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 Copyright (c) 1997-2012 University of Cambridge
10
11 -----------------------------------------------------------------------------
12 Redistribution and use in source and binary forms, with or without
13 modification, are permitted provided that the following conditions are met:
14
15 * Redistributions of source code must retain the above copyright notice,
16 this list of conditions and the following disclaimer.
17
18 * Redistributions in binary form must reproduce the above copyright
19 notice, this list of conditions and the following disclaimer in the
20 documentation and/or other materials provided with the distribution.
21
22 * Neither the name of the University of Cambridge nor the names of its
23 contributors may be used to endorse or promote products derived from
24 this software without specific prior written permission.
25
26 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
27 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
30 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36 POSSIBILITY OF SUCH DAMAGE.
37 -----------------------------------------------------------------------------
38 */
39
40
41 /* This module contains an internal function for validating UTF-8 character
42 strings. */
43
44
45 #ifdef HAVE_CONFIG_H
46 #include "config.h"
47 #endif
48
49 #include "pcre_internal.h"
50
51
52 /*************************************************
53 * Validate a UTF-8 string *
54 *************************************************/
55
56 /* This function is called (optionally) at the start of compile or match, to
57 check that a supposed UTF-8 string is actually valid. The early check means
58 that subsequent code can assume it is dealing with a valid string. The check
59 can be turned off for maximum performance, but the consequences of supplying an
60 invalid string are then undefined.
61
62 Originally, this function checked according to RFC 2279, allowing for values in
63 the range 0 to 0x7fffffff, up to 6 bytes long, but ensuring that they were in
64 the canonical format. Once somebody had pointed out RFC 3629 to me (it
65 obsoletes 2279), additional restrictions were applied. The values are now
66 limited to be between 0 and 0x0010ffff, no more than 4 bytes long, and the
67 subrange 0xd000 to 0xdfff is excluded. However, the format of 5-byte and 6-byte
68 characters is still checked.
69
70 From release 8.13 more information about the details of the error are passed
71 back in the returned value:
72
73 PCRE_UTF8_ERR0 No error
74 PCRE_UTF8_ERR1 Missing 1 byte at the end of the string
75 PCRE_UTF8_ERR2 Missing 2 bytes at the end of the string
76 PCRE_UTF8_ERR3 Missing 3 bytes at the end of the string
77 PCRE_UTF8_ERR4 Missing 4 bytes at the end of the string
78 PCRE_UTF8_ERR5 Missing 5 bytes at the end of the string
79 PCRE_UTF8_ERR6 2nd-byte's two top bits are not 0x80
80 PCRE_UTF8_ERR7 3rd-byte's two top bits are not 0x80
81 PCRE_UTF8_ERR8 4th-byte's two top bits are not 0x80
82 PCRE_UTF8_ERR9 5th-byte's two top bits are not 0x80
83 PCRE_UTF8_ERR10 6th-byte's two top bits are not 0x80
84 PCRE_UTF8_ERR11 5-byte character is not permitted by RFC 3629
85 PCRE_UTF8_ERR12 6-byte character is not permitted by RFC 3629
86 PCRE_UTF8_ERR13 4-byte character with value > 0x10ffff is not permitted
87 PCRE_UTF8_ERR14 3-byte character with value 0xd000-0xdfff is not permitted
88 PCRE_UTF8_ERR15 Overlong 2-byte sequence
89 PCRE_UTF8_ERR16 Overlong 3-byte sequence
90 PCRE_UTF8_ERR17 Overlong 4-byte sequence
91 PCRE_UTF8_ERR18 Overlong 5-byte sequence (won't ever occur)
92 PCRE_UTF8_ERR19 Overlong 6-byte sequence (won't ever occur)
93 PCRE_UTF8_ERR20 Isolated 0x80 byte (not within UTF-8 character)
94 PCRE_UTF8_ERR21 Byte with the illegal value 0xfe or 0xff
95 PCRE_UTF8_ERR22 Non-character
96
97 Arguments:
98 string points to the string
99 length length of string, or -1 if the string is zero-terminated
100 errp pointer to an error position offset variable
101
102 Returns: = 0 if the string is a valid UTF-8 string
103 > 0 otherwise, setting the offset of the bad character
104 */
105
106 int
PRIV(valid_utf)107 PRIV(valid_utf)(PCRE_PUCHAR string, int length, int *erroroffset)
108 {
109 #ifdef SUPPORT_UTF
110 register PCRE_PUCHAR p;
111
112 if (length < 0)
113 {
114 for (p = string; *p != 0; p++);
115 length = (int)(p - string);
116 }
117
118 for (p = string; length-- > 0; p++)
119 {
120 register pcre_uchar ab, c, d;
121 pcre_uint32 v = 0;
122
123 c = *p;
124 if (c < 128) continue; /* ASCII character */
125
126 if (c < 0xc0) /* Isolated 10xx xxxx byte */
127 {
128 *erroroffset = (int)(p - string);
129 return PCRE_UTF8_ERR20;
130 }
131
132 if (c >= 0xfe) /* Invalid 0xfe or 0xff bytes */
133 {
134 *erroroffset = (int)(p - string);
135 return PCRE_UTF8_ERR21;
136 }
137
138 ab = PRIV(utf8_table4)[c & 0x3f]; /* Number of additional bytes */
139 if (length < ab)
140 {
141 *erroroffset = (int)(p - string); /* Missing bytes */
142 return ab - length; /* Codes ERR1 to ERR5 */
143 }
144 length -= ab; /* Length remaining */
145
146 /* Check top bits in the second byte */
147
148 if (((d = *(++p)) & 0xc0) != 0x80)
149 {
150 *erroroffset = (int)(p - string) - 1;
151 return PCRE_UTF8_ERR6;
152 }
153
154 /* For each length, check that the remaining bytes start with the 0x80 bit
155 set and not the 0x40 bit. Then check for an overlong sequence, and for the
156 excluded range 0xd800 to 0xdfff. */
157
158 switch (ab)
159 {
160 /* 2-byte character. No further bytes to check for 0x80. Check first byte
161 for for xx00 000x (overlong sequence). */
162
163 case 1: if ((c & 0x3e) == 0)
164 {
165 *erroroffset = (int)(p - string) - 1;
166 return PCRE_UTF8_ERR15;
167 }
168 break;
169
170 /* 3-byte character. Check third byte for 0x80. Then check first 2 bytes
171 for 1110 0000, xx0x xxxx (overlong sequence) or
172 1110 1101, 1010 xxxx (0xd800 - 0xdfff) */
173
174 case 2:
175 if ((*(++p) & 0xc0) != 0x80) /* Third byte */
176 {
177 *erroroffset = (int)(p - string) - 2;
178 return PCRE_UTF8_ERR7;
179 }
180 if (c == 0xe0 && (d & 0x20) == 0)
181 {
182 *erroroffset = (int)(p - string) - 2;
183 return PCRE_UTF8_ERR16;
184 }
185 if (c == 0xed && d >= 0xa0)
186 {
187 *erroroffset = (int)(p - string) - 2;
188 return PCRE_UTF8_ERR14;
189 }
190 v = ((c & 0x0f) << 12) | ((d & 0x3f) << 6) | (*p & 0x3f);
191 break;
192
193 /* 4-byte character. Check 3rd and 4th bytes for 0x80. Then check first 2
194 bytes for for 1111 0000, xx00 xxxx (overlong sequence), then check for a
195 character greater than 0x0010ffff (f4 8f bf bf) */
196
197 case 3:
198 if ((*(++p) & 0xc0) != 0x80) /* Third byte */
199 {
200 *erroroffset = (int)(p - string) - 2;
201 return PCRE_UTF8_ERR7;
202 }
203 if ((*(++p) & 0xc0) != 0x80) /* Fourth byte */
204 {
205 *erroroffset = (int)(p - string) - 3;
206 return PCRE_UTF8_ERR8;
207 }
208 if (c == 0xf0 && (d & 0x30) == 0)
209 {
210 *erroroffset = (int)(p - string) - 3;
211 return PCRE_UTF8_ERR17;
212 }
213 if (c > 0xf4 || (c == 0xf4 && d > 0x8f))
214 {
215 *erroroffset = (int)(p - string) - 3;
216 return PCRE_UTF8_ERR13;
217 }
218 v = ((c & 0x07) << 18) | ((d & 0x3f) << 12) | ((p[-1] & 0x3f) << 6) | (*p & 0x3f);
219 break;
220
221 /* 5-byte and 6-byte characters are not allowed by RFC 3629, and will be
222 rejected by the length test below. However, we do the appropriate tests
223 here so that overlong sequences get diagnosed, and also in case there is
224 ever an option for handling these larger code points. */
225
226 /* 5-byte character. Check 3rd, 4th, and 5th bytes for 0x80. Then check for
227 1111 1000, xx00 0xxx */
228
229 case 4:
230 if ((*(++p) & 0xc0) != 0x80) /* Third byte */
231 {
232 *erroroffset = (int)(p - string) - 2;
233 return PCRE_UTF8_ERR7;
234 }
235 if ((*(++p) & 0xc0) != 0x80) /* Fourth byte */
236 {
237 *erroroffset = (int)(p - string) - 3;
238 return PCRE_UTF8_ERR8;
239 }
240 if ((*(++p) & 0xc0) != 0x80) /* Fifth byte */
241 {
242 *erroroffset = (int)(p - string) - 4;
243 return PCRE_UTF8_ERR9;
244 }
245 if (c == 0xf8 && (d & 0x38) == 0)
246 {
247 *erroroffset = (int)(p - string) - 4;
248 return PCRE_UTF8_ERR18;
249 }
250 break;
251
252 /* 6-byte character. Check 3rd-6th bytes for 0x80. Then check for
253 1111 1100, xx00 00xx. */
254
255 case 5:
256 if ((*(++p) & 0xc0) != 0x80) /* Third byte */
257 {
258 *erroroffset = (int)(p - string) - 2;
259 return PCRE_UTF8_ERR7;
260 }
261 if ((*(++p) & 0xc0) != 0x80) /* Fourth byte */
262 {
263 *erroroffset = (int)(p - string) - 3;
264 return PCRE_UTF8_ERR8;
265 }
266 if ((*(++p) & 0xc0) != 0x80) /* Fifth byte */
267 {
268 *erroroffset = (int)(p - string) - 4;
269 return PCRE_UTF8_ERR9;
270 }
271 if ((*(++p) & 0xc0) != 0x80) /* Sixth byte */
272 {
273 *erroroffset = (int)(p - string) - 5;
274 return PCRE_UTF8_ERR10;
275 }
276 if (c == 0xfc && (d & 0x3c) == 0)
277 {
278 *erroroffset = (int)(p - string) - 5;
279 return PCRE_UTF8_ERR19;
280 }
281 break;
282 }
283
284 /* Character is valid under RFC 2279, but 4-byte and 5-byte characters are
285 excluded by RFC 3629. The pointer p is currently at the last byte of the
286 character. */
287
288 if (ab > 3)
289 {
290 *erroroffset = (int)(p - string) - ab;
291 return (ab == 4)? PCRE_UTF8_ERR11 : PCRE_UTF8_ERR12;
292 }
293
294 /* Reject non-characters. The pointer p is currently at the last byte of the
295 character. */
296 if ((v & 0xfffeu) == 0xfffeu || (v >= 0xfdd0 && v <= 0xfdef))
297 {
298 *erroroffset = (int)(p - string) - ab;
299 return PCRE_UTF8_ERR22;
300 }
301 }
302
303 #else /* Not SUPPORT_UTF */
304 (void)(string); /* Keep picky compilers happy */
305 (void)(length);
306 (void)(erroroffset);
307 #endif
308
309 return PCRE_UTF8_ERR0; /* This indicates success */
310 }
311
312 /* End of pcre_valid_utf8.c */
313
