/*

 * Copyright (c) 1999, 2010, 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 com.sun.security.sasl;

import javax.security.sasl.*;

/**

  * Implements the EXTERNAL SASL client mechanism.

  * (<A HREF="http://www.ietf.org/rfc/rfc2222.txt">RFC 2222</A>).

  * The EXTERNAL mechanism returns the optional authorization ID as

  * the initial response. It processes no challenges.

  *

  * @author Rosanna Lee

  */

final class ExternalClient implements SaslClient {

    private byte[] username;

    private boolean completed = false;

    /**

     * Constructs an External mechanism with optional authorization ID.

     *

     * @param authorizationID If non-null, used to specify authorization ID.

     * @throws SaslException if cannot convert authorizationID into UTF-8

     *     representation.

     */

    ExternalClient(String authorizationID) throws SaslException {

        if (authorizationID != null) {

            try {

                username = authorizationID.getBytes("UTF8");

            } catch (java.io.UnsupportedEncodingException e) {

                throw new SaslException("Cannot convert " + authorizationID +

                    " into UTF-8", e);

            }

        } else {

            username = new byte[0];

        }

    }

    /**

     * Retrieves this mechanism's name for initiating the "EXTERNAL" protocol

     * exchange.

     *

     * @return  The string "EXTERNAL".

     */

    public String getMechanismName() {

        return "EXTERNAL";

    }

    /**

     * This mechanism has an initial response.

     */

    public boolean hasInitialResponse() {

        return true;

    }

    public void dispose() throws SaslException {

    }

    /**

     * Processes the challenge data.

     * It returns the EXTERNAL mechanism's initial response,

     * which is the authorization id encoded in UTF-8.

     * This is the optional information that is sent along with the SASL command.

     * After this method is called, isComplete() returns true.

     *

     * @param challengeData Ignored.

     * @return The possible empty initial response.

     * @throws SaslException If authentication has already been called.

     */

    public byte[] evaluateChallenge(byte[] challengeData)

        throws SaslException {

        if (completed) {

            throw new IllegalStateException(

                "EXTERNAL authentication already completed");

        }

        completed = true;

        return username;

    }

    /**

     * Returns whether this mechanism is complete.

     * @return true if initial response has been sent; 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("EXTERNAL has no supported QOP");

        } else {

            throw new IllegalStateException(

                "EXTERNAL 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("EXTERNAL has no supported QOP");

        } else {

            throw new IllegalStateException(

                "EXTERNAL authentication not completed");

        }

    }

    /**

     * Retrieves the negotiated property.

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

     * completed (i.e., when {@code isComplete()} returns true);

     * otherwise, an {@code IllegalStateException} is thrown.

     *

     * @return null No property is applicable to this mechanism.

     * @exception IllegalStateException if this authentication exchange

     * has not completed

     */

    public Object getNegotiatedProperty(String propName) {

        if (completed) {

            return null;

        } else {

            throw new IllegalStateException(

                "EXTERNAL authentication not completed");

        }

    }

}