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Re: FT_BYTES hf with len==0
From: Martin Kaiser <lists () kaiser cx>
Date: Fri, 20 Dec 2013 18:25:19 +0100

Thus wrote Martin Kaiser (lists () kaiser cx):

5392             label_fill(label_str, 0, hfinfo,
5393                             (bytes) ? bytes_to_str(bytes, fvalue_length(&fi->value)) : "<MISSING>");
5394             break;

It'd be good to make them consistent, allow empty bytes (+1 from me) or assert in both place.

ok, I'll change this.

done in r54290.

I've just found one more issue with empty FT_BYTES:
When I click on an empty FT_BYTES element in the tree and select Apply
as Filter / Selected, wireshark creates a filter expression

<filter name>==

that results in a syntax error.

This is created by construct_match_selected_string(), which calls
fvalue_to_string_repr() and uses the fvalue's string representation by

One way to resolve this would be to change an empty FT_BYTES' string
representation from <nothing> to "" (as <filter name>=="" is a valid
filter expression). See the attached patch.

Is that ok or does it break someone else's code? Should I check for
FTREPR_DFILTER and modify the representation for empty FT_BYTES only in
this case?

Attachment: bytes_repr.patch

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