/securimage/securimage.php

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<?php

// error_reporting(E_ALL); ini_set('display_errors', 1); // uncomment this line for debugging

/**
 * Project:     Securimage: A PHP class for creating and managing form CAPTCHA images<br />
 * File:        securimage.php<br />
 *
 * Copyright (c) 2013, Drew Phillips
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 *  - Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *  - Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * Any modifications to the library should be indicated clearly in the source code
 * to inform users that the changes are not a part of the original software.<br /><br />
 *
 * If you found this script useful, please take a quick moment to rate it.<br />
 * http://www.hotscripts.com/rate/49400.html  Thanks.
 *
 * @link http://www.phpcaptcha.org Securimage PHP CAPTCHA
 * @link http://www.phpcaptcha.org/latest.zip Download Latest Version
 * @link http://www.phpcaptcha.org/Securimage_Docs/ Online Documentation
 * @copyright 2013 Drew Phillips
 * @author Drew Phillips <drew@drew-phillips.com>
 * @version 3.5 (April 2013)
 * @package Securimage
 *
 */

/**
 ChangeLog
 
 3.5
 - Release new version
 - MB string support for charlist
 - Modify audio file path to use language directories
 - Changed default captcha appearance
 
 3.2RC4
 - Add MySQL, PostgreSQL, and SQLite3 support for database storage 
 - Deprecate "use_sqlite_db" option and remove SQLite2/sqlite_* functions
 - Add new captcha type that displays 2 dictionary words on one image
 - Update examples

 3.2RC3
 - Fix canSendHeaders() check which was breaking if a PHP startup error was issued

 3.2RC2
 - Add error handler (https://github.com/dapphp/securimage/issues/15)
 - Fix flash examples to use the correct value name for audio parameter

 3.2RC1
 - New audio captcha code.  Faster, fully dynamic audio, full WAV support
   (Paul Voegler, Drew Phillips) <http://voegler.eu/pub/audio>
 - New Flash audio streaming button.  User defined image and size supported
 - Additional options for customizing captcha (noise_level, send_headers,
   no_exit, no_session, display_value
 - Add captcha ID support.  Uses sqlite and unique captcha IDs to track captchas,
   no session used
 - Add static methods for creating and validating captcha by ID
 - Automatic clearing of old codes from SQLite database

 3.0.3Beta
 - Add improved mixing function to WavFile class (Paul Voegler)
 - Improve performance and security of captcha audio (Paul Voegler, Drew Phillips)
 - Add option to use random file as background noise in captcha audio
 - Add new securimage options for audio files

 3.0.2Beta
 - Fix issue with session variables when upgrading from 2.0 - 3.0
 - Improve audio captcha, switch to use WavFile class, make mathematical captcha audio work

 3.0.1
 - Bugfix: removed use of deprecated variable in addSignature method that would cause errors with display_errors on

 3.0
 - Rewrite class using PHP5 OOP
 - Remove support for GD fonts, require FreeType
 - Remove support for multi-color codes
 - Add option to make codes case-sensitive
 - Add namespaces to support multiple captchas on a single page or page specific captchas
 - Add option to show simple math problems instead of codes
 - Remove support for mp3 files due to vulnerability in decoding mp3 audio files
 - Create new flash file to stream wav files instead of mp3
 - Changed to BSD license

 2.0.2
 - Fix pathing to make integration into libraries easier (Nathan Phillip Brink ohnobinki@ohnopublishing.net)

 2.0.1
 - Add support for browsers with cookies disabled (requires php5, sqlite) maps users to md5 hashed ip addresses and md5 hashed codes for security
 - Add fallback to gd fonts if ttf support is not enabled or font file not found (Mike Challis http://www.642weather.com/weather/scripts.php)
 - Check for previous definition of image type constants (Mike Challis)
 - Fix mime type settings for audio output
 - Fixed color allocation issues with multiple colors and background images, consolidate allocation to one function
 - Ability to let codes expire after a given length of time
 - Allow HTML color codes to be passed to Securimage_Color (suggested by Mike Challis)

 2.0.0
 - Add mathematical distortion to characters (using code from HKCaptcha)
 - Improved session support
 - Added Securimage_Color class for easier color definitions
 - Add distortion to audio output to prevent binary comparison attack (proposed by Sven "SavageTiger" Hagemann [insecurity.nl])
 - Flash button to stream mp3 audio (Douglas Walsh www.douglaswalsh.net)
 - Audio output is mp3 format by default
 - Change font to AlteHaasGrotesk by yann le coroller
 - Some code cleanup

 1.0.4 (unreleased)
 - Ability to output audible codes in mp3 format to stream from flash

 1.0.3.1
 - Error reading from wordlist in some cases caused words to be cut off 1 letter short

 1.0.3
 - Removed shadow_text from code which could cause an undefined property error due to removal from previous version

 1.0.2
 - Audible CAPTCHA Code wav files
 - Create codes from a word list instead of random strings

 1.0
 - Added the ability to use a selected character set, rather than a-z0-9 only.
 - Added the multi-color text option to use different colors for each letter.
 - Switched to automatic session handling instead of using files for code storage
 - Added GD Font support if ttf support is not available.  Can use internal GD fonts or load new ones.
 - Added the ability to set line thickness
 - Added option for drawing arced lines over letters
 - Added ability to choose image type for output

 */


/**
 * Securimage CAPTCHA Class.
 *
 * @version    3.5
 * @package    Securimage
 * @subpackage classes
 * @author     Drew Phillips <drew@drew-phillips.com>
 *
 */
class Securimage
{
    // All of the public variables below are securimage options
    // They can be passed as an array to the Securimage constructor, set below,
    // or set from securimage_show.php and securimage_play.php

    /**
     * Renders captcha as a JPEG image
     * @var int
     */
    const SI_IMAGE_JPEG = 1;
    /**
     * Renders captcha as a PNG image (default)
     * @var int
     */
    const SI_IMAGE_PNG  = 2;
    /**
     * Renders captcha as a GIF image
     * @var int
     */
    const SI_IMAGE_GIF  = 3;

    /**
     * Create a normal alphanumeric captcha
     * @var int
     */
    const SI_CAPTCHA_STRING     = 0;
    /**
     * Create a captcha consisting of a simple math problem
     * @var int
     */
    const SI_CAPTCHA_MATHEMATIC = 1;
    /**
     * Create a word based captcha using 2 words
     * @var int
     */
    const SI_CAPTCHA_WORDS      = 2;
    
    /**
     * MySQL option identifier for database storage option
     * 
     * @var string
     */
    const SI_DRIVER_MYSQL   = 'mysql';
    
    /**
     * PostgreSQL option identifier for database storage option
     * 
     * @var string
     */
    const SI_DRIVER_PGSQL   = 'pgsql';
    
    /**
     * SQLite option identifier for database storage option
     * 
     * @var string
     */
    const SI_DRIVER_SQLITE3 = 'sqlite';

    /*%*********************************************************************%*/
    // Properties
    
    /**
     * The width of the captcha image
     * @var int
     */
    public $image_width = 215;
    /**
     * The height of the captcha image
     * @var int
     */
    public $image_height = 80;
    /**
     * The type of the image, default = png
     * @var int
     */
    public $image_type   = self::SI_IMAGE_PNG;

    /**
     * The background color of the captcha
     * @var Securimage_Color
     */
    public $image_bg_color = '#ffffff';
    /**
     * The color of the captcha text
     * @var Securimage_Color
     */
    public $text_color     = '#707070';
    /**
     * The color of the lines over the captcha
     * @var Securimage_Color
     */
    public $line_color     = '#707070';
    /**
     * The color of the noise that is drawn
     * @var Securimage_Color
     */
    public $noise_color    = '#707070';

    /**
     * How transparent to make the text 0 = completely opaque, 100 = invisible
     * @var int
     */
    public $text_transparency_percentage = 20;
    /**
     * Whether or not to draw the text transparently, true = use transparency, false = no transparency
     * @var bool
     */
    public $use_transparent_text         = true;

    /**
     * The length of the captcha code
     * @var int
     */
    public $code_length    = 6;
    /**
     * Whether the captcha should be case sensitive (not recommended, use only for maximum protection)
     * @var bool
     */
    public $case_sensitive = false;
    /**
     * The character set to use for generating the captcha code
     * @var string
     */
    public $charset        = 'ABCDEFGHKLMNPRSTUVWYZabcdefghklmnprstuvwyz23456789';
    /**
     * How long in seconds a captcha remains valid, after this time it will not be accepted
     * @var unknown_type
     */
    public $expiry_time    = 900;

    /**
     * The session name securimage should use, only set this if your application uses a custom session name
     * It is recommended to set this value below so it is used by all securimage scripts
     * @var string
     */
    public $session_name   = null;

    /**
     * true to use the wordlist file, false to generate random captcha codes
     * @var bool
     */
    public $use_wordlist   = false;

    /**
     * The level of distortion, 0.75 = normal, 1.0 = very high distortion
     * @var double
     */
    public $perturbation = 0.85;
    /**
     * How many lines to draw over the captcha code to increase security
     * @var int
     */
    public $num_lines    = 5;
    /**
     * The level of noise (random dots) to place on the image, 0-10
     * @var int
     */
    public $noise_level  = 2;

    /**
     * The signature text to draw on the bottom corner of the image
     * @var string
     */
    public $image_signature = '';
    /**
     * The color of the signature text
     * @var Securimage_Color
     */
    public $signature_color = '#707070';
    /**
     * The path to the ttf font file to use for the signature text, defaults to $ttf_file (AHGBold.ttf)
     * @var string
     */
    public $signature_font;

    /**
     * DO NOT USE!!!
     * Use an SQLite database to store data (for users that do not support cookies)
     * @var bool
     * @see Securimage::$use_sqlite_db
     * @deprecated 3.2RC4
     */
    public $use_sqlite_db = false;
    
    /**
     * Use a database backend for code storage.
     * Provides a fallback to users with cookies disabled.
     * Required when using captcha IDs.
     * 
     * @see Securimage::$database_driver
     * @var bool
     */
    public $use_database = false;
    
    /**
     * Database driver to use for database support.
     * Allowable values: 'mysql', 'pgsql', 'sqlite'.
     * Default: sqlite
     * 
     * @var string
     */
    public $database_driver = self::SI_DRIVER_SQLITE3;
    
    /**
     * Database host to connect to when using mysql or postgres
     * On Linux use "localhost" for Unix domain socket, otherwise uses TCP/IP
     * Does not apply to SQLite
     * 
     * @var string
     */
    public $database_host   = 'localhost';
    
    /**
     * Database username for connection (mysql, postgres only)
     * Default is an empty string
     * 
     * @var string 
     */
    public $database_user   = '';
    
    /**
     * Database password for connection (mysql, postgres only)
     * Default is empty string
     * 
     * @var string
     */
    public $database_pass   = '';
    
    /**
     * Name of the database to select (mysql, postgres only)
     * 
     * @see Securimage::$database_file for SQLite
     * @var string
     */
    public $database_name   = '';
    
    /**
     * Database table where captcha codes are stored
     * Note: Securimage will attempt to create this table for you if it does
     * not exist.  If the table cannot be created, an E_USER_WARNING is emitted.
     * 
     * @var string
     */
    public $database_table  = 'captcha_codes';
    
    /**
     * Fully qualified path to the database file when using SQLite3.
     * This value is only used when $database_driver == sqlite3 and does
     * not apply when no database is used, or when using MySQL or PostgreSQL.
     * 
     * @var string
     */
    public $database_file;

    /**
     * The type of captcha to create, either alphanumeric, or a math problem<br />
     * Securimage::SI_CAPTCHA_STRING or Securimage::SI_CAPTCHA_MATHEMATIC
     * @var int
     */
    public $captcha_type  = self::SI_CAPTCHA_STRING; // or self::SI_CAPTCHA_MATHEMATIC;

    /**
     * The captcha namespace, use this if you have multiple forms on a single page, blank if you do not use multiple forms on one page
     * @var string
     * <code>
     * <?php
     * // in securimage_show.php (create one show script for each form)
     * $img->namespace = 'contact_form';
     *
     * // in form validator
     * $img->namespace = 'contact_form';
     * if ($img->check($code) == true) {
     *     echo "Valid!";
     *  }
     * </code>
     */
    public $namespace;

    /**
     * The font file to use to draw the captcha code, leave blank for default font AHGBold.ttf
     * @var string
     */
    public $ttf_file;
    /**
     * The path to the wordlist file to use, leave blank for default words/words.txt
     * @var string
     */
    public $wordlist_file;
    /**
     * The directory to scan for background images, if set a random background will be chosen from this folder
     * @var string
     */
    public $background_directory;
    /**
     * The path to the SQLite database file to use, if $use_sqlite_database = true, should be chmod 666
     * @deprecated 3.2RC4
     * @var string
     */
    public $sqlite_database;
    /**
     * The path to the securimage audio directory, can be set in securimage_play.php
     * @var string
     * <code>
     * $img->audio_path = '/home/yoursite/public_html/securimage/audio/en/';
     * </code>
     */
    public $audio_path;
    /**
     * The path to the directory containing audio files that will be selected
     * randomly and mixed with the captcha audio.
     *
     * @var string
     */
    public $audio_noise_path;
    /**
     * Whether or not to mix background noise files into captcha audio (true = mix, false = no)
     * Mixing random background audio with noise can help improve security of audio captcha.
     * Default: securimage/audio/noise
     *
     * @since 3.0.3
     * @see Securimage::$audio_noise_path
     * @var bool
     */
    public $audio_use_noise;
    /**
     * The method and threshold (or gain factor) used to normalize the mixing with background noise.
     * See http://www.voegler.eu/pub/audio/ for more information.
     *
     * Valid: <ul>
     *     <li> >= 1 - Normalize by multiplying by the threshold (boost - positive gain). <br />
     *            A value of 1 in effect means no normalization (and results in clipping). </li>
     *     <li> <= -1 - Normalize by dividing by the the absolute value of threshold (attenuate - negative gain). <br />
     *            A factor of 2 (-2) is about 6dB reduction in volume.</li>
     *     <li> [0, 1) - (open inverval - not including 1) - The threshold
     *            above which amplitudes are comressed logarithmically. <br />
     *            e.g. 0.6 to leave amplitudes up to 60% "as is" and compress above. </li>
     *     <li> (-1, 0) - (open inverval - not including -1 and 0) - The threshold
     *            above which amplitudes are comressed linearly. <br />
     *            e.g. -0.6 to leave amplitudes up to 60% "as is" and compress above. </li></ul>
     *
     * Default: 0.6
     *
     * @since 3.0.4
     * @var float
     */
    public $audio_mix_normalization = 0.6;
    /**
     * Whether or not to degrade audio by introducing random noise (improves security of audio captcha)
     * Default: true
     *
     * @since 3.0.3
     * @var bool
     */
    public $degrade_audio;
    /**
     * Minimum delay to insert between captcha audio letters in milliseconds
     *
     * @since 3.0.3
     * @var float
     */
    public $audio_gap_min = 0;
    /**
     * Maximum delay to insert between captcha audio letters in milliseconds
     *
     * @since 3.0.3
     * @var float
     */
    public $audio_gap_max = 600;

    /**
     * Captcha ID if using static captcha
     * @var string Unique captcha id
     */
    protected static $_captchaId = null;

    protected $im;
    protected $tmpimg;
    protected $bgimg;
    protected $iscale = 5;

    public $securimage_path = null;

    /**
     * The captcha challenge value (either the case-sensitive/insensitive word captcha, or the solution to the math captcha)
     *
     * @var string Captcha challenge value
     */
    protected $code;

    /**
     * The display value of the captcha to draw on the image (the word captcha, or the math equation to present to the user)
     *
     * @var string Captcha display value to draw on the image
     */
    protected $code_display;

    /**
     * A value that can be passed to the constructor that can be used to generate a captcha image with a given value
     * This value does not get stored in the session or database and is only used when calling Securimage::show().
     * If a display_value was passed to the constructor and the captcha image is generated, the display_value will be used
     * as the string to draw on the captcha image.  Used only if captcha codes are generated and managed by a 3rd party app/library
     *
     * @var string Captcha code value to display on the image
     */
    public $display_value;

    /**
     * Captcha code supplied by user [set from Securimage::check()]
     *
     * @var string
     */
    protected $captcha_code;

    /**
     * Flag that can be specified telling securimage not to call exit after generating a captcha image or audio file
     *
     * @var bool If true, script will not terminate; if false script will terminate (default)
     */
    protected $no_exit;

    /**
     * Flag indicating whether or not a PHP session should be started and used
     *
     * @var bool If true, no session will be started; if false, session will be started and used to store data (default)
     */
    protected $no_session;

    /**
     * Flag indicating whether or not HTTP headers will be sent when outputting captcha image/audio
     *
     * @var bool If true (default) headers will be sent, if false, no headers are sent
     */
    protected $send_headers;

    /**
     * PDO connection when a database is used
     * 
     * @var resource
     */
    protected $pdo_conn;

    // gd color resources that are allocated for drawing the image
    protected $gdbgcolor;
    protected $gdtextcolor;
    protected $gdlinecolor;
    protected $gdsignaturecolor;

    /**
     * Create a new securimage object, pass options to set in the constructor.<br />
     * This can be used to display a captcha, play an audible captcha, or validate an entry
     * @param array $options
     * <code>
     * $options = array(
     *     'text_color' => new Securimage_Color('#013020'),
     *     'code_length' => 5,
     *     'num_lines' => 5,
     *     'noise_level' => 3,
     *     'font_file' => Securimage::getPath() . '/custom.ttf'
     * );
     *
     * $img = new Securimage($options);
     * </code>
     */
    public function __construct($options = array())
    {
        $this->securimage_path = dirname(__FILE__);

        if (is_array($options) && sizeof($options) > 0) {
            foreach($options as $prop => $val) {
                if ($prop == 'captchaId') {
                    Securimage::$_captchaId = $val;
                    $this->use_database     = true;
                } else if ($prop == 'use_sqlite_db') {
                    trigger_error("The use_sqlite_db option is deprecated, use 'use_database' instead", E_USER_NOTICE);
                } else {
                    $this->$prop = $val;
                }
            }
        }

        $this->image_bg_color  = $this->initColor($this->image_bg_color,  '#ffffff');
        $this->text_color      = $this->initColor($this->text_color,      '#616161');
        $this->line_color      = $this->initColor($this->line_color,      '#616161');
        $this->noise_color     = $this->initColor($this->noise_color,     '#616161');
        $this->signature_color = $this->initColor($this->signature_color, '#616161');

        if (is_null($this->ttf_file)) {
            $this->ttf_file = $this->securimage_path . '/AHGBold.ttf';
        }

        $this->signature_font = $this->ttf_file;

        if (is_null($this->wordlist_file)) {
            $this->wordlist_file = $this->securimage_path . '/words/words.txt';
        }

        if (is_null($this->database_file)) {
            $this->database_file = $this->securimage_path . '/database/securimage.sq3';
        }

        if (is_null($this->audio_path)) {
            $this->audio_path = $this->securimage_path . '/audio/en/';
        }

        if (is_null($this->audio_noise_path)) {
            $this->audio_noise_path = $this->securimage_path . '/audio/noise/';
        }

        if (is_null($this->audio_use_noise)) {
            $this->audio_use_noise = true;
        }

        if (is_null($this->degrade_audio)) {
            $this->degrade_audio = true;
        }

        if (is_null($this->code_length) || (int)$this->code_length < 1) {
            $this->code_length = 6;
        }

        if (is_null($this->perturbation) || !is_numeric($this->perturbation)) {
            $this->perturbation = 0.75;
        }

        if (is_null($this->namespace) || !is_string($this->namespace)) {
            $this->namespace = 'default';
        }

        if (is_null($this->no_exit)) {
            $this->no_exit = false;
        }

        if (is_null($this->no_session)) {
            $this->no_session = false;
        }

        if (is_null($this->send_headers)) {
            $this->send_headers = true;
        }

        if ($this->no_session != true) {
            // Initialize session or attach to existing
            if ( session_id() == '' ) { // no session has been started yet, which is needed for validation
                if (!is_null($this->session_name) && trim($this->session_name) != '') {
                    session_name(trim($this->session_name)); // set session name if provided
                }
                session_start();
            }
        }
    }

    /**
     * Return the absolute path to the Securimage directory
     * @return string The path to the securimage base directory
     */
    public static function getPath()
    {
        return dirname(__FILE__);
    }

    /**
     * Generate a new captcha ID or retrieve the current ID
     *
     * @param $new bool If true, generates a new challenge and returns and ID
     * @param $options array Additional options to be passed to Securimage.
     * Must include database options if not set directly in securimage.php
     *
     * @return null|string Returns null if no captcha id set and new was false, or string captcha ID
     */
    public static function getCaptchaId($new = true, array $options = array())
    {
        if (is_null($new) || (bool)$new == true) {
            $id = sha1(uniqid($_SERVER['REMOTE_ADDR'], true));
            $opts = array('no_session'    => true,
                          'use_database'  => true);
            if (sizeof($options) > 0) $opts = array_merge($options, $opts);
            $si = new self($opts);
            Securimage::$_captchaId = $id;
            $si->createCode();

            return $id;
        } else {
            return Securimage::$_captchaId;
        }
    }

    /**
     * Validate a captcha code input against a captcha ID
     * 
     * @param string $id       The captcha ID to check
     * @param string $value    The captcha value supplied by the user
     * @param array  $options  Array of options to construct Securimage with.
     * Options must include database options if they are not set in securimage.php
     *
     * @see Securimage::$database_driver
     * @return bool true if the code was valid for the given captcha ID, false if not or if database failed to open
     */
    public static function checkByCaptchaId($id, $value, array $options = array())
    {
        $opts = array('captchaId'    => $id,
                      'no_session'   => true,
                      'use_database' => true);
        
        if (sizeof($options) > 0) $opts = array_merge($options, $opts);
        
        $si = new self($opts);

        if ($si->openDatabase()) {
            $code = $si->getCodeFromDatabase();

            if (is_array($code)) {
                $si->code         = $code['code'];
                $si->code_display = $code['code_disp'];
            }

            if ($si->check($value)) {
                $si->clearCodeFromDatabase();
                
                return true;
            } else {
                return false;
            }
        } else {
            return false;
        }
    }


    /**
     * Used to serve a captcha image to the browser
     * @param string $background_image The path to the background image to use
     * <code>
     * $img = new Securimage();
     * $img->code_length = 6;
     * $img->num_lines   = 5;
     * $img->noise_level = 5;
     *
     * $img->show(); // sends the image to browser
     * exit;
     * </code>
     */
    public function show($background_image = '')
    {
        set_error_handler(array(&$this, 'errorHandler'));

        if($background_image != '' && is_readable($background_image)) {
            $this->bgimg = $background_image;
        }

        $this->doImage();
    }

    /**
     * Check a submitted code against the stored value
     * @param string $code  The captcha code to check
     * <code>
     * $code = $_POST['code'];
     * $img  = new Securimage();
     * if ($img->check($code) == true) {
     *     $captcha_valid = true;
     * } else {
     *     $captcha_valid = false;
     * }
     * </code>
     */
    public function check($code)
    {
        $this->code_entered = $code;
        $this->validate();
        return $this->correct_code;
    }

    /**
     * Output a wav file of the captcha code to the browser
     *
     * <code>
     * $img = new Securimage();
     * $img->outputAudioFile(); // outputs a wav file to the browser
     * exit;
     * </code>
     */
    public function outputAudioFile()
    {
        set_error_handler(array(&$this, 'errorHandler'));

        require_once dirname(__FILE__) . '/WavFile.php';

        try {
            $audio = $this->getAudibleCode();
        } catch (Exception $ex) {
            if (($fp = @fopen(dirname(__FILE__) . '/si.error_log', 'a+')) !== false) {
                fwrite($fp, date('Y-m-d H:i:s') . ': Securimage audio error "' . $ex->getMessage() . '"' . "\n");
                fclose($fp);
            }

            $audio = $this->audioError();
        }

        if ($this->canSendHeaders() || $this->send_headers == false) {
            if ($this->send_headers) {
                $uniq = md5(uniqid(microtime()));
                header("Content-Disposition: attachment; filename=\"securimage_audio-{$uniq}.wav\"");
                header('Cache-Control: no-store, no-cache, must-revalidate');
                header('Expires: Sun, 1 Jan 2000 12:00:00 GMT');
                header('Last-Modified: ' . gmdate('D, d M Y H:i:s') . 'GMT');
                header('Content-type: audio/x-wav');

                if (extension_loaded('zlib')) {
                    ini_set('zlib.output_compression', true);  // compress output if supported by browser
                } else {
                    header('Content-Length: ' . strlen($audio));
                }
            }

            echo $audio;
        } else {
            echo '<hr /><strong>'
                .'Failed to generate audio file, content has already been '
                .'output.<br />This is most likely due to misconfiguration or '
                .'a PHP error was sent to the browser.</strong>';
        }

        restore_error_handler();

        if (!$this->no_exit) exit;
    }

    /**
     * Return the code from the session or sqlite database if used.  If none exists yet, an empty string is returned
     *
     * @param $array bool   True to receive an array containing the code and properties
     * @return array|string Array if $array = true, otherwise a string containing the code
     */
    public function getCode($array = false, $returnExisting = false)
    {
        $code = '';
        $time = 0;
        $disp = 'error';
        
        if ($returnExisting && strlen($this->code) > 0) {
            if ($array) {
                return array('code' => $this->code,
                             'display' => $this->code_display,
                             'code_display' => $this->code_display,
                             'time' => 0);
            } else {
                return $this->code;
            }
        }

        if ($this->no_session != true) {
            if (isset($_SESSION['securimage_code_value'][$this->namespace]) &&
                    trim($_SESSION['securimage_code_value'][$this->namespace]) != '') {
                if ($this->isCodeExpired(
                        $_SESSION['securimage_code_ctime'][$this->namespace]) == false) {
                    $code = $_SESSION['securimage_code_value'][$this->namespace];
                    $time = $_SESSION['securimage_code_ctime'][$this->namespace];
                    $disp = $_SESSION['securimage_code_disp'] [$this->namespace];
                }
            }
        }

        if (empty($code) && $this->use_database) {
            // no code in session - may mean user has cookies turned off
            $this->openDatabase();
            $code = $this->getCodeFromDatabase();
        } else { /* no code stored in session or sqlite database, validation will fail */ }

        if ($array == true) {
            return array('code' => $code, 'ctime' => $time, 'display' => $disp);
        } else {
            return $code;
        }
    }

    /**
     * The main image drawing routing, responsible for constructing the entire image and serving it
     */
    protected function doImage()
    {
        if( ($this->use_transparent_text == true || $this->bgimg != '') && function_exists('imagecreatetruecolor')) {
            $imagecreate = 'imagecreatetruecolor';
        } else {
            $imagecreate = 'imagecreate';
        }

        $this->im     = $imagecreate($this->image_width, $this->image_height);
        $this->tmpimg = $imagecreate($this->image_width * $this->iscale, $this->image_height * $this->iscale);

        $this->allocateColors();
        imagepalettecopy($this->tmpimg, $this->im);

        $this->setBackground();

        $code = '';

        if ($this->getCaptchaId(false) !== null) {
            // a captcha Id was supplied

            // check to see if a display_value for the captcha image was set
            if (is_string($this->display_value) && strlen($this->display_value) > 0) {
                $this->code_display = $this->display_value;
                $this->code         = ($this->case_sensitive) ?
                                       $this->display_value   :
                                       strtolower($this->display_value);
                $code = $this->code;
            } else if ($this->openDatabase()) {
                // no display_value, check the database for existing captchaId
                $code = $this->getCodeFromDatabase();

                // got back a result from the database with a valid code for captchaId
                if (is_array($code)) {
                    $this->code         = $code['code'];
                    $this->code_display = $code['code_disp'];
                    $code = $code['code'];
                }
            }
        }

        if ($code == '') {
            // if the code was not set using display_value or was not found in
            // the database, create a new code
            $this->createCode();
        }

        if ($this->noise_level > 0) {
            $this->drawNoise();
        }

        $this->drawWord();

        if ($this->perturbation > 0 && is_readable($this->ttf_file)) {
            $this->distortedCopy();
        }

        if ($this->num_lines > 0) {
            $this->drawLines();
        }

        if (trim($this->image_signature) != '') {
            $this->addSignature();
        }

        $this->output();
    }

    /**
     * Allocate the colors to be used for the image
     */
    protected function allocateColors()
    {
        // allocate bg color first for imagecreate
        $this->gdbgcolor = imagecolorallocate($this->im,
                                              $this->image_bg_color->r,
                                              $this->image_bg_color->g,
                                              $this->image_bg_color->b);

        $alpha = intval($this->text_transparency_percentage / 100 * 127);

        if ($this->use_transparent_text == true) {
            $this->gdtextcolor = imagecolorallocatealpha($this->im,
                                                         $this->text_color->r,
                                                         $this->text_color->g,
                                                         $this->text_color->b,
                                                         $alpha);
            $this->gdlinecolor = imagecolorallocatealpha($this->im,
                                                         $this->line_color->r,
                                                         $this->line_color->g,
                                                         $this->line_color->b,
                                                         $alpha);
            $this->gdnoisecolor = imagecolorallocatealpha($this->im,
                                                          $this->noise_color->r,
                                                          $this->noise_color->g,
                                                          $this->noise_color->b,
                                                          $alpha);
        } else {
            $this->gdtextcolor = imagecolorallocate($this->im,
                                                    $this->text_color->r,
                                                    $this->text_color->g,
                                                    $this->text_color->b);
            $this->gdlinecolor = imagecolorallocate($this->im,
                                                    $this->line_color->r,
                                                    $this->line_color->g,
                                                    $this->line_color->b);
            $this->gdnoisecolor = imagecolorallocate($this->im,
                                                          $this->noise_color->r,
                                                          $this->noise_color->g,
                                                          $this->noise_color->b);
        }

        $this->gdsignaturecolor = imagecolorallocate($this->im,
                                                     $this->signature_color->r,
                                                     $this->signature_color->g,
                                                     $this->signature_color->b);

    }

    /**
     * The the background color, or background image to be used
     */
    protected function setBackground()
    {
        // set background color of image by drawing a rectangle since imagecreatetruecolor doesn't set a bg color
        imagefilledrectangle($this->im, 0, 0,
                             $this->image_width, $this->image_height,
                             $this->gdbgcolor);
        imagefilledrectangle($this->tmpimg, 0, 0,
                             $this->image_width * $this->iscale, $this->image_height * $this->iscale,
                             $this->gdbgcolor);

        if ($this->bgimg == '') {
            if ($this->background_directory != null &&
                is_dir($this->background_directory) &&
                is_readable($this->background_directory))
            {
                $img = $this->getBackgroundFromDirectory();
                if ($img != false) {
                    $this->bgimg = $img;
                }
            }
        }

        if ($this->bgimg == '') {
            return;
        }

        $dat = @getimagesize($this->bgimg);
        if($dat == false) {
            return;
        }

        switch($dat[2]) {
            case 1:  $newim = @imagecreatefromgif($this->bgimg); break;
            case 2:  $newim = @imagecreatefromjpeg($this->bgimg); break;
            case 3:  $newim = @imagecreatefrompng($this->bgimg); break;
            default: return;
        }

        if(!$newim) return;

        imagecopyresized($this->im, $newim, 0, 0, 0, 0,
                         $this->image_width, $this->image_height,
                         imagesx($newim), imagesy($newim));
    }

    /**
     * Scan the directory for a background image to use
     */
    protected function getBackgroundFromDirectory()
    {
        $images = array();

        if ( ($dh = opendir($this->background_directory)) !== false) {
            while (($file = readdir($dh)) !== false) {
                if (preg_match('/(jpg|gif|png)$/i', $file)) $images[] = $file;
            }

            closedir($dh);

            if (sizeof($images) > 0) {
                return rtrim($this->background_directory, '/') . '/' . $images[mt_rand(0, sizeof($images)-1)];
            }
        }

        return false;
    }

    /**
     * Generates the code or math problem and saves the value to the session
     */
    public function createCode()
    {
        $this->code = false;

        switch($this->captcha_type) {
            case self::SI_CAPTCHA_MATHEMATIC:
            {
                do {
                    $signs = array('+', '-', 'x');
                    $left  = mt_rand(1, 10);
                    $right = mt_rand(1, 5);
                    $sign  = $signs[mt_rand(0, 2)];

                    switch($sign) {
                        case 'x': $c = $left * $right; break;
                        case '-': $c = $left - $right; break;
                        default:  $c = $left + $right; break;
                    }
                } while ($c <= 0); // no negative #'s or 0

                $this->code         = $c;
                $this->code_display = "$left $sign $right";
                break;
            }
            
            case self::SI_CAPTCHA_WORDS:
                $words = $this->readCodeFromFile(2);
                $this->code = implode(' ', $words);
                $this->code_display = $this->code;
                break;

            default:
            {
                if ($this->use_wordlist && is_readable($this->wordlist_file)) {
                    $this->code = $this->readCodeFromFile();
                }

                if ($this->code == false) {
                    $this->code = $this->generateCode($this->code_length);
                }

                $this->code_display = $this->code;
                $this->code         = ($this->case_sensitive) ? $this->code : strtolower($this->code);
            } // default
        }

        $this->saveData();
    }

    /**
     * Draws the captcha code on the image
     */
    protected function drawWord()
    {
        $width2  = $this->image_width * $this->iscale;
        $height2 = $this->image_height * $this->iscale;

        if (!is_readable($this->ttf_file)) {
            imagestring($this->im, 4, 10, ($this->image_height / 2) - 5, 'Failed to load TTF font file!', $this->gdtextcolor);
        } else {
            if ($this->perturbation > 0) {
                $font_size = $height2 * .4;
                $bb = imageftbbox($font_size, 0, $this->ttf_file, $this->code_display);
                $tx = $bb[4] - $bb[0];
                $ty = $bb[5] - $bb[1];
                $x  = floor($width2 / 2 - $tx / 2 - $bb[0]);
                $y  = round($height2 / 2 - $ty / 2 - $bb[1]);

                imagettftext($this->tmpimg, $font_size, 0, $x, $y, $this->gdtextcolor, $this->ttf_file, $this->code_display);
            } else {
                $font_size = $this->image_height * .4;
                $bb = imageftbbox($font_size, 0, $this->ttf_file, $this->code_display);
                $tx = $bb[4] - $bb[0];
                $ty = $bb[5] - $bb[1];
                $x  = floor($this->image_width / 2 - $tx / 2 - $bb[0]);
                $y  = round($this->image_height / 2 - $ty / 2 - $bb[1]);

                imagettftext($this->im, $font_size, 0, $x, $y, $this->gdtextcolor, $this->ttf_file, $this->code_display);
            }
        }

        // DEBUG
        //$this->im = $this->tmpimg;
        //$this->output();

    }

    /**
     * Copies the captcha image to the final image with distortion applied
     */
    protected function distortedCopy()
    {
        $numpoles = 3; // distortion factor
        // make array of poles AKA attractor points
        for ($i = 0; $i < $numpoles; ++ $i) {
            $px[$i]  = mt_rand($this->image_width  * 0.2, $this->image_width  * 0.8);
            $py[$i]  = mt_rand($this->image_height * 0.2, $this->image_height * 0.8);
            $rad[$i] = mt_rand($this->image_height * 0.2, $this->image_height * 0.8);
            $tmp     = ((- $this->frand()) * 0.15) - .15;
            $amp[$i] = $this->perturbation * $tmp;
        }

        $bgCol = imagecolorat($this->tmpimg, 0, 0);
        $width2 = $this->iscale * $this->image_width;
        $height2 = $this->iscale * $this->image_height;
        imagepalettecopy($this->im, $this->tmpimg); // copy palette to final image so text colors come across
        // loop over $img pixels, take pixels from $tmpimg with distortion field
        for ($ix = 0; $ix < $this->image_width; ++ $ix) {
            for ($iy = 0; $iy < $this->image_height; ++ $iy) {
                $x = $ix;
                $y = $iy;
                for ($i = 0; $i < $numpoles; ++ $i) {
                    $dx = $ix - $px[$i];
                    $dy = $iy - $py[$i];
                    if ($dx == 0 && $dy == 0) {
                        continue;
                    }
                    $r = sqrt($dx * $dx + $dy * $dy);
                    if ($r > $rad[$i]) {
                        continue;
                    }
                    $rscale = $amp[$i] * sin(3.14 * $r / $rad[$i]);
                    $x += $dx * $rscale;
                    $y += $dy * $rscale;
                }
                $c = $bgCol;
                $x *= $this->iscale;
                $y *= $this->iscale;
                if ($x >= 0 && $x < $width2 && $y >= 0 && $y < $height2) {
                    $c = imagecolorat($this->tmpimg, $x, $y);
                }
                if ($c != $bgCol) { // only copy pixels of letters to preserve any background image
                    imagesetpixel($this->im, $ix, $iy, $c);
                }
            }
        }
    }

    /**
     * Draws distorted lines on the image
     */
    protected function drawLines()
    {
        for ($line = 0; $line < $this->num_lines; ++ $line) {
            $x = $this->image_width * (1 + $line) / ($this->num_lines + 1);
            $x += (0.5 - $this->frand()) * $this->image_width / $this->num_lines;
            $y = mt_rand($this->image_height * 0.1, $this->image_height * 0.9);

            $theta = ($this->frand() - 0.5) * M_PI * 0.7;
            $w = $this->image_width;
            $len = mt_rand($w * 0.4, $w * 0.7);
            $lwid = mt_rand(0, 2);

            $k = $this->frand() * 0.6 + 0.2;
            $k = $k * $k * 0.5;
            $phi = $this->frand() * 6.28;
            $step = 0.5;
            $dx = $step * cos($theta);
            $dy = $step * sin($theta);
            $n = $len / $step;
            $amp = 1.5 * $this->frand() / ($k + 5.0 / $len);
            $x0 = $x - 0.5 * $len * cos($theta);
            $y0 = $y - 0.5 * $len * sin($theta);

            $ldx = round(- $dy * $lwid);
            $ldy = round($dx * $lwid);

            for ($i = 0; $i < $n; ++ $i) {
                $x = $x0 + $i * $dx + $amp * $dy * sin($k * $i * $step + $phi);
                $y = $y0 + $i * $dy - $amp * $dx * sin($k * $i * $step + $phi);
                imagefilledrectangle($this->im, $x, $y, $x + $lwid, $y + $lwid, $this->gdlinecolor);
            }
        }
    }

    /**
     * Draws random noise on the image
     */
    protected function drawNoise()
    {
        if ($this->noise_level > 10) {
            $noise_level = 10;
        } else {
            $noise_level = $this->noise_level;
        }

        $t0 = microtime(true);

        $noise_level *= 125; // an arbitrary number that works well on a 1-10 scale

        $points = $this->image_width * $this->image_height * $this->iscale;
        $height = $this->image_height * $this->iscale;
        $width  = $this->image_width * $this->iscale;
        for ($i = 0; $i < $noise_level; ++$i) {
            $x = mt_rand(10, $width);
            $y = mt_rand(10, $height);
            $size = mt_rand(7, 10);
            if ($x - $size <= 0 && $y - $size <= 0) continue; // dont cover 0,0 since it is used by imagedistortedcopy
            imagefilledarc($this->tmpimg, $x, $y, $size, $size, 0, 360, $this->gdnoisecolor, IMG_ARC_PIE);
        }

        $t1 = microtime(true);

        $t = $t1 - $t0;

        /*
        // DEBUG
        imagestring($this->tmpimg, 5, 25, 30, "$t", $this->gdnoisecolor);
        header('content-type: image/png');
        imagepng($this->tmpimg);
        exit;
        */
    }

    /**
    * Print signature text on image
    */
    protected function addSignature()
    {
        $bbox = imagettfbbox(10, 0, $this->signature_font, $this->image_signature);
        $textlen = $bbox[2] - $bbox[0];
        $x = $this->image_width - $textlen - 5;
        $y = $this->image_height - 3;

        imagettftext($this->im, 10, 0, $x, $y, $this->gdsignaturecolor, $this->signature_font, $this->image_signature);
    }

    /**
     * Sends the appropriate image and cache headers and outputs image to the browser
     */
    protected function output()
    {
        if ($this->canSendHeaders() || $this->send_headers == false) {
            if ($this->send_headers) {
                // only send the content-type headers if no headers have been output
                // this will ease debugging on misconfigured servers where warnings
                // may have been output which break the image and prevent easily viewing
                // source to see the error.
                header("Expires: Mon, 26 Jul 1997 05:00:00 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");
            }

            switch ($this->image_type) {
                case self::SI_IMAGE_JPEG:
                    if ($this->send_headers) header("Content-Type: image/jpeg");
                    imagejpeg($this->im, null, 90);
                    break;
                case self::SI_IMAGE_GIF:
                    if ($this->send_headers) header("Content-Type: image/gif");
                    imagegif($this->im);
                    break;
                default:
                    if ($this->send_headers) header("Content-Type: image/png");
                    imagepng($this->im);
                    break;
            }
        } else {
            echo '<hr /><strong>'
                .'Failed to generate captcha image, content has already been '
                .'output.<br />This is most likely due to misconfiguration or '
                .'a PHP error was sent to the browser.</strong>';
        }

        imagedestroy($this->im);
        restore_error_handler();

        if (!$this->no_exit) exit;
    }

    /**
     * Gets the code and returns the binary audio file for the stored captcha code
     *
     * @return The audio representation of the captcha in Wav format
     */
    protected function getAudibleCode()
    {
        $letters = array();
        $code    = $this->getCode(true, true);

        if ($code['code'] == '') {
            if (strlen($this->display_value) > 0) {
                $code = array('code' => $this->display_value, 'display' => $this->display_value);
            } else {
                $this->createCode()…

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