一个获取google chrome扩展crx文件信息的PHP操作类

此类中实现了从crx文件获取扩展的Appid、获取manifest.json文件内容、将crx文件转换为一般zip文件 

代码如下:

<?php
class CrxParserException extends Exception {

}

/**
 * Chrome crx 解析器，用于获取扩展、皮肤ID
 *
 */
class CrxParser {
    const MAX_PUBLIC_KEY_SIZE = 65535;
    const MAX_SIGNATURE_SIZE  = 65535;
    const HEADER_MAGIC_PREFIX = 'Cr24';
    const CURRENT_VERSION     = 2;

    private $fp = null; //文件指针
    private $filename = ''; //文件路径
    private $_header = array(); //crx 文件的头信息

    public function __construct($filename){
        $this->parse($filename);
    }

    /**
     * 获取此应用的ID
     * @return string
     */
    public function getAppid() {
        $hash = hash('sha256',$this->_key);
        $hash = substr($hash,0,32);

        $length = strlen($hash);
        $ascii_0 = ord('0');
        $ascii_9 = ord('9');
        $ascii_a = ord('a');
        $data = '';
        for($i=0;$i<$length;$i++) {
            $c = ord($hash[$i]);

            if($c >= $ascii_0 && $c <= $ascii_9) {
                $d = chr($ascii_a + $c - $ascii_0);
            } else if($c >= $ascii_a && $c < $ascii_a + 6) {
                $d = chr($ascii_a + $c - $ascii_a + 10);
            } else {
                $d = 'a';
            }
            $data .= $d;
        }
        return $data;
    }

    /**
     * 从crx文件中获取manifest.json文件的配置信息
     * @param unknown $zip_file
     * @return mixed[]
     */
    function getConfig($key=null){
        $zip_file=tempnam(dirname($this->filename),'zip');
        $manifest_arr=array();
        if($this->convertToZip($zip_file)){
            $zip=zip_open($zip_file);
            if(is_resource($zip)){
                while($zip_entry=zip_read($zip)){
                    $entry_name=zip_entry_name($zip_entry);
                    if(preg_match('/manifest.json$/', $entry_name)){
                        $content=zip_entry_read($zip_entry, zip_entry_filesize($zip_entry));
                        $content_j=json_decode($content, true);
                        if(!empty($content_j)){
                            $manifest_arr=$content_j;
                        }
                    }
                }
            }
            zip_close($zip);
            unlink($zip_file);
        }
        return is_null($key) ? $manifest_arr : $manifest_arr[$key];
    }

    /**
     * 将文件转换为zip文件
     * @param unknown $target_path
     */
    public function convertToZip($target_path=null){
        $offset=16+$this->_header['key_size']+$this->_header['sig_size'];
        $data=$this->getContent($this->filename,$offset);
        return !is_null($target_path) ? file_put_contents($target_path, $data) : $data;
    }

    /**
     * 开始解析该 crx 文件
     */
    private function parse($filename) {
        if(strpos($filename, '://')!==false && !file_exists($filename)) {
            throw new CrxParserException("parser init: crx file does not exisit");
        }
        $this->filename=$filename;
        $this->fp = fopen($filename, 'r');
        $this->parse_header(); // 解析头部信息
        $this->parse_key();
        $this->parse_sig();
        fclose($this->fp);
    }

    /**
     * 解析头部信息，并设置 $_header 数组
     * @throws CrxParserException 解析错误抛出异常
     */
    private function parse_header() {
        $data = fread($this->fp, 16); // HEADER 头信息有16个字节
        if($data) {
            $data = @unpack('C4prefix/Vversion/Vkey_size/Vsig_size',$data);
        }else{
            throw new CrxParserException("header parse: error reading header");
        }
        // 前四个字节拼合 prefix
        $data['prefix'] = chr( $data['prefix1'] ).chr( $data['prefix2'] ).chr( $data['prefix3'] ).chr( $data['prefix4'] );
        unset($data['prefix1'],$data['prefix2'],$data['prefix3'],$data['prefix4']);

        if($data['prefix'] != self::HEADER_MAGIC_PREFIX) {
            throw new CrxParserException("header parse: illegal prefix");
        }
        if( $data['version'] != self::CURRENT_VERSION ) {
            throw new CrxParserException("header parse: illegal version");
        }
        if(
                empty($data['key_size']) || $data['key_size'] > self::MAX_PUBLIC_KEY_SIZE ||
                empty($data['sig_size']) || $data['sig_size'] > self::MAX_SIGNATURE_SIZE
                ){
                    throw new CrxParserException("header parse: illegal public key size or signature size");
        }
        $this->_header = $data;
    }

    /**
     * 解析key
     * @throws CrxParserException
     */
    private function parse_key() {
        $key = fread($this->fp,$this->_header['key_size']);
        if($key) {
            $this->_key = $key;
        }else{
            throw new CrxParserException("key parse: error reading key");
        }
    }

    /**
     * 解析sig
     * @throws CrxParserException
     */
    private function parse_sig() {
        $sig = fread($this->fp,$this->_header['sig_size']);
        if($sig) {
            $this->_sig = $sig;
        }else{
            throw new CrxParserException("sig parse: error reading sig");
        }
    }

    /**
     * 从文件中获取指定位置及大小的内容
     * @param unknown $filename
     * @param number $offset
     * @param unknown $length
     * @return string
     */
    private function getContent($filename,$offset=0,$length=-1){
        $stream = fopen($filename, 'rb');
        $content = stream_get_contents($stream, $length, $offset);
        fclose($stream);
        return $content;
    }

}

使用方法：

<?php
$crxParser=new CrxParser('abc.crx');
echo $crxParser->getAppid();
var_dump($crxParser->getConfig());
//$crxParser->convertToZip('abc.zip');