Re: [PATCH 1/4][CONNTRACK] Introduce flag facilities to take over TCP connections

[Patrick McHardy <kaber@trash.net>]

Pablo Neira Ayuso wrote:
> This patch introduces two new flags called IPS_PICKUP that forces the
> protocol handler to pick up the window of valid TCP packets and
> IPS_IN_WINDOW to by pass window checkings.
> 
> Moreover, four new attributes to inject the window scale factor and
> enable SACK are introduced. These new facilities provide the appropiate
> mechanisms to take over TCP connections in failover settings with TCP
> tracking enabled.

I still think a simple flag/mask attribute would be nicer and
would save lots of code. The TCP flag values are already exposed
to userspace. Something like:

CTA_PROTOINFO_TCP_FLAGS_ORIGINAL:

struct tcp_flags {
	u_int32_t flags;
	u_int32_t mask;
};

ct->proto.tcp.seen[].flags &= ~attr->mask;
ct->proto.tcp.seen[].flags |= attr->flags & attr->mask;

Even better might be to nest all directional attributes under
a CTA_ORIGNAL/CTA_REPLY attribute.