Every photo from a phone camera ships with an EXIF block that leaks:
GPS coordinates, camera model + serial, original timestamp, software
name, author/copyright fields, sometimes an embedded thumbnail that
survives cropping. For a social feed positioned as privacy-friendly
we can't trust the client alone to scrub — a compromised build,
a future plugin, or a hostile fork would simply skip the step and
leak authorship data.
So: server-side scrub is mandatory for every /feed/publish upload.
New package: media
media/scrub.go
- Scrubber type with Scrub(ctx, bytes, claimedMIME) → (clean, actualMIME)
- ScrubImage handles JPEG/PNG/GIF/WebP in-process: decodes, optionally
downscales to 1080px max-dim, re-encodes as JPEG Q=75. Stdlib
jpeg.Encode emits ZERO metadata → scrub is complete by construction.
- Sidecar client (HTTP): posts video/audio bytes to an external
FFmpeg worker at DCHAIN_MEDIA_SIDECAR_URL
- Magic-byte MIME detection: rejects uploads where declared MIME
doesn't match actual bytes (prevents a PDF dressed as image/jpeg
from bypassing the scrubber)
- ErrSidecarUnavailable: explicit error when video arrives but no
sidecar is wired; operator opts in to fallback via
--allow-unscrubbed-video (default: reject)
media/scrub_test.go
- Crafted EXIF segment with "SECRETGPS-…Canon-EOS-R5" canary —
verifies the string is gone after ScrubImage
- Downscale test (2000×1000 → 1080×540, aspect preserved)
- MIME-mismatch rejection
- Magic-byte detector sanity table
FFmpeg sidecar — new docker/media-sidecar/
Tiny Go HTTP service (~180 LOC, no non-stdlib deps) that shells out
to ffmpeg with -map_metadata -1 + -map 0:v -map 0:a? to guarantee
only video + audio streams survive (no subtitles, attached pictures,
or data channels that could carry hidden info).
Re-encode profile:
video → H.264 CRF 28 preset=fast, Opus 64k, MP4 faststart
audio → Opus 64k, Ogg container
Dockerfile: two-stage build (Go → alpine+ffmpeg), ~90 MB image, non-
root user, /healthz endpoint for compose probes.
Node reaches it via DCHAIN_MEDIA_SIDECAR_URL. Without it, video uploads
are rejected with 503 unless operator sets DCHAIN_ALLOW_UNSCRUBBED_VIDEO.
/feed/publish wiring
- cfg.Scrubber is a required dependency
- Before storing post body we call scrubber.Scrub(); attachment bytes
+ MIME are replaced with the cleaned version
- content_hash is computed over the SCRUBBED bytes — so the on-chain
CREATE_POST tx references exactly what readers will fetch
- EstimatedFeeUT uses the scrubbed size, so author's fee reflects
actual on-disk cost
- Content-type mismatches → 400; sidecar unavailable for video → 503
Flags / env vars
--feed-db / DCHAIN_FEED_DB (existing)
--feed-ttl-days / DCHAIN_FEED_TTL_DAYS (existing)
--media-sidecar-url / DCHAIN_MEDIA_SIDECAR_URL (NEW)
--allow-unscrubbed-video / DCHAIN_ALLOW_UNSCRUBBED_VIDEO (NEW; default false)
Client responsibilities (for reference — client work lands in Phase C)
Even with server-side scrub, the client should still compress aggressively
BEFORE upload, because:
- upload time is ~N× larger for unscrubbed media (mobile networks)
- the server's 256 KiB MaxPostSize is a HARD cap — oversized uploads
are rejected, not silently truncated
- the on-chain fee is size-based, so users pay for every byte the
client didn't bother to shrink
Recommended client pipeline:
images → expo-image-manipulator: resize max-dim 1080px, WebP or
JPEG quality 50-60
videos → react-native-compressor: H.264 CRF 28, 720p max, 64k audio
audio → expo-audio's default Opus 32k (already compressed)
Documented in docs/media-sidecar.md (added later with Phase C PR).
Tests
- go test ./... green across 6 packages (blockchain consensus identity
media relay vm)
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
DChain
Блокчейн-стек для децентрализованного мессенджера:
- PBFT консенсус с multi-sig validator governance и equivocation slashing
- Native Go контракты рядом с WASM (wazero) — нулевая задержка для
системных сервисов типа
username_registry - WebSocket push API — клиент не опрашивает, все события прилетают на соединение
- E2E-шифрованный relay mailbox на libp2p gossipsub с TTL live-detection
- Система обновлений: build-time версия →
/api/well-known-version, peer-version gossip,/api/update-checkпротив Gitea releases,update.shс semver guard - Prometheus
/metrics, Caddy auto-HTTPS, observer mode, load-test
Содержание
Быстрый старт
Одна нода в Docker, HTTP API на localhost:8080, Explorer UI и Swagger
открыты:
# 1. Собираем prod-образ
docker build -t dchain-node-slim -f deploy/prod/Dockerfile.slim .
# 2. Ключ ноды (один раз)
mkdir -p keys
docker run --rm --entrypoint /usr/local/bin/client \
-v "$PWD/keys:/out" dchain-node-slim \
keygen --out /out/node.json
# 3. Запуск (genesis-валидатор)
docker run -d --name dchain --restart unless-stopped \
-p 4001:4001 -p 8080:8080 \
-v dchain_data:/data \
-v "$PWD/keys:/keys:ro" \
-e DCHAIN_GENESIS=true \
-e DCHAIN_ANNOUNCE=/ip4/127.0.0.1/tcp/4001 \
dchain-node-slim \
--db=/data/chain --mailbox-db=/data/mailbox --key=/keys/node.json \
--relay-key=/data/relay.json --listen=/ip4/0.0.0.0/tcp/4001 --stats-addr=:8080
# 4. Проверка
open http://localhost:8080/ # Explorer
open http://localhost:8080/swagger # Swagger UI
curl -s http://localhost:8080/api/well-known-version | jq .
3-node dev-кластер (для тестов PBFT кворума, slashing, federation): docker compose up --build -d — см. docs/quickstart.md.
Продакшен деплой
Два варианта, по масштабу.
🔸 Single-node (deploy/single/)
Рекомендуется для личного/первого узла. Один узел + Caddy TLS +
опциональный Prometheus. Полный runbook с 6 сценариями (публичная с UI,
headless, полностью приватная, genesis, joiner, auto-update) — в
deploy/single/README.md.
Модели доступа
| Режим | DCHAIN_API_TOKEN |
DCHAIN_API_PRIVATE |
Поведение |
|---|---|---|---|
| Public (default) | не задан | — | Все могут читать и писать |
| Token writes | задан | false |
Читать — любой; submit tx — только с токеном |
| Fully private | задан | true |
Всё требует Authorization: Bearer <token> |
UI / Swagger — включать или нет?
| Нужно | DCHAIN_DISABLE_UI |
DCHAIN_DISABLE_SWAGGER |
Открыто |
|---|---|---|---|
| Публичная с эксплорером + docs | не задано | не задано | / Explorer, /swagger, /api/*, /metrics |
| Headless API-нода с OpenAPI | true |
не задано | /swagger, /api/*, /metrics |
| Личная hardened | true |
true |
/api/* + /metrics |
Флаги читаются и из CLI (--disable-ui, --disable-swagger), и из env.
/api/* JSON-поверхность регистрируется всегда — отключить её можно
только на уровне Caddy / firewall.
Auto-update
# node.env — когда проект в Gitea
DCHAIN_UPDATE_SOURCE_URL=https://gitea.example.com/api/v1/repos/OWNER/REPO/releases/latest
UPDATE_ALLOW_MAJOR=false
# Hourly systemd timer с 15-мин jitter
sudo cp deploy/single/systemd/dchain-update.{service,timer} /etc/systemd/system/
sudo systemctl daemon-reload
sudo systemctl enable --now dchain-update.timer
Подробно: docs/update-system.md + deploy/UPDATE_STRATEGY.md.
🔹 Multi-validator (deploy/prod/)
3 validator'а в PBFT-кворуме, Caddy с ip_hash для WS-стикинесса и
least-conn для REST. Для федераций / консорциумов — см.
deploy/prod/README.md и
docs/node/multi-server.md.
Архитектура
┌────────────┐ libp2p ┌────────────┐ libp2p ┌────────────┐
│ node-A │◄─────pubsub──►│ node-B │◄─────pubsub──►│ node-C │
│ validator │ │ validator │ │ validator │
│ + relay │ │ + relay │ │ + relay │
└─────┬──────┘ └─────┬──────┘ └─────┬──────┘
│ │ │
│ HTTPS / wss (via Caddy) │ │
▼ ▼ ▼
mobile / web / CLI clients (ip_hash для WS, least-conn для REST)
Четыре слоя: network → chain → transport → app. Детали — в
docs/architecture.md.
Основные пакеты:
| Путь | Роль |
|---|---|
blockchain/ |
Блочная машина, applyTx, native-контракты, schema-migrations |
consensus/ |
PBFT (Pre-prepare → Prepare → Commit), мемпул, equivocation |
p2p/ |
libp2p host, gossipsub, sync протокол, peer-version gossip |
node/ |
HTTP + WS API, SSE, metrics, access control |
node/version/ |
Build-time version metadata (ldflags-инжектимый) |
vm/ |
wazero runtime для WASM-контрактов + gas model |
relay/ |
E2E mailbox с NaCl-envelopes |
identity/ |
Ed25519 + X25519 keypair, tx signing |
economy/ |
Fee model, rewards |
wallet/ |
Optional payout wallet (отдельный ключ) |
REST / WebSocket API
Обзор (полный reference — docs/api/README.md):
Chain + stats
| Endpoint | Описание |
|---|---|
GET /api/netstats |
height, total_txs, supply, validator_count |
GET /api/network-info |
chain_id, genesis, peers, validators, contracts |
GET /api/blocks?limit=N / /api/block/{index} |
Блоки |
GET /api/tx/{id} / /api/txs/recent?limit=N |
Транзакции |
GET /api/address/{pub_or_addr} |
Баланс + история |
GET /api/validators |
Validator set |
GET /api/peers |
Connected peers + их версии |
POST /api/tx |
Submit signed tx (rate-limited, size-capped) |
Discovery + update
| Endpoint | Описание |
|---|---|
GET /api/well-known-version |
{node_version, build{}, protocol_version, features[], chain_id} |
GET /api/well-known-contracts |
{name → contract_id} map |
GET /api/update-check |
Diff с Gitea release (см. docs/update-system.md) |
Real-time
GET /api/ws— WebSocket (recommended). Ops:auth,subscribe,unsubscribe,submit_tx,typing,ping. Push:block,tx,inbox,typing,submit_ack.GET /api/events— SSE legacy one-way.
Scoped WS-топики (addr:, inbox:, typing:) требуют auth через
Ed25519-nonce; публичные (blocks, tx, contract_log) — без.
Docs / UI
GET /swagger— Swagger UI (рендерится через swagger-ui-dist).GET /swagger/openapi.json— сырая OpenAPI 3.0 спека.GET /— block-explorer HTML (выключаетсяDCHAIN_DISABLE_UI=true).
CLI
client keygen --out key.json
client --version # → dchain-client vX.Y.Z (commit=... date=...)
client balance --key key.json --node URL
client transfer --key key.json --to <pub> --amount <µT> --node URL
client call-contract --key key.json --contract native:username_registry \
--method register --arg alice --amount 10000 \
--node URL
client add-validator --key key.json --target <pub> --cosigs pub:sig,pub:sig
client admit-sign --key validator.json --target <candidate-pub>
client deploy-contract --key key.json --wasm ./my.wasm --abi ./my_abi.json --node URL
# полный список — `client` без аргументов, или в docs/cli/README.md
Все флаги node — в docs/node/README.md, либо
node --help.
Мониторинг
Prometheus endpoint /metrics на каждой ноде. Ключевые метрики:
dchain_blocks_total # committed blocks count
dchain_txs_total # tx count
dchain_tx_submit_accepted_total
dchain_tx_submit_rejected_total
dchain_ws_connections # current WS sockets
dchain_peer_count_live # live libp2p peer count
dchain_max_missed_blocks # worst validator liveness gap
dchain_block_commit_seconds # histogram of AddBlock time
Grafana + Prometheus поднимаются вместе с нодой через
docker compose --profile monitor up -d (см. deploy/single/docker-compose.yml).
Тесты
# Unit + integration
go test ./... # blockchain + consensus + identity + relay + vm
go vet ./... # static checks
# End-to-end load (3-node dev cluster должен быть поднят):
docker compose up --build -d
go run ./cmd/loadtest \
--node http://localhost:8081 \
--funder testdata/node1.json \
--clients 50 --duration 60s
Документация
Полный справочник в docs/ — см. docs/README.md как
оглавление. Ключевые документы:
| Документ | О чём |
|---|---|
docs/quickstart.md |
Три пути: локально, single-node prod, федерация |
docs/architecture.md |
4 слоя, consensus, storage, gas model |
docs/update-system.md |
Versioning + update-check + semver guard |
docs/api/README.md |
REST + WebSocket reference |
docs/cli/README.md |
CLI команды и флаги |
docs/node/README.md |
Запуск ноды (native + Docker) |
docs/contracts/README.md |
Системные + WASM контракты |
docs/development/README.md |
SDK для своих контрактов |
deploy/single/README.md |
Single-node operator runbook |
deploy/prod/README.md |
Multi-validator federation |
deploy/UPDATE_STRATEGY.md |
Forward-compat design (4 слоя) |