On Fri, Feb 22, 2002 at 09:43:58AM -0800, John Polstra wrote:
> In article <[EMAIL PROTECTED]>,
> Joe Eykholt  <[EMAIL PROTECTED]> wrote:
> > 
> > It seems like along with the packet being sent up to bpf, there's
> > a need for some flags that tell tcpdump about the packet.  I haven't
> > looked at the current implementation, but in another system, I found
> > it useful to add a flag indicating whether the packet was being received
> > or transmitted.   
> > 
> > Adding a flag indicating that no checksum generation has been done yet,
> > but will be done by the NIC, would allow tcpdump to also ignore checksum
> > errors on outgoing packets, or it could generate the checksum itself
> > if displaying those bytes (in a hex output, e.g.).
> 
> Remember, bpf is used by many things besides tcpdump.  Adding these
> flags would require extending the bpf API.  They couldn't be added for
> the default case, because that would break compatibility with other
> applications.  They'd have to be enabled specifically, by means of a
> new ioctl.

You could always just add a flags field to struct bpf_hdr, and hope noone 
is stupid enough to hardcode the size.

-- 
Richard A Steenbergen <[EMAIL PROTECTED]>       http://www.e-gerbil.net/ras
PGP Key ID: 0x138EA177  (67 29 D7 BC E8 18 3E DA  B2 46 B3 D8 14 36 FE B6)

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