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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 #include <sys/cdefs.h>
     23 #ifndef lint
     24 __RCSID("$NetBSD: print-null.c,v 1.10 2024/09/02 16:15:32 christos Exp $");
     25 #endif
     26 
     27 /* \summary: BSD loopback device printer */
     28 
     29 #include <config.h>
     30 
     31 #include "netdissect-stdinc.h"
     32 
     33 #define ND_LONGJMP_FROM_TCHECK
     34 #include "netdissect.h"
     35 #include "extract.h"
     36 #include "af.h"
     37 
     38 
     39 /*
     40  * The DLT_NULL packet header is 4 bytes long. It contains a host-byte-order
     41  * 32-bit integer that specifies the family, e.g. AF_INET.
     42  *
     43  * Note here that "host" refers to the host on which the packets were
     44  * captured; that isn't necessarily *this* host.
     45  *
     46  * The OpenBSD DLT_LOOP packet header is the same, except that the integer
     47  * is in network byte order.
     48  */
     49 #define	NULL_HDRLEN 4
     50 
     51 /*
     52  * Byte-swap a 32-bit number.
     53  * ("htonl()" or "ntohl()" won't work - we want to byte-swap even on
     54  * big-endian platforms.)
     55  */
     56 #define	SWAPLONG(y) \
     57 ((((y)&0xff)<<24) | (((y)&0xff00)<<8) | (((y)&0xff0000)>>8) | (((y)>>24)&0xff))
     58 
     59 static void
     60 null_hdr_print(netdissect_options *ndo, uint32_t family, u_int length)
     61 {
     62 	if (!ndo->ndo_qflag) {
     63 		ND_PRINT("AF %s (%u)",
     64 			tok2str(bsd_af_values,"Unknown",family),family);
     65 	} else {
     66 		ND_PRINT("%s",
     67 			tok2str(bsd_af_values,"Unknown AF %u",family));
     68 	}
     69 
     70 	ND_PRINT(", length %u: ", length);
     71 }
     72 
     73 /*
     74  * This is the top level routine of the printer.  'p' points
     75  * to the ether header of the packet, 'h->ts' is the timestamp,
     76  * 'h->len' is the length of the packet off the wire, and 'h->caplen'
     77  * is the number of bytes actually captured.
     78  */
     79 void
     80 null_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char *p)
     81 {
     82 	u_int length = h->len;
     83 	u_int caplen = h->caplen;
     84 	uint32_t family;
     85 
     86 	ndo->ndo_protocol = "null";
     87 	ND_TCHECK_LEN(p, NULL_HDRLEN);
     88 	ndo->ndo_ll_hdr_len += NULL_HDRLEN;
     89 
     90 	family = GET_HE_U_4(p);
     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);
    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