Re: libpcap patches for DLT_SITA support

[Guy Harris <guy () alum mit edu>]

Fulko Hew wrote:
> On 8/21/07, Guy Harris <guy () alum mit edu> wrote:
> > 1) Files added to INSTALL.txt also need to be added to FILES.
>
> Opps, sorry, I forgot about that file (I thought I caught them all).
> Do you want me to submit a new patch file with that added?

If you make any other changes, as per the suggestions below, also change 
FILES in the new patch.

> > Perhaps there should be a separate document that describes how the ACN
> > version of libpcap differs from the standard one.
>
> Thats what that document does.

It also duplicates what's in pcap.3; the problem is that changes to 
pcap.3 might render the duplicated stuff out of date.

A document that assumes the reader has already read the libpcap man 
page, and just explains what's different about the ACN version, might 
require less maintenance.

> > It sounds as if IOP-type devices have names with
> > a particular format that isn't likely to match the name of a regular
> > Linux networking device, so it should, I think, be possible to support
> > both.
>
> You are correct, I intentionally tried to ensure that my naming
> convention was different than that of the other OS I was aware of...

Then, in that case, one version of libpcap could handle both.

> So the usual time/budget constraints made me separate the two
> functionalities as much as possible.  And... I didn't want to 'polute' the
> pcap-linux.c  file any more than  I had to, so I would not confuse people
> that followed me in non-ACN-land with un-related code.

pcap-linux.c already has extra stuff to check for a variety of optional 
device types; pcap_open_live() would just have

        if (the device looks like an ACN device) {
                return acn_open_live(device, snaplen, promisc, to_ms, ebuf);
        }

added to it, along with all the other checks.

At some point I'll probably look at making it easier to add hooks for 
other device types without modifying pcap_open_live().

That would allow users to build libpcap with ACN support, and (with the 
top-of-tree version, to which the ACN support would be added) install it 
as a shared library, which would mean that applications that can handle 
DLT_SITA would handle your devices *without having to be recompiled*.

If you don't have time to add a check like that, just indicate what 
names it should check for, and I can add that support.
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