linux内核源码实战_3.3理解中断和网络

linux内核源码实战_理解中断和网络

前面的博客我只是对知识点的整理， 没有对知识点进行理解， 准备从实战方面入手去理解中断和网络。

体验课(Linux内核源码/内存调优/文件系统/进程管理/设备驱动/网络协议栈)学习视频链接地址　
正课学习视频链接地址
第二个链接是我学习的链接，如果你有兴趣学习，我可以为你推荐，老学员推荐新学员会有相应的折扣 我的QQ号码: 852897652.

以前学习整理的
整理知识点 进程管理和内存管理 链接1。
整理知识点 设备驱动和文件系统 链接2。
整理知识点 中断和网络 链接3。
整理知识点 内核实战 链接3

理解中断和网络

第031讲 套接字及分层模型
netlink

理解中断和网络详解

第031讲 套接字及分层模型

netlink

/****************************************
* Author: vico
* Date: 2021-06-26
* Filename: netlink_test.c
* Descript: netlink of kernel
* Kernel: 3.10.0-327.22.2.el7.x86_64
* Warning:
******************************************/

#include 
#include 
#include 
#include 
#include 

#define NETLINK_TEST     30
#define MSG_LEN            125
#define USER_PORT        100

MODULE_LICENSE("GPL");
MODULE_AUTHOR("vico");
MODULE_DESCRIPTION("netlink protocol example");

struct sock *nlsk = NULL;
extern struct net init_net;

int send_usrmsg(char *pbuf, uint16_t len)
{
    struct sk_buff *nl_skb;
    struct nlmsghdr *nlh;

    int ret;

    /* 创建sk_buff 空间 */
    nl_skb = nlmsg_new(len, GFP_ATOMIC);
    if(!nl_skb)
    {
        printk("\nError:netlink alloc failure.\n\n");
        return -1;
    }

    /* 设置netlink消息头部 */
    nlh = nlmsg_put(nl_skb, 0, 0, NETLINK_TEST, len, 0);
    if(nlh == NULL)
    {
        printk("\nError:nlmsg_put failaure. \n\n");
        nlmsg_free(nl_skb);
        return -1;
    }

    /* 拷贝数据发送 */
    memcpy(nlmsg_data(nlh), pbuf, len);
    ret = netlink_unicast(nlsk, nl_skb, USER_PORT, MSG_DONTWAIT);

    return ret;
}

static void netlink_rcv_msg(struct sk_buff *skb)
{
    struct nlmsghdr *nlh = NULL;
    char *umsg = NULL;
    char *kmsg = "Hello vico users program.";

    if(skb->len >= nlmsg_total_size(0))
    {
        nlh = nlmsg_hdr(skb);
        umsg = NLMSG_DATA(nlh);
        if(umsg)
        {
            printk("kernel recv from user: %s\n", umsg);
            send_usrmsg(kmsg, strlen(kmsg));
        }
    }
}

struct netlink_kernel_cfg cfg = {
        .input  = netlink_rcv_msg, /* set recv callback */
};

int test_netlink_init(void)
{
    /* create netlink socket */
    nlsk = (struct sock *)netlink_kernel_create(&init_net, NETLINK_TEST, &cfg);
    if(nlsk == NULL)
    {
        printk("\nError:netlink_kernel_create error !\n");
        return -1;
    }
    printk("\ntest_netlink_init\n");

    return 0;
}

void test_netlink_exit(void)
{
    if (nlsk){
        netlink_kernel_release(nlsk); /* release ..*/
        nlsk = NULL;
    }
    printk("test_netlink_exit!\n");
}

module_init(test_netlink_init);
module_exit(test_netlink_exit);

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#define NETLINK_TEST    30
#define MSG_LEN         125
#define MAX_PLOAD       125

typedef struct _user_msg_info
{
    struct nlmsghdr hdr;
    char  msg[MSG_LEN];
} user_msg_info;

int main(int argc, char **argv)
{
    int skfd;
    int ret;
    user_msg_info u_info;
    socklen_t len;
    struct nlmsghdr *nlh = NULL;
    struct sockaddr_nl saddr, daddr;
    char *umsg = "Hello Netlink protocol.";

    /* 创建NETLINK socket */
    skfd = socket(AF_NETLINK, SOCK_RAW, NETLINK_TEST);
    if(skfd == -1)
    {
        perror("\nError:Create socket error.\n");
        return -1;
    }

    memset(&saddr, 0, sizeof(saddr));
    saddr.nl_family = AF_NETLINK; //AF_NETLINK
    saddr.nl_pid = 100;  //端口号(port ID)
    saddr.nl_groups = 0;
    if(bind(skfd, (struct sockaddr *)&saddr, sizeof(saddr)) != 0)
    {
        perror("\nError:bind() error.\n");
        close(skfd);
        return -1;
    }

    memset(&daddr, 0, sizeof(daddr));
    daddr.nl_family = AF_NETLINK;
    daddr.nl_pid = 0; // to kernel
    daddr.nl_groups = 0;

    nlh = (struct nlmsghdr *)malloc(NLMSG_SPACE(MAX_PLOAD));
    memset(nlh, 0, sizeof(struct nlmsghdr));
    nlh->nlmsg_len = NLMSG_SPACE(MAX_PLOAD);
    nlh->nlmsg_flags = 0;
    nlh->nlmsg_type = 0;
    nlh->nlmsg_seq = 0;
    nlh->nlmsg_pid = saddr.nl_pid; //self port

    memcpy(NLMSG_DATA(nlh), umsg, strlen(umsg));
    ret = sendto(skfd, nlh, nlh->nlmsg_len, 0, (struct sockaddr *)&daddr, sizeof(struct sockaddr_nl));
    if(!ret)
    {
        perror("\nError:sendto error.\n");
        close(skfd);
        exit(-1);
    }
    printf("\nApplication-->Send kernel:%s\n\n", umsg);

    memset(&u_info, 0, sizeof(u_info));
    len = sizeof(struct sockaddr_nl);
    ret = recvfrom(skfd, &u_info, sizeof(user_msg_info), 0, (struct sockaddr *)&daddr, &len);
    if(!ret)
    {
        perror("\nError:recv form kernel error.\n");
        close(skfd);
        exit(-1);
    }

    printf("\nApplication-->From kernel:%s\n\n", u_info.msg);
    close(skfd);

    free((void *)nlh);
    return 0;
}

总结

太花时间，原谅我，留着后面理解------