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acddc0ed3c
Done with a combination of regex'ing and banging my head against a wall. Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
62 lines
1.5 KiB
Python
62 lines
1.5 KiB
Python
# SPDX-License-Identifier: GPL-2.0-or-later
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# xref unique ID hash calculation
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#
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# Copyright (C) 2020 David Lamparter for NetDEF, Inc.
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import struct
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from hashlib import sha256
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def bititer(data, bits, startbit=True):
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"""
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just iterate the individual bits out from a bytes object
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if startbit is True, an '1' bit is inserted at the very beginning
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goes <bits> at a time, starts at LSB.
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"""
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bitavail, v = 0, 0
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if startbit and len(data) > 0:
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v = data.pop(0)
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yield (v & ((1 << bits) - 1)) | (1 << (bits - 1))
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bitavail = 9 - bits
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v >>= bits - 1
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while len(data) > 0:
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while bitavail < bits:
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v |= data.pop(0) << bitavail
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bitavail += 8
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yield v & ((1 << bits) - 1)
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bitavail -= bits
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v >>= bits
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def base32c(data):
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"""
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Crockford base32 with extra dashes
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"""
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chs = "0123456789ABCDEFGHJKMNPQRSTVWXYZ"
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o = ""
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if type(data) == str:
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data = [ord(v) for v in data]
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else:
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data = list(data)
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for i, bits in enumerate(bititer(data, 5)):
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if i == 5:
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o = o + "-"
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elif i == 10:
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break
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o = o + chs[bits]
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return o
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def uidhash(filename, hashstr, hashu32a, hashu32b):
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"""
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xref Unique ID hash used in FRRouting
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"""
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filename = "/".join(filename.rsplit("/")[-2:])
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hdata = filename.encode("UTF-8") + hashstr.encode("UTF-8")
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hdata += struct.pack(">II", hashu32a, hashu32b)
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i = sha256(hdata).digest()
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return base32c(i)
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