package jos.system.net.jeps;

import java.io.*;

class UDPPacket extends Packet
{
  public final int HEADER_LEN = 8;

  int srcport;		// Source Protocol Port Number
  int destport;		// Destination Prot. Port Number
  int length;		// Length of data
  int checksum;		// Checksum (over __Pseudoheader__+data)
  
  UDPPacket()
  {
    super();
    protocol=0x11;
  }
  
  UDPPacket(byte[] raw)
  {
    protocol=0x11;
    data = raw;
    parse();
  }

  UDPPacket(Packet p)
  {
    this(p.data);
    wrapper=p.wrapper;
  }

  void parse()
  {
    DataInputStream ds=new DataInputStream(new ByteArrayInputStream(data,0,8));
    try 
     { 
      srcport=ds.readUnsignedShort();
      destport=ds.readUnsignedShort();
      length=ds.readUnsignedShort();
      checksum=ds.readUnsignedShort();
     }
    catch (EOFException e) {}
    catch (IOException e) {}
  }

  public void update()
  {
    checksum=0;
    data[0]=(byte)(srcport >> 8);
    data[1]=(byte)(srcport & 0xff);
    data[2]=(byte)(destport >> 8);
    data[3]=(byte)(destport & 0xff);
    data[4]=(byte)(length >> 8);
    data[5]=(byte)(length & 0xff);
    data[6]=(byte)(checksum >> 8);
    data[7]=(byte)(checksum & 0xff);
/*    checksum=checksum(data.length);
    data[2]=(byte)(checksum >> 8);
    data[3]=(byte)(checksum & 0xff);*/
  }
  
  public String toString()
  {
    return "UDP: "+srcport+"/"+destport+"/"+length+"/"+checksum;
  }
};