private int getAck(TcpSegment segment) {
int retval;
// The ack # depends on the segment's flags.
switch (segment.getFlags()) {
case TcpSegment.FIN:
case TcpSegment.SYN:
case TcpSegment.FIN_ACK:
case TcpSegment.SYN_ACK:
retval = segment.getSequenceNumber() + 1;
break;
case TcpSegment.PSH:
case TcpSegment.PSH_ACK:
retval = segment.getSequenceNumber() + segment.getDataSize();
break;
case TcpSegment.ACK:
default:
retval = segment.getSequenceNumber();
break;
}
return (retval);
}
public final void handleReceive(DatagramPacket packet, AsyncDatagramSocket dgram_socket) {
synchronized (this) {
try {
TcpSegment segment = new TcpSegment(packet);
Object[] args = new Object[1];
// Generate the appropriate transition based on
// the header flags.
args[0] = segment;
// DEBUG
// System.out.println(
// "Receive event from " +
// packet.getAddress() +
// ":" +
// Integer.toString(packet.getPort()) +
// ":\n" +
// segment);
// REFLECTION
// Uncomment the following line to output
// transitions.
// _outputTransitions();
_transition_table[segment.getFlags()].invoke(_fsm, args);
} catch (Exception jex) {
System.err.println(jex);
jex.printStackTrace();
} finally {
this.notify();
}
}
return;
}
