print-null.c revision 1.4 
1/*
2 * Copyright (c) 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#include <sys/cdefs.h>
23#ifndef lint
24__RCSID("$NetBSD: print-null.c,v 1.4 2014/11/20 03:05:03 christos Exp $");
25#endif
26
27#define NETDISSECT_REWORKED
28#ifdef HAVE_CONFIG_H
29#include "config.h"
30#endif
31
32#include <tcpdump-stdinc.h>
33
34#include <string.h>
35
36#include "interface.h"
37#include "af.h"
38
39/*
40 * The DLT_NULL packet header is 4 bytes long. It contains a host-byte-order
41 * 32-bit integer that specifies the family, e.g. AF_INET.
42 *
43 * Note here that "host" refers to the host on which the packets were
44 * captured; that isn't necessarily *this* host.
45 *
46 * The OpenBSD DLT_LOOP packet header is the same, except that the integer
47 * is in network byte order.
48 */
49#define	NULL_HDRLEN 4
50
51/*
52 * Byte-swap a 32-bit number.
53 * ("htonl()" or "ntohl()" won't work - we want to byte-swap even on
54 * big-endian platforms.)
55 */
56#define	SWAPLONG(y) \
57((((y)&0xff)<<24) | (((y)&0xff00)<<8) | (((y)&0xff0000)>>8) | (((y)>>24)&0xff))
58
59static inline void
60null_hdr_print(netdissect_options *ndo, u_int family, u_int length)
61{
62	if (!ndo->ndo_qflag) {
63		ND_PRINT((ndo, "AF %s (%u)",
64			tok2str(bsd_af_values,"Unknown",family),family));
65	} else {
66		ND_PRINT((ndo, "%s",
67			tok2str(bsd_af_values,"Unknown AF %u",family)));
68	}
69
70	ND_PRINT((ndo, ", length %u: ", length));
71}
72
73/*
74 * This is the top level routine of the printer.  'p' points
75 * to the ether header of the packet, 'h->ts' is the timestamp,
76 * 'h->len' is the length of the packet off the wire, and 'h->caplen'
77 * is the number of bytes actually captured.
78 */
79u_int
80null_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char *p)
81{
82	u_int length = h->len;
83	u_int caplen = h->caplen;
84	u_int family;
85
86	if (caplen < NULL_HDRLEN) {
87		ND_PRINT((ndo, "[|null]"));
88		return (NULL_HDRLEN);
89	}
90
91	memcpy((char *)&family, (char *)p, sizeof(family));
92
93	/*
94	 * This isn't necessarily in our host byte order; if this is
95	 * a DLT_LOOP capture, it's in network byte order, and if
96	 * this is a DLT_NULL capture from a machine with the opposite
97	 * byte-order, it's in the opposite byte order from ours.
98	 *
99	 * If the upper 16 bits aren't all zero, assume it's byte-swapped.
100	 */
101	if ((family & 0xFFFF0000) != 0)
102		family = SWAPLONG(family);
103
104	if (ndo->ndo_eflag)
105		null_hdr_print(ndo, family, length);
106
107	length -= NULL_HDRLEN;
108	caplen -= NULL_HDRLEN;
109	p += NULL_HDRLEN;
110
111	switch (family) {
112
113	case BSD_AFNUM_INET:
114		ip_print(ndo, p, length);
115		break;
116
117#ifdef INET6
118	case BSD_AFNUM_INET6_BSD:
119	case BSD_AFNUM_INET6_FREEBSD:
120	case BSD_AFNUM_INET6_DARWIN:
121		ip6_print(ndo, p, length);
122		break;
123#endif
124
125	case BSD_AFNUM_ISO:
126		isoclns_print(ndo, p, length, caplen);
127		break;
128
129	case BSD_AFNUM_APPLETALK:
130		atalk_print(ndo, p, length);
131		break;
132
133	case BSD_AFNUM_IPX:
134		ipx_print(ndo, p, length);
135		break;
136
137	default:
138		/* unknown AF_ value */
139		if (!ndo->ndo_eflag)
140			null_hdr_print(ndo, family, length + NULL_HDRLEN);
141		if (!ndo->ndo_suppress_default_print)
142			ND_DEFAULTPRINT(p, caplen);
143	}
144
145	return (NULL_HDRLEN);
146}
147
148/*
149 * Local Variables:
150 * c-style: whitesmith
151 * c-basic-offset: 8
152 * End:
153 */
154