Subversion-Projekte lars-tiefland.prado

<?php

/**

 * TCaptcha class file

 *

 * @author Qiang Xue <qiang.xue@gmail.com>

 * @link http://www.pradosoft.com/

 * @copyright Copyright © 2005-2008 PradoSoft

 * @license http://www.pradosoft.com/license/

 * @version $Id: TCaptcha.php 2541 2008-10-21 15:05:13Z qiang.xue $

 * @package System.Web.UI.WebControls

 */

Prado::using('System.Web.UI.WebControls.TImage');

/**

 * TCaptcha class.

 *

 * TCaptcha displays a CAPTCHA (a token displayed as an image) that can be used

 * to determine if the input is entered by a real user instead of some program.

 *

 * Unlike other CAPTCHA scripts, TCaptcha does not need session or cookie.

 *

 * The token (a string consisting of alphanumeric characters) displayed is automatically

 * generated and can be configured in several ways. To specify the length of characters

 * in the token, set {@link setMinTokenLength MinTokenLength} and {@link setMaxTokenLength MaxTokenLength}.

 * To use case-insensitive comparison and generate upper-case-only token, set {@link setCaseSensitive CaseSensitive}

 * to false. Advanced users can try to set {@link setTokenAlphabet TokenAlphabet}, which

 * specifies what characters can appear in tokens.

 *

 * The validation of the token is related with two properties: {@link setTestLimit TestLimit}

 * and {@link setTokenExpiry TokenExpiry}. The former specifies how many times a token can

 * be tested with on the server side, and the latter says when a generated token will expire.

 *

 * To specify the appearance of the generated token image, set {@link setTokenImageTheme TokenImageTheme}

 * to be an integer between 0 and 63. And to adjust the generated image size, set {@link setTokenFontSize TokenFontSize}

 * (you may also set {@link TWebControl::setWidth Width}, but the scaled image may not look good.)

 * By setting {@link setChangingTokenBackground ChangingTokenBackground} to true, the image background

 * of the token will be variating even though the token is the same during postbacks.

 *

 * Upon postback, user input can be validated by calling {@link validate()}.

 * The {@link TCaptchaValidator} control can also be used to do validation, which provides

 * client-side validation besides the server-side validation.  By default, the token will

 * remain the same during multiple postbacks. A new one can be generated by calling

 * {@link regenerateToken()} manually.

 *

 * The following template shows a typical use of TCaptcha control:

 * <code>

 * <com:TCaptcha ID="Captcha" />

 * <com:TTextBox ID="Input" />

 * <com:TCaptchaValidator CaptchaControl="Captcha"

 *                        ControlToValidate="Input"

 *                        ErrorMessage="You are challenged!" />

 * </code>

 *

 * @author Qiang Xue <qiang.xue@gmail.com>

 * @version $Id: TCaptcha.php 2541 2008-10-21 15:05:13Z qiang.xue $

 * @package System.Web.UI.WebControls

 * @since 3.1.1

 */

class TCaptcha extends TImage

{

	const MIN_TOKEN_LENGTH=2;

	const MAX_TOKEN_LENGTH=40;

	private $_privateKey;

	private $_validated=false;

	/**

	 * @return integer the theme of the token image. Defaults to 0.

	 */

	public function getTokenImageTheme()

	{

		return $this->getViewState('TokenImageTheme',0);

	}

	/**

	 * Sets the theme of the token image.

	 * You may test each theme to find out the one you like the most.

	 * Below is the explanation of the theme value:

	 * It is treated as a 5-bit integer. Each bit toggles a specific feature of the image.

	 * Bit 0 (the least significant): whether the image is opaque (1) or transparent (0).

	 * Bit 1: whether we should add white noise to the image (1) or not (0).

	 * Bit 2: whether we should add a grid to  the image (1) or not (0).

	 * Bit 3: whether we should add some scribbles to the image (1) or not (0).

	 * Bit 4: whether the image background should be morphed (1) or not (0).

	 * Bit 5: whether the token text should cast a shadow (1) or not (0).

	 * @param integer the theme of the token image. It must be an integer between 0 and 63.

	 */

	public function setTokenImageTheme($value)

	{

		$value=TPropertyValue::ensureInteger($value);

		if($value>=0 && $value<=63)

			$this->setViewState('TokenImageTheme',$value,0);

		else

			throw new TConfigurationException('captcha_tokenimagetheme_invalid',0,63);

	}

	/**

	 * @return integer the font size used for displaying the token in an image. Defaults to 30.

	 */

	public function getTokenFontSize()

	{

		return $this->getViewState('TokenFontSize',30);

	}

	/**

	 * Sets the font size used for displaying the token in an image.

	 * This property affects the generated token image size.

	 * The image width is proportional to this font size.

	 * @param integer the font size used for displaying the token in an image. It must be an integer between 20 and 100.

	 */

	public function setTokenFontSize($value)

	{

		$value=TPropertyValue::ensureInteger($value);

		if($value>=20 && $value<=100)

			$this->setViewState('TokenFontSize',$value,30);

		else

			throw new TConfigurationException('captcha_tokenfontsize_invalid',20,100);

	}

	/**

	 * @return integer the minimum length of the token. Defaults to 4.

	 */

	public function getMinTokenLength()

	{

		return $this->getViewState('MinTokenLength',4);

	}

	/**

	 * @param integer the minimum length of the token. It must be between 2 and 40.

	 */

	public function setMinTokenLength($value)

	{

		$length=TPropertyValue::ensureInteger($value);

		if($length>=self::MIN_TOKEN_LENGTH && $length<=self::MAX_TOKEN_LENGTH)

			$this->setViewState('MinTokenLength',$length,4);

		else

			throw new TConfigurationException('captcha_mintokenlength_invalid',self::MIN_TOKEN_LENGTH,self::MAX_TOKEN_LENGTH);

	}

	/**

	 * @return integer the maximum length of the token. Defaults to 6.

	 */

	public function getMaxTokenLength()

	{

		return $this->getViewState('MaxTokenLength',6);

	}

	/**

	 * @param integer the maximum length of the token. It must be between 2 and 40.

	 */

	public function setMaxTokenLength($value)

	{

		$length=TPropertyValue::ensureInteger($value);

		if($length>=self::MIN_TOKEN_LENGTH && $length<=self::MAX_TOKEN_LENGTH)

			$this->setViewState('MaxTokenLength',$length,6);

		else

			throw new TConfigurationException('captcha_maxtokenlength_invalid',self::MIN_TOKEN_LENGTH,self::MAX_TOKEN_LENGTH);

	}

	/**

	 * @return boolean whether the token should be treated as case-sensitive. Defaults to true.

	 */

	public function getCaseSensitive()

	{

		return $this->getViewState('CaseSensitive',true);

	}

	/**

	 * @param boolean whether the token should be treated as case-sensitive. If false, only upper-case letters will appear in the token.

	 */

	public function setCaseSensitive($value)

	{

		$this->setViewState('CaseSensitive',TPropertyValue::ensureBoolean($value),true);

	}

	/**

	 * @return string the characters that may appear in the token. Defaults to '234578adefhijmnrtABDEFGHJLMNRT'.

	 */

	public function getTokenAlphabet()

	{

		return $this->getViewState('TokenAlphabet','234578adefhijmnrtABDEFGHJLMNRT');

	}

	/**

	 * @param string the characters that may appear in the token. At least 2 characters must be specified.

	 */

	public function setTokenAlphabet($value)

	{

		if(strlen($value)<2)

			throw new TConfigurationException('captcha_tokenalphabet_invalid');

		$this->setViewState('TokenAlphabet',$value,'234578adefhijmnrtABDEFGHJLMNRT');

	}

	/**

	 * @return integer the number of seconds that a generated token will remain valid. Defaults to 600 seconds (10 minutes).

	 */

	public function getTokenExpiry()

	{

		return $this->getViewState('TokenExpiry',600);

	}

	/**

	 * @param integer the number of seconds that a generated token will remain valid. A value smaller than 1 means the token will not expire.

	 */

	public function setTokenExpiry($value)

	{

		$this->setViewState('TokenExpiry',TPropertyValue::ensureInteger($value),600);

	}

	/**

	 * @return boolean whether the background of the token image should be variated during postbacks. Defaults to false.

	 */

	public function getChangingTokenBackground()

	{

		return $this->getViewState('ChangingTokenBackground',false);

	}

	/**

	 * @param boolean whether the background of the token image should be variated during postbacks.

	 */

	public function setChangingTokenBackground($value)

	{

		$this->setViewState('ChangingTokenBackground',TPropertyValue::ensureBoolean($value),false);

	}

	/**

	 * @return integer how many times a generated token can be tested. Defaults to 5.

	 */

	public function getTestLimit()

	{

		return $this->getViewState('TestLimit',5);

	}

	/**

	 * @param integer how many times a generated token can be tested. For unlimited tests, set it to 0.

	 */

	public function setTestLimit($value)

	{

		$this->setViewState('TestLimit',TPropertyValue::ensureInteger($value),5);

	}

	/**

	 * @return boolean whether the currently generated token has expired.

	 */

	public function getIsTokenExpired()

	{

		if(($expiry=$this->getTokenExpiry())>0 && ($start=$this->getViewState('TokenGenerated',0))>0)

			return $expiry+$start<time();

		else

			return false;

	}

	/**

	 * @return string the public key used for generating the token. A random one will be generated and returned if this is not set.

	 */

	public function getPublicKey()

	{

		if(($publicKey=$this->getViewState('PublicKey',''))==='')

		{

			$publicKey=$this->generateRandomKey();

			$this->setPublicKey($publicKey);

		}

		return $publicKey;

	}

	/**

	 * @param string the public key used for generating the token. A random one will be generated if this is not set.

	 */

	public function setPublicKey($value)

	{

		$this->setViewState('PublicKey',$value,'');

	}

	/**

	 * @return string the token that will be displayed

	 */

	public function getToken()

	{

		return $this->generateToken($this->getPublicKey(),$this->getPrivateKey(),$this->getTokenAlphabet(),$this->getTokenLength(),$this->getCaseSensitive());

	}

	/**

	 * @return integer the length of the token to be generated.

	 */

	protected function getTokenLength()

	{

		if(($tokenLength=$this->getViewState('TokenLength'))===null)

		{

			$minLength=$this->getMinTokenLength();

			$maxLength=$this->getMaxTokenLength();

			if($minLength>$maxLength)

				$tokenLength=rand($maxLength,$minLength);

			else if($minLength<$maxLength)

				$tokenLength=rand($minLength,$maxLength);

			else

				$tokenLength=$minLength;

			$this->setViewState('TokenLength',$tokenLength);

		}

		return $tokenLength;

	}

	/**

	 * @return string the private key used for generating the token. This is randomly generated and kept in a file for persistency.

	 */

	public function getPrivateKey()

	{

		if($this->_privateKey===null)

		{

			$fileName=$this->generatePrivateKeyFile();

			$content=file_get_contents($fileName);

			$matches=array();

			if(preg_match("/privateKey='(.*?)'/ms",$content,$matches)>0)

				$this->_privateKey=$matches[1];

			else

				throw new TConfigurationException('captcha_privatekey_unknown');

		}

		return $this->_privateKey;

	}

	/**

	 * Validates a user input with the token.

	 * @param string user input

	 * @return boolean if the user input is not the same as the token.

	 */

	public function validate($input)

	{

		$number=$this->getViewState('TestNumber',0);

		if(!$this->_validated)

		{

			$this->setViewState('TestNumber',++$number);

			$this->_validated=true;

		}

		if($this->getIsTokenExpired() || (($limit=$this->getTestLimit())>0 && $number>$limit))

		{

			$this->regenerateToken();

			return false;

		}

		return ($this->getToken()===($this->getCaseSensitive()?$input:strtoupper($input)));

	}

	/**

	 * Regenerates the token to be displayed.

	 * By default, a token, once generated, will remain the same during the following page postbacks.

	 * Calling this method will generate a new token.

	 */

	public function regenerateToken()

	{

		$this->clearViewState('TokenLength');

		$this->setPublicKey('');

		$this->clearViewState('TokenGenerated');

		$this->clearViewState('RandomSeed');

		$this->clearViewState('TestNumber',0);

	}

	/**

	 * Configures the image URL that shows the token.

	 * @param mixed event parameter

	 */

	public function onPreRender($param)

	{

		parent::onPreRender($param);

		if(!self::checkRequirements())

			throw new TConfigurationException('captcha_imagettftext_required');

		if(!$this->getViewState('TokenGenerated',0))

		{

			$manager=$this->getApplication()->getAssetManager();

			$manager->publishFilePath($this->getFontFile());

			$url=$manager->publishFilePath($this->getCaptchaScriptFile());

			$url.='?options='.urlencode($this->getTokenImageOptions());

			$this->setImageUrl($url);

			$this->setViewState('TokenGenerated',time());

		}

	}

	/**

	 * @return string the options to be passed to the token image generator

	 */

	protected function getTokenImageOptions()

	{

		$privateKey=$this->getPrivateKey();  // call this method to ensure private key is generated

		$token=$this->getToken();

		$options=array();

		$options['publicKey']=$this->getPublicKey();

		$options['tokenLength']=strlen($token);

		$options['caseSensitive']=$this->getCaseSensitive();

		$options['alphabet']=$this->getTokenAlphabet();

		$options['fontSize']=$this->getTokenFontSize();

		$options['theme']=$this->getTokenImageTheme();

		if(($randomSeed=$this->getViewState('RandomSeed',0))===0)

		{

			$randomSeed=(int)(microtime()*1000000);

			$this->setViewState('RandomSeed',$randomSeed);

		}

		$options['randomSeed']=$this->getChangingTokenBackground()?0:$randomSeed;

		$str=serialize($options);

		return base64_encode(md5($privateKey.$str).$str);

	}

	/**

	 * @return string the file path of the PHP script generating the token image

	 */

	protected function getCaptchaScriptFile()

	{

		return dirname(__FILE__).DIRECTORY_SEPARATOR.'assets'.DIRECTORY_SEPARATOR.'captcha.php';

	}

	protected function getFontFile()

	{

		return dirname(__FILE__).DIRECTORY_SEPARATOR.'assets'.DIRECTORY_SEPARATOR.'verase.ttf';

	}

	/**

	 * Generates a file with a randomly generated private key.

	 * @return string the path of the file keeping the private key

	 */

	protected function generatePrivateKeyFile()

	{

		$captchaScript=$this->getCaptchaScriptFile();

		$path=dirname($this->getApplication()->getAssetManager()->getPublishedPath($captchaScript));

		$fileName=$path.DIRECTORY_SEPARATOR.'captcha_key.php';

		if(!is_file($fileName))

		{

			@mkdir($path);

			$key=$this->generateRandomKey();

			$content="<?php

\$privateKey='$key';

?>";

			file_put_contents($fileName,$content);

		}

		return $fileName;

	}

	/**

	 * @return string a randomly generated key

	 */

	protected function generateRandomKey()

	{

		return md5(rand().rand().rand().rand());

	}

	/**

	 * Generates the token.

	 * @param string public key

	 * @param string private key

	 * @param integer the length of the token

	 * @param boolean whether the token is case sensitive

	 * @return string the token generated.

	 */

	protected function generateToken($publicKey,$privateKey,$alphabet,$tokenLength,$caseSensitive)

	{

		$token=substr($this->hash2string(md5($publicKey.$privateKey),$alphabet).$this->hash2string(md5($privateKey.$publicKey),$alphabet),0,$tokenLength);

		return $caseSensitive?$token:strtoupper($token);

	}

	/**

	 * Converts a hash string into a string with characters consisting of alphanumeric characters.

	 * @param string the hexadecimal representation of the hash string

	 * @param string the alphabet used to represent the converted string. If empty, it means '234578adefhijmnrtwyABDEFGHIJLMNQRTWY', which excludes those confusing characters.

	 * @return string the converted string

	 */

	protected function hash2string($hex,$alphabet='')

	{

		if(strlen($alphabet)<2)

			$alphabet='234578adefhijmnrtABDEFGHJLMNQRT';

		$hexLength=strlen($hex);

		$base=strlen($alphabet);

		$result='';

		for($i=0;$i<$hexLength;$i+=6)

		{

			$number=hexdec(substr($hex,$i,6));

			while($number)

			{

				$result.=$alphabet[$number%$base];

				$number=floor($number/$base);

			}

		}

		return $result;

	}

	/**

	 * Checks the requirements needed for generating CAPTCHA images.

	 * TCaptach requires GD2 with TrueType font support and PNG image support.

	 * @return boolean whether the requirements are satisfied.

	 */

	public static function checkRequirements()

	{

		return extension_loaded('gd') && function_exists('imagettftext') && function_exists('imagepng');

	}

}