Re: Wireshark lua (wslua) and bit fields - how to do it?

[Daniel Lynes <dlynes () pv-labs com>]

Thanks, Tamás,

Is this the best way of doing bitfields in wireshark, if you want to
make them filterable?

On Fri, 2010-10-22 at 13:05 +0800, Tamás Regõs wrote:
> Hi,
>  
> Try ByteArray.tvb(hexba,"hex") instead of Tvb.new_real(hexba, "hex")
> Tvb.new_real does not exists.
>  
> Regards,
> Tamas
>  
>
>
>
>
> ______________________________________________________________________
> From: wireshark-dev-bounces () wireshark org
> [mailto:wireshark-dev-bounces () wireshark org] On Behalf Of Daniel Lynes
> Sent: Friday, 22 October 2010 4:46 AM
> To: wireshark-dev () wireshark org
> Subject: [Wireshark-dev] Wireshark lua (wslua) and bit fields - how to
> do it?
>
>
>
>
> I'm trying to output some bit values in my wireshark dissector decode.
> However, I want to be able to filter based on those bit values.
>
> I can't seem to use the LUA bitop library to do it, because lua
> complains that the result is not a uservalue.
>
> I've got the following code:
>
>                         for shred = 1, num_shreds
>                         do
>                                 subtree:add("----- NV Storage Shred
> " .. shred .. " -----")
>                                 subtree:add(fields.shred_id,
> buffer(offset, 8))
>                                 subtree:add(fields.shred_flags,
> buffer(offset+8, 8))
>                                 local
> flags=tonumber(tostring(buffer(offset+8,8):uint64()))
>                                 local
> hex=tostring(bit.tohex(bit.band(flags,0x02)))
>                                 subtree:add("----- NV Storage hex
> flags: " .. hex)
>                                 local hexba=ByteArray.new(hex)
>                           -- The following line complains about a nil
> uservalue
>                                 local rdonly=Tvb.new_real(hexba,
> "hex")
>                           -- The following line complains about the
> value being a number instead of a uservalue
>                                 subtree:add(fields.shred_rd,
> bit.band(flags, 0x02))
>                                 offset=offset+inc
>                         end
>
> Does anyone happen to have any clues as to what I'm doing wrong?
> Fwiw, I'm using 1.2.0 (1.3, 1.4, and 1.5 all have video corruption
> issues, and 1.0 has issues with 64-bit integers).
>
> Thanks. 

Daniel Lynes
Software Engineer
PV Labs Intelligent Imaging
(905) 667-7308

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