listShares() shows struct.error about pysmb HOT 5 CLOSED

Patch has been merged and released under pysmb 1.1.23.

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I have also stumbled on this issue. It happens when the whole list of shares cannot be returned in a single response, and a second one has to be issued. The code that handles the response is in smb\base.py. The second response is parsed by readCB(read_message, **kwargs) and oddly enough the data returned in the response is trimmed by 24 bytes before and after: kwargs['data_bytes'] + data_bytes[24:data_len-24].

I've been looking for an explanation to these 24 bytes, but I haven't found an easy answer. The only thing that seems to be linked is that the ComReadAndxResponse header is also 24 bytes. (introduced in commit f6ebcd4)

I changed kwargs['data_bytes'] + data_bytes[24:data_len-24] to kwargs['data_bytes'] + data_bytes[24:data_len] and it seems to work for me, but I'm not sure if this is correct.

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I'm also having this issue and removing the 24-byte trim allows it to work. At first glance, it looks like the first 24 bytes are being dropped and the data_len-24 is just making sure the buffer doesn't overflow but, of course, that's not how byte slices work. I wonder if all those data_bytes[24:data_len-24] shouldn't all be just data_bytes[24:]...

Traceback (most recent call last):
  File "./pysmb-test.py", line 74, in <module>
    main()
  File "./pysmb-test.py", line 66, in main
    for entry in conn.listShares():
  File "/home/vagrant/bpstat-venv/lib64/python3.6/site-packages/smb/SMBConnection.py", line 149, in listShares
    self._pollForNetBIOSPacket(timeout)
  File "/home/vagrant/bpstat-venv/lib64/python3.6/site-packages/smb/SMBConnection.py", line 614, in _pollForNetBIOSPacket
    self.feedData(data)
  File "/home/vagrant/bpstat-venv/lib64/python3.6/site-packages/nmb/base.py", line 54, in feedData
    self._processNMBSessionPacket(self.data_nmb)
  File "/home/vagrant/bpstat-venv/lib64/python3.6/site-packages/nmb/base.py", line 75, in _processNMBSessionPacket
    self.onNMBSessionMessage(packet.flags, packet.data)
  File "/home/vagrant/bpstat-venv/lib64/python3.6/site-packages/smb/base.py", line 138, in onNMBSessionMessage
    if self._updateState(self.smb_message):
  File "/home/vagrant/bpstat-venv/lib64/python3.6/site-packages/smb/base.py", line 279, in _updateState_SMB2
    req.callback(message, **req.kwargs)
  File "/home/vagrant/bpstat-venv/lib64/python3.6/site-packages/smb/base.py", line 506, in readCB
    decodeResults(read_message.tid, kwargs['fid'], kwargs['data_bytes'] + data_bytes[24:data_len-24])
  File "/home/vagrant/bpstat-venv/lib64/python3.6/site-packages/smb/base.py", line 476, in decodeResults
    max_length, _, length = struct.unpack('<III', data_bytes[offset:offset+12])
struct.error: unpack requires a buffer of 12 bytes

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@carlosefr : Can you provide more information about your remote SMB server and OS? Thank you.

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I'm seeing this with OS=[Windows Server 2016 Standard 14393] Server=[Windows Server 2016 Standard 6.3] where the number of shares is around 120.

I don't see this problem in another server with OS=[Windows Server 2012 R2 Standard 9600] Server=[Windows Server 2012 R2 Standard 6.3] where there are "only" around 50 shares.

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