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 #ifndef lint
  23 static const char rcsid[] =
  24     "@(#) $Header: /tcpdump/master/tcpdump/print-null.c,v 1.47 2002-12-19 09:39:13 guy Exp $ (LBL)";
  25 #endif
  26
  27 #ifdef HAVE_CONFIG_H
  28 #include "config.h"
  29 #endif
  30
  31 #include <tcpdump-stdinc.h>
  32
  33 #include <pcap.h>
  34 #include <stdio.h>
  35 #include <string.h>
  36
  37 #include "interface.h"
  38 #include "addrtoname.h"
  39
  40 #include "ip.h"
  41 #ifdef INET6
  42 #include "ip6.h"
  43 #endif
  44
  45 #ifndef AF_NS
  46 #define AF_NS           6               /* XEROX NS protocols */
  47 #endif
  48
  49 /*
  50  * The DLT_NULL packet header is 4 bytes long. It contains a host-byte-order
  51  * 32-bit integer that specifies the family, e.g. AF_INET.
  52  *
  53  * Note here that "host" refers to the host on which the packets were
  54  * captured; that isn't necessarily *this* host.
  55  *
  56  * The OpenBSD DLT_LOOP packet header is the same, except that the integer
  57  * is in network byte order.
  58  */
  59 #define NULL_HDRLEN 4
  60
  61 static void
  62 null_print(u_int family, u_int length)
  63 {
  64         if (nflag)
  65                 printf("AF %u ", family);
  66         else {
  67                 switch (family) {
  68
  69                 case AF_INET:
  70                         printf("ip ");
  71                         break;
  72
  73 #ifdef INET6
  74                 case AF_INET6:
  75                         printf("ip6 ");
  76                         break;
  77 #endif
  78
  79                 case AF_NS:
  80                         printf("ns ");
  81                         break;
  82
  83                 default:
  84                         printf("AF %u ", family);
  85                         break;
  86                 }
  87         }
  88         printf("%d: ", length);
  89 }
  90
  91 /*
  92  * Byte-swap a 32-bit number.
  93  * ("htonl()" or "ntohl()" won't work - we want to byte-swap even on
  94  * big-endian platforms.)
  95  */
  96 #define SWAPLONG(y) \
  97 ((((y)&0xff)<<24) | (((y)&0xff00)<<8) | (((y)&0xff0000)>>8) | (((y)>>24)&0xff))
  98
  99 u_int
 100 null_if_print(const struct pcap_pkthdr *h, const u_char *p)
 101 {
 102         u_int length = h->len;
 103         const struct ip *ip;
 104         u_int family;
 105
 106         memcpy((char *)&family, (char *)p, sizeof(family));
 107
 108         /*
 109          * This isn't necessarily in our host byte order; if this is
 110          * a DLT_LOOP capture, it's in network byte order, and if
 111          * this is a DLT_NULL capture from a machine with the opposite
 112          * byte-order, it's in the opposite byte order from ours.
 113          *
 114          * If the upper 16 bits aren't all zero, assume it's byte-swapped.
 115          */
 116         if ((family & 0xFFFF0000) != 0)
 117                 family = SWAPLONG(family);
 118
 119         length -= NULL_HDRLEN;
 120
 121         ip = (struct ip *)(p + NULL_HDRLEN);
 122
 123         if (eflag)
 124                 null_print(family, length);
 125
 126         switch (IP_V(ip)) {
 127         case 4:
 128                 ip_print((const u_char *)ip, length);
 129                 break;
 130 #ifdef INET6
 131         case 6:
 132                 ip6_print((const u_char *)ip, length);
 133                 break;
 134 #endif /* INET6 */
 135         default:
 136                 printf("ip v%d", IP_V(ip));
 137                 break;
 138         }
 139
 140         return (NULL_HDRLEN);
 141 }
 142