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/* iptables module for setting the IPv4 DSCP field, Version 1.8
*
* (C) 2002 by Harald Welte <laforge@netfilter.org>
* based on ipt_FTOS.c (C) 2000 by Matthew G. Marsh <mgm@paktronix.com>
*
* 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.
*
* See RFC2474 for a description of the DSCP field within the IP Header.
*
* ipt_DSCP.c,v 1.8 2002/08/06 18:41:57 laforge Exp
*/
#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_DSCP.h>
MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
MODULE_DESCRIPTION("iptables DSCP modification module");
MODULE_LICENSE("GPL");
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_DSCP_info *dinfo = targinfo;
u_int8_t sh_dscp = ((dinfo->dscp << IPT_DSCP_SHIFT) & IPT_DSCP_MASK);
if (((*pskb)->nh.iph->tos & IPT_DSCP_MASK) != sh_dscp) {
u_int16_t diffs[2];
if (!skb_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 & ~IPT_DSCP_MASK)
| sh_dscp;
diffs[1] = htons((*pskb)->nh.iph->tos);
(*pskb)->nh.iph->check
= csum_fold(csum_partial((char *)diffs,
sizeof(diffs),
(*pskb)->nh.iph->check
^ 0xFFFF));
}
return IPT_CONTINUE;
}
static int
checkentry(const char *tablename,
const void *e_void,
void *targinfo,
unsigned int targinfosize,
unsigned int hook_mask)
{
const u_int8_t dscp = ((struct ipt_DSCP_info *)targinfo)->dscp;
if (targinfosize != IPT_ALIGN(sizeof(struct ipt_DSCP_info))) {
printk(KERN_WARNING "DSCP: targinfosize %u != %Zu\n",
targinfosize,
IPT_ALIGN(sizeof(struct ipt_DSCP_info)));
return 0;
}
if (strcmp(tablename, "mangle") != 0) {
printk(KERN_WARNING "DSCP: can only be called from \"mangle\" table, not \"%s\"\n", tablename);
return 0;
}
if ((dscp > IPT_DSCP_MAX)) {
printk(KERN_WARNING "DSCP: dscp %x out of range\n", dscp);
return 0;
}
return 1;
}
static struct ipt_target ipt_dscp_reg = {
.name = "DSCP",
.target = target,
.checkentry = checkentry,
.me = THIS_MODULE,
};
static int __init init(void)
{
return ipt_register_target(&ipt_dscp_reg);
}
static void __exit fini(void)
{
ipt_unregister_target(&ipt_dscp_reg);
}
module_init(init);
module_exit(fini);
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