root/net/ipv6/netfilter/ip6t_hl.c

DEFINITIONS

1. hl_mt6
2. hl_mt6_init
3. hl_mt6_exit

/* Hop Limit matching module */

/* (C) 2001-2002 Maciej Soltysiak <solt@dns.toxicfilms.tv>
 * Based on HW's ttl module
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/ipv6.h>
#include <linux/module.h>
#include <linux/skbuff.h>

#include <linux/netfilter_ipv6/ip6t_hl.h>
#include <linux/netfilter/x_tables.h>

MODULE_AUTHOR("Maciej Soltysiak <solt@dns.toxicfilms.tv>");
MODULE_DESCRIPTION("Xtables: IPv6 Hop Limit field match");
MODULE_LICENSE("GPL");

static bool hl_mt6(const struct sk_buff *skb, const struct xt_match_param *par)
{
        const struct ip6t_hl_info *info = par->matchinfo;
        const struct ipv6hdr *ip6h = ipv6_hdr(skb);

        switch (info->mode) {
                case IP6T_HL_EQ:
                        return ip6h->hop_limit == info->hop_limit;
                        break;
                case IP6T_HL_NE:
                        return ip6h->hop_limit != info->hop_limit;
                        break;
                case IP6T_HL_LT:
                        return ip6h->hop_limit < info->hop_limit;
                        break;
                case IP6T_HL_GT:
                        return ip6h->hop_limit > info->hop_limit;
                        break;
                default:
                        printk(KERN_WARNING "ip6t_hl: unknown mode %d\n",
                                info->mode);
                        return false;
        }

        return false;
}

static struct xt_match hl_mt6_reg __read_mostly = {
        .name           = "hl",
        .family         = NFPROTO_IPV6,
        .match          = hl_mt6,
        .matchsize      = sizeof(struct ip6t_hl_info),
        .me             = THIS_MODULE,
};

static int __init hl_mt6_init(void)
{
        return xt_register_match(&hl_mt6_reg);
}

static void __exit hl_mt6_exit(void)
{
        xt_unregister_match(&hl_mt6_reg);
}

module_init(hl_mt6_init);
module_exit(hl_mt6_exit);