bluetooth - Unable to unpack

Question

I am getting below errors while parsing BLE packet. Any suggestion how to fix this?

Packet b'x04>+x02x01x03x01xd7xd3Axc9xaexf5x1fx02x01x06x03x03xaaxfex17x16xaaxfex00xd8x8bx9cxc7<:xe7Gxefexbcx00x00x00x00x15xd1x00x00xaf'

Traceback (most recent call last):
File "BluetoothWiliot.py", line 95, in <module>
    dataString = parse_events(sock, 100)
File "BluetoothWiliot.py", line 47, in parse_events
    print(struct.unpack("B", bytes(pkt[3])))
**struct.error: unpack requires a buffer of 1 bytes**


Traceback (most recent call last):
File "BluetoothWiliot.py", line 95, in <module>
    dataString = parse_events(sock, 100)
File "BluetoothWiliot.py", line 47, in parse_events
    print(struct.unpack("B", pkt[3]))

**TypeError: a bytes-like object is required, not 'int'**

Answer 1

int.from_bytes is normally my go to function for these situations but there are a number of options:

$ python3
Python 3.7.3 (default, Jul 25 2020, 13:03:44) 
[GCC 8.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> pkt = b'x04>+x02x01x03x01xd7xd3Axc9xaexf5x1fx02x01x06x03x03xaaxfex17x16xaaxfex00xd8x8bx9cxc7<:xe7Gxefexbcx00x00x00x00x15xd1x00x00xaf'
>>> pkt[3]
2
>>> int.from_bytes([pkt[3]], byteorder='little', signed=False)
2
>>> struct.unpack_from('B', pkt, 3)
(2,)
>>> struct.unpack('B',pkt[3:3+1])
(2,)
>>> struct.unpack('B', bytes([pkt[3]]))
(2,)