VK API Audio Upload

<?php
function api($method, $params = array()) {
    $token = $_SESSION["token"];
    $paramstr = http_build_query($params);
    $url = "https://api.vk.com/method/" . $method . "?" . $paramstr . "&access_token=" . $token;
    echo "query url: " . $url . "<br />\n";
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_HEADER, 0);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_URL, $url);
    $data = curl_exec($ch);
    echo "response:<br />\n" . $data . "<br /><br />\n";
        curl_close($ch);
    return json_decode($data);
}
session_start();

if (!isset($_SESSION["token"]))
    header('Location: http://api.vk.com/oauth/authorize?client_id=2642786&scope=audio&redirect_uri=http://home.makarushin.ru/apitest/auth_audio.php&response_type=code');


if ($_SERVER["REQUEST_METHOD"]=="POST") {
    $r = api("audio.getUploadServer");
    $ch = curl_init($r->response->upload_url);
    curl_setopt($ch, CURLOPT_HEADER, 0);
    curl_setopt($ch, CURLOPT_VERBOSE, 0);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_POST, true);
    curl_setopt($ch, CURLOPT_POSTFIELDS, array("file" => "@test.mp3"));
    curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_0);
    $audio = json_decode(curl_exec($ch));
    curl_close($ch);
    var_dump($audio);

    $r = api("audio.save", array(
        "server" => $audio->server,
        "audio" => $audio->audio,
        "hash" => $audio->hash
    ));
}
?>
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8" />
<title>API test</title>
</head>
<body>
    <form method="post">
        <input type="submit" value="test" />
    </form>
</body>
</html>