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