/*

 * Copyright (c) 1996, 2015, 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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.

 */

package sun.security.ssl;

import java.io.InputStream;

import java.io.IOException;

import java.nio.ByteBuffer;

import javax.net.ssl.SSLProtocolException;

/**

 * InputStream for application data as returned by SSLSocket.getInputStream().

 *

 * @author David Brownell

 */

final class AppInputStream extends InputStream {

    // the buffer size for each read of network data

    private static final int READ_BUFFER_SIZE = 4096;

    // static dummy array we use to implement skip()

    private static final byte[] SKIP_ARRAY = new byte[256];

    // the related socket of the input stream

    private final SSLSocketImpl socket;

    // the temporary buffer used to read network

    private ByteBuffer buffer;

    // Is application data available in the stream?

    private boolean appDataIsAvailable;

    // One element array used to implement the single byte read() method

    private final byte[] oneByte = new byte[1];

    AppInputStream(SSLSocketImpl conn) {

        this.buffer = ByteBuffer.allocate(READ_BUFFER_SIZE);

        this.socket = conn;

        this.appDataIsAvailable = false;

    }

    /**

     * Return the minimum number of bytes that can be read without blocking.

     *

     * Currently not synchronized.

     */

    @Override

    public int available() throws IOException {

        if ((!appDataIsAvailable) || socket.checkEOF()) {

            return 0;

        }

        return buffer.remaining();

    }

    /**

     * Read a single byte, returning -1 on non-fault EOF status.

     */

    @Override

    public synchronized int read() throws IOException {

        int n = read(oneByte, 0, 1);

        if (n <= 0) { // EOF

            return -1;

        }

        return oneByte[0] & 0xFF;

    }

    /**

     * Reads up to {@code len} bytes of data from the input stream into an

     * array of bytes. An attempt is made to read as many as {@code len} bytes,

     * but a smaller number may be read. The number of bytes actually read

     * is returned as an integer.

     *

     * If the layer above needs more data, it asks for more, so we

     * are responsible only for blocking to fill at most one buffer,

     * and returning "-1" on non-fault EOF status.

     */

    @Override

    public synchronized int read(byte[] b, int off, int len)

            throws IOException {

        if (b == null) {

            throw new NullPointerException();

        } else if (off < 0 || len < 0 || len > b.length - off) {

            throw new IndexOutOfBoundsException();

        } else if (len == 0) {

            return 0;

        }

        if (socket.checkEOF()) {

            return -1;

        }

        // Read the available bytes at first.

        int remains = available();

        if (remains > 0) {

            int howmany = Math.min(remains, len);

            buffer.get(b, off, howmany);

            return howmany;

        }

        appDataIsAvailable = false;

        int volume = 0;

        try {

            /*

             * Read data if needed ... notice that the connection guarantees

             * that handshake, alert, and change cipher spec data streams are

             * handled as they arrive, so we never see them here.

             */

            while(volume == 0) {

                // Clear the buffer for a new record reading.

                buffer.clear();

                //

                // grow the buffer if needed

                //

                // Read the header of a record into the buffer, and return

                // the packet size.

                int packetLen = socket.bytesInCompletePacket();

                if (packetLen < 0) {    // EOF

                    return -1;

                }

                // Is this packet bigger than SSL/TLS normally allows?

                if (packetLen > SSLRecord.maxLargeRecordSize) {

                    throw new SSLProtocolException(

                        "Illegal packet size: " + packetLen);

                }

                if (packetLen > buffer.remaining()) {

                    buffer = ByteBuffer.allocate(packetLen);

                }

                volume = socket.readRecord(buffer);

                if (volume < 0) {    // EOF

                    return -1;

                } else if (volume > 0) {

                    appDataIsAvailable = true;

                    break;

                }

            }

            int howmany = Math.min(len, volume);

            buffer.get(b, off, howmany);

            return howmany;

        } catch (Exception e) {

            // shutdown and rethrow (wrapped) exception as appropriate

            socket.handleException(e);

            // dummy for compiler

            return -1;

        }

    }

    /**

     * Skip n bytes. This implementation is somewhat less efficient

     * than possible, but not badly so (redundant copy). We reuse

     * the read() code to keep things simpler. Note that SKIP_ARRAY

     * is static and may garbled by concurrent use, but we are not interested

     * in the data anyway.

     */

    @Override

    public synchronized long skip(long n) throws IOException {

        long skipped = 0;

        while (n > 0) {

            int len = (int)Math.min(n, SKIP_ARRAY.length);

            int r = read(SKIP_ARRAY, 0, len);

            if (r <= 0) {

                break;

            }

            n -= r;

            skipped += r;

        }

        return skipped;

    }

    /*

     * Socket close is already synchronized, no need to block here.

     */

    @Override

    public void close() throws IOException {

        socket.close();

    }

    // inherit default mark/reset behavior (throw Exceptions) from InputStream

}