session.php 13 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
    /**
     * Adds a message that indicates something was successful
     *
     * @param string $message The message to add
     * @param boolean $escape Whether to HTML escape the message
168
169
     * @param string $placement Place for messages to appear on page (See render_messages()
     *     for information about placement options)
170
     */
171
    public function add_ok_msg($message, $escape=true, $placement='messages') {
172
        $this->ensure_session();
173
        if ($escape) {
174
            $message = self::escape_message($message);
175
        }
176
        $_SESSION['messages'][] = array('type' => 'ok', 'msg' => $message, 'placement' => $placement);
177
        $this->ro_session();
178
179
180
181
182
183
184
    }

    /**
     * Adds a message that indicates an informational message
     *
     * @param string $message The message to add
     * @param boolean $escape Whether to HTML escape the message
185
186
     * @param string $placement Place for messages to appear on page (See render_messages()
     *     for information about placement options)
187
     */
188
    public function add_info_msg($message, $escape=true, $placement='messages') {
189
        $this->ensure_session();
190
        if ($escape) {
191
            $message = self::escape_message($message);
192
        }
193
        $_SESSION['messages'][] = array('type' => 'info', 'msg' => $message, 'placement' => $placement);
194
        $this->ro_session();
195
196
197
198
199
200
201
    }

    /**
     * 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
202
203
     * @param string $placement Place for messages to appear on page (See render_messages()
     *     for information about placement options)
204
     */
205
    public function add_error_msg($message, $escape=true, $placement='messages') {
206
        $this->ensure_session();
207
        if ($escape) {
208
            $message = self::escape_message($message);
209
        }
210
        $_SESSION['messages'][] = array('type' => 'error', 'msg' => $message, 'placement' => $placement);
211
        $this->ro_session();
212
213
214
215
216
217
218
219
    }

    /**
     * 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
220
221
     * assigned to the $placement, so they do not inadvertently get
     * displayed again.
222
223
224
225
226
227
228
229
230
231
232
233
234
235
     *
     * 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
236
     *
237
238
     * @return string The HTML representing all of the session messages assigned
     * to $placement.
239
     */
240
    public function render_messages($placement = 'messages') {
241
        global $THEME;
242
        $result = '<div id="' . $placement . '" role="alert" aria-live="assertive">';
243
        if (isset($_SESSION['messages'])) {
244
            $this->ensure_session();  // Make it writable and lock against other threads.
245
246
247
248
249
250
            foreach ($_SESSION['messages'] as $key => $data) {
                if ($data['placement'] == $placement) {
                    $result .= '<div class="' . $data['type'] . '"><div>';
                    $result .= $data['msg'] . '</div></div>';
                    unset($_SESSION['messages'][$key]);
                }
251
            }
252
            $this->ro_session();
253
        }
254
        $result .= '</div>';
255
256
257
        return $result;
    }

258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
    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();
    }

273
    /**
274
     * Create a session, by initialising the $_SESSION array.
275
     */
276
277
    private function ensure_session() {
        if (empty($_SESSION)) {
278
            @session_start();
279
280
281
            $_SESSION = array(
                'messages' => array()
            );
282
        }
283
284
285
286
287
288
289
290
291
292
293
294
295
        else {
            @session_start();
        }
    }

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

    private function ro_session() {
        session_write_close();
296
297
    }

298
299
300
301
302
303
304
305
306
307
308
309
310
311
    /**
     * Destroy a session
     */
    public function destroy_session() {
        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')
                );
            }
312
            @session_start();
313
314
315
316
            session_destroy();
        }
    }

317
318
319
320
321
322
323
324
325
326
    /**
     * Find out if the session has been started yet
     */
    public function is_live() {
        if ("" == session_id()) {
            return false;
        }
        return true;
    }

327
328
    /**
     * Escape a message for HTML output
329
     *
330
331
332
333
334
335
336
     * @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;
337
    }
338

339
340
341
342
343
344
345
}

/**
 * A smarty callback to insert page messages
 *
 * @return string The HTML represening all of the session messages.
 */
346
function insert_messages($placement='messages') {
347
    global $SESSION;
348
    return $SESSION->render_messages($placement);
349
350
}

351

352
353
354
355
/**
 * Delete all sessions belonging to a given user except for the current one
 */
function remove_user_sessions($userid) {
356
    global $sessionpath, $USER, $SESSION;
357

358
    $sessionids = get_column('usr_session', 'session', 'usr', (int) $userid);
359
360

    if (empty($sessionids)) {
361
362
363
364
365
        return;
    }

    $alive = array();
    $dead = array();
366
367
368
369
370
371
372
373
374
375

    // 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;
    }

376
    foreach ($sessionids as $sessionid) {
377
378
379
        if ($sessionid == $sid) {
            continue;
        }
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
        $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();
        }
    }

411
412
413
414
    if ($sid !== false) {
        session_id($sid);
        session_start();
    }
415
416
417
418

    delete_records_select('usr_session', 'session IN (' . join(',', array_map('db_quote', $alive)) . ')');
}

419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
/**
 * 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));
}