ChannelBinding


1   /*
2    * @(#)ChannelBinding.java  1.8 03/12/19
3    *
4    * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
5    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6    */
7    
8   package org.ietf.jgss;
9   
10  import java.net.InetAddress  ;
11  import java.util.Arrays  ;
12  
13  /**
14   * This class encapsulates the concept of caller-provided channel
15   * binding information. Channel bindings are used to strengthen the
16   * quality with which peer entity authentication is provided during
17   * context establishment.  They enable the GSS-API callers to bind the
18   * establishment of the security context to relevant characteristics
19   * like addresses or to application specific data.<p>
20   *
21   * The caller initiating the security context must determine the
22   * appropriate channel binding values to set in the GSSContext object.
23   * The acceptor must provide an identical binding in order to validate
24   * that received tokens possess correct channel-related characteristics.<p>
25   *
26   * Use of channel bindings is optional in GSS-API. ChannelBinding can be
27   * set for the {@link GSSContext GSSContext} using the {@link
28   * GSSContext#setChannelBinding(ChannelBinding) setChannelBinding} method
29   * before the first call to {@link GSSContext#initSecContext(byte[], int, int)
30   * initSecContext} or {@link GSSContext#acceptSecContext(byte[], int, int)
31   * acceptSecContext} has been performed.  Unless the <code>setChannelBinding</code>
32   * method has been used to set the ChannelBinding for a GSSContext object,
33   * <code>null</code> ChannelBinding will be assumed. <p>
34   *
35   * Conceptually, the GSS-API concatenates the initiator and acceptor
36   * address information, and the application supplied byte array to form an
37   * octet string.  The mechanism calculates a MIC over this octet string and
38   * binds the MIC to the context establishment token emitted by
39   * <code>initSecContext</code> method of the <code>GSSContext</code>
40   * interface.  The same bindings are set by the context acceptor for its
41   * <code>GSSContext</code> object and during processing of the
42   * <code>acceptSecContext</code> method a MIC is calculated in the same
43   * way. The calculated MIC is compared with that found in the token, and if
44   * the MICs differ, accept will throw a <code>GSSException</code> with the
45   * major code set to {@link GSSException#BAD_BINDINGS BAD_BINDINGS}, and
46   * the context will not be established. Some mechanisms may include the
47   * actual channel binding data in the token (rather than just a MIC);
48   * applications should therefore not use confidential data as
49   * channel-binding components.<p>
50   *
51   *  Individual mechanisms may impose additional constraints on addresses
52   *  that may appear in channel bindings.  For example, a mechanism may
53   *  verify that the initiator address field of the channel binding
54   *  contains the correct network address of the host system.  Portable
55   *  applications should therefore ensure that they either provide correct
56   *  information for the address fields, or omit setting of the addressing
57   *  information.
58   *
59   * @author Mayank Upadhyay
60   * @version 1.8, 12/19/03
61   * @since 1.4
62   */
63  public class ChannelBinding {
64  
65      private InetAddress   initiator;
66      private InetAddress   acceptor;
67      private  byte[] appData;
68      
69      /** 
70       * Create a ChannelBinding object with user supplied address information
71       * and data.  <code>null</code> values can be used for any fields which the
72       * application does not want to specify.
73       * 
74       * @param initAddr the address of the context initiator.
75       * <code>null</code> value can be supplied to indicate that the
76       * application does not want to set this value.
77       * @param acceptAddr the address of the context
78       * acceptor. <code>null</code> value can be supplied to indicate that
79       * the application does not want to set this value.
80       * @param appData application supplied data to be used as part of the
81       * channel bindings. <code>null</code> value can be supplied to
82       * indicate that the application does not want to set this value.
83       */
84      public ChannelBinding(InetAddress   initAddr, InetAddress   acceptAddr,
85              byte[] appData) {
86  
87      initiator = initAddr;
88      acceptor = acceptAddr;
89  
90      if (appData != null) {
91          this.appData = new byte[appData.length];
92          java.lang.System.arraycopy(appData, 0, this.appData, 0,
93                  appData.length);
94      }
95      }
96      
97      /** 
98       * Creates a ChannelBinding object without any addressing information.
99       *
100      * @param appData application supplied data to be used as part of the
101      * channel bindings.
102      */
103     public ChannelBinding(byte[] appData) {
104         this(null, null, appData);
105     }
106 
107     /** 
108      * Get the initiator's address for this channel binding.
109      * 
110      * @return the initiator's address. <code>null</code> is returned if
111      * the address has not been set.
112      */
113     public InetAddress   getInitiatorAddress() {
114     return initiator;
115     }
116 
117     /** 
118      * Get the acceptor's address for this channel binding.
119      * 
120      * @return the acceptor's address. null is returned if the address has
121      * not been set.
122      */
123     public InetAddress   getAcceptorAddress() {
124     return acceptor;
125     }
126   
127     /** 
128      * Get the application specified data for this channel binding.
129      *
130      * @return the application data being used as part of the
131      * ChannelBinding. <code>null</code> is returned if no application data
132      * has been specified for the channel binding.
133      */
134     public byte[] getApplicationData() {
135         
136         if (appData == null) {
137             return null;
138         }
139         
140         byte[] retVal = new byte[appData.length];
141         System.arraycopy(appData, 0, retVal, 0, appData.length);
142     return retVal;
143     }
144 
145     /** 
146      * Compares two instances of ChannelBinding.
147      * 
148      * @param obj another ChannelBinding to compare this one with
149      * @return true if the two ChannelBinding's contain
150      * the same values for the initiator and acceptor addresses and the
151      * application data. 
152      */
153     public boolean equals(Object   obj) {
154 
155     if (this == obj)
156         return true;
157     
158     if (! (obj instanceof ChannelBinding  ))
159         return false;
160     
161     ChannelBinding   cb = (ChannelBinding  ) obj;
162     
163     if ((initiator != null && cb.initiator == null) ||
164         (initiator == null && cb.initiator != null))
165         return false;
166 
167     if (initiator != null && !initiator.equals(cb.initiator))
168         return false;
169 
170     if ((acceptor != null && cb.acceptor == null) ||
171         (acceptor == null && cb.acceptor != null))
172         return false;
173 
174     if (acceptor != null && !acceptor.equals(cb.acceptor))
175         return false;
176 
177     return Arrays.equals(appData, cb.appData);
178     }
179 
180     /**
181      * Returns a hashcode value for this ChannelBinding object.
182      *
183      * @return a hashCode value
184      */
185     public int hashCode() {
186     if (initiator != null)
187         return initiator.hashCode();
188     else if (acceptor != null)
189         return acceptor.hashCode();
190     else if (appData != null)
191         return new String  (appData).hashCode();
192     else
193         return 1;
194     }
195 }
196
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