import java.net.*;
import java.io.*;

public class Router {
    final static int BUF_LENGTH = 1024;
    
    public static void main(String[] args) {
	ServerSocket clientSocket = null;
	try {
	    clientSocket = new ServerSocket(Integer.parseInt(args[1]));
	} catch (IOException e) {
	    System.err.println("Could not listen on port: "+args[1]);
	    System.exit(1);
	}
	
	ServerSocket serverSocket = null;
	try {
	    serverSocket = new ServerSocket(Integer.parseInt(args[0]));
	} catch (IOException e) {
	    System.err.println("Could not listen on port: "+args[0]);
	    System.exit(1);
	}
	
	Socket bankSocket = null;
	try {
	    bankSocket = serverSocket.accept();
	    serverSocket.close();
	    System.out.println("Bank connected to the router.");
	} catch (IOException e) {
	    System.err.println("Bank Socket Accept() failed.");
	    System.exit(1);
	}
	
	Socket atmSocket = null;
	try {
	    atmSocket = clientSocket.accept();
	    clientSocket.close();
	    System.out.println("ATM connected to the router.");
	} catch (IOException e) {
	    System.err.println("ATM Socket Accept() failed.");
	    System.exit(1);
	}
	
	byte buf[] = new byte[BUF_LENGTH];
	int len; 
	InputStream atmSocketInputStream = null;
	OutputStream atmSocketOutputStream = null;
	InputStream bankSocketInputStream = null;
	OutputStream bankSocketOutputStream = null;
	try {
	    atmSocketInputStream = atmSocket.getInputStream();
	    atmSocketOutputStream = atmSocket.getOutputStream();
	    bankSocketInputStream = bankSocket.getInputStream();
	    bankSocketOutputStream = bankSocket.getOutputStream();
	} catch (IOException e) {
	    e.printStackTrace();
	}
	
	while (true) {
	    try {
		if (atmSocket.isClosed() || bankSocket.isClosed()) {
		    System.exit(0);
		}

		if ((len = bankSocketInputStream.available()) > 0) {
		    bankSocketInputStream.read(buf,0,len);
		    atmSocketOutputStream.write(buf,0,len);
		    System.out.println("sent " + len + " bytes from Bank to ATM");
		}
		
		if ((len = atmSocketInputStream.available()) > 0) {
		    atmSocketInputStream.read(buf,0,len);
		    bankSocketOutputStream.write(buf,0,len);
		    System.out.println("sent " + len + " bytes from ATM to Bank");
		}
	    } catch (IOException e) {	    
		// Connection may have been closed
		System.out.println("The ATM or Bank connection to the router may have been closed");
	    }
	}
    }
}