/*

 * Copyright 2000-2006 Sun Microsystems, Inc.  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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package com.sun.security.sasl;

import javax.security.sasl.*;

/**

  * Implements the PLAIN SASL client mechanism.

  * (<A

  * HREF="http://ftp.isi.edu/in-notes/rfc2595.txt">RFC 2595</A>)

  *

  * @author Rosanna Lee

  */

final class PlainClient implements SaslClient {

    private boolean completed = false;

    private byte[] pw;

    private String authorizationID;

    private String authenticationID;

    private static byte SEP = 0; // US-ASCII <NUL>

    /**

     * Creates a SASL mechanism with client credentials that it needs

     * to participate in Plain authentication exchange with the server.

     *

     * @param authorizationID A possibly null string representing the principal

     *  for which authorization is being granted; if null, same as

     *  authenticationID

     * @param authenticationID A non-null string representing the principal

     * being authenticated. pw is associated with with this principal.

     * @param pw A non-null byte[] containing the password.

     */

    PlainClient(String authorizationID, String authenticationID, byte[] pw)

    throws SaslException {

        if (authenticationID == null || pw == null) {

            throw new SaslException(

                "PLAIN: authorization ID and password must be specified");

        }

        this.authorizationID = authorizationID;

        this.authenticationID = authenticationID;

        this.pw = pw;  // caller should have already cloned

    }

    /**

     * Retrieves this mechanism's name for to initiate the PLAIN protocol

     * exchange.

     *

     * @return  The string "PLAIN".

     */

    public String getMechanismName() {

        return "PLAIN";

    }

    public boolean hasInitialResponse() {

        return true;

    }

    public void dispose() throws SaslException {

        clearPassword();

    }

    /**

     * Retrieves the initial response for the SASL command, which for

     * PLAIN is the concatenation of authorization ID, authentication ID

     * and password, with each component separated by the US-ASCII <NUL> byte.

     *

     * @param challengeData Ignored

     * @return A non-null byte array containing the response to be sent to the server.

     * @throws SaslException If cannot encode ids in UTF-8

     * @throw IllegalStateException if authentication already completed

     */

    public byte[] evaluateChallenge(byte[] challengeData) throws SaslException {

        if (completed) {

            throw new IllegalStateException(

                "PLAIN authentication already completed");

        }

        completed = true;

        try {

            byte[] authz = (authorizationID != null)?

                authorizationID.getBytes("UTF8") :

                null;

            byte[] auth = authenticationID.getBytes("UTF8");

            byte[] answer = new byte[pw.length + auth.length + 2 +

                (authz == null ? 0 : authz.length)];

            int pos = 0;

            if (authz != null) {

                System.arraycopy(authz, 0, answer, 0, authz.length);

                pos = authz.length;

            }

            answer[pos++] = SEP;

            System.arraycopy(auth, 0, answer, pos, auth.length);

            pos += auth.length;

            answer[pos++] = SEP;

            System.arraycopy(pw, 0, answer, pos, pw.length);

            clearPassword();

            return answer;

        } catch (java.io.UnsupportedEncodingException e) {

            throw new SaslException("Cannot get UTF-8 encoding of ids", e);

        }

    }

    /**

     * Determines whether this mechanism has completed.

     * Plain completes after returning one response.

     *

     * @return true if has completed; false otherwise;

     */

    public boolean isComplete() {

        return completed;

    }

    /**

      * Unwraps the incoming buffer.

      *

      * @throws SaslException Not applicable to this mechanism.

      */

    public byte[] unwrap(byte[] incoming, int offset, int len)

        throws SaslException {

        if (completed) {

            throw new SaslException(

                "PLAIN supports neither integrity nor privacy");

        } else {

            throw new IllegalStateException("PLAIN authentication not completed");

        }

    }

    /**

      * Wraps the outgoing buffer.

      *

      * @throws SaslException Not applicable to this mechanism.

      */

    public byte[] wrap(byte[] outgoing, int offset, int len) throws SaslException {

        if (completed) {

            throw new SaslException(

                "PLAIN supports neither integrity nor privacy");

        } else {

            throw new IllegalStateException("PLAIN authentication not completed");

        }

    }

    /**

     * Retrieves the negotiated property.

     * This method can be called only after the authentication exchange has

     * completed (i.e., when <tt>isComplete()</tt> returns true); otherwise, a

     * <tt>SaslException</tt> is thrown.

     *

     * @return value of property; only QOP is applicable to PLAIN.

     * @exception IllegalStateException if this authentication exchange

     *     has not completed

     */

    public Object getNegotiatedProperty(String propName) {

        if (completed) {

            if (propName.equals(Sasl.QOP)) {

                return "auth";

            } else {

                return null;

            }

        } else {

            throw new IllegalStateException("PLAIN authentication not completed");

        }

    }

    private void clearPassword() {

        if (pw != null) {

            // zero out password

            for (int i = 0; i < pw.length; i++) {

                pw[i] = (byte)0;

            }

            pw = null;

        }

    }

    protected void finalize() {

        clearPassword();

    }

}