private static function readDER()

in src/JWT.php [569:599]

• 26 lines of code
• 5 McCabe index (conditional complexity)

    private static function readDER($der, $offset = 0)
    {
        $pos = $offset;
        $size = \strlen($der);
        $constructed = (\ord($der[$pos]) >> 5) & 0x01;
        $type = \ord($der[$pos++]) & 0x1f;

        // Length
        $len = \ord($der[$pos++]);
        if ($len & 0x80) {
            $n = $len & 0x1f;
            $len = 0;
            while ($n-- && $pos < $size) {
                $len = ($len << 8) | \ord($der[$pos++]);
            }
        }

        // Value
        if ($type == self::$asn1BitString) {
            $pos++; // Skip the first contents octet (padding indicator)
            $data = \substr($der, $pos, $len - 1);
            $pos += $len - 1;
        } elseif (!$constructed) {
            $data = \substr($der, $pos, $len);
            $pos += $len;
        } else {
            $data = null;
        }

        return array($pos, $data);
    }