| /* Amanda extension for TCP NAT alteration. |
| * (C) 2002 by Brian J. Murrell <netfilter@interlinx.bc.ca> |
| * based on a copy of HW's ip_nat_irc.c as well as other modules |
| * |
| * 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. |
| * |
| * Module load syntax: |
| * insmod ip_nat_amanda.o |
| */ |
| |
| #include <linux/kernel.h> |
| #include <linux/module.h> |
| #include <linux/netfilter.h> |
| #include <linux/skbuff.h> |
| #include <linux/ip.h> |
| #include <linux/udp.h> |
| #include <net/tcp.h> |
| #include <net/udp.h> |
| |
| #include <linux/netfilter_ipv4.h> |
| #include <linux/netfilter_ipv4/ip_nat.h> |
| #include <linux/netfilter_ipv4/ip_nat_helper.h> |
| #include <linux/netfilter_ipv4/ip_conntrack_helper.h> |
| #include <linux/netfilter_ipv4/ip_conntrack_amanda.h> |
| |
| |
| MODULE_AUTHOR("Brian J. Murrell <netfilter@interlinx.bc.ca>"); |
| MODULE_DESCRIPTION("Amanda 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) |
| { |
| char buffer[sizeof("65535")]; |
| u_int16_t port; |
| unsigned int ret; |
| |
| /* Connection comes from client. */ |
| exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port; |
| exp->dir = IP_CT_DIR_ORIGINAL; |
| |
| /* When you see the packet, we need to NAT it the same as the |
| * this one (ie. same IP: it will be TCP and master is UDP). */ |
| 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; |
| |
| sprintf(buffer, "%u", port); |
| ret = ip_nat_mangle_udp_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_amanda_fini(void) |
| { |
| ip_nat_amanda_hook = NULL; |
| /* Make sure noone calls it, meanwhile. */ |
| synchronize_net(); |
| } |
| |
| static int __init ip_nat_amanda_init(void) |
| { |
| BUG_ON(ip_nat_amanda_hook); |
| ip_nat_amanda_hook = help; |
| return 0; |
| } |
| |
| module_init(ip_nat_amanda_init); |
| module_exit(ip_nat_amanda_fini); |