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[/] [or1k_soc_on_altera_embedded_dev_kit/] [trunk/] [linux-2.6/] [linux-2.6.24/] [net/] [ipv6/] [netfilter/] [ip6t_HL.c] - Rev 3
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/* * Hop Limit modification target for ip6tables * Maciej Soltysiak <solt@dns.toxicfilms.tv> * Based on HW's TTL module * * This software is distributed under the terms of GNU GPL */ #include <linux/module.h> #include <linux/skbuff.h> #include <linux/ip.h> #include <linux/ipv6.h> #include <linux/netfilter/x_tables.h> #include <linux/netfilter_ipv6/ip6t_HL.h> MODULE_AUTHOR("Maciej Soltysiak <solt@dns.toxicfilms.tv>"); MODULE_DESCRIPTION("IP6 tables Hop Limit modification module"); MODULE_LICENSE("GPL"); static unsigned int ip6t_hl_target(struct sk_buff *skb, const struct net_device *in, const struct net_device *out, unsigned int hooknum, const struct xt_target *target, const void *targinfo) { struct ipv6hdr *ip6h; const struct ip6t_HL_info *info = targinfo; int new_hl; if (!skb_make_writable(skb, skb->len)) return NF_DROP; ip6h = ipv6_hdr(skb); switch (info->mode) { case IP6T_HL_SET: new_hl = info->hop_limit; break; case IP6T_HL_INC: new_hl = ip6h->hop_limit + info->hop_limit; if (new_hl > 255) new_hl = 255; break; case IP6T_HL_DEC: new_hl = ip6h->hop_limit - info->hop_limit; if (new_hl < 0) new_hl = 0; break; default: new_hl = ip6h->hop_limit; break; } ip6h->hop_limit = new_hl; return XT_CONTINUE; } static bool ip6t_hl_checkentry(const char *tablename, const void *entry, const struct xt_target *target, void *targinfo, unsigned int hook_mask) { const struct ip6t_HL_info *info = targinfo; if (info->mode > IP6T_HL_MAXMODE) { printk(KERN_WARNING "ip6t_HL: invalid or unknown Mode %u\n", info->mode); return false; } if (info->mode != IP6T_HL_SET && info->hop_limit == 0) { printk(KERN_WARNING "ip6t_HL: increment/decrement doesn't " "make sense with value 0\n"); return false; } return true; } static struct xt_target ip6t_HL __read_mostly = { .name = "HL", .family = AF_INET6, .target = ip6t_hl_target, .targetsize = sizeof(struct ip6t_HL_info), .table = "mangle", .checkentry = ip6t_hl_checkentry, .me = THIS_MODULE }; static int __init ip6t_hl_init(void) { return xt_register_target(&ip6t_HL); } static void __exit ip6t_hl_fini(void) { xt_unregister_target(&ip6t_HL); } module_init(ip6t_hl_init); module_exit(ip6t_hl_fini);