prashanth joshi wrote:

> So length-2 bytes of data is added in to tree ,starting from the 
> location number ofset + 5 of tvb.
> My query is : is it absolutely necessary to have hf_gtp_ext_
> as the second argument when ever we want to add an item?
> Can not we do away with it by having a NULL as second argument instead?

No.

For one thing, the second argument is an integer value, not a pointer, 
so NULL doesn't make sense as the second argument.

Furthermore, proto_tree_add_item() adds an instance of a named field, so 
you *have* to supply an integer value that identifies a named field.

> ( I found it difficult to understand how the contents of the 
> proto_register_gtp array are built)
> And what would be the limitations if we try to add an item using the 
> proto_tree_add_text( ) instead ?

Well, one limitation is that you will not be able to do any display 
filtering on the value - it'll just be entered as text to be displayed. 
  You won't be able to select packets with a particular value of that 
field by doing "gtp.ext_val == <value>".
_______________________________________________
Wireshark-dev mailing list
[email protected]
http://www.wireshark.org/mailman/listinfo/wireshark-dev

Reply via email to