/*

 * Copyright (c) 2018, 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

 * @requires (os.family == "linux" | os.family == "mac")

 * @bug 8203937

 * @summary Test reading bytes from a socket after the connection has been

 *          reset by the peer

 */

import java.io.IOException;

import java.io.PrintStream;

import java.net.InetAddress;

import java.net.InetSocketAddress;

import java.net.ServerSocket;

import java.net.Socket;

/**

 * This test exercises platform specific and unspecified behavior. It exists

 * only to ensure that the behavior doesn't change between JDK releases.

 */

public class ReadAfterReset {

    private static final PrintStream out = System.out;

    // number of bytes to write before the connection reset

    private static final int NUM_BYTES_TO_WRITE = 1000;

    public static void main(String[] args) throws IOException {

        try (ServerSocket ss = new ServerSocket()) {

            ss.bind(new InetSocketAddress(InetAddress.getLoopbackAddress(), 0));

            /**

             * Connect to the server which will write some bytes and reset the

             * connection. The client then attempts to read the bytes sent by

             * the server before it closed the connection.

             */

            out.println("Test connection ...");

            try (Socket s = new Socket()) {

                s.connect(ss.getLocalSocketAddress());

                int nwrote = acceptAndResetConnection(ss);

                int nread = readUntilIOException(s);

                if (nread != nwrote) {

                    throw new RuntimeException("Client read " + nread + ", expected " + nwrote);

                }

            }

            /**

             * Connect to the server which will write some bytes and reset the

             * connection. The client then writes to its end of the connection,

             * failing as the connection is reset. It then attempts to read the

             * bytes sent by the server before it closed the connection.

             */

            out.println();

            out.println("Test connection ...");

            try (Socket s = new Socket()) {

                s.connect(ss.getLocalSocketAddress());

                int nwrote = acceptAndResetConnection(ss);

                writeUntilIOException(s);

                int nread = readUntilIOException(s);

                if (nread != nwrote) {

                    throw new RuntimeException("Client read " + nread + ", expected " + nwrote);

                }

            }

        }

    }

    /**

     * Accept a connection, write bytes, and then reset the connection

     */

    static int acceptAndResetConnection(ServerSocket ss) throws IOException {

        int count = NUM_BYTES_TO_WRITE;

        try (Socket peer = ss.accept()) {

            peer.getOutputStream().write(new byte[count]);

            peer.setSoLinger(true, 0);

            out.format("Server wrote %d bytes and reset connection%n", count);

        }

        return count;

    }

    /**

     * Write bytes to a socket until I/O exception is thrown

     */

    static void writeUntilIOException(Socket s) {

        try {

            byte[] bytes = new byte[100];

            while (true) {

                s.getOutputStream().write(bytes);

                out.format("Client wrote %d bytes%n", bytes.length);

            }

        } catch (IOException ioe) {

            out.format("Client write failed: %s (expected)%n", ioe);

        }

    }

    /**

     * Read bytes from a socket until I/O exception is thrown.

     *

     * @return the number of bytes read before the I/O exception was thrown

     */

    static int readUntilIOException(Socket s) {

        int nread = 0;

        try {

            byte[] bytes = new byte[100];

            while (true) {

                int n = s.getInputStream().read(bytes);

                if (n < 0) {

                    out.println("Client read EOF");

                    break;

                } else {

                    out.format("Client read %s bytes%n", n);

                    nread += n;

                }

            }

        } catch (IOException ioe) {

            out.format("Client read failed: %s (expected)%n", ioe);

        }

        return nread;

    }

}