2 * Hop Limit modification target for ip6tables
3 * Maciej Soltysiak <solt@dns.toxicfilms.tv>
4 * Based on HW's TTL module
6 * This software is distributed under the terms of GNU GPL
9 #include <linux/module.h>
10 #include <linux/skbuff.h>
13 #include <linux/netfilter_ipv6/ip6_tables.h>
14 #include <linux/netfilter_ipv6/ip6t_HL.h>
16 MODULE_AUTHOR("Maciej Soltysiak <solt@dns.toxicfilms.tv>");
17 MODULE_DESCRIPTION("IP tables Hop Limit modification module");
18 MODULE_LICENSE("GPL");
20 static unsigned int ip6t_hl_target(struct sk_buff
**pskb
,
21 const struct net_device
*in
,
22 const struct net_device
*out
,
24 const struct xt_target
*target
,
28 const struct ip6t_HL_info
*info
= targinfo
;
31 if (!skb_make_writable(pskb
, (*pskb
)->len
))
34 ip6h
= (*pskb
)->nh
.ipv6h
;
38 new_hl
= info
->hop_limit
;
41 new_hl
= ip6h
->hop_limit
+ info
->hop_limit
;
46 new_hl
= ip6h
->hop_limit
- info
->hop_limit
;
51 new_hl
= ip6h
->hop_limit
;
55 if (new_hl
!= ip6h
->hop_limit
)
56 ip6h
->hop_limit
= new_hl
;
61 static int ip6t_hl_checkentry(const char *tablename
,
63 const struct xt_target
*target
,
65 unsigned int hook_mask
)
67 struct ip6t_HL_info
*info
= targinfo
;
69 if (info
->mode
> IP6T_HL_MAXMODE
) {
70 printk(KERN_WARNING
"ip6t_HL: invalid or unknown Mode %u\n",
74 if ((info
->mode
!= IP6T_HL_SET
) && (info
->hop_limit
== 0)) {
75 printk(KERN_WARNING
"ip6t_HL: increment/decrement doesn't "
76 "make sense with value 0\n");
82 static struct ip6t_target ip6t_HL
= {
84 .target
= ip6t_hl_target
,
85 .targetsize
= sizeof(struct ip6t_HL_info
),
87 .checkentry
= ip6t_hl_checkentry
,
91 static int __init
ip6t_hl_init(void)
93 return ip6t_register_target(&ip6t_HL
);
96 static void __exit
ip6t_hl_fini(void)
98 ip6t_unregister_target(&ip6t_HL
);
101 module_init(ip6t_hl_init
);
102 module_exit(ip6t_hl_fini
);