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