Wireshark-dev: Re: [Wireshark-dev] SCPS dissector.
From: Guy Harris <guy@xxxxxxxxxxxx>
Date: Mon, 6 Oct 2008 09:44:44 -0700
On Oct 6, 2008, at 8:09 AM, Cosmin Craciunescu wrote:

One problem is in order to dissect IP protocol 0x69 (SCPS)
SCPS compressed TCP, that is (according to the SCPS-NS specification).

I need to
have access to information from the TCP packet with the SYN flag for
this connection (it's a convoluted protocol).
I.e., the connection starts out using TCP (protocol 6) and then  
switches to compressed-header TCP (protocol 105)?
Does the initial SYN always have SCPS options?  If so,  
dissect_tcpopt_scps() in the TCP dissector could attach the relevant  
information to the conversation for the TCP connection, and the SCPS  
dissector could look for the TCP conversation and use that  
information.  If not, the TCP dissector might have to have an option  
to create a conversation and attach the relevant data (if it already  
does so, it probably needs to have that controlled by an option, so  
that a TCP capture with a SYN flood doesn't cause a lot of  
conversations to be allocated - that was an issue with tcpdump, which  
allocates a conversation data structure by default).