<?php

/**
* @version $Id: validation.php,v 1.2 2006/02/26 13:20:44 harryf Exp $
* Tools for validing a UTF-8 string is well formed.
* The Original Code is Mozilla Communicator client code.
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1998
* the Initial Developer. All Rights Reserved.
* Ported to PHP by Henri Sivonen (http://hsivonen.iki.fi)
* Slight modifications to fit with phputf8 library by Harry Fuecks (hfuecks gmail com)
* @see http://lxr.mozilla.org/seamonkey/source/intl/uconv/src/nsUTF8ToUnicode.cpp
* @see http://lxr.mozilla.org/seamonkey/source/intl/uconv/src/nsUnicodeToUTF8.cpp
* @see http://hsivonen.iki.fi/php-utf8/
* @package utf8
* @subpackage validation
*/

/**
* Tests a string as to whether it's valid UTF-8 and supported by the
* Unicode standard
* Note: this function has been modified to simple return true or false
* @author <hsivonen@iki.fi>
* @param string UTF-8 encoded string
* @return boolean true if valid
* @see http://hsivonen.iki.fi/php-utf8/
* @see utf8_compliant
* @package utf8
* @subpackage validation
*/
function utf8_is_valid($str)
{
	$mState = 0;	// Cached expected number of octets after the current octet
					// until the beginning of the next UTF8 character sequence
	$mUcs4  = 0;	// Cached Unicode character
	$mBytes = 1;	// Cached expected number of octets in the current sequence

	$len = strlen($str);

	for($i = 0; $i < $len; $i++)
	{
		$in = ord($str{$i});

		if ( $mState == 0)
		{
			// When mState is zero we expect either a US-ASCII character or a multi-octet sequence.
			if (0 == (0x80 & ($in)))
			{
				$mBytes = 1; // US-ASCII, pass straight through
			}
			else if (0xC0 == (0xE0 & ($in)))
			{
				// First octet of 2 octet sequence
				$mUcs4 = ($in);
				$mUcs4 = ($mUcs4 & 0x1F) << 6;
				$mState = 1;
				$mBytes = 2;
			}
			else if (0xE0 == (0xF0 & ($in)))
			{
				// First octet of 3 octet sequence
				$mUcs4 = ($in);
				$mUcs4 = ($mUcs4 & 0x0F) << 12;
				$mState = 2;
				$mBytes = 3;
			}
			else if (0xF0 == (0xF8 & ($in)))
			{
				// First octet of 4 octet sequence
				$mUcs4 = ($in);
				$mUcs4 = ($mUcs4 & 0x07) << 18;
				$mState = 3;
				$mBytes = 4;
			}
			else if (0xF8 == (0xFC & ($in)))
			{
				/* First octet of 5 octet sequence.
				*
				* This is illegal because the encoded codepoint must be either
				* (a) not the shortest form or
				* (b) outside the Unicode range of 0-0x10FFFF.
				* Rather than trying to resynchronize, we will carry on until the end
				* of the sequence and let the later error handling code catch it.
				*/
				$mUcs4 = ($in);
				$mUcs4 = ($mUcs4 & 0x03) << 24;
				$mState = 4;
				$mBytes = 5;
			}
			else if (0xFC == (0xFE & ($in)))
			{
				// First octet of 6 octet sequence, see comments for 5 octet sequence.
				$mUcs4 = ($in);
				$mUcs4 = ($mUcs4 & 1) << 30;
				$mState = 5;
				$mBytes = 6;
			}
			else
			{
				// Current octet is neither in the US-ASCII range nor a legal first octet of a multi-octet sequence.
				return false;
			}
		}
		else
		{
			// When mState is non-zero, we expect a continuation of the multi-octet sequence
			if (0x80 == (0xC0 & ($in)))
			{
				// Legal continuation.
				$shift = ($mState - 1) * 6;
				$tmp = $in;
				$tmp = ($tmp & 0x0000003F) << $shift;
				$mUcs4 |= $tmp;

				/**
				* End of the multi-octet sequence. mUcs4 now contains the final
				* Unicode codepoint to be output
				*/
				if (0 == --$mState)
				{
					/*
					* Check for illegal sequences and codepoints.
					*/
					// From Unicode 3.1, non-shortest form is illegal
					if (((2 == $mBytes) && ($mUcs4 < 0x0080)) || ((3 == $mBytes) && ($mUcs4 < 0x0800)) ||
					((4 == $mBytes) && ($mUcs4 < 0x10000)) || (4 < $mBytes) ||
					// From Unicode 3.2, surrogate characters are illegal
					(($mUcs4 & 0xFFFFF800) == 0xD800) ||
					// Codepoints outside the Unicode range are illegal
					($mUcs4 > 0x10FFFF))
					{
						return FALSE;
					}

					// Initialize UTF8 cache
					$mState = 0;
					$mUcs4  = 0;
					$mBytes = 1;
				}
			}
			else
			{
				/**
				*((0xC0 & (*in) != 0x80) && (mState != 0))
				* Incomplete multi-octet sequence.
				*/

				return false;
			}
		}
	}

	return true;
}

/**
* Tests whether a string complies as UTF-8. This will be much
* faster than utf8_is_valid, but will pass five and six octet
* UTF-8 sequences, which are not supported by Unicode and
* so cannot be displayed correctly in a browser. In other words
* it is not as strict as utf8_is_valid but it's faster. If you use
* is to validate user input, you place yourself at the risk that
* attackers will be able to inject 5 and 6 byte sequences (which
* may or may not be a significant risk, depending on what you are
* are doing)
* Note: Does not pass five and six octet UTF-8 sequences anymore in
*       in the unit tests.
* @see utf8_is_valid
* @see http://www.php.net/manual/en/reference.pcre.pattern.modifiers.php#54805
* @param string UTF-8 string to check
* @return boolean TRUE if string is valid UTF-8
* @package utf8
* @subpackage validation
*/
function utf8_compliant($str)
{
	if (strlen($str) == 0)
		return true;

	// If even just the first character can be matched, when the /u
	// modifier is used, then it's valid UTF-8. If the UTF-8 is somehow
	// invalid, nothing at all will match, even if the string contains
	// some valid sequences
	return (preg_match('/^.{1}/us', $str, $ar) == 1);
}
