Files
DECNET/decnet/templates/syslog_bridge.py
anti aebb9f81c6 feat(templates): encode_secret() helper in canonical syslog_bridge
Phase 1/3 of DEBT-039. Adds the Python emitter-side counterpart to
auth-helper.c's sd_escape + base64 logic so service templates can
emit the universal credential SD shape with a single spread:

    _log("auth_attempt", principal=user, **encode_secret(password))

secret_printable mirrors the C helper's [0x20, 0x7f) → '?' contract;
secret_b64 preserves the ORIGINAL utf-8 bytes losslessly so non-ASCII
or control-byte payloads survive as fingerprinting signal even when
the printable form sanitizes them.

The canonical syslog_bridge.py is what _sync_logging_helper()
propagates into per-template build contexts at deploy time, so any
service that imports its local syslog_bridge picks this up
automatically on next rebuild.

Phase 2 migrates the six cred-emitting service templates (FTP, POP3,
IMAP, SMTP, Redis, LDAP) onto this helper. Phase 3 deletes the
ingester's legacy adapter once nothing emits the old shape.
2026-04-25 05:37:44 -04:00

117 lines
4.1 KiB
Python

#!/usr/bin/env python3
"""
Shared RFC 5424 syslog helper used by service containers.
Services call syslog_line() to format an RFC 5424 message, then
write_syslog_file() to emit it to stdout — the container runtime
captures it, and the host-side collector streams it into the log file.
RFC 5424 structure:
<PRI>1 TIMESTAMP HOSTNAME APP-NAME PROCID MSGID [SD-ELEMENT] MSG
Facility: local0 (16). SD element ID uses PEN 55555.
"""
import base64
from datetime import datetime, timezone
from typing import Any
# ─── Constants ────────────────────────────────────────────────────────────────
_FACILITY_LOCAL0 = 16
_SD_ID = "relay@55555"
_NILVALUE = "-"
SEVERITY_EMERG = 0
SEVERITY_ALERT = 1
SEVERITY_CRIT = 2
SEVERITY_ERROR = 3
SEVERITY_WARNING = 4
SEVERITY_NOTICE = 5
SEVERITY_INFO = 6
SEVERITY_DEBUG = 7
_MAX_HOSTNAME = 255
_MAX_APPNAME = 48
_MAX_MSGID = 32
# ─── Formatter ────────────────────────────────────────────────────────────────
def _sd_escape(value: str) -> str:
"""Escape SD-PARAM-VALUE per RFC 5424 §6.3.3."""
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,
timestamp: datetime | None = None,
msg: str | None = None,
**fields: Any,
) -> str:
"""
Return a single RFC 5424-compliant syslog line (no trailing newline).
Args:
service: APP-NAME (e.g. "http", "mysql")
hostname: HOSTNAME (node name)
event_type: MSGID (e.g. "request", "login_attempt")
severity: Syslog severity integer (default: INFO=6)
timestamp: UTC datetime; defaults to now
msg: Optional free-text MSG
**fields: Encoded as structured data params
"""
pri = f"<{_FACILITY_LOCAL0 * 8 + severity}>"
ts = (timestamp or 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 encode_secret(secret: str) -> dict[str, str]:
"""Standardized credential-secret encoding for the universal SD-block shape.
Returns ``{'secret_printable': ..., 'secret_b64': ...}`` ready to spread
into a :func:`syslog_line` / ``_log`` call::
_log("auth_attempt", principal=user, **encode_secret(password))
``secret_printable`` mirrors auth-helper.c's sd_escape: bytes outside
``[0x20, 0x7f)`` collapse to ``'?'`` so the field is always parser-safe
RFC 5424 ASCII. ``secret_b64`` preserves the *original* utf-8 bytes —
NUL/0xff/control/non-utf8 sequences all survive losslessly, useful as
a fingerprinting signal even when the printable form sanitizes them.
The decnet web ingester's native-shape branch keys off ``secret_b64``
being present, so any service emitter calling this helper lands its
cred attempt directly in the :class:`Credential` table.
"""
raw = secret.encode("utf-8", errors="replace")
printable = "".join(chr(b) if 0x20 <= b < 0x7f else "?" for b in raw)
return {
"secret_printable": printable,
"secret_b64": base64.b64encode(raw).decode("ascii"),
}
def write_syslog_file(line: str) -> None:
"""Emit a syslog line to stdout for container log capture."""
print(line, flush=True)
def forward_syslog(line: str, log_target: str) -> None:
"""No-op stub. TCP forwarding is handled by rsyslog, not by service containers."""
pass