[systemd-devel] Regression in ipv6 resolutions in systemd-resolved with AF_UNSPEC

[Yuriy M. Kaminskiy]

On 19.02.2016 18:26, Lennart Poettering wrote:
> On Fri, 19.02.16 15:43, Sébastien Luttringer (seblu at seblu.net) wrote:
>
>> Hello,
>>
>> Since systemd v229, I have one server which no more resolve ipv6 adresses when
>> it use nss-resolve and AF_UNSPEC.
>>
>> This issue seems to be linked with the DNS resolver used on its network. This
>> resolved is provided by a french FAI box (SFR).
>>
>> I'm currently not able to understand precisely where is the issue, but opening
>> the socket with AF_UNSPEC does not resolve ipv6 and with AF_INET6
>> does.
>
> Note that resolved will not look up IPv6 addresses if this isn't
> explicitly requested if there are no local routable IPv6 addresses
> configured. And vice versa, it won't look for IPv4 addresses if this

Maybe I'm missing something, but That looks ...problematic. To extreme.
So, I cannot

getent ahosts www.freedesktop.org | while read a rest; do
    case $a in
    *:*) ip6tables -A OUTPUT -d $a -j REJECT;;
    *.*) iptables -A OUTPUT -d $a -j REJECT;;
    esac
done

*before* I've got my ipv6 connectivity up and running?

> isn't explicitly requested and there are no local routable Ipv4
> addresses configured. Basically, when doing lookups without specifying

Same, but if I have ipv6-only native connectivity and my ipv4 tunnel is 
not up yet?

> what you want, we'll return something that you can actually talk
> to. If during resolving you however specify what you want, then we'll
> actually return that.
>
> How precisely does your IP configuration look like? Do you use
> per-interface DNS servers (i.e. configured via networkd), or do you
> have global DNS servers configured via /etc/resolv.conf or via DNS= in
> /etc/systemd/resolved.conf?
>
> If you use per-interface DNS servers, do you have a routable IPv6
> address on that interface? If you use global DNS servers instead, do
> you have any routable Ipv6 address on any interface?