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