- selection: utilize address_state::broken also when forwarding
- selection: drop fallbacks that don't make sense when forwarding
- iterate: copy EDE codes on DNSSEC SERVFAILs

We use "monotonic" time-stamps for the dead_since field;
that breaks on system reboots, in which case we reset the stats.
(if the server was categorized as dead)

If the server times out afterwards, we'd fail the condition
`cur_state.consecutive_timeouts == old_state.consecutive_timeouts`
so its stats would not update.  Therefore we'd get stuck forever
in a state where the unusable server has high priority (no_rtt_info).

This commit changes a bit more than was necessary to fix this,
including precision of the stats (in some cases).

Vladimír Čunát authored 3 years ago and Tomas Krizek committed 3 years ago

They probably couldn't hang open for long, as each client request
should cause some cache-searching and thus close it, and even with
queries stopping I haven't managed to find a case where it would be
left open but... it's nicer to clean up and it should be very cheap.

To (hopefully) improve readability, rename the typical macro usage of:

    if (!kr_assume(x)) y; // to
    if (kr_fails_assert(x)) y;

As a convenience, replace the assert without a return value to a more
simple version:

    (void)!kr_assume(x);  // becomes
    kr_assert(x);

I'm overall unsure here, but this does seem as improvement.

The target of STUB might commonly not have good support
for "advanced" features like TCP.

This lead to unintitialized values being possibly used down the line.

More idiomatic code seems better:
- for variable initialization we have = { 0 }
- (mm_)calloc for heap allocations
  sizeof: use variable instead of type (where suitable; not sure why)

This is done by changing the type of address field in struct choice to
union inaddr and moving some conversion around.

Small things I've noticed while reading it all.
- line breaks: I believe <90 is OK, as usually the attempts to reduce
  lengths impair readability
- avoid unnecessary casts; usually the type was visible
  on the same line anyway
- avoid `|` on booleans
- one block gets de-indented (often badly shown in diffs)
- no need for UNRECOVERABLE_ERRORS in a header (and a weird one, too)
- recoverability from failed assertions (in case they're turned off)

Štěpán Balážik authored 5 years ago and Vladimír Čunát committed 4 years ago

Design discussion: #447
Code discussion: !1030