// SPDX-License-Identifier: GPL-2.0-only
/*
 * (C) 2007 Patrick McHardy <kaber@trash.net>
 */
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/gen_stats.h>

#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_rateest.h>
#include <net/netfilter/xt_rateest.h>


static bool
xt_rateest_mt(const struct sk_buff *skb, struct xt_action_param *par)
{
        const struct xt_rateest_match_info *info = par->matchinfo;
        struct gnet_stats_rate_est64 sample = {0};
        u64 bps1, bps2, pps1, pps2;
        bool ret = true;

        gen_estimator_read(&info->est1->rate_est, &sample);

        if (info->flags & XT_RATEEST_MATCH_DELTA) {
                bps1 = info->bps1 >= sample.bps ? info->bps1 - sample.bps : 0;
                pps1 = info->pps1 >= sample.pps ? info->pps1 - sample.pps : 0;
        } else {
                bps1 = sample.bps;
                pps1 = sample.pps;
        }

        if (info->flags & XT_RATEEST_MATCH_ABS) {
                bps2 = info->bps2;
                pps2 = info->pps2;
        } else {
                gen_estimator_read(&info->est2->rate_est, &sample);

                if (info->flags & XT_RATEEST_MATCH_DELTA) {
                        bps2 = info->bps2 >= sample.bps ? info->bps2 - sample.bps : 0;
                        pps2 = info->pps2 >= sample.pps ? info->pps2 - sample.pps : 0;
                } else {
                        bps2 = sample.bps;
                        pps2 = sample.pps;
                }
        }

        switch (info->mode) {
        case XT_RATEEST_MATCH_LT:
                if (info->flags & XT_RATEEST_MATCH_BPS)
                        ret &= bps1 < bps2;
                if (info->flags & XT_RATEEST_MATCH_PPS)
                        ret &= pps1 < pps2;
                break;
        case XT_RATEEST_MATCH_GT:
                if (info->flags & XT_RATEEST_MATCH_BPS)
                        ret &= bps1 > bps2;
                if (info->flags & XT_RATEEST_MATCH_PPS)
                        ret &= pps1 > pps2;
                break;
        case XT_RATEEST_MATCH_EQ:
                if (info->flags & XT_RATEEST_MATCH_BPS)
                        ret &= bps1 == bps2;
                if (info->flags & XT_RATEEST_MATCH_PPS)
                        ret &= pps1 == pps2;
                break;
        }

        ret ^= info->flags & XT_RATEEST_MATCH_INVERT ? true : false;
        return ret;
}

static int xt_rateest_mt_checkentry(const struct xt_mtchk_param *par)
{
        struct xt_rateest_match_info *info = par->matchinfo;
        struct xt_rateest *est1, *est2;
        int ret = -EINVAL;

        if (hweight32(info->flags & (XT_RATEEST_MATCH_ABS |
                                     XT_RATEEST_MATCH_REL)) != 1)
                goto err1;

        if (!(info->flags & (XT_RATEEST_MATCH_BPS | XT_RATEEST_MATCH_PPS)))
                goto err1;

        switch (info->mode) {
        case XT_RATEEST_MATCH_EQ:
        case XT_RATEEST_MATCH_LT:
        case XT_RATEEST_MATCH_GT:
                break;
        default:
                goto err1;
        }

        if (strnlen(info->name1, sizeof(info->name1)) >= sizeof(info->name1))
                return -ENAMETOOLONG;
        if (strnlen(info->name2, sizeof(info->name2)) >= sizeof(info->name2))
                return -ENAMETOOLONG;

        ret  = -ENOENT;
        est1 = xt_rateest_lookup(par->net, info->name1);
        if (!est1)
                goto err1;

        est2 = NULL;
        if (info->flags & XT_RATEEST_MATCH_REL) {
                est2 = xt_rateest_lookup(par->net, info->name2);
                if (!est2)
                        goto err2;
        }

        info->est1 = est1;
        info->est2 = est2;
        return 0;

err2:
        xt_rateest_put(par->net, est1);
err1:
        return ret;
}

static void xt_rateest_mt_destroy(const struct xt_mtdtor_param *par)
{
        struct xt_rateest_match_info *info = par->matchinfo;

        xt_rateest_put(par->net, info->est1);
        if (info->est2)
                xt_rateest_put(par->net, info->est2);
}

static struct xt_match xt_rateest_mt_reg __read_mostly = {
        .name       = "rateest",
        .revision   = 0,
        .family     = NFPROTO_UNSPEC,
        .match      = xt_rateest_mt,
        .checkentry = xt_rateest_mt_checkentry,
        .destroy    = xt_rateest_mt_destroy,
        .matchsize  = sizeof(struct xt_rateest_match_info),
        .usersize   = offsetof(struct xt_rateest_match_info, est1),
        .me         = THIS_MODULE,
};

static int __init xt_rateest_mt_init(void)
{
        return xt_register_match(&xt_rateest_mt_reg);
}

static void __exit xt_rateest_mt_fini(void)
{
        xt_unregister_match(&xt_rateest_mt_reg);
}

MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("xtables rate estimator match");
MODULE_ALIAS("ipt_rateest");
MODULE_ALIAS("ip6t_rateest");
module_init(xt_rateest_mt_init);
module_exit(xt_rateest_mt_fini);