/*
 * Copyright (c) 2018 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package com.sun.jndi.ldap.ext;

import java.io.IOException;

import javax.naming.ldap.ExtendedResponse;

/**
 * This class implements the LDAPv3 Extended Response for WhoAmI.
 * The <tt>WhoAmIRequest</tt> and <tt>WhoAmIResponse</tt> are used to
 * obtain the current authorization identity of the user.
 * WhoAmI extended operation allows users to get authorization identity
 * seperately from LDAP bind operation, unlike {@link com.sun.jndi.ldap.ctl.AuthorizationIDControl <tt>AuthorizationIDControl</tt>}
 * which has to be used with LDAP bind operation.
 *
 * <p>
 * The WhoAmI LDAP extended operation is defined in <a href="http://www.ietf.org/internet-drafts/draft-zeilenga-ldap-authzid-08.txt">draft-zeilenga-ldap-authzid-08</a>.
 * <p>
 * The object identifier used by WhoAmI extended operation is
 * 2.16.840.1.113730.3.4.15 and the extended response value is the user
 * authorization identity.
 * <p>
 * The extended response's value has the following ASN.1 definition:
 * <pre>
 *
 *     AuthzId ::= LDAPString ; containing an authzId as defined in RFC 2829
 *                            ; or an empty value
 *
 *     authzId    = dnAuthzId / uAuthzId
 *
 *     ; distinguished-name-based authz id.
 *     dnAuthzId  = "dn:" dn
 *     dn         = utf8string    ; with syntax defined in RFC 2253
 *
 *     ; unspecified userid, UTF-8 encoded.
 *     uAuthzId   = "u:" userid
 *     userid     = utf8string    ; syntax unspecified
 *
 * </pre>
 * <p>
 * The following code sample shows how the extended operation may be used:
 * <pre>
 *
 *     // create an initial context using the supplied environment properties
 *     LdapContext ctx = new InitialLdapContext(env, null);
 *
 *     // perform the extended operation
 *     WhoAmIResponse whoAmI =
 *         (WhoAmIResponse) ctx.extendedOperation(new WhoAmIRequest());
 *
 *     System.out.println("I am <" + whoAmI.getAuthorizationID() + ">");
 *
 * </pre>
 * @see WhoAmIRequest
 * @see com.sun.jndi.ldap.ctl.AuthorizationIDControl
 * @author Vincent Ryan
 */

public class WhoAmIResponse implements ExtendedResponse {

    /**
     * The WhoAmI extended response's assigned object identifier
     * is 1.3.6.1.4.1.4203.1.11.3.
     */
    public static final String OID = "1.3.6.1.4.1.4203.1.11.3";

    /**
     * Authorization identity of the bound user
     * @serial
     */
    private String authzId;

    /**
     * The ASN1 encoded value of the extended response
     * @serial
     */
    private byte[] value;

    private static final long serialVersionUID = 4095032263256625777L;

    /**
     * Constructs a WhoAmI extended response.
     */
    WhoAmIResponse(String id, byte[] value, int offset, int length)
        throws IOException {

        this.value = value;

        // decode value
        if ((value != null) && (value.length > 0)) {
            authzId = new String(value, offset, length, "UTF8");
        }
    }

    /**
     * Retrieves the WhoAmI response's object identifier string.
     *
     * @return The non-null object identifier string.
     */
    @Override
    public String getID() {
        return OID;
    }

    /**
     * Retrieves the WhoAmI response's ASN.1 BER encoded value.
     *
     * @return A possibly null byte array representing the ASN.1 BER
     *            encoded value of the LDAP extended response.
     */
    @Override
    public byte[] getEncodedValue() {
        if (value == null) {
            return null;
        }

        // return a copy of value
        byte[] retval = new byte[value.length];
        System.arraycopy(value, 0, retval, 0, value.length);
        return retval;
    }

    /**
     * Retrieves the authorization identity.
     *
     * @return The authorization identity. An empty string is returned
     * when anonymous authentication is used.
     */
    public String getAuthorizationID() {
        if (authzId == null) {
            return "";
        }
        return authzId;
    }
}