/* jcifs smb client library in Java
 * Copyright (C) 2002  "Michael B. Allen" <jcifs at samba dot org>
 *                   "Eric Glass" <jcifs at samba dot org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package jcifs.ntlmssp;

import jcifs.Config;

/**
 * Abstract superclass for all NTLMSSP messages.
 */
public abstract class NtlmMessage implements NtlmFlags {

    /**
     * The NTLMSSP "preamble".
     */
    protected static final byte[] NTLMSSP_SIGNATURE = new byte[] {
        (byte) 'N', (byte) 'T', (byte) 'L', (byte) 'M',
        (byte) 'S', (byte) 'S', (byte) 'P', (byte) 0
    };

    private static final String OEM_ENCODING = Config.DEFAULT_OEM_ENCODING;
    protected static final String UNI_ENCODING = "UTF-16LE";

    private int flags;

    /**
     * Returns the flags currently in use for this message.
     *
     * @return An <code>int</code> containing the flags in use for this
     * message.
     */
    public int getFlags() {
        return flags;
    }

    /**
     * Sets the flags for this message.
     *
     * @param flags The flags for this message.
     */
    public void setFlags(int flags) {
        this.flags = flags;
    }

    /**
     * Returns the status of the specified flag.
     *
     * @param flag The flag to test (i.e., <code>NTLMSSP_NEGOTIATE_OEM</code>).
     * @return A <code>boolean</code> indicating whether the flag is set.
     */
    public boolean getFlag(int flag) {
        return (getFlags() & flag) != 0;
    }

    /**
     * Sets or clears the specified flag.
     * 
     * @param flag The flag to set/clear (i.e.,
     * <code>NTLMSSP_NEGOTIATE_OEM</code>).
     * @param value Indicates whether to set (<code>true</code>) or
     * clear (<code>false</code>) the specified flag.
     */
    public void setFlag(int flag, boolean value) {
        setFlags(value ? (getFlags() | flag) :
                (getFlags() & (0xffffffff ^ flag)));
    }

    static int readULong(byte[] src, int index) {
        return (src[index] & 0xff) |
                ((src[index + 1] & 0xff) << 8) |
                ((src[index + 2] & 0xff) << 16) |
                ((src[index + 3] & 0xff) << 24);
    }

    static int readUShort(byte[] src, int index) {
        return (src[index] & 0xff) | ((src[index + 1] & 0xff) << 8);
    }

    static byte[] readSecurityBuffer(byte[] src, int index) {
        int length = readUShort(src, index);
        int offset = readULong(src, index + 4);
        byte[] buffer = new byte[length];
        System.arraycopy(src, offset, buffer, 0, length);
        return buffer;
    }

    static void writeULong(byte[] dest, int offset, int ulong) {
        dest[offset] = (byte) (ulong & 0xff);
        dest[offset + 1] = (byte) (ulong >> 8 & 0xff);
        dest[offset + 2] = (byte) (ulong >> 16 & 0xff);
        dest[offset + 3] = (byte) (ulong >> 24 & 0xff);
    }

    static void writeUShort(byte[] dest, int offset, int ushort) {
        dest[offset] = (byte) (ushort & 0xff);
        dest[offset + 1] = (byte) (ushort >> 8 & 0xff);
    }

    static void writeSecurityBuffer(byte[] dest, int offset, int bodyOffset,
            byte[] src) {
        int length = (src != null) ? src.length : 0;
        if (length == 0) return;
        writeUShort(dest, offset, length);
        writeUShort(dest, offset + 2, length);
        writeULong(dest, offset + 4, bodyOffset);
        System.arraycopy(src, 0, dest, bodyOffset, length);
    }

    static String getOEMEncoding() {
        return OEM_ENCODING;
    }

    /**
     * Returns the raw byte representation of this message.
     *
     * @return A <code>byte[]</code> containing the raw message material.
     */
    public abstract byte[] toByteArray();

}