Created
October 2, 2012 09:07
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ultra light captcha
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| <?php | |
| /** | |
| * ultra light captcha class | |
| * | |
| * @package Open Classifieds | |
| * @subpackage Core | |
| * @category Helper | |
| * @author Chema Garrido <chema@garridodiaz.com> | |
| * @license GPL v3 | |
| */ | |
| class captcha{ | |
| /** | |
| * generates the image for the captcha | |
| * @param string $name, used in the session | |
| * @param int $width | |
| * @param int $height | |
| * @param string $baseList | |
| */ | |
| public static function image($name='',$width=120,$height=40,$baseList = '0123456789abcdfghjkmnpqrstvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ') | |
| { | |
| session_start(); | |
| $length = mt_rand(3,5);//code length | |
| $lines = mt_rand(1,5);//to make the image dirty | |
| $image = @imagecreate($width, $height) or die('Cannot initialize GD!'); | |
| $code = ''; //code generated saved at session | |
| //base image with dirty lines | |
| for( $i=0; $i<$lines; $i++ ) { | |
| imageline($image, | |
| mt_rand(0,$width), mt_rand(0,$height), | |
| mt_rand(0,$width), mt_rand(0,$height), | |
| imagecolorallocate($image, mt_rand(150,255), mt_rand(150,255), mt_rand(150,255))); | |
| } | |
| //writting the chars | |
| for( $i=0, $x=0; $i<$length; $i++ ) { | |
| $actChar = substr($baseList, rand(0, strlen($baseList)-1), 1); | |
| $x += 10 + mt_rand(0,10); | |
| imagechar($image, mt_rand(4,5), $x, mt_rand(5,20), $actChar, | |
| imagecolorallocate($image, mt_rand(0,155), mt_rand(0,155), mt_rand(0,155))); | |
| $code .= strtolower($actChar); | |
| } | |
| // prevent client side caching | |
| header("Expires: Wed, 1 Jan 1997 00:00:00 GMT"); | |
| header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT"); | |
| header("Cache-Control: no-store, no-cache, must-revalidate"); | |
| header("Cache-Control: post-check=0, pre-check=0", FALSE); | |
| header("Pragma: no-cache"); | |
| header('Content-Type: image/jpeg'); | |
| imagejpeg($image); | |
| imagedestroy($image); | |
| $_SESSION['captcha'.$name] = $code; | |
| } | |
| /** | |
| * gets the URL where the image is created | |
| * @param string $name for the session | |
| * @return string | |
| */ | |
| public static function image_url($name='') | |
| { | |
| return 'img.php?salt='.$name; | |
| } | |
| /** | |
| * check if its valid or not | |
| * @param string $name for the session | |
| * @return boolean | |
| */ | |
| public static function check($name='') | |
| { | |
| if ($_SESSION['captcha'.$name]==strtolower($_POST['captcha'])) | |
| { | |
| $_SESSION['captcha'.$name] = ''; | |
| return TRUE; | |
| } | |
| else return FALSE; | |
| } | |
| /** | |
| * check that there's no CSRF attack | |
| * @param string $name the salt used to create the CSRF | |
| * @return boolean | |
| */ | |
| public static function check_CSRF($name='') | |
| { | |
| if ( (!empty($_SESSION['token_'.$name])) && (!empty($_POST['token_'.$name])) ) | |
| {//echo $_SESSION['token_'.$name].'---'.$_POST['token_'.$name]; | |
| if ($_SESSION['token_'.$name] == $_POST['token_'.$name]) | |
| { | |
| return TRUE; | |
| } | |
| } | |
| return FALSE; | |
| } | |
| /** | |
| * Creates CSRF token and the HTML tag | |
| * @param string $name salt allows us to have more than 1 form per page and to have more than 1 tab opened with different items | |
| * @return string | |
| */ | |
| public static function CSRF($name='') | |
| { | |
| $token = md5($name.uniqid(rand(), TRUE));//unique form token | |
| $_SESSION['token_'.$name] = $token; | |
| return'<input type="hidden" name="token_'.$name.'" value="'.$token.'">'; | |
| } | |
| } |
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| <!DOCTYPE HTML> | |
| <html> | |
| <body> | |
| <?php | |
| session_start(); | |
| require_once('captcha.php'); | |
| if ($_POST) | |
| { | |
| if ( captcha::check_CSRF('contact')) | |
| { | |
| if(captcha::check('contact')) | |
| { | |
| //correct captcha! | |
| echo 'correct captcha! <br>'; | |
| var_dump($_POST); | |
| } | |
| else echo "Wrong captcha"; | |
| } | |
| else echo "Wrong referer CSRF"; | |
| } | |
| ?> | |
| <form method="post" action="" > | |
| Name:<br /> | |
| <input id="name" name="name" type="text" value="<?php echo $_P['name'];?>" maxlength="75" /><br /> | |
| Captcha*:<br /> | |
| <img alt="captcha" src="<?php echo captcha::image_url('contact');?>"><br /> | |
| <input id="captcha" name="captcha" type="text" /> | |
| <br /> | |
| <br /> | |
| <?php echo captcha::CSRF('contact');?> | |
| <input type="submit" /> | |
| </form> | |
| </body> | |
| </html> |
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| <?php include('captcha.php'); | |
| captcha::image($_GET['salt']); |
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