/* Kernel module to match one of a list of TCP/UDP(-Lite)/SCTP/DCCP ports:
     ports are in the same place so we can treat them as equal. */

  
  /* (C) 1999-2001 Paul `Rusty' Russell
   * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
   *
   * 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.
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/module.h>
  #include <linux/types.h>
  #include <linux/udp.h>
  #include <linux/skbuff.h>
  #include <linux/in.h>
  
  #include <linux/netfilter/xt_multiport.h>
  #include <linux/netfilter/x_tables.h>
  #include <linux/netfilter_ipv4/ip_tables.h>
  #include <linux/netfilter_ipv6/ip6_tables.h>
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");

  MODULE_DESCRIPTION("Xtables: multiple port matching for TCP, UDP, UDP-Lite, SCTP and DCCP");

  MODULE_ALIAS("ipt_multiport");
  MODULE_ALIAS("ip6t_multiport");

  /* Returns 1 if the port is matched by the test, 0 otherwise. */

  static inline bool

  ports_match_v1(const struct xt_multiport_v1 *minfo,
  	       u_int16_t src, u_int16_t dst)
  {
  	unsigned int i;
  	u_int16_t s, e;
  
  	for (i = 0; i < minfo->count; i++) {
  		s = minfo->ports[i];
  
  		if (minfo->pflags[i]) {
  			/* range port matching */
  			e = minfo->ports[++i];

  			pr_debug("src or dst matches with %d-%d?
  ", s, e);

  
  			if (minfo->flags == XT_MULTIPORT_SOURCE
  			    && src >= s && src <= e)

  				return true ^ minfo->invert;

  			if (minfo->flags == XT_MULTIPORT_DESTINATION
  			    && dst >= s && dst <= e)

  				return true ^ minfo->invert;

  			if (minfo->flags == XT_MULTIPORT_EITHER
  			    && ((dst >= s && dst <= e)
  				|| (src >= s && src <= e)))

  				return true ^ minfo->invert;

  		} else {
  			/* exact port matching */

  			pr_debug("src or dst matches with %d?
  ", s);

  
  			if (minfo->flags == XT_MULTIPORT_SOURCE
  			    && src == s)

  				return true ^ minfo->invert;

  			if (minfo->flags == XT_MULTIPORT_DESTINATION
  			    && dst == s)

  				return true ^ minfo->invert;

  			if (minfo->flags == XT_MULTIPORT_EITHER
  			    && (src == s || dst == s))

  				return true ^ minfo->invert;

  		}
  	}

  	return minfo->invert;

  }

  static bool

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

  {

  	const __be16 *pptr;
  	__be16 _ports[2];

  	const struct xt_multiport_v1 *multiinfo = par->matchinfo;

  	if (par->fragoff != 0)

  		return false;

  	pptr = skb_header_pointer(skb, par->thoff, sizeof(_ports), _ports);

  	if (pptr == NULL) {
  		/* We've been asked to examine this packet, and we
  		 * can't.  Hence, no choice but to drop.
  		 */

  		pr_debug("Dropping evil offset=0 tinygram.
  ");

  		par->hotdrop = true;

  		return false;

  	}
  
  	return ports_match_v1(multiinfo, ntohs(pptr[0]), ntohs(pptr[1]));
  }

  static inline bool

  check(u_int16_t proto,
        u_int8_t ip_invflags,
        u_int8_t match_flags,
        u_int8_t count)
  {

  	/* Must specify supported protocol, no unknown flags or bad count */
  	return (proto == IPPROTO_TCP || proto == IPPROTO_UDP

  		|| proto == IPPROTO_UDPLITE

  		|| proto == IPPROTO_SCTP || proto == IPPROTO_DCCP)

  		&& !(ip_invflags & XT_INV_PROTO)
  		&& (match_flags == XT_MULTIPORT_SOURCE
  		    || match_flags == XT_MULTIPORT_DESTINATION
  		    || match_flags == XT_MULTIPORT_EITHER)
  		&& count <= XT_MULTI_PORTS;
  }

  static int multiport_mt_check(const struct xt_mtchk_param *par)

  {

  	const struct ipt_ip *ip = par->entryinfo;
  	const struct xt_multiport_v1 *multiinfo = par->matchinfo;

  
  	return check(ip->proto, ip->invflags, multiinfo->flags,

  		     multiinfo->count) ? 0 : -EINVAL;

  }

  static int multiport_mt6_check(const struct xt_mtchk_param *par)

  {

  	const struct ip6t_ip6 *ip = par->entryinfo;
  	const struct xt_multiport_v1 *multiinfo = par->matchinfo;

  
  	return check(ip->proto, ip->invflags, multiinfo->flags,

  		     multiinfo->count) ? 0 : -EINVAL;

  }

  static struct xt_match multiport_mt_reg[] __read_mostly = {

  	{
  		.name		= "multiport",

  		.family		= NFPROTO_IPV4,

  		.revision	= 1,

  		.checkentry	= multiport_mt_check,
  		.match		= multiport_mt,

  		.matchsize	= sizeof(struct xt_multiport_v1),
  		.me		= THIS_MODULE,
  	},
  	{
  		.name		= "multiport",

  		.family		= NFPROTO_IPV6,

  		.revision	= 1,

  		.checkentry	= multiport_mt6_check,
  		.match		= multiport_mt,

  		.matchsize	= sizeof(struct xt_multiport_v1),
  		.me		= THIS_MODULE,
  	},

  };

  static int __init multiport_mt_init(void)

  {

  	return xt_register_matches(multiport_mt_reg,
  	       ARRAY_SIZE(multiport_mt_reg));

  }

  static void __exit multiport_mt_exit(void)

  {

  	xt_unregister_matches(multiport_mt_reg, ARRAY_SIZE(multiport_mt_reg));

  }

  module_init(multiport_mt_init);
  module_exit(multiport_mt_exit);