关于netlink的使用

ID:196356 · 发表于 2017-5-4 09:29

/* file : genl_kernel.c
* kernel module for test genetlink
* sudochen@163.com
*
*/
#include <linux/init.h>
#include <linux/module.h>
#include <net/genetlink.h>
static int cmd_echo(struct sk_buff *skb_2, struct genl_info *info);
enum {
CMD_NONE,
CMD_ECHO,
CMD_MAX
};
static struct genl_family cmd_genl_family = {
.id = GENL_ID_GENERATE,
.hdrsize = 0,
.name = "cmd",
.version = 1,
.maxattr = CMD_MAX,
};
static struct nla_policy cmd_nla_policy[CMD_MAX + 1] = {
[CMD_NONE] = {
.type = NLA_UNSPEC,
},
[CMD_ECHO] = {
.type = NLA_STRING,
.len = 0x100,
},
};
static struct genl_ops cmd_ops[] = {
{
.cmd = CMD_ECHO,
.flags = 0,
.policy = cmd_nla_policy,
.doit = cmd_echo,
.dumpit = NULL,
}
};
static int cmd_echo(struct sk_buff *skb_2, struct genl_info *info)
{
struct nlattr *attr = NULL;
struct sk_buff *skb = NULL;
int ret = -1;
char *data;
char *head;
if (NULL == info) {
return -1;
}
attr = info->attrs[CMD_ECHO];
if (attr) {
data = (char*)nla_data(attr);
if (data) {
printk("genl recv data %s\n",data);
} else {
printk("genl recv data NULL\n");
}
} else {
printk("no attr %d\n",CMD_ECHO);
}
skb = genlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
if (NULL == skb) {
goto out;
}
head = genlmsg_put(skb, 0, info->snd_seq+1,&cmd_genl_family,0,CMD_ECHO);
if (NULL == head) {
goto out;
}
ret = nla_put_string(skb, CMD_ECHO, "hello world form kernel space");
if (ret)
goto out;
genlmsg_end(skb,head);
ret = genlmsg_unicast(&init_net,skb,info->snd_pid);
if (ret)
goto out;
return 0;
out:
printk("genl an error ocured\n");
return -1;
}
int __init cmd_init(void)
{
int error;
error = genl_register_family_with_ops(&cmd_genl_family, cmd_ops, ARRAY_SIZE(cmd_ops));
if (error) {
printk("register family error\n");
return error;
}
printk("register family ok\n");
return 0;
}
void __exit cmd_exit(void)
{
genl_unregister_family(&cmd_genl_family);
printk("unregister family ok\n");
}
MODULE_LICENSE("GPL");
module_init(cmd_init);
module_exit(cmd_exit);

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