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1
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""" |
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2
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Helper function and classes that do not rely on asyncua library. |
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3
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Helper function and classes depending on ua object are in ua_utils.py |
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4
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""" |
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5
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6
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import os |
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7
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import logging |
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8
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from ..ua.uaerrors import UaError |
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9
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10
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_logger = logging.getLogger(__name__) |
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11
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12
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13
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class ServiceError(UaError): |
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14
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def __init__(self, code): |
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15
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super(ServiceError, self).__init__('UA Service Error') |
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16
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self.code = code |
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17
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18
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19
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class NotEnoughData(UaError): |
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20
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pass |
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21
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22
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23
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class SocketClosedException(UaError): |
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24
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pass |
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25
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26
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27
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class Buffer: |
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28
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""" |
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29
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Alternative to io.BytesIO making debug easier |
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30
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and added a few convenience methods. |
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31
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""" |
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32
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33
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def __init__(self, data, start_pos=0, size=-1): |
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34
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self._data = data |
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35
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self._cur_pos = start_pos |
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36
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if size == -1: |
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37
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size = len(data) - start_pos |
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38
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self._size = size |
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39
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40
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def __str__(self): |
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41
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return f"Buffer(size:{self._size}, data:{self._data[self._cur_pos:self._cur_pos + self._size]})" |
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42
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__repr__ = __str__ |
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43
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44
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def __len__(self): |
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45
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return self._size |
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46
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47
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def __bool__(self): |
|
48
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return self._size > 0 |
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49
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|
50
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def __bytes__(self): |
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51
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"""Return remains of buffer as bytes.""" |
|
52
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return self._data[self._cur_pos:] |
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53
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|
54
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def read(self, size): |
|
55
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""" |
|
56
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read and pop number of bytes for buffer |
|
57
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""" |
|
58
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if size > self._size: |
|
59
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raise NotEnoughData(f"Not enough data left in buffer, request for {size}, we have {self._size}") |
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60
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self._size -= size |
|
61
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pos = self._cur_pos |
|
62
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self._cur_pos += size |
|
63
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return self._data[pos:self._cur_pos] |
|
64
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|
65
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def copy(self, size=-1): |
|
66
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""" |
|
67
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return a shadow copy, optionally only copy 'size' bytes |
|
68
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""" |
|
69
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|
|
if size == -1 or size > self._size: |
|
70
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size = self._size |
|
71
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return Buffer(self._data, self._cur_pos, size) |
|
72
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|
73
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|
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def skip(self, size): |
|
74
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|
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""" |
|
75
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|
|
skip size bytes in buffer |
|
76
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""" |
|
77
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|
|
if size > self._size: |
|
78
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|
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raise NotEnoughData(f"Not enough data left in buffer, request for {size}, we have {self._size}") |
|
79
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self._size -= size |
|
80
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|
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self._cur_pos += size |
|
81
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|
82
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|
83
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|
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def create_nonce(size=32): |
|
84
|
|
|
return os.urandom(size) |
|
85
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|
FreeOpcUa /
opcua-asyncio
