001    /* CertPathBuilder.java -- bulids CertPath objects from Certificates.
002       Copyright (C) 2003, 2004  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    
039    package java.security.cert;
040    
041    import gnu.java.lang.CPStringBuilder;
042    
043    import gnu.java.security.Engine;
044    
045    import java.lang.reflect.InvocationTargetException;
046    import java.security.InvalidAlgorithmParameterException;
047    import java.security.NoSuchAlgorithmException;
048    import java.security.NoSuchProviderException;
049    import java.security.Provider;
050    import java.security.Security;
051    
052    /**
053     * This class builds certificate paths (also called certificate chains),
054     * which can be used to establish trust for a particular certificate by
055     * building a path from a trusted certificate (a trust anchor) to the
056     * untrusted certificate.
057     *
058     * @see CertPath
059     */
060    public class CertPathBuilder
061    {
062    
063      // Constants and fields.
064      // ------------------------------------------------------------------------
065    
066      /** Service name for CertPathBuilder. */
067      private static final String CERT_PATH_BUILDER = "CertPathBuilder";
068    
069      /** The underlying implementation. */
070      private CertPathBuilderSpi cpbSpi;
071    
072      /** The provider of this implementation. */
073      private Provider provider;
074    
075      /** The name of this implementation. */
076      private String algorithm;
077    
078      // Constructor.
079      // ------------------------------------------------------------------------
080    
081      /**
082       * Creates a new CertPathBuilder.
083       *
084       * @param cpbSpi    The underlying implementation.
085       * @param provider  The provider of the implementation.
086       * @param algorithm This implementation's name.
087       */
088      protected CertPathBuilder(CertPathBuilderSpi cpbSpi, Provider provider,
089                                String algorithm)
090      {
091        this.cpbSpi = cpbSpi;
092        this.provider = provider;
093        this.algorithm = algorithm;
094      }
095    
096      // Class methods.
097      // ------------------------------------------------------------------------
098    
099      /**
100       * Get the default cert path builder type.
101       *
102       * <p>This value can be set at run-time by the security property
103       * <code>"certpathbuilder.type"</code>. If this property is not set,
104       * then the value returned is <code>"PKIX"</code>.
105       *
106       * @return The default CertPathBuilder algorithm.
107       */
108      public static final String getDefaultType()
109      {
110        String type = Security.getProperty("certpathbuilder.type");
111        if (type == null)
112          type = "PKIX";
113        return type;
114      }
115    
116      /**
117       * Returns an instance of a named <code>CertPathBuilder</code> from the
118       * first provider that implements it.
119       *
120       * @param algorithm The name of the <code>CertPathBuilder</code> to create.
121       * @return The new instance.
122       * @throws NoSuchAlgorithmException If no installed provider implements the
123       *           named algorithm.
124       * @throws IllegalArgumentException if <code>algorithm</code> is
125       *           <code>null</code> or is an empty string.
126       */
127      public static CertPathBuilder getInstance(String algorithm)
128          throws NoSuchAlgorithmException
129      {
130        Provider[] p = Security.getProviders();
131        NoSuchAlgorithmException lastException = null;
132        for (int i = 0; i < p.length; i++)
133          try
134            {
135              return getInstance(algorithm, p[i]);
136            }
137          catch (NoSuchAlgorithmException x)
138            {
139              lastException = x;
140            }
141        if (lastException != null)
142          throw lastException;
143        throw new NoSuchAlgorithmException(algorithm);
144      }
145    
146      /**
147       * Returns an instance of a named <code>CertPathBuilder</code> from a named
148       * provider.
149       *
150       * @param algorithm The name of the <code>CertPathBuilder</code> to create.
151       * @param provider The name of the provider to use.
152       * @return The new instance.
153       * @throws NoSuchAlgorithmException If no installed provider implements the
154       *           named algorithm.
155       * @throws NoSuchProviderException If the named provider does not exist.
156       * @throws IllegalArgumentException if either <code>algorithm</code> or
157       *           <code>provider</code> is <code>null</code>, or if
158       *           <code>algorithm</code> is an empty string.
159       */
160      public static CertPathBuilder getInstance(String algorithm, String provider)
161          throws NoSuchAlgorithmException, NoSuchProviderException
162      {
163        if (provider == null)
164          throw new IllegalArgumentException("provider MUST NOT be null");
165        Provider p = Security.getProvider(provider);
166        if (p == null)
167          throw new NoSuchProviderException(provider);
168        return getInstance(algorithm, p);
169      }
170    
171      /**
172       * Returns an instance of a named <code>CertPathBuilder</code> from the
173       * specified provider.
174       *
175       * @param algorithm The name of the <code>CertPathBuilder</code> to create.
176       * @param provider The provider to use.
177       * @return The new instance.
178       * @throws NoSuchAlgorithmException If no installed provider implements the
179       *           named algorithm.
180       * @throws IllegalArgumentException if either <code>algorithm</code> or
181       *           <code>provider</code> is <code>null</code>, or if
182       *           <code>algorithm</code> is an empty string.
183       */
184      public static CertPathBuilder getInstance(String algorithm, Provider provider)
185          throws NoSuchAlgorithmException
186      {
187        CPStringBuilder sb = new CPStringBuilder("CertPathBuilder for algorithm [")
188            .append(algorithm).append("] from provider[")
189            .append(provider).append("] could not be created");
190        Throwable cause;
191        try
192          {
193            Object spi = Engine.getInstance(CERT_PATH_BUILDER, algorithm, provider);
194            return new CertPathBuilder((CertPathBuilderSpi) spi, provider, algorithm);
195          }
196        catch (InvocationTargetException x)
197          {
198            cause = x.getCause();
199            if (cause instanceof NoSuchAlgorithmException)
200              throw (NoSuchAlgorithmException) cause;
201            if (cause == null)
202              cause = x;
203          }
204        catch (ClassCastException x)
205          {
206            cause = x;
207          }
208        NoSuchAlgorithmException x = new NoSuchAlgorithmException(sb.toString());
209        x.initCause(cause);
210        throw x;
211      }
212    
213      /**
214       * Return the name of this CertPathBuilder algorithm.
215       *
216       * @return The algorithm name.
217       */
218      public final String getAlgorithm()
219      {
220        return algorithm;
221      }
222    
223      /**
224       * Return the provider of this instance's implementation.
225       *
226       * @return The provider.
227       */
228      public final Provider getProvider()
229      {
230        return provider;
231      }
232    
233      /**
234       * Builds a certificate path. The {@link CertPathParameters} parameter
235       * passed to this method is implementation-specific, but in general
236       * should contain some number of certificates and some number of
237       * trusted certificates (or "trust anchors").
238       *
239       * @param params The parameters.
240       * @retrun The certificate path result.
241       * @throws CertPathBuilderException If the certificate path cannot be
242       *   built.
243       * @throws InvalidAlgorithmParameterException If the implementation
244       *   rejects the specified parameters.
245       */
246      public final CertPathBuilderResult build(CertPathParameters params)
247        throws CertPathBuilderException, InvalidAlgorithmParameterException
248      {
249        return cpbSpi.engineBuild(params);
250      }
251    }