Arcturus Emulator RCON PHP shell

shell.php

<?php
// replace $key with something secret or face peril!
error_reporting(E_ALL);
$key = 'secret';
$sec = $_GET['sec'];
$payload = $_POST['payload'];

if (isset($payload) && $sec == $key) {
  $sock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
  $res = socket_connect($sock, "127.0.0.1", 3001);

  if ($res === false) {
    echo "socket_connect() failed.<br />Reason: ($result) " . socket_strerror(socket_last_error($sock)) . "<br />";
  }
  
  $res = socket_write($sock, $payload, strlen($payload));
  if ($res === false) {
    echo socket_strerror(socket_last_error($sock)) . "<br />";
  }
  $out = socket_read($sock, 2048);
  echo "<textarea rows='2' cols='30' disabled>$out</textarea><br /><br />";
} else {
  $payload = '{
  "key": "action",
  "data": {
    "message": "-",
    "username": "-"
  }
}';
}

if (isset($sec) && $sec == $key) {
?>
  <form method="post">
    <input type="hidden" value="<?php echo $key; ?>" />
    <textarea rows="20" cols="90" name="payload"><?php echo $payload; ?></textarea><br />
    <button type="submit">Submit</button>
  </form>
<?php
}
else
{
  echo "lol";
}
?>