* @link http://www.pradosoft.com/
* @copyright Copyright © 2005-2011 PradoSoft
* @license http://www.pradosoft.com/license/
* @version $Id$
* @package System.Web.UI.WebControls
*/
Prado::using('System.Web.UI.WebControls.TImage');
/**
* TCaptcha class.
*
* Notice: while this class is easy to use and implement, it does not provide full security.
* In fact, it's easy to bypass the checks reusing old, already-validated tokens (reply attack).
* A better alternative is provided by {@link TReCaptcha}.
*
* 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:
*
*
*
*
*
*
* @author Qiang Xue
* @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;
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 $expiry+$startgetViewState('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();
$content="";
file_put_contents($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');
}
}