Two small problems with libpcap
kaber at trash.net
Wed Nov 24 12:50:29 UTC 2010
On 23.11.2010 23:32, Erik Tews wrote:
> I spotted two small problems with libpcap:
> * Preables for received PP frames are missing, the dedected.org
> tools used to include the preamble as well. This can easily be
> fixed by adding a default preamble if the kernel doesn't report
> the preamble to the userspace.
I guess the kernel should report it, at least with double simplex
bearers the sender can't be determined based on the slot number.
> * The slottime wraps around at 2^12 and not at 2^11 as it used to
> wrap around with the dedected.org tools. I am not sure about the
> best solution here, one could also use the full 16 bits for the
> time which are available in the header.
I'm not sure what you're referring to here. The slot numbers are in
the range of 0-23.
Generally I think the header format should be revamped:
- we don't need the fake ethernet addresses
- the preamble should use 5 bytes for the case of a prolonged
- the RSSI shouldn't use the raw COA values but defined units
- the multiframe number should be added
- the RF-band and/or specific frequency should be added. Using
the RF-band is probably the more flexible way.
- drift for received packets could be added
additionally we could optionally ignore S-field errors in the driver
and indicate them in the frame header.
The easiest way to make these changes is probably to add a new
link type for the new header and have wireshark etc. deal with
More information about the linux-dect