The Tcpdump Group git mirrors - tcpdump/blob - 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 #ifdef HAVE_CONFIG_H
  23 #include "config.h"
  24 #endif
  25
  26 #include <tcpdump-stdinc.h>
  27
  28 #include <string.h>
  29
  30 #include "interface.h"
  31 #include "af.h"
  32
  33 /*
  34  * The DLT_NULL packet header is 4 bytes long. It contains a host-byte-order
  35  * 32-bit integer that specifies the family, e.g. AF_INET.
  36  *
  37  * Note here that "host" refers to the host on which the packets were
  38  * captured; that isn't necessarily *this* host.
  39  *
  40  * The OpenBSD DLT_LOOP packet header is the same, except that the integer
  41  * is in network byte order.
  42  */
  43 #define NULL_HDRLEN 4
  44
  45 /*
  46  * Byte-swap a 32-bit number.
  47  * ("htonl()" or "ntohl()" won't work - we want to byte-swap even on
  48  * big-endian platforms.)
  49  */
  50 #define SWAPLONG(y) \
  51 ((((y)&0xff)<<24) | (((y)&0xff00)<<8) | (((y)&0xff0000)>>8) | (((y)>>24)&0xff))
  52
  53 static inline void
  54 null_hdr_print(netdissect_options *ndo, u_int family, u_int length)
  55 {
  56         if (!ndo->ndo_qflag) {
  57                 ND_PRINT((ndo, "AF %s (%u)",
  58                         tok2str(bsd_af_values,"Unknown",family),family));
  59         } else {
  60                 ND_PRINT((ndo, "%s",
  61                         tok2str(bsd_af_values,"Unknown AF %u",family)));
  62         }
  63
  64         ND_PRINT((ndo, ", length %u: ", length));
  65 }
  66
  67 /*
  68  * This is the top level routine of the printer.  'p' points
  69  * to the ether header of the packet, 'h->ts' is the timestamp,
  70  * 'h->len' is the length of the packet off the wire, and 'h->caplen'
  71  * is the number of bytes actually captured.
  72  */
  73 u_int
  74 null_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char *p)
  75 {
  76         u_int length = h->len;
  77         u_int caplen = h->caplen;
  78         u_int family;
  79
  80         if (caplen < NULL_HDRLEN) {
  81                 ND_PRINT((ndo, "[|null]"));
  82                 return (NULL_HDRLEN);
  83         }
  84
  85         memcpy((char *)&family, (const char *)p, sizeof(family));
  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, caplen);
 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         return (NULL_HDRLEN);
 138 }
 139
 140 /*
 141  * Local Variables:
 142  * c-style: whitesmith
 143  * c-basic-offset: 8
 144  * End:
 145  */