aboutsummaryrefslogtreecommitdiff
path: root/libidn/idna.c
blob: bf692c029beb506eba51c7fcf2ff728c04885acd (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
/* idna.c	Convert to or from IDN strings.
 * Copyright (C) 2002, 2003, 2004  Simon Josefsson
 *
 * This file is part of GNU Libidn.
 *
 * GNU Libidn 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.
 *
 * GNU Libidn 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 Libidn; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

#if HAVE_CONFIG_H
# include "config.h"
#endif

#include <stdlib.h>
#include <string.h>
#include <stringprep.h>
#include <punycode.h>

#include "idna.h"

#define DOTP(c) ((c) == 0x002E || (c) == 0x3002 ||	\
		 (c) == 0xFF0E || (c) == 0xFF61)

/* Core functions */

/**
 * idna_to_ascii_4i
 * @in: input array with unicode code points.
 * @inlen: length of input array with unicode code points.
 * @out: output zero terminated string that must have room for at
 *       least 63 characters plus the terminating zero.
 * @flags: IDNA flags, e.g. IDNA_ALLOW_UNASSIGNED or IDNA_USE_STD3_ASCII_RULES.
 *
 * The ToASCII operation takes a sequence of Unicode code points that make
 * up one label and transforms it into a sequence of code points in the
 * ASCII range (0..7F). If ToASCII succeeds, the original sequence and the
 * resulting sequence are equivalent labels.
 *
 * It is important to note that the ToASCII operation can fail. ToASCII
 * fails if any step of it fails. If any step of the ToASCII operation
 * fails on any label in a domain name, that domain name MUST NOT be used
 * as an internationalized domain name. The method for deadling with this
 * failure is application-specific.
 *
 * The inputs to ToASCII are a sequence of code points, the AllowUnassigned
 * flag, and the UseSTD3ASCIIRules flag. The output of ToASCII is either a
 * sequence of ASCII code points or a failure condition.
 *
 * ToASCII never alters a sequence of code points that are all in the ASCII
 * range to begin with (although it could fail). Applying the ToASCII
 * operation multiple times has exactly the same effect as applying it just
 * once.
 *
 * Return value: Returns 0 on success, or an error code.
 */
int
idna_to_ascii_4i (const uint32_t * in, size_t inlen, char *out, int flags)
{
  size_t len, outlen;
  uint32_t *src;		/* XXX don't need to copy data? */
  int rc;

  /*
   * ToASCII consists of the following steps:
   *
   * 1. If all code points in the sequence are in the ASCII range (0..7F)
   * then skip to step 3.
   */

  {
    size_t i;
    int inasciirange;

    inasciirange = 1;
    for (i = 0; i < inlen; i++)
      if (in[i] > 0x7F)
	inasciirange = 0;
    if (inasciirange)
      {
	src = malloc (sizeof (in[0]) * (inlen + 1));
	if (src == NULL)
	  return IDNA_MALLOC_ERROR;

	memcpy (src, in, sizeof (in[0]) * inlen);
	src[inlen] = 0;

	goto step3;
      }
  }

  /*
   * 2. Perform the steps specified in [NAMEPREP] and fail if there is
   * an error. The AllowUnassigned flag is used in [NAMEPREP].
   */

  {
    char *p;

    p = stringprep_ucs4_to_utf8 (in, inlen, NULL, NULL);
    if (p == NULL)
      return IDNA_MALLOC_ERROR;

    len = strlen (p);
    do
      {
	len = 2 * len + 10;	/* XXX better guess? */
	p = realloc (p, len);
	if (p == NULL)
	  return IDNA_MALLOC_ERROR;

	if (flags & IDNA_ALLOW_UNASSIGNED)
	  rc = stringprep_nameprep (p, len);
	else
	  rc = stringprep_nameprep_no_unassigned (p, len);
      }
    while (rc == STRINGPREP_TOO_SMALL_BUFFER);

    if (rc != STRINGPREP_OK)
      {
	free (p);
	return IDNA_STRINGPREP_ERROR;
      }

    src = stringprep_utf8_to_ucs4 (p, -1, NULL);

    free (p);
  }

step3:
  /*
   * 3. If the UseSTD3ASCIIRules flag is set, then perform these checks:
   *
   * (a) Verify the absence of non-LDH ASCII code points; that is,
   * the absence of 0..2C, 2E..2F, 3A..40, 5B..60, and 7B..7F.
   *
   * (b) Verify the absence of leading and trailing hyphen-minus;
   * that is, the absence of U+002D at the beginning and end of
   * the sequence.
   */

  if (flags & IDNA_USE_STD3_ASCII_RULES)
    {
      size_t i;

      for (i = 0; src[i]; i++)
	if (src[i] <= 0x2C || src[i] == 0x2E || src[i] == 0x2F ||
	    (src[i] >= 0x3A && src[i] <= 0x40) ||
	    (src[i] >= 0x5B && src[i] <= 0x60) ||
	    (src[i] >= 0x7B && src[i] <= 0x7F))
	  {
	    free (src);
	    return IDNA_CONTAINS_NON_LDH;
	  }

      if (src[0] == 0x002D || (i > 0 && src[i - 1] == 0x002D))
	{
	  free (src);
	  return IDNA_CONTAINS_MINUS;
	}
    }

  /*
   * 4. If all code points in the sequence are in the ASCII range
   * (0..7F), then skip to step 8.
   */

  {
    size_t i;
    int inasciirange;

    inasciirange = 1;
    for (i = 0; src[i]; i++)
      {
	if (src[i] > 0x7F)
	  inasciirange = 0;
	/* copy string to output buffer if we are about to skip to step8 */
	if (i < 64)
	  out[i] = src[i];
      }
    if (i < 64)
      out[i] = '\0';
    if (inasciirange)
      goto step8;
  }

  /*
   * 5. Verify that the sequence does NOT begin with the ACE prefix.
   *
   */

  {
    size_t i;
    int match;

    match = 1;
    for (i = 0; match && i < strlen (IDNA_ACE_PREFIX); i++)
      if (((uint32_t) IDNA_ACE_PREFIX[i] & 0xFF) != src[i])
	match = 0;
    if (match)
      {
	free (src);
	return IDNA_CONTAINS_ACE_PREFIX;
      }
  }

  /*
   * 6. Encode the sequence using the encoding algorithm in [PUNYCODE]
   * and fail if there is an error.
   */
  for (len = 0; src[len]; len++)
    ;
  src[len] = '\0';
  outlen = 63 - strlen (IDNA_ACE_PREFIX);
  rc = punycode_encode (len, src, NULL,
			&outlen, &out[strlen (IDNA_ACE_PREFIX)]);
  if (rc != PUNYCODE_SUCCESS)
    {
      free (src);
      return IDNA_PUNYCODE_ERROR;
    }
  out[strlen (IDNA_ACE_PREFIX) + outlen] = '\0';

  /*
   * 7. Prepend the ACE prefix.
   */

  memcpy (out, IDNA_ACE_PREFIX, strlen (IDNA_ACE_PREFIX));

  /*
   * 8. Verify that the number of code points is in the range 1 to 63
   * inclusive (0 is excluded).
   */

step8:
  free (src);
  if (strlen (out) < 1 || strlen (out) > 63)
    return IDNA_INVALID_LENGTH;

  return IDNA_SUCCESS;
}

/* ToUnicode().  May realloc() utf8in. */
static int
idna_to_unicode_internal (char *utf8in,
			  uint32_t * out, size_t * outlen, int flags)
{
  int rc;
  char tmpout[64];
  size_t utf8len = strlen (utf8in) + 1;
  size_t addlen = 0;

  /*
   * ToUnicode consists of the following steps:
   *
   * 1. If the sequence contains any code points outside the ASCII range
   * (0..7F) then proceed to step 2, otherwise skip to step 3.
   */

  {
    size_t i;
    int inasciirange;

    inasciirange = 1;
    for (i = 0; utf8in[i]; i++)
      if (utf8in[i] & ~0x7F)
	inasciirange = 0;
    if (inasciirange)
      goto step3;
  }

  /*
   * 2. Perform the steps specified in [NAMEPREP] and fail if there is an
   * error. (If step 3 of ToASCII is also performed here, it will not
   * affect the overall behavior of ToUnicode, but it is not
   * necessary.) The AllowUnassigned flag is used in [NAMEPREP].
   */
  do
    {
      utf8in = realloc (utf8in, utf8len + addlen);
      if (!utf8in)
	return IDNA_MALLOC_ERROR;
      if (flags & IDNA_ALLOW_UNASSIGNED)
	rc = stringprep_nameprep (utf8in, utf8len + addlen);
      else
	rc = stringprep_nameprep_no_unassigned (utf8in, utf8len + addlen);
      addlen += 1;
    }
  while (rc == STRINGPREP_TOO_SMALL_BUFFER);

  if (rc != STRINGPREP_OK)
    return IDNA_STRINGPREP_ERROR;

  /* 3. Verify that the sequence begins with the ACE prefix, and save a
   * copy of the sequence.
   */

step3:
  if (memcmp (IDNA_ACE_PREFIX, utf8in, strlen (IDNA_ACE_PREFIX)) != 0)
    return IDNA_NO_ACE_PREFIX;

  /* 4. Remove the ACE prefix.
   */

  memmove (utf8in, &utf8in[strlen (IDNA_ACE_PREFIX)],
	   strlen (utf8in) - strlen (IDNA_ACE_PREFIX) + 1);

  /* 5. Decode the sequence using the decoding algorithm in [PUNYCODE]
   * and fail if there is an error. Save a copy of the result of
   * this step.
   */

  (*outlen)--;			/* reserve one for the zero */

  rc = punycode_decode (strlen (utf8in), utf8in, outlen, out, NULL);
  if (rc != PUNYCODE_SUCCESS)
    return IDNA_PUNYCODE_ERROR;

  out[*outlen] = 0;		/* add zero */

  /* 6. Apply ToASCII.
   */

  rc = idna_to_ascii_4i (out, *outlen, tmpout, flags);
  if (rc != IDNA_SUCCESS)
    return rc;

  /* 7. Verify that the result of step 6 matches the saved copy from
   * step 3, using a case-insensitive ASCII comparison.
   */

  if (strcasecmp (utf8in, tmpout + strlen (IDNA_ACE_PREFIX)) != 0)
    return IDNA_ROUNDTRIP_VERIFY_ERROR;

  /* 8. Return the saved copy from step 5.
   */

  return IDNA_SUCCESS;
}

/**
 * idna_to_unicode_44i
 * @in: input array with unicode code points.
 * @inlen: length of input array with unicode code points.
 * @out: output array with unicode code points.
 * @outlen: on input, maximum size of output array with unicode code points,
 *          on exit, actual size of output array with unicode code points.
 * @flags: IDNA flags, e.g. IDNA_ALLOW_UNASSIGNED or IDNA_USE_STD3_ASCII_RULES.
 *
 * The ToUnicode operation takes a sequence of Unicode code points
 * that make up one label and returns a sequence of Unicode code
 * points. If the input sequence is a label in ACE form, then the
 * result is an equivalent internationalized label that is not in ACE
 * form, otherwise the original sequence is returned unaltered.
 *
 * ToUnicode never fails. If any step fails, then the original input
 * sequence is returned immediately in that step.
 *
 * The Punycode decoder can never output more code points than it
 * inputs, but Nameprep can, and therefore ToUnicode can.  Note that
 * the number of octets needed to represent a sequence of code points
 * depends on the particular character encoding used.
 *
 * The inputs to ToUnicode are a sequence of code points, the
 * AllowUnassigned flag, and the UseSTD3ASCIIRules flag. The output of
 * ToUnicode is always a sequence of Unicode code points.
 *
 * Return value: Returns error condition, but it must only be used for
 *               debugging purposes.  The output buffer is always
 *               guaranteed to contain the correct data according to
 *               the specification (sans malloc induced errors).  NB!
 *               This means that you normally ignore the return code
 *               from this function, as checking it means breaking the
 *               standard.
 */
int
idna_to_unicode_44i (const uint32_t * in, size_t inlen,
		     uint32_t * out, size_t * outlen, int flags)
{
  int rc;
  size_t outlensave = *outlen;
  char *p;

  p = stringprep_ucs4_to_utf8 (in, inlen, NULL, NULL);
  if (p == NULL)
    return IDNA_MALLOC_ERROR;

  rc = idna_to_unicode_internal (p, out, outlen, flags);
  if (rc != IDNA_SUCCESS)
    {
      memcpy (out, in, sizeof (in[0]) * (inlen < outlensave ?
					 inlen : outlensave));
      *outlen = inlen;
    }

  free (p);

  return rc;
}

/* Wrappers that handle several labels */

/**
 * idna_to_ascii_4z:
 * @input: zero terminated input Unicode string.
 * @output: pointer to newly allocated output string.
 * @flags: IDNA flags, e.g. IDNA_ALLOW_UNASSIGNED or IDNA_USE_STD3_ASCII_RULES.
 *
 * Convert UCS-4 domain name to ASCII string.  The domain name may
 * contain several labels, separated by dots.  The output buffer must
 * be deallocated by the caller.
 *
 * Return value: Returns IDNA_SUCCESS on success, or error code.
 **/
int
idna_to_ascii_4z (const uint32_t * input, char **output, int flags)
{
  const uint32_t *start = input;
  const uint32_t *end = input;
  char buf[64];
  char *out = NULL;
  int rc;

  /* 1) Whenever dots are used as label separators, the following
     characters MUST be recognized as dots: U+002E (full stop),
     U+3002 (ideographic full stop), U+FF0E (fullwidth full stop),
     U+FF61 (halfwidth ideographic full stop). */

  if (input[0] == 0)
    {
      /* Handle implicit zero-length root label. */
      *output = malloc (1);
      if (!*output)
	return IDNA_MALLOC_ERROR;
      strcpy (*output, "");
      return IDNA_SUCCESS;
    }

  if (DOTP (input[0]) && input[1] == 0)
    {
      /* Handle explicit zero-length root label. */
      *output = malloc (2);
      if (!*output)
	return IDNA_MALLOC_ERROR;
      strcpy (*output, ".");
      return IDNA_SUCCESS;
    }

  *output = NULL;
  do
    {
      end = start;

      for (; *end && !DOTP (*end); end++)
	;

      if (*end == '\0' && start == end)
	{
	  /* Handle explicit zero-length root label. */
	  buf[0] = '\0';
	}
      else
	{
	  rc = idna_to_ascii_4i (start, end - start, buf, flags);
	  if (rc != IDNA_SUCCESS)
	    return rc;
	}

      if (out)
	{
	  out = realloc (out, strlen (out) + 1 + strlen (buf) + 1);
	  if (!out)
	    return IDNA_MALLOC_ERROR;
	  strcat (out, ".");
	  strcat (out, buf);
	}
      else
	{
	  out = (char *) malloc (strlen (buf) + 1);
	  if (!out)
	    return IDNA_MALLOC_ERROR;
	  strcpy (out, buf);
	}

      start = end + 1;
    }
  while (*end);

  *output = out;

  return IDNA_SUCCESS;
}

/**
 * idna_to_ascii_8z:
 * @input: zero terminated input UTF-8 string.
 * @output: pointer to newly allocated output string.
 * @flags: IDNA flags, e.g. IDNA_ALLOW_UNASSIGNED or IDNA_USE_STD3_ASCII_RULES.
 *
 * Convert UTF-8 domain name to ASCII string.  The domain name may
 * contain several labels, separated by dots.  The output buffer must
 * be deallocated by the caller.
 *
 * Return value: Returns IDNA_SUCCESS on success, or error code.
 **/
int
idna_to_ascii_8z (const char *input, char **output, int flags)
{
  uint32_t *ucs4;
  size_t ucs4len;
  int rc;

  ucs4 = stringprep_utf8_to_ucs4 (input, -1, &ucs4len);
  if (!ucs4)
    return IDNA_ICONV_ERROR;

  rc = idna_to_ascii_4z (ucs4, output, flags);

  free (ucs4);

  return rc;

}

/**
 * idna_to_ascii_lz:
 * @input: zero terminated input UTF-8 string.
 * @output: pointer to newly allocated output string.
 * @flags: IDNA flags, e.g. IDNA_ALLOW_UNASSIGNED or IDNA_USE_STD3_ASCII_RULES.
 *
 * Convert domain name in the locale's encoding to ASCII string.  The
 * domain name may contain several labels, separated by dots.  The
 * output buffer must be deallocated by the caller.
 *
 * Return value: Returns IDNA_SUCCESS on success, or error code.
 **/
int
idna_to_ascii_lz (const char *input, char **output, int flags)
{
  char *utf8;
  int rc;

  utf8 = stringprep_locale_to_utf8 (input);
  if (!utf8)
    return IDNA_ICONV_ERROR;

  rc = idna_to_ascii_8z (utf8, output, flags);

  free (utf8);

  return rc;
}

/**
 * idna_to_unicode_4z4z:
 * @input: zero-terminated Unicode string.
 * @output: pointer to newly allocated output Unicode string.
 * @flags: IDNA flags, e.g. IDNA_ALLOW_UNASSIGNED or IDNA_USE_STD3_ASCII_RULES.
 *
 * Convert possibly ACE encoded domain name in UCS-4 format into a
 * UCS-4 string.  The domain name may contain several labels,
 * separated by dots.  The output buffer must be deallocated by the
 * caller.
 *
 * Return value: Returns IDNA_SUCCESS on success, or error code.
 **/
int
idna_to_unicode_4z4z (const uint32_t * input, uint32_t ** output, int flags)
{
  const uint32_t *start = input;
  const uint32_t *end = input;
  uint32_t *buf;
  size_t buflen;
  uint32_t *out = NULL;
  size_t outlen = 0;
  int rc;

  *output = NULL;

  do
    {
      end = start;

      for (; *end && !DOTP (*end); end++)
	;

      buflen = end - start;
      buf = malloc (sizeof (buf[0]) * (buflen + 1));
      if (!buf)
	return IDNA_MALLOC_ERROR;

      rc = idna_to_unicode_44i (start, end - start, buf, &buflen, flags);
      /* don't check rc as per specification! */

      if (out)
	{
	  out = realloc (out, sizeof (out[0]) * (outlen + 1 + buflen + 1));
	  if (!out)
	    return IDNA_MALLOC_ERROR;
	  out[outlen++] = 0x002E;	/* '.' (full stop) */
	  memcpy (out + outlen, buf, sizeof (buf[0]) * buflen);
	  outlen += buflen;
	  out[outlen] = 0x0;
	  free (buf);
	}
      else
	{
	  out = buf;
	  outlen = buflen;
	  out[outlen] = 0x0;
	}

      start = end + 1;
    }
  while (*end);

  *output = out;

  return IDNA_SUCCESS;
}

/**
 * idna_to_unicode_8z4z:
 * @input: zero-terminated UTF-8 string.
 * @output: pointer to newly allocated output Unicode string.
 * @flags: IDNA flags, e.g. IDNA_ALLOW_UNASSIGNED or IDNA_USE_STD3_ASCII_RULES.
 *
 * Convert possibly ACE encoded domain name in UTF-8 format into a
 * UCS-4 string.  The domain name may contain several labels,
 * separated by dots.  The output buffer must be deallocated by the
 * caller.
 *
 * Return value: Returns IDNA_SUCCESS on success, or error code.
 **/
int
idna_to_unicode_8z4z (const char *input, uint32_t ** output, int flags)
{
  uint32_t *ucs4;
  size_t ucs4len;
  int rc;

  ucs4 = stringprep_utf8_to_ucs4 (input, -1, &ucs4len);
  if (!ucs4)
    return IDNA_ICONV_ERROR;

  rc = idna_to_unicode_4z4z (ucs4, output, flags);
  free (ucs4);

  return rc;
}

/**
 * idna_to_unicode_8z8z:
 * @input: zero-terminated UTF-8 string.
 * @output: pointer to newly allocated output UTF-8 string.
 * @flags: IDNA flags, e.g. IDNA_ALLOW_UNASSIGNED or IDNA_USE_STD3_ASCII_RULES.
 *
 * Convert possibly ACE encoded domain name in UTF-8 format into a
 * UTF-8 string.  The domain name may contain several labels,
 * separated by dots.  The output buffer must be deallocated by the
 * caller.
 *
 * Return value: Returns IDNA_SUCCESS on success, or error code.
 **/
int
idna_to_unicode_8z8z (const char *input, char **output, int flags)
{
  uint32_t *ucs4;
  int rc;

  rc = idna_to_unicode_8z4z (input, &ucs4, flags);
  *output = stringprep_ucs4_to_utf8 (ucs4, -1, NULL, NULL);
  free (ucs4);

  if (!*output)
    return IDNA_ICONV_ERROR;

  return rc;
}

/**
 * idna_to_unicode_8zlz:
 * @input: zero-terminated UTF-8 string.
 * @output: pointer to newly allocated output string encoded in the
 *   current locale's character set.
 * @flags: IDNA flags, e.g. IDNA_ALLOW_UNASSIGNED or IDNA_USE_STD3_ASCII_RULES.
 *
 * Convert possibly ACE encoded domain name in UTF-8 format into a
 * string encoded in the current locale's character set.  The domain
 * name may contain several labels, separated by dots.  The output
 * buffer must be deallocated by the caller.
 *
 * Return value: Returns IDNA_SUCCESS on success, or error code.
 **/
int
idna_to_unicode_8zlz (const char *input, char **output, int flags)
{
  char *utf8;
  int rc;

  rc = idna_to_unicode_8z8z (input, &utf8, flags);
  *output = stringprep_utf8_to_locale (utf8);
  free (utf8);

  if (!*output)
    return IDNA_ICONV_ERROR;

  return rc;
}

/**
 * idna_to_unicode_lzlz:
 * @input: zero-terminated string encoded in the current locale's
 *   character set.
 * @output: pointer to newly allocated output string encoded in the
 *   current locale's character set.
 * @flags: IDNA flags, e.g. IDNA_ALLOW_UNASSIGNED or IDNA_USE_STD3_ASCII_RULES.
 *
 * Convert possibly ACE encoded domain name in the locale's character
 * set into a string encoded in the current locale's character set.
 * The domain name may contain several labels, separated by dots.  The
 * output buffer must be deallocated by the caller.
 *
 * Return value: Returns IDNA_SUCCESS on success, or error code.
 **/
int
idna_to_unicode_lzlz (const char *input, char **output, int flags)
{
  char *utf8;
  int rc;

  utf8 = stringprep_locale_to_utf8 (input);
  if (!utf8)
    return IDNA_ICONV_ERROR;

  rc = idna_to_unicode_8zlz (utf8, output, flags);
  free (utf8);

  return rc;
}

/**
 * IDNA_ACE_PREFIX
 *
 * The IANA allocated prefix to use for IDNA. "xn--"
 */

/**
 * Idna_rc:
 * @IDNA_SUCCESS: Successful operation.  This value is guaranteed to
 *   always be zero, the remaining ones are only guaranteed to hold
 *   non-zero values, for logical comparison purposes.
 * @IDNA_STRINGPREP_ERROR:  Error during string preparation.
 * @IDNA_PUNYCODE_ERROR: Error during punycode operation.
 * @IDNA_CONTAINS_NON_LDH: For IDNA_USE_STD3_ASCII_RULES, indicate that
 *   the string contains non-LDH ASCII characters.
 * @IDNA_CONTAINS_MINUS: For IDNA_USE_STD3_ASCII_RULES, indicate that
 *   the string contains a leading or trailing hyphen-minus (U+002D).
 * @IDNA_INVALID_LENGTH: The final output string is not within the
 *   (inclusive) range 1 to 63 characters.
 * @IDNA_NO_ACE_PREFIX: The string does not contain the ACE prefix
 *   (for ToUnicode).
 * @IDNA_ROUNDTRIP_VERIFY_ERROR: The ToASCII operation on output
 *   string does not equal the input.
 * @IDNA_CONTAINS_ACE_PREFIX: The input contains the ACE prefix (for
 *   ToASCII).
 * @IDNA_ICONV_ERROR: Could not convert string in locale encoding.
 * @IDNA_MALLOC_ERROR: Could not allocate buffer (this is typically a
 *   fatal error).
 * @IDNA_DLOPEN_ERROR: Could not dlopen the libcidn DSO (only used
 *   internally in libc).
 *
 * Enumerated return codes of idna_to_ascii_4i(),
 * idna_to_unicode_44i() functions (and functions derived from those
 * functions).  The value 0 is guaranteed to always correspond to
 * success.
 */


/**
 * Idna_flags:
 * @IDNA_ALLOW_UNASSIGNED: Don't reject strings containing unassigned
 *   Unicode code points.
 * @IDNA_USE_STD3_ASCII_RULES: Validate strings according to STD3
 *   rules (i.e., normal host name rules).
 *
 * Flags to pass to idna_to_ascii_4i(), idna_to_unicode_44i() etc.
 */