Wireshark-dev: [Wireshark-dev] Small bug in Modbus dissector exception information
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From: Dennis Luehring <dl.soluz@xxxxxxx>
Date: Sat, 30 Jul 2016 08:27:33 +0200
i use a "Live on the Bleeding Edge" Version
https://www.wireshark.org/download/automated/win64/Wireshark-win64-2.3.0-128-g98e8b26.exe

Sample Modbus-Exception-Code Response:
00 00 00 00 00 03 00 88 01

Modbus/TCP
    Transaction Identifier: 0
    Protocol Identifier: 0
    Length: 3
    Unit Identifier: 0
Function 8:  Diagnostics.  Exception: Illegal function
Function Code: Unknown (136) <-- !! the execption bit does not get masked here !! (136 & 0x7F) == 8 
    Exception Code: Illegal function (1)