MAKE book IP limiter (req'd by @rashidi_life)

ip_limiter.php

#    
		// check if customer hash correct
		loadDbs(array('customers'));
		$query=$customersDb->prepare("SELECT * FROM customers WHERE secret_hash=:secret_hash");
		$query->bindValue(':secret_hash',$_GET['hash']);
		$query->execute();
		$customers=$query->fetchAll(PDO::FETCH_ASSOC);
		$customer=$customers[0];

		if(!empty($customer) && $customers[0]['secret_hash']==$_GET['hash']) {
			$userPaidForBook=true;
			$customer=$customers[0];
		}
		else {
			echo "Can't find hash, sorry!";
			$_COOKIE['hash']='';
			unset($_COOKIE);
			unset($_SESSION);
			exit;
		}

		if($customers[0]['ip_addresses']!=='allow_infinite') {
			if(!empty($customers[0]['ip_addresses'])) {
				$ips=explode("\n",$customers[0]['ip_addresses']);
				$maxIps=4;
				if(count($ips)>$maxIps) {
					list($epoch,$ip)=explode("\t",$ips[0]);
					$ip=trim($ip);
					// if oldest (first) IP usage was within 24 hours, it means there's $maxIps IPs that used it within last 24h, so we lock
					// otherwise remove the oldest IP, and add the new one
					if($epoch>strtotime("-24 hours")) {
						echo "Too many different IPs have accessed this book, to protect file sharing, the book is locked. Try again later!";
						echo '<hr><pre>';
						foreach($ips as $ip_line) {
							list($epoch,$ip)=explode("\t",$ip_line);
							echo date('c',$epoch);
							echo "\t";
							echo $ip;
							echo "\n";
						}
						exit;
					}
				}
				$newIps=array();
				foreach($ips as $ip_line) {
					list($epoch,$ip)=explode("\t",$ip_line);
					$ip=trim($ip);
					if($ip!=$_SERVER['REMOTE_ADDR']) {
						array_push($newIps,$ip_line);
					}
				}
				if(count($newIps)>$maxIps) {
					// pop first element off IPs
					array_shift($newIps);
				}
				$ips=$newIps;
			}
			else {
				$ips=array();
			}

			array_push($ips,time()."\t".$_SERVER['REMOTE_ADDR']);

			$ip_addresses_string='';
			foreach($ips as $ip_line) {
				$ip_addresses_string=$ip_addresses_string.$ip_line."\n";
			}
			// remove \n last
			$ip_addresses_string=substr($ip_addresses_string,0,strlen($ip_addresses_string)-1);


			// save new IP to db
			$query=$customersDb->prepare("UPDATE customers SET ip_addresses=:ip_addresses WHERE secret_hash=:secret_hash");
			$query->bindValue(':secret_hash',$_GET['hash']);
			$query->bindValue(':ip_addresses',$ip_addresses_string);
			$query->execute();