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.Inet4Address;
20import java.nio.ByteBuffer;
21
22/**
23 * This class implements the DHCP-ACK packet.
24 */
25class DhcpAckPacket extends DhcpPacket {
26
27    /**
28     * The address of the server which sent this packet.
29     */
30    private final Inet4Address mSrcIp;
31
32    DhcpAckPacket(int transId, short secs, boolean broadcast, Inet4Address serverAddress,
33                  Inet4Address clientIp, Inet4Address yourIp, byte[] clientMac) {
34        super(transId, secs, clientIp, yourIp, serverAddress, INADDR_ANY, clientMac, broadcast);
35        mBroadcast = broadcast;
36        mSrcIp = serverAddress;
37    }
38
39    public String toString() {
40        String s = super.toString();
41        String dnsServers = " DNS servers: ";
42
43        for (Inet4Address dnsServer: mDnsServers) {
44            dnsServers += dnsServer.toString() + " ";
45        }
46
47        return s + " ACK: your new IP " + mYourIp +
48                ", netmask " + mSubnetMask +
49                ", gateways " + mGateways + dnsServers +
50                ", lease time " + mLeaseTime;
51    }
52
53    /**
54     * Fills in a packet with the requested ACK parameters.
55     */
56    public ByteBuffer buildPacket(int encap, short destUdp, short srcUdp) {
57        ByteBuffer result = ByteBuffer.allocate(MAX_LENGTH);
58        Inet4Address destIp = mBroadcast ? INADDR_BROADCAST : mYourIp;
59        Inet4Address srcIp = mBroadcast ? INADDR_ANY : mSrcIp;
60
61        fillInPacket(encap, destIp, srcIp, destUdp, srcUdp, result,
62            DHCP_BOOTREPLY, mBroadcast);
63        result.flip();
64        return result;
65    }
66
67    /**
68     * Adds the optional parameters to the client-generated ACK packet.
69     */
70    void finishPacket(ByteBuffer buffer) {
71        addTlv(buffer, DHCP_MESSAGE_TYPE, DHCP_MESSAGE_TYPE_ACK);
72        addTlv(buffer, DHCP_SERVER_IDENTIFIER, mServerIdentifier);
73        addTlv(buffer, DHCP_LEASE_TIME, mLeaseTime);
74
75        // the client should renew at 1/2 the lease-expiry interval
76        if (mLeaseTime != null) {
77            addTlv(buffer, DHCP_RENEWAL_TIME,
78                Integer.valueOf(mLeaseTime.intValue() / 2));
79        }
80
81        addTlv(buffer, DHCP_SUBNET_MASK, mSubnetMask);
82        addTlv(buffer, DHCP_ROUTER, mGateways);
83        addTlv(buffer, DHCP_DOMAIN_NAME, mDomainName);
84        addTlv(buffer, DHCP_BROADCAST_ADDRESS, mBroadcastAddress);
85        addTlv(buffer, DHCP_DNS_SERVER, mDnsServers);
86        addTlvEnd(buffer);
87    }
88
89    /**
90     * Un-boxes an Integer, returning 0 if a null reference is supplied.
91     */
92    private static final int getInt(Integer v) {
93        if (v == null) {
94            return 0;
95        } else {
96            return v.intValue();
97        }
98    }
99}
100