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how to do ssl socket programming
I am doing communication from android as client and laptop as server through Socket using wireless router.But how if i want to do communication securely. here is my android code in eclipse
public class TCPClient implements Runnable {
public void run() {
try {
InetAddress serverAddr = InetAddress.getByName("192.168.1.2");
Log.d("TCP", "C: Connecting...");
Socket socket = new Socket(serverAddr,12345);
String message = "Hello from Client android emulator";
try {
Log.d("TCP", "C: Sending: '" + message + "'");
PrintWriter out = new PrintWriter( new BufferedWriter( new OutputStreamWriter(socket.getOutputStream())),true);
out.println(message);
Log.d("TCP", "C: Sent.");
Log.d("TCP", "C: Done.");
} catch(Exception e) {
Log.e("TCP", "S: Error", e);
} finally {
socket.close();
}
} catch (Exception e) {
Log.e("TCP", "C: Error", e);
}
}
}
here is server code in Netbean that is working and communicating with android. what changes i have to do ?
public class TCPDesktopServer implements Runnable{
public static final String SERVERIP = "10.0.2.15";
public static final int SERVERPORT = 12345;
public void run() {
try {
System.out.println("S: Connecting...");
ServerSocket serverSocket = new ServerSocket(SERVERPORT);
while (true) {
Socket client = serverSocket.accept();
System.out.println("S: Receiving...");
try {
BufferedReader in = new BufferedReader(new InputStreamReader(client.getInputStream()));
String str = in.readLine();
System.out.println("S: Received: '" + str + "'");
} catch(Exception e) {
System.out.println("S: Error");
e.printStackTrace();
} finally {
client.close();
System.out.println("S: Done.");
}
}
} catch (Exception e) {
System.out.println("S: Error");
e.printStackTrace();
}
}
public static void main (String a[]) {
Thread desktopServerThread = new Thread(new TCPDesktopServer());
desktopServerThread.start();
}
}
Seems like you need to use javax.crypto.CipherOutputStream/CipherInputStream, or if you want a more standardized approach you could try Apache commons (http://commons.apache.org/) where there is a basic implementation of SSL.
You could very easily use the SSLSocket class which is part of the base java distribution. If you are having problems getting certificates to validate, you can user this tutorial to show you how to allow self-signed certs and non-matching host names.
Related
I made a Chat Application (Server/Client) using Java. Note: The server is ran as its own jar file and each client is ran as its own jar file.
Each client is on their own thread.
Whenever I send messages to the server, each client receives the message, however when I send messages from the client, only the server receives the message. When the client sends a message, I want all connected clients and the server to receive the message so all of the clients can communicate together and with the server as well.
I've looked at multiple posts and videos about this, but most were too confusing for me to understand.
Could someone please help me understand how I can send messages between threads? Thanks!
-- My Code --
Client:
public Client(User user, String address, int port) {
try {
socket = new Socket(address, port);
ClientApplicationUI app = new ClientApplicationUI();
app.setTitle("Chat Application - " + user.getUsername());
app.setVisible(true);
ServerConnection connection = new ServerConnection(socket, app);
output = new DataOutputStream(new BufferedOutputStream(socket.getOutputStream()));
new Thread(connection).start();
app.getButton().addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if (app.getTextField().getText() != null && app.getTextField().getText().length() > 0) {
String message = MessageUtil.getMessage(Message.LOGGER_PREFIX) + " <" + user.getUsername() + "> " + app.getTextField().getText() + "\n";
try {
output.writeUTF(message);
output.flush();
} catch (IOException e1) {
e1.printStackTrace();
}
}
}
});
} catch (UnknownHostException e) {
System.out.println(e);
System.out.println("Could not connect! Reason: " + e);
} catch (IOException e) {
System.out.println("Could not connect! Reason: " + e);
}
}
ServerConnection
public class ServerConnection implements Runnable {
#SuppressWarnings("unused")
private Socket socket;
private DataInputStream in;
private ClientApplicationUI app;
public ServerConnection(Socket socket, ClientApplicationUI app) throws IOException {
this.socket = socket;
this.app = app;
in = new DataInputStream(new BufferedInputStream(socket.getInputStream()));
}
#Override
public void run() {
while (true) {
String message;
try {
message = in.readUTF();
app.logMessage(message);
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
Server
public class Server {
private Socket socket = null;
private ServerSocket server = null;
private ExecutorService pool = Executors.newFixedThreadPool(4);
public Server (int port) {
try {
ApplicationUI app = new ApplicationUI();
app.setVisible(true);
server = new ServerSocket(port);
app.logMessage(MessageUtil.getMessage(Message.LOGGER_PREFIX) + " " + MessageUtil.getMessage(Message.INFO) + " Server started!\n");
app.logMessage(MessageUtil.getMessage(Message.LOGGER_PREFIX) + " " + MessageUtil.getMessage(Message.INFO) + " Waiting for new connections...\n");
while (true) {
socket = server.accept();
ConnectionHandler clientThread = new ConnectionHandler(socket, app);
app.logMessage(MessageUtil.getMessage(Message.LOGGER_PREFIX) + " " + MessageUtil.getMessage(Message.INFO) + " A new client has been accepted!\n");
pool.execute(clientThread);
}
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
Server server = new Server(58139);
}
}
ConnectionHandler
public class ConnectionHandler implements Runnable {
private Socket client;
private ApplicationUI app;
private DataInputStream in;
private DataOutputStream out;
public ConnectionHandler(Socket client, ApplicationUI app) throws IOException {
this.client = client;
this.app = app;
in = new DataInputStream(new BufferedInputStream(client.getInputStream()));
out = new DataOutputStream(new BufferedOutputStream(client.getOutputStream()));
}
#Override
public void run() {
try {
app.getButton().addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if (app.getTextField().getText() != null && app.getTextField().getText().length() > 0) {
String message = MessageUtil.getMessage(Message.LOGGER_PREFIX) + " <Server> " + app.getTextField().getText() + "\n";
try {
sendMessage(message);
} catch (IOException e1) {
e1.printStackTrace();
}
}
}
});
String message = "";
while (!message.equals("/stop")) {
message = in.readUTF();
app.logMessage(message);
}
} catch (IOException e) {
System.err.println("IO exception in connection handler!");
System.err.println(e.getStackTrace());
} finally {
try {
out.close();
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
private void sendMessage(String message) throws IOException {
out.writeUTF(message);
out.flush();
}
}
You need to understand, how sockets work. They are always Client and Server.
There are two ways you could achieve what you want:
First solution:
Send the message which is meant for all clients to the server and let the server distribute the message to all the other clients. The server will need to keep track of the already connected clients, i.e. store their Socket.
Second solution: (which totally is not advisable)
If you want to send a message to a client of a network without haveing the actual server involved, you will need that client to act as a server, or the other way around. This means that every client will actually need to listen to every other client, instead of only the server.
You should definitely go with the first solution!
Is it possible to write a client-server code that can connect 2-different computers to play a multi-player game using sockets in java? Do these computers need to be connected by a cable? Or can I send the data through some other source? (Like internet..) Or is it enough if I know just the ip addresses of both computers and put that in in the sockets? Please tell me how I can do it.
You can connect computers that are on the same Wifi network. You will need to open a server and then open clients that connect to it.
The following code may help:
Server.java
ArrayList<Socket> clientSockets = new ArrayList<>();
try {
ServerSocket serverSocket = new ServerSocket(port); // port same as client
InetAddress inetAddress = InetAddress.getLocalHost();
System.out.println("Server opened at: "+inetAddress.getHostAddress());
while (true) // this keeps the server listening
{
final Socket socket = serverSocket.accept(); // this accepts incomming connections
clientSockets.add(socket); // adds current connection to an arraylist
System.out.println(timestamp()+"Connection from "+socket.getInetAddress());
Thread t = new Thread(new Runnable() // Thread handles messages sent by client that just connected
{
#Override
public void run() {
try
{
while (socket.isConnected())
{
BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
String fromClient = br.readLine();
if (fromClient != null)
{
//use message from client
}
else // connection might have been reset by client
{
socket.close();
clientSockets.remove(socket);
}
}
} catch (SocketException e)
{
System.out.println("Disconnection from "+socket.getInetAddress());
} catch (IOException e) {}
}
});
t.start();
}
} catch (Exception e) {}
Client.java - add two buttons, one for connecting and one for sending
bConnect.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
try {
InetAddress address = InetAddress.getByName(host); // host IPaddress
socket = new Socket(address, port); // port same as server
bw = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
final Timer time = new Timer(); // to get new server txt if it changes
TimerTask t = new TimerTask() {
#Override
public void run() {
try {
BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
String kry = br.readLine();
// use message from server
} catch (Exception e1) {
JOptionPane.showMessageDialog(null, "The Server has just gone offline");
}
}
};
time.scheduleAtFixedRate(t, 0, 2000);
}
catch (Exception e1)
{e1.printStackTrace();
JOptionPane.showMessageDialog(null, "The Server is not online");}
}
});
bSend.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
String textGekry = "what you are sending";
if (!textGekry.equals(""))
{
String sendMessage = textGekry + "\n";
try
{
bw.write(sendMessage);
bw.flush();
}
catch (Exception e1)
{
JOptionPane.showMessageDialog(null,"The Server is most likely offline");
}
}
}
});
This may be a stupid question, but here goes.
Im writing this chat program, where there is a server, and clients that can connect to it. I want to implement private messaging into the program, but I don't know how to get the clients to directly connect to eachother. For the server, I used a ServerSocket, which runs on a single port. To get that to work, I needed to forward a port to the server. Is there a way to get the clients to wait for connections, without forwarding a port to them?
Thanks
The whole point of TCP/IP is that a single client connects to a predefined port on a server. So yes, you'll also need to have a ServerSocket on the client that's going to accept the direct connection. You'll almost always run into trouble with port forwarding and the like, which is why UPnP was invented one day.
What you are trying to do is 'peer to peer' connectivity, aka P2P, which is always, by its very definition, plagued by firewalling problems. As such it's usually, especially for a chat, easier to use the central server as 'switchboard' server and relay the private messages as well.
I've written not long time ago a template for multiple client - server application, that might help you to solve your problem. The rest of your question was already answerd by #Niels, I think ;)
import java.net.*;
import java.io.*;
class ServeConnection extends Thread {
private Socket socket = null;
private BufferedReader in = null;
private PrintWriter out = null;
public ServeConnection(Socket s) throws IOException {
// init connection with client
socket = s;
try {
in = new BufferedReader(new InputStreamReader(
this.socket.getInputStream()));
out = new PrintWriter(this.socket.getOutputStream(), true);
} catch (IOException e) {
System.err.println("Couldn't get I/O.");
System.exit(1);
}
start();
}
public void run() {
System.out.println("client accepted from: " + socket.getInetAddress()
+ ":" + socket.getPort());
// get commands from client, until is he communicating or until no error
// occurs
String inputLine, outputLine;
try {
while ((inputLine = in.readLine()) != null) {
System.out.println("request: " + inputLine);
outputLine = inputLine;
out.println("I've recived "+outputLine);
} catch (IOException e) {
e.printStackTrace();
}
System.out.println("server ending");
out.close();
try {
in.close();
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
class Server {
public static void svr_main(int port) throws IOException {
ServerSocket serverSocket = null;
try {
serverSocket = new ServerSocket(port);
} catch (IOException e) {
System.err.println("Could not listen on port: " + port);
System.exit(1);
}
System.out.println("Server ready");
try {
while (true) {
Socket socket = serverSocket.accept();
try {
new ServeConnection(socket);
} catch (IOException e) {
System.err.println("IO Exception");
}
}
} finally {
serverSocket.close();
}
}
}
class Client {
static Socket echoSocket = null;
static PrintWriter out = null;
static BufferedReader in = null;
public static void cli_main(int port, String servername) throws
IOException {
try {
echoSocket = new Socket(servername, port);
out = new PrintWriter(echoSocket.getOutputStream(), true);
in = new BufferedReader(new InputStreamReader(
echoSocket.getInputStream()));
} catch (UnknownHostException e) {
System.err.println("Don't know about host: " + servername);
System.exit(1);
} catch (IOException e) {
System.err.println("Couldn't get I/O for " + servername);
System.exit(1);
}
System.out.println("Client ready!");
while (true) {
inputLine = (in.readLine().toString());
if (inputLine == null) {
System.out.println("Client closing!");
break;
}
// get the input and tokenize it
String[] tokens = inputLine.split(" ");
}
out.close();
in.close();
echoSocket.close();
System.out.println("Client closing");
}
}
public class MyClientServerSnippet{
public static void main(String[] args) throws IOException {
if (args.length == 0) {
System.err.println("Client: java snippet.MyClientServerSnippet<hostname> <port>");
System.err.println("Server: java snippet.MyClientServerSnippet<port>");
System.exit(1);
}
else if (args.length > 1) {
System.out.println("Starting client...\n");
Client client = new Client();
client.cli_main(3049, "127.0.0.1");
} else {
System.out.println("Starting server...\n");
Server server = new Server();
server.svr_main(3049);
}
}
}
I am new to java TCP socket. I tried to implement a server and a client. So the server should check input (do something) and send string to client. The client should send string to the server and look for an input string from the server (and do something). Both should loop checking and sending all the time if something new is available.
The client can send data to the server, the server receives it an can display/process this data.
But the data from the server isn't displayed by the client. Can someone tell me why the client isn't receiving the string from the server? Any better ideas to do endless loop? There will be only one client and one server.
while true:
server out------> send String-----> in client
in<----- sent String <------ out
this is the simplified server part:
public class MainActivity extends Activity {
Socket client;
ServerSocket server;
int serverport = 54321;
String inputData = null;
BufferedReader in;
PrintWriter out;
String outputData;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
new Thread(setupConnection).start();
}
private Runnable setupConnection = new Thread() {
public void run() {
try {
server = new ServerSocket(serverport);
while (true) {
client = server.accept();
in = new BufferedReader(new InputStreamReader(client.getInputStream()));
out = new PrintWriter(client.getOutputStream(), true);
inputData = in.readLine();
InputStream inStream = new ByteArrayInputStream(inputData.getBytes());
in.close();
if (inputData != null) {
System.out.println(TAG + "-----Incoming Message---- " + inputData);
//this is working String is shown
} }
out.write("nothing to do?");
out.flush();
out.close();
}
} catch (SocketException e) {
Log.v(TAG, "SocketException: " + e);
e.printStackTrace();
} catch (IOException e) {
Log.v(TAG, "IOException: " + e);
e.printStackTrace();
}
}
the simplified client looks like this:
public class testClass {
public static void main(String[] args) throws IOException, InterruptedException {
Socket socket = null;
String host = "127.0.0.1";
int port = 54321;
PrintWriter out = null;
BufferedReader in = null;
while (true) {
try {
socket = new Socket(host, port);
out = new PrintWriter(socket.getOutputStream(), true);
in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
} catch (UnknownHostException e) {
System.out.println(TAG + "Error: " + e);
System.err.println("Don't know about host: localhost.");
System.exit(1);
} catch (IOException e) {
System.out.println(TAG + "Error: " + e);
System.err.println("Couldn't get I/O for " + "the connection to: localhost.");
System.exit(1);
}
out.println("Hello, is it me you're looking for...");
out.flush();
String input = in.readLine();
System.out.println("Input: " + input);
in.close();
out.close();
}
}
}
If readLine() returns null,the peer has closed the connection, and you must do likewise. And stop reading.
if you want implement this code in android , you faces many problems:
you can find the solution in this link:
Post JSON in android
in the following code may be fix this problem:
HttpPost post = new HttpPost("http://xxxxxx");
DefaultHttpClient httpClient = new DefaultHttpClient();
post.setEntity(new ByteArrayEntity(json.toString().getBytes()));
HttpResponse response = httpClient.execute(post);
return EntityUtils.toString(response.getEntity());
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
System.out.println(">>>>>>>" + e.getMessage());
} catch (ClientProtocolException e) {
e.printStackTrace();
System.out.println(">>>>>>>" + e.getMessage());
} catch (IOException e) {
e.printStackTrace();
System.out.println(">>>>>>>" + e.getMessage());
}
I have a problem with my Java program. It has a socket connection between a server and many client. Here is the server (the part which concerns the problem):
private static ArrayList<ParallelServer> clientConnected = new ArrayList<ParallelServer>();
public Server(int port) {
this.port = port;
if (!startServer())
JOptionPane.showMessageDialog(new JFrame(""),
"Error!", "ERROR!",
JOptionPane.ERROR_MESSAGE);
}
private boolean startServer() {
try {
server = new ServerSocket(port);
loadDatabase();
} catch (IOException ex) {
ex.printStackTrace();
return false;
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
return true;
}
public void runServer() {
while (true) {
try {
client = server.accept();
ParallelServer pServer = new ParallelServer(client);
clientConnected.add(pServer);
Thread thread = new Thread(pServer);
thread.start();
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
public static void sendBroadcast(String username) throws IOException {
for(int i = 0; i < clientConnected.size(); i++)
clientConnected.get(i).sendAnswer("#change," + username);
}
The parallel server is:
private Socket client;
private InputStreamReader inputstreamreader;
private BufferedReader bufferedreader;
private PrintWriter printwriter;
public ParallelServer(Socket client) {
this.client = client;
}
public void run() {
try {
inputstreamreader = new InputStreamReader(client.getInputStream());
bufferedreader = new BufferedReader(inputstreamreader);
printwriter = new PrintWriter(client.getOutputStream(), true);
String lineread = "";
while (client.isConnected()) {
lineread = bufferedreader.readLine();
doCommand(lineread);
}
} catch (UnknownHostException unhe) {
} catch (InterruptedIOException intioe) {
} catch (IOException ioe) {
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
public void sendAnswer(String answer) throws IOException {
printwriter = new PrintWriter(client.getOutputStream(), true);
printwriter.println(answer);
printwriter.flush();
}
And here is the client:
private String serverurl = "localhost";
private int serverport = 7777;
private PrintWriter printwriter;
private InputStreamReader inputstreamreader;
private BufferedReader bufferedreader;
private Socket server;
public Client() {
server = null;
try {
server = new Socket(serverurl, serverport);
server.setSoTimeout(5000);
} catch (UnknownHostException unhe) {
System.out.println("UnknownHostException: " + unhe.getMessage());
} catch (InterruptedIOException intioe) {
System.out.println("Timeout while attempting to establish socket connection.");
} catch (IOException ioe) {
JOptionPane.showMessageDialog(new JFrame(),"Unable to reach the server!","ERROE!",JOptionPane.ERROR_MESSAGE);
}
}
public String sendCommand(String command) throws IOException {
if(server == null) {
try {
server = new Socket(serverurl, serverport);
server.setSoTimeout(5000);
} catch (UnknownHostException unhe) {
System.out.println("UnknownHostException: " + unhe.getMessage());
} catch (InterruptedIOException intioe) {
System.out.println("Timeout while attempting to establish socket connection.");
} catch (IOException ioe) {
JOptionPane.showMessageDialog(new JFrame(),"Unable to reach the server!","ERROR!",JOptionPane.ERROR_MESSAGE);
}
}
if(server != null) {
printwriter = new PrintWriter(server.getOutputStream(), true);
printwriter.println(command);
printwriter.flush();
inputstreamreader = new InputStreamReader(server.getInputStream());
bufferedreader = new BufferedReader(inputstreamreader);
return bufferedreader.readLine();
}
else
return "#serverProblem";
}
The program is a simple online game with turns. Players' turns are created with a queue and when a player passes his turn, the server send a broadcast message which say "Now it is 'Player 1' turn." (for instance). My problem is that when a client receive the message, its like it add the answer "Now it is 'Player 1' turn." to the next message it will receive. In my case: when a player passes his turn, he sends "#passTurn,username". The ParallelServer class polls it from the queue, puts it at the bottom of the queue, sends the client "#ok" to tell it that the turn has changed successfully and tells the Server class to send the broadcast message. Then, when the same client will try do do a further action, it will consider "Now it is 'Player 1' turn." as the answer the server has given to it. Instead, I would like that the server and the clients work as always and when the broadcast message is cought, the client is notified without any collateral effect.
What can I do?
Thanks.
Your bi-directional message passing mechanism should look something like this:
Server:
Wait on any client InputStream
if (broadcast)
broadcast_message()
else
process_message()
Client:
Receiving Thread:
Wait on server broadcast
Sending Thread:
Wait on messages to be sent to server from the User Input
This should do the trick :)
Hope it helps. Cheers!