"""Multicast DNS Service Discovery for Python, v0.14-wmcbrine

)

Copyright 2003 Paul Scott-Murphy, 2014 William McBrine

This module provides a framework for the use of DNS Service Discovery

using IP multicast.

This library is free software; you can redistribute it and/or

modify it under the terms of the GNU Lesser General Public

License as published by the Free Software Foundation; either

version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public

License along with this library; if not, write to the Free Software

Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301

USA

"""

from __future__ import annotations

import logging

import sys

from typing import Any

log = logging.getLogger(__name__.split(".", maxsplit=1)[0])

log.addHandler(logging.NullHandler())

def set_logger_level_if_unset() -> None:

if log.level == logging.NOTSET:

log.setLevel(logging.WARN)

set_logger_level_if_unset()

_MAX_SEEN_LOGS = 512

_seen_logs: dict[str, None] = {}

def _evict_oldest(seen: dict[str, None]) -> bool:

"""Pop the oldest entry from ``seen``; return False if it raced.

Individual dict ops (``pop`` with a default, ``next``) are atomic

on the free-threaded build, but the compound ``iter`` → ``next``

used to pick the FIFO victim can raise ``RuntimeError`` if

another thread mutates the dict between the two ops. The caller

breaks its drain loop on False so concurrent mutation can't make

it spin.

"""

try:

seen.pop(next(iter(seen)), None)

except (RuntimeError, StopIteration):

return False

return True

def _mark_seen(seen: dict[str, None], key: str) -> bool:

"""Record ``key`` in ``seen`` and return True if it was newly added.

Bounds the dict so callers passing attacker-influenced keys (peer

addresses, packet offsets) cannot grow it without bound. Evicts

the oldest entries on overflow (dict preserves insertion order on

Python 3.7+), so ``_MAX_SEEN_LOGS`` is a recency window.

The dict is shared across all ``Zeroconf`` instances in the

process; on the free-threaded build (3.14t) and under multi-

instance sync use, callers can race the ``len < cap`` check and

both insert, leaving the dict transiently above the cap. The

drain loop runs on every call (steady-state-at-cap hits are a

single ``len`` + compare past the membership check because the

helper short-circuits) so a contention burst is corrected by the

next caller regardless of whether it's a hit or a miss.

"""

inserting = key not in seen

# Hit (``inserting`` is False): drain only if drifted above cap.

# Miss (``inserting`` is True): drain to ``cap - 1`` to make room

# for the new key. Bool subtracts as 0/1 to pick the right limit.

while len(seen) > _MAX_SEEN_LOGS - inserting and _evict_oldest(seen):

pass

if inserting:

seen[key] = None

return inserting

class QuietLogger:

@classmethod

def log_exception_warning(cls, *logger_data: Any) -> None:

first_time = _mark_seen(_seen_logs, str(sys.exc_info()[1]))

logger = log.warning if first_time else log.debug

logger(*(logger_data or ["Exception occurred"]), exc_info=True)

@classmethod

def log_exception_debug(cls, *logger_data: Any) -> None:

first_time = _mark_seen(_seen_logs, str(sys.exc_info()[1]))

log.debug(*(logger_data or ["Exception occurred"]), exc_info=first_time)

@classmethod

def log_warning_once(cls, *args: Any) -> None:

logger = log.warning if _mark_seen(_seen_logs, args[0]) else log.debug

logger(*args)

@classmethod

def log_exception_once(cls, exc: Exception, *args: Any) -> None:

logger = log.warning if _mark_seen(_seen_logs, args[0]) else log.debug

logger(*args, exc_info=exc)