fix(sdk): synchronize packet sending

Prevents obscure XStream conversion issues that occurred when messages
interleaved.

sdk/src/server-api/sc/networking/clients/XStreamClient.java

@@ -157,12 +157,17 @@ public void sendCustomData(byte[] data) throws IOException {
     networkInterface.getOutputStream().flush();
   }
 
-  public void send(ProtocolMessage packet) {
+  public synchronized void send(ProtocolMessage packet) {
     if (!isReady())
-      throw new IllegalStateException("Please call start() before sending any packets!");
-
-    if (isClosed())
-      throw new IllegalStateException("Writing on a closed xStream!");
+      throw new IllegalStateException(
+          String.format("Trying to write packet on %s which wasn't started: %s", shortString(), packet));
+
+    if (isClosed()) {
+      logger.warn("Writing on a closed Stream -> dropped the packet (tried to send package of type {}) Thread: {}",
+          packet.getClass().getSimpleName(),
+          Thread.currentThread().getName());
+      return;
+    }
 
     logger.debug("{}: Sending {} via {} from {}", shortString(), packet, networkInterface, toString());
     if (logger.isTraceEnabled())

server/src/sc/server/network/Client.java

@@ -45,18 +45,6 @@ public void addRole(IClientRole role) {
     this.roles.add(role);
   }
 
-  /** Send a package to the server. */
-  @Override
-  public synchronized void send(ProtocolMessage packet) {
-    if (!isClosed()) {
-      super.send(packet);
-    } else {
-      logger.warn("Writing on a closed Stream -> dropped the packet (tried to send package of type {}) Thread: {}",
-              packet.getClass().getSimpleName(),
-              Thread.currentThread().getName());
-    }
-  }
-
   /** Call listener that handle new Packages. */
   private void notifyOnPacket(Object packet) throws UnprocessedPacketException {
     /*
@@ -103,18 +91,18 @@ private void notifyOnPacket(Object packet) throws UnprocessedPacketException {
   }
 
   /** Call listeners upon error. */
-  private synchronized void notifyOnError(ProtocolErrorMessage packet) {
+  private void notifyOnError(ProtocolErrorMessage packet) {
     for (IClientListener listener : new ArrayList<>(clientListeners)) {
       try {
         listener.onError(this, packet);
       } catch (Exception e) {
-        logger.error("OnError Notification caused an exception.", e);
+        logger.error("OnError Notification caused an exception, error: " + packet, e);
       }
     }
   }
 
   /** Call listeners upon disconnect. */
-  private synchronized void notifyOnDisconnect() {
+  private void notifyOnDisconnect() {
     if (!this.notifiedOnDisconnect) {
       this.notifiedOnDisconnect = true;
       for (IClientListener listener : new ArrayList<>(clientListeners)) {
@@ -142,9 +130,11 @@ public void removeClientListener(IClientListener listener) {
    * @return true iff this client has an AdministratorRole
    */
   public boolean isAdministrator() {
-    for (IClientRole role : this.roles) {
-      if (role instanceof AdministratorRole) {
-        return true;
+    synchronized(roles) {
+      for (IClientRole role : this.roles) {
+        if (role instanceof AdministratorRole) {
+          return true;
+        }
       }
     }
     return false;
@@ -179,12 +169,13 @@ public void authenticate(String password) throws AuthenticationFailedException {
    */
   @Override
   protected void onDisconnect(DisconnectCause cause) {
-    super.onDisconnect(cause);
-    for (IClientRole role : this.roles) {
-      try {
-        role.disconnect(cause);
-      } catch (Exception e) {
-        logger.warn("Couldn't close role.", e);
+    synchronized(roles) {
+      for (IClientRole role : this.roles) {
+        try {
+          role.disconnect(cause);
+        } catch (Exception e) {
+          logger.warn("Couldn't close role.", e);
+        }
       }
     }