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<?php
/**
* SimplePie
*
* A PHP-Based RSS and Atom Feed Framework.
* Takes the hard work out of managing a complete RSS/Atom solution.
*
* Copyright (c) 2004-2012, Ryan Parman, Geoffrey Sneddon, Ryan McCue, and contributors
* All rights reserved.
*
* 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 SimplePie Team 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 HOLDERS
* AND 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.
*
* @package SimplePie
* @version 1.3.1
* @copyright 2004-2012 Ryan Parman, Geoffrey Sneddon, Ryan McCue
* @author Ryan Parman
* @author Geoffrey Sneddon
* @author Ryan McCue
* @link http://simplepie.org/ SimplePie
* @license http://www.opensource.org/licenses/bsd-license.php BSD License
*/
/**
* Decode 'gzip' encoded HTTP data
*
* @package SimplePie
* @subpackage HTTP
* @link http://www.gzip.org/format.txt
*/
class SimplePie_gzdecode
{
/**
* Compressed data
*
* @access private
* @var string
* @see gzdecode::$data
*/
var $compressed_data;
/**
* Size of compressed data
*
* @access private
* @var int
*/
var $compressed_size;
/**
* Minimum size of a valid gzip string
*
* @access private
* @var int
*/
var $min_compressed_size = 18;
/**
* Current position of pointer
*
* @access private
* @var int
*/
var $position = 0;
/**
* Flags (FLG)
*
* @access private
* @var int
*/
var $flags;
/**
* Uncompressed data
*
* @access public
* @see gzdecode::$compressed_data
* @var string
*/
var $data;
/**
* Modified time
*
* @access public
* @var int
*/
var $MTIME;
/**
* Extra Flags
*
* @access public
* @var int
*/
var $XFL;
/**
* Operating System
*
* @access public
* @var int
*/
var $OS;
/**
* Subfield ID 1
*
* @access public
* @see gzdecode::$extra_field
* @see gzdecode::$SI2
* @var string
*/
var $SI1;
/**
* Subfield ID 2
*
* @access public
* @see gzdecode::$extra_field
* @see gzdecode::$SI1
* @var string
*/
var $SI2;
/**
* Extra field content
*
* @access public
* @see gzdecode::$SI1
* @see gzdecode::$SI2
* @var string
*/
var $extra_field;
/**
* Original filename
*
* @access public
* @var string
*/
var $filename;
/**
* Human readable comment
*
* @access public
* @var string
*/
var $comment;
/**
* Don't allow anything to be set
*
* @param string $name
* @param mixed $value
*/
public function __set($name, $value)
{
trigger_error("Cannot write property $name", E_USER_ERROR);
}
/**
* Set the compressed string and related properties
*
* @param string $data
*/
public function __construct($data)
{
$this->compressed_data = $data;
$this->compressed_size = strlen($data);
}
/**
* Decode the GZIP stream
*
* @return bool Successfulness
*/
public function parse()
{
if ($this->compressed_size >= $this->min_compressed_size)
{
// Check ID1, ID2, and CM
if (substr($this->compressed_data, 0, 3) !== "\x1F\x8B\x08")
{
return false;
}
// Get the FLG (FLaGs)
$this->flags = ord($this->compressed_data[3]);
// FLG bits above (1 << 4) are reserved
if ($this->flags > 0x1F)
{
return false;
}
// Advance the pointer after the above
$this->position += 4;
// MTIME
$mtime = substr($this->compressed_data, $this->position, 4);
// Reverse the string if we're on a big-endian arch because l is the only signed long and is machine endianness
if (current(unpack('S', "\x00\x01")) === 1)
{
$mtime = strrev($mtime);
}
$this->MTIME = current(unpack('l', $mtime));
$this->position += 4;
// Get the XFL (eXtra FLags)
$this->XFL = ord($this->compressed_data[$this->position++]);
// Get the OS (Operating System)
$this->OS = ord($this->compressed_data[$this->position++]);
// Parse the FEXTRA
if ($this->flags & 4)
{
// Read subfield IDs
$this->SI1 = $this->compressed_data[$this->position++];
$this->SI2 = $this->compressed_data[$this->position++];
// SI2 set to zero is reserved for future use
if ($this->SI2 === "\x00")
{
return false;
}
// Get the length of the extra field
$len = current(unpack('v', substr($this->compressed_data, $this->position, 2)));
$this->position += 2;
// Check the length of the string is still valid
$this->min_compressed_size += $len + 4;
if ($this->compressed_size >= $this->min_compressed_size)
{
// Set the extra field to the given data
$this->extra_field = substr($this->compressed_data, $this->position, $len);
$this->position += $len;
}
else
{
return false;
}
}
// Parse the FNAME
if ($this->flags & 8)
{
// Get the length of the filename
$len = strcspn($this->compressed_data, "\x00", $this->position);
// Check the length of the string is still valid
$this->min_compressed_size += $len + 1;
if ($this->compressed_size >= $this->min_compressed_size)
{
// Set the original filename to the given string
$this->filename = substr($this->compressed_data, $this->position, $len);
$this->position += $len + 1;
}
else
{
return false;
}
}
// Parse the FCOMMENT
if ($this->flags & 16)
{
// Get the length of the comment
$len = strcspn($this->compressed_data, "\x00", $this->position);
// Check the length of the string is still valid
$this->min_compressed_size += $len + 1;
if ($this->compressed_size >= $this->min_compressed_size)
{
// Set the original comment to the given string
$this->comment = substr($this->compressed_data, $this->position, $len);
$this->position += $len + 1;
}
else
{
return false;
}
}
// Parse the FHCRC
if ($this->flags & 2)
{
// Check the length of the string is still valid
$this->min_compressed_size += $len + 2;
if ($this->compressed_size >= $this->min_compressed_size)
{
// Read the CRC
$crc = current(unpack('v', substr($this->compressed_data, $this->position, 2)));
// Check the CRC matches
if ((crc32(substr($this->compressed_data, 0, $this->position)) & 0xFFFF) === $crc)
{
$this->position += 2;
}
else
{
return false;
}
}
else
{
return false;
}
}
// Decompress the actual data
if (($this->data = gzinflate(substr($this->compressed_data, $this->position, -8))) === false)
{
return false;
}
else
{
$this->position = $this->compressed_size - 8;
}
// Check CRC of data
$crc = current(unpack('V', substr($this->compressed_data, $this->position, 4)));
$this->position += 4;
/*if (extension_loaded('hash') && sprintf('%u', current(unpack('V', hash('crc32b', $this->data)))) !== sprintf('%u', $crc))
{
return false;
}*/
// Check ISIZE of data
$isize = current(unpack('V', substr($this->compressed_data, $this->position, 4)));
$this->position += 4;
if (sprintf('%u', strlen($this->data) & 0xFFFFFFFF) !== sprintf('%u', $isize))
{
return false;
}
// Wow, against all odds, we've actually got a valid gzip string
return true;
}
else
{
return false;
}
}
}
