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 #include "config.h"
46
47 #include "pcre_internal.h"
48
49
50 /*************************************************
51 * Validate a UTF-8 string *
52 *************************************************/
53
54 /* This function is called (optionally) at the start of compile or match, to
55 check that a supposed UTF-8 string is actually valid. The early check means
56 that subsequent code can assume it is dealing with a valid string. The check
57 can be turned off for maximum performance, but the consequences of supplying an
58 invalid string are then undefined.
59
60 Originally, this function checked according to RFC 2279, allowing for values in
61 the range 0 to 0x7fffffff, up to 6 bytes long, but ensuring that they were in
62 the canonical format. Once somebody had pointed out RFC 3629 to me (it
63 obsoletes 2279), additional restrictions were applied. The values are now
64 limited to be between 0 and 0x0010ffff, no more than 4 bytes long, and the
65 subrange 0xd000 to 0xdfff is excluded. However, the format of 5-byte and 6-byte
66 characters is still checked.
67
68 From release 8.13 more information about the details of the error are passed
69 back in the returned value:
70
71 PCRE_UTF8_ERR0 No error
72 PCRE_UTF8_ERR1 Missing 1 byte at the end of the string
73 PCRE_UTF8_ERR2 Missing 2 bytes at the end of the string
74 PCRE_UTF8_ERR3 Missing 3 bytes at the end of the string
75 PCRE_UTF8_ERR4 Missing 4 bytes at the end of the string
76 PCRE_UTF8_ERR5 Missing 5 bytes at the end of the string
77 PCRE_UTF8_ERR6 2nd-byte's two top bits are not 0x80
78 PCRE_UTF8_ERR7 3rd-byte's two top bits are not 0x80
79 PCRE_UTF8_ERR8 4th-byte's two top bits are not 0x80
80 PCRE_UTF8_ERR9 5th-byte's two top bits are not 0x80
81 PCRE_UTF8_ERR10 6th-byte's two top bits are not 0x80
82 PCRE_UTF8_ERR11 5-byte character is not permitted by RFC 3629
83 PCRE_UTF8_ERR12 6-byte character is not permitted by RFC 3629
84 PCRE_UTF8_ERR13 4-byte character with value > 0x10ffff is not permitted
85 PCRE_UTF8_ERR14 3-byte character with value 0xd000-0xdfff is not permitted
86 PCRE_UTF8_ERR15 Overlong 2-byte sequence
87 PCRE_UTF8_ERR16 Overlong 3-byte sequence
88 PCRE_UTF8_ERR17 Overlong 4-byte sequence
89 PCRE_UTF8_ERR18 Overlong 5-byte sequence (won't ever occur)
90 PCRE_UTF8_ERR19 Overlong 6-byte sequence (won't ever occur)
91 PCRE_UTF8_ERR20 Isolated 0x80 byte (not within UTF-8 character)
92 PCRE_UTF8_ERR21 Byte with the illegal value 0xfe or 0xff
93
94 Arguments:
95 string points to the string
96 length length of string, or -1 if the string is zero-terminated
97 errp pointer to an error position offset variable
98
99 Returns: = 0 if the string is a valid UTF-8 string
100 > 0 otherwise, setting the offset of the bad character
101 */
102
103 int
PRIV(valid_utf)104 PRIV(valid_utf)(PCRE_PUCHAR string, int length, int *erroroffset)
105 {
106 #ifdef SUPPORT_UTF
107 PCRE_PUCHAR p;
108
109 if (length < 0)
110 {
111 for (p = string; *p != 0; p++);
112 length = (int)(p - string);
113 }
114
115 for (p = string; length-- > 0; p++)
116 {
117 int ab, c, d;
118
119 c = *p;
120 if (c < 128) continue; /* ASCII character */
121
122 if (c < 0xc0) /* Isolated 10xx xxxx byte */
123 {
124 *erroroffset = (int)(p - string);
125 return PCRE_UTF8_ERR20;
126 }
127
128 if (c >= 0xfe) /* Invalid 0xfe or 0xff bytes */
129 {
130 *erroroffset = (int)(p - string);
131 return PCRE_UTF8_ERR21;
132 }
133
134 ab = PRIV(utf8_table4)[c & 0x3f]; /* Number of additional bytes */
135 if (length < ab)
136 {
137 *erroroffset = (int)(p - string); /* Missing bytes */
138 return ab - length; /* Codes ERR1 to ERR5 */
139 }
140 length -= ab; /* Length remaining */
141
142 /* Check top bits in the second byte */
143
144 if (((d = *(++p)) & 0xc0) != 0x80)
145 {
146 *erroroffset = (int)(p - string) - 1;
147 return PCRE_UTF8_ERR6;
148 }
149
150 /* For each length, check that the remaining bytes start with the 0x80 bit
151 set and not the 0x40 bit. Then check for an overlong sequence, and for the
152 excluded range 0xd800 to 0xdfff. */
153
154 switch (ab)
155 {
156 /* 2-byte character. No further bytes to check for 0x80. Check first byte
157 for for xx00 000x (overlong sequence). */
158
159 case 1: if ((c & 0x3e) == 0)
160 {
161 *erroroffset = (int)(p - string) - 1;
162 return PCRE_UTF8_ERR15;
163 }
164 break;
165
166 /* 3-byte character. Check third byte for 0x80. Then check first 2 bytes
167 for 1110 0000, xx0x xxxx (overlong sequence) or
168 1110 1101, 1010 xxxx (0xd800 - 0xdfff) */
169
170 case 2:
171 if ((*(++p) & 0xc0) != 0x80) /* Third byte */
172 {
173 *erroroffset = (int)(p - string) - 2;
174 return PCRE_UTF8_ERR7;
175 }
176 if (c == 0xe0 && (d & 0x20) == 0)
177 {
178 *erroroffset = (int)(p - string) - 2;
179 return PCRE_UTF8_ERR16;
180 }
181 if (c == 0xed && d >= 0xa0)
182 {
183 *erroroffset = (int)(p - string) - 2;
184 return PCRE_UTF8_ERR14;
185 }
186 break;
187
188 /* 4-byte character. Check 3rd and 4th bytes for 0x80. Then check first 2
189 bytes for for 1111 0000, xx00 xxxx (overlong sequence), then check for a
190 character greater than 0x0010ffff (f4 8f bf bf) */
191
192 case 3:
193 if ((*(++p) & 0xc0) != 0x80) /* Third byte */
194 {
195 *erroroffset = (int)(p - string) - 2;
196 return PCRE_UTF8_ERR7;
197 }
198 if ((*(++p) & 0xc0) != 0x80) /* Fourth byte */
199 {
200 *erroroffset = (int)(p - string) - 3;
201 return PCRE_UTF8_ERR8;
202 }
203 if (c == 0xf0 && (d & 0x30) == 0)
204 {
205 *erroroffset = (int)(p - string) - 3;
206 return PCRE_UTF8_ERR17;
207 }
208 if (c > 0xf4 || (c == 0xf4 && d > 0x8f))
209 {
210 *erroroffset = (int)(p - string) - 3;
211 return PCRE_UTF8_ERR13;
212 }
213 break;
214
215 /* 5-byte and 6-byte characters are not allowed by RFC 3629, and will be
216 rejected by the length test below. However, we do the appropriate tests
217 here so that overlong sequences get diagnosed, and also in case there is
218 ever an option for handling these larger code points. */
219
220 /* 5-byte character. Check 3rd, 4th, and 5th bytes for 0x80. Then check for
221 1111 1000, xx00 0xxx */
222
223 case 4:
224 if ((*(++p) & 0xc0) != 0x80) /* Third byte */
225 {
226 *erroroffset = (int)(p - string) - 2;
227 return PCRE_UTF8_ERR7;
228 }
229 if ((*(++p) & 0xc0) != 0x80) /* Fourth byte */
230 {
231 *erroroffset = (int)(p - string) - 3;
232 return PCRE_UTF8_ERR8;
233 }
234 if ((*(++p) & 0xc0) != 0x80) /* Fifth byte */
235 {
236 *erroroffset = (int)(p - string) - 4;
237 return PCRE_UTF8_ERR9;
238 }
239 if (c == 0xf8 && (d & 0x38) == 0)
240 {
241 *erroroffset = (int)(p - string) - 4;
242 return PCRE_UTF8_ERR18;
243 }
244 break;
245
246 /* 6-byte character. Check 3rd-6th bytes for 0x80. Then check for
247 1111 1100, xx00 00xx. */
248
249 case 5:
250 if ((*(++p) & 0xc0) != 0x80) /* Third byte */
251 {
252 *erroroffset = (int)(p - string) - 2;
253 return PCRE_UTF8_ERR7;
254 }
255 if ((*(++p) & 0xc0) != 0x80) /* Fourth byte */
256 {
257 *erroroffset = (int)(p - string) - 3;
258 return PCRE_UTF8_ERR8;
259 }
260 if ((*(++p) & 0xc0) != 0x80) /* Fifth byte */
261 {
262 *erroroffset = (int)(p - string) - 4;
263 return PCRE_UTF8_ERR9;
264 }
265 if ((*(++p) & 0xc0) != 0x80) /* Sixth byte */
266 {
267 *erroroffset = (int)(p - string) - 5;
268 return PCRE_UTF8_ERR10;
269 }
270 if (c == 0xfc && (d & 0x3c) == 0)
271 {
272 *erroroffset = (int)(p - string) - 5;
273 return PCRE_UTF8_ERR19;
274 }
275 break;
276 }
277
278 /* Character is valid under RFC 2279, but 4-byte and 5-byte characters are
279 excluded by RFC 3629. The pointer p is currently at the last byte of the
280 character. */
281
282 if (ab > 3)
283 {
284 *erroroffset = (int)(p - string) - ab;
285 return (ab == 4)? PCRE_UTF8_ERR11 : PCRE_UTF8_ERR12;
286 }
287 }
288
289 #else /* SUPPORT_UTF */
290 (void)(string); /* Keep picky compilers happy */
291 (void)(length);
292 #endif
293
294 return PCRE_UTF8_ERR0; /* This indicates success */
295 }
296
297 /* End of pcre_valid_utf8.c */
298