Symfony\Component\HttpKernel\Security\Firewall\DigestAuthenticationListener::handle PHP Method

    public function handle(Event $event)
    {
        $request = $event->get('request');

        if (!$header = $request->server->get('PHP_AUTH_DIGEST')) {
            return;
        }

        if (null !== $token = $this->securityContext->getToken()) {
            if ($token->isImmutable()) {
                return;
            }

            if ($token instanceof UsernamePasswordToken && $token->isAuthenticated() && (string) $token === $username) {
                return;
            }
        }

        if (null !== $this->logger) {
            $this->logger->debug(sprintf('Digest Authorization header received from user agent: %s', $header));
        }

        $digestAuth = new DigestData($header);

        try {
            $digestAuth->validateAndDecode($this->authenticationEntryPoint->getKey(), $this->authenticationEntryPoint->getRealmName());
        } catch (BadCredentialsException $e) {
            $this->fail($request, $e);

            return;
        }

        try {
            $user = $this->provider->loadUserByUsername($digestAuth->getUsername());

            if (null === $user) {
                throw new AuthenticationServiceException('AuthenticationDao returned null, which is an interface contract violation');
            }

            $serverDigestMd5 = $digestAuth->calculateServerDigest($user->getPassword(), $request->getMethod());
        } catch (UsernameNotFoundException $notFound) {
            $this->fail($request, new BadCredentialsException(sprintf('Username %s not found.', $digestAuth->getUsername())));

            return;
        }

        if ($serverDigestMd5 !== $digestAuth->getResponse()) {
            if (null !== $this->logger) {
                $this->logger->debug(sprintf("Expected response: '%s' but received: '%s'; is AuthenticationDao returning clear text passwords?", $serverDigestMd5, $digestAuth->getResponse()));
            }

            $this->fail($request, new BadCredentialsException('Incorrect response'));

            return;
        }

        if ($digestAuth->isNonceExpired()) {
            $this->fail($request, new NonceExpiredException('Nonce has expired/timed out.'));

            return;
        }

        if (null !== $this->logger) {
            $this->logger->debug(sprintf('Authentication success for user "%s" with response "%s"', $digestAuth->getUsername(), $digestAuth->getResponse()));
        }

        $this->securityContext->setToken(new UsernamePasswordToken($user, $user->getPassword()));
    }