auth 4.9: backport "iputils: do not index past the address for byte-aligned prefixes"

[miodvallat]

Short description

Backport of #17835.

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

[coveralls]

Coverage Report for CI Build 30795230217

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 (+0.02%) to 63.128%

Details

• Coverage increased (+0.02%) from the base build.
• Patch coverage: 1 uncovered change across 1 file (24 of 25 lines covered, 96.0%).
• 16 coverage regressions across 5 files.

Uncovered Changes

File	Changed	Covered	%
pdns/iputils.hh	5	4	80.0%
Total (3 files)	25	24	96.0%

Coverage Regressions

16 previously-covered lines in 5 files lost coverage.

File	Lines Losing Coverage	Coverage
modules/godbcbackend/sodbc.cc	6	70.08%
pdns/signingpipe.cc	5	85.25%
pdns/rcpgenerator.cc	2	88.48%
pdns/ws-auth.cc	2	81.45%
pdns/iputils.hh	1	67.72%

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Coverage Stats

Relevant Lines:	59981
Covered Lines:	42142
Line Coverage:	70.26%
Relevant Branches:	27524
Covered Branches:	13098
Branch Coverage:	47.59%
Branches in Coverage %:	Yes
Coverage Strength:	6482576.77 hits per line

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💛 - Coveralls