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/* \summary: BSD loopback device printer */
23
24#ifdef HAVE_CONFIG_H
25#include <config.h>
26#endif
27
28#include "netdissect-stdinc.h"
29
30#define ND_LONGJMP_FROM_TCHECK
31#include "netdissect.h"
32#include "extract.h"
33#include "af.h"
34
35
36/*
37 * The DLT_NULL packet header is 4 bytes long. It contains a host-byte-order
38 * 32-bit integer that specifies the family, e.g. AF_INET.
39 *
40 * Note here that "host" refers to the host on which the packets were
41 * captured; that isn't necessarily *this* host.
42 *
43 * The OpenBSD DLT_LOOP packet header is the same, except that the integer
44 * is in network byte order.
45 */
46#define	NULL_HDRLEN 4
47
48/*
49 * Byte-swap a 32-bit number.
50 * ("htonl()" or "ntohl()" won't work - we want to byte-swap even on
51 * big-endian platforms.)
52 */
53#define	SWAPLONG(y) \
54((((y)&0xff)<<24) | (((y)&0xff00)<<8) | (((y)&0xff0000)>>8) | (((y)>>24)&0xff))
55
56static void
57null_hdr_print(netdissect_options *ndo, uint32_t family, u_int length)
58{
59	if (!ndo->ndo_qflag) {
60		ND_PRINT("AF %s (%u)",
61			tok2str(bsd_af_values,"Unknown",family),family);
62	} else {
63		ND_PRINT("%s",
64			tok2str(bsd_af_values,"Unknown AF %u",family));
65	}
66
67	ND_PRINT(", length %u: ", length);
68}
69
70/*
71 * This is the top level routine of the printer.  'p' points
72 * to the ether header of the packet, 'h->ts' is the timestamp,
73 * 'h->len' is the length of the packet off the wire, and 'h->caplen'
74 * is the number of bytes actually captured.
75 */
76void
77null_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char *p)
78{
79	u_int length = h->len;
80	u_int caplen = h->caplen;
81	uint32_t family;
82
83	ndo->ndo_protocol = "null";
84	ND_TCHECK_LEN(p, NULL_HDRLEN);
85	ndo->ndo_ll_hdr_len += NULL_HDRLEN;
86
87	family = GET_HE_U_4(p);
88
89	/*
90	 * This isn't necessarily in our host byte order; if this is
91	 * a DLT_LOOP capture, it's in network byte order, and if
92	 * this is a DLT_NULL capture from a machine with the opposite
93	 * byte-order, it's in the opposite byte order from ours.
94	 *
95	 * If the upper 16 bits aren't all zero, assume it's byte-swapped.
96	 */
97	if ((family & 0xFFFF0000) != 0)
98		family = SWAPLONG(family);
99
100	if (ndo->ndo_eflag)
101		null_hdr_print(ndo, family, length);
102
103	length -= NULL_HDRLEN;
104	caplen -= NULL_HDRLEN;
105	p += NULL_HDRLEN;
106
107	switch (family) {
108
109	case BSD_AFNUM_INET:
110		ip_print(ndo, p, length);
111		break;
112
113	case BSD_AFNUM_INET6_BSD:
114	case BSD_AFNUM_INET6_FREEBSD:
115	case BSD_AFNUM_INET6_DARWIN:
116		ip6_print(ndo, p, length);
117		break;
118
119	case BSD_AFNUM_ISO:
120		isoclns_print(ndo, p, length);
121		break;
122
123	case BSD_AFNUM_APPLETALK:
124		atalk_print(ndo, p, length);
125		break;
126
127	case BSD_AFNUM_IPX:
128		ipx_print(ndo, p, length);
129		break;
130
131	default:
132		/* unknown AF_ value */
133		if (!ndo->ndo_eflag)
134			null_hdr_print(ndo, family, length + NULL_HDRLEN);
135		if (!ndo->ndo_suppress_default_print)
136			ND_DEFAULTPRINT(p, caplen);
137	}
138}
139