2015-02-17 8:48 GMT+01:00 Vishnu Bhatt <[email protected]>:
> Thanks for the reply. Can you please tell me what is the function of
> p_get_proto_data()
> in Wireshark. Specifically, in case of FP frame, what is the role of this
> function?
>
>
>
> p_fp_info = (fp_info *)p_get_proto_data(wmem_file_scope(), pinfo,
> proto_fp, 0);
>
Hi Vishnu,
you can find a detailed description of those functions in
doc/README.dissector file, chapter 2.5:
2.5 Per-packet information.
Information can be stored for each data packet that is processed by the
dissector. The information is added with the p_add_proto_data function and
retrieved with the p_get_proto_data function. The data pointers passed into
the p_add_proto_data are not managed by the proto_data routines, however the
data pointer memory scope must match that of the scope parameter.
The two most common use cases for p_add_proto_data/p_get_proto_data are for
persistent data about the packet for the lifetime of the capture (file
scope)
and to exchange data between dissectors across a single packet (packet
scope).
It is also used to provide packet data for Decode As dialog (packet scope).
void
p_add_proto_data(wmem_allocator_t *scope, packet_info *pinfo, int proto,
guint32 key, void *proto_data)
void *
p_get_proto_data(wmem_allocator_t *scope, packet_info *pinfo, int proto,
guint32 key)
Where:
scope - Lifetime of the data to be stored, typically
wmem_file_scope()
or pinfo->pool (packet scope). Must match scope of data
allocated.
pinfo - The packet info pointer.
proto - Protocol id returned by the proto_register_protocol call
during initialization
key - key associated with 'proto_data'
proto_data - pointer to the dissector data.
For FP protocol, this is used to store data later used by sub dissectors
like RLC or RRC.
>
>
> Thanks
>
> Vishnu Bhatt
>
>
>
> *From:* [email protected] [mailto:
> [email protected]] *On Behalf Of *Anders Broman
> *Sent:* Monday, February 16, 2015 7:37 PM
>
> *To:* Developer support list for Wireshark
> *Subject:* Re: [Wireshark-dev] function of dissector_try_uint()
>
>
>
>
>
>
>
> *From:* [email protected] [
> mailto:[email protected]
> <[email protected]>] *On Behalf Of *Anders Broman
> *Sent:* den 16 februari 2015 15:05
> *To:* Developer support list for Wireshark
> *Subject:* Re: [Wireshark-dev] function of dissector_try_uint()
>
>
>
>
>
>
>
> *From:* [email protected]
> [mailto:[email protected]] *On Behalf Of *Vishnu Bhatt
> *Sent:* den 16 februari 2015 14:55
> *To:* Developer support list for Wireshark
> *Subject:* [Wireshark-dev] function of dissector_try_uint()
>
>
>
> >Hi,
>
> >
>
> >I have a dissector code (atmii) and I am having problem in understanding
> the following two lines of code:
>
> >
>
> >In proto_register_atmii()
>
> >
>
> >aal_dissector_table = register_dissector_table("atmii.aal2_payload",
> "AAL payload type", FT_UINT8, BASE_DEC);
>
>
>
> Registers a dissector table with the name atmii.aal2_payload in which it
> will be possible to register a callback for an UINT8 value. Compare with
> the UDP table where a dissector can
>
> Register to be called for a message with UDP port number. SIP registers
> for port 5060 for instance.
>
>
>
> and then in dissect_atmii()
>
>
>
> if (!dissector_try_port(aal_dissector_table, payload_type, next_tvb,
> pinfo, tree)) {
>
> proto_tree_add_item(atmii_tree,hf_atmii_aal2_payload, tvb,
> ATM_HEADER_LENGTH, -1, FALSE);
>
> }
>
>
>
> The atmii.aal2_payload table will be searched for a match on payload
> type if a match is found the callback will be executed handing next_tvb to
> the called function.
>
> If no match is found(no dissector registered for the payload type FALSE
> will be returned.
>
>
>
> >What does these two lines of code do in general as I’ve seen them in
> other protocols as well?
>
>
>
> Oh, and you can see who has registered in the table in the Internal menu
> in the main menu bar and with what value.
>
>
>
> Thanks
>
> Vishnu
>
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