Send full response for unsupported websocket versions

Motivation:

WebSocketServerHandshakerFactory.sendUnsupportedVersionResponse does not
send a LastHttpContent, nor does it flush, and it doesn't send a content
length.

Modifications:

Changed sendUnsupportedVersionResponse to send FullHttpResponse, to
writeAndFlush, and to set a content length of 0. Also added a test for
this method.

Result:

Upstream handlers will be able to determine the end of the response, the
response will actually get written to the client, and the client will be
able to determine the end of the response.

codec-http/src/main/java/io/netty/handler/codec/http/websocketx/WebSocketServerHandshakerFactory.java

@@ -18,8 +18,9 @@
 import io.netty.channel.Channel;
 import io.netty.channel.ChannelFuture;
 import io.netty.channel.ChannelPromise;
-import io.netty.handler.codec.http.DefaultHttpResponse;
+import io.netty.handler.codec.http.DefaultFullHttpResponse;
 import io.netty.handler.codec.http.HttpHeaderNames;
+import io.netty.handler.codec.http.HttpHeaderUtil;
 import io.netty.handler.codec.http.HttpRequest;
 import io.netty.handler.codec.http.HttpResponse;
 import io.netty.handler.codec.http.HttpResponseStatus;
@@ -154,10 +155,11 @@ public static ChannelFuture sendUnsupportedVersionResponse(Channel channel) {
      * Return that we need cannot not support the web socket version
      */
     public static ChannelFuture sendUnsupportedVersionResponse(Channel channel, ChannelPromise promise) {
-        HttpResponse res = new DefaultHttpResponse(
+        HttpResponse res = new DefaultFullHttpResponse(
                 HttpVersion.HTTP_1_1,
                 HttpResponseStatus.UPGRADE_REQUIRED);
         res.headers().set(HttpHeaderNames.SEC_WEBSOCKET_VERSION, WebSocketVersion.V13.toHttpHeaderValue());
-        return channel.write(res, promise);
+        HttpHeaderUtil.setContentLength(res, 0);
+        return channel.writeAndFlush(res, promise);
     }
 }

codec-http/src/test/java/io/netty/handler/codec/http/websocketx/WebSocketServerHandshakerFactoryTest.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2015 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.websocketx;
+
+import io.netty.channel.embedded.EmbeddedChannel;
+import io.netty.handler.codec.http.FullHttpResponse;
+import io.netty.handler.codec.http.HttpHeaderNames;
+import io.netty.handler.codec.http.HttpHeaderUtil;
+import io.netty.handler.codec.http.HttpResponseStatus;
+import io.netty.util.ReferenceCountUtil;
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+public class WebSocketServerHandshakerFactoryTest {
+
+    @Test
+    public void testUnsupportedVersion() throws Exception {
+        EmbeddedChannel ch = new EmbeddedChannel();
+        WebSocketServerHandshakerFactory.sendUnsupportedVersionResponse(ch);
+        ch.runPendingTasks();
+        Object msg = ch.readOutbound();
+
+        if (!(msg instanceof FullHttpResponse)) {
+            fail("Got wrong response " + msg);
+        }
+        FullHttpResponse response = (FullHttpResponse) msg;
+
+        assertEquals(HttpResponseStatus.UPGRADE_REQUIRED, response.status());
+        assertEquals(WebSocketVersion.V13.toHttpHeaderValue(),
+                response.headers().get(HttpHeaderNames.SEC_WEBSOCKET_VERSION));
+        assertTrue(HttpHeaderUtil.isContentLengthSet(response));
+        assertEquals(0, HttpHeaderUtil.getContentLength(response));
+
+        ReferenceCountUtil.release(response);
+        assertFalse(ch.finish());
+    }
+}