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
17package android.net.dhcp;
18
19import java.net.InetAddress;
20import java.net.Inet4Address;
21import java.nio.ByteBuffer;
22import java.util.List;
23
24/**
25 * This class implements the DHCP-ACK packet.
26 */
27class 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