On 2025 Apr 26 (Sat) at 16:41:24 +0200 (+0200), Florian Obser wrote:
:On 2025-04-23 03:14 -07, Nick Owens <mischief@offblast.org> wrote:
:> hi,
:>
:> i moved and got a new isp (google fiber webpass). i moved my odroid-h2
:> gateway and plugged it in and got met with some dhcp6leased spam in the
:> log, where it kept sending renews. there seems to be a 'ruckus wireless'
:> (based on mac oui) sending back ia pd with iaid 0, t1 0, t2 0. ipv6 works
:> fine besides that, but dhcp6leased does not appear to follow the advice in
:> RFC 8415 S 21.21 that says the client needs to pick a renew time that isn't
:> too fast if the server gives 0.
:>
:> i've arbitrarily picked 1 day here on 0, this at least shuts up dhcp6leased
:> from spamming renews. i'm not really an ipv6 expert, happy to have
:> input or
:
:that section as this:
:
:   Recommended values for T1 and T2 are 0.5 and 0.8 times the
:   shortest preferred lifetime of the prefixes in the IA_PD that the
:   server is willing to extend, respectively.
:
:which dhcpleased implements. I wonder why I didn't implement the same
:thing in dhcp6leased, I even put an XXX in.
:
:Please try this (it also fixes the calculation of lease_time, it needs
:to be the smallest vltime, not the largest.):
:

See also the commentary in S 14.2, which S 21.21 references.

OK


:diff --git engine.c engine.c
:index 80c8d3bc1db..ac56c0f3e09 100644
:--- engine.c
:+++ engine.c
:@@ -873,7 +873,7 @@ parse_dhcp(struct dhcp6leased_iface *iface, struct imsg_dhcp *dhcp)
: 			goto out;
: 		}
: 
:-		if (lease_time < pd->vltime)
:+		if (lease_time == 0 || lease_time > pd->vltime)
: 			lease_time = pd->vltime;
: 
: 		log_debug("%s: pltime: %u, vltime: %u, prefix: %s/%u",
:@@ -928,9 +928,14 @@ parse_dhcp(struct dhcp6leased_iface *iface, struct imsg_dhcp *dhcp)
: 		iface->serverid_len = serverid_len;
: 		memcpy(iface->serverid, serverid, SERVERID_SIZE);
: 
:-		/* XXX handle t1 = 0 or t2 = 0 */
:-		iface->t1 = t1;
:-		iface->t2 = t2;
:+		if (t1 == 0)
:+			iface->t1 = lease_time / 2;
:+		else
:+			iface->t1 = t1;
:+		if (t2 == 0)
:+		    iface->t2 = lease_time - (lease_time / 8);
:+		else
:+			iface->t2 = t2;
: 		iface->lease_time = lease_time;
: 		clock_gettime(CLOCK_MONOTONIC, &iface->request_time);
: 		state_transition(iface, IF_BOUND);
:
:
:-- 
:In my defence, I have been left unsupervised.
:

-- 
You can't carve your way to success without cutting remarks.