<?php
 
/**
 * class to compare an ip address against a given range of IPs 
 * 
 * sample usage
 * <code>
 $ipRangeCompare = new IPRangeCompare;
 $result = $ipRangeCompare->compare('212.143.142.1', '212.142.142.1', '212.143.140.255');
 if ($ipRangeCompare->isError){
 	echo $ipRangeCompare->getErrorMessages();
 	exit;
 } else {
 	if ($result){
 		echo "Confirmed that $ipRangeCompare->ip is within the range $ipRangeCompare->startIP - $ipRangeCompare->endIP";
 	} else {
 		echo "Confirmed that $ipRangeCompare->ip is NOT within the range $ipRangeCompare->startIP - $ipRangeCompare->endIP";
 	}
 }
 * </code>
 */
 
class IPRangeCompare{
 
	public $endIP;
	public $startIP;
	public $ip;
	public $errors;
 
	public $isError;
 
	/**
	 * constructor method
	 * @return 
	 */
	public function __construct(){
		$this->flush();
	}
 
	/**
	 * public method that kick starts the engine.  
	 * 
	 * @return bool - true if the IP is in the provided range, false otherwise
	 * 
	 * @param object $startIP
	 * @param object $endIP
	 * @param object $ip
	 */
	public function compare ($startIP, $endIP, $ip){
		$this->flush();
		$this->startIP = $startIP;
		$this->endIP = $endIP;
		$this->ip = $ip;
		if (!$this->isValidIP($this->startIP) || !$this->isValidIP($this->endIP) || !$this->isValidIP($this->ip)){
			$this->setError('IP address provided is not valid');
			return false;
		}
		$this->startIPDecimal = $this->getDecimalIP($this->startIP);
		$this->endIPDecimal = $this->getDecimalIP($this->endIP);
		$this->ipDecimal = $this->getDecimalIP($this->ip);
		$this->checkIPDirection();
 
		$match = ($this->ipDecimal >= $this->startIPDecimal) && ($this->ipDecimal <= $this->endIPDecimal);
		return $match;
	}
	/**
	 * public function to return the error messages
	 * 
	 * @return string
	 */
	public function getErrorMessage(){
		$return = '';
		if ($this->isError){
			foreach ($this->errors as $e){
				$return .= "\r\n<div class=\"errorMessage\">$e</div>\r\n";
			}
		}
		return $return;
	}
 
	/**
	 * method to invert start and end ip addresses if they have been entered the wrong way around
	 * 
	 * @return void
	 */
	private function checkIPDirection(){
		if ($this->startIPDecimal > $this->endIPDecimal){
			$temp = $this->endIPDecimal;
			$this->endIPDecimal = $this->startIPDecimal;
			$this->startIPDecimal = $temp;
			$temp = $this->endIP;
			$this->endIP = $this->startIP;
			$this->startIP = $temp;
		}
	}
 
	/**
	 * private method to convert an octet based IP address to a decimal
	 * 
	 * @return decimal IP address
	 * @param string $ip
	 */
	private function getDecimalIP($ip){
                return ip2long($ip);
                /* left in for historic reasons only
		$bits = explode ('.', $ip);
		//convert the octets to binary
		foreach ($bits as $bit){
			$_bits[] = str_pad(decbin($bit), 8, '0', STR_PAD_LEFT);
		}
 
		//now implode the _bits
		$bin = implode('', $_bits);
		//convert to decimal
		$dec = bindec($bin);
 
		return $dec;
                */
	}
 
	/**
	 * private method for determining whether the ip address provided is in the right format
	 * 
	 * @return bool: true for the right format, false otherwise
	 * @param object $ip
	 */
	private function isValidIP($ip){
		$pattern = '/(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})/ims';
		$result = preg_match($pattern, $ip, $matches);
		if (!$result){
			return false;
		}
		for($i=1; $i<=4; $i++){
			if ($matches[$i] < 0 || $matches[$i] > 255){
				return false;
			}
		}
		return true;
	}
 
	/**
	 * private helper method to set error messages
	 * 
	 * @return void
	 * @param object $error
	 */
	private function setError($error){
		$this->errors[] = $error;
		$this->isError = true;
	}
 
 
	/**
	 * private method for zeroing the variables
	 * @return 
	 */
	private function flush(){
		$this->errors = array();
		$this->startIP = $this->endIP = $this->ip = null;
		$this->isError= false;
	}
}
?>