Wireshark-dev: Re: [Wireshark-dev] Best way to handle a variable-length NULL-terminated string
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. I know I
could just g_free the string immediately after fetching it, but this
seems like it has a little overhead.
On Mon, May 3, 2010 at 11:08, Jeremy O'Brien <obrien654j@xxxxxxxxx> wrote:
> Separated by. tvb_get_stringz is exactly what I was looking for. Thank you!
>
> On Fri, Apr 30, 2010 at 15:42, Guy Harris <guy@xxxxxxxxxxxx> wrote:
>>
>> On Apr 30, 2010, at 12:33 PM, Jeremy O'Brien wrote:
>>
>>> So I have several strings in my protocol, which are separated by
>>> NULL's.
>>
>> Separated by, or terminated by?
>>
>> I.e., is there a NUL at the end of the *last* string, or just in *between* strings?
>>
>>> There is no information contained in the packet that gives the
>>> length of each string. Is there a better way to add these strings to
>>> the protocol dissection besides doing a tvb_get_ephemeral_string() on
>>> the section of the tvb in question, searching for the ending NULL's
>>> for each string, and manually incrementing the offset for each one?
>>> I'm just not sure if wireshark has any convenience functions that
>>> would handle this sort of situation.
>>
>> /**
>> * Given a tvbuff and an offset, with the offset assumed to refer to
>> * a null-terminated string, find the length of that string (and throw
>> * an exception if the tvbuff ends before we find the null), allocate
>> * a buffer big enough to hold the string, copy the string into it,
>> * and return a pointer to the string. Also return the length of the
>> * string (including the terminating null) through a pointer.
>> *
>> * tvb_get_stringz() returns a string allocated by g_malloc() and therefore
>> * MUST be g_free() by the caller in order not to leak
>> * memory.
>> *
>> * tvb_get_ephemeral_stringz() returns a string that does not need to be freed,
>> * instead it will automatically be freed once the next
>> * packet is dissected.
>> *
>> * tvb_get_seasonal_stringz() returns a string that does not need to be freed,
>> * instead it will automatically be freed when a new capture
>> * or file is opened.
>> */
>> extern guint8 *tvb_get_stringz(tvbuff_t *tvb, const gint offset, gint *lengthp);
>> extern guint8 *tvb_get_ephemeral_stringz(tvbuff_t *tvb, const gint offset, gint *lengthp);
>> extern guint8 *tvb_get_seasonal_stringz(tvbuff_t *tvb, const gint offset, gint *lengthp);
>>
>> You presumably want tvb_get_ephemeral_stringz().
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>
