写一个can 和canfd 做回环测试的程序

以下是一个简单的 C++ 程序，用于进行 CAN 和 CAN FD 的回环测试：

#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <signal.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/can.h>
#include <linux/can/raw.h>

int s;

void sigterm(int signo)
{
  (void)signo;
  close(s);
  exit(0);
}

int main(int argc, char **argv)
{
  struct can_frame frame;
  struct sockaddr_can addr;
  struct ifreq ifr;
  struct canfd_frame frame_fd;
  struct sockaddr_can addr_fd;
  struct ifreq ifr_fd;
  int nbytes;
  unsigned int can_id = 0x123;
  int i;

  if (argc == 2) {
    s = socket(PF_CAN, SOCK_RAW, CAN_RAW);
    if (s < 0) {
      perror("socket PF_CAN failed");
      return 1;
    }

    strcpy(ifr.ifr_name, argv[1]);
    ioctl(s, SIOCGIFINDEX, &ifr);

    addr.can_family = AF_CAN;
    addr.can_ifindex = ifr.ifr_ifindex;

    if (bind(s, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
      perror("bind failed");
      return 1;
    }

    while(1) {
      nbytes = read(s, &frame, sizeof(struct can_frame));
      if (nbytes < 0) {
        perror("Read");
        return 1;
      }

      printf("CAN ID: 0x%X DLC: %d Data: ", frame.can_id, frame.can_dlc);
      for (i = 0; i < frame.can_dlc; i++)
        printf("%02X ", frame.data[i]);
      printf("\n");

      frame.can_id &= CAN_EFF_MASK;
      frame.can_id |= CAN_EFF_FLAG;
      write(s, &frame, sizeof(struct can_frame));
    }
  } else if (argc == 3) {
    s = socket(PF_CAN, SOCK_RAW, CAN_RAW);
    if (s < 0) {
      perror("socket PF_CAN failed");
      return 1;
    }

    strcpy(ifr.ifr_name, argv[1]);
    ioctl(s, SIOCGIFINDEX, &ifr);

    addr.can_family = AF_CAN;
    addr.can_ifindex = ifr.ifr_ifindex;

    if (bind(s, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
      perror("bind failed");
      return 1;
    }

    s = socket(PF_CAN, SOCK_RAW, CAN_RAW);
    if (s < 0) {
      perror("socket PF_CAN failed");
      return 1;
    }

    strcpy(ifr_fd.ifr_name, argv[2]);
    ioctl(s, SIOCGIFINDEX, &ifr_fd);

    addr_fd.can_family = AF_CAN;
    addr_fd.can_ifindex = ifr_fd.ifr_ifindex;

    if (bind(s, (struct sockaddr *)&addr_fd, sizeof(addr_fd)) < 0) {
      perror("bind failed");
      return 1;
    }

    while(1) {
      nbytes = read(s, &frame_fd, sizeof(struct canfd_frame));
      if (nbytes < 0) {
        perror("Read");
        return 1;
      }

      printf("CAN ID: 0x%X DLC: %d Data: ", frame_fd.can_id, frame_fd.len);
      for (i = 0; i < frame_fd.len; i++)
        printf("%02X ", frame_fd.data[i]);
      printf("\n");

      frame_fd.can_id &= CAN_EFF_MASK;
      frame_fd.can_id |= CAN_EFF_FLAG;
      write(s, &frame_fd, sizeof(struct canfd_frame));
    }
  } else {
    printf("Usage: %s <interface> or %s <interface> <canfd-interface>\n", argv[0], argv[0]);
    return 1;
  }

  return 0;
}

使用方法：

1. 单独使用 CAN：

   $ ./can_loopback can0

将 can0 接口连接在回环模式下。程序将读取每个收到的帧并将其发送回去。

2. 使用 CAN 和 CAN FD：

   $ ./can_loopback can0 can1

将 can0 接口连接到 CAN FD 节点 can1。程序将读取每个收到的 CAN FD 帧并将其发送回去。

注意：使用此程序需要 root 权限。