diff -r de9dd71ef18c -r 88a41734ddbe test/jdk/java/net/SocketImpl/CustomSocketImpls.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/jdk/java/net/SocketImpl/CustomSocketImpls.java	Wed Feb 20 20:55:24 2019 +0000
@@ -0,0 +1,620 @@
+/*
+ * Copyright (c) 2019, 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
+ * @modules java.base/java.net:+open java.base/sun.nio.ch:+open
+ * @run testng/othervm CustomSocketImpls
+ * @run testng/othervm -Djdk.net.usePlainSocketImpl CustomSocketImpls
+ */
+
+import java.io.FileDescriptor;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.lang.reflect.Field;
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
+import java.net.Proxy;
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.net.SocketAddress;
+import java.net.SocketImpl;
+import java.net.SocketImplFactory;
+import java.nio.channels.ServerSocketChannel;
+import java.nio.channels.SocketChannel;
+import java.util.function.Consumer;
+
+import org.testng.annotations.Test;
+import static org.testng.Assert.*;
+
+@Test
+public class CustomSocketImpls {
+
+    /**
+     * Test ServerSocket is created with the expected SocketImpl.
+     */
+    public void testServerSocketSocketImpl() throws Exception {
+        try (ServerSocket ss = new ServerSocket()) {
+            SocketImpl si = getSocketImpl(ss);
+            assertTrue(isPlatformSocketImpl(si));
+        }
+
+        SocketImpl impl = new CustomSocketImpl(true);
+        try (ServerSocket ss = new ServerSocket(impl){}) {
+            SocketImpl si = getSocketImpl(ss);
+            assertTrue(si instanceof CustomSocketImpl);
+        }
+
+        setSocketFactory(() -> new CustomSocketImpl(true));
+        try (ServerSocket ss = new ServerSocket()) {
+            SocketImpl si = getSocketImpl(ss);
+            assertTrue(si instanceof CustomSocketImpl);
+        } finally {
+            setSocketFactory(null);
+        }
+    }
+
+    /**
+     * Test Socket is created with the expected SocketImpl.
+     */
+    public void tesSocketSocketImpl() throws Exception {
+        try (Socket s = new Socket()) {
+            SocketImpl si = getSocketImpl(s);
+            assertTrue(isSocksSocketImpl(si));
+            SocketImpl delegate = getDelegate(si);
+            assertTrue(isPlatformSocketImpl(delegate));
+        }
+
+        try (Socket s = new Socket((SocketImpl) null){}) {
+            assertTrue(getSocketImpl(s) == null);
+        }
+
+        try (Socket s = new Socket(Proxy.NO_PROXY)) {
+            SocketImpl si = getSocketImpl(s);
+            assertTrue(isPlatformSocketImpl(si));
+        }
+
+        var address = new InetSocketAddress("127.0.0.1", 1000);
+        var socksProxy = new Proxy(Proxy.Type.SOCKS, address);
+        try (Socket s = new Socket(socksProxy)) {
+            SocketImpl si = getSocketImpl(s);
+            assertTrue(isSocksSocketImpl(si));
+            SocketImpl delegate = getDelegate(si);
+            assertTrue(isPlatformSocketImpl(delegate));
+        }
+
+        var httpProxy = new Proxy(Proxy.Type.HTTP, address);
+        try (Socket s = new Socket(httpProxy)) {
+            SocketImpl si = getSocketImpl(s);
+            assertTrue(isHttpConnectSocketImpl(si));
+            SocketImpl delegate = getDelegate(si);
+            assertTrue(isPlatformSocketImpl(delegate));
+        }
+
+        try (Socket s = new Socket(new CustomSocketImpl(false)){}) {
+            SocketImpl si = getSocketImpl(s);
+            assertTrue(si instanceof CustomSocketImpl);
+        }
+
+        setSocketImplFactory(() -> new CustomSocketImpl(false));
+        try (Socket s = new Socket()) {
+            SocketImpl si = getSocketImpl(s);
+            assertTrue(si instanceof CustomSocketImpl);
+        } finally {
+            setSocketImplFactory(null);
+        }
+    }
+
+    /**
+     * ServerSocket using default SocketImpl. Test accept returning a Socket
+     * that initially doesn't have a SocketImpl.
+     */
+    public void test1() throws Exception {
+        var socket = new Socket((SocketImpl) null) { };
+        assertTrue(getSocketImpl(socket) == null);
+        testAccept(socket, s -> {
+            assertTrue(s == socket);
+            SocketImpl si = getSocketImpl(s);
+            assertTrue(isPlatformSocketImpl(si));
+            checkFields(si);
+        });
+    }
+
+    /**
+     * ServerSocket using default SocketImpl. Test accept returning a Socket
+     * that has an existing default SocketImpl.
+     */
+    public void test2() throws Exception {
+        var socket = new Socket();
+        SocketImpl si = getSocketImpl(socket);
+        assertTrue(isSocksSocketImpl(si));
+        SocketImpl delegate = getDelegate(si);
+        assertTrue(isPlatformSocketImpl(delegate));
+        testAccept(socket, s -> {
+            assertTrue(s == socket);
+            assertTrue(getSocketImpl(s) == si);
+            assertTrue(getDelegate(si) == delegate);
+            checkFields(delegate);
+        });
+    }
+
+    /**
+     * ServerSocket using default SocketImpl. A SocketImplFactory is set to
+     * return a custom SocketImpl. Test accept returning a Socket that initially
+     * doesn't have a SocketImpl.
+     */
+    public void test3() throws Exception {
+        var socket = new Socket((SocketImpl) null) { };
+        assertTrue(getSocketImpl(socket) == null);
+        testAccept(socket, () -> new CustomSocketImpl(false), s -> {
+            assertTrue(s == socket);
+            SocketImpl si = getSocketImpl(s);
+            assertTrue(si instanceof CustomSocketImpl);
+            checkFields(si);
+        });
+    }
+
+    /**
+     * ServerSocket using default SocketImpl. Test accept returning a Socket
+     * that has an existing custom SocketImpl.
+     */
+    public void test4() throws Exception {
+        SocketImpl si = new CustomSocketImpl(false);
+        Socket socket = new Socket(si) { };
+        assertTrue(getSocketImpl(socket) == si);
+        testAccept(socket, s -> {
+            assertTrue(s == socket);
+            assertTrue(getSocketImpl(s) == si);
+            checkFields(si);
+        });
+    }
+
+    /**
+     * ServerSocket using a custom SocketImpl. Test accept returning a Socket
+     * that initially doesn't have a SocketImpl.
+     */
+    public void test5() throws Exception {
+        SocketImpl impl = new CustomSocketImpl(true);
+        Socket socket = new Socket((SocketImpl) null) { };
+        assertTrue(getSocketImpl(socket) == null);
+        testAccept(impl, socket, s -> {
+            assertTrue(s == socket);
+            SocketImpl si = getSocketImpl(s);
+            assertTrue(isPlatformSocketImpl(si));
+            checkFields(si);
+        });
+    }
+
+    /**
+     * ServerSocket using a custom SocketImpl. Test accept returning a Socket
+     * that has an existing default SocketImpl.
+     */
+    public void test6() throws Exception {
+        SocketImpl impl = new CustomSocketImpl(true);
+        var socket = new Socket();
+        SocketImpl si = getSocketImpl(socket);
+        assertTrue(isSocksSocketImpl(si));
+        SocketImpl delegate = getDelegate(si);
+        assertTrue(isPlatformSocketImpl(delegate));
+        testAccept(impl, socket, s -> {
+            assertTrue(s == socket);
+            assertTrue(getSocketImpl(s) == si);
+            assertTrue(getDelegate(si) == delegate);
+            checkFields(delegate);
+        });
+    }
+
+    /**
+     * ServerSocket using a custom SocketImpl. A SocketImplFactory is set to
+     * return a custom SocketImpl. Test accept returning a Socket that initially
+     * doesn't have a SocketImpl.
+     */
+    public void test7() throws Exception {
+        var socket = new Socket((SocketImpl) null) { };
+        assertTrue(getSocketImpl(socket) == null);
+        Socket s1 = null;
+        Socket s2 = null;
+        try (ServerSocket ss = prepareToAccept(new CustomSocketImpl(true), socket)) {
+            s1 = new Socket(ss.getInetAddress(), ss.getLocalPort());
+            setSocketImplFactory(() -> new CustomSocketImpl(false));
+            try {
+                s2 = ss.accept();
+                SocketImpl si = getSocketImpl(s2);
+                assertTrue(si instanceof CustomSocketImpl);
+                checkFields(si);
+            } finally {
+                setSocketImplFactory(null);
+            }
+        } finally {
+            if (s1 != null) s1.close();
+            if (s2 != null) s1.close();
+        }
+    }
+
+    /**
+     * ServerSocket using a custom SocketImpl. A SocketImplFactory is set to
+     * return a custom SocketImpl. Test accept returning a Socket has an existing
+     * custom SocketImpl.
+     */
+    public void test8() throws Exception {
+        SocketImpl si = new CustomSocketImpl(false);
+        Socket socket = new Socket(si) { };
+        assertTrue(getSocketImpl(socket) == si);
+        Socket s1 = null;
+        Socket s2 = null;
+        try (ServerSocket ss = prepareToAccept(new CustomSocketImpl(true), socket)) {
+            s1 = new Socket(ss.getInetAddress(), ss.getLocalPort());
+            setSocketImplFactory(() -> new CustomSocketImpl(false));
+            try {
+                s2 = ss.accept();
+                assertTrue(getSocketImpl(s2) == si);
+                checkFields(si);
+            } finally {
+                setSocketImplFactory(null);
+            }
+        } finally {
+            if (s1 != null) s1.close();
+            if (s2 != null) s1.close();
+        }
+    }
+
+    /**
+     * Creates a ServerSocket that returns the given Socket from accept.
+     * The consumer is invoked with the accepted socket.
+     */
+    static void testAccept(Socket socket, Consumer<Socket> consumer)
+        throws IOException
+    {
+        Socket s1 = null;
+        Socket s2 = null;
+        try (ServerSocket ss = prepareToAccept(socket)) {
+            s1 = new Socket(ss.getInetAddress(), ss.getLocalPort());
+            s2 = ss.accept();
+            consumer.accept(s2);
+        } finally {
+            if (s1 != null) s1.close();
+            if (s2 != null) s1.close();
+        }
+    }
+
+    /**
+     * Creates a ServerSocket that returns the given Socket from accept. The
+     * given SocketImplFactory is set during the accept and the consumer is
+     * invoked when the accepted socket.
+     */
+    static void testAccept(Socket socket, SocketImplFactory factory, Consumer<Socket> consumer)
+        throws IOException
+    {
+        Socket s1 = null;
+        Socket s2 = null;
+        try (ServerSocket ss = prepareToAccept(socket)) {
+            s1 = new Socket(ss.getInetAddress(), ss.getLocalPort());
+            setSocketImplFactory(factory);
+            try {
+                s2 = ss.accept();
+            } finally {
+                setSocketImplFactory(null);
+            }
+            consumer.accept(s2);
+        } finally {
+            if (s1 != null) s1.close();
+            if (s2 != null) s1.close();
+        }
+    }
+
+    /**
+     * Creates a ServerSocket with a SocketImpl that returns the given Socket
+     * from accept. The consumer is invoked with the accepted socket.
+     */
+    static void testAccept(SocketImpl impl, Socket socket, Consumer<Socket> consumer)
+        throws IOException
+    {
+        Socket s1 = null;
+        Socket s2 = null;
+        try (ServerSocket ss = prepareToAccept(impl, socket)) {
+            s1 = new Socket(ss.getInetAddress(), ss.getLocalPort());
+            s2 = ss.accept();
+            consumer.accept(s2);
+        } finally {
+            if (s1 != null) s1.close();
+            if (s2 != null) s1.close();
+        }
+    }
+
+    /**
+     * Creates a ServerSocket that returns the given Socket from accept.
+     */
+    static ServerSocket prepareToAccept(Socket s) throws IOException {
+        return new ServerSocket(0) {
+            @Override
+            public Socket accept() throws IOException {
+                implAccept(s);
+                return s;
+            }
+        };
+    }
+
+    /**
+     * Creates a ServerSocket with a SocketImpl that returns the given Socket
+     * from accept.
+     */
+    static ServerSocket prepareToAccept(SocketImpl impl, Socket s) throws IOException {
+        ServerSocket ss = new ServerSocket(impl) {
+            @Override
+            public Socket accept() throws IOException {
+                implAccept(s);
+                return s;
+            }
+        };
+        ss.bind(new InetSocketAddress(0));
+        return ss;
+    }
+
+    /**
+     * Returns the socket's SocketImpl
+     */
+    static SocketImpl getSocketImpl(Socket s) {
+        try {
+            Field f = Socket.class.getDeclaredField("impl");
+            f.setAccessible(true);
+            return (SocketImpl) f.get(s);
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * Returns the server socket's SocketImpl
+     */
+    static SocketImpl getSocketImpl(ServerSocket ss) {
+        try {
+            Field f = ServerSocket.class.getDeclaredField("impl");
+            f.setAccessible(true);
+            return (SocketImpl) f.get(ss);
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * Returns the SocketImpl that the given SocketImpl delegates to
+     */
+    static SocketImpl getDelegate(SocketImpl si) {
+        try {
+            Class<?> clazz = Class.forName("java.net.DelegatingSocketImpl");
+            Field f = clazz.getDeclaredField("delegate");
+            f.setAccessible(true);
+            return (SocketImpl) f.get(si);
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * Returns the value of a SocketImpl field
+     */
+    static <T> T get(SocketImpl si, String name) {
+        try {
+            Field f = SocketImpl.class.getDeclaredField(name);
+            f.setAccessible(true);
+            return (T) f.get(si);
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * Sets the value of SocketImpl field
+     */
+    static void set(SocketImpl si, String name, Object value) {
+        try {
+            Field f = SocketImpl.class.getDeclaredField(name);
+            f.setAccessible(true);
+            f.set(si, value);
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * Returns true if the SocketImpl is a PlatformSocketImpl
+     */
+    static boolean isPlatformSocketImpl(SocketImpl si) {
+        try {
+            Class<?> clazz = Class.forName("sun.net.PlatformSocketImpl");
+            return clazz.isInstance(si);
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * Returns true if the SocketImpl is a SocksSocketImpl
+     */
+    static boolean isSocksSocketImpl(SocketImpl si) {
+        try {
+            Class<?> clazz = Class.forName("java.net.SocksSocketImpl");
+            return clazz.isInstance(si);
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * Returns true if the SocketImpl is a HttpConnectSocketImpl
+     */
+    static boolean isHttpConnectSocketImpl(SocketImpl si) {
+        try {
+            Class<?> clazz = Class.forName("java.net.HttpConnectSocketImpl");
+            return clazz.isInstance(si);
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * Socket.setSocketImplFactory
+     */
+    static void setSocketImplFactory(SocketImplFactory factory) {
+        try {
+            Field f = Socket.class.getDeclaredField("factory");
+            f.setAccessible(true);
+            f.set(null, factory);
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * ServerSocket.setSocketFactory
+     */
+    static void setSocketFactory(SocketImplFactory factory) {
+        try {
+            Field f = ServerSocket.class.getDeclaredField("factory");
+            f.setAccessible(true);
+            f.set(null, factory);
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * Checks the 4 protected fields of a SocketImpl to make sure that they
+     * have been initialized.
+     */
+    static void checkFields(SocketImpl si) {
+        FileDescriptor fd = get(si, "fd");
+        InetAddress address = get(si, "address");
+        int port = get(si, "port");
+        int localport = get(si, "localport");
+        assertTrue(fd.valid() && address != null && port != 0 && localport != 0);
+    }
+
+    /**
+     * Custom SocketImpl that is layed on a SocketChannel or ServerSocketChannel
+     */
+    static class CustomSocketImpl extends SocketImpl {
+        private final boolean server;
+        private ServerSocketChannel ssc;
+        private SocketChannel sc;
+
+        CustomSocketImpl(boolean server) {
+            this.server = server;
+        }
+
+        @Override
+        protected void create(boolean stream) throws IOException {
+            if (server) {
+                ssc = ServerSocketChannel.open();
+            } else {
+                sc = SocketChannel.open();
+            }
+        }
+
+        @Override
+        protected void connect(String host, int port) throws IOException {
+            connect(new InetSocketAddress(host, port), 0);
+        }
+
+        @Override
+        protected void connect(InetAddress address, int port) throws IOException {
+            connect(new InetSocketAddress(address, port), 0);
+        }
+
+        @Override
+        protected void connect(SocketAddress remote, int timeout) throws IOException {
+            sc.connect(remote);
+            super.address = ((InetSocketAddress) remote).getAddress();
+            super.port = ((InetSocketAddress) remote).getPort();
+        }
+
+        @Override
+        protected void bind(InetAddress address, int port) throws IOException {
+            if (server) {
+                ssc.bind(new InetSocketAddress(address, port));
+            } else {
+                sc.bind(new InetSocketAddress(address, port));
+            }
+            super.address = address;
+            super.localport = ssc.socket().getLocalPort();
+        }
+
+        @Override
+        protected void listen(int backlog) {
+            // do nothing
+        }
+
+        @Override
+        protected void accept(SocketImpl si) throws IOException {
+            SocketChannel peer = ssc.accept();
+            FileDescriptor fd;
+            try {
+                Class<?> clazz = Class.forName("sun.nio.ch.SocketChannelImpl");
+                Field f = clazz.getDeclaredField("fd");
+                f.setAccessible(true);
+                fd = (FileDescriptor) f.get(peer);
+            } catch (Exception e) {
+                throw new RuntimeException(e);
+            }
+            set(si, "fd", fd);
+            set(si, "address", peer.socket().getInetAddress());
+            set(si, "port", peer.socket().getPort());
+            set(si, "localport", peer.socket().getLocalPort());
+        }
+
+        @Override
+        protected InputStream getInputStream() {
+            throw new RuntimeException();
+        }
+
+        @Override
+        protected OutputStream getOutputStream() {
+            throw new RuntimeException();
+        }
+
+        @Override
+        protected int available() {
+            return 0;
+        }
+
+        @Override
+        protected void close() {
+        }
+
+        @Override
+        protected void sendUrgentData(int data) {
+            throw new RuntimeException();
+        }
+
+        @Override
+        public void setOption(int option, Object value) {
+            throw new RuntimeException();
+        }
+
+        @Override
+        public Object getOption(int option) {
+            throw new RuntimeException();
+        }
+    }
+}