69 lines
2.3 KiB
Python
69 lines
2.3 KiB
Python
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import binascii, utils
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context_FCP = object()
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context_FMD = object()
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context_FCI = object()
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recurse = object()
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binary = object()
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number = object()
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ascii = object()
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tags = {
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None: {
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0x62: (recurse, "File Control Parameters", context_FCP),
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0x64: (recurse, "File Management Data", context_FMD),
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0x6F: (recurse, "File Control Information", context_FCI),
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0x80: (number, "Number of data bytes in the file, excluding structural information"),
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0x81: (number, "Number of data bytes in the file, including structural information"),
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0x82: (binary, "File descriptor byte"),
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0x83: (binary, "File identifier"),
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0x84: (binary, "DF name"),
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0x85: (binary, "Proprietary information"),
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0x86: (binary, "Security attributes"),
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0x87: (binary, "Identifier of an EF containing an extension of the FCI"),
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},
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}
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def tvl_unpack(data):
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tag = ord(data[0])
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length = ord(data[1])
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value = data[2:(2+length)]
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rest = data[(2+length):]
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return tag, length, value, rest
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def decode(data, context = None, level = 0):
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result = []
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while len(data) > 0:
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tag, length, value, data = tvl_unpack(data)
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interpretation = tags.get(context, tags.get(None, {})).get(tag, (binary, "Unknown"))
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current = ["\t"*level]
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current.append("Tag 0x%02X, Len 0x%02X, '%s':" % (tag, length, interpretation[1]))
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if interpretation[0] is recurse:
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current.append("\n")
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current.append( decode(value, interpretation[2], level+1) )
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elif interpretation[0] is number:
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num = 0
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for i in value:
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num = num * 256
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num = num + ord(i)
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current.append( " 0x%02x (%i)" % (num, num))
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elif interpretation[0] is ascii:
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current.append( " %s" % value)
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elif interpretation[0] is binary:
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current.append( " %s" % utils.hexdump(value, short=True))
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result.append( "".join(current) )
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return "\n".join(result)
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if __name__ == "__main__":
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test = binascii.unhexlify("".join(("6f 2b 83 02 2f 00 81 02 01 00 82 03 05 41 26 85" \
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+"02 01 00 86 18 60 00 00 00 ff ff b2 00 00 00 ff" \
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+"ff dc 00 00 00 ff ff e4 10 00 00 ff ff").split()))
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decoded = decode(test)
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print decoded
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