Usage of proto_tree_add_item_ret_string() and WMEM

Thank you, it works. In case someone is interested, I paste here the relevant lines :

static int
dissect_rdp_cr(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void* data _U_)
{
    ...
    const guint8 *stringval;
    ...
    proto_tree_add_item_ret_string(tree, hf_rdp_rt_cookie, tvb, offset,
                                   linelen, ENC_ASCII|ENC_NA,
                                   wmem_packet_scope(), &stringval);
    ...
}

with the following declaraction in wmem_scopes.h

WS_DLL_PUBLIC
wmem_allocator_t *
wmem_packet_scope(void);

I don't know exactly, I just need it to be displayed in the column info. Since I don't know what and when is being freed by Wireshark, I can't tell the scope I need.

I've looked in README.wmem but I don't have the necessary experience to choose between packet, file or epan pool. Off the top of my head, I'd say that packet pool, hence wmempacketscope(), is ok. I'd need a clear example to understand the limitations of each pool.

I just need it to be displayed in the column info.

Then you'll probably be doing col_add_str() or col_add_fstr(); neither of those routines keep copies of the string pointers passed to them, so they could be freed at any point, and wmem_packet_scope() would suffice.