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  * UNIDIRECTIONAL LINK DETECTION (UDLD) as per RFC5171
  16  *
  17  * Original code by Carles Kishimoto <carles.kishimoto@gmail.com>
  18  */
  19
  20 #ifdef HAVE_CONFIG_H
  21 #include "config.h"
  22 #endif
  23
  24 #include <netdissect-stdinc.h>
  25
  26 #include "netdissect.h"
  27 #include "extract.h"
  28
  29 static const char tstr[] = " [|udld]";
  30
  31 #define UDLD_HEADER_LEN                 4
  32 #define UDLD_DEVICE_ID_TLV              0x0001
  33 #define UDLD_PORT_ID_TLV                0x0002
  34 #define UDLD_ECHO_TLV                   0x0003
  35 #define UDLD_MESSAGE_INTERVAL_TLV       0x0004
  36 #define UDLD_TIMEOUT_INTERVAL_TLV       0x0005
  37 #define UDLD_DEVICE_NAME_TLV            0x0006
  38 #define UDLD_SEQ_NUMBER_TLV             0x0007
  39
  40 static const struct tok udld_tlv_values[] = {
  41     { UDLD_DEVICE_ID_TLV, "Device-ID TLV"},
  42     { UDLD_PORT_ID_TLV, "Port-ID TLV"},
  43     { UDLD_ECHO_TLV, "Echo TLV"},
  44     { UDLD_MESSAGE_INTERVAL_TLV, "Message Interval TLV"},
  45     { UDLD_TIMEOUT_INTERVAL_TLV, "Timeout Interval TLV"},
  46     { UDLD_DEVICE_NAME_TLV, "Device Name TLV"},
  47     { UDLD_SEQ_NUMBER_TLV,"Sequence Number TLV"},
  48     { 0, NULL}
  49 };
  50
  51 static const struct tok udld_code_values[] = {
  52     { 0x00, "Reserved"},
  53     { 0x01, "Probe message"},
  54     { 0x02, "Echo message"},
  55     { 0x03, "Flush message"},
  56     { 0, NULL}
  57 };
  58
  59 static const struct tok udld_flags_values[] = {
  60     { 0x00, "RT"},
  61     { 0x01, "RSY"},
  62     { 0, NULL}
  63 };
  64
  65 /*
  66  * UDLD's Protocol Data Unit format:
  67  *
  68  *  0                   1                   2                   3
  69  *  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
  70  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  71  * | Ver | Opcode  |     Flags     |           Checksum            |
  72  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  73  * |               List of TLVs (variable length list)             |
  74  * |                              ...                              |
  75  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  76  *
  77  * TLV format:
  78  *
  79  *  0                   1                   2                   3
  80  *  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
  81  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  82  * |             TYPE              |            LENGTH             |
  83  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  84  * |                             VALUE                             |
  85  * |                              ...                              |
  86  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  87  *
  88  * LENGTH: Length in bytes of the Type, Length, and Value fields.
  89  */
  90
  91 #define UDLD_EXTRACT_VERSION(x) (((x)&0xe0)>>5)
  92 #define UDLD_EXTRACT_OPCODE(x) ((x)&0x1f)
  93
  94 void
  95 udld_print (netdissect_options *ndo, const u_char *pptr, u_int length)
  96 {
  97     int code, type, len;
  98     const u_char *tptr;
  99
 100     if (length < UDLD_HEADER_LEN)
 101         goto trunc;
 102
 103     tptr = pptr;
 104
 105     ND_TCHECK2(*tptr, UDLD_HEADER_LEN);
 106
 107     code = UDLD_EXTRACT_OPCODE(*tptr);
 108
 109     ND_PRINT((ndo, "UDLDv%u, Code %s (%x), Flags [%s] (0x%02x), length %u",
 110            UDLD_EXTRACT_VERSION(*tptr),
 111            tok2str(udld_code_values, "Reserved", code),
 112            code,
 113            bittok2str(udld_flags_values, "none", *(tptr+1)),
 114            *(tptr+1),
 115            length));
 116
 117     /*
 118      * In non-verbose mode, just print version and opcode type
 119      */
 120     if (ndo->ndo_vflag < 1) {
 121         return;
 122     }
 123
 124     ND_PRINT((ndo, "\n\tChecksum 0x%04x (unverified)", EXTRACT_16BITS(tptr+2)));
 125
 126     tptr += UDLD_HEADER_LEN;
 127
 128     while (tptr < (pptr+length)) {
 129
 130         ND_TCHECK2(*tptr, 4);
 131         type = EXTRACT_16BITS(tptr);
 132         len  = EXTRACT_16BITS(tptr+2);
 133
 134         ND_PRINT((ndo, "\n\t%s (0x%04x) TLV, length %u",
 135                tok2str(udld_tlv_values, "Unknown", type),
 136                type, len));
 137
 138         if (type == 0)
 139             goto invalid;
 140
 141         /* infinite loop check */
 142         if (len <= 4)
 143             goto invalid;
 144
 145         len -= 4;
 146         tptr += 4;
 147
 148         ND_TCHECK2(*tptr, len);
 149
 150         switch (type) {
 151         case UDLD_DEVICE_ID_TLV:
 152         case UDLD_PORT_ID_TLV:
 153         case UDLD_DEVICE_NAME_TLV:
 154             ND_PRINT((ndo, ", "));
 155             fn_printzp(ndo, tptr, len, NULL);
 156             break;
 157
 158         case UDLD_ECHO_TLV:
 159             ND_PRINT((ndo, ", "));
 160             (void)fn_printn(ndo, tptr, len, NULL);
 161             break;
 162
 163         case UDLD_MESSAGE_INTERVAL_TLV:
 164         case UDLD_TIMEOUT_INTERVAL_TLV:
 165             if (len != 1)
 166                 goto invalid;
 167             ND_PRINT((ndo, ", %us", (*tptr)));
 168             break;
 169
 170         case UDLD_SEQ_NUMBER_TLV:
 171             if (len != 4)
 172                 goto invalid;
 173             ND_PRINT((ndo, ", %u", EXTRACT_32BITS(tptr)));
 174             break;
 175
 176         default:
 177             break;
 178         }
 179         tptr += len;
 180     }
 181
 182     return;
 183
 184 invalid:
 185     ND_PRINT((ndo, "%s", istr));
 186     return;
 187 trunc:
 188     ND_PRINT((ndo, "%s", tstr));
 189 }
 190
 191 /*
 192  * Local Variables:
 193  * c-style: whitesmith
 194  * c-basic-offset: 4
 195  * End:
 196  */