Re: bin/57957: dhcpcd fails to unconfigure addresses from released lease

[Roy Marples <roy%marples.name@localhost>]

 ---- On Sun, 25 Feb 2024 15:13:03 +0000  Taylor R Campbell  wrote --- 
 > > Date: Sun, 25 Feb 2024 15:05:01 +0000 (UTC)
 > > From: Robert Elz kre%munnari.OZ.AU@localhost>
 > > 
 > > But that would still be wrong, the old addresses should expire,
 > > but weren't (and apparently didn't for Taylor either).
 > 
 > Just to clarify: the issue I observed is that the old DHCPv6-assigned
 > addresses weren't removed.

Why should they be? They obey the same rules as RA addresses in that removal is either manual or a zero lifetime is emitted.
Now IA options can include a  status code such as NotOnLink, but there is no indication in the RFC that any existing address should be removed.
Infact it's recommendation to enter discovery mode and find a new DHCPv6 server.

Is the lifetime of the address continously decreasing or does it ever increase?

> (and kept getting used as default source
 > addresses).

I find this statement odd because DHCPv6 addresses are not tied to any route.
Infact there is zero routing in DHCPv6 because RA covers it nicely.

>  The SLAAC addresses with the old prefix, in contrast, did
> get removed and replaced by SLAAC addresses with the new prefix.
 
The error in dhcpcd is that when a prefix derived route changes it's address the source address in the route is not changed.
But I don't think this is what you are seeing.