Airship\Engine\Security\Util::downloadFileType PHP Méthode

    public static function downloadFileType(string $mimeType, string $default = 'text/plain', array $badSubstrings = self::DEFAULT_MIME_BLOCK) : string
    {
        $block = false;
        foreach ($badSubstrings as $str) {
            $block = $block || \strpos($mimeType, $str) !== false;
        }
        if ($block) {
            $p = \strpos($mimeType, ';');
            if ($p !== false) {
                return self::charWhitelist($default, self::MIME_CHARS) . '; ' . self::charWhitelist(self::subString($mimeType, $p), self::MIME_CHARS);
            }
            return $default;
        }
        // Not a blocked MIME type, but we should still filter it
        // to prevent CRLF injections, etc. A character whitelist
        // is better than a blacklist.
        $p = \strpos($mimeType, ';');
        if ($p !== false) {
            return self::charWhitelist(self::subString($mimeType, 0, $p - 1), self::MIME_CHARS) . '; ' . self::charWhitelist(self::subString($mimeType, $p), self::MIME_CHARS);
        }
        return self::charWhitelist($mimeType, self::MIME_CHARS);
    }

 /**
  * @covers Util::downloadFileType()
  */
 public function testDownloadFileType()
 {
     $vectors = [['in' => 'text/javascript', 'out' => 'text/plain'], ['in' => 'image/png', 'out' => 'image/png'], ['in' => 'application/javascript', 'out' => 'text/plain'], ['in' => 'text/html', 'out' => 'text/plain'], ['in' => 'text/html; charset=UTF-8', 'out' => 'text/plain; charset=UTF-8']];
     foreach ($vectors as $test) {
         $this->assertSame($test['out'], Util::downloadFileType($test['in']));
     }
 }