[Dnsmasq-discuss] dhcpv6 problem with static allocations and "no addresses available"

[Carlos Carvalho]

I'm stumbling on an important problem that looks like a bug in dnsmasq. Clients
declared statically in a zone are being denied their address with the message
"no addresses available":

Oct 20 09:56:10 dnsmasq-dhcp[18342]: 6947286 available DHCPv6 subnet: 2801:82:80ff:7f05::/64
Oct 20 09:56:10 dnsmasq-dhcp[18342]: 6947286 vendor class: 40712
Oct 20 09:56:10 dnsmasq-dhcp[18342]: 6947286 client MAC address: 10:bf:48:71:65:99
Oct 20 09:56:10 dnsmasq-dhcp[18342]: 6947286 DHCPSOLICIT(meteo) 00:01:00:01:1d:a8:3f:4a:10:bf:48:71:65:99 
Oct 20 09:56:10 dnsmasq-dhcp[18342]: 6947286 DHCPADVERTISE(meteo) 00:01:00:01:1d:a8:3f:4a:10:bf:48:71:65:99 no addresses available
Oct 20 09:56:10 dnsmasq-dhcp[18342]: 6947286 tags: known, dhcpv6, meteo
Oct 20 09:56:10 dnsmasq-dhcp[18342]: 6947286 sent size: 14 option:  1 client-id  00:01:00:01:1d:a8:3f:4a:10:bf:48:71:65:99
Oct 20 09:56:10 dnsmasq-dhcp[18342]: 6947286 sent size: 10 option:  2 server-id  00:03:00:01:00:24:8c:0c:37:90
Oct 20 09:56:10 dnsmasq-dhcp[18342]: 6947286 sent size: 24 option: 13 status  2 no addresses available

Note that the client is recognized because the known tag is set. The dhcp
config is the following:

interface=meteo
dhcp-range=::,constructor:meteo,static,infinite
enable-ra
dhcp-range=192.168.5.1,static

dhcp-host=cobb,192.168.5.11,[2801:82:80ff:7f05:12bf:48ff:fe71:6599],10:bf:48:71:65:99,id:00:01:00:01:1d:a8:3f:4a:10:bf:48:71:65:99
[other dhcp-host declarations]

dhcp-host=elbrus,192.168.5.75,[2801:82:80ff:7f05:12bf:48ff:fe79:aa07],10:bf:48:79:aa:07,id:*

At first I tried to use only id:* for all machines but started getting refusals
like the above. I noticed that the DUID was changing, so I fixed it in the
client. Still got sporadic refusals (it doesn't happen everytime?!). Then I put
the full id in the config as shown above for host cobb. Even then dnsmasq is
refusing it. How can this be? Also, the refusal is for IPv6 only.

There's no collision with other declarations omitted above, I checked with
grep.

This is important because these hosts are diskless and without the IP they
cannot access the root server and thus don't boot.

On a related issue, is it possible to always use only the hardware address for
dhcpv6 and not the full DUID? In my case it may happen when diffent programs
are used for requests, such as UEFI firmware and linux in diskless stations.
Since the machine doesn't have permanent storage it's difficult to keep the
DUID constant.