The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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