/*
   * net/sched/em_u32.c	U32 Ematch
   *
   *		This program is free software; you can redistribute it and/or
   *		modify it under the terms of the GNU General Public License
   *		as published by the Free Software Foundation; either version
   *		2 of the License, or (at your option) any later version.
   *
   * Authors:	Thomas Graf <tgraf@suug.ch>
   *		Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
   *
   * Based on net/sched/cls_u32.c
   */

  #include <linux/module.h>
  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/skbuff.h>
  #include <net/pkt_cls.h>
  
  static int em_u32_match(struct sk_buff *skb, struct tcf_ematch *em,
  			struct tcf_pkt_info *info)
  {
  	struct tc_u32_key *key = (struct tc_u32_key *) em->data;

  	const unsigned char *ptr = skb_network_header(skb);

  	if (info) {
  		if (info->ptr)
  			ptr = info->ptr;
  		ptr += (info->nexthdr & key->offmask);
  	}
  
  	ptr += key->off;
  
  	if (!tcf_valid_offset(skb, ptr, sizeof(u32)))
  		return 0;

  	return !(((*(__be32 *) ptr)  ^ key->val) & key->mask);

  }
  
  static struct tcf_ematch_ops em_u32_ops = {
  	.kind	  = TCF_EM_U32,
  	.datalen  = sizeof(struct tc_u32_key),
  	.match	  = em_u32_match,
  	.owner	  = THIS_MODULE,
  	.link	  = LIST_HEAD_INIT(em_u32_ops.link)
  };
  
  static int __init init_em_u32(void)
  {
  	return tcf_em_register(&em_u32_ops);
  }

  static void __exit exit_em_u32(void)

  {
  	tcf_em_unregister(&em_u32_ops);
  }
  
  MODULE_LICENSE("GPL");
  
  module_init(init_em_u32);
  module_exit(exit_em_u32);

  
  MODULE_ALIAS_TCF_EMATCH(TCF_EM_U32);