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Wireshark-dev: [Wireshark-dev] Creating a TVB

From: Paul Offord <Paul.Offord@xxxxxxxxxxxx>
Date: Wed, 28 Feb 2018 09:49:28 +0000

Hi,

 

I’m writing a dissector for a new block type.  I register a block read function for my new block type, and when Wireshark detects one of these blocks, my block read function is called with the following parameters:

 

gboolean tdb_read_block(FILE_T fh, guint32 block_data_len, gboolean c, wtapng_block_t *wtapng_block,   int *err, gchar **err_info)

 

This function then reads the block content like this:

 

    /* read block content */

    if (!wtap_read_bytes(fh, wtapng_block->frame_buffer->data, block_data_len, err, err_info)) {

        wmem_strdup_printf(wmem_file_scope(), "tdb_read_block: failed to read TDB");

        return FALSE;

    }

 

Later I need to parse the serialised data in wtapng_block->frame_buffer->data.  I have been writing my own accessors but I realised I am just duplicating existing TVB accessors.  I’ve looked through README.dissector which describes in detail how to use the TVB accessors, but not about creating a TVB.  There is a section on TVBUFF_SUBSET but that doesn’t seem relevant.

 

How do I get the block data into a TVB, preferably without having to copy it?

 

Thanks and regards…Paul

 


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