ip_ecn.c

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    1 /*      $KAME: ip_ecn.c,v 1.12 2002/01/07 11:34:47 kjc Exp $    */
    2 
    3 /*-
    4  * SPDX-License-Identifier: BSD-3-Clause
    5  *
    6  * Copyright (C) 1999 WIDE Project.
    7  * All rights reserved.
    8  *
    9  * Redistribution and use in source and binary forms, with or without
   10  * modification, are permitted provided that the following conditions
   11  * are met:
   12  * 1. Redistributions of source code must retain the above copyright
   13  *    notice, this list of conditions and the following disclaimer.
   14  * 2. Redistributions in binary form must reproduce the above copyright
   15  *    notice, this list of conditions and the following disclaimer in the
   16  *    documentation and/or other materials provided with the distribution.
   17  * 3. Neither the name of the project nor the names of its contributors
   18  *    may be used to endorse or promote products derived from this software
   19  *    without specific prior written permission.
   20  *
   21  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
   22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
   25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   31  * SUCH DAMAGE.
   32  *
   33  */
   34 /*
   35  * ECN consideration on tunnel ingress/egress operation.
   36  * http://www.aciri.org/floyd/papers/draft-ipsec-ecn-00.txt
   37  */
   38 
   39 #include <sys/cdefs.h>
   40 __FBSDID("$FreeBSD$");
   41 
   42 #include "opt_inet.h"
   43 #include "opt_inet6.h"
   44 
   45 #include <sys/param.h>
   46 #include <sys/systm.h>
   47 #include <sys/mbuf.h>
   48 #include <sys/errno.h>
   49 
   50 #include <netinet/in.h>
   51 #include <netinet/in_systm.h>
   52 #include <netinet/ip.h>
   53 #ifdef INET6
   54 #include <netinet/ip6.h>
   55 #endif
   56 
   57 #include <netinet/ip_ecn.h>
   58 #ifdef INET6
   59 #include <netinet6/ip6_ecn.h>
   60 #endif
   61 
   62 /*
   63  * ECN and TOS (or TCLASS) processing rules at tunnel encapsulation and
   64  * decapsulation from RFC3168:
   65  *
   66  *                      Outer Hdr at                 Inner Hdr at
   67  *                      Encapsulator                 Decapsulator
   68  *   Header fields:     --------------------         ------------
   69  *     DS Field         copied from inner hdr        no change
   70  *     ECN Field        constructed by (I)           constructed by (E)
   71  *
   72  * ECN_ALLOWED (full functionality):
   73  *    (I) if the ECN field in the inner header is set to CE, then set the
   74  *    ECN field in the outer header to ECT(0).
   75  *    otherwise, copy the ECN field to the outer header.
   76  *
   77  *    (E) if the ECN field in the outer header is set to CE and the ECN
   78  *    field of the inner header is not-ECT, drop the packet.
   79  *    if the ECN field in the inner header is set to ECT(0) or ECT(1)
   80  *    and the ECN field in the outer header is set to CE, then copy CE to
   81  *    the inner header.  otherwise, make no change to the inner header.
   82  *
   83  * ECN_FORBIDDEN (limited functionality):
   84  *    (I) set the ECN field to not-ECT in the outer header.
   85  *
   86  *    (E) if the ECN field in the outer header is set to CE, drop the packet.
   87  *    otherwise, make no change to the ECN field in the inner header.
   88  *
   89  * the drop rule is for backward compatibility and protection against
   90  * erasure of CE.
   91  */
   92 
   93 /*
   94  * modify outer ECN (TOS) field on ingress operation (tunnel encapsulation).
   95  */
   96 void
   97 ip_ecn_ingress(int mode, u_int8_t *outer, const u_int8_t *inner)
   98 {
   99 
  100         if (!outer || !inner)
  101                 panic("NULL pointer passed to ip_ecn_ingress");
  102 
  103         *outer = *inner;
  104         switch (mode) {
  105         case ECN_ALLOWED:               /* ECN allowed */
  106                 /*
  107                  * full-functionality: if the inner is CE, set ECT(0)
  108                  * to the outer.  otherwise, copy the ECN field.
  109                  */
  110                 if ((*inner & IPTOS_ECN_MASK) == IPTOS_ECN_CE)
  111                         *outer &= ~IPTOS_ECN_ECT1;
  112                 break;
  113         case ECN_FORBIDDEN:             /* ECN forbidden */
  114                 /*
  115                  * limited-functionality: set not-ECT to the outer
  116                  */
  117                 *outer &= ~IPTOS_ECN_MASK;
  118                 break;
  119         case ECN_NOCARE:        /* no consideration to ECN */
  120                 break;
  121         }
  122 }
  123 
  124 /*
  125  * modify inner ECN (TOS) field on egress operation (tunnel decapsulation).
  126  * the caller should drop the packet if the return value is 0.
  127  */
  128 int
  129 ip_ecn_egress(int mode, const u_int8_t *outer, u_int8_t *inner)
  130 {
  131 
  132         if (!outer || !inner)
  133                 panic("NULL pointer passed to ip_ecn_egress");
  134 
  135         switch (mode) {
  136         case ECN_ALLOWED:
  137                 /*
  138                  * full-functionality: if the outer is CE and the inner is
  139                  * not-ECT, should drop it.  otherwise, copy CE.
  140                  */
  141                 if ((*outer & IPTOS_ECN_MASK) == IPTOS_ECN_CE) {
  142                         if ((*inner & IPTOS_ECN_MASK) == IPTOS_ECN_NOTECT)
  143                                 return (0);
  144                         *inner |= IPTOS_ECN_CE;
  145                 }
  146                 break;
  147         case ECN_FORBIDDEN:             /* ECN forbidden */
  148                 /*
  149                  * limited-functionality: if the outer is CE, should drop it.
  150                  * otherwise, leave the inner.
  151                  */
  152                 if ((*outer & IPTOS_ECN_MASK) == IPTOS_ECN_CE)
  153                         return (0);
  154                 break;
  155         case ECN_NOCARE:        /* no consideration to ECN */
  156                 break;
  157         }
  158         return (1);
  159 }
  160 
  161 #ifdef INET6
  162 void
  163 ip6_ecn_ingress(int mode, u_int32_t *outer, const u_int32_t *inner)
  164 {
  165         u_int8_t outer8, inner8;
  166 
  167         if (!outer || !inner)
  168                 panic("NULL pointer passed to ip6_ecn_ingress");
  169 
  170         inner8 = (ntohl(*inner) >> 20) & 0xff;
  171         ip_ecn_ingress(mode, &outer8, &inner8);
  172         *outer &= ~htonl(0xff << 20);
  173         *outer |= htonl((u_int32_t)outer8 << 20);
  174 }
  175 
  176 int
  177 ip6_ecn_egress(int mode, const u_int32_t *outer, u_int32_t *inner)
  178 {
  179         u_int8_t outer8, inner8, oinner8;
  180 
  181         if (!outer || !inner)
  182                 panic("NULL pointer passed to ip6_ecn_egress");
  183 
  184         outer8 = (ntohl(*outer) >> 20) & 0xff;
  185         inner8 = oinner8 = (ntohl(*inner) >> 20) & 0xff;
  186         if (ip_ecn_egress(mode, &outer8, &inner8) == 0)
  187                 return (0);
  188         if (inner8 != oinner8) {
  189                 *inner &= ~htonl(0xff << 20);
  190                 *inner |= htonl((u_int32_t)inner8 << 20);
  191         }
  192         return (1);
  193 }
  194 #endif

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FreeBSD/Linux Kernel Cross Reference sys/netinet/ip_ecn.c

FreeBSD/Linux Kernel Cross Reference
sys/netinet/ip_ecn.c