The Tcpdump Group git mirrors - tcpdump/blob - print-udld.c

   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: Cisco UniDirectional Link Detection (UDLD) protocol printer */
  19
  20 /* specification: RFC 5171 */
  21
  22 #ifdef HAVE_CONFIG_H
  23 #include <config.h>
  24 #endif
  25
  26 #include "netdissect-stdinc.h"
  27
  28 #include "netdissect.h"
  29 #include "extract.h"
  30
  31
  32 #define UDLD_HEADER_LEN                 4
  33 #define UDLD_DEVICE_ID_TLV              0x0001
  34 #define UDLD_PORT_ID_TLV                0x0002
  35 #define UDLD_ECHO_TLV                   0x0003
  36 #define UDLD_MESSAGE_INTERVAL_TLV       0x0004
  37 #define UDLD_TIMEOUT_INTERVAL_TLV       0x0005
  38 #define UDLD_DEVICE_NAME_TLV            0x0006
  39 #define UDLD_SEQ_NUMBER_TLV             0x0007
  40
  41 static const struct tok udld_tlv_values[] = {
  42     { UDLD_DEVICE_ID_TLV, "Device-ID TLV"},
  43     { UDLD_PORT_ID_TLV, "Port-ID TLV"},
  44     { UDLD_ECHO_TLV, "Echo TLV"},
  45     { UDLD_MESSAGE_INTERVAL_TLV, "Message Interval TLV"},
  46     { UDLD_TIMEOUT_INTERVAL_TLV, "Timeout Interval TLV"},
  47     { UDLD_DEVICE_NAME_TLV, "Device Name TLV"},
  48     { UDLD_SEQ_NUMBER_TLV,"Sequence Number TLV"},
  49     { 0, NULL}
  50 };
  51
  52 static const struct tok udld_code_values[] = {
  53     { 0x00, "Reserved"},
  54     { 0x01, "Probe message"},
  55     { 0x02, "Echo message"},
  56     { 0x03, "Flush message"},
  57     { 0, NULL}
  58 };
  59
  60 static const struct tok udld_flags_bitmap_str[] = {
  61     { 1U << 0, "RT"    },
  62     { 1U << 1, "RSY"   },
  63     { 1U << 2, "MBZ-2" },
  64     { 1U << 3, "MBZ-3" },
  65     { 1U << 4, "MBZ-4" },
  66     { 1U << 5, "MBZ-5" },
  67     { 1U << 6, "MBZ-6" },
  68     { 1U << 7, "MBZ-7" },
  69     { 0, NULL}
  70 };
  71
  72 /*
  73  * UDLD's Protocol Data Unit format:
  74  *
  75  *  0                   1                   2                   3
  76  *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  77  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  78  * | Ver | Opcode  |     Flags     |           Checksum            |
  79  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  80  * |               List of TLVs (variable length list)             |
  81  * |                              ...                              |
  82  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  83  *
  84  * TLV format:
  85  *
  86  *  0                   1                   2                   3
  87  *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  88  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  89  * |             TYPE              |            LENGTH             |
  90  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  91  * |                             VALUE                             |
  92  * |                              ...                              |
  93  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  94  *
  95  * LENGTH: Length in bytes of the Type, Length, and Value fields.
  96  */
  97
  98 #define UDLD_EXTRACT_VERSION(x) (((x)&0xe0)>>5)
  99 #define UDLD_EXTRACT_OPCODE(x) ((x)&0x1f)
 100
 101 void
 102 udld_print(netdissect_options *ndo, const u_char *pptr, u_int length)
 103 {
 104     int code, type, len;
 105     const u_char *tptr;
 106
 107     ndo->ndo_protocol = "udld";
 108     if (length < UDLD_HEADER_LEN)
 109         goto trunc;
 110
 111     tptr = pptr;
 112
 113     ND_TCHECK_LEN(tptr, UDLD_HEADER_LEN);
 114
 115     code = UDLD_EXTRACT_OPCODE(GET_U_1(tptr));
 116
 117     ND_PRINT("UDLDv%u, Code %s (%x), Flags [%s] (0x%02x), length %u",
 118            UDLD_EXTRACT_VERSION(GET_U_1(tptr)),
 119            tok2str(udld_code_values, "Reserved", code),
 120            code,
 121            bittok2str(udld_flags_bitmap_str, "none", GET_U_1((tptr + 1))),
 122            GET_U_1((tptr + 1)),
 123            length);
 124
 125     /*
 126      * In non-verbose mode, just print version and opcode type
 127      */
 128     if (ndo->ndo_vflag < 1) {
 129         return;
 130     }
 131
 132     ND_PRINT("\n\tChecksum 0x%04x (unverified)", GET_BE_U_2(tptr + 2));
 133
 134     tptr += UDLD_HEADER_LEN;
 135
 136     while (tptr < (pptr+length)) {
 137
 138         type = GET_BE_U_2(tptr);
 139         len  = GET_BE_U_2(tptr + 2);
 140
 141         ND_PRINT("\n\t%s (0x%04x) TLV, length %u",
 142                tok2str(udld_tlv_values, "Unknown", type),
 143                type, len);
 144
 145         if (type == 0)
 146             goto invalid;
 147
 148         /* infinite loop check */
 149         if (len <= 4)
 150             goto invalid;
 151
 152         len -= 4;
 153         tptr += 4;
 154
 155         ND_TCHECK_LEN(tptr, len);
 156
 157         switch (type) {
 158         case UDLD_DEVICE_ID_TLV:
 159         case UDLD_PORT_ID_TLV:
 160         case UDLD_DEVICE_NAME_TLV:
 161             ND_PRINT(", ");
 162             nd_printzp(ndo, tptr, len, NULL);
 163             break;
 164
 165         case UDLD_ECHO_TLV:
 166             ND_PRINT(", ");
 167             (void)nd_printn(ndo, tptr, len, NULL);
 168             break;
 169
 170         case UDLD_MESSAGE_INTERVAL_TLV:
 171         case UDLD_TIMEOUT_INTERVAL_TLV:
 172             if (len != 1)
 173                 goto invalid;
 174             ND_PRINT(", %us", (GET_U_1(tptr)));
 175             break;
 176
 177         case UDLD_SEQ_NUMBER_TLV:
 178             if (len != 4)
 179                 goto invalid;
 180             ND_PRINT(", %u", GET_BE_U_4(tptr));
 181             break;
 182
 183         default:
 184             break;
 185         }
 186         tptr += len;
 187     }
 188
 189     return;
 190
 191 invalid:
 192     nd_print_invalid(ndo);
 193     return;
 194 trunc:
 195     nd_print_trunc(ndo);
 196 }