Re: Extra DLT types required for opensolaris DLPI DL

[Sebastien Roy <Sebastien.Roy () Sun COM>]

Hi Darren,

On Fri, 2009-03-27 at 10:58 -0700, Darren Reed wrote:
> Additionally, I'm considering creating a new datalink type for loopback 
> packets on OpenSolaris. The contents would be something like:
> version (16 bits: 1)
> protocol family (16 bits: AF_INET, AF_INET6)
> capture point (32bits enum: local, in, out)
> interface index (32bits)
> group interface index (32bits)
> source zone (32 or 64bits?)
> destination zone (32 or 64bits?)
> I'm guessing that this should be called DLT_LOOP_SOLARIS.

There is already a datalink type associated with loopback (/dev/lo0),
DL_IPNET, and the header is described in the lo0(7D) man page.  It's
versioned, so it would be technically possible to evolve it to include
more information.

The only hitch is that DL_IPNET devices behave like DLT_RAW by default.
The DL_IOC_IPNET_INFO ioctl enables the inclusion of the "ipnet" header.
The thinking here was that with a tiny modification to libpcap, existing
applications that understand DLT_RAW could read packets off of DL_IPNET
devices.  The downside is that we now can't really have libpcap turn on
DL_IOC_IPNET_INFO if such applications assume that these devices are
DLT_RAW.  Perhaps it would be simpler if we got rid of DL_IOC_IPNET_INFO
and had DL_IPNET devices always include the header.  Since the
Solaris-specific snoop application is the only thing that currently uses
the ioctl, it's a change that could be manageable.  This is something
we'd need to discuss with the OpenSolaris networking community first,
though.

-Seb


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