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-OFFER packet.
24  */
25 public class DhcpOfferPacket extends DhcpPacket {
26     /**
27      * The IP address of the server which sent this packet.
28      */
29     private final Inet4Address mSrcIp;
30 
31     /**
32      * Generates a OFFER packet with the specified parameters.
33      */
DhcpOfferPacket(int transId, short secs, boolean broadcast, Inet4Address serverAddress, Inet4Address relayIp, Inet4Address clientIp, Inet4Address yourIp, byte[] clientMac)34     DhcpOfferPacket(int transId, short secs, boolean broadcast, Inet4Address serverAddress,
35             Inet4Address relayIp, Inet4Address clientIp, Inet4Address yourIp, byte[] clientMac) {
36         super(transId, secs, clientIp, yourIp, serverAddress, relayIp, clientMac, broadcast);
37         mSrcIp = serverAddress;
38     }
39 
toString()40     public String toString() {
41         String s = super.toString();
42         String dnsServers = ", DNS servers: ";
43 
44         if (mDnsServers != null) {
45             for (Inet4Address dnsServer: mDnsServers) {
46                 dnsServers += dnsServer + " ";
47             }
48         }
49 
50         return s + " OFFER, ip " + mYourIp + ", mask " + mSubnetMask +
51                 dnsServers + ", gateways " + mGateways +
52                 " lease time " + mLeaseTime + ", domain " + mDomainName;
53     }
54 
55     /**
56      * Fills in a packet with the specified OFFER attributes.
57      */
buildPacket(int encap, short destUdp, short srcUdp)58     public ByteBuffer buildPacket(int encap, short destUdp, short srcUdp) {
59         ByteBuffer result = ByteBuffer.allocate(MAX_LENGTH);
60         Inet4Address destIp = mBroadcast ? INADDR_BROADCAST : mYourIp;
61         Inet4Address srcIp = mBroadcast ? INADDR_ANY : mSrcIp;
62 
63         fillInPacket(encap, destIp, srcIp, destUdp, srcUdp, result,
64             DHCP_BOOTREPLY, mBroadcast);
65         result.flip();
66         return result;
67     }
68 
69     /**
70      * Adds the optional parameters to the server-generated OFFER packet.
71      */
finishPacket(ByteBuffer buffer)72     void finishPacket(ByteBuffer buffer) {
73         addTlv(buffer, DHCP_MESSAGE_TYPE, DHCP_MESSAGE_TYPE_OFFER);
74         addTlv(buffer, DHCP_SERVER_IDENTIFIER, mServerIdentifier);
75 
76         addCommonServerTlvs(buffer);
77         addTlvEnd(buffer);
78     }
79 }
80