File: testThis.class.php

<?
/**
* Brett D. Estrade
* 3/29/2001
* brett@mvdev.com
* http://www.mvdev.com
* This class is designed to let you easily implement required constraints on your php applications
*
* You can use this class as long as you keep this header up here along with a summary of any modifications
* that you have made.
*
* Also, if you have any suggestions on how to improve this, please email me with a detailed suggestion.
* If there is a bug or vulnerability found, please alert me immediately
*/

class testThis {
	/**
	* Tests constraint provided by user.  Levels can be extended simply by adding to the switch statement
	*/
        
	function constraint($reqConstraint = '1 == 1',$requireLevel,$errMsg = '')
	{

        	/**
        	* Test for illegal code; Attempts to prevent insertion of other
        	* types of code for execution by searching for a "}";
        	*/

                if(ereg('}',$reqConstraint))
                {
                 Die('Illegal character "}" found.');
                }


        	/**
        	* Switch that checks for $requireLevel.  Add more for extended functionality
        	*/

		switch($requireLevel)
		{
			case 1:
				// returns error and kills script process if false
				$str = 'if ('.$reqConstraint.'){return true;}else{die(\''.$errMsg.'\');}';
				eval($str);			
			break;
			case 2:
				// just returns false and error if false
				$str = 'if ('.$reqConstraint.'){return true;}else{echo \''.$errMsg.'\'; return false;}';
				eval($str);		
			break;
			default:
				die('Level <b>'.$requireLevel.'</b> not defined.<br>Script Terminated...good bye!');
			break;
		}
	}

	/**
	* The following are methods that utilize the constraint method above.  There are many ways that this can
	* be used, and the following are just a couple of them
	*/
	
	/**
	* Requires file provided by user.  Levels can be extended simply by adding to the switch statement to this->constraint
	* First, existance of file is checked.  If that is true, the it uses the constraint method to perform the inclusion of the file
	* If file does not exist, the constraint function is called, this time with a predermined 'false' inserted, and it handles the rest
	*/
	function includeFile($file = '',$requireLevel = 1,$errMsg = ''){
		if (file_exists($file)){
			$this->constraint('@include('.$file.')',$requireLevel,$errMsg);
		} else {
			$this->constraint('false',$requireLevel,$errMsg);
		}
	}

	/**
	* Requires file provided by user.  Levels can be extended simply by adding to the switch statement to this->constraint
	* First, existance of file is checked.  If that is true, the it uses the constraint method to perform the inclusion of the file
	* If file does not exist, the constraint function is called, this time with a predermined 'false' inserted, and it handles the rest
	*/	
	function requireFile($file = '',$requireLevel = 1,$errMsg = 'Required file does not exist Script Terminated...good bye!'){
		if (file_exists($file)){
			$this->constraint('@require('.$file.')',$requireLevel,$errMsg);
		} else {
			$this->constraint('false',$requireLevel,$errMsg);
		}
	}
}
?>