/*************************************************

*      Perl-Compatible Regular Expressions       *

*************************************************/

/* PCRE is a library of functions to support regular expressions whose syntax

and semantics are as close as possible to those of the Perl 5 language.

                       Written by Philip Hazel

           Copyright (c) 1997-2012 University of Cambridge

-----------------------------------------------------------------------------

Redistribution and use in source and binary forms, with or without

modification, are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright notice,

      this list of conditions and the following disclaimer.

    * Redistributions in binary form must reproduce the above copyright

      notice, this list of conditions and the following disclaimer in the

      documentation and/or other materials provided with the distribution.

    * Neither the name of the University of Cambridge nor the names of its

      contributors may be used to endorse or promote products derived from

      this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE

LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

POSSIBILITY OF SUCH DAMAGE.

-----------------------------------------------------------------------------

*/

/* This module contains an internal function for validating UTF-8 character

strings. */

#include "config.h"

#include "pcre_internal.h"

/*************************************************

*         Validate a UTF-8 string                *

*************************************************/

/* This function is called (optionally) at the start of compile or match, to

check that a supposed UTF-8 string is actually valid. The early check means

that subsequent code can assume it is dealing with a valid string. The check

can be turned off for maximum performance, but the consequences of supplying an

invalid string are then undefined.

Originally, this function checked according to RFC 2279, allowing for values in

the range 0 to 0x7fffffff, up to 6 bytes long, but ensuring that they were in

the canonical format. Once somebody had pointed out RFC 3629 to me (it

obsoletes 2279), additional restrictions were applied. The values are now

limited to be between 0 and 0x0010ffff, no more than 4 bytes long, and the

subrange 0xd000 to 0xdfff is excluded. However, the format of 5-byte and 6-byte

characters is still checked.

From release 8.13 more information about the details of the error are passed

back in the returned value:

PCRE_UTF8_ERR0   No error

PCRE_UTF8_ERR1   Missing 1 byte at the end of the string

PCRE_UTF8_ERR2   Missing 2 bytes at the end of the string

PCRE_UTF8_ERR3   Missing 3 bytes at the end of the string

PCRE_UTF8_ERR4   Missing 4 bytes at the end of the string

PCRE_UTF8_ERR5   Missing 5 bytes at the end of the string

PCRE_UTF8_ERR6   2nd-byte's two top bits are not 0x80

PCRE_UTF8_ERR7   3rd-byte's two top bits are not 0x80

PCRE_UTF8_ERR8   4th-byte's two top bits are not 0x80

PCRE_UTF8_ERR9   5th-byte's two top bits are not 0x80

PCRE_UTF8_ERR10  6th-byte's two top bits are not 0x80

PCRE_UTF8_ERR11  5-byte character is not permitted by RFC 3629

PCRE_UTF8_ERR12  6-byte character is not permitted by RFC 3629

PCRE_UTF8_ERR13  4-byte character with value > 0x10ffff is not permitted

PCRE_UTF8_ERR14  3-byte character with value 0xd000-0xdfff is not permitted

PCRE_UTF8_ERR15  Overlong 2-byte sequence

PCRE_UTF8_ERR16  Overlong 3-byte sequence

PCRE_UTF8_ERR17  Overlong 4-byte sequence

PCRE_UTF8_ERR18  Overlong 5-byte sequence (won't ever occur)

PCRE_UTF8_ERR19  Overlong 6-byte sequence (won't ever occur)

PCRE_UTF8_ERR20  Isolated 0x80 byte (not within UTF-8 character)

PCRE_UTF8_ERR21  Byte with the illegal value 0xfe or 0xff

Arguments:

  string       points to the string

  length       length of string, or -1 if the string is zero-terminated

  errp         pointer to an error position offset variable

Returns:       = 0    if the string is a valid UTF-8 string

               > 0    otherwise, setting the offset of the bad character

*/

int

PRIV(valid_utf)(PCRE_PUCHAR string, int length, int *erroroffset)

{

#ifdef SUPPORT_UTF

PCRE_PUCHAR p;

if (length < 0)

  {

  for (p = string; *p != 0; p++);

  length = (int)(p - string);

  }

for (p = string; length-- > 0; p++)

  {

  int ab, c, d;

  c = *p;

  if (c < 128) continue;                /* ASCII character */

  if (c < 0xc0)                         /* Isolated 10xx xxxx byte */

    {

    *erroroffset = (int)(p - string);

    return PCRE_UTF8_ERR20;

    }

  if (c >= 0xfe)                        /* Invalid 0xfe or 0xff bytes */

    {

    *erroroffset = (int)(p - string);

    return PCRE_UTF8_ERR21;

    }

  ab = PRIV(utf8_table4)[c & 0x3f];     /* Number of additional bytes */

  if (length < ab)

    {

    *erroroffset = (int)(p - string);          /* Missing bytes */

    return ab - length;                 /* Codes ERR1 to ERR5 */

    }

  length -= ab;                         /* Length remaining */

  /* Check top bits in the second byte */

  if (((d = *(++p)) & 0xc0) != 0x80)

    {

    *erroroffset = (int)(p - string) - 1;

    return PCRE_UTF8_ERR6;

    }

  /* For each length, check that the remaining bytes start with the 0x80 bit

  set and not the 0x40 bit. Then check for an overlong sequence, and for the

  excluded range 0xd800 to 0xdfff. */

  switch (ab)

    {

    /* 2-byte character. No further bytes to check for 0x80. Check first byte

    for for xx00 000x (overlong sequence). */

    case 1: if ((c & 0x3e) == 0)

      {

      *erroroffset = (int)(p - string) - 1;

      return PCRE_UTF8_ERR15;

      }

    break;

    /* 3-byte character. Check third byte for 0x80. Then check first 2 bytes

      for 1110 0000, xx0x xxxx (overlong sequence) or

          1110 1101, 1010 xxxx (0xd800 - 0xdfff) */

    case 2:

    if ((*(++p) & 0xc0) != 0x80)     /* Third byte */

      {

      *erroroffset = (int)(p - string) - 2;

      return PCRE_UTF8_ERR7;

      }

    if (c == 0xe0 && (d & 0x20) == 0)

      {

      *erroroffset = (int)(p - string) - 2;

      return PCRE_UTF8_ERR16;

      }

    if (c == 0xed && d >= 0xa0)

      {

      *erroroffset = (int)(p - string) - 2;

      return PCRE_UTF8_ERR14;

      }

    break;

    /* 4-byte character. Check 3rd and 4th bytes for 0x80. Then check first 2

       bytes for for 1111 0000, xx00 xxxx (overlong sequence), then check for a

       character greater than 0x0010ffff (f4 8f bf bf) */

    case 3:

    if ((*(++p) & 0xc0) != 0x80)     /* Third byte */

      {

      *erroroffset = (int)(p - string) - 2;

      return PCRE_UTF8_ERR7;

      }

    if ((*(++p) & 0xc0) != 0x80)     /* Fourth byte */

      {

      *erroroffset = (int)(p - string) - 3;

      return PCRE_UTF8_ERR8;

      }

    if (c == 0xf0 && (d & 0x30) == 0)

      {

      *erroroffset = (int)(p - string) - 3;

      return PCRE_UTF8_ERR17;

      }

    if (c > 0xf4 || (c == 0xf4 && d > 0x8f))

      {

      *erroroffset = (int)(p - string) - 3;

      return PCRE_UTF8_ERR13;

      }

    break;

    /* 5-byte and 6-byte characters are not allowed by RFC 3629, and will be

    rejected by the length test below. However, we do the appropriate tests

    here so that overlong sequences get diagnosed, and also in case there is

    ever an option for handling these larger code points. */

    /* 5-byte character. Check 3rd, 4th, and 5th bytes for 0x80. Then check for

    1111 1000, xx00 0xxx */

    case 4:

    if ((*(++p) & 0xc0) != 0x80)     /* Third byte */

      {

      *erroroffset = (int)(p - string) - 2;

      return PCRE_UTF8_ERR7;

      }

    if ((*(++p) & 0xc0) != 0x80)     /* Fourth byte */

      {

      *erroroffset = (int)(p - string) - 3;

      return PCRE_UTF8_ERR8;

      }

    if ((*(++p) & 0xc0) != 0x80)     /* Fifth byte */

      {

      *erroroffset = (int)(p - string) - 4;

      return PCRE_UTF8_ERR9;

      }

    if (c == 0xf8 && (d & 0x38) == 0)

      {

      *erroroffset = (int)(p - string) - 4;

      return PCRE_UTF8_ERR18;

      }

    break;

    /* 6-byte character. Check 3rd-6th bytes for 0x80. Then check for

    1111 1100, xx00 00xx. */

    case 5:

    if ((*(++p) & 0xc0) != 0x80)     /* Third byte */

      {

      *erroroffset = (int)(p - string) - 2;

      return PCRE_UTF8_ERR7;

      }

    if ((*(++p) & 0xc0) != 0x80)     /* Fourth byte */

      {

      *erroroffset = (int)(p - string) - 3;

      return PCRE_UTF8_ERR8;

      }

    if ((*(++p) & 0xc0) != 0x80)     /* Fifth byte */

      {

      *erroroffset = (int)(p - string) - 4;

      return PCRE_UTF8_ERR9;

      }

    if ((*(++p) & 0xc0) != 0x80)     /* Sixth byte */

      {

      *erroroffset = (int)(p - string) - 5;

      return PCRE_UTF8_ERR10;

      }

    if (c == 0xfc && (d & 0x3c) == 0)

      {

      *erroroffset = (int)(p - string) - 5;

      return PCRE_UTF8_ERR19;

      }

    break;

    }

  /* Character is valid under RFC 2279, but 4-byte and 5-byte characters are

  excluded by RFC 3629. The pointer p is currently at the last byte of the

  character. */

  if (ab > 3)

    {

    *erroroffset = (int)(p - string) - ab;

    return (ab == 4)? PCRE_UTF8_ERR11 : PCRE_UTF8_ERR12;

    }

  }

#else  /* SUPPORT_UTF */

(void)(string);  /* Keep picky compilers happy */

(void)(length);

#endif

return PCRE_UTF8_ERR0;   /* This indicates success */

}

/* End of pcre_valid_utf8.c */