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Wireshark-dev: Re: [Wireshark-dev] Decompress Data

From: Marcel Haas <inf462@xxxxxxxxxxx>
Date: Fri, 07 Oct 2011 13:38:33 +0200
On Fri, 7 Oct 2011 13:21:15 +0200, fab12@xxxxxxxxxxx wrote:
I have a example from my plugin if it may help:

        unsigned char Ip_Buffer[2000];

        /* Get the buffer bytes to decompress */
	tvb_memcpy(tvb, Ip_Buffer, (*bitoffset)/8,lgpdubit/8);

        /*
         * Decompress it:
         * Decompressed buffer is output in Op_Buffer,
         * size of the decompressed buffer (in bit in this case) in
SizeInBits */
         */
	rc = decompress(Ip_Buffer, lgpdubit - ((8-bitnb) % 8), &(Op_Buffer),
&O_SizeInBits);

        /* Now re-setup the tvb buffer to have the new data */
        next_tvb = tvb_new_real_data(Op_Buffer, O_SizeInBits/8,
O_SizeInBits/8);
        tvb_set_child_real_data_tvbuff(tvb, next_tvb);
        add_new_data_source(pInfoG, next_tvb, "Decompressed Data");

 /* From here dissect next_tvb from offset 0 */



Where u get the decompress function and what type does rc have .. ?


 On Fri, 7 Oct 2011 13:51:13 +0400, Max Dmitrichenko
 <dmitrmax@xxxxxxxxx> wrote:
2011/10/7 Marcel Haas <inf462@xxxxxxxxxxx>:
And i have the next problem. Damn wireshark kick my ass :)

I have some packets witch are compress witz zlib.
I want to uncompress them.
I read the dev-guid about transformed data but i dont have a clue.
I were testing some stuff but with no good result.
Can someone help me with that ?

It is simple.
1) You have to know the size of decompressed data, e.g. in
buffer_size variable.
2) Alloc the buffer of needed size for it using e.g. se_alloc, e.g.
you have pointer to alloced buffer called buffer_ptr.
3) Decompress you data into that buffer.
4) call
     child_tvb = tvb_new_child_real_data(current_tvb, buffer_ptr,
buffer_size, buffer_size);
5) call
     add_new_data_source(pinfo, child_tvb, "Decompressed Data");
6*) Optionally you can dissect child_tvb as any usual TVB.

In the GUI you'll get the decompressed data into another tab called
"Decompressed Data" or any other name you provide in step 5.

--
  Max


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 hmm i dont get it at all .. my code looks like this :

 guint8 *buff;
 tvbuff_t *compress_tvb;
 int captured_size;

captured_size=tvb_length_remaining(tvb, offset2); //I think that what u
 mean by 1
 buff= g_malloc(captured_size); // step 2 ?
 compress_tvb=tvb_new_real_data(buff,captured_size,captured_size);//
 step 4 ?
tvb_set_free_cb(compress_tvb,g_free); // step
 4 ?
tvb_set_child_real_data_tvbuff(tvb,compress_tvb); // step
 4 ?
add_new_data_source(pinfo,compress_tvb,"Decompressed TVB"); //step 5








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