1<?php 2/** 3 * @license GPL 2 (http://www.gnu.org/licenses/gpl.html) 4 * @author Andreas Gohr <andi@splitbrain.org> 5 */ 6// must be run within Dokuwiki 7if(!defined('DOKU_INC')) die(); 8if(!defined('DOKU_PLUGIN')) define('DOKU_PLUGIN', DOKU_INC.'lib/plugins/'); 9require_once(DOKU_INC.'inc/blowfish.php'); 10 11class helper_plugin_captcha extends DokuWiki_Plugin { 12 13 protected $field_in = 'plugin__captcha'; 14 protected $field_sec = 'plugin__captcha_secret'; 15 protected $field_hp = 'plugin__captcha_honeypot'; 16 17 /** 18 * Constructor. Initializes field names 19 */ 20 public function __construct() { 21 $this->field_in = md5($this->_fixedIdent().$this->field_in); 22 $this->field_sec = md5($this->_fixedIdent().$this->field_sec); 23 $this->field_hp = md5($this->_fixedIdent().$this->field_hp); 24 } 25 26 /** 27 * Check if the CAPTCHA should be used. Always check this before using the methods below. 28 * 29 * @return bool true when the CAPTCHA should be used 30 */ 31 public function isEnabled() { 32 if(!$this->getConf('forusers') && $_SERVER['REMOTE_USER']) return false; 33 return true; 34 } 35 36 /** 37 * Returns the HTML to display the CAPTCHA with the chosen method 38 */ 39 public function getHTML() { 40 global $ID; 41 42 $rand = (float) (rand(0, 10000)) / 10000; 43 if($this->getConf('mode') == 'math') { 44 $code = $this->_generateMATH($this->_fixedIdent(), $rand); 45 $code = $code[0]; 46 $text = $this->getLang('fillmath'); 47 } else { 48 $code = $this->_generateCAPTCHA($this->_fixedIdent(), $rand); 49 $text = $this->getLang('fillcaptcha'); 50 } 51 $secret = PMA_blowfish_encrypt($rand, auth_cookiesalt()); 52 53 $txtlen = $this->getConf('lettercount'); 54 55 $out = ''; 56 $out .= '<div id="plugin__captcha_wrapper">'; 57 $out .= '<input type="hidden" name="'.$this->field_sec.'" value="'.hsc($secret).'" />'; 58 $out .= '<label for="plugin__captcha">'.$text.'</label> '; 59 60 switch($this->getConf('mode')) { 61 case 'text': 62 case 'math': 63 $out .= $code; 64 break; 65 case 'js': 66 $out .= '<span id="plugin__captcha_code">'.$code.'</span>'; 67 break; 68 case 'image': 69 $out .= '<img src="'.DOKU_BASE.'lib/plugins/captcha/img.php?secret='.rawurlencode($secret).'&id='.$ID.'" '. 70 ' width="'.$this->getConf('width').'" height="'.$this->getConf('height').'" alt="" /> '; 71 break; 72 case 'audio': 73 $out .= '<img src="'.DOKU_BASE.'lib/plugins/captcha/img.php?secret='.rawurlencode($secret).'&id='.$ID.'" '. 74 ' width="'.$this->getConf('width').'" height="'.$this->getConf('height').'" alt="" /> '; 75 $out .= '<a href="'.DOKU_BASE.'lib/plugins/captcha/wav.php?secret='.rawurlencode($secret).'&id='.$ID.'"'. 76 ' class="JSnocheck" title="'.$this->getLang('soundlink').'">'; 77 $out .= '<img src="'.DOKU_BASE.'lib/plugins/captcha/sound.png" width="16" height="16"'. 78 ' alt="'.$this->getLang('soundlink').'" /></a>'; 79 break; 80 case 'figlet': 81 require_once(dirname(__FILE__).'/figlet.php'); 82 $figlet = new phpFiglet(); 83 if($figlet->loadfont(dirname(__FILE__).'/figlet.flf')) { 84 $out .= '<pre>'; 85 $out .= rtrim($figlet->fetch($code)); 86 $out .= '</pre>'; 87 } else { 88 msg('Failed to load figlet.flf font file. CAPTCHA broken', -1); 89 } 90 break; 91 } 92 $out .= ' <input type="text" size="'.$txtlen.'" maxlength="'.$txtlen.'" name="'.$this->field_in.'" class="edit" /> '; 93 94 // add honeypot field 95 $out .= '<label class="no">Please keep this field empty: <input type="text" name="'.$this->field_hp.'" /></label>'; 96 $out .= '</div>'; 97 return $out; 98 } 99 100 /** 101 * Checks if the the CAPTCHA was solved correctly 102 * 103 * @param bool $msg when true, an error will be signalled through the msg() method 104 * @return bool true when the answer was correct, otherwise false 105 */ 106 public function check($msg = true) { 107 // compare provided string with decrypted captcha 108 $rand = PMA_blowfish_decrypt($_REQUEST[$this->field_sec], auth_cookiesalt()); 109 110 if($this->getConf('mode') == 'math') { 111 $code = $this->_generateMATH($this->_fixedIdent(), $rand); 112 $code = $code[1]; 113 } else { 114 $code = $this->_generateCAPTCHA($this->_fixedIdent(), $rand); 115 } 116 117 if(!$_REQUEST[$this->field_sec] || 118 !$_REQUEST[$this->field_in] || 119 strtoupper($_REQUEST[$this->field_in]) != $code || 120 trim($_REQUEST[$this->field_hp]) !== '' 121 ) { 122 if($msg) msg($this->getLang('testfailed'), -1); 123 return false; 124 } 125 return true; 126 } 127 128 /** 129 * Build a semi-secret fixed string identifying the current page and user 130 * 131 * This string is always the same for the current user when editing the same 132 * page revision, but only for one day. Editing a page before midnight and saving 133 * after midnight will result in a failed CAPTCHA once, but makes sure it can 134 * not be reused which is especially important for the registration form where the 135 * $ID usually won't change. 136 * 137 * @return string 138 */ 139 public function _fixedIdent() { 140 global $ID; 141 $lm = @filemtime(wikiFN($ID)); 142 $td = date('Y-m-d'); 143 return auth_browseruid(). 144 auth_cookiesalt(). 145 $ID.$lm.$td; 146 } 147 148 /** 149 * Generates a random char string 150 * 151 * @param $fixed string the fixed part, any string 152 * @param $rand float some random number between 0 and 1 153 * @return string 154 */ 155 public function _generateCAPTCHA($fixed, $rand) { 156 $fixed = hexdec(substr(md5($fixed), 5, 5)); // use part of the md5 to generate an int 157 $numbers = md5($rand * $fixed); // combine both values 158 159 // now create the letters 160 $code = ''; 161 for($i = 0; $i < ($this->getConf('lettercount') * 2); $i += 2) { 162 $code .= chr(floor(hexdec($numbers[$i].$numbers[$i + 1]) / 10) + 65); 163 } 164 165 return $code; 166 } 167 168 /** 169 * Create a mathematical task and its result 170 * 171 * @param $fixed string the fixed part, any string 172 * @param $rand float some random number between 0 and 1 173 * @return array taks, result 174 */ 175 protected function _generateMATH($fixed, $rand) { 176 $fixed = hexdec(substr(md5($fixed), 5, 5)); // use part of the md5 to generate an int 177 $numbers = md5($rand * $fixed); // combine both values 178 179 // first letter is the operator (+/-) 180 $op = (hexdec($numbers[0]) > 8) ? -1 : 1; 181 $num = array(hexdec($numbers[1].$numbers[2]), hexdec($numbers[3])); 182 183 // we only want positive results 184 if(($op < 0) && ($num[0] < $num[1])) rsort($num); 185 186 // prepare result and task text 187 $res = $num[0] + ($num[1] * $op); 188 $task = $num[0].(($op < 0) ? ' - ' : ' + ').$num[1].' = ?'; 189 190 return array($task, $res); 191 } 192 193 /** 194 * Create a CAPTCHA image 195 * 196 * @param string $text the letters to display 197 */ 198 public function _imageCAPTCHA($text) { 199 $w = $this->getConf('width'); 200 $h = $this->getConf('height'); 201 202 $fonts = glob(dirname(__FILE__).'/fonts/*.ttf'); 203 204 // create a white image 205 $img = imagecreatetruecolor($w, $h); 206 $white = imagecolorallocate($img, 255, 255, 255); 207 imagefill($img, 0, 0, $white); 208 209 // add some lines as background noise 210 for($i = 0; $i < 30; $i++) { 211 $color = imagecolorallocate($img, rand(100, 250), rand(100, 250), rand(100, 250)); 212 imageline($img, rand(0, $w), rand(0, $h), rand(0, $w), rand(0, $h), $color); 213 } 214 215 // draw the letters 216 $txtlen = strlen($text); 217 for($i = 0; $i < $txtlen; $i++) { 218 $font = $fonts[array_rand($fonts)]; 219 $color = imagecolorallocate($img, rand(0, 100), rand(0, 100), rand(0, 100)); 220 $size = rand(floor($h / 1.8), floor($h * 0.7)); 221 $angle = rand(-35, 35); 222 223 $x = ($w * 0.05) + $i * floor($w * 0.9 / $txtlen); 224 $cheight = $size + ($size * 0.5); 225 $y = floor($h / 2 + $cheight / 3.8); 226 227 imagettftext($img, $size, $angle, $x, $y, $color, $font, $text[$i]); 228 } 229 230 header("Content-type: image/png"); 231 imagepng($img); 232 imagedestroy($img); 233 } 234 235} 236
