This is a basic Controller Area Network (CAN) infrastructure.

CAN is a serial bus network commonly used in automotive and industrial
control applications.  CAN is exclusively a broadcast network.  Frames
do not have destination addresses and instead have an ID which
identifies the frame (generally the ID identifies the type of data in
the payload of the frame).  Nodes can selectively receive frames based
on their ID (using mask and match bits).

Since CAN is a network, CAN controller drivers are implemented as
network devices with a few extras provided by a CAN class device.  CAN
frame aren't a whole number of octets so the user recv()'s and send()'s
'struct can_frame's which include all the header bits and the 8 octets
of payload.

This infrastructure provides the bare minimum required to test CAN
controllers and is likely missing stuff necessary to actually use it in
an application.  In particular, the requirement that frames are sent via
a packet(7) socket could do with being removed but I'm unclear on a
method that would allow this but wouldn't be a security risk (e.g., a
mechanism needs to be provided so you can't send/receive raw CAN frames
on, say, an ethernet device).

David Vrabel
-- 
David Vrabel, Design Engineer

Arcom, Clifton Road           Tel: +44 (0)1223 411200 ext. 3233
Cambridge CB1 7EA, UK         Web: http://www.arcom.com/