A failing transaction might cause other transactions to fail too, and
thus the set of transactions to notify for a transaction might change
while we are notifying them. Protect against that.
We end up needing the stringified transaction key in many log messages,
hence let's simplify the logic and cache it inside of the transaction:
generate it the first time we need it, and reuse it afterwards. Free it
when the transaction goes away.
This also updated a couple of log messages to make use of this.
Output the same message when a request to change the log level is
received over dbus and through a signal. From the user point of view
those two operations are very similar and it's easy to think that the
dbus operation didn't work when the expected message is not emitted.
Also "downgrade" the message level to info, since this is a normal
user initiated action.
This way we can only print the debug message when the status actually
changes. We also means we don't print anything when running in --user
mode, where status output is always disabled.
This changes answer validation to be more accepting to unordered RRs in
responses. The agorithm we now implement goes something like this:
1. populate validated keys list for this transaction from DS RRs
2. as long as the following changes the unvalidated answer list:
2a. try to validate the first RRset we find in unvalidated answer
list
2b. if that worked: add to validated answer; if DNSKEY also add to
validated keys list; remove from unvalidated answer.
2c. continue at 2a, with the next RRset, or restart from the
beginning when we hit the end
3. as long as the following changes the unvalidated answer list:
3a. try to validate the first RRset again. This will necessarily
fail, but we learn the precise error
3b. If this was a "primary" response to the question, fail the
entire transaction. "Primary" in this context means that it is
directly a response to the query, or a CNAME/DNAME for it.
3c. Otherwise, remove the RRset from the unvalidated answer list.
Note that we the too loops in 2 + 3 are actually coded as a single one,
but the dnskeys_finalized bool indicates which loop we are currently
processing.
Note that loop 2 does not drop any invalidated RRsets yet, that's
something only loop 3 does. This is because loop 2 might still encounter
additional DNSKEYS which might validate more stuff, and if we'd already
have dropped those RRsets we couldn't validate those anymore. The first
loop is hence a "constructive" loop, the second loop a "destructive"
one: the first one validates whatever is possible, the second one then
deletes whatever still isn't.
This adds a new validation result DNSSEC_UNSUPPORTED_ALGORITHM which is
returned when we encounter an unsupported crypto algorithm when trying
to validate RRSIG/DNSKEY combinations. Previously we'd return ENOTSUPP
in this case, but it's better to consider this a non-error DNSSEC
validation result, since our reaction to this case needs to be more like
in cases such as expired or missing keys: we need to keep continue
validation looking for another RRSIG/DNSKEY combination that works
better for us.
This also reworks how dnssec_validate_rrsig_search() propagates errors
from dnssec_validate_rrsig(). Previously, errors such as unsupported
algorithms or expired signatures would not be propagated, but simply be
returned as "missing-key".
Instead of figuring out how many RRs to cache right before we do so,
determine this at the time we install the answer RRs, so that we can
still alter this as we manipulate the answer during validation.
The primary purpose of this is to pave the way so that we can drop
unsigned RRsets from the answer and invalidate the number of RRs to
cache at the same time.
We later rely that the DnsAnswer object contains all RRs from the
original packet, at least when it comes to the answer and authorization
sections, hence we better make sure we don#t silently end up removing an
OPT RR from these two sections.
When the DNS_RESOURCE_KEY_CACHE_FLUSH flag is not set for an mDNS packet, we should not flush
the cache for RRs with matching keys. However, we were unconditionally flushing the cache
also for these packets.
Now mark all packets as cache_flush by default, except for these mDNS packets, and respect
that flag in the cache handling.
This fixes 90325e8c2e.
