dist/tcpdump/print-vjc.c

   1 /*      $NetBSD$        */
   2
   3 /*
   4  * Copyright (c) 1990, 1991, 1993, 1994, 1995, 1996, 1997
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that: (1) source code distributions
   9  * retain the above copyright notice and this paragraph in its entirety, (2)
  10  * distributions including binary code include the above copyright notice and
  11  * this paragraph in its entirety in the documentation or other materials
  12  * provided with the distribution, and (3) all advertising materials mentioning
  13  * features or use of this software display the following acknowledgement:
  14  * ``This product includes software developed by the University of California,
  15  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  16  * the University nor the names of its contributors may be used to endorse
  17  * or promote products derived from this software without specific prior
  18  * written permission.
  19  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  20  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  21  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  22  */
  23
  24 #ifdef HAVE_CONFIG_H
  25 #include "config.h"
  26 #endif
  27
  28 #include <sys/cdefs.h>
  29 #ifndef lint
  30 #if 0
  31 static const char rcsid[] _U_ =
  32     "@(#) Header: /tcpdump/master/tcpdump/print-vjc.c,v 1.15 2004/03/25 03:31:17 mcr Exp (LBL)";
  33 #else
  34 __RCSID("$NetBSD: tcpdump2rcsid.ex,v 1.1 2001/06/25 20:09:58 itojun Exp $");
  35 #endif
  36 #endif
  37
  38 #include <tcpdump-stdinc.h>
  39
  40 #include <pcap.h>
  41 #include <stdio.h>
  42
  43 #include "interface.h"
  44 #include "addrtoname.h"
  45
  46 #include "slcompress.h"
  47 #include "ppp.h"
  48
  49 /*
  50  * XXX - for BSD/OS PPP, what packets get supplied with a PPP header type
  51  * of PPP_VJC and what packets get supplied with a PPP header type of
  52  * PPP_VJNC?  PPP_VJNC is for "UNCOMPRESSED_TCP" packets, and PPP_VJC
  53  * is for COMPRESSED_TCP packets (PPP_IP is used for TYPE_IP packets).
  54  *
  55  * RFC 1144 implies that, on the wire, the packet type is *not* needed
  56  * for PPP, as different PPP protocol types can be used; it only needs
  57  * to be put on the wire for SLIP.
  58  *
  59  * It also indicates that, for compressed SLIP:
  60  *
  61  *      If the COMPRESSED_TCP bit is set in the first byte, it's
  62  *      a COMPRESSED_TCP packet; that byte is the change byte, and
  63  *      the COMPRESSED_TCP bit, 0x80, isn't used in the change byte.
  64  *
  65  *      If the upper 4 bits of the first byte are 7, it's an
  66  *      UNCOMPRESSED_TCP packet; that byte is the first byte of
  67  *      the UNCOMPRESSED_TCP modified IP header, with a connection
  68  *      number in the protocol field, and with the version field
  69  *      being 7, not 4.
  70  *
  71  *      Otherwise, the packet is an IPv4 packet (where the upper 4 bits
  72  *      of the packet are 4).
  73  *
  74  * So this routine looks as if it's sort-of intended to handle
  75  * compressed SLIP, although it doesn't handle UNCOMPRESSED_TCP
  76  * correctly for that (it doesn't fix the version number and doesn't
  77  * do anything to the protocol field), and doesn't check for COMPRESSED_TCP
  78  * packets correctly for that (you only check the first bit - see
  79  * B.1 in RFC 1144).
  80  *
  81  * But it's called for BSD/OS PPP, not SLIP - perhaps BSD/OS does weird
  82  * things with the headers?
  83  *
  84  * Without a BSD/OS VJC-compressed PPP trace, or knowledge of what the
  85  * BSD/OS VJC code does, we can't say what's the case.
  86  *
  87  * We therefore leave "proto" - which is the PPP protocol type - in place,
  88  * *not* marked as unused, for now, so that GCC warnings about the
  89  * unused argument remind us that we should fix this some day.
  90  */
  91 int
  92 vjc_print(register const char *bp, u_short proto _U_)
  93 {
  94         int i;
  95
  96         switch (bp[0] & 0xf0) {
  97         case TYPE_IP:
  98                 if (eflag)
  99                         printf("(vjc type=IP) ");
 100                 return PPP_IP;
 101         case TYPE_UNCOMPRESSED_TCP:
 102                 if (eflag)
 103                         printf("(vjc type=raw TCP) ");
 104                 return PPP_IP;
 105         case TYPE_COMPRESSED_TCP:
 106                 if (eflag)
 107                         printf("(vjc type=compressed TCP) ");
 108                 for (i = 0; i < 8; i++) {
 109                         if (bp[1] & (0x80 >> i))
 110                                 printf("%c", "?CI?SAWU"[i]);
 111                 }
 112                 if (bp[1])
 113                         printf(" ");
 114                 printf("C=0x%02x ", bp[2]);
 115                 printf("sum=0x%04x ", *(u_short *)&bp[3]);
 116                 return -1;
 117         case TYPE_ERROR:
 118                 if (eflag)
 119                         printf("(vjc type=error) ");
 120                 return -1;
 121         default:
 122                 if (eflag)
 123                         printf("(vjc type=0x%02x) ", bp[0] & 0xf0);
 124                 return -1;
 125         }
 126 }