task 5 started.

week3_TinsaeGhilay/Task 2/README.md

@@ -23,3 +23,116 @@
     ```bash
     java -cp "out:lib/*" client.Client
     ```
+
+
+    ### inspecting packets using wireshark.
+    ***
+    #### Normal functions
+    ***
+
+    I installed wireshark-cli and run 
+    ```bash
+    sudo tshark -i lo -f "tcp port 8080" -z follow,tcp,ascii,0
+    ```
+    In Client program the interaction looked like this
+    ```
+    Enter an integer: 4
+    Enter an integer: 6
+    The sum is: 10
+    ```
+    And the output of wireshark was as follows
+
+    ```xml
+        POST /RPC2 HTTP/1.1
+        Content-Type: text/xml
+        User-Agent: Apache XML RPC 3.0 (Sun HTTP Transport)
+        Cache-Control: no-cache
+        Pragma: no-cache
+        Host: localhost:8080
+        Accept: */*
+        Connection: keep-alive
+        Content-Length: 195
+
+        <?xml version="1.0" encoding="UTF-8"?>
+        <methodCall>
+            <methodName>sample.sum</methodName>
+            <params>
+                <param>
+                    <value><i4>4</i4></value>
+                </param>
+                <param>
+                    <value><i4>6</i4></value>
+                </param>
+            </params>
+        </methodCall>
+
+    HTTP/1.1 200 OK
+    Server: Apache XML-RPC 1.0
+    Connection: close
+    Content-Type: text/xml
+    Content-Length: 129
+
+    <?xml version="1.0" encoding="UTF-8"?>
+    <methodResponse>
+        <params>
+            <param>
+                <value><i4>10</i4></value>
+            </param>
+        </params>
+    </methodResponse>
+    ```
+	I believe this is the expected result.
+
+    ***
+    #### Intentional error
+    I changed the messge call string to `sample.add` instead of the correct `sample.sum` and run the program. obviously it threw an exception. the http response from wireguard was as follows
+    ```xml
+    POST /RPC2 HTTP/1.1
+    Content-Type: text/xml
+    User-Agent: Apache XML RPC 3.0 (Sun HTTP Transport)
+    Cache-Control: no-cache
+    Pragma: no-cache
+    Host: localhost:8080
+    Accept: */*
+    Connection: keep-alive
+    Content-Length: 196
+
+    <?xml version="1.0" encoding="UTF-8"?>
+    <methodCall>
+        <methodName>sample.add</methodName>
+            <params>
+                <param>
+                    <value><i4>23</i4></value>
+                </param>
+                <param>
+                    <value><i4>4</i4></value>
+                </param>
+            </params>
+        </methodCall>
+
+    HTTP/1.1 200 OK
+    Server: Apache XML-RPC 1.0
+    Connection: close
+    Content-Type: text/xml
+    Content-Length: 265
+
+    <?xml version="1.0" encoding="UTF-8"?>
+    <methodResponse>
+        <fault>
+            <value>
+                <struct>
+                    <member>
+                        <name>faultCode</name>
+                        <value><i4>0</i4></value>
+                    </member>
+                    <member>
+                        <name>faultString</name>
+                        <value>No such handler: sample.add</value>
+                    </member>
+                </struct>
+            </value>
+        </fault>
+    </methodResponse>
+    ```
+    Again the expected results. I only tested it in one machine. so time will be done may be another time.
+    

week3_TinsaeGhilay/Task 2/src/client/Client.java

@@ -4,6 +4,7 @@ package client;
 import java.util.Vector;
 import java.util.Scanner;
 import java.net.URL;
+import java.net.URI;
 
 /**
  * Client class for XML-RPC communication
@@ -33,16 +34,11 @@ public class Client {
             // URL can be any valid URL. the default port for XML-RPC is 80
             // but here we use 8080 since 80 may need root privileges
             XmlRpcClientConfigImpl config = new XmlRpcClientConfigImpl();
-            config.setServerURL(URI.create("http://localhost:8080/RPC2").toURL());
+            // config.setServerURL(new URL("http://localhost:8080/RPC2"));
+            config.setServerURL(new URI("http://localhost:8080/RPC2").toURL());
             XmlRpcClient client = new XmlRpcClient();
             client.setConfig(config);
 
-            // Logging of XML-RPC messages between server and client
-            XmlRpcCommonsTransportFactory factory = new XmlRpcCommonsTransportFactory(client);
-            // enable logging
-            factory.setEnableLogging(true);
-            client.setTransportFactory(factory);
-
             while (true) {
                 // create parameters to be sent to server method in a vector
                 // and populate it
@@ -56,7 +52,7 @@ public class Client {
                 // make the remote method call
                 // the result of the remot call must be an Object
                 // and be casted to the appropriate type
-                Object result = client.execute("sample.sum", params);
+                Object result = client.execute("sample.add", params);
                 // process the result
                 int sum = ((Integer) result).intValue();
                 System.out.println("The sum is: " + sum);

week3_TinsaeGhilay/Task 2/src/server/Server.java

@@ -14,11 +14,6 @@ import java.net.URL;
 import org.apache.xmlrpc.server.PropertyHandlerMapping;
 import org.apache.xmlrpc.server.XmlRpcServer;
 
-// logging imports
-import java.util.logging.ConsoleHandler;
-import java.util.logging.Level;
-import java.util.logging.Logger;
-
 public class Server {
 
     private static String TAG = "Server";
@@ -26,6 +21,7 @@ public class Server {
     public static void main(String[] args) {
 
         try {
+
             // start XML-RPC server at port 8080
             WebServer server = new WebServer(8080);
             XmlRpcServer xmlRpcServer = server.getXmlRpcServer();

week3_TinsaeGhilay/Task 5/src/client/Client.java

@@ -0,0 +1,66 @@
+package client;
+
+import java.rmi.server.UnicastRemoteObject;
+import java.rmi.RemoteException;
+import java.rmi.registry.LocateRegistry;
+import java.rmi.registry.Registry;
+import java.util.Scanner;
+import common.ClientInterface;
+import common.ServerInterface;
+
+public class Client extends UnicastRemoteObject implements ClientInterface {
+    private String clientId;
+    private ServerInterface server;
+
+    protected Client(String clientId, ServerInterface server) throws RemoteException {
+        super();
+        this.clientId = clientId;
+        this.server = server;
+        server.registerClient(clientId, this);
+    }
+
+    public void sendMessage(String toId, String message) throws RemoteException {
+        server.sendMessage(clientId, toId, message);
+    }
+
+    public void blockClient(String blockedId) throws RemoteException {
+        server.blockClient(clientId, blockedId);
+    }
+
+    @Override
+    public void receiveMessage(String fromId, String message) throws RemoteException {
+        System.out.println("[" + fromId + "]: " + message);
+    }
+
+    // entry point
+    public static void main(String[] args) {
+        try (Scanner scanner = new Scanner(System.in)) {
+            // get client ID and server info
+            System.out.print("Enter your client ID: ");
+            String clientId = scanner.nextLine();
+
+            // get recipient ID
+            System.out.print("Enter recipient ID: ");
+            String toId = scanner.nextLine();
+
+            Registry registry = LocateRegistry.getRegistry("localhost", 1099);
+            ServerInterface server = (ServerInterface) registry.lookup("ChatServer");
+
+            Client client = new Client(clientId, server);
+
+            System.out.print("You can start chatting now. Type your messages below: Type exit to log out\n");
+
+            while (true) {
+                String msg = scanner.nextLine();
+                if (msg.equalsIgnoreCase("exit")) {
+                    System.out.println("Logging out...");
+                    break;
+                }
+                client.sendMessage(toId, msg);
+            }
+        } catch (Exception e) {
+            System.err.println("Client exception: " + e.getMessage());
+        }
+    }
+
+}

week3_TinsaeGhilay/Task 5/src/common/ClientInterface.java

@@ -0,0 +1,16 @@
+package common;
+
+/**
+ * ClientInterface interface
+ * 
+ * @author Tinsae Ghilay
+ *
+ */
+import java.rmi.Remote;
+import java.rmi.RemoteException;
+
+public interface ClientInterface extends Remote {
+
+    void receiveMessage(String fromId, String message) throws RemoteException;
+
+}

week3_TinsaeGhilay/Task 5/src/common/ServerInterface.java

@@ -0,0 +1,23 @@
+package common;
+
+/**
+ * ClientInterface interface
+ * 
+ * @author Tinsae Ghilay
+ *
+ */
+import java.rmi.Remote;
+import java.rmi.RemoteException;
+import java.util.List;
+
+public interface ServerInterface extends Remote {
+
+    void registerClient(String clientId, ClientInterface client) throws RemoteException;
+
+    void sendMessage(String fromId, String toId, String message) throws RemoteException;
+
+    void blockClient(String clientId, String blockedId) throws RemoteException;
+
+    List<String> getOfflineMessages(String clientId) throws RemoteException;
+
+}

week3_TinsaeGhilay/Task 5/src/server/Server.java

@@ -0,0 +1,69 @@
+package server;
+
+import java.rmi.server.UnicastRemoteObject;
+import java.rmi.RemoteException;
+import java.util.*;
+import java.rmi.registry.LocateRegistry;
+import java.rmi.registry.Registry;
+// import interfaces
+import common.ClientInterface;
+import common.ServerInterface;
+
+public class Server extends UnicastRemoteObject implements ServerInterface {
+    private Map<String, ClientInterface> onlineClients = new HashMap<>();
+    private Map<String, List<String>> offlineMessages = new HashMap<>();
+    private Map<String, Set<String>> blockedClients = new HashMap<>();
+
+    protected Server() throws RemoteException {
+        super();
+    }
+
+    @Override
+    public synchronized void registerClient(String clientId, ClientInterface client) throws RemoteException {
+        onlineClients.put(clientId, client);
+        blockedClients.putIfAbsent(clientId, new HashSet<>());
+
+        // Send any offline messages
+        List<String> messages = offlineMessages.getOrDefault(clientId, new ArrayList<>());
+        for (String msg : messages) {
+            client.receiveMessage("Offline", msg);
+        }
+        offlineMessages.remove(clientId);
+    }
+
+    @Override
+    public synchronized void sendMessage(String fromId, String toId, String message) throws RemoteException {
+        // Check if recipient blocked sender
+        Set<String> blocked = blockedClients.getOrDefault(toId, Collections.emptySet());
+        if (blocked.contains(fromId))
+            return;
+
+        ClientInterface recipient = onlineClients.get(toId);
+        if (recipient != null) {
+            recipient.receiveMessage(fromId, message);
+        } else {
+            // Store message for offline delivery
+            offlineMessages.putIfAbsent(toId, new ArrayList<>());
+            offlineMessages.get(toId).add(fromId + ": " + message);
+        }
+    }
+
+    @Override
+    public synchronized void blockClient(String clientId, String blockedId) throws RemoteException {
+        blockedClients.putIfAbsent(clientId, new HashSet<>());
+        blockedClients.get(clientId).add(blockedId);
+    }
+
+    @Override
+    public synchronized List<String> getOfflineMessages(String clientId) throws RemoteException {
+        return offlineMessages.getOrDefault(clientId, Collections.emptyList());
+    }
+
+    // entry point
+    public static void main(String[] args) throws Exception {
+        Server server = new Server();
+        Registry registry = LocateRegistry.createRegistry(1099);
+        registry.rebind("ChatServer", server);
+        System.out.println("Chat server running...");
+    }
+}