<?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Symfony\Component\Security\Http\Firewall;

use Symfony\Component\Security\Core\User\UserProviderInterface;
use Symfony\Component\Security\Http\EntryPoint\DigestAuthenticationEntryPoint;
use Psr\Log\LoggerInterface;
use Symfony\Component\HttpKernel\Event\GetResponseEvent;
use Symfony\Component\Security\Core\Authentication\Token\UsernamePasswordToken;
use Symfony\Component\Security\Core\Authentication\Token\Storage\TokenStorageInterface;
use Symfony\Component\Security\Core\Exception\BadCredentialsException;
use Symfony\Component\Security\Core\Exception\AuthenticationServiceException;
use Symfony\Component\Security\Core\Exception\UsernameNotFoundException;
use Symfony\Component\Security\Core\Exception\NonceExpiredException;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\Security\Core\Exception\AuthenticationException;

/**
 * DigestAuthenticationListener implements Digest HTTP authentication.
 *
 * @author Fabien Potencier <fabien@symfony.com>
 */
class DigestAuthenticationListener implements ListenerInterface
{
    private $tokenStorage;
    private $provider;
    private $providerKey;
    private $authenticationEntryPoint;
    private $logger;

    public function __construct(TokenStorageInterface $tokenStorage, UserProviderInterface $provider, $providerKey, DigestAuthenticationEntryPoint $authenticationEntryPoint, LoggerInterface $logger = null)
    {
        if (empty($providerKey)) {
            throw new \InvalidArgumentException('$providerKey must not be empty.');
        }

        $this->tokenStorage = $tokenStorage;
        $this->provider = $provider;
        $this->providerKey = $providerKey;
        $this->authenticationEntryPoint = $authenticationEntryPoint;
        $this->logger = $logger;
    }

    /**
     * Handles digest authentication.
     *
     * @param GetResponseEvent $event A GetResponseEvent instance
     *
     * @throws AuthenticationServiceException
     */
    public function handle(GetResponseEvent $event)
    {
        $request = $event->getRequest();

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

        $digestAuth = new DigestData($header);

        if (null !== $token = $this->tokenStorage->getToken()) {
            if ($token instanceof UsernamePasswordToken && $token->isAuthenticated() && $token->getUsername() === $digestAuth->getUsername()) {
                return;
            }
        }

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

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

            return;
        }

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

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

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

            return;
        }

        if (!hash_equals($serverDigestMd5, $digestAuth->getResponse())) {
            if (null !== $this->logger) {
                $this->logger->debug('Unexpected response from the DigestAuth received; is the header returning a clear text passwords?', array('expected' => $serverDigestMd5, 'received' => $digestAuth->getResponse()));
            }

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

            return;
        }

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

            return;
        }

        if (null !== $this->logger) {
            $this->logger->info('Digest authentication successful.', array('username' => $digestAuth->getUsername(), 'received' => $digestAuth->getResponse()));
        }

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

    private function fail(GetResponseEvent $event, Request $request, AuthenticationException $authException)
    {
        $token = $this->tokenStorage->getToken();
        if ($token instanceof UsernamePasswordToken && $this->providerKey === $token->getProviderKey()) {
            $this->tokenStorage->setToken(null);
        }

        if (null !== $this->logger) {
            $this->logger->info('Digest authentication failed.', array('exception' => $authException));
        }

        $event->setResponse($this->authenticationEntryPoint->start($request, $authException));
    }
}

class DigestData
{
    private $elements = array();
    private $header;
    private $nonceExpiryTime;

    public function __construct($header)
    {
        $this->header = $header;
        preg_match_all('/(\w+)=("((?:[^"\\\\]|\\\\.)+)"|([^\s,$]+))/', $header, $matches, PREG_SET_ORDER);
        foreach ($matches as $match) {
            if (isset($match[1]) && isset($match[3])) {
                $this->elements[$match[1]] = isset($match[4]) ? $match[4] : $match[3];
            }
        }
    }

    public function getResponse()
    {
        return $this->elements['response'];
    }

    public function getUsername()
    {
        return strtr($this->elements['username'], array('\\"' => '"', '\\\\' => '\\'));
    }

    public function validateAndDecode($entryPointKey, $expectedRealm)
    {
        if ($keys = array_diff(array('username', 'realm', 'nonce', 'uri', 'response'), array_keys($this->elements))) {
            throw new BadCredentialsException(sprintf('Missing mandatory digest value; received header "%s" (%s)', $this->header, implode(', ', $keys)));
        }

        if ('auth' === $this->elements['qop'] && !isset($this->elements['nc'], $this->elements['cnonce'])) {
            throw new BadCredentialsException(sprintf('Missing mandatory digest value; received header "%s"', $this->header));
        }

        if ($expectedRealm !== $this->elements['realm']) {
            throw new BadCredentialsException(sprintf('Response realm name "%s" does not match system realm name of "%s".', $this->elements['realm'], $expectedRealm));
        }

        if (false === $nonceAsPlainText = base64_decode($this->elements['nonce'])) {
            throw new BadCredentialsException(sprintf('Nonce is not encoded in Base64; received nonce "%s".', $this->elements['nonce']));
        }

        $nonceTokens = explode(':', $nonceAsPlainText);

        if (2 !== count($nonceTokens)) {
            throw new BadCredentialsException(sprintf('Nonce should have yielded two tokens but was "%s".', $nonceAsPlainText));
        }

        $this->nonceExpiryTime = $nonceTokens[0];

        if (md5($this->nonceExpiryTime.':'.$entryPointKey) !== $nonceTokens[1]) {
            throw new BadCredentialsException(sprintf('Nonce token compromised "%s".', $nonceAsPlainText));
        }
    }

    public function calculateServerDigest($password, $httpMethod)
    {
        $a2Md5 = md5(strtoupper($httpMethod).':'.$this->elements['uri']);
        $a1Md5 = md5($this->elements['username'].':'.$this->elements['realm'].':'.$password);

        $digest = $a1Md5.':'.$this->elements['nonce'];
        if (!isset($this->elements['qop'])) {
        } elseif ('auth' === $this->elements['qop']) {
            $digest .= ':'.$this->elements['nc'].':'.$this->elements['cnonce'].':'.$this->elements['qop'];
        } else {
            throw new \InvalidArgumentException('This method does not support a qop: "%s".', $this->elements['qop']);
        }
        $digest .= ':'.$a2Md5;

        return md5($digest);
    }

    public function isNonceExpired()
    {
        return $this->nonceExpiryTime < microtime(true);
    }
}
