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 #define ND_LONGJMP_FROM_TCHECK
  29 #include "netdissect.h"
  30 #include "extract.h"
  31
  32
  33 #define UDLD_HEADER_LEN                 4
  34 #define UDLD_TLV_HEADER_LEN             4
  35 #define UDLD_DEVICE_ID_TLV              0x0001
  36 #define UDLD_PORT_ID_TLV                0x0002
  37 #define UDLD_ECHO_TLV                   0x0003
  38 #define UDLD_MESSAGE_INTERVAL_TLV       0x0004
  39 #define UDLD_TIMEOUT_INTERVAL_TLV       0x0005
  40 #define UDLD_DEVICE_NAME_TLV            0x0006
  41 #define UDLD_SEQ_NUMBER_TLV             0x0007
  42
  43 static const struct tok udld_tlv_values[] = {
  44     { UDLD_DEVICE_ID_TLV, "Device-ID TLV"},
  45     { UDLD_PORT_ID_TLV, "Port-ID TLV"},
  46     { UDLD_ECHO_TLV, "Echo TLV"},
  47     { UDLD_MESSAGE_INTERVAL_TLV, "Message Interval TLV"},
  48     { UDLD_TIMEOUT_INTERVAL_TLV, "Timeout Interval TLV"},
  49     { UDLD_DEVICE_NAME_TLV, "Device Name TLV"},
  50     { UDLD_SEQ_NUMBER_TLV,"Sequence Number TLV"},
  51     { 0, NULL}
  52 };
  53
  54 static const struct tok udld_code_values[] = {
  55     { 0x00, "Reserved"},
  56     { 0x01, "Probe message"},
  57     { 0x02, "Echo message"},
  58     { 0x03, "Flush message"},
  59     { 0, NULL}
  60 };
  61
  62 static const struct tok udld_flags_bitmap_str[] = {
  63     { 1U << 0, "RT"    },
  64     { 1U << 1, "RSY"   },
  65     { 1U << 2, "MBZ-2" },
  66     { 1U << 3, "MBZ-3" },
  67     { 1U << 4, "MBZ-4" },
  68     { 1U << 5, "MBZ-5" },
  69     { 1U << 6, "MBZ-6" },
  70     { 1U << 7, "MBZ-7" },
  71     { 0, NULL}
  72 };
  73
  74 /*
  75  * UDLD's Protocol Data Unit format:
  76  *
  77  *  0                   1                   2                   3
  78  *  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
  79  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  80  * | Ver | Opcode  |     Flags     |           Checksum            |
  81  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  82  * |               List of TLVs (variable length list)             |
  83  * |                              ...                              |
  84  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  85  *
  86  * TLV format:
  87  *
  88  *  0                   1                   2                   3
  89  *  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
  90  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  91  * |             TYPE              |            LENGTH             |
  92  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  93  * |                             VALUE                             |
  94  * |                              ...                              |
  95  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  96  *
  97  * LENGTH: Length in bytes of the Type, Length, and Value fields.
  98  */
  99
 100 #define UDLD_EXTRACT_VERSION(x) (((x)&0xe0)>>5)
 101 #define UDLD_EXTRACT_OPCODE(x) ((x)&0x1f)
 102
 103 void
 104 udld_print(netdissect_options *ndo,
 105            const u_char *tptr, u_int length)
 106 {
 107     uint8_t ver, code, flags;
 108
 109     ndo->ndo_protocol = "udld";
 110     if (length < UDLD_HEADER_LEN)
 111         goto invalid;
 112
 113     ver = UDLD_EXTRACT_VERSION(GET_U_1(tptr));
 114     code = UDLD_EXTRACT_OPCODE(GET_U_1(tptr));
 115     tptr += 1;
 116     length -= 1;
 117
 118     flags = GET_U_1(tptr);
 119     tptr += 1;
 120     length -= 1;
 121
 122     ND_PRINT("UDLDv%u, Code %s (%x), Flags [%s] (0x%02x), length %u",
 123            ver,
 124            tok2str(udld_code_values, "Reserved", code),
 125            code,
 126            bittok2str(udld_flags_bitmap_str, "none", flags),
 127            flags,
 128            length + 2);
 129
 130     /*
 131      * In non-verbose mode, just print version and opcode type
 132      */
 133     if (ndo->ndo_vflag < 1) {
 134         goto tcheck_remainder;
 135     }
 136
 137     ND_PRINT("\n\tChecksum 0x%04x (unverified)", GET_BE_U_2(tptr));
 138     tptr += 2;
 139     length -= 2;
 140
 141     while (length) {
 142         uint16_t type, len;
 143
 144         if (length < UDLD_TLV_HEADER_LEN)
 145             goto invalid;
 146
 147         type = GET_BE_U_2(tptr);
 148         tptr += 2;
 149         length -= 2;
 150
 151         len  = GET_BE_U_2(tptr);
 152         tptr += 2;
 153         length -= 2;
 154
 155         ND_PRINT("\n\t%s (0x%04x) TLV, length %u",
 156                tok2str(udld_tlv_values, "Unknown", type),
 157                type, len);
 158
 159         /* infinite loop check */
 160         if (len <= UDLD_TLV_HEADER_LEN)
 161             goto invalid;
 162
 163         len -= UDLD_TLV_HEADER_LEN;
 164         if (length < len)
 165             goto invalid;
 166
 167         switch (type) {
 168         case UDLD_DEVICE_ID_TLV:
 169         case UDLD_PORT_ID_TLV:
 170         case UDLD_DEVICE_NAME_TLV:
 171             ND_PRINT(", ");
 172             nd_printzp(ndo, tptr, len, NULL);
 173             break;
 174
 175         case UDLD_ECHO_TLV:
 176             ND_PRINT(", ");
 177             (void)nd_printn(ndo, tptr, len, NULL);
 178             break;
 179
 180         case UDLD_MESSAGE_INTERVAL_TLV:
 181         case UDLD_TIMEOUT_INTERVAL_TLV:
 182             if (len != 1)
 183                 goto invalid;
 184             ND_PRINT(", %us", (GET_U_1(tptr)));
 185             break;
 186
 187         case UDLD_SEQ_NUMBER_TLV:
 188             if (len != 4)
 189                 goto invalid;
 190             ND_PRINT(", %u", GET_BE_U_4(tptr));
 191             break;
 192
 193         default:
 194             ND_TCHECK_LEN(tptr, len);
 195             break;
 196         }
 197         tptr += len;
 198         length -= len;
 199     }
 200
 201     return;
 202
 203 invalid:
 204     nd_print_invalid(ndo);
 205 tcheck_remainder:
 206     ND_TCHECK_LEN(tptr, length);
 207 }