// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *      cn_test.c
 * 
 * 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
 * All rights reserved.
 */

#define pr_fmt(fmt) "cn_test: " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/timer.h>

#include <linux/connector.h>

static struct cb_id cn_test_id = { CN_NETLINK_USERS + 3, 0x456 };
static char cn_test_name[] = "cn_test";
static struct sock *nls;
static struct timer_list cn_test_timer;

static void cn_test_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
{
        pr_info("%s: %lu: idx=%x, val=%x, seq=%u, ack=%u, len=%d: %s.\n",
                __func__, jiffies, msg->id.idx, msg->id.val,
                msg->seq, msg->ack, msg->len,
                msg->len ? (char *)msg->data : "");
}

/*
 * Do not remove this function even if no one is using it as
 * this is an example of how to get notifications about new
 * connector user registration
 */
#if 0
static int cn_test_want_notify(void)
{
        struct cn_ctl_msg *ctl;
        struct cn_notify_req *req;
        struct cn_msg *msg = NULL;
        int size, size0;
        struct sk_buff *skb;
        struct nlmsghdr *nlh;
        u32 group = 1;

        size0 = sizeof(*msg) + sizeof(*ctl) + 3 * sizeof(*req);

        size = NLMSG_SPACE(size0);

        skb = alloc_skb(size, GFP_ATOMIC);
        if (!skb) {
                pr_err("failed to allocate new skb with size=%u\n", size);
                return -ENOMEM;
        }

        nlh = nlmsg_put(skb, 0, 0x123, NLMSG_DONE, size - sizeof(*nlh), 0);
        if (!nlh) {
                kfree_skb(skb);
                return -EMSGSIZE;
        }

        msg = nlmsg_data(nlh);

        memset(msg, 0, size0);

        msg->id.idx = -1;
        msg->id.val = -1;
        msg->seq = 0x123;
        msg->ack = 0x345;
        msg->len = size0 - sizeof(*msg);

        ctl = (struct cn_ctl_msg *)(msg + 1);

        ctl->idx_notify_num = 1;
        ctl->val_notify_num = 2;
        ctl->group = group;
        ctl->len = msg->len - sizeof(*ctl);

        req = (struct cn_notify_req *)(ctl + 1);

        /*
         * Idx.
         */
        req->first = cn_test_id.idx;
        req->range = 10;

        /*
         * Val 0.
         */
        req++;
        req->first = cn_test_id.val;
        req->range = 10;

        /*
         * Val 1.
         */
        req++;
        req->first = cn_test_id.val + 20;
        req->range = 10;

        NETLINK_CB(skb).dst_group = ctl->group;
        //netlink_broadcast(nls, skb, 0, ctl->group, GFP_ATOMIC);
        netlink_unicast(nls, skb, 0, 0);

        pr_info("request was sent: group=0x%x\n", ctl->group);

        return 0;
}
#endif

static u32 cn_test_timer_counter;
static void cn_test_timer_func(struct timer_list *unused)
{
        struct cn_msg *m;
        char data[32];

        pr_debug("%s: timer fired\n", __func__);

        m = kzalloc(sizeof(*m) + sizeof(data), GFP_ATOMIC);
        if (m) {

                memcpy(&m->id, &cn_test_id, sizeof(m->id));
                m->seq = cn_test_timer_counter;
                m->len = sizeof(data);

                m->len =
                    scnprintf(data, sizeof(data), "counter = %u",
                              cn_test_timer_counter) + 1;

                memcpy(m + 1, data, m->len);

                cn_netlink_send(m, 0, 0, GFP_ATOMIC);
                kfree(m);
        }

        cn_test_timer_counter++;

        mod_timer(&cn_test_timer, jiffies + msecs_to_jiffies(1000));
}

static int cn_test_init(void)
{
        int err;

        err = cn_add_callback(&cn_test_id, cn_test_name, cn_test_callback);
        if (err)
                goto err_out;
        cn_test_id.val++;
        err = cn_add_callback(&cn_test_id, cn_test_name, cn_test_callback);
        if (err) {
                cn_del_callback(&cn_test_id);
                goto err_out;
        }

        timer_setup(&cn_test_timer, cn_test_timer_func, 0);
        mod_timer(&cn_test_timer, jiffies + msecs_to_jiffies(1000));

        pr_info("initialized with id={%u.%u}\n",
                cn_test_id.idx, cn_test_id.val);

        return 0;

      err_out:
        if (nls && nls->sk_socket)
                sock_release(nls->sk_socket);

        return err;
}

static void cn_test_fini(void)
{
        timer_delete_sync(&cn_test_timer);
        cn_del_callback(&cn_test_id);
        cn_test_id.val--;
        cn_del_callback(&cn_test_id);
        if (nls && nls->sk_socket)
                sock_release(nls->sk_socket);
}

module_init(cn_test_init);
module_exit(cn_test_fini);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
MODULE_DESCRIPTION("Connector's test module");