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/* IRC extension for TCP NAT alteration.
* (C) 2000-2001 by Harald Welte <laforge@gnumonks.org>
* (C) 2004 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
* based on a copy of RR's ip_nat_ftp.c
*
* ip_nat_irc.c,v 1.16 2001/12/06 07:42:10 laforge Exp
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/module.h>
#include <linux/netfilter_ipv4.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/kernel.h>
#include <net/tcp.h>
#include <linux/netfilter_ipv4/ip_nat.h>
#include <linux/netfilter_ipv4/ip_nat_helper.h>
#include <linux/netfilter_ipv4/ip_nat_rule.h>
#include <linux/netfilter_ipv4/ip_conntrack_irc.h>
#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
#include <linux/moduleparam.h>
#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif
MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
MODULE_DESCRIPTION("IRC (DCC) NAT helper");
MODULE_LICENSE("GPL");
static unsigned int help(struct sk_buff **pskb,
enum ip_conntrack_info ctinfo,
unsigned int matchoff,
unsigned int matchlen,
struct ip_conntrack_expect *exp)
{
u_int16_t port;
unsigned int ret;
/* "4294967296 65635 " */
char buffer[18];
DEBUGP("IRC_NAT: info (seq %u + %u) in %u\n",
expect->seq, exp_irc_info->len,
ntohl(tcph->seq));
/* Reply comes from server. */
exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
exp->dir = IP_CT_DIR_REPLY;
/* When you see the packet, we need to NAT it the same as the
* this one. */
exp->expectfn = ip_nat_follow_master;
/* Try to get same port: if not, try to change it. */
for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) {
exp->tuple.dst.u.tcp.port = htons(port);
if (ip_conntrack_expect_related(exp) == 0)
break;
}
if (port == 0)
return NF_DROP;
/* strlen("\1DCC CHAT chat AAAAAAAA P\1\n")=27
* strlen("\1DCC SCHAT chat AAAAAAAA P\1\n")=28
* strlen("\1DCC SEND F AAAAAAAA P S\1\n")=26
* strlen("\1DCC MOVE F AAAAAAAA P S\1\n")=26
* strlen("\1DCC TSEND F AAAAAAAA P S\1\n")=27
* AAAAAAAAA: bound addr (1.0.0.0==16777216, min 8 digits,
* 255.255.255.255==4294967296, 10 digits)
* P: bound port (min 1 d, max 5d (65635))
* F: filename (min 1 d )
* S: size (min 1 d )
* 0x01, \n: terminators
*/
/* AAA = "us", ie. where server normally talks to. */
sprintf(buffer, "%u %u",
ntohl(exp->master->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip),
port);
DEBUGP("ip_nat_irc: Inserting '%s' == %u.%u.%u.%u, port %u\n",
buffer, NIPQUAD(exp->tuple.src.ip), port);
ret = ip_nat_mangle_tcp_packet(pskb, exp->master, ctinfo,
matchoff, matchlen, buffer,
strlen(buffer));
if (ret != NF_ACCEPT)
ip_conntrack_unexpect_related(exp);
return ret;
}
static void __exit fini(void)
{
ip_nat_irc_hook = NULL;
/* Make sure noone calls it, meanwhile. */
synchronize_net();
}
static int __init init(void)
{
BUG_ON(ip_nat_irc_hook);
ip_nat_irc_hook = help;
return 0;
}
/* Prior to 2.6.11, we had a ports param. No longer, but don't break users. */
static int warn_set(const char *val, struct kernel_param *kp)
{
printk(KERN_INFO KBUILD_MODNAME
": kernel >= 2.6.10 only uses 'ports' for conntrack modules\n");
return 0;
}
module_param_call(ports, warn_set, NULL, NULL, 0);
module_init(init);
module_exit(fini);
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