can't store sockets in fields because Pinger instances are reused between threads - ThreadResourceBinder introduced instead

src/net/azib/ipscan/core/net/TCPPinger.java

@@ -6,6 +6,7 @@
 package net.azib.ipscan.core.net;
 
 import net.azib.ipscan.core.ScanningSubject;
+import net.azib.ipscan.util.ThreadResourceBinder;
 
 import java.io.IOException;
 import java.net.InetSocketAddress;
@@ -15,7 +16,6 @@ import java.net.SocketTimeoutException;
 import java.util.logging.Logger;
 
 import static java.util.logging.Level.*;
-import static net.azib.ipscan.util.IOUtils.*;
 
 /**
  * TCP Pinger. Uses a TCP port to ping, doesn't require root privileges.
@@ -28,7 +28,7 @@ public class TCPPinger implements Pinger {
 	// try different ports in sequence, starting with 80 (which is most probably not filtered)
 	private static final int[] PROBE_TCP_PORTS = {80, 80, 443, 8080, 22, 7};
 
-  private Socket socket;
+  private ThreadResourceBinder<Socket> sockets = new ThreadResourceBinder<Socket>();
   private int timeout;
 
   public TCPPinger(int timeout) {
@@ -39,9 +39,10 @@ public class TCPPinger implements Pinger {
 	public PingResult ping(ScanningSubject subject, int count) throws IOException {
 		PingResult result = new PingResult(subject.getAddress());
 		int workingPort = -1;
-		
+
+    Socket socket;
 		for (int i = 0; i < count && !Thread.currentThread().isInterrupted(); i++) {
-      socket = new Socket();
+      socket = sockets.bind(new Socket());
 			long startTime = System.currentTimeMillis();
 			try {
 				// cycle through different ports until a working one is found
@@ -78,7 +79,7 @@ public class TCPPinger implements Pinger {
 				}
 				else
 				// this should result in NoRouteToHostException or ConnectException, but not all Java implementation respect that
-				if (msg.contains(/*No*/"route to host") || msg.contains(/*Host is*/"down") || msg.contains(/*Network*/"unreachable")) {
+				if (msg.contains(/*No*/"route to host") || msg.contains(/*Host is*/"down") || msg.contains(/*Network*/"unreachable") || msg.contains(/*Socket*/"closed")) {
 					// host is down
 					break;
 				}
@@ -88,7 +89,7 @@ public class TCPPinger implements Pinger {
 				}
 			}
 			finally {
-        closeQuietly(socket);
+        sockets.closeAndUnbind(socket);
 			}
 		}
 		
@@ -102,6 +103,6 @@ public class TCPPinger implements Pinger {
 	}
 
 	public void close() throws IOException {
-    closeQuietly(socket);
+    sockets.close();
 	}
 }

src/net/azib/ipscan/core/net/UDPPinger.java

@@ -6,13 +6,13 @@
 package net.azib.ipscan.core.net;
 
 import net.azib.ipscan.core.ScanningSubject;
+import net.azib.ipscan.util.ThreadResourceBinder;
 
 import java.io.IOException;
 import java.net.*;
 import java.util.logging.Logger;
 
 import static java.util.logging.Level.*;
-import static net.azib.ipscan.util.IOUtils.*;
 
 /**
  * UDP Pinger. Uses an UDP port to ping, doesn't require root privileges.
@@ -24,8 +24,8 @@ public class UDPPinger implements Pinger {
 	
 	private static final int PROBE_UDP_PORT = 33381;
 
-  private DatagramSocket socket;
   private int timeout;
+  private ThreadResourceBinder<DatagramSocket> sockets = new ThreadResourceBinder<DatagramSocket>();
 
   public UDPPinger(int timeout) {
 		this.timeout = timeout;
@@ -34,7 +34,7 @@ public class UDPPinger implements Pinger {
 	public PingResult ping(ScanningSubject subject, int count) throws IOException {
 		PingResult result = new PingResult(subject.getAddress());
 
-    socket = new DatagramSocket();
+    DatagramSocket socket = sockets.bind(new DatagramSocket());
 		socket.setSoTimeout(timeout);
 		socket.connect(subject.getAddress(), PROBE_UDP_PORT);
 		
@@ -68,6 +68,6 @@ public class UDPPinger implements Pinger {
 	}
 
 	public void close() throws IOException {
-    closeQuietly(socket);
+    sockets.close();
   }
 }

src/net/azib/ipscan/util/ThreadResourceBinder.java

@@ -0,0 +1,34 @@
+package net.azib.ipscan.util;
+
+import java.io.Closeable;
+import java.net.DatagramSocket;
+import java.net.Socket;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+import static net.azib.ipscan.util.IOUtils.*;
+
+public class ThreadResourceBinder<T> {
+  private Map<Long, T> resources = new ConcurrentHashMap<Long, T>(256);
+
+  public T bind(T resource) {
+    resources.put(Thread.currentThread().getId(), resource);
+    return resource;
+  }
+
+  public void close() {
+    for (T resource : resources.values()) close(resource);
+    resources.clear();
+  }
+
+  private void close(T resource) {
+    if (resource instanceof DatagramSocket) closeQuietly((DatagramSocket) resource);
+    else if (resource instanceof Socket) closeQuietly((Socket) resource);
+    else if (resource instanceof Closeable) closeQuietly((Closeable) resource);
+  }
+
+  public void closeAndUnbind(T resource) {
+    close(resource);
+    resources.remove(Thread.currentThread().getId());
+  }
+}