There was a misunderstanding whether to include them by default in
the dns.log, so remove them again.
There had also been a discussion and quirk that AD of a request would
always be overwritten by reply in the dns.log unless the reply is
missing. For now, let users extend dns.log themselves for what best
fits their requirements, rather than adding these flags by default.
Add a btest to print AD and CD flags for smoke testing still.
Parse authentic data (AD) and checking disabled (CD) bits according to
RFC 2535. Leaves the Z field as-is, in case users are already handling
this elsewhere and depend on the value being the integer for all 3 bits.
https://www.rfc-editor.org/rfc/rfc2535#section-6.1Fixes#2672
* 'fatemabw/bro' of https://github.com/fatemabw/bro:
DNSSEC support in Bro
I made several changes:
- renamed event/record types
- reformatted the info added to dns.log
- removed the "addl" scripts that added extended dnssec info to dns.log
- simplifications/improvements to the internal parsing logic
These have been lingering for a while and they generally annoy
everyone because of the sheer volume. They also don't really add
any useful information for debugging and they were generated differently
than most other weirds anyway (which was a little weird...).
This commit rewrites the way that weirds are logged and fixes a number
of issues on the way. Most prominently, flow weirds now actually log
information about the flow that they occur in (before this change, they
only logged the name of the weird, which is only marginally helpful).
Besides restructuring how weird logging works internally, weirds can now
also be generated by calling Weird::weird with the info record directly,
allowing more fine-granular passing of information. This is e.g. used
for DNS weirds, which do not have the connection record available any
more when they are generated (before data like the connection ID was
just not logged in these instances).
Addresses BIT-1578
The amount of timers involved in DNS::PendingMessage tables'
expiration attributes have a significant performance hit. Instead the
script now relies solely on maximum thresholds for pending message
quantities to limit amount of accumulated state. There's a new option,
"DNS::max_pending_query_ids", to limit the number outstanding messages
across all DNS query IDs ("DNS::max_pending_msgs" still limits number
of outstanding messages for a *given* query ID).
- Fix parsing of empty question sections (when QDCOUNT == 0). In this
case, the DNS parser would extract two 2-byte fields for use in either
"dns_query_reply" or "dns_rejected" events (dependent on value of
RCODE) as qclass and qtype parameters. This is not correct, because
such fields don't actually exist in the DNS message format when
QDCOUNT is 0. As a result, these events are no longer raised when
there's an empty question section. Scripts that depends on checking
for an empty question section can do that in the "dns_message" event.
- Add a new "dns_unknown_reply" event, for when Bro does not know how
to fully parse a particular resource record type. This helps fix a
problem in the default DNS scripts where the logic to complete
request-reply pair matching doesn't work because it's waiting on more
RR events to complete the reply. i.e. it expects ANCOUNT number of
dns_*_reply events and will wait until it gets that many before
completing a request-reply pair and logging it to dns.log. This could
cause bogus replies to match a previous request if they happen to
share a DNS transaction ID.
