tcpdump.tproj/print-gre.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * "Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
   7  * Reserved.  This file contains Original Code and/or Modifications of
   8  * Original Code as defined in and that are subject to the Apple Public
   9  * Source License Version 1.0 (the 'License').  You may not use this file
  10  * except in compliance with the License.  Please obtain a copy of the
  11  * License at http://www.apple.com/publicsource and read it before using
  12  * this file.
  13  *
  14  * The Original Code and all software distributed under the License are
  15  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  16  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  17  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  19  * License for the specific language governing rights and limitations
  20  * under the License."
  21  *
  22  * @APPLE_LICENSE_HEADER_END@
  23  */
  24 /*
  25  * Copyright (c) 1996
  26  *      The Regents of the University of California.  All rights reserved.
  27  *
  28  * Redistribution and use in source and binary forms are permitted
  29  * provided that the above copyright notice and this paragraph are
  30  * duplicated in all such forms and that any documentation,
  31  * advertising materials, and other materials related to such
  32  * distribution and use acknowledge that the software was developed
  33  * by the University of California, Lawrence Berkeley Laboratory,
  34  * Berkeley, CA.  The name of the University may not be used to
  35  * endorse or promote products derived from this software without
  36  * specific prior written permission.
  37  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  38  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  39  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  40  *
  41  * Initial contribution from John Hawkinson <jhawk@bbnplanet.com>
  42  *
  43  * This module implements support for decoding GRE (Generic Routing
  44  * Encapsulation) tunnels; they're documented in RFC1701 and RFC1702.
  45  * This code only supports the IP encapsulation thereof.
  46  */
  47
  48 #ifndef lint
  49 static const char rcsid[] =
  50     "@(#) $Header: /cvs/Darwin/Commands/NeXT/network_cmds/tcpdump.tproj/print-gre.c,v 1.1.1.1 1999/05/02 03:58:33 wsanchez Exp $";
  51 #endif
  52
  53 #include <sys/param.h>
  54 #include <sys/time.h>
  55 #include <sys/uio.h>
  56 #include <sys/socket.h>
  57
  58 #include <netinet/in.h>
  59 #include <netinet/in_systm.h>
  60 #include <netinet/ip.h>
  61
  62 #include <netdb.h>
  63 #include <stdio.h>
  64
  65 #include "interface.h"
  66 #include "addrtoname.h"
  67 #include "extract.h"            /* must come after interface.h */
  68
  69 #define GRE_SIZE (20)
  70
  71 struct gre {
  72         u_short flags;
  73         u_short proto;
  74         union {
  75                 struct gre_ckof {
  76                         u_short cksum;
  77                         u_short offset;
  78                 }        gre_ckof;
  79                 u_int32_t key;
  80                 u_int32_t seq;
  81         }     gre_void1;
  82         union {
  83                 u_int32_t key;
  84                 u_int32_t seq;
  85                 u_int32_t routing;
  86         }     gre_void2;
  87         union {
  88                 u_int32_t seq;
  89                 u_int32_t routing;
  90         }     gre_void3;
  91         union {
  92                 u_int32_t routing;
  93         }     gre_void4;
  94 };
  95
  96 #define GRE_CP          0x8000  /* Checksum Present */
  97 #define GRE_RP          0x4000  /* Routing Present */
  98 #define GRE_KP          0x2000  /* Key Present */
  99 #define GRE_SP          0x1000  /* Sequence Present */
 100
 101
 102 #define GREPROTO_IP     0x0800
 103
 104
 105 /*
 106  * Deencapsulate and print a GRE-tunneled IP datagram
 107  */
 108 void
 109 gre_print(const u_char *bp, u_int length)
 110 {
 111         const u_char *cp = bp + 4;
 112         const struct gre *gre;
 113         u_short flags, proto;
 114
 115         gre = (const struct gre *)bp;
 116
 117         if (length < GRE_SIZE) {
 118                 goto trunc;
 119         }
 120         flags = EXTRACT_16BITS(&gre->flags);
 121         proto = EXTRACT_16BITS(&gre->proto);
 122
 123         if (vflag) {
 124                 /* Decode the flags */
 125                 putchar('[');
 126                 if (flags & GRE_CP)
 127                         putchar('C');
 128                 if (flags & GRE_RP)
 129                         putchar('R');
 130                 if (flags & GRE_KP)
 131                         putchar('K');
 132                 if (flags & GRE_SP)
 133                         putchar('S');
 134                 fputs("] ", stdout);
 135         }
 136         /* Checksum & Offset are present */
 137         if ((flags & GRE_CP) | (flags & GRE_RP))
 138                 cp += 4;
 139
 140         /* We don't support routing fields (variable length) now. Punt. */
 141         if (flags & GRE_RP)
 142                 return;
 143
 144         if (flags & GRE_KP)
 145                 cp += 4;
 146         if (flags & GRE_SP)
 147                 cp += 4;
 148
 149         switch (proto) {
 150
 151         case GREPROTO_IP:
 152                 ip_print(cp, length - ((cp - bp) / sizeof(u_char)));
 153                 break;
 154
 155         default:
 156                 printf("gre-proto-0x%04X", proto);
 157                 break;
 158         }
 159         return;
 160
 161 trunc:
 162         fputs("[|gre]", stdout);
 163
 164 }