class SessionConfiguration

class SessionConfiguration implements SessionConfigurationInterface {
    
    /**
     * An associative array of session ini settings.
     */
    protected $options;
    
    /**
     * Constructs a new session configuration instance.
     *
     * @param array $options
     *   An associative array of session ini settings.
     *
     * @see \Symfony\Component\HttpFoundation\Session\Storage\NativeSessionStorage::__construct()
     * @see http://php.net/manual/session.configuration.php
     * @see https://www.php.net/manual/session.security.ini.php
     */
    public function __construct($options = []) {
        // Provide sensible defaults for sid_length, sid_bits_per_character and
        // name_suffix.
        // @see core/assets/scaffold/files/default.services.yml
        $this->options = $options + [
            'sid_length' => 48,
            'sid_bits_per_character' => 6,
            'name_suffix' => '',
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function hasSession(Request $request) {
        return $request->cookies
            ->has($this->getName($request));
    }
    
    /**
     * {@inheritdoc}
     */
    public function getOptions(Request $request) {
        $options = $this->options;
        // Generate / validate the cookie domain.
        $options['cookie_domain'] = $this->getCookieDomain($request) ?: '';
        // If the site is accessed via SSL, ensure that the session cookie is
        // issued with the secure flag.
        $options['cookie_secure'] = $request->isSecure();
        // Set the session cookie name.
        $options['name'] = $this->getName($request);
        return $options;
    }
    
    /**
     * Returns the session cookie name.
     *
     * @param \Symfony\Component\HttpFoundation\Request $request
     *   The request.
     *
     * @return string
     *   The name of the session cookie.
     */
    protected function getName(Request $request) {
        // To prevent session cookies from being hijacked, a user can configure the
        // SSL version of their website to only transfer session cookies via SSL by
        // using PHP's session.cookie_secure setting. The browser will then use two
        // separate session cookies for the HTTPS and HTTP versions of the site. So
        // we must use different session identifiers for HTTPS and HTTP to prevent a
        // cookie collision.
        $prefix = $request->isSecure() ? 'SSESS' : 'SESS';
        return $prefix . $this->getUnprefixedName($request);
    }
    
    /**
     * Returns the session cookie name without the secure/insecure prefix.
     *
     * @param \Symfony\Component\HttpFoundation\Request $request
     *   The request.
     *
     * @return string
     *   The session name without the prefix (SESS/SSESS).
     */
    protected function getUnprefixedName(Request $request) {
        if ($test_prefix = $this->drupalValidTestUa()) {
            $session_name = $test_prefix;
        }
        elseif (isset($this->options['cookie_domain'])) {
            // If the user specifies the cookie domain, also use it for session name.
            $session_name = $this->options['cookie_domain'];
        }
        else {
            // Otherwise use $base_url as session name, without the protocol
            // to use the same session identifiers across HTTP and HTTPS.
            $session_name = $request->getHost() . $request->getBasePath() . $this->options['name_suffix'];
            // Replace "core" out of session_name so core scripts redirect properly,
            // specifically install.php.
            $session_name = preg_replace('#/core$#', '', $session_name);
        }
        return substr(hash('sha256', $session_name), 0, 32);
    }
    
    /**
     * Return the session cookie domain.
     *
     * The Set-Cookie response header and its domain attribute are defined in RFC
     * 2109, RFC 2965 and RFC 6265 each one superseding the previous version.
     *
     * @see http://tools.ietf.org/html/rfc2109
     * @see http://tools.ietf.org/html/rfc2965
     * @see http://tools.ietf.org/html/rfc6265
     *
     * @param \Symfony\Component\HttpFoundation\Request $request
     *   The request.
     *
     * @return string|null
     *   The session cookie domain, or NULL if the calculated value is invalid.
     */
    protected function getCookieDomain(Request $request) {
        if (isset($this->options['cookie_domain'])) {
            $cookie_domain = $this->options['cookie_domain'];
        }
        else {
            $host = $request->getHost();
            // To maximize compatibility and normalize the behavior across user
            // agents, the cookie domain should start with a dot.
            $cookie_domain = '.' . $host;
        }
        // Cookies for domains without an embedded dot will be rejected by user
        // agents in order to defeat malicious websites attempting to set cookies
        // for top-level domains. Also IP addresses may not be used in the domain
        // attribute of a Set-Cookie header. IPv6 addresses will not pass the first
        // test, so it's acceptable to bias the second test to IPv4.
        if (count(explode('.', $cookie_domain)) > 2 && !is_numeric(str_replace('.', '', $cookie_domain))) {
            return $cookie_domain;
        }
    }
    
    /**
     * Wraps drupal_valid_test_ua().
     *
     * @return string|false
     *   Either the simpletest prefix (the string "simpletest" followed by any
     *   number of digits) or FALSE if the user agent does not contain a valid
     *   HMAC and timestamp.
     */
    protected function drupalValidTestUa() {
        return drupal_valid_test_ua();
    }

}