/*
 * Copyright (c) 1996, 2012, 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.security.SecureRandom;
import javax.net.ssl.SSLProtocolException;

Encapsulates an SSL session ID.  SSL Session IDs are not reused by
servers during the lifetime of any sessions it created.  Sessions may
be used by many connections, either concurrently (for example, two
connections to a web server at the same time) or sequentially (over as
long a time period as is allowed by a given server).
Author:
Satish Dharmaraj, David Brownell/**
 * Encapsulates an SSL session ID.  SSL Session IDs are not reused by
 * servers during the lifetime of any sessions it created.  Sessions may
 * be used by many connections, either concurrently (for example, two
 * connections to a web server at the same time) or sequentially (over as
 * long a time period as is allowed by a given server).
 *
 * @author Satish Dharmaraj
 * @author David Brownell
 */
final
class SessionId
{
    static int MAX_LENGTH = 32;
    private byte[] sessionId;          // max 32 bytes

    
Constructs a new session ID ... perhaps for a rejoinable session /** Constructs a new session ID ... perhaps for a rejoinable session */
    SessionId (boolean isRejoinable, SecureRandom generator)
    {
        if (isRejoinable)
            // this will be unique, it's a timestamp plus much randomness
            sessionId = new RandomCookie (generator).random_bytes;
        else
            sessionId = new byte [0];
    }

    
Constructs a session ID from a byte array (max size 32 bytes) /** Constructs a session ID from a byte array (max size 32 bytes) */
    SessionId (byte[] sessionId)
        { this.sessionId = sessionId; }

    
Returns the length of the ID, in bytes /** Returns the length of the ID, in bytes */
    int length ()
        { return sessionId.length; }

    
Returns the bytes in the ID.  May be an empty array.  /** Returns the bytes in the ID.  May be an empty array.  */
    byte[] getId ()
    {
        return sessionId.clone ();
    }

    
Returns the ID as a string /** Returns the ID as a string */
    @Override
    public String toString ()
    {
        int             len = sessionId.length;
        StringBuilder    sb = new StringBuilder (10 + 2 * len);

        sb.append("{");
        for (int i = 0; i < len; i++) {
            sb.append(0x0ff & sessionId[i]);
            if (i != (len - 1))
                sb.append (", ");
        }
        sb.append("}");
        return sb.toString ();
    }


    
Returns a value which is the same for session IDs which are equal /** Returns a value which is the same for session IDs which are equal */
    @Override
    public int hashCode ()
    {
        int     retval = 0;

        for (int i = 0; i < sessionId.length; i++)
            retval += sessionId [i];
        return retval;
    }

    
Returns true if the parameter is the same session ID /** Returns true if the parameter is the same session ID */
    @Override
    public boolean equals (Object obj)
    {
        if (!(obj instanceof SessionId))
            return false;

        SessionId s = (SessionId) obj;
        byte[] b = s.getId ();

        if (b.length != sessionId.length)
            return false;
        for (int i = 0; i < sessionId.length; i++) {
            if (b [i] != sessionId [i])
                return false;
        }
        return true;
    }

    
Checks the length of the session ID to make sure it sits within
the range called out in the specification
/**
     * Checks the length of the session ID to make sure it sits within
     * the range called out in the specification
     */
    void checkLength(ProtocolVersion pv) 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)");
        }
    }

}