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https://github.com/unshackle-dl/unshackle.git
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imSp4rky
9c9e059e2d
Cache keys are now the path relative to the service cache dir without .json, so Cacher keys like session_web/<sha1> reach the remote session. The credential filter runs on every path segment, the suffix is appended rather than substituted, and both sides cap the map at 64 keys.
44 lines
1.8 KiB
Python
44 lines
1.8 KiB
Python
"""Helpers for safely logging and handling user-provided values."""
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from __future__ import annotations
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import re
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from pathlib import PureWindowsPath
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from typing import Optional
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MAX_CACHE_KEY_DEPTH = 8
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MAX_SESSION_CACHE_KEYS = 64
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def sanitize_log(value: object) -> str:
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"""Sanitise a value for safe logging by removing newlines and control characters."""
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return str(value).replace("\n", "").replace("\r", "").replace("\x00", "")
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def safe_cache_key(key: object) -> Optional[str]:
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"""Return a relative posix path for a peer-supplied cache key, or None if it escapes its directory.
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unshackle writes each cache key as ``<key>.json`` inside a fixed directory, and a key may
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hold ``/`` to place the file in a subdirectory (``Cacher`` keys such as ``session_web/<sha1>``).
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A cache key with a drive letter, a root, a ``..`` or ``.`` segment, an empty segment, a
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control character, or more than ``MAX_CACHE_KEY_DEPTH`` segments would let the peer write
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outside that directory or build an unbounded tree, so this function rejects it.
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PureWindowsPath treats both ``/`` and ``\\`` as separators, so this function rejects a
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cache key like ``..\\..\\secret`` even on POSIX (where backslash is a plain character).
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The function turns a surviving backslash into ``/`` so the same cache key names the
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same file on every platform.
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"""
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text = str(key)
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if not text or any(ord(ch) < 32 or ch == "\x7f" for ch in text):
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return None
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path = PureWindowsPath(text)
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if path.drive or path.root or path.anchor:
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return None
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parts = re.split(r"[\\/]", text)
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if len(parts) > MAX_CACHE_KEY_DEPTH:
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return None
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if any(not part or part in {".", ".."} or part.endswith((" ", ".")) or ":" in part for part in parts):
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return None
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return "/".join(parts)
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