From 49a993786c6435cc17780241dd205a2ca1a818a2 Mon Sep 17 00:00:00 2001
From: Simon Rettberg
Date: Tue, 7 Jan 2020 15:34:57 +0100
Subject: Add TCP interface

Supports password protection
---
 .../taskmanager/network/NetworkHandlerUdp.java     | 170 +++++++++++++++++++++
 1 file changed, 170 insertions(+)
 create mode 100644 daemon/src/main/java/org/openslx/taskmanager/network/NetworkHandlerUdp.java

(limited to 'daemon/src/main/java/org/openslx/taskmanager/network/NetworkHandlerUdp.java')

diff --git a/daemon/src/main/java/org/openslx/taskmanager/network/NetworkHandlerUdp.java b/daemon/src/main/java/org/openslx/taskmanager/network/NetworkHandlerUdp.java
new file mode 100644
index 0000000..4c12960
--- /dev/null
+++ b/daemon/src/main/java/org/openslx/taskmanager/network/NetworkHandlerUdp.java
@@ -0,0 +1,170 @@
+package org.openslx.taskmanager.network;
+
+import java.io.IOException;
+import java.net.DatagramPacket;
+import java.net.DatagramSocket;
+import java.net.InetAddress;
+import java.net.SocketAddress;
+import java.net.SocketException;
+import java.nio.charset.StandardCharsets;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.LinkedBlockingQueue;
+
+import org.apache.log4j.Logger;
+import org.openslx.taskmanager.Global;
+
+/**
+ * The network listener that will receive incoming UDP packets, try to process
+ * them, and then send a reply.
+ */
+public class NetworkHandlerUdp extends NetworkHandlerBase
+{
+
+	private static final Logger log = Logger.getLogger( NetworkHandlerUdp.class );
+
+	private Thread sendThread = null;
+	/**
+	 * Sender instance (Runnable handling outgoing packets)
+	 */
+	private final Sender sender;
+	/**
+	 * UDP socket for sending and receiving.
+	 */
+	private final DatagramSocket socket;
+
+	/**
+	 * Initialize the NetworkHandler by starting threads and opening the socket.
+	 */
+	public NetworkHandlerUdp( int port, InetAddress listenAddress, RequestParser parser ) throws SocketException
+	{
+		super(parser);
+		socket = new DatagramSocket( port, listenAddress );
+		log.info( "Listening on UDP:" + port );
+		sendThread = new Thread( sender = new Sender() );
+	}
+
+	public void shutdown()
+	{
+		socket.close();
+	}
+
+	// Class part
+
+	/**
+	 * Prepare and enqueue reply for client request.
+	 * Only ever to be called from the receiving thread. The reply message is crafted
+	 * and then handed over to the sending thread.
+	 * 
+	 * @param destination SocketAddress of the client
+	 * @param messageId The same ID the client used in it's request.
+	 *           It's echoed back to the client to enable request bursts, and has no meaning for the
+	 *           server.
+	 * @param status A TaskStatus instance to be serialized to json and sent to the client.
+	 */
+	private void send( SocketAddress destination, byte[] buffer )
+	{
+		final DatagramPacket packet;
+		try {
+			packet = new DatagramPacket( buffer, buffer.length, destination );
+		} catch ( Exception e ) {
+			log.warn( "Could not construct datagram packet for target " + destination.toString() );
+			e.printStackTrace();
+			return;
+		}
+		sender.send( packet );
+	}
+
+	/**
+	 * Main loop of receiving thread - wait until a packet arrives, then try to handle/decode
+	 */
+	@Override
+	public void run()
+	{
+		byte readBuffer[] = new byte[ 66000 ];
+		try {
+			sendThread.start();
+			while ( !Global.doShutdown ) {
+				DatagramPacket packet = new DatagramPacket( readBuffer, readBuffer.length );
+				try {
+					socket.receive( packet );
+				} catch ( IOException e ) {
+					log.info( "IOException on UDP socket when reading: " + e.getMessage() );
+					Thread.sleep( 100 );
+					continue;
+				}
+				if ( packet.getLength() < 2 ) {
+					log.debug( "Message too short" );
+					continue;
+				}
+				String payload = new String( readBuffer, 0, packet.getLength(), StandardCharsets.UTF_8 );
+				byte[] reply;
+				try {
+					reply = parser.handle( payload );
+				} catch ( Throwable t ) {
+					log.error( "Exception in RequestParser: " + t.toString() );
+					log.error( "Payload was: " + payload );
+					t.printStackTrace();
+					continue;
+				}
+				if ( reply != null )
+					send( packet.getSocketAddress(), reply );
+			}
+		} catch ( InterruptedException e ) {
+			Thread.currentThread().interrupt();
+		} finally {
+			Global.doShutdown = true;
+			sendThread.interrupt();
+			log.info( "UDP receiver finished." );
+		}
+	}
+
+	/**
+	 * Private sending thread.
+	 * Use blocking queue, wait for packet to be added to it, then try to send.
+	 */
+	private class Sender implements Runnable
+	{
+
+		/**
+		 * Queue to stuff outgoing packets into.
+		 */
+		private final BlockingQueue<DatagramPacket> queue = new LinkedBlockingQueue<>( 128 );
+
+		/**
+		 * Wait until something is put into the queue, then send it.
+		 */
+		@Override
+		public void run()
+		{
+			try {
+				while ( !Global.doShutdown ) {
+					final DatagramPacket packet;
+					packet = queue.take();
+					try {
+						socket.send( packet );
+					} catch ( IOException e ) {
+						log.debug( "Could not send UDP packet to " + packet.getAddress().getHostAddress().toString(), e );
+					}
+				}
+			} catch ( InterruptedException e ) {
+				Thread.currentThread().interrupt();
+			} finally {
+				Global.doShutdown = true;
+				log.info( "UDP sender finished." );
+			}
+		}
+
+		/**
+		 * Add something to the outgoing packet queue.
+		 * Called from the receiving thread.
+		 */
+		public void send( DatagramPacket packet )
+		{
+			if ( queue.offer( packet ) )
+				return;
+			log.warn( "Could not add packet to queue: Full" );
+		}
+
+	}
+
+}
-- 
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