Wireshark-dev: Re: [Wireshark-dev] Best algorithmic way to implement MPTCP sequence number spac
You should just be able to call `epan_get_frame_ts` and pass it
`pinfo->epan` plus your frame number.
On Thu, Oct 8, 2015 at 4:26 PM, Matt <mattator@xxxxxxxxx> wrote:
> I managed to get the interval tree working with only a few
> modifications to the core R/B tree.
>
> I now would like to compute the sequence number inter arrival times
> (multipath may provoke more out of order hence it is a metric of
> interest). To do that I need to get access to the time arrival of a
> specific frame (i.e., I know the frame number) from packet-tcp.c.
> For instance I have a packet with Sequence Number (=SN) 100 in packet
> 5 and I know that SN 99 is in packet 2 or in packet 8 (out of order)
> and I would like to compute the delta time of arrival between the 2
> packets.
>
> I found the frame_data_sequence_find() function but it expects a list
> of frames as first parameter. Any idea how to retrieve that list from
> packet-tcp.c ?
>
> Regards
>
>
> 2015-10-02 18:11 GMT+02:00 Matt <mattator@xxxxxxxxx>:
>> Hi,
>>
>> (Question is at the end, I start with an Multipath TCP introduction (MPTCP) ).
>> I would be interested in adding MPTCP sequence number analysis to
>> wireshark, similar to what is done with TCP but taking into account
>> MPTCP specifics:
>> - MPTCP sequence number is 64 bits.
>> - MPTCP uses a global sequence number (SN) space and maps this global
>> SN to a TCP SN. For instance, an MPTCP socket wants to send the bytes
>> 1 to 10. It may send 6 bytes on TCP subflow 1 and the 4 other bytes on
>> another subflow 2. On each subflow (=TCP connection), it will send a
>> mapping (via a TCP option called DSS=Data Sequence Signaling) saying
>> for instance
>> on subflow 1 I map MPTCP global SN 1-6 to local subflow SN 21-26,
>> on subflow 2 I map MPTCP global SN 7-10 to local TCP SN 60-63.
>>
>> Keeping track of those DSS options/mappings would help analyzing the
>> behavior of an MPTCP connection:
>> - does it duplicate some packets over different paths (<=> do some DSS
>> overlap on different subflows?)
>> - it would allow to generate an MPTCP RTT/application latency since
>> striping packets over several paths is likely to increase the
>> application latency
>> - also allow to deduce if we've captured all subflows or if there are
>> holes in the MPTCP sequence number (maybe one subflow was emitting on
>> the wifi interface and we didn't capture it)
>> etc...
>>
>> Now here is my problem: what datastructure should I use to achieve
>> what I previously describe in a way that could be accepted upstream ?
>> or to put it differently how to retrieve a list of ranges (MPTCP start
>> SN and end SN) from another SN range ? The interval tree sounds like a
>> good solution (http://www.geeksforgeeks.org/interval-tree/) but I
>> wonder if there is any advice on an alternate solution ? or ways to
>> build the tree efficiently (like disabling rotations and balancing the
>> tree only at the end or stuff like that, I am not an algorithmic
>> expert).
>>
>> In any case, I plan to add an option to turn this DSS analysis on/off.
>>
>> Regards
>>
>> Matt
> ___________________________________________________________________________
> Sent via: Wireshark-dev mailing list <wireshark-dev@xxxxxxxxxxxxx>
> Archives: https://www.wireshark.org/lists/wireshark-dev
> Unsubscribe: https://wireshark.org/mailman/options/wireshark-dev
> mailto:wireshark-dev-request@xxxxxxxxxxxxx?subject=unsubscribe
