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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 24284 2008-02-07 15:05:42Z stig $
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

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

#include <glib.h>
#include <epan/packet.h>
#include <epan/strutil.h>
#include <epan/in_cksum.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_checksum_good = -1;
static int hf_cdp_checksum_bad = -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 gint ett_cdp_checksum = -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 */
#define TYPE_EXT_PORT_ID        0x0018 /* External Port-ID */
#define TYPE_POWER_REQUESTED    0x0019 /* Power Requested */
#define TYPE_POWER_AVAILABLE    0x001a /* Power Available */
#define TYPE_PORT_UNIDIR        0x001b /* Port Unidirectional */

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" },
      { TYPE_EXT_PORT_ID,     "External Port-ID" },
      { TYPE_POWER_REQUESTED, "Power Requested" },
      { TYPE_POWER_AVAILABLE, "Power Available" },
      { TYPE_PORT_UNIDIR,     "Port Unidirectional" },
      { 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, *checksum_item;
    proto_tree *cdp_tree = NULL, *checksum_tree;
    int offset = 0;
    guint16 type;
    guint16 length, packet_checksum, computed_checksum, data_length;
    gboolean checksum_good, checksum_bad;
    proto_item *tlvi = NULL;
    proto_tree *tlv_tree = NULL;
    int real_length;
    guint32 naddresses;
    guint32 power_avail_len, power_avail;
    guint32 power_req_len, power_req;
    int addr_length;
    guint32 ip_addr;
    vec_t cksum_vec[1];

    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;
    } else {
      offset += 2; /* The version/ttl fields from above */
    }

    /* Checksum display & verification code */
    packet_checksum = tvb_get_ntohs(tvb, offset);
    
    data_length = tvb_reported_length(tvb);
    
    cksum_vec[0].ptr = tvb_get_ptr(tvb, 0, data_length);
    cksum_vec[0].len = data_length;
    
    computed_checksum = in_cksum(cksum_vec, 1);
    checksum_good = (computed_checksum == 0);
    checksum_bad = !checksum_good;
    if (checksum_good) {
        checksum_item = proto_tree_add_uint_format(cdp_tree,
      hf_cdp_checksum, tvb, offset, 2, packet_checksum,
      "Checksum: 0x%04x [correct]", packet_checksum);
    } else {
      checksum_item = proto_tree_add_uint_format(cdp_tree,
       hf_cdp_checksum, tvb, offset, 2, packet_checksum,
       "Checksum: 0x%04x [incorrect, should be 0x%04x]",
       packet_checksum,
       in_cksum_shouldbe(packet_checksum, computed_checksum));
    }
    
    checksum_tree = proto_item_add_subtree(checksum_item, ett_cdp_checksum);
    checksum_item = proto_tree_add_boolean(checksum_tree, hf_cdp_checksum_good,
                                 tvb, offset, 2, checksum_good);
    PROTO_ITEM_SET_GENERATED(checksum_item);
    checksum_item = proto_tree_add_boolean(checksum_tree, hf_cdp_checksum_bad,
                                 tvb, offset, 2, checksum_bad);
    PROTO_ITEM_SET_GENERATED(checksum_item);
    
    offset += 2;
    
    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;

      case TYPE_ADDRESS:
      /* Addresses */
      if (tree) {
        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);
      if (tree) {
        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:
      if (tree) {
        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:
      if (tree) {
        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 */
      if (tree) {
        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 */
        if (tree) {
          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 {  
        if (tree) {
          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) {
          if (tree) {
            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:
      if (tree) {
        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:
      if (tree) {
        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:
      if (tree) {
        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:
      if (tree) {
        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 (tree) {
        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 (tree) {
        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:
      if (tree) {
        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:
      if (tree) {
        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:
      if (tree) {
        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:
      if (tree) {
        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:
      if (tree) {
        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:
      if (tree) {
        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:
      if (tree) {
        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);
      if (tree) {
        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:
      if (tree) {
        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;
            
      case TYPE_POWER_REQUESTED:
      if (tree) {
        tlvi = proto_tree_add_text(cdp_tree, tvb,
                             offset, length, "Power Request: ");
        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,
                        2, "Request-ID: %u",
                        tvb_get_ntohs(tvb, offset + 4));
        proto_tree_add_text(tlv_tree, tvb, offset + 6,
                        2, "Management-ID: %u",
                        tvb_get_ntohs(tvb, offset + 6));
      }
      power_req_len = (tvb_get_ntohs(tvb, offset + TLV_LENGTH)) - 8;
      /* Move offset to where the list of Power Request Values Exist */
      offset += 8;
      while(power_req_len) {
        if (power_req_len > 4) {
          power_req = tvb_get_ntohl(tvb, offset);
          if (tree) {
            proto_tree_add_text(tlv_tree, tvb, offset,
                          4, "Power Requested: %u mW", power_req);
            proto_item_append_text(tlvi, "%u mW, ", power_req);
          }
          power_req_len -= 4;
          offset += 4;
        } else {
          if (power_req_len == 4) {
            power_req = tvb_get_ntohl(tvb, offset);
            if (tree) {
            proto_tree_add_text(tlv_tree, tvb, offset,
                            4, "Power Requested: %u mW", power_req);
            proto_item_append_text(tlvi, "%u mW", power_req);
            }
          }
          offset += power_req_len;
          break;
        }
      }
      break;
            
      case TYPE_POWER_AVAILABLE:
      if (tree) {
        tlvi = proto_tree_add_text(cdp_tree, tvb,
                             offset, length, "Power Available: ");
        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,
                        2, "Request-ID: %u",
                        tvb_get_ntohs(tvb, offset + 4));
        proto_tree_add_text(tlv_tree, tvb, offset + 6,
                        2, "Management-ID: %u",
                        tvb_get_ntohs(tvb, offset + 6));
      }
      power_avail_len = (tvb_get_ntohs(tvb, offset + TLV_LENGTH)) - 8;
      /* Move offset to where the list of Power Available Values Exist */
      offset += 8;
      while(power_avail_len) {
        if (power_avail_len > 4) {
          power_avail = tvb_get_ntohl(tvb, offset);
          if (tree) {
            proto_tree_add_text(tlv_tree, tvb, offset,
                          4, "Power Available: %u mW", power_avail);
            proto_item_append_text(tlvi, "%u mW, ", power_avail);
          }
          power_avail_len -= 4;
          offset += 4;
        } else {
          if (power_avail_len == 4) {
            power_avail = tvb_get_ntohl(tvb, offset);
            if (tree) {
            proto_tree_add_text(tlv_tree, tvb, offset,
                            4, "Power Available: %u mW", power_avail);
            proto_item_append_text(tlvi, "%u mW", power_avail);
            }
          }
          offset += power_avail_len;
          break;
        }
      }
      break;

      default:
      if (tree) {
        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_checksum_good,
        { "Good",       "cdp.checksum_good", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
          "True: checksum matches packet content; False: doesn't match content or not checked", HFILL }},
      
      { &hf_cdp_checksum_bad,
        { "Bad ",       "cdp.checksum_bad", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
          "True: checksum doesn't match packet content; False: matches content or not checked", 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,
      &ett_cdp_checksum
    };

    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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