SimplePie_gzdecode
Decode 'gzip' encoded HTTP data.
Defined (1)
The class is defined in the following location(s).
- /wp-includes/SimplePie/gzdecode.php
- 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;
- }
- }
- }