48 lines
2.2 KiB
Python
48 lines
2.2 KiB
Python
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"""Consumer-owned bounded time adapter; explicit opt-in, no configured fallback."""
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from datetime import datetime, timezone, timedelta
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from functools import lru_cache
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from secrets_engine.errors import DecisionError
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@lru_cache(maxsize=8)
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def _clock(path):
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try:
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from railiance_clock.client import Clock, FileTrust
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return Clock(FileTrust(path))
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except (ImportError, OSError, ValueError, TypeError, KeyError) as exc:
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raise DecisionError("Railiance clock unavailable or untrusted") from exc
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def read_window(cfg):
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path = getattr(cfg, "clock_trust_file", None)
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if not path:
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return None
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try:
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return _clock(str(path)).read()
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except (OSError, ValueError) as exc:
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raise DecisionError("Railiance clock unavailable or untrusted") from exc
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def validity_bounds(now=None, window=None):
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if window is None:
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current = (now or datetime.now(timezone.utc)).astimezone(timezone.utc)
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return current, current
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if now is not None:
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raise DecisionError("choose interval evidence or explicit test time, not both")
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try:
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lower, upper = window.lower_ns, window.upper_ns
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if type(lower) is not int or type(upper) is not int or not 0 <= lower <= upper:
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raise ValueError("invalid interval")
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epoch = datetime(1970, 1, 1, tzinfo=timezone.utc)
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return epoch + timedelta(microseconds=lower // 1000), epoch + timedelta(microseconds=(upper + 999) // 1000)
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except (ValueError, TypeError, AttributeError, OverflowError) as exc:
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raise DecisionError("invalid Railiance time interval") from exc
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def recheck_binding(cfg, binding):
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if not getattr(cfg, "clock_trust_file", None):
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return
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if not binding.decision_expires_at:
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raise DecisionError("bounded-time consume requires decision validity")
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lower, upper = validity_bounds(window=read_window(cfg))
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expires = datetime.fromisoformat(binding.decision_expires_at.replace("Z", "+00:00"))
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start = datetime.fromisoformat(binding.decision_not_before.replace("Z", "+00:00")) if binding.decision_not_before else None
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if upper >= expires or (start is not None and lower < start):
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raise DecisionError("decision validity does not contain the Railiance interval")
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