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 #include <string.h>
31 
32 #include "netdissect.h"
33 #include "af.h"
34 
35 /*
36  * The DLT_NULL packet header is 4 bytes long. It contains a host-byte-order
37  * 32-bit integer that specifies the family, e.g. AF_INET.
38  *
39  * Note here that "host" refers to the host on which the packets were
40  * captured; that isn't necessarily *this* host.
41  *
42  * The OpenBSD DLT_LOOP packet header is the same, except that the integer
43  * is in network byte order.
44  */
45 #define	NULL_HDRLEN 4
46 
47 /*
48  * Byte-swap a 32-bit number.
49  * ("htonl()" or "ntohl()" won't work - we want to byte-swap even on
50  * big-endian platforms.)
51  */
52 #define	SWAPLONG(y) \
53 ((((y)&0xff)<<24) | (((y)&0xff00)<<8) | (((y)&0xff0000)>>8) | (((y)>>24)&0xff))
54 
55 static inline void
null_hdr_print(netdissect_options * ndo,u_int family,u_int length)56 null_hdr_print(netdissect_options *ndo, u_int family, u_int length)
57 {
58 	if (!ndo->ndo_qflag) {
59 		ND_PRINT((ndo, "AF %s (%u)",
60 			tok2str(bsd_af_values,"Unknown",family),family));
61 	} else {
62 		ND_PRINT((ndo, "%s",
63 			tok2str(bsd_af_values,"Unknown AF %u",family)));
64 	}
65 
66 	ND_PRINT((ndo, ", length %u: ", length));
67 }
68 
69 /*
70  * This is the top level routine of the printer.  'p' points
71  * to the ether header of the packet, 'h->ts' is the timestamp,
72  * 'h->len' is the length of the packet off the wire, and 'h->caplen'
73  * is the number of bytes actually captured.
74  */
75 u_int
null_if_print(netdissect_options * ndo,const struct pcap_pkthdr * h,const u_char * p)76 null_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char *p)
77 {
78 	u_int length = h->len;
79 	u_int caplen = h->caplen;
80 	u_int family;
81 
82 	if (caplen < NULL_HDRLEN) {
83 		ND_PRINT((ndo, "[|null]"));
84 		return (NULL_HDRLEN);
85 	}
86 
87 	memcpy((char *)&family, (const char *)p, sizeof(family));
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 	return (NULL_HDRLEN);
140 }
141 
142 /*
143  * Local Variables:
144  * c-style: whitesmith
145  * c-basic-offset: 8
146  * End:
147  */
148