kalkulacka ip

<?php

$maska = ""; $binmaska= ""; $broadcast = ""; $binbroadcast = ""; $prvaip = ""; $binprvaip = ""; $poslednaip = ""; $binposlednaip = ""; $pocetip = "";
$error = ""; $output = "";

if (isset($_POST['submit'])) {
    if(empty($_POST['prva']) && empty($_POST['druha']) && empty($_POST['tretia']) && empty($_POST['stvrta']) && empty($_POST['prefix'])){
        $error = "<strong>Vyplnte IP!</strong>";
    }else{
        $prva = strval(decbin($_POST['prva']));
        $druha = strval(decbin($_POST['druha']));
        $tretia = strval(decbin($_POST['tretia']));
        $stvrta = strval(decbin($_POST['stvrta']));
        $prefix = $_POST['prefix'];

        switch (strlen($prva)) {
            case 1:
                $prva = "0000000".$prva;
                break;
            case 2:
                $prva = "000000".$prva;
                break;
            case 3:
                $prva = "00000".$prva;
                break;
            case 4:
                $prva = "0000".$prva;
                break;
            case 5:
                $prva = "000".$prva;
                break;
            case 6:
                $prva = "00".$prva;
                break;
            case 7:
                $prva = "0".$prva;
                break;
        }

        switch (strlen($druha)) {
            case 1:
                $druha = "0000000".$druha;
                break;
            case 2:
                $druha = "000000".$druha;
                break;
            case 3:
                $druha = "00000".$druha;
                break;
            case 4:
                $druha = "0000".$druha;
                break;
            case 5:
                $druha = "000".$druha;
                break;
            case 6:
                $druha = "00".$druha;
                break;
            case 7:
                $druha = "0".$druha;
                break;
        }

        switch (strlen($tretia)) {
            case 1:
                $tretia = "0000000".$tretia;
                break;
            case 2:
                $tretia = "000000".$tretia;
                break;
            case 3:
                $tretia = "00000".$tretia;
                break;
            case 4:
                $tretia = "0000".$tretia;
                break;
            case 5:
                $tretia = "000".$tretia;
                break;
            case 6:
                $tretia = "00".$tretia;
                break;
            case 7:
                $tretia = "0".$tretia;
                break;
        }

        switch (strlen($stvrta)) {
            case 1:
                $stvrta = "0000000".$stvrta;
                break;
            case 2:
                $stvrta = "000000".$stvrta;
                break;
            case 3:
                $stvrta = "00000".$stvrta;
                break;
            case 4:
                $stvrta = "0000".$stvrta;
                break;
            case 5:
                $stvrta = "000".$stvrta;
                break;
            case 6:
                $stvrta = "00".$stvrta;
                break;
            case 7:
                $stvrta = "0".$stvrta;
                break;
        }

        $temp = $prva.$druha.$tretia.$stvrta;
        $temp = substr($temp, 0, $prefix);
        $temp = str_pad($temp, 32, "0", STR_PAD_RIGHT);
        $prvaip = bindec(substr($temp, 0, 8)).".".bindec(substr($temp, 8, 8)).".".bindec(substr($temp, 16, 8)).".".bindec(substr($temp, 24, 8));
        $binmaska = substr($temp, 0, 8).".".substr($temp, 8, 8).".".substr($temp, 16, 8).".".substr($temp, 24, 8);
        $maska = bindec(substr($temp, 0, 8)).".".bindec(substr($temp, 8, 8)).".".bindec(substr($temp, 16, 8)).".".bindec(substr($temp, 24, 8))."/".strval($prefix);


        $temp = $prva.$druha.$tretia.$stvrta;
        $temp = substr($temp, 0, $prefix);
        $temp = str_pad($temp, 32, "1", STR_PAD_RIGHT);
    $poslednaip = bindec(substr($temp, 0, 8)).".".bindec(substr($temp, 8, 8)).".".bindec(substr($temp, 16, 8)).".".bindec(substr($temp, 24, 8));
        $binbroadcast = substr($temp, 0, 8).".".substr($temp, 8, 8).".".substr($temp, 16, 8).".".substr($temp, 24, 8);
        $broadcast = bindec(substr($temp, 0, 8)).".".bindec(substr($temp, 8, 8)).".".bindec(substr($temp, 16, 8)).".".bindec(substr($temp, 24, 8))."/".strval($prefix);

        $pocetip = pow(2, 32-$prefix)-2;

        if(!empty($maska) || !empty($broadcast) || !empty($prvaip) || !empty($poslednaip)){

            $output = "<div class='output'>
                    <p>Maska siete: <strong>$binmaska</strong></p>
                    <p>Maska siete: <strong>$maska</strong></p>
                    <p>Broadcast siete: <strong>$binbroadcast</strong></p>
                    <p>Broadcast siete: <strong>$broadcast</strong></p>
                    <p>Prvá použiteľná IP: <strong>".substr($prvaip,0, -1).substr_replace($prvaip, substr($prvaip, -1)+1, 0)."</strong></p>
                    <p>Posledná použiteľná IP: <strong>".substr($poslednaip,0, -1).substr_replace($poslednaip, substr($poslednaip, -1)-1, 0)."</strong></p>
                    <p>Počet použiteľných IP: <strong>$pocetip</strong></p>
                </div>";

        }

    }

}



?>

<!DOCTYPE html>

<html>

<head>

    <title>RoyalPortal.eu</title>

    <meta name="author" content="Roman Vašek">

    <meta name="description" content="">

    <meta name="keywords" content="">

    <meta charset="UTF-8">

    <meta name="viewport" content="width=device-width, initial-scale=1">

    <link rel="stylesheet" type="text/css" href="assets/css/bootstrap.min.css">

    <style>

        body{

            margin-top: 3em;

        }

        label,input.form-control{

            display:  inline-block;

        }

        input.form-control{

            width: 4.75em;

        }

        .output{

            margin-top: .25em;

            text-align: left;

        }

    </style>

</head>

<body>

    <div class="container text-center">

        <?=$error?>

        <form method="post">

          <div class="form-group">

            <input type="number" class="form-control" min="0" max="255" name="prva" placeholder="<?=bindec($prva)?>">

            <label>.</label>

            <input type="number" class="form-control" min="0" max="255" name="druha" placeholder="<?=bindec($druha)?>">

            <label>.</label>

            <input type="number" class="form-control" min="0" max="255" name="tretia" placeholder="<?=bindec($tretia)?>">

            <label>.</label>

            <input type="number" class="form-control" min="0" max="255" name="stvrta" placeholder="<?=bindec($stvrta)?>">

            <label>/</label>

            <input type="number" class="form-control" min="1" max="32" name="prefix" placeholder="<?=$prefix?>">

          </div>

        <button type="submit" name="submit" class="btn btn-primary">Odoslať</button>

        </form>

        <?=$output?>

    </div>

</body>

</html>