From: [email protected] 
[mailto:[email protected]] On Behalf Of Vishnu Bhatt
Sent: den 10 januari 2014 10:54
To: Developer support list for Wireshark
Subject: Re: [Wireshark-dev] Siginificance of pinfo->fd->flags.visited

Thanks for the explanation.


  1.  << The result of a packet dissection is thrown away as soon as the packet 
has been read and presented, so if you 'click' on a new packet the dissection 
has to be redone.>>

>"Thrown away" means it's not stored anywhere. Am I right? If yes, why is it 
>thrown away?

As its not needed as the packet will be re dissected when the information is 
needed again. Saving the dissection result for every packet in a trace would 
require a lot of (RAM)memory.
(number of bytes times a factor > 10?)

>And also, few things are done only once using "flags.visited == FALSE", why 
>then this variable is used, if the previous results are not stored, then 
>everything has to be redone.

Perhaps I expressed that poorly, if you need some result of the dissection you 
need to arrange to store it and protect that code with "flags.visited" to have 
it only executed once - the first time
When the packets are executed in order.


  1.  << Not sure what you are referring to here >>
>In packet-rlc.c in epan/dissectors, duplicity of RLC frames is checked, should 
>that be done everytime?

No it should probably only be done once and the result saved.

Regards
Anders

________________________________
From: 
[email protected]<mailto:[email protected]> 
[mailto:[email protected]] On Behalf Of Anders Broman
Sent: Friday, January 10, 2014 2:53 PM
To: Developer support list for Wireshark
Subject: Re: [Wireshark-dev] Siginificance of pinfo->fd->flags.visited



From: 
[email protected]<mailto:[email protected]> 
[mailto:[email protected]] On Behalf Of Vishnu Bhatt
Sent: den 10 januari 2014 08:59
To: [email protected]<mailto:[email protected]>
Subject: [Wireshark-dev] Siginificance of pinfo->fd->flags.visited

>Hello all,
>
>Can anyone please explain me the significance of pinfo->fd->flags.visited. I 
>know that this variable is set to TRUE if a packet has been visited once but 
>if we click on the same packet then why all things are done again?

pinfo->fd->flags.visited is FALSE on the first pass when all packets are read 
in sequence then it's set to FALSE. The result of a packet dissection is thrown 
away as soon as the packet has been read and presented, so if you 'click' on a 
new packet the dissection has to be redone.

>
>Logically if a frame has been dissected once, it should not be checked again, 
>so condition "if(pinfo->fd->flags.visited == FALSE)" should always be checked 
>before doing the dissection.
No true see above.

>Why the need of re-dissecting >the frame over and over again?

See above.

>My second doubt is that in RLC, if duplicity has already been checked then why 
>to check it again? I mean should the duplicity function be covered under 
>"if(pinfo->fd->flags.visited == FALSE)"?


Not sure what you are referring to here...

Thanks
Vishnu Bhatt




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