/* 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 intamanda_nat_expected(struct sk_buff **pskb,                    unsigned int hooknum,                    struct ip_conntrack *ct,                    struct ip_nat_info *info){	struct ip_conntrack *master = master_ct(ct);	struct ip_ct_amanda_expect *exp_amanda_info;	struct ip_nat_multi_range mr;	u_int32_t newip;	IP_NF_ASSERT(info);	IP_NF_ASSERT(master);	IP_NF_ASSERT(!(info->initialized & (1 << HOOK2MANIP(hooknum))));	if (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC)		newip = master->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip;	else		newip = master->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip;	mr.rangesize = 1;	/* We don't want to manip the per-protocol, just the IPs. */	mr.range[0].flags = IP_NAT_RANGE_MAP_IPS;	mr.range[0].min_ip = mr.range[0].max_ip = newip;	if (HOOK2MANIP(hooknum) == IP_NAT_MANIP_DST) {		exp_amanda_info = &ct->master->help.exp_amanda_info;		mr.range[0].flags |= IP_NAT_RANGE_PROTO_SPECIFIED;		mr.range[0].min = mr.range[0].max			= ((union ip_conntrack_manip_proto)				{ .udp = { htons(exp_amanda_info->port) } });	}	return ip_nat_setup_info(ct, &mr, hooknum);}static int amanda_data_fixup(struct ip_conntrack *ct,                             struct sk_buff **pskb,                             enum ip_conntrack_info ctinfo,                             struct ip_conntrack_expect *exp){	struct ip_ct_amanda_expect *exp_amanda_info;	struct ip_conntrack_tuple t = exp->tuple;	char buffer[sizeof("65535")];	u_int16_t port;	/* Alter conntrack's expectations. */	exp_amanda_info = &exp->help.exp_amanda_info;	t.dst.ip = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.ip;	for (port = exp_amanda_info->port; port != 0; port++) {		t.dst.u.tcp.port = htons(port);		if (ip_conntrack_change_expect(exp, &t) == 0)			break;	}	if (port == 0)		return 0;	sprintf(buffer, "%u", port);	return ip_nat_mangle_udp_packet(pskb, ct, ctinfo,	                                exp_amanda_info->offset,	                                exp_amanda_info->len,	                                buffer, strlen(buffer));}static unsigned int help(struct ip_conntrack *ct,                         struct ip_conntrack_expect *exp,                         struct ip_nat_info *info,                         enum ip_conntrack_info ctinfo,                         unsigned int hooknum,                         struct sk_buff **pskb){	int dir = CTINFO2DIR(ctinfo);	int ret = NF_ACCEPT;	/* Only mangle things once: original direction in POST_ROUTING	   and reply direction on PRE_ROUTING. */	if (!((hooknum == NF_IP_POST_ROUTING && dir == IP_CT_DIR_ORIGINAL)	      || (hooknum == NF_IP_PRE_ROUTING && dir == IP_CT_DIR_REPLY)))		return NF_ACCEPT;	/* if this exectation has a "offset" the packet needs to be mangled */	if (exp->help.exp_amanda_info.offset != 0)		if (!amanda_data_fixup(ct, pskb, ctinfo, exp))			ret = NF_DROP;	exp->help.exp_amanda_info.offset = 0;	return ret;}static struct ip_nat_helper ip_nat_amanda_helper;static void __exit fini(void){	ip_nat_helper_unregister(&ip_nat_amanda_helper);}static int __init init(void){	struct ip_nat_helper *hlpr = &ip_nat_amanda_helper;	hlpr->tuple.dst.protonum = IPPROTO_UDP;	hlpr->tuple.src.u.udp.port = htons(10080);	hlpr->mask.src.u.udp.port = 0xFFFF;	hlpr->mask.dst.protonum = 0xFFFF;	hlpr->help = help;	hlpr->flags = 0;	hlpr->me = THIS_MODULE;	hlpr->expect = amanda_nat_expected;	hlpr->name = "amanda";	return ip_nat_helper_register(hlpr);}NEEDS_CONNTRACK(amanda);module_init(init);module_exit(fini);