<?php

class Firewall{
    public function __construct(){
        if(@$_POST['firewall'] == 'cancelar'){
            //NÃO FAZ NADA
        }else{

            if ($_POST) {
                $this->post();
            } else if ($_GET){
                $this->get();
            }
        }
    }

    function post(){
        foreach ($_POST as $chave => $valor){
            if(is_array($valor)){
                foreach ($valor as $chave2 => $valor2){
                    $_POST[$chave2] = $this->antiInjection($valor2);
                }
            }else{
                $_POST[$chave] = $this->antiInjection($valor);
            }

        }return;
    }

    function get(){
        foreach ($_GET as $chave => $valor){

            if(is_array($valor)){
                foreach ($valor as $chave2 => $valor2){
                    $_POST[$chave2] = $this->antiInjection($valor2);
                }
            }
            else { $_GET[$chave] = $this->antiInjection($valor);
            }

        } return;
    }

    function antiInjection($valor) {
        $valor = preg_replace("/(from|select|insert|delete|where|drop table|show tables|show databases|describe|left join|right join|inner join|#|\*|--|\\\\)/i", "", $valor);
        $valor = trim($valor);
        $valor = strip_tags($valor);
        $valor = addslashes($valor);

        return $valor;
    }
}

$fw = new Firewall();