Wireshark · Ethereal-dev: Re: [Ethereal-dev] Patch to expose OPC/DPC from MTP3, SCCP preferences

[Jeff Morriss <morriss@xxxxxxxxx>]

Michael Lum wrote:

> > -----Original Message-----
> > From: Jeff Morriss [mailto:morriss@XXX]
> >
> > Michael Lum wrote:
> >
> >
> > > I wanted to make the following changes to the MTP3 dissector:
> > >
> > > 1.  Add two hidden uint32 fields for 24bit OPC/DPC
> > > 	This allows display filtering using the complete 24 bit
> >
> > integer value
> >
> > > 	as an alternative to something like "mtp3.ansi_opc == 214-170-26".
> > >
> > > 	i.e.  "mtp3.24bit_opc == 0x66aad6" or "mtp3.24bit_opc == 6728406"
> >
> > Why not re-use "mtp3.opc" (normally used for ITU) in ANSI--but hidden?
>
> One other reason is that currently the opc header field definition use a 14
> bit
> MASK.

It's been a while since I actually worked on a dissector, but I think 
it's okay to have 2 hf_ variables that correspond to the same filter 
string.  E.g. something like:

>     { &hf_mtp3_itu_opc,
>       { "OPC", "mtp3.opc",   
>               FT_UINT32, BASE_DEC, NULL, ITU_OPC_MASK,
>               "", HFILL }},
>     { &hf_mtp3_ansi_opc,
>       { "DPC", "mtp3.opc",
>               FT_UINT32, BASE_NONE, NULL, 0x0,
>               "", HFILL }},