SO2.lab10.zad1.netlink

#include<linux/init.h>
#include<linux/module.h>
#include<linux/fs.h>
#include<linux/seq_file.h>
#include<linux/proc_fs.h>
#include<linux/netlink.h>
#include<net/netlink.h>
#include<net/sock.h>

#define NETLINK_TEST 17

static int error_level;
static char content[128];
static struct sock *sock;

static int netlink_show(struct seq_file *seq, void *v)
{
    seq_printf(seq,content);
    return 0;
}

static int netlink_seq_open(struct inode *inode, struct file *file)
{
    return single_open(file,netlink_show,NULL);
}

static struct file_operations netlink_proc_fops = {
    .owner = THIS_MODULE,
    .open = netlink_seq_open,
    .read = seq_read,
    .llseek = seq_lseek,
    .release = single_release,
};

static void netlink_receive_skb(struct sk_buff *skb)
{
    struct nlmsghdr *nlh;
    uint32_t rlen;

    nlh = nlmsg_hdr(skb);
    rlen = NLMSG_ALIGN(nlh->nlmsg_len);
    sprintf(content,"Received message: \"%s\", sequence number: %u\n",(char *)NLMSG_DATA(nlh),nlh->nlmsg_seq);
    skb_pull(skb,rlen);
}

static struct netlink_kernel_cfg netlink_configuration = {
    .groups = 0,
    .input = netlink_receive_skb,
    .cb_mutex = NULL,
    .compare = NULL,
};

static int __init netlink_start(void)
{
    if(proc_create("netlink",0,NULL,&netlink_proc_fops)==NULL) {
        printk(KERN_ALERT "Error creating procfs entry!\n");
        error_level=1;
        return -1;
    }
    sock = netlink_kernel_create(&init_net,NETLINK_TEST, &netlink_configuration);
    if(!sock) {
        printk(KERN_ALERT "Error creating netlink socket!\n");
        error_level=2;
        return -2;
    }
    return 0;
}

static void __exit netlink_stop(void)
{
    if(error_level!=1)
        remove_proc_entry("netlink",NULL);
    if(error_level!=2)
        netlink_kernel_release(sock);
}

module_init(netlink_start);
module_exit(netlink_stop);
MODULE_LICENSE("GPL");