001    /* CertPath.java -- a sequence of certificates
002       Copyright (C) 2002, 2005  Free Software Foundation, Inc.
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    package java.security.cert;
039    
040    import gnu.java.lang.CPStringBuilder;
041    
042    import java.io.ByteArrayInputStream;
043    import java.io.NotSerializableException;
044    import java.io.ObjectStreamException;
045    import java.io.Serializable;
046    import java.util.Iterator;
047    import java.util.List;
048    
049    /**
050     * This class represents an immutable sequence, or path, of security
051     * certificates. The path type must match the type of each certificate in the
052     * path, or in other words, for all instances of cert in a certpath object,
053     * <code>cert.getType().equals(certpath.getType())</code> will return true.
054     *
055     * <p>Since this class is immutable, it is thread-safe. During serialization,
056     * the path is consolidated into a {@link CertPathRep}, which preserves the
057     * data regardless of the underlying implementation of the path.
058     *
059     * @author Eric Blake (ebb9@email.byu.edu)
060     * @since 1.4
061     * @status updated to 1.4
062     */
063    public abstract class CertPath implements Serializable
064    {
065      /**
066       * The serialized representation of a path.
067       *
068       * @author Eric Blake (ebb9@email.byu.edu)
069       */
070      protected static class CertPathRep implements Serializable
071      {
072        /**
073         * Compatible with JDK 1.4+.
074         */
075        private static final long serialVersionUID = 3015633072427920915L;
076    
077        /**
078         * The certificate type.
079         *
080         * @serial the type of the certificate path
081         */
082        private final String type;
083    
084        /**
085         * The encoded form of the path.
086         *
087         * @serial the encoded form
088         */
089        private final byte[] data;
090    
091        /**
092         * Create the new serial representation.
093         *
094         * @param type the path type
095         * @param data the encoded path data
096         */
097        protected CertPathRep(String type, byte[] data)
098        {
099          this.type = type;
100          this.data = data;
101        }
102    
103        /**
104         * Decode the data into an actual {@link CertPath} upon deserialization.
105         *
106         * @return the replacement object
107         * @throws ObjectStreamException if replacement fails
108         */
109        protected Object readResolve() throws ObjectStreamException
110        {
111          try
112            {
113              return CertificateFactory.getInstance(type)
114                .generateCertPath(new ByteArrayInputStream(data));
115            }
116          catch (CertificateException e)
117            {
118              throw (ObjectStreamException)
119                new NotSerializableException("java.security.cert.CertPath: "
120                                             + type).initCause(e);
121            }
122        }
123      } // class CertPathRep
124    
125      /**
126       * Compatible with JDK 1.4+.
127       */
128      private static final long serialVersionUID = 6068470306649138683L;
129    
130      /**
131       * The path type.
132       *
133       * @serial the type of all certificates in this path
134       */
135      private final String type;
136    
137      /**
138       * Create a certificate path with the given type. Most code should use
139       * {@link CertificateFactory} to create CertPaths.
140       *
141       * @param type the type of the path
142       */
143      protected CertPath(String type)
144      {
145        this.type = type;
146      }
147    
148      /**
149       * Get the (non-null) type of all certificates in the path.
150       *
151       * @return the path certificate type
152       */
153      public String getType()
154      {
155        return type;
156      }
157    
158      /**
159       * Get an immutable iterator over the path encodings (all String names),
160       * starting with the default encoding. The iterator will throw an
161       * <code>UnsupportedOperationException</code> if an attempt is made to
162       * remove items from the list.
163       *
164       * @return the iterator of supported encodings in the path
165       */
166      public abstract Iterator<String> getEncodings();
167    
168      /**
169       * Compares this path to another for semantic equality. To be equal, both
170       * must be instances of CertPath, with the same type, and identical
171       * certificate lists. Overriding classes must not change this behavior.
172       *
173       * @param o the object to compare to
174       * @return true if the two are equal
175       */
176      public boolean equals(Object o)
177      {
178        if (! (o instanceof CertPath))
179          return false;
180        CertPath cp = (CertPath) o;
181        return type.equals(cp.type)
182          && getCertificates().equals(cp.getCertificates());
183      }
184    
185      /**
186       * Returns the hashcode of this certificate path. This is defined as:<br>
187       * <code>31 * getType().hashCode() + getCertificates().hashCode()</code>.
188       *
189       * @return the hashcode
190       */
191      public int hashCode()
192      {
193        return 31 * type.hashCode() + getCertificates().hashCode();
194      }
195    
196      public String toString()
197      {
198        List l = getCertificates();
199        int size = l.size();
200        int i = 0;
201        CPStringBuilder result = new CPStringBuilder(type);
202        result.append(" Cert Path: length = ").append(size).append(".\n[\n");
203        while (--size >= 0)
204          result.append(l.get(i++)).append('\n');
205        return result.append("\n]").toString();
206      }
207    
208      /**
209       * Returns the encoded form of this path, via the default encoding.
210       *
211       * @return the encoded form
212       * @throws CertificateEncodingException if encoding fails
213       */
214      public abstract byte[] getEncoded() throws CertificateEncodingException;
215    
216      /**
217       * Returns the encoded form of this path, via the specified encoding.
218       *
219       * @param encoding the encoding to use
220       * @return the encoded form
221       * @throws CertificateEncodingException if encoding fails or does not exist
222       */
223      public abstract byte[] getEncoded(String encoding)
224        throws CertificateEncodingException;
225    
226      /**
227       * Returns the immutable, thread-safe list of certificates in this path.
228       *
229       * @return the list of certificates, non-null but possibly empty
230       */
231      public abstract List<? extends Certificate> getCertificates();
232    
233      /**
234       * Serializes the path in its encoded form, to ensure reserialization with
235       * the appropriate factory object without worrying about list implementation.
236       * The result will always be an instance of {@link CertPathRep}.
237       *
238       * @return the replacement object
239       * @throws ObjectStreamException if the replacement creation fails
240       */
241      protected Object writeReplace() throws ObjectStreamException
242      {
243        try
244          {
245            return new CertPathRep(type, getEncoded());
246          }
247        catch (CertificateEncodingException e)
248          {
249            throw (ObjectStreamException)
250              new NotSerializableException("java.security.cert.CertPath: "
251                                           + type).initCause(e);
252          }
253      }
254    } // class CertPath