[#1385] Fix NPE which was triggered if a write was executed but the HeadHandler not init yet

testsuite/src/test/java/io/netty/testsuite/transport/socket/WriteBeforeRegisteredTest.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2013 The Netty Project
+ *
+ * The Netty Project licenses this file to you 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 io.netty.testsuite.transport.socket;
+
+import io.netty.bootstrap.Bootstrap;
+import io.netty.buffer.Unpooled;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.ChannelStateHandlerAdapter;
+import io.netty.channel.socket.SocketChannel;
+import org.junit.Test;
+
+public class WriteBeforeRegisteredTest extends AbstractClientSocketTest {
+
+    @Test(timeout = 30000)
+    public void testWriteBeforeConnect() throws Throwable {
+        run();
+    }
+
+    public void testWriteBeforeConnect(Bootstrap cb) throws Throwable {
+        TestHandler h = new TestHandler();
+        SocketChannel ch = null;
+        try {
+            ch = (SocketChannel) cb.handler(h).connect().channel();
+            ch.write(Unpooled.wrappedBuffer(new byte[] { 1 })).await();
+        } finally {
+            if (ch != null) {
+                ch.close();
+            }
+        }
+    }
+
+    private static class TestHandler extends ChannelStateHandlerAdapter {
+
+        @Override
+        public void inboundBufferUpdated(ChannelHandlerContext ctx) throws Exception {
+            ctx.fireInboundBufferUpdated();
+        }
+
+        @Override
+        public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
+            cause.printStackTrace();
+        }
+    }
+}

transport/src/main/java/io/netty/channel/DefaultChannelHandlerContext.java

@@ -1502,7 +1502,7 @@ final class DefaultChannelHandlerContext extends DefaultAttributeMap implements
         validateFuture(promise, true);
 
         DefaultChannelHandlerContext ctx = prev;
-        EventExecutor executor;
+        EventExecutor executor = executor();
         final boolean msgBuf;
 
         if (message instanceof ByteBuf) {
@@ -1519,7 +1519,26 @@ final class DefaultChannelHandlerContext extends DefaultAttributeMap implements
                     break;
                 }
 
-                ctx = ctx.prev;
+                DefaultChannelHandlerContext prev = ctx.prev;
+                if (prev == null) {
+                    assert ctx == pipeline.head;
+                    // this means we reached end of pipeline but the head-handler was not yet init.
+                    // in this case init it now and schedule the write via the executor so it is
+                    // done after fireChannelRegistered() completes
+                    //
+                    // See https://github.com/netty/netty/issues/1385
+                    ctx.initHeadHandler();
+
+                    executor.execute(new Runnable() {
+                        @Override
+                        public void run() {
+                            write(message, promise);
+                        }
+                    });
+                    return promise;
+                } else {
+                    ctx = prev;
+                }
             }
         } else {
             msgBuf = true;