Bug#1051477: dnssd: IPv6: fails to resolve services

[Luca Boccassi]

Control: close -1

On Fri, 08 Sep 2023 15:11:33 +0100 Tj <debian at iam.tj> wrote:
> Package: systemd-resolved
> Version: 252.14-1~deb12u1
> Severity: normal
> Tags: ipv6 upstream
> 
> Reported upstream and tracked as:
> 
> https://github.com/systemd/systemd/issues/29120
> 
> Two hosts on the same link of an IPv6-only network. Host A is unable
to resolve a service record advertised by host B using `resolvectl`
where each has multiple IPv6 addresses (link-local, ULA, and global).
> 
> When host A does `resolvectl -i LOCAL service _apt-proxy._tcp local.`
it sends from the link-local address. Host B ignores it.
> When host A does `avahi-browse -rt _apt-proxy._tcp` it sends from a
global address. Host B responds but sends the response from its link-
local address to the multicast group.
> 
> This affects tools like `auto-apt-proxy` that uses `apt-helper
> srv-lookup ...` and that talks to the system resolver configured in
> `/etc/resolv.conf` which is systemd-resolve's stub entry when
> systemd-resolved is active.
> 
> I was hoping to figure it out and have been working in the source-
code
> but so far not identified anything. It looks to be due to how the
> multicast DNS (`src/resolve/resolved-mdns*`) discards packets for
> various reasons on reception.

This is tracked upstream, there are no patches nor configuration
downstream, closing.

-- 
Kind regards,
Luca Boccassi
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