[#1648] Make sure trailing headers are not dropped during content encoding/decoding

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

@@ -0,0 +1,86 @@
+/*
+ * 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.ByteBuf;
+import io.netty.buffer.Unpooled;
+import io.netty.handler.codec.DecoderResult;
+
+
+final class ComposedLastHttpContent implements LastHttpContent {
+    private final HttpHeaders trailingHeaders;
+    private DecoderResult result;
+
+    ComposedLastHttpContent(HttpHeaders trailingHeaders) {
+        this.trailingHeaders = trailingHeaders;
+    }
+    @Override
+    public HttpHeaders trailingHeaders() {
+        return trailingHeaders;
+    }
+
+    @Override
+    public LastHttpContent copy() {
+        LastHttpContent content = new DefaultLastHttpContent(Unpooled.EMPTY_BUFFER);
+        content.trailingHeaders().set(trailingHeaders());
+        return content;
+    }
+
+    @Override
+    public LastHttpContent retain(int increment) {
+        return this;
+    }
+
+    @Override
+    public LastHttpContent retain() {
+        return this;
+    }
+
+    @Override
+    public HttpContent duplicate() {
+        return copy();
+    }
+
+    @Override
+    public ByteBuf content() {
+        return Unpooled.EMPTY_BUFFER;
+    }
+
+    @Override
+    public DecoderResult getDecoderResult() {
+        return result;
+    }
+
+    @Override
+    public void setDecoderResult(DecoderResult result) {
+        this.result = result;
+    }
+
+    @Override
+    public int refCnt() {
+        return 1;
+    }
+
+    @Override
+    public boolean release() {
+        return false;
+    }
+
+    @Override
+    public boolean release(int decrement) {
+        return false;
+    }
+}

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

@@ -153,9 +153,15 @@ public abstract class HttpContentDecoder extends MessageToMessageDecoder<HttpObj
         if (c instanceof LastHttpContent) {
             finishDecode(out);
 
+            LastHttpContent last = (LastHttpContent) c;
             // Generate an additional chunk if the decoder produced
             // the last product on closure,
-            out.add(LastHttpContent.EMPTY_LAST_CONTENT);
+            HttpHeaders headers = last.trailingHeaders();
+            if (headers.isEmpty()) {
+                out.add(LastHttpContent.EMPTY_LAST_CONTENT);
+            } else {
+                out.add(new ComposedLastHttpContent(headers));
+            }
         }
     }
 

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

@@ -160,8 +160,7 @@ public abstract class HttpContentEncoder extends MessageToMessageCodec<HttpReque
             }
             case AWAIT_CONTENT: {
                 ensureContent(msg);
-                encodeContent((HttpContent) msg, out);
-                if (msg  instanceof LastHttpContent) {
+                if (encodeContent((HttpContent) msg, out)) {
                     state = State.AWAIT_HEADERS;
                 }
                 break;
@@ -194,18 +193,26 @@ public abstract class HttpContentEncoder extends MessageToMessageCodec<HttpReque
         }
     }
 
-    private void encodeContent(HttpContent c, List<Object> out) {
+    private boolean encodeContent(HttpContent c, List<Object> out) {
         ByteBuf content = c.content();
 
         encode(content, out);
 
         if (c instanceof LastHttpContent) {
             finishEncode(out);
+            LastHttpContent last = (LastHttpContent) c;
 
             // Generate an additional chunk if the decoder produced
             // the last product on closure,
-            out.add(LastHttpContent.EMPTY_LAST_CONTENT);
+            HttpHeaders headers = last.trailingHeaders();
+            if (headers.isEmpty()) {
+                out.add(LastHttpContent.EMPTY_LAST_CONTENT);
+            } else {
+                out.add(new ComposedLastHttpContent(headers));
+            }
+            return true;
         }
+        return false;
     }
 
     /**