Files
DECNET/decnet/sniffer/syslog.py
anti 5a7ff285cd feat: fleet-wide MACVLAN sniffer microservice
Replace per-decky sniffer containers with a single host-side sniffer
that monitors all traffic on the MACVLAN interface. Runs as a background
task in the FastAPI lifespan alongside the collector, fully fault-isolated
so failures never crash the API.

- Add fleet_singleton flag to BaseService; sniffer marked as singleton
- Composer skips fleet_singleton services in compose generation
- Fleet builder excludes singletons from random service assignment
- Extract TLS fingerprinting engine from templates/sniffer/server.py
  into decnet/sniffer/ package (parameterized for fleet-wide use)
- Sniffer worker maps packets to deckies via IP→name state mapping
- Original templates/sniffer/server.py preserved for future use
2026-04-14 15:02:34 -04:00

70 lines
2.1 KiB
Python

"""
RFC 5424 syslog formatting and log-file writing for the fleet sniffer.
Reuses the same wire format as templates/sniffer/decnet_logging.py so the
existing collector parser and ingester can consume events without changes.
"""
import json
from datetime import datetime, timezone
from pathlib import Path
from typing import Any
from decnet.collector.worker import parse_rfc5424
# ─── Constants (must match templates/sniffer/decnet_logging.py) ──────────────
_FACILITY_LOCAL0 = 16
_SD_ID = "decnet@55555"
_NILVALUE = "-"
SEVERITY_INFO = 6
SEVERITY_WARNING = 4
_MAX_HOSTNAME = 255
_MAX_APPNAME = 48
_MAX_MSGID = 32
# ─── Formatter ───────────────────────────────────────────────────────────────
def _sd_escape(value: str) -> str:
return value.replace("\\", "\\\\").replace('"', '\\"').replace("]", "\\]")
def _sd_element(fields: dict[str, Any]) -> str:
if not fields:
return _NILVALUE
params = " ".join(f'{k}="{_sd_escape(str(v))}"' for k, v in fields.items())
return f"[{_SD_ID} {params}]"
def syslog_line(
service: str,
hostname: str,
event_type: str,
severity: int = SEVERITY_INFO,
msg: str | None = None,
**fields: Any,
) -> str:
pri = f"<{_FACILITY_LOCAL0 * 8 + severity}>"
ts = datetime.now(timezone.utc).isoformat()
host = (hostname or _NILVALUE)[:_MAX_HOSTNAME]
appname = (service or _NILVALUE)[:_MAX_APPNAME]
msgid = (event_type or _NILVALUE)[:_MAX_MSGID]
sd = _sd_element(fields)
message = f" {msg}" if msg else ""
return f"{pri}1 {ts} {host} {appname} {_NILVALUE} {msgid} {sd}{message}"
def write_event(line: str, log_path: Path, json_path: Path) -> None:
"""Append a syslog line to the raw log and its parsed JSON to the json log."""
with open(log_path, "a", encoding="utf-8") as lf:
lf.write(line + "\n")
lf.flush()
parsed = parse_rfc5424(line)
if parsed:
with open(json_path, "a", encoding="utf-8") as jf:
jf.write(json.dumps(parsed) + "\n")
jf.flush()