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<?php
/**
* TCaptcha class file
*
* @author Qiang Xue <qiang.xue@gmail.com>
* @link http://www.pradosoft.com/
* @copyright Copyright © 2005-2007 PradoSoft
* @license http://www.pradosoft.com/license/
* @version $Id$
* @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.
*
* 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 setTokenLength TokenLength}. To use case-insensitive
* comparison and generate upper-case-only token, set {@link setCaseSensitive CaseSensitive}
* to false.
*
* 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.
*
* @author Qiang Xue <qiang.xue@gmail.com>
* @version $Id$
* @package System.Web.UI.WebControls
* @since 3.1.1
*/
class TCaptcha extends TImage
{
const MIN_TOKEN_LENGTH=2;
const MAX_TOKEN_LENGTH=40;
/**
* @return integer the length of the token. Defaults to 6.
*/
public function getTokenLength()
{
return $this->getViewState('TokenLength',6);
}
/**
* @param integer the length of the token. It must be between 2 and 40.
*/
public function setTokenLength($value)
{
$length=TPropertyValue::ensureInteger($value);
if($length>=self::MIN_TOKEN_LENGTH && $length<=self::MAX_TOKEN_LENGTH)
$this->setViewState('TokenLength',$length,6);
else
throw new TConfigurationException('captcha_TokenLength_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 public key used for generating the token. A random one will be generated 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->getTokenLength(),$this->getCaseSensitive()); return $this->generateToken();
}
/**
* @return string the private key used for generating the token. This is randomly generated and kept in a file for persistency.
*/
public function getPrivateKey()
{
$fileName=$this->generatePrivateKeyFile();
$content=file_get_contents($fileName);
$matches=array();
if(preg_match("/privateKey='(.*?)'/ms",$content,$matches)>0)
return $matches[1];
else
throw new TConfigurationException('captcha_private_unknown');
}
/**
* Validates a user input with the token.
* @param string user input
* @return boolean if the user input is not the same as the token.
*/
public function validate($input)
{
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('RegenerateToken');
$this->setPublicKey('');
}
/**
* Configures the image URL that shows the token.
* @param mixed event parameter
*/
public function onPreRender($param)
{
parent::onPreRender($param);
if($this->getViewState('RegenerateToken',true))
{
$this->getToken(); // call to ensure the token is regenerated
$url=$this->getApplication()->getAssetManager()->publishFilePath($this->getCaptchaScriptFile());
$url.='?pk='.urlencode($this->getPublicKey());
$url.='&length='.$this->getTokenLength();
$url.='&case='.($this->getCaseSensitive()?'1':'0');
$this->setImageUrl($url);
$this->generatePrivateKeyFile();
$this->setViewState('RegenerateToken',false);
}
}
/**
* @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';
}
/**
* 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,$privateKey,$tokenLength,$caseSensitive)
{
$token=substr($this->hash2string(md5($publicKey.$privateKey)).$this->hash2string(md5($privateKey.$publicKey)),0,$tokenLength);
return $caseSensitive?$token:strtoupper($token);
}
/**
* Converts a hash string into a string with characters consisting of alphanumeric characters.
* @param string the hexadecimal representation of the hash string
* @param string the alphabet used to represent the converted string. If empty, it means 0-9, a-z and A-Z.
* @return string the converted string
*/
protected function hash2string($hex,$alphabet='')
{
if(strlen($alphabet)<2)
$alphabet='0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
$hexLength=strlen($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;
}
}
?>
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