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117 lines
3.5 KiB
C
117 lines
3.5 KiB
C
#include <stdint.h>
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#include "re_config.h"
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#include "pcre_internal.h"
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/*************************************************
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* Validate a UTF-8 string *
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*************************************************/
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/* This function is called (optionally) at the start of compile or match, to
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validate that a supposed UTF-8 string is actually valid. The early check means
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that subsequent code can assume it is dealing with a valid string. The check
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can be turned off for maximum performance, but the consequences of supplying
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an invalid string are then undefined.
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Originally, this function checked according to RFC 2279, allowing for values in
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the range 0 to 0x7fffffff, up to 6 bytes long, but ensuring that they were in
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the canonical format. Once somebody had pointed out RFC 3629 to me (it
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obsoletes 2279), additional restrictions were applied. The values are now
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limited to be between 0 and 0x0010ffff, no more than 4 bytes long, and the
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subrange 0xd000 to 0xdfff is excluded.
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Arguments:
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string points to the string
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length length of string, or -1 if the string is zero-terminated
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Returns: < 0 if the string is a valid UTF-8 string
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>= 0 otherwise; the value is the offset of the bad byte
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*/
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int
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_pcre_valid_utf8(const uschar *string, int length)
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{
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#ifdef SUPPORT_UTF8
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register const uschar *p;
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if (length < 0)
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{
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for (p = string; *p != 0; p++);
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length = (uintptr_t)p - (uintptr_t)string;
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}
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for (p = string; length-- > 0; p++)
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{
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register int ab;
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register int c = *p;
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if (c < 128) continue;
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if (c < 0xc0) return (uintptr_t)p - (uintptr_t)string;
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ab = _pcre_utf8_table4[c & 0x3f]; /* Number of additional bytes */
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if (length < ab || ab > 3) return (uintptr_t)p - (uintptr_t)string;
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length -= ab;
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/* Check top bits in the second byte */
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if ((*(++p) & 0xc0) != 0x80) return (uintptr_t)p - (uintptr_t)string;
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/* Check for overlong sequences for each different length, and for the
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excluded range 0xd000 to 0xdfff. */
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switch (ab)
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{
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/* Check for xx00 000x (overlong sequence) */
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case 1:
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if ((c & 0x3e) == 0) return (uintptr_t)p - (uintptr_t)string;
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continue; /* We know there aren't any more bytes to check */
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/* Check for 1110 0000, xx0x xxxx (overlong sequence) or
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1110 1101, 1010 xxxx (0xd000 - 0xdfff) */
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case 2:
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if ((c == 0xe0 && (*p & 0x20) == 0) ||
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(c == 0xed && *p >= 0xa0))
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return (uintptr_t)p - (uintptr_t)string;
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break;
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/* Check for 1111 0000, xx00 xxxx (overlong sequence) or
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greater than 0x0010ffff (f4 8f bf bf) */
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case 3:
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if ((c == 0xf0 && (*p & 0x30) == 0) ||
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(c > 0xf4 ) ||
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(c == 0xf4 && *p > 0x8f))
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return (uintptr_t)p - (uintptr_t)string;
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break;
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#if 0
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/* These cases can no longer occur, as we restrict to a maximum of four
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bytes nowadays. Leave the code here in case we ever want to add an option
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for longer sequences. */
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/* Check for 1111 1000, xx00 0xxx */
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case 4:
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if (c == 0xf8 && (*p & 0x38) == 0) return (uintptr_t)p - (uintptr_t)string;
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break;
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/* Check for leading 0xfe or 0xff, and then for 1111 1100, xx00 00xx */
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case 5:
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if (c == 0xfe || c == 0xff ||
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(c == 0xfc && (*p & 0x3c) == 0)) return (uintptr_t)p - (uintptr_t)string;
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break;
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#endif
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}
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/* Check for valid bytes after the 2nd, if any; all must start 10 */
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while (--ab > 0)
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{
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if ((*(++p) & 0xc0) != 0x80) return (uintptr_t)p - (uintptr_t)string;
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}
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}
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#endif
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return -1;
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}
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/* End of pcre_valid_utf8.c */
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