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
51                 + ", netmask " + mSubnetMask + dnsServers
52                 + ", gateways " + mGateways
53                 + ", lease time " + mLeaseTime
54                 + ", domain " + mDomainName
55                 + (mIpv6OnlyWaitTime != null ? ", V6ONLY_WAIT " + mIpv6OnlyWaitTime : "");
56     }
57 
58     /**
59      * Fills in a packet with the specified OFFER attributes.
60      */
buildPacket(int encap, short destUdp, short srcUdp)61     public ByteBuffer buildPacket(int encap, short destUdp, short srcUdp) {
62         ByteBuffer result = ByteBuffer.allocate(MAX_LENGTH);
63         Inet4Address destIp = mBroadcast ? INADDR_BROADCAST : mYourIp;
64         Inet4Address srcIp = mBroadcast ? INADDR_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      */
finishPacket(ByteBuffer buffer)75     void finishPacket(ByteBuffer buffer) {
76         addTlv(buffer, DHCP_MESSAGE_TYPE, DHCP_MESSAGE_TYPE_OFFER);
77         addTlv(buffer, DHCP_SERVER_IDENTIFIER, mServerIdentifier);
78 
79         addCommonServerTlvs(buffer);
80         addTlvEnd(buffer);
81     }
82 }
83