predict docs: better explain how it works

See merge request !1145

release 5.3.0

See merge request !1138

lib/selection: add simple detection of IPv6 being broken

See merge request !1143

Details are described in code comments.

lib/selection: halve the default timeout (for iteration)

See merge request !1141

lib/selection{,_iter}.c: allow switching back to UDP

See merge request !1140

Switching to TCP instead of querying very slow servers over UDP has had
unwanted side effect – we would sometimes get stuck with a server
permanently switched to TCP. And if the server happens to not reply over
TCP we were in trouble.

Therefore after we TCP connect fails or timeouts we provide one last
chance for the server over UDP. This will not prevent the next request
to try TCP again on this server again, but we don't care because
DNS MUST ******* work over TCP.

daemon/udp_queue: drop the error logging

See merge request !1139

We should do this for all transports and probably just in verbose mode.
We were printing lots of these on Turris OS (for one user at least):
https://forum.turris.cz/t/5-1-8-kresd-throwing-many-errors-in-var-log-messages/14775

EACCESS in particular apparently may happen (on Linux) when the network
is "unavailable", EPERM because of firewall/netfilter:
https://stackoverflow.com/a/23869102

modules/{http,watchdog}: fix stability problems

See merge request knot/knot-resolver!1136

Vladimír Čunát authored 4 years ago and Tomas Krizek committed 4 years ago

As first noted in commit d1a229ae, in some cases we do call chains that
are not supported for JIT in LuaJIT.

I'm not 100% sure all of these are needed to comply, but the functions
here are really small and probably not to be that heavily used,
so I don't think it will be costly to interpret them
(and avoiding crashes is more important).

In my tests this fixed occasional crashes when using http://*/trace/*

adapt to knot 3.1 changes

See merge request knot/knot-resolver!1134

ci: Sonarcloud fixup

See merge request knot/knot-resolver!1135

ci: sonarcloud improvements

See merge request knot/knot-resolver!1121

Vladimír Čunát authored 4 years ago and Tomas Krizek committed 4 years ago

and break the overlong line

policy.ANSWER: minor fixes, mainly around NODATA answers

See merge request knot/knot-resolver!1129

Reported on:
https://gitter.im/CZ-NIC/knot-resolver?at=60213c720eed905f189da4d7

- return SOA in NODATA answers and allow customizing it
- only call ensure_answer() if really generating an answer
  (otherwise we might e.g. deplete XDP buffers, in extreme cases)

Arch Linux now ships knot-resolver in their repositories, delete
reference to AUR.

Thanks to daurnimator who adopted the package!

minor module docs fixes

See merge request knot/knot-resolver!1131

Reported on:
https://gitter.im/CZ-NIC/knot-resolver?at=601ae90e9fa6765ef8f6b408

(and regularize indentation)  Reported on:
https://gitter.im/CZ-NIC/knot-resolver?at=601b36f6aa6a6f319d0235f5

In particular, non-support of EDNS is implied iff FORMERR without OPT
comes.  If OPT is there, one possibility is that there was something
wrong in the OPT that *we* sent, but it seems much more likely that
this particular server is just bad and we want to try another one.
https://tools.ietf.org/html/rfc6891#section-7
In particular, we would be in trouble if we dropped OPT in a zone
that is covered by DNSSEC.

It's now consistent with KNOT_RCODE_FORMERR and the official name
https://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-6

It wasn't really used for a long time and became completely obsolete after
!1030.