Add Discovery service.

DiscoveryService listens to UDP broadcasts.

2 files changed, 158 insertions, 0 deletions

diff --git a/same-android/src/main/java/com/orbekk/discovery/Broadcast.java b/same-android/src/main/java/com/orbekk/discovery/Broadcast.java
new file mode 100644
index 0000000..5f592db
--- /dev/null
+++ b/same-android/src/main/java/com/orbekk/discovery/Broadcast.java
@@ -0,0 +1,82 @@
+package com.orbekk.discovery;
+
+import java.io.IOException;
+import java.net.DatagramPacket;
+import java.net.DatagramSocket;
+import java.net.InetAddress;
+import java.net.SocketException;
+import java.net.UnknownHostException;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import android.content.Context;
+import android.net.DhcpInfo;
+import android.net.wifi.WifiManager;
+
+public class Broadcast {
+    private Context context;
+    private Logger logger = LoggerFactory.getLogger(getClass());
+    private DatagramSocket socket = null;
+    
+    public Broadcast(Context context) {
+        this.context = context;
+    }
+    
+    public synchronized InetAddress getBroadcastAddress() {
+        WifiManager wifi = (WifiManager)context.getSystemService(Context.WIFI_SERVICE);
+        DhcpInfo dhcp = wifi.getDhcpInfo();
+
+        int broadcast = (dhcp.ipAddress & dhcp.netmask) | ~dhcp.netmask;
+        byte[] quads = new byte[4];
+        for (int k = 0; k < 4; k++)
+          quads[k] = (byte) ((broadcast >> k * 8) & 0xFF);
+        try {
+            return InetAddress.getByAddress(quads);
+        } catch (UnknownHostException e) {
+            logger.warn("Failed to find broadcast address.");
+            return null;
+        }
+    }
+    
+    public synchronized boolean sendBroadcast(byte[] data, int port) {
+        try {
+            socket = new DatagramSocket(port);
+            socket.setBroadcast(true);
+            DatagramPacket packet = new DatagramPacket(data, data.length, getBroadcastAddress(), port);
+            socket.send(packet);
+            return true;
+        } catch (SocketException e) {
+            logger.warn("Failed to send broadcast.", e.fillInStackTrace());
+            return false;
+        } catch (IOException e) {
+            logger.warn("Error when sending broadcast.", e.fillInStackTrace());
+            return false;
+        } finally {
+            socket.close();
+            socket = null;
+        }
+    }
+    
+    public synchronized DatagramPacket receiveBroadcast(int port) {
+        try {
+            socket = new DatagramSocket(port);
+            byte[] data = new byte[1024];
+            DatagramPacket packet = new DatagramPacket(data, data.length);
+            socket.receive(packet);
+            return packet;
+        } catch (IOException e) {
+            logger.warn("Failed to receive broadcast.", e);
+            return null;
+        } finally {
+            socket.close();
+            socket = null;
+        }
+    }
+    
+    public void interrupt() {
+        if (socket != null) {
+            socket.close();
+        }
+    }
+}
\ No newline at end of file
diff --git a/same-android/src/main/java/com/orbekk/discovery/DiscoveryService.java b/same-android/src/main/java/com/orbekk/discovery/DiscoveryService.java
new file mode 100644
index 0000000..e9aac5f
--- /dev/null
+++ b/same-android/src/main/java/com/orbekk/discovery/DiscoveryService.java
@@ -0,0 +1,76 @@
+package com.orbekk.discovery;
+
+import java.net.DatagramPacket;
+
+import android.app.Service;
+import android.content.Intent;
+import android.os.Handler;
+import android.os.IBinder;
+import android.os.Message;
+import android.widget.Toast;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class DiscoveryService extends Service {
+    private Logger logger = LoggerFactory.getLogger(getClass());
+    private Thread thread = null;
+    
+    public final class DiscoveryThread extends Thread {
+        Broadcast broadcast;
+        
+        public DiscoveryThread() {
+            broadcast = new Broadcast(DiscoveryService.this);
+        }
+        
+        @Override public void run() {
+            while (!Thread.interrupted()) {
+                byte[] data = new byte[1024];
+                DatagramPacket packet = broadcast.receiveBroadcast(15066);
+                String content = new String(packet.getData(), 0, packet.getLength());
+                Message message = Message.obtain();
+                message.obj = content;
+                toastHandler.sendMessage(message);
+            }
+        }
+        
+        @Override public void interrupt() {
+            super.interrupt();
+            broadcast.interrupt();
+        }
+    }
+    
+    private Handler toastHandler = new Handler() {
+        @Override public void handleMessage(Message message) {
+            Toast.makeText(DiscoveryService.this,
+                    (String)message.obj, Toast.LENGTH_SHORT)
+                            .show();
+            logger.info("Display toast: {}", (String)message.obj);
+        }
+    };
+    
+    @Override
+    public IBinder onBind(Intent intent) {
+        return null;
+    }
+    
+    @Override
+    public int onStartCommand(Intent intent, int flags, int startId) {
+        Toast.makeText(this, "service start: " + intent.getAction(),
+                Toast.LENGTH_SHORT).show();
+        if (thread == null) {
+            synchronized (this) {
+                thread = new DiscoveryThread();
+                thread.start();
+            }
+        }
+        return START_STICKY;
+    }
+    
+    @Override
+    public void onDestroy() {
+        Toast.makeText(this, "service stopped", Toast.LENGTH_SHORT).show();
+        thread.interrupt();
+    }
+
+}