/* String matching match for iptables

   *

   * (C) 2005 Pablo Neira Ayuso <pablo@eurodev.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.
   */

  #include <linux/gfp.h>

  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/skbuff.h>

  #include <linux/netfilter/x_tables.h>
  #include <linux/netfilter/xt_string.h>

  #include <linux/textsearch.h>
  
  MODULE_AUTHOR("Pablo Neira Ayuso <pablo@eurodev.net>");

  MODULE_DESCRIPTION("Xtables: string-based matching");

  MODULE_LICENSE("GPL");

  MODULE_ALIAS("ipt_string");
  MODULE_ALIAS("ip6t_string");

  static bool

  string_mt(const struct sk_buff *skb, struct xt_action_param *par)

  {

  	const struct xt_string_info *conf = par->matchinfo;

  	struct ts_state state;

  	bool invert;

  
  	memset(&state, 0, sizeof(struct ts_state));

  	invert = conf->u.v1.flags & XT_STRING_FLAG_INVERT;

  	return (skb_find_text((struct sk_buff *)skb, conf->from_offset,
  			     conf->to_offset, conf->config, &state)

  			     != UINT_MAX) ^ invert;

  }

  #define STRING_TEXT_PRIV(m) ((struct xt_string_info *)(m))

  static int string_mt_check(const struct xt_mtchk_param *par)

  {

  	struct xt_string_info *conf = par->matchinfo;

  	struct ts_config *ts_conf;

  	int flags = TS_AUTOLOAD;

  	/* Damn, can't handle this case properly with iptables... */
  	if (conf->from_offset > conf->to_offset)

  		return -EINVAL;

  	if (conf->algo[XT_STRING_MAX_ALGO_NAME_SIZE - 1] != '\0')

  		return -EINVAL;

  	if (conf->patlen > XT_STRING_MAX_PATTERN_SIZE)

  		return -EINVAL;

  	if (conf->u.v1.flags &
  	    ~(XT_STRING_FLAG_IGNORECASE | XT_STRING_FLAG_INVERT))
  		return -EINVAL;
  	if (conf->u.v1.flags & XT_STRING_FLAG_IGNORECASE)
  		flags |= TS_IGNORECASE;

  	ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen,

  				     GFP_KERNEL, flags);

  	if (IS_ERR(ts_conf))

  		return PTR_ERR(ts_conf);

  
  	conf->config = ts_conf;

  	return 0;

  }

  static void string_mt_destroy(const struct xt_mtdtor_param *par)

  {

  	textsearch_destroy(STRING_TEXT_PRIV(par->matchinfo)->config);

  }

  static struct xt_match xt_string_mt_reg __read_mostly = {
  	.name       = "string",
  	.revision   = 1,
  	.family     = NFPROTO_UNSPEC,
  	.checkentry = string_mt_check,
  	.match      = string_mt,
  	.destroy    = string_mt_destroy,
  	.matchsize  = sizeof(struct xt_string_info),
  	.me         = THIS_MODULE,

  };

  static int __init string_mt_init(void)

  {

  	return xt_register_match(&xt_string_mt_reg);

  }

  static void __exit string_mt_exit(void)

  {

  	xt_unregister_match(&xt_string_mt_reg);

  }

  module_init(string_mt_init);
  module_exit(string_mt_exit);