/* |
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* Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. Oracle designates this |
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* particular file as subject to the "Classpath" exception as provided |
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* by Oracle in the LICENSE file that accompanied this code. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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*/ |
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package javax.security.sasl; |
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/** |
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* Performs SASL authentication as a client. |
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*<p> |
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* A protocol library such as one for LDAP gets an instance of this |
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* class in order to perform authentication defined by a specific SASL |
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* mechanism. Invoking methods on the {@code SaslClient} instance |
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* process challenges and create responses according to the SASL |
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* mechanism implemented by the {@code SaslClient}. |
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* As the authentication proceeds, the instance |
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* encapsulates the state of a SASL client's authentication exchange. |
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*<p> |
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* Here's an example of how an LDAP library might use a {@code SaslClient}. |
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* It first gets an instance of a {@code SaslClient}: |
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*<blockquote><pre>{@code |
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* SaslClient sc = Sasl.createSaslClient(mechanisms, |
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* authorizationId, protocol, serverName, props, callbackHandler); |
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*}</pre></blockquote> |
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* It can then proceed to use the client for authentication. |
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* For example, an LDAP library might use the client as follows: |
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*<blockquote><pre>{@code |
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* // Get initial response and send to server |
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* byte[] response = (sc.hasInitialResponse() ? sc.evaluateChallenge(new byte[0]) : |
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* null); |
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* LdapResult res = ldap.sendBindRequest(dn, sc.getName(), response); |
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* while (!sc.isComplete() && |
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* (res.status == SASL_BIND_IN_PROGRESS || res.status == SUCCESS)) { |
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* response = sc.evaluateChallenge(res.getBytes()); |
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* if (res.status == SUCCESS) { |
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* // we're done; don't expect to send another BIND |
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* if (response != null) { |
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* throw new SaslException( |
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* "Protocol error: attempting to send response after completion"); |
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* } |
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* break; |
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* } |
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* res = ldap.sendBindRequest(dn, sc.getName(), response); |
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* } |
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* if (sc.isComplete() && res.status == SUCCESS) { |
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* String qop = (String) sc.getNegotiatedProperty(Sasl.QOP); |
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* if (qop != null |
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* && (qop.equalsIgnoreCase("auth-int") |
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* || qop.equalsIgnoreCase("auth-conf"))) { |
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* |
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* // Use SaslClient.wrap() and SaslClient.unwrap() for future |
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* // communication with server |
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* ldap.in = new SecureInputStream(sc, ldap.in); |
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* ldap.out = new SecureOutputStream(sc, ldap.out); |
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* } |
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* } |
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*}</pre></blockquote> |
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* |
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* If the mechanism has an initial response, the library invokes |
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* {@code evaluateChallenge()} with an empty |
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* challenge and to get initial response. |
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* Protocols such as IMAP4, which do not include an initial response with |
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* their first authentication command to the server, initiates the |
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* authentication without first calling {@code hasInitialResponse()} |
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* or {@code evaluateChallenge()}. |
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* When the server responds to the command, it sends an initial challenge. |
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* For a SASL mechanism in which the client sends data first, the server should |
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* have issued a challenge with no data. This will then result in a call |
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* (on the client) to {@code evaluateChallenge()} with an empty challenge. |
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* |
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* @since 1.5 |
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* |
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* @see Sasl |
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* @see SaslClientFactory |
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* |
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* @author Rosanna Lee |
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* @author Rob Weltman |
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*/ |
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public abstract interface SaslClient { |
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/** |
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* Returns the IANA-registered mechanism name of this SASL client. |
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* (e.g. "CRAM-MD5", "GSSAPI"). |
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* @return A non-null string representing the IANA-registered mechanism name. |
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*/ |
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public abstract String getMechanismName(); |
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/** |
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* Determines whether this mechanism has an optional initial response. |
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* If true, caller should call {@code evaluateChallenge()} with an |
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* empty array to get the initial response. |
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* |
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* @return true if this mechanism has an initial response. |
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*/ |
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public abstract boolean hasInitialResponse(); |
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/** |
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* Evaluates the challenge data and generates a response. |
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* If a challenge is received from the server during the authentication |
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* process, this method is called to prepare an appropriate next |
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* response to submit to the server. |
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* |
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* @param challenge The non-null challenge sent from the server. |
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* The challenge array may have zero length. |
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* |
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* @return The possibly null response to send to the server. |
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* It is null if the challenge accompanied a "SUCCESS" status and the challenge |
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* only contains data for the client to update its state and no response |
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* needs to be sent to the server. The response is a zero-length byte |
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* array if the client is to send a response with no data. |
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* @exception SaslException If an error occurred while processing |
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* the challenge or generating a response. |
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*/ |
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public abstract byte[] evaluateChallenge(byte[] challenge) |
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throws SaslException; |
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/** |
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* Determines whether the authentication exchange has completed. |
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* This method may be called at any time, but typically, it |
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* will not be called until the caller has received indication |
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* from the server |
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* (in a protocol-specific manner) that the exchange has completed. |
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* |
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* @return true if the authentication exchange has completed; false otherwise. |
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*/ |
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public abstract boolean isComplete(); |
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/** |
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* Unwraps a byte array received from the server. |
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* This method can be called only after the authentication exchange has |
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* completed (i.e., when {@code isComplete()} returns true) and only if |
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* the authentication exchange has negotiated integrity and/or privacy |
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* as the quality of protection; otherwise, an |
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* {@code IllegalStateException} is thrown. |
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*<p> |
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* {@code incoming} is the contents of the SASL buffer as defined in RFC 2222 |
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* without the leading four octet field that represents the length. |
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* {@code offset} and {@code len} specify the portion of {@code incoming} |
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* to use. |
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* |
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* @param incoming A non-null byte array containing the encoded bytes |
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* from the server. |
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* @param offset The starting position at {@code incoming} of the bytes to use. |
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* @param len The number of bytes from {@code incoming} to use. |
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* @return A non-null byte array containing the decoded bytes. |
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* @exception SaslException if {@code incoming} cannot be successfully |
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* unwrapped. |
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* @exception IllegalStateException if the authentication exchange has |
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* not completed, or if the negotiated quality of protection |
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* has neither integrity nor privacy. |
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*/ |
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public abstract byte[] unwrap(byte[] incoming, int offset, int len) |
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throws SaslException; |
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/** |
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* Wraps a byte array to be sent to the server. |
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* This method can be called only after the authentication exchange has |
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* completed (i.e., when {@code isComplete()} returns true) and only if |
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* the authentication exchange has negotiated integrity and/or privacy |
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* as the quality of protection; otherwise, an |
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* {@code IllegalStateException} is thrown. |
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*<p> |
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* The result of this method will make up the contents of the SASL buffer |
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* as defined in RFC 2222 without the leading four octet field that |
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* represents the length. |
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* {@code offset} and {@code len} specify the portion of {@code outgoing} |
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* to use. |
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* |
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* @param outgoing A non-null byte array containing the bytes to encode. |
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* @param offset The starting position at {@code outgoing} of the bytes to use. |
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* @param len The number of bytes from {@code outgoing} to use. |
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* @return A non-null byte array containing the encoded bytes. |
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* @exception SaslException if {@code outgoing} cannot be successfully |
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* wrapped. |
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* @exception IllegalStateException if the authentication exchange has |
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* not completed, or if the negotiated quality of protection |
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* has neither integrity nor privacy. |
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*/ |
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public abstract byte[] wrap(byte[] outgoing, int offset, int len) |
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throws SaslException; |
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/** |
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* Retrieves the negotiated property. |
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* This method can be called only after the authentication exchange has |
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* completed (i.e., when {@code isComplete()} returns true); otherwise, an |
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* {@code IllegalStateException} is thrown. |
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* |
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* @param propName The non-null property name. |
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* @return The value of the negotiated property. If null, the property was |
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* not negotiated or is not applicable to this mechanism. |
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* @exception IllegalStateException if this authentication exchange |
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* has not completed |
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*/ |
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public abstract Object getNegotiatedProperty(String propName); |
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/** |
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* Disposes of any system resources or security-sensitive information |
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* the SaslClient might be using. Invoking this method invalidates |
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* the SaslClient instance. This method is idempotent. |
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* @throws SaslException If a problem was encountered while disposing |
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* the resources. |
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*/ |
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public abstract void dispose() throws SaslException; |
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} |