function lti_tool_provider_launch in LTI Tool Provider 7

LTI launch.

Implements the [base_url]/lti path which is called to launch the tool from the LMS

• Verifies the request using OAuth and adds the lti context_info to the session
• Authenticates the user, possibly after provisioning the account
• Authorises the user via global role mapping
• If OG is configured a course may be provisioned from the context_info and group roles are mapped
• Finally the destination is calculated and user is redirected there.

Return value

string Page content.

1 string reference to 'lti_tool_provider_launch'

lti_tool_provider_menu in ./lti_tool_provider.module

Implements hook_menu().

File

./lti_tool_provider.operations.inc, line 25

Menu page callbacks for the lti operations launch, return as well as home and info.

Code

function lti_tool_provider_launch() {
  global $user;

  // If not an LTI launch request, then ignore.
  if (!lti_tool_provider_is_basic_lti_request()) {
    drupal_set_message(t('Not a LTI request.'), 'info');
    return t('Error: Not a LTI request.');
  }

  // Insure we have a valid context.
  if (empty($_REQUEST['oauth_consumer_key'])) {
    unset($_SESSION['lti_tool_provider_context_info']);
    drupal_set_message(t('Not a valid LTI context.'), 'info');
    return t('Error: Invalid context. Missing oauth_consumer_key in request.');
  }

  // Begin a new session based on this LTI launch request.
  drupal_session_start();
  $oauth_consumer_key = $_REQUEST["oauth_consumer_key"];

  // Verify the message signature.
  $store = new LTIToolProviderOAuthDataStore();
  $server = new OAuthServer($store);
  $method = new OAuthSignatureMethod_HMAC_SHA1();
  $server
    ->add_signature_method($method);
  $request = OAuthRequest::from_request();
  try {
    $server
      ->verify_request($request);

    // This is a LTI launch request.
  } catch (Exception $e) {
    drupal_set_message(check_plain($e
      ->getMessage()), 'error');
    return t('Error: Invalid context, OAuth failure.');
  }

  // Collect the launch information for later storage in the session.
  $launch_info = $request
    ->get_parameters();
  if (empty($launch_info['context_id'])) {
    if (isset($launch_info['launch_presentation_return_url'])) {
      lti_tool_provider_goto(url($launch_info['launch_presentation_return_url'], array(
        'query' => array(
          'lti_errormsg' => t('Error: Invalid context, No context Id.'),
        ),
      )));
    }
    else {
      return t('Error: Invalid context, No context Id.');
    }
  }
  $consumer = lti_tool_provider_get_consumer_by_key($oauth_consumer_key);
  $launch_info['consumer_id'] = $consumer->lti_tool_provider_consumer_id;
  $launch_info['consumer_domain'] = $consumer->lti_tool_provider_consumer_domain;
  if (!empty($launch_info['user_id'])) {
    $lti_user = $launch_info['user_id'] . $launch_info['consumer_domain'];
  }
  else {
    $lti_user = 'lti_user' . $launch_info['consumer_domain'];
  }

  // Revalidate incoming user.
  if ($user->uid > 0 && $user->name != $lti_user) {

    // Log out prior user and clear session, retaining lti session variables.
    watchdog('user', 'Session closed for %name.', array(
      '%name' => $user->name,
    ));
    module_invoke_all('user_logout', $user);

    // Destroy the current session, and reset $user to the anonymous user.
    session_destroy();
    drupal_session_start();
    drupal_set_message(t('Logged current user out.'), 'info');
  }
  if ($user->uid == 0) {

    // If no mail address given, Form a dummy mail address.
    if (empty($launch_info['lis_person_contact_email_primary'])) {
      if ($launch_info['consumer_domain'] == '') {
        $launch_info['lis_person_contact_email_primary'] = $lti_user . '@invalid';
      }
      else {
        $launch_info['lis_person_contact_email_primary'] = $lti_user . '.invalid';
      }
    }

    // Unauthenticated so create user if necessary.
    if (($account = user_load_by_name($lti_user)) || ($account = user_load_by_mail($launch_info['lis_person_contact_email_primary']))) {

      // User exists by name or mail.
      if ($account->uid == 1) {

        // User 1 must use drupal authentication.
        if (isset($launch_info['launch_presentation_return_url'])) {
          lti_tool_provider_goto(url($launch_info['launch_presentation_return_url'], array(
            'query' => array(
              'lti_errormsg' => t('Admin account must use Drupal authentication.'),
            ),
          )));
        }
        else {
          drupal_set_message(t('Admin account must use Drupal authentication.'), 'error');
          return t('Admin account must use Drupal authentication.');
        }
      }
    }
    else {
      if (!($account = lti_tool_provider_create_account($lti_user, $launch_info))) {
        if (isset($launch_info['launch_presentation_return_url'])) {
          lti_tool_provider_goto(url($launch_info['launch_presentation_return_url'], array(
            'query' => array(
              'lti_errormsg' => t('Account creation failed.'),
            ),
          )));
        }
        else {
          drupal_set_message(t('Account creation failed.'), 'error');
          return t('Account creation failed.');
        }
      }
    }

    // Log the user in.
    $form_state = array(
      'uid' => $account->uid,
    );
    user_login_submit(array(), $form_state);
  }
  else {
    $account = user_load($user->uid);
  }

  // $account is the $lti_user.
  // Map Drupal global roles based on the user LTI role.
  if (!empty($launch_info['roles'])) {
    lti_tool_provider_assign_global_roles_to_user($launch_info['roles'], $account->uid);
    drupal_static_reset('user_access');
  }
  $launch_info['destination'] = '';
  drupal_alter('lti_tool_provider_launch', $launch_info, $account);

  // Calculate the final destination.
  if (!empty($launch_info['custom_destination'])) {
    $launch_info['destination'] .= '/' . $launch_info['custom_destination'];
  }

  // Save launch information in session.
  $_SESSION['lti_tool_provider_context_info'] = $launch_info;

  // Set language in session.
  if (!empty($launch_info['launch_presentation_locale'])) {
    $_SESSION['language'] = drupal_strtolower($launch_info['launch_presentation_locale']);
  }
  lti_tool_provider_goto($launch_info['destination']);
}