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 <pcap.h>
  29 #include <stdio.h>
  30 #include <string.h>
  31
  32 #include "interface.h"
  33
  34 #include "ip.h"
  35 #ifdef INET6
  36 #include "ip6.h"
  37 #endif
  38 #include "af.h"
  39
  40 /*
  41  * The DLT_NULL packet header is 4 bytes long. It contains a host-byte-order
  42  * 32-bit integer that specifies the family, e.g. AF_INET.
  43  *
  44  * Note here that "host" refers to the host on which the packets were
  45  * captured; that isn't necessarily *this* host.
  46  *
  47  * The OpenBSD DLT_LOOP packet header is the same, except that the integer
  48  * is in network byte order.
  49  */
  50 #define NULL_HDRLEN 4
  51
  52 /*
  53  * Byte-swap a 32-bit number.
  54  * ("htonl()" or "ntohl()" won't work - we want to byte-swap even on
  55  * big-endian platforms.)
  56  */
  57 #define SWAPLONG(y) \
  58 ((((y)&0xff)<<24) | (((y)&0xff00)<<8) | (((y)&0xff0000)>>8) | (((y)>>24)&0xff))
  59
  60 static inline void
  61 null_hdr_print(u_int family, u_int length)
  62 {
  63         if (!qflag) {
  64                 (void)printf("AF %s (%u)",
  65                         tok2str(bsd_af_values,"Unknown",family),family);
  66         } else {
  67                 (void)printf("%s",
  68                         tok2str(bsd_af_values,"Unknown AF %u",family));
  69         }
  70
  71         (void)printf(", length %u: ", length);
  72 }
  73
  74 /*
  75  * This is the top level routine of the printer.  'p' points
  76  * to the ether header of the packet, 'h->ts' is the timestamp,
  77  * 'h->len' is the length of the packet off the wire, and 'h->caplen'
  78  * is the number of bytes actually captured.
  79  */
  80 u_int
  81 null_if_print(const struct pcap_pkthdr *h, const u_char *p)
  82 {
  83         u_int length = h->len;
  84         u_int caplen = h->caplen;
  85         u_int family;
  86
  87         if (caplen < NULL_HDRLEN) {
  88                 printf("[|null]");
  89                 return (NULL_HDRLEN);
  90         }
  91
  92         memcpy((char *)&family, (char *)p, sizeof(family));
  93
  94         /*
  95          * This isn't necessarily in our host byte order; if this is
  96          * a DLT_LOOP capture, it's in network byte order, and if
  97          * this is a DLT_NULL capture from a machine with the opposite
  98          * byte-order, it's in the opposite byte order from ours.
  99          *
 100          * If the upper 16 bits aren't all zero, assume it's byte-swapped.
 101          */
 102         if ((family & 0xFFFF0000) != 0)
 103                 family = SWAPLONG(family);
 104
 105         if (eflag)
 106                 null_hdr_print(family, length);
 107
 108         length -= NULL_HDRLEN;
 109         caplen -= NULL_HDRLEN;
 110         p += NULL_HDRLEN;
 111
 112         switch (family) {
 113
 114         case BSD_AFNUM_INET:
 115                 ip_print(gndo, p, length);
 116                 break;
 117
 118 #ifdef INET6
 119         case BSD_AFNUM_INET6_BSD:
 120         case BSD_AFNUM_INET6_FREEBSD:
 121         case BSD_AFNUM_INET6_DARWIN:
 122                 ip6_print(gndo, p, length);
 123                 break;
 124 #endif
 125
 126         case BSD_AFNUM_ISO:
 127                 isoclns_print(p, length, caplen);
 128                 break;
 129
 130         case BSD_AFNUM_APPLETALK:
 131                 atalk_print(p, length);
 132                 break;
 133
 134         case BSD_AFNUM_IPX:
 135                 ipx_print(p, length);
 136                 break;
 137
 138         default:
 139                 /* unknown AF_ value */
 140                 if (!eflag)
 141                         null_hdr_print(family, length + NULL_HDRLEN);
 142                 if (!suppress_default_print)
 143                         default_print(p, caplen);
 144         }
 145
 146         return (NULL_HDRLEN);
 147 }
 148
 149 /*
 150  * Local Variables:
 151  * c-style: whitesmith
 152  * c-basic-offset: 8
 153  * End:
 154  */