Re: Best way to handle a variable-length NULL-terminated string in a tvb

[Stephen Fisher <steve () stephen-fisher com>]

On Mon, May 03, 2010 at 11:14:15AM -0400, Jeremy O'Brien wrote:

> Actually, is there a function that will just get the length of said 
> string? I don't need to do anything with the string itself other than 
> add it to the proto_tree and of course increment my offset.

You could use tvb_get_ephemeral_stringz() to both fetch the string (and 
allocate memory) along with setting the length variable (passing it by 
reference as the third parameter).  Then add the string to the tree 
using proto_tree_add_string() and pass the string and the length 
variables starting at the offset variable (set to 0 before starting).  
Then increment offset by the length

This is basically what I did in epan/dissectors/packet-exec.c, but the 
packet data sounds a bit different from what you're working with.  In 
the (r)exec protocol, there are four null-terminated strings that it 
looks for.

Although, as Guy mentioned, you will have trouble (a thrown exception) 
with this if the final string really doesn't have a null.  Perhaps you 
could do a search (perhaps by using tvb_find_guint8 with '\0' as your 
needle [search term]) to see if there is a null coming up before looking 
for it, otherwise just grab the final string without a null 
(tvb_get_string).


-- 
Steve
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