raspisms/controllers/internals/ExpressionProvider.php

<?php

/*
 * This file is part of RaspiSMS.
 *
 * (c) Pierre-Lin Bonnemaison <plebwebsas@gmail.com>
 *
 * This source file is subject to the GPL-3.0 license that is bundled
 * with this source code in the file LICENSE.
 */

namespace controllers\internals;

use Symfony\Component\ExpressionLanguage\ExpressionFunction;
use Symfony\Component\ExpressionLanguage\ExpressionFunctionProviderInterface;

class ExpressionProvider implements ExpressionFunctionProviderInterface
{
    public function getFunctions()
    {
        //Override default constant() function to make it return null
        //This will prevent the use of constant() func to read constants with security impact (such as session, db credentials, etc.)
        $neutralized_constant = new ExpressionFunction('constant', function ($str)
        {
            return null;
        }, function ($arguments, $str)
        {
            return null;
        });
        
        //Exists must be personnalized because it inverse is_null
        $exists = new ExpressionFunction('exists', function ($str)
        {
            return sprintf('isset(%1$s)', $str);
        }, function ($arguments, $var)
        {
            return isset($var);
        });

        return [
            $neutralized_constant,
            $exists,
            ExpressionFunction::fromPhp('mb_strtolower', 'lower'),
            ExpressionFunction::fromPhp('mb_strtoupper', 'upper'),
            ExpressionFunction::fromPhp('mb_substr', 'substr'),
            ExpressionFunction::fromPhp('mb_strlen', 'strlen'),
            ExpressionFunction::fromPhp('abs', 'abs'),
            ExpressionFunction::fromPhp('strtotime', 'date'),
        ];
    }
}