/*

 * Copyright (c) 2013, 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.

 */

/*

 *

 *  (C) Copyright IBM Corp. 1999 All Rights Reserved.

 *  Copyright 1997 The Open Group Research Institute.  All rights reserved.

 */

package sun.security.krb5.internal.rcache;

import java.io.IOException;

import java.nio.BufferUnderflowException;

import java.nio.ByteBuffer;

import java.nio.ByteOrder;

import java.nio.channels.SeekableByteChannel;

import java.nio.charset.StandardCharsets;

import java.util.StringTokenizer;

/**

 * The class represents an old style replay cache entry. It is only used in

 * a dfl file.

 *

 * @author Sun/Oracle

 * @author Yanni Zhang

 */

public class AuthTime {

    final int ctime;

    final int cusec;

    final String client;

    final String server;

    /**

     * Constructs an <code>AuthTime</code>.

     */

    public AuthTime(String client, String server,

            int ctime, int cusec) {

        this.ctime = ctime;

        this.cusec = cusec;

        this.client = client;

        this.server = server;

    }

    @Override

    public String toString() {

        return String.format("%d/%06d/----/%s", ctime, cusec, client);

    }

    // Methods used when saved in a dfl file. See DflCache.java

    /**

     * Reads an LC style string from a channel, which is a int32 length

     * plus a UTF-8 encoded string possibly ends with \0.

     * @throws IOException if there is a format error

     * @throws BufferUnderflowException if goes beyond the end

     */

    private static String readStringWithLength(SeekableByteChannel chan)

            throws IOException {

        ByteBuffer bb = ByteBuffer.allocate(4);

        bb.order(ByteOrder.nativeOrder());

        chan.read(bb);

        bb.flip();

        int len = bb.getInt();

        if (len > 1024) {

            // Memory attack? The string should be fairly short.

            throw new IOException("Invalid string length");

        }

        bb = ByteBuffer.allocate(len);

        if (chan.read(bb) != len) {

            throw new IOException("Not enough string");

        }

        byte[] data = bb.array();

        return (data[len-1] == 0)?

                new String(data, 0, len-1, StandardCharsets.UTF_8):

                new String(data, StandardCharsets.UTF_8);

    }

    /**

     * Reads an AuthTime or AuthTimeWithHash object from a channel.

     * @throws IOException if there is a format error

     * @throws BufferUnderflowException if goes beyond the end

     */

    public static AuthTime readFrom(SeekableByteChannel chan)

            throws IOException {

        String client = readStringWithLength(chan);

        String server = readStringWithLength(chan);

        ByteBuffer bb = ByteBuffer.allocate(8);

        chan.read(bb);

        bb.order(ByteOrder.nativeOrder());

        int cusec = bb.getInt(0);

        int ctime = bb.getInt(4);

        if (client.isEmpty()) {

            StringTokenizer st = new StringTokenizer(server, " :");

            if (st.countTokens() != 6) {

                throw new IOException("Incorrect rcache style");

            }

            st.nextToken();

            String hash = st.nextToken();

            st.nextToken();

            client = st.nextToken();

            st.nextToken();

            server = st.nextToken();

            return new AuthTimeWithHash(

                    client, server, ctime, cusec, hash);

        } else {

            return new AuthTime(

                    client, server, ctime, cusec);

        }

    }

    /**

     * Encodes to be used in a dfl file

     */

    protected byte[] encode0(String cstring, String sstring) {

        byte[] c = cstring.getBytes(StandardCharsets.UTF_8);;

        byte[] s = sstring.getBytes(StandardCharsets.UTF_8);;

        byte[] zero = new byte[1];

        int len = 4 + c.length + 1 + 4 + s.length + 1 + 4 + 4;

        ByteBuffer bb = ByteBuffer.allocate(len)

                .order(ByteOrder.nativeOrder());

        bb.putInt(c.length+1).put(c).put(zero)

                .putInt(s.length+1).put(s).put(zero)

                .putInt(cusec).putInt(ctime);

        return bb.array();

    }

    /**

     * Encodes to be used in a dfl file

     * @param withHash useless here

     */

    public byte[] encode(boolean withHash) {

        return encode0(client, server);

    }

}