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) 1997-2013 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 Unused (was 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
122 c = *p;
123 if (c < 128) continue; /* ASCII character */
124
125 if (c < 0xc0) /* Isolated 10xx xxxx byte */
126 {
127 *erroroffset = (int)(p - string);
128 return PCRE_UTF8_ERR20;
129 }
130
131 if (c >= 0xfe) /* Invalid 0xfe or 0xff bytes */
132 {
133 *erroroffset = (int)(p - string);
134 return PCRE_UTF8_ERR21;
135 }
136
137 ab = PRIV(utf8_table4)[c & 0x3f]; /* Number of additional bytes */
138 if (length < ab)
139 {
140 *erroroffset = (int)(p - string); /* Missing bytes */
141 return ab - length; /* Codes ERR1 to ERR5 */
142 }
143 length -= ab; /* Length remaining */
144
145 /* Check top bits in the second byte */
146
147 if (((d = *(++p)) & 0xc0) != 0x80)
148 {
149 *erroroffset = (int)(p - string) - 1;
150 return PCRE_UTF8_ERR6;
151 }
152
153 /* For each length, check that the remaining bytes start with the 0x80 bit
154 set and not the 0x40 bit. Then check for an overlong sequence, and for the
155 excluded range 0xd800 to 0xdfff. */
156
157 switch (ab)
158 {
159 /* 2-byte character. No further bytes to check for 0x80. Check first byte
160 for for xx00 000x (overlong sequence). */
161
162 case 1: if ((c & 0x3e) == 0)
163 {
164 *erroroffset = (int)(p - string) - 1;
165 return PCRE_UTF8_ERR15;
166 }
167 break;
168
169 /* 3-byte character. Check third byte for 0x80. Then check first 2 bytes
170 for 1110 0000, xx0x xxxx (overlong sequence) or
171 1110 1101, 1010 xxxx (0xd800 - 0xdfff) */
172
173 case 2:
174 if ((*(++p) & 0xc0) != 0x80) /* Third byte */
175 {
176 *erroroffset = (int)(p - string) - 2;
177 return PCRE_UTF8_ERR7;
178 }
179 if (c == 0xe0 && (d & 0x20) == 0)
180 {
181 *erroroffset = (int)(p - string) - 2;
182 return PCRE_UTF8_ERR16;
183 }
184 if (c == 0xed && d >= 0xa0)
185 {
186 *erroroffset = (int)(p - string) - 2;
187 return PCRE_UTF8_ERR14;
188 }
189 break;
190
191 /* 4-byte character. Check 3rd and 4th bytes for 0x80. Then check first 2
192 bytes for for 1111 0000, xx00 xxxx (overlong sequence), then check for a
193 character greater than 0x0010ffff (f4 8f bf bf) */
194
195 case 3:
196 if ((*(++p) & 0xc0) != 0x80) /* Third byte */
197 {
198 *erroroffset = (int)(p - string) - 2;
199 return PCRE_UTF8_ERR7;
200 }
201 if ((*(++p) & 0xc0) != 0x80) /* Fourth byte */
202 {
203 *erroroffset = (int)(p - string) - 3;
204 return PCRE_UTF8_ERR8;
205 }
206 if (c == 0xf0 && (d & 0x30) == 0)
207 {
208 *erroroffset = (int)(p - string) - 3;
209 return PCRE_UTF8_ERR17;
210 }
211 if (c > 0xf4 || (c == 0xf4 && d > 0x8f))
212 {
213 *erroroffset = (int)(p - string) - 3;
214 return PCRE_UTF8_ERR13;
215 }
216 break;
217
218 /* 5-byte and 6-byte characters are not allowed by RFC 3629, and will be
219 rejected by the length test below. However, we do the appropriate tests
220 here so that overlong sequences get diagnosed, and also in case there is
221 ever an option for handling these larger code points. */
222
223 /* 5-byte character. Check 3rd, 4th, and 5th bytes for 0x80. Then check for
224 1111 1000, xx00 0xxx */
225
226 case 4:
227 if ((*(++p) & 0xc0) != 0x80) /* Third byte */
228 {
229 *erroroffset = (int)(p - string) - 2;
230 return PCRE_UTF8_ERR7;
231 }
232 if ((*(++p) & 0xc0) != 0x80) /* Fourth byte */
233 {
234 *erroroffset = (int)(p - string) - 3;
235 return PCRE_UTF8_ERR8;
236 }
237 if ((*(++p) & 0xc0) != 0x80) /* Fifth byte */
238 {
239 *erroroffset = (int)(p - string) - 4;
240 return PCRE_UTF8_ERR9;
241 }
242 if (c == 0xf8 && (d & 0x38) == 0)
243 {
244 *erroroffset = (int)(p - string) - 4;
245 return PCRE_UTF8_ERR18;
246 }
247 break;
248
249 /* 6-byte character. Check 3rd-6th bytes for 0x80. Then check for
250 1111 1100, xx00 00xx. */
251
252 case 5:
253 if ((*(++p) & 0xc0) != 0x80) /* Third byte */
254 {
255 *erroroffset = (int)(p - string) - 2;
256 return PCRE_UTF8_ERR7;
257 }
258 if ((*(++p) & 0xc0) != 0x80) /* Fourth byte */
259 {
260 *erroroffset = (int)(p - string) - 3;
261 return PCRE_UTF8_ERR8;
262 }
263 if ((*(++p) & 0xc0) != 0x80) /* Fifth byte */
264 {
265 *erroroffset = (int)(p - string) - 4;
266 return PCRE_UTF8_ERR9;
267 }
268 if ((*(++p) & 0xc0) != 0x80) /* Sixth byte */
269 {
270 *erroroffset = (int)(p - string) - 5;
271 return PCRE_UTF8_ERR10;
272 }
273 if (c == 0xfc && (d & 0x3c) == 0)
274 {
275 *erroroffset = (int)(p - string) - 5;
276 return PCRE_UTF8_ERR19;
277 }
278 break;
279 }
280
281 /* Character is valid under RFC 2279, but 4-byte and 5-byte characters are
282 excluded by RFC 3629. The pointer p is currently at the last byte of the
283 character. */
284
285 if (ab > 3)
286 {
287 *erroroffset = (int)(p - string) - ab;
288 return (ab == 4)? PCRE_UTF8_ERR11 : PCRE_UTF8_ERR12;
289 }
290 }
291
292 #else /* Not SUPPORT_UTF */
293 (void)(string); /* Keep picky compilers happy */
294 (void)(length);
295 (void)(erroroffset);
296 #endif
297
298 return PCRE_UTF8_ERR0; /* This indicates success */
299 }
300
301 /* End of pcre_valid_utf8.c */
302