Class CANFD

scapy/layers/can.py:175–210

This class is used for distinction of CAN FD packets.

class CANFD(CAN):
    """
    This class is used for distinction of CAN FD packets.
    """
    fields_desc = [
        FlagsField('flags', 0, 3, ['error',
                                   'remote_transmission_request',
                                   'extended']),
        XBitField('identifier', 0, 29),
        FieldLenField('length', None, length_of='data', fmt='B'),
        FlagsField('fd_flags', 4, 8, ['bit_rate_switch',
                                      'error_state_indicator',
                                      'fd_frame']),
        ShortField('reserved', 0),
        StrLenField('data', b'', length_from=lambda pkt: int(pkt.length)),
    ]

    def post_build(self, pkt, pay):
        # type: (bytes, bytes) -> bytes

        data = super(CANFD, self).post_build(pkt, pay)

        length = data[4]

        if 8 < length <= 24:
            wire_length = length + (-length) % 4
        elif 24 < length <= 64:
            wire_length = length + (-length) % 8
        elif length > 64:
            raise NotImplementedError
        else:
            wire_length = length

        pad = b"\x00" * (wire_length - length)

        return data[0:4] + chb(wire_length) + data[5:] + pad


bind_layers(CookedLinux, CANFD, proto=13)