/* * Copyright (c) 1999, 2003, 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 javax.security.sasl; /** * Performs SASL authentication as a client. *<p> * A protocol library such as one for LDAP gets an instance of this * class in order to perform authentication defined by a specific SASL * mechanism. Invoking methods on the <tt>SaslClient</tt> instance * process challenges and create responses according to the SASL * mechanism implemented by the <tt>SaslClient</tt>. * As the authentication proceeds, the instance * encapsulates the state of a SASL client's authentication exchange. *<p> * Here's an example of how an LDAP library might use a <tt>SaslClient</tt>. * It first gets an instance of a <tt>SaslClient</tt>: *<blockquote><pre> * SaslClient sc = Sasl.createSaslClient(mechanisms, *     authorizationId, protocol, serverName, props, callbackHandler); *</pre></blockquote> * It can then proceed to use the client for authentication. * For example, an LDAP library might use the client as follows: *<blockquote><pre> * // Get initial response and send to server * byte[] response = (sc.hasInitialResponse() ? sc.evaluateChallenge(new byte[0]) : *     null); * LdapResult res = ldap.sendBindRequest(dn, sc.getName(), response); * while (!sc.isComplete() && *     (res.status == SASL_BIND_IN_PROGRESS || res.status == SUCCESS)) { *     response = sc.evaluateChallenge(res.getBytes()); *     if (res.status == SUCCESS) { *         // we're done; don't expect to send another BIND *         if (response != null) { *             throw new SaslException( *                 "Protocol error: attempting to send response after completion"); *         } *         break; *     } *     res = ldap.sendBindRequest(dn, sc.getName(), response); * } * if (sc.isComplete() && res.status == SUCCESS) { *    String qop = (String) sc.getNegotiatedProperty(Sasl.QOP); *    if (qop != null *        && (qop.equalsIgnoreCase("auth-int") *            || qop.equalsIgnoreCase("auth-conf"))) { * *      // Use SaslClient.wrap() and SaslClient.unwrap() for future *      // communication with server *      ldap.in = new SecureInputStream(sc, ldap.in); *      ldap.out = new SecureOutputStream(sc, ldap.out); *    } * } *</pre></blockquote> * * If the mechanism has an initial response, the library invokes * <tt>evaluateChallenge()</tt> with an empty * challenge and to get initial response. * Protocols such as IMAP4, which do not include an initial response with * their first authentication command to the server, initiates the * authentication without first calling <tt>hasInitialResponse()</tt> * or <tt>evaluateChallenge()</tt>. * When the server responds to the command, it sends an initial challenge. * For a SASL mechanism in which the client sends data first, the server should * have issued a challenge with no data. This will then result in a call * (on the client) to <tt>evaluateChallenge()</tt> with an empty challenge. * * @since 1.5 * * @see Sasl * @see SaslClientFactory * * @author Rosanna Lee * @author Rob Weltman */public abstract interface SaslClient {     /**     * Returns the IANA-registered mechanism name of this SASL client.     * (e.g. "CRAM-MD5", "GSSAPI").     * @return A non-null string representing the IANA-registered mechanism name.     */    public abstract String getMechanismName();     /**     * Determines whether this mechanism has an optional initial response.     * If true, caller should call <tt>evaluateChallenge()</tt> with an     * empty array to get the initial response.     *     * @return true if this mechanism has an initial response.     */    public abstract boolean hasInitialResponse();     /**     * Evaluates the challenge data and generates a response.     * If a challenge is received from the server during the authentication     * process, this method is called to prepare an appropriate next     * response to submit to the server.     *     * @param challenge The non-null challenge sent from the server.     * The challenge array may have zero length.     *     * @return The possibly null reponse to send to the server.     * It is null if the challenge accompanied a "SUCCESS" status and the challenge     * only contains data for the client to update its state and no response     * needs to be sent to the server. The response is a zero-length byte     * array if the client is to send a response with no data.     * @exception SaslException If an error occurred while processing     * the challenge or generating a response.     */    public abstract byte[] evaluateChallenge(byte[] challenge)        throws SaslException;     /**      * Determines whether the authentication exchange has completed.      * This method may be called at any time, but typically, it      * will not be called until the caller has received indication      * from the server      * (in a protocol-specific manner) that the exchange has completed.      *      * @return true if the authentication exchange has completed; false otherwise.      */    public abstract boolean isComplete();     /**     * Unwraps a byte array received from the server.     * This method can be called only after the authentication exchange has     * completed (i.e., when <tt>isComplete()</tt> returns true) and only if     * the authentication exchange has negotiated integrity and/or privacy     * as the quality of protection; otherwise, an     * <tt>IllegalStateException</tt> is thrown.     *<p>     * <tt>incoming</tt> is the contents of the SASL buffer as defined in RFC 2222     * without the leading four octet field that represents the length.     * <tt>offset</tt> and <tt>len</tt> specify the portion of <tt>incoming</tt>     * to use.     *     * @param incoming A non-null byte array containing the encoded bytes     *                from the server.     * @param offset The starting position at <tt>incoming</tt> of the bytes to use.     * @param len The number of bytes from <tt>incoming</tt> to use.     * @return A non-null byte array containing the decoded bytes.     * @exception SaslException if <tt>incoming</tt> cannot be successfully     * unwrapped.     * @exception IllegalStateException if the authentication exchange has     * not completed, or  if the negotiated quality of protection     * has neither integrity nor privacy.     */    public abstract byte[] unwrap(byte[] incoming, int offset, int len)        throws SaslException;     /**     * Wraps a byte array to be sent to the server.     * This method can be called only after the authentication exchange has     * completed (i.e., when <tt>isComplete()</tt> returns true) and only if     * the authentication exchange has negotiated integrity and/or privacy     * as the quality of protection; otherwise, an     * <tt>IllegalStateException</tt> is thrown.     *<p>     * The result of this method will make up the contents of the SASL buffer     * as defined in RFC 2222 without the leading four octet field that     * represents the length.     * <tt>offset</tt> and <tt>len</tt> specify the portion of <tt>outgoing</tt>     * to use.     *     * @param outgoing A non-null byte array containing the bytes to encode.     * @param offset The starting position at <tt>outgoing</tt> of the bytes to use.     * @param len The number of bytes from <tt>outgoing</tt> to use.     * @return A non-null byte array containing the encoded bytes.     * @exception SaslException if <tt>outgoing</tt> cannot be successfully     * wrapped.     * @exception IllegalStateException if the authentication exchange has     * not completed, or if the negotiated quality of protection     * has neither integrity nor privacy.     */    public abstract byte[] wrap(byte[] outgoing, int offset, int len)        throws SaslException;     /**     * 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, an     * <tt>IllegalStateException</tt> is thrown.     *     * @param propName The non-null property name.     * @return The value of the negotiated property. If null, the property was     * not negotiated or is not applicable to this mechanism.     * @exception IllegalStateException if this authentication exchange     * has not completed     */     public abstract Object getNegotiatedProperty(String propName);      /**      * Disposes of any system resources or security-sensitive information      * the SaslClient might be using. Invoking this method invalidates      * the SaslClient instance. This method is idempotent.      * @throws SaslException If a problem was encountered while disposing      * the resources.      */    public abstract void dispose() throws SaslException;}