Home | History | Annotate | Download | only in dhcp 
      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.InetAddress;
     20 import java.net.Inet4Address;
     21 import java.nio.ByteBuffer;
     22 
     23 /**
     24  * This class implements the DHCP-NAK packet.
     25  */
     26 class 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