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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  * UNIDIRECTIONAL LINK DETECTION (UDLD) as per
     16  * http://www.ietf.org/internet-drafts/draft-foschiano-udld-02.txt
     17  *
     18  * Original code by Carles Kishimoto <carles.kishimoto (at) gmail.com>
     19  */
     20 
     21 #define NETDISSECT_REWORKED
     22 #ifdef HAVE_CONFIG_H
     23 #include "config.h"
     24 #endif
     25 
     26 #include <tcpdump-stdinc.h>
     27 
     28 #include "interface.h"
     29 #include "extract.h"
     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  *
     67  * 0                   1                   2                   3
     68  * 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
     69  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     70  * | Ver | Opcode  |     Flags     |           Checksum            |
     71  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     72  * |               List of TLVs (variable length list)             |
     73  * |                              ...                              |
     74  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     75  *
     76  */
     77 
     78 #define	UDLD_EXTRACT_VERSION(x) (((x)&0xe0)>>5)
     79 #define	UDLD_EXTRACT_OPCODE(x) ((x)&0x1f)
     80 
     81 void
     82 udld_print (netdissect_options *ndo, const u_char *pptr, u_int length)
     83 {
     84     int code, type, len;
     85     const u_char *tptr;
     86 
     87     if (length < UDLD_HEADER_LEN)
     88         goto trunc;
     89 
     90     tptr = pptr;
     91 
     92     ND_TCHECK2(*tptr, UDLD_HEADER_LEN);
     93 
     94     code = UDLD_EXTRACT_OPCODE(*tptr);
     95 
     96     ND_PRINT((ndo, "UDLDv%u, Code %s (%x), Flags [%s] (0x%02x), length %u",
     97            UDLD_EXTRACT_VERSION(*tptr),
     98            tok2str(udld_code_values, "Reserved", code),
     99            code,
    100            bittok2str(udld_flags_values, "none", *(tptr+1)),
    101            *(tptr+1),
    102            length));
    103 
    104     /*
    105      * In non-verbose mode, just print version and opcode type
    106      */
    107     if (ndo->ndo_vflag < 1) {
    108 	return;
    109     }
    110 
    111     ND_PRINT((ndo, "\n\tChecksum 0x%04x (unverified)", EXTRACT_16BITS(tptr+2)));
    112 
    113     tptr += UDLD_HEADER_LEN;
    114 
    115     while (tptr < (pptr+length)) {
    116 
    117         ND_TCHECK2(*tptr, 4);
    118 
    119 	type = EXTRACT_16BITS(tptr);
    120         len  = EXTRACT_16BITS(tptr+2);
    121         len -= 4;
    122         tptr += 4;
    123 
    124         /* infinite loop check */
    125         if (type == 0 || len == 0) {
    126             return;
    127         }
    128 
    129         ND_PRINT((ndo, "\n\t%s (0x%04x) TLV, length %u",
    130                tok2str(udld_tlv_values, "Unknown", type),
    131                type, len));
    132 
    133         switch (type) {
    134         case UDLD_DEVICE_ID_TLV:
    135         case UDLD_PORT_ID_TLV:
    136         case UDLD_ECHO_TLV:
    137         case UDLD_DEVICE_NAME_TLV:
    138             ND_PRINT((ndo, ", %s", tptr));
    139             break;
    140 
    141         case UDLD_MESSAGE_INTERVAL_TLV:
    142         case UDLD_TIMEOUT_INTERVAL_TLV:
    143             ND_PRINT((ndo, ", %us", (*tptr)));
    144             break;
    145 
    146         case UDLD_SEQ_NUMBER_TLV:
    147             ND_PRINT((ndo, ", %u", EXTRACT_32BITS(tptr)));
    148             break;
    149 
    150         default:
    151             break;
    152         }
    153         tptr += len;
    154     }
    155 
    156     return;
    157 
    158  trunc:
    159     ND_PRINT((ndo, "[|udld]"));
    160 }
    161 
    162 /*
    163  * Local Variables:
    164  * c-style: whitesmith
    165  * c-basic-offset: 4
    166  * End:
    167  */
    168