openl2tp.org

hello
thank for your reply for my question . I want send buf and recv buf using pppol2tp .I have create pppo connect between lan and lns.
this time I saw the openl2tp code and pppol2tp.c.I have a few question to ask。
1 I find I didn't use the func of htons(). so I should use this func when step in the arg of peer_port or our_port.is it right?
2. udp_fd of the sample pppol2tp code . is the (struct l2tp_tunnel)tunnel->fd,is it right ?
3. my send buf code is another app,not in the openl2tpd, when I use the fd ,it is said " Bad file descriptor", it means they are not in a app.and I cannt use the fd in another app .Is it right ? so what is your suggestion about use the udp_fd ? should I use the fd in the openl2tpd app, or I should use the fd in some way in another app?
thank you