canbus_query.py

#!/usr/bin/env python2
# Tool to query CAN bus uuids
#
# Copyright (C) 2021  Kevin O'Connor <kevin@koconnor.net>
#
# This file may be distributed under the terms of the GNU GPLv3 license.
import sys, os, optparse, time
import can

CANBUS_ID_ADMIN = 0x3f0
CMD_QUERY_UNASSIGNED = 0x00
RESP_NEED_NODEID = 0x20

def query_unassigned(canbus_iface):
    # Open CAN socket
    filters = [{"can_id": CANBUS_ID_ADMIN + 1, "can_mask": 0x7ff,
                "extended": False}]
    bus = can.interface.Bus(channel=canbus_iface, can_filters=filters,
                            bustype='socketcan')
    # Send query
    msg = can.Message(arbitration_id=CANBUS_ID_ADMIN,
                      data=[CMD_QUERY_UNASSIGNED], is_extended_id=False)
    bus.send(msg)
    # Read responses
    found_ids = {}
    start_time = curtime = time.time()
    while 1:
        tdiff = start_time + 2. - curtime
        if tdiff <= 0.:
            break
        msg = bus.recv(tdiff)
        curtime = time.time()
        if (msg is None or msg.arbitration_id != CANBUS_ID_ADMIN + 1
            or msg.dlc < 7 or msg.data[0] != RESP_NEED_NODEID):
            continue
        uuid = sum([v << ((5-i)*8) for i, v in enumerate(msg.data[1:7])])
        if uuid in found_ids:
            continue
        found_ids[uuid] = 1
        sys.stdout.write("Found canbus_uuid=%012x\n" % (uuid,))
    sys.stdout.write("Total %d uuids found\n" % (len(found_ids,)))

def main():
    usage = "%prog [options] <can interface>"
    opts = optparse.OptionParser(usage)
    options, args = opts.parse_args()
    if len(args) != 1:
        opts.error("Incorrect number of arguments")
    canbus_iface = args[0]
    query_unassigned(canbus_iface)

if __name__ == '__main__':
    main()