diff options
Diffstat (limited to 'system/libraries/drivers/Captcha.php')
| -rw-r--r-- | system/libraries/drivers/Captcha.php | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/system/libraries/drivers/Captcha.php b/system/libraries/drivers/Captcha.php new file mode 100644 index 00000000..a4343e19 --- /dev/null +++ b/system/libraries/drivers/Captcha.php @@ -0,0 +1,227 @@ +<?php defined('SYSPATH') OR die('No direct access allowed.'); +/** + * Captcha driver class. + * + * $Id: Captcha.php 3769 2008-12-15 00:48:56Z zombor $ + * + * @package Captcha + * @author Kohana Team + * @copyright (c) 2007-2008 Kohana Team + * @license http://kohanaphp.com/license.html + */ +abstract class Captcha_Driver { + + // The correct Captcha challenge answer + protected $response; + + // Image resource identifier and type ("png", "gif" or "jpeg") + protected $image; + protected $image_type = 'png'; + + /** + * Constructs a new challenge. + * + * @return void + */ + public function __construct() + { + // Generate a new challenge + $this->response = $this->generate_challenge(); + + // Store the correct Captcha response in a session + Event::add('system.post_controller', array($this, 'update_response_session')); + } + + /** + * Generate a new Captcha challenge. + * + * @return string the challenge answer + */ + abstract public function generate_challenge(); + + /** + * Output the Captcha challenge. + * + * @param boolean html output + * @return mixed the rendered Captcha (e.g. an image, riddle, etc.) + */ + abstract public function render($html); + + /** + * Stores the response for the current Captcha challenge in a session so it is available + * on the next page load for Captcha::valid(). This method is called after controller + * execution (in the system.post_controller event) in order not to overwrite itself too soon. + * + * @return void + */ + public function update_response_session() + { + Session::instance()->set('captcha_response', sha1(strtoupper($this->response))); + } + + /** + * Validates a Captcha response from a user. + * + * @param string captcha response + * @return boolean + */ + public function valid($response) + { + return (sha1(strtoupper($response)) === Session::instance()->get('captcha_response')); + } + + /** + * Returns the image type. + * + * @param string filename + * @return string|FALSE image type ("png", "gif" or "jpeg") + */ + public function image_type($filename) + { + switch (strtolower(substr(strrchr($filename, '.'), 1))) + { + case 'png': + return 'png'; + + case 'gif': + return 'gif'; + + case 'jpg': + case 'jpeg': + // Return "jpeg" and not "jpg" because of the GD2 function names + return 'jpeg'; + + default: + return FALSE; + } + } + + /** + * Creates an image resource with the dimensions specified in config. + * If a background image is supplied, the image dimensions are used. + * + * @throws Kohana_Exception if no GD2 support + * @param string path to the background image file + * @return void + */ + public function image_create($background = NULL) + { + // Check for GD2 support + if ( ! function_exists('imagegd2')) + throw new Kohana_Exception('captcha.requires_GD2'); + + // Create a new image (black) + $this->image = imagecreatetruecolor(Captcha::$config['width'], Captcha::$config['height']); + + // Use a background image + if ( ! empty($background)) + { + // Create the image using the right function for the filetype + $function = 'imagecreatefrom'.$this->image_type($background); + $this->background_image = $function($background); + + // Resize the image if needed + if (imagesx($this->background_image) !== Captcha::$config['width'] + OR imagesy($this->background_image) !== Captcha::$config['height']) + { + imagecopyresampled + ( + $this->image, $this->background_image, 0, 0, 0, 0, + Captcha::$config['width'], Captcha::$config['height'], + imagesx($this->background_image), imagesy($this->background_image) + ); + } + + // Free up resources + imagedestroy($this->background_image); + } + } + + /** + * Fills the background with a gradient. + * + * @param resource gd image color identifier for start color + * @param resource gd image color identifier for end color + * @param string direction: 'horizontal' or 'vertical', 'random' by default + * @return void + */ + public function image_gradient($color1, $color2, $direction = NULL) + { + $directions = array('horizontal', 'vertical'); + + // Pick a random direction if needed + if ( ! in_array($direction, $directions)) + { + $direction = $directions[array_rand($directions)]; + + // Switch colors + if (mt_rand(0, 1) === 1) + { + $temp = $color1; + $color1 = $color2; + $color2 = $temp; + } + } + + // Extract RGB values + $color1 = imagecolorsforindex($this->image, $color1); + $color2 = imagecolorsforindex($this->image, $color2); + + // Preparations for the gradient loop + $steps = ($direction === 'horizontal') ? Captcha::$config['width'] : Captcha::$config['height']; + + $r1 = ($color1['red'] - $color2['red']) / $steps; + $g1 = ($color1['green'] - $color2['green']) / $steps; + $b1 = ($color1['blue'] - $color2['blue']) / $steps; + + if ($direction === 'horizontal') + { + $x1 =& $i; + $y1 = 0; + $x2 =& $i; + $y2 = Captcha::$config['height']; + } + else + { + $x1 = 0; + $y1 =& $i; + $x2 = Captcha::$config['width']; + $y2 =& $i; + } + + // Execute the gradient loop + for ($i = 0; $i <= $steps; $i++) + { + $r2 = $color1['red'] - floor($i * $r1); + $g2 = $color1['green'] - floor($i * $g1); + $b2 = $color1['blue'] - floor($i * $b1); + $color = imagecolorallocate($this->image, $r2, $g2, $b2); + + imageline($this->image, $x1, $y1, $x2, $y2, $color); + } + } + + /** + * Returns the img html element or outputs the image to the browser. + * + * @param boolean html output + * @return mixed html string or void + */ + public function image_render($html) + { + // Output html element + if ($html) + return '<img alt="Captcha" src="'.url::site('captcha/'.Captcha::$config['group']).'" width="'.Captcha::$config['width'].'" height="'.Captcha::$config['height'].'" />'; + + // Send the correct HTTP header + header('Content-Type: image/'.$this->image_type); + + // Pick the correct output function + $function = 'image'.$this->image_type; + $function($this->image); + + // Free up resources + imagedestroy($this->image); + } + +} // End Captcha Driver
\ No newline at end of file |