/*
    *  Licensed to the Apache Software Foundation (ASF) under one
    *  or more contributor license agreements.  See the NOTICE file
    *  distributed with this work for additional information
    *  regarding copyright ownership.  The ASF licenses this file
    *  to you under the Apache License, Version 2.0 (the
    *  "License"); you may not use this file except in compliance
    *  with the License.  You may obtain a copy of the License at
    *  
   *    http://www.apache.org/licenses/LICENSE-2.0
   *  
   *  Unless required by applicable law or agreed to in writing,
   *  software distributed under the License is distributed on an
   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   *  KIND, either express or implied.  See the License for the
   *  specific language governing permissions and limitations
   *  under the License. 
   *  
   */
  package org.apache.directory.server.dhcp.service;
  
  
  import java.net.InetAddress;
  import java.net.InetSocketAddress;
  
  import org.apache.directory.server.dhcp.DhcpException;
  import org.apache.directory.server.dhcp.messages.DhcpMessage;
  import org.apache.directory.server.dhcp.messages.MessageType;
  import org.apache.directory.server.dhcp.options.AddressOption;
  import org.apache.directory.server.dhcp.options.OptionsField;
  import org.apache.directory.server.dhcp.options.dhcp.ClientIdentifier;
  import org.apache.directory.server.dhcp.options.dhcp.IpAddressLeaseTime;
  import org.apache.directory.server.dhcp.options.dhcp.MaximumDhcpMessageSize;
  import org.apache.directory.server.dhcp.options.dhcp.ParameterRequestList;
  import org.apache.directory.server.dhcp.options.dhcp.RequestedIpAddress;
  import org.apache.directory.server.dhcp.options.dhcp.ServerIdentifier;
  import org.apache.directory.server.dhcp.store.DhcpStore;
  
  
  /**
   * A default implementation of the DHCP service. Does the tedious low-level
   * chores of handling DHCP messages, but delegates the lease-handling to a
   * supplied DhcpStore.
   * 
   * @see org.apache.directory.server.dhcp.store.DhcpStore
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  public class StoreBasedDhcpService extends AbstractDhcpService
  {
      private final DhcpStore dhcpStore;
  
  
      public StoreBasedDhcpService( DhcpStore dhcpStore )
      {
          this.dhcpStore = dhcpStore;
      }
  
  
      /**
       * Try to get an existing lease. The lease may have been created during
       * earlier DHCP negotiations or a recent DHCPDISCOVER.
       * 
       * @param clientAddress
       * @param request
       * @return
       * @throws DhcpException
       */
      private Lease getExistingLease( InetSocketAddress clientAddress, DhcpMessage request ) throws DhcpException
      {
          // determine requested lease time
          IpAddressLeaseTimerectory/server/dhcp/options/dhcp/IpAddressLeaseTime.html#IpAddressLeaseTime">IpAddressLeaseTime requestedLeaseTimeOption = ( IpAddressLeaseTime ) request.getOptions().get(
              IpAddressLeaseTime.class );
          long requestedLeaseTime = null != requestedLeaseTimeOption ? requestedLeaseTimeOption.getIntValue() * 1000
              : -1L;
  
          // try to get the lease (address) requested by the client
          InetAddress requestedAddress = null;
          AddressOptionache/directory/server/dhcp/options/AddressOption.html#AddressOption">AddressOption requestedAddressOption = ( AddressOption ) request.getOptions().get( RequestedIpAddress.class );
  
          if ( null != requestedAddressOption )
          {
              requestedAddress = requestedAddressOption.getAddress();
          }
  
          if ( null == requestedAddress )
          {
              requestedAddress = request.getCurrentClientAddress();
          }
  
          InetAddress selectionBase = determineSelectionBase( clientAddress, request );
  
          Lease lease = dhcpStore.getExistingLease( request.getHardwareAddress(), requestedAddress, selectionBase,
              requestedLeaseTime, request.getOptions() );
  
          if ( null == lease )
          {
              return null;
          }
  
         return lease;
     }
 
 
     /**
      * Determine a lease to offer in response to a DHCPDISCOVER message.
      * <p>
      * When a server receives a DHCPDISCOVER message from a client, the server
      * chooses a network address for the requesting client. If no address is
      * available, the server may choose to report the problem to the system
      * administrator. If an address is available, the new address SHOULD be
      * chosen as follows:
      * <ul>
      * <li> The client's current address as recorded in the client's current
      * binding, ELSE
      * <li> The client's previous address as recorded in the client's (now
      * expired or released) binding, if that address is in the server's pool of
      * available addresses and not already allocated, ELSE
      * <li> The address requested in the 'Requested IP Address' option, if that
      * address is valid and not already allocated, ELSE
      * <li> A new address allocated from the server's pool of available
      * addresses; the address is selected based on the subnet from which the
      * message was received (if 'giaddr' is 0) or on the address of the relay
      * agent that forwarded the message ('giaddr' when not 0).
      * </ul>
      * 
      * @param clientAddress
      * @param request
      * @return
      */
     private Lease getLeaseOffer( InetSocketAddress clientAddress, DhcpMessage request ) throws DhcpException
     {
         // determine requested lease time
         IpAddressLeaseTimerectory/server/dhcp/options/dhcp/IpAddressLeaseTime.html#IpAddressLeaseTime">IpAddressLeaseTime requestedLeaseTimeOption = ( IpAddressLeaseTime ) request.getOptions().get(
             IpAddressLeaseTime.class );
         long requestedLeaseTime = null != requestedLeaseTimeOption ? requestedLeaseTimeOption.getIntValue() * 1000
             : -1L;
 
         // try to get the lease (address) requested by the client
         InetAddress requestedAddress = null;
         AddressOptionache/directory/server/dhcp/options/AddressOption.html#AddressOption">AddressOption requestedAddressOption = ( AddressOption ) request.getOptions().get( RequestedIpAddress.class );
 
         if ( null != requestedAddressOption )
         {
             requestedAddress = requestedAddressOption.getAddress();
         }
 
         InetAddress selectionBase = determineSelectionBase( clientAddress, request );
 
         return dhcpStore.getLeaseOffer( request.getHardwareAddress(), requestedAddress, selectionBase,
             requestedLeaseTime, request.getOptions() );
     }
 
 
     /*
      * @see org.apache.directory.server.dhcp.service.AbstractDhcpService#handleRELEASE(java.net.InetSocketAddress,
      *      java.net.InetSocketAddress,
      *      org.apache.directory.server.dhcp.messages.DhcpMessage)
      */
     @Override
     protected DhcpMessage handleRELEASE( InetSocketAddress localAddress, InetSocketAddress clientAddress,
         DhcpMessage request ) throws DhcpException
     {
         // check server ident
         AddressOptionrg/apache/directory/server/dhcp/options/AddressOption.html#AddressOption">AddressOption serverIdentOption = ( AddressOption ) request.getOptions().get( ServerIdentifier.class );
 
         if ( null != serverIdentOption && serverIdentOption.getAddress().isAnyLocalAddress() )
         {
             return null; // not me?! FIXME: handle authoritative server case
         }
 
         Lease lease = getExistingLease( clientAddress, request );
 
         DhcpMessage reply = initGeneralReply( localAddress, request );
 
         if ( null == lease )
         {
             // null lease? send NAK
             // FIXME...
             reply.setMessageType( MessageType.DHCPNAK );
             reply.setCurrentClientAddress( null );
             reply.setAssignedClientAddress( null );
             reply.setNextServerAddress( null );
         }
         else
         {
             dhcpStore.releaseLease( lease );
 
             // lease Ok, send ACK
             // FIXME...
             reply.getOptions().merge( lease.getOptions() );
 
             reply.setAssignedClientAddress( lease.getClientAddress() );
             reply.setNextServerAddress( lease.getNextServerAddress() );
 
             // fix options
             OptionsField options = reply.getOptions();
 
             // these options must not be present
             options.remove( RequestedIpAddress.class );
             options.remove( ParameterRequestList.class );
             options.remove( ClientIdentifier.class );
             options.remove( MaximumDhcpMessageSize.class );
 
             // these options must be present
             options.add( new IpAddressLeaseTime( ( lease.getExpires() - System.currentTimeMillis() ) / 1000L ) );
 
             stripUnwantedOptions( request, options );
         }
 
         return reply;
 
     }
 
 
     /*
      * @see org.apache.directory.server.dhcp.service.AbstractDhcpService#handleDISCOVER(java.net.InetSocketAddress,
      *      org.apache.directory.server.dhcp.messages.DhcpMessage)
      */
     @Override
     protected DhcpMessage handleDISCOVER( InetSocketAddress localAddress, InetSocketAddress clientAddress,
         DhcpMessage request ) throws DhcpException
     {
         Lease lease = getLeaseOffer( clientAddress, request );
 
         // null lease? don't offer one.
         if ( null == lease )
         {
             return null;
         }
 
         DhcpMessage reply = initGeneralReply( localAddress, request );
 
         reply.getOptions().merge( lease.getOptions() );
 
         reply.setMessageType( MessageType.DHCPOFFER );
 
         reply.setAssignedClientAddress( lease.getClientAddress() );
         reply.setNextServerAddress( lease.getNextServerAddress() );
 
         // fix options
         OptionsField options = reply.getOptions();
 
         // these options must not be present
         options.remove( RequestedIpAddress.class );
         options.remove( ParameterRequestList.class );
         options.remove( ClientIdentifier.class );
         options.remove( MaximumDhcpMessageSize.class );
 
         // these options must be present
         options.add( new IpAddressLeaseTime( ( lease.getExpires() - System.currentTimeMillis() ) / 1000L ) );
 
         stripUnwantedOptions( request, options );
 
         return reply;
     }
 
 
     /*
      * @see org.apache.directory.server.dhcp.service.AbstractDhcpService#handleREQUEST(java.net.InetSocketAddress,
      *      org.apache.directory.server.dhcp.messages.DhcpMessage)
      */
     @Override
     protected DhcpMessage handleREQUEST( InetSocketAddress localAddress, InetSocketAddress clientAddress,
         DhcpMessage request ) throws DhcpException
     {
         // check server ident
         AddressOptionrg/apache/directory/server/dhcp/options/AddressOption.html#AddressOption">AddressOption serverIdentOption = ( AddressOption ) request.getOptions().get( ServerIdentifier.class );
 
         if ( null != serverIdentOption && serverIdentOption.getAddress().isAnyLocalAddress() )
         {
             return null; // not me?! FIXME: handle authoritative server case
         }
 
         Lease lease = getExistingLease( clientAddress, request );
 
         DhcpMessage reply = initGeneralReply( localAddress, request );
 
         if ( null == lease )
         {
             // null lease? send NAK
             reply.setMessageType( MessageType.DHCPNAK );
             reply.setCurrentClientAddress( null );
             reply.setAssignedClientAddress( null );
             reply.setNextServerAddress( null );
         }
         else
         {
             // lease Ok, send ACK
             reply.getOptions().merge( lease.getOptions() );
 
             reply.setAssignedClientAddress( lease.getClientAddress() );
             reply.setNextServerAddress( lease.getNextServerAddress() );
 
             // fix options
             OptionsField options = reply.getOptions();
 
             // these options must not be present
             options.remove( RequestedIpAddress.class );
             options.remove( ParameterRequestList.class );
             options.remove( ClientIdentifier.class );
             options.remove( MaximumDhcpMessageSize.class );
 
             // these options must be present
             options.add( new IpAddressLeaseTime( ( lease.getExpires() - System.currentTimeMillis() ) / 1000L ) );
 
             stripUnwantedOptions( request, options );
         }
         return reply;
     }
 }