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1 /* Hop Limit matching module */
2 
3 /* (C) 2001-2002 Maciej Soltysiak <solt@dns.toxicfilms.tv>
4  * Based on HW's ttl module
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  */
10 
11 #include <linux/ipv6.h>
12 #include <linux/module.h>
13 #include <linux/skbuff.h>
14 
15 #include <linux/netfilter_ipv6/ip6t_hl.h>
16 #include <linux/netfilter/x_tables.h>
17 
18 MODULE_AUTHOR("Maciej Soltysiak <solt@dns.toxicfilms.tv>");
19 MODULE_DESCRIPTION("Xtables: IPv6 Hop Limit field match");
20 MODULE_LICENSE("GPL");
21 
hl_mt6(const struct sk_buff * skb,const struct xt_match_param * par)22 static bool hl_mt6(const struct sk_buff *skb, const struct xt_match_param *par)
23 {
24 	const struct ip6t_hl_info *info = par->matchinfo;
25 	const struct ipv6hdr *ip6h = ipv6_hdr(skb);
26 
27 	switch (info->mode) {
28 		case IP6T_HL_EQ:
29 			return ip6h->hop_limit == info->hop_limit;
30 			break;
31 		case IP6T_HL_NE:
32 			return ip6h->hop_limit != info->hop_limit;
33 			break;
34 		case IP6T_HL_LT:
35 			return ip6h->hop_limit < info->hop_limit;
36 			break;
37 		case IP6T_HL_GT:
38 			return ip6h->hop_limit > info->hop_limit;
39 			break;
40 		default:
41 			printk(KERN_WARNING "ip6t_hl: unknown mode %d\n",
42 				info->mode);
43 			return false;
44 	}
45 
46 	return false;
47 }
48 
49 static struct xt_match hl_mt6_reg __read_mostly = {
50 	.name		= "hl",
51 	.family		= NFPROTO_IPV6,
52 	.match		= hl_mt6,
53 	.matchsize	= sizeof(struct ip6t_hl_info),
54 	.me		= THIS_MODULE,
55 };
56 
hl_mt6_init(void)57 static int __init hl_mt6_init(void)
58 {
59 	return xt_register_match(&hl_mt6_reg);
60 }
61 
hl_mt6_exit(void)62 static void __exit hl_mt6_exit(void)
63 {
64 	xt_unregister_match(&hl_mt6_reg);
65 }
66 
67 module_init(hl_mt6_init);
68 module_exit(hl_mt6_exit);
69