/FormProcessor.php

<?php

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

class FormStatus {
    const VALID     = 1;
    const INVALID   = 2;
    const UNSURE    = 3;
}

/**
 * The class that processes form.
 */
class FormProcessor {
    private $raw = array();
    public $processed = array();
    private $secret = null;
    private $captcha = 'CAPTCHA PRIVATE KEY HERE';
    private $valid = null;
    
    public function __construct($secret) {
        $this->secret = $secret;
    }
    
    public function pipe($raw) {
        $this->raw = array_merge($this->raw, $raw);
        return $this;
    }
    
    public function valid() {
        if (isset($this->valid)) {
            return $this->valid;
        } else {
            $this->process();
            return $this->valid();
        }
    }
    
    public function process($alloted_time = 900000, $kill = false) {
        require_once 'Encryption\TW_Encryption.php';
        
        $crypt = new TW_Encryption();
        
        if (!isset($this->raw['spinner'])) {
            $this->valid = FormStatus::INVALID;
            return false;
        }
        
        $timestamp_label = $this->_hash_name('timestamp', $this->raw['spinner']);
        if (!isset($this->raw[$timestamp_label])) {
            $this->valid = FormStatus::INVALID;
            return false;
        }
        
        if (($this->raw[$timestamp_label] + $alloted_time) < time()) {
            if ($kill) {
                $this->valid = FormStatus::INVALID;
                return false;
            }
            $this->valid = FormStatus::UNSURE;
        }
        
        $calc_spinner = $this->_calculate_spinner($this->raw[$timestamp_label]);
        if ($calc_spinner != $this->raw['spinner']) {
            $this->valid = FormStatus::INVALID;
            return false;
        }
        
        if (isset($this->raw['recaptcha_challenge_field']) && isset($this->raw['recaptcha_challenge_field'])) {
            if (!$this->_check_recaptcha($this->raw['recaptcha_challenge_field'], $this->raw['recaptcha_response_field'])) {
                $this->valid = FormStatus::INVALID;
                return false;
            }
        }
        
        
        foreach($this->raw as $key => $value) {
            if ($key == $timestamp_label || $key == 'spinner' || $key == 'recaptcha_challenge_field' || $key == 'recaptcha_response_field') {
                continue;
            }
            $pKey = $this->_unhash_name($key, $this->raw['spinner']);
            $this->processed[$pKey] = $value;
        }
        
        
        
        $this->valid = FormStatus::VALID;
        return true;
    }
    
    private function _calculate_spinner($timestamp) {
        return hash('sha256', $timestamp . $this->secret);
    }
    
    function _hash_name($name, $spinner) {
        require_once 'Encryption\TW_Encryption.php';
        $array = false;
        
        if (strstr($name, '[]')) {
            $array = true;
        }
        
        $crypt = new TW_Encryption();
        $encoded = $this->_encode_name($crypt->encrypt($spinner, $name . $this->secret));
        
        return $encoded;
    }
    
    private function _encode_name($name) {
        return strtr(base64_encode($name), array('+' => '-', '/' => '_', '=' => ''));
    }
    
    private function _unhash_name($hash, $spinner) {
        require_once 'Encryption\TW_Encryption.php';
        
        $crypt = new TW_Encryption();
        if (strstr($hash, '_x')) {
            return strtr($crypt->decrypt($spinner, substr($this->_decode_name($hash), 0, -2)), array($this->secret => '')) . '_x';
        }
        if (strstr($hash, '_y')) {
            return strtr($crypt->decrypt($spinner, substr($this->_decode_name($hash), 0, -2)), array($this->secret => '')) . '_y';
        }
        return strtr($crypt->decrypt($spinner, $this->_decode_name($hash)), array($this->secret => ''));
    }
    
    private function _decode_name($name) {
        if(strstr($name, '_x')) {
            return base64_decode(str_pad(strtr(substr($name, 0, -2), array('-' => '+', '_' => '/')), strlen($name) % 4, '=')) . '_x';
        }
        if(strstr($name, '_y')) {
            return base64_decode(str_pad(strtr(substr($name, 0, -2), array('-' => '+', '_' => '/')), strlen($name) % 4, '=')) . '_y';
        }
        return base64_decode(str_pad(strtr($name, array('-' => '+', '_' => '/')), strlen($name) % 4, '='));
    }
    
    private function _check_recaptcha($challenge, $response) {
        require_once 'ReCAPTCHA\recaptchalib.php';
        
         $resp = recaptcha_check_answer ($this->captcha, $_SERVER["REMOTE_ADDR"], $challenge, $response);

         return $resp->is_valid;
    }
}

?>