Home | History | Annotate | Download | only in tcpdump 
      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
     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
     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