Send the correct kick packet to the client in order to show the reason

src/main/java/com/github/games647/fastlogin/FastLogin.java

@@ -149,7 +149,7 @@ public class FastLogin extends JavaPlugin {
         }
 
         if (authPluginHook == null) {
-            //run this check for exceptions and not found plugins
+            //run this check for exceptions (errors) and not found plugins
             getLogger().warning("No support offline Auth plugin found. ");
             getLogger().warning("Disabling this plugin...");
 

src/main/java/com/github/games647/fastlogin/listener/EncryptionPacketListener.java

@@ -7,6 +7,7 @@ import com.comphenix.protocol.events.PacketContainer;
 import com.comphenix.protocol.events.PacketEvent;
 import com.comphenix.protocol.injector.server.TemporaryPlayerFactory;
 import com.comphenix.protocol.reflect.FuzzyReflection;
+import com.comphenix.protocol.wrappers.WrappedChatComponent;
 import com.comphenix.protocol.wrappers.WrappedGameProfile;
 import com.github.games647.fastlogin.Encryption;
 import com.github.games647.fastlogin.FastLogin;
@@ -137,14 +138,29 @@ public class EncryptionPacketListener extends PacketAdapter {
         packetEvent.setCancelled(true);
     }
 
-    private void disconnect(PacketEvent packetEvent, String kickMessage, Level logLevel, String logMessage
+    private void disconnect(PacketEvent packetEvent, String kickReason, Level logLevel, String logMessage
             , Object... arguments) {
         plugin.getLogger().log(logLevel, logMessage, arguments);
-        packetEvent.getPlayer().kickPlayer(kickMessage);
+        kickPlayer(packetEvent.getPlayer(), kickReason);
         //cancel the event in order to prevent the server receiving an invalid packet
         packetEvent.setCancelled(true);
     }
 
+    private void kickPlayer(Player player, String reason) {
+        PacketContainer kickPacket = protocolManager.createPacket(PacketType.Login.Server.DISCONNECT);
+        kickPacket.getChatComponents().write(0, WrappedChatComponent.fromText(reason));
+
+        try {
+            //send kick packet at login state
+            //the normal event.getPlayer.kickPlayer(String) method does only work at play state
+            protocolManager.sendServerPacket(player, kickPacket);
+            //tell the server that we want to close the connection
+            player.kickPlayer("Disconnect");
+        } catch (InvocationTargetException ex) {
+            plugin.getLogger().log(Level.SEVERE, "Error sending kickpacket", ex);
+        }
+    }
+
     private Object getNetworkManager(Player player)
             throws SecurityException, IllegalAccessException, NoSuchFieldException {
         Object injector = TemporaryPlayerFactory.getInjectorFromPlayer(player);
@@ -178,8 +194,8 @@ public class EncryptionPacketListener extends PacketAdapter {
             //catch not only ioexceptions also parse and NPE on unexpected json format
             plugin.getLogger().log(Level.WARNING, "Failed to verify if session is valid", ex);
         }
-        //this connection doesn't need to be closed. So can make use of keep alive in java
 
+        //this connection doesn't need to be closed. So can make use of keep alive in java
         return false;
     }
 
@@ -191,11 +207,12 @@ public class EncryptionPacketListener extends PacketAdapter {
         WrappedGameProfile fakeProfile = WrappedGameProfile.fromOfflinePlayer(Bukkit.getOfflinePlayer(username));
         startPacket.getGameProfiles().write(0, fakeProfile);
         try {
+            //we don't want to handle our own packets so ignore filters
             protocolManager.recieveClientPacket(from, startPacket, false);
         } catch (InvocationTargetException | IllegalAccessException ex) {
             plugin.getLogger().log(Level.WARNING, "Failed to fake a new start packet", ex);
             //cancel the event in order to prevent the server receiving an invalid packet
-            from.kickPlayer("Error occurred");
+            kickPlayer(from, "Error occured");
         }
     }
 }

src/main/java/com/github/games647/fastlogin/listener/PlayerListener.java

@@ -32,11 +32,13 @@ public class PlayerListener implements Listener {
         //check if it's the same player as we checked before
         if (session != null && session.getUsername().equals(player.getName())
                 && session.isVerified()) {
+//java 8
 //            Bukkit.getScheduler().runTaskLater(plugin, () -> {
 //                if (player.isOnline()) {
 //                    plugin.getLogger().log(Level.FINER, "Logging player {0} in", player.getName());
 //                    authPlugin.forceLogin(player);
 //                }
+            //java 7+
             Bukkit.getScheduler().runTaskLater(plugin, new Runnable() {
 
                 @Override
@@ -47,7 +49,7 @@ public class PlayerListener implements Listener {
                     }
                 }
                 //Wait before auth plugin initializes the player
-            }, 1 * 20L);
+            }, 2 * 20L);
         }
     }
 }

src/main/java/com/github/games647/fastlogin/listener/StartPacketListener.java

@@ -75,7 +75,7 @@ public class StartPacketListener extends PacketAdapter {
         plugin.getLogger().log(Level.FINER, "Player {0} with {1} connecting to the server"
                 , new Object[]{sessionKey, username});
         //do premium login process
-        if (isPremium(username)) {
+        if (plugin.getEnabledPremium().contains(username) && isPremium(username)) {
             //minecraft server implementation
             //https://github.com/bergerkiller/CraftSource/blob/master/net.minecraft.server/LoginListener.java#L161
             sentEncryptionRequest(sessionKey, username, player, packetEvent);
@@ -84,7 +84,7 @@ public class StartPacketListener extends PacketAdapter {
 
     private boolean isPremium(String playerName) {
         //check if it's a valid playername and the user activated fast logins
-        if (playernameMatcher.matcher(playerName).matches() && plugin.getEnabledPremium().contains(playerName)) {
+        if (playernameMatcher.matcher(playerName).matches()) {
             //only make a API call if the name is valid existing mojang account
             try {
                 HttpURLConnection connection = plugin.getConnection(UUID_LINK + playerName);
@@ -119,7 +119,7 @@ public class StartPacketListener extends PacketAdapter {
             random.nextBytes(verifyToken);
             newPacket.getByteArrays().write(0, verifyToken);
 
-            protocolManager.sendServerPacket(player, newPacket, false);
+            protocolManager.sendServerPacket(player, newPacket);
 
             //cancel only if the player has a paid account otherwise login as normal offline player
             packetEvent.setCancelled(true);