Wireshark · Ethereal-dev: Re: [Ethereal-dev] Unnecessary checks to see if COL_PROTOCOL is being displayed

[Guy Harris <guy@xxxxxxxxxxxx>]

On Thu, Sep 18, 2003 at 12:16:21AM -0700, Richard Sharpe wrote:
> I was documenting some stuff on dissectors when I noticed that pretty much 
> all dissectors have this as the first statement in them:
> 
>         if (check_col(pinfo->cinfo, COL_PROTOCOL))
>                 col_set_str(pinfo->cinfo, COL_PROTOCOL, "POP");
> 
> However, if it is being called to build the protocol tree, should it 
> bother to update the summary pane, as that has most likely already been 
> done.

Yes, because, on the first pass through the packets, if you have a list
of color filters, or have a tap listener, it will be generating summary
pane column text *and* will be constructing the protocol tree; the same
is true if you have a display filter and are applying it.

The summary pane won't get updated if, for example, you've clicked on a
packet, because "check_col(pinfo->cinfo, COL_PROTOCOL)" will return
FALSE.