161 lines
3.7 KiB
Python
161 lines
3.7 KiB
Python
##
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#
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# bencode.py python3 compatable bencode / bdecode
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#
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##
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class Decoder(object):
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def _decode_int(self):
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"""
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decode integer from bytearray
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return int
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"""
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self.idx += 1
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start = self.idx
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end = self.data.index(b'e', self.idx)
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self.idx = end + 1
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return int(self.data[start:end])
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def _decode_str(self):
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"""
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decode string from bytearray
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return string
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"""
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start = self.data.index(b':', self.idx)
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l = int(self.data[self.idx:start].decode(), 10)
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if l <= 0:
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raise Exception('invalid string size: %d' % l)
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start += 1
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ret = self.data[start:start+l]
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try:
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ret = ret.decode('utf-8')
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except:
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pass
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self.idx = start + l
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return ret
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def _decode_list(self):
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"""
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decode list from bytearray
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return list
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"""
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ls = []
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self.idx += 1
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while self.data[self.idx] != ord(b'e'):
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ls.append(self._decode())
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self.idx += 1
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return ls
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def _decode_dict(self):
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"""
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decode dict from bytearray
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return dict
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"""
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d = {}
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self.idx += 1
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while self.data[self.idx] != ord(b'e'):
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k = self._decode_str()
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v = self._decode()
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d[k] = v
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self.idx += 1
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return d
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def _decode(self):
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ch = chr(self.data[self.idx])
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if ch == 'l':
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return self._decode_list()
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elif ch == 'i':
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return self._decode_int()
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elif ch == 'd':
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return self._decode_dict()
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elif ch.isdigit():
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return self._decode_str()
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else:
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raise Exception('could not decode data: %s' % data)
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def decode(self, data):
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self.idx = 0
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self.data = data
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obj = self._decode()
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if len(data) != self.idx:
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raise Exception('failed to decode, extra data: %s' % data)
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return obj
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def bdecode(data):
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"""
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decode a bytearray
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return decoded object
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"""
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return Decoder().decode(data)
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def _encode_str(s, buff):
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"""
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encode string to a buffer
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"""
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s = bytearray(s)
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l = len(s)
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buff.append(bytearray(str(l)+':', 'utf-8'))
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buff.append(s)
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def _encode_int(i, buff):
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"""
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encode integer to a buffer
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"""
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buff.append(b'i')
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buff.append(bytearray(str(i), 'ascii'))
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buff.append(b'e')
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def _encode_list(l, buff):
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"""
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encode list of elements to a buffer
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"""
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buff.append(b'l')
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for i in l:
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_encode(i, buff)
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buff.append(b'e')
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def _encode_dict(d, buff):
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"""
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encode dict
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"""
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buff.append(b'd')
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for k in sorted(d):
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if not isinstance(k, (bytes, str)):
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k = str(k)
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_encode(k, buff)
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_encode(d[k], buff)
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buff.append(b'e')
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def _encode(obj, buff):
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"""
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encode element obj to a buffer buff
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"""
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if isinstance(obj, str):
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_encode_str(bytearray(obj, 'utf-8'), buff)
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elif isinstance(obj, bytes):
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_encode_str(bytearray(obj), buff)
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elif isinstance(obj, bytearray):
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_encode_str(obj, buff)
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elif str(obj).isdigit():
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_encode_int(obj, buff)
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elif isinstance(obj, list):
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_encode_list(obj, buff)
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elif hasattr(obj, 'keys') and hasattr(obj, 'values'):
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_encode_dict(obj, buff)
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elif str(obj) in ['True', 'False']:
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_encode_int(int(obj and '1' or '0'), buff)
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else:
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raise Exception('non serializable object: %s' % obj)
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def bencode(obj):
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"""
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bencode element, return bytearray
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"""
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buff = []
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_encode(obj, buff)
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ret = bytearray()
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for ba in buff:
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ret += ba
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return bytes(ret)
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