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      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 #ifndef lint
     23 static const char rcsid[] _U_ =
     24     "@(#) $Header: /tcpdump/master/tcpdump/print-null.c,v 1.53.2.4 2007/02/26 13:31:33 hannes Exp $ (LBL)";
     25 #endif
     26 
     27 #ifdef HAVE_CONFIG_H
     28 #include "config.h"
     29 #endif
     30 
     31 #include <tcpdump-stdinc.h>
     32 
     33 #include <pcap.h>
     34 #include <stdio.h>
     35 #include <string.h>
     36 
     37 #include "interface.h"
     38 #include "addrtoname.h"
     39 #include "af.h"
     40 
     41 #include "ip.h"
     42 #ifdef INET6
     43 #include "ip6.h"
     44 #endif
     45 
     46 /*
     47  * The DLT_NULL packet header is 4 bytes long. It contains a host-byte-order
     48  * 32-bit integer that specifies the family, e.g. AF_INET.
     49  *
     50  * Note here that "host" refers to the host on which the packets were
     51  * captured; that isn't necessarily *this* host.
     52  *
     53  * The OpenBSD DLT_LOOP packet header is the same, except that the integer
     54  * is in network byte order.
     55  */
     56 #define	NULL_HDRLEN 4
     57 
     58 
     59 /*
     60  * Byte-swap a 32-bit number.
     61  * ("htonl()" or "ntohl()" won't work - we want to byte-swap even on
     62  * big-endian platforms.)
     63  */
     64 #define	SWAPLONG(y) \
     65 ((((y)&0xff)<<24) | (((y)&0xff00)<<8) | (((y)&0xff0000)>>8) | (((y)>>24)&0xff))
     66 
     67 static inline void
     68 null_hdr_print(u_int family, u_int length)
     69 {
     70 	if (!qflag) {
     71 		(void)printf("AF %s (%u)",
     72 			tok2str(bsd_af_values,"Unknown",family),family);
     73 	} else {
     74 		(void)printf("%s",
     75 			tok2str(bsd_af_values,"Unknown AF %u",family));
     76 	}
     77 
     78 	(void)printf(", length %u: ", length);
     79 }
     80 
     81 /*
     82  * This is the top level routine of the printer.  'p' points
     83  * to the ether header of the packet, 'h->ts' is the timestamp,
     84  * 'h->len' is the length of the packet off the wire, and 'h->caplen'
     85  * is the number of bytes actually captured.
     86  */
     87 u_int
     88 null_if_print(const struct pcap_pkthdr *h, const u_char *p)
     89 {
     90 	u_int length = h->len;
     91 	u_int caplen = h->caplen;
     92 	u_int family;
     93 
     94 	if (caplen < NULL_HDRLEN) {
     95 		printf("[|null]");
     96 		return (NULL_HDRLEN);
     97 	}
     98 
     99 	memcpy((char *)&family, (char *)p, sizeof(family));
    100 
    101 	/*
    102 	 * This isn't necessarily in our host byte order; if this is
    103 	 * a DLT_LOOP capture, it's in network byte order, and if
    104 	 * this is a DLT_NULL capture from a machine with the opposite
    105 	 * byte-order, it's in the opposite byte order from ours.
    106 	 *
    107 	 * If the upper 16 bits aren't all zero, assume it's byte-swapped.
    108 	 */
    109 	if ((family & 0xFFFF0000) != 0)
    110 		family = SWAPLONG(family);
    111 
    112 	if (eflag)
    113 		null_hdr_print(family, length);
    114 
    115 	length -= NULL_HDRLEN;
    116 	caplen -= NULL_HDRLEN;
    117 	p += NULL_HDRLEN;
    118 
    119 	switch (family) {
    120 
    121 	case BSD_AFNUM_INET:
    122 		ip_print(gndo, p, length);
    123 		break;
    124 
    125 #ifdef INET6
    126 	case BSD_AFNUM_INET6_BSD:
    127 	case BSD_AFNUM_INET6_FREEBSD:
    128 	case BSD_AFNUM_INET6_DARWIN:
    129 		ip6_print(p, length);
    130 		break;
    131 #endif
    132 
    133 	case BSD_AFNUM_ISO:
    134 		isoclns_print(p, length, caplen);
    135 		break;
    136 
    137 	case BSD_AFNUM_APPLETALK:
    138 		atalk_print(p, length);
    139 		break;
    140 
    141 	case BSD_AFNUM_IPX:
    142 		ipx_print(p, length);
    143 		break;
    144 
    145 	default:
    146 		/* unknown AF_ value */
    147 		if (!eflag)
    148 			null_hdr_print(family, length + NULL_HDRLEN);
    149 		if (!suppress_default_print)
    150 			default_print(p, caplen);
    151 	}
    152 
    153 	return (NULL_HDRLEN);
    154 }
    155 
    156 /*
    157  * Local Variables:
    158  * c-style: whitesmith
    159  * c-basic-offset: 8
    160  * End:
    161  */
    162