fix: コード最適化、テスト追加

[crow-misia]

Summary by CodeRabbit

• 新機能

  • 暗号化・復号処理の入力検証が強化され、想定外の短いデータや不正な設定でもより早く失敗するようになりました。

• バグ修正

  • 一部の境界条件で発生していた切り詰め判定やパディング処理を改善し、復号時の安定性を向上しました。
  • ヘッダー読み取り時の範囲外参照を防ぎ、短い入力でも安全に処理できるようになりました。
  • 鍵・オプション関連の不正入力に対するエラー処理を強化しました。

[crow-misia]

@coderabbitai full review

[coderabbitai]

✅ Action performed

Full review finished.

[coderabbitai]

Warning

Review limit reached

@crow-misia, you've reached your PR review limit, so we couldn't start this review.

Next review available in: 52 minutes

Enable usage-based reviews in Billing to review now. Otherwise, wait until the next included review is available.
You're only billed for reviews past your plan's rate limits ($0.25/file).

How can I continue?

After more reviews become available, a review can be triggered using the @coderabbitai review command as a PR comment. Alternatively, push new commits to this PR.

To avoid repeated limits, reduce automatic review volume by pausing incremental auto-reviews earlier, using label-based review opt-in, excluding WIP or generated PR titles, or requesting reviews manually when the PR is ready. If your team needs uninterrupted high-volume reviews, an organization admin can enable usage-based reviews.

How do review limits work?

CodeRabbit enforces per-developer PR review limits for each organization. Most developers receive the normal plan review availability.

For paid Pro and Pro+ PR reviews, CodeRabbit uses adaptive limits for sustained high-volume activity. When a developer's recent PR review activity reaches the 95th percentile or higher among CodeRabbit users, additional reviews become available more gradually as earlier reviews age out of the rolling window.

Please refer docs for additional details.

Review details

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: e3ce79ff-8d5f-4546-a6ef-99671a2919ad

📥 Commits

Reviewing files that changed from the base of the PR and between 1175849 and 151ae5c.

📒 Files selected for processing (11)

• contentencoding.go
• contentencoding_test.go
• decrypt.go
• decrypt_test.go
• encrypt.go
• encrypt_test.go
• keys.go
• keys_test.go
• options_test.go
• utils.go
• utils_test.go

📝 Walkthrough

Walkthrough

ContentEncodingのパディング計算・境界判定・最終ブロック判定ロジックを修正し、decrypt/encryptでバッファ再利用とバウンドチェックを追加。keys.go/utils.goの文字列連結・nonce生成をbytes.Join及びインラインXORに置換。多数のエラー系・境界系テストを追加。

Changes

コアロジック修正とテスト

Layer / File(s)	Summary
ContentEncodingのパディング・境界・最終ブロック判定 contentencoding.go, contentencoding_test.go	calculateRecordPadSize、calculateCipherBlockEnd、unpad、isLastBlockの計算順序・境界条件を変更し、対応するエラー・境界系テストを追加。
decryptのヘッダ検証とバッファ再利用 decrypt.go, decrypt_test.go	readHeaderにcontentLen/idLenの境界チェックを追加してcontentLen不足時は早期リターン、decryptRecordのgcm.Open出力先をcontent[:0]に変更、AESGCM切り詰めテストを追加。
encryptのヘッダ書き込みとバッファ再利用 encrypt.go, encrypt_test.go	writeHeaderのrecordSize書き込みをbinary.BigEndian.PutUint32へ、encryptRecordのgcm.Seal出力先をplaintextWithPadding[:0]へ変更、parseOptionsのエラー処理を整理し、異常系テストを追加。
keys/utilsの連結処理とnonce生成の置換 keys.go, keys_test.go, utils.go, utils_test.go, options_test.go	buildInfoとjoinをbytes.Joinへ、generateNonceをインラインXORループへ置換しuint32ToBytes/xor12を削除、鍵・オプション・デバッグ関連のエラー系テストを追加。

Estimated code review effort: 3 (Moderate) | ~25 minutes

Sequence Diagram(s)

sequenceDiagram
  participant Caller
  participant readHeader
  participant decryptRecord
  participant unpad

  Caller->>readHeader: ヘッダ解析(content)
  readHeader-->>Caller: contentLen不足時は元のcontentを返却
  Caller->>decryptRecord: gcm.Open(content[:0], ...)
  decryptRecord->>unpad: パディング除去
  unpad-->>decryptRecord: plaintext[:j]またはエラー
  decryptRecord-->>Caller: plaintextまたはErrTruncated

Loading

Poem

パディングの端っこ、ぴょんと跳ねて
j番目まで正しく数えたよ 🐰
content[:0]でバッファ節約
bytes.Joinでうさぎも楽々連結
ヘッダも短すぎたら安全に止まるね
テストいっぱい、にんじんいっぱい 🥕

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	コードの最適化とテスト追加という変更内容を概ね反映しており、主な差分と一致しています。
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/misc

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

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

[coderabbitai]

🧹 Nitpick comments (1)

options_test.go (1)

64-70: 📐 Maintainability & Code Quality | 🔵 Trivial | 💤 Low value

テスト名の検討。

TestOptions_InitializeErrorはparseOptionsのエラー処理をテストしていますが、関数名はinitializeのエラーを示唆しています。コメントでも言及されている通り、TestOptions_ParseOptions_Errorなどより実態に近い名前にするとよいです。

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@options_test.go` around lines 64 - 70, Rename the test function
TestOptions_InitializeError to match what it actually verifies: parseOptions
error handling rather than initialize failure. Update the test name in
options_test.go to something like TestOptions_ParseOptions_Error so it clearly
reflects the behavior under test and aligns with the parseOptions call inside
the test body.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@options_test.go`:
- Around line 64-70: Rename the test function TestOptions_InitializeError to
match what it actually verifies: parseOptions error handling rather than
initialize failure. Update the test name in options_test.go to something like
TestOptions_ParseOptions_Error so it clearly reflects the behavior under test
and aligns with the parseOptions call inside the test body.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: f1e77735-9ad1-4dcf-bfa9-6c1988452d0b

📥 Commits

Reviewing files that changed from the base of the PR and between 98b9c79 and 1175849.

📒 Files selected for processing (11)

• contentencoding.go
• contentencoding_test.go
• decrypt.go
• decrypt_test.go
• encrypt.go
• encrypt_test.go
• keys.go
• keys_test.go
• options_test.go
• utils.go
• utils_test.go