Bug#952894: cups: Bad Request for FQDN without explicit ServerAlias

[Kevin Locke <kevin@kevinlocke.name>]

Package: cups
Version: 2.3.1-7
Severity: normal

Dear Maintainer,

Accessing CUPS via https://hostname:631 works while
https://hostname.example.com:631 fails with 400 Bad Request if
cupsd.conf does not contain either "HostNameLookups on" or
"ServerAlias printserver.example.com".  This is a divergence from
upstream, where the FQDN returned by gethostname(2) is automatically
added as a ServerAlias.

It appears to be an untended side-effect of
0026-Do-not-use-host-names-for-broadcasting-print-queues-.patch for
LP#449586.  Perhaps we could consider a different way to disable name
broadcasting without removing the ServerAlias for the FQDN which is used
for HTTP host checking?

Thanks,
Kevin

-- System Information:
Debian Release: bullseye/sid
  APT prefers testing
  APT policy: (990, 'testing'), (500, 'unstable'), (101, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 5.5.5 (SMP w/4 CPU cores)
Kernel taint flags: TAINT_OOT_MODULE
Locale: LANG=en_US.utf8, LC_CTYPE=en_US.utf8 (charmap=UTF-8), LANGUAGE=en_US.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages cups depends on:
ii  cups-client            2.3.1-7
ii  cups-common            2.3.1-7
ii  cups-core-drivers      2.3.1-7
ii  cups-daemon            2.3.1-7
ii  cups-filters           1.27.1-1
ii  cups-ppdc              2.3.1-7
ii  cups-server-common     2.3.1-7
ii  debconf [debconf-2.0]  1.5.73
ii  ghostscript            9.50~dfsg-5
ii  libavahi-client3       0.7-5
ii  libavahi-common3       0.7-5
ii  libc6                  2.29-10
ii  libcups2               2.3.1-7
ii  libgcc-s1              10-20200222-1
ii  libstdc++6             10-20200222-1
ii  libusb-1.0-0           2:1.0.23-2
ii  poppler-utils          0.71.0-6
ii  procps                 2:3.3.15-2+b1

Versions of packages cups recommends:
pn  avahi-daemon  <none>
pn  colord        <none>

Versions of packages cups suggests:
pn  cups-bsd                                   <none>
pn  cups-pdf                                   <none>
ii  foomatic-db-compressed-ppds [foomatic-db]  20191126-1
ii  smbclient                                  2:4.11.5+dfsg-1
ii  udev                                       244.3-1

-- debconf information excluded