1 /*************************************************
2 *      Perl-Compatible Regular Expressions       *
3 *************************************************/
4 
5 /* PCRE is a library of functions to support regular expressions whose syntax
6 and semantics are as close as possible to those of the Perl 5 language.
7 
8                        Written by Philip Hazel
9      Original API code Copyright (c) 1997-2012 University of Cambridge
10           New API code Copyright (c) 2016-2020 University of Cambridge
11 
12 -----------------------------------------------------------------------------
13 Redistribution and use in source and binary forms, with or without
14 modification, are permitted provided that the following conditions are met:
15 
16     * Redistributions of source code must retain the above copyright notice,
17       this list of conditions and the following disclaimer.
18 
19     * Redistributions in binary form must reproduce the above copyright
20       notice, this list of conditions and the following disclaimer in the
21       documentation and/or other materials provided with the distribution.
22 
23     * Neither the name of the University of Cambridge nor the names of its
24       contributors may be used to endorse or promote products derived from
25       this software without specific prior written permission.
26 
27 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
28 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
31 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
32 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
33 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
34 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
35 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
36 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
37 POSSIBILITY OF SUCH DAMAGE.
38 -----------------------------------------------------------------------------
39 */
40 
41 
42 /* This module contains an internal function for validating UTF character
43 strings. This file is also #included by the pcre2test program, which uses
44 macros to change names from _pcre2_xxx to xxxx, thereby avoiding name clashes
45 with the library. In this case, PCRE2_PCRE2TEST is defined. */
46 
47 #ifndef PCRE2_PCRE2TEST           /* We're compiling the library */
48 #ifdef HAVE_CONFIG_H
49 #include "config.h"
50 #endif
51 #include "pcre2_internal.h"
52 #endif /* PCRE2_PCRE2TEST */
53 
54 
55 #ifndef SUPPORT_UNICODE
56 /*************************************************
57 *  Dummy function when Unicode is not supported  *
58 *************************************************/
59 
60 /* This function should never be called when Unicode is not supported. */
61 
62 int
PRIV(valid_utf)63 PRIV(valid_utf)(PCRE2_SPTR string, PCRE2_SIZE length, PCRE2_SIZE *erroroffset)
64 {
65 (void)string;
66 (void)length;
67 (void)erroroffset;
68 return 0;
69 }
70 #else  /* UTF is supported */
71 
72 
73 
74 /*************************************************
75 *           Validate a UTF string                *
76 *************************************************/
77 
78 /* This function is called (optionally) at the start of compile or match, to
79 check that a supposed UTF string is actually valid. The early check means
80 that subsequent code can assume it is dealing with a valid string. The check
81 can be turned off for maximum performance, but the consequences of supplying an
82 invalid string are then undefined.
83 
84 Arguments:
85   string       points to the string
86   length       length of string
87   errp         pointer to an error position offset variable
88 
89 Returns:       == 0    if the string is a valid UTF string
90                != 0    otherwise, setting the offset of the bad character
91 */
92 
93 int
PRIV(valid_utf)94 PRIV(valid_utf)(PCRE2_SPTR string, PCRE2_SIZE length, PCRE2_SIZE *erroroffset)
95 {
96 PCRE2_SPTR p;
97 uint32_t c;
98 
99 /* ----------------- Check a UTF-8 string ----------------- */
100 
101 #if PCRE2_CODE_UNIT_WIDTH == 8
102 
103 /* Originally, this function checked according to RFC 2279, allowing for values
104 in the range 0 to 0x7fffffff, up to 6 bytes long, but ensuring that they were
105 in the canonical format. Once somebody had pointed out RFC 3629 to me (it
106 obsoletes 2279), additional restrictions were applied. The values are now
107 limited to be between 0 and 0x0010ffff, no more than 4 bytes long, and the
108 subrange 0xd000 to 0xdfff is excluded. However, the format of 5-byte and 6-byte
109 characters is still checked. Error returns are as follows:
110 
111 PCRE2_ERROR_UTF8_ERR1   Missing 1 byte at the end of the string
112 PCRE2_ERROR_UTF8_ERR2   Missing 2 bytes at the end of the string
113 PCRE2_ERROR_UTF8_ERR3   Missing 3 bytes at the end of the string
114 PCRE2_ERROR_UTF8_ERR4   Missing 4 bytes at the end of the string
115 PCRE2_ERROR_UTF8_ERR5   Missing 5 bytes at the end of the string
116 PCRE2_ERROR_UTF8_ERR6   2nd-byte's two top bits are not 0x80
117 PCRE2_ERROR_UTF8_ERR7   3rd-byte's two top bits are not 0x80
118 PCRE2_ERROR_UTF8_ERR8   4th-byte's two top bits are not 0x80
119 PCRE2_ERROR_UTF8_ERR9   5th-byte's two top bits are not 0x80
120 PCRE2_ERROR_UTF8_ERR10  6th-byte's two top bits are not 0x80
121 PCRE2_ERROR_UTF8_ERR11  5-byte character is not permitted by RFC 3629
122 PCRE2_ERROR_UTF8_ERR12  6-byte character is not permitted by RFC 3629
123 PCRE2_ERROR_UTF8_ERR13  4-byte character with value > 0x10ffff is not permitted
124 PCRE2_ERROR_UTF8_ERR14  3-byte character with value 0xd800-0xdfff is not permitted
125 PCRE2_ERROR_UTF8_ERR15  Overlong 2-byte sequence
126 PCRE2_ERROR_UTF8_ERR16  Overlong 3-byte sequence
127 PCRE2_ERROR_UTF8_ERR17  Overlong 4-byte sequence
128 PCRE2_ERROR_UTF8_ERR18  Overlong 5-byte sequence (won't ever occur)
129 PCRE2_ERROR_UTF8_ERR19  Overlong 6-byte sequence (won't ever occur)
130 PCRE2_ERROR_UTF8_ERR20  Isolated 0x80 byte (not within UTF-8 character)
131 PCRE2_ERROR_UTF8_ERR21  Byte with the illegal value 0xfe or 0xff
132 */
133 
134 for (p = string; length > 0; p++)
135   {
136   uint32_t ab, d;
137 
138   c = *p;
139   length--;
140 
141   if (c < 128) continue;                /* ASCII character */
142 
143   if (c < 0xc0)                         /* Isolated 10xx xxxx byte */
144     {
145     *erroroffset = (PCRE2_SIZE)(p - string);
146     return PCRE2_ERROR_UTF8_ERR20;
147     }
148 
149   if (c >= 0xfe)                        /* Invalid 0xfe or 0xff bytes */
150     {
151     *erroroffset = (PCRE2_SIZE)(p - string);
152     return PCRE2_ERROR_UTF8_ERR21;
153     }
154 
155   ab = PRIV(utf8_table4)[c & 0x3f];     /* Number of additional bytes (1-5) */
156   if (length < ab)                      /* Missing bytes */
157     {
158     *erroroffset = (PCRE2_SIZE)(p - string);
159     switch(ab - length)
160       {
161       case 1: return PCRE2_ERROR_UTF8_ERR1;
162       case 2: return PCRE2_ERROR_UTF8_ERR2;
163       case 3: return PCRE2_ERROR_UTF8_ERR3;
164       case 4: return PCRE2_ERROR_UTF8_ERR4;
165       case 5: return PCRE2_ERROR_UTF8_ERR5;
166       }
167     }
168   length -= ab;                         /* Length remaining */
169 
170   /* Check top bits in the second byte */
171 
172   if (((d = *(++p)) & 0xc0) != 0x80)
173     {
174     *erroroffset = (int)(p - string) - 1;
175     return PCRE2_ERROR_UTF8_ERR6;
176     }
177 
178   /* For each length, check that the remaining bytes start with the 0x80 bit
179   set and not the 0x40 bit. Then check for an overlong sequence, and for the
180   excluded range 0xd800 to 0xdfff. */
181 
182   switch (ab)
183     {
184     /* 2-byte character. No further bytes to check for 0x80. Check first byte
185     for for xx00 000x (overlong sequence). */
186 
187     case 1: if ((c & 0x3e) == 0)
188       {
189       *erroroffset = (int)(p - string) - 1;
190       return PCRE2_ERROR_UTF8_ERR15;
191       }
192     break;
193 
194     /* 3-byte character. Check third byte for 0x80. Then check first 2 bytes
195       for 1110 0000, xx0x xxxx (overlong sequence) or
196           1110 1101, 1010 xxxx (0xd800 - 0xdfff) */
197 
198     case 2:
199     if ((*(++p) & 0xc0) != 0x80)     /* Third byte */
200       {
201       *erroroffset = (int)(p - string) - 2;
202       return PCRE2_ERROR_UTF8_ERR7;
203       }
204     if (c == 0xe0 && (d & 0x20) == 0)
205       {
206       *erroroffset = (int)(p - string) - 2;
207       return PCRE2_ERROR_UTF8_ERR16;
208       }
209     if (c == 0xed && d >= 0xa0)
210       {
211       *erroroffset = (int)(p - string) - 2;
212       return PCRE2_ERROR_UTF8_ERR14;
213       }
214     break;
215 
216     /* 4-byte character. Check 3rd and 4th bytes for 0x80. Then check first 2
217        bytes for for 1111 0000, xx00 xxxx (overlong sequence), then check for a
218        character greater than 0x0010ffff (f4 8f bf bf) */
219 
220     case 3:
221     if ((*(++p) & 0xc0) != 0x80)     /* Third byte */
222       {
223       *erroroffset = (int)(p - string) - 2;
224       return PCRE2_ERROR_UTF8_ERR7;
225       }
226     if ((*(++p) & 0xc0) != 0x80)     /* Fourth byte */
227       {
228       *erroroffset = (int)(p - string) - 3;
229       return PCRE2_ERROR_UTF8_ERR8;
230       }
231     if (c == 0xf0 && (d & 0x30) == 0)
232       {
233       *erroroffset = (int)(p - string) - 3;
234       return PCRE2_ERROR_UTF8_ERR17;
235       }
236     if (c > 0xf4 || (c == 0xf4 && d > 0x8f))
237       {
238       *erroroffset = (int)(p - string) - 3;
239       return PCRE2_ERROR_UTF8_ERR13;
240       }
241     break;
242 
243     /* 5-byte and 6-byte characters are not allowed by RFC 3629, and will be
244     rejected by the length test below. However, we do the appropriate tests
245     here so that overlong sequences get diagnosed, and also in case there is
246     ever an option for handling these larger code points. */
247 
248     /* 5-byte character. Check 3rd, 4th, and 5th bytes for 0x80. Then check for
249     1111 1000, xx00 0xxx */
250 
251     case 4:
252     if ((*(++p) & 0xc0) != 0x80)     /* Third byte */
253       {
254       *erroroffset = (int)(p - string) - 2;
255       return PCRE2_ERROR_UTF8_ERR7;
256       }
257     if ((*(++p) & 0xc0) != 0x80)     /* Fourth byte */
258       {
259       *erroroffset = (int)(p - string) - 3;
260       return PCRE2_ERROR_UTF8_ERR8;
261       }
262     if ((*(++p) & 0xc0) != 0x80)     /* Fifth byte */
263       {
264       *erroroffset = (int)(p - string) - 4;
265       return PCRE2_ERROR_UTF8_ERR9;
266       }
267     if (c == 0xf8 && (d & 0x38) == 0)
268       {
269       *erroroffset = (int)(p - string) - 4;
270       return PCRE2_ERROR_UTF8_ERR18;
271       }
272     break;
273 
274     /* 6-byte character. Check 3rd-6th bytes for 0x80. Then check for
275     1111 1100, xx00 00xx. */
276 
277     case 5:
278     if ((*(++p) & 0xc0) != 0x80)     /* Third byte */
279       {
280       *erroroffset = (int)(p - string) - 2;
281       return PCRE2_ERROR_UTF8_ERR7;
282       }
283     if ((*(++p) & 0xc0) != 0x80)     /* Fourth byte */
284       {
285       *erroroffset = (int)(p - string) - 3;
286       return PCRE2_ERROR_UTF8_ERR8;
287       }
288     if ((*(++p) & 0xc0) != 0x80)     /* Fifth byte */
289       {
290       *erroroffset = (int)(p - string) - 4;
291       return PCRE2_ERROR_UTF8_ERR9;
292       }
293     if ((*(++p) & 0xc0) != 0x80)     /* Sixth byte */
294       {
295       *erroroffset = (int)(p - string) - 5;
296       return PCRE2_ERROR_UTF8_ERR10;
297       }
298     if (c == 0xfc && (d & 0x3c) == 0)
299       {
300       *erroroffset = (int)(p - string) - 5;
301       return PCRE2_ERROR_UTF8_ERR19;
302       }
303     break;
304     }
305 
306   /* Character is valid under RFC 2279, but 4-byte and 5-byte characters are
307   excluded by RFC 3629. The pointer p is currently at the last byte of the
308   character. */
309 
310   if (ab > 3)
311     {
312     *erroroffset = (int)(p - string) - ab;
313     return (ab == 4)? PCRE2_ERROR_UTF8_ERR11 : PCRE2_ERROR_UTF8_ERR12;
314     }
315   }
316 return 0;
317 
318 
319 /* ----------------- Check a UTF-16 string ----------------- */
320 
321 #elif PCRE2_CODE_UNIT_WIDTH == 16
322 
323 /* There's not so much work, nor so many errors, for UTF-16.
324 PCRE2_ERROR_UTF16_ERR1  Missing low surrogate at the end of the string
325 PCRE2_ERROR_UTF16_ERR2  Invalid low surrogate
326 PCRE2_ERROR_UTF16_ERR3  Isolated low surrogate
327 */
328 
329 for (p = string; length > 0; p++)
330   {
331   c = *p;
332   length--;
333 
334   if ((c & 0xf800) != 0xd800)
335     {
336     /* Normal UTF-16 code point. Neither high nor low surrogate. */
337     }
338   else if ((c & 0x0400) == 0)
339     {
340     /* High surrogate. Must be a followed by a low surrogate. */
341     if (length == 0)
342       {
343       *erroroffset = p - string;
344       return PCRE2_ERROR_UTF16_ERR1;
345       }
346     p++;
347     length--;
348     if ((*p & 0xfc00) != 0xdc00)
349       {
350       *erroroffset = p - string - 1;
351       return PCRE2_ERROR_UTF16_ERR2;
352       }
353     }
354   else
355     {
356     /* Isolated low surrogate. Always an error. */
357     *erroroffset = p - string;
358     return PCRE2_ERROR_UTF16_ERR3;
359     }
360   }
361 return 0;
362 
363 
364 
365 /* ----------------- Check a UTF-32 string ----------------- */
366 
367 #else
368 
369 /* There is very little to do for a UTF-32 string.
370 PCRE2_ERROR_UTF32_ERR1  Surrogate character
371 PCRE2_ERROR_UTF32_ERR2  Character > 0x10ffff
372 */
373 
374 for (p = string; length > 0; length--, p++)
375   {
376   c = *p;
377   if ((c & 0xfffff800u) != 0xd800u)
378     {
379     /* Normal UTF-32 code point. Neither high nor low surrogate. */
380     if (c > 0x10ffffu)
381       {
382       *erroroffset = p - string;
383       return PCRE2_ERROR_UTF32_ERR2;
384       }
385     }
386   else
387     {
388     /* A surrogate */
389     *erroroffset = p - string;
390     return PCRE2_ERROR_UTF32_ERR1;
391     }
392   }
393 return 0;
394 #endif  /* CODE_UNIT_WIDTH */
395 }
396 #endif  /* SUPPORT_UNICODE */
397 
398 /* End of pcre2_valid_utf.c */
399