path: root/system/libraries/Input.php

<?php defined('SYSPATH') OR die('No direct access allowed.');
/**
 * Input library.
 *
 * $Id: Input.php 4346 2009-05-11 17:08:15Z zombor $
 *
 * @package    Core
 * @author     Kohana Team
 * @copyright  (c) 2007-2008 Kohana Team
 * @license    http://kohanaphp.com/license.html
 */
class Input_Core {

	// Enable or disable automatic XSS cleaning
	protected $use_xss_clean = FALSE;

	// Are magic quotes enabled?
	protected $magic_quotes_gpc = FALSE;

	// IP address of current user
	public $ip_address;

	// Input singleton
	protected static $instance;

	/**
	 * Retrieve a singleton instance of Input. This will always be the first
	 * created instance of this class.
	 *
	 * @return  object
	 */
	public static function instance()
	{
		if (Input::$instance === NULL)
		{
			// Create a new instance
			return new Input;
		}

		return Input::$instance;
	}

	/**
	 * Sanitizes global GET, POST and COOKIE data. Also takes care of
	 * magic_quotes and register_globals, if they have been enabled.
	 *
	 * @return  void
	 */
	public function __construct()
	{
		// Use XSS clean?
		$this->use_xss_clean = (bool) Kohana::config('core.global_xss_filtering');

		if (Input::$instance === NULL)
		{
			// magic_quotes_runtime is enabled
			if (get_magic_quotes_runtime())
			{
				set_magic_quotes_runtime(0);
				Kohana::log('debug', 'Disable magic_quotes_runtime! It is evil and deprecated: http://php.net/magic_quotes');
			}

			// magic_quotes_gpc is enabled
			if (get_magic_quotes_gpc())
			{
				$this->magic_quotes_gpc = TRUE;
				Kohana::log('debug', 'Disable magic_quotes_gpc! It is evil and deprecated: http://php.net/magic_quotes');
			}

			// register_globals is enabled
			if (ini_get('register_globals'))
			{
				if (isset($_REQUEST['GLOBALS']))
				{
					// Prevent GLOBALS override attacks
					exit('Global variable overload attack.');
				}

				// Destroy the REQUEST global
				$_REQUEST = array();

				// These globals are standard and should not be removed
				$preserve = array('GLOBALS', '_REQUEST', '_GET', '_POST', '_FILES', '_COOKIE', '_SERVER', '_ENV', '_SESSION');

				// This loop has the same effect as disabling register_globals
				foreach (array_diff(array_keys($GLOBALS), $preserve) as $key)
				{
					global $$key;
					$$key = NULL;

					// Unset the global variable
					unset($GLOBALS[$key], $$key);
				}

				// Warn the developer about register globals
				Kohana::log('debug', 'Disable register_globals! It is evil and deprecated: http://php.net/register_globals');
			}

			if (is_array($_GET))
			{
				foreach ($_GET as $key => $val)
				{
					// Sanitize $_GET
					$_GET[$this->clean_input_keys($key)] = $this->clean_input_data($val);
				}
			}
			else
			{
				$_GET = array();
			}

			if (is_array($_POST))
			{
				foreach ($_POST as $key => $val)
				{
					// Sanitize $_POST
					$_POST[$this->clean_input_keys($key)] = $this->clean_input_data($val);
				}
			}
			else
			{
				$_POST = array();
			}

			if (is_array($_COOKIE))
			{
				foreach ($_COOKIE as $key => $val)
				{
					// Ignore special attributes in RFC2109 compliant cookies
					if ($key == '$Version' OR $key == '$Path' OR $key == '$Domain')
						continue;

					// Sanitize $_COOKIE
					$_COOKIE[$this->clean_input_keys($key)] = $this->clean_input_data($val);
				}
			}
			else
			{
				$_COOKIE = array();
			}

			// Create a singleton
			Input::$instance = $this;

			Kohana::log('debug', 'Global GET, POST and COOKIE data sanitized');
		}
	}

	/**
	 * Fetch an item from the $_GET array.
	 *
	 * @param   string   key to find
	 * @param   mixed    default value
	 * @param   boolean  XSS clean the value
	 * @return  mixed
	 */
	public function get($key = array(), $default = NULL, $xss_clean = FALSE)
	{
		return $this->search_array($_GET, $key, $default, $xss_clean);
	}

	/**
	 * Fetch an item from the $_POST array.
	 *
	 * @param   string   key to find
	 * @param   mixed    default value
	 * @param   boolean  XSS clean the value
	 * @return  mixed
	 */
	public function post($key = array(), $default = NULL, $xss_clean = FALSE)
	{
		return $this->search_array($_POST, $key, $default, $xss_clean);
	}

	/**
	 * Fetch an item from the $_COOKIE array.
	 *
	 * @param   string   key to find
	 * @param   mixed    default value
	 * @param   boolean  XSS clean the value
	 * @return  mixed
	 */
	public function cookie($key = array(), $default = NULL, $xss_clean = FALSE)
	{
		return $this->search_array($_COOKIE, $key, $default, $xss_clean);
	}

	/**
	 * Fetch an item from the $_SERVER array.
	 *
	 * @param   string   key to find
	 * @param   mixed    default value
	 * @param   boolean  XSS clean the value
	 * @return  mixed
	 */
	public function server($key = array(), $default = NULL, $xss_clean = FALSE)
	{
		return $this->search_array($_SERVER, $key, $default, $xss_clean);
	}

	/**
	 * Fetch an item from a global array.
	 *
	 * @param   array    array to search
	 * @param   string   key to find
	 * @param   mixed    default value
	 * @param   boolean  XSS clean the value
	 * @return  mixed
	 */
	protected function search_array($array, $key, $default = NULL, $xss_clean = FALSE)
	{
		if ($key === array())
			return $array;

		if ( ! isset($array[$key]))
			return $default;

		// Get the value
		$value = $array[$key];

		if ($this->use_xss_clean === FALSE AND $xss_clean === TRUE)
		{
			// XSS clean the value
			$value = $this->xss_clean($value);
		}

		return $value;
	}

	/**
	 * Fetch the IP Address.
	 *
	 * @return string
	 */
	public function ip_address()
	{
		if ($this->ip_address !== NULL)
			return $this->ip_address;

		// Server keys that could contain the client IP address
		$keys = array('HTTP_X_FORWARDED_FOR', 'HTTP_CLIENT_IP', 'REMOTE_ADDR');

		foreach ($keys as $key)
		{
			if ($ip = $this->server($key))
			{
				$this->ip_address = $ip;

				// An IP address has been found
				break;
			}
		}

		if ($comma = strrpos($this->ip_address, ',') !== FALSE)
		{
			$this->ip_address = substr($this->ip_address, $comma + 1);
		}

		if ( ! valid::ip($this->ip_address))
		{
			// Use an empty IP
			$this->ip_address = '0.0.0.0';
		}

		return $this->ip_address;
	}

	/**
	 * Clean cross site scripting exploits from string.
	 * HTMLPurifier may be used if installed, otherwise defaults to built in method.
	 * Note - This function should only be used to deal with data upon submission.
	 * It's not something that should be used for general runtime processing
	 * since it requires a fair amount of processing overhead.
	 *
	 * @param   string  data to clean
	 * @param   string  xss_clean method to use ('htmlpurifier' or defaults to built-in method)
	 * @return  string
	 */
	public function xss_clean($data, $tool = NULL)
	{
		if ($tool === NULL)
		{
			// Use the default tool
			$tool = Kohana::config('core.global_xss_filtering');
		}

		if (is_array($data))
		{
			foreach ($data as $key => $val)
			{
				$data[$key] = $this->xss_clean($val, $tool);
			}

			return $data;
		}

		// Do not clean empty strings
		if (trim($data) === '')
			return $data;

		if ($tool === TRUE)
		{
			// NOTE: This is necessary because switch is NOT type-sensative!
			$tool = 'default';
		}

		switch ($tool)
		{
			case 'htmlpurifier':
				/**
				 * @todo License should go here, http://htmlpurifier.org/
				 */
				if ( ! class_exists('HTMLPurifier_Config', FALSE))
				{
					// Load HTMLPurifier
					require Kohana::find_file('vendor', 'htmlpurifier/HTMLPurifier.auto', TRUE);
					require 'HTMLPurifier.func.php';
				}

				// Set configuration
				$config = HTMLPurifier_Config::createDefault();
				$config->set('HTML', 'TidyLevel', 'none'); // Only XSS cleaning now

				// Run HTMLPurifier
				$data = HTMLPurifier($data, $config);
			break;
			default:
				// http://svn.bitflux.ch/repos/public/popoon/trunk/classes/externalinput.php
				// +----------------------------------------------------------------------+
				// | Copyright (c) 2001-2006 Bitflux GmbH                                 |
				// +----------------------------------------------------------------------+
				// | Licensed under the Apache License, Version 2.0 (the "License");      |
				// | you may not use this file except in compliance with the License.     |
				// | You may obtain a copy of the License at                              |
				// | http://www.apache.org/licenses/LICENSE-2.0                           |
				// | Unless required by applicable law or agreed to in writing, software  |
				// | distributed under the License is distributed on an "AS IS" BASIS,    |
				// | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or      |
				// | implied. See the License for the specific language governing         |
				// | permissions and limitations under the License.                       |
				// +----------------------------------------------------------------------+
				// | Author: Christian Stocker <chregu@bitflux.ch>                        |
				// +----------------------------------------------------------------------+
				//
				// Kohana Modifications:
				// * Changed double quotes to single quotes, changed indenting and spacing
				// * Removed magic_quotes stuff
				// * Increased regex readability:
				//   * Used delimeters that aren't found in the pattern
				//   * Removed all unneeded escapes
				//   * Deleted U modifiers and swapped greediness where needed
				// * Increased regex speed:
				//   * Made capturing parentheses non-capturing where possible
				//   * Removed parentheses where possible
				//   * Split up alternation alternatives
				//   * Made some quantifiers possessive

				// Fix &entity\n;
				$data = str_replace(array('&amp;','&lt;','&gt;'), array('&amp;amp;','&amp;lt;','&amp;gt;'), $data);
				$data = preg_replace('/(&#*\w+)[\x00-\x20]+;/u', '$1;', $data);
				$data = preg_replace('/(&#x*[0-9A-F]+);*/iu', '$1;', $data);
				$data = html_entity_decode($data, ENT_COMPAT, 'UTF-8');

				// Remove any attribute starting with "on" or xmlns
				$data = preg_replace('#(<[^>]+?[\x00-\x20"\'])(?:on|xmlns)[^>]*+>#iu', '$1>', $data);

				// Remove javascript: and vbscript: protocols
				$data = preg_replace('#([a-z]*)[\x00-\x20]*=[\x00-\x20]*([`\'"]*)[\x00-\x20]*j[\x00-\x20]*a[\x00-\x20]*v[\x00-\x20]*a[\x00-\x20]*s[\x00-\x20]*c[\x00-\x20]*r[\x00-\x20]*i[\x00-\x20]*p[\x00-\x20]*t[\x00-\x20]*:#iu', '$1=$2nojavascript...', $data);
				$data = preg_replace('#([a-z]*)[\x00-\x20]*=([\'"]*)[\x00-\x20]*v[\x00-\x20]*b[\x00-\x20]*s[\x00-\x20]*c[\x00-\x20]*r[\x00-\x20]*i[\x00-\x20]*p[\x00-\x20]*t[\x00-\x20]*:#iu', '$1=$2novbscript...', $data);
				$data = preg_replace('#([a-z]*)[\x00-\x20]*=([\'"]*)[\x00-\x20]*-moz-binding[\x00-\x20]*:#u', '$1=$2nomozbinding...', $data);

				// Only works in IE: <span style="width: expression(alert('Ping!'));"></span>
				$data = preg_replace('#(<[^>]+?)style[\x00-\x20]*=[\x00-\x20]*[`\'"]*.*?expression[\x00-\x20]*\([^>]*+>#i', '$1>', $data);
				$data = preg_replace('#(<[^>]+?)style[\x00-\x20]*=[\x00-\x20]*[`\'"]*.*?behaviour[\x00-\x20]*\([^>]*+>#i', '$1>', $data);
				$data = preg_replace('#(<[^>]+?)style[\x00-\x20]*=[\x00-\x20]*[`\'"]*.*?s[\x00-\x20]*c[\x00-\x20]*r[\x00-\x20]*i[\x00-\x20]*p[\x00-\x20]*t[\x00-\x20]*:*[^>]*+>#iu', '$1>', $data);

				// Remove namespaced elements (we do not need them)
				$data = preg_replace('#</*\w+:\w[^>]*+>#i', '', $data);

				do
				{
					// Remove really unwanted tags
					$old_data = $data;
					$data = preg_replace('#</*(?:applet|b(?:ase|gsound|link)|embed|frame(?:set)?|i(?:frame|layer)|l(?:ayer|ink)|meta|object|s(?:cript|tyle)|title|xml)[^>]*+>#i', '', $data);
				}
				while ($old_data !== $data);
			break;
		}

		return $data;
	}

	/**
	 * This is a helper method. It enforces W3C specifications for allowed
	 * key name strings, to prevent malicious exploitation.
	 *
	 * @param   string  string to clean
	 * @return  string
	 */
	public function clean_input_keys($str)
	{
		$chars = PCRE_UNICODE_PROPERTIES ? '\pL' : 'a-zA-Z';

		if ( ! preg_match('#^['.$chars.'0-9:_.-]++$#uD', $str))
		{
			exit('Disallowed key characters in global data.');
		}

		return $str;
	}

	/**
	 * This is a helper method. It escapes data and forces all newline
	 * characters to "\n".
	 *
	 * @param   unknown_type  string to clean
	 * @return  string
	 */
	public function clean_input_data($str)
	{
		if (is_array($str))
		{
			$new_array = array();
			foreach ($str as $key => $val)
			{
				// Recursion!
				$new_array[$this->clean_input_keys($key)] = $this->clean_input_data($val);
			}
			return $new_array;
		}

		if ($this->magic_quotes_gpc === TRUE)
		{
			// Remove annoying magic quotes
			$str = stripslashes($str);
		}

		if ($this->use_xss_clean === TRUE)
		{
			$str = $this->xss_clean($str);
		}

		if (strpos($str, "\r") !== FALSE)
		{
			// Standardize newlines
			$str = str_replace(array("\r\n", "\r"), "\n", $str);
		}

		return $str;
	}

} // End Input Class