Create .CRX (chrome extension / webapp ) file on demand using PHP

Question

I need to create CRX file on the fly. It's for my CMS backend, so it will be just for authenticated users who can install CMS backend as webapp and offer some more privileges to the web app. The problem is, that the backend is used for many domains so creating CRX file for each of them is quite a work. So I figured that it would be easier to just create CRX file on demand which would be generated by PHP using its own domain and probably custom icon.

Answer 1

On the documentation page, they explain the CRX package format. There are many third party libraries that implemented that format. In the following page, you can learn the format and either download a Ruby / Bash script (you can find others too online), and if you want to implement your own packager, you can follow the format described there.

https://developer.chrome.com/extensions/crx

If you really don't want to follow the format, you can let your PHP script do one of the following:

1. Use Chrome binary chrome.exe --pack-extension=c:\myext --pack-extension-key=c:\myext.pem
2. Use the Ruby or Bash script from PHP (you can call system commands)

Hope that helps!

Answer 2

This works for me :D I just change from real path to null without that changes won't work on new chrome :D

/** * Class CrxGenerator * * Create Chrome Extension CRX packages from * folder & pem private key * * Based on CRX format documentation: http://developer.chrome.com/extensions/crx.html * * @author: Tomasz Banasiak * @license: MIT * @date: 2013-11-03 */

class CrxGenerator { const TEMP_ARCHIVE_EXT = '.zip';

private $sourceDir = null;
private $cacheDir = '';

private $privateKeyContents = null;
private $publicKeyContents = null;

private $privateKey = null;
private $publicKey = null;

/**
 * @param $file Path to PEM key
 * @throws Exception
 */
public function setPrivateKey($file) {
    if (!file_exists($file)) {
        throw new Exception('Private key file does not exist');
    }

    $this->privateKeyContents = file_get_contents($file);
    $this->privateKey = $file;
}

/**
 * @param $file Path to PUB key
 * @throws Exception
 */
public function setPublicKey($file) {
    if (!file_exists($file)) {
        throw new Exception('Private key file does not exist');
    }

    $this->publicKeyContents = file_get_contents($file);
    $this->publicKey = $file;
}

/**
 * @param $cacheDir dir specified for caching temporary archives
 * @throws Exception
 */
public function setCacheDir($cacheDir) {
    if (!is_dir($cacheDir)) {
        throw new Exception('Cache dir does not exist!');
    }

    $this->cacheDir = $cacheDir;
}

/**
 * @param $sourceDir Extension source directory
 */
public function setSourceDir($sourceDir) {
    $this->sourceDir = $sourceDir;
}

/**
 * @param $outputFile path to output file
 * @throws Exception
 */
public function generateCrx($outputFile) {
    $basename = basename($outputFile);
    // First step - create ZIP archive
    $zipArchive = $this->cacheDir . DIRECTORY_SEPARATOR . $basename . self::TEMP_ARCHIVE_EXT;

    $result = $this->createZipArchive(
        $this->sourceDir,
        $zipArchive
    );

    if (!$result) {
        throw new Exception('ZIP creation failed');
    }

    $zipContents = file_get_contents($zipArchive);

    // Second step - create file signature
    $privateKey = openssl_pkey_get_private($this->privateKeyContents);
    openssl_sign($zipContents, $signature, $privateKey, 'sha1');
    openssl_free_key($privateKey);

    // Create output file

    $crx = fopen($outputFile, 'wb');
    fwrite($crx, 'Cr24');
    fwrite($crx, pack('V', 2));
    fwrite($crx, pack('V', strlen($this->publicKeyContents)));
    fwrite($crx, pack('V', strlen($signature)));
    fwrite($crx, $this->publicKeyContents);
    fwrite($crx, $signature);
    fwrite($crx, $zipContents);
    fclose($crx);

    // Clear cache
    unset($zipArchive);
}

/**
 * @param $source - source dir
 * @param $outputFile - output file
 * @return bool - success?
 */
private function createZipArchive($source, $outputFile) {
    if (!extension_loaded('zip') || !file_exists($source)) {
        return false;
    }

    $zip = new ZipArchive();
    if (!$zip->open($outputFile, ZIPARCHIVE::CREATE)) {
        return false;
    }

     $source = str_replace('\\', '/', realpath($source));

    if (is_dir($source) === true) {
        $files = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($source), RecursiveIteratorIterator::SELF_FIRST);
        foreach ($files as $file) {
            $file = str_replace('\\', '/', $file);

            // Exclude "." and ".." folders
            if( in_array(substr($file, strrpos($file, '/') + 1), array('.', '..')) ) {
                continue;
            }

            $file = $file;

            if (is_dir($file) === true) {
                $zip->addEmptyDir(str_replace($source . '/', '', $file . '/'));
            }
            else if (is_file($file) === true) {
                $zip->addFromString(str_replace($source . '/', '', $file), file_get_contents($file));
            }
        }
    }
    else if (is_file($source) === true) {
        $zip->file_get_contents($source);
    echo  $source;
    }

    return $zip->close();
}

}

Answer 3

Also, for anyone still looking for a way to create a CTX in PHP, look at this question: Create Google Chrome Crx file with PHP

Answer 4

Looks like I have found exactly what I was looking for. Chrome team has made this option to create CRX-less web apps, just by using simple manifest file.

Much easier to create own webapp and publish it on website for installation. And it also solves my problem when I have many websites with a lot of domains and I don't have to create custom CRX file for each domain. I just create small PHP script which creates manifest files on the fly for each domain.