mirror of https://github.com/akx/walletool.git
79 lines
2.2 KiB
Python
79 lines
2.2 KiB
Python
# -- encoding: UTF-8 --
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import sys
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assert sys.version_info[0] == 3 # TODO: Use six for 2/3 compat
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# From Joric's pywallet.
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import struct
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class SerializationError(Exception):
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pass
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class BCDataStream(object):
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def __init__(self, input):
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self.input = bytes(input)
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self.read_cursor = 0
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def read_string(self):
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# Strings are encoded depending on length:
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# 0 to 252 : 1-byte-length followed by bytes (if any)
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# 253 to 65,535 : byte'253' 2-byte-length followed by bytes
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# 65,536 to 4,294,967,295 : byte '254' 4-byte-length followed by bytes
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# ... and the Bitcoin client is coded to understand:
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# greater than 4,294,967,295 : byte '255' 8-byte-length followed by bytes of string
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# ... but I don't think it actually handles any strings that big.
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try:
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length = self.read_compact_size()
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except IndexError:
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raise SerializationError("attempt to read past end of buffer")
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return self.read_bytes(length)
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def read_bytes(self, length):
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try:
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result = self.input[self.read_cursor:self.read_cursor + length]
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self.read_cursor += length
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return result
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except IndexError:
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raise SerializationError("attempt to read past end of buffer")
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def read_boolean(self):
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return self.read_bytes(1)[0] != chr(0)
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def read_int16(self):
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return self._read_num('<h')
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def read_uint16(self):
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return self._read_num('<H')
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def read_int32(self):
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return self._read_num('<i')
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def read_uint32(self):
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return self._read_num('<I')
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def read_int64(self):
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return self._read_num('<q')
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def read_uint64(self):
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return self._read_num('<Q')
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def read_compact_size(self):
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size = int(self.input[self.read_cursor])
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self.read_cursor += 1
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if size == 253:
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size = self._read_num('<H')
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elif size == 254:
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size = self._read_num('<I')
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elif size == 255:
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size = self._read_num('<Q')
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return size
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def _read_num(self, format):
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(i,) = struct.unpack_from(format, self.input, self.read_cursor)
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self.read_cursor += struct.calcsize(format)
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return i
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