/*
* Copyright (c) 1998-2007 The TCPDUMP project
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that: (1) source code
* distributions retain the above copyright notice and this paragraph
* in its entirety, and (2) distributions including binary code include
* the above copyright notice and this paragraph in its entirety in
* the documentation or other materials provided with the distribution.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND
* WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT
* LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE.
*
* Original code by Carles Kishimoto <[email protected]>
*/

/* \summary: Cisco UniDirectional Link Detection (UDLD) protocol printer */

/* specification: RFC 5171 */

#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: print-udld.c,v 1.5 2024/09/02 16:15:33 christos Exp $");
#endif

#include <config.h>

#include "netdissect-stdinc.h"

#define ND_LONGJMP_FROM_TCHECK
#include "netdissect.h"
#include "extract.h"


#define UDLD_HEADER_LEN                 4
#define UDLD_TLV_HEADER_LEN             4
#define UDLD_DEVICE_ID_TLV              0x0001
#define UDLD_PORT_ID_TLV                0x0002
#define UDLD_ECHO_TLV                   0x0003
#define UDLD_MESSAGE_INTERVAL_TLV       0x0004
#define UDLD_TIMEOUT_INTERVAL_TLV       0x0005
#define UDLD_DEVICE_NAME_TLV            0x0006
#define UDLD_SEQ_NUMBER_TLV             0x0007

static const struct tok udld_tlv_values[] = {
   { UDLD_DEVICE_ID_TLV, "Device-ID TLV"},
   { UDLD_PORT_ID_TLV, "Port-ID TLV"},
   { UDLD_ECHO_TLV, "Echo TLV"},
   { UDLD_MESSAGE_INTERVAL_TLV, "Message Interval TLV"},
   { UDLD_TIMEOUT_INTERVAL_TLV, "Timeout Interval TLV"},
   { UDLD_DEVICE_NAME_TLV, "Device Name TLV"},
   { UDLD_SEQ_NUMBER_TLV,"Sequence Number TLV"},
   { 0, NULL}
};

static const struct tok udld_code_values[] = {
   { 0x00, "Reserved"},
   { 0x01, "Probe message"},
   { 0x02, "Echo message"},
   { 0x03, "Flush message"},
   { 0, NULL}
};

static const struct tok udld_flags_bitmap_str[] = {
   { 1U << 0, "RT"    },
   { 1U << 1, "RSY"   },
   { 1U << 2, "MBZ-2" },
   { 1U << 3, "MBZ-3" },
   { 1U << 4, "MBZ-4" },
   { 1U << 5, "MBZ-5" },
   { 1U << 6, "MBZ-6" },
   { 1U << 7, "MBZ-7" },
   { 0, NULL}
};

/*
* UDLD's Protocol Data Unit format:
*
*  0                   1                   2                   3
*  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
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Ver | Opcode  |     Flags     |           Checksum            |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |               List of TLVs (variable length list)             |
* |                              ...                              |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
* TLV format:
*
*  0                   1                   2                   3
*  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
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |             TYPE              |            LENGTH             |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |                             VALUE                             |
* |                              ...                              |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
* LENGTH: Length in bytes of the Type, Length, and Value fields.
*/

#define UDLD_EXTRACT_VERSION(x) (((x)&0xe0)>>5)
#define UDLD_EXTRACT_OPCODE(x) ((x)&0x1f)

void
udld_print(netdissect_options *ndo,
          const u_char *tptr, u_int length)
{
   uint8_t ver, code, flags;

   ndo->ndo_protocol = "udld";
   if (length < UDLD_HEADER_LEN)
       goto invalid;

   ver = UDLD_EXTRACT_VERSION(GET_U_1(tptr));
   code = UDLD_EXTRACT_OPCODE(GET_U_1(tptr));
   tptr += 1;
   length -= 1;

   flags = GET_U_1(tptr);
   tptr += 1;
   length -= 1;

   ND_PRINT("UDLDv%u, Code %s (%x), Flags [%s] (0x%02x), length %u",
          ver,
          tok2str(udld_code_values, "Reserved", code),
          code,
          bittok2str(udld_flags_bitmap_str, "none", flags),
          flags,
          length + 2);

   /*
    * In non-verbose mode, just print version and opcode type
    */
   if (ndo->ndo_vflag < 1) {
       goto tcheck_remainder;
   }

   ND_PRINT("\n\tChecksum 0x%04x (unverified)", GET_BE_U_2(tptr));
   tptr += 2;
   length -= 2;

   while (length) {
       uint16_t type, len;

       if (length < UDLD_TLV_HEADER_LEN)
           goto invalid;

       type = GET_BE_U_2(tptr);
       tptr += 2;
       length -= 2;

       len  = GET_BE_U_2(tptr);
       tptr += 2;
       length -= 2;

       ND_PRINT("\n\t%s (0x%04x) TLV, length %u",
              tok2str(udld_tlv_values, "Unknown", type),
              type, len);

       /* infinite loop check */
       if (len <= UDLD_TLV_HEADER_LEN)
           goto invalid;

       len -= UDLD_TLV_HEADER_LEN;
       if (length < len)
           goto invalid;

       switch (type) {
       case UDLD_DEVICE_ID_TLV:
       case UDLD_PORT_ID_TLV:
       case UDLD_DEVICE_NAME_TLV:
           ND_PRINT(", ");
           nd_printjnp(ndo, tptr, len);
           break;

       case UDLD_ECHO_TLV:
           ND_PRINT(", ");
           (void)nd_printn(ndo, tptr, len, NULL);
           break;

       case UDLD_MESSAGE_INTERVAL_TLV:
       case UDLD_TIMEOUT_INTERVAL_TLV:
           if (len != 1)
               goto invalid;
           ND_PRINT(", %us", (GET_U_1(tptr)));
           break;

       case UDLD_SEQ_NUMBER_TLV:
           if (len != 4)
               goto invalid;
           ND_PRINT(", %u", GET_BE_U_4(tptr));
           break;

       default:
           ND_TCHECK_LEN(tptr, len);
           break;
       }
       tptr += len;
       length -= len;
   }

   return;

invalid:
   nd_print_invalid(ndo);
tcheck_remainder:
   ND_TCHECK_LEN(tptr, length);
}

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