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/* Kernel module to match MAC address parameters. */

#include <linux/module.h>

#include <linux/skbuff.h>

#include <linux/if_ether.h>

#include <linux/netfilter_ipv4/ipt_mac.h>

#include <linux/netfilter_ipv4/ip_tables.h>

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_mac_info *info = matchinfo;

    /* Is mac pointer valid? */

    return (skb->mac.raw >= skb->head

            && (skb->mac.raw + ETH_HLEN) <= skb->data

            /* If so, compare... */

            && ((memcmp(skb->mac.ethernet->h_source, info->srcaddr, ETH_ALEN)

                == 0) ^ info->invert));

}

static int

ipt_mac_checkentry(const char *tablename,

                   const struct ipt_ip *ip,

                   void *matchinfo,

                   unsigned int matchsize,

                   unsigned int hook_mask)

{

        /* FORWARD isn't always valid, but it's nice to be able to do --RR */

        if (hook_mask

            & ~((1 << NF_IP_PRE_ROUTING) | (1 << NF_IP_LOCAL_IN)

                | (1 << NF_IP_FORWARD))) {

                printk("ipt_mac: only valid for PRE_ROUTING, LOCAL_IN or FORWARD.\n");

                return 0;

        }

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

                return 0;

        return 1;

}

static struct ipt_match mac_match

= { { NULL, NULL }, "mac", &match, &ipt_mac_checkentry, NULL, THIS_MODULE };

static int __init init(void)

{

        return ipt_register_match(&mac_match);

}

static void __exit fini(void)

{

        ipt_unregister_match(&mac_match);

}

module_init(init);

module_exit(fini);

MODULE_LICENSE("GPL");