WIP: configurable extension for RRSIG expiry

[Habbie]

Short description

This goes well with #17281 but can exist separately.

Checklist

I have:

• read the CONTRIBUTING.md document
• read and accepted the Developer Certificate of Origin document, including the AI Policy, and added a "Signed-off-by" to my commits
• compiled this code
• tested this code
• included documentation (including possible behaviour changes)
• documented the code
• added or modified regression test(s)
• added or modified unit test(s)
• checked that this code was merged to master

[pieterlexis]

Please add documentation.

[miodvallat]

Would it be worth limiting the values to a reasonable range of seconds? Something like [minus one week; one year] maybe.

[Habbie]

Would it be worth limiting the values to a reasonable range of seconds? Something like [minus one week; one year] maybe.

Yes: users will regret anything over minus one or two weeks.

No: it's just rope. We don't do the hanging.

That all said, generating a value before Inception is invalid anyway, so a -3 week lower bound makes sense to me.

[coveralls]

Coverage Report for CI Build 25757017830

Warning

Build has drifted: This PR's base is out of sync with its target branch, so coverage data may include unrelated changes.
Quick fix: rebase this PR. Learn more →

Coverage increased (+0.2%) to 66.388%

Details

• Coverage increased (+0.2%) from the base build.
• Patch coverage: No coverable lines changed in this PR.
• 9548 coverage regressions across 119 files.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

9548 previously-covered lines in 119 files lost coverage.

Top 10 Files by Coverage Loss	Lines Losing Coverage	Coverage
pdns/recursordist/pdns_recursor.cc	1102	28.77%
pdns/recursordist/lua-recursor4.cc	681	0.0%
pdns/recursordist/rec-tcp.cc	589	5.19%
pdns/recursordist/rec-main.cc	518	44.96%
pdns/recursordist/lwres.cc	409	17.99%
pdns/recursordist/rec_channel_rec.cc	391	15.49%
pdns/recursordist/rec-lua-conf.cc	347	2.49%
pdns/recursordist/rec-rust-lib/cxxsupport.cc	341	48.68%
pdns/recursordist/syncres.cc	339	72.57%
pdns/recursordist/rpzloader.cc	291	29.88%

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Coverage Stats

Relevant Lines:	132431
Covered Lines:	97424
Line Coverage:	73.57%
Relevant Branches:	63938
Covered Branches:	32942
Branch Coverage:	51.52%
Branches in Coverage %:	Yes
Coverage Strength:	3851132.83 hits per line

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💛 - Coveralls