aboutsummaryrefslogtreecommitdiff
path: root/src/json/json.c
blob: 4c2b82ccb8a9e5501b6f460a58bd6eb6fb03d676 (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
/*
  This file is part of TALER
  Copyright (C) 2014, 2015, 2016, 2020, 2021 Taler Systems SA

  TALER 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.

  TALER 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
  TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
*/
/**
 * @file json/json.c
 * @brief helper functions for JSON processing using libjansson
 * @author Sree Harsha Totakura <sreeharsha@totakura.in>
 * @author Christian Grothoff
 */
#include "platform.h"
#include <gnunet/gnunet_util_lib.h>
#include "taler_util.h"
#include "taler_json_lib.h"


/**
 * Check if @a json contains a 'real' value anywhere.
 *
 * @param json json to check
 * @return true if a real is in it somewhere
 */
static bool
contains_real (const json_t *json)
{
  if (json_is_real (json))
    return true;
  if (json_is_object (json))
  {
    json_t *member;
    const char *name;

    json_object_foreach ((json_t *) json, name, member)
    if (contains_real (member))
      return true;
    return false;
  }
  if (json_is_array (json))
  {
    json_t *member;
    size_t index;

    json_array_foreach ((json_t *) json, index, member)
    if (contains_real (member))
      return true;
    return false;
  }
  return false;
}


/**
 * Dump the @a json to a string and hash it.
 *
 * @param json value to hash
 * @param salt salt value to include when using HKDF,
 *        NULL to not use any salt and to use SHA512
 * @param[out] hc where to store the hash
 * @return #GNUNET_OK on success,
 *         #GNUNET_NO if @a json was not hash-able
 *         #GNUNET_SYSERR on failure
 */
static enum GNUNET_GenericReturnValue
dump_and_hash (const json_t *json,
               const char *salt,
               struct GNUNET_HashCode *hc)
{
  char *wire_enc;
  size_t len;

  if (NULL == json)
  {
    GNUNET_break_op (0);
    return GNUNET_NO;
  }
  if (contains_real (json))
  {
    GNUNET_break_op (0);
    return GNUNET_NO;
  }
  if (NULL == (wire_enc = json_dumps (json,
                                      JSON_ENCODE_ANY
                                      | JSON_COMPACT
                                      | JSON_SORT_KEYS)))
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  len = strlen (wire_enc) + 1;
  if (NULL == salt)
  {
    GNUNET_CRYPTO_hash (wire_enc,
                        len,
                        hc);
  }
  else
  {
    if (GNUNET_YES !=
        GNUNET_CRYPTO_kdf (hc,
                           sizeof (*hc),
                           salt,
                           strlen (salt) + 1,
                           wire_enc,
                           len,
                           NULL,
                           0))
    {
      GNUNET_break (0);
      free (wire_enc);
      return GNUNET_SYSERR;
    }
  }
  free (wire_enc);
  return GNUNET_OK;
}


/**
 * Replace "forgettable" parts of a JSON object with their salted hash.
 *
 * @param[in] in some JSON value
 * @param[out] out resulting JSON value
 * @return #GNUNET_OK on success,
 *         #GNUNET_NO if @a json was not hash-able
 *         #GNUNET_SYSERR on failure
 */
static enum GNUNET_GenericReturnValue
forget (const json_t *in,
        json_t **out)
{
  if (json_is_real (in))
  {
    /* floating point is not allowed! */
    GNUNET_break_op (0);
    return GNUNET_NO;
  }
  if (json_is_array (in))
  {
    /* array is a JSON array */
    size_t index;
    json_t *value;
    json_t *ret;

    ret = json_array ();
    if (NULL == ret)
    {
      GNUNET_break (0);
      return GNUNET_SYSERR;
    }
    json_array_foreach (in, index, value) {
      enum GNUNET_GenericReturnValue iret;
      json_t *t;

      iret = forget (value,
                     &t);
      if (GNUNET_OK != iret)
      {
        json_decref (ret);
        return iret;
      }
      if (0 != json_array_append_new (ret,
                                      t))
      {
        GNUNET_break (0);
        json_decref (ret);
        return GNUNET_SYSERR;
      }
    }
    *out = ret;
    return GNUNET_OK;
  }
  if (json_is_object (in))
  {
    json_t *ret;
    const char *key;
    json_t *value;
    json_t *fg;
    json_t *rx;

    fg = json_object_get (in,
                          "$forgettable");
    rx = json_object_get (in,
                          "$forgotten");
    if (NULL != rx)
    {
      rx = json_deep_copy (rx); /* should be shallow
                                   by structure, but
                                   deep copy is safer */
      if (NULL == rx)
      {
        GNUNET_break (0);
        return GNUNET_SYSERR;
      }
    }
    ret = json_object ();
    if (NULL == ret)
    {
      GNUNET_break (0);
      return GNUNET_SYSERR;
    }
    json_object_foreach ((json_t*) in, key, value) {
      json_t *t;
      json_t *salt;
      enum GNUNET_GenericReturnValue iret;

      if (fg == value)
        continue; /* skip! */
      if (rx == value)
        continue; /* skip! */
      if ( (NULL != rx) &&
           (NULL !=
            json_object_get (rx,
                             key)) )
      {
        (void) json_object_del (ret,
                                key);
        continue; /* already forgotten earlier */
      }
      iret = forget (value,
                     &t);
      if (GNUNET_OK != iret)
      {
        json_decref (ret);
        json_decref (rx);
        return iret;
      }
      if ( (NULL != fg) &&
           (NULL != (salt = json_object_get (fg,
                                             key))) )
      {
        /* 't' is to be forgotten! */
        struct GNUNET_HashCode hc;

        if (! json_is_string (salt))
        {
          GNUNET_break_op (0);
          json_decref (ret);
          json_decref (rx);
          json_decref (t);
          return GNUNET_NO;
        }
        iret = dump_and_hash (t,
                              json_string_value (salt),
                              &hc);
        if (GNUNET_OK != iret)
        {
          json_decref (ret);
          json_decref (rx);
          json_decref (t);
          return iret;
        }
        json_decref (t);
        /* scrub salt */
        if (0 !=
            json_object_del (fg,
                             key))
        {
          GNUNET_break_op (0);
          json_decref (ret);
          json_decref (rx);
          return GNUNET_NO;
        }
        if (NULL == rx)
          rx = json_object ();
        if (NULL == rx)
        {
          GNUNET_break (0);
          json_decref (ret);
          return GNUNET_SYSERR;
        }
        if (0 !=
            json_object_set_new (rx,
                                 key,
                                 GNUNET_JSON_from_data_auto (&hc)))
        {
          GNUNET_break (0);
          json_decref (ret);
          json_decref (rx);
          return GNUNET_SYSERR;
        }
      }
      else
      {
        /* 't' to be used without 'forgetting' */
        if (0 !=
            json_object_set_new (ret,
                                 key,
                                 t))
        {
          GNUNET_break (0);
          json_decref (ret);
          json_decref (rx);
          return GNUNET_SYSERR;
        }
      }
    } /* json_object_foreach */
    if ( (NULL != rx) &&
         (0 !=
          json_object_set_new (ret,
                               "$forgotten",
                               rx)) )
    {
      GNUNET_break (0);
      json_decref (ret);
      return GNUNET_SYSERR;
    }
    *out = ret;
    return GNUNET_OK;
  }
  *out = json_incref ((json_t *) in);
  return GNUNET_OK;
}


enum GNUNET_GenericReturnValue
TALER_JSON_contract_hash (const json_t *json,
                          struct GNUNET_HashCode *hc)
{
  enum GNUNET_GenericReturnValue ret;
  json_t *cjson;
  json_t *dc;

  dc = json_deep_copy (json);
  ret = forget (dc,
                &cjson);
  json_decref (dc);
  if (GNUNET_OK != ret)
    return ret;
  ret = dump_and_hash (cjson,
                       NULL,
                       hc);
  json_decref (cjson);
  return ret;
}


enum GNUNET_GenericReturnValue
TALER_JSON_contract_mark_forgettable (json_t *json,
                                      const char *field)
{
  json_t *fg;
  struct GNUNET_ShortHashCode salt;

  if (! json_is_object (json))
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  /* check field name is legal for forgettable field */
  for (const char *f = field; '\0' != *f; f++)
  {
    char c = *f;

    if ( (c >= 'a') && (c <= 'z') )
      continue;
    if ( (c >= 'A') && (c <= 'Z') )
      continue;
    if ( (c >= '0') && (c <= '9') )
      continue;
    if ('_' == c)
      continue;
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  if (NULL == json_object_get (json,
                               field))
  {
    /* field must exist */
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  fg = json_object_get (json,
                        "$forgettable");
  if (NULL == fg)
  {
    fg = json_object ();
    if (0 !=
        json_object_set_new (json,
                             "$forgettable",
                             fg))
    {
      GNUNET_break (0);
      return GNUNET_SYSERR;
    }
  }

  GNUNET_CRYPTO_random_block (GNUNET_CRYPTO_QUALITY_NONCE,
                              &salt,
                              sizeof (salt));
  if (0 !=
      json_object_set_new (fg,
                           field,
                           GNUNET_JSON_from_data_auto (&salt)))
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  return GNUNET_OK;
}


enum GNUNET_GenericReturnValue
TALER_JSON_contract_part_forget (json_t *json,
                                 const char *field)
{
  json_t *fg;
  const json_t *part;
  json_t *fp;
  json_t *rx;
  struct GNUNET_HashCode hc;
  const char *salt;
  enum GNUNET_GenericReturnValue ret;

  if (! json_is_object (json))
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  if (NULL == (part = json_object_get (json,
                                       field)))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                "Did not find field `%s' we were asked to forget\n",
                field);
    return GNUNET_SYSERR;
  }
  fg = json_object_get (json,
                        "$forgettable");
  if (NULL == fg)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                "Did not find '$forgettable' attribute trying to forget field `%s'\n",
                field);
    return GNUNET_SYSERR;
  }
  rx = json_object_get (json,
                        "$forgotten");
  if (NULL == rx)
  {
    rx = json_object ();
    if (0 !=
        json_object_set_new (json,
                             "$forgotten",
                             rx))
    {
      GNUNET_break (0);
      return GNUNET_SYSERR;
    }
  }
  if (NULL !=
      json_object_get (rx,
                       field))
  {
    if (! json_is_null (json_object_get (json,
                                         field)))
    {
      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                  "Field `%s' market as forgotten, but still exists!\n",
                  field);
      return GNUNET_SYSERR;
    }
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                "Already forgot field `%s'\n",
                field);
    return GNUNET_NO;
  }
  salt = json_string_value (json_object_get (fg,
                                             field));
  if (NULL == salt)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                "Did not find required salt to forget field `%s'\n",
                field);
    return GNUNET_SYSERR;
  }

  /* need to recursively forget to compute 'hc' */
  ret = forget (part,
                &fp);
  if (GNUNET_OK != ret)
    return ret;
  if (GNUNET_OK !=
      dump_and_hash (fp,
                     salt,
                     &hc))
  {
    json_decref (fp);
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  json_decref (fp);
  /* drop salt */
  if (0 !=
      json_object_del (fg,
                       field))
  {
    json_decref (fp);
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }

  /* remember field as 'forgotten' */
  if (0 !=
      json_object_set_new (rx,
                           field,
                           GNUNET_JSON_from_data_auto (&hc)))
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  /* finally, set 'forgotten' field to null */
  if (0 !=
      json_object_del (json,
                       field))
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  return GNUNET_OK;
}


/**
 * Look over all of the values of a '$forgettable' object.  Replace 'True'
 * values with proper random salts.  Fails if any forgettable values are
 * neither 'True' nor valid salts (strings).
 *
 * @param[in,out] f JSON to transform
 * @return #GNUNET_OK on success
 */
static enum GNUNET_GenericReturnValue
seed_forgettable (json_t *f)
{
  const char *key;
  json_t *val;

  json_object_foreach (f,
                       key,
                       val)
  {
    if (json_is_string (val))
      continue;
    if (json_is_true (val))
    {
      struct GNUNET_ShortHashCode sh;

      GNUNET_CRYPTO_random_block (GNUNET_CRYPTO_QUALITY_NONCE,
                                  &sh,
                                  sizeof (sh));
      json_object_set_new (f,
                           key,
                           GNUNET_JSON_from_data_auto (&sh));
      continue;
    }
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Forgettable field `%s' has invalid value\n",
                key);
    return GNUNET_SYSERR;
  }
  return GNUNET_OK;
}


/**
 * Take a given contract with "forgettable" fields marked
 * but with 'True' instead of a real salt. Replaces all
 * 'True' values with proper random salts.  Fails if any
 * forgettable markers are neither 'True' nor valid salts.
 *
 * @param[in,out] json JSON to transform
 * @return #GNUNET_OK on success
 */
enum GNUNET_GenericReturnValue
TALER_JSON_contract_seed_forgettable (json_t *json)
{
  if (json_is_object (json))
  {
    const char *key;
    json_t *val;

    json_object_foreach (json,
                         key,
                         val)
    {
      if (0 == strcmp ("$forgettable",
                       key))
      {
        if (GNUNET_OK !=
            seed_forgettable (val))
          return GNUNET_SYSERR;
        continue;
      }
      if (GNUNET_OK !=
          TALER_JSON_contract_seed_forgettable (val))
        return GNUNET_SYSERR;
    }
  }
  if (json_is_array (json))
  {
    size_t index;
    json_t *val;

    json_array_foreach (json,
                        index,
                        val)
    {
      if (GNUNET_OK !=
          TALER_JSON_contract_seed_forgettable (val))
        return GNUNET_SYSERR;
    }
  }
  return GNUNET_OK;
}


/**
 * Parse a json path.
 *
 * @param obj the object that the path is relative to.
 * @param prev the parent of @e obj.
 * @param path the path to parse.
 * @param cb the callback to call, if we get to the end of @e path.
 * @param cb_cls the closure for the callback.
 * @return #GNUNET_OK on success, #GNUNET_SYSERR if @e path is malformed.
 */
static enum GNUNET_GenericReturnValue
parse_path (json_t *obj,
            json_t *prev,
            const char *path,
            TALER_JSON_ExpandPathCallback cb,
            void *cb_cls)
{
  char *id = GNUNET_strdup (path);
  char *next_id = strchr (id,
                          '.');
  char *next_path;
  char *bracket;
  json_t *next_obj = NULL;
  char *next_dot;

  if (NULL == next_id)
  {
    cb (cb_cls,
        id,
        prev);
    GNUNET_free (id);
    return GNUNET_OK;
  }
  bracket = strchr (next_id,
                    '[');
  *next_id = '\0';
  next_id++;
  next_path = GNUNET_strdup (next_id);
  next_dot = strchr (next_id,
                     '.');
  if (NULL != next_dot)
    *next_dot = '\0';
  /* If this is the first time this is called, make sure id is "$" */
  if ( (NULL == prev) &&
       (0 != strcmp (id,
                     "$")))
  {
    GNUNET_free (id);
    GNUNET_free (next_path);
    return GNUNET_SYSERR;
  }

  /* Check for bracketed indices */
  if (NULL != bracket)
  {
    char *end_bracket = strchr (bracket,
                                ']');
    if (NULL == end_bracket)
    {
      GNUNET_free (id);
      GNUNET_free (next_path);
      return GNUNET_SYSERR;
    }
    *end_bracket = '\0';

    *bracket = '\0';
    bracket++;

    json_t *array = json_object_get (obj,
                                     next_id);
    if (0 == strcmp (bracket,
                     "*"))
    {
      size_t index;
      json_t *value;
      int ret = GNUNET_OK;

      json_array_foreach (array, index, value) {
        ret = parse_path (value,
                          obj,
                          next_path,
                          cb,
                          cb_cls);
        if (GNUNET_OK != ret)
        {
          GNUNET_free (id);
          GNUNET_free (next_path);
          return ret;
        }
      }
    }
    else
    {
      unsigned int index;
      char dummy;

      if (1 != sscanf (bracket,
                       "%u%c",
                       &index,
                       &dummy))
      {
        GNUNET_free (id);
        GNUNET_free (next_path);
        return GNUNET_SYSERR;
      }
      next_obj = json_array_get (array,
                                 index);
    }
  }
  else
  {
    /* No brackets, so just fetch the object by name */
    next_obj = json_object_get (obj,
                                next_id);
  }

  if (NULL != next_obj)
  {
    int ret = parse_path (next_obj,
                          obj,
                          next_path,
                          cb,
                          cb_cls);
    GNUNET_free (id);
    GNUNET_free (next_path);
    return ret;
  }
  GNUNET_free (id);
  GNUNET_free (next_path);
  return GNUNET_OK;
}


enum GNUNET_GenericReturnValue
TALER_JSON_expand_path (json_t *json,
                        const char *path,
                        TALER_JSON_ExpandPathCallback cb,
                        void *cb_cls)
{
  return parse_path (json,
                     NULL,
                     path,
                     cb,
                     cb_cls);
}


enum TALER_ErrorCode
TALER_JSON_get_error_code (const json_t *json)
{
  const json_t *jc;

  if (NULL == json)
    return TALER_EC_GENERIC_INVALID_RESPONSE;
  jc = json_object_get (json, "code");
  /* The caller already knows that the JSON represents an error,
     so we are dealing with a missing error code here.  */
  if (NULL == jc)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                "Expected Taler error code `code' in JSON, but field does not exist!\n");
    return TALER_EC_INVALID;
  }
  if (json_is_integer (jc))
    return (enum TALER_ErrorCode) json_integer_value (jc);
  GNUNET_break_op (0);
  return TALER_EC_INVALID;
}


const char *
TALER_JSON_get_error_hint (const json_t *json)
{
  const json_t *jc;

  if (NULL == json)
    return NULL;
  jc = json_object_get (json,
                        "hint");
  if (NULL == jc)
    return NULL; /* no hint, is allowed */
  if (! json_is_string (jc))
  {
    /* Hints must be strings */
    GNUNET_break_op (0);
    return NULL;
  }
  return json_string_value (jc);
}


enum TALER_ErrorCode
TALER_JSON_get_error_code2 (const void *data,
                            size_t data_size)
{
  json_t *json;
  enum TALER_ErrorCode ec;
  json_error_t err;

  json = json_loadb (data,
                     data_size,
                     JSON_REJECT_DUPLICATES,
                     &err);
  if (NULL == json)
    return TALER_EC_INVALID;
  ec = TALER_JSON_get_error_code (json);
  json_decref (json);
  if (ec == TALER_EC_NONE)
    return TALER_EC_INVALID;
  return ec;
}


/* End of json/json.c */