Added java and net assignments

1 files changed, 155 insertions, 0 deletions

diff --git a/sem5/oop/m7/src/Node.java b/sem5/oop/m7/src/Node.java
new file mode 100644
index 0000000..2a5d56a
--- /dev/null
+++ b/sem5/oop/m7/src/Node.java
@@ -0,0 +1,155 @@
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.concurrent.Semaphore;
+
+import java.io.OutputStream;
+import java.io.ObjectInputStream;
+import java.io.InputStream;
+
+class NodeAddr {
+	public int port;
+	public InetAddress addr;
+
+	public NodeAddr(String addr, int port) throws UnknownHostException {
+		this.port = port;
+		this.addr = InetAddress.getByName(addr);
+	}
+
+	public NodeAddr(String fulladdr) throws UnknownHostException {
+		String fields[] = fulladdr.split(":");
+		this.port = Integer.parseInt(fields[1]);
+		this.addr = InetAddress.getByName(fields[0]);
+	}
+}
+
+public class Node {
+	private NodeAddr bind;
+	private ArrayList<NodeAddr> neighbors;
+
+	private HashSet<String> seenMsgs;
+	private Semaphore lock;
+
+	public String name;
+
+	public Node(String bind, String name) throws UnknownHostException {
+		this.bind = new NodeAddr(bind);
+		this.neighbors = new ArrayList<>();
+		this.name = name;
+		this.seenMsgs = new HashSet<>();
+		this.lock = new Semaphore(1);
+	}
+	
+	public void addNeighbor(String addr) throws UnknownHostException {
+		this.neighbors.add(new NodeAddr(addr));
+	}
+
+	public void start() throws IOException {
+		ServerSocket socket = null;
+		try {
+			socket = new ServerSocket(this.bind.port, 50, this.bind.addr);
+
+			while (true) {
+				Socket conn = socket.accept();
+				Handler h = new Handler(conn, this);
+				h.start();
+			}
+		} finally {
+			if (socket != null) {
+				socket.close();
+			}
+		}
+	}
+	
+	public void sendMsgLocal(Message msg) throws Exception {
+		// Kind of hacky but thats how we do it
+		msg.id = ThreadLocalRandom.current().nextInt();
+		
+		if (!this.checkMsg(msg)) {
+			this.sendMsg(msg);
+		}
+	}
+	
+	private boolean checkMsg(Message msg) throws InterruptedException {
+		String msgid = String.format("%s%d", msg.from, msg.id);
+		this.lock.acquire();
+
+		if (this.seenMsgs.contains(msgid)) {
+			this.lock.release();
+			return true;
+		}
+		this.seenMsgs.add(msgid);
+		this.lock.release();
+		return false;
+	}
+
+	private void sendMsg(Message msg) throws Exception {
+		for (NodeAddr n : this.neighbors) {
+			Socket conn = null;
+			OutputStream out = null;
+			try {
+				conn = new Socket(n.addr, n.port);
+				out = conn.getOutputStream();
+
+				msg.send(out);
+
+			} finally {
+				if (conn != null) {
+					conn.close();
+				}
+				if (out != null) {
+					out.close();
+				}
+			}
+		}
+	}
+	
+	public void handleMsg(Message msg) throws Exception {
+		if (this.checkMsg(msg)) {
+			return;
+		}
+		if (!msg.to.equals(this.name)) {
+			msg.trace(this.name);
+
+			// Forward
+			this.sendMsg(msg);
+			
+			if (!msg.to.equals("")) {
+				return;
+			}
+		}
+		
+		msg.handle(this);
+	}
+}
+
+class Handler extends Thread {
+	private Socket conn;
+	private Node node;
+
+	public Handler(Socket conn, Node node) {
+		this.conn = conn;
+		this.node = node;
+	}
+
+	public void run() {
+		InputStream in = null;
+		ObjectInputStream objin = null;
+		try {
+			in = this.conn.getInputStream();
+			objin = new ObjectInputStream(in);
+			Object obj = objin.readObject();
+			if (!(obj instanceof Message)) {
+				throw new Exception("Received object is not a message");
+			}
+			this.node.handleMsg((Message) obj);
+		} catch (Exception e) {
+			System.err.printf("Client err: %s%n", e);
+		}
+	}
+}
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