fix(whois): check conn.Close return in tcp43RawDial (CI red on main)

[anushkavirgaonkar]

Summary

CI has been failing on main since the Consolidate WHOIS commit (4f7fead). The Lint job fails with a single errcheck issue; every other job in the run is green.

pkg/whois/tcp43.go:139:18: Error return value of `conn.Close` is not checked (errcheck)
	defer conn.Close()
	                ^
1 issues:
* errcheck: 1

Failing run: https://github.com/praetorian-inc/pius/actions/runs/31187027446

One line, in tcp43RawDial:

-	defer conn.Close()
+	defer func() { _ = conn.Close() }()

Why this only shows up in CI

CI pins golangci-lint v2.12.2. v2 dropped the legacy default exclusions that v1 shipped, one of which (EXC0001) excluded .*Close. Anyone still on a v1 linter locally will see this line pass, which is likely how it reached main. Re-running v1 with exclude-use-default=false reproduces the CI error character-for-character, including the 139:18 position, and reports clean after the fix.

conn.Close() on a read-only WHOIS socket has no error worth acting on, so the return is discarded explicitly rather than logged. This matches the idiom already in the repo (pkg/cache/cache.go:89,100,108, pkg/plugins/cidrs/rpsl.go:107) and the _ = conn.SetDeadline(deadline) line six lines below it in the same function.

JIRA or Linear

None. This is an unblock for red main, not tracked work. Happy to file one if the team wants a record.

Verification

• go build ./... clean
• go vet ./pkg/whois/... clean
• go test ./pkg/whois/... -> ok github.com/praetorian-inc/pius/pkg/whois
• errcheck red/green reproduced locally as described above

No test added: the deferred call runs identically before and after, only the discarded return is now explicit, so no test could distinguish the two. CI's own Lint job is the real check.

🤖 Generated with Claude Code

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 45d94954-ba53-47cf-81f8-cb2e6f13ca57

📥 Commits

Reviewing files that changed from the base of the PR and between 4f7fead and e84971f.

📒 Files selected for processing (1)

• pkg/whois/tcp43.go

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Walkthrough

The TCP WHOIS connection cleanup now uses a deferred function to call conn.Close() and discard its error. No exported declarations changed.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch anushkavirgaonkar/fix-errcheck-tcp43-conn-close

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_{Comment @coderabbitai help to get the list of available commands.}

[github-actions]

Claude Review

Critical issues

None.

Security

No security concerns flagged.

Test coverage

No test needed — the deferred call behaves identically before and after; only the discarded return is now explicit. Matches the existing _ = conn.SetDeadline(...) idiom in the same function (tcp43.go:145), and CI Lint (golangci-lint v2.12.2, which drops the legacy EXC0001 .*Close exclusion) is the real check.

No critical issues — LGTM pending human review.

[github-actions]

Gemini Review

No critical issues — LGTM pending human review.

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Reviewed by Gemini (gemini-3.1-pro-preview)

[github-actions]

Codex Review

No critical issues — LGTM pending human review.

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Reviewed by Codex (gpt-5.5)