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 <stdio.h>
#include <stdlib.h>
#include <netlink/netlink.h>
#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 <linux/kernel.h>
#include <linux/module.h>
#include <net/sock.h>
#include <net/netlink.h>
#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
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