[NUT-devel] huge vs. damaged forward_ptrs in packets

[Rich Felker]

On Thu, Mar 09, 2006 at 10:39:10AM -0500, Rich Felker wrote:
> You mean just placing the checksum at arbitrary byte positions
> independent of contents? I'm at least mildly against this since it
> seems to complicate the implementation, requiring the data to be
> copied around to make up for the checksums inserted at random
> positions in it before it can be parsed.
> 
> IMO the only piece of data that needs to be protected more than the
> whole-packet checksum is the forward_ptr (otherwise the demuxer may
> read unboundedly into the future trying to verify the whole-packet and
> its checksum). What if, instead of a checksum on the first N bytes of
> a packet when the packet size is >N, we instead do just a checksum on
> startcode+forward_ptr when the packet size is >N? This would eliminate
> the need for buffering to write the data, and would get all the
> benefits of the secondary-checksum (i.e. protecting forward_ptr).

Forget it; Oded just told me that this is what you originally
proposed. :) Sorry I misunderstood. I thought the secondary checksum
was going to cover all bytes in the first N bytes of the packet, not
just the startcode+forward_ptr.

Rich