Throttle IP connections. Fixes #4

src/me/StevenLawson/BukkitTelnet/SocketListener.java

@@ -1,22 +1,31 @@
 package me.StevenLawson.BukkitTelnet;
 
-import me.StevenLawson.BukkitTelnet.session.ClientSession;
+import java.io.BufferedWriter;
 import java.io.IOException;
+import java.io.OutputStreamWriter;
+import java.net.InetAddress;
 import java.net.ServerSocket;
 import java.net.Socket;
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.Iterator;
 import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import me.StevenLawson.BukkitTelnet.session.ClientSession;
 
 public class SocketListener extends Thread
 {
+    public static long LISTEN_THRESHOLD_MILLIS = 10000;
     private final ServerSocket serverSocket;
     private final List<ClientSession> clientSessions;
+    private final Map<InetAddress, Long> recentIPs;
 
     public SocketListener(ServerSocket serverSocket)
     {
         this.serverSocket = serverSocket;
         this.clientSessions = new ArrayList<ClientSession>();
+        this.recentIPs = new HashMap<InetAddress, Long>();
     }
 
     @Override
@@ -35,6 +44,51 @@ public class SocketListener extends Thread
                 continue;
             }
 
+            // Remove old entries
+            final Iterator<Entry<InetAddress, Long>> it = recentIPs.entrySet().iterator();
+            Entry<InetAddress, Long> entry;
+            while (it.hasNext())
+            {
+                if (it.next().getValue() + LISTEN_THRESHOLD_MILLIS < System.currentTimeMillis())
+                {
+                    it.remove();
+                }
+            }
+
+            final InetAddress addr = clientSocket.getInetAddress();
+            if (addr == null)
+            {
+                return; // Socket is not connected
+            }
+
+            // Connect Threshold
+            if (recentIPs.containsKey(addr))
+            {
+                recentIPs.put(addr, System.currentTimeMillis());
+
+                try
+                {
+                    final BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(clientSocket.getOutputStream()));
+                    writer.write("Connection throttled. Please wait a minute and try again.\r\n");
+                    writer.flush();
+                }
+                catch (IOException ignored)
+                {
+                }
+
+                try
+                {
+                    clientSocket.close();
+                }
+                catch (IOException ignored)
+                {
+                }
+
+                continue;
+            }
+
+            recentIPs.put(addr, System.currentTimeMillis());
+
             final ClientSession clientSession = new ClientSession(clientSocket);
             clientSessions.add(clientSession);
             clientSession.start();