?? ipt_helper.c
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/* iptables module to match on related connections *//* * (C) 2001 Martin Josefsson <gandalf@wlug.westbo.se> * * 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. * * 19 Mar 2002 Harald Welte <laforge@gnumonks.org>: * - Port to newnat infrastructure */#include <linux/module.h>#include <linux/skbuff.h>#include <linux/netfilter.h>#include <linux/netfilter_ipv4/ip_conntrack.h>#include <linux/netfilter_ipv4/ip_conntrack_core.h>#include <linux/netfilter_ipv4/ip_conntrack_helper.h>#include <linux/netfilter_ipv4/ip_tables.h>#include <linux/netfilter_ipv4/ipt_helper.h>MODULE_LICENSE("GPL");MODULE_AUTHOR("Martin Josefsson <gandalf@netfilter.org>");MODULE_DESCRIPTION("iptables helper match module");#if 0#define DEBUGP printk#else#define DEBUGP(format, args...)#endifstatic intmatch(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_helper_info *info = matchinfo; struct ip_conntrack_expect *exp; struct ip_conntrack *ct; enum ip_conntrack_info ctinfo; int ret = info->invert; ct = ip_conntrack_get((struct sk_buff *)skb, &ctinfo); if (!ct) { DEBUGP("ipt_helper: Eek! invalid conntrack?\n"); return ret; } if (!ct->master) { DEBUGP("ipt_helper: conntrack %p has no master\n", ct); return ret; } exp = ct->master; READ_LOCK(&ip_conntrack_lock); if (!exp->expectant) { DEBUGP("ipt_helper: expectation %p without expectant !?!\n", exp); goto out_unlock; } if (!exp->expectant->helper) { DEBUGP("ipt_helper: master ct %p has no helper\n", exp->expectant); goto out_unlock; } DEBUGP("master's name = %s , info->name = %s\n", exp->expectant->helper->name, info->name); if (info->name[0] == '\0') ret ^= 1; else ret ^= !strncmp(exp->expectant->helper->name, info->name, strlen(exp->expectant->helper->name));out_unlock: READ_UNLOCK(&ip_conntrack_lock); return ret;}static int check(const char *tablename, const struct ipt_ip *ip, void *matchinfo, unsigned int matchsize, unsigned int hook_mask){ struct ipt_helper_info *info = matchinfo; info->name[29] = '\0'; /* verify size */ if (matchsize != IPT_ALIGN(sizeof(struct ipt_helper_info))) return 0; return 1;}static struct ipt_match helper_match = { .name = "helper", .match = &match, .checkentry = &check, .me = THIS_MODULE,};static int __init init(void){ return ipt_register_match(&helper_match);}static void __exit fini(void){ ipt_unregister_match(&helper_match);}module_init(init);module_exit(fini);
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