Coverage Report

Created: 2025-01-28 06:58

/src/libidn2/lib/punycode.c
Line
Count
Source (jump to first uncovered line)
1
/* punycode.c - punycode encoding/decoding
2
   Copyright (C) 2011-2024 Simon Josefsson
3
4
   Libidn2 is free software: you can redistribute it and/or modify it
5
   under the terms of either:
6
7
     * the GNU Lesser General Public License as published by the Free
8
       Software Foundation; either version 3 of the License, or (at
9
       your option) any later version.
10
11
   or
12
13
     * the GNU General Public License as published by the Free
14
       Software Foundation; either version 2 of the License, or (at
15
       your option) any later version.
16
17
   or both in parallel, as here.
18
19
   This program is distributed in the hope that it will be useful,
20
   but WITHOUT ANY WARRANTY; without even the implied warranty of
21
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
22
   GNU General Public License for more details.
23
24
   You should have received copies of the GNU General Public License and
25
   the GNU Lesser General Public License along with this program.  If
26
   not, see <http://www.gnu.org/licenses/>.
27
*/
28
29
/*
30
  Code copied from http://www.nicemice.net/idn/punycode-spec.gz on
31
  2011-01-04 with SHA-1 a966a8017f6be579d74a50a226accc7607c40133
32
  labeled punycode-spec 1.0.3 (2006-Mar-23-Thu).  It is modified for
33
  Libidn2 by Simon Josefsson and others.  Original code license:
34
35
  punycode-spec 1.0.3 (2006-Mar-23-Thu)
36
  http://www.nicemice.net/idn/
37
  Adam M. Costello
38
  http://www.nicemice.net/amc/
39
40
  B. Disclaimer and license
41
42
    Regarding this entire document or any portion of it (including
43
    the pseudocode and C code), the author makes no guarantees and
44
    is not responsible for any damage resulting from its use.  The
45
    author grants irrevocable permission to anyone to use, modify,
46
    and distribute it in any way that does not diminish the rights
47
    of anyone else to use, modify, and distribute it, provided that
48
    redistributed derivative works do not contain misleading author or
49
    version information.  Derivative works need not be licensed under
50
    similar terms.
51
52
  C. Punycode sample implementation
53
54
  punycode-sample.c 2.0.0 (2004-Mar-21-Sun)
55
  http://www.nicemice.net/idn/
56
  Adam M. Costello
57
  http://www.nicemice.net/amc/
58
59
  This is ANSI C code (C89) implementing Punycode 1.0.x.
60
*/
61
62
#include <config.h>
63
64
#include "idn2.h"   /* IDN2_OK, ... */
65
66
#include <string.h>
67
68
/*** Bootstring parameters for Punycode ***/
69
70
enum
71
{ base = 36, tmin = 1, tmax = 26, skew = 38, damp = 700,
72
  initial_bias = 72, initial_n = 0x80, delimiter = 0x2D
73
};
74
75
/* basic(cp) tests whether cp is a basic code point: */
76
344k
#define encode_basic(cp) ((uint32_t)(cp) < 0x80)
77
78
/* encode_digit(d,flag) returns the basic code point whose value      */
79
/* (when used for representing integers) is d, which needs to be in   */
80
/* the range 0 to base-1.  The lowercase form is used unless flag is  */
81
/* nonzero, in which case the uppercase form is used.  The behavior   */
82
/* is undefined if flag is nonzero and digit d has no uppercase form. */
83
84
static char
85
encode_digit (uint32_t d, int flag)
86
456k
{
87
456k
  return d + 22 + 75 * (d < 26) - ((flag != 0) << 5);
88
  /*  0..25 map to ASCII a..z or A..Z */
89
  /* 26..35 map to ASCII 0..9         */
90
456k
}
91
92
/* basic(cp) tests whether cp is a basic code point: */
93
#define decode_basic(cp)             \
94
741k
  ((cp >= 'a' && cp <= 'z') || (cp >= '0' && cp <='9')    \
95
741k
   || (cp >= 'A' && cp <='Z') || cp == '-' || cp == '_')
96
97
/* decode_digit(cp) returns the numeric value of a basic code */
98
/* point (for use in representing integers) in the range 0 to */
99
/* base-1, or base if cp does not represent a value.          */
100
101
static unsigned
102
decode_digit (int cp)
103
610k
{
104
610k
  if (cp >= 'a' && cp <= 'z')
105
476k
    return cp - 'a';
106
133k
  if (cp >= '0' && cp <= '9')
107
133k
    return cp - '0' + 26;
108
0
  if (cp >= 'A' && cp <= 'Z')
109
0
    return cp - 'A';
110
111
0
  return 0;
112
0
}
113
114
/*** Bias adaptation function ***/
115
116
static uint32_t
117
adapt (uint32_t delta, uint32_t numpoints, int firsttime)
118
  _GL_ATTRIBUTE_CONST;
119
120
     static uint32_t adapt (uint32_t delta, uint32_t numpoints, int firsttime)
121
519k
{
122
519k
  uint32_t k;
123
124
519k
  delta = firsttime ? delta / damp : delta >> 1;
125
  /* delta >> 1 is a faster way of doing delta / 2 */
126
519k
  delta += delta / numpoints;
127
128
641k
  for (k = 0; delta > ((base - tmin) * tmax) / 2; k += base)
129
122k
    {
130
122k
      delta /= base - tmin;
131
122k
    }
132
133
519k
  return k + (base - tmin + 1) * delta / (delta + skew);
134
519k
}
135
136
/**
137
 * idn2_punycode_encode:
138
 * @input: array of input Unicode (UCS-4) code points
139
 * @input_length: number of code points in the @input array.
140
 * @output: output character array with ASCII code points.
141
 * @output_length: size of @output array
142
 *
143
 * Converts a sequence of code points to Punycode.
144
 *
145
 * Warning: Be aware that is rare for applications to need to perform
146
 *   Punycode operations, and you should consider idn2_to_ascii_8z(),
147
 *   idn2_to_ascii_lz(), idn2_to_ascii_4z() etc.
148
 *
149
 * Returns: On successful encoding %IDN2_OK is returned, or an error
150
 *   codes like %IDN2_PUNYCODE_BAD_INPUT, %IDN2_PUNYCODE_BIG_OUTPUT,
151
 *   or %IDN2_PUNYCODE_OVERFLOW.
152
 *
153
 * Since: 2.3.5
154
 **/
155
int
156
idn2_punycode_encode (const uint32_t *input,
157
          size_t input_length,
158
          char *output, size_t *output_length)
159
50.0k
{
160
50.0k
  uint32_t our_input_length, n, delta, h, b, bias, j, m, q, k, t;
161
50.0k
  size_t out, max_out;
162
163
  /* The Punycode spec assumes that the input length is the same type */
164
  /* of integer as a code point, so we need to convert the size_t to  */
165
  /* a uint32_t, which could overflow.                           */
166
167
50.0k
  if (input_length > UINT32_MAX)
168
0
    return IDN2_PUNYCODE_OVERFLOW;
169
50.0k
  our_input_length = (uint32_t) input_length;
170
171
  /* Initialize the state: */
172
173
50.0k
  n = initial_n;
174
50.0k
  delta = 0;
175
50.0k
  out = 0;
176
50.0k
  max_out = *output_length;
177
50.0k
  bias = initial_bias;
178
179
  /* Handle the basic code points: */
180
181
393k
  for (j = 0; j < our_input_length; ++j)
182
344k
    {
183
344k
      if (encode_basic (input[j]))
184
101k
  {
185
101k
    if (max_out - out < 2)
186
632
      return IDN2_PUNYCODE_BIG_OUTPUT;
187
100k
    output[out++] = (char) input[j];
188
100k
  }
189
242k
      else if (input[j] > 0x10FFFF
190
242k
         || (input[j] >= 0xD800 && input[j] <= 0xDBFF))
191
0
  return IDN2_PUNYCODE_BAD_INPUT;
192
344k
    }
193
194
49.4k
  h = b = (uint32_t) out;
195
  /* cannot overflow because out <= our_input_length <= UINT32_MAX */
196
197
  /* h is the number of code points that have been handled, b is the  */
198
  /* number of basic code points, and out is the number of ASCII code */
199
  /* points that have been output.                                    */
200
201
49.4k
  if (b > 0)
202
17.2k
    output[out++] = delimiter;
203
204
  /* Main encoding loop: */
205
206
177k
  while (h < our_input_length)
207
129k
    {
208
      /* All non-basic code points < n have been     */
209
      /* handled already.  Find the next larger one: */
210
211
1.62M
      for (m = UINT32_MAX, j = 0; j < our_input_length; ++j)
212
1.49M
  {
213
    /* if (basic(input[j])) continue; */
214
    /* (not needed for Punycode) */
215
1.49M
    if (input[j] >= n && input[j] < m)
216
294k
      m = input[j];
217
1.49M
  }
218
219
      /* Increase delta enough to advance the decoder's    */
220
      /* <n,i> state to <m,0>, but guard against overflow: */
221
222
129k
      if (m - n > (UINT32_MAX - delta) / (h + 1))
223
0
  return IDN2_PUNYCODE_OVERFLOW;
224
129k
      delta += (m - n) * (h + 1);
225
129k
      n = m;
226
227
1.58M
      for (j = 0; j < our_input_length; ++j)
228
1.45M
  {
229
    /* Punycode does not need to check whether input[j] is basic: */
230
1.45M
    if (input[j] < n /* || basic(input[j]) */ )
231
638k
      {
232
638k
        if (++delta == 0)
233
0
    return IDN2_PUNYCODE_OVERFLOW;
234
638k
      }
235
236
1.45M
    if (input[j] == n)
237
206k
      {
238
        /* Represent delta as a generalized variable-length integer: */
239
240
251k
        for (q = delta, k = base;; k += base)
241
458k
    {
242
458k
      if (out >= max_out)
243
1.96k
        return IDN2_PUNYCODE_BIG_OUTPUT;
244
456k
      t = k <= bias /* + tmin */ ? tmin :  /* +tmin not needed */
245
456k
        k >= bias + tmax ? tmax : k - bias;
246
456k
      if (q < t)
247
205k
        break;
248
251k
      output[out++] = encode_digit (t + (q - t) % (base - t), 0);
249
251k
      q = (q - t) / (base - t);
250
251k
    }
251
252
205k
        output[out++] = encode_digit (q, 0);
253
205k
        bias = adapt (delta, h + 1, h == b);
254
205k
        delta = 0;
255
205k
        ++h;
256
205k
      }
257
1.45M
  }
258
259
127k
      ++delta, ++n;
260
127k
    }
261
262
47.4k
  *output_length = out;
263
47.4k
  return IDN2_OK;
264
49.4k
}
265
266
/**
267
 * idn2_punycode_decode:
268
 * @input: array of ASCII characters (0..7F)
269
 * @input_length: Number of ASCII characters in the @input array.
270
 * @output: output character array with ASCII code points.
271
 * @output_length: on input, guarantee that @output has room
272
 *   for this many code points; on output, *@output_length
273
 *   holds number of code points in @output.
274
 *
275
 * Converts Punycode to a sequence of code points.
276
 *
277
 * The decoder will never need to output more code points than the
278
 * number of ASCII code points in the input, because of the way the
279
 * encoding is defined.
280
 *
281
 * The number of code points output cannot exceed the maximum possible
282
 * value of a uint32_t, even if the supplied @output_length is greater
283
 * than that.
284
 *
285
 * Warning: Be aware that is rare for applications to need to perform
286
 *   Punycode operations, and you should consider
287
 *   idn2_to_unicode_8z8z(), idn2_to_unicode_lzlz() etc.
288
 *
289
 * Returns: On successful encoding %IDN2_OK is returned, or an error
290
 *   codes like %IDN2_PUNYCODE_BAD_INPUT, %IDN2_PUNYCODE_BIG_OUTPUT,
291
 *   or %IDN2_PUNYCODE_OVERFLOW.
292
 *
293
 * Since: 2.3.5
294
 **/
295
int
296
idn2_punycode_decode (const char *input,
297
          size_t input_length,
298
          uint32_t *output, size_t *output_length)
299
78.6k
{
300
78.6k
  uint32_t n, out = 0, i, max_out, bias, oldi, w, k, digit, t;
301
78.6k
  size_t b = 0, j, in;
302
303
78.6k
  if (!input_length)
304
814
    return IDN2_PUNYCODE_BAD_INPUT;
305
306
  /* Check that all chars are basic */
307
816k
  for (j = 0; j < input_length; ++j)
308
741k
    {
309
741k
      if (!decode_basic (input[j]))
310
3.12k
  return IDN2_PUNYCODE_BAD_INPUT;
311
738k
      if (input[j] == delimiter)
312
32.7k
  b = j;
313
738k
    }
314
315
74.6k
  max_out =
316
74.6k
    *output_length > UINT32_MAX ? UINT32_MAX : (uint32_t) * output_length;
317
318
74.6k
  if (input[b] == delimiter)
319
24.9k
    {
320
      /* do not accept leading or trailing delimiter
321
       *   - leading delim must be omitted if there is no ASCII char in u-label
322
       *   - trailing delim means there where no non-ASCII chars in u-label
323
       */
324
24.9k
      if (!b || b == input_length - 1)
325
860
  return IDN2_PUNYCODE_BAD_INPUT;
326
327
24.0k
      if (b >= max_out)
328
466
  return IDN2_PUNYCODE_BIG_OUTPUT;
329
330
      /* Check that all chars before last delimiter are basic chars */
331
      /* and copy the first b code points to the output. */
332
90.7k
      for (j = 0; j < b; j++)
333
67.1k
  output[out++] = input[j];
334
335
23.6k
      b += 1;     /* advance to non-basic char encoding */
336
23.6k
    }
337
338
  /* Initialize the state: */
339
73.3k
  n = initial_n;
340
73.3k
  i = 0;
341
73.3k
  bias = initial_bias;
342
343
  /* Main decoding loop:  Start just after the last delimiter if any  */
344
  /* basic code points were copied; start at the beginning otherwise. */
345
385k
  for (in = b; in < input_length; ++out)
346
315k
    {
347
348
      /* in is the index of the next ASCII code point to be consumed, */
349
      /* and out is the number of code points in the output array.    */
350
351
      /* Decode a generalized variable-length integer into delta,  */
352
      /* which gets added to i.  The overflow checking is easier   */
353
      /* if we increase i as we go, then subtract off its starting */
354
      /* value at the end to obtain delta.                         */
355
315k
      for (oldi = i, w = 1, k = base;; k += base)
356
610k
  {
357
610k
    if (in >= input_length)
358
469
      return IDN2_PUNYCODE_BAD_INPUT;
359
610k
    digit = decode_digit (input[in++]);
360
610k
    if (digit >= base)
361
0
      return IDN2_PUNYCODE_BAD_INPUT;
362
610k
    if (digit > (UINT32_MAX - i) / w)
363
977
      return IDN2_PUNYCODE_OVERFLOW;
364
609k
    i += digit * w;
365
609k
    t = k <= bias /* + tmin */ ? tmin :  /* +tmin not needed */
366
609k
      k >= bias + tmax ? tmax : k - bias;
367
609k
    if (digit < t)
368
314k
      break;
369
294k
    if (w > UINT32_MAX / (base - t))
370
0
      return IDN2_PUNYCODE_OVERFLOW;
371
294k
    w *= (base - t);
372
294k
  }
373
374
314k
      bias = adapt (i - oldi, out + 1, oldi == 0);
375
376
      /* i was supposed to wrap around from out+1 to 0,   */
377
      /* incrementing n each time, so we'll fix that now: */
378
314k
      if (i / (out + 1) > UINT32_MAX - n)
379
226
  return IDN2_PUNYCODE_OVERFLOW;
380
313k
      n += i / (out + 1);
381
313k
      if (n > 0x10FFFF || (n >= 0xD800 && n <= 0xDBFF))
382
1.12k
  return IDN2_PUNYCODE_BAD_INPUT;
383
312k
      i %= (out + 1);
384
385
      /* Insert n at position i of the output: */
386
387
      /* not needed for Punycode: */
388
      /* if (basic(n)) return IDN2_PUNYCODE_BAD_INPUT; */
389
312k
      if (out >= max_out)
390
437
  return IDN2_PUNYCODE_BIG_OUTPUT;
391
392
312k
      memmove (output + i + 1, output + i, (out - i) * sizeof *output);
393
312k
      output[i++] = n;
394
312k
    }
395
396
70.1k
  *output_length = (size_t) out;
397
  /* cannot overflow because out <= old value of *output_length */
398
70.1k
  return IDN2_OK;
399
73.3k
}
400
401
/* We are stuck exporting these old internal interfaces because old
402
   versions of GNUTLS used them, and maybe other software. */
403
404
extern int _IDN2_API _idn2_punycode_decode (size_t input_length,
405
              const char input[],
406
              size_t *output_length,
407
              uint32_t output[]);
408
extern int _IDN2_API _idn2_punycode_encode (size_t input_length,
409
              const uint32_t input[],
410
              size_t *output_length,
411
              char output[]);
412
413
int
414
_idn2_punycode_decode (size_t input_length,
415
           const char input[],
416
           size_t *output_length, uint32_t output[])
417
0
{
418
0
  return idn2_punycode_decode (input, input_length, output, output_length);
419
420
0
}
421
422
int
423
_idn2_punycode_encode (size_t input_length,
424
           const uint32_t input[],
425
           size_t *output_length, char output[])
426
0
{
427
0
  return idn2_punycode_encode (input, input_length, output, output_length);
428
0
}