Fix FileTransferManager invoking request listeners

those need to be called asynchronously.

Also add a small API for that.

smack-core/src/main/java/org/jivesoftware/smack/util/Async.java

@@ -0,0 +1,26 @@
+/**
+ *
+ * Copyright 2014 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smack.util;
+
+public class Async {
+
+    public static void go(Runnable runnable) {
+        Thread thread = new Thread(runnable);
+        thread.setDaemon(true);
+        thread.start();
+    }
+}

smack-extensions/src/main/java/org/jivesoftware/smackx/filetransfer/FileTransferManager.java

@@ -26,6 +26,7 @@ import org.jivesoftware.smack.filter.PacketTypeFilter;
 import org.jivesoftware.smack.packet.IQ;
 import org.jivesoftware.smack.packet.Packet;
 import org.jivesoftware.smack.packet.XMPPError;
+import org.jivesoftware.smack.util.Async;
 import org.jivesoftware.smackx.si.packet.StreamInitiation;
 import org.jxmpp.util.XmppStringUtils;
 
@@ -76,10 +77,19 @@ public class FileTransferManager extends Manager {
         connection.addPacketListener(new PacketListener() {
             public void processPacket(Packet packet) {
                 StreamInitiation si = (StreamInitiation) packet;
-                FileTransferRequest request = new FileTransferRequest(FileTransferManager.this, si);
+                final FileTransferRequest request = new FileTransferRequest(FileTransferManager.this, si);
-                for (FileTransferListener listener : listeners) {
+                for (final FileTransferListener listener : listeners) {
+                    // Those listeners need to be called asynchronously, in
+                    // order to not block further processing of incoming
+                    // stanzas. They also may send further requests, whose
+                    // responses are not processed if we do not call them
+                    // asynchronously.
+                    Async.go(new Runnable() {
+                        public void run() {
                             listener.fileTransferRequest(request);
                         }
+                    });
+                }
             }
         }, new AndFilter(new PacketTypeFilter(StreamInitiation.class), IQTypeFilter.SET));
 	}