IncomingCmd.java

/* 
SDN-Project [Rec-A and Region Optimization for controller tree mechanism]

By: Avinash Sridhar, Nachiket Rau, Shruti Ramesh, Sareena Abdul Razak

This program servers the following in SDN Project:

1) It opens 4 sockets in the range 411xx and 412xx for Rec-A and Region Optimization applications of child controllers c1, and c2
2) Above is implpemented using four different threads

		int port1 = 41101; (REC-A Child-Controller 1)
		int port2 = 41102; (REG-OPT Child-Controller 1)
		int port3 = 41201; (REC-A Child-Controller 2)
		int port4 = 41202; (REG-OPT Child-Controller 2)

3) We also have a a switch failover mechanism that happens every 10 seconds. In case the switch-controller connection is detected to be broken with
   , we will automatically point the switch to the slave controller.

 NOTE: This program is run on the machine where Mininet is running
*/

import java.net.*;
import java.io.*;
import java.lang.Runtime;
import java.lang.Process;

public class IncomingCmd extends Thread {
	private ServerSocket serverSocket;
	private long currentTime;

	public IncomingCmd(int port) throws IOException {
		serverSocket = new ServerSocket(port);
		serverSocket.setSoTimeout(0);
	}

	public IncomingCmd(long timeValue) throws IOException {
		currentTime = timeValue;
		System.out.println("IncomingCmd:: Timer thread that checks switch master-slave failover implemented");
	}

	public void run() {
		while (true) {

			// We need to ensure that only thread values 0-3 are focussed here else we will get null pointer exception as Thread-4 does not have a
			// listening socket
			if (!Thread.currentThread().getName().equals("Thread-4")) {
				System.out.println("IncomingCmd::run(): Thread Started " + Thread.currentThread().getName());
				try {
					System.out.println("IncomingCmd::run(): Listening on socket " + serverSocket.getLocalPort());
					Socket server = serverSocket.accept();
					DataInputStream in = new DataInputStream(server.getInputStream());
					String checkInput = in.readUTF();
					System.out.println(checkInput);
					// Based on the string we receive from other end, the Rec-A application will execute one of the below commands on the switch gs1 or gs2
					if (checkInput.equals("Delete-gs1")) {
						try {
							Process p = Runtime.getRuntime().exec("sudo ovs-vsctl del-port gs1 gs1-eth1");
						}
						catch (IOException e) { System.out.println("IncomingCmd::run(): Error deleting G-Switch 1 port gs1-eth1"); }
					}
					else if (checkInput.equals("Delete-gs2")) {
						try {
							Process p = Runtime.getRuntime().exec("sudo ovs-vsctl del-port gs2 gs2-eth1");
						}
						catch (IOException e) {System.out.println("IncomingCmd::run(): Error deleting G-Switch 2 port gs2-eth1"); }
					}
					else if (checkInput.equals("Pull-gs1")) {
						try {
							Process p = Runtime.getRuntime().exec("sudo ovs-vsctl add-port gs1 gs1-eth1");
						}
						catch (IOException e) {System.out.println("IncomingCmd::run(): Error adding G-Switch 1 port gs1-eth1"); }
					}
					else if (checkInput.equals("Pull-gs2")) {
						try {
							Process p = Runtime.getRuntime().exec("sudo ovs-vsctl add-port gs2 gs2-eth1");
						}
						catch(IOException e) {System.out.println("IncomingCmd::run(): Error adding G-Switch 2 port gs2-eth1"); }
					}
					else if (checkInput.startsWith("Switch-Controller"))
					{
						String switchNumber = checkInput.substring(18, 19);
						switchController(switchNumber);
					}
				}
				// We should not run into socket timeout exceptions as we use infinite time out. However, catching exception as a precaution
				catch (SocketTimeoutException s) {System.out.println("IncomingCmd::run(): Socket Timed Out"); }
				catch (IOException e) {
					System.out.println("IncomingCmd::run() Error receiving data from socket");
					e.printStackTrace();
				}
			}

			// Only for the failover 5th thread that handles failover of switch with master-slave controllers
			else if (Thread.currentThread().getName().equals("Thread-4") && (System.currentTimeMillis() - currentTime) > 10000) {
				currentTime = System.currentTimeMillis();
				String[] switchList = {"s1", "s2", "s3", "s4"};
				for ( String switchID : switchList) {
					checkFailover(switchID);
				}
			}
		}
	}

	// Function to switch the switch's controller role
	public void switchController(String switchID) {

		// If the child controller 1 is initiating switch to fail over to new controller,
		if (serverSocket.getLocalPort() == 41102) {
			try {
				Process p = Runtime.getRuntime().exec("sudo ovs-vsctl del-controller " + switchID);

				// Note that the below controller IP may change if needed based on testing
				p = Runtime.getRuntime().exec("sudo ovs-vsctl set-controller " + switchID + " tcp:192.168.56.101:6633");
			}
			catch(IOException e) {System.out.println("IncomingCmd::switchController(): Error performing controller commands for switch " + switchID); }
		}
		else if (serverSocket.getLocalPort() == 41202) {
			try {
				Process p = Runtime.getRuntime().exec("sudo ovs-vsctl del-controller " + switchID);

				// Note that the below controller IP may change if needed based on testing
				p = Runtime.getRuntime().exec("sudo ovs-vsctl set-controller " + switchID + " tcp:192.168.56.102:6633");
			}
			catch(IOException e) {System.out.println("IncomingCmd::switchController(): Error performing controller commands for switch " + switchID); }
		}
	}

	// Function to check if failover of switch is required. If so, do the needful from master to slave and vice versa
	public void checkFailover(String switchID) {

		// Obtain the current switch's current controller
		try {
			Process p = Runtime.getRuntime().exec("sudo ovs-vsctl get-controller " + switchID);
			BufferedReader input = new BufferedReader(new InputStreamReader(p.getInputStream()));
			String controller = input.readLine();
			System.out.println("IncomingCmd::checkFailover(): " + switchID + " connected to controller " + controller);

			// Based on the switch's current controller, check if it's connectivity is true/false. If false, do the failover to slave controller.
			// Below check command is obtained from mininet Node.py code --> https://github.com/mininet/mininet/blob/master/mininet/node.py under
			// def connected().
			// There is another issue here where we have to take care of a null pointer exception in case the above command does not return a current controller
			// This seems to happen probably because the ovs-vsctl set-controller command for a specific switch is not being taken into effect.
			// Maybe the commands are executing too fast, leading to some sort of a race condition. Hence we need to ensure we give some gap of 1 second,
			// to prevent the race condition. This will be done by making the thread sleep for a gap of 1 second as safety. We also check for controller string to
			// not be null in order to ensure we don't run into Null Pointer Exception. This way entire program won't crash.
                        if (controller != null) {      
				if (controller.equals("tcp:192.168.56.1:6633")) {
					p = Runtime.getRuntime().exec("sudo ovs-vsctl -- get Controller " + switchID + " is_connected");
					BufferedReader newInput = new BufferedReader(new InputStreamReader(p.getInputStream()));
					String newInputString = newInput.readLine();
					System.out.println("IncomingCmd::checkFailover(): Is " + switchID + " connected to current controller? " + newInputString);
					if (newInputString.equals("false")) {
						p = Runtime.getRuntime().exec("sudo ovs-vsctl del-controller " + switchID);
						Thread.sleep(1000);
						p = Runtime.getRuntime().exec("sudo ovs-vsctl set-controller " + switchID + " tcp:192.168.56.102:6633");
					}
				}
				else if (controller.equals("tcp:192.168.56.102:6633")) {
					p = Runtime.getRuntime().exec("sudo ovs-vsctl -- get Controller " + switchID + " is_connected");
					BufferedReader newInput = new BufferedReader(new InputStreamReader(p.getInputStream()));
					String newInputString = newInput.readLine();
					System.out.println("IncomingCmd::checkFailover(): Is " + switchID + " connected to current controller? " + newInputString);
					if (newInputString.equals("false")) {			
						p = Runtime.getRuntime().exec("sudo ovs-vsctl del-controller " + switchID);
						Thread.sleep(1000);
						p = Runtime.getRuntime().exec("sudo ovs-vsctl set-controller " + switchID + " tcp:192.168.56.1:6633");
					}
				}
			}
		}					
		
		catch(IOException e) {System.out.println("IncomingCmd::checkFailover(): Error executing commands for switch " + switchID); }
		catch(InterruptedException ie) {System.out.println("IncomingCmd::checkFailover() Error with thread sleep "); }
	}

	public static void main(String[] args) {
		System.out.println("IncomingCmd::main() Started");

		// 411xx is the listening socket for Rec-A and Region Optimization modules of child controller c1. 412xx are the listening sockets for same
		// applications for child controller c2.
		int port1 = 41101;
		int port2 = 41102;
		int port3 = 41201;
		int port4 = 41202;
		long timer = System.currentTimeMillis();
		try {
			Thread t1 = new IncomingCmd(port1);
			Thread t2 = new IncomingCmd(port2);
			Thread t3 = new IncomingCmd(port3);
			Thread t4 = new IncomingCmd(port4);
			Thread t5 = new IncomingCmd(timer);
			t1.start();
			t2.start();
			t3.start();
			t4.start();
			t5.start();

		}
		catch (IOException e) {
			System.out.println("IncomingCmd::main() Error starting thread");
			e.printStackTrace();
		}
	}
}