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94 lines
3.8 KiB
94 lines
3.8 KiB
import socket
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import struct
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# /**
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# * struct canfd_frame - CAN flexible data rate frame structure
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# * @can_id: CAN ID of the frame and CAN_*_FLAG flags, see canid_t definition
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# * @len: frame payload length in byte (0 .. CANFD_MAX_DLEN)
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# * @flags: additional flags for CAN FD
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# * @__res0: reserved / padding
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# * @__res1: reserved / padding
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# * @data: CAN FD frame payload (up to CANFD_MAX_DLEN byte)
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# */
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# struct canfd_frame {
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# canid_t can_id; /* 32 bit CAN_ID + EFF/RTR/ERR flags */
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# __u8 len; /* frame payload length in byte */
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# __u8 flags; /* additional flags for CAN FD */
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# __u8 __res0; /* reserved / padding */
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# __u8 __res1; /* reserved / padding */
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# __u8 data[CANFD_MAX_DLEN] __attribute__((aligned(8)));
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# };
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CAN_HEADER_FMT = "=IBB2x"
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CAN_HEADER_LEN = struct.calcsize(CAN_HEADER_FMT)
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CAN_MAX_DLEN = 8
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CANFD_MAX_DLEN = 64
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CANFD_BRS = 0x01 # bit rate switch (second bitrate for payload data)
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CANFD_FDF = 0x04 # mark CAN FD for dual use of struct canfd_frame
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# socket.SO_RXQ_OVFL is missing
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# https://github.com/torvalds/linux/blob/47ac09b91befbb6a235ab620c32af719f8208399/include/uapi/asm-generic/socket.h#L61
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SO_RXQ_OVFL = 40
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def create_socketcan(interface:str, recv_buffer_size:int, fd:bool) -> socket.socket:
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# settings mostly from https://github.com/linux-can/can-utils/blob/master/candump.c
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socketcan = socket.socket(socket.AF_CAN, socket.SOCK_RAW, socket.CAN_RAW)
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if fd:
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socketcan.setsockopt(socket.SOL_CAN_RAW, socket.CAN_RAW_FD_FRAMES, 1)
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socketcan.setsockopt(socket.SOL_SOCKET, socket.SO_RCVBUF, recv_buffer_size)
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# TODO: why is it always 2x the requested size?
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assert socketcan.getsockopt(socket.SOL_SOCKET, socket.SO_RCVBUF) == recv_buffer_size * 2
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# TODO: how to dectect and alert on buffer overflow?
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socketcan.setsockopt(socket.SOL_SOCKET, SO_RXQ_OVFL, 1)
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socketcan.bind((interface,))
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return socketcan
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# Panda class substitute for socketcan device (to support using the uds/iso-tp/xcp/ccp library)
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class SocketPanda():
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def __init__(self, interface:str="can0", bus:int=0, fd:bool=False, recv_buffer_size:int=212992) -> None:
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self.interface = interface
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self.bus = bus
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self.fd = fd
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self.flags = CANFD_BRS | CANFD_FDF if fd else 0
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self.data_len = CANFD_MAX_DLEN if fd else CAN_MAX_DLEN
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self.recv_buffer_size = recv_buffer_size
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self.socket = create_socketcan(interface, recv_buffer_size, fd)
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def __del__(self):
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self.socket.close()
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def get_serial(self) -> tuple[int, int]:
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return (0, 0) # TODO: implemented in panda socketcan driver
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def get_version(self) -> int:
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return 0 # TODO: implemented in panda socketcan driver
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def can_clear(self, bus:int) -> None:
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# TODO: implemented in panda socketcan driver
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self.socket.close()
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self.socket = create_socketcan(self.interface, self.recv_buffer_size, self.fd)
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def set_safety_mode(self, mode:int, param=0) -> None:
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pass # TODO: implemented in panda socketcan driver
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def has_obd(self) -> bool:
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return False # TODO: implemented in panda socketcan driver
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def can_send(self, addr, dat, bus=0, timeout=0) -> None:
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msg_len = len(dat)
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msg_dat = dat.ljust(self.data_len, b'\x00')
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can_frame = struct.pack(CAN_HEADER_FMT, addr, msg_len, self.flags) + msg_dat
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self.socket.sendto(can_frame, (self.interface,))
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def can_recv(self) -> list[tuple[int, bytes, int]]:
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msgs = list()
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while True:
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try:
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dat, _ = self.socket.recvfrom(self.recv_buffer_size, socket.MSG_DONTWAIT)
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assert len(dat) == CAN_HEADER_LEN + self.data_len, f"ERROR: received {len(dat)} bytes"
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can_id, msg_len, _ = struct.unpack(CAN_HEADER_FMT, dat[:CAN_HEADER_LEN])
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msg_dat = dat[CAN_HEADER_LEN:CAN_HEADER_LEN+msg_len]
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msgs.append((can_id, msg_dat, self.bus))
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except BlockingIOError:
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break # buffered data exhausted
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return msgs
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