from __future__ import absolute_import import hashlib from pip.exceptions import HashMismatch, HashMissing, InstallationError from pip.utils import read_chunks from pip._vendor.six import iteritems, iterkeys, itervalues # The recommended hash algo of the moment. Change this whenever the state of # the art changes; it won't hurt backward compatibility. FAVORITE_HASH = 'sha256' # Names of hashlib algorithms allowed by the --hash option and ``pip hash`` # Currently, those are the ones at least as collision-resistant as sha256. STRONG_HASHES = ['sha256', 'sha384', 'sha512'] class Hashes(object): """A wrapper that builds multiple hashes at once and checks them against known-good values """ def __init__(self, hashes=None): """ :param hashes: A dict of algorithm names pointing to lists of allowed hex digests """ self._allowed = {} if hashes is None else hashes def check_against_chunks(self, chunks): """Check good hashes against ones built from iterable of chunks of data. Raise HashMismatch if none match. """ gots = {} for hash_name in iterkeys(self._allowed): try: gots[hash_name] = hashlib.new(hash_name) except (ValueError, TypeError): raise InstallationError('Unknown hash name: %s' % hash_name) for chunk in chunks: for hash in itervalues(gots): hash.update(chunk) for hash_name, got in iteritems(gots): if got.hexdigest() in self._allowed[hash_name]: return self._raise(gots) def _raise(self, gots): raise HashMismatch(self._allowed, gots) def check_against_file(self, file): """Check good hashes against a file-like object Raise HashMismatch if none match. """ return self.check_against_chunks(read_chunks(file)) def check_against_path(self, path): with open(path, 'rb') as file: return self.check_against_file(file) def __nonzero__(self): """Return whether I know any known-good hashes.""" return bool(self._allowed) def __bool__(self): return self.__nonzero__() class MissingHashes(Hashes): """A workalike for Hashes used when we're missing a hash for a requirement It computes the actual hash of the requirement and raises a HashMissing exception showing it to the user. """ def __init__(self): """Don't offer the ``hashes`` kwarg.""" # Pass our favorite hash in to generate a "gotten hash". With the # empty list, it will never match, so an error will always raise. super(MissingHashes, self).__init__(hashes={FAVORITE_HASH: []}) def _raise(self, gots): raise HashMissing(gots[FAVORITE_HASH].hexdigest())