<?php

/**

 * Smarty plugin

 *

 * @package Smarty

 * @subpackage Security

 * @author Uwe Tews

 */

/*

 * FIXME: Smarty_Security API

 *      - getter and setter instead of public properties would allow cultivating an internal cache properly

 *      - current implementation of isTrustedResourceDir() assumes that Smarty::$template_dir and Smarty::$config_dir are immutable

 *        the cache is killed every time either of the variables change. That means that two distinct Smarty objects with differing

 *        $template_dir or $config_dir should NOT share the same Smarty_Security instance, 

 *        as this would lead to (severe) performance penalty! how should this be handled? 

 */

/**

 * This class does contain the security settings

 */

class Smarty_Security {

    /**

     * This determines how Smarty handles "<?php ... ?>" tags in templates.

     * possible values:

     * <ul>

     *   <li>Smarty::PHP_PASSTHRU -> echo PHP tags as they are</li>

     *   <li>Smarty::PHP_QUOTE    -> escape tags as entities</li>

     *   <li>Smarty::PHP_REMOVE   -> remove php tags</li>

     *   <li>Smarty::PHP_ALLOW    -> execute php tags</li>

     * </ul>

     *

     * @var integer

     */

    public $php_handling = Smarty::PHP_PASSTHRU;

    /**

     * This is the list of template directories that are considered secure.

     * $template_dir is in this list implicitly.

     *

     * @var array

     */

    public $secure_dir = array();

    /**

     * This is an array of directories where trusted php scripts reside.

     * {@link $security} is disabled during their inclusion/execution.

     *

     * @var array

     */

    public $trusted_dir = array();

    /**

     * List of regular expressions (PCRE) that include trusted URIs

     *

     * @var array

     */

    public $trusted_uri = array();

    /**

     * This is an array of trusted static classes.

     *

     * If empty access to all static classes is allowed.

     * If set to 'none' none is allowed.

     * @var array

     */

    public $static_classes = array();

    /**

     * This is an array of trusted PHP functions.

     *

     * If empty all functions are allowed.

     * To disable all PHP functions set $php_functions = null.

     * @var array

     */

    public $php_functions = array(

        'isset', 'empty',

        'count', 'sizeof',

        'in_array', 'is_array',

        'time',

        'nl2br',

    );

    /**

     * This is an array of trusted PHP modifers.

     *

     * If empty all modifiers are allowed.

     * To disable all modifier set $modifiers = null.

     * @var array

     */

    public $php_modifiers = array(

        'escape',

        'count'

    );

    /**

     * This is an array of allowed tags.

     *

     * If empty no restriction by allowed_tags.

     * @var array

     */

    public $allowed_tags = array();

    /**

     * This is an array of disabled tags.

     *

     * If empty no restriction by disabled_tags.

     * @var array

     */

    public $disabled_tags = array();

    /**

     * This is an array of allowed modifier plugins.

     *

     * If empty no restriction by allowed_modifiers.

     * @var array

     */

    public $allowed_modifiers = array();

    /**

     * This is an array of disabled modifier plugins.

     *

     * If empty no restriction by disabled_modifiers.

     * @var array

     */

    public $disabled_modifiers = array();

    /**

     * This is an array of trusted streams.

     *

     * If empty all streams are allowed.

     * To disable all streams set $streams = null.

     * @var array

     */

    public $streams = array('file');

    /**

     * + flag if constants can be accessed from template

     * @var boolean

     */

    public $allow_constants = true;

    /**

     * + flag if super globals can be accessed from template

     * @var boolean

     */

    public $allow_super_globals = true;

    /**

     * Cache for $resource_dir lookups

     * @var array

     */

    protected $_resource_dir = null;

    /**

     * Cache for $template_dir lookups

     * @var array

     */

    protected $_template_dir = null;

    /**

     * Cache for $config_dir lookups

     * @var array

     */

    protected $_config_dir = null;

    /**

     * Cache for $secure_dir lookups

     * @var array

     */

    protected $_secure_dir = null;

    /**

     * Cache for $php_resource_dir lookups

     * @var array

     */

    protected $_php_resource_dir = null;

    /**

     * Cache for $trusted_dir lookups

     * @var array

     */

    protected $_trusted_dir = null;

    /**

     * @param Smarty $smarty

     */

    public function __construct($smarty)

    {

        $this->smarty = $smarty;

    }

    /**

     * Check if PHP function is trusted.

     *

     * @param string $function_name

     * @param object $compiler compiler object

     * @return boolean true if function is trusted

     * @throws SmartyCompilerException if php function is not trusted

     */

    public function isTrustedPhpFunction($function_name, $compiler)

    {

        if (isset($this->php_functions) && (empty($this->php_functions) || in_array($function_name, $this->php_functions))) {

            return true;

        }

        $compiler->trigger_template_error("PHP function '{$function_name}' not allowed by security setting");

        return false; // should not, but who knows what happens to the compiler in the future?

    }

    /**

     * Check if static class is trusted.

     *

     * @param string $class_name

     * @param object $compiler compiler object

     * @return boolean true if class is trusted

     * @throws SmartyCompilerException if static class is not trusted

     */

    public function isTrustedStaticClass($class_name, $compiler)

    {

        if (isset($this->static_classes) && (empty($this->static_classes) || in_array($class_name, $this->static_classes))) {

            return true;

        }

        $compiler->trigger_template_error("access to static class '{$class_name}' not allowed by security setting");

        return false; // should not, but who knows what happens to the compiler in the future?

    }

    /**

     * Check if PHP modifier is trusted.

     *

     * @param string $modifier_name

     * @param object $compiler compiler object

     * @return boolean true if modifier is trusted

     * @throws SmartyCompilerException if modifier is not trusted

     */

    public function isTrustedPhpModifier($modifier_name, $compiler)

    {

        if (isset($this->php_modifiers) && (empty($this->php_modifiers) || in_array($modifier_name, $this->php_modifiers))) {

            return true;

        }

        $compiler->trigger_template_error("modifier '{$modifier_name}' not allowed by security setting");

        return false; // should not, but who knows what happens to the compiler in the future?

    }

    /**

     * Check if tag is trusted.

     *

     * @param string $tag_name

     * @param object $compiler compiler object

     * @return boolean true if tag is trusted

     * @throws SmartyCompilerException if modifier is not trusted

     */

    public function isTrustedTag($tag_name, $compiler)

    {

        // check for internal always required tags

        if (in_array($tag_name, array('assign', 'call', 'private_filter', 'private_block_plugin', 'private_function_plugin', 'private_object_block_function',

                    'private_object_function', 'private_registered_function', 'private_registered_block', 'private_special_variable', 'private_print_expression', 'private_modifier'))) {

            return true;

        }

        // check security settings

        if (empty($this->allowed_tags)) {

            if (empty($this->disabled_tags) || !in_array($tag_name, $this->disabled_tags)) {

                return true;

            } else {

                $compiler->trigger_template_error("tag '{$tag_name}' disabled by security setting", $compiler->lex->taglineno);

            }

        } else if (in_array($tag_name, $this->allowed_tags) && !in_array($tag_name, $this->disabled_tags)) {

            return true;

        } else {

            $compiler->trigger_template_error("tag '{$tag_name}' not allowed by security setting", $compiler->lex->taglineno);

        }

        return false; // should not, but who knows what happens to the compiler in the future?

    }

    /**

     * Check if modifier plugin is trusted.

     *

     * @param string $modifier_name

     * @param object $compiler compiler object

     * @return boolean true if tag is trusted

     * @throws SmartyCompilerException if modifier is not trusted

     */

    public function isTrustedModifier($modifier_name, $compiler)

    {

        // check for internal always allowed modifier

        if (in_array($modifier_name, array('default'))) {

            return true;

        }

        // check security settings

        if (empty($this->allowed_modifiers)) {

            if (empty($this->disabled_modifiers) || !in_array($modifier_name, $this->disabled_modifiers)) {

                return true;

            } else {

                $compiler->trigger_template_error("modifier '{$modifier_name}' disabled by security setting", $compiler->lex->taglineno);

            }

        } else if (in_array($modifier_name, $this->allowed_modifiers) && !in_array($modifier_name, $this->disabled_modifiers)) {

            return true;

        } else {

            $compiler->trigger_template_error("modifier '{$modifier_name}' not allowed by security setting", $compiler->lex->taglineno);

        }

        return false; // should not, but who knows what happens to the compiler in the future?

    }

    /**

     * Check if stream is trusted.

     *

     * @param string $stream_name

     * @return boolean true if stream is trusted

     * @throws SmartyException if stream is not trusted

     */

    public function isTrustedStream($stream_name)

    {

        if (isset($this->streams) && (empty($this->streams) || in_array($stream_name, $this->streams))) {

            return true;

        }

        throw new SmartyException("stream '{$stream_name}' not allowed by security setting");

    }

    /**

     * Check if directory of file resource is trusted.

     *

     * @param string $filepath

     * @return boolean true if directory is trusted

     * @throws SmartyException if directory is not trusted

     */

    public function isTrustedResourceDir($filepath)

    {

        $_template = false;

        $_config = false;

        $_secure = false;

        $_template_dir = $this->smarty->getTemplateDir();

        $_config_dir = $this->smarty->getConfigDir();

        // check if index is outdated

        if ((!$this->_template_dir || $this->_template_dir !== $_template_dir)

                || (!$this->_config_dir || $this->_config_dir !== $_config_dir)

                || (!empty($this->secure_dir) && (!$this->_secure_dir || $this->_secure_dir !== $this->secure_dir))

        ) {

            $this->_resource_dir = array();

            $_template = true;

            $_config = true;

            $_secure = !empty($this->secure_dir);

        }

        // rebuild template dir index

        if ($_template) {

            $this->_template_dir = $_template_dir;

            foreach ($_template_dir as $directory) {

                $directory = realpath($directory);

                $this->_resource_dir[$directory] = true;

            }

        }

        // rebuild config dir index

        if ($_config) {

            $this->_config_dir = $_config_dir;

            foreach ($_config_dir as $directory) {

                $directory = realpath($directory);

                $this->_resource_dir[$directory] = true;

            }

        }

        // rebuild secure dir index

        if ($_secure) {

            $this->_secure_dir = $this->secure_dir;

            foreach ((array) $this->secure_dir as $directory) {

                $directory = realpath($directory);

                $this->_resource_dir[$directory] = true;

            }

        }

        $_filepath = realpath($filepath);

        $directory = dirname($_filepath);

        $_directory = array();

        while (true) {

            // remember the directory to add it to _resource_dir in case we're successful

            $_directory[$directory] = true;

            // test if the directory is trusted

            if (isset($this->_resource_dir[$directory])) {

                // merge sub directories of current $directory into _resource_dir to speed up subsequent lookups

                $this->_resource_dir = array_merge($this->_resource_dir, $_directory);

                return true;

            }

            // abort if we've reached root

            if (($pos = strrpos($directory, DS)) === false || !isset($directory[1])) {

                break;

            }

            // bubble up one level

            $directory = substr($directory, 0, $pos);

        }

        // give up

        throw new SmartyException("directory '{$_filepath}' not allowed by security setting");

    }

    /**

     * Check if URI (e.g. {fetch} or {html_image}) is trusted

     *

     * To simplify things, isTrustedUri() resolves all input to "{$PROTOCOL}://{$HOSTNAME}".

     * So "http://username:password@hello.world.example.org:8080/some-path?some=query-string"

     * is reduced to "http://hello.world.example.org" prior to applying the patters from {@link $trusted_uri}.

     * @param string $uri 

     * @return boolean true if URI is trusted

     * @throws SmartyException if URI is not trusted

     * @uses $trusted_uri for list of patterns to match against $uri

     */

    public function isTrustedUri($uri)

    {

        $_uri = parse_url($uri);

        if (!empty($_uri['scheme']) && !empty($_uri['host'])) {

            $_uri = $_uri['scheme'] . '://' . $_uri['host'];

            foreach ($this->trusted_uri as $pattern) {

                if (preg_match($pattern, $_uri)) {

                    return true;

                }

            }

        }

        throw new SmartyException("URI '{$uri}' not allowed by security setting");

    }

    /**

     * Check if directory of file resource is trusted.

     *

     * @param string $filepath

     * @return boolean true if directory is trusted

     * @throws SmartyException if PHP directory is not trusted

     */

    public function isTrustedPHPDir($filepath)

    {

        if (empty($this->trusted_dir)) {

            throw new SmartyException("directory '{$filepath}' not allowed by security setting (no trusted_dir specified)");

        }

        // check if index is outdated

        if (!$this->_trusted_dir || $this->_trusted_dir !== $this->trusted_dir) {

            $this->_php_resource_dir = array();

            $this->_trusted_dir = $this->trusted_dir;

            foreach ((array) $this->trusted_dir as $directory) {

                $directory = realpath($directory);

                $this->_php_resource_dir[$directory] = true;

            }

        }

        $_filepath = realpath($filepath);

        $directory = dirname($_filepath);

        $_directory = array();

        while (true) {

            // remember the directory to add it to _resource_dir in case we're successful

            $_directory[] = $directory;

            // test if the directory is trusted

            if (isset($this->_php_resource_dir[$directory])) {

                // merge sub directories of current $directory into _resource_dir to speed up subsequent lookups

                $this->_php_resource_dir = array_merge($this->_php_resource_dir, $_directory);

                return true;

            }

            // abort if we've reached root

            if (($pos = strrpos($directory, DS)) === false || !isset($directory[2])) {

                break;

            }

            // bubble up one level

            $directory = substr($directory, 0, $pos);

        }

        throw new SmartyException("directory '{$_filepath}' not allowed by security setting");

    }

}

?>