package jos.system.net.jeps;

class UDPQueue
{
  final static int MAX=50;
  final static int ANYPORT=0;
  UDPPacket[] queue;
  int first;
  int last;
  int localport;
  int remoteport;
  NetworkInterface ni;
  IPAddr remoteIPAddr;

  UDPQueue(int localport,int remoteport)
  {
    this(localport,remoteport,null);    
  }

  
  UDPQueue(int localport,int remoteport, NetworkInterface ni)
  {
    this.localport=localport;
    this.remoteport=remoteport;
    this.ni=ni;
    queue=new UDPPacket[MAX];    
    first=0; last=0;
  }
  
  void bind(NetworkInterface ni)
  {
    this.ni=ni;
  }
  
  public synchronized void add(UDPPacket udpp)
  {
    if (udpp==null) return;
    if ((ni!=null) && (!ni.ipaddr.equals(((IPPacket)(udpp.wrapper)).dest))) return; 
    if (udpp.destport!=localport) return;   // ^^ On specified interface
    if ((udpp.srcport!=remoteport) && (remoteport!=ANYPORT)) return;
    if (((last+1) % MAX)==first) return; // Full! Drop packets.
    queue[last]=udpp;
    last=(last+1) % MAX;
    notifyAll();
  }
  
  public synchronized UDPPacket get()
  {
    while (last==first) { try {wait();} catch (InterruptedException e) {}}
    UDPPacket result = queue[first];
    queue[first]=null;
    first=(first+1) % MAX;
    return result;
  }
}