external/bsd/tcpdump/dist/print-loopback.c

   1 /*
   2  * This module implements decoding of the Loopback Protocol, originally
   3  * defined as the Configuration Testing Protocol. It is based on the following
   4  * specification:
   5  * http://www.mit.edu/people/jhawk/ctp.pdf
   6  *
   7  * Copyright (c) 2014 The TCPDUMP project
   8  * All rights reserved.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  20  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  21  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  22  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  23  * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  24  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  25  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  26  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  27  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  29  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  30  * POSSIBILITY OF SUCH DAMAGE.
  31  */
  32
  33 #include <sys/cdefs.h>
  34 #ifndef lint
  35 __RCSID("$NetBSD: print-loopback.c,v 1.2 2014/11/20 03:05:03 christos Exp $");
  36 #endif
  37
  38 #define NETDISSECT_REWORKED
  39 #ifdef HAVE_CONFIG_H
  40 #include "config.h"
  41 #endif
  42
  43 #include <tcpdump-stdinc.h>
  44
  45 #include "interface.h"
  46 #include "extract.h"
  47 #include "ether.h"
  48 #include "addrtoname.h"
  49
  50 static const char tstr[] = " [|loopback]";
  51 static const char cstr[] = " (corrupt)";
  52
  53 #define LOOPBACK_REPLY   1
  54 #define LOOPBACK_FWDDATA 2
  55
  56 static const struct tok fcode_str[] = {
  57         { LOOPBACK_REPLY,   "Reply"        },
  58         { LOOPBACK_FWDDATA, "Forward Data" },
  59         { 0, NULL }
  60 };
  61
  62 static void
  63 loopback_message_print(netdissect_options *ndo, const u_char *cp, const u_int len)
  64 {
  65         const u_char *ep = cp + len;
  66         uint16_t function;
  67
  68         if (len < 2)
  69                 goto corrupt;
  70         /* function */
  71         ND_TCHECK2(*cp, 2);
  72         function = EXTRACT_LE_16BITS(cp);
  73         cp += 2;
  74         ND_PRINT((ndo, ", %s", tok2str(fcode_str, " invalid (%u)", function)));
  75
  76         switch (function) {
  77                 case LOOPBACK_REPLY:
  78                         if (len < 4)
  79                                 goto corrupt;
  80                         /* receipt number */
  81                         ND_TCHECK2(*cp, 2);
  82                         ND_PRINT((ndo, ", receipt number %u", EXTRACT_LE_16BITS(cp)));
  83                         cp += 2;
  84                         /* data */
  85                         ND_PRINT((ndo, ", data (%u octets)", len - 4));
  86                         ND_TCHECK2(*cp, len - 4);
  87                         break;
  88                 case LOOPBACK_FWDDATA:
  89                         if (len < 8)
  90                                 goto corrupt;
  91                         /* forwarding address */
  92                         ND_TCHECK2(*cp, ETHER_ADDR_LEN);
  93                         ND_PRINT((ndo, ", forwarding address %s", etheraddr_string(ndo, cp)));
  94                         cp += ETHER_ADDR_LEN;
  95                         /* data */
  96                         ND_PRINT((ndo, ", data (%u octets)", len - 8));
  97                         ND_TCHECK2(*cp, len - 8);
  98                         break;
  99                 default:
 100                         ND_TCHECK2(*cp, len - 2);
 101                         break;
 102         }
 103         return;
 104
 105 corrupt:
 106         ND_PRINT((ndo, "%s", cstr));
 107         ND_TCHECK2(*cp, ep - cp);
 108         return;
 109 trunc:
 110         ND_PRINT((ndo, "%s", tstr));
 111 }
 112
 113 void
 114 loopback_print(netdissect_options *ndo, const u_char *cp, const u_int len)
 115 {
 116         const u_char *ep = cp + len;
 117         uint16_t skipCount;
 118
 119         ND_PRINT((ndo, "Loopback"));
 120         if (len < 2)
 121                 goto corrupt;
 122         /* skipCount */
 123         ND_TCHECK2(*cp, 2);
 124         skipCount = EXTRACT_LE_16BITS(cp);
 125         cp += 2;
 126         ND_PRINT((ndo, ", skipCount %u", skipCount));
 127         if (skipCount % 8)
 128                 ND_PRINT((ndo, " (bogus)"));
 129         if (skipCount > len - 2)
 130                 goto corrupt;
 131         loopback_message_print(ndo, cp + skipCount, len - 2 - skipCount);
 132         return;
 133
 134 corrupt:
 135         ND_PRINT((ndo, "%s", cstr));
 136         ND_TCHECK2(*cp, ep - cp);
 137         return;
 138 trunc:
 139         ND_PRINT((ndo, "%s", tstr));
 140 }
 141