print-null.c revision 111729 
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 * $FreeBSD: head/contrib/tcpdump/print-null.c 111729 2003-03-02 08:25:48Z fenner $
22 */
23
24#ifndef lint
25static const char rcsid[] =
26    "@(#) $Header: /tcpdump/master/tcpdump/print-null.c,v 1.41.4.1 2002/06/01 23:51:15 guy Exp $ (LBL)";
27#endif
28
29#ifdef HAVE_CONFIG_H
30#include "config.h"
31#endif
32
33#include <sys/param.h>
34#include <sys/time.h>
35#include <sys/socket.h>
36
37#include <netinet/in.h>
38
39#include <pcap.h>
40#include <stdio.h>
41#include <string.h>
42
43#include "interface.h"
44#include "addrtoname.h"
45
46#include "ip.h"
47#ifdef INET6
48#include "ip6.h"
49#endif
50
51#ifndef AF_NS
52#define AF_NS		6		/* XEROX NS protocols */
53#endif
54
55/*
56 * The DLT_NULL packet header is 4 bytes long. It contains a host-byte-order
57 * 32-bit integer that specifies the family, e.g. AF_INET.
58 *
59 * Note here that "host" refers to the host on which the packets were
60 * captured; that isn't necessarily *this* host.
61 *
62 * The OpenBSD DLT_LOOP packet header is the same, except that the integer
63 * is in network byte order.
64 */
65#define	NULL_HDRLEN 4
66
67static void
68null_print(u_int family, u_int length)
69{
70	if (nflag)
71		printf("AF %u ", family);
72	else {
73		switch (family) {
74
75		case AF_INET:
76			printf("ip ");
77			break;
78
79#ifdef INET6
80		case AF_INET6:
81			printf("ip6 ");
82			break;
83#endif
84
85		case AF_NS:
86			printf("ns ");
87			break;
88
89		default:
90			printf("AF %u ", family);
91			break;
92		}
93	}
94	printf("%d: ", length);
95}
96
97/*
98 * Byte-swap a 32-bit number.
99 * ("htonl()" or "ntohl()" won't work - we want to byte-swap even on
100 * big-endian platforms.)
101 */
102#define	SWAPLONG(y) \
103((((y)&0xff)<<24) | (((y)&0xff00)<<8) | (((y)&0xff0000)>>8) | (((y)>>24)&0xff))
104
105void
106null_if_print(u_char *user, const struct pcap_pkthdr *h, const u_char *p)
107{
108	u_int length = h->len;
109	u_int caplen = h->caplen;
110	const struct ip *ip;
111	u_int family;
112
113	++infodelay;
114	ts_print(&h->ts);
115
116	memcpy((char *)&family, (char *)p, sizeof(family));
117
118	/*
119	 * This isn't necessarily in our host byte order; if this is
120	 * a DLT_LOOP capture, it's in network byte order, and if
121	 * this is a DLT_NULL capture from a machine with the opposite
122	 * byte-order, it's in the opposite byte order from ours.
123	 *
124	 * If the upper 16 bits aren't all zero, assume it's byte-swapped.
125	 */
126	if ((family & 0xFFFF0000) != 0)
127		family = SWAPLONG(family);
128
129	/*
130	 * Some printers want to get back at the link level addresses,
131	 * and/or check that they're not walking off the end of the packet.
132	 * Rather than pass them all the way down, we set these globals.
133	 */
134	packetp = p;
135	snapend = p + caplen;
136
137	length -= NULL_HDRLEN;
138
139	ip = (struct ip *)(p + NULL_HDRLEN);
140
141	if (eflag)
142		null_print(family, length);
143
144	switch (IP_V(ip)) {
145	case 4:
146		ip_print((const u_char *)ip, length);
147		break;
148#ifdef INET6
149	case 6:
150		ip6_print((const u_char *)ip, length);
151		break;
152#endif /* INET6 */
153	default:
154		printf("ip v%d", IP_V(ip));
155		break;
156	}
157
158	if (xflag)
159		default_print((const u_char *)ip, caplen - NULL_HDRLEN);
160	putchar('\n');
161	--infodelay;
162	if (infoprint)
163		info(0);
164}
165
166