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 23 /** 24 * This class implements the DHCP-OFFER packet. 25 */ 26 class DhcpOfferPacket extends DhcpPacket { 27 /** 28 * The IP address of the server which sent this packet. 29 */ 30 private final InetAddress mSrcIp; 31 32 /** 33 * Generates a OFFER packet with the specified parameters. 34 */ 35 DhcpOfferPacket(int transId, boolean broadcast, InetAddress serverAddress, 36 InetAddress clientIp, byte[] clientMac) { 37 super(transId, Inet4Address.ANY, clientIp, Inet4Address.ANY, 38 Inet4Address.ANY, clientMac, broadcast); 39 mSrcIp = serverAddress; 40 } 41 42 public String toString() { 43 String s = super.toString(); 44 String dnsServers = ", DNS servers: "; 45 46 if (mDnsServers != null) { 47 for (InetAddress dnsServer: mDnsServers) { 48 dnsServers += dnsServer + " "; 49 } 50 } 51 52 return s + " OFFER, ip " + mYourIp + ", mask " + mSubnetMask + 53 dnsServers + ", gateway " + mGateway + 54 " lease time " + mLeaseTime + ", domain " + mDomainName; 55 } 56 57 /** 58 * Fills in a packet with the specified OFFER attributes. 59 */ 60 public ByteBuffer buildPacket(int encap, short destUdp, short srcUdp) { 61 ByteBuffer result = ByteBuffer.allocate(MAX_LENGTH); 62 InetAddress destIp = mBroadcast ? Inet4Address.ALL : mYourIp; 63 InetAddress srcIp = mBroadcast ? Inet4Address.ANY : mSrcIp; 64 65 fillInPacket(encap, destIp, srcIp, destUdp, srcUdp, result, 66 DHCP_BOOTREPLY, mBroadcast); 67 result.flip(); 68 return result; 69 } 70 71 /** 72 * Adds the optional parameters to the server-generated OFFER packet. 73 */ 74 void finishPacket(ByteBuffer buffer) { 75 addTlv(buffer, DHCP_MESSAGE_TYPE, DHCP_MESSAGE_TYPE_OFFER); 76 addTlv(buffer, DHCP_SERVER_IDENTIFIER, mServerIdentifier); 77 addTlv(buffer, DHCP_LEASE_TIME, mLeaseTime); 78 79 // the client should renew at 1/2 the lease-expiry interval 80 if (mLeaseTime != null) { 81 addTlv(buffer, DHCP_RENEWAL_TIME, 82 Integer.valueOf(mLeaseTime.intValue() / 2)); 83 } 84 85 addTlv(buffer, DHCP_SUBNET_MASK, mSubnetMask); 86 addTlv(buffer, DHCP_ROUTER, mGateway); 87 addTlv(buffer, DHCP_DOMAIN_NAME, mDomainName); 88 addTlv(buffer, DHCP_BROADCAST_ADDRESS, mBroadcastAddress); 89 addTlv(buffer, DHCP_DNS_SERVER, mDnsServers); 90 addTlvEnd(buffer); 91 } 92 93 /** 94 * Notifies the state machine of the OFFER packet parameters. 95 */ 96 public void doNextOp(DhcpStateMachine machine) { 97 machine.onOfferReceived(mBroadcast, mTransId, mClientMac, mYourIp, 98 mServerIdentifier); 99 } 100 } 101