/library/Zend/Captcha/Word.php

<?php
/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Captcha
 * @subpackage Adapter
 * @copyright  Copyright (c) 2005-2008 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */

/** Zend_Captcha_Base */
require_once 'Zend/Captcha/Base.php';

/**
 * Word-based captcha adapter
 * 
 * Generates random word which user should recognise
 *
 * @category   Zend
 * @package    Zend_Captcha
 * @subpackage Adapter
 * @copyright  Copyright (c) 2005-2008 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 * @version    $Id: $
 */
abstract class Zend_Captcha_Word extends Zend_Captcha_Base
{
    /**#@+
     * @var array Character sets
     */
    static $V  = array("a", "e", "i", "o", "u", "y");
    static $VN = array("a", "e", "i", "o", "u", "y","2","3","4","5","6","7","8","9");
    static $C  = array("b","c","d","f","g","h","j","k","m","n","p","q","r","s","t","u","v","w","x","z");
    static $CN = array("b","c","d","f","g","h","j","k","m","n","p","q","r","s","t","u","v","w","x","z","2","3","4","5","6","7","8","9");
    /**#@-*/
    
    /**
     * Random session ID
     *
     * @var string
     */
    protected $_id;

    /**
     * Generated word
     *
     * @var string
     */
    protected $_word;

    /**
     * Session
     *
     * @var Zend_Session_Namespace
     */
    protected $_session;
    
    /**
     * Class name for sessions
     *
     * @var string
     */
    protected $_sessionClass = 'Zend_Session_Namespace';

    /**
     * Should the numbers be used or only letters 
     *
     * @var boolean
     */
    protected $_useNumbers = true;

    /**
     * Should both cases be used or only lowercase
     *
     * @var boolean
     */
    // protected $_useCase = false;
    
    /**
     * Session lifetime for the captcha data
     *
     * @var integer
     */
    protected $_timeout = 300;
    
    /**#@+
     * Error codes
     * @const string
     */
    const MISSING_VALUE = 'missingValue';
    const MISSING_ID    = 'missingID';
    const BAD_CAPTCHA   = 'badCaptcha';
    /**#@-*/

    /**
     * Error messages
     * @var array
     */
    protected $_messageTemplates = array(
        self::MISSING_VALUE => 'Empty captcha value',
        self::MISSING_ID    => 'Captcha ID field is missing',
        self::BAD_CAPTCHA   => 'Captcha value is wrong',
    );
    
    /**
     * Length of the word to generate
     *
     * @var integer
     */
    protected $_wordlen = 8;
	
	/**
     * Retrieve session class to utilize
     *
	 * @return string
	 */
    public function getSessionClass() 
    {
		return $this->_sessionClass;
	}
	
	/**
     * Set session class for persistence
     *
	 * @param  string $_sessionClass
     * @return Zend_Captcha_Word
	 */
    public function setSessionClass($_sessionClass) 
    {
		$this->_sessionClass = $_sessionClass;
		return $this;
	}

	/**
     * Retrieve word length to use when genrating captcha
     *
	 * @return integer
	 */
    public function getWordlen() 
    {
		return $this->_wordlen;
	}
	
	/**
     * Set word length of captcha
     *
	 * @param integer $wordlen
     * @return Zend_Captcha_Word
	 */
    public function setWordlen($wordlen) 
    {
		$this->_wordlen = $wordlen;
		return $this;
	}

	/**
     * Retrieve captcha ID
     *
     * @return string
     */
    public function getId ()
    {
        if (null === $this->_id) {
            $this->_setId($this->_generateRandomId());
        }
        return $this->_id;
    }

    /**
     * Set captcha identifier
     *
     * @param string $id
     * return Zend_Captcha_Word
     */
    protected function _setId ($id)
    {
        $this->_id = $id;
        return $this;
    }

    /**
     * Set timeout for session token
     * 
     * @param  int $ttl 
     * @return Zend_Captcha_Word
     */
    public function setTimeout($ttl)
    {
        $this->_timeout = (int) $ttl;
        return $this;
    }

    /**
     * Get session token timeout
     * 
     * @return int
     */
    public function getTimeout()
    {
        return $this->_timeout;
    }
    
    /**
     * Get session object
     *
     * @return Zend_Session_Namespace
     */
    public function getSession()
    {
        if (!isset($this->_session) || (null === $this->_session)) {
            $id = $this->getId();
            $this->_session = new $this->_sessionClass('Zend_Form_Captcha_' . $id);
            $this->_session->setExpirationHops(1, null, true);
            $this->_session->setExpirationSeconds($this->getTimeout());
        }
        return $this->_session;
    }

	/**
     * Set session namespace object
     *
	 * @param  Zend_Session_Namespace $session
     * @return Zend_Captcha_Word
	 */
    public function setSession(Zend_Session_Namespace $session) 
    {
		$this->_session = $session;
		return $this;
	}

    /**
     * Get captcha word
     *
     * @return string
     */
    public function getWord()
    {
        if (empty($this->_word)) {
            $session     = $this->getSession();
            $this->_word = $session->word;
        }
        return $this->_word;
    }

    /**
     * Set captcha word
     *
     * @param  string $word
     * @return Zend_Captcha_Word
     */
    protected function _setWord($word)
    {
        $session       = $this->getSession();
        $session->word = $word;
        $this->_word   = $word;
        return $this;
    }
    
    /**
     * Generate new random word
     *
     * @return string
     */
    protected function _generateWord()
    {
        $word       = '';
        $wordLen    = $this->getWordLen();
        $vowels     = $this->_useNumbers ? self::$VN : self::$V;
        $consonants = $this->_useNumbers ? self::$CN : self::$C;

        for ($i=0; $i < $wordLen; $i = $i + 2) {
            // generate word with mix of vowels and consonants
            $consonant = $consonants[array_rand($consonants)];
            $vowel     = $vowels[array_rand($vowels)];
            $word     .= $consonant . $vowel;
        }

        if (strlen($word) > $wordLen) {
            $word = substr($word, 0, $wordLen);
        }

        return $word;
    }
    
    /**
     * Generate new session ID and new word
     *
     * @return string session ID
     */
    public function generate()
    {
	    $this->_session = null;
        $id             = $this->_generateRandomId();
        $this->_setId($id);
        $word           = $this->_generateWord();
        $this->_setWord($word);
	    return $id;
    }

    protected function _generateRandomId()
    {
        return md5(mt_rand(0, 1000) . microtime(true));
    }

    /**
     * Validate the word
     * 
     * @see    Zend_Validate_Interface::isValid()
     * @param  mixed $value
     * @return boolean
     */
    public function isValid($value, $context = null)
    {
        $name = $this->getName();
    	if (!isset($context[$name]['input'])) {
    		$this->_error(self::MISSING_VALUE);
    		return false;
    	}
    	$value = strtolower($context[$name]['input']);
        $this->_setValue($value);

    	if (!isset($context[$name]['id'])) {
    		$this->_error(self::MISSING_ID);
    		return false;
    	}
        
    	$this->_id = $context[$name]['id'];
    	if ($value != $this->getWord()) {
            $this->_error(self::BAD_CAPTCHA);
            return false;
        }
        
        return true;
    }

    /**
     * Get captcha decorator
     * 
     * @return string
     */
    public function getDecorator() 
    {
        return "Captcha_Word";
    }
}