libraries/Input.php

   1 <?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');\r
   2 /**\r
   3  * CodeIgniter\r
   4  *\r
   5  * An open source application development framework for PHP 4.3.2 or newer\r
   6  *\r
   7  * @package             CodeIgniter\r
   8  * @author              ExpressionEngine Dev Team\r
   9  * @copyright   Copyright (c) 2008, EllisLab, Inc.\r
  10  * @license             http://codeigniter.com/user_guide/license.html\r
  11  * @link                http://codeigniter.com\r
  12  * @since               Version 1.0\r
  13  * @filesource\r
  14  */\r
  15 \r
  16 // ------------------------------------------------------------------------\r
  17 \r
  18 /**\r
  19  * Input Class\r
  20  *\r
  21  * Pre-processes global input data for security\r
  22  *\r
  23  * @package             CodeIgniter\r
  24  * @subpackage  Libraries\r
  25  * @category    Input\r
  26  * @author              ExpressionEngine Dev Team\r
  27  * @link                http://codeigniter.com/user_guide/libraries/input.html\r
  28  */\r
  29 class CI_Input {\r
  30         var $use_xss_clean              = FALSE;\r
  31         var $xss_hash                   = '';\r
  32         var $ip_address                 = FALSE;\r
  33         var $user_agent                 = FALSE;\r
  34         var $allow_get_array    = FALSE;\r
  35         \r
  36         /* never allowed, string replacement */\r
  37         var $never_allowed_str = array(\r
  38                                                                         'document.cookie'       => '[removed]',\r
  39                                                                         'document.write'        => '[removed]',\r
  40                                                                         '.parentNode'           => '[removed]',\r
  41                                                                         '.innerHTML'            => '[removed]',\r
  42                                                                         'window.location'       => '[removed]',\r
  43                                                                         '-moz-binding'          => '[removed]',\r
  44                                                                         '<!--'                          => '&lt;!--',\r
  45                                                                         '-->'                           => '--&gt;',\r
  46                                                                         '<![CDATA['                     => '&lt;![CDATA['\r
  47                                                                         );\r
  48         /* never allowed, regex replacement */\r
  49         var $never_allowed_regex = array(\r
  50                                                                                 "javascript\s*:"        => '[removed]',\r
  51                                                                                 "expression\s*\("       => '[removed]', // CSS and IE\r
  52                                                                                 "Redirect\s+302"        => '[removed]'\r
  53                                                                         );\r
  54                                 \r
  55         /**\r
  56          * Constructor\r
  57          *\r
  58          * Sets whether to globally enable the XSS processing\r
  59          * and whether to allow the $_GET array\r
  60          *\r
  61          * @access      public\r
  62          */\r
  63         function CI_Input()\r
  64         {\r
  65                 log_message('debug', "Input Class Initialized");\r
  66 \r
  67                 $CFG =& load_class('Config');\r
  68                 $this->use_xss_clean    = ($CFG->item('global_xss_filtering') === TRUE) ? TRUE : FALSE;\r
  69                 $this->allow_get_array  = ($CFG->item('enable_query_strings') === TRUE) ? TRUE : FALSE;\r
  70                 $this->_sanitize_globals();\r
  71         }\r
  72 \r
  73         // --------------------------------------------------------------------\r
  74 \r
  75         /**\r
  76          * Sanitize Globals\r
  77          *\r
  78          * This function does the following:\r
  79          *\r
  80          * Unsets $_GET data (if query strings are not enabled)\r
  81          *\r
  82          * Unsets all globals if register_globals is enabled\r
  83          *\r
  84          * Standardizes newline characters to \n\r
  85          *\r
  86          * @access      private\r
  87          * @return      void\r
  88          */\r
  89         function _sanitize_globals()\r
  90         {\r
  91                 // Would kind of be "wrong" to unset any of these GLOBALS\r
  92                 $protected = array('_SERVER', '_GET', '_POST', '_FILES', '_REQUEST', '_SESSION', '_ENV', 'GLOBALS', 'HTTP_RAW_POST_DATA',\r
  93                                                         'system_folder', 'application_folder', 'BM', 'EXT', 'CFG', 'URI', 'RTR', 'OUT', 'IN');\r
  94 \r
  95                 // Unset globals for security. \r
  96                 // This is effectively the same as register_globals = off\r
  97                 foreach (array($_GET, $_POST, $_COOKIE, $_SERVER, $_FILES, $_ENV, (isset($_SESSION) && is_array($_SESSION)) ? $_SESSION : array()) as $global)\r
  98                 {\r
  99                         if ( ! is_array($global))\r
 100                         {\r
 101                                 if ( ! in_array($global, $protected))\r
 102                                 {\r
 103                                         unset($GLOBALS[$global]);\r
 104                                 }\r
 105                         }\r
 106                         else\r
 107                         {\r
 108                                 foreach ($global as $key => $val)\r
 109                                 {\r
 110                                         if ( ! in_array($key, $protected))\r
 111                                         {\r
 112                                                 unset($GLOBALS[$key]);\r
 113                                         }\r
 114                         \r
 115                                         if (is_array($val))\r
 116                                         {\r
 117                                                 foreach($val as $k => $v)\r
 118                                                 {\r
 119                                                         if ( ! in_array($k, $protected))\r
 120                                                         {\r
 121                                                                 unset($GLOBALS[$k]);\r
 122                                                         }\r
 123                                                 }\r
 124                                         }\r
 125                                 }\r
 126                         }\r
 127                 }\r
 128 \r
 129                 // Is $_GET data allowed? If not we'll set the $_GET to an empty array\r
 130                 if ($this->allow_get_array == FALSE)\r
 131                 {\r
 132                         $_GET = array();\r
 133                 }\r
 134                 else\r
 135                 {\r
 136                         $_GET = $this->_clean_input_data($_GET);\r
 137                 }\r
 138 \r
 139                 // Clean $_POST Data\r
 140                 $_POST = $this->_clean_input_data($_POST);\r
 141                 \r
 142                 // Clean $_COOKIE Data\r
 143                 // Also get rid of specially treated cookies that might be set by a server\r
 144                 // or silly application, that are of no use to a CI application anyway\r
 145                 // but that when present will trip our 'Disallowed Key Characters' alarm\r
 146                 // http://www.ietf.org/rfc/rfc2109.txt\r
 147                 // note that the key names below are single quoted strings, and are not PHP variables\r
 148                 unset($_COOKIE['$Version']);\r
 149                 unset($_COOKIE['$Path']);\r
 150                 unset($_COOKIE['$Domain']);\r
 151                 $_COOKIE = $this->_clean_input_data($_COOKIE);\r
 152 \r
 153                 log_message('debug', "Global POST and COOKIE data sanitized");\r
 154         }\r
 155 \r
 156         // --------------------------------------------------------------------\r
 157 \r
 158         /**\r
 159          * Clean Input Data\r
 160          *\r
 161          * This is a helper function. It escapes data and\r
 162          * standardizes newline characters to \n\r
 163          *\r
 164          * @access      private\r
 165          * @param       string\r
 166          * @return      string\r
 167          */\r
 168         function _clean_input_data($str)\r
 169         {\r
 170                 if (is_array($str))\r
 171                 {\r
 172                         $new_array = array();\r
 173                         foreach ($str as $key => $val)\r
 174                         {\r
 175                                 $new_array[$this->_clean_input_keys($key)] = $this->_clean_input_data($val);\r
 176                         }\r
 177                         return $new_array;\r
 178                 }\r
 179 \r
 180                 // We strip slashes if magic quotes is on to keep things consistent\r
 181                 if (get_magic_quotes_gpc())\r
 182                 {\r
 183                         $str = stripslashes($str);\r
 184                 }\r
 185 \r
 186                 // Should we filter the input data?\r
 187                 if ($this->use_xss_clean === TRUE)\r
 188                 {\r
 189                         $str = $this->xss_clean($str);\r
 190                 }\r
 191 \r
 192                 // Standardize newlines\r
 193                 if (strpos($str, "\r") !== FALSE)\r
 194                 {\r
 195                         $str = str_replace(array("\r\n", "\r"), "\n", $str);\r
 196                 }\r
 197                 \r
 198                 return $str;\r
 199         }\r
 200 \r
 201         // --------------------------------------------------------------------\r
 202 \r
 203         /**\r
 204          * Clean Keys\r
 205          *\r
 206          * This is a helper function. To prevent malicious users\r
 207          * from trying to exploit keys we make sure that keys are\r
 208          * only named with alpha-numeric text and a few other items.\r
 209          *\r
 210          * @access      private\r
 211          * @param       string\r
 212          * @return      string\r
 213          */\r
 214         function _clean_input_keys($str)\r
 215         {\r
 216                  if ( ! preg_match("/^[a-z0-9:_\/-]+$/i", $str))\r
 217                  {\r
 218                         exit('Disallowed Key Characters.');\r
 219                  }\r
 220 \r
 221                 return $str;\r
 222         }\r
 223 \r
 224         // --------------------------------------------------------------------\r
 225         \r
 226         /**\r
 227          * Fetch from array\r
 228          *\r
 229          * This is a helper function to retrieve values from global arrays\r
 230          *\r
 231          * @access      private\r
 232          * @param       array\r
 233          * @param       string\r
 234          * @param       bool\r
 235          * @return      string\r
 236          */\r
 237         function _fetch_from_array(&$array, $index = '', $xss_clean = FALSE)\r
 238         {\r
 239                 if ( ! isset($array[$index]))\r
 240                 {\r
 241                         return FALSE;\r
 242                 }\r
 243 \r
 244                 if ($xss_clean === TRUE)\r
 245                 {\r
 246                         return $this->xss_clean($array[$index]);\r
 247                 }\r
 248 \r
 249                 return $array[$index];\r
 250         }\r
 251 \r
 252         // --------------------------------------------------------------------\r
 253         \r
 254         /**\r
 255          * Fetch an item from the GET array\r
 256          *\r
 257          * @access      public\r
 258          * @param       string\r
 259          * @param       bool\r
 260          * @return      string\r
 261          */\r
 262         function get($index = '', $xss_clean = FALSE)\r
 263         {\r
 264                 return $this->_fetch_from_array($_GET, $index, $xss_clean);\r
 265         }\r
 266 \r
 267         // --------------------------------------------------------------------\r
 268 \r
 269         /**\r
 270          * Fetch an item from the POST array\r
 271          *\r
 272          * @access      public\r
 273          * @param       string\r
 274          * @param       bool\r
 275          * @return      string\r
 276          */\r
 277         function post($index = '', $xss_clean = FALSE)\r
 278         {\r
 279                 return $this->_fetch_from_array($_POST, $index, $xss_clean);\r
 280         }\r
 281 \r
 282         // --------------------------------------------------------------------\r
 283 \r
 284         /**\r
 285          * Fetch an item from either the GET array or the POST\r
 286          *\r
 287          * @access      public\r
 288          * @param       string  The index key\r
 289          * @param       bool    XSS cleaning\r
 290          * @return      string\r
 291          */\r
 292         function get_post($index = '', $xss_clean = FALSE)\r
 293         {               \r
 294                 if ( ! isset($_POST[$index]) )\r
 295                 {\r
 296                         return $this->get($index, $xss_clean);\r
 297                 }\r
 298                 else\r
 299                 {\r
 300                         return $this->post($index, $xss_clean);\r
 301                 }               \r
 302         }\r
 303 \r
 304         // --------------------------------------------------------------------\r
 305 \r
 306         /**\r
 307          * Fetch an item from the COOKIE array\r
 308          *\r
 309          * @access      public\r
 310          * @param       string\r
 311          * @param       bool\r
 312          * @return      string\r
 313          */\r
 314         function cookie($index = '', $xss_clean = FALSE)\r
 315         {\r
 316                 return $this->_fetch_from_array($_COOKIE, $index, $xss_clean);\r
 317         }\r
 318 \r
 319         // --------------------------------------------------------------------\r
 320 \r
 321         /**\r
 322          * Fetch an item from the SERVER array\r
 323          *\r
 324          * @access      public\r
 325          * @param       string\r
 326          * @param       bool\r
 327          * @return      string\r
 328          */\r
 329         function server($index = '', $xss_clean = FALSE)\r
 330         {\r
 331                 return $this->_fetch_from_array($_SERVER, $index, $xss_clean);\r
 332         }\r
 333 \r
 334         // --------------------------------------------------------------------\r
 335 \r
 336         /**\r
 337          * Fetch the IP Address\r
 338          *\r
 339          * @access      public\r
 340          * @return      string\r
 341          */\r
 342         function ip_address()\r
 343         {\r
 344                 if ($this->ip_address !== FALSE)\r
 345                 {\r
 346                         return $this->ip_address;\r
 347                 }\r
 348 \r
 349                 if ($this->server('REMOTE_ADDR') AND $this->server('HTTP_CLIENT_IP'))\r
 350                 {\r
 351                          $this->ip_address = $_SERVER['HTTP_CLIENT_IP'];\r
 352                 }\r
 353                 elseif ($this->server('REMOTE_ADDR'))\r
 354                 {\r
 355                          $this->ip_address = $_SERVER['REMOTE_ADDR'];\r
 356                 }\r
 357                 elseif ($this->server('HTTP_CLIENT_IP'))\r
 358                 {\r
 359                          $this->ip_address = $_SERVER['HTTP_CLIENT_IP'];\r
 360                 }\r
 361                 elseif ($this->server('HTTP_X_FORWARDED_FOR'))\r
 362                 {\r
 363                          $this->ip_address = $_SERVER['HTTP_X_FORWARDED_FOR'];\r
 364                 }\r
 365 \r
 366                 if ($this->ip_address === FALSE)\r
 367                 {\r
 368                         $this->ip_address = '0.0.0.0';\r
 369                         return $this->ip_address;\r
 370                 }\r
 371 \r
 372                 if (strstr($this->ip_address, ','))\r
 373                 {\r
 374                         $x = explode(',', $this->ip_address);\r
 375                         $this->ip_address = end($x);\r
 376                 }\r
 377 \r
 378                 if ( ! $this->valid_ip($this->ip_address))\r
 379                 {\r
 380                         $this->ip_address = '0.0.0.0';\r
 381                 }\r
 382                 \r
 383                 return $this->ip_address;\r
 384         }\r
 385 \r
 386         // --------------------------------------------------------------------\r
 387 \r
 388         /**\r
 389          * Validate IP Address\r
 390          *\r
 391          * Updated version suggested by Geert De Deckere\r
 392          * \r
 393          * @access      public\r
 394          * @param       string\r
 395          * @return      string\r
 396          */\r
 397         function valid_ip($ip)\r
 398         {\r
 399                 $ip_segments = explode('.', $ip);\r
 400 \r
 401                 // Always 4 segments needed\r
 402                 if (count($ip_segments) != 4)\r
 403                 {\r
 404                         return FALSE;\r
 405                 }\r
 406                 // IP can not start with 0\r
 407                 if ($ip_segments[0][0] == '0')\r
 408                 {\r
 409                         return FALSE;\r
 410                 }\r
 411                 // Check each segment\r
 412                 foreach ($ip_segments as $segment)\r
 413                 {\r
 414                         // IP segments must be digits and can not be \r
 415                         // longer than 3 digits or greater then 255\r
 416                         if ($segment == '' OR preg_match("/[^0-9]/", $segment) OR $segment > 255 OR strlen($segment) > 3)\r
 417                         {\r
 418                                 return FALSE;\r
 419                         }\r
 420                 }\r
 421 \r
 422                 return TRUE;\r
 423         }\r
 424 \r
 425         // --------------------------------------------------------------------\r
 426 \r
 427         /**\r
 428          * User Agent\r
 429          *\r
 430          * @access      public\r
 431          * @return      string\r
 432          */\r
 433         function user_agent()\r
 434         {\r
 435                 if ($this->user_agent !== FALSE)\r
 436                 {\r
 437                         return $this->user_agent;\r
 438                 }\r
 439 \r
 440                 $this->user_agent = ( ! isset($_SERVER['HTTP_USER_AGENT'])) ? FALSE : $_SERVER['HTTP_USER_AGENT'];\r
 441 \r
 442                 return $this->user_agent;\r
 443         }\r
 444 \r
 445         // --------------------------------------------------------------------\r
 446 \r
 447         /**\r
 448          * Filename Security\r
 449          *\r
 450          * @access      public\r
 451          * @param       string\r
 452          * @return      string\r
 453          */\r
 454         function filename_security($str)\r
 455         {\r
 456                 $bad = array(\r
 457                                                 "../",\r
 458                                                 "./",\r
 459                                                 "<!--",\r
 460                                                 "-->",\r
 461                                                 "<",\r
 462                                                 ">",\r
 463                                                 "'",\r
 464                                                 '"',\r
 465                                                 '&',\r
 466                                                 '$',\r
 467                                                 '#',\r
 468                                                 '{',\r
 469                                                 '}',\r
 470                                                 '[',\r
 471                                                 ']',\r
 472                                                 '=',\r
 473                                                 ';',\r
 474                                                 '?',\r
 475                                                 "%20",\r
 476                                                 "%22",\r
 477                                                 "%3c",          // <\r
 478                                                 "%253c",        // <\r
 479                                                 "%3e",          // >\r
 480                                                 "%0e",          // >\r
 481                                                 "%28",          // (  \r
 482                                                 "%29",          // ) \r
 483                                                 "%2528",        // (\r
 484                                                 "%26",          // &\r
 485                                                 "%24",          // $\r
 486                                                 "%3f",          // ?\r
 487                                                 "%3b",          // ;\r
 488                                                 "%3d"           // =\r
 489                                         );\r
 490 \r
 491                 return stripslashes(str_replace($bad, '', $str));\r
 492         }\r
 493 \r
 494         // --------------------------------------------------------------------\r
 495 \r
 496         /**\r
 497          * XSS Clean\r
 498          *\r
 499          * Sanitizes data so that Cross Site Scripting Hacks can be\r
 500          * prevented.  This function does a fair amount of work but\r
 501          * it is extremely thorough, designed to prevent even the\r
 502          * most obscure XSS attempts.  Nothing is ever 100% foolproof,\r
 503          * of course, but I haven't been able to get anything passed\r
 504          * the filter.\r
 505          *\r
 506          * Note: This function should only be used to deal with data\r
 507          * upon submission.  It's not something that should\r
 508          * be used for general runtime processing.\r
 509          *\r
 510          * This function was based in part on some code and ideas I\r
 511          * got from Bitflux: http://blog.bitflux.ch/wiki/XSS_Prevention\r
 512          *\r
 513          * To help develop this script I used this great list of\r
 514          * vulnerabilities along with a few other hacks I've\r
 515          * harvested from examining vulnerabilities in other programs:\r
 516          * http://ha.ckers.org/xss.html\r
 517          *\r
 518          * @access      public\r
 519          * @param       string\r
 520          * @return      string\r
 521          */\r
 522         function xss_clean($str, $is_image = FALSE)\r
 523         {\r
 524                 /*\r
 525                  * Is the string an array?\r
 526                  *\r
 527                  */\r
 528                 if (is_array($str))\r
 529                 {\r
 530                         while (list($key) = each($str))\r
 531                         {\r
 532                                 $str[$key] = $this->xss_clean($str[$key]);\r
 533                         }\r
 534         \r
 535                         return $str;\r
 536                 }\r
 537 \r
 538                 /*\r
 539                  * Remove Invisible Characters\r
 540                  */\r
 541                 $str = $this->_remove_invisible_characters($str);\r
 542 \r
 543                 /*\r
 544                  * Protect GET variables in URLs\r
 545                  */\r
 546                  \r
 547                  // 901119URL5918AMP18930PROTECT8198\r
 548                  \r
 549                 $str = preg_replace('|\&([a-z\_0-9]+)\=([a-z\_0-9]+)|i', $this->xss_hash()."\\1=\\2", $str);\r
 550 \r
 551                 /*\r
 552                  * Validate standard character entities\r
 553                  *\r
 554                  * Add a semicolon if missing.  We do this to enable\r
 555                  * the conversion of entities to ASCII later.\r
 556                  *\r
 557                  */\r
 558                 $str = preg_replace('#(&\#?[0-9a-z]{2,})[\x00-\x20]*;?#i', "\\1;", $str);\r
 559 \r
 560                 /*\r
 561                  * Validate UTF16 two byte encoding (x00) \r
 562                  *\r
 563                  * Just as above, adds a semicolon if missing.\r
 564                  *\r
 565                  */\r
 566                 $str = preg_replace('#(&\#x?)([0-9A-F]+);?#i',"\\1\\2;",$str);\r
 567 \r
 568                 /*\r
 569                  * Un-Protect GET variables in URLs\r
 570                  */\r
 571                 $str = str_replace($this->xss_hash(), '&', $str);\r
 572 \r
 573                 /*\r
 574                  * URL Decode\r
 575                  *\r
 576                  * Just in case stuff like this is submitted:\r
 577                  *\r
 578                  * <a href="http://%77%77%77%2E%67%6F%6F%67%6C%65%2E%63%6F%6D">Google</a>\r
 579                  *\r
 580                  * Note: Use rawurldecode() so it does not remove plus signs\r
 581                  *\r
 582                  */\r
 583                 $str = rawurldecode($str);\r
 584         \r
 585                 /*\r
 586                  * Convert character entities to ASCII \r
 587                  *\r
 588                  * This permits our tests below to work reliably.\r
 589                  * We only convert entities that are within tags since\r
 590                  * these are the ones that will pose security problems.\r
 591                  *\r
 592                  */\r
 593 \r
 594                 $str = preg_replace_callback("/[a-z]+=([\'\"]).*?\\1/si", array($this, '_convert_attribute'), $str);\r
 595          \r
 596                 $str = preg_replace_callback("/<\w+.*?(?=>|<|$)/si", array($this, '_html_entity_decode_callback'), $str);\r
 597 \r
 598                 /*\r
 599                  * Remove Invisible Characters Again!\r
 600                  */\r
 601                 $str = $this->_remove_invisible_characters($str);\r
 602                 \r
 603                 /*\r
 604                  * Convert all tabs to spaces\r
 605                  *\r
 606                  * This prevents strings like this: ja  vascript\r
 607                  * NOTE: we deal with spaces between characters later.\r
 608                  * NOTE: preg_replace was found to be amazingly slow here on large blocks of data,\r
 609                  * so we use str_replace.\r
 610                  *\r
 611                  */\r
 612                 \r
 613                 if (strpos($str, "\t") !== FALSE)\r
 614                 {\r
 615                         $str = str_replace("\t", ' ', $str);\r
 616                 }\r
 617                 \r
 618                 /*\r
 619                  * Capture converted string for later comparison\r
 620                  */\r
 621                 $converted_string = $str;\r
 622                 \r
 623                 /*\r
 624                  * Not Allowed Under Any Conditions\r
 625                  */\r
 626                 \r
 627                 foreach ($this->never_allowed_str as $key => $val)\r
 628                 {\r
 629                         $str = str_replace($key, $val, $str);   \r
 630                 }\r
 631         \r
 632                 foreach ($this->never_allowed_regex as $key => $val)\r
 633                 {\r
 634                         $str = preg_replace("#".$key."#i", $val, $str);   \r
 635                 }\r
 636 \r
 637                 /*\r
 638                  * Makes PHP tags safe\r
 639                  *\r
 640                  *  Note: XML tags are inadvertently replaced too:\r
 641                  *\r
 642                  *      <?xml\r
 643                  *\r
 644                  * But it doesn't seem to pose a problem.\r
 645                  *\r
 646                  */\r
 647                 if ($is_image === TRUE)\r
 648                 {\r
 649                         // Images have a tendency to have the PHP short opening and closing tags every so often\r
 650                         // so we skip those and only do the long opening tags.\r
 651                         $str = str_replace(array('<?php', '<?PHP'),  array('&lt;?php', '&lt;?PHP'), $str);\r
 652                 }\r
 653                 else\r
 654                 {\r
 655                         $str = str_replace(array('<?php', '<?PHP', '<?', '?'.'>'),  array('&lt;?php', '&lt;?PHP', '&lt;?', '?&gt;'), $str);\r
 656                 }\r
 657                 \r
 658                 /*\r
 659                  * Compact any exploded words\r
 660                  *\r
 661                  * This corrects words like:  j a v a s c r i p t\r
 662                  * These words are compacted back to their correct state.\r
 663                  *\r
 664                  */\r
 665                 $words = array('javascript', 'expression', 'vbscript', 'script', 'applet', 'alert', 'document', 'write', 'cookie', 'window');\r
 666                 foreach ($words as $word)\r
 667                 {\r
 668                         $temp = '';\r
 669                         \r
 670                         for ($i = 0, $wordlen = strlen($word); $i < $wordlen; $i++)\r
 671                         {\r
 672                                 $temp .= substr($word, $i, 1)."\s*";\r
 673                         }\r
 674 \r
 675                         // We only want to do this when it is followed by a non-word character\r
 676                         // That way valid stuff like "dealer to" does not become "dealerto"\r
 677                         $str = preg_replace_callback('#('.substr($temp, 0, -3).')(\W)#is', array($this, '_compact_exploded_words'), $str);\r
 678                 }\r
 679                 \r
 680                 /*\r
 681                  * Remove disallowed Javascript in links or img tags\r
 682                  * We used to do some version comparisons and use of stripos for PHP5, but it is dog slow compared\r
 683                  * to these simplified non-capturing preg_match(), especially if the pattern exists in the string\r
 684                  */\r
 685                 do\r
 686                 {\r
 687                         $original = $str;\r
 688         \r
 689                         if (preg_match("/<a/i", $str))\r
 690                         {\r
 691                                 $str = preg_replace_callback("#<a\s+([^>]*?)(>|$)#si", array($this, '_js_link_removal'), $str);\r
 692                         }\r
 693         \r
 694                         if (preg_match("/<img/i", $str))\r
 695                         {\r
 696                                 $str = preg_replace_callback("#<img\s+([^>]*?)(\s?/?>|$)#si", array($this, '_js_img_removal'), $str);\r
 697                         }\r
 698         \r
 699                         if (preg_match("/script/i", $str) OR preg_match("/xss/i", $str))\r
 700                         {\r
 701                                 $str = preg_replace("#<(/*)(script|xss)(.*?)\>#si", '[removed]', $str);\r
 702                         }\r
 703                 }\r
 704                 while($original != $str);\r
 705 \r
 706                 unset($original);\r
 707 \r
 708                 /*\r
 709                  * Remove JavaScript Event Handlers\r
 710                  *\r
 711                  * Note: This code is a little blunt.  It removes\r
 712                  * the event handler and anything up to the closing >,\r
 713                  * but it's unlikely to be a problem.\r
 714                  *\r
 715                  */\r
 716                 $event_handlers = array('[^a-z_\-]on\w*','xmlns');\r
 717 \r
 718                 if ($is_image === TRUE)\r
 719                 {\r
 720                         /*\r
 721                          * Adobe Photoshop puts XML metadata into JFIF images, including namespacing, \r
 722                          * so we have to allow this for images. -Paul\r
 723                          */\r
 724                         unset($event_handlers[array_search('xmlns', $event_handlers)]);\r
 725                 }\r
 726 \r
 727                 $str = preg_replace("#<([^><]+?)(".implode('|', $event_handlers).")(\s*=\s*[^><]*)([><]*)#i", "<\\1\\4", $str);\r
 728 \r
 729                 /*\r
 730                  * Sanitize naughty HTML elements\r
 731                  *\r
 732                  * If a tag containing any of the words in the list\r
 733                  * below is found, the tag gets converted to entities.\r
 734                  *\r
 735                  * So this: <blink>\r
 736                  * Becomes: &lt;blink&gt;\r
 737                  *\r
 738                  */\r
 739                 $naughty = 'alert|applet|audio|basefont|base|behavior|bgsound|blink|body|embed|expression|form|frameset|frame|head|html|ilayer|iframe|input|isindex|layer|link|meta|object|plaintext|style|script|textarea|title|video|xml|xss';\r
 740                 $str = preg_replace_callback('#<(/*\s*)('.$naughty.')([^><]*)([><]*)#is', array($this, '_sanitize_naughty_html'), $str);\r
 741 \r
 742                 /*\r
 743                  * Sanitize naughty scripting elements\r
 744                  *\r
 745                  * Similar to above, only instead of looking for\r
 746                  * tags it looks for PHP and JavaScript commands\r
 747                  * that are disallowed.  Rather than removing the\r
 748                  * code, it simply converts the parenthesis to entities\r
 749                  * rendering the code un-executable.\r
 750                  *\r
 751                  * For example: eval('some code')\r
 752                  * Becomes:             eval&#40;'some code'&#41;\r
 753                  *\r
 754                  */\r
 755                 $str = preg_replace('#(alert|cmd|passthru|eval|exec|expression|system|fopen|fsockopen|file|file_get_contents|readfile|unlink)(\s*)\((.*?)\)#si', "\\1\\2&#40;\\3&#41;", $str);\r
 756                                         \r
 757                 /*\r
 758                  * Final clean up\r
 759                  *\r
 760                  * This adds a bit of extra precaution in case\r
 761                  * something got through the above filters\r
 762                  *\r
 763                  */\r
 764                 foreach ($this->never_allowed_str as $key => $val)\r
 765                 {\r
 766                         $str = str_replace($key, $val, $str);   \r
 767                 }\r
 768         \r
 769                 foreach ($this->never_allowed_regex as $key => $val)\r
 770                 {\r
 771                         $str = preg_replace("#".$key."#i", $val, $str);\r
 772                 }\r
 773 \r
 774                 /*\r
 775                  *  Images are Handled in a Special Way\r
 776                  *  - Essentially, we want to know that after all of the character conversion is done whether\r
 777                  *  any unwanted, likely XSS, code was found.  If not, we return TRUE, as the image is clean.\r
 778                  *  However, if the string post-conversion does not matched the string post-removal of XSS,\r
 779                  *  then it fails, as there was unwanted XSS code found and removed/changed during processing.\r
 780                  */\r
 781 \r
 782                 if ($is_image === TRUE)\r
 783                 {\r
 784                         if ($str == $converted_string)\r
 785                         {\r
 786                                 return TRUE;\r
 787                         }\r
 788                         else\r
 789                         {\r
 790                                 return FALSE;\r
 791                         }\r
 792                 }\r
 793                 \r
 794                 log_message('debug', "XSS Filtering completed");\r
 795                 return $str;\r
 796         }\r
 797 \r
 798         // --------------------------------------------------------------------\r
 799 \r
 800         /**\r
 801          * Random Hash for protecting URLs\r
 802          *\r
 803          * @access      public\r
 804          * @return      string\r
 805          */\r
 806         function xss_hash()\r
 807         {\r
 808                 if ($this->xss_hash == '')\r
 809                 {\r
 810                         if (phpversion() >= 4.2)\r
 811                                 mt_srand();\r
 812                         else\r
 813                                 mt_srand(hexdec(substr(md5(microtime()), -8)) & 0x7fffffff);\r
 814 \r
 815                         $this->xss_hash = md5(time() + mt_rand(0, 1999999999));\r
 816                 }\r
 817 \r
 818                 return $this->xss_hash;\r
 819         }\r
 820 \r
 821         // --------------------------------------------------------------------\r
 822         \r
 823         /**\r
 824          * Remove Invisible Characters\r
 825          *\r
 826          * This prevents sandwiching null characters\r
 827          * between ascii characters, like Java\0script.\r
 828          *\r
 829          * @access      public\r
 830          * @param       string\r
 831          * @return      string\r
 832          */\r
 833         function _remove_invisible_characters($str)\r
 834         {\r
 835                 static $non_displayables;\r
 836                 \r
 837                 if ( ! isset($non_displayables))\r
 838                 {\r
 839                         // every control character except newline (dec 10), carriage return (dec 13), and horizontal tab (dec 09),\r
 840                         $non_displayables = array(\r
 841                                                                                 '/%0[0-8bcef]/',                        // url encoded 00-08, 11, 12, 14, 15\r
 842                                                                                 '/%1[0-9a-f]/',                         // url encoded 16-31\r
 843                                                                                 '/[\x00-\x08]/',                        // 00-08\r
 844                                                                                 '/\x0b/', '/\x0c/',                     // 11, 12\r
 845                                                                                 '/[\x0e-\x1f]/'                         // 14-31\r
 846                                                                         );\r
 847                 }\r
 848 \r
 849                 do\r
 850                 {\r
 851                         $cleaned = $str;\r
 852                         $str = preg_replace($non_displayables, '', $str);\r
 853                 }\r
 854                 while ($cleaned != $str);\r
 855 \r
 856                 return $str;\r
 857         }\r
 858 \r
 859         // --------------------------------------------------------------------\r
 860         \r
 861         /**\r
 862          * Compact Exploded Words\r
 863          *\r
 864          * Callback function for xss_clean() to remove whitespace from\r
 865          * things like j a v a s c r i p t\r
 866          *\r
 867          * @access      public\r
 868          * @param       type\r
 869          * @return      type\r
 870          */\r
 871         function _compact_exploded_words($matches)\r
 872         {\r
 873                 return preg_replace('/\s+/s', '', $matches[1]).$matches[2];\r
 874         }\r
 875 \r
 876         // --------------------------------------------------------------------\r
 877         \r
 878         /**\r
 879          * Sanitize Naughty HTML\r
 880          *\r
 881          * Callback function for xss_clean() to remove naughty HTML elements\r
 882          *\r
 883          * @access      private\r
 884          * @param       array\r
 885          * @return      string\r
 886          */\r
 887         function _sanitize_naughty_html($matches)\r
 888         {\r
 889                 // encode opening brace\r
 890                 $str = '&lt;'.$matches[1].$matches[2].$matches[3];\r
 891                 \r
 892                 // encode captured opening or closing brace to prevent recursive vectors\r
 893                 $str .= str_replace(array('>', '<'), array('&gt;', '&lt;'), $matches[4]);\r
 894                 \r
 895                 return $str;\r
 896         }\r
 897 \r
 898         // --------------------------------------------------------------------\r
 899         \r
 900         /**\r
 901          * JS Link Removal\r
 902          *\r
 903          * Callback function for xss_clean() to sanitize links\r
 904          * This limits the PCRE backtracks, making it more performance friendly\r
 905          * and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in\r
 906          * PHP 5.2+ on link-heavy strings\r
 907          *\r
 908          * @access      private\r
 909          * @param       array\r
 910          * @return      string\r
 911          */\r
 912         function _js_link_removal($match)\r
 913         {\r
 914                 $attributes = $this->_filter_attributes(str_replace(array('<', '>'), '', $match[1]));\r
 915                 return str_replace($match[1], preg_replace("#href=.*?(alert\(|alert&\#40;|javascript\:|charset\=|window\.|document\.|\.cookie|<script|<xss|base64\s*,)#si", "", $attributes), $match[0]);\r
 916         }\r
 917 \r
 918         /**\r
 919          * JS Image Removal\r
 920          *\r
 921          * Callback function for xss_clean() to sanitize image tags\r
 922          * This limits the PCRE backtracks, making it more performance friendly\r
 923          * and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in\r
 924          * PHP 5.2+ on image tag heavy strings\r
 925          *\r
 926          * @access      private\r
 927          * @param       array\r
 928          * @return      string\r
 929          */\r
 930         function _js_img_removal($match)\r
 931         {\r
 932                 $attributes = $this->_filter_attributes(str_replace(array('<', '>'), '', $match[1]));\r
 933                 return str_replace($match[1], preg_replace("#src=.*?(alert\(|alert&\#40;|javascript\:|charset\=|window\.|document\.|\.cookie|<script|<xss|base64\s*,)#si", "", $attributes), $match[0]);\r
 934         }\r
 935 \r
 936         // --------------------------------------------------------------------\r
 937 \r
 938         /**\r
 939          * Attribute Conversion\r
 940          *\r
 941          * Used as a callback for XSS Clean\r
 942          *\r
 943          * @access      public\r
 944          * @param       array\r
 945          * @return      string\r
 946          */\r
 947         function _convert_attribute($match)\r
 948         {\r
 949                 return str_replace(array('>', '<'), array('&gt;', '&lt;'), $match[0]);\r
 950         }\r
 951 \r
 952         // --------------------------------------------------------------------\r
 953 \r
 954         /**\r
 955          * HTML Entity Decode Callback\r
 956          *\r
 957          * Used as a callback for XSS Clean\r
 958          *\r
 959          * @access      public\r
 960          * @param       array\r
 961          * @return      string\r
 962          */\r
 963         function _html_entity_decode_callback($match)\r
 964         {\r
 965                 $CFG =& load_class('Config');\r
 966                 $charset = $CFG->item('charset');\r
 967 \r
 968                 return $this->_html_entity_decode($match[0], strtoupper($charset));\r
 969         }\r
 970 \r
 971         // --------------------------------------------------------------------\r
 972 \r
 973         /**\r
 974          * HTML Entities Decode\r
 975          *\r
 976          * This function is a replacement for html_entity_decode()\r
 977          *\r
 978          * In some versions of PHP the native function does not work\r
 979          * when UTF-8 is the specified character set, so this gives us\r
 980          * a work-around.  More info here:\r
 981          * http://bugs.php.net/bug.php?id=25670\r
 982          *\r
 983          * @access      private\r
 984          * @param       string\r
 985          * @param       string\r
 986          * @return      string\r
 987          */\r
 988         /* -------------------------------------------------\r
 989         /*  Replacement for html_entity_decode()\r
 990         /* -------------------------------------------------*/\r
 991 \r
 992         /*\r
 993         NOTE: html_entity_decode() has a bug in some PHP versions when UTF-8 is the\r
 994         character set, and the PHP developers said they were not back porting the\r
 995         fix to versions other than PHP 5.x.\r
 996         */\r
 997         function _html_entity_decode($str, $charset='UTF-8')\r
 998         {\r
 999                 if (stristr($str, '&') === FALSE) return $str;\r
1000 \r
1001                 // The reason we are not using html_entity_decode() by itself is because\r
1002                 // while it is not technically correct to leave out the semicolon\r
1003                 // at the end of an entity most browsers will still interpret the entity\r
1004                 // correctly.  html_entity_decode() does not convert entities without\r
1005                 // semicolons, so we are left with our own little solution here. Bummer.\r
1006 \r
1007                 if (function_exists('html_entity_decode') && (strtolower($charset) != 'utf-8' OR version_compare(phpversion(), '5.0.0', '>=')))\r
1008                 {\r
1009                         $str = html_entity_decode($str, ENT_COMPAT, $charset);\r
1010                         $str = preg_replace('~&#x(0*[0-9a-f]{2,5})~ei', 'chr(hexdec("\\1"))', $str);\r
1011                         return preg_replace('~&#([0-9]{2,4})~e', 'chr(\\1)', $str);\r
1012                 }\r
1013 \r
1014                 // Numeric Entities\r
1015                 $str = preg_replace('~&#x(0*[0-9a-f]{2,5});{0,1}~ei', 'chr(hexdec("\\1"))', $str);\r
1016                 $str = preg_replace('~&#([0-9]{2,4});{0,1}~e', 'chr(\\1)', $str);\r
1017 \r
1018                 // Literal Entities - Slightly slow so we do another check\r
1019                 if (stristr($str, '&') === FALSE)\r
1020                 {\r
1021                         $str = strtr($str, array_flip(get_html_translation_table(HTML_ENTITIES)));\r
1022                 }\r
1023 \r
1024                 return $str;\r
1025         }\r
1026 \r
1027         // --------------------------------------------------------------------\r
1028         \r
1029         /**\r
1030          * Filter Attributes\r
1031          *\r
1032          * Filters tag attributes for consistency and safety\r
1033          *\r
1034          * @access      public\r
1035          * @param       string\r
1036          * @return      string\r
1037          */\r
1038         function _filter_attributes($str)\r
1039         {\r
1040                 $out = '';\r
1041 \r
1042                 if (preg_match_all('#\s*[a-z\-]+\s*=\s*(\042|\047)([^\\1]*?)\\1#is', $str, $matches))\r
1043                 {\r
1044                         foreach ($matches[0] as $match)\r
1045                         {\r
1046                                 $out .= "{$match}";\r
1047                         }                       \r
1048                 }\r
1049 \r
1050                 return $out;\r
1051         }\r
1052 \r
1053         // --------------------------------------------------------------------\r
1054 \r
1055 }\r
1056 // END Input class\r
1057 \r
1058 /* End of file Input.php */\r
1059 /* Location: ./system/libraries/Input.php */