[ovs-dev] [PATCH] datapath: Make port numbers for UDP-based tunnels userspace configurable.

[Ben Pfaff]

On Fri, Oct 28, 2011 at 06:37:42PM -0700, Jesse Gross wrote:
> On Fri, Oct 28, 2011 at 11:29 AM, Ben Pfaff <blp at nicira.com> wrote:
> > On Thu, Oct 27, 2011 at 04:38:39PM -0700, Jesse Gross wrote:
> >> On Wed, Oct 26, 2011 at 3:27 PM, Ben Pfaff <blp at nicira.com> wrote:
> >> > diff --git a/datapath/tunnel.c b/datapath/tunnel.c
> >> > index 372d90e..047961f 100644
> >> > --- a/datapath/tunnel.c
> >> > +++ b/datapath/tunnel.c
> >> > +static int tnl_sock_bind(const struct tnl_ops *tnl_ops, struct tnl_mutable_config *mutable)
> >> > +{
> >> > +#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,26)
> >> > + ?? ?? ?? struct sockaddr_in sin;
> >> > + ?? ?? ?? struct tnl_sock *ts;
> >> > + ?? ?? ?? int err;
> >> > +
> >> > + ?? ?? ?? if (tnl_ops->ipproto != IPPROTO_UDP)
> >> > + ?? ?? ?? ?? ?? ?? ?? return 0;
> >> > +
> >> > + ?? ?? ?? list_for_each_entry (ts, &tnl_socks, list) {
> >> > + ?? ?? ?? ?? ?? ?? ?? if (ts->port == mutable->dst_port) {
> >> > + ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? if (udp_sk(ts->socket->sk)->encap_rcv != tnl_ops->udp_rcv)
> >> > + ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? return -EADDRINUSE;
> >>
> >> When I originally proposed this, I thought that we could directly use
> >> the socket lookup to find the tunnel. ??I now see that it isn't
> >> possible because of the key (and there is no way to know whether the
> >> key is important until after you do the tunnel lookup). ??Is there any
> >> benefit to binding the socket more specifically to the tunnel using
> >> the remote and local (if there is one) IPs? ??The main benefit of this
> >> would be to enable finer grained binding of sockets for different
> >> tunnel types. ??I don't know whether that is more or less confusing
> >> though. ??It also makes the UDP socket lookup marginally faster.
> >
> > If I do that I think I'll need a hash table for the tnl_socks since
> > there's likely to be many of them (one per local/remote IP pair) if
> > someone configures a bunch of tunnels instead of just one (for a given
> > port).
> >
> > I'm willing to do it, your paragraph doesn't make me sure whether you
> > really want it though.
> 
> My gut feeling is that it's probably the right thing to do (and
> actually follow through to use the socket for tunnel lookup, modulo
> the key; in the keyless case we don't even have to anything else).  It
> doesn't excite me that much because it results in parallel code paths
> for UDP based protocols vs. everything else.  However, I think for
> upstreaming where we only have VXLAN it will look a lot more correct
> if we do it this way and it should perform slightly better as well.

OK, I'll do it that way.

>From some points of view having userspace pass in a fd for a socket that
it already opened would be a nice way to go, but I see multiple reasons
why it won't work.