/* * Copyright (c) 1999, 2003, Oracle and/or its affiliates. All rights reserved. * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. * * * * * * * * * * * * * * * * * * * * */ package javax.security.sasl; /** * Performs SASL authentication as a client. *

* 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 SaslClient instance * process challenges and create responses according to the SASL * mechanism implemented by the SaslClient. * As the authentication proceeds, the instance * encapsulates the state of a SASL client's authentication exchange. *

* Here's an example of how an LDAP library might use a SaslClient. * It first gets an instance of a SaslClient: *

 * SaslClient sc = Sasl.createSaslClient(mechanisms,
 *     authorizationId, protocol, serverName, props, callbackHandler);
 *
* It can then proceed to use the client for authentication. * For example, an LDAP library might use the client as follows: *
 * // 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);
 *    }
 * }
 *
* * If the mechanism has an initial response, the library invokes * evaluateChallenge() 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 hasInitialResponse() * or evaluateChallenge(). * 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 evaluateChallenge() 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 evaluateChallenge() 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 isComplete() returns true) and only if * the authentication exchange has negotiated integrity and/or privacy * as the quality of protection; otherwise, an * IllegalStateException is thrown. *

* incoming is the contents of the SASL buffer as defined in RFC 2222 * without the leading four octet field that represents the length. * offset and len specify the portion of incoming * to use. * * @param incoming A non-null byte array containing the encoded bytes * from the server. * @param offset The starting position at incoming of the bytes to use. * @param len The number of bytes from incoming to use. * @return A non-null byte array containing the decoded bytes. * @exception SaslException if incoming 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 isComplete() returns true) and only if * the authentication exchange has negotiated integrity and/or privacy * as the quality of protection; otherwise, an * IllegalStateException is thrown. *

* 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. * offset and len specify the portion of outgoing * to use. * * @param outgoing A non-null byte array containing the bytes to encode. * @param offset The starting position at outgoing of the bytes to use. * @param len The number of bytes from outgoing to use. * @return A non-null byte array containing the encoded bytes. * @exception SaslException if outgoing 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 isComplete() returns true); otherwise, an * IllegalStateException 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; }