用户进程与内核进程通信netlink实例

为了方便应用程序使用netlink接口,一个叫libnl库被开发.
1 下载libnl2 
http://packages.ubuntu.com/oneiric/libnl2
2 下载libnl2-dev
http://packages.ubuntu.com/precise/libnl2-dev
3 先安装libnl2 在安装libnl2-dev
 
应用层代码
 
#include
#include
 
#include
 
#define MY_MSG_TYPE (0x10 + 2)  // + 2 is arbitrary but is the same for kern/usr
int
main(int argc, char *argv[])
{
    struct nl_sock *nls;
    char msg[] = { 0xde, 0xad, 0xbe, 0xef, 0x90, 0x0d, 0xbe, 0xef };
    int ret;
 
    nls = nl_socket_alloc();
    if (!nls) {
        printf("bad nl_socket_alloc\n");
        return EXIT_FAILURE;
    }
 
    ret = nl_connect(nls, NETLINK_USERSOCK);
    if (ret < 0) {
        nl_perror(ret, "nl_connect");
        nl_socket_free(nls);
        return EXIT_FAILURE;
    }
 
    ret = nl_send_simple(nls, MY_MSG_TYPE, 0, msg, sizeof(msg));
    if (ret < 0) {
        nl_perror(ret, "nl_send_simple");
        nl_close(nls);
        nl_socket_free(nls);
        return EXIT_FAILURE;
    } else {
        printf("sent %d bytes\n", ret);
    }
 
    nl_close(nls);
    nl_socket_free(nls);
 
    return EXIT_SUCCESS;
}
 
内核代码
 
#include
#include
 
#include
#include
 
#define MY_MSG_TYPE (0x10 + 2)  // + 2 is arbitrary. same value for kern/usr
 
static struct sock *my_nl_sock;
 
DEFINE_MUTEX(my_mutex);
 
static int
my_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
{
    int type;
    char *data;
 
    type = nlh->nlmsg_type;
    if (type != MY_MSG_TYPE) {
        printk("%s: expect %#x got %#x\n", __func__, MY_MSG_TYPE, type);
        return -EINVAL;
    }
 
    data = NLMSG_DATA(nlh);
    printk("%s: x x x x x x x x\n", __func__,
            data[0], data[1], data[2], data[3],
            data[4], data[5], data[6], data[7]);
    return 0;
}
 
static void
my_nl_rcv_msg(struct sk_buff *skb)
{
    mutex_lock(&my_mutex);
    netlink_rcv_skb(skb, &my_rcv_msg);
    mutex_unlock(&my_mutex);
}
 
static int
my_init(void)
{
    my_nl_sock = netlink_kernel_create(&init_net, NETLINK_USERSOCK, 0,
            my_nl_rcv_msg, NULL, THIS_MODULE);
    if (!my_nl_sock) {
        printk(KERN_ERR "%s: receive handler registration failed\n", __func__);
        return -ENOMEM;
    }
 
    return 0;
}
 
static void
my_exit(void)
{
    if (my_nl_sock) {
        netlink_kernel_release(my_nl_sock);
    }
}
 
module_init(my_init);
module_exit(my_exit);
 
 
系统:ubuntu 10.04 ,内核: linux-2.6.38
编译应用层代码需要加入动态链接库 /usr/lib/libnl.so
即sudo gcc -o 1 1.c /usr/lib/libnl.so
 

转载于:https://www.cnblogs.com/kungfupanda/archive/2013/01/11/2856973.html

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