aboutsummaryrefslogtreecommitdiff
path: root/libidn/stringprep.c
blob: 1841b36178aca132d3ddce13be2abe48cf8bcdce (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
/* stringprep.c --- Core stringprep implementation.
 * 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"

static ssize_t
stringprep_find_character_in_table (uint32_t ucs4,
				    const Stringprep_table_element * table)
{
  ssize_t i;

  /* This is where typical uses of Libidn spends very close to all CPU
     time and causes most cache misses.  One could easily do a binary
     search instead.  Before rewriting this, I want hard evidence this
     slowness is at all relevant in typical applications.  (I don't
     dispute optimization may improve matters significantly, I'm
     mostly interested in having someone give real-world benchmark on
     the impact of libidn.) */

  for (i = 0; table[i].start || table[i].end; i++)
    if (ucs4 >= table[i].start &&
	ucs4 <= (table[i].end ? table[i].end : table[i].start))
      return i;

  return -1;
}

static ssize_t
stringprep_find_string_in_table (uint32_t * ucs4,
				 size_t ucs4len,
				 size_t * tablepos,
				 const Stringprep_table_element * table)
{
  size_t j;
  ssize_t pos;

  for (j = 0; j < ucs4len; j++)
    if ((pos = stringprep_find_character_in_table (ucs4[j], table)) != -1)
      {
	if (tablepos)
	  *tablepos = pos;
	return j;
      }

  return -1;
}

static int
stringprep_apply_table_to_string (uint32_t * ucs4,
				  size_t * ucs4len,
				  size_t maxucs4len,
				  const Stringprep_table_element * table)
{
  ssize_t pos;
  size_t i, maplen;

  while ((pos = stringprep_find_string_in_table (ucs4, *ucs4len,
						 &i, table)) != -1)
    {
      for (maplen = STRINGPREP_MAX_MAP_CHARS;
	   maplen > 0 && table[i].map[maplen - 1] == 0; maplen--)
	;

      if (*ucs4len - 1 + maplen >= maxucs4len)
	return STRINGPREP_TOO_SMALL_BUFFER;

      memmove (&ucs4[pos + maplen], &ucs4[pos + 1],
	       sizeof (uint32_t) * (*ucs4len - pos - 1));
      memcpy (&ucs4[pos], table[i].map, sizeof (uint32_t) * maplen);
      *ucs4len = *ucs4len - 1 + maplen;
    }

  return STRINGPREP_OK;
}

#define INVERTED(x) ((x) & ((~0UL) >> 1))
#define UNAPPLICAPLEFLAGS(flags, profileflags) \
  ((!INVERTED(profileflags) && !(profileflags & flags) && profileflags) || \
   ( INVERTED(profileflags) && (profileflags & flags)))

/**
 * stringprep_4i:
 * @ucs4: input/output array with string to prepare.
 * @len: on input, length of input array with Unicode code points,
 *          on exit, length of output array with Unicode code points.
 * @maxucs4len: maximum length of input/output array.
 * @flags: stringprep profile flags, or 0.
 * @profile: pointer to stringprep profile to use.
 *
 * Prepare the input UCS-4 string according to the stringprep profile,
 * and write back the result to the input string.
 *
 * The input is not required to be zero terminated (@ucs4[@len] = 0).
 * The output will not be zero terminated unless @ucs4[@len] = 0.
 * Instead, see stringprep_4zi() if your input is zero terminated or
 * if you want the output to be.
 *
 * Since the stringprep operation can expand the string, @maxucs4len
 * indicate how large the buffer holding the string is.  This function
 * will not read or write to code points outside that size.
 *
 * The @flags are one of Stringprep_profile_flags, or 0.
 *
 * The @profile contain the instructions to perform.  Your application
 * can define new profiles, possibly re-using the generic stringprep
 * tables that always will be part of the library, or use one of the
 * currently supported profiles.
 *
 * Return value: Returns %STRINGPREP_OK iff successful, or an error code.
 **/
int
stringprep_4i (uint32_t * ucs4, size_t * len, size_t maxucs4len,
	       Stringprep_profile_flags flags,
	       const Stringprep_profile * profile)
{
  size_t i, j;
  ssize_t k;
  size_t ucs4len = *len;
  int rc;

  for (i = 0; profile[i].operation; i++)
    {
      switch (profile[i].operation)
	{
	case STRINGPREP_NFKC:
	  {
	    uint32_t *q = 0;

	    if (UNAPPLICAPLEFLAGS (flags, profile[i].flags))
	      break;

	    if (flags & STRINGPREP_NO_NFKC && !profile[i].flags)
	      /* Profile requires NFKC, but callee asked for no NFKC. */
	      return STRINGPREP_FLAG_ERROR;

	    q = stringprep_ucs4_nfkc_normalize (ucs4, ucs4len);
	    if (!q)
	      return STRINGPREP_NFKC_FAILED;

	    for (ucs4len = 0; q[ucs4len]; ucs4len++)
	      ;

	    if (ucs4len >= maxucs4len)
	      {
		free (q);
		return STRINGPREP_TOO_SMALL_BUFFER;
	      }

	    memcpy (ucs4, q, ucs4len * sizeof (ucs4[0]));

	    free (q);
	  }
	  break;

	case STRINGPREP_PROHIBIT_TABLE:
	  k = stringprep_find_string_in_table (ucs4, ucs4len,
					       NULL, profile[i].table);
	  if (k != -1)
	    return STRINGPREP_CONTAINS_PROHIBITED;
	  break;

	case STRINGPREP_UNASSIGNED_TABLE:
	  if (UNAPPLICAPLEFLAGS (flags, profile[i].flags))
	    break;
	  if (flags & STRINGPREP_NO_UNASSIGNED)
	    {
	      k = stringprep_find_string_in_table
		(ucs4, ucs4len, NULL, profile[i].table);
	      if (k != -1)
		return STRINGPREP_CONTAINS_UNASSIGNED;
	    }
	  break;

	case STRINGPREP_MAP_TABLE:
	  if (UNAPPLICAPLEFLAGS (flags, profile[i].flags))
	    break;
	  rc = stringprep_apply_table_to_string
	    (ucs4, &ucs4len, maxucs4len, profile[i].table);
	  if (rc != STRINGPREP_OK)
	    return rc;
	  break;

	case STRINGPREP_BIDI_PROHIBIT_TABLE:
	case STRINGPREP_BIDI_RAL_TABLE:
	case STRINGPREP_BIDI_L_TABLE:
	  break;

	case STRINGPREP_BIDI:
	  {
	    int done_prohibited = 0;
	    int done_ral = 0;
	    int done_l = 0;
	    int contains_ral = -1;
	    int contains_l = -1;

	    for (j = 0; profile[j].operation; j++)
	      if (profile[j].operation == STRINGPREP_BIDI_PROHIBIT_TABLE)
		{
		  done_prohibited = 1;
		  k = stringprep_find_string_in_table (ucs4, ucs4len,
						       NULL,
						       profile[j].table);
		  if (k != -1)
		    return STRINGPREP_BIDI_CONTAINS_PROHIBITED;
		}
	      else if (profile[j].operation == STRINGPREP_BIDI_RAL_TABLE)
		{
		  done_ral = 1;
		  if (stringprep_find_string_in_table
		      (ucs4, ucs4len, NULL, profile[j].table) != -1)
		    contains_ral = j;
		}
	      else if (profile[j].operation == STRINGPREP_BIDI_L_TABLE)
		{
		  done_l = 1;
		  if (stringprep_find_string_in_table
		      (ucs4, ucs4len, NULL, profile[j].table) != -1)
		    contains_l = j;
		}

	    if (!done_prohibited || !done_ral || !done_l)
	      return STRINGPREP_PROFILE_ERROR;

	    if (contains_ral != -1 && contains_l != -1)
	      return STRINGPREP_BIDI_BOTH_L_AND_RAL;

	    if (contains_ral != -1)
	      {
		if (!(stringprep_find_character_in_table
		      (ucs4[0], profile[contains_ral].table) != -1 &&
		      stringprep_find_character_in_table
		      (ucs4[ucs4len - 1], profile[contains_ral].table) != -1))
		  return STRINGPREP_BIDI_LEADTRAIL_NOT_RAL;
	      }
	  }
	  break;

	default:
	  return STRINGPREP_PROFILE_ERROR;
	  break;
	}
    }

  *len = ucs4len;

  return STRINGPREP_OK;
}

static int
stringprep_4zi_1 (uint32_t * ucs4, size_t ucs4len, size_t maxucs4len,
		  Stringprep_profile_flags flags,
		  const Stringprep_profile * profile)
{
  int rc;

  rc = stringprep_4i (ucs4, &ucs4len, maxucs4len, flags, profile);
  if (rc != STRINGPREP_OK)
    return rc;

  if (ucs4len >= maxucs4len)
    return STRINGPREP_TOO_SMALL_BUFFER;

  ucs4[ucs4len] = 0;

  return STRINGPREP_OK;
}

/**
 * stringprep_4zi:
 * @ucs4: input/output array with zero terminated string to prepare.
 * @maxucs4len: maximum length of input/output array.
 * @flags: stringprep profile flags, or 0.
 * @profile: pointer to stringprep profile to use.
 *
 * Prepare the input zero terminated UCS-4 string according to the
 * stringprep profile, and write back the result to the input string.
 *
 * Since the stringprep operation can expand the string, @maxucs4len
 * indicate how large the buffer holding the string is.  This function
 * will not read or write to code points outside that size.
 *
 * The @flags are one of Stringprep_profile_flags, or 0.
 *
 * The @profile contain the instructions to perform.  Your application
 * can define new profiles, possibly re-using the generic stringprep
 * tables that always will be part of the library, or use one of the
 * currently supported profiles.
 *
 * Return value: Returns %STRINGPREP_OK iff successful, or an error code.
 **/
int
stringprep_4zi (uint32_t * ucs4, size_t maxucs4len,
		Stringprep_profile_flags flags,
		const Stringprep_profile * profile)
{
  size_t ucs4len;

  for (ucs4len = 0; ucs4len < maxucs4len && ucs4[ucs4len] != 0; ucs4len++)
    ;

  return stringprep_4zi_1 (ucs4, ucs4len, maxucs4len, flags, profile);
}

/**
 * stringprep:
 * @in: input/ouput array with string to prepare.
 * @maxlen: maximum length of input/output array.
 * @flags: stringprep profile flags, or 0.
 * @profile: pointer to stringprep profile to use.
 *
 * Prepare the input zero terminated UTF-8 string according to the
 * stringprep profile, and write back the result to the input string.
 *
 * Note that you must convert strings entered in the systems locale
 * into UTF-8 before using this function, see
 * stringprep_locale_to_utf8().
 *
 * Since the stringprep operation can expand the string, @maxlen
 * indicate how large the buffer holding the string is.  This function
 * will not read or write to characters outside that size.
 *
 * The @flags are one of Stringprep_profile_flags, or 0.
 *
 * The @profile contain the instructions to perform.  Your application
 * can define new profiles, possibly re-using the generic stringprep
 * tables that always will be part of the library, or use one of the
 * currently supported profiles.
 *
 * Return value: Returns %STRINGPREP_OK iff successful, or an error code.
 **/
int
stringprep (char *in,
	    size_t maxlen,
	    Stringprep_profile_flags flags,
	    const Stringprep_profile * profile)
{
  int rc;
  char *utf8 = NULL;
  uint32_t *ucs4 = NULL;
  size_t ucs4len, maxucs4len, adducs4len = 50;

  do
    {
      if (ucs4)
	free (ucs4);
      ucs4 = stringprep_utf8_to_ucs4 (in, -1, &ucs4len);
      maxucs4len = ucs4len + adducs4len;
      ucs4 = realloc (ucs4, maxucs4len * sizeof (uint32_t));
      if (!ucs4)
	return STRINGPREP_MALLOC_ERROR;

      rc = stringprep_4i (ucs4, &ucs4len, maxucs4len, flags, profile);
      adducs4len += 50;
    }
  while (rc == STRINGPREP_TOO_SMALL_BUFFER);
  if (rc != STRINGPREP_OK)
    {
      free (ucs4);
      return rc;
    }

  utf8 = stringprep_ucs4_to_utf8 (ucs4, ucs4len, 0, 0);
  free (ucs4);
  if (!utf8)
    return STRINGPREP_MALLOC_ERROR;

  if (strlen (utf8) >= maxlen)
    {
      free (utf8);
      return STRINGPREP_TOO_SMALL_BUFFER;
    }

  strcpy (in, utf8);		/* flawfinder: ignore */

  free (utf8);

  return STRINGPREP_OK;
}

/**
 * stringprep_profile:
 * @in: input array with UTF-8 string to prepare.
 * @out: output variable with pointer to newly allocate string.
 * @profile: name of stringprep profile to use.
 * @flags: stringprep profile flags, or 0.
 *
 * Prepare the input zero terminated UTF-8 string according to the
 * stringprep profile, and return the result in a newly allocated
 * variable.
 *
 * Note that you must convert strings entered in the systems locale
 * into UTF-8 before using this function, see
 * stringprep_locale_to_utf8().
 *
 * The output @out variable must be deallocated by the caller.
 *
 * The @flags are one of Stringprep_profile_flags, or 0.
 *
 * The @profile specifies the name of the stringprep profile to use.
 * It must be one of the internally supported stringprep profiles.
 *
 * Return value: Returns %STRINGPREP_OK iff successful, or an error code.
 **/
int
stringprep_profile (const char *in,
		    char **out,
		    const char *profile, Stringprep_profile_flags flags)
{
  const Stringprep_profiles *p;
  char *str = NULL;
  size_t len = strlen (in) + 1;
  int rc;

  for (p = &stringprep_profiles[0]; p->name; p++)
    if (strcmp (p->name, profile) == 0)
      break;

  if (!p || !p->name || !p->tables)
    return STRINGPREP_UNKNOWN_PROFILE;

  do
    {
      if (str)
	free (str);
      str = (char *) malloc (len);
      if (str == NULL)
	return STRINGPREP_MALLOC_ERROR;

      strcpy (str, in);

      rc = stringprep (str, len, flags, p->tables);
      len += 50;
    }
  while (rc == STRINGPREP_TOO_SMALL_BUFFER);

  if (rc == STRINGPREP_OK)
    *out = str;
  else
    free (str);

  return rc;
}

/*! \mainpage GNU Internationalized Domain Name Library
 *
 * \section intro Introduction
 *
 * GNU Libidn is an implementation of the Stringprep, Punycode and IDNA
 * specifications defined by the IETF Internationalized Domain Names
 * (IDN) working group, used for internationalized domain names.  The
 * package is available under the GNU Lesser General Public License.
 *
 * The library contains a generic Stringprep implementation that does
 * Unicode 3.2 NFKC normalization, mapping and prohibitation of
 * characters, and bidirectional character handling.  Profiles for
 * Nameprep, iSCSI, SASL and XMPP are included.  Punycode and ASCII
 * Compatible Encoding (ACE) via IDNA are supported.  A mechanism to
 * define Top-Level Domain (TLD) specific validation tables, and to
 * compare strings against those tables, is included.  Default tables
 * for some TLDs are also included.
 *
 * The Stringprep API consists of two main functions, one for
 * converting data from the system's native representation into UTF-8,
 * and one function to perform the Stringprep processing.  Adding a
 * new Stringprep profile for your application within the API is
 * straightforward.  The Punycode API consists of one encoding
 * function and one decoding function.  The IDNA API consists of the
 * ToASCII and ToUnicode functions, as well as an high-level interface
 * for converting entire domain names to and from the ACE encoded
 * form.  The TLD API consists of one set of functions to extract the
 * TLD name from a domain string, one set of functions to locate the
 * proper TLD table to use based on the TLD name, and core functions
 * to validate a string against a TLD table, and some utility wrappers
 * to perform all the steps in one call.
 *
 * The library is used by, e.g., GNU SASL and Shishi to process user
 * names and passwords.  Libidn can be built into GNU Libc to enable a
 * new system-wide getaddrinfo() flag for IDN processing.
 *
 * Libidn is developed for the GNU/Linux system, but runs on over 20 Unix
 * platforms (including Solaris, IRIX, AIX, and Tru64) and Windows.
 * Libidn is written in C and (parts of) the API is accessible from C,
 * C++, Emacs Lisp, Python and Java.
 *
 * The project web page:\n
 * http://www.gnu.org/software/libidn/
 *
 * The software archive:\n
 * ftp://alpha.gnu.org/pub/gnu/libidn/
 *
 * For more information see:\n
 * http://www.ietf.org/html.charters/idn-charter.html\n
 * http://www.ietf.org/rfc/rfc3454.txt (stringprep specification)\n
 * http://www.ietf.org/rfc/rfc3490.txt (idna specification)\n
 * http://www.ietf.org/rfc/rfc3491.txt (nameprep specification)\n
 * http://www.ietf.org/rfc/rfc3492.txt (punycode specification)\n
 * http://www.ietf.org/internet-drafts/draft-ietf-ips-iscsi-string-prep-04.txt\n
 * http://www.ietf.org/internet-drafts/draft-ietf-krb-wg-utf8-profile-01.txt\n
 * http://www.ietf.org/internet-drafts/draft-ietf-sasl-anon-00.txt\n
 * http://www.ietf.org/internet-drafts/draft-ietf-sasl-saslprep-00.txt\n
 * http://www.ietf.org/internet-drafts/draft-ietf-xmpp-nodeprep-01.txt\n
 * http://www.ietf.org/internet-drafts/draft-ietf-xmpp-resourceprep-01.txt\n
 *
 * Further information and paid contract development:\n
 * Simon Josefsson <simon@josefsson.org>
 *
 * \section examples Examples
 *
 * \include example.c
 * \include example3.c
 * \include example4.c
 * \include example5.c
 */

/**
 * STRINGPREP_VERSION
 *
 * String defined via CPP denoting the header file version number.
 * Used together with stringprep_check_version() to verify header file
 * and run-time library consistency.
 */

/**
 * STRINGPREP_MAX_MAP_CHARS
 *
 * Maximum number of code points that can replace a single code point,
 * during stringprep mapping.
 */

/**
 * Stringprep_rc:
 * @STRINGPREP_OK: 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.
 * @STRINGPREP_CONTAINS_UNASSIGNED: String contain unassigned Unicode
 *   code points, which is forbidden by the profile.
 * @STRINGPREP_CONTAINS_PROHIBITED: String contain code points
 *   prohibited by the profile.
 * @STRINGPREP_BIDI_BOTH_L_AND_RAL: String contain code points with
 *   conflicting bidirection category.
 * @STRINGPREP_BIDI_LEADTRAIL_NOT_RAL: Leading and trailing character
 *   in string not of proper bidirectional category.
 * @STRINGPREP_BIDI_CONTAINS_PROHIBITED: Contains prohibited code
 *   points detected by bidirectional code.
 * @STRINGPREP_TOO_SMALL_BUFFER: Buffer handed to function was too
 *   small.  This usually indicate a problem in the calling
 *   application.
 * @STRINGPREP_PROFILE_ERROR: The stringprep profile was inconsistent.
 *   This usually indicate an internal error in the library.
 * @STRINGPREP_FLAG_ERROR: The supplied flag conflicted with profile.
 *   This usually indicate a problem in the calling application.
 * @STRINGPREP_UNKNOWN_PROFILE: The supplied profile name was not
 *   known to the library.
 * @STRINGPREP_NFKC_FAILED: The Unicode NFKC operation failed.  This
 *   usually indicate an internal error in the library.
 * @STRINGPREP_MALLOC_ERROR: The malloc() was out of memory.  This is
 *   usually a fatal error.
 *
 * Enumerated return codes of stringprep(), stringprep_profile()
 * functions (and macros using those functions).  The value 0 is
 * guaranteed to always correspond to success.
 */

/**
 * Stringprep_profile_flags:
 * @STRINGPREP_NO_NFKC: Disable the NFKC normalization, as well as
 *   selecting the non-NFKC case folding tables.  Usually the profile
 *   specifies BIDI and NFKC settings, and applications should not
 *   override it unless in special situations.
 * @STRINGPREP_NO_BIDI: Disable the BIDI step.  Usually the profile
 *   specifies BIDI and NFKC settings, and applications should not
 *   override it unless in special situations.
 * @STRINGPREP_NO_UNASSIGNED: Make the library return with an error if
 *   string contains unassigned characters according to profile.
 *
 * Stringprep profile flags.
 */

/**
 * Stringprep_profile_steps:
 *
 * Various steps in the stringprep algorithm.  You really want to
 * study the source code to understand this one.  Only useful if you
 * want to add another profile.
 */

/**
 * stringprep_nameprep:
 * @in: input/ouput array with string to prepare.
 * @maxlen: maximum length of input/output array.
 *
 * Prepare the input UTF-8 string according to the nameprep profile.
 * The AllowUnassigned flag is true, use
 * stringprep_nameprep_no_unassigned() if you want a false
 * AllowUnassigned.  Returns 0 iff successful, or an error code.
 **/

/**
 * stringprep_nameprep_no_unassigned:
 * @in: input/ouput array with string to prepare.
 * @maxlen: maximum length of input/output array.
 *
 * Prepare the input UTF-8 string according to the nameprep profile.
 * The AllowUnassigned flag is false, use stringprep_nameprep() for
 * true AllowUnassigned.  Returns 0 iff successful, or an error code.
 **/

/**
 * stringprep_iscsi:
 * @in: input/ouput array with string to prepare.
 * @maxlen: maximum length of input/output array.
 *
 * Prepare the input UTF-8 string according to the draft iSCSI
 * stringprep profile.  Returns 0 iff successful, or an error code.
 **/

/**
 * stringprep_plain:
 * @in: input/ouput array with string to prepare.
 * @maxlen: maximum length of input/output array.
 *
 * Prepare the input UTF-8 string according to the draft SASL
 * ANONYMOUS profile.  Returns 0 iff successful, or an error code.
 **/

/**
 * stringprep_xmpp_nodeprep:
 * @in: input/ouput array with string to prepare.
 * @maxlen: maximum length of input/output array.
 *
 * Prepare the input UTF-8 string according to the draft XMPP node
 * identifier profile.  Returns 0 iff successful, or an error code.
 **/

/**
 * stringprep_xmpp_resourceprep:
 * @in: input/ouput array with string to prepare.
 * @maxlen: maximum length of input/output array.
 *
 * Prepare the input UTF-8 string according to the draft XMPP resource
 * identifier profile.  Returns 0 iff successful, or an error code.
 **/