*/ // must be run within Dokuwiki if(!defined('DOKU_INC')) die(); if(!defined('DOKU_PLUGIN')) define('DOKU_PLUGIN', DOKU_INC . 'lib/plugins/'); /** * Class helper_plugin_captcha */ 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; $this->storeCaptchaCookie($this->_fixedIdent(), $rand); if($this->getConf('mode') == 'math') { $code = $this->_generateMATH($this->_fixedIdent(), $rand); $code = $code[0]; $text = $this->getLang('fillmath'); } elseif($this->getConf('mode') == 'question') { $code = ''; // not used $text = $this->getConf('question'); } else { $code = $this->_generateCAPTCHA($this->_fixedIdent(), $rand); $text = $this->getLang('fillcaptcha'); } $secret = $this->encrypt($rand); $txtlen = $this->getConf('lettercount'); $out = ''; $out .= '

'; $out .= ''; $out .= ''.$text.' '; switch($this->getConf('mode')) { case 'math': case 'text': $out .= $this->_obfuscateText($code); break; case 'js': $out .= ''.$this->_obfuscateText($code).''; break; case 'svg': $out .= ''; $out .= $this->_svgCAPTCHA($code); $out .= ''; break; case 'svgaudio': $out .= ''; $out .= $this->_svgCAPTCHA($code); $out .= ''; $out .= ''; $out .= '

'; break; case 'image': $out .= '

'; break; case 'audio': $out .= '

'; $out .= ''; $out .= '

'; 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 $out .= ''.$this->getLang('honeypot').''; $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) { global $INPUT; $field_sec = $INPUT->str($this->field_sec); $field_in = $INPUT->str($this->field_in); $field_hp = $INPUT->str($this->field_hp); // reconstruct captcha from provided $field_sec $rand = $this->decrypt($field_sec); if($this->getConf('mode') == 'math') { $code = $this->_generateMATH($this->_fixedIdent(), $rand); $code = $code[1]; } elseif($this->getConf('mode') == 'question') { $code = $this->getConf('answer'); } else { $code = $this->_generateCAPTCHA($this->_fixedIdent(), $rand); } // compare values if(!$field_sec || !$field_in || $rand === false || utf8_strtolower($field_in) != utf8_strtolower($code) || trim($field_hp) !== '' || !$this->retrieveCaptchaCookie($this->_fixedIdent(), $rand) ) { if($msg) msg($this->getLang('testfailed'), -1); return false; } return true; } /** * Get the path where a captcha cookie would be stored * * We use a daily temp directory which is easy to clean up * * @param $fixed string the fixed part, any string * @param $rand float some random number between 0 and 1 * @return string the path to the cookie file */ protected function getCaptchaCookiePath($fixed, $rand) { global $conf; $path = $conf['tmpdir'] . '/captcha/' . date('Y-m-d') . '/' . md5($fixed . $rand) . '.cookie'; io_makeFileDir($path); return $path; } /** * remove all outdated captcha cookies */ public function _cleanCaptchaCookies() { global $conf; $path = $conf['tmpdir'] . '/captcha/'; $dirs = glob("$path/*", GLOB_ONLYDIR); $today = date('Y-m-d'); foreach($dirs as $dir) { if(basename($dir) === $today) continue; if(!preg_match('/\/captcha\//', $dir)) continue; // safety net io_rmdir($dir, true); } } /** * Creates a one time captcha cookie * * This is used to prevent replay attacks. It is generated when the captcha form * is shown and checked with the captcha check. Since we can not be sure about the * session state (might be closed or open) we're not using it. * * We're not using the stored values for displaying the captcha image (or audio) * but continue to use our encryption scheme. This way it's still possible to have * multiple captcha checks going on in parallel (eg. with multiple browser tabs) * * @param $fixed string the fixed part, any string * @param $rand float some random number between 0 and 1 */ protected function storeCaptchaCookie($fixed, $rand) { $cache = $this->getCaptchaCookiePath($fixed, $rand); touch($cache); } /** * Checks if the captcha cookie exists and deletes it * * @param $fixed string the fixed part, any string * @param $rand float some random number between 0 and 1 * @return bool true if the cookie existed */ protected function retrieveCaptchaCookie($fixed, $rand) { $cache = $this->getCaptchaCookiePath($fixed, $rand); if(file_exists($cache)) { unlink($cache); return true; } return false; } /** * 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; } /** * Adds random space characters within the given text * * Keeps subsequent numbers without spaces (for math problem) * * @param $text * @return string */ protected function _obfuscateText($text) { $new = ''; $spaces = array( "\r", "\n", "\r\n", ' ', "\xC2\xA0", // \u00A0 NO-BREAK SPACE "\xE2\x80\x80", // \u2000 EN QUAD "\xE2\x80\x81", // \u2001 EM QUAD "\xE2\x80\x82", // \u2002 EN SPACE // "\xE2\x80\x83", // \u2003 EM SPACE "\xE2\x80\x84", // \u2004 THREE-PER-EM SPACE "\xE2\x80\x85", // \u2005 FOUR-PER-EM SPACE "\xE2\x80\x86", // \u2006 SIX-PER-EM SPACE "\xE2\x80\x87", // \u2007 FIGURE SPACE "\xE2\x80\x88", // \u2008 PUNCTUATION SPACE "\xE2\x80\x89", // \u2009 THIN SPACE "\xE2\x80\x8A", // \u200A HAIR SPACE "\xE2\x80\xAF", // \u202F NARROW NO-BREAK SPACE "\xE2\x81\x9F", // \u205F MEDIUM MATHEMATICAL SPACE "\xE1\xA0\x8E\r\n", // \u180E MONGOLIAN VOWEL SEPARATOR "\xE2\x80\x8B\r\n", // \u200B ZERO WIDTH SPACE "\xEF\xBB\xBF\r\n", // \uFEFF ZERO WIDTH NO-BREAK SPACE ); $len = strlen($text); for($i = 0; $i < $len - 1; $i++) { $new .= $text[$i]; if(!is_numeric($text[$i + 1])) { $new .= $spaces[array_rand($spaces)]; } } $new .= $text[$len - 1]; return $new; } /** * Generate some numbers from a known string and random number * * @param $fixed string the fixed part, any string * @param $rand float some random number between 0 and 1 * @return string */ protected function _generateNumbers($fixed, $rand) { $fixed = hexdec(substr(md5($fixed), 5, 5)); // use part of the md5 to generate an int $rand = $rand * 0xFFFFF; // bitmask from the random number return md5($rand ^ $fixed); // combine both values } /** * Generates a random 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) { $numbers = $this->_generateNumbers($fixed, $rand); // now create the letters $code = ''; $lettercount = $this->getConf('lettercount') * 2; if($lettercount > strlen($numbers)) $lettercount = strlen($numbers); for($i = 0; $i < $lettercount; $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) { $numbers = $this->_generateNumbers($fixed, $rand); // 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 $img = imagecreatetruecolor($w, $h); $white = imagecolorallocate($img, 255, 255, 255); imagefill($img, 0, 0, $white); // add some lines as background noise for($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 $txtlen = strlen($text); for($i = 0; $i < $txtlen; $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 / $txtlen); $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); } /** * Create an SVG of the given text * * @param string $text * @return string */ public function _svgCAPTCHA($text) { require_once(__DIR__ . '/EasySVG.php'); $fonts = glob(__DIR__ . '/fonts/*.svg'); $x = 0; // where we start to draw $y = 100; // our max height $svg = new EasySVG(); // draw the letters $txtlen = strlen($text); for($i = 0; $i < $txtlen; $i++) { $char = $text[$i]; $size = rand($y / 2, $y - $y * 0.1); // 50-90% $svg->setFontSVG($fonts[array_rand($fonts)]); $svg->setFontSize($size); $svg->setLetterSpacing(round(rand(1, 4) / 10, 2)); // 0.1 - 0.4 $svg->addText($char, $x, rand(0, round($y - $size))); // random up and down list($w) = $svg->textDimensions($char); $x += $w; } $svg->addAttribute('width', $x . 'px'); $svg->addAttribute('height', $y . 'px'); $svg->addAttribute('viewbox', "0 0 $x $y"); return $svg->asXML(); } /** * Encrypt the given string with the cookie salt * * @param string $data * @return string */ public function encrypt($data) { if(function_exists('auth_encrypt')) { $data = auth_encrypt($data, auth_cookiesalt()); // since binky } else { $data = PMA_blowfish_encrypt($data, auth_cookiesalt()); // deprecated } return base64_encode($data); } /** * Decrypt the given string with the cookie salt * * @param string $data * @return string */ public function decrypt($data) { $data = base64_decode($data); if($data === false || $data === '') return false; if(function_exists('auth_decrypt')) { return auth_decrypt($data, auth_cookiesalt()); // since binky } else { return PMA_blowfish_decrypt($data, auth_cookiesalt()); // deprecated } } }