session.php 14.4 KB
Newer Older
1 2 3 4
<?php
/**
 *
 * @package    mahara
Nigel McNie's avatar
Nigel McNie committed
5
 * @subpackage core
6
 * @author     Catalyst IT Ltd
7 8
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL version 3 or later
 * @copyright  For copyright information on Mahara, please see the README file distributed with this software.
9 10 11 12 13
 *
 */

defined('INTERNAL') || die();

14 15 16
//
// Set session settings
//
17
session_name(get_config('cookieprefix') . 'mahara');
18 19
$sessionpath = get_config('sessionpath');
ini_set('session.save_path', '3;' . $sessionpath);
20
ini_set('session.gc_divisor', 1000);
21
ini_set('session.gc_maxlifetime', get_config('session_timeout'));
22
ini_set('session.use_only_cookies', true);
23 24 25
if ($domain = get_config('cookiedomain')) {
    ini_set('session.cookie_domain', $domain);
}
26 27
ini_set('session.cookie_path', get_mahara_install_subdirectory());
ini_set('session.cookie_httponly', 1);
28
ini_set('session.hash_bits_per_character', 4);
29
ini_set('session.hash_function', 0);
30 31 32
if (is_https()) {
    ini_set('session.cookie_secure', true);
}
33

34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
// Attempt to create session directories
if (!is_dir("$sessionpath/0")) {
    // Create three levels of directories, named 0-9, a-f
    $characters = array('0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f');
    foreach ($characters as $c1) {
        check_dir_exists("$sessionpath/$c1");
        foreach ($characters as $c2) {
            check_dir_exists("$sessionpath/$c1/$c2");
            foreach ($characters as $c3) {
                check_dir_exists("$sessionpath/$c1/$c2/$c3");
            }
        }
    }
}

49
/**
50
 * The session class handles session data and messages.
51
 *
52 53 54 55
 * This class stores information across page loads, using only a cookie to
 * remember the info. User information is stored in the session so it does
 * not have to be requested each time the page is loaded, however any other
 * information can also be stored using this class.
56 57 58 59
 *
 * This class also is smart about giving out sessions - if a visitor
 * has not logged in (e.g. they are a guest, searchbot or a simple
 * 'curl' request), a session will not be created for them.
60
 *
61 62
 * Messages are stored in the session and are displayed the next time
 * a page is displayed to a user, even over multiple requests.
63 64 65 66
 *
 * In addition, to allow the json progress meter to do its work, this
 * class maintains the session state, keeping it read-only except as
 * necessary (in order to not block the progress meter json calls).
67 68 69
 */
class Session {

70
    /**
71
     * Resumes an existing session, only if there is one
72
     */
73
    private function __construct() {
74
        // Resume an existing session if required
75
        if (isset($_COOKIE[session_name()])) {
76
            @session_start();
77 78 79

            // But it's not writable except through functions below.
            $this->ro_session();
80 81 82
        }
    }

83 84 85 86 87 88 89 90 91 92 93 94
    /**
     * Singelton function keeps us from generating multiple instances of this
     * class
     *
     * @return object   The class instance
     * @access public
     */
    public static function singleton() {
        //single instance
        static $instance;

        //if we don't have the single instance, create one
95
        if (!isset($instance)) {
96 97 98 99 100
            $instance = new Session();
        }
        return($instance);
    }

101 102 103 104 105 106 107 108 109 110
    /**
     * Gets the session property keyed by $key.
     *
     * @param string $key The key to get the value of
     * @return mixed
     */
    public function __get($key) {
        return $this->get($key);
    }

111 112 113 114 115 116 117 118 119 120
    /**
     * Gets the session property keyed by $key.
     *
     * @param string $key The key to get the value of
     * @return mixed
     */
    public function get($key) {
        if (isset($_SESSION[$key])) {
            return $_SESSION[$key];
        }
Penny Leach's avatar
Penny Leach committed
121 122 123
        return null;
    }

124 125 126 127 128 129 130 131 132 133
    /**
     * Sets the session property keyed by $key.
     *
     * @param string $key The key to get the value of
     * @return mixed
     */
    public function __set($key, $value) {
        return $this->set($key, $value);
    }

134 135 136 137 138 139 140
    /**
     * Sets the session property keyed by $key.
     *
     * @param string $key   The key to set.
     * @param string $value The value to set for the key
     */
    public function set($key, $value) {
141
        $this->ensure_session();
142 143 144 145 146 147 148 149

        if (is_null($value)) {
            unset($_SESSION[$key]);
        }
        else {
            $_SESSION[$key] = $value;
        }
        $this->ro_session();
150 151
    }

Martyn Smith's avatar
Martyn Smith committed
152
    /**
153
     * Unsets the session property keyed by $key.
Martyn Smith's avatar
Martyn Smith committed
154
     *
155
     * @param string $key   The key to remove.
Martyn Smith's avatar
Martyn Smith committed
156
     */
157
    public function __unset($key) {
Martyn Smith's avatar
Martyn Smith committed
158
        $this->ensure_session();
159 160
        unset($_SESSION[$key]);
        $this->ro_session();
Martyn Smith's avatar
Martyn Smith committed
161 162
    }

163 164 165 166 167 168 169 170 171
    /**
     * Old way of clearing session property - added for backwards compatibility
     *
     * @param string $key   The key to remove.
     */
    public function clear($key) {
        $this->__unset($key);
    }

172 173 174 175 176
    /**
     * Adds a message that indicates something was successful
     *
     * @param string $message The message to add
     * @param boolean $escape Whether to HTML escape the message
177 178
     * @param string $placement Place for messages to appear on page (See render_messages()
     *     for information about placement options)
179
     */
180
    public function add_ok_msg($message, $escape=true, $placement='messages') {
181
        $this->ensure_session();
182
        if ($escape) {
183
            $message = self::escape_message($message);
184
        }
185
        $_SESSION['messages'][] = array('type' => 'ok', 'msg' => $message, 'placement' => $placement);
186
        $this->ro_session();
187 188 189 190 191 192 193
    }

    /**
     * Adds a message that indicates an informational message
     *
     * @param string $message The message to add
     * @param boolean $escape Whether to HTML escape the message
194 195
     * @param string $placement Place for messages to appear on page (See render_messages()
     *     for information about placement options)
196
     */
197
    public function add_info_msg($message, $escape=true, $placement='messages') {
198
        $this->ensure_session();
199
        if ($escape) {
200
            $message = self::escape_message($message);
201
        }
202
        $_SESSION['messages'][] = array('type' => 'info', 'msg' => $message, 'placement' => $placement);
203
        $this->ro_session();
204 205 206 207 208 209 210
    }

    /**
     * Adds a message that indicates a failure to do something
     *
     * @param string $message The message to add
     * @param boolean $escape Whether to HTML escape the message
211 212
     * @param string $placement Place for messages to appear on page (See render_messages()
     *     for information about placement options)
213
     */
214
    public function add_error_msg($message, $escape=true, $placement='messages') {
215
        $this->ensure_session();
216
        if ($escape) {
217
            $message = self::escape_message($message);
218
        }
219
        $_SESSION['messages'][] = array('type' => 'error', 'msg' => $message, 'placement' => $placement);
220
        $this->ro_session();
221 222 223 224 225 226 227 228
    }

    /**
     * Builds HTML that represents all of the messages and returns it.
     *
     * This is designed to let smarty templates hook in any session messages.
     *
     * Calling this function will destroy the session messages that were
229 230
     * assigned to the $placement, so they do not inadvertently get
     * displayed again.
231 232 233 234 235 236 237 238 239 240 241 242 243 244
     *
     * To define where the messages for a particular $placement value should be displayed,
     * add this code to a page template:
     *
     *   {dynamic}{insert_messages placement='your_placement_name_here'}{/dynamic}
     *
     * The default 'messages' placement is shown on every page, and is suitable for most purposes.
     * Alternative placements should only be needed in special situations, such as showing a login-related
     * error in the login box. Note that messages will hang around in the $SESSION until a page template
     * with their "placement" in it is loaded. So, they should only be used in situations where you're
     * certain their placement zone will be present on the next page load, or else the user may be
     * confused by their appearance several page loads later.
     *
     * @param string $placement Render only messages for this placement
245
     *
246 247
     * @return string The HTML representing all of the session messages assigned
     * to $placement.
248
     */
249
    public function render_messages($placement = 'messages') {
250
        global $THEME;
251
        $result = '<div id="' . $placement . '" role="alert" aria-live="assertive">';
252
        if (isset($_SESSION['messages'])) {
253
            $this->ensure_session();  // Make it writable and lock against other threads.
254 255 256 257 258 259
            foreach ($_SESSION['messages'] as $key => $data) {
                if ($data['placement'] == $placement) {
                    $result .= '<div class="' . $data['type'] . '"><div>';
                    $result .= $data['msg'] . '</div></div>';
                    unset($_SESSION['messages'][$key]);
                }
260
            }
261
            $this->ro_session();
262
        }
263
        $result .= '</div>';
264 265 266
        return $result;
    }

267 268 269 270 271 272 273 274 275 276 277 278 279 280 281
    public function set_progress($token, $content) {
        // Make the session writable.
        $this->ensure_session();

        if ($content === FALSE) {
            unset($_SESSION['progress_meters'][$token]);
        }
        else {
            $_SESSION['progress_meters'][$token] = $content;
        }

        // Release our lock.
        $this->ro_session();
    }

282
    /**
283
     * Create a session, by initialising the $_SESSION array.
284
     */
285
    private function ensure_session() {
286 287 288 289
        if (defined('CLI')) {
            return;
        }

290
        if (empty($_SESSION)) {
291
            @session_start();
292 293 294
            $_SESSION = array(
                'messages' => array()
            );
295
        }
296 297 298
        else {
            @session_start();
        }
299 300 301
        // Anytime you call session_start() more than once, PHP will usually
        // send out a duplicate session header.
        clear_duplicate_cookies();
302 303 304 305 306 307 308 309 310
    }

    /*
     * Make a session readonly after modifying it.
     *
     * The session must have been opened already.
     */

    private function ro_session() {
311 312 313 314
        if (defined('CLI')) {
            return;
        }

315
        session_write_close();
316 317
    }

318 319 320 321
    /**
     * Destroy a session
     */
    public function destroy_session() {
322 323 324 325
        if (defined('CLI')) {
            return;
        }

326 327 328 329 330 331 332 333 334 335
        if ($this->is_live()) {
            $_SESSION = array();
            if (isset($_COOKIE[session_name()])) {
                setcookie(session_name(), '', time() - 65536,
                    ini_get('session.cookie_path'),
                    ini_get('session.cookie_domain'),
                    ini_get('session.cookie_secure'),
                    ini_get('session.cookie_httponly')
                );
            }
336
            @session_start();
337
            session_destroy();
338
            clear_duplicate_cookies();
339 340 341
        }
    }

342 343 344 345 346 347 348 349 350 351
    /**
     * Find out if the session has been started yet
     */
    public function is_live() {
        if ("" == session_id()) {
            return false;
        }
        return true;
    }

352 353
    /**
     * Escape a message for HTML output
354
     *
355 356 357 358 359 360 361
     * @param string $message The message to escape
     * @return string         The message, escaped for output as HTML
     */
    private static function escape_message($message) {
        $message = hsc($message);
        $message = str_replace('  ', '&nbsp; ', $message);
        return $message;
362
    }
363

364 365 366 367 368 369 370
}

/**
 * A smarty callback to insert page messages
 *
 * @return string The HTML represening all of the session messages.
 */
371
function insert_messages($placement='messages') {
372
    global $SESSION;
373
    return $SESSION->render_messages($placement);
374 375
}

376

377 378 379 380
/**
 * Delete all sessions belonging to a given user except for the current one
 */
function remove_user_sessions($userid) {
381
    global $sessionpath, $USER, $SESSION;
382

383
    $sessionids = get_column('usr_session', 'session', 'usr', (int) $userid);
384 385

    if (empty($sessionids)) {
386 387 388 389 390
        return;
    }

    $alive = array();
    $dead = array();
391 392 393 394 395 396 397 398 399 400

    // Keep track of the current session id so we can return to it at the end
    if ($SESSION->is_live()) {
        $sid = $USER->get('sessionid');
    }
    else {
        // The user has no session (this function is being called by a CLI script)
        $sid = false;
    }

401
    foreach ($sessionids as $sessionid) {
402 403 404
        if ($sessionid == $sid) {
            continue;
        }
405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435
        $file = $sessionpath;
        for ($i = 0; $i < 3; $i++) {
            $file .= '/' . substr($sessionid, $i, 1);
        }
        $file .= '/sess_' . $sessionid;
        if (file_exists($file)) {
            $alive[] = $sessionid;
        }
        else {
            $dead[] = $sessionid;
        }
    }

    if (!empty($dead)) {
        delete_records_select('usr_session', 'session IN (' . join(',', array_map('db_quote', $dead)) . ')');
    }

    if (empty($alive)) {
        return;
    }

    session_commit();

    foreach ($alive as $sessionid) {
        session_id($sessionid);
        if (session_start()) {
            session_destroy();
            session_commit();
        }
    }

436 437 438 439
    if ($sid !== false) {
        session_id($sid);
        session_start();
    }
440

441
    clear_duplicate_cookies();
442 443 444
    delete_records_select('usr_session', 'session IN (' . join(',', array_map('db_quote', $alive)) . ')');
}

445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462
/**
 * Delete all session files except for the current one
 */
function remove_all_sessions() {
    global $sessionpath, $USER;

    $sid = $USER->get('sessionid');

    $iterator = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($sessionpath));
    foreach ($iterator as $path) {
        if ($path->isFile() && $path->getFilename() !== ('sess_' . $sid)) {
            @unlink($path->getPathname());
        }
    }
    clearstatcache();

    delete_records_select('usr_session', 'session != ?', array($sid));
}
463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492

/**
 * Every time you call session_start(), PHP adds another
 * identical session cookie to the response header. Do this
 * enough times, and your response header becomes big enough
 * to choke the web server.
 *
 * This method clears out the duplicate session cookies.
 */
function clear_duplicate_cookies() {
    // If headers have already been sent, there's nothing we can do
    if (headers_sent()) {
        return;
    }

    $cookies = array();
    foreach (headers_list() as $header) {
        // Identify cookie headers
        if (strpos($header, 'Set-Cookie:') === 0) {
            $cookies[] = $header;
        }
    }
    // Removes all cookie headers, not just the session one.
    header_remove('Set-Cookie');

    // Restore one copy of each cookie
    foreach(array_unique($cookies) as $cookie) {
        header($cookie, false);
    }
}