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/* This is a module which is used for setting the TOS field of a packet. */
/* (C) 1999-2001 Paul `Rusty' Russell
* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
*
* 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.
*/
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <net/checksum.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ipt_TOS.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
MODULE_DESCRIPTION("iptables TOS mangling module");
static unsigned int
target(struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
unsigned int hooknum,
const void *targinfo,
void *userinfo)
{
const struct ipt_tos_target_info *tosinfo = targinfo;
if (((*pskb)->nh.iph->tos & IPTOS_TOS_MASK) != tosinfo->tos) {
u_int16_t diffs[2];
if (!skb_ip_make_writable(pskb, sizeof(struct iphdr)))
return NF_DROP;
diffs[0] = htons((*pskb)->nh.iph->tos) ^ 0xFFFF;
(*pskb)->nh.iph->tos
= ((*pskb)->nh.iph->tos & IPTOS_PREC_MASK)
| tosinfo->tos;
diffs[1] = htons((*pskb)->nh.iph->tos);
(*pskb)->nh.iph->check
= csum_fold(csum_partial((char *)diffs,
sizeof(diffs),
(*pskb)->nh.iph->check
^0xFFFF));
(*pskb)->nfcache |= NFC_ALTERED;
}
return IPT_CONTINUE;
}
static int
checkentry(const char *tablename,
const struct ipt_entry *e,
void *targinfo,
unsigned int targinfosize,
unsigned int hook_mask)
{
const u_int8_t tos = ((struct ipt_tos_target_info *)targinfo)->tos;
if (targinfosize != IPT_ALIGN(sizeof(struct ipt_tos_target_info))) {
printk(KERN_WARNING "TOS: targinfosize %u != %Zu\n",
targinfosize,
IPT_ALIGN(sizeof(struct ipt_tos_target_info)));
return 0;
}
if (strcmp(tablename, "mangle") != 0) {
printk(KERN_WARNING "TOS: can only be called from \"mangle\" table, not \"%s\"\n", tablename);
return 0;
}
if (tos != IPTOS_LOWDELAY
&& tos != IPTOS_THROUGHPUT
&& tos != IPTOS_RELIABILITY
&& tos != IPTOS_MINCOST
&& tos != IPTOS_NORMALSVC) {
printk(KERN_WARNING "TOS: bad tos value %#x\n", tos);
return 0;
}
return 1;
}
static struct ipt_target ipt_tos_reg = {
.name = "TOS",
.target = target,
.checkentry = checkentry,
.me = THIS_MODULE,
};
static int __init init(void)
{
return ipt_register_target(&ipt_tos_reg);
}
static void __exit fini(void)
{
ipt_unregister_target(&ipt_tos_reg);
}
module_init(init);
module_exit(fini);
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