Patrick McHardy | f338980 | 2006-05-29 18:21:00 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (c) 2006 Patrick McHardy <kaber@trash.net> |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License version 2 as |
| 6 | * published by the Free Software Foundation. |
| 7 | * |
| 8 | * Based on ipt_random and ipt_nth by Fabrice MARIE <fabrice@netfilter.org>. |
| 9 | */ |
| 10 | |
| 11 | #include <linux/init.h> |
| 12 | #include <linux/spinlock.h> |
| 13 | #include <linux/skbuff.h> |
| 14 | #include <linux/net.h> |
| 15 | |
| 16 | #include <linux/netfilter/xt_statistic.h> |
| 17 | #include <linux/netfilter/x_tables.h> |
| 18 | |
| 19 | MODULE_LICENSE("GPL"); |
| 20 | MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); |
| 21 | MODULE_DESCRIPTION("xtables statistical match module"); |
| 22 | MODULE_ALIAS("ipt_statistic"); |
| 23 | MODULE_ALIAS("ip6t_statistic"); |
| 24 | |
| 25 | static DEFINE_SPINLOCK(nth_lock); |
| 26 | |
| 27 | static int |
| 28 | match(const struct sk_buff *skb, |
| 29 | const struct net_device *in, const struct net_device *out, |
| 30 | const struct xt_match *match, const void *matchinfo, |
| 31 | int offset, unsigned int protoff, int *hotdrop) |
| 32 | { |
| 33 | struct xt_statistic_info *info = (struct xt_statistic_info *)matchinfo; |
| 34 | int ret = info->flags & XT_STATISTIC_INVERT ? 1 : 0; |
| 35 | |
| 36 | switch (info->mode) { |
| 37 | case XT_STATISTIC_MODE_RANDOM: |
| 38 | if ((net_random() & 0x7FFFFFFF) < info->u.random.probability) |
| 39 | ret ^= 1; |
| 40 | break; |
| 41 | case XT_STATISTIC_MODE_NTH: |
| 42 | info = info->master; |
| 43 | spin_lock_bh(&nth_lock); |
| 44 | if (info->u.nth.count++ == info->u.nth.every) { |
| 45 | info->u.nth.count = 0; |
| 46 | ret ^= 1; |
| 47 | } |
| 48 | spin_unlock_bh(&nth_lock); |
| 49 | break; |
| 50 | } |
| 51 | |
| 52 | return ret; |
| 53 | } |
| 54 | |
| 55 | static int |
| 56 | checkentry(const char *tablename, const void *entry, |
| 57 | const struct xt_match *match, void *matchinfo, |
| 58 | unsigned int matchsize, unsigned int hook_mask) |
| 59 | { |
| 60 | struct xt_statistic_info *info = (struct xt_statistic_info *)matchinfo; |
| 61 | |
| 62 | if (info->mode > XT_STATISTIC_MODE_MAX || |
| 63 | info->flags & ~XT_STATISTIC_MASK) |
| 64 | return 0; |
| 65 | info->master = info; |
| 66 | return 1; |
| 67 | } |
| 68 | |
| 69 | static struct xt_match statistic_match = { |
| 70 | .name = "statistic", |
| 71 | .match = match, |
| 72 | .matchsize = sizeof(struct xt_statistic_info), |
| 73 | .checkentry = checkentry, |
| 74 | .family = AF_INET, |
| 75 | .me = THIS_MODULE, |
| 76 | }; |
| 77 | |
| 78 | static struct xt_match statistic_match6 = { |
| 79 | .name = "statistic", |
| 80 | .match = match, |
| 81 | .matchsize = sizeof(struct xt_statistic_info), |
| 82 | .checkentry = checkentry, |
| 83 | .family = AF_INET6, |
| 84 | .me = THIS_MODULE, |
| 85 | }; |
| 86 | |
| 87 | static int __init xt_statistic_init(void) |
| 88 | { |
| 89 | int ret; |
| 90 | |
| 91 | ret = xt_register_match(&statistic_match); |
| 92 | if (ret) |
| 93 | goto err1; |
| 94 | |
| 95 | ret = xt_register_match(&statistic_match6); |
| 96 | if (ret) |
| 97 | goto err2; |
| 98 | return ret; |
| 99 | err2: |
| 100 | xt_unregister_match(&statistic_match); |
| 101 | err1: |
| 102 | return ret; |
| 103 | } |
| 104 | |
| 105 | static void __exit xt_statistic_fini(void) |
| 106 | { |
| 107 | xt_unregister_match(&statistic_match6); |
| 108 | xt_unregister_match(&statistic_match); |
| 109 | } |
| 110 | |
| 111 | module_init(xt_statistic_init); |
| 112 | module_exit(xt_statistic_fini); |