mirror of
https://github.com/firestar5683/StarPilot.git
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Danny
96 lines
3.4 KiB
Python
96 lines
3.4 KiB
Python
"""A pure python implementation of multicast DNS service discovery.
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Licensed under LGPL-2.1-or-later; see COPYING for details. This file is
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part of a continuously modified work; modification dates are recorded
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in the project's git history.
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"""
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from __future__ import annotations
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import logging
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import sys
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from typing import Any
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log = logging.getLogger(__name__.split(".", maxsplit=1)[0])
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log.addHandler(logging.NullHandler())
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def set_logger_level_if_unset() -> None:
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if log.level == logging.NOTSET:
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log.setLevel(logging.WARN)
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set_logger_level_if_unset()
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_MAX_SEEN_LOGS = 512
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_seen_logs: dict[str, None] = {}
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def _evict_oldest(seen: dict[str, None]) -> bool:
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"""Pop the oldest entry from ``seen``; return False if it raced.
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Individual dict ops (``pop`` with a default, ``next``) are atomic
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on the free-threaded build, but the compound ``iter`` → ``next``
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used to pick the FIFO victim can raise ``RuntimeError`` if
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another thread mutates the dict between the two ops. The caller
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breaks its drain loop on False so concurrent mutation can't make
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it spin.
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"""
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try:
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seen.pop(next(iter(seen)), None)
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except (RuntimeError, StopIteration):
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return False
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return True
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def _mark_seen(seen: dict[str, None], key: str) -> bool:
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"""Record ``key`` in ``seen`` and return True if it was newly added.
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Bounds the dict so callers passing attacker-influenced keys (peer
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addresses, packet offsets) cannot grow it without bound. Evicts
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the oldest entries on overflow (dict preserves insertion order on
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Python 3.7+), so ``_MAX_SEEN_LOGS`` is a recency window.
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The dict is shared across all ``Zeroconf`` instances in the
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process; on the free-threaded build (3.14t) and under multi-
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instance sync use, callers can race the ``len < cap`` check and
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both insert, leaving the dict transiently above the cap. The
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drain loop runs on every call (steady-state-at-cap hits are a
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single ``len`` + compare past the membership check because the
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helper short-circuits) so a contention burst is corrected by the
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next caller regardless of whether it's a hit or a miss.
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"""
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inserting = key not in seen
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# Hit (``inserting`` is False): drain only if drifted above cap.
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# Miss (``inserting`` is True): drain to ``cap - 1`` to make room
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# for the new key. Bool subtracts as 0/1 to pick the right limit.
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while len(seen) > _MAX_SEEN_LOGS - inserting and _evict_oldest(seen):
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pass
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if inserting:
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seen[key] = None
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return inserting
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class QuietLogger:
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@classmethod
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def log_exception_debug(cls, *logger_data: Any) -> None:
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first_time = _mark_seen(_seen_logs, str(sys.exc_info()[1]))
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log.debug(*(logger_data or ["Exception occurred"]), exc_info=first_time)
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@classmethod
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def log_exception_once(cls, exc: Exception, *args: Any) -> None:
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logger = log.warning if _mark_seen(_seen_logs, args[0]) else log.debug
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logger(*args, exc_info=exc)
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@classmethod
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def log_exception_warning(cls, *logger_data: Any) -> None:
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first_time = _mark_seen(_seen_logs, str(sys.exc_info()[1]))
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logger = log.warning if first_time else log.debug
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logger(*(logger_data or ["Exception occurred"]), exc_info=True)
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@classmethod
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def log_warning_once(cls, *args: Any) -> None:
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logger = log.warning if _mark_seen(_seen_logs, args[0]) else log.debug
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logger(*args)
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