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 /*      $FreeBSD: src/sys/netinet/ip_ecn.c,v 1.6.4.1 2005/01/31 23:26:35 imp Exp $      */
    2 /*      $KAME: ip_ecn.c,v 1.12 2002/01/07 11:34:47 kjc Exp $    */
    3 
    4 /*-
    5  * Copyright (C) 1999 WIDE Project.
    6  * All rights reserved.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  * 3. Neither the name of the project nor the names of its contributors
   17  *    may be used to endorse or promote products derived from this software
   18  *    without specific prior written permission.
   19  *
   20  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
   21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
   24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   30  * SUCH DAMAGE.
   31  *
   32  */
   33 /*
   34  * ECN consideration on tunnel ingress/egress operation.
   35  * http://www.aciri.org/floyd/papers/draft-ipsec-ecn-00.txt
   36  */
   37 
   38 #include "opt_inet.h"
   39 #include "opt_inet6.h"
   40 
   41 #include <sys/param.h>
   42 #include <sys/systm.h>
   43 #include <sys/mbuf.h>
   44 #include <sys/errno.h>
   45 
   46 #include <netinet/in.h>
   47 #include <netinet/in_systm.h>
   48 #include <netinet/ip.h>
   49 #ifdef INET6
   50 #include <netinet/ip6.h>
   51 #endif
   52 
   53 #include <netinet/ip_ecn.h>
   54 #ifdef INET6
   55 #include <netinet6/ip6_ecn.h>
   56 #endif
   57 
   58 /*
   59  * ECN and TOS (or TCLASS) processing rules at tunnel encapsulation and
   60  * decapsulation from RFC3168:
   61  *
   62  *                      Outer Hdr at                 Inner Hdr at
   63  *                      Encapsulator                 Decapsulator
   64  *   Header fields:     --------------------         ------------
   65  *     DS Field         copied from inner hdr        no change
   66  *     ECN Field        constructed by (I)           constructed by (E)
   67  *
   68  * ECN_ALLOWED (full functionality):
   69  *    (I) if the ECN field in the inner header is set to CE, then set the
   70  *    ECN field in the outer header to ECT(0).
   71  *    otherwise, copy the ECN field to the outer header.
   72  *
   73  *    (E) if the ECN field in the outer header is set to CE and the ECN
   74  *    field of the inner header is not-ECT, drop the packet.
   75  *    if the ECN field in the inner header is set to ECT(0) or ECT(1)
   76  *    and the ECN field in the outer header is set to CE, then copy CE to
   77  *    the inner header.  otherwise, make no change to the inner header.
   78  *
   79  * ECN_FORBIDDEN (limited functionality):
   80  *    (I) set the ECN field to not-ECT in the outer header.
   81  *
   82  *    (E) if the ECN field in the outer header is set to CE, drop the packet.
   83  *    otherwise, make no change to the ECN field in the inner header.
   84  *
   85  * the drop rule is for backward compatibility and protection against
   86  * erasure of CE.
   87  */
   88 
   89 /*
   90  * modify outer ECN (TOS) field on ingress operation (tunnel encapsulation).
   91  */
   92 void
   93 ip_ecn_ingress(mode, outer, inner)
   94         int mode;
   95         u_int8_t *outer;
   96         const u_int8_t *inner;
   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(mode, outer, inner)
  128         int mode;
  129         const u_int8_t *outer;
  130         u_int8_t *inner;
  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(mode, outer, inner)
  164         int mode;
  165         u_int32_t *outer;
  166         const u_int32_t *inner;
  167 {
  168         u_int8_t outer8, inner8;
  169 
  170         if (!outer || !inner)
  171                 panic("NULL pointer passed to ip6_ecn_ingress");
  172 
  173         inner8 = (ntohl(*inner) >> 20) & 0xff;
  174         ip_ecn_ingress(mode, &outer8, &inner8);
  175         *outer &= ~htonl(0xff << 20);
  176         *outer |= htonl((u_int32_t)outer8 << 20);
  177 }
  178 
  179 int
  180 ip6_ecn_egress(mode, outer, inner)
  181         int mode;
  182         const u_int32_t *outer;
  183         u_int32_t *inner;
  184 {
  185         u_int8_t outer8, inner8, oinner8;
  186 
  187         if (!outer || !inner)
  188                 panic("NULL pointer passed to ip6_ecn_egress");
  189 
  190         outer8 = (ntohl(*outer) >> 20) & 0xff;
  191         inner8 = oinner8 = (ntohl(*inner) >> 20) & 0xff;
  192         if (ip_ecn_egress(mode, &outer8, &inner8) == 0)
  193                 return (0);
  194         if (inner8 != oinner8) {
  195                 *inner &= ~htonl(0xff << 20);
  196                 *inner |= htonl((u_int32_t)inner8 << 20);
  197         }
  198         return (1);
  199 }
  200 #endif

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