Re: Should an IPv4 netmask be its own fieldtype?

[Evan Huus <eapache () gmail com>]

> On Oct 1, 2015, at 08:35, mmann78 () netscape net wrote:
>
> But doesn't any of these potential representations (mostly network prefix) require a specific field type (and not a 
> display type) for display filtering purposes?
>  

I don't think so. You can use an FT_UINT32 and just tweak the dfilter grammar to recognize /## as a shortcut for 
integers generally.

>  
> -----Original Message-----
> From: Jeffrey Smith <whydoubt () gmail com>
> To: Developer support list for Wireshark <wireshark-dev () wireshark org>
> Sent: Thu, Oct 1, 2015 1:46 am
> Subject: Re: [Wireshark-dev] Should an IPv4 netmask be its own fieldtype?
>
> RFC950: "Since the bits that identify the subnet are specified by a bitmask, they need not be adjacent in the 
> address. However, we recommend that the subnet bits be contiguous and located as the most significant bits of the 
> local address."
> So essentially any mask IS legal (even if not recommended).
> The two standard subnets notations are dotted decimal (e.g. 255.255.255.0) and network prefix (e.g. /24).  So 
> recognizing just "24" may not be terrible, but I find no precedent for doing so.
> > On Sep 30, 2015 11:03 PM, "Guy Harris" <guy () alum mit edu> wrote:
> >
> > On Sep 30, 2015, at 9:00 PM, Evan Huus <eapache () gmail com> wrote:
> >
> > > A pure netmask (without an associated address) is representable as
> > > just a UINT8. Would it be terrible to write `protocolXYZ.netmask ==
> > > 24`?
> >
> > Some are sent over the wire as a 32-bit mask, which could, conceivably, have holes in the middle.
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