malmert
a282b89d45
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47 lines
1.3 KiB
Python
47 lines
1.3 KiB
Python
"""Helpers for the shared skb mark layout used for packet correlation and verdict hints."""
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from __future__ import annotations
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from typing import Optional
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PACKET_ID_MASK = 0x0FFFFFFF
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VERDICT_MASK = 0xF0000000
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VERDICT_FLAG_DROP = 0x10000000
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VERDICT_FLAG_REJECT = 0x20000000
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def normalize_skb_mark(value: object) -> Optional[int]:
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"""Return a positive integer skb mark or `None` when the value is empty."""
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if value in (None, "", 0, "0"):
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return None
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try:
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mark = int(value)
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except (TypeError, ValueError):
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return None
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if mark < 0:
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mark &= 0xFFFFFFFF
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return mark or None
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def packet_id_from_mark(value: object) -> Optional[str]:
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"""Extract the packet correlation identifier from the shared skb mark layout."""
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mark = normalize_skb_mark(value)
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if mark is None:
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return None
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packet_id = mark & PACKET_ID_MASK
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return str(packet_id) if packet_id else None
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def verdict_from_mark(value: object) -> Optional[str]:
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"""Return a verdict hint encoded into the upper mark bits, if any."""
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mark = normalize_skb_mark(value)
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if mark is None:
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return None
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verdict_bits = mark & VERDICT_MASK
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if verdict_bits & VERDICT_FLAG_REJECT:
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return "reject"
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if verdict_bits & VERDICT_FLAG_DROP:
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return "drop"
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return None
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