# Log sanitization

`internal/sanitize` produces a de-identified copy of an uploaded diagnostic
file. It is the redaction counterpart of the detection-only `internal/privacy`
scan (see `privacy-scan.md`). ADL-067.

## Contract

- **Same format, same structure.** Archive entry names, modes, uid/gid, and all
  embedded timestamps (tar `ModTime`/`AccessTime`/`ChangeTime`, gzip `Name`/
  `ModTime`/`OS`, zip `Modified`/`Extra`) are preserved. Entry order is kept.
- **Length-preserving replacement.** Every filler is the exact byte length of
  the token it replaces, so tar/zip member sizes - and therefore the tar
  headers and their checksums - are byte-identical. Untouched zip entries are
  copied raw (`(*zip.Writer).Copy`).
- **Byte-identical when nothing changes.** An uncompressed `.tar`/`.sds`/`.txt`/
  `.log` with no redactable data comes out equal to the input. `.gz`/`.zip`
  cannot be byte-identical because the compression layer is always rebuilt
  (member payloads and metadata still match; only the compressed stream and the
  total size differ).
- **No marker.** Nothing is stamped into the file.
- **Idempotent.** The fillers are on the privacy allowlist (`isRedactionFiller`),
  so a re-scan finds nothing and a second `Sanitize` is a no-op.

## Entry point

```go
sanitize.Sanitize(filename string, data []byte) (*sanitize.Result, error)
sanitize.CanSanitize(filename string) bool   // .tar .sds .gz .tgz .zip .txt .log
```

`Result{ Data, Changes []Change, SkippedBinary []string, TotalReplaced }`.
Format is resolved by extension; nested archives (`.tar.gz` in a `.zip`, ...)
are rewritten recursively.

## Fillers

| Category | Example | Filler |
|----------|---------|--------|
| `domain`, `mgmt_subdomain`, `resolv`, `ad_ldap`, `nsupdate`, `collector`, `dhcp`, `cert` | `sigma.sbrf.ru` | letters/digits → `x`, punctuation kept → `xxxxx.xxxx.xx` |
| `email` | `admin@corp.acme.ru` | `xxxxx@xxxx.xxxx.xx` |
| `public_ip` | `93.184.216.34` | digits → `0`, dots kept → `00.000.000.00` (`net.ParseIP` → nil) |
| `timezone` name | `Europe/Moscow` | same-length valid neutral IANA zone from `neutralZoneByLen` (`Etc/Universal`, `Antarctica/McMurdo`, ...) |
| `timezone` offset | `SELTimeUTCOffset=180` | `000` |
| `timezone` abbr | `... MSK 2026` | `UTC` (len 3), else `x`-fill |

Timezone redaction changes the config value only; **event timestamps are never
recomputed**, so a re-analysis of the sanitized dump may read event times in the
wrong zone (the same trade-off as the KB manual cleanup).

`fru_location` spans are **not** redacted (often a serial / manufacturing code,
sometimes in a binary FRU area) - only reported by the scan.

Private IPs, `pool.ntp.org` and everything else on the privacy allowlist are
never touched. Vendor factory-template members (`*_tianyiyun`, `*.conf_bak`,
`raw_export.json`, ...) are skipped whole (`privacy.IsAllowlistedFile`).

## Not edited (`Result.SkippedBinary`)

Reported for manual handling, never modified:
- Binary members with a customer string in a printable run: `FRU.bin`
  (Asset Tag), `redis-dump.rdb`, `SDR.dat`, SOL captures with control bytes,
  `racsessioninfo` / `session_token`.
- `configuration/conf/localtime` - a real UTC tzdata blob is a different length,
  so it cannot be swapped in place.
- Truncated / mis-named nested archives (copied verbatim).
- HPE `.ahs` (proprietary container).

## Surfaces

| Where | How |
|-------|-----|
| API | `POST /api/sanitize` runs it on the retained upload bytes and returns the preview JSON (`total_replaced`, `changes[]`, `skipped_binary[]`); `GET /api/sanitize/download` streams the file (`Content-Disposition: attachment; filename="<original>"`, `application/octet-stream`). `422` for live-Redfish / snapshot sources. |
| UI | "Обезличить и скачать копию" in the Customer-data panel (shown when `privacy-scan` reports `sanitizable: true`) → preview → download. |
| CLI | `logpile -sanitize <file> [-sanitize-out <file>]` - edits in place (or writes `-sanitize-out`), restores mtime/atime via `os.Chtimes`, prints the change summary. ctime reflects the edit. |

## Limits

- Whole file is held in memory and rebuilt: `maxInputBytes` 800 MiB,
  `maxMemberBytes` 1 GiB per decompressed member.
- Fixtures and tests use `acme.ru` / `corp.acme.local` - never a real customer
  domain, same rule as the privacy scan.