/*

 * Copyright (c) 1996, 2018, 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

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package sun.security.ssl;

import java.security.SecureRandom;

import java.util.Arrays;

import javax.net.ssl.SSLProtocolException;

/**

 * Encapsulates an SSL session ID.

 *

 * @author Satish Dharmaraj

 * @author David Brownell

 */

final class SessionId {

    private static final int MAX_LENGTH = 32;

    private final byte[] sessionId;          // max 32 bytes

    // Constructs a new session ID ... perhaps for a rejoinable session

    SessionId(boolean isRejoinable, SecureRandom generator) {

        if (isRejoinable && (generator != null)) {

            sessionId = new RandomCookie(generator).randomBytes;

        } else {

            sessionId = new byte[0];

        }

    }

    // Constructs a session ID from a byte array (max size 32 bytes)

    SessionId(byte[] sessionId) {

        this.sessionId = sessionId.clone();

    }

    // Returns the length of the ID, in bytes

    int length() {

        return sessionId.length;

    }

    // Returns the bytes in the ID.  May be an empty array.

    byte[] getId() {

        return sessionId.clone();

    }

    // Returns the ID as a string

    @Override

    public String toString() {

        if (sessionId.length == 0) {

            return "";

        }

        return Utilities.toHexString(sessionId);

    }

    // Returns a value which is the same for session IDs which are equal

    @Override

    public int hashCode() {

        return Arrays.hashCode(sessionId);

    }

    // Returns true if the parameter is the same session ID

    @Override

    public boolean equals (Object obj) {

        if (obj == this) {

            return true;

        }

        if (obj instanceof SessionId) {

            SessionId that = (SessionId)obj;

            return Arrays.equals(this.sessionId, that.sessionId);

        }

        return false;

    }

    /**

     * Checks the length of the session ID to make sure it sits within

     * the range called out in the specification

     */

    void checkLength(int protocolVersion) throws SSLProtocolException {

        // As of today all versions of TLS have a 32-byte maximum length.

        // In the future we can do more here to support protocol versions

        // that may have longer max lengths.

        if (sessionId.length > MAX_LENGTH) {

            throw new SSLProtocolException("Invalid session ID length (" +

                    sessionId.length + " bytes)");

        }

    }

}