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      1 /*
      2  * Copyright (C) 2010 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.net.dhcp;
     18 
     19 import java.net.InetAddress;
     20 import java.net.Inet4Address;
     21 import java.nio.ByteBuffer;
     22 import java.util.List;
     23 
     24 /**
     25  * This class implements the DHCP-ACK packet.
     26  */
     27 class DhcpAckPacket extends DhcpPacket {
     28 
     29     /**
     30      * The address of the server which sent this packet.
     31      */
     32     private final InetAddress mSrcIp;
     33 
     34     DhcpAckPacket(int transId, boolean broadcast, InetAddress serverAddress,
     35                   InetAddress clientIp, byte[] clientMac) {
     36         super(transId, Inet4Address.ANY, clientIp, serverAddress,
     37             Inet4Address.ANY, clientMac, broadcast);
     38         mBroadcast = broadcast;
     39         mSrcIp = serverAddress;
     40     }
     41 
     42     public String toString() {
     43         String s = super.toString();
     44         String dnsServers = " DNS servers: ";
     45 
     46         for (InetAddress dnsServer: mDnsServers) {
     47             dnsServers += dnsServer.toString() + " ";
     48         }
     49 
     50         return s + " ACK: your new IP " + mYourIp +
     51                 ", netmask " + mSubnetMask +
     52                 ", gateway " + mGateway + dnsServers +
     53                 ", lease time " + mLeaseTime;
     54     }
     55 
     56     /**
     57      * Fills in a packet with the requested ACK parameters.
     58      */
     59     public ByteBuffer buildPacket(int encap, short destUdp, short srcUdp) {
     60         ByteBuffer result = ByteBuffer.allocate(MAX_LENGTH);
     61         InetAddress destIp = mBroadcast ? Inet4Address.ALL : mYourIp;
     62         InetAddress srcIp = mBroadcast ? Inet4Address.ANY : mSrcIp;
     63 
     64         fillInPacket(encap, destIp, srcIp, destUdp, srcUdp, result,
     65             DHCP_BOOTREPLY, mBroadcast);
     66         result.flip();
     67         return result;
     68     }
     69 
     70     /**
     71      * Adds the optional parameters to the client-generated ACK packet.
     72      */
     73     void finishPacket(ByteBuffer buffer) {
     74         addTlv(buffer, DHCP_MESSAGE_TYPE, DHCP_MESSAGE_TYPE_ACK);
     75         addTlv(buffer, DHCP_SERVER_IDENTIFIER, mServerIdentifier);
     76         addTlv(buffer, DHCP_LEASE_TIME, mLeaseTime);
     77 
     78         // the client should renew at 1/2 the lease-expiry interval
     79         if (mLeaseTime != null) {
     80             addTlv(buffer, DHCP_RENEWAL_TIME,
     81                 Integer.valueOf(mLeaseTime.intValue() / 2));
     82         }
     83 
     84         addTlv(buffer, DHCP_SUBNET_MASK, mSubnetMask);
     85         addTlv(buffer, DHCP_ROUTER, mGateway);
     86         addTlv(buffer, DHCP_DOMAIN_NAME, mDomainName);
     87         addTlv(buffer, DHCP_BROADCAST_ADDRESS, mBroadcastAddress);
     88         addTlv(buffer, DHCP_DNS_SERVER, mDnsServers);
     89         addTlvEnd(buffer);
     90     }
     91 
     92     /**
     93      * Un-boxes an Integer, returning 0 if a null reference is supplied.
     94      */
     95     private static final int getInt(Integer v) {
     96         if (v == null) {
     97             return 0;
     98         } else {
     99             return v.intValue();
    100         }
    101     }
    102 
    103     /**
    104      * Notifies the specified state machine of the ACK packet parameters.
    105      */
    106     public void doNextOp(DhcpStateMachine machine) {
    107         machine.onAckReceived(mYourIp, mSubnetMask, mGateway, mDnsServers,
    108             mServerIdentifier, getInt(mLeaseTime));
    109     }
    110 }
    111