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packet-dhcp-failover.c

/* packet-dhcpfo.c
 * Routines for ISC DHCP Server failover protocol dissection
 * Copyright 2004, M. Ortega y Strupp <moys@loplof.de>
 *
 * $Id: packet-dhcp-failover.c 18196 2006-05-21 04:49:01Z sahlberg $
 *
 * 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.
 */

/*
 * This implementation is loosely based on draft-ietf-dhc-failover-07.txt.
 * As this document does not represent the actual implementation, the
 * source code of ISC DHCPD 3.0 was used too.
 *
 * See also
 *
 *    http://community.roxen.com/developers/idocs/drafts/draft-ietf-dhc-failover-10.html
 *
 * upon which the handling of the message-digest option is based.
 */

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

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

#include <glib.h>

#include <epan/packet.h>
#include <epan/strutil.h>
#include <epan/prefs.h>
#include <epan/emem.h>
#include "packet-arp.h"
#include "packet-tcp.h"

#define TCP_PORT_DHCPFO 519

static unsigned int tcp_port_pref = TCP_PORT_DHCPFO;

/* desegmentation of DHCP failover over TCP */
static gboolean dhcpfo_desegment = TRUE;

static dissector_handle_t dhcpfo_handle;

/* Initialize the protocol and registered fields */
static int proto_dhcpfo = -1;
static int hf_dhcpfo_length = -1;
static int hf_dhcpfo_type = -1;
static int hf_dhcpfo_poffset = -1;
static int hf_dhcpfo_time = -1;
static int hf_dhcpfo_xid = -1;
static int hf_dhcpfo_additional_HB = -1;
static int hf_dhcpfo_payload_data = -1;
static int hf_dhcpfo_option_code = -1;
static int hf_dhcpfo_dhcp_style_option = -1;
static int hf_dhcpfo_option_length = -1;
static int hf_dhcpfo_binding_status = -1;
static int hf_dhcpfo_server_state = -1;
static int hf_dhcpfo_assigned_ip_address = -1;
static int hf_dhcpfo_sending_server_ip_address = -1;
static int hf_dhcpfo_addresses_transferred = -1;
static int hf_dhcpfo_client_identifier = -1;
static int hf_dhcpfo_client_hw_type = -1;
static int hf_dhcpfo_client_hardware_address = -1;
static int hf_dhcpfo_ftddns = -1;
static int hf_dhcpfo_reject_reason = -1;
static int hf_dhcpfo_message = -1;
static int hf_dhcpfo_mclt = -1;
static int hf_dhcpfo_vendor_class = -1;
static int hf_dhcpfo_lease_expiration_time = -1;
static int hf_dhcpfo_grace_expiration_time = -1;
static int hf_dhcpfo_potential_expiration_time = -1;
static int hf_dhcpfo_client_last_transaction_time = -1;
static int hf_dhcpfo_start_time_of_state = -1;
static int hf_dhcpfo_vendor_option = -1;
static int hf_dhcpfo_max_unacked_bndupd = -1;
static int hf_dhcpfo_protocol_version = -1;
static int hf_dhcpfo_receive_timer = -1;
static int hf_dhcpfo_message_digest = -1;
static int hf_dhcpfo_hash_bucket_assignment = -1;

/* Initialize the subtree pointers */
static gint ett_dhcpfo = -1;
static gint ett_fo_payload = -1;
static gint ett_fo_option = -1;

/* Length of fixed-length portion of header */
#define DHCPFO_FL_HDR_LEN     12

/* message-types of failover */
enum {
      DHCP_FO_RESERVED,
      DHCP_FO_POOLREQ,
      DHCP_FO_POOLRESP,
      DHCP_FO_BNDUPD,
      DHCP_FO_BNDACK,
      DHCP_FO_CONNECT,
      DHCP_FO_CONNECTACK,
      DHCP_FO_UPDREQ,
      DHCP_FO_UPDDONE,
      DHCP_FO_UPDREQALL,
      DHCP_FO_STATE,
      DHCP_FO_CONTACT,
      DHCP_FO_DISCONNECT
};

static const value_string failover_vals[] =
{
      {DHCP_FO_RESERVED,      "Reserved"},
      {DHCP_FO_POOLREQ, "Pool request"},
      {DHCP_FO_POOLRESP,      "Pool response"},
      {DHCP_FO_BNDUPD,  "Binding update"},
      {DHCP_FO_BNDACK,  "Binding acknowledge"},
      {DHCP_FO_CONNECT, "Connect"},
      {DHCP_FO_CONNECTACK,    "Connect acknowledge"},
      {DHCP_FO_UPDREQ,  "Update request all"},
      {DHCP_FO_UPDDONE, "Update done"},
      {DHCP_FO_UPDREQALL,     "Update request"},
      {DHCP_FO_STATE,         "State"},
      {DHCP_FO_CONTACT, "Contact"},
      {DHCP_FO_DISCONNECT,    "Disconnect"},
      {0, NULL}
};

/*options of payload-data*/
enum {
      DHCP_FO_PD_UNKNOWN_PACKET0,
      DHCP_FO_PD_BINDING_STATUS,
      DHCP_FO_PD_ASSIGNED_IP_ADDRESS,
      DHCP_FO_PD_SENDING_SERVER_IP_ADDRESS,
      DHCP_FO_PD_ADDRESSES_TRANSFERED,
      DHCP_FO_PD_CLIENT_IDENTIFIER,
      DHCP_FO_PD_CLIENT_HARDWARE_ADDRESS,
      DHCP_FO_PD_FTDDNS,
      DHCP_FO_PD_REJECT_REASON,
      DHCP_FO_PD_MESSAGE,
      DHCP_FO_PD_MCLT,
      DHCP_FO_PD_VENDOR_CLASS,
      DHCP_FO_PD_UNKNOWN_PACKET12,
      DHCP_FO_PD_LEASE_EXPIRATION_TIME,
      DHCP_FO_PD_POTENTIAL_EXPIRATION_TIME,
      DHCP_FO_PD_GRACE_EXPIRATION_TIME,
      DHCP_FO_PD_CLIENT_LAST_TRANSACTION_TIME,
      DHCP_FO_PD_START_TIME_OF_STATE,
      DHCP_FO_PD_SERVERSTATE,
      DHCP_FO_PD_SERVERFLAG,
      DHCP_FO_PD_VENDOR_OPTION,
      DHCP_FO_PD_MAX_UNACKED_BNDUPD,
      DHCP_FO_PD_UNKNOWN_PACKET22,
      DHCP_FO_PD_RECEIVE_TIMER,
      DHCP_FO_PD_HASH_BUCKET_ASSIGNMENT,
      DHCP_FO_PD_MESSAGE_DIGEST,
      DHCP_FO_PD_PROTOCOL_VERSION,
      DHCP_FO_PD_TLS_REQUEST,
      DHCP_FO_PD_TLS_REPLY,
      DHCP_FO_PD_REQUEST_OPTION,
      DHCP_FO_PD_REPLY_OPTION
};

static const value_string option_code_vals[] =
{
      {DHCP_FO_PD_UNKNOWN_PACKET0,              "Unknown Packet"},
      {DHCP_FO_PD_BINDING_STATUS,               "binding-status"},
      {DHCP_FO_PD_ASSIGNED_IP_ADDRESS,          "assigned-IP-address"},
      {DHCP_FO_PD_SENDING_SERVER_IP_ADDRESS,          "sending-server-IP-address"},
      {DHCP_FO_PD_ADDRESSES_TRANSFERED,         "addresses-transferred"},
      {DHCP_FO_PD_CLIENT_IDENTIFIER,                  "client-identifier"},
      {DHCP_FO_PD_CLIENT_HARDWARE_ADDRESS,            "client-hardware-address"},
      {DHCP_FO_PD_FTDDNS,                       "FTDDNS"},
      {DHCP_FO_PD_REJECT_REASON,                "reject-reason"},
      {DHCP_FO_PD_MESSAGE,                      "message"},
      {DHCP_FO_PD_MCLT,                   "MCLT"},
      {DHCP_FO_PD_VENDOR_CLASS,                 "vendor-class"},
      {DHCP_FO_PD_UNKNOWN_PACKET12,             "Unknown Packet"},
      {DHCP_FO_PD_LEASE_EXPIRATION_TIME,        "lease-expiration-time"},
      {DHCP_FO_PD_POTENTIAL_EXPIRATION_TIME,          "potential-expiration-time"},
      {DHCP_FO_PD_GRACE_EXPIRATION_TIME,        "grace-expiration-time"},
      {DHCP_FO_PD_CLIENT_LAST_TRANSACTION_TIME, "client-last-transaction-time"},
      {DHCP_FO_PD_START_TIME_OF_STATE,          "start-time-of-state"},
      {DHCP_FO_PD_SERVERSTATE,                  "server-state"},
      {DHCP_FO_PD_SERVERFLAG,                   "server-flag"},
      {DHCP_FO_PD_VENDOR_OPTION,                "vendor-option"},
      {DHCP_FO_PD_MAX_UNACKED_BNDUPD,                 "max-unacked-BNDUPD"},
      {DHCP_FO_PD_UNKNOWN_PACKET22,             "Unknown Packet"},
      {DHCP_FO_PD_RECEIVE_TIMER,                "receive-timer"},
      {DHCP_FO_PD_HASH_BUCKET_ASSIGNMENT,       "hash-bucket-assignment"},
      {DHCP_FO_PD_MESSAGE_DIGEST,               "message-digest"},
      {DHCP_FO_PD_PROTOCOL_VERSION,             "protocol-version"},
      {DHCP_FO_PD_TLS_REQUEST,                  "TLS-request"},
      {DHCP_FO_PD_TLS_REPLY,                    "TLS-reply"},
      {DHCP_FO_PD_REQUEST_OPTION,               "request-option"},
      {DHCP_FO_PD_REPLY_OPTION,                 "reply-option"},
      {0, NULL}

};

/* Binding-status */
enum {
      DHCP_FO_BS_UNKNOWN_PACKET,
      DHCP_FO_BS_FREE,
      DHCP_FO_BS_ACTIVE,
      DHCP_FO_BS_EXPIRED,
      DHCP_FO_BS_RELEASED,
      DHCP_FO_BS_ABANDONED,
      DHCP_FO_BS_RESET,
      DHCP_FO_BS_BACKUP
};

static const value_string binding_status_vals[] =
{
      {DHCP_FO_BS_UNKNOWN_PACKET,   "Unknown Packet"},
      {DHCP_FO_BS_FREE,       "FREE"},
      {DHCP_FO_BS_ACTIVE,           "ACTIVE"},
      {DHCP_FO_BS_EXPIRED,          "EXPIRED"},
      {DHCP_FO_BS_RELEASED,         "RELEASED"},
      {DHCP_FO_BS_ABANDONED,        "ABANDONED"},
      {DHCP_FO_BS_RESET,            "RESET"},
      {DHCP_FO_BS_BACKUP,           "BACKUP"},
      {0, NULL}

};

/* Server-status */
enum {
      DHCP_FO_SS_UNKNOWN_PACKET,
      DHCP_FO_SS_PARTNER_DOWN,
      DHCP_FO_SS_NORMAL,
      DHCP_FO_SS_COMMUNICATION_INTERRUPTED,
      DHCP_FO_SS_RESOLUTION_INTERRUPTED,
      DHCP_FO_SS_POTENTIAL_CONFLICT,
      DHCP_FO_SS_RECOVER,
      DHCP_FO_SS_RECOVER_DONE,
      DHCP_FO_SS_SHUTDOWN,
      DHCP_FO_SS_PAUSED,
      DHCP_FO_SS_STARTUP,
      DHCP_FO_SS_RECOVER_WAIT
};


static const value_string server_state_vals[] =
{
      {DHCP_FO_SS_UNKNOWN_PACKET,         "Unknown Packet"},
      {DHCP_FO_SS_PARTNER_DOWN,           "partner down"},
      {DHCP_FO_SS_NORMAL,                 "normal"},
      {DHCP_FO_SS_COMMUNICATION_INTERRUPTED,    "communication interrupted"},
      {DHCP_FO_SS_RESOLUTION_INTERRUPTED, "resolution interrupted"},
      {DHCP_FO_SS_POTENTIAL_CONFLICT,           "potential conflict"},
      {DHCP_FO_SS_RECOVER,                "recover"},
      {DHCP_FO_SS_RECOVER_DONE,           "recover done"},
      {DHCP_FO_SS_SHUTDOWN,               "shutdown"},
      {DHCP_FO_SS_PAUSED,                 "paused"},
      {DHCP_FO_SS_STARTUP,                "startup"},
      {DHCP_FO_SS_RECOVER_WAIT,           "recover wait"},
      {0, NULL}
};

/* reject reasons */


enum {
      DHCP_FO_RR_0,
      DHCP_FO_RR_1,
      DHCP_FO_RR_2,
      DHCP_FO_RR_3,
      DHCP_FO_RR_4,
      DHCP_FO_RR_5,
      DHCP_FO_RR_6,
      DHCP_FO_RR_7,
      DHCP_FO_RR_8,
      DHCP_FO_RR_9,
      DHCP_FO_RR_10,
      DHCP_FO_RR_11,
      DHCP_FO_RR_12,
      DHCP_FO_RR_13,
      DHCP_FO_RR_14,
      DHCP_FO_RR_15,
      DHCP_FO_RR_16,
      DHCP_FO_RR_17,
      DHCP_FO_RR_18,
      DHCP_FO_RR_19,
      DHCP_FO_RR_254 = 254

};


static const value_string reject_reason_vals[] =
{
      {DHCP_FO_RR_0,    "Reserved"},
      {DHCP_FO_RR_1,    "Illegal IP address (not part of any address pool)"},
      {DHCP_FO_RR_2,    "Fatal conflict exists: address in use by other client"},
      {DHCP_FO_RR_3,    "Missing binding information"},
      {DHCP_FO_RR_4,    "Connection rejected, time mismatch too great"},
      {DHCP_FO_RR_5,    "Connection rejected, invalid MCLT"},
      {DHCP_FO_RR_6,    "Connection rejected, unknown reason"},
      {DHCP_FO_RR_7,    "Connection rejected, duplicate connection"},
      {DHCP_FO_RR_8,    "Connection rejected, invalid failover partner"},
      {DHCP_FO_RR_9,    "TLS not supported"},
      {DHCP_FO_RR_10,   "TLS supported but not configured"},
      {DHCP_FO_RR_11,   "TLS required but not supported by partner"},
      {DHCP_FO_RR_12,   "Message digest not supported"},
      {DHCP_FO_RR_13,   "Message digest not configured"},
      {DHCP_FO_RR_14,   "Protocol version mismatch"},
      {DHCP_FO_RR_15,   "Missing binding information"},
      {DHCP_FO_RR_16,   "Outdated binding information"},
      {DHCP_FO_RR_17,   "Less critical binding information"},
      {DHCP_FO_RR_18,   "No traffic within sufficient time"},
      {DHCP_FO_RR_19,   "Hash bucket assignment conflict"},
      {DHCP_FO_RR_254, "Unknown: Error occurred but does not match any reason"},
      {0, NULL}
};

static const value_string tls_request_vals[] =
{
      {0, "No TLS operation"},
      {1, "TLS operation desired but not required"},
      {2, "TLS operation is required"},
      {0, NULL}
};

/* Code to actually dissect the packets */
static guint
get_dhcpfo_pdu_len(tvbuff_t *tvb, int offset)
{
      /*
       * Return the length of the DHCP failover packet.
       */
      return tvb_get_ntohs(tvb, offset);
}

static void
dissect_dhcpfo_pdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
      int offset = 0;
      proto_item *ti, *pi, *oi;
      proto_tree *dhcpfo_tree = NULL, *payload_tree, *option_tree;
      guint16 length, tls_request;
      guint type, serverflag;
      int poffset;
      guint32 xid;
      const gchar *tls_request_string;
      nstime_t time;
      guint32 lease_expiration_time, grace_expiration_time;
      guint32 potential_expiration_time, client_last_transaction_time;
      guint32 start_time_of_state;
      gboolean bogus_poffset;
      guint16 opcode;
      guint16 option_length;
      guint8 htype, reject_reason, message_digest_type;
      const guint8 *chaddr;
      guint8 binding_status;
      gchar *assigned_ip_address_str, *sending_server_ip_address_str;
      guint32 addresses_transferred;
      guint8 *client_identifier_str, *vendor_class_str;
      const gchar *htype_str;
      const gchar *chaddr_str;
      gchar *lease_expiration_time_str;
      gchar *grace_expiration_time_str, *potential_expiration_time_str;
      gchar *client_last_transaction_time_str, *start_time_of_state_str;
      guint32 mclt;
      guint8 server_state, protocol_version;
      guint32 max_unacked_bndupd, receive_timer;

/* Make entries in Protocol column and Info column on summary display */
      if (check_col(pinfo->cinfo, COL_PROTOCOL))
            col_set_str(pinfo->cinfo, COL_PROTOCOL, "DHCPFO");
      if (check_col(pinfo->cinfo, COL_INFO))
            col_clear(pinfo->cinfo, COL_INFO);

      length = tvb_get_ntohs(tvb, offset);
      if (tree) {
            /* create display subtree for the protocol */
            ti = proto_tree_add_item(tree, proto_dhcpfo, tvb, 0, -1, FALSE);

            dhcpfo_tree = proto_item_add_subtree(ti, ett_dhcpfo);

            if (length >= DHCPFO_FL_HDR_LEN) {
                  proto_tree_add_uint(dhcpfo_tree,
                      hf_dhcpfo_length, tvb, offset, 2, length);
            } else {
                  proto_tree_add_uint_format_value(dhcpfo_tree,
                      hf_dhcpfo_length, tvb, offset, 2, length,
                      "%u (bogus, must be >= %u)",
                      length, DHCPFO_FL_HDR_LEN);
            }
      }
      offset += 2;

      type = tvb_get_guint8(tvb, offset);
      if (tree) {
            proto_tree_add_uint(dhcpfo_tree,
                hf_dhcpfo_type, tvb, offset, 1, type);
      }
      if (check_col(pinfo->cinfo, COL_INFO)) {
            col_add_str(pinfo->cinfo, COL_INFO,
                val_to_str(type, failover_vals, "Unknown Packet"));
      }
      offset += 1;

      poffset = tvb_get_guint8(tvb, offset);
      if (poffset < DHCPFO_FL_HDR_LEN) {
            bogus_poffset = TRUE;
            if (tree) {
                  proto_tree_add_uint_format_value(dhcpfo_tree,
                      hf_dhcpfo_poffset, tvb, offset, 1, poffset,
                      "%u (bogus, must be >= %u)",
                      poffset, DHCPFO_FL_HDR_LEN);
            }
      } else if (poffset > length) {
            bogus_poffset = TRUE;
            if (tree) {
                  proto_tree_add_uint_format_value(dhcpfo_tree,
                      hf_dhcpfo_poffset, tvb, offset, 1, poffset,
                      "%u (bogus, must be <= length of message)",
                      poffset);
            }
      } else {
            bogus_poffset = FALSE;
            if (tree) {
                  proto_tree_add_uint(dhcpfo_tree,
                      hf_dhcpfo_poffset, tvb, offset, 1, poffset);
            }
      }
      offset += 1;

      if (tree) {
            /*
             * XXX - this is *almost* like a time_t, but it's unsigned.
             * Also, we need a way to keep from displaying nanoseconds,
             * so as not to make it look as if it has higher
             */
            time.secs = tvb_get_ntohl(tvb, offset);
            time.nsecs = 0;
            proto_tree_add_time_format_value(dhcpfo_tree, hf_dhcpfo_time, tvb,
                offset, 4, &time, "%s",
                abs_time_secs_to_str(time.secs));
      }
      offset += 4;

      xid = tvb_get_ntohl(tvb, offset);
      if (tree) {
            proto_tree_add_item(dhcpfo_tree,
                hf_dhcpfo_xid, tvb, offset, 4, FALSE);
      }
      if (check_col(pinfo->cinfo, COL_INFO))
            col_append_fstr(pinfo->cinfo, COL_INFO," xid: %x", xid);
      offset += 4;

      if (bogus_poffset)
            return;     /* payload offset was bogus */

      if (!tree)
            return;

      /* if there are any additional header bytes */
      if (poffset != offset) {
            proto_tree_add_item(dhcpfo_tree, hf_dhcpfo_additional_HB, tvb,
                offset, poffset-offset, FALSE);
            offset = poffset;
      }

      /* payload-data */
      if (poffset == length)
            return;     /* no payload */
      /* create display subtree for the payload */
      pi = proto_tree_add_item(dhcpfo_tree, hf_dhcpfo_payload_data,
          tvb, poffset, length-poffset, FALSE);
      payload_tree = proto_item_add_subtree(pi, ett_fo_payload);
      while (offset < length) {
            opcode = tvb_get_ntohs(tvb, offset);
            option_length = tvb_get_ntohs(tvb, offset+2);

            oi = proto_tree_add_item(payload_tree,
                hf_dhcpfo_dhcp_style_option, tvb, offset,
                option_length+4, FALSE);
            option_tree = proto_item_add_subtree(oi, ett_fo_option);

            /*** DHCP-Style-Options ****/

            proto_item_append_text(oi, ", %s (%u)",
                val_to_str(opcode, option_code_vals, "Unknown Option"),
                opcode);

            proto_tree_add_uint(option_tree, hf_dhcpfo_option_code, tvb,
                offset, 2, opcode);

            proto_tree_add_uint(option_tree, hf_dhcpfo_option_length, tvb,
                offset+2, 2, option_length);

            offset += 4;

            /** opcode dependent format **/

            switch (opcode) {

            case DHCP_FO_PD_BINDING_STATUS:
                  binding_status = tvb_get_guint8(tvb, offset);
                  proto_item_append_text(oi, ", %s (%d)",
                      val_to_str(binding_status,
                        binding_status_vals,
                        "Unknown Packet"),
                      binding_status);

                  proto_tree_add_item(option_tree,
                      hf_dhcpfo_binding_status, tvb,
                      offset, 1, FALSE);
                  break;

            case DHCP_FO_PD_ASSIGNED_IP_ADDRESS:
                  if (option_length != 4) {
                        proto_tree_add_text(option_tree, tvb,
                            offset, option_length,
                            "assigned ip address is not 4 bytes long");
                        break;
                  }
                  assigned_ip_address_str = ip_to_str(
                      tvb_get_ptr(tvb, offset, 4));

                  proto_item_append_text(oi, ", %s ",
                      assigned_ip_address_str);

                  proto_tree_add_item(option_tree,
                      hf_dhcpfo_assigned_ip_address, tvb,   offset,
                      option_length, FALSE);
                  break;

            case DHCP_FO_PD_SENDING_SERVER_IP_ADDRESS:
                  if (option_length != 4) {
                        proto_tree_add_text(option_tree, tvb,
                            offset, option_length,
                            "sending server ip address is not 4 bytes long");
                        break;
                  }
                  sending_server_ip_address_str = ip_to_str(tvb_get_ptr(tvb,offset,option_length));

                  proto_item_append_text(oi, ", %s ",
                      sending_server_ip_address_str);
                  proto_tree_add_item(option_tree,
                      hf_dhcpfo_sending_server_ip_address, tvb,
                      offset, option_length, FALSE);
                  break;

            case DHCP_FO_PD_ADDRESSES_TRANSFERED:
                  if (option_length != 4) {
                        proto_tree_add_text(option_tree, tvb,
                            offset, option_length,
                            "addresses transferred is not 4 bytes long");
                        break;
                  }
                  addresses_transferred = tvb_get_ntohl(tvb, offset);

                  proto_item_append_text(oi,", %u", addresses_transferred);
                  proto_tree_add_uint(option_tree,
                      hf_dhcpfo_addresses_transferred, tvb, offset,
                      option_length, addresses_transferred);
                  break;

            case DHCP_FO_PD_CLIENT_IDENTIFIER:
                  /*
                   * XXX - if this is truly like DHCP option 81,
                   * we need to dissect it as such.
                   */
                  client_identifier_str =
                      tvb_get_ephemeral_string(tvb, offset, option_length);
                  proto_item_append_text(oi,", \"%s\"",
                      format_text(client_identifier_str, option_length));
                  proto_tree_add_string(option_tree,
                      hf_dhcpfo_client_identifier, tvb, offset,
                      option_length, client_identifier_str);
                  break;

            case DHCP_FO_PD_CLIENT_HARDWARE_ADDRESS:
                  if (option_length < 2) {
                        proto_tree_add_text(option_tree, tvb,
                            offset, option_length,
                            "hardware address is too short");
                        break;
                  }
                  htype = tvb_get_guint8(tvb, offset);
                  chaddr = tvb_get_ptr(tvb, offset+1,
                      option_length-1);
                  htype_str = arphrdtype_to_str(htype, "Unknown (0x%02x)");
                  chaddr_str = arphrdaddr_to_str(chaddr, option_length-1,
                      htype);

                  proto_item_append_text(oi, ", %s, %s", htype_str,
                      chaddr_str);

                  proto_tree_add_text(option_tree, tvb, offset, 1,
                      "Hardware type: %s", htype_str);

                  proto_tree_add_text(option_tree, tvb, offset+1,
                      option_length-1,
                      "Client hardware address: %s", chaddr_str);
                  break;

            case DHCP_FO_PD_FTDDNS:
                  proto_tree_add_item(option_tree, hf_dhcpfo_ftddns, tvb,
                      offset, option_length, FALSE);
                  break;

            case DHCP_FO_PD_REJECT_REASON:
                  if (option_length != 1) {
                        proto_tree_add_text(option_tree, tvb,
                            offset, option_length,
                            "Reject reason is not 1 byte long");
                        break;
                  }
                  reject_reason = tvb_get_guint8(tvb, offset);

                  proto_item_append_text(oi, ", %s (%d)",
                      val_to_str(reject_reason, reject_reason_vals,
                        "Unknown Packet"),
                      reject_reason);

                  proto_tree_add_uint(option_tree,
                      hf_dhcpfo_reject_reason, tvb, offset,
                      option_length, reject_reason);
                  break;

            case DHCP_FO_PD_MESSAGE:
                  proto_tree_add_item(option_tree, hf_dhcpfo_message, tvb,
                      offset, option_length, FALSE);
                  break;

            case DHCP_FO_PD_MCLT:
                  if (option_length != 4) {
                        proto_tree_add_text(option_tree, tvb,
                            offset, option_length,
                            "MCLT is not 4 bytes long");
                        break;
                  }
                  mclt = tvb_get_ntohl(tvb, offset);
                  proto_item_append_text(oi,", %u seconds", mclt);
                  proto_tree_add_uint(option_tree, hf_dhcpfo_mclt, tvb,
                      offset, option_length, mclt);
                  break;

            case DHCP_FO_PD_VENDOR_CLASS:
                  vendor_class_str =
                      tvb_get_ephemeral_string(tvb, offset, option_length);
                  proto_item_append_text(oi,", \"%s\"",
                      format_text(vendor_class_str, option_length));
                  proto_tree_add_string(option_tree,
                      hf_dhcpfo_vendor_class, tvb, offset,
                      option_length, vendor_class_str);
                  break;

            case DHCP_FO_PD_LEASE_EXPIRATION_TIME:
                  if (option_length != 4) {
                        proto_tree_add_text(option_tree, tvb,
                            offset, option_length,
                            "Lease expiration time is not 4 bytes long");
                        break;
                  }
                  lease_expiration_time =
                      tvb_get_ntohl(tvb, offset);
                  lease_expiration_time_str =
                      abs_time_secs_to_str(lease_expiration_time);

                  proto_item_append_text(oi, ", %s",
                      lease_expiration_time_str);

                  proto_tree_add_uint_format_value(option_tree,
                      hf_dhcpfo_lease_expiration_time, tvb,
                      offset, option_length,
                      lease_expiration_time,
                      "%s",
                      lease_expiration_time_str);
                  break;

            case DHCP_FO_PD_POTENTIAL_EXPIRATION_TIME:
                  if (option_length != 4) {
                        proto_tree_add_text(option_tree, tvb,
                            offset, option_length,
                            "Potential expiration time is not 4 bytes long");
                        break;
                  }
                  potential_expiration_time =
                      tvb_get_ntohl(tvb, offset);

                  potential_expiration_time_str =
                      abs_time_secs_to_str(potential_expiration_time);

                  proto_item_append_text(oi, ", %s",
                      potential_expiration_time_str);

                  proto_tree_add_uint_format_value(option_tree,
                      hf_dhcpfo_potential_expiration_time, tvb,
                      offset, option_length,
                      potential_expiration_time,
                      "%s",
                      potential_expiration_time_str);
                  break;

            case DHCP_FO_PD_GRACE_EXPIRATION_TIME:
                  if (option_length != 4) {
                        proto_tree_add_text(option_tree, tvb,
                            offset, option_length,
                            "Grace expiration time is not 4 bytes long");
                        break;
                  }
                  grace_expiration_time =
                      tvb_get_ntohl(tvb, offset);

                  grace_expiration_time_str =
                      abs_time_secs_to_str(grace_expiration_time);

                  proto_item_append_text(oi, ", %s",
                      grace_expiration_time_str);

                  proto_tree_add_uint_format_value(option_tree,
                      hf_dhcpfo_grace_expiration_time, tvb,
                      offset, option_length,
                      grace_expiration_time,
                      "%s",
                      grace_expiration_time_str);
                  break;

            case DHCP_FO_PD_CLIENT_LAST_TRANSACTION_TIME:
                  if (option_length != 4) {
                        proto_tree_add_text(option_tree, tvb,
                            offset, option_length,
                            "Last transaction time is not 4 bytes long");
                        break;
                  }
                  client_last_transaction_time =
                      tvb_get_ntohl(tvb, offset);
                  client_last_transaction_time_str =
                      abs_time_secs_to_str(client_last_transaction_time);

                  proto_item_append_text(oi, ", %s",
                      client_last_transaction_time_str);

                  proto_tree_add_uint_format_value(option_tree,
                      hf_dhcpfo_client_last_transaction_time, tvb,
                      offset, option_length,
                      client_last_transaction_time,
                      "%s",
                      abs_time_secs_to_str(client_last_transaction_time));
                  break;

            case DHCP_FO_PD_START_TIME_OF_STATE:
                  if (option_length != 4) {
                        proto_tree_add_text(option_tree, tvb,
                            offset, option_length,
                            "Start time of state is not 4 bytes long");
                        break;
                  }
                  start_time_of_state =
                      tvb_get_ntohl(tvb, offset);
                  start_time_of_state_str =
                      abs_time_secs_to_str(start_time_of_state);

                  proto_item_append_text(oi, ", %s",
                      start_time_of_state_str);

                  proto_tree_add_uint_format_value(option_tree,
                      hf_dhcpfo_start_time_of_state, tvb,
                      offset, option_length,
                      start_time_of_state,
                      "%s",
                      abs_time_secs_to_str(start_time_of_state));
                  break;

            case DHCP_FO_PD_SERVERSTATE:
                  if (option_length != 1) {
                        proto_tree_add_text(option_tree, tvb,
                            offset, option_length,
                            "server status is not 1 byte long");
                        break;
                  }
                  server_state = tvb_get_guint8(tvb, offset);

                  proto_item_append_text(oi, ", %s (%u)",
                      val_to_str(server_state, server_state_vals,
                          "Unknown"),
                      server_state);

                  proto_tree_add_uint(option_tree,
                      hf_dhcpfo_server_state, tvb, offset, 1,
                      server_state);
                  break;

            case DHCP_FO_PD_SERVERFLAG:
                  if (option_length != 1) {
                        proto_tree_add_text(option_tree, tvb,
                            offset, option_length,
                            "Serverflag is not 1 byte long");
                        break;
                  }
                  serverflag = tvb_get_guint8(tvb, offset);

                  if (serverflag == 1) {
                        proto_item_append_text(oi, ", STARTUP (1)");
                        proto_tree_add_text(option_tree,tvb,
                            offset, option_length,
                            "Serverflag: STARTUP");
                  } else if (serverflag == 0) {
                        proto_item_append_text(oi, ", NONE (0)");
                        proto_tree_add_text(option_tree,tvb,
                            offset, option_length,
                        "Serverflag: NONE");
                  } else {
                        proto_item_append_text(oi,
                              "UNKNOWN FLAGS (%u)", serverflag);
                        proto_tree_add_text(option_tree,tvb,
                            offset, option_length,
                            "Serverflag: UNKNOWN FLAGS (%u)",
                            serverflag);
                  }
                  break;

            case DHCP_FO_PD_VENDOR_OPTION:
                  proto_tree_add_item(option_tree,
                      hf_dhcpfo_vendor_option, tvb, offset,
                      option_length, FALSE);
                  break;

            case DHCP_FO_PD_MAX_UNACKED_BNDUPD:
                  if (option_length != 4) {
                        proto_tree_add_text(option_tree, tvb,
                            offset, option_length,
                        "Max unacked BNDUPD is not 4 bytes long");
                        break;
                  }
                  max_unacked_bndupd = tvb_get_ntohl(tvb, offset);
                  proto_item_append_text(oi, ", %u", max_unacked_bndupd);

                  proto_tree_add_uint(option_tree,
                      hf_dhcpfo_max_unacked_bndupd, tvb, offset,
                      option_length, max_unacked_bndupd);
                  break;

            case DHCP_FO_PD_RECEIVE_TIMER:
                  if (option_length != 4) {
                        proto_tree_add_text(option_tree, tvb,
                            offset, option_length,
                            "Receive timer is not 4 bytes long");
                        break;
                  }
                  receive_timer = tvb_get_ntohl(tvb, offset);
                  proto_item_append_text(oi,", %u seconds",
                      receive_timer);

                  proto_tree_add_uint_format_value(option_tree,
                      hf_dhcpfo_receive_timer, tvb, offset,
                      option_length, receive_timer,
                      "%u seconds",
                      receive_timer);
                  break;

            case DHCP_FO_PD_HASH_BUCKET_ASSIGNMENT:
                  proto_tree_add_item(option_tree,
                      hf_dhcpfo_hash_bucket_assignment, tvb,
                      offset, option_length, FALSE);
                  break;

            case DHCP_FO_PD_MESSAGE_DIGEST:
                  if (option_length < 2) {
                        proto_tree_add_text(option_tree, tvb,
                            offset, option_length,
                            "Message digest is too short");
                        break;
                  }
                  message_digest_type = tvb_get_guint8(tvb, offset);
                  if (message_digest_type == 1) {
                        proto_item_append_text(oi, ", HMAC-MD5");
                        proto_tree_add_text(option_tree, tvb,
                            offset, 1,
                            "Message digest type: HMAC-MD5");
                  } else {
                        proto_item_append_text(oi, ", type not allowed");
                        proto_tree_add_text(option_tree, tvb,
                            offset, 1,
                            "Message digest type: %u, not allowed",
                            message_digest_type);
                  }

                  proto_tree_add_item(option_tree,
                      hf_dhcpfo_message_digest, tvb, offset+1,
                      option_length-1, FALSE);
                  break;

            case DHCP_FO_PD_PROTOCOL_VERSION:
                  if (option_length != 1) {
                        proto_tree_add_text(option_tree, tvb,
                            offset, option_length,
                            "Protocol version is not 1 byte long");
                        break;
                  }
                  protocol_version = tvb_get_guint8(tvb, offset);

                  proto_item_append_text(oi, ", version: %u",
                      protocol_version);
                  proto_tree_add_uint(option_tree,
                      hf_dhcpfo_protocol_version, tvb, offset,
                      option_length, protocol_version);
                  break;

            case DHCP_FO_PD_TLS_REQUEST:
                  if (option_length != 2) {
                        proto_tree_add_text(option_tree, tvb,
                            offset, option_length,
                            "TLS request is not 2 bytes long");
                        break;
                  }
                  tls_request = tvb_get_ntohs(tvb, offset);
                  tls_request_string =
                      val_to_str(tls_request, tls_request_vals,
                        "Unknown (%u)");
                  proto_item_append_text(oi, ", %s", tls_request_string);

                  proto_tree_add_text(option_tree, tvb, offset,
                      option_length,
                      "TLS request: %s", tls_request_string);
                  break;

            case DHCP_FO_PD_TLS_REPLY:
                  break;
            case DHCP_FO_PD_REQUEST_OPTION:
                  break;
            case DHCP_FO_PD_REPLY_OPTION:
                  break;
            default:
                  break;
            }

            offset += option_length;
      }
}

static void
dissect_dhcpfo(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
      tcp_dissect_pdus(tvb, pinfo, tree, dhcpfo_desegment, 2,
          get_dhcpfo_pdu_len, dissect_dhcpfo_pdu);
}

void
proto_reg_handoff_dhcpfo(void)
{
      static gboolean initialized = FALSE;
      static unsigned int port = 0;

      if (initialized) {
            dissector_delete("tcp.port", port, dhcpfo_handle);
      } else {
            initialized = TRUE;
      }
      port = tcp_port_pref;
      dissector_add("tcp.port", tcp_port_pref, dhcpfo_handle);
}

/* Register the protocol with Wireshark */
void
proto_register_dhcpfo(void)
{

/* Setup list of header fields  See Section 1.6.1 for details*/
      static hf_register_info hf[] = {
            { &hf_dhcpfo_length,
                  { "Message length",        "dhcpfo.length",
                  FT_UINT16, BASE_DEC, NULL, 0,
                  "", HFILL }
            },
            { &hf_dhcpfo_type,
                  { "Message Type",    "dhcpfo.type",
                  FT_UINT8, BASE_DEC, VALS(failover_vals), 0,
                  "", HFILL }
            },

            { &hf_dhcpfo_poffset,
                  { "Payload Offset",        "dhcpfo.poffset",
                  FT_UINT8, BASE_DEC, NULL, 0,
                  "", HFILL }
            },

            { &hf_dhcpfo_time,
                  { "Time",      "dhcpfo.time",
                  FT_ABSOLUTE_TIME, BASE_NONE, NULL, 0,
                  "", HFILL }
            },

            { &hf_dhcpfo_xid,
                  { "Xid",       "dhcpfo.xid",
                  FT_UINT32, BASE_HEX, NULL, 0,
                  "", HFILL }
            },

            { &hf_dhcpfo_additional_HB,
                  {"Additional Header Bytes",   "dhcpfo.additionalheaderbytes",
                  FT_BYTES, BASE_NONE, NULL, 0x0,
                  "", HFILL }
            },

            { &hf_dhcpfo_payload_data,
                  {"Payload Data",  "dhcpfo.payloaddata",
                  FT_NONE, BASE_NONE, NULL, 0,
                  "", HFILL }
            },

            { &hf_dhcpfo_dhcp_style_option,
                  {"DHCP Style Option",   "dhcpfo.dhcpstyleoption",
                  FT_NONE, BASE_NONE, NULL, 0,
                  "", HFILL }
            },

            { &hf_dhcpfo_option_code,
                  {"Option Code",         "dhcpfo.optioncode",
                  FT_UINT16, BASE_DEC, VALS(option_code_vals), 0,
                  "", HFILL }
            },

            {&hf_dhcpfo_option_length,
                  {"Length",        "dhcpfo.optionlength",
                  FT_UINT16, BASE_DEC, NULL, 0,
                  "", HFILL }
            },

            {&hf_dhcpfo_binding_status,
                  {"Type", "dhcpfo.bindingstatus",
                  FT_UINT32, BASE_DEC, VALS(binding_status_vals), 0,
                  "", HFILL }
            },


            {&hf_dhcpfo_server_state,
                  {"server status", "dhcpfo.serverstatus",
                  FT_UINT8, BASE_DEC, VALS(server_state_vals), 0,
                  "", HFILL }
            },


            {&hf_dhcpfo_assigned_ip_address,
                  {"assigned ip address", "dhcpfo.assignedipaddress",
                  FT_IPv4, BASE_NONE, NULL, 0x0,
                  "", HFILL }
            },

            {&hf_dhcpfo_sending_server_ip_address,
                  {"sending server ip-address", "dhcpfo.sendingserveripaddress",
                  FT_IPv4, BASE_NONE, NULL, 0x0,
                  "", HFILL }
            },


            {&hf_dhcpfo_addresses_transferred,
                  {"addresses transferred", "dhcpfo.addressestransferred",
                  FT_UINT32, BASE_DEC, NULL, 0,
                  "", HFILL }
            },


            {&hf_dhcpfo_client_identifier,
                  {"Client Identifier", "dhcpfo.clientidentifier",
                  FT_STRING, BASE_NONE, NULL, 0,
                  "", HFILL }
            },

            {&hf_dhcpfo_client_hw_type,
                  {"Client Hardware Type", "dhcpfo.clienthardwaretype",
                  FT_UINT8, BASE_HEX, NULL, 0x0,
                  "", HFILL }},

            {&hf_dhcpfo_client_hardware_address,
                  {"Client Hardware Address", "dhcpfo.clienthardwareaddress",
                  FT_BYTES, BASE_NONE, NULL, 0,
                  "", HFILL }
            },

            {&hf_dhcpfo_ftddns,
                  {"FTDDNS", "dhcpfo.ftddns",
                  FT_STRING, BASE_NONE, NULL, 0,
                  "", HFILL }
            },

            {&hf_dhcpfo_reject_reason,
                  {"Reject reason", "dhcpfo.rejectreason",
                  FT_UINT8, BASE_DEC, VALS(reject_reason_vals), 0,
                  "", HFILL }
            },

            {&hf_dhcpfo_message,
                  {"Message", "dhcpfo.message",
                  FT_STRING, BASE_NONE, NULL, 0,
                  "", HFILL }
            },


            {&hf_dhcpfo_mclt,
                  {"MCLT", "dhcpfo.mclt",
                  FT_UINT32, BASE_DEC, NULL, 0,
                  "", HFILL }
            },

            {&hf_dhcpfo_vendor_class,
                  {"Vendor class", "dhcpfo.vendorclass",
                  FT_STRING, BASE_NONE, NULL, 0,
                  "", HFILL }
            },

            {&hf_dhcpfo_lease_expiration_time,
                  {"Lease expiration time", "dhcpfo.leaseexpirationtime",
                  FT_UINT32, BASE_DEC, NULL, 0,
                  "", HFILL }
            },

            {&hf_dhcpfo_grace_expiration_time,
                  {"Grace expiration time", "dhcpfo.graceexpirationtime",
                  FT_UINT32, BASE_DEC, NULL, 0,
                  "", HFILL }
            },

            {&hf_dhcpfo_potential_expiration_time,
                  {"Potential expiration time", "dhcpfo.potentialexpirationtime",
                  FT_UINT32, BASE_DEC, NULL, 0,
                  "", HFILL }
            },

            {&hf_dhcpfo_client_last_transaction_time,
                  {"Client last transaction time", "dhcpfo.clientlasttransactiontime",
                  FT_UINT32, BASE_DEC, NULL, 0,
                  "", HFILL }
            },

            {&hf_dhcpfo_start_time_of_state,
                  {"Start time of state", "dhcpfo.starttimeofstate",
                  FT_UINT32, BASE_DEC, NULL, 0,
                  "", HFILL }
            },

            {&hf_dhcpfo_vendor_option,
                  {"Vendor option", "dhcpfo.vendoroption",
                  FT_NONE, BASE_NONE, NULL, 0x0,
                  "", HFILL }
            },

            {&hf_dhcpfo_max_unacked_bndupd,
                  {"Max unacked BNDUPD", "dhcpfo.maxunackedbndupd",
                  FT_UINT32, BASE_DEC, NULL, 0,
                  "", HFILL }
            },

            {&hf_dhcpfo_protocol_version,
                  {"Protocol version", "dhcpfo.protocolversion",
                  FT_UINT8, BASE_DEC, NULL, 0,
                  "", HFILL }
            },

            {&hf_dhcpfo_receive_timer,
                  {"Receive timer", "dhcpfo.receivetimer",
                  FT_UINT32, BASE_DEC, NULL, 0,
                  "", HFILL }
            },

            {&hf_dhcpfo_message_digest,
                  {"Message digest", "dhcpfo.messagedigest",
                  FT_STRING, BASE_NONE, NULL, 0,
                  "", HFILL }
            },

            {&hf_dhcpfo_hash_bucket_assignment,
                  {"Hash bucket assignment", "dhcpfo.hashbucketassignment",
                  FT_BYTES, BASE_HEX, NULL, 0,
                  "", HFILL }
            },
      };

/* Setup protocol subtree array */
      static gint *ett[] = {
            &ett_dhcpfo,
            &ett_fo_payload,
            &ett_fo_option,
      };

      module_t *dhcpfo_module;

/* Register the protocol name and description */
      proto_dhcpfo = proto_register_protocol("DHCP Failover", "DHCPFO",
          "dhcpfo");

/* Required function calls to register the header fields and subtrees used */
      proto_register_field_array(proto_dhcpfo, hf, array_length(hf));
      proto_register_subtree_array(ett, array_length(ett));

      dhcpfo_handle = create_dissector_handle(dissect_dhcpfo, proto_dhcpfo);

      dhcpfo_module = prefs_register_protocol(proto_dhcpfo, proto_reg_handoff_dhcpfo);
      prefs_register_uint_preference(dhcpfo_module, "tcp_port",
            "DHCP failover TCP Port", "Set the port for DHCP failover communications",
            10, &tcp_port_pref);
      prefs_register_bool_preference(dhcpfo_module, "desegment",
          "Reassemble DHCP failover messages spanning multiple TCP segments",
          "Whether the DHCP failover dissector should reassemble messages spanning multiple TCP segments."
          " To use this option, you must also enable \"Allow subdissectors to reassemble TCP streams\" in the TCP protocol settings.",
          &dhcpfo_desegment);
}

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