In some cases we refuse a query based on the RR type, mostly old
deprecated types. Let's return NOTIMP in this case, which best
communicates why the query failed.
In the current testing scheme in test-extract-word, we only
have two test cases covering unicode strings. Improve upon
this by adding more cases for the same.
Signed-off-by: Chandra Pratap <chandrapratap3519@gmail.com>
The name resolver.arpa is reserved for RFC9462 "Discovery of Designated
Resolvers" (DDR). This relies on regular dns queries for SVCB records at
the special use domain name _dns.resolver.arpa. Unfortunately, older
nameservers (or broken ones) won't know about this SUDN and will likely
return NXDOMAIN. If this is cached, the cache entry will become an
impediment for any clients trying to discover designated resolvers
through the stub-resolver, or potentially even sd-resolved itself, were
it to implement DDR.
The RFC recommendation is that "clients MUST NOT perform A or AAAA
queries for resolver.arpa", and "resolvers SHOULD respond to queries of
any type other than SVCB for _dns.resolver.arpa. with NODATA and queries
of any type for any domain name under resolver.arpa with NODATA." which
should help avoid potential compatibility issues. This enforces that
condition within sd-resolved, and avoids caching any such erroneous
NXDOMAIN.
The RFC also recommends requests for this domain should never be
forwarded, to prevent authentication failures. Since there isn't much
point in establishing secure communication to the local stub, we still
allow SVCB to be forwarded from the stub, in case the client cares to
implement some other authentication method and understands the
consequences of skipping the local stub. Normal clients are not
expected to implement DDR, but this change will protect sd-resolved's
own caches in case they try.
Although A and AAAA are prohibited, I think validating resolvers
might reasonably query for dnssec records, even though the resolver.arpa
zone does not exist (it is declared to be a locally served zone). For
this reason, I have also added resolver.arpa to the builtin dnssec NTA.
In some cases there is no configured server to answer a given question,
because all scopes refused the query. In this case we currently return
rcode SERVFAIL.
In dns it is customary for authoritative nameservers to return REFUSED
where the question is outside of their authority. This is better than
SERVFAIL because it informs the client that they aren't likely to get an
answer out of us anytime soon, and either the configuration, or the
query, need to change.
Similar logic invites us to use use the rcode REFUSED on the stub if we
aren't configured with any suitable scope for this question.
This brings the handling of config for kernel-install in line with most of
systemd, i.e. we search the set of paths for the main config file, and the full
set of drop-in paths for drop-ins.
This mirrors what 07f5e35fe7 did for udev.conf.
That change worked out fine, so I hope this one will too.
The update in the man page is minimal. I think we should split out a separate
page for the config file later on.
One motivating use case is to allow a drop-in to be created for temporary
config overrides and then removed after the operation is done.
This means the main config file is loaded also from /run and /usr.
We should load the main config file from all the places where we load drop-ins.
I realize I had a giant blind spot: I always assumed that we load config files
from /etc, /run, /usr/local/lib, /usr/lib. But it turns out that we only used
those paths for drop-ins. For the main config file, we only looked in /etc. The
docs actually partially described this behaviour, i.e. most SYNOPSIS sections
and some parts of the text, but not others.
This is strange, because 6495361c7d was completely
bogus with the behaviour before this patch. We had a huge discussion before it
was merged, and clearly nobody noticed this. Similarly, in the previous version
of the current pull request, we had a long discussion about the appropriate
order of directories, and apparently nobody noticed that there was no order,
because only looked in one directory. So the blind spot seems to have been
shared.
Also, systemd-analyze cat-config behaved incorrectly, i.e. its behaviour matches
the new behaviour.
Possibly, in the future it'll make it easier to add support for --root.
