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   1 /*
   2  * Copyright (c) 1998-2007 The TCPDUMP project
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that: (1) source code
   6  * distributions retain the above copyright notice and this paragraph
   7  * in its entirety, and (2) distributions including binary code include
   8  * the above copyright notice and this paragraph in its entirety in
   9  * the documentation or other materials provided with the distribution.
  10  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND
  11  * WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT
  12  * LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  13  * FOR A PARTICULAR PURPOSE.
  14  *
  15  * Original code by Carles Kishimoto <carles.kishimoto@gmail.com>
  16  */
  17
  18 /* \summary: Dynamic Trunking Protocol (DTP) printer */
  19
  20 #include <config.h>
  21
  22 #include "netdissect-stdinc.h"
  23
  24 #define ND_LONGJMP_FROM_TCHECK
  25 #include "netdissect.h"
  26 #include "addrtoname.h"
  27 #include "extract.h"
  28
  29
  30 #define DTP_HEADER_LEN                  1
  31 #define DTP_DOMAIN_TLV                  0x0001
  32 #define DTP_STATUS_TLV                  0x0002
  33 #define DTP_DTP_TYPE_TLV                0x0003
  34 #define DTP_NEIGHBOR_TLV                0x0004
  35
  36 static const struct tok dtp_tlv_values[] = {
  37     { DTP_DOMAIN_TLV, "Domain" },
  38     { DTP_STATUS_TLV, "Status" },
  39     { DTP_DTP_TYPE_TLV, "DTP type" },
  40     { DTP_NEIGHBOR_TLV, "Neighbor" },
  41     { 0, NULL}
  42 };
  43
  44 void
  45 dtp_print(netdissect_options *ndo, const u_char *tptr, u_int length)
  46 {
  47     ndo->ndo_protocol = "dtp";
  48     if (length < DTP_HEADER_LEN) {
  49         ND_PRINT("[zero packet length]");
  50         goto invalid;
  51     }
  52
  53     ND_PRINT("DTPv%u, length %u",
  54            GET_U_1(tptr),
  55            length);
  56
  57     /*
  58      * In non-verbose mode, just print version.
  59      */
  60     if (ndo->ndo_vflag < 1) {
  61         return;
  62     }
  63
  64     tptr += DTP_HEADER_LEN;
  65     length -= DTP_HEADER_LEN;
  66
  67     while (length) {
  68         uint16_t type, len;
  69
  70         if (length < 4) {
  71             ND_PRINT("[%u bytes remaining]", length);
  72             goto invalid;
  73         }
  74         type = GET_BE_U_2(tptr);
  75         len  = GET_BE_U_2(tptr + 2);
  76        /* XXX: should not be but sometimes it is, see the test captures */
  77         if (type == 0)
  78             return;
  79         ND_PRINT("\n\t%s (0x%04x) TLV, length %u",
  80                tok2str(dtp_tlv_values, "Unknown", type),
  81                type, len);
  82
  83         /* infinite loop check */
  84         if (len < 4 || len > length) {
  85             ND_PRINT("[TLV length %u]", len);
  86             goto invalid;
  87         }
  88
  89         switch (type) {
  90         case DTP_DOMAIN_TLV:
  91                 ND_PRINT(", ");
  92                 nd_printjnp(ndo, tptr+4, len-4);
  93                 break;
  94
  95         case DTP_STATUS_TLV:
  96         case DTP_DTP_TYPE_TLV:
  97                 if (len != 5)
  98                     goto invalid;
  99                 ND_PRINT(", 0x%x", GET_U_1(tptr + 4));
 100                 break;
 101
 102         case DTP_NEIGHBOR_TLV:
 103                 if (len != 10)
 104                     goto invalid;
 105                 ND_PRINT(", %s", GET_MAC48_STRING(tptr+4));
 106                 break;
 107
 108         default:
 109             ND_TCHECK_LEN(tptr, len);
 110             break;
 111         }
 112         tptr += len;
 113         length -= len;
 114     }
 115     return;
 116
 117  invalid:
 118     nd_print_invalid(ndo);
 119     ND_TCHECK_LEN(tptr, length);
 120 }