52 lines
1.9 KiB
Python
52 lines
1.9 KiB
Python
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import enum
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import entry
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import hashing
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class result(enum.Enum):
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notfound, ok, fail = range(3)
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def check_fingerprint(entries, domain, port, fingerprint):
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"""check_fingerprint([Entry], str, u16, bytes[32]) → (enum result: result, str / None: comment)
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Checks if the given host is found with the given fingerprint.
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Will return the comment on the host if the host is found, regardless
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of whether the fingerprint checks out."""
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assert type(entries) == list and all(type(i) == entry.Entry for i in entries)
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assert type(domain) == str
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assert type(port) == int and 0 <= port <= (1<<16) - 1
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assert type(fingerprint) == bytes and len(fingerprint) == 32
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# Normalize the host here, so we don't have to do it every time we
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# check for a possible match
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normalized_hosts = [entry.normalize_host(domain, port)]
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# If we are looking at non-22 port, also check the general form of
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# the host without a port specifier. This seems to be how OpenSSH
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# does it too
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if port != 22:
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normalized_hosts.append(entry.normalize_host(domain, 22))
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for possible_match in entries:
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for normalized_host in normalized_hosts:
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hashed_host = hashing.hash_with_salt(normalized_host, possible_match.salt)
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if hashed_host == possible_match.hashed_host:
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# Convert the comment to a string
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# We put replacement characters where
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# decoding fails instead of throwing an
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# error, because even whilethe comment
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# field must be valid utf-8, failing in this
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# situation is bad UX
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comment = possible_match.comment.decode('utf-8', errors = 'replace')
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# TODO: Justify this
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# We only care about the first match, so we
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# return here
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if fingerprint == possible_match.fingerprint:
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# Fingerprint matches, it passes
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return (result.ok, comment)
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else:
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# Fingerprint different, it fails
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return (result.fail, comment)
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# We did not match, tell the caller so
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return (result.notfound, None)
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