For some of the protocols that I am writing dissectors for there is a need to know the direction of the message.
For instance GSM SMS TPDUs (GSM 03.40) require different dissection depending on whether the message is going towards the mobile or from the mobile. Does anybody know of a dissector that requires this that I can look at, or does anyone have a good solution? My current solution, which I don't necessarily like, is the addition of a preference called "Source PC" in my SCCP dissector. My work involves Mobile Switching Centre (MSC) development, so I set the Source PC to be the point code of the MSC. Any message with a DPC=Source PC is an uplink message (towards the MSC) and any with an OPC=Source PC is downlink (from the MSC). I can think of 3 ways to pass the 'uplink/downlink' status to other dissectors further up the stack. 1. private_data pointer in the pinfo buffer 2. global variable 3. use "register_dissector_table()" twice Does anybody have some experience with this problem? -- Michael Lum Architect 4600 Jacombs Road (604) 276-0055 Richmond, B.C. Canada V6V 3B1 Telos Technology Winner of the 2003 GSM Association Award for Technology Innovation Best Infrastructure
