Make sure that HttpObjectDecoder decodes the last HTTP message without 'Content-Length' header

- Fixes #1410
- Revert 1e5f266a3c and provide a proper fix with a test

codec-http/src/main/java/io/netty/handler/codec/http/HttpObjectDecoder.java

@@ -21,6 +21,7 @@ import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelPipeline;
 import io.netty.channel.MessageList;
 import io.netty.handler.codec.DecoderResult;
+import io.netty.handler.codec.PrematureChannelClosureException;
 import io.netty.handler.codec.ReplayingDecoder;
 import io.netty.handler.codec.TooLongFrameException;
 
@@ -420,6 +421,44 @@ public abstract class HttpObjectDecoder extends ReplayingDecoder<HttpObjectDecod
         }
     }
 
+    @Override
+    protected void decodeLast(ChannelHandlerContext ctx, ByteBuf in, MessageList<Object> out) throws Exception {
+        decode(ctx, in, out);
+
+        // Handle the last unfinished message.
+        if (message != null) {
+            // Get the length of the content received so far for the last message.
+            HttpMessage message = this.message;
+            int actualContentLength;
+            if (content != null) {
+                actualContentLength = content.readableBytes();
+            } else {
+                actualContentLength = 0;
+            }
+
+            // Add the last message (and its content) to the output.
+            reset(out);
+
+            // Check if this situation where the connection has been closed before decoding the last message completely
+            // is expected or not.  If unexpected, set decoder result as failure.
+            boolean prematureClosure;
+            if (isDecodingRequest()) {
+                // The last request did not wait for a response.
+                prematureClosure = true;
+            } else {
+                // Compare the length of the received content and the 'Content-Length' header.
+                // If the 'Content-Length' header is absent, the length of the content is determined by the end of the
+                // connection, so it is perfectly fine.
+                long expectedContentLength = HttpHeaders.getContentLength(message, -1);
+                prematureClosure = expectedContentLength >= 0 && actualContentLength != expectedContentLength;
+            }
+
+            if (prematureClosure) {
+                message.setDecoderResult(DecoderResult.failure(new PrematureChannelClosureException()));
+            }
+        }
+    }
+
     protected boolean isContentAlwaysEmpty(HttpMessage msg) {
         if (msg instanceof HttpResponse) {
             HttpResponse res = (HttpResponse) msg;
@@ -450,7 +489,7 @@ public abstract class HttpObjectDecoder extends ReplayingDecoder<HttpObjectDecod
         reset(null);
     }
 
-    protected final void reset(MessageList<Object> out) {
+    private void reset(MessageList<Object> out) {
         if (out != null) {
             HttpMessage message = this.message;
             ByteBuf content = this.content;

codec-http/src/main/java/io/netty/handler/codec/http/HttpResponseDecoder.java

@@ -16,9 +16,7 @@
 package io.netty.handler.codec.http;
 
 import io.netty.buffer.ByteBuf;
-import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelPipeline;
-import io.netty.channel.MessageList;
 import io.netty.handler.codec.TooLongFrameException;
 
 
@@ -119,20 +117,4 @@ public class HttpResponseDecoder extends HttpObjectDecoder {
     protected boolean isDecodingRequest() {
         return false;
     }
-
-    @Override
-    protected void decodeLast(ChannelHandlerContext ctx, ByteBuf in, MessageList<Object> out) throws Exception {
-        super.decodeLast(ctx, in, out);
-        MessageList<Object> msgs = MessageList.newInstance();
-        reset(msgs);
-        if (!msgs.isEmpty()) {
-            // Handle the case where the server sends an empty 200 response and close the connection
-            // https://github.com/netty/netty/issues/1410
-            HttpResponse response = (HttpResponse) msgs.get(0);
-            if (response.getStatus().code() == 200) {
-                out.add(msgs);
-            }
-        }
-        msgs.recycle();
-    }
 }

codec-http/src/test/java/io/netty/handler/codec/http/HttpResponseDecoderTest.java

@@ -0,0 +1,44 @@
+/*
+ * 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.handler.codec.http;
+
+import io.netty.buffer.Unpooled;
+import io.netty.channel.embedded.EmbeddedChannel;
+import io.netty.util.CharsetUtil;
+import org.junit.Test;
+
+import static org.hamcrest.CoreMatchers.*;
+import static org.junit.Assert.*;
+
+public class HttpResponseDecoderTest {
+    @Test
+    public void testEmptyHeaderAndEmptyContent() {
+        EmbeddedChannel ch = new EmbeddedChannel(new HttpResponseDecoder());
+        ch.writeInbound(Unpooled.copiedBuffer("HTTP/1.1 200 OK\r\n\r\n", CharsetUtil.US_ASCII));
+
+        HttpResponse res = (HttpResponse) ch.readInbound();
+        assertThat(res.getProtocolVersion(), sameInstance(HttpVersion.HTTP_1_1));
+        assertThat(res.getStatus(), is(HttpResponseStatus.OK));
+        assertThat(ch.readInbound(), is(nullValue()));
+
+        assertThat(ch.finish(), is(true));
+
+        LastHttpContent content = (LastHttpContent) ch.readInbound();
+        assertThat(content.content().isReadable(), is(false));
+
+        assertThat(ch.readInbound(), is(nullValue()));
+    }
+}