summaryrefslogtreecommitdiff
path: root/libmailutils/filter/xml.c
blob: 85f9dbadfdcacfb07914d10dd492660b0e6579c6 (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
/* GNU Mailutils -- a suite of utilities for electronic mail
   Copyright (C) 2014-2018 Free Software Foundation, Inc.

   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 3, 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 GNU Mailutils.  If not, see <http://www.gnu.org/licenses/>. */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <mailutils/errno.h>
#include <mailutils/filter.h>
#include <mailutils/cctype.h>

/* In the "encode" mode, the "xml" filter takes a stream of UTF-8
   characters as its input, converts the three XML entities as per
   table below and replaces invalid characters (see
   http://www.w3.org/TR/xml/#charsets) with their numeric character
   reference representation as per http://www.w3.org/TR/xml/#dt-charref.

   In decode mode, the filter does the reverse.
   
   Special conversions:
   
    Decode       Encode
   ---------+------------- 
      <     +     &lt;
      >     +     &gt;
      &     +     &amp;
 */

struct transcode_map
{
  const char *ent;
  size_t len;
  int ch;
};

/* Note: entries in this array must be lexicographically sorted by the
   ent member. */
static struct transcode_map transcode_map[] = {
#define S(s) s, sizeof(s) - 1
  { S("&amp;"), '&' },
  { S("&gt;"), '>' },
  { S("&lt;"), '<' },
#undef S
  { NULL }
};

static struct transcode_map *
ch2ent (int c)
{
  struct transcode_map *p;

  for (p = transcode_map; p->ent; p++) 
    {
      if (p->ch == c)
	return p;
    }
  return NULL;
}

struct xml_encode_state
{
  char buf[11]; /* Enough to acomodate &#x10FFFF; - max. UTF-8 codepoint */
  int idx;
};

static int
utf8_char_width(unsigned char ch)
{
    if (ch <= 0x7f)
        return 1;
    if (0xc2 <= ch && ch <= 0xdf)
        return 2;
    if (0xe0 <= ch && ch <= 0xef)
        return 3;
    if (0xf0 <= ch && ch <= 0xf4)
        return 4;
    return 0;
}

#ifndef ENODATA
# define ENODATA EINVAL
#endif

static int
utf8_mbtowc (unsigned char const *s, size_t l, unsigned int *pwc)
{
  if (l == 0)
    {
      errno = ENODATA;
      return -1;
    }
  
  if (s[0] < 0x80)
    {
      *pwc = s[0];
      return 1;
    }

  if (s[0] < 0xc2)
    {
      errno = EILSEQ;
      return -1;
    }
  else if (s[0] < 0xe0)
    {
      if (l < 2)
        {
	  errno = ENODATA;
	  return -1;
	}
      if (!((s[1] ^ 0x80) < 0x40))
	{
	  errno = EILSEQ;
	  return -1;
        }
      *pwc = ((unsigned int) (s[0] & 0x1f) << 6) |
	      (unsigned int) (s[1] ^ 0x80);
      return 2;
    }

  if (s[0] < 0xf0)
    {
      if (l < 3)
        {
	  errno = ENODATA;
	  return -1;
	}

      if (!((s[1] ^ 0x80) < 0x40
	    && (s[2] ^ 0x80) < 0x40 && (s[0] >= 0xe1 || s[1] >= 0xa0)))
	{
	  errno = EILSEQ;
	  return -1;
        }
      
      *pwc = ((unsigned long) (s[0] & 0x0f) << 12) |
              ((unsigned long) (s[1] ^ 0x80) << 6) |
               (unsigned long) (s[2] ^ 0x80);

      return 3;
    }
    if (s[0] < 0xf8)
      {
	if (l < 4)
	  {
	    errno = ENODATA;
	    return -1;
	  }

        if (!((s[1] ^ 0x80) < 0x40 &&
              (s[2] ^ 0x80) < 0x40 &&
              (s[3] ^ 0x80) < 0x40 && (s[0] >= 0xf1 || s[1] >= 0x90)))
	  {
            errno = EILSEQ;
            return -1;
	  }

        *pwc = ((unsigned long) (s[0] & 0x07) << 18) |
                ((unsigned long) (s[1] ^ 0x80) << 12) |
                ((unsigned long) (s[2] ^ 0x80) << 6) |
                (unsigned long) (s[3] ^ 0x80);

        return 4;
      }
    errno = EILSEQ;
    return -1;
}

static void
store_buf (struct xml_encode_state *cp, const char *s, size_t len)
{
  cp->idx = 0;
  s += len;
  while (len--)
    cp->buf[cp->idx++] = *--s;
}

static void
store_char_ref (struct xml_encode_state *cp, unsigned wc)
{
  char buf[11];
  snprintf (buf, sizeof buf, "&#x%x;", wc);
  store_buf (cp, buf, strlen (buf));
}

static enum mu_filter_result
_xml_encoder (void *xd,
	      enum mu_filter_command cmd,
	      struct mu_filter_io *iobuf)
{
  struct xml_encode_state *cp = xd;
  const unsigned char *iptr;
  size_t isize;
  char *optr;
  size_t osize;
  
  switch (cmd)
    {
    case mu_filter_init:
      cp->idx = -1;
      return mu_filter_ok;
      
    case mu_filter_done:
      return mu_filter_ok;
      
    default:
      break;
    }

  iptr = (unsigned char*) iobuf->input;
  isize = iobuf->isize;
  optr = iobuf->output;
  osize = iobuf->osize;

  while (osize)
    {
      if (cp->idx > 0)
	{
	  *optr++ = cp->buf[--cp->idx];
	  --osize;
	}
      else if (isize == 0)
	break;
      else
	{
	  struct transcode_map *p;
	  unsigned int c = *iptr;

	  p = ch2ent (c);
	  if (p)
	    {
	      store_buf (cp, p->ent, p->len);
	      ++iptr;
	      --isize;
	    }
	  else
	    {
	      int count = utf8_char_width (c);

	      if (count == 0)
		{
		  store_char_ref (cp, *iptr);
		  ++iptr;
		  --isize;
		}
	      else if (count > isize)
		{
		  if (cmd == mu_filter_lastbuf)
		    {
		      store_buf (cp, (char*) iptr, isize);
		      iptr += isize;
		      isize = 0;
		    }
		  else
		    break;
		}
	      else
		{
		  unsigned wc;
		  int rc;

		  rc = utf8_mbtowc (iptr, isize, &wc);
		  
		  if (rc == -1)
		    {	
		      store_char_ref (cp, *iptr);
		      ++iptr;
		      --isize;
		    }
		  else
		    {
/* http://www.w3.org/TR/xml/#dt-charref:

   Character Range

   Char ::= #x9 | #xA | #xD | [#x20-#xD7FF] |
            [#xE000-#xFFFD] | [#x10000-#x10FFFF]

   (any Unicode character, excluding the surrogate blocks, FFFE, and FFFF)
*/
		      if (wc == 0x9
			  || wc == 0xa
			  || wc == 0xd
			  || (wc >= 0x20 && wc < 0xd7ff)
			  || (wc >= 0xe000 && wc < 0xfffd)
			  || (wc >= 0x10000 && wc < 0x10FFFF))
			{
			  if (osize >= count)
			    {
			      memcpy (optr, iptr, count);
			      
			      optr += count;
			      osize -= count;

			      iptr += count;
			      isize -= count;
			    }
			  else
			    {
			      store_buf (cp, (char*) iptr, count);
			      iptr += count;
			      isize -= count;
			    }
			}
		      else
			{
                          store_char_ref (cp, wc);
			  iptr += count;
			  isize -= count;
			}
		    }
		}
	    }
	}
    }
  iobuf->isize -= isize;
  iobuf->osize -= osize;

  return mu_filter_ok;
}

enum xml_decode_phase
  {
    enc_init,
    enc_map,
    enc_rollback,
    enc_finish,
    enc_char_ref,
    enc_char_cont,
    enc_char_rollback
  };

struct xml_decode_state
{
  enum xml_decode_phase phase;   /* Decoding phase */
  struct transcode_map *map;     /* Map entry being tried */
  char buf[11]; /* Buffer for storing &# sequence -- used for rollback.
		   Regarding its dimension, see the comment to
		   xml_encode_state above. */
  int idx;      /* In enc_init and enc_map phase - index to the next
		   character in map->ent to compare;
		   In enc_rollback phase marks the point in map->ent where
		   to stop rolling back.
		   In enc_char_ref and enc_char_cont modes indicates next
		   free slot in buf.
		   In enc_char_rollback phase marks the point in buf where
		   to stop rolling back.
		*/
  int pos;      /* In enc_rollback phase - position in
		   map->ent of the next character  to restore.
		   In enc_char_rollback phase - position in buf of the next
		   character  to restore. 
		*/
  int base;     /* Base for converting &# references */
  unsigned wc;  /* Wide char being constructed from a reference */
};

#define DECODE_INIT(s)				\
  do						\
    {						\
      (s)->phase = enc_init;			\
      (s)->map = transcode_map;			\
      (s)->idx = 0;				\
    }						\
  while (0)

static enum xml_decode_phase
nextchar (struct xml_decode_state *s, int c)
{
  if (c == s->map->ent[s->idx])
    {
      if (++s->idx == s->map->len)
	s->phase = enc_finish;
      else
	s->phase = enc_map;
    }
  else if (s->phase == enc_init)
    /* nothing */;
  else if (s->idx == 1 && c == '#')
    {
      s->phase = enc_char_ref;
      s->base = 0;
      s->wc = 0;
      s->idx = 0;
      s->buf[s->idx++] = '&';
      s->buf[s->idx++] = c;
    }
  else
    {
      struct transcode_map *map;
      
      for (map = s->map; map->ent && c > map->ent[s->idx]; map++)
	;
      if (map->ent == NULL || c != map->ent[s->idx])
	{
	  if (s->idx != 0)
	    { 
	      s->phase = enc_rollback;
	      s->pos = 0;
	    }
	  else
	    DECODE_INIT (s);
	}
      else
	{
	  s->map = map;
	  if (++s->idx == s->map->len)
	    s->phase = enc_finish;
	  else
	    s->phase = enc_map;
	}
    }
  return s->phase;
}

static enum mu_filter_result
_xml_decoder (void *xd,
	      enum mu_filter_command cmd,
	      struct mu_filter_io *iobuf)
{
  struct xml_decode_state *cp = xd;
  const char *iptr;
  size_t isize;
  char *optr;
  size_t osize;

  switch (cmd)
    {
    case mu_filter_init:
      DECODE_INIT (cp);
      return mu_filter_ok;
      
    case mu_filter_done:
      return mu_filter_ok;
      
    default:
      break;
    }

  iptr = iobuf->input;
  isize = iobuf->isize;
  optr = iobuf->output;
  osize = iobuf->osize;

  while (isize && osize)
    {
      switch (cp->phase)
	{
	case enc_init:
	  nextchar (cp, *iptr);
	  if (cp->phase == enc_init)
	    {
	      *optr++ = *iptr;
	      --osize;
	    }
	  ++iptr;
	  --isize;
	  break;
	      
	case enc_map:
	  nextchar (cp, *iptr);
	  if (cp->phase == enc_map || cp->phase == enc_finish
	      || cp->phase == enc_char_ref)
	    {
	      ++iptr;
	      --isize;
	    }
	  else if (cp->phase == enc_init)
	    {
	      *optr++ = *iptr++;
	      --osize;
	      --isize;
	    }
	  break;

	case enc_finish:
	  *optr++ = cp->map->ch;
	  --osize;
	  DECODE_INIT (cp);
	  break;
	  
	case enc_rollback:
	  *optr++ = cp->map->ent[cp->pos];
	  --osize;
	  if (++cp->pos == cp->idx)
	    DECODE_INIT (cp);
	  break;

	case enc_char_ref:
	  if (*iptr == 'x')
	    {
	      cp->base = 16;
	      cp->buf[cp->idx++] = *iptr;
	      ++iptr;
	      --isize;
	    }
	  else
	    cp->base = 10;
	  cp->phase = enc_char_cont;
	  break;

	case enc_char_cont:
	  if (*iptr == ';')
	    {
	      *optr++ = cp->wc;
	      --osize;
	      ++iptr;
	      --isize;
	      DECODE_INIT (cp);
	    }
	  else if (cp->idx < MU_ARRAY_SIZE (cp->buf) && mu_isxdigit (*iptr))
	    {
	      static char xdig[] = "0123456789ABCDEF";
	      int n = strchr (xdig, mu_toupper (*iptr)) - xdig;
	      cp->wc = cp->wc * cp->base + n;
	      cp->buf[cp->idx++] = *iptr;
	      ++iptr;
	      --isize;
	    }
	  else
	    {
	      cp->phase = enc_char_rollback;
	      cp->pos = 0;
	    }
	  break;

	case enc_char_rollback:
	  *optr++ = cp->buf[cp->pos++];
	  --osize;
	  if (cp->pos == cp->idx)
	    DECODE_INIT (cp);
	}
    }      
  iobuf->isize -= isize;
  iobuf->osize -= osize;

  return mu_filter_ok;  
}

static int
alloc_state (void **pret, int mode, int argc MU_ARG_UNUSED,
	     const char **argv MU_ARG_UNUSED)
{
  union
  {
    struct xml_encode_state encode;
    struct xml_decode_state decode;
  } *cp;
    

  switch (mode)
    {
    case MU_FILTER_ENCODE:
      cp = malloc (sizeof (cp->encode));
      if (!cp)
	return ENOMEM;
      cp->encode.idx = -1;
      break;

    case MU_FILTER_DECODE:
      cp = malloc (sizeof (cp->decode));
      if (!cp)
	return ENOMEM;
      cp->decode.idx = 0;
      cp->decode.map = transcode_map;
      break;

    default:
      abort ();
    }
      
  *pret = cp;
  return 0;
}

static struct _mu_filter_record _xml_filter = {
  "xml",
  alloc_state,
  _xml_encoder,
  _xml_decoder
};

mu_filter_record_t mu_xml_filter = &_xml_filter;


Return to:

Send suggestions and report system problems to the System administrator.