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 #include <config.h>
25
26 #include "netdissect-stdinc.h"
27
28 #define ND_LONGJMP_FROM_TCHECK
29 #include "netdissect.h"
30 #include "extract.h"
31 #include "af.h"
32
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 void
null_hdr_print(netdissect_options * ndo,uint32_t family,u_int length)55 null_hdr_print(netdissect_options *ndo, uint32_t family, u_int length)
56 {
57 if (!ndo->ndo_qflag) {
58 ND_PRINT("AF %s (%u)",
59 tok2str(bsd_af_values,"Unknown",family),family);
60 } else {
61 ND_PRINT("%s",
62 tok2str(bsd_af_values,"Unknown AF %u",family));
63 }
64
65 ND_PRINT(", 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 void
null_if_print(netdissect_options * ndo,const struct pcap_pkthdr * h,const u_char * p)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 uint32_t family;
80
81 ndo->ndo_protocol = "null";
82 ND_TCHECK_LEN(p, NULL_HDRLEN);
83 ndo->ndo_ll_hdr_len += NULL_HDRLEN;
84
85 family = GET_HE_U_4(p);
86
87 /*
88 * This isn't necessarily in our host byte order; if this is
89 * a DLT_LOOP capture, it's in network byte order, and if
90 * this is a DLT_NULL capture from a machine with the opposite
91 * byte-order, it's in the opposite byte order from ours.
92 *
93 * If the upper 16 bits aren't all zero, assume it's byte-swapped.
94 */
95 if ((family & 0xFFFF0000) != 0)
96 family = SWAPLONG(family);
97
98 if (ndo->ndo_eflag)
99 null_hdr_print(ndo, family, length);
100
101 length -= NULL_HDRLEN;
102 caplen -= NULL_HDRLEN;
103 p += NULL_HDRLEN;
104
105 switch (family) {
106
107 case BSD_AFNUM_INET:
108 ip_print(ndo, p, length);
109 break;
110
111 case BSD_AFNUM_INET6_BSD:
112 case BSD_AFNUM_INET6_FREEBSD:
113 case BSD_AFNUM_INET6_DARWIN:
114 ip6_print(ndo, p, length);
115 break;
116
117 case BSD_AFNUM_ISO:
118 isoclns_print(ndo, p, length);
119 break;
120
121 case BSD_AFNUM_APPLETALK:
122 atalk_print(ndo, p, length);
123 break;
124
125 case BSD_AFNUM_IPX:
126 ipx_print(ndo, p, length);
127 break;
128
129 default:
130 /* unknown AF_ value */
131 if (!ndo->ndo_eflag)
132 null_hdr_print(ndo, family, length + NULL_HDRLEN);
133 if (!ndo->ndo_suppress_default_print)
134 ND_DEFAULTPRINT(p, caplen);
135 }
136 }
137