| /* IP tables module for matching the value of the TTL |
| * |
| * ipt_ttl.c,v 1.5 2000/11/13 11:16:08 laforge Exp |
| * |
| * (C) 2000,2001 by Harald Welte <laforge@netfilter.org> |
| * |
| * 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/module.h> |
| #include <linux/skbuff.h> |
| |
| #include <linux/netfilter_ipv4/ipt_ttl.h> |
| #include <linux/netfilter_ipv4/ip_tables.h> |
| |
| MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); |
| MODULE_DESCRIPTION("IP tables TTL matching module"); |
| MODULE_LICENSE("GPL"); |
| |
| static int match(const struct sk_buff *skb, const struct net_device *in, |
| const struct net_device *out, const void *matchinfo, |
| int offset, int *hotdrop) |
| { |
| const struct ipt_ttl_info *info = matchinfo; |
| |
| switch (info->mode) { |
| case IPT_TTL_EQ: |
| return (skb->nh.iph->ttl == info->ttl); |
| break; |
| case IPT_TTL_NE: |
| return (!(skb->nh.iph->ttl == info->ttl)); |
| break; |
| case IPT_TTL_LT: |
| return (skb->nh.iph->ttl < info->ttl); |
| break; |
| case IPT_TTL_GT: |
| return (skb->nh.iph->ttl > info->ttl); |
| break; |
| default: |
| printk(KERN_WARNING "ipt_ttl: unknown mode %d\n", |
| info->mode); |
| return 0; |
| } |
| |
| return 0; |
| } |
| |
| static int checkentry(const char *tablename, const struct ipt_ip *ip, |
| void *matchinfo, unsigned int matchsize, |
| unsigned int hook_mask) |
| { |
| if (matchsize != IPT_ALIGN(sizeof(struct ipt_ttl_info))) |
| return 0; |
| |
| return 1; |
| } |
| |
| static struct ipt_match ttl_match = { |
| .name = "ttl", |
| .match = &match, |
| .checkentry = &checkentry, |
| .me = THIS_MODULE, |
| }; |
| |
| static int __init init(void) |
| { |
| return ipt_register_match(&ttl_match); |
| } |
| |
| static void __exit fini(void) |
| { |
| ipt_unregister_match(&ttl_match); |
| |
| } |
| |
| module_init(init); |
| module_exit(fini); |