帮我用C写一段CANopen SDO收发函数

以下是一个简单的CANopen SDO收发函数的示例代码，使用了SocketCAN库实现CAN总线通信。代码中使用了SDO客户端和服务器的标准COB ID。

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <net/if.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <linux/can.h>
#include <linux/can/raw.h>

#define CAN_INTERFACE "can0"   // CAN接口名称
#define SDO_CLIENT_COB_ID 0x600 // SDO客户端COB ID
#define SDO_SERVER_COB_ID 0x580 // SDO服务器COB ID

int can_socket;

// 初始化CAN总线套接字
int init_can_socket()
{
    struct sockaddr_can addr;
    struct ifreq ifr;

    // 创建socket
    if ((can_socket = socket(PF_CAN, SOCK_RAW, CAN_RAW)) == -1)
    {
        perror("socket");
        return -1;
    }

    // 设置CAN接口
    strcpy(ifr.ifr_name, CAN_INTERFACE);
    ioctl(can_socket, SIOCGIFINDEX, &ifr);
    addr.can_family = AF_CAN;
    addr.can_ifindex = ifr.ifr_ifindex;

    // 绑定socket
    if (bind(can_socket, (struct sockaddr *)&addr, sizeof(addr)) == -1)
    {
        perror("bind");
        close(can_socket);
        return -1;
    }

    return 0;
}

// 发送SDO请求
int send_sdo_request(uint8_t *data, uint8_t len, uint16_t index, uint8_t subindex)
{
    struct can_frame frame;
    int nbytes;

    // 填充CAN帧
    frame.can_id = SDO_CLIENT_COB_ID;
    frame.can_dlc = 8;
    frame.data[0] = 0x22; // 客户端请求SDO下载
    frame.data[1] = (index >> 0) & 0xFF;
    frame.data[2] = (index >> 8) & 0xFF;
    frame.data[3] = subindex;
    frame.data[4] = len;
    memcpy(&frame.data[5], data, len);

    // 发送CAN帧
    nbytes = write(can_socket, &frame, sizeof(struct can_frame));
    if (nbytes != sizeof(struct can_frame))
    {
        perror("write");
        return -1;
    }

    return 0;
}

// 接收SDO响应
int recv_sdo_response(uint8_t *data, uint8_t *len)
{
    struct can_frame frame;
    int nbytes;

    // 循环接收CAN帧
    while (1)
    {
        nbytes = read(can_socket, &frame, sizeof(struct can_frame));
        if (nbytes < 0)
        {
            perror("read");
            return -1;
        }
        else if (nbytes == sizeof(struct can_frame))
        {
            // 判断是否为SDO响应帧
            if ((frame.can_id & 0x7FF) == SDO_SERVER_COB_ID)
            {
                // 解析SDO响应
                if ((frame.data[0] & 0xE0) == 0x60) // 服务器响应SDO上传
                {
                    *len = frame.data[0] & 0x1F;
                    memcpy(data, &frame.data[1], *len);
                    return 0;
                }
                else if ((frame.data[0] & 0xE0) == 0x40) // 服务器响应SDO下载
                {
                    return 0;
                }
            }
        }
    }
}

int main()
{
    uint8_t data[4] = {0x01, 0x23, 0x45, 0x67}; // SDO数据
    uint8_t len;                                 // SDO数据长度

    // 初始化CAN总线套接字
    if (init_can_socket() == -1)
    {
        return -1;
    }

    // 发送SDO请求
    if (send_sdo_request(data, 4, 0x1017, 0x01) == -1)
    {
        return -1;
    }

    // 接收SDO响应
    if (recv_sdo_response(data, &len) == -1)
    {
        return -1;
    }

    // 输出SDO响应
    printf("SDO response: ");
    for (int i = 0; i < len; i++)
    {
        printf("%02X ", data[i]);
    }
    printf("\n");

    return 0;
}

请注意，此代码仅供参考，并且可能需要根据您的具体应用程序进行修改。