gcc/libjava/java/security/cert/CertPathBuilder.java

/* CertPathBuilder.java -- bulids CertPath objects from Certificates.
   Copyright (C) 2003 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
 
GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
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this exception to your version of the library, but you are not
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exception statement from your version. */


package java.security.cert;

import java.security.InvalidAlgorithmParameterException;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.Provider;
import java.security.Security;

import gnu.java.security.Engine;

/**
 * This class builds certificate paths (also called certificate chains),
 * which can be used to establish trust for a particular certificate by
 * building a path from a trusted certificate (a trust anchor) to the
 * untrusted certificate.
 *
 * @see CertPath
 */
public class CertPathBuilder
{

  // Constants and fields.
  // ------------------------------------------------------------------------

  /** Service name for CertPathBuilder. */
  private static final String CERT_PATH_BUILDER = "CertPathBuilder";

  /** The underlying implementation. */
  private CertPathBuilderSpi cpbSpi;

  /** The provider of this implementation. */
  private Provider provider;

  /** The name of this implementation. */
  private String algorithm;

  // Constructor.
  // ------------------------------------------------------------------------

  /**
   * Creates a new CertPathBuilder.
   *
   * @param cpbSpi    The underlying implementation.
   * @param provider  The provider of the implementation.
   * @param algorithm This implementation's name.
   */
  protected CertPathBuilder(CertPathBuilderSpi cpbSpi, Provider provider,
                            String algorithm)
  {
    this.cpbSpi = cpbSpi;
    this.provider = provider;
    this.algorithm = algorithm;
  }

  // Class methods.
  // ------------------------------------------------------------------------

  /**
   * Get the default cert path builder type.
   *
   * <p>This value can be set at run-time by the security property
   * <code>"certpathbuilder.type"</code>. If this property is not set,
   * then the value returned is <code>"PKIX"</code>.
   *
   * @return The default CertPathBuilder algorithm.
   */
  public static final String getDefaultType()
  {
    String type = Security.getProperty("certpathbuilder.type");
    if (type == null)
      type = "PKIX";
    return type;
  }

  /**
   * Get an instance of a named CertPathBuilder, from the first provider
   * that implements it.
   *
   * @param algorithm The name of the CertPathBuilder to create.
   * @return The new instance.
   * @throws NoSuchAlgorithmException If no installed provider
   *   implements the named algorithm.
   */
  public static CertPathBuilder getInstance(String algorithm)
    throws NoSuchAlgorithmException
  {
    Provider[] p = Security.getProviders();

    for (int i = 0; i < p.length; i++)
      {
        try
          {
            return getInstance(algorithm, p[i]);
          }
        catch (NoSuchAlgorithmException ignored)
          {
          }
      }

    throw new NoSuchAlgorithmException(algorithm);
  }

  /**
   * Get an instance of a named CertPathBuilder from the named
   * provider.
   *
   * @param algorithm The name of the CertPathBuilder to create.
   * @param provider  The name of the provider from which to get the
   *   implementation.
   * @return The new instance.
   * @throws NoSuchAlgorithmException If no installed provider
   *   implements the named algorithm.
   * @throws NoSuchProviderException If the named provider does not
   *   exist.
   */
  public static CertPathBuilder getInstance(String algorithm, String provider)
    throws NoSuchAlgorithmException, NoSuchProviderException
  {
    Provider p = Security.getProvider(provider);
    if (p == null)
      throw new NoSuchProviderException(provider);
    return getInstance(algorithm, p);
  }

  /**
   * Get an instance of a named CertPathBuilder from the specified
   * provider.
   *
   * @param algorithm The name of the CertPathBuilder to create.
   * @param provider  The provider from which to get the implementation.
   * @return The new instance.
   * @throws NoSuchAlgorithmException If no installed provider
   *   implements the named algorithm.
   * @throws IllegalArgumentException If <i>provider</i> in
   *   <tt>null</tt>.
   */
  public static CertPathBuilder getInstance(String algorithm, Provider provider)
    throws NoSuchAlgorithmException
  {
    if (provider == null)
      throw new IllegalArgumentException("null provider");
    try
      {
        return new CertPathBuilder((CertPathBuilderSpi)
          Engine.getInstance(CERT_PATH_BUILDER, algorithm, provider),
          provider, algorithm);
      }
    catch (java.lang.reflect.InvocationTargetException ite)
      {
        throw new NoSuchAlgorithmException(algorithm);
      }
    catch (ClassCastException cce)
      {
        throw new NoSuchAlgorithmException(algorithm);
      }
  }

  // Instance methods.
  // ------------------------------------------------------------------------

  /**
   * Return the name of this CertPathBuilder algorithm.
   *
   * @return The algorithm name.
   */
  public final String getAlgorithm()
  {
    return algorithm;
  }

  /**
   * Return the provider of this instance's implementation.
   *
   * @return The provider.
   */
  public final Provider getProvider()
  {
    return provider;
  }

  /**
   * Builds a certificate path. The {@link CertPathParameters} parameter
   * passed to this method is implementation-specific, but in general
   * should contain some number of certificates and some number of
   * trusted certificates (or "trust anchors").
   *
   * @param params The parameters.
   * @retrun The certificate path result.
   * @throws CertPathBuilderException If the certificate path cannot be
   *   built.
   * @throws InvalidAlgorithmParameterException If the implementation
   *   rejects the specified parameters.
   */
  public final CertPathBuilderResult build(CertPathParameters params)
    throws CertPathBuilderException, InvalidAlgorithmParameterException
  {
    return cpbSpi.engineBuild(params);
  }
}