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