Use synchronous calls and wait for chat disconnect. Fixes BUKKIT-2946

When invalid chat is detected we currently drop the connection with no
hint as to why as anything else is not allowed while we're off the main
thread. To give valid disconnect reasons and fire proper events instead
pass these off to the main thread and wait for it to process them.

src/main/java/net/minecraft/server/NetServerHandler.java

@@ -10,6 +10,7 @@ import java.util.logging.Logger;
 
 // CraftBukkit start
 import java.io.UnsupportedEncodingException;
+import java.util.concurrent.ExecutionException;
 import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
 import java.util.logging.Level;
 import java.util.HashSet;
@@ -792,13 +793,49 @@ public class NetServerHandler extends NetHandler {
             String s = packet3chat.message;
 
             if (s.length() > 100) {
-                this.networkManager.a("Chat message too long"); // CraftBukkit disconnect client asynchronously
+                // CraftBukkit start
+                Waitable waitable = new Waitable() {
+                    @Override
+                    protected Object evaluate() {
+                        NetServerHandler.this.disconnect("Chat message too long");
+                        return null;
+                    }
+                };
+
+                this.minecraftServer.processQueue.add(waitable);
+
+                try {
+                    waitable.get();
+                } catch (InterruptedException e) {
+                    Thread.currentThread().interrupt();
+                } catch (ExecutionException e) {
+                    throw new RuntimeException(e);
+                }
+                // CraftBukkit end
             } else {
                 s = s.trim();
 
                 for (int i = 0; i < s.length(); ++i) {
                     if (!SharedConstants.isAllowedChatCharacter(s.charAt(i))) {
-                        this.networkManager.a("Illegal characters in chat"); // CraftBukkit disconnect client asynchronously
+                        // CraftBukkit start
+                        Waitable waitable = new Waitable() {
+                            @Override
+                            protected Object evaluate() {
+                                NetServerHandler.this.disconnect("Illegal characters in chat");
+                                return null;
+                            }
+                        };
+
+                        this.minecraftServer.processQueue.add(waitable);
+
+                        try {
+                            waitable.get();
+                        } catch (InterruptedException e) {
+                            Thread.currentThread().interrupt();
+                        } catch (ExecutionException e) {
+                            throw new RuntimeException(e);
+                        }
+                        // CraftBukkit end
                         return;
                     }
                 }
@@ -813,7 +850,25 @@ public class NetServerHandler extends NetHandler {
 
                 // This section stays because it is only applicable to packets
                 if (chatSpamField.addAndGet(this, 20) > 200 && !this.minecraftServer.getServerConfigurationManager().isOp(this.player.name)) { // CraftBukkit use thread-safe spam
-                    this.networkManager.a("disconnect.spam"); // CraftBukkit disconnect client asynchronously
+                    // CraftBukkit start
+                    Waitable waitable = new Waitable() {
+                        @Override
+                        protected Object evaluate() {
+                            NetServerHandler.this.disconnect("disconnect.spam");
+                            return null;
+                        }
+                    };
+
+                    this.minecraftServer.processQueue.add(waitable);
+
+                    try {
+                        waitable.get();
+                    } catch (InterruptedException e) {
+                        Thread.currentThread().interrupt();
+                    } catch (ExecutionException e) {
+                        throw new RuntimeException(e);
+                    }
+                    // CraftBukkit end
                 }
             }
         }
@@ -874,7 +929,7 @@ public class NetServerHandler extends NetHandler {
                         waitable.get();
                     } catch (InterruptedException e) {
                         Thread.currentThread().interrupt(); // This is proper habit for java. If we aren't handling it, pass it on!
-                    } catch (java.util.concurrent.ExecutionException e) {
+                    } catch (ExecutionException e) {
                         throw new RuntimeException("Exception processing chat event", e.getCause());
                     }
                 } else {