On Wed, Oct 29, 2025 at 05:26:20PM +1100, David Gibson wrote:
> The fact that outbound forwarding sockets are bound to the loopback
> address, whereas inbound forwarding sockets are (by default) bound to
> the unspecified address leads to some unexpected differences between
> the paths setting up each of them.
> 
> An idea for tackling bug 100 suggested a different approach which will
> also reduce some of those differences and allow more code to be shared
> between the two paths.  I've since discovered that this approach may
> not help for bug 100, but it might still be worthwhile for the clean
> up.
> 
> Patches 1..6/8 are cleanups which shouldn't change behaviour, and I
> think are ready to merge.  7/8 is (arguably) a behavioural change, but
> I've made my case for it in the patch comment.  8/8 needs some further
> consideration, since I've discovered it does not fix bug 100 as is,
> I'm including it for advance review, though.

Follow up on 8/8 now I've looked into SO_BINDTODEVICE semantics more
clearly.  Unfortunately this approach won't work to fix bug 100 [0].
I still think the change is useful for the internals and it may also
help with some other bugs such as 113.

So, I don't think the code of 8/8 needs to change, but the comments
and commit message do.

Here's my plan:
 - I'll wait for review on this draft
 - If it needs a respin, I'll make those doc changes in the next
   version
 - If the series doesn't need a respin, go ahead and apply 1..7, and
   I'll send a revised 8/8 separately.

[0] https://bugs.passt.top/show_bug.cgi?id=100#c8

-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson