Implemented checker as described in internal-docs/notes4coding/checker_design.md

README.md

@@ -0,0 +1,69 @@
+# Checker
+
+Modbus/TCP traffic checker that validates generated PCAP/PCAPNG traces against
+Modbus rules, request/response pairing, and optional expected fields supplied
+via JSONL sidecar metadata.
+
+## What It Does
+
+- Parses Ethernet/RAW PCAP packets, extracts TCP payloads
+- Validates MBAP header and basic Modbus/TCP invariants
+- Parses PDU fields using descriptor JSON (request/response)
+- Tracks outstanding requests and flags unmatched responses
+- Compares observed values with optional expected fields in JSONL
+- Emits a JSON report with findings and a summary
+
+## Build
+
+```bash
+cargo build
+```
+
+## Run
+
+```bash
+cargo run -- \
+  --pcap trace.pcapng \
+  --meta trace.meta.jsonl \
+  --config modbus.json \
+  --report report.json \
+  --port 502 \
+  --mode mvp
+```
+
+Sample CLI with the example files:
+
+```bash
+cargo run -- \
+  --pcap trace.pcapng \
+  --meta docs/examples/trace.meta.jsonl \
+  --config docs/examples/modbus.json \
+  --report report.json
+```
+
+## CLI Options
+
+- `--pcap <path>`: PCAP or PCAPNG input file
+- `--meta <path>`: JSONL sidecar metadata (1 line per packet)
+- `--config <path>`: Modbus descriptor JSON
+- `--report <path>`: Report JSON output (default: `report.json`)
+- `--port <u16>`: Modbus/TCP port (default: `502`)
+- `--mode mvp|strict`: Validation mode (default: `mvp`)
+- `--fail-fast`: Stop on first fatal error
+
+## Files and Formats
+
+See `docs/api.md` for the full schema of:
+- `trace.meta.jsonl` lines
+- Modbus descriptor JSON
+- `report.json` output
+
+Example files live in `docs/examples/`:
+- `docs/examples/trace.meta.jsonl`
+- `docs/examples/modbus.json`
+- `docs/examples/report.json`
+
+## Notes
+
+- This checker assumes one Modbus ADU per TCP payload.
+- TCP reassembly and checksum validation are not implemented.