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 /* \summary: BSD loopback device printer */
  23
  24 #ifdef HAVE_CONFIG_H
  25 #include <config.h>
  26 #endif
  27
  28 #include "netdissect-stdinc.h"
  29
  30 #define ND_LONGJMP_FROM_TCHECK
  31 #include "netdissect.h"
  32 #include "extract.h"
  33 #include "af.h"
  34
  35
  36 /*
  37  * The DLT_NULL packet header is 4 bytes long. It contains a host-byte-order
  38  * 32-bit integer that specifies the family, e.g. AF_INET.
  39  *
  40  * Note here that "host" refers to the host on which the packets were
  41  * captured; that isn't necessarily *this* host.
  42  *
  43  * The OpenBSD DLT_LOOP packet header is the same, except that the integer
  44  * is in network byte order.
  45  */
  46 #define NULL_HDRLEN 4
  47
  48 /*
  49  * Byte-swap a 32-bit number.
  50  * ("htonl()" or "ntohl()" won't work - we want to byte-swap even on
  51  * big-endian platforms.)
  52  */
  53 #define SWAPLONG(y) \
  54 ((((y)&0xff)<<24) | (((y)&0xff00)<<8) | (((y)&0xff0000)>>8) | (((y)>>24)&0xff))
  55
  56 static void
  57 null_hdr_print(netdissect_options *ndo, uint32_t family, u_int length)
  58 {
  59         if (!ndo->ndo_qflag) {
  60                 ND_PRINT("AF %s (%u)",
  61                         tok2str(bsd_af_values,"Unknown",family),family);
  62         } else {
  63                 ND_PRINT("%s",
  64                         tok2str(bsd_af_values,"Unknown AF %u",family));
  65         }
  66
  67         ND_PRINT(", length %u: ", length);
  68 }
  69
  70 /*
  71  * This is the top level routine of the printer.  'p' points
  72  * to the ether header of the packet, 'h->ts' is the timestamp,
  73  * 'h->len' is the length of the packet off the wire, and 'h->caplen'
  74  * is the number of bytes actually captured.
  75  */
  76 void
  77 null_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char *p)
  78 {
  79         u_int length = h->len;
  80         u_int caplen = h->caplen;
  81         uint32_t family;
  82
  83         ndo->ndo_protocol = "null";
  84         ND_TCHECK_LEN(p, NULL_HDRLEN);
  85         ndo->ndo_ll_hdr_len += NULL_HDRLEN;
  86
  87         family = GET_HE_U_4(p);
  88
  89         /*
  90          * This isn't necessarily in our host byte order; if this is
  91          * a DLT_LOOP capture, it's in network byte order, and if
  92          * this is a DLT_NULL capture from a machine with the opposite
  93          * byte-order, it's in the opposite byte order from ours.
  94          *
  95          * If the upper 16 bits aren't all zero, assume it's byte-swapped.
  96          */
  97         if ((family & 0xFFFF0000) != 0)
  98                 family = SWAPLONG(family);
  99
 100         if (ndo->ndo_eflag)
 101                 null_hdr_print(ndo, family, length);
 102
 103         length -= NULL_HDRLEN;
 104         caplen -= NULL_HDRLEN;
 105         p += NULL_HDRLEN;
 106
 107         switch (family) {
 108
 109         case BSD_AFNUM_INET:
 110                 ip_print(ndo, p, length);
 111                 break;
 112
 113         case BSD_AFNUM_INET6_BSD:
 114         case BSD_AFNUM_INET6_FREEBSD:
 115         case BSD_AFNUM_INET6_DARWIN:
 116                 ip6_print(ndo, p, length);
 117                 break;
 118
 119         case BSD_AFNUM_ISO:
 120                 isoclns_print(ndo, p, length);
 121                 break;
 122
 123         case BSD_AFNUM_APPLETALK:
 124                 atalk_print(ndo, p, length);
 125                 break;
 126
 127         case BSD_AFNUM_IPX:
 128                 ipx_print(ndo, p, length);
 129                 break;
 130
 131         default:
 132                 /* unknown AF_ value */
 133                 if (!ndo->ndo_eflag)
 134                         null_hdr_print(ndo, family, length + NULL_HDRLEN);
 135                 if (!ndo->ndo_suppress_default_print)
 136                         ND_DEFAULTPRINT(p, caplen);
 137         }
 138 }