        recv_error (recv);
        return GNUNET_SYSERR;
      }
      recv->state = GNUNET_PSYC_MESSAGE_STATE_METHOD;
      break;
    }
    case GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_MODIFIER:
    {
      if (!(GNUNET_PSYC_MESSAGE_STATE_METHOD == recv->state
            || GNUNET_PSYC_MESSAGE_STATE_MODIFIER == recv->state
            || GNUNET_PSYC_MESSAGE_STATE_MOD_CONT == recv->state))
      {
        LOG (GNUNET_ERROR_TYPE_WARNING,
             "Dropping out of order message modifier (%u).\n",
             recv->state);
        GNUNET_break_op (0);
        recv_error (recv);
        return GNUNET_SYSERR;
      }

      struct GNUNET_PSYC_MessageModifier *mod
        = (struct GNUNET_PSYC_MessageModifier *) pmsg;

      uint16_t name_size = ntohs (mod->name_size);
      recv->mod_value_size_expected = ntohl (mod->value_size);
      recv->mod_value_size = psize - sizeof (*mod) - name_size;

      if (psize < sizeof (*mod) + name_size
          || '\0' != *((char *) &mod[1] + name_size - 1)
          || recv->mod_value_size_expected < recv->mod_value_size)
      {
        LOG (GNUNET_ERROR_TYPE_WARNING, "Dropping malformed modifier.\n");
        GNUNET_break_op (0);
        recv_error (recv);
        return GNUNET_SYSERR;
      }
      recv->state = GNUNET_PSYC_MESSAGE_STATE_MODIFIER;
      break;
    }
    case GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_MOD_CONT:
    {
      recv->mod_value_size += psize - sizeof (*pmsg);

      if (!(GNUNET_PSYC_MESSAGE_STATE_MODIFIER == recv->state
            || GNUNET_PSYC_MESSAGE_STATE_MOD_CONT == recv->state)
          || recv->mod_value_size_expected < recv->mod_value_size)
      {
        LOG (GNUNET_ERROR_TYPE_WARNING,
             "Dropping out of order message modifier continuation "
             "!(%u == %u || %u == %u) || %lu < %lu.\n",
             GNUNET_PSYC_MESSAGE_STATE_MODIFIER, recv->state,
             GNUNET_PSYC_MESSAGE_STATE_MOD_CONT, recv->state,
             recv->mod_value_size_expected, recv->mod_value_size);
        GNUNET_break_op (0);
        recv_error (recv);
        return GNUNET_SYSERR;
      }
      break;
    }
    case GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_DATA:
    {
      if (recv->state < GNUNET_PSYC_MESSAGE_STATE_METHOD
          || recv->mod_value_size_expected != recv->mod_value_size)
      {
        LOG (GNUNET_ERROR_TYPE_WARNING,
             "Dropping out of order message data fragment "
             "(%u < %u || %lu != %lu).\n",
             recv->state, GNUNET_PSYC_MESSAGE_STATE_METHOD,
             recv->mod_value_size_expected, recv->mod_value_size);

        GNUNET_break_op (0);
        recv_error (recv);
        return GNUNET_SYSERR;
      }
      recv->state = GNUNET_PSYC_MESSAGE_STATE_DATA;
      break;
    }
    }

    if (NULL != recv->message_part_cb)
      recv->message_part_cb (recv->cb_cls, msg, pmsg);

    switch (ptype)
    {
    case GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_END:
    case GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_CANCEL:
      GNUNET_PSYC_receive_reset (recv);
      break;
    }
  }

  if (NULL != recv->message_cb)
    recv->message_cb (recv->cb_cls, msg);
  return GNUNET_OK;
}


/**
 * Check if @a data contains a series of valid message parts.
 *
 * @param      data_size    Size of @a data.
 * @param      data	    Data.
 * @param[out] first_ptype  Type of first message part.
 * @param[out] last_ptype   Type of last message part.
 *
 * @return Number of message parts found in @a data.
 *         or GNUNET_SYSERR if the message contains invalid parts.
 */
int
GNUNET_PSYC_receive_check_parts (uint16_t data_size, const char *data,
                                 uint16_t *first_ptype, uint16_t *last_ptype)
{
  const struct GNUNET_MessageHeader *pmsg;
  uint16_t parts = 0, ptype = 0, psize = 0, pos = 0;
  if (NULL != first_ptype)
    *first_ptype = 0;
  if (NULL != last_ptype)
    *last_ptype = 0;

  for (pos = 0; pos < data_size; pos += psize, parts++)
  {
    pmsg = (const struct GNUNET_MessageHeader *) (data + pos);
    GNUNET_PSYC_log_message (GNUNET_ERROR_TYPE_DEBUG, pmsg);
    psize = ntohs (pmsg->size);
    ptype = ntohs (pmsg->type);
    if (0 == parts && NULL != first_ptype)
      *first_ptype = ptype;
    if (NULL != last_ptype
        && *last_ptype < GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_END)
      *last_ptype = ptype;
    if (psize < sizeof (*pmsg)
        || pos + psize > data_size
        || ptype < GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_METHOD
        || GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_CANCEL < ptype)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                  "Invalid message part of type %u and size %u.\n",
                  ptype, psize);
      return GNUNET_SYSERR;
    }
    /** @todo FIXME: check message part order */
  }
  return parts;
}


struct ParseMessageClosure
{
  struct GNUNET_PSYC_Environment *env;
  const char **method_name;
  const void **data;
  uint16_t *data_size;
  enum GNUNET_PSYC_MessageState msg_state;
};


static void
parse_message_part_cb (void *cls,
                       const struct GNUNET_PSYC_MessageHeader *msg,
                       const struct GNUNET_MessageHeader *pmsg)
{
  struct ParseMessageClosure *pmc = cls;
  if (NULL == pmsg)
  {
    pmc->msg_state = GNUNET_PSYC_MESSAGE_STATE_ERROR;
    return;
  }

  switch (ntohs (pmsg->type))
  {
  case GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_METHOD:
  {
    struct GNUNET_PSYC_MessageMethod *
      pmeth = (struct GNUNET_PSYC_MessageMethod *) pmsg;
    *pmc->method_name = (const char *) &pmeth[1];
    pmc->msg_state = GNUNET_PSYC_MESSAGE_STATE_METHOD;
    break;
  }

  case GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_MODIFIER:
  {
    struct GNUNET_PSYC_MessageModifier *
      pmod = (struct GNUNET_PSYC_MessageModifier *) pmsg;

    const char *name = (const char *) &pmod[1];
    const void *value = name + ntohs (pmod->name_size);
    GNUNET_PSYC_env_add (pmc->env, pmod->oper, name, value,
                         ntohl (pmod->value_size));
    pmc->msg_state = GNUNET_PSYC_MESSAGE_STATE_MODIFIER;
    break;
  }

  case GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_DATA:
    *pmc->data = &pmsg[1];
    *pmc->data_size = ntohs (pmsg->size) - sizeof (*pmsg);
    pmc->msg_state = GNUNET_PSYC_MESSAGE_STATE_DATA;
    break;

  case GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_END:
    pmc->msg_state = GNUNET_PSYC_MESSAGE_STATE_END;
    break;

  default:
    pmc->msg_state = GNUNET_PSYC_MESSAGE_STATE_ERROR;
  }
}


/**
 * Parse PSYC message.
 *
 * @param msg
 *        The PSYC message to parse.
 * @param[out] method_name
 *        Pointer to the method name inside @a pmsg.
 * @param env
 *        The environment for the message with a list of modifiers.
 * @param[out] data
 *        Pointer to data inside @a msg.
 * @param[out] data_size
 *        Size of @data is written here.
 *
 * @return #GNUNET_OK on success,
 *         #GNUNET_SYSERR on parse error.
 */
int
GNUNET_PSYC_message_parse (const struct GNUNET_PSYC_MessageHeader *msg,
                           const char **method_name,
                           struct GNUNET_PSYC_Environment *env,
                           const void **data,
                           uint16_t *data_size)
{
  struct ParseMessageClosure cls;
  cls.env = env;
  cls.method_name = method_name;
  cls.data = data;
  cls.data_size = data_size;

  struct GNUNET_PSYC_ReceiveHandle *
    recv = GNUNET_PSYC_receive_create (NULL, parse_message_part_cb, &cls);
  int ret = GNUNET_PSYC_receive_message (recv, msg);
  GNUNET_PSYC_receive_destroy (recv);

  if (GNUNET_OK != ret)
    return GNUNET_SYSERR;

  return (GNUNET_PSYC_MESSAGE_STATE_END == cls.msg_state)
    ? GNUNET_OK
    : GNUNET_NO;
}


/**
 * Initialize PSYC message header.
 */
void
GNUNET_PSYC_message_header_init (struct GNUNET_PSYC_MessageHeader *pmsg,
                                 const struct GNUNET_MULTICAST_MessageHeader *mmsg,
                                 uint32_t flags)
{
  uint16_t size = ntohs (mmsg->header.size);
  uint16_t psize = sizeof (*pmsg) + size - sizeof (*mmsg);

  pmsg->header.size = htons (psize);
  pmsg->header.type = htons (GNUNET_MESSAGE_TYPE_PSYC_MESSAGE);
  pmsg->message_id = mmsg->message_id;
  pmsg->fragment_offset = mmsg->fragment_offset;
  pmsg->flags = htonl (flags);

  memcpy (&pmsg[1], &mmsg[1], size - sizeof (*mmsg));
}


/**
 * Create a new PSYC message header from a multicast message.
 */
struct GNUNET_PSYC_MessageHeader *
GNUNET_PSYC_message_header_create (const struct GNUNET_MULTICAST_MessageHeader *mmsg,
                                   uint32_t flags)
{
  struct GNUNET_PSYC_MessageHeader *pmsg;
  uint16_t size = ntohs (mmsg->header.size);
  uint16_t psize = sizeof (*pmsg) + size - sizeof (*mmsg);

  pmsg = GNUNET_malloc (psize);
  GNUNET_PSYC_message_header_init (pmsg, mmsg, flags);
  return pmsg;
}


/**
 * Create a new PSYC message header from a PSYC message.
 */
struct GNUNET_PSYC_MessageHeader *
GNUNET_PSYC_message_header_create_from_psyc (const struct GNUNET_PSYC_Message *msg)
{
  uint16_t msg_size = ntohs (msg->header.size);
  struct GNUNET_PSYC_MessageHeader *
    pmsg = GNUNET_malloc (sizeof (*pmsg) + msg_size - sizeof (*msg));
  pmsg->header.type = htons (GNUNET_MESSAGE_TYPE_PSYC_MESSAGE);
  pmsg->header.size = htons (sizeof (*pmsg) + msg_size - sizeof (*msg));
  memcpy (&pmsg[1], &msg[1], msg_size - sizeof (*msg));
  return pmsg;
}