/*      $NetBSD: ip_ecn.c,v 1.17 2017/12/09 08:03:07 pgoyette Exp $     */
/*      $KAME: ip_ecn.c,v 1.11 2001/05/03 16:09:29 itojun Exp $ */

/*
* Copyright (C) 1999 WIDE Project.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
* 3. Neither the name of the project nor the names of its contributors
*    may be used to endorse or promote products derived from this software
*    without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
/*
* ECN consideration on tunnel ingress/egress operation.
* http://www.aciri.org/floyd/papers/draft-ipsec-ecn-00.txt
*/

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ip_ecn.c,v 1.17 2017/12/09 08:03:07 pgoyette Exp $");

#ifdef _KERNEL_OPT
#include "opt_inet.h"
#endif

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/errno.h>
#include <sys/module.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#ifdef INET6
#include <netinet/ip6.h>
#endif

#include <netinet/ip_ecn.h>

/*
* modify outer ECN (TOS) field on ingress operation (tunnel encapsulation).
*/
void
ip_ecn_ingress(int mode, u_int8_t *outer, const u_int8_t *inner)
{
       if (!outer || !inner)
               panic("NULL pointer passed to ip_ecn_ingress");

       *outer = *inner;
       switch (mode) {
       case ECN_ALLOWED:               /* ECN allowed */
               *outer &= ~IPTOS_ECN_CE;
               break;
       case ECN_FORBIDDEN:             /* ECN forbidden */
               *outer &= ~(IPTOS_ECN_ECT0 | IPTOS_ECN_CE);
               break;
       case ECN_NOCARE:        /* no consideration to ECN */
               break;
       }
}

/*
* modify inner ECN (TOS) field on egress operation (tunnel decapsulation).
*/
void
ip_ecn_egress(int mode, const u_int8_t *outer, u_int8_t *inner)
{
       if (!outer || !inner)
               panic("NULL pointer passed to ip_ecn_egress");

       switch (mode) {
       case ECN_ALLOWED:
               if (*outer & IPTOS_ECN_CE)
                       *inner |= IPTOS_ECN_CE;
               break;
       case ECN_FORBIDDEN:             /* ECN forbidden */
       case ECN_NOCARE:        /* no consideration to ECN */
               break;
       }
}

#ifdef INET6
void
ip6_ecn_ingress(int mode, u_int32_t *outer, const u_int32_t *inner)
{
       u_int8_t outer8, inner8;

       if (!outer || !inner)
               panic("NULL pointer passed to ip6_ecn_ingress");

       outer8 = (ntohl(*outer) >> 20) & 0xff;
       inner8 = (ntohl(*inner) >> 20) & 0xff;
       ip_ecn_ingress(mode, &outer8, &inner8);
       *outer &= ~htonl(0xff << 20);
       *outer |= htonl((u_int32_t)outer8 << 20);
}

void
ip6_ecn_egress(int mode, const u_int32_t *outer, u_int32_t *inner)
{
       u_int8_t outer8, inner8;

       if (!outer || !inner)
               panic("NULL pointer passed to ip6_ecn_egress");

       outer8 = (ntohl(*outer) >> 20) & 0xff;
       inner8 = (ntohl(*inner) >> 20) & 0xff;
       ip_ecn_egress(mode, &outer8, &inner8);
       *inner &= ~htonl(0xff << 20);
       *inner |= htonl((u_int32_t)inner8 << 20);
}
#endif

MODULE(MODULE_CLASS_MISC, ip_ecn, NULL);

static int
ip_ecn_modcmd(modcmd_t cmd, void *arg)
{

       switch (cmd) {
       case MODULE_CMD_INIT:
       case MODULE_CMD_FINI:
               return 0;

       default:
               return ENOTTY;
       }
}