function search()
{
    if (!isset($_POST['s_content'])) {
        return Receive::send_ms("lack the post variables.");
    }
    if (empty($_POST['s_content'])) {
        return Receive::send_ms("输入内容后再搜搜。");
    }
    $content = addcslashes(trim($_POST['s_content']), specialcharacter);
    if ($_POST['client'] == '1') {
        $receive = new Receive($content, '', '', false, true);
    } else {
        $receive = new Receive($content, '', '', false);
    }
    return Receive::send_ms($receive->search());
}
    return Receive::send_ms("nothing...");
}
if (empty($_POST['method']) || empty($_POST['user'])) {
    return Receive::send_ms("the variable cannot be blank.");
}
$user = addcslashes(trim($_POST['user']), specialcharacter);
$method = addcslashes(trim($_POST['method']), specialcharacter);
switch ($method) {
    case 'get':
        $receive = new Receive('', '', $user, true);
        return stripcslashes($receive->rec_challenge());
        break;
    case 'post':
        if (!isset($_POST['content'])) {
            return Receive::send_ms("no post content.");
        }
        if (empty($content = addcslashes(trim($_POST['content']), specialcharacter))) {
            return Receive::send_ms("the variable cannot be blank.");
        }
        $receive = new Receive($content, '', $user, true);
        // echo $content;
        if ($receive->new_challenge()) {
            return Receive::send_ms("提交成功。");
        } else {
            return Receive::send_ms("提交失败。");
        }
        break;
    default:
        return Receive::send_ms("unknown method.");
        break;
}