raven.module

<?php

require_once dirname(__FILE__) . '/raven.service.inc';

/**
 * Implements hook_help().
 */
function raven_help($path, $arg) {
  global $user;

  $output = '';

  switch ($path) {
    case 'admin/config/people/raven':
      $output .= '<p>' . t('Raven users are able to log in to the site. If an account does not already exist, one is created.') . '</p>';
      break;
    case 'admin/help#raven':
      $output .= '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('The Raven authentication module allows users to log in using <a href="@raven_url">Raven</a>, the University of Cambridge\'s central web authentication service. It can replace, or co-exist with, the standard Drupal authentication method.', array('@raven_url' => 'http://raven.cam.ac.uk/')) . '</p>';

      $output .= '<h3>' . t('Users') . '</h3>';
      $output .= '<dl>';

      $output .= '<dt>' . t('Creating Raven users') . '</dt>';
      $output .= '<dd>' . t('Users who log in with Raven create a new account automatically if one does not already exist, assuming your site allows visitors to create accounts.') . '</dd>';

      $output .= '<dt>' . t('Editing Raven users') . '</dt>';
      $output .= '<dd>' . t('On the <a href="@user_edit_path">user edit page</a> the username field is replaced with a disabled CRSid field for users who have logged in with Raven. The password area is also hidden.', array('@user_edit_path' => url('user/' . $user->uid . '/edit'))) . '</dd>';

      $user1 = user_load(1);
      $output .= '<dt>' . t('Disable non-Raven users') . '</dt>';
      $output .= '<dd>' . t('The standard user login paths can be overridden in the <a href="@raven_config_path">Raven administration page</a>, so all users must log in using Raven.', array('@raven_config_path' => url('admin/config/people/raven'))) . '</dd>';
      $output .= '<dd>' . t('Site-created users such as \'@user1\' will not be able to log in, unless the backdoor login path is enabled. <i>Disabling this without having an administrator able to log in via Raven will lock you out of your site.</i>', array(
        '@user1' => $user1 ? $user1->name : 'admin',
        // user 1 should always exist, but just in case
      )) . '</dd>';

      $output .= '</dl>';
      break;
  }

  return $output;
}

/**
 * Implements hook_menu();
 */
function raven_menu() {
  $items = array();

  $items['raven/login'] = array(
    'title' => 'Raven log in',
    'access callback' => 'user_is_anonymous',
    'page callback' => 'raven_login',
    'type' => MENU_CALLBACK,
  );

  $items['admin/config/people/raven'] = array(
    'title' => 'Raven authentication',
    'description' => 'Settings to configure logging in with Raven',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('raven_settings_form'),
    'access arguments' => array('administer raven authentication'),
    'file' => 'raven.admin.inc',
  );

  $items['user/backdoor/login'] = array(
    'title' => 'Non-Raven backdoor login',
    'access callback' => 'raven_backdoor_login_is_enabled',
    'page callback' => 'raven_backdoor_login',
    'type' => MENU_CALLBACK,
  );

  return $items;
}

/**
 * Implements hook_permission().
 */
function raven_permission() {
  $permissions['administer raven authentication'] = array(
    'title' => t('Administer Raven authentication configuration.'),
    'restrict access' => TRUE,
  );
  return $permissions;
}

/**
 * Implements hook_menu_site_status_alter().
 *
 * Makes the Raven login pages available if the site is in maintenance mode.
 */
function raven_menu_site_status_alter(&$menu_site_status, $path) {
  if (
    $menu_site_status === MENU_SITE_OFFLINE &&
    user_is_anonymous() &&
    ($path === 'raven/login' || ($path === 'user/backdoor/login' && raven_backdoor_login_is_enabled()))
  ) {
    $menu_site_status = MENU_SITE_ONLINE;
  }
}

/**
 * Is non-Raven backdoor login enabled?
 *
 * @return bool
 *   TRUE if enable, FALSE otherwise
 */
function raven_backdoor_login_is_enabled() {
  return (bool) ((variable_get('raven_login_override', FALSE) == TRUE) * (variable_get('raven_backdoor_login', TRUE) == TRUE));
}

/**
 * Provides a backdoor for logging in without Raven.
 *
 * This means that site-created accounts (eg the original administrator account) can still access the site.
 *
 * If the user is already logged in, they are redirected to their profile page.
 */
function raven_backdoor_login() {
  global $user;

  if ($user->uid) {
    // User is already logged in
    drupal_goto('user/' . $user->uid);
  }

  return drupal_get_form('user_login');
}

/**
 * Send the user to the Raven login page.
 *
 * @param string|null $redirect
 *   Path to redirect to. If null, the HTTP_REFERER header is used. If that's not set, the front page is used.
 */
function raven_login($redirect = NULL) {
  global $base_url;

  if ($redirect === NULL) {
    if (isset($_GET['destination']) && FALSE === url_is_external($_GET['destination'])) {
      $redirect = $_GET['destination'];
    }
    elseif (NULL != $_SERVER['HTTP_REFERER']) {
      $redirect = rawurldecode($_SERVER['HTTP_REFERER']);
    }
    else {
      $redirect = $base_url . '/';
    }
  }

  $website_description = variable_get('raven_website_description');

  $params['ver'] = '3';
  $params['url'] = $base_url . '/';
  $params['desc'] = !empty($website_description) ? $website_description : variable_get('site_name', $base_url);
  // The options passed to drupal_goto() must not be URI-encoded because they ultimately get passed to drupal_encode_path()
  $params['params'] = rawurldecode(url($redirect, array('absolute' => TRUE, 'language' => (object) array('language' => FALSE))));

  // Remove any messages (such as 'You need to log in') to stop them appearing on the next page.
  drupal_get_messages();

  unset($_GET['destination']);
  drupal_goto(get_raven_url(), array('query' => $params), 303);
}

/**
 * Main authentication function.
 *
 * Get the returned details from Raven and decide whether to log in the user.
 *
 * Failed attempts send the user to the login failure redirect path and logs the problem.
 */
function raven_auth() {
  global $base_url;

  if (FALSE === isset($_REQUEST['WLS-Response'])) {
    drupal_goto(variable_get('raven_login_fail_redirect'));
  }

  // Parse Raven Reply
  $parts = explode('!', $_REQUEST['WLS-Response']);

  $r_ver = array_shift($parts);
  $versions = array('1' => 12, '2' => 12, '3' => 13);

  if (FALSE === in_array($r_ver, array('1', '2', '3'), TRUE) || count($parts) <> $versions[$r_ver]) {
    drupal_set_message(t('Suspicious login attempt denied and logged.'), 'error');
    watchdog('raven', 'Suspicious login attempt. Raven response is not acceptable (@wls_response).', array('@wls_response' => $_REQUEST['WLS-Response']), WATCHDOG_ALERT);
    drupal_goto(variable_get('raven_login_fail_redirect'));
  }

  $r_sig = array_pop($parts);
  $r_kid = array_pop($parts);

  if ($r_ver >= 3) {
    list($r_status, $r_msg, $r_issue, $r_id, $r_url, $r_principal, $r_ptags, $r_auth, $r_sso, $r_life, $r_params) = $parts;
  }
  else {
    list($r_status, $r_msg, $r_issue, $r_id, $r_url, $r_principal, $r_auth, $r_sso, $r_life, $r_params) = $parts;
  }

  array_unshift($parts, $r_ver);

  if (($r_status === '200') && (raven_signature_check(implode('!', $parts), $r_sig) === TRUE)) {
    // Timeout check
    if ((time() - strtotime($r_issue)) > 30) {
      drupal_set_message(t('Login attempt timed out.'), 'error');
      watchdog('raven', 'Timeout on login attempt for @raven_id', array('@raven_id' => $r_principal), WATCHDOG_WARNING);
      drupal_goto(variable_get('raven_login_fail_redirect'));
    }

    // 'kid' check
    if ($r_kid !== get_raven_kid()) {
      drupal_set_message(t('Suspicious login attempt denied and logged.'), 'error');
      watchdog('raven', 'Suspicious login attempt claiming to be @raven_id. \'kid\' validation failed: expecting \'@expected\', got \'@given\'.', array(
        '@raven_id' => $r_principal,
        '@expected' => get_raven_kid(),
        '@given' => $r_kid,
      ), WATCHDOG_ALERT);
      drupal_goto(variable_get('raven_login_fail_redirect'));
    }

    // Valid path check
    if ($r_url !== $base_url . '/') {
      drupal_set_message(t('Suspicious login attempt denied and logged.'), 'error');
      watchdog('raven', 'Suspicious login attempt claiming to be @raven_id. \'url\' validation failed: expecting \'@expected\', got \'@given\'.', array(
        '@raven_id' => $r_principal,
        '@expected' => $base_url . '/',
        '@given' => $r_url,
      ), WATCHDOG_ALERT);
      drupal_goto(variable_get('raven_login_fail_redirect'));
    }

    // 'auth' check
    if ($r_auth !== 'pwd' && $r_auth !== '') {
      drupal_set_message(t('Suspicious login attempt denied and logged.'), 'error');
      watchdog('raven', 'Suspicious login attempt claiming to be @raven_id. \'auth\' validation failed: expecting \'@expected\', got \'@given\'.', array(
        '@raven_id' => $r_principal,
        '@expected' => 'pwd',
        '@given' => $r_auth,
      ), WATCHDOG_ALERT);
      drupal_goto(variable_get('raven_login_fail_redirect'));
    }

    // 'sso' check
    if ($r_sso !== 'pwd' && $r_auth === '') {
      drupal_set_message(t('Suspicious login attempt denied and logged.'), 'error');
      watchdog('raven', 'Suspicious login attempt claiming to be @raven_id. \'sso\' validation failed: expecting \'@expected\', got \'@given\'.', array(
        '@raven_id' => $r_principal,
        '@expected' => 'pwd',
        '@given' => $r_sso,
      ), WATCHDOG_ALERT);
      drupal_goto(variable_get('raven_login_fail_redirect'));
    }

    // Raven for Life check
    if (isset($r_ptags) && $r_ptags !== 'current' && variable_get('raven_allow_raven_for_life', FALSE) != TRUE) {
      drupal_set_message(t('Raven for Life accounts are not allowed to access the site.'), 'error');
      watchdog('raven', 'Raven for Life account @raven_id denied access.', array('@raven_id' => $r_principal), WATCHDOG_INFO);
      drupal_goto(variable_get('raven_login_fail_redirect'));
    }

    // Successful login
    user_raven_login_register($r_principal);
    drupal_goto(urldecode($r_params));
  }
  elseif ($r_status === '410') {
    watchdog('raven', 'Raven authentication cancelled.', array(), WATCHDOG_INFO);
    drupal_set_message(t('Raven authentication cancelled.'));
    drupal_goto(variable_get('raven_login_fail_redirect'));
  }
  else {
    watchdog('raven', 'Authentication failure: @message.', array('@message' => raven_response_status_name($r_status)), WATCHDOG_ERROR);
    drupal_set_message(t('Raven authentication failure.'), 'error');
    drupal_goto(variable_get('raven_login_fail_redirect'));
  }
}

/**
 * Get Raven response status name.
 *
 * @param int $code
 *   Response status code.
 *
 * @return string
 *   Response status name.
 */
function raven_response_status_name($code) {
  switch ($code) {
    case 200:
      return 'Successful authentication';
    case 410:
      return 'The user cancelled the authentication request';
    case 510:
      return 'No mutually acceptable authentication types available';
    case 520:
      return 'Unsupported protocol version';
    case 530:
      return 'General request parameter error';
    case 540:
      return 'Interaction would be required';
    case 560:
      return 'WAA not authorised';
    case 570:
      return 'Authentication declined';
    default:
      return 'Unknown status code';
  }
}

/**
 * Implements hook_url_outbound_alter().
 */
function raven_url_outbound_alter(&$path, &$options, $original_path) {
  if (variable_get('raven_login_override', FALSE)) {
    if ('user/login' === $path) {
      $path = 'raven/login';
    }
  }
}

/**
 * Implements hook_init().
 */
function raven_init() {
  global $user;

  // prevent normal login pages if needed
  if (variable_get('raven_login_override', FALSE)) {
    switch (strtolower(current_path())) {
      case 'user':
        if (!$user->uid) {
          raven_login('user');
        }
        break;
      case 'user/login':
      case 'user/register':
        if (!$user->uid) {
          raven_login();
        }
        break;
      case 'user/password':
        if ($user->uid) {
          drupal_goto('user');
        }
        else {
          drupal_access_denied();
        }
        break;
    }
  }

  if (isset($_REQUEST['WLS-Response'])) {
    raven_auth();
  }
}

/**
 * Check Raven signature.
 *
 * @param string $data
 *   Data to check.
 * @param string $sig
 *   Signature to check against.
 *
 * @return bool
 *   TRUE if successful, FALSE otherwise.
 */
function raven_signature_check($data, $sig) {
  $key = openssl_pkey_get_public(get_raven_pubkey());
  $result = openssl_verify(rawurldecode($data), raven_signature_decode(rawurldecode($sig)), $key);
  openssl_free_key($key);
  switch ($result) {
    case 1:
      return TRUE;
      break;
    case 0:
      return FALSE;
      break;
    default:
      watchdog('raven', 'OpenSSL error.', array(), WATCHDOG_ERROR);
      drupal_set_message(t('Error authenticating.'), 'error');
      return FALSE;
      break;
  }
}

/**
 * Decode Raven signature.
 *
 * @param string $str
 *   Signature to decode.
 *
 * @return string|bool
 *   Decoded signature string on success, FALSE otherwise.
 */
function raven_signature_decode($str) {
  $result = preg_replace(array(
    '/-/',
    '/\./',
    '/_/',
  ), array(
    '+',
    '/',
    '=',
  ), $str);
  $result = base64_decode($result);
  return $result;
}

/**
 * Implements hook_form_FORM_ID_alter() for user_profile_form().
 *
 * Changes the user profile from for Raven users (eg the username field is labelled as CRSid).
 */
function raven_form_user_profile_form_alter(&$form, &$form_state, $form_id) {
  // If this is a Raven user
  if (is_raven_user($form['#user'])) {
    // Change the username so that it's an unalterable CRSid
    $form['account']['name']['#title'] = 'CRSid';
    $form['account']['name']['#description'] = 'University of Cambridge CRSid.';
    $form['account']['name']['#attributes']['disabled'] = 'disabled';

    // Hide the password fields
    if (isset($form['account']['pass'])) {
      $form['account']['pass']['#access'] = FALSE;
    }
    if (isset($form['account']['current_pass'])) {
      $form['account']['current_pass']['#access'] = FALSE;
    }
  }
}

/**
 * Implements hook_form_alter().
 *
 * Adds a 'log in with Raven' link to relevant pages.
 */
function raven_form_alter(&$form, $form_state, $form_id) {
  switch ($form_id) {
    case 'user_login':
    case 'user_register_form':
      if (current_path() !== 'user/backdoor/login' && strncmp(current_path(), 'admin', 5)) {
        $form['raven_message'] = array(
          '#markup' => '<div class="messages">' . t('Have a Raven account? You can <a href="@raven_login_path">log in with Raven</a> instead.', array('@raven_login_path' => url('raven/login'))) . '</div>',
          '#weight' => -100,
        );
      }
      break;
    case 'user_login_block':
      $form['raven_message'] = array(
        '#markup' => '<p>' . t('Have a Raven account? You can <a href="@raven_login_path">log in with Raven</a> instead.', array('@raven_login_path' => url('raven/login'))) . '</p>',
        '#weight' => -100,
      );
      break;
  }
}

/**
 * Implements hook_block_view_alter().
 */
function raven_block_view_alter(&$data, $block) {
  global $user;

  if ($user->uid) {
    return;
  }

  if ($block->delta === 'login' && variable_get('raven_login_override', FALSE) == TRUE) {
    $data['content'] = '<ul><li>' . t('<a href="@raven_login_path">Log in with Raven</a>', array('@raven_login_path' => url('raven/login'))) . '</li></ul>';
  }
}

/**
 * Implements hook_block_list_alter().
 */
function raven_block_list_alter(&$blocks) {
  if(raven_backdoor_login_is_enabled() === TRUE && current_path() === 'user/backdoor/login') {
    foreach($blocks as $key => $block) {
      if($block->module === 'user' && $block->delta === 'login') {
        unset($blocks[$key]);
      }
    }
  }
}

/**
 * Is this a Raven user?
 *
 * @param StdClass $account
 *   User account.
 *
 * @return bool
 *   TRUE if is a Raven user, FALSE if not.
 */
function is_raven_user(StdClass $account) {
  if (isset($account->is_raven_user) === FALSE) {
    $authmaps = user_get_authmaps($account->name);
    $account->is_raven_user = isset($authmaps['raven']);
  }
  return $account->is_raven_user;
}

/**
 * Logs in or register the user following Raven authentication.
 *
 * The global $user object is populated and login tasks are performed.
 *
 * @param string $name
 *   Username, which is the CRSid.
 *
 * @see hook_raven_register_alter()
 * @see hook_raven_migrate_alter()
 * @see hook_raven_login_alter()
 */
function user_raven_login_register($name) {
  $edit = array();
  $account = user_external_load($name);

  if (variable_get('raven_logout_on_browser_close', TRUE) == TRUE) {
    ini_set('session.cookie_lifetime', 0);
  }

  if ($account === FALSE) {
    // User hasn't logged in with Raven before
    $account = user_load_by_name($name);
    if ($account === FALSE) {
      // User does not exist yet
      // Check if overriding admin approval is set
      if (variable_get('raven_override_administrator_approval', FALSE)) {
        $status = 1;
      }
      else {
        switch (variable_get('user_register')) {
          case USER_REGISTER_ADMINISTRATORS_ONLY:
            drupal_set_message(t('Only site administrators can create accounts.'), 'error');
            unset($_GET['destination']);
            drupal_goto(variable_get('raven_login_fail_redirect'));
            break;
          case USER_REGISTER_VISITORS_ADMINISTRATIVE_APPROVAL:
            drupal_set_message(t('Thank you for applying for an account. Your account is currently pending approval by the site administrator.'));
            $status = 0;
            break;
          default:
            $status = 1;
            break;
        }
      }
      $account = drupal_anonymous_user();
      $account->is_raven_user = TRUE;
      $edit = array(
        'name' => $name,
        'pass' => user_password(),
        'init' => $name . '@cam.ac.uk',
        'mail' => $name . '@cam.ac.uk',
        'status' => $status,
        'access' => REQUEST_TIME,
      );
      drupal_alter('raven_register', $edit, $account);
      watchdog('raven', 'New user: @name (@email).', array(
        '@name' => $edit['name'],
        '@email' => $edit['mail'],
        WATCHDOG_NOTICE,
        l(t('edit'), 'user/' . $account->uid . '/edit')
      ));
    }
    else {
      $account->is_raven_user = TRUE;
      drupal_alter('raven_migrate', $edit, $account);
      watchdog('raven', 'Migrated user: @name (@email).', array(
        '@name' => $account->name,
        '@email' => isset($edit['mail']) ? $edit['mail'] : $account->mail,
        WATCHDOG_NOTICE,
        l(t('edit'), 'user/' . $account->uid . '/edit')
      ));
    }
  }
  else {
    $account->is_raven_user = TRUE;
    drupal_alter('raven_login', $edit, $account);
  }

  $account = user_save($account, $edit);

  if (FALSE === $account) {
    drupal_set_message(t('Error saving user account.'), 'error');
  }
  elseif (FALSE === isset($status) && user_is_blocked($account->name)) {
    drupal_set_message(t('The username @name is blocked.', array('@name' => $account->name)), 'error');
  }
  else {
    user_set_authmaps($account, array('authname_raven' => $name));

    // Log user in
    $form_state['uid'] = $account->uid;
    user_login_submit(array(), $form_state);
  }

  global $user;

  if (!$user->uid || $user->status == 0) {
    unset($_GET['destination']);
    drupal_goto(variable_get('raven_login_fail_redirect'));
  }
}