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_values[] = {
  61     { 0x00, "RT"},
  62     { 0x01, "RSY"},
  63     { 0, NULL}
  64 };
  65
  66 /*
  67  * UDLD's Protocol Data Unit format:
  68  *
  69  *  0                   1                   2                   3
  70  *  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
  71  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  72  * | Ver | Opcode  |     Flags     |           Checksum            |
  73  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  74  * |               List of TLVs (variable length list)             |
  75  * |                              ...                              |
  76  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  77  *
  78  * TLV format:
  79  *
  80  *  0                   1                   2                   3
  81  *  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
  82  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  83  * |             TYPE              |            LENGTH             |
  84  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  85  * |                             VALUE                             |
  86  * |                              ...                              |
  87  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  88  *
  89  * LENGTH: Length in bytes of the Type, Length, and Value fields.
  90  */
  91
  92 #define UDLD_EXTRACT_VERSION(x) (((x)&0xe0)>>5)
  93 #define UDLD_EXTRACT_OPCODE(x) ((x)&0x1f)
  94
  95 void
  96 udld_print(netdissect_options *ndo, const u_char *pptr, u_int length)
  97 {
  98     int code, type, len;
  99     const u_char *tptr;
 100
 101     ndo->ndo_protocol = "udld";
 102     if (length < UDLD_HEADER_LEN)
 103         goto trunc;
 104
 105     tptr = pptr;
 106
 107     ND_TCHECK_LEN(tptr, UDLD_HEADER_LEN);
 108
 109     code = UDLD_EXTRACT_OPCODE(EXTRACT_U_1(tptr));
 110
 111     ND_PRINT("UDLDv%u, Code %s (%x), Flags [%s] (0x%02x), length %u",
 112            UDLD_EXTRACT_VERSION(EXTRACT_U_1(tptr)),
 113            tok2str(udld_code_values, "Reserved", code),
 114            code,
 115            bittok2str(udld_flags_values, "none", EXTRACT_U_1((tptr + 1))),
 116            EXTRACT_U_1((tptr + 1)),
 117            length);
 118
 119     /*
 120      * In non-verbose mode, just print version and opcode type
 121      */
 122     if (ndo->ndo_vflag < 1) {
 123         return;
 124     }
 125
 126     ND_PRINT("\n\tChecksum 0x%04x (unverified)", EXTRACT_BE_U_2(tptr + 2));
 127
 128     tptr += UDLD_HEADER_LEN;
 129
 130     while (tptr < (pptr+length)) {
 131
 132         ND_TCHECK_4(tptr);
 133         type = EXTRACT_BE_U_2(tptr);
 134         len  = EXTRACT_BE_U_2(tptr + 2);
 135
 136         ND_PRINT("\n\t%s (0x%04x) TLV, length %u",
 137                tok2str(udld_tlv_values, "Unknown", type),
 138                type, len);
 139
 140         if (type == 0)
 141             goto invalid;
 142
 143         /* infinite loop check */
 144         if (len <= 4)
 145             goto invalid;
 146
 147         len -= 4;
 148         tptr += 4;
 149
 150         ND_TCHECK_LEN(tptr, len);
 151
 152         switch (type) {
 153         case UDLD_DEVICE_ID_TLV:
 154         case UDLD_PORT_ID_TLV:
 155         case UDLD_DEVICE_NAME_TLV:
 156             ND_PRINT(", ");
 157             nd_printzp(ndo, tptr, len, NULL);
 158             break;
 159
 160         case UDLD_ECHO_TLV:
 161             ND_PRINT(", ");
 162             (void)nd_printn(ndo, tptr, len, NULL);
 163             break;
 164
 165         case UDLD_MESSAGE_INTERVAL_TLV:
 166         case UDLD_TIMEOUT_INTERVAL_TLV:
 167             if (len != 1)
 168                 goto invalid;
 169             ND_PRINT(", %us", (EXTRACT_U_1(tptr)));
 170             break;
 171
 172         case UDLD_SEQ_NUMBER_TLV:
 173             if (len != 4)
 174                 goto invalid;
 175             ND_PRINT(", %u", EXTRACT_BE_U_4(tptr));
 176             break;
 177
 178         default:
 179             break;
 180         }
 181         tptr += len;
 182     }
 183
 184     return;
 185
 186 invalid:
 187     nd_print_invalid(ndo);
 188     return;
 189 trunc:
 190     nd_print_trunc(ndo);
 191 }