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<?php
/**
* Class HTTP_Encoder
* @package Minify
* @subpackage HTTP
*/
/**
* Encode and send gzipped/deflated content
*
* The "Vary: Accept-Encoding" header is sent. If the client allows encoding,
* Content-Encoding and Content-Length are added.
*
* <code>
* // Send a CSS file, compressed if possible
* $he = new HTTP_Encoder(array(
* 'content' => file_get_contents($cssFile)
* ,'type' => 'text/css'
* ));
* $he->encode();
* $he->sendAll();
* </code>
*
* <code>
* // Shortcut to encoding output
* header('Content-Type: text/css'); // needed if not HTML
* HTTP_Encoder::output($css);
* </code>
*
* <code>
* // Just sniff for the accepted encoding
* $encoding = HTTP_Encoder::getAcceptedEncoding();
* </code>
*
* For more control over headers, use getHeaders() and getData() and send your
* own output.
*
* Note: If you don't need header mgmt, use PHP's native gzencode, gzdeflate,
* and gzcompress functions for gzip, deflate, and compress-encoding
* respectively.
*
* @package Minify
* @subpackage HTTP
* @author Stephen Clay <steve@mrclay.org>
*/
class HTTP_Encoder {
/**
* Should the encoder allow HTTP encoding to IE6?
*
* If you have many IE6 users and the bandwidth savings is worth troubling
* some of them, set this to true.
*
* By default, encoding is only offered to IE7+. When this is true,
* getAcceptedEncoding() will return an encoding for IE6 if its user agent
* string contains "SV1". This has been documented in many places as "safe",
* but there seem to be remaining, intermittent encoding bugs in patched
* IE6 on the wild web.
*
* @var bool
*/
public static $encodeToIe6 = true;
/**
* Default compression level for zlib operations
*
* This level is used if encode() is not given a $compressionLevel
*
* @var int
*/
public static $compressionLevel = 6;
/**
* Get an HTTP Encoder object
*
* @param array $spec options
*
* 'content': (string required) content to be encoded
*
* 'type': (string) if set, the Content-Type header will have this value.
*
* 'method: (string) only set this if you are forcing a particular encoding
* method. If not set, the best method will be chosen by getAcceptedEncoding()
* The available methods are 'gzip', 'deflate', 'compress', and '' (no
* encoding)
*
* @return null
*/
public function __construct($spec)
{
$this->_content = $spec['content'];
$this->_headers['Content-Length'] = (string)strlen($this->_content);
if (isset($spec['type'])) {
$this->_headers['Content-Type'] = $spec['type'];
}
if (isset($spec['method'])
&& in_array($spec['method'], array('gzip', 'deflate', '')))
{
$this->_encodeMethod = array($spec['method'], $spec['method']);
} else {
$this->_encodeMethod = self::getAcceptedEncoding();
}
}
/**
* Get content in current form
*
* Call after encode() for encoded content.
*
* return string
*/
public function getContent()
{
return $this->_content;
}
/**
* Get array of output headers to be sent
*
* E.g.
* <code>
* array(
* 'Content-Length' => '615'
* ,'Content-Encoding' => 'x-gzip'
* ,'Vary' => 'Accept-Encoding'
* )
* </code>
*
* @return array
*/
public function getHeaders()
{
return $this->_headers;
}
/**
* Send output headers
*
* You must call this before headers are sent and it probably cannot be
* used in conjunction with zlib output buffering / mod_gzip. Errors are
* not handled purposefully.
*
* @see getHeaders()
*
* @return null
*/
public function sendHeaders()
{
foreach ($this->_headers as $name => $val) {
header($name . ': ' . $val);
}
}
/**
* Send output headers and content
*
* A shortcut for sendHeaders() and echo getContent()
*
* You must call this before headers are sent and it probably cannot be
* used in conjunction with zlib output buffering / mod_gzip. Errors are
* not handled purposefully.
*
* @return null
*/
public function sendAll()
{
$this->sendHeaders();
echo $this->_content;
}
/**
* Determine the client's best encoding method from the HTTP Accept-Encoding
* header.
*
* If no Accept-Encoding header is set, or the browser is IE before v6 SP2,
* this will return ('', ''), the "identity" encoding.
*
* A syntax-aware scan is done of the Accept-Encoding, so the method must
* be non 0. The methods are favored in order of gzip, deflate, then
* compress. Deflate is always smallest and generally faster, but is
* rarely sent by servers, so client support could be buggier.
*
* @return array two values, 1st is the actual encoding method, 2nd is the
* alias of that method to use in the Content-Encoding header (some browsers
* call gzip "x-gzip" etc.)
*/
public static function getAcceptedEncoding()
{
// @link http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html
if (! isset($_SERVER['HTTP_ACCEPT_ENCODING'])
|| w3_zlib_output_compression()
|| headers_sent()
|| self::_isBuggyIe())
{
return array('', '');
}
if (stristr($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip') && function_exists('gzencode')) {
return array('gzip', 'gzip');
}
return array('', '');
}
/**
* Encode (compress) the content
*
* If the encode method is '' (none) or compression level is 0, or the 'zlib'
* extension isn't loaded, we return false.
*
* Then the appropriate gz_* function is called to compress the content. If
* this fails, false is returned.
*
* The header "Vary: Accept-Encoding" is added. If encoding is successful,
* the Content-Length header is updated, and Content-Encoding is also added.
*
* @param int $compressionLevel given to zlib functions. If not given, the
* class default will be used.
*
* @return bool success true if the content was actually compressed
*/
public function encode($compressionLevel = null)
{
$this->_headers['Vary'] = 'Accept-Encoding';
if (null === $compressionLevel) {
$compressionLevel = self::$compressionLevel;
}
if ('' === $this->_encodeMethod[0]
|| ($compressionLevel == 0)
|| !extension_loaded('zlib'))
{
return false;
}
if ($this->_encodeMethod[0] === 'deflate') {
$encoded = gzdeflate($this->_content, $compressionLevel);
} elseif ($this->_encodeMethod[0] === 'gzip') {
$encoded = gzencode($this->_content, $compressionLevel);
} else {
$encoded = gzcompress($this->_content, $compressionLevel);
}
if (false === $encoded) {
return false;
}
$this->_headers['Content-Length'] = strlen($encoded);
$this->_headers['Content-Encoding'] = $this->_encodeMethod[1];
$this->_content = $encoded;
return true;
}
/**
* Encode and send appropriate headers and content
*
* This is a convenience method for common use of the class
*
* @param string $content
*
* @param int $compressionLevel given to zlib functions. If not given, the
* class default will be used.
*
* @return bool success true if the content was actually compressed
*/
public static function output($content, $compressionLevel = null)
{
if (null === $compressionLevel) {
$compressionLevel = self::$compressionLevel;
}
$he = new HTTP_Encoder(array('content' => $content));
$ret = $he->encode($compressionLevel);
$he->sendAll();
return $ret;
}
protected $_content = '';
protected $_headers = array();
protected $_encodeMethod = array('', '');
/**
* Is the browser an IE version earlier than 6 SP2?
*/
protected static function _isBuggyIe()
{
$ua = $_SERVER['HTTP_USER_AGENT'];
// quick escape for non-IEs
if (0 !== strpos($ua, 'Mozilla/4.0 (compatible; MSIE ')
|| false !== strpos($ua, 'Opera')) {
return false;
}
// no regex = faaast
$version = (float)substr($ua, 30);
return self::$encodeToIe6
? ($version < 6 || ($version == 6 && false === strpos($ua, 'SV1')))
: ($version < 7);
}
}
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