system/libraries/Session.php

   1 <?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');
   2 /**
   3  * CodeIgniter
   4  *
   5  * An open source application development framework for PHP 5.1.6 or newer
   6  *
   7  * @package             CodeIgniter
   8  * @author              ExpressionEngine Dev Team
   9  * @copyright   Copyright (c) 2008 - 2011, EllisLab, Inc.
  10  * @license             http://codeigniter.com/user_guide/license.html
  11  * @link                http://codeigniter.com
  12  * @since               Version 1.0
  13  * @filesource
  14  */
  15
  16 // ------------------------------------------------------------------------
  17
  18 /**
  19  * Session Class
  20  *
  21  * @package             CodeIgniter
  22  * @subpackage  Libraries
  23  * @category    Sessions
  24  * @author              ExpressionEngine Dev Team
  25  * @link                http://codeigniter.com/user_guide/libraries/sessions.html
  26  */
  27 class CI_Session {
  28
  29         var $sess_encrypt_cookie                = FALSE;
  30         var $sess_use_database                  = FALSE;
  31         var $sess_table_name                    = '';
  32         var $sess_expiration                    = 7200;
  33         var $sess_expire_on_close               = FALSE;
  34         var $sess_match_ip                              = FALSE;
  35         var $sess_match_useragent               = TRUE;
  36         var $sess_cookie_name                   = 'ci_session';
  37         var $cookie_prefix                              = '';
  38         var $cookie_path                                = '';
  39         var $cookie_domain                              = '';
  40         var $cookie_secure                              = FALSE;
  41         var $sess_time_to_update                = 300;
  42         var $encryption_key                             = '';
  43         var $flashdata_key                              = 'flash';
  44         var $time_reference                             = 'time';
  45         var $gc_probability                             = 5;
  46         var $userdata                                   = array();
  47         var $CI;
  48         var $now;
  49
  50         /**
  51          * Session Constructor
  52          *
  53          * The constructor runs the session routines automatically
  54          * whenever the class is instantiated.
  55          */
  56         public function __construct($params = array())
  57         {
  58                 log_message('debug', "Session Class Initialized");
  59
  60                 // Set the super object to a local variable for use throughout the class
  61                 $this->CI =& get_instance();
  62
  63                 // Set all the session preferences, which can either be set
  64                 // manually via the $params array above or via the config file
  65                 foreach (array('sess_encrypt_cookie', 'sess_use_database', 'sess_table_name', 'sess_expiration', 'sess_expire_on_close', 'sess_match_ip', 'sess_match_useragent', 'sess_cookie_name', 'cookie_path', 'cookie_domain', 'cookie_secure', 'sess_time_to_update', 'time_reference', 'cookie_prefix', 'encryption_key') as $key)
  66                 {
  67                         $this->$key = (isset($params[$key])) ? $params[$key] : $this->CI->config->item($key);
  68                 }
  69
  70                 if ($this->encryption_key == '')
  71                 {
  72                         show_error('In order to use the Session class you are required to set an encryption key in your config file.');
  73                 }
  74
  75                 // Load the string helper so we can use the strip_slashes() function
  76                 $this->CI->load->helper('string');
  77
  78                 // Do we need encryption? If so, load the encryption class
  79                 if ($this->sess_encrypt_cookie == TRUE)
  80                 {
  81                         $this->CI->load->library('encrypt');
  82                 }
  83
  84                 // Are we using a database?  If so, load it
  85                 if ($this->sess_use_database === TRUE AND $this->sess_table_name != '')
  86                 {
  87                         $this->CI->load->database();
  88                 }
  89
  90                 // Set the "now" time.  Can either be GMT or server time, based on the
  91                 // config prefs.  We use this to set the "last activity" time
  92                 $this->now = $this->_get_time();
  93
  94                 // Set the session length. If the session expiration is
  95                 // set to zero we'll set the expiration two years from now.
  96                 if ($this->sess_expiration == 0)
  97                 {
  98                         $this->sess_expiration = (60*60*24*365*2);
  99                 }
 100
 101                 // Set the cookie name
 102                 $this->sess_cookie_name = $this->cookie_prefix.$this->sess_cookie_name;
 103
 104                 // Run the Session routine. If a session doesn't exist we'll
 105                 // create a new one.  If it does, we'll update it.
 106                 if ( ! $this->sess_read())
 107                 {
 108                         $this->sess_create();
 109                 }
 110                 else
 111                 {
 112                         $this->sess_update();
 113                 }
 114
 115                 // Delete 'old' flashdata (from last request)
 116                 $this->_flashdata_sweep();
 117
 118                 // Mark all new flashdata as old (data will be deleted before next request)
 119                 $this->_flashdata_mark();
 120
 121                 // Delete expired sessions if necessary
 122                 $this->_sess_gc();
 123
 124                 log_message('debug', "Session routines successfully run");
 125         }
 126
 127         // --------------------------------------------------------------------
 128
 129         /**
 130          * Fetch the current session data if it exists
 131          *
 132          * @access      public
 133          * @return      bool
 134          */
 135         function sess_read()
 136         {
 137                 // Fetch the cookie
 138                 $session = $this->CI->input->cookie($this->sess_cookie_name);
 139
 140                 // No cookie?  Goodbye cruel world!...
 141                 if ($session === FALSE)
 142                 {
 143                         log_message('debug', 'A session cookie was not found.');
 144                         return FALSE;
 145                 }
 146
 147                 // Decrypt the cookie data
 148                 if ($this->sess_encrypt_cookie == TRUE)
 149                 {
 150                         $session = $this->CI->encrypt->decode($session);
 151                 }
 152                 else
 153                 {
 154                         // encryption was not used, so we need to check the md5 hash
 155                         $hash    = substr($session, strlen($session)-32); // get last 32 chars
 156                         $session = substr($session, 0, strlen($session)-32);
 157
 158                         // Does the md5 hash match?  This is to prevent manipulation of session data in userspace
 159                         if ($hash !==  md5($session.$this->encryption_key))
 160                         {
 161                                 log_message('error', 'The session cookie data did not match what was expected. This could be a possible hacking attempt.');
 162                                 $this->sess_destroy();
 163                                 return FALSE;
 164                         }
 165                 }
 166
 167                 // Unserialize the session array
 168                 $session = $this->_unserialize($session);
 169
 170                 // Is the session data we unserialized an array with the correct format?
 171                 if ( ! is_array($session) OR ! isset($session['session_id']) OR ! isset($session['ip_address']) OR ! isset($session['user_agent']) OR ! isset($session['last_activity']))
 172                 {
 173                         $this->sess_destroy();
 174                         return FALSE;
 175                 }
 176
 177                 // Is the session current?
 178                 if (($session['last_activity'] + $this->sess_expiration) < $this->now)
 179                 {
 180                         $this->sess_destroy();
 181                         return FALSE;
 182                 }
 183
 184                 // Does the IP Match?
 185                 if ($this->sess_match_ip == TRUE AND $session['ip_address'] != $this->CI->input->ip_address())
 186                 {
 187                         $this->sess_destroy();
 188                         return FALSE;
 189                 }
 190
 191                 // Does the User Agent Match?
 192                 if ($this->sess_match_useragent == TRUE AND trim($session['user_agent']) != trim(substr($this->CI->input->user_agent(), 0, 50)))
 193                 {
 194                         $this->sess_destroy();
 195                         return FALSE;
 196                 }
 197
 198                 // Is there a corresponding session in the DB?
 199                 if ($this->sess_use_database === TRUE)
 200                 {
 201                         $this->CI->db->where('session_id', $session['session_id']);
 202
 203                         if ($this->sess_match_ip == TRUE)
 204                         {
 205                                 $this->CI->db->where('ip_address', $session['ip_address']);
 206                         }
 207
 208                         if ($this->sess_match_useragent == TRUE)
 209                         {
 210                                 $this->CI->db->where('user_agent', $session['user_agent']);
 211                         }
 212
 213                         $query = $this->CI->db->get($this->sess_table_name);
 214
 215                         // No result?  Kill it!
 216                         if ($query->num_rows() == 0)
 217                         {
 218                                 $this->sess_destroy();
 219                                 return FALSE;
 220                         }
 221
 222                         // Is there custom data?  If so, add it to the main session array
 223                         $row = $query->row();
 224                         if (isset($row->user_data) AND $row->user_data != '')
 225                         {
 226                                 $custom_data = $this->_unserialize($row->user_data);
 227
 228                                 if (is_array($custom_data))
 229                                 {
 230                                         foreach ($custom_data as $key => $val)
 231                                         {
 232                                                 $session[$key] = $val;
 233                                         }
 234                                 }
 235                         }
 236                 }
 237
 238                 // Session is valid!
 239                 $this->userdata = $session;
 240                 unset($session);
 241
 242                 return TRUE;
 243         }
 244
 245         // --------------------------------------------------------------------
 246
 247         /**
 248          * Write the session data
 249          *
 250          * @access      public
 251          * @return      void
 252          */
 253         function sess_write()
 254         {
 255                 // Are we saving custom data to the DB?  If not, all we do is update the cookie
 256                 if ($this->sess_use_database === FALSE)
 257                 {
 258                         $this->_set_cookie();
 259                         return;
 260                 }
 261
 262                 // set the custom userdata, the session data we will set in a second
 263                 $custom_userdata = $this->userdata;
 264                 $cookie_userdata = array();
 265
 266                 // Before continuing, we need to determine if there is any custom data to deal with.
 267                 // Let's determine this by removing the default indexes to see if there's anything left in the array
 268                 // and set the session data while we're at it
 269                 foreach (array('session_id','ip_address','user_agent','last_activity') as $val)
 270                 {
 271                         unset($custom_userdata[$val]);
 272                         $cookie_userdata[$val] = $this->userdata[$val];
 273                 }
 274
 275                 // Did we find any custom data?  If not, we turn the empty array into a string
 276                 // since there's no reason to serialize and store an empty array in the DB
 277                 if (count($custom_userdata) === 0)
 278                 {
 279                         $custom_userdata = '';
 280                 }
 281                 else
 282                 {
 283                         // Serialize the custom data array so we can store it
 284                         $custom_userdata = $this->_serialize($custom_userdata);
 285                 }
 286
 287                 // Run the update query
 288                 $this->CI->db->where('session_id', $this->userdata['session_id']);
 289                 $this->CI->db->update($this->sess_table_name, array('last_activity' => $this->userdata['last_activity'], 'user_data' => $custom_userdata));
 290
 291                 // Write the cookie.  Notice that we manually pass the cookie data array to the
 292                 // _set_cookie() function. Normally that function will store $this->userdata, but
 293                 // in this case that array contains custom data, which we do not want in the cookie.
 294                 $this->_set_cookie($cookie_userdata);
 295         }
 296
 297         // --------------------------------------------------------------------
 298
 299         /**
 300          * Create a new session
 301          *
 302          * @access      public
 303          * @return      void
 304          */
 305         function sess_create()
 306         {
 307                 $sessid = '';
 308                 while (strlen($sessid) < 32)
 309                 {
 310                         $sessid .= mt_rand(0, mt_getrandmax());
 311                 }
 312
 313                 // To make the session ID even more secure we'll combine it with the user's IP
 314                 $sessid .= $this->CI->input->ip_address();
 315
 316                 $this->userdata = array(
 317                                                         'session_id'    => md5(uniqid($sessid, TRUE)),
 318                                                         'ip_address'    => $this->CI->input->ip_address(),
 319                                                         'user_agent'    => substr($this->CI->input->user_agent(), 0, 50),
 320                                                         'last_activity' => $this->now
 321                                                         );
 322
 323
 324                 // Save the data to the DB if needed
 325                 if ($this->sess_use_database === TRUE)
 326                 {
 327                         $this->CI->db->query($this->CI->db->insert_string($this->sess_table_name, $this->userdata));
 328                 }
 329
 330                 // Write the cookie
 331                 $this->_set_cookie();
 332         }
 333
 334         // --------------------------------------------------------------------
 335
 336         /**
 337          * Update an existing session
 338          *
 339          * @access      public
 340          * @return      void
 341          */
 342         function sess_update()
 343         {
 344                 // We only update the session every five minutes by default
 345                 if (($this->userdata['last_activity'] + $this->sess_time_to_update) >= $this->now)
 346                 {
 347                         return;
 348                 }
 349
 350                 // Save the old session id so we know which record to
 351                 // update in the database if we need it
 352                 $old_sessid = $this->userdata['session_id'];
 353                 $new_sessid = '';
 354                 while (strlen($new_sessid) < 32)
 355                 {
 356                         $new_sessid .= mt_rand(0, mt_getrandmax());
 357                 }
 358
 359                 // To make the session ID even more secure we'll combine it with the user's IP
 360                 $new_sessid .= $this->CI->input->ip_address();
 361
 362                 // Turn it into a hash
 363                 $new_sessid = md5(uniqid($new_sessid, TRUE));
 364
 365                 // Update the session data in the session data array
 366                 $this->userdata['session_id'] = $new_sessid;
 367                 $this->userdata['last_activity'] = $this->now;
 368
 369                 // _set_cookie() will handle this for us if we aren't using database sessions
 370                 // by pushing all userdata to the cookie.
 371                 $cookie_data = NULL;
 372
 373                 // Update the session ID and last_activity field in the DB if needed
 374                 if ($this->sess_use_database === TRUE)
 375                 {
 376                         // set cookie explicitly to only have our session data
 377                         $cookie_data = array();
 378                         foreach (array('session_id','ip_address','user_agent','last_activity') as $val)
 379                         {
 380                                 $cookie_data[$val] = $this->userdata[$val];
 381                         }
 382
 383                         $this->CI->db->query($this->CI->db->update_string($this->sess_table_name, array('last_activity' => $this->now, 'session_id' => $new_sessid), array('session_id' => $old_sessid)));
 384                 }
 385
 386                 // Write the cookie
 387                 $this->_set_cookie($cookie_data);
 388         }
 389
 390         // --------------------------------------------------------------------
 391
 392         /**
 393          * Destroy the current session
 394          *
 395          * @access      public
 396          * @return      void
 397          */
 398         function sess_destroy()
 399         {
 400                 // Kill the session DB row
 401                 if ($this->sess_use_database === TRUE AND isset($this->userdata['session_id']))
 402                 {
 403                         $this->CI->db->where('session_id', $this->userdata['session_id']);
 404                         $this->CI->db->delete($this->sess_table_name);
 405                 }
 406
 407                 // Kill the cookie
 408                 setcookie(
 409                                         $this->sess_cookie_name,
 410                                         addslashes(serialize(array())),
 411                                         ($this->now - 31500000),
 412                                         $this->cookie_path,
 413                                         $this->cookie_domain,
 414                                         0
 415                                 );
 416         }
 417
 418         // --------------------------------------------------------------------
 419
 420         /**
 421          * Fetch a specific item from the session array
 422          *
 423          * @access      public
 424          * @param       string
 425          * @return      string
 426          */
 427         function userdata($item)
 428         {
 429                 return ( ! isset($this->userdata[$item])) ? FALSE : $this->userdata[$item];
 430         }
 431
 432         // --------------------------------------------------------------------
 433
 434         /**
 435          * Fetch all session data
 436          *
 437          * @access      public
 438          * @return      mixed
 439          */
 440         function all_userdata()
 441         {
 442                 return ( ! isset($this->userdata)) ? FALSE : $this->userdata;
 443         }
 444
 445         // --------------------------------------------------------------------
 446
 447         /**
 448          * Add or change data in the "userdata" array
 449          *
 450          * @access      public
 451          * @param       mixed
 452          * @param       string
 453          * @return      void
 454          */
 455         function set_userdata($newdata = array(), $newval = '')
 456         {
 457                 if (is_string($newdata))
 458                 {
 459                         $newdata = array($newdata => $newval);
 460                 }
 461
 462                 if (count($newdata) > 0)
 463                 {
 464                         foreach ($newdata as $key => $val)
 465                         {
 466                                 $this->userdata[$key] = $val;
 467                         }
 468                 }
 469
 470                 $this->sess_write();
 471         }
 472
 473         // --------------------------------------------------------------------
 474
 475         /**
 476          * Delete a session variable from the "userdata" array
 477          *
 478          * @access      array
 479          * @return      void
 480          */
 481         function unset_userdata($newdata = array())
 482         {
 483                 if (is_string($newdata))
 484                 {
 485                         $newdata = array($newdata => '');
 486                 }
 487
 488                 if (count($newdata) > 0)
 489                 {
 490                         foreach ($newdata as $key => $val)
 491                         {
 492                                 unset($this->userdata[$key]);
 493                         }
 494                 }
 495
 496                 $this->sess_write();
 497         }
 498
 499         // ------------------------------------------------------------------------
 500
 501         /**
 502          * Add or change flashdata, only available
 503          * until the next request
 504          *
 505          * @access      public
 506          * @param       mixed
 507          * @param       string
 508          * @return      void
 509          */
 510         function set_flashdata($newdata = array(), $newval = '')
 511         {
 512                 if (is_string($newdata))
 513                 {
 514                         $newdata = array($newdata => $newval);
 515                 }
 516
 517                 if (count($newdata) > 0)
 518                 {
 519                         foreach ($newdata as $key => $val)
 520                         {
 521                                 $flashdata_key = $this->flashdata_key.':new:'.$key;
 522                                 $this->set_userdata($flashdata_key, $val);
 523                         }
 524                 }
 525         }
 526
 527         // ------------------------------------------------------------------------
 528
 529         /**
 530          * Keeps existing flashdata available to next request.
 531          *
 532          * @access      public
 533          * @param       string
 534          * @return      void
 535          */
 536         function keep_flashdata($key)
 537         {
 538                 // 'old' flashdata gets removed.  Here we mark all
 539                 // flashdata as 'new' to preserve it from _flashdata_sweep()
 540                 // Note the function will return FALSE if the $key
 541                 // provided cannot be found
 542                 $old_flashdata_key = $this->flashdata_key.':old:'.$key;
 543                 $value = $this->userdata($old_flashdata_key);
 544
 545                 $new_flashdata_key = $this->flashdata_key.':new:'.$key;
 546                 $this->set_userdata($new_flashdata_key, $value);
 547         }
 548
 549         // ------------------------------------------------------------------------
 550
 551         /**
 552          * Fetch a specific flashdata item from the session array
 553          *
 554          * @access      public
 555          * @param       string
 556          * @return      string
 557          */
 558         function flashdata($key)
 559         {
 560                 $flashdata_key = $this->flashdata_key.':old:'.$key;
 561                 return $this->userdata($flashdata_key);
 562         }
 563
 564         // ------------------------------------------------------------------------
 565
 566         /**
 567          * Identifies flashdata as 'old' for removal
 568          * when _flashdata_sweep() runs.
 569          *
 570          * @access      private
 571          * @return      void
 572          */
 573         function _flashdata_mark()
 574         {
 575                 $userdata = $this->all_userdata();
 576                 foreach ($userdata as $name => $value)
 577                 {
 578                         $parts = explode(':new:', $name);
 579                         if (is_array($parts) && count($parts) === 2)
 580                         {
 581                                 $new_name = $this->flashdata_key.':old:'.$parts[1];
 582                                 $this->set_userdata($new_name, $value);
 583                                 $this->unset_userdata($name);
 584                         }
 585                 }
 586         }
 587
 588         // ------------------------------------------------------------------------
 589
 590         /**
 591          * Removes all flashdata marked as 'old'
 592          *
 593          * @access      private
 594          * @return      void
 595          */
 596
 597         function _flashdata_sweep()
 598         {
 599                 $userdata = $this->all_userdata();
 600                 foreach ($userdata as $key => $value)
 601                 {
 602                         if (strpos($key, ':old:'))
 603                         {
 604                                 $this->unset_userdata($key);
 605                         }
 606                 }
 607
 608         }
 609
 610         // --------------------------------------------------------------------
 611
 612         /**
 613          * Get the "now" time
 614          *
 615          * @access      private
 616          * @return      string
 617          */
 618         function _get_time()
 619         {
 620                 if (strtolower($this->time_reference) == 'gmt')
 621                 {
 622                         $now = time();
 623                         $time = mktime(gmdate("H", $now), gmdate("i", $now), gmdate("s", $now), gmdate("m", $now), gmdate("d", $now), gmdate("Y", $now));
 624                 }
 625                 else
 626                 {
 627                         $time = time();
 628                 }
 629
 630                 return $time;
 631         }
 632
 633         // --------------------------------------------------------------------
 634
 635         /**
 636          * Write the session cookie
 637          *
 638          * @access      public
 639          * @return      void
 640          */
 641         function _set_cookie($cookie_data = NULL)
 642         {
 643                 if (is_null($cookie_data))
 644                 {
 645                         $cookie_data = $this->userdata;
 646                 }
 647
 648                 // Serialize the userdata for the cookie
 649                 $cookie_data = $this->_serialize($cookie_data);
 650
 651                 if ($this->sess_encrypt_cookie == TRUE)
 652                 {
 653                         $cookie_data = $this->CI->encrypt->encode($cookie_data);
 654                 }
 655                 else
 656                 {
 657                         // if encryption is not used, we provide an md5 hash to prevent userside tampering
 658                         $cookie_data = $cookie_data.md5($cookie_data.$this->encryption_key);
 659                 }
 660
 661                 $expire = ($this->sess_expire_on_close === TRUE) ? 0 : $this->sess_expiration + time();
 662
 663                 // Set the cookie
 664                 setcookie(
 665                                         $this->sess_cookie_name,
 666                                         $cookie_data,
 667                                         $expire,
 668                                         $this->cookie_path,
 669                                         $this->cookie_domain,
 670                                         $this->cookie_secure
 671                                 );
 672         }
 673
 674         // --------------------------------------------------------------------
 675
 676         /**
 677          * Serialize an array
 678          *
 679          * This function first converts any slashes found in the array to a temporary
 680          * marker, so when it gets unserialized the slashes will be preserved
 681          *
 682          * @access      private
 683          * @param       array
 684          * @return      string
 685          */
 686         function _serialize($data)
 687         {
 688                 if (is_array($data))
 689                 {
 690                         foreach ($data as $key => $val)
 691                         {
 692                                 if (is_string($val))
 693                                 {
 694                                         $data[$key] = str_replace('\\', '{{slash}}', $val);
 695                                 }
 696                         }
 697                 }
 698                 else
 699                 {
 700                         if (is_string($data))
 701                         {
 702                                 $data = str_replace('\\', '{{slash}}', $data);
 703                         }
 704                 }
 705
 706                 return serialize($data);
 707         }
 708
 709         // --------------------------------------------------------------------
 710
 711         /**
 712          * Unserialize
 713          *
 714          * This function unserializes a data string, then converts any
 715          * temporary slash markers back to actual slashes
 716          *
 717          * @access      private
 718          * @param       array
 719          * @return      string
 720          */
 721         function _unserialize($data)
 722         {
 723                 $data = @unserialize(strip_slashes($data));
 724
 725                 if (is_array($data))
 726                 {
 727                         foreach ($data as $key => $val)
 728                         {
 729                                 if (is_string($val))
 730                                 {
 731                                         $data[$key] = str_replace('{{slash}}', '\\', $val);
 732                                 }
 733                         }
 734
 735                         return $data;
 736                 }
 737
 738                 return (is_string($data)) ? str_replace('{{slash}}', '\\', $data) : $data;
 739         }
 740
 741         // --------------------------------------------------------------------
 742
 743         /**
 744          * Garbage collection
 745          *
 746          * This deletes expired session rows from database
 747          * if the probability percentage is met
 748          *
 749          * @access      public
 750          * @return      void
 751          */
 752         function _sess_gc()
 753         {
 754                 if ($this->sess_use_database != TRUE)
 755                 {
 756                         return;
 757                 }
 758
 759                 srand(time());
 760                 if ((rand() % 100) < $this->gc_probability)
 761                 {
 762                         $expire = $this->now - $this->sess_expiration;
 763
 764                         $this->CI->db->where("last_activity < {$expire}");
 765                         $this->CI->db->delete($this->sess_table_name);
 766
 767                         log_message('debug', 'Session garbage collection performed.');
 768                 }
 769         }
 770
 771
 772 }
 773 // END Session Class
 774
 775 /* End of file Session.php */
 776 /* Location: ./system/libraries/Session.php */