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/* IP tables module for matching the value of the IPv4 DSCP field

 *

 * ipt_dscp.c,v 1.3 2002/08/05 19:00:21 laforge Exp

 *

 * (C) 2002 by Harald Welte <laforge@gnumonks.org>

 *

 * This software is distributed under the terms  GNU GPL

 */

#include <linux/module.h>

#include <linux/skbuff.h>

#include <linux/netfilter_ipv4/ipt_dscp.h>

#include <linux/netfilter_ipv4/ip_tables.h>

MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");

MODULE_DESCRIPTION("IP tables DSCP matching module");

MODULE_LICENSE("GPL");

static int match(const struct sk_buff *skb, const struct net_device *in,

                 const struct net_device *out, const void *matchinfo,

                 int offset, const void *hdr, u_int16_t datalen,

                 int *hotdrop)

{

        const struct ipt_dscp_info *info = matchinfo;

        const struct iphdr *iph = skb->nh.iph;

        u_int8_t sh_dscp = ((info->dscp << IPT_DSCP_SHIFT) & IPT_DSCP_MASK);

        return ((iph->tos&IPT_DSCP_MASK) == sh_dscp) ^ info->invert;

}

static int checkentry(const char *tablename, const struct ipt_ip *ip,

                      void *matchinfo, unsigned int matchsize,

                      unsigned int hook_mask)

{

        if (matchsize != IPT_ALIGN(sizeof(struct ipt_dscp_info)))

                return 0;

        return 1;

}

static struct ipt_match dscp_match = { { NULL, NULL }, "dscp", &match,

                &checkentry, NULL, THIS_MODULE };

static int __init init(void)

{

        return ipt_register_match(&dscp_match);

}

static void __exit fini(void)

{

        ipt_unregister_match(&dscp_match);

}

module_init(init);

module_exit(fini);