*/ // must be run within Dokuwiki if(!defined('DOKU_INC')) die(); if(!defined('DOKU_PLUGIN')) define('DOKU_PLUGIN', DOKU_INC.'lib/plugins/'); require_once(DOKU_INC.'inc/blowfish.php'); class helper_plugin_captcha extends DokuWiki_Plugin { protected $field_in = 'plugin__captcha'; protected $field_sec = 'plugin__captcha_secret'; protected $field_hp = 'plugin__captcha_honeypot'; /** * Constructor. Initializes field names */ public function __construct() { $this->field_in = md5($this->_fixedIdent().$this->field_in); $this->field_sec = md5($this->_fixedIdent().$this->field_sec); $this->field_hp = md5($this->_fixedIdent().$this->field_hp); } /** * Check if the CAPTCHA should be used. Always check this before using the methods below. * * @return bool true when the CAPTCHA should be used */ public function isEnabled() { if(!$this->getConf('forusers') && $_SERVER['REMOTE_USER']) return false; return true; } /** * Returns the HTML to display the CAPTCHA with the chosen method */ public function getHTML() { global $ID; $rand = (float) (rand(0, 10000)) / 10000; if($this->getConf('mode') == 'math') { $code = $this->_generateMATH($this->_fixedIdent(), $rand); $code = $code[0]; $text = $this->getLang('fillmath'); } else { $code = $this->_generateCAPTCHA($this->_fixedIdent(), $rand); $text = $this->getLang('fillcaptcha'); } $secret = PMA_blowfish_encrypt($rand, auth_cookiesalt()); $out = ''; $out .= '
'; $out .= ''; $out .= ' '; switch($this->getConf('mode')) { case 'text': case 'math': $out .= $code; break; case 'js': $out .= ''.$code.''; break; case 'image': $out .= ' '; break; case 'audio': $out .= ' '; $out .= ''; $out .= ''.$this->getLang('soundlink').''; break; case 'figlet': require_once(dirname(__FILE__).'/figlet.php'); $figlet = new phpFiglet(); if($figlet->loadfont(dirname(__FILE__).'/figlet.flf')) { $out .= '
';
                    $out .= rtrim($figlet->fetch($code));
                    $out .= '
'; } else { msg('Failed to load figlet.flf font file. CAPTCHA broken', -1); } break; } $out .= ' '; // add honeypot field $out .= ''; $out .= '
'; return $out; } /** * Checks if the the CAPTCHA was solved correctly * * @param bool $msg when true, an error will be signalled through the msg() method * @return bool true when the answer was correct, otherwise false */ public function check($msg = true) { // compare provided string with decrypted captcha $rand = PMA_blowfish_decrypt($_REQUEST[$this->field_sec], auth_cookiesalt()); if($this->getConf('mode') == 'math') { $code = $this->_generateMATH($this->_fixedIdent(), $rand); $code = $code[1]; } else { $code = $this->_generateCAPTCHA($this->_fixedIdent(), $rand); } if(!$_REQUEST[$this->field_sec] || !$_REQUEST[$this->field_in] || strtoupper($_REQUEST[$this->field_in]) != $code || trim($_REQUEST[$this->field_hp]) !== '' ) { if($msg) msg($this->getLang('testfailed'), -1); return false; } return true; } /** * Build a semi-secret fixed string identifying the current page and user * * This string is always the same for the current user when editing the same * page revision, but only for one day. Editing a page before midnight and saving * after midnight will result in a failed CAPTCHA once, but makes sure it can * not be reused which is especially important for the registration form where the * $ID usually won't change. * * @return string */ public function _fixedIdent() { global $ID; $lm = @filemtime(wikiFN($ID)); $td = date('Y-m-d'); return auth_browseruid(). auth_cookiesalt(). $ID.$lm.$td; } /** * Generates a random 5 char string * * @param $fixed string the fixed part, any string * @param $rand float some random number between 0 and 1 * @return string */ public function _generateCAPTCHA($fixed, $rand) { $fixed = hexdec(substr(md5($fixed), 5, 5)); // use part of the md5 to generate an int $numbers = md5($rand * $fixed); // combine both values // now create the letters $code = ''; for($i = 0; $i < 10; $i += 2) { $code .= chr(floor(hexdec($numbers[$i].$numbers[$i + 1]) / 10) + 65); } return $code; } /** * Create a mathematical task and its result * * @param $fixed string the fixed part, any string * @param $rand float some random number between 0 and 1 * @return array taks, result */ protected function _generateMATH($fixed, $rand) { $fixed = hexdec(substr(md5($fixed), 5, 5)); // use part of the md5 to generate an int $numbers = md5($rand * $fixed); // combine both values // first letter is the operator (+/-) $op = (hexdec($numbers[0]) > 8) ? -1 : 1; $num = array(hexdec($numbers[1].$numbers[2]), hexdec($numbers[3])); // we only want positive results if(($op < 0) && ($num[0] < $num[1])) rsort($num); // prepare result and task text $res = $num[0] + ($num[1] * $op); $task = $num[0].(($op < 0) ? ' - ' : ' + ').$num[1].' = ?'; return array($task, $res); } /** * Create a CAPTCHA image * * @param string $text the letters to display */ public function _imageCAPTCHA($text) { $w = $this->getConf('width'); $h = $this->getConf('height'); $fonts = glob(dirname(__FILE__).'/fonts/*.ttf'); // create a white image $img = imagecreate($w, $h); imagecolorallocate($img, 255, 255, 255); // add some lines as background noise for($i = 0; $i < 30; $i++) { $color = imagecolorallocate($img, rand(100, 250), rand(100, 250), rand(100, 250)); imageline($img, rand(0, $w), rand(0, $h), rand(0, $w), rand(0, $h), $color); } // draw the letters for($i = 0; $i < strlen($text); $i++) { $font = $fonts[array_rand($fonts)]; $color = imagecolorallocate($img, rand(0, 100), rand(0, 100), rand(0, 100)); $size = rand(floor($h / 1.8), floor($h * 0.7)); $angle = rand(-35, 35); $x = ($w * 0.05) + $i * floor($w * 0.9 / 5); $cheight = $size + ($size * 0.5); $y = floor($h / 2 + $cheight / 3.8); imagettftext($img, $size, $angle, $x, $y, $color, $font, $text[$i]); } header("Content-type: image/png"); imagepng($img); imagedestroy($img); } }