| /* 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 ip_nat_irc_fini(void) |
| { |
| ip_nat_irc_hook = NULL; |
| /* Make sure noone calls it, meanwhile. */ |
| synchronize_net(); |
| } |
| |
| static int __init ip_nat_irc_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(ip_nat_irc_init); |
| module_exit(ip_nat_irc_fini); |