aboutsummaryrefslogtreecommitdiff
path: root/src/microhttpd/postprocessor.c
blob: b7f6b108d58df897f563dc28bff13feeb59c81db (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
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
/*
     This file is part of libmicrohttpd
     Copyright (C) 2007-2013 Daniel Pittman and Christian Grothoff

     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Lesser General Public
     License as published by the Free Software Foundation; either
     version 2.1 of the License, or (at your option) any later version.

     This library 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
     Lesser General Public License for more details.

     You should have received a copy of the GNU Lesser General Public
     License along with this library; if not, write to the Free Software
     Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/

/**
 * @file postprocessor.c
 * @brief  Methods for parsing POST data
 * @author Christian Grothoff
 */

#include "internal.h"
#include "mhd_str.h"
#include "mhd_compat.h"

/**
 * Size of on-stack buffer that we use for un-escaping of the value.
 * We use a pretty small value to be nice to the stack on embedded
 * systems.
 */
#define XBUF_SIZE 512

/**
 * States in the PP parser's state machine.
 */
enum PP_State
{
  /* general states */
  PP_Error,
  PP_Done,
  PP_Init,
  PP_NextBoundary,

  /* url encoding-states */
  PP_ProcessValue,
  PP_Callback,
  PP_ExpectNewLine,

  /* post encoding-states  */
  PP_ProcessEntryHeaders,
  PP_PerformCheckMultipart,
  PP_ProcessValueToBoundary,
  PP_PerformCleanup,

  /* nested post-encoding states */
  PP_Nested_Init,
  PP_Nested_PerformMarking,
  PP_Nested_ProcessEntryHeaders,
  PP_Nested_ProcessValueToBoundary,
  PP_Nested_PerformCleanup

};


enum RN_State
{
  /**
   * No RN-preprocessing in this state.
   */
  RN_Inactive = 0,

  /**
   * If the next character is CR, skip it.  Otherwise,
   * just go inactive.
   */
  RN_OptN = 1,

  /**
   * Expect LFCR (and only LFCR).  As always, we also
   * expect only LF or only CR.
   */
  RN_Full = 2,

  /**
   * Expect either LFCR or '--'LFCR.  If '--'LFCR, transition into dash-state
   * for the main state machine
   */
  RN_Dash = 3,

  /**
   * Got a single dash, expect second dash.
   */
  RN_Dash2 = 4
};


/**
 * Bits for the globally known fields that
 * should not be deleted when we exit the
 * nested state.
 */
enum NE_State
{
  NE_none = 0,
  NE_content_name = 1,
  NE_content_type = 2,
  NE_content_filename = 4,
  NE_content_transfer_encoding = 8
};


/**
 * Internal state of the post-processor.  Note that the fields
 * are sorted by type to enable optimal packing by the compiler.
 */
struct MHD_PostProcessor
{

  /**
   * The connection for which we are doing
   * POST processing.
   */
  struct MHD_Connection *connection;

  /**
   * Function to call with POST data.
   */
  MHD_PostDataIterator ikvi;

  /**
   * Extra argument to ikvi.
   */
  void *cls;

  /**
   * Encoding as given by the headers of the
   * connection.
   */
  const char *encoding;

  /**
   * Primary boundary (points into encoding string)
   */
  const char *boundary;

  /**
   * Nested boundary (if we have multipart/mixed encoding).
   */
  char *nested_boundary;

  /**
   * Pointer to the name given in disposition.
   */
  char *content_name;

  /**
   * Pointer to the (current) content type.
   */
  char *content_type;

  /**
   * Pointer to the (current) filename.
   */
  char *content_filename;

  /**
   * Pointer to the (current) encoding.
   */
  char *content_transfer_encoding;

  /**
   * Value data left over from previous iteration.
   */
  char xbuf[2];
  
  /**
   * Size of our buffer for the key.
   */
  size_t buffer_size;

  /**
   * Current position in the key buffer.
   */
  size_t buffer_pos;

  /**
   * Current position in @e xbuf.
   */
  size_t xbuf_pos;

  /**
   * Current offset in the value being processed.
   */
  uint64_t value_offset;

  /**
   * strlen(boundary) -- if boundary != NULL.
   */
  size_t blen;

  /**
   * strlen(nested_boundary) -- if nested_boundary != NULL.
   */
  size_t nlen;

  /**
   * Do we have to call the 'ikvi' callback when processing the
   * multipart post body even if the size of the payload is zero?
   * Set to #MHD_YES whenever we parse a new multiparty entry header,
   * and to #MHD_NO the first time we call the 'ikvi' callback.
   * Used to ensure that we do always call 'ikvi' even if the
   * payload is empty (but not more than once).
   */
  bool must_ikvi;

  /**
   * Set if we still need to run the unescape logic
   * on the key allocated at the end of this struct.
   */ 
  bool must_unescape_key;
  
  /**
   * State of the parser.
   */
  enum PP_State state;

  /**
   * Side-state-machine: skip LRCR (or just LF).
   * Set to 0 if we are not in skip mode.  Set to 2
   * if a LFCR is expected, set to 1 if a CR should
   * be skipped if it is the next character.
   */
  enum RN_State skip_rn;

  /**
   * If we are in skip_rn with "dash" mode and
   * do find 2 dashes, what state do we go into?
   */
  enum PP_State dash_state;

  /**
   * Which headers are global? (used to tell which
   * headers were only valid for the nested multipart).
   */
  enum NE_State have;

};


/**
 * Create a `struct MHD_PostProcessor`.
 *
 * A `struct MHD_PostProcessor` can be used to (incrementally) parse
 * the data portion of a POST request.  Note that some buggy browsers
 * fail to set the encoding type.  If you want to support those, you
 * may have to call #MHD_set_connection_value with the proper encoding
 * type before creating a post processor (if no supported encoding
 * type is set, this function will fail).
 *
 * @param connection the connection on which the POST is
 *        happening (used to determine the POST format)
 * @param buffer_size maximum number of bytes to use for
 *        internal buffering (used only for the parsing,
 *        specifically the parsing of the keys).  A
 *        tiny value (256-1024) should be sufficient.
 *        Do NOT use a value smaller than 256.  For good
 *        performance, use 32 or 64k (i.e. 65536).
 * @param iter iterator to be called with the parsed data,
 *        Must NOT be NULL.
 * @param iter_cls first argument to @a iter
 * @return NULL on error (out of memory, unsupported encoding),
 *         otherwise a PP handle
 * @ingroup request
 */
struct MHD_PostProcessor *
MHD_create_post_processor (struct MHD_Connection *connection,
                           size_t buffer_size,
                           MHD_PostDataIterator iter,
                           void *iter_cls)
{
  struct MHD_PostProcessor *ret;
  const char *encoding;
  const char *boundary;
  size_t blen;

  if ( (buffer_size < 256) ||
       (NULL == connection) ||
       (NULL == iter))
    mhd_panic (mhd_panic_cls,
               __FILE__,
               __LINE__,
               NULL);
  if (MHD_NO == MHD_lookup_connection_value_n (connection,
                                               MHD_HEADER_KIND,
                                               MHD_HTTP_HEADER_CONTENT_TYPE,
                                               MHD_STATICSTR_LEN_ (
                                                 MHD_HTTP_HEADER_CONTENT_TYPE),
                                               &encoding,
                                               NULL))
    return NULL;
  boundary = NULL;
  if (! MHD_str_equal_caseless_n_ (MHD_HTTP_POST_ENCODING_FORM_URLENCODED,
                                   encoding,
                                   MHD_STATICSTR_LEN_ (
                                     MHD_HTTP_POST_ENCODING_FORM_URLENCODED)))
  {
    if (! MHD_str_equal_caseless_n_ (MHD_HTTP_POST_ENCODING_MULTIPART_FORMDATA,
                                     encoding,
                                     MHD_STATICSTR_LEN_ (
                                       MHD_HTTP_POST_ENCODING_MULTIPART_FORMDATA)))
      return NULL;
    boundary =
      &encoding[MHD_STATICSTR_LEN_ (MHD_HTTP_POST_ENCODING_MULTIPART_FORMDATA)];
    /* Q: should this be "strcasestr"? */
    boundary = strstr (boundary, "boundary=");
    if (NULL == boundary)
      return NULL; /* failed to determine boundary */
    boundary += MHD_STATICSTR_LEN_ ("boundary=");
    blen = strlen (boundary);
    if ( (blen == 0) ||
         (blen * 2 + 2 > buffer_size) )
      return NULL;              /* (will be) out of memory or invalid boundary */
    if ( (boundary[0] == '"') &&
         (boundary[blen - 1] == '"') )
    {
      /* remove enclosing quotes */
      ++boundary;
      blen -= 2;
    }
  }
  else
    blen = 0;
  buffer_size += 4; /* round up to get nice block sizes despite boundary search */

  /* add +1 to ensure we ALWAYS have a zero-termination at the end */
  if (NULL == (ret = MHD_calloc_ (1, sizeof (struct MHD_PostProcessor)
                                  + buffer_size + 1)))
    return NULL;
  ret->connection = connection;
  ret->ikvi = iter;
  ret->cls = iter_cls;
  ret->encoding = encoding;
  ret->buffer_size = buffer_size;
  ret->state = PP_Init;
  ret->blen = blen;
  ret->boundary = boundary;
  ret->skip_rn = RN_Inactive;
  return ret;
}


/**
 * Give a (possibly partial) value to the
 * application callback.  We have some
 * part of the value in the 'pp->xbuf', the
 * rest is between @a value_start and @a value_end.
 * If @a last_escape is non-NULL, there may be
 * an incomplete escape sequence at at @a value_escape
 * between @a value_start and @a value_end which
 * we should preserve in 'pp->xbuf' for the future.
 *
 * Unescapes the value and calls the iterator
 * together with the key.  The key must already
 * be in the key buffer allocated and 0-terminated
 * at the end of @a pp at the time of the call.
 *
 * @param pp post processor to act upon
 * @param value_start where in memory is the value
 * @param value_end where does the value end
 * @param last_escape last '%'-sign in value range,
 *        if relevant, or NULL
 */
static void
process_value (struct MHD_PostProcessor *pp,
               const char *value_start,
               const char *value_end,
               const char *last_escape)
{
  char xbuf[XBUF_SIZE + 1];
  size_t xoff;

  mhd_assert (pp->xbuf_pos < sizeof (xbuf));
  memcpy (xbuf,
          pp->xbuf,
          pp->xbuf_pos);
  xoff = pp->xbuf_pos;
  pp->xbuf_pos = 0;
  if (NULL != last_escape)
  {
    if (value_end - last_escape < sizeof (pp->xbuf))
    {
      pp->xbuf_pos = value_end - last_escape;
      memcpy (pp->xbuf,
              last_escape,
              value_end - last_escape);
      value_end = last_escape;
    }
  }
  while ( (value_start != value_end) ||
          (pp->must_ikvi) ||
          (xoff > 0) )
  {
    size_t delta = value_end - value_start;

    if (delta > XBUF_SIZE - xoff)
      delta = XBUF_SIZE - xoff;
    /* move input into processing buffer */
    memcpy (&xbuf[xoff],
            value_start,
            delta);
    /* find if escape sequence is at the end of the processing buffer;
       if so, exclude those from processing (reduce delta to point at
       end of processed region) */
    if (delta >= XBUF_SIZE - 2)
    {
      if ((xoff + delta > 0) &&
          ('%' == xbuf[xoff + delta - 1]))
        delta--;
      else if ((xoff + delta > 1) &&
               ('%' == xbuf[xoff + delta - 2]))
        delta -= 2;
    }
    xoff += delta;
    value_start += delta;
    mhd_assert (xoff < sizeof (xbuf));
    /* unescape */
    xbuf[xoff] = '\0';        /* 0-terminate in preparation */
    MHD_unescape_plus (xbuf);
    xoff = MHD_http_unescape (xbuf);
    /* finally: call application! */
    pp->must_ikvi = false;
    if (MHD_NO == pp->ikvi (pp->cls,
                            MHD_POSTDATA_KIND,
                            (const char *) &pp[1],        /* key */
                            NULL,
                            NULL,
                            NULL,
                            xbuf,
                            pp->value_offset,
                            xoff))
    {
      pp->state = PP_Error;
      return;
    }
    pp->value_offset += xoff;
    xoff = 0;
  }
}


/**
 * Process url-encoded POST data.
 *
 * @param pp post processor context
 * @param post_data upload data
 * @param post_data_len number of bytes in @a post_data
 * @return #MHD_YES on success, #MHD_NO if there was an error processing the data
 */
static int
post_process_urlencoded (struct MHD_PostProcessor *pp,
                         const char *post_data,
                         size_t post_data_len)
{
  char *kbuf = (char *) &pp[1];
  size_t poff;
  const char *start_key = NULL;
  const char *end_key = NULL;
  const char *start_value = NULL;
  const char *end_value = NULL;
  const char *last_escape = NULL;

  poff = 0;
  while ( ( (poff < post_data_len) ||
            (pp->state == PP_Callback) ) &&
          (pp->state != PP_Error) )
  {
    switch (pp->state) {
    case PP_Error:
      /* clearly impossible as per while loop invariant */
      abort ();
      break;
    case PP_Init:
      /* key phase */
      if (NULL == start_key)
        start_key = &post_data[poff];
      pp->must_ikvi = true;
      switch (post_data[poff])
      {
      case '=':
        /* Case: 'key=' */
        end_key = &post_data[poff];
        poff++;
        pp->state = PP_ProcessValue;
        break;
      case '&':
        /* Case: 'key&' */
        end_key = &post_data[poff];
        mhd_assert (NULL == start_value);
        mhd_assert (NULL == end_value);
        poff++;
        pp->state = PP_Callback;
        break;
      case '\n':
      case '\r':
        /* Case: 'key\n' or 'key\r' */
        end_key = &post_data[poff];
        poff++;
        pp->state = PP_Done;
        break;
      default:
        /* normal character, advance! */
        poff++;
        continue;
      }
      break; /* end PP_Init */
    case PP_ProcessValue:
      if (NULL == start_value)
        start_value = &post_data[poff];
      switch (post_data[poff]) {
      case '=':
        /* case 'key==' */
        pp->state = PP_Error;
        continue;
      case '&':
        /* case 'value&' */
        end_value = &post_data[poff];
        poff++;
        if ( pp->must_ikvi ||
             (start_value != end_value) )
        {
          pp->state = PP_Callback;
        }
        else
        {
          pp->buffer_pos = 0;
          pp->value_offset = 0;
          pp->state = PP_Init; 
        }
        continue;
      case '\n':
      case '\r':
        /* Case: 'value\n' or 'value\r' */
        end_value = &post_data[poff];
        poff++;
        if (pp->must_ikvi)
          pp->state = PP_Callback;
        else
          pp->state = PP_Done;
        break;
      case '%':
        last_escape = &post_data[poff];
        poff++;
        break;
      case '0':
      case '1':
      case '2':
      case '3':
      case '4':
      case '5':
      case '6':
      case '7':
      case '8':
      case '9':
        /* character, may be part of escaping */
        poff++;
        continue;
      default:
        /* normal character, no more escaping! */
        last_escape = NULL;
        poff++;
        continue;
      }
      break; /* end PP_ProcessValue */
    case PP_Done:
      switch (post_data[poff]) {
      case '\n':
      case '\r':
        poff++;
        continue;
      }
      /* unexpected data at the end, fail! */
      pp->state = PP_Error;
      break;
    case PP_Callback:
      if ( (pp->buffer_pos + (end_key - start_key) >
            pp->buffer_size) ||
           (pp->buffer_pos + (end_key - start_key) <
            pp->buffer_pos) )
      {
        /* key too long, cannot parse! */
        pp->state = PP_Error;
        continue;
      }
      /* compute key, if we have not already */
      if (NULL != start_key)
      {
        memcpy (&kbuf[pp->buffer_pos],
                start_key,
                end_key - start_key);
        pp->buffer_pos += end_key - start_key;
        start_key = NULL;
        end_key = NULL;
        pp->must_unescape_key = true;
      }
      if (pp->must_unescape_key)
      {
        kbuf[pp->buffer_pos] = '\0'; /* 0-terminate key */
        MHD_unescape_plus (kbuf);
        MHD_http_unescape (kbuf);
        pp->must_unescape_key = false;
      }
      process_value (pp,
                     start_value,
                     end_value,
                     NULL);
      pp->value_offset = 0;
      start_value = NULL;
      end_value = NULL;
      pp->buffer_pos = 0;
      pp->state = PP_Init;
      break;
    default:
      mhd_panic (mhd_panic_cls,
                 __FILE__,
                 __LINE__,
                 NULL);              /* should never happen! */
    }
  }

  /* save remaining data for next iteration */
  if (NULL != start_key) 
  {
    if (NULL == end_key) 
      end_key = &post_data[poff];
    memcpy (&kbuf[pp->buffer_pos],
            start_key,
            end_key - start_key);
    pp->buffer_pos += end_key - start_key;
    pp->must_unescape_key = true;
    start_key = NULL;
    end_key = NULL;
  }
  if ( (NULL != start_value) &&
       (PP_ProcessValue == pp->state) )
  {
    /* compute key, if we have not already */
    if (pp->must_unescape_key)
    {
      kbuf[pp->buffer_pos] = '\0'; /* 0-terminate key */
      MHD_unescape_plus (kbuf);
      MHD_http_unescape (kbuf);
      pp->must_unescape_key = false;
    }
    if (NULL == end_value)
      end_value = &post_data[poff];
    process_value (pp,
                   start_value,
                   end_value,
                   last_escape);
    pp->must_ikvi = false;
  }
  return MHD_YES;
}


/**
 * If the given line matches the prefix, strdup the
 * rest of the line into the suffix ptr.
 *
 * @param prefix prefix to match
 * @param prefix_len length of @a prefix
 * @param line line to match prefix in
 * @param suffix set to a copy of the rest of the line, starting at the end of the match
 * @return #MHD_YES if there was a match, #MHD_NO if not
 */
static int
try_match_header (const char *prefix,
                  size_t prefix_len,
                  char *line,
                  char **suffix)
{
  if (NULL != *suffix)
    return MHD_NO;
  while (0 != *line)
  {
    if (MHD_str_equal_caseless_n_ (prefix,
                                   line,
                                   prefix_len))
    {
      *suffix = strdup (&line[prefix_len]);
      return MHD_YES;
    }
    ++line;
  }
  return MHD_NO;
}


/**
 *
 * @param pp post processor context
 * @param boundary boundary to look for
 * @param blen number of bytes in boundary
 * @param ioffptr set to the end of the boundary if found,
 *                otherwise incremented by one (FIXME: quirky API!)
 * @param next_state state to which we should advance the post processor
 *                   if the boundary is found
 * @param next_dash_state dash_state to which we should advance the
 *                   post processor if the boundary is found
 * @return #MHD_NO if the boundary is not found, #MHD_YES if we did find it
 */
static int
find_boundary (struct MHD_PostProcessor *pp,
               const char *boundary,
               size_t blen,
               size_t *ioffptr,
               enum PP_State next_state,
               enum PP_State next_dash_state)
{
  char *buf = (char *) &pp[1];
  const char *dash;

  if (pp->buffer_pos < 2 + blen)
  {
    if (pp->buffer_pos == pp->buffer_size)
      pp->state = PP_Error;     /* out of memory */
    /* ++(*ioffptr); */
    return MHD_NO;              /* not enough data */
  }
  if ( (0 != memcmp ("--",
                     buf,
                     2)) ||
       (0 != memcmp (&buf[2],
                     boundary,
                     blen)))
  {
    if (pp->state != PP_Init)
    {
      /* garbage not allowed */
      pp->state = PP_Error;
    }
    else
    {
      /* skip over garbage (RFC 2046, 5.1.1) */
      dash = memchr (buf,
                     '-',
                     pp->buffer_pos);
      if (NULL == dash)
        (*ioffptr) += pp->buffer_pos;     /* skip entire buffer */
      else if (dash == buf)
        (*ioffptr)++;       /* at least skip one byte */
      else
        (*ioffptr) += dash - buf;       /* skip to first possible boundary */
    }
    return MHD_NO;              /* expected boundary */
  }
  /* remove boundary from buffer */
  (*ioffptr) += 2 + blen;
  /* next: start with headers */
  pp->skip_rn = RN_Dash;
  pp->state = next_state;
  pp->dash_state = next_dash_state;
  return MHD_YES;
}


/**
 * In buf, there maybe an expression '$key="$value"'.  If that is the
 * case, copy a copy of $value to destination.
 *
 * If destination is already non-NULL, do nothing.
 */
static void
try_get_value (const char *buf,
               const char *key,
               char **destination)
{
  const char *spos;
  const char *bpos;
  const char *endv;
  size_t klen;
  size_t vlen;

  if (NULL != *destination)
    return;
  bpos = buf;
  klen = strlen (key);
  while (NULL != (spos = strstr (bpos, key)))
  {
    if ( (spos[klen] != '=') ||
         ( (spos != buf) &&
           (spos[-1] != ' ') ) )
    {
      /* no match */
      bpos = spos + 1;
      continue;
    }
    if (spos[klen + 1] != '"')
      return;                   /* not quoted */
    if (NULL == (endv = strchr (&spos[klen + 2],
                                '\"')))
      return;                   /* no end-quote */
    vlen = endv - spos - klen - 1;
    *destination = malloc (vlen);
    if (NULL == *destination)
      return;                   /* out of memory */
    (*destination)[vlen - 1] = '\0';
    memcpy (*destination,
            &spos[klen + 2],
            vlen - 1);
    return;                     /* success */
  }
}


/**
 * Go over the headers of the part and update
 * the fields in "pp" according to what we find.
 * If we are at the end of the headers (as indicated
 * by an empty line), transition into next_state.
 *
 * @param pp post processor context
 * @param ioffptr set to how many bytes have been
 *                processed
 * @param next_state state to which the post processor should
 *                be advanced if we find the end of the headers
 * @return #MHD_YES if we can continue processing,
 *         #MHD_NO on error or if we do not have
 *                enough data yet
 */
static int
process_multipart_headers (struct MHD_PostProcessor *pp,
                           size_t *ioffptr,
                           enum PP_State next_state)
{
  char *buf = (char *) &pp[1];
  size_t newline;

  newline = 0;
  while ( (newline < pp->buffer_pos) &&
          (buf[newline] != '\r') &&
          (buf[newline] != '\n') )
    newline++;
  if (newline == pp->buffer_size)
  {
    pp->state = PP_Error;
    return MHD_NO;              /* out of memory */
  }
  if (newline == pp->buffer_pos)
    return MHD_NO;              /* will need more data */
  if (0 == newline)
  {
    /* empty line - end of headers */
    pp->skip_rn = RN_Full;
    pp->state = next_state;
    return MHD_YES;
  }
  /* got an actual header */
  if (buf[newline] == '\r')
    pp->skip_rn = RN_OptN;
  buf[newline] = '\0';
  if (MHD_str_equal_caseless_n_ ("Content-disposition: ",
                                 buf,
                                 MHD_STATICSTR_LEN_ ("Content-disposition: ")))
  {
    try_get_value (&buf[MHD_STATICSTR_LEN_ ("Content-disposition: ")],
                   "name",
                   &pp->content_name);
    try_get_value (&buf[MHD_STATICSTR_LEN_ ("Content-disposition: ")],
                   "filename",
                   &pp->content_filename);
  }
  else
  {
    try_match_header ("Content-type: ",
                      MHD_STATICSTR_LEN_ ("Content-type: "),
                      buf,
                      &pp->content_type);
    try_match_header ("Content-Transfer-Encoding: ",
                      MHD_STATICSTR_LEN_ ("Content-Transfer-Encoding: "),
                      buf,
                      &pp->content_transfer_encoding);
  }
  (*ioffptr) += newline + 1;
  return MHD_YES;
}


/**
 * We have the value until we hit the given boundary;
 * process accordingly.
 *
 * @param pp post processor context
 * @param ioffptr incremented based on the number of bytes processed
 * @param boundary the boundary to look for
 * @param blen strlen(boundary)
 * @param next_state what state to go into after the
 *        boundary was found
 * @param next_dash_state state to go into if the next
 *        boundary ends with "--"
 * @return #MHD_YES if we can continue processing,
 *         #MHD_NO on error or if we do not have
 *                enough data yet
 */
static int
process_value_to_boundary (struct MHD_PostProcessor *pp,
                           size_t *ioffptr,
                           const char *boundary,
                           size_t blen,
                           enum PP_State next_state,
                           enum PP_State next_dash_state)
{
  char *buf = (char *) &pp[1];
  size_t newline;
  const char *r;

  /* all data in buf until the boundary
     (\r\n--+boundary) is part of the value */
  newline = 0;
  while (1)
  {
    while (newline + 4 < pp->buffer_pos)
    {
      r = memchr (&buf[newline],
                  '\r',
                  pp->buffer_pos - newline - 4);
      if (NULL == r)
      {
        newline = pp->buffer_pos - 4;
        break;
      }
      newline = r - buf;
      if (0 == memcmp ("\r\n--",
                       &buf[newline],
                       4))
        break;
      newline++;
    }
    if (newline + blen + 4 <= pp->buffer_pos)
    {
      /* can check boundary */
      if (0 != memcmp (&buf[newline + 4],
                       boundary,
                       blen))
      {
        /* no boundary, "\r\n--" is part of content, skip */
        newline += 4;
        continue;
      }
      else
      {
        /* boundary found, process until newline then
           skip boundary and go back to init */
        pp->skip_rn = RN_Dash;
        pp->state = next_state;
        pp->dash_state = next_dash_state;
        (*ioffptr) += blen + 4;             /* skip boundary as well */
        buf[newline] = '\0';
        break;
      }
    }
    else
    {
      /* cannot check for boundary, process content that
         we have and check again later; except, if we have
         no content, abort (out of memory) */
      if ( (0 == newline) &&
           (pp->buffer_pos == pp->buffer_size) )
      {
        pp->state = PP_Error;
        return MHD_NO;
      }
      break;
    }
  }
  /* newline is either at beginning of boundary or
     at least at the last character that we are sure
     is not part of the boundary */
  if ( ( (pp->must_ikvi) ||
         (0 != newline) ) &&
       (MHD_NO == pp->ikvi (pp->cls,
                            MHD_POSTDATA_KIND,
                            pp->content_name,
                            pp->content_filename,
                            pp->content_type,
                            pp->content_transfer_encoding,
                            buf,
                            pp->value_offset,
                            newline)) )
  {
    pp->state = PP_Error;
    return MHD_NO;
  }
  pp->must_ikvi = false;
  pp->value_offset += newline;
  (*ioffptr) += newline;
  return MHD_YES;
}


/**
 *
 * @param pp post processor context
 */
static void
free_unmarked (struct MHD_PostProcessor *pp)
{
  if ( (NULL != pp->content_name) &&
       (0 == (pp->have & NE_content_name)) )
  {
    free (pp->content_name);
    pp->content_name = NULL;
  }
  if ( (NULL != pp->content_type) &&
       (0 == (pp->have & NE_content_type)) )
  {
    free (pp->content_type);
    pp->content_type = NULL;
  }
  if ( (NULL != pp->content_filename) &&
       (0 == (pp->have & NE_content_filename)) )
  {
    free (pp->content_filename);
    pp->content_filename = NULL;
  }
  if ( (NULL != pp->content_transfer_encoding) &&
       (0 == (pp->have & NE_content_transfer_encoding)) )
  {
    free (pp->content_transfer_encoding);
    pp->content_transfer_encoding = NULL;
  }
}


/**
 * Decode multipart POST data.
 *
 * @param pp post processor context
 * @param post_data data to decode
 * @param post_data_len number of bytes in @a post_data
 * @return #MHD_NO on error,
 */
static int
post_process_multipart (struct MHD_PostProcessor *pp,
                        const char *post_data,
                        size_t post_data_len)
{
  char *buf;
  size_t max;
  size_t ioff;
  size_t poff;
  int state_changed;

  buf = (char *) &pp[1];
  ioff = 0;
  poff = 0;
  state_changed = 1;
  while ( (poff < post_data_len) ||
          ( (pp->buffer_pos > 0) &&
            (0 != state_changed) ) )
  {
    /* first, move as much input data
       as possible to our internal buffer */
    max = pp->buffer_size - pp->buffer_pos;
    if (max > post_data_len - poff)
      max = post_data_len - poff;
    memcpy (&buf[pp->buffer_pos],
            &post_data[poff],
            max);
    poff += max;
    pp->buffer_pos += max;
    if ( (0 == max) &&
         (0 == state_changed) &&
         (poff < post_data_len) )
    {
      pp->state = PP_Error;
      return MHD_NO;            /* out of memory */
    }
    state_changed = 0;

    /* first state machine for '\r'-'\n' and '--' handling */
    switch (pp->skip_rn)
    {
    case RN_Inactive:
      break;
    case RN_OptN:
      if (buf[0] == '\n')
      {
        ioff++;
        pp->skip_rn = RN_Inactive;
        goto AGAIN;
      }
    /* fall-through! */
    case RN_Dash:
      if (buf[0] == '-')
      {
        ioff++;
        pp->skip_rn = RN_Dash2;
        goto AGAIN;
      }
      pp->skip_rn = RN_Full;
    /* fall-through! */
    case RN_Full:
      if (buf[0] == '\r')
      {
        if ( (pp->buffer_pos > 1) &&
             ('\n' == buf[1]) )
        {
          pp->skip_rn = RN_Inactive;
          ioff += 2;
        }
        else
        {
          pp->skip_rn = RN_OptN;
          ioff++;
        }
        goto AGAIN;
      }
      if (buf[0] == '\n')
      {
        ioff++;
        pp->skip_rn = RN_Inactive;
        goto AGAIN;
      }
      pp->skip_rn = RN_Inactive;
      pp->state = PP_Error;
      return MHD_NO;            /* no '\r\n' */
    case RN_Dash2:
      if (buf[0] == '-')
      {
        ioff++;
        pp->skip_rn = RN_Full;
        pp->state = pp->dash_state;
        goto AGAIN;
      }
      pp->state = PP_Error;
      break;
    }

    /* main state engine */
    switch (pp->state)
    {
    case PP_Error:
      return MHD_NO;
    case PP_Done:
      /* did not expect to receive more data */
      pp->state = PP_Error;
      return MHD_NO;
    case PP_Init:
      /**
       * Per RFC2046 5.1.1 NOTE TO IMPLEMENTORS, consume anything
       * prior to the first multipart boundary:
       *
       * > There appears to be room for additional information prior
       * > to the first boundary delimiter line and following the
       * > final boundary delimiter line.  These areas should
       * > generally be left blank, and implementations must ignore
       * > anything that appears before the first boundary delimiter
       * > line or after the last one.
       */(void) find_boundary (pp,
                            pp->boundary,
                            pp->blen,
                            &ioff,
                            PP_ProcessEntryHeaders,
                            PP_Done);
      break;
    case PP_NextBoundary:
      if (MHD_NO == find_boundary (pp,
                                   pp->boundary,
                                   pp->blen,
                                   &ioff,
                                   PP_ProcessEntryHeaders,
                                   PP_Done))
      {
        if (pp->state == PP_Error)
          return MHD_NO;
        goto END;
      }
      break;
    case PP_ProcessEntryHeaders:
      pp->must_ikvi = true;
      if (MHD_NO ==
          process_multipart_headers (pp,
                                     &ioff,
                                     PP_PerformCheckMultipart))
      {
        if (pp->state == PP_Error)
          return MHD_NO;
        else
          goto END;
      }
      state_changed = 1;
      break;
    case PP_PerformCheckMultipart:
      if ( (NULL != pp->content_type) &&
           (MHD_str_equal_caseless_n_ (pp->content_type,
                                       "multipart/mixed",
                                       MHD_STATICSTR_LEN_ ("multipart/mixed"))))
      {
        pp->nested_boundary = strstr (pp->content_type,
                                      "boundary=");
        if (NULL == pp->nested_boundary)
        {
          pp->state = PP_Error;
          return MHD_NO;
        }
        pp->nested_boundary =
          strdup (&pp->nested_boundary[MHD_STATICSTR_LEN_ ("boundary=")]);
        if (NULL == pp->nested_boundary)
        {
          /* out of memory */
          pp->state = PP_Error;
          return MHD_NO;
        }
        /* free old content type, we will need that field
           for the content type of the nested elements */
        free (pp->content_type);
        pp->content_type = NULL;
        pp->nlen = strlen (pp->nested_boundary);
        pp->state = PP_Nested_Init;
        state_changed = 1;
        break;
      }
      pp->state = PP_ProcessValueToBoundary;
      pp->value_offset = 0;
      state_changed = 1;
      break;
    case PP_ProcessValueToBoundary:
      if (MHD_NO == process_value_to_boundary (pp,
                                               &ioff,
                                               pp->boundary,
                                               pp->blen,
                                               PP_PerformCleanup,
                                               PP_Done))
      {
        if (pp->state == PP_Error)
          return MHD_NO;
        break;
      }
      break;
    case PP_PerformCleanup:
      /* clean up state of one multipart form-data element! */
      pp->have = NE_none;
      free_unmarked (pp);
      if (NULL != pp->nested_boundary)
      {
        free (pp->nested_boundary);
        pp->nested_boundary = NULL;
      }
      pp->state = PP_ProcessEntryHeaders;
      state_changed = 1;
      break;
    case PP_Nested_Init:
      if (NULL == pp->nested_boundary)
      {
        pp->state = PP_Error;
        return MHD_NO;
      }
      if (MHD_NO == find_boundary (pp,
                                   pp->nested_boundary,
                                   pp->nlen,
                                   &ioff,
                                   PP_Nested_PerformMarking,
                                   PP_NextBoundary /* or PP_Error? */))
      {
        if (pp->state == PP_Error)
          return MHD_NO;
        goto END;
      }
      break;
    case PP_Nested_PerformMarking:
      /* remember what headers were given
         globally */
      pp->have = NE_none;
      if (NULL != pp->content_name)
        pp->have |= NE_content_name;
      if (NULL != pp->content_type)
        pp->have |= NE_content_type;
      if (NULL != pp->content_filename)
        pp->have |= NE_content_filename;
      if (NULL != pp->content_transfer_encoding)
        pp->have |= NE_content_transfer_encoding;
      pp->state = PP_Nested_ProcessEntryHeaders;
      state_changed = 1;
      break;
    case PP_Nested_ProcessEntryHeaders:
      pp->value_offset = 0;
      if (MHD_NO ==
          process_multipart_headers (pp,
                                     &ioff,
                                     PP_Nested_ProcessValueToBoundary))
      {
        if (pp->state == PP_Error)
          return MHD_NO;
        else
          goto END;
      }
      state_changed = 1;
      break;
    case PP_Nested_ProcessValueToBoundary:
      if (MHD_NO == process_value_to_boundary (pp,
                                               &ioff,
                                               pp->nested_boundary,
                                               pp->nlen,
                                               PP_Nested_PerformCleanup,
                                               PP_NextBoundary))
      {
        if (pp->state == PP_Error)
          return MHD_NO;
        break;
      }
      break;
    case PP_Nested_PerformCleanup:
      free_unmarked (pp);
      pp->state = PP_Nested_ProcessEntryHeaders;
      state_changed = 1;
      break;
    default:
      mhd_panic (mhd_panic_cls,
                 __FILE__,
                 __LINE__,
                 NULL);              /* should never happen! */
    }
AGAIN:
    if (ioff > 0)
    {
      memmove (buf,
               &buf[ioff],
               pp->buffer_pos - ioff);
      pp->buffer_pos -= ioff;
      ioff = 0;
      state_changed = 1;
    }
  }
END:
  if (0 != ioff)
  {
    memmove (buf,
             &buf[ioff],
             pp->buffer_pos - ioff);
    pp->buffer_pos -= ioff;
  }
  if (poff < post_data_len)
  {
    pp->state = PP_Error;
    return MHD_NO;              /* serious error */
  }
  return MHD_YES;
}


/**
 * Parse and process POST data.  Call this function when POST data is
 * available (usually during an #MHD_AccessHandlerCallback) with the
 * "upload_data" and "upload_data_size".  Whenever possible, this will
 * then cause calls to the #MHD_PostDataIterator.
 *
 * @param pp the post processor
 * @param post_data @a post_data_len bytes of POST data
 * @param post_data_len length of @a post_data
 * @return #MHD_YES on success, #MHD_NO on error
 *         (out-of-memory, iterator aborted, parse error)
 * @ingroup request
 */
int
MHD_post_process (struct MHD_PostProcessor *pp,
                  const char *post_data,
                  size_t post_data_len)
{
  if (0 == post_data_len)
    return MHD_YES;
  if (NULL == pp)
    return MHD_NO;
  if (MHD_str_equal_caseless_n_ (MHD_HTTP_POST_ENCODING_FORM_URLENCODED,
                                 pp->encoding,
                                 MHD_STATICSTR_LEN_ (
                                   MHD_HTTP_POST_ENCODING_FORM_URLENCODED)))
    return post_process_urlencoded (pp,
                                    post_data,
                                    post_data_len);
  if (MHD_str_equal_caseless_n_ (MHD_HTTP_POST_ENCODING_MULTIPART_FORMDATA,
                                 pp->encoding,
                                 MHD_STATICSTR_LEN_ (
                                   MHD_HTTP_POST_ENCODING_MULTIPART_FORMDATA)))
    return post_process_multipart (pp,
                                   post_data,
                                   post_data_len);
  /* this should never be reached */
  return MHD_NO;
}


/**
 * Release PostProcessor resources.
 *
 * @param pp post processor context to destroy
 * @return #MHD_YES if processing completed nicely,
 *         #MHD_NO if there were spurious characters / formatting
 *                problems; it is common to ignore the return
 *                value of this function
 * @ingroup request
 */
int
MHD_destroy_post_processor (struct MHD_PostProcessor *pp)
{
  int ret;

  if (NULL == pp)
    return MHD_YES;
  if (PP_ProcessValue == pp->state)
  {
    /* key without terminated value left at the end of the
       buffer; fake receiving a termination character to
       ensure it is also processed */
    post_process_urlencoded (pp,
                             "\n",
                             1);
  }
  /* These internal strings need cleaning up since
     the post-processing may have been interrupted
     at any stage */
  if ( (pp->xbuf_pos > 0) ||
       (pp->state != PP_Done) )
    ret = MHD_NO;
  else
    ret = MHD_YES;
  pp->have = NE_none;
  free_unmarked (pp);
  if (NULL != pp->nested_boundary)
    free (pp->nested_boundary);
  free (pp);
  return ret;
}


/* end of postprocessor.c */