<?php

/**

 * @file

 * User session handling functions.

 *

 * The user-level session storage handlers:

 * - _drupal_session_open()

 * - _drupal_session_close()

 * - _drupal_session_read()

 * - _drupal_session_write()

 * - _drupal_session_destroy()

 * - _drupal_session_garbage_collection()

 * are assigned by session_set_save_handler() in bootstrap.inc and are called

 * automatically by PHP. These functions should not be called directly. Session

 * data should instead be accessed via the $_SESSION superglobal.

 */

/**

 * Session handler assigned by session_set_save_handler().

 *

 * This function is used to handle any initialization, such as file paths or

 * database connections, that is needed before accessing session data. Drupal

 * does not need to initialize anything in this function.

 *

 * This function should not be called directly.

 *

 * @return

 *   This function will always return TRUE.

 */

function _drupal_session_open() {

  return TRUE;

}

/**

 * Session handler assigned by session_set_save_handler().

 *

 * This function is used to close the current session. Because Drupal stores

 * session data in the database immediately on write, this function does

 * not need to do anything.

 *

 * This function should not be called directly.

 *

 * @return

 *   This function will always return TRUE.

 */

function _drupal_session_close() {

  return TRUE;

}

/**

 * Reads an entire session from the database (internal use only).

 *

 * Also initializes the $user object for the user associated with the session.

 * This function is registered with session_set_save_handler() to support

 * database-backed sessions. It is called on every page load when PHP sets

 * up the $_SESSION superglobal.

 *

 * This function is an internal function and must not be called directly.

 * Doing so may result in logging out the current user, corrupting session data

 * or other unexpected behavior. Session data must always be accessed via the

 * $_SESSION superglobal.

 *

 * @param $sid

 *   The session ID of the session to retrieve.

 *

 * @return

 *   The user's session, or an empty string if no session exists.

 */

function _drupal_session_read($sid) {

  global $user, $is_https;

  // Write and Close handlers are called after destructing objects

  // since PHP 5.0.5.

  // Thus destructors can use sessions but session handler can't use objects.

  // So we are moving session closure before destructing objects.

  drupal_register_shutdown_function('session_write_close');

  // Handle the case of first time visitors and clients that don't store

  // cookies (eg. web crawlers).

  $insecure_session_name = substr(session_name(), 1);

  if (empty($sid) || (!isset($_COOKIE[session_name()]) && !isset($_COOKIE[$insecure_session_name]))) {

    $user = drupal_anonymous_user();

    return '';

  }

  // Otherwise, if the session is still active, we have a record of the

  // client's session in the database. If it's HTTPS then we are either have

  // a HTTPS session or we are about to log in so we check the sessions table

  // for an anonymous session with the non-HTTPS-only cookie.

  if ($is_https) {

    $user = db_query("SELECT u.*, s.* FROM {users} u INNER JOIN {sessions} s ON u.uid = s.uid WHERE s.ssid = :ssid", array(':ssid' => $sid))->fetchObject();

    if (!$user) {

      if (isset($_COOKIE[$insecure_session_name])) {

        $user = db_query("SELECT u.*, s.* FROM {users} u INNER JOIN {sessions} s ON u.uid = s.uid WHERE s.sid = :sid AND s.uid = 0", array(

        ':sid' => $_COOKIE[$insecure_session_name]))

        ->fetchObject();

      }

    }

  }

  else {

    $user = db_query("SELECT u.*, s.* FROM {users} u INNER JOIN {sessions} s ON u.uid = s.uid WHERE s.sid = :sid", array(':sid' => $sid))->fetchObject();

  }

  // We found the client's session record and they are an authenticated,

  // active user.

  if ($user && $user->uid > 0 && $user->status == 1) {

    // This is done to unserialize the data member of $user.

    $user->data = unserialize($user->data);

    // Add roles element to $user.

    $user->roles = array();

    $user->roles[DRUPAL_AUTHENTICATED_RID] = 'authenticated user';

    $user->roles += db_query("SELECT r.rid, r.name FROM {role} r INNER JOIN {users_roles} ur ON ur.rid = r.rid WHERE ur.uid = :uid", array(':uid' => $user->uid))->fetchAllKeyed(0, 1);

  }

  elseif ($user) {

    // The user is anonymous or blocked. Only preserve two fields from the

    // {sessions} table.

    $account = drupal_anonymous_user();

    $account->session = $user->session;

    $account->timestamp = $user->timestamp;

    $user = $account;

  }

  else {

    // The session has expired.

    $user = drupal_anonymous_user();

    $user->session = '';

  }

  // Store the session that was read for comparison in _drupal_session_write().

  $last_read = &drupal_static('drupal_session_last_read');

  $last_read = array(

    'sid' => $sid,

    'value' => $user->session,

  );

  return $user->session;

}

/**

 * Writes an entire session to the database (internal use only).

 *

 * This function is registered with session_set_save_handler() to support

 * database-backed sessions.

 *

 * This function is an internal function and must not be called directly.

 * Doing so may result in corrupted session data or other unexpected behavior.

 * Session data must always be accessed via the $_SESSION superglobal.

 *

 * @param $sid

 *   The session ID of the session to write to.

 * @param $value

 *   Session data to write as a serialized string.

 *

 * @return

 *   Always returns TRUE.

 */

function _drupal_session_write($sid, $value) {

  global $user, $is_https;

  // The exception handler is not active at this point, so we need to do it

  // manually.

  try {

    if (!drupal_save_session()) {

      // We don't have anything to do if we are not allowed to save the session.

      return TRUE;

    }

    // Check whether $_SESSION has been changed in this request.

    $last_read = &drupal_static('drupal_session_last_read');

    $is_changed = !isset($last_read) || $last_read['sid'] != $sid || $last_read['value'] !== $value;

    // For performance reasons, do not update the sessions table, unless

    // $_SESSION has changed or more than 180 has passed since the last update.

    if ($is_changed || !isset($user->timestamp) || REQUEST_TIME - $user->timestamp > variable_get('session_write_interval', 180)) {

      // Either ssid or sid or both will be added from $key below.

      $fields = array(

        'uid' => $user->uid,

        'cache' => isset($user->cache) ? $user->cache : 0,

        'hostname' => ip_address(),

        'session' => $value,

        'timestamp' => REQUEST_TIME,

      );

      // Use the session ID as 'sid' and an empty string as 'ssid' by default.

      // _drupal_session_read() does not allow empty strings so that's a safe

      // default.

      $key = array('sid' => $sid, 'ssid' => '');

      // On HTTPS connections, use the session ID as both 'sid' and 'ssid'.

      if ($is_https) {

        $key['ssid'] = $sid;

        // The "secure pages" setting allows a site to simultaneously use both

        // secure and insecure session cookies. If enabled and both cookies are

        // presented then use both keys.

        if (variable_get('https', FALSE)) {

          $insecure_session_name = substr(session_name(), 1);

          if (isset($_COOKIE[$insecure_session_name])) {

            $key['sid'] = $_COOKIE[$insecure_session_name];

          }

        }

      }

      elseif (variable_get('https', FALSE)) {

        unset($key['ssid']);

      }

      db_merge('sessions')

        ->key($key)

        ->fields($fields)

        ->execute();

    }

    // Likewise, do not update access time more than once per 180 seconds.

    if ($user->uid && REQUEST_TIME - $user->access > variable_get('session_write_interval', 180)) {

      db_update('users')

        ->fields(array(

          'access' => REQUEST_TIME

        ))

        ->condition('uid', $user->uid)

        ->execute();

    }

    return TRUE;

  }

  catch (Exception $exception) {

    require_once DRUPAL_ROOT . '/includes/errors.inc';

    // If we are displaying errors, then do so with no possibility of a further

    // uncaught exception being thrown.

    if (error_displayable()) {

      print '<h1>Uncaught exception thrown in session handler.</h1>';

      print '<p>' . _drupal_render_exception_safe($exception) . '</p><hr />';

    }

    return FALSE;

  }

}

/**

 * Initializes the session handler, starting a session if needed.

 */

function drupal_session_initialize() {

  global $user, $is_https;

  session_set_save_handler('_drupal_session_open', '_drupal_session_close', '_drupal_session_read', '_drupal_session_write', '_drupal_session_destroy', '_drupal_session_garbage_collection');

  // We use !empty() in the following check to ensure that blank session IDs

  // are not valid.

  if (!empty($_COOKIE[session_name()]) || ($is_https && variable_get('https', FALSE) && !empty($_COOKIE[substr(session_name(), 1)]))) {

    // If a session cookie exists, initialize the session. Otherwise the

    // session is only started on demand in drupal_session_commit(), making

    // anonymous users not use a session cookie unless something is stored in

    // $_SESSION. This allows HTTP proxies to cache anonymous pageviews.

    drupal_session_start();

    if (!empty($user->uid) || !empty($_SESSION)) {

      drupal_page_is_cacheable(FALSE);

    }

  }

  else {

    // Set a session identifier for this request. This is necessary because

    // we lazily start sessions at the end of this request, and some

    // processes (like drupal_get_token()) needs to know the future

    // session ID in advance.

    $GLOBALS['lazy_session'] = TRUE;

    $user = drupal_anonymous_user();

    // Less random sessions (which are much faster to generate) are used for

    // anonymous users than are generated in drupal_session_regenerate() when

    // a user becomes authenticated.

    session_id(drupal_random_key());

    if ($is_https && variable_get('https', FALSE)) {

      $insecure_session_name = substr(session_name(), 1);

      $session_id = drupal_random_key();

      $_COOKIE[$insecure_session_name] = $session_id;

    }

  }

  date_default_timezone_set(drupal_get_user_timezone());

}

/**

 * Starts a session forcefully, preserving already set session data.

 *

 * @ingroup php_wrappers

 */

function drupal_session_start() {

  // Command line clients do not support cookies nor sessions.

  if (!drupal_session_started() && !drupal_is_cli()) {

    // Save current session data before starting it, as PHP will destroy it.

    $session_data = isset($_SESSION) ? $_SESSION : NULL;

    session_start();

    drupal_session_started(TRUE);

    // Restore session data.

    if (!empty($session_data)) {

      $_SESSION += $session_data;

    }

  }

}

/**

 * Commits the current session, if necessary.

 *

 * If an anonymous user already have an empty session, destroy it.

 */

function drupal_session_commit() {

  global $user, $is_https;

  if (!drupal_save_session()) {

    // We don't have anything to do if we are not allowed to save the session.

    return;

  }

  if (empty($user->uid) && empty($_SESSION)) {

    // There is no session data to store, destroy the session if it was

    // previously started.

    if (drupal_session_started()) {

      session_destroy();

    }

  }

  else {

    // There is session data to store. Start the session if it is not already

    // started.

    if (!drupal_session_started()) {

      drupal_session_start();

      if ($is_https && variable_get('https', FALSE)) {

        $insecure_session_name = substr(session_name(), 1);

        $params = session_get_cookie_params();

        $expire = $params['lifetime'] ? REQUEST_TIME + $params['lifetime'] : 0;

        setcookie($insecure_session_name, $_COOKIE[$insecure_session_name], $expire, $params['path'], $params['domain'], FALSE, $params['httponly']);

      }

    }

    // Write the session data.

    session_write_close();

  }

}

/**

 * Returns whether a session has been started.

 */

function drupal_session_started($set = NULL) {

  static $session_started = FALSE;

  if (isset($set)) {

    $session_started = $set;

  }

  return $session_started && session_id();

}

/**

 * Called when an anonymous user becomes authenticated or vice-versa.

 *

 * @ingroup php_wrappers

 */

function drupal_session_regenerate() {

  global $user, $is_https;

  // Nothing to do if we are not allowed to change the session.

  if (!drupal_save_session()) {

    return;

  }

  if ($is_https && variable_get('https', FALSE)) {

    $insecure_session_name = substr(session_name(), 1);

    if (!isset($GLOBALS['lazy_session']) && isset($_COOKIE[$insecure_session_name])) {

      $old_insecure_session_id = $_COOKIE[$insecure_session_name];

    }

    $params = session_get_cookie_params();

    $session_id = drupal_random_key();

    // If a session cookie lifetime is set, the session will expire

    // $params['lifetime'] seconds from the current request. If it is not set,

    // it will expire when the browser is closed.

    $expire = $params['lifetime'] ? REQUEST_TIME + $params['lifetime'] : 0;

    setcookie($insecure_session_name, $session_id, $expire, $params['path'], $params['domain'], FALSE, $params['httponly']);

    $_COOKIE[$insecure_session_name] = $session_id;

  }

  if (drupal_session_started()) {

    $old_session_id = session_id();

  }

  session_id(drupal_random_key());

  if (isset($old_session_id)) {

    $params = session_get_cookie_params();

    $expire = $params['lifetime'] ? REQUEST_TIME + $params['lifetime'] : 0;

    setcookie(session_name(), session_id(), $expire, $params['path'], $params['domain'], $params['secure'], $params['httponly']);

    $fields = array('sid' => session_id());

    if ($is_https) {

      $fields['ssid'] = session_id();

      // If the "secure pages" setting is enabled, use the newly-created

      // insecure session identifier as the regenerated sid.

      if (variable_get('https', FALSE)) {

        $fields['sid'] = $session_id;

      }

    }

    db_update('sessions')

      ->fields($fields)

      ->condition($is_https ? 'ssid' : 'sid', $old_session_id)

      ->execute();

  }

  elseif (isset($old_insecure_session_id)) {

    // If logging in to the secure site, and there was no active session on the

    // secure site but a session was active on the insecure site, update the

    // insecure session with the new session identifiers.

    db_update('sessions')

      ->fields(array('sid' => $session_id, 'ssid' => session_id()))

      ->condition('sid', $old_insecure_session_id)

      ->execute();

  }

  else {

    // Start the session when it doesn't exist yet.

    // Preserve the logged in user, as it will be reset to anonymous

    // by _drupal_session_read.

    $account = $user;

    drupal_session_start();

    $user = $account;

  }

  date_default_timezone_set(drupal_get_user_timezone());

}

/**

 * Session handler assigned by session_set_save_handler().

 *

 * Cleans up a specific session.

 *

 * @param $sid

 *   Session ID.

 */

function _drupal_session_destroy($sid) {

  global $user, $is_https;

  // Nothing to do if we are not allowed to change the session.

  if (!drupal_save_session()) {

    return TRUE;

  }

  // Delete session data.

  db_delete('sessions')

    ->condition($is_https ? 'ssid' : 'sid', $sid)

    ->execute();