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;
22
23/**
24 * This class implements the DHCP-NAK packet.
25 */
26class DhcpNakPacket extends DhcpPacket {
27    /**
28     * Generates a NAK packet with the specified parameters.
29     */
30    DhcpNakPacket(int transId, InetAddress clientIp, InetAddress yourIp,
31                  InetAddress nextIp, InetAddress relayIp,
32                  byte[] clientMac) {
33        super(transId, Inet4Address.ANY, Inet4Address.ANY, nextIp, relayIp,
34            clientMac, false);
35    }
36
37    public String toString() {
38        String s = super.toString();
39        return s + " NAK, reason " + (mMessage == null ? "(none)" : mMessage);
40    }
41
42    /**
43     * Fills in a packet with the requested NAK attributes.
44     */
45    public ByteBuffer buildPacket(int encap, short destUdp, short srcUdp) {
46        ByteBuffer result = ByteBuffer.allocate(MAX_LENGTH);
47        InetAddress destIp = mClientIp;
48        InetAddress srcIp = mYourIp;
49
50        fillInPacket(encap, destIp, srcIp, destUdp, srcUdp, result,
51            DHCP_BOOTREPLY, mBroadcast);
52        result.flip();
53        return result;
54    }
55
56    /**
57     * Adds the optional parameters to the client-generated NAK packet.
58     */
59    void finishPacket(ByteBuffer buffer) {
60        addTlv(buffer, DHCP_MESSAGE_TYPE, DHCP_MESSAGE_TYPE_NAK);
61        addTlv(buffer, DHCP_SERVER_IDENTIFIER, mServerIdentifier);
62        addTlv(buffer, DHCP_MESSAGE, mMessage);
63        addTlvEnd(buffer);
64    }
65
66    /**
67     * Notifies the specified state machine of the newly-arrived NAK packet.
68     */
69    public void doNextOp(DhcpStateMachine machine) {
70        machine.onNakReceived();
71    }
72}
73