Bug#1122015: systemd: autopkgtest 'test upstream' fails with dnsmasq 2.92~rc1-1

[Luca Boccassi]

On Fri, 05 Dec 2025 22:04:26 +0100 Sven Geuer <sge at debian.org> wrote:
> Source: systemd
> Version: 259~rc2-1
> Severity: important
> X-Debbugs-Cc: Simon Kelley <simon at thekelleys.org.uk>
> Control: affects -1 + src:dnsmasq
> 
> Dear Maintainer,
> 
> in testing, autopkgtest 'test upstream', apparently executed only on
> amd64 architecture, fails with dnsmasq 2.92~rc1-1 from unstable [1].
It
> specifically fails in TEST-85-NETWORK-NetworkdDHCPClientTests,
> test_dhcp_client_reject_captive_portal [2]. Tests with dnsmasq 2.91-1
> succeeded [3].
> 
> As to me, the logs don't reveal enough details about how dnsmasq
might
> trigger this failure. I therefore ask for help on this issue.
> 
> PS.: No other autopkgtest involving dnsmasq shows abnormalities [4].

You can find more information by downloading the 'artifacts' tar.gz and
extracting the journal file from it.

This is the test that fails:

https://github.com/systemd/systemd/blob/a895fb38bb615b7ddd29e14d876485701b445eaf/test/test-network/systemd-networkd-tests.py#L8604

It is starting dnsmasq as such:

start_dnsmasq('--dhcp-option=114,' + masq(b'http://\x00invalid/url'),
     '--dhcp-option=option6:103,' +  masq(b'http://\x00/invalid/url'))

(full cmdline:
https://github.com/systemd/systemd/blob/a895fb38bb615b7ddd29e14d876485701b445eaf/test/test-network/systemd-networkd-tests.py#L857
)

So there should be no 'captive portal' visible given the invalid
addresses.

But there is:

   Captive Portal: 68:74:74:70:3a:2f:2f:00:69:6e:76:61:6c:69:64:2f:75:72:6c

Did something change in dnsmasq in the new version related to any of
this?