rreppacket.java

DSr project for the java applications

package dsr;



import java.net.*;
import java.util.*;
import java.lang.*;
import java.io.*;

//This implements the RREP packet
class RREPPacket {
  public byte type;              //the type of the packet. not really required here since all
                                 //packets have seperate class
  public short flags;            //represents the flags information
  public byte hopCount;          //hop count
  public int dstSeqNum;          //destination sequence number
  public InetAddress dstIPAddr;  //destination ip address
  public InetAddress orgIPAddr;  //originator's ip address
//  public int lifetime;

  //default constructor
  public RREPPacket() {}

  //constructor
  public RREPPacket (byte type, byte hopCount, int dstSeqNum,
                     InetAddress dstIPAddr, InetAddress orgIPAddr) {
    this.type = type;
    this.flags = (byte)2;
    this.hopCount = hopCount;
    this.dstSeqNum = dstSeqNum;
    this.dstIPAddr = dstIPAddr;
    this.orgIPAddr = orgIPAddr;
    //this.lifetime = lifetime;
  }

  //copy constructor
  public RREPPacket (RREPPacket rhs) {
    this.type = rhs.type;
    this.flags = rhs.flags;
    this.hopCount = rhs.hopCount;
    this.dstSeqNum = rhs.dstSeqNum;
    this.dstIPAddr = rhs.dstIPAddr;
    this.orgIPAddr = rhs.orgIPAddr;
    //this.lifetime = rhs.lifetime;
  }

  //decodes the datagram packet to get the RREP packet information
  //the datagram packet transmitted over the net is in bytes which needs to be decoded
  public RREPPacket decode(DatagramPacket packet) {
    ByteArrayInputStream payload = new ByteArrayInputStream(packet.getData());
    DataInputStream src = new DataInputStream(payload);
    try{
      this.type = src.readByte();
      this.flags = src.readShort();
      this.hopCount = src.readByte();
      this.dstSeqNum = src.readInt();
      byte b[] = new byte[4];
      src.read(b, 0, 4);
      this.dstIPAddr = InetAddress.getByAddress(b);
      src.read(b, 0, 4);
      this.orgIPAddr = InetAddress.getByAddress(b);
      //this.lifetime = src.readInt();
    } catch (IOException ie) {
      System.out.println("IO ERROR in decode\n");
    }
    return this;
  }

  //since the datagram packet has to be in bytes when being transmitted over the net
  //the RREP packet has to be converted into bytes first
  public  byte[] encode(RREPPacket packet) {
    ByteArrayOutputStream buf = new ByteArrayOutputStream();
    DataOutputStream out = new DataOutputStream(buf);
    try {
      out.writeByte(this.type);
      out.writeShort(this.flags);
      out.writeByte(this.hopCount);
      out.writeInt(this.dstSeqNum);
      try{
        out.write((packet.dstIPAddr).getAddress(), 0, 4);
        out.write((packet.orgIPAddr).getAddress(), 0, 4);
      } catch (NullPointerException e) {
        System.out.println("the message is " + e.getMessage());
      }
      //out.writeInt(this.lifetime);
      out.flush();
    } catch (IOException ie) {
      System.out.println("IO ERROR\n");
    }
    return buf.toByteArray();
  }

  //put info in displayable form
  public String toString() {
    final String EOLN = java.lang.System.getProperty("line.separator");
    String value = "type = " + type + EOLN +
                   "flags = " + flags + EOLN +
                   "hop Count = " + hopCount + EOLN +
                   "Destination Sequence # = " + dstSeqNum + EOLN +
                   "Destination Address = " + dstIPAddr + EOLN +
                   "Originator IP Address = " + orgIPAddr + EOLN;
    //             "Lifetime = " + lifetime + EOLN;
    return value;
  }
}