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/* * @(#)SaslClient.java 1.15 05/11/17 * * Copyright 2006 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ 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; }