/*

   * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>

   *
   * 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.
   *
   * Development of this code funded by Astaro AG (http://www.astaro.com/)
   */
  
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/netlink.h>
  #include <linux/netfilter.h>
  #include <linux/netfilter/nf_tables.h>
  #include <net/netfilter/nf_tables_core.h>
  #include <net/netfilter/nf_tables.h>
  
  struct nft_bitwise {
  	enum nft_registers	sreg:8;
  	enum nft_registers	dreg:8;
  	u8			len;
  	struct nft_data		mask;
  	struct nft_data		xor;
  };
  
  static void nft_bitwise_eval(const struct nft_expr *expr,

  			     struct nft_regs *regs,

  			     const struct nft_pktinfo *pkt)
  {
  	const struct nft_bitwise *priv = nft_expr_priv(expr);

  	const u32 *src = &regs->data[priv->sreg];
  	u32 *dst = &regs->data[priv->dreg];

  	unsigned int i;

  	for (i = 0; i < DIV_ROUND_UP(priv->len, 4); i++)
  		dst[i] = (src[i] & priv->mask.data[i]) ^ priv->xor.data[i];

  }
  
  static const struct nla_policy nft_bitwise_policy[NFTA_BITWISE_MAX + 1] = {
  	[NFTA_BITWISE_SREG]	= { .type = NLA_U32 },
  	[NFTA_BITWISE_DREG]	= { .type = NLA_U32 },
  	[NFTA_BITWISE_LEN]	= { .type = NLA_U32 },
  	[NFTA_BITWISE_MASK]	= { .type = NLA_NESTED },
  	[NFTA_BITWISE_XOR]	= { .type = NLA_NESTED },
  };
  
  static int nft_bitwise_init(const struct nft_ctx *ctx,
  			    const struct nft_expr *expr,
  			    const struct nlattr * const tb[])
  {
  	struct nft_bitwise *priv = nft_expr_priv(expr);
  	struct nft_data_desc d1, d2;
  	int err;
  
  	if (tb[NFTA_BITWISE_SREG] == NULL ||
  	    tb[NFTA_BITWISE_DREG] == NULL ||
  	    tb[NFTA_BITWISE_LEN] == NULL ||
  	    tb[NFTA_BITWISE_MASK] == NULL ||
  	    tb[NFTA_BITWISE_XOR] == NULL)
  		return -EINVAL;

  	priv->len  = ntohl(nla_get_be32(tb[NFTA_BITWISE_LEN]));

  	priv->sreg = nft_parse_register(tb[NFTA_BITWISE_SREG]);

  	err = nft_validate_register_load(priv->sreg, priv->len);

  	if (err < 0)
  		return err;

  	priv->dreg = nft_parse_register(tb[NFTA_BITWISE_DREG]);

  	err = nft_validate_register_store(ctx, priv->dreg, NULL,
  					  NFT_DATA_VALUE, priv->len);

  	if (err < 0)
  		return err;

  	err = nft_data_init(NULL, &priv->mask, sizeof(priv->mask), &d1,
  			    tb[NFTA_BITWISE_MASK]);

  	if (err < 0)
  		return err;
  	if (d1.len != priv->len)
  		return -EINVAL;

  	err = nft_data_init(NULL, &priv->xor, sizeof(priv->xor), &d2,
  			    tb[NFTA_BITWISE_XOR]);

  	if (err < 0)
  		return err;
  	if (d2.len != priv->len)
  		return -EINVAL;
  
  	return 0;
  }
  
  static int nft_bitwise_dump(struct sk_buff *skb, const struct nft_expr *expr)
  {
  	const struct nft_bitwise *priv = nft_expr_priv(expr);

  	if (nft_dump_register(skb, NFTA_BITWISE_SREG, priv->sreg))

  		goto nla_put_failure;

  	if (nft_dump_register(skb, NFTA_BITWISE_DREG, priv->dreg))

  		goto nla_put_failure;
  	if (nla_put_be32(skb, NFTA_BITWISE_LEN, htonl(priv->len)))
  		goto nla_put_failure;
  
  	if (nft_data_dump(skb, NFTA_BITWISE_MASK, &priv->mask,
  			  NFT_DATA_VALUE, priv->len) < 0)
  		goto nla_put_failure;
  
  	if (nft_data_dump(skb, NFTA_BITWISE_XOR, &priv->xor,
  			  NFT_DATA_VALUE, priv->len) < 0)
  		goto nla_put_failure;
  
  	return 0;
  
  nla_put_failure:
  	return -1;
  }

  static struct nft_expr_type nft_bitwise_type;
  static const struct nft_expr_ops nft_bitwise_ops = {
  	.type		= &nft_bitwise_type,

  	.size		= NFT_EXPR_SIZE(sizeof(struct nft_bitwise)),

  	.eval		= nft_bitwise_eval,
  	.init		= nft_bitwise_init,
  	.dump		= nft_bitwise_dump,

  };
  
  static struct nft_expr_type nft_bitwise_type __read_mostly = {
  	.name		= "bitwise",
  	.ops		= &nft_bitwise_ops,

  	.policy		= nft_bitwise_policy,
  	.maxattr	= NFTA_BITWISE_MAX,

  	.owner		= THIS_MODULE,

  };
  
  int __init nft_bitwise_module_init(void)
  {

  	return nft_register_expr(&nft_bitwise_type);

  }
  
  void nft_bitwise_module_exit(void)
  {

  	nft_unregister_expr(&nft_bitwise_type);

  }