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 1.42 2002-06-01 23:50:33 guy Exp $ (LBL)";
  25 #endif
  26
  27 #ifdef HAVE_CONFIG_H
  28 #include "config.h"
  29 #endif
  30
  31 #include <sys/param.h>
  32 #include <sys/time.h>
  33 #include <sys/socket.h>
  34
  35 #include <netinet/in.h>
  36
  37 #include <pcap.h>
  38 #include <stdio.h>
  39 #include <string.h>
  40
  41 #include "interface.h"
  42 #include "addrtoname.h"
  43
  44 #include "ip.h"
  45 #ifdef INET6
  46 #include "ip6.h"
  47 #endif
  48
  49 #ifndef AF_NS
  50 #define AF_NS           6               /* XEROX NS protocols */
  51 #endif
  52
  53 /*
  54  * The DLT_NULL packet header is 4 bytes long. It contains a host-byte-order
  55  * 32-bit integer that specifies the family, e.g. AF_INET.
  56  *
  57  * Note here that "host" refers to the host on which the packets were
  58  * captured; that isn't necessarily *this* host.
  59  *
  60  * The OpenBSD DLT_LOOP packet header is the same, except that the integer
  61  * is in network byte order.
  62  */
  63 #define NULL_HDRLEN 4
  64
  65 static void
  66 null_print(u_int family, u_int length)
  67 {
  68         if (nflag)
  69                 printf("AF %u ", family);
  70         else {
  71                 switch (family) {
  72
  73                 case AF_INET:
  74                         printf("ip ");
  75                         break;
  76
  77 #ifdef INET6
  78                 case AF_INET6:
  79                         printf("ip6 ");
  80                         break;
  81 #endif
  82
  83                 case AF_NS:
  84                         printf("ns ");
  85                         break;
  86
  87                 default:
  88                         printf("AF %u ", family);
  89                         break;
  90                 }
  91         }
  92         printf("%d: ", length);
  93 }
  94
  95 /*
  96  * Byte-swap a 32-bit number.
  97  * ("htonl()" or "ntohl()" won't work - we want to byte-swap even on
  98  * big-endian platforms.)
  99  */
 100 #define SWAPLONG(y) \
 101 ((((y)&0xff)<<24) | (((y)&0xff00)<<8) | (((y)&0xff0000)>>8) | (((y)>>24)&0xff))
 102
 103 void
 104 null_if_print(u_char *user, const struct pcap_pkthdr *h, const u_char *p)
 105 {
 106         u_int length = h->len;
 107         u_int caplen = h->caplen;
 108         const struct ip *ip;
 109         u_int family;
 110
 111         ++infodelay;
 112         ts_print(&h->ts);
 113
 114         memcpy((char *)&family, (char *)p, sizeof(family));
 115
 116         /*
 117          * This isn't necessarily in our host byte order; if this is
 118          * a DLT_LOOP capture, it's in network byte order, and if
 119          * this is a DLT_NULL capture from a machine with the opposite
 120          * byte-order, it's in the opposite byte order from ours.
 121          *
 122          * If the upper 16 bits aren't all zero, assume it's byte-swapped.
 123          */
 124         if ((family & 0xFFFF0000) != 0)
 125                 family = SWAPLONG(family);
 126
 127         /*
 128          * Some printers want to get back at the link level addresses,
 129          * and/or check that they're not walking off the end of the packet.
 130          * Rather than pass them all the way down, we set these globals.
 131          */
 132         packetp = p;
 133         snapend = p + caplen;
 134
 135         length -= NULL_HDRLEN;
 136
 137         ip = (struct ip *)(p + NULL_HDRLEN);
 138
 139         if (eflag)
 140                 null_print(family, length);
 141
 142         switch (IP_V(ip)) {
 143         case 4:
 144                 ip_print((const u_char *)ip, length);
 145                 break;
 146 #ifdef INET6
 147         case 6:
 148                 ip6_print((const u_char *)ip, length);
 149                 break;
 150 #endif /* INET6 */
 151         default:
 152                 printf("ip v%d", IP_V(ip));
 153                 break;
 154         }
 155
 156         if (xflag)
 157                 default_print((const u_char *)ip, caplen - NULL_HDRLEN);
 158         putchar('\n');
 159         --infodelay;
 160         if (infoprint)
 161                 info(0);
 162 }
 163