8304963: HttpServer closes connection after processing HEAD after JDK-7026262

Reviewed-by: dfuchs

src/jdk.httpserver/share/classes/sun/net/httpserver/ExchangeImpl.java

@@ -240,6 +240,7 @@ class ExchangeImpl {
             }
             noContentToSend = true;
             contentLen = 0;
+            o.setWrappedStream (new FixedLengthOutputStream (this, ros, contentLen));
         } else { /* not a HEAD request or 304 response */
             if (contentLen == 0) {
                 if (http10) {

test/jdk/com/sun/net/httpserver/bugs/HeadKeepAlive.java

@@ -0,0 +1,128 @@
+/*
+ * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/**
+ * @test
+ * @bug 8304963
+ * @summary Connection should be reusable after HEAD request
+ * @library /test/lib
+ * @run junit HeadKeepAlive
+ */
+
+import com.sun.net.httpserver.HttpExchange;
+import com.sun.net.httpserver.HttpHandler;
+import com.sun.net.httpserver.HttpServer;
+import jdk.test.lib.net.URIBuilder;
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
+import java.net.Proxy;
+import java.net.URL;
+import java.util.logging.Handler;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+import java.util.logging.SimpleFormatter;
+import java.util.logging.StreamHandler;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class HeadKeepAlive
+{
+
+    public static final Logger LOGGER = Logger.getLogger("com.sun.net.httpserver");
+
+    @Test
+    void test() throws IOException, InterruptedException {
+        HttpServer httpServer = startHttpServer();
+        int port = httpServer.getAddress().getPort();
+        try {
+            URL url = URIBuilder.newBuilder()
+                .scheme("http")
+                .loopback()
+                .port(port)
+                .path("/firstCall")
+                .toURLUnchecked();
+            HttpURLConnection uc = (HttpURLConnection)url.openConnection(Proxy.NO_PROXY);
+            uc.setRequestMethod("HEAD");
+            int responseCode = uc.getResponseCode();
+            assertEquals(200, responseCode, "First request should succeed");
+
+            URL url2 = URIBuilder.newBuilder()
+                    .scheme("http")
+                    .loopback()
+                    .port(port)
+                    .path("/secondCall")
+                    .toURLUnchecked();
+            HttpURLConnection uc2 = (HttpURLConnection)url2.openConnection(Proxy.NO_PROXY);
+            uc2.setRequestMethod("HEAD");
+            responseCode = uc2.getResponseCode();
+            assertEquals(200, responseCode, "Second request should reuse connection");
+        } finally {
+            httpServer.stop(0);
+        }
+    }
+
+    /**
+     * Http Server
+     */
+    HttpServer startHttpServer() throws IOException {
+        Handler outHandler = new StreamHandler(System.out,
+                                 new SimpleFormatter());
+        outHandler.setLevel(Level.FINEST);
+        LOGGER.setLevel(Level.FINEST);
+        LOGGER.addHandler(outHandler);
+        InetAddress loopback = InetAddress.getLoopbackAddress();
+        HttpServer httpServer = HttpServer.create(new InetSocketAddress(loopback, 0), 0);
+        httpServer.createContext("/", new MyHandler());
+        httpServer.start();
+        return httpServer;
+    }
+
+    class MyHandler implements HttpHandler {
+
+        volatile int port1;
+        @Override
+        public void handle(HttpExchange t) throws IOException {
+            String path = t.getRequestURI().getPath();
+            if (path.equals("/firstCall")) {
+                port1 = t.getRemoteAddress().getPort();
+                System.out.println("First connection on client port = " + port1);
+                // send response
+                t.sendResponseHeaders(200, -1);
+                // the connection should still be reusable
+            } else if (path.equals("/secondCall")) {
+                int port2 = t.getRemoteAddress().getPort();
+                System.out.println("Second connection on client port = " + port2);
+                if (port1 == port2) {
+                    t.sendResponseHeaders(200, -1);
+                } else {
+                    t.sendResponseHeaders(500, -1);
+                }
+            }
+            t.close();
+        }
+    }
+}