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Diffstat (limited to 'contrib/seeds/asmap.py')
-rw-r--r-- | contrib/seeds/asmap.py | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/contrib/seeds/asmap.py b/contrib/seeds/asmap.py new file mode 100644 index 0000000000..e7e05a1d10 --- /dev/null +++ b/contrib/seeds/asmap.py @@ -0,0 +1,90 @@ +#!/usr/bin/env python3 +# Copyright (c) 2013-2020 The Bitcoin Core developers +# Distributed under the MIT software license, see the accompanying +# file COPYING or http://www.opensource.org/licenses/mit-license.php. +import ipaddress + +# Convert a byte array to a bit array +def DecodeBytes(byts): + return [(byt >> i) & 1 for byt in byts for i in range(8)] + +def DecodeBits(stream, bitpos, minval, bit_sizes): + val = minval + for pos in range(len(bit_sizes)): + bit_size = bit_sizes[pos] + if pos + 1 < len(bit_sizes): + bit = stream[bitpos] + bitpos += 1 + else: + bit = 0 + if bit: + val += (1 << bit_size) + else: + for b in range(bit_size): + bit = stream[bitpos] + bitpos += 1 + val += bit << (bit_size - 1 - b) + return (val, bitpos) + assert(False) + +def DecodeType(stream, bitpos): + return DecodeBits(stream, bitpos, 0, [0, 0, 1]) + +def DecodeASN(stream, bitpos): + return DecodeBits(stream, bitpos, 1, [15, 16, 17, 18, 19, 20, 21, 22, 23, 24]) + +def DecodeMatch(stream, bitpos): + return DecodeBits(stream, bitpos, 2, [1, 2, 3, 4, 5, 6, 7, 8]) + +def DecodeJump(stream, bitpos): + return DecodeBits(stream, bitpos, 17, [5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30]) + +def Interpret(asmap, num, bits): + pos = 0 + default = None + while True: + assert(len(asmap) >= pos + 1) + (opcode, pos) = DecodeType(asmap, pos) + if opcode == 0: + (asn, pos) = DecodeASN(asmap, pos) + return asn + elif opcode == 1: + (jump, pos) = DecodeJump(asmap, pos) + if (num >> (bits - 1)) & 1: + pos += jump + bits -= 1 + elif opcode == 2: + (match, pos) = DecodeMatch(asmap, pos) + matchlen = match.bit_length() - 1 + for bit in range(matchlen): + if ((num >> (bits - 1)) & 1) != ((match >> (matchlen - 1 - bit)) & 1): + return default + bits -= 1 + elif opcode == 3: + (default, pos) = DecodeASN(asmap, pos) + else: + assert(False) + + + +def decode_ip(ip: str) -> int: + addr = ipaddress.ip_address(ip) + if isinstance(addr, ipaddress.IPv4Address): + return int.from_bytes(addr.packed, 'big') + 0xffff00000000 + elif isinstance(addr, ipaddress.IPv6Address): + return int.from_bytes(addr.packed, 'big') + +class ASMap: + def __init__(self, filename): + ''' + Instantiate an ASMap from a file. + ''' + with open(filename, "rb") as f: + self.asmap = DecodeBytes(f.read()) + + def lookup_asn(self, ip): + ''' + Look up the ASN for an IP, returns an ASN id as integer or None if not + known. + ''' + return Interpret(self.asmap, decode_ip(ip), 128) |