1 /* SaslClient.java -- 2 Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc. 3 4 This file is part of GNU Classpath. 5 6 GNU Classpath is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2, or (at your option) 9 any later version. 10 11 GNU Classpath is distributed in the hope that it will be useful, but 12 WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with GNU Classpath; see the file COPYING. If not, write to the 18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19 02110-1301 USA. 20 21 Linking this library statically or dynamically with other modules is 22 making a combined work based on this library. Thus, the terms and 23 conditions of the GNU General Public License cover the whole 24 combination. 25 26 As a special exception, the copyright holders of this library give you 27 permission to link this library with independent modules to produce an 28 executable, regardless of the license terms of these independent 29 modules, and to copy and distribute the resulting executable under 30 terms of your choice, provided that you also meet, for each linked 31 independent module, the terms and conditions of the license of that 32 module. An independent module is a module which is not derived from 33 or based on this library. If you modify this library, you may extend 34 this exception to your version of the library, but you are not 35 obligated to do so. If you do not wish to do so, delete this 36 exception statement from your version. */ 37 38 39 package javax.security.sasl; 40 41 /** 42 * <p>Performs SASL authentication as a client.</p> 43 * 44 * <p>A protocol library such as one for LDAP gets an instance of this class in 45 * order to perform authentication defined by a specific SASL mechanism. 46 * Invoking methods on the <code>SaslClient</code> instance process challenges 47 * and create responses according to the SASL mechanism implemented by the 48 * <code>SaslClient</code>. As the authentication proceeds, the instance 49 * encapsulates the state of a SASL client's authentication exchange.</p> 50 * 51 * <p>Here's an example of how an LDAP library might use a <code>SaslClient</code>. 52 * It first gets an instance of a SaslClient:</p> 53 * <pre> 54 *SaslClient sc = 55 * Sasl.createSaslClient(mechanisms, authorizationID, protocol, 56 * serverName, props, callbackHandler); 57 * </pre> 58 * 59 * <p>It can then proceed to use the client for authentication. For example, an 60 * LDAP library might use the client as follows:</p> 61 * <pre> 62 * // Get initial response and send to server 63 *byte[] response = sc.hasInitialResponse() 64 * ? sc.evaluateChallenge(new byte[0]) : null; 65 *LdapResult res = ldap.sendBindRequest(dn, sc.getName(), response); 66 *while (!sc.isComplete() 67 * && ((res.status == SASL_BIND_IN_PROGRESS) || (res.status == SUCCESS))) { 68 * response = sc.evaluateChallenge( res.getBytes() ); 69 * if (res.status == SUCCESS) { 70 * // we're done; don't expect to send another BIND 71 * if ( response != null ) { 72 * throw new SaslException( 73 * "Protocol error: attempting to send response after completion"); 74 * } 75 * break; 76 * } 77 * res = ldap.sendBindRequest(dn, sc.getName(), response); 78 *} 79 *if (sc.isComplete() && (res.status == SUCCESS) ) { 80 * String qop = (String)sc.getNegotiatedProperty(Sasl.QOP); 81 * if ((qop != null) 82 * && (qop.equalsIgnoreCase("auth-int") 83 * || qop.equalsIgnoreCase("auth-conf"))) { 84 * // Use SaslClient.wrap() and SaslClient.unwrap() for future 85 * // communication with server 86 * ldap.in = new SecureInputStream(sc, ldap.in); 87 * ldap.out = new SecureOutputStream(sc, ldap.out); 88 * } 89 *} 90 * </pre> 91 * 92 * <p>If the mechanism has an initial response, the library invokes 93 * {@link #evaluateChallenge(byte[])} with an empty challenge to get the initial 94 * response. Protocols such as IMAP4, which do not include an initial response 95 * with their first authentication command to the server, initiate the 96 * authentication without first calling {@link #hasInitialResponse()} or 97 * {@link #evaluateChallenge(byte[])}. When the server responds to the command, 98 * it sends an initial challenge. For a SASL mechanism in which the client sends 99 * data first, the server should have issued a challenge with no data. This will 100 * then result in a call (on the client) to {@link #evaluateChallenge(byte[])} 101 * with an empty challenge.</p> 102 * 103 * @see Sasl 104 * @see SaslClientFactory 105 * 106 * @since 1.5 107 */ 108 public interface SaslClient 109 { 110 111 /** 112 * Returns the IANA-registered mechanism name of this SASL client. (e.g. 113 * "CRAM-MD5", "GSSAPI"). 114 * 115 * @return a non-null string representing the IANA-registered mechanism name. 116 */ getMechanismName()117 String getMechanismName(); 118 119 /** 120 * Determines if this mechanism has an optional initial response. If 121 * <code>true</code>, caller should call {@link #evaluateChallenge(byte[])} 122 * with an empty array to get the initial response. 123 * 124 * @return <code>true</code> if this mechanism has an initial response. 125 */ hasInitialResponse()126 boolean hasInitialResponse(); 127 128 /** 129 * Evaluates the challenge data and generates a response. If a challenge is 130 * received from the server during the authentication process, this method is 131 * called to prepare an appropriate next response to submit to the server. 132 * 133 * @param challenge the non-null challenge sent from the server. The 134 * challenge array may have zero length. 135 * @return the possibly <code>null</code> reponse to send to the server. It 136 * is <code>null</code> if the challenge accompanied a "SUCCESS" status and 137 * the challenge only contains data for the client to update its state and no 138 * response needs to be sent to the server. The response is a zero-length 139 * byte array if the client is to send a response with no data. 140 * @throws SaslException if an error occurred while processing the challenge 141 * or generating a response. 142 */ evaluateChallenge(byte[] challenge)143 byte[] evaluateChallenge(byte[] challenge) throws SaslException; 144 145 /** 146 * Determines if the authentication exchange has completed. This method may 147 * be called at any time, but typically, it will not be called until the 148 * caller has received indication from the server (in a protocol-specific 149 * manner) that the exchange has completed. 150 * 151 * @return <code>true</code> if the authentication exchange has completed; 152 * <code>false</code> otherwise. 153 */ isComplete()154 boolean isComplete(); 155 156 /** 157 * <p>Unwraps a byte array received from the server. This method can be 158 * called only after the authentication exchange has completed (i.e., when 159 * {@link #isComplete()} returns <code>true</code>) and only if the 160 * authentication exchange has negotiated integrity and/or privacy as the 161 * quality of protection; otherwise, an {@link IllegalStateException} is 162 * thrown.</p> 163 * 164 * <p><code>incoming</code> is the contents of the SASL buffer as defined in 165 * RFC 2222 without the leading four octet field that represents the length. 166 * <code>offset</code> and <code>len</code> specify the portion of incoming 167 * to use.</p> 168 * 169 * @param incoming a non-null byte array containing the encoded bytes from 170 * the server. 171 * @param offset the starting position at <code>incoming</code> of the bytes 172 * to use. 173 * @param len the number of bytes from <code>incoming</code> to use. 174 * @return a non-null byte array containing the decoded bytes. 175 * @throws SaslException if <code>incoming</code> cannot be successfully 176 * unwrapped. 177 * @throws IllegalStateException if the authentication exchange has not 178 * completed, or if the negotiated quality of protection has neither 179 * integrity nor privacy. 180 */ unwrap(byte[] incoming, int offset, int len)181 byte[] unwrap(byte[] incoming, int offset, int len) throws SaslException; 182 183 /** 184 * <p>Wraps a byte array to be sent to the server. This method can be called 185 * only after the authentication exchange has completed (i.e., when 186 * {@link #isComplete()} returns <code>true</code>) and only if the 187 * authentication exchange has negotiated integrity and/or privacy as the 188 * quality of protection; otherwise, an {@link IllegalStateException} is 189 * thrown.</p> 190 * 191 * <p>The result of this method will make up the contents of the SASL buffer 192 * as defined in RFC 2222 without the leading four octet field that 193 * represents the length. <code>offset</code> and <code>len</code> specify 194 * the portion of <code>outgoing</code> to use.</p> 195 * 196 * @param outgoing a non-null byte array containing the bytes to encode. 197 * @param offset the starting position at <code>outgoing</code> of the bytes 198 * to use. 199 * @param len the number of bytes from <code>outgoing</code> to use. 200 * @return a non-null byte array containing the encoded bytes. 201 * @throws SaslException if <code>outgoing</code> cannot be successfully 202 * wrapped. 203 * @throws IllegalStateException if the authentication exchange has not 204 * completed, or if the negotiated quality of protection has neither 205 * integrity nor privacy. 206 */ wrap(byte[] outgoing, int offset, int len)207 byte[] wrap(byte[] outgoing, int offset, int len) throws SaslException; 208 209 /** 210 * Retrieves the negotiated property. This method can be called only after 211 * the authentication exchange has completed (i.e., when {@link #isComplete()} 212 * returns <code>true</code>); otherwise, an {@link IllegalStateException} is 213 * thrown. 214 * 215 * @param propName the non-null property name. 216 * @return the value of the negotiated property. If <code>null</code>, the 217 * property was not negotiated or is not applicable to this mechanism. 218 * @throws IllegalStateException if this authentication exchange has not 219 * completed. 220 */ getNegotiatedProperty(String propName)221 Object getNegotiatedProperty(String propName); 222 223 /** 224 * Disposes of any system resources or security-sensitive information the 225 * <code>SaslClient</code> might be using. Invoking this method invalidates 226 * the <code>SaslClient</code> instance. This method is idempotent. 227 * 228 * @throws SaslException if a problem was encountered while disposing of the 229 * resources. 230 */ dispose()231 void dispose() throws SaslException; 232 } 233