/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2023 Baptiste Daroussin <bapt@FreeBSD.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/types.h>
#include <sys/devctl.h>
#include <sys/errno.h>
#include <sys/module.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <net/vnet.h>
#include <netlink/netlink.h>
#include <netlink/netlink_ctl.h>
#include <netlink/netlink_generic.h>
#include <netlink/netlink_sysevent.h>

#define DEBUG_MOD_NAME  nl_sysevent
#define DEBUG_MAX_LEVEL LOG_DEBUG3
#include <netlink/netlink_debug.h>
_DECLARE_DEBUG(LOG_INFO);

MALLOC_DEFINE(M_NLSE, "nlsysevent", "Memory used for Netlink sysevent");
#define NLSE_FAMILY_NAME        "nlsysevent"
static uint16_t ctrl_family_id;

#define MAX_SYSEVENT_GROUPS     64
static struct sysevent_group {
        char *name;
        uint32_t id;
} sysevent_groups[MAX_SYSEVENT_GROUPS] = {};

static const char *devctl_systems[] = {
        "ACPI",
        "AEON",
        "CAM",
        "CARP",
        "coretemp",
        "DEVFS",
        "device",
        "ETHERNET",
        "GEOM",
        "HYPERV_NIC_VF",
        "IFNET",
        "INFINIBAND",
        "KERNEL",
        "nvme",
        "PMU",
        "RCTL",
        "USB",
        "VFS",
        "VT",
        "ZFS",
};

static void
sysevent_write(struct sysevent_group *se, const char *subsystem, const char *type,
    const char *data)
{
        struct nl_writer nw;

        if (!nl_writer_group(&nw, NLMSG_LARGE, NETLINK_GENERIC, se->id, 0,
            false)) {
                NL_LOG(LOG_DEBUG, "error allocating group writer");
                return;
        }
        struct nlmsghdr hdr = { .nlmsg_type = ctrl_family_id };
        if (!nlmsg_reply(&nw, &hdr, sizeof(struct genlmsghdr))) {
                return;
        }

        struct genlmsghdr *ghdr = nlmsg_reserve_object(&nw, struct genlmsghdr);
        if (ghdr == NULL) {
                NL_LOG(LOG_DEBUG, "unable to allocate memory");
                return;
        }
        ghdr->version = 0;
        ghdr->cmd = NLSE_CMD_NEWEVENT;
        ghdr->reserved = 0;
        nlattr_add_string(&nw, NLSE_ATTR_SYSTEM, se->name);
        nlattr_add_string(&nw, NLSE_ATTR_SUBSYSTEM, subsystem);
        nlattr_add_string(&nw, NLSE_ATTR_TYPE, type);
        if (data != NULL)
                nlattr_add_string(&nw, NLSE_ATTR_DATA, data);
        nlmsg_end(&nw);
        nlmsg_flush(&nw);
}

static void
sysevent_new_group(size_t index, const char *name)
{
        if (index >= MAX_SYSEVENT_GROUPS) {
                NL_LOG(LOG_WARNING, "impossible to add the event %s, "
                    "too many event groups\n", name);
                return;
        }
        sysevent_groups[index].name = strdup(name, M_NLSE);
        sysevent_groups[index].id = genl_register_group(ctrl_family_id,
            sysevent_groups[index].name);
}

static struct sysevent_group *
sysevent_get_group(const char *system)
{
        for (size_t i = 0; i < MAX_SYSEVENT_GROUPS; i++) {
                if (sysevent_groups[i].name == NULL) {
                        sysevent_new_group(i, system);
                        return (&sysevent_groups[i]);
                }
                if (strcmp(sysevent_groups[i].name, system) == 0)
                        return (&sysevent_groups[i]);
        }

        return (NULL);
}

static void
sysevent_send(const char *system, const char *subsystem, const char *type,
    const char *data)
{
        struct sysevent_group *se = sysevent_get_group(system);

        if (se == NULL) {
                NL_LOG(LOG_WARNING, "impossible to add the event %s, "
                    "too many event groups\n", system);
                return;
        }

        CURVNET_SET(vnet0);
        sysevent_write(se, subsystem, type, data);
        CURVNET_RESTORE();
}

static void
nlsysevent_load(void)
{
        devctl_set_notify_hook(sysevent_send);
        ctrl_family_id = genl_register_family(NLSE_FAMILY_NAME, 0, 2, NLSE_ATTR_MAX);
        for (size_t i = 0; i < nitems(devctl_systems); i++) {
                if (i >= MAX_SYSEVENT_GROUPS) {
                        NL_LOG(LOG_WARNING, "impossible to add the event %s, too many events\n", devctl_systems[i]);
                        continue;
                }
                sysevent_new_group(i, devctl_systems[i]);
        }
}

static void
nlsysevent_unload(void)
{
        devctl_unset_notify_hook();
        genl_unregister_family(ctrl_family_id);
        for (size_t i = 0; i < MAX_SYSEVENT_GROUPS; i++) {
                if (sysevent_groups[i].name == NULL)
                        break;
                free(sysevent_groups[i].name, M_NLSE);
        }
}

static int
nlsysevent_loader(module_t mod __unused, int what, void *priv __unused)
{
        int err = 0;

        switch (what) {
        case MOD_LOAD:
                nlsysevent_load();
                break;
        case MOD_UNLOAD:
                nlsysevent_unload();
                break;
        default:
                err = EOPNOTSUPP;
                break;
        }
        return (err);
}
static moduledata_t nlsysevent_mod = { "nlsysevent", nlsysevent_loader, NULL};

DECLARE_MODULE(nlsysevent, nlsysevent_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
MODULE_DEPEND(nlsysevent, netlink, 1, 1, 1);
MODULE_VERSION(nlsysevent, 1);