/*

 * 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.ByteArrayInputStream;

import java.io.IOException;

import java.nio.ByteBuffer;

import javax.net.ssl.SSLException;

/**

 * InputStream for handshake data, used internally only. Contains the

 * handshake message buffer and methods to parse them.

 *

 * Once a new handshake record arrives, it is buffered in this class until

 * processed by the Handshaker. The buffer may also contain incomplete

 * handshake messages in case the message is split across multiple records.

 * Handshaker.processRecord deals with all that. It may also contain

 * handshake messages larger than the default buffer size (e.g. large

 * certificate messages). The buffer is grown dynamically to handle that.

 *

 * Note that this class only handles Handshake messages in TLS format.

 * DTLS Handshake messages should be converted into TLS format before

 * calling into this method.

 *

 * @author David Brownell

 */

// This class is used to handle plain text handshake messages.

//

public final class HandshakeInStream extends ByteArrayInputStream {

    /*

     * Construct the stream; we'll be accumulating hashes of the

     * input records using two sets of digests.

     */

    HandshakeInStream() {

        super(new byte[0]);     // lazy to alloacte the internal buffer

    }

    //

    // overridden ByteArrayInputStream methods

    //

    @Override

    public int read(byte[] b) throws IOException {

        if (super.read(b) != b.length) {

            throw new SSLException("Unexpected end of handshake data");

        }

        return b.length;

    }

    //

    // handshake input stream management functions

    //

    /*

     * Here's an incoming record with handshake data.  Queue the contents;

     * it might be one or more entire messages, complete a message that's

     * partly queued, or both.

     */

    void incomingRecord(ByteBuffer in) throws IOException {

        int len;

        // Move any unread data to the front of the buffer.

        if (pos != 0) {

            len = count - pos;

            if (len != 0) {

                System.arraycopy(buf, pos, buf, 0, len);

            }

            pos = 0;

            count = len;

        }

        // Grow buffer if needed.

        len = in.remaining() + count;

        if (buf.length < len) {

            byte[] newbuf = new byte[len];

            if (count != 0) {

                System.arraycopy(buf, 0, newbuf, 0, count);

            }

            buf = newbuf;

        }

        // Append the incoming record to the buffer

        in.get(buf, count, in.remaining());

        count = len;

    }

    //

    // Message parsing methods

    //

    /*

     * Read 8, 16, 24, and 32 bit SSL integer data types, encoded

     * in standard big-endian form.

     */

    int getInt8() throws IOException {

        verifyLength(1);

        return read();

    }

    int getInt16() throws IOException {

        verifyLength(2);

        return (getInt8() << 8) | getInt8();

    }

    int getInt24() throws IOException {

        verifyLength(3);

        return (getInt8() << 16) | (getInt8() << 8) | getInt8();

    }

    int getInt32() throws IOException {

        verifyLength(4);

        return (getInt8() << 24) | (getInt8() << 16)

             | (getInt8() << 8) | getInt8();

    }

    /*

     * Read byte vectors with 8, 16, and 24 bit length encodings.

     */

    byte[] getBytes8() throws IOException {

        int len = getInt8();

        verifyLength(len);

        byte[] b = new byte[len];

        read(b);

        return b;

    }

    public byte[] getBytes16() throws IOException {

        int len = getInt16();

        verifyLength(len);

        byte[] b = new byte[len];

        read(b);

        return b;

    }

    byte[] getBytes24() throws IOException {

        int len = getInt24();

        verifyLength(len);

        byte[] b = new byte[len];

        read(b);

        return b;

    }

    // Is a length greater than available bytes in the record?

    private void verifyLength(int len) throws SSLException {

        if (len > available()) {

            throw new SSLException("Unexpected end of handshake data");

        }

    }

}