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-OFFER packet.
26 */
27class DhcpOfferPacket extends DhcpPacket {
28    /**
29     * The IP address of the server which sent this packet.
30     */
31    private final InetAddress mSrcIp;
32
33    /**
34     * Generates a OFFER packet with the specified parameters.
35     */
36    DhcpOfferPacket(int transId, boolean broadcast, InetAddress serverAddress,
37                    InetAddress clientIp, byte[] clientMac) {
38        super(transId, Inet4Address.ANY, clientIp, Inet4Address.ANY,
39            Inet4Address.ANY, clientMac, broadcast);
40        mSrcIp = serverAddress;
41    }
42
43    public String toString() {
44        String s = super.toString();
45        String dnsServers = ", DNS servers: ";
46
47        if (mDnsServers != null) {
48            for (InetAddress dnsServer: mDnsServers) {
49                dnsServers += dnsServer + " ";
50            }
51        }
52
53        return s + " OFFER, ip " + mYourIp + ", mask " + mSubnetMask +
54                dnsServers + ", gateway " + mGateway +
55                " lease time " + mLeaseTime + ", domain " + mDomainName;
56    }
57
58    /**
59     * Fills in a packet with the specified OFFER attributes.
60     */
61    public ByteBuffer buildPacket(int encap, short destUdp, short srcUdp) {
62        ByteBuffer result = ByteBuffer.allocate(MAX_LENGTH);
63        InetAddress destIp = mBroadcast ? Inet4Address.ALL : mYourIp;
64        InetAddress srcIp = mBroadcast ? Inet4Address.ANY : mSrcIp;
65
66        fillInPacket(encap, destIp, srcIp, destUdp, srcUdp, result,
67            DHCP_BOOTREPLY, mBroadcast);
68        result.flip();
69        return result;
70    }
71
72    /**
73     * Adds the optional parameters to the server-generated OFFER packet.
74     */
75    void finishPacket(ByteBuffer buffer) {
76        addTlv(buffer, DHCP_MESSAGE_TYPE, DHCP_MESSAGE_TYPE_OFFER);
77        addTlv(buffer, DHCP_SERVER_IDENTIFIER, mServerIdentifier);
78        addTlv(buffer, DHCP_LEASE_TIME, mLeaseTime);
79
80        // the client should renew at 1/2 the lease-expiry interval
81        if (mLeaseTime != null) {
82            addTlv(buffer, DHCP_RENEWAL_TIME,
83                Integer.valueOf(mLeaseTime.intValue() / 2));
84        }
85
86        addTlv(buffer, DHCP_SUBNET_MASK, mSubnetMask);
87        addTlv(buffer, DHCP_ROUTER, mGateway);
88        addTlv(buffer, DHCP_DOMAIN_NAME, mDomainName);
89        addTlv(buffer, DHCP_BROADCAST_ADDRESS, mBroadcastAddress);
90        addTlv(buffer, DHCP_DNS_SERVER, mDnsServers);
91        addTlvEnd(buffer);
92    }
93
94    /**
95     * Notifies the state machine of the OFFER packet parameters.
96     */
97    public void doNextOp(DhcpStateMachine machine) {
98        machine.onOfferReceived(mBroadcast, mTransId, mClientMac, mYourIp,
99            mServerIdentifier);
100    }
101}
102