[lwip-devel] [bug #19722] when incoming segment is out-of-sequence, recv_wnd should be update too

[Kieran Mansley]

Follow-up Comment #1, bug #19722 (project lwip):

I'm not so sure.  Can you explain why you think we should make the recv
window small when queueing out of order segments?

The recv window tells the other end how much it can send (relative to the ACK
in the packet) to us.  When we get out of order data we don't ACK it, so the
ACK doesn't change.  If we made the recv window smaller, we would be telling
the other end it can send less than it could before, which is rather naughty
and seems unecessary.  We should still be able to accept the same amount of
data regardless of the order we receive it in.

If memory is so tight that you want to advertise a smaller window because
some has been taken up buffering the out of order packet, I think a better
solution would be to turn off queueing of the out of order segments, which
would make lwIP discard them and force the other end to retransmit in-order.

However, if you can explain why, I'm happy to change my mind.

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