print-null.c revision 1.6 
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 1.6 2017/01/24 23:29:14 christos Exp $");
25#endif
26
27#ifdef HAVE_CONFIG_H
28#include "config.h"
29#endif
30
31#include <netdissect-stdinc.h>
32
33#include <string.h>
34
35#include "netdissect.h"
36#include "af.h"
37
38/*
39 * The DLT_NULL packet header is 4 bytes long. It contains a host-byte-order
40 * 32-bit integer that specifies the family, e.g. AF_INET.
41 *
42 * Note here that "host" refers to the host on which the packets were
43 * captured; that isn't necessarily *this* host.
44 *
45 * The OpenBSD DLT_LOOP packet header is the same, except that the integer
46 * is in network byte order.
47 */
48#define	NULL_HDRLEN 4
49
50/*
51 * Byte-swap a 32-bit number.
52 * ("htonl()" or "ntohl()" won't work - we want to byte-swap even on
53 * big-endian platforms.)
54 */
55#define	SWAPLONG(y) \
56((((y)&0xff)<<24) | (((y)&0xff00)<<8) | (((y)&0xff0000)>>8) | (((y)>>24)&0xff))
57
58static inline void
59null_hdr_print(netdissect_options *ndo, u_int family, u_int length)
60{
61	if (!ndo->ndo_qflag) {
62		ND_PRINT((ndo, "AF %s (%u)",
63			tok2str(bsd_af_values,"Unknown",family),family));
64	} else {
65		ND_PRINT((ndo, "%s",
66			tok2str(bsd_af_values,"Unknown AF %u",family)));
67	}
68
69	ND_PRINT((ndo, ", length %u: ", length));
70}
71
72/*
73 * This is the top level routine of the printer.  'p' points
74 * to the ether header of the packet, 'h->ts' is the timestamp,
75 * 'h->len' is the length of the packet off the wire, and 'h->caplen'
76 * is the number of bytes actually captured.
77 */
78u_int
79null_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char *p)
80{
81	u_int length = h->len;
82	u_int caplen = h->caplen;
83	u_int family;
84
85	if (caplen < NULL_HDRLEN) {
86		ND_PRINT((ndo, "[|null]"));
87		return (NULL_HDRLEN);
88	}
89
90	memcpy((char *)&family, (const char *)p, sizeof(family));
91
92	/*
93	 * This isn't necessarily in our host byte order; if this is
94	 * a DLT_LOOP capture, it's in network byte order, and if
95	 * this is a DLT_NULL capture from a machine with the opposite
96	 * byte-order, it's in the opposite byte order from ours.
97	 *
98	 * If the upper 16 bits aren't all zero, assume it's byte-swapped.
99	 */
100	if ((family & 0xFFFF0000) != 0)
101		family = SWAPLONG(family);
102
103	if (ndo->ndo_eflag)
104		null_hdr_print(ndo, family, length);
105
106	length -= NULL_HDRLEN;
107	caplen -= NULL_HDRLEN;
108	p += NULL_HDRLEN;
109
110	switch (family) {
111
112	case BSD_AFNUM_INET:
113		ip_print(ndo, p, length);
114		break;
115
116	case BSD_AFNUM_INET6_BSD:
117	case BSD_AFNUM_INET6_FREEBSD:
118	case BSD_AFNUM_INET6_DARWIN:
119		ip6_print(ndo, p, length);
120		break;
121
122	case BSD_AFNUM_ISO:
123		isoclns_print(ndo, p, length, caplen);
124		break;
125
126	case BSD_AFNUM_APPLETALK:
127		atalk_print(ndo, p, length);
128		break;
129
130	case BSD_AFNUM_IPX:
131		ipx_print(ndo, p, length);
132		break;
133
134	default:
135		/* unknown AF_ value */
136		if (!ndo->ndo_eflag)
137			null_hdr_print(ndo, family, length + NULL_HDRLEN);
138		if (!ndo->ndo_suppress_default_print)
139			ND_DEFAULTPRINT(p, caplen);
140	}
141
142	return (NULL_HDRLEN);
143}
144
145/*
146 * Local Variables:
147 * c-style: whitesmith
148 * c-basic-offset: 8
149 * End:
150 */
151