8289291: HttpServer sets incorrect value for "max" parameter in Keep-Alive header value

Reviewed-by: michaelm, dfuchs

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

@@ -672,9 +672,8 @@ class ServerImpl implements TimeSource {
                         rheaders.set ("Connection", "close");
                     } else if (chdr.equalsIgnoreCase("keep-alive")) {
                         rheaders.set("Connection", "keep-alive");
-                        int idle=(int)(ServerConfig.getIdleInterval()/1000);
-                        int max=ServerConfig.getMaxIdleConnections();
-                        String val = "timeout="+idle+", max="+max;
+                        int timeoutSeconds = (int) (ServerConfig.getIdleInterval() / 1000);
+                        String val = "timeout=" + timeoutSeconds;
                         rheaders.set("Keep-Alive", val);
                     }
                 }

test/jdk/com/sun/net/httpserver/Http10KeepAliveMaxParamTest.java

@@ -0,0 +1,104 @@
+/*
+ * Copyright (c) 2022, 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.
+ */
+
+import com.sun.net.httpserver.HttpServer;
+import jdk.test.lib.net.HttpHeaderParser;
+
+import java.io.OutputStream;
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
+import java.net.Socket;
+import java.nio.charset.StandardCharsets;
+import java.util.List;
+import java.util.Locale;
+
+/*
+ * @test
+ * @bug 8289291
+ * @summary Verifies that the HttpServer doesn't add the "max" parameter to the Keep-Alive header
+ * that it sets in the response
+ * @library /test/lib
+ * @run main Http10KeepAliveMaxParamTest
+ */
+public class Http10KeepAliveMaxParamTest {
+
+    /**
+     * Sends a HTTP/1.0 request with "Connection: keep-alive" header to the
+     * com.sun.net.httpserver.HttpServer and then verifies that if the server responds back
+     * with a "Keep-Alive" header in the response, then the header value doesn't have the
+     * "max" parameter.
+     */
+    public static void main(final String[] args) throws Exception {
+        final var bindAddr = new InetSocketAddress(InetAddress.getLoopbackAddress(), 0);
+        final int backlog = 0;
+        final HttpServer server = HttpServer.create(bindAddr, backlog);
+        server.createContext("/", (exchange) -> {
+            System.out.println("Sending response for request " + exchange.getRequestURI());
+            exchange.sendResponseHeaders(200, 0);
+            exchange.getResponseBody().close();
+        });
+        server.start();
+        System.out.println("Server started at address " + server.getAddress());
+        try {
+            try (final Socket sock = new Socket(bindAddr.getAddress(), server.getAddress().getPort())) {
+                // send a HTTP/1.0 request
+                final String request = "GET /test/foo HTTP/1.0\r\nConnection: keep-alive\r\n\r\n";
+                final OutputStream os = sock.getOutputStream();
+                os.write(request.getBytes(StandardCharsets.UTF_8));
+                os.flush();
+                System.out.println("Sent request to server:");
+                System.out.println(request);
+                // read the response headers
+                final HttpHeaderParser headerParser = new HttpHeaderParser(sock.getInputStream());
+                // verify that the response contains 200 status code.
+                // method is oddly named, but it returns status line of response
+                final String statusLine = headerParser.getRequestDetails();
+                System.out.println("Received status line " + statusLine);
+                if (statusLine == null || !statusLine.contains("200")) {
+                    throw new AssertionError("Unexpected response from server," +
+                            " status line = " + statusLine);
+                }
+                System.out.println("Server responded with headers: " + headerParser.getHeaderMap());
+                // spec doesn't mandate the presence of the Keep-Alive header. We skip this test
+                // if the server doesn't send one
+                final List<String> keepAliveHeader = headerParser.getHeaderValue("keep-alive");
+                if (keepAliveHeader == null || keepAliveHeader.isEmpty()) {
+                    // skip the test
+                    System.out.println("Test SKIPPED since the server didn't return a keep-alive" +
+                            " header in response");
+                    return;
+                }
+                // we expect only one keep-alive header and there shouldn't be any "max" parameter
+                // in that value
+                final String val = keepAliveHeader.get(0);
+                if (val.toLowerCase(Locale.ROOT).contains("max")) {
+                    throw new AssertionError("Server wasn't supposed to send " +
+                            "\"max\" parameter in keep-alive response header. " +
+                            "Actual header value = " + val);
+                }
+            }
+        } finally {
+            server.stop(0);
+        }
+    }
+}