145 lines
4.7 KiB
Python
145 lines
4.7 KiB
Python
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import hashlib
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from typing import TYPE_CHECKING, BinaryIO, Dict, Iterator, List
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from pip._internal.exceptions import HashMismatch, HashMissing, InstallationError
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from pip._internal.utils.misc import read_chunks
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if TYPE_CHECKING:
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from hashlib import _Hash
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# NoReturn introduced in 3.6.2; imported only for type checking to maintain
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# pip compatibility with older patch versions of Python 3.6
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from typing import NoReturn
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# The recommended hash algo of the moment. Change this whenever the state of
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# the art changes; it won't hurt backward compatibility.
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FAVORITE_HASH = "sha256"
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# Names of hashlib algorithms allowed by the --hash option and ``pip hash``
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# Currently, those are the ones at least as collision-resistant as sha256.
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STRONG_HASHES = ["sha256", "sha384", "sha512"]
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class Hashes:
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"""A wrapper that builds multiple hashes at once and checks them against
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known-good values
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"""
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def __init__(self, hashes: Dict[str, List[str]] = None) -> None:
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"""
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:param hashes: A dict of algorithm names pointing to lists of allowed
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hex digests
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"""
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allowed = {}
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if hashes is not None:
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for alg, keys in hashes.items():
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# Make sure values are always sorted (to ease equality checks)
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allowed[alg] = sorted(keys)
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self._allowed = allowed
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def __and__(self, other: "Hashes") -> "Hashes":
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if not isinstance(other, Hashes):
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return NotImplemented
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# If either of the Hashes object is entirely empty (i.e. no hash
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# specified at all), all hashes from the other object are allowed.
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if not other:
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return self
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if not self:
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return other
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# Otherwise only hashes that present in both objects are allowed.
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new = {}
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for alg, values in other._allowed.items():
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if alg not in self._allowed:
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continue
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new[alg] = [v for v in values if v in self._allowed[alg]]
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return Hashes(new)
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@property
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def digest_count(self) -> int:
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return sum(len(digests) for digests in self._allowed.values())
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def is_hash_allowed(self, hash_name: str, hex_digest: str) -> bool:
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"""Return whether the given hex digest is allowed."""
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return hex_digest in self._allowed.get(hash_name, [])
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def check_against_chunks(self, chunks: Iterator[bytes]) -> None:
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"""Check good hashes against ones built from iterable of chunks of
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data.
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Raise HashMismatch if none match.
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"""
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gots = {}
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for hash_name in self._allowed.keys():
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try:
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gots[hash_name] = hashlib.new(hash_name)
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except (ValueError, TypeError):
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raise InstallationError(f"Unknown hash name: {hash_name}")
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for chunk in chunks:
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for hash in gots.values():
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hash.update(chunk)
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for hash_name, got in gots.items():
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if got.hexdigest() in self._allowed[hash_name]:
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return
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self._raise(gots)
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def _raise(self, gots: Dict[str, "_Hash"]) -> "NoReturn":
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raise HashMismatch(self._allowed, gots)
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def check_against_file(self, file: BinaryIO) -> None:
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"""Check good hashes against a file-like object
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Raise HashMismatch if none match.
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"""
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return self.check_against_chunks(read_chunks(file))
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def check_against_path(self, path: str) -> None:
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with open(path, "rb") as file:
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return self.check_against_file(file)
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def __bool__(self) -> bool:
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"""Return whether I know any known-good hashes."""
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return bool(self._allowed)
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def __eq__(self, other: object) -> bool:
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if not isinstance(other, Hashes):
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return NotImplemented
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return self._allowed == other._allowed
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def __hash__(self) -> int:
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return hash(
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",".join(
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sorted(
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":".join((alg, digest))
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for alg, digest_list in self._allowed.items()
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for digest in digest_list
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)
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)
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)
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class MissingHashes(Hashes):
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"""A workalike for Hashes used when we're missing a hash for a requirement
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It computes the actual hash of the requirement and raises a HashMissing
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exception showing it to the user.
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"""
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def __init__(self) -> None:
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"""Don't offer the ``hashes`` kwarg."""
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# Pass our favorite hash in to generate a "gotten hash". With the
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# empty list, it will never match, so an error will always raise.
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super().__init__(hashes={FAVORITE_HASH: []})
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def _raise(self, gots: Dict[str, "_Hash"]) -> "NoReturn":
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raise HashMissing(gots[FAVORITE_HASH].hexdigest())
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