KorsaR-ZN

$user = 'mi@user';
$pass = 'la@pass';
$url = 'https://site.ru/api/upload.xml';
$file = $_SERVER['DOCUMENT_ROOT'] . '\\orders\\shipments_22.10.2010_part_1.xml';
$boundary = '---------------------' . substr(md5(rand(0, 32000)), 0, 10);

$postData = '';
$postData .= '--' . $boundary . "\n";
$postData .= 'Content-Disposition: form-data; name="orders"; filename="' . basename($file) . '"' . "\n";
$postData .= 'Content-Type: text/xml' . "\n";
$postData .= 'Content-Transfer-Encoding: binary' . "\n\n";
$postData .= file_get_contents($file) . "\n";
$postData .= '--' . $boundary . "\n";

$params = array
(
    'http' => array
    (
        'method' => 'POST',
        'content' => $postData,
        'header' => array
        (
            'Authorization: Basic ' . base64_encode($user . ':' . $pass),
            'Content-Type: multipart/form-data; boundary=' . $boundary
        )
    )
);

$context = stream_context_create($params);