Wireshark-dev: [Wireshark-dev] Making sure a dissector correctly interprets the extra data pass
On Apr 17, 2016, at 5:33 AM, Peter Wu (Code Review) <code-review-do-not-reply@xxxxxxxxxxxxx> wrote:
> Peter Wu has posted comments on this change.
>
> Change subject: Don't assume the HTTP dissector is being called from the TCP dissector.
> ......................................................................
>
>
> Patch Set 2:
>
> This internal detail unnecessarily changes the external interface. Can't we just check for the parent protocol in the dissect_http?
>
> Change Ib5138d3a082f1017b7ef190e5128a21eb9a49e92 is an example of a test that was adjusted, but I believe that is the wrong fix as it will break all existing configurations.
There is a problem with the current "extra data" mechanism - there's no enforcement. Nothing in the Wireshark core checks whether dissector A is getting the extra data it expects to be passed.
If we decide not to support polymorphism, we need to have some way to ensure that, if dissector A expects to be handled the sort of extra data that dissector B passes to its subdissectors, dissector A is *not* called by any dissectors that *don't* do that.
If we *do* decide to support polymorphism, we should have a standard and convenient way to allow dissector A to determine what type of extra data is being passed to it.
It sounds as if you're advocating polymorphism here. Are you saying that a standard and convenient way to allow a dissector to determine what sort of extra data is being passed to it, by checking the parent protocol? If so, what is it?
