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/*
 * Copyright (c) 2016, 2020, Oracle and/or its affiliates.
 *
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License, version 2.0, as published by the
 * Free Software Foundation.
 *
 * This program is also distributed with certain software (including but not
 * limited to OpenSSL) that is licensed under separate terms, as designated in a
 * particular file or component or in included license documentation. The
 * authors of MySQL hereby grant you an additional permission to link the
 * program and your derivative works with the separately licensed software that
 * they have included with MySQL.
 *
 * Without limiting anything contained in the foregoing, this file, which is
 * part of MySQL Connector/J, is also subject to the Universal FOSS Exception,
 * version 1.0, a copy of which can be found at
 * http://oss.oracle.com/licenses/universal-foss-exception.
 *
 * This program 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 2.0,
 * for more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
 */

package com.mysql.cj.protocol.a;

import java.nio.ByteBuffer;

import com.mysql.cj.protocol.MessageHeader;

/**
 * Represents the legacy protocol packet header, consisting of
 * 3-bytes payload_length and 1-byte sequence_id.
 * 
 * see http://dev.mysql.com/doc/internals/en/mysql-packet.html
 */
public class NativePacketHeader implements MessageHeader {

    protected ByteBuffer packetHeaderBuf;

    public NativePacketHeader() {
        this.packetHeaderBuf = ByteBuffer.allocate(4);
    }

    public NativePacketHeader(byte[] buf) {
        this.packetHeaderBuf = ByteBuffer.wrap(buf);
    }

    public ByteBuffer getBuffer() {
        return this.packetHeaderBuf;
    }

    @Override
    public int getMessageSize() {
        return (this.packetHeaderBuf.array()[0] & 0xff) + ((this.packetHeaderBuf.array()[1] & 0xff) << 8) + ((this.packetHeaderBuf.array()[2] & 0xff) << 16);
    }

    @Override
    public byte getMessageSequence() {
        return this.packetHeaderBuf.array()[3];
    }
}