net/ipv4/netfilter/ipt_dscp.c

   1 /* IP tables module for matching the value of the IPv4 DSCP field
   2  *
   3  * ipt_dscp.c,v 1.3 2002/08/05 19:00:21 laforge Exp
   4  *
   5  * (C) 2002 by Harald Welte <laforge@netfilter.org>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/skbuff.h>
  14
  15 #include <linux/netfilter_ipv4/ipt_dscp.h>
  16 #include <linux/netfilter_ipv4/ip_tables.h>
  17
  18 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  19 MODULE_DESCRIPTION("iptables DSCP matching module");
  20 MODULE_LICENSE("GPL");
  21
  22 static int match(const struct sk_buff *skb, const struct net_device *in,
  23                  const struct net_device *out, const void *matchinfo,
  24                  int offset, int *hotdrop)
  25 {
  26         const struct ipt_dscp_info *info = matchinfo;
  27         const struct iphdr *iph = skb->nh.iph;
  28
  29         u_int8_t sh_dscp = ((info->dscp << IPT_DSCP_SHIFT) & IPT_DSCP_MASK);
  30
  31         return ((iph->tos&IPT_DSCP_MASK) == sh_dscp) ^ info->invert;
  32 }
  33
  34 static int checkentry(const char *tablename, const struct ipt_ip *ip,
  35                       void *matchinfo, unsigned int matchsize,
  36                       unsigned int hook_mask)
  37 {
  38         if (matchsize != IPT_ALIGN(sizeof(struct ipt_dscp_info)))
  39                 return 0;
  40
  41         return 1;
  42 }
  43
  44 static struct ipt_match dscp_match = {
  45         .name           = "dscp",
  46         .match          = &match,
  47         .checkentry     = &checkentry,
  48         .me             = THIS_MODULE,
  49 };
  50
  51 static int __init init(void)
  52 {
  53         return ipt_register_match(&dscp_match);
  54 }
  55
  56 static void __exit fini(void)
  57 {
  58         ipt_unregister_match(&dscp_match);
  59
  60 }
  61
  62 module_init(init);
  63 module_exit(fini);