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packet-cdp.c

/* packet-cdp.c
 * Routines for the disassembly of the "Cisco Discovery Protocol"
 * (c) Copyright Hannes R. Boehm <hannes@boehm.org>
 *
 * $Id: packet-cdp.c 18941 2006-08-17 20:32:06Z etxrab $
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#include "config.h"

#include <stdlib.h>
#include <string.h>

#include <glib.h>
#include <epan/packet.h>
#include <epan/strutil.h>

#include <epan/oui.h>
#include <epan/nlpid.h>


/*
 * See
 *
 *    http://www.cisco.com/univercd/cc/td/doc/product/lan/trsrb/frames.htm#xtocid12
 *
 * for some information on CDP.
 *
 * See
 *
 *    http://www.cisco.com/en/US/products/hw/switches/ps663/products_tech_note09186a0080094713.shtml#cdp
 *
 * for some more information on CDP version 2.
 */

/* Offsets in TLV structure. */
#define     TLV_TYPE    0
#define     TLV_LENGTH  2

static int proto_cdp = -1;
static int hf_cdp_version = -1;
static int hf_cdp_checksum = -1;
static int hf_cdp_ttl = -1;
static int hf_cdp_tlvtype = -1;
static int hf_cdp_tlvlength = -1;

static gint ett_cdp = -1;
static gint ett_cdp_tlv = -1;
static gint ett_cdp_address = -1;
static gint ett_cdp_capabilities = -1;

static dissector_handle_t data_handle;

static int
dissect_address_tlv(tvbuff_t *tvb, int offset, int length, proto_tree *tree);
static void
dissect_capabilities(tvbuff_t *tvb, int offset, int length, proto_tree *tree);
static void
add_multi_line_string_to_tree(proto_tree *tree, tvbuff_t *tvb, gint start,
  gint len, const gchar *prefix);

#define TYPE_DEVICE_ID        0x0001
#define TYPE_ADDRESS          0x0002
#define TYPE_PORT_ID          0x0003
#define TYPE_CAPABILITIES     0x0004
#define TYPE_IOS_VERSION      0x0005
#define TYPE_PLATFORM         0x0006
#define TYPE_IP_PREFIX        0x0007
#define TYPE_PROTOCOL_HELLO     0x0008 /* Protocol Hello */
#define TYPE_VTP_MGMT_DOMAIN    0x0009 /* VTP Domain, CTPv2 - see second URL */
#define TYPE_NATIVE_VLAN        0x000a /* Native VLAN, CTPv2 - see second URL */
#define TYPE_DUPLEX             0x000b /* Full/Half Duplex - see second URL */
/*                              0x000c */
/*                              0x000d */
#define TYPE_VOIP_VLAN_REPLY    0x000e /* VoIP VLAN reply */
#define TYPE_VOIP_VLAN_QUERY    0x000f /* VoIP VLAN query */
#define TYPE_POWER              0x0010 /* Power consumption */
#define TYPE_MTU                0x0011 /* MTU */
#define TYPE_TRUST_BITMAP       0x0012 /* Trust bitmap */
#define TYPE_UNTRUSTED_COS      0x0013 /* Untrusted port CoS */
#define TYPE_SYSTEM_NAME        0x0014 /* System Name */
#define TYPE_SYSTEM_OID         0x0015 /* System OID */
#define TYPE_MANAGEMENT_ADDR    0x0016 /* Management Address(es) */
#define TYPE_LOCATION           0x0017 /* Location */


static const value_string type_vals[] = {
      { TYPE_DEVICE_ID,       "Device ID" },
      { TYPE_ADDRESS,         "Addresses" },
      { TYPE_PORT_ID,         "Port ID" },
      { TYPE_CAPABILITIES,    "Capabilities" },
      { TYPE_IOS_VERSION,     "Software version" },
      { TYPE_PLATFORM,        "Platform" },
      { TYPE_IP_PREFIX,       "IP Prefix/Gateway (used for ODR)" },
      { TYPE_PROTOCOL_HELLO,  "Protocol Hello" },
      { TYPE_VTP_MGMT_DOMAIN, "VTP Management Domain" },
      { TYPE_NATIVE_VLAN,     "Native VLAN" },
      { TYPE_DUPLEX,          "Duplex" },
      { TYPE_VOIP_VLAN_REPLY, "VoIP VLAN Reply" },
      { TYPE_VOIP_VLAN_QUERY, "VoIP VLAN Query" },
      { TYPE_POWER,           "Power consumption" },
      { TYPE_MTU,             "MTU"},
      { TYPE_TRUST_BITMAP,    "Trust Bitmap" },
      { TYPE_UNTRUSTED_COS,   "Untrusted Port CoS" },
      { TYPE_SYSTEM_NAME,     "System Name" },
      { TYPE_SYSTEM_OID,      "System Object ID" },
      { TYPE_MANAGEMENT_ADDR, "Management Address" },
      { TYPE_LOCATION,        "Location" },
      { 0,                    NULL },
};

#define TYPE_HELLO_CLUSTER_MGMT    0x0112

static const value_string type_hello_vals[] = {
        { TYPE_HELLO_CLUSTER_MGMT,   "Cluster Management" },
      { 0,                    NULL },
};

static void
dissect_cdp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
    proto_item *ti;
    proto_tree *cdp_tree = NULL;
    int offset = 0;
    guint16 type;
    guint16 length;
    proto_item *tlvi;
    proto_tree *tlv_tree;
    int real_length;
    guint32 naddresses;
    int addr_length;
    guint32 ip_addr;

    if (check_col(pinfo->cinfo, COL_PROTOCOL))
        col_set_str(pinfo->cinfo, COL_PROTOCOL, "CDP");
    if (check_col(pinfo->cinfo, COL_INFO))
      col_clear(pinfo->cinfo, COL_INFO);

    if (tree){
        ti = proto_tree_add_item(tree, proto_cdp, tvb, offset, -1, FALSE);
      cdp_tree = proto_item_add_subtree(ti, ett_cdp);

      /* CDP header */
      proto_tree_add_item(cdp_tree, hf_cdp_version, tvb, offset, 1, FALSE);
      offset += 1;
      proto_tree_add_uint_format_value(cdp_tree, hf_cdp_ttl, tvb, offset, 1,
                               tvb_get_guint8(tvb, offset),
                               "%u seconds",
                               tvb_get_guint8(tvb, offset));
      offset += 1;
      proto_tree_add_item(cdp_tree, hf_cdp_checksum, tvb, offset, 2, FALSE);
      offset += 2;
      }
    else
      {
      offset += 4; /* The version/ttl/checksum fields from above */
      }

      while (tvb_reported_length_remaining(tvb, offset) != 0) {
          type = tvb_get_ntohs(tvb, offset + TLV_TYPE);
          length = tvb_get_ntohs(tvb, offset + TLV_LENGTH);
          if (length < 4) {
                if(tree) {
                tlvi = proto_tree_add_text(cdp_tree, tvb, offset, 4,
                  "TLV with invalid length %u (< 4)",
                  length);
                tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
                proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                        offset + TLV_TYPE, 2, type);
                proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                        offset + TLV_LENGTH, 2, length);
                }
                offset += 4;
                break;
          }

          switch (type) {

          case TYPE_DEVICE_ID:
            /* Device ID */

            if(check_col(pinfo->cinfo, COL_INFO))
                col_append_fstr(pinfo->cinfo, COL_INFO,
                            "Device ID: %s  ",
                            tvb_format_stringzpad(tvb, offset + 4,
                                            length - 4));

            if(tree){
                tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
                        length, "Device ID: %s",
                        tvb_format_stringzpad(tvb, offset + 4, length - 4));
                tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
                proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                        offset + TLV_TYPE, 2, type);
                proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                        offset + TLV_LENGTH, 2, length);
                proto_tree_add_text(tlv_tree, tvb, offset + 4,
                        length - 4, "Device ID: %s",
                        tvb_format_stringzpad(tvb, offset + 4, length - 4));
                }
                offset += length;
                break;

          case TYPE_PORT_ID:
            real_length = length;
            if (tvb_get_guint8(tvb, offset + real_length) != 0x00) {
                /* The length in the TLV doesn't appear to be the
                   length of the TLV, as the byte just past it
                   isn't the first byte of a 2-byte big-endian
                   small integer; make the length of the TLV the length
                   in the TLV, plus 4 bytes for the TLV type and length,
                   minus 1 because that's what makes one capture work. */
                real_length = length + 3;
            }

            if(check_col(pinfo->cinfo, COL_INFO))
                col_append_fstr(pinfo->cinfo, COL_INFO,
                            "Port ID: %s  ",
                            tvb_format_stringzpad(tvb, offset + 4,
                                            length - 4));

            if(tree){ 
            tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
                      real_length, "Port ID: %s",
                      tvb_format_text(tvb, offset + 4, real_length - 4));
            tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
            proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                      offset + TLV_TYPE, 2, type);
            proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                      offset + TLV_LENGTH, 2, length);
            proto_tree_add_text(tlv_tree, tvb, offset + 4,
                      real_length - 4,
                      "Sent through Interface: %s",
                      tvb_format_text(tvb, offset + 4, real_length - 4));
            }
            offset += real_length;
            break;

          if(tree){
            case TYPE_ADDRESS:
                /* Addresses */
                tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
                        length, "Addresses");
                tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
                proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                        offset + TLV_TYPE, 2, type);
                proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                        offset + TLV_LENGTH, 2, length);
                offset += 4;
                length -= 4;
                naddresses = tvb_get_ntohl(tvb, offset);
                proto_tree_add_text(tlv_tree, tvb, offset, 4,
                        "Number of addresses: %u", naddresses);
                offset += 4;
                length -= 4;
                while (naddresses != 0) {
                  addr_length = dissect_address_tlv(tvb, offset, length,
                            tlv_tree);
                  if (addr_length < 0)
                      break;
                  offset += addr_length;
                  length -= addr_length;
    
                  naddresses--;
                }
                offset += length;
                break;

            case TYPE_CAPABILITIES:
                tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
                        length, "Capabilities");
                tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
                proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                        offset + TLV_TYPE, 2, type);
                proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                        offset + TLV_LENGTH, 2, length);
                offset += 4;
                length -= 4;
                dissect_capabilities(tvb, offset, length, tlv_tree);
                offset += length;
                break;

            case TYPE_IOS_VERSION:
                tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
                        length, "Software Version");
                tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
                proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                        offset + TLV_TYPE, 2, type);
                proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                        offset + TLV_LENGTH, 2, length);
                add_multi_line_string_to_tree(tlv_tree, tvb, offset + 4,
                            length - 4, "Software Version: ");
                offset += length;
                break;

            case TYPE_PLATFORM:
                /* ??? platform */
                tlvi = proto_tree_add_text(cdp_tree, tvb,
                        offset, length, "Platform: %s",
                        tvb_format_text(tvb, offset + 4, length - 4));
                tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
                proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                        offset + TLV_TYPE, 2, type);
                proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                        offset + TLV_LENGTH, 2, length);
                proto_tree_add_text(tlv_tree, tvb, offset + 4,
                        length - 4, "Platform: %s",
                        tvb_format_text(tvb, offset + 4, length - 4));
                offset += length;
                break;

            case TYPE_IP_PREFIX:
                if (length == 8) {
                  /* if length is 8 then this is default gw not prefix */
                  tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
                        length, "ODR Default gateway: %s",
                        ip_to_str(tvb_get_ptr(tvb, offset+4, 4)));
                  tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
                  proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                        offset + TLV_TYPE, 2, type);
                  proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                        offset + TLV_LENGTH, 2, length);
                  proto_tree_add_text(tlv_tree, tvb, offset+4, 4,
                            "ODR Default gateway = %s",
                            ip_to_str(tvb_get_ptr(tvb, offset+4, 4)));
                  offset += 8;
                } else {  
                  tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
                        length, "IP Prefixes: %d",length/5);

                  /* the actual number of prefixes is (length-4)/5
                  but if the variable is not a "float" but "integer"
                  then length/5=(length-4)/5  :)  */

                  tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
                  proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                        offset + TLV_TYPE, 2, type);
                  proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                        offset + TLV_LENGTH, 2, length);
                  offset += 4;
                  length -= 4;
                  while (length > 0) {
                      proto_tree_add_text(tlv_tree, tvb, offset, 5,
                            "IP Prefix = %s/%u",
                            ip_to_str(tvb_get_ptr(tvb, offset, 4)),
                            tvb_get_guint8(tvb,offset+4));
                      offset += 5;
                      length -= 5;
                  }
                }
                break;

            case TYPE_PROTOCOL_HELLO:
              tlvi = proto_tree_add_text(cdp_tree, tvb,
                                   offset,length, "Protocol Hello: %s",
                                   val_to_str(tvb_get_ntohs(tvb, offset+7), type_hello_vals, "Unknown (0x%04x)"));
              tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
              proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                              offset + TLV_TYPE, 2, type);
              proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                              offset + TLV_LENGTH, 2, length);
              proto_tree_add_text(tlv_tree, tvb, offset+4, 3,
                              "OUI: 0x%06X (%s)",
                              tvb_get_ntoh24(tvb,offset+4),
                              val_to_str(tvb_get_ntoh24(tvb,offset+4), oui_vals, "Unknown"));
              proto_tree_add_text(tlv_tree, tvb, offset+7, 2,
                              "Protocol ID: 0x%04X (%s)",
                              tvb_get_ntohs(tvb, offset+7),
                              val_to_str(tvb_get_ntohs(tvb, offset+7), type_hello_vals, "Unknown"));
              switch(tvb_get_ntohs(tvb, offset+7)) {

              case TYPE_HELLO_CLUSTER_MGMT:
                /*            proto_tree_add_text(tlv_tree, tvb, offset+9,
                              length - 9, "Cluster Management");
                */
                ip_addr = tvb_get_ipv4(tvb, offset+9);
                proto_tree_add_text(tlv_tree, tvb, offset+9, 4,
                              "Cluster Master IP: %s",ip_to_str((guint8 *)&ip_addr));
                ip_addr = tvb_get_ipv4(tvb, offset+13);
                proto_tree_add_text(tlv_tree, tvb, offset+13, 4,
                              "UNKNOWN (IP?): 0x%08X (%s)",
                                ip_addr, ip_to_str((guint8 *)&ip_addr));
                proto_tree_add_text(tlv_tree, tvb, offset+17, 1,
                              "Version?: 0x%02X",
                              tvb_get_guint8(tvb, offset+17));
                proto_tree_add_text(tlv_tree, tvb, offset+18, 1,
                              "Sub Version?: 0x%02X",
                              tvb_get_guint8(tvb, offset+18));
                proto_tree_add_text(tlv_tree, tvb, offset+19, 1,
                              "Status?: 0x%02X",
                              tvb_get_guint8(tvb, offset+19));
                proto_tree_add_text(tlv_tree, tvb, offset+20, 1,
                              "UNKNOWN: 0x%02X",
                              tvb_get_guint8(tvb, offset+20));
                proto_tree_add_text(tlv_tree, tvb, offset+21, 6,
                              "Cluster Commander MAC: %s",
                              ether_to_str(tvb_get_ptr(tvb, offset+21, 6)));
                proto_tree_add_text(tlv_tree, tvb, offset+27, 6,
                              "Switch's MAC: %s",
                              ether_to_str(tvb_get_ptr(tvb, offset+27, 6)));
                proto_tree_add_text(tlv_tree, tvb, offset+33, 1,
                              "UNKNOWN: 0x%02X",
                              tvb_get_guint8(tvb, offset+33));
                proto_tree_add_text(tlv_tree, tvb, offset+34, 2,
                              "Management VLAN: %d",
                              tvb_get_ntohs(tvb, offset+34));
                break;
              default:
                proto_tree_add_text(tlv_tree, tvb, offset + 9,
                              length - 9, "Unknown");
                break;
              }
              offset += length;
              break;

             case TYPE_VTP_MGMT_DOMAIN:
                tlvi = proto_tree_add_text(cdp_tree, tvb,
                        offset, length, "VTP Management Domain: %s",
                        tvb_format_text(tvb, offset + 4, length - 4));
                tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
                proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                        offset + TLV_TYPE, 2, type);
                proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                        offset + TLV_LENGTH, 2, length);
                proto_tree_add_text(tlv_tree, tvb, offset + 4,
                        length - 4, "VTP Management Domain: %s",
                        tvb_format_text(tvb, offset + 4, length - 4));
                offset += length;
                break;

            case TYPE_NATIVE_VLAN:
                tlvi = proto_tree_add_text(cdp_tree, tvb,
                        offset, length, "Native VLAN: %u",
                                     tvb_get_ntohs(tvb, offset + 4));
                tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
                proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                        offset + TLV_TYPE, 2, type);
                proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                        offset + TLV_LENGTH, 2, length);
                proto_tree_add_text(tlv_tree, tvb, offset + 4,
                        length - 4, "Native VLAN: %u",
                              tvb_get_ntohs(tvb, offset + 4));
                offset += length;
                break;

            case TYPE_DUPLEX:
                tlvi = proto_tree_add_text(cdp_tree, tvb,
                        offset, length, "Duplex: %s",
                                     tvb_get_guint8(tvb, offset + 4) ?
                                     "Full" : "Half" );
                tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
                proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                        offset + TLV_TYPE, 2, type);
                proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                        offset + TLV_LENGTH, 2, length);
                proto_tree_add_text(tlv_tree, tvb, offset + 4,
                        length - 4, "Duplex: %s",
                              tvb_get_guint8(tvb, offset + 4) ?
                              "Full" : "Half" );
                offset += length;
                break;

            case TYPE_VOIP_VLAN_REPLY:
              if (length >= 7) {
                tlvi = proto_tree_add_text(cdp_tree, tvb,
                                     offset, length, "VoIP VLAN Reply: %u", tvb_get_ntohs(tvb, offset + 5));
              } else {
                /*
                 * XXX - what are these?  I've seen them in some captures;
                 * they have a length of 6, and run up to the end of
                 * the packet, so if we try to dissect it the same way
                 * we dissect the 7-byte ones, we report a malformed
                 * frame.
                 */
                tlvi = proto_tree_add_text(cdp_tree, tvb,
                                     offset, length, "VoIP VLAN Reply");
              }
              tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
              proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                              offset + TLV_TYPE, 2, type);
              proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                              offset + TLV_LENGTH, 2, length);
              proto_tree_add_text(tlv_tree, tvb, offset + 4,
                              1, "Data");
              if (length >= 7) {
                proto_tree_add_text(tlv_tree, tvb, offset + 5,
                              2, "Voice VLAN: %u",
                              tvb_get_ntohs(tvb, offset + 5));
              }
              offset += length;
              break;

            case TYPE_VOIP_VLAN_QUERY:
              if (length >= 7) {
                  tlvi = proto_tree_add_text(cdp_tree, tvb,
                                       offset, length, "VoIP VLAN Query: %u", tvb_get_ntohs(tvb, offset + 5));
              } else {
                /*
                 * XXX - what are these?  I've seen them in some captures;
                 * they have a length of 6, and run up to the end of
                 * the packet, so if we try to dissect it the same way
                 * we dissect the 7-byte ones, we report a malformed
                 * frame.
                 */
                tlvi = proto_tree_add_text(cdp_tree, tvb,
                                     offset, length, "VoIP VLAN Query");
              }
              tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
              proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                              offset + TLV_TYPE, 2, type);
              proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                              offset + TLV_LENGTH, 2, length);
              proto_tree_add_text(tlv_tree, tvb, offset + 4,
                              1, "Data");
              if (length >= 7) {
                proto_tree_add_text(tlv_tree, tvb, offset + 5,
                              2, "Voice VLAN: %u",
                              tvb_get_ntohs(tvb, offset + 5));
              }
              offset += length;
              break;

            case TYPE_POWER:
                tlvi = proto_tree_add_text(cdp_tree, tvb,
                        offset, length, "Power consumption: %u mW",
                                     tvb_get_ntohs(tvb, offset + 4));
                tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
                proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                        offset + TLV_TYPE, 2, type);
                proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                        offset + TLV_LENGTH, 2, length);
                proto_tree_add_text(tlv_tree, tvb, offset + 4,
                        length - 4, "Power consumption: %u mW",
                              tvb_get_ntohs(tvb, offset + 4));
                offset += length;
                break;

            case TYPE_MTU:
              tlvi = proto_tree_add_text(cdp_tree, tvb,
                                   offset, length, "MTU: %u",
                                   tvb_get_ntohl(tvb,offset + 4));
              tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
              proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                              offset + TLV_TYPE, 2, type);
              proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                              offset + TLV_LENGTH, 2, length);
              proto_tree_add_text(tlv_tree, tvb, offset + 4,
                              length - 4, "MTU: %u",
                              tvb_get_ntohl(tvb,offset + 4));
              offset += length;
              break;

            case TYPE_TRUST_BITMAP:
              tlvi = proto_tree_add_text(cdp_tree, tvb,
                                   offset, length, "Trust Bitmap: 0x%02X",
                                   tvb_get_guint8(tvb, offset + 4));
              tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
              proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                              offset + TLV_TYPE, 2, type);
              proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                              offset + TLV_LENGTH, 2, length);
              proto_tree_add_text(tlv_tree, tvb, offset + 4,
                              length - 4, "Trust Bitmap: %02x",
                              tvb_get_guint8(tvb, offset + 4));
              offset += length;
              break;

            case TYPE_UNTRUSTED_COS:
              tlvi = proto_tree_add_text(cdp_tree, tvb,
                                   offset, length, "Untrusted port CoS: 0x%02X",
                                   tvb_get_guint8(tvb, offset + 4));
              tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
              proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                              offset + TLV_TYPE, 2, type);
              proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                              offset + TLV_LENGTH, 2, length);
              proto_tree_add_text(tlv_tree, tvb, offset + 4,
                              length - 4, "Untrusted port CoS: %02x",
                              tvb_get_guint8(tvb, offset + 4));
              offset += length;
              break;

            case TYPE_SYSTEM_NAME:
              tlvi = proto_tree_add_text(cdp_tree, tvb,
                                   offset, length, "System Name: %s",
                                   tvb_format_text(tvb, offset + 4, length - 4));
              tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
              proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                              offset + TLV_TYPE, 2, type);
              proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                              offset + TLV_LENGTH, 2, length);
              proto_tree_add_text(tlv_tree, tvb, offset + 4,
                              length - 4, "System Name: %s",
                              tvb_format_text(tvb, offset + 4, length - 4));
              offset += length;
              break;

            case TYPE_SYSTEM_OID:
              tlvi = proto_tree_add_text(cdp_tree, tvb,
                                   offset, length, "System Object Identifier");
              tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
              proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                              offset + TLV_TYPE, 2, type);
              proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                              offset + TLV_LENGTH, 2, length);
              proto_tree_add_text(tlv_tree, tvb, offset + 4,
                              length - 4, "System Object Identifier: %s",
                              tvb_bytes_to_str(tvb, offset + 4, length - 4));
              offset += length;
              break;

            case TYPE_MANAGEMENT_ADDR:
              tlvi = proto_tree_add_text(cdp_tree, tvb,
                                   offset, length, "Management Addresses");
              tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
              proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                              offset + TLV_TYPE, 2, type);
              proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                              offset + TLV_LENGTH, 2, length);
              offset += 4;
              length -= 4;
              naddresses = tvb_get_ntohl(tvb, offset);
              proto_tree_add_text(tlv_tree, tvb, offset, 4,
                              "Number of addresses: %u", naddresses);
              offset += 4;
              length -= 4;
              while (naddresses != 0) {
                addr_length = dissect_address_tlv(tvb, offset, length,
                                          tlv_tree);
                if (addr_length < 0)
                  break;
                  offset += addr_length;
                length -= addr_length;

                naddresses--;
              }
              offset += length;
              break;

            case TYPE_LOCATION:
              tlvi = proto_tree_add_text(cdp_tree, tvb,
                                   offset, length, "Location: %s",
                                   tvb_format_text(tvb, offset + 5, length - 5));
              tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
              proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                              offset + TLV_TYPE, 2, type);
              proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                              offset + TLV_LENGTH, 2, length);
              proto_tree_add_text(tlv_tree, tvb, offset + 4,
                              1 , "UNKNOWN: 0x%02X",
                              tvb_get_guint8(tvb, offset + 4));
              proto_tree_add_text(tlv_tree, tvb, offset + 5,
                              length - 5, "Location: %s",
                              tvb_format_text(tvb, offset + 5, length - 5));
              offset += length;
              break;
              }

            default:
              tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
                        length, "Type: %s, length: %u",
                        val_to_str(type, type_vals, "Unknown (0x%04x)"),
                        length);
                tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
                proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
                        offset + TLV_TYPE, 2, type);
                proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
                        offset + TLV_LENGTH, 2, length);
                if (length > 4) {
                      proto_tree_add_text(tlv_tree, tvb, offset + 4,
                                  length - 4, "Data");
                } else
                      return;
                offset += length;
          }
      }
    call_dissector(data_handle, tvb_new_subset(tvb, offset, -1, -1), pinfo,
                  cdp_tree);
}

#define     PROTO_TYPE_NLPID  1
#define     PROTO_TYPE_IEEE_802_2   2

static const value_string proto_type_vals[] = {
      { PROTO_TYPE_NLPID,      "NLPID" },
      { PROTO_TYPE_IEEE_802_2, "802.2" },
      { 0,                     NULL },
};

static int
dissect_address_tlv(tvbuff_t *tvb, int offset, int length, proto_tree *tree)
{
    proto_item *ti;
    proto_tree *address_tree;
    guint8 protocol_type;
    guint8 protocol_length;
    int nlpid;
    const char *protocol_str;
    guint16 address_length;
    const char *address_type_str;
    char *address_str;

    if (length < 1)
        return -1;
    ti = proto_tree_add_text(tree, tvb, offset, length, "Truncated address");
    address_tree = proto_item_add_subtree(ti, ett_cdp_address);
    protocol_type = tvb_get_guint8(tvb, offset);
    proto_tree_add_text(address_tree, tvb, offset, 1, "Protocol type: %s",
      val_to_str(protocol_type, proto_type_vals, "Unknown (0x%02x)"));
    offset += 1;
    length -= 1;

    if (length < 1)
      return -1;
    protocol_length = tvb_get_guint8(tvb, offset);
    proto_tree_add_text(address_tree, tvb, offset, 1, "Protocol length: %u",
                  protocol_length);
    offset += 1;
    length -= 1;

    if (length < protocol_length) {
        if (length != 0) {
            proto_tree_add_text(address_tree, tvb, offset, length,
              "Protocol: %s (truncated)",
              tvb_bytes_to_str(tvb, offset, length));
        }
      return -1;
    }
    protocol_str = NULL;
    if (protocol_type == PROTO_TYPE_NLPID && protocol_length == 1) {
      nlpid = tvb_get_guint8(tvb, offset);
      protocol_str = val_to_str(nlpid, nlpid_vals, "Unknown (0x%02x)");
    } else
        nlpid = -1;
    if (protocol_str == NULL)
        protocol_str = tvb_bytes_to_str(tvb, offset, protocol_length);
    proto_tree_add_text(address_tree, tvb, offset, protocol_length,
                  "Protocol: %s", protocol_str);
    offset += protocol_length;
    length -= protocol_length;

    if (length < 2)
      return -1;
    address_length = tvb_get_ntohs(tvb, offset);
    proto_tree_add_text(address_tree, tvb, offset, 2, "Address length: %u",
                  address_length);
    offset += 2;
    length -= 2;

    if (length < address_length) {
        if (length != 0) {
            proto_tree_add_text(address_tree, tvb, offset, length,
              "Address: %s (truncated)",
              tvb_bytes_to_str(tvb, offset, length));
        }
      return -1;
    }
    /* XXX - the Cisco document seems to be saying that, for 802.2-format
       protocol types, 0xAAAA03 0x000000 0x0800 is IPv6, but 0x0800 is
       the Ethernet protocol type for IPv4. */
    length = 2 + protocol_length + 2 + address_length;
    address_type_str = NULL;
    address_str = NULL;
    if (protocol_type == PROTO_TYPE_NLPID && protocol_length == 1) {
        switch (nlpid) {

        /* XXX - dissect NLPID_ISO8473_CLNP as OSI CLNP address? */

        case NLPID_IP:
            if (address_length == 4) {
                /* The address is an IP address. */
                address_type_str = "IP address";
                address_str = ip_to_str(tvb_get_ptr(tvb, offset, 4));
            }
            break;
        }
    }
    if (address_type_str == NULL)
        address_type_str = "Address";
    if (address_str == NULL) {
        address_str = tvb_bytes_to_str(tvb, offset, address_length);
    }
    proto_item_set_text(ti, "%s: %s", address_type_str, address_str);
    proto_tree_add_text(address_tree, tvb, offset, address_length, "%s: %s",
      address_type_str, address_str);
    return 2 + protocol_length + 2 + address_length;
}

static void
dissect_capabilities(tvbuff_t *tvb, int offset, int length, proto_tree *tree)
{
    proto_item *ti;
    proto_tree *capabilities_tree;
    guint32 capabilities;

    if (length < 4)
        return;
    capabilities = tvb_get_ntohl(tvb, offset);
    ti = proto_tree_add_text(tree, tvb, offset, length, "Capabilities: 0x%08x",
        capabilities);
    capabilities_tree = proto_item_add_subtree(ti, ett_cdp_capabilities);
    proto_tree_add_text(capabilities_tree, tvb, offset, 4,
      decode_boolean_bitfield(capabilities, 0x01, 4*8,
          "Is  a Router",
          "Not a Router"));
    proto_tree_add_text(capabilities_tree, tvb, offset, 4,
      decode_boolean_bitfield(capabilities, 0x02, 4*8,
          "Is  a Transparent Bridge",
          "Not a Transparent Bridge"));
    proto_tree_add_text(capabilities_tree, tvb, offset, 4,
      decode_boolean_bitfield(capabilities, 0x04, 4*8,
          "Is  a Source Route Bridge",
          "Not a Source Route Bridge"));
    proto_tree_add_text(capabilities_tree, tvb, offset, 4,
      decode_boolean_bitfield(capabilities, 0x08, 4*8,
          "Is  a Switch",
          "Not a Switch"));
    proto_tree_add_text(capabilities_tree, tvb, offset, 4,
      decode_boolean_bitfield(capabilities, 0x10, 4*8,
          "Is  a Host",
          "Not a Host"));
    proto_tree_add_text(capabilities_tree, tvb, offset, 4,
      decode_boolean_bitfield(capabilities, 0x20, 4*8,
          "Is  IGMP capable",
          "Not IGMP capable"));
    proto_tree_add_text(capabilities_tree, tvb, offset, 4,
      decode_boolean_bitfield(capabilities, 0x40, 4*8,
          "Is  a Repeater",
          "Not a Repeater"));
}

static void
add_multi_line_string_to_tree(proto_tree *tree, tvbuff_t *tvb, gint start,
  gint len, const gchar *prefix)
{
    int prefix_len;
    int i;
    char blanks[64+1];
    gint next;
    int line_len;
    int data_len;

    prefix_len = strlen(prefix);
    if (prefix_len > 64)
      prefix_len = 64;
    for (i = 0; i < prefix_len; i++)
      blanks[i] = ' ';
    blanks[i] = '\0';
    while (len > 0) {
      line_len = tvb_find_line_end(tvb, start, len, &next, FALSE);
      data_len = next - start;
      proto_tree_add_text(tree, tvb, start, data_len, "%s%s", prefix,
         tvb_format_stringzpad(tvb, start, line_len));
      start += data_len;
      len -= data_len;
      prefix = blanks;
    }
}

void
proto_register_cdp(void)
{
    static hf_register_info hf[] = {
      { &hf_cdp_version,
      { "Version",            "cdp.version",  FT_UINT8, BASE_DEC, NULL, 0x0,
        "", HFILL }},

      { &hf_cdp_ttl,
      { "TTL",          "cdp.ttl", FT_UINT16, BASE_DEC, NULL, 0x0,
        "", HFILL }},

      { &hf_cdp_checksum,
      { "Checksum",           "cdp.checksum", FT_UINT16, BASE_HEX, NULL, 0x0,
        "", HFILL }},

      { &hf_cdp_tlvtype,
      { "Type",         "cdp.tlv.type", FT_UINT16, BASE_HEX, VALS(type_vals), 0x0,
        "", HFILL }},

      { &hf_cdp_tlvlength,
      { "Length",       "cdp.tlv.len", FT_UINT16, BASE_DEC, NULL, 0x0,
        "", HFILL }},
    };
    static gint *ett[] = {
      &ett_cdp,
      &ett_cdp_tlv,
      &ett_cdp_address,
      &ett_cdp_capabilities,
    };

    proto_cdp = proto_register_protocol("Cisco Discovery Protocol",
                              "CDP", "cdp");
    proto_register_field_array(proto_cdp, hf, array_length(hf));
    proto_register_subtree_array(ett, array_length(ett));
}

void
proto_reg_handoff_cdp(void)
{
    dissector_handle_t cdp_handle;

    data_handle = find_dissector("data");
    cdp_handle = create_dissector_handle(dissect_cdp, proto_cdp);
    dissector_add("llc.cisco_pid", 0x2000, cdp_handle);
    dissector_add("chdlctype", 0x2000, cdp_handle);
    dissector_add("ppp.protocol", 0x0207, cdp_handle);
}

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