001/* CertPath.java -- a sequence of certificates
002   Copyright (C) 2002, 2005  Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038package java.security.cert;
039
040import gnu.java.lang.CPStringBuilder;
041
042import java.io.ByteArrayInputStream;
043import java.io.NotSerializableException;
044import java.io.ObjectStreamException;
045import java.io.Serializable;
046import java.util.Iterator;
047import 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 */
063public 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