On Thu, Feb 20, 2020 at 5:18 PM Leppanen, Jere (Nokia - FI/Espoo)
<jere.leppanen@xxxxxxxxx> wrote:
>
> Hello All,
>
> According to the RFC, a peeled-off socket is a one-to-one socket. But in lksctp a peeled-off socket it not TCP style, it's UDP_HIGH_BANDWIDTH style. Because of this, shutdown() doesn't work, linger probably doesn't work, and so on.
>
> For example, in sctp_shutdown():
>
> static void sctp_shutdown(struct sock *sk, int how)
> {
> struct net *net = sock_net(sk);
> struct sctp_endpoint *ep;
>
> if (!sctp_style(sk, TCP))
> return;
>
> Here we just bail out, because a peeled-off socket is not TCP style.
>
> Is this just a bug, or am I missing something? Asking mostly out of personal curiosity.
I would say, it's because .shutdown is tcp_prot thing and udp_prot doesn't
have. sctp doesn't have to implement it for UDP style socket. But for TCP-
style socket, sctp is trying to be compatible with TCP protocol user API.
But even though, sctp's .shutdown is still not fully compatible with TCP
protocol due to sctp's 3-way shakehands for finishing a connection.
