def decode_frame(self, msg):
if len(msg) < self.MIN_MSG_LEN:
return None
cmd, msg = msg[0], msg[1:]
if cmd == 'T':
extended = True
id_len = 8
elif cmd == 't':
extended = False
id_len = 3
else:
return None
if len(msg) < id_len + 1:
return None
can_id = int(msg[0:id_len], 16)
msg = msg[id_len:]
data_len = int(msg[0])
msg = msg[1:]
if len(msg) < 2 * data_len:
return None
data = [int(msg[i:i + 2], 16) for i in range(0, 2 * data_len, 2)]
return can.Frame(id=can_id,
data=bytearray(data),
data_length=data_len,
extended=extended)
def test_drop_extended_frames(self):
"""
Checks that we drop extended frames
"""
data = 'Hello world'.encode('ascii')
# Encapsulates it in a CAN datagram
data = can.encode_datagram(data, destinations=[1])
# Slice the datagram in frames
frames = list(can.datagram_to_frames(data, source=42))
# Add an extended frame, with an annoying ID
id = frames[0].id
frames = [can.Frame(extended=True, data=bytes([1, 2, 3]), id=id)
] + frames
# Prepares a pseudo CAN adapter
fdesc = Mock()
fdesc.receive_frame.side_effect = frames
reader = read_can_datagrams(fdesc)
# Read a CAN datagram from that pseudofile
dt, dst, src = next(reader)
self.assertEqual(dt.decode('ascii'), 'Hello world')
self.assertEqual(dst, [1])
self.assertEqual(src, 42)
def receive_frame(self):
try:
frame, _ = self.socket.recvfrom(self.CAN_FRAME_SIZE)
except socket.timeout:
return None
can_id, can_dlc, data = struct.unpack(self.CAN_FRAME_FMT, frame)
return can.Frame(id=can_id, data=data[:can_dlc])
def rx_handler(self, msg):
rec = self.cvra_can.Frame.decode(msg[0])
if rec.can_id.extended:
return
frame = can.Frame(id=rec.can_id.value,
data=rec.data,
extended=rec.can_id.extended,
transmission_request=rec.can_id.remote,
data_length=len(rec.data))
self.rx_queue.put(frame)