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.Inet4Address;
20 import java.nio.ByteBuffer;
21 
22 /**
23  * This class implements the DHCP-ACK packet.
24  */
25 public class DhcpAckPacket extends DhcpPacket {
26 
27     /**
28      * The address of the server which sent this packet.
29      */
30     private final Inet4Address mSrcIp;
31 
DhcpAckPacket(int transId, short secs, boolean broadcast, Inet4Address serverAddress, Inet4Address relayIp, Inet4Address clientIp, Inet4Address yourIp, byte[] clientMac, boolean rapidCommit)32     DhcpAckPacket(int transId, short secs, boolean broadcast, Inet4Address serverAddress,
33             Inet4Address relayIp, Inet4Address clientIp, Inet4Address yourIp, byte[] clientMac,
34             boolean rapidCommit) {
35         super(transId, secs, clientIp, yourIp, serverAddress, relayIp, clientMac, broadcast);
36         mBroadcast = broadcast;
37         mSrcIp = serverAddress;
38         mRapidCommit = rapidCommit;
39     }
40 
toString()41     public String toString() {
42         String s = super.toString();
43         String dnsServers = " DNS servers: ";
44 
45         for (Inet4Address dnsServer: mDnsServers) {
46             dnsServers += dnsServer.toString() + " ";
47         }
48 
49         return s + " ACK: your new IP " + mYourIp
50                 + ", netmask " + mSubnetMask
51                 + ", gateways " + mGateways + dnsServers
52                 + ", lease time " + mLeaseTime
53                 + (mIpv6OnlyWaitTime != null ? ", V6ONLY_WAIT " + mIpv6OnlyWaitTime : "");
54     }
55 
56     /**
57      * Fills in a packet with the requested ACK parameters.
58      */
buildPacket(int encap, short destUdp, short srcUdp)59     public ByteBuffer buildPacket(int encap, short destUdp, short srcUdp) {
60         ByteBuffer result = ByteBuffer.allocate(MAX_LENGTH);
61         Inet4Address destIp = mBroadcast ? INADDR_BROADCAST : mYourIp;
62         Inet4Address srcIp = mBroadcast ? INADDR_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      */
finishPacket(ByteBuffer buffer)73     void finishPacket(ByteBuffer buffer) {
74         addTlv(buffer, DHCP_MESSAGE_TYPE, DHCP_MESSAGE_TYPE_ACK);
75         addTlv(buffer, DHCP_SERVER_IDENTIFIER, mServerIdentifier);
76         addCommonServerTlvs(buffer);
77         if (mRapidCommit) {
78             addTlv(buffer, DHCP_RAPID_COMMIT);
79         }
80         addTlvEnd(buffer);
81     }
82 
83     /**
84      * Un-boxes an Integer, returning 0 if a null reference is supplied.
85      */
getInt(Integer v)86     private static final int getInt(Integer v) {
87         if (v == null) {
88             return 0;
89         } else {
90             return v.intValue();
91         }
92     }
93 }
94