通用netlink的基本使用（1） NETLINK_GENERIC

内核部分

#include <net/genetlink.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>

int ctl_test_function(struct sk_buff *skb, struct genl_info *info)
{
    printk("get process pid=%d  cmd=%d pid=%d type=%d\n",info->snd_pid,info->genlhdr->cmd,info->nlhdr->nlmsg_pid,info->nlhdr->nlmsg_type);
    return 0;
}

struct genl_family test_ctl = {
    .id=1023, //消息类型
    .name="testnet",
    .version=0x02,
};

struct genl_ops test_ctl_ops={
    .cmd = 100,//自己先设置一个命令
    .doit = ctl_test_function,
};

static int __init testnlk_init(void)
{
    if(genl_register_family(&test_ctl) != 0)
    {
        printk("register faimly error\n");
        return -1;
    }

    if(genl_register_ops(&test_ctl,&test_ctl_ops) !=  0)
    {
        printk("Register ops error\n");
        goto out;
    }

    return 0;
out:
    genl_unregister_family(&test_ctl);
    return 0;
}

static void __exit testnlk_exit(void)
{
    genl_unregister_ops(&test_ctl,&test_ctl_ops);
    genl_unregister_family(&test_ctl);
}

module_init(testnlk_init);
module_exit(testnlk_exit);
MODULE_LICENSE("GPL");

应用部分

#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <linux/netlink.h>
#include <linux/genetlink.h>

//先只传递消息头没有载荷数据
struct mymsg{
    struct nlmsghdr nhdr;
    struct genlmsghdr  genhdr;
};

int main(int argc,char *argv[])
{
    int skfd;
    struct sockaddr_nl addr={0};
    struct mymsg msg={0};
    int ret;

    skfd = socket(AF_NETLINK,SOCK_RAW,NETLINK_GENERIC);
    if(skfd < 0)
    {
        printf("socket error\n");
        return -1;
    }
    addr.nl_family = AF_NETLINK;
    addr.nl_pid = getpid();

    if(bind(skfd,(struct sockaddr *)&addr,sizeof(addr)) < 0 )
    {
        printf("Bind error\n");
        goto out;
    }

    //设置消息头
    msg.nhdr.nlmsg_type = 1023;  //消息类型
    msg.nhdr.nlmsg_pid = getpid();
    msg.nhdr.nlmsg_flags = NLM_F_REQUEST;
    msg.nhdr.nlmsg_len  = NLMSG_LENGTH(GENL_HDRLEN); //nlmsghdr头长 + gennlmsg头长

    msg.genhdr.cmd = 100; //命令字
    msg.genhdr.version = 0x02;

	 //发送信息到内核
    addr.nl_family = AF_NETLINK;
    addr.nl_pid = 0; 
	
    ret = sendto(skfd,(char*)&msg,msg.nhdr.nlmsg_len,0,(struct sockaddr *)&addr,sizeof(addr));
	if(ret <= 0)
    {
        printf("send error\n");
    }

out:
    close(skfd);
    return 0;
}