contrib/tcpdump/print-null.c

   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  */