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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
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 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
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 *
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package java.security.cert;

import java.security.AccessController;
import java.security.InvalidAlgorithmParameterException;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.PrivilegedAction;
import java.security.Provider;
import java.security.Security;
import java.util.Collection;

import sun.security.jca.*;
import sun.security.jca.GetInstance.Instance;

/**
 * A class for retrieving <code>Certificate</code>s and <code>CRL</code>s
 * from a repository.
 * <p>
 * This class uses a provider-based architecture.
 * To create a <code>CertStore</code>, call one of the static
 * <code>getInstance</code> methods, passing in the type of
 * <code>CertStore</code> desired, any applicable initialization parameters
 * and optionally the name of the provider desired.
 * <p>
 * Once the <code>CertStore</code> has been created, it can be used to
 * retrieve <code>Certificate</code>s and <code>CRL</code>s by calling its
 * {@link #getCertificates(CertSelector selector) getCertificates} and
 * {@link #getCRLs(CRLSelector selector) getCRLs} methods.
 * <p>
 * Unlike a {@link java.security.KeyStore KeyStore}, which provides access
 * to a cache of private keys and trusted certificates, a
 * <code>CertStore</code> is designed to provide access to a potentially
 * vast repository of untrusted certificates and CRLs. For example, an LDAP
 * implementation of <code>CertStore</code> provides access to certificates
 * and CRLs stored in one or more directories using the LDAP protocol and the
 * schema as defined in the RFC service attribute.
 *
 * <p> Android provides the following <code>CertStore</code> types:
 * <table>
 *     <thead>
 *         <tr>
 *             <th>Name</th>
 *             <th>Supported (API Levels)</th>
 *         </tr>
 *     </thead>
 *     <tbody>
 *         <tr>
 *             <td>Collection</td>
 *             <td>1+</td>
 *         </tr>
 *     </tbody>
 * </table>
 *
 * This type is described in the <a href=
 * "{@docRoot}openjdk-redirect.html?v=8&path=/technotes/guides/security/StandardNames.html#CertStore">
 * CertStore section</a> of the
 * Java Cryptography Architecture Standard Algorithm Name Documentation.
 *
 * <p>
 * <b>Concurrent Access</b>
 * <p>
 * All public methods of <code>CertStore</code> objects must be thread-safe.
 * That is, multiple threads may concurrently invoke these methods on a
 * single <code>CertStore</code> object (or more than one) with no
 * ill effects. This allows a <code>CertPathBuilder</code> to search for a
 * CRL while simultaneously searching for further certificates, for instance.
 * <p>
 * The static methods of this class are also guaranteed to be thread-safe.
 * Multiple threads may concurrently invoke the static methods defined in
 * this class with no ill effects.
 *
 * @since       1.4
 * @author      Sean Mullan, Steve Hanna
 */
public class CertStore {
    /*
     * Constant to lookup in the Security properties file to determine
     * the default certstore type. In the Security properties file, the
     * default certstore type is given as:
     * <pre>
     * certstore.type=LDAP
     * </pre>
     */
    private static final String CERTSTORE_TYPE = "certstore.type";
    private CertStoreSpi storeSpi;
    private Provider provider;
    private String type;
    private CertStoreParameters params;

    /**
     * Creates a <code>CertStore</code> object of the given type, and
     * encapsulates the given provider implementation (SPI object) in it.
     *
     * @param storeSpi the provider implementation
     * @param provider the provider
     * @param type the type
     * @param params the initialization parameters (may be <code>null</code>)
     */
    protected CertStore(CertStoreSpi storeSpi, Provider provider,
                        String type, CertStoreParameters params) {
        this.storeSpi = storeSpi;
        this.provider = provider;
        this.type = type;
        if (params != null)
            this.params = (CertStoreParameters) params.clone();
    }

    /**
     * Returns a <code>Collection</code> of <code>Certificate</code>s that
     * match the specified selector. If no <code>Certificate</code>s
     * match the selector, an empty <code>Collection</code> will be returned.
     * <p>
     * For some <code>CertStore</code> types, the resulting
     * <code>Collection</code> may not contain <b>all</b> of the
     * <code>Certificate</code>s that match the selector. For instance,
     * an LDAP <code>CertStore</code> may not search all entries in the
     * directory. Instead, it may just search entries that are likely to
     * contain the <code>Certificate</code>s it is looking for.
     * <p>
     * Some <code>CertStore</code> implementations (especially LDAP
     * <code>CertStore</code>s) may throw a <code>CertStoreException</code>
     * unless a non-null <code>CertSelector</code> is provided that
     * includes specific criteria that can be used to find the certificates.
     * Issuer and/or subject names are especially useful criteria.
     *
     * @param selector A <code>CertSelector</code> used to select which
     *  <code>Certificate</code>s should be returned. Specify <code>null</code>
     *  to return all <code>Certificate</code>s (if supported).
     * @return A <code>Collection</code> of <code>Certificate</code>s that
     *         match the specified selector (never <code>null</code>)
     * @throws CertStoreException if an exception occurs
     */
    public final Collection<? extends Certificate> getCertificates
            (CertSelector selector) throws CertStoreException {
        return storeSpi.engineGetCertificates(selector);
    }

    /**
     * Returns a <code>Collection</code> of <code>CRL</code>s that
     * match the specified selector. If no <code>CRL</code>s
     * match the selector, an empty <code>Collection</code> will be returned.
     * <p>
     * For some <code>CertStore</code> types, the resulting
     * <code>Collection</code> may not contain <b>all</b> of the
     * <code>CRL</code>s that match the selector. For instance,
     * an LDAP <code>CertStore</code> may not search all entries in the
     * directory. Instead, it may just search entries that are likely to
     * contain the <code>CRL</code>s it is looking for.
     * <p>
     * Some <code>CertStore</code> implementations (especially LDAP
     * <code>CertStore</code>s) may throw a <code>CertStoreException</code>
     * unless a non-null <code>CRLSelector</code> is provided that
     * includes specific criteria that can be used to find the CRLs.
     * Issuer names and/or the certificate to be checked are especially useful.
     *
     * @param selector A <code>CRLSelector</code> used to select which
     *  <code>CRL</code>s should be returned. Specify <code>null</code>
     *  to return all <code>CRL</code>s (if supported).
     * @return A <code>Collection</code> of <code>CRL</code>s that
     *         match the specified selector (never <code>null</code>)
     * @throws CertStoreException if an exception occurs
     */
    public final Collection<? extends CRL> getCRLs(CRLSelector selector)
            throws CertStoreException {
        return storeSpi.engineGetCRLs(selector);
    }

    /**
     * Returns a <code>CertStore</code> object that implements the specified
     * <code>CertStore</code> type and is initialized with the specified
     * parameters.
     *
     * <p> This method traverses the list of registered security Providers,
     * starting with the most preferred Provider.
     * A new CertStore object encapsulating the
     * CertStoreSpi implementation from the first
     * Provider that supports the specified type is returned.
     *
     * <p> Note that the list of registered providers may be retrieved via
     * the {@link Security#getProviders() Security.getProviders()} method.
     *
     * <p>The <code>CertStore</code> that is returned is initialized with the
     * specified <code>CertStoreParameters</code>. The type of parameters
     * needed may vary between different types of <code>CertStore</code>s.
     * Note that the specified <code>CertStoreParameters</code> object is
     * cloned.
     *
     * @param type the name of the requested <code>CertStore</code> type.
     * See the CertStore section in the <a href=
     * "{@docRoot}openjdk-redirect.html?v=8&path=/technotes/guides/security/StandardNames.html#CertStore">
     * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
     * for information about standard types.
     *
     * @param params the initialization parameters (may be <code>null</code>).
     *
     * @return a <code>CertStore</code> object that implements the specified
     *          <code>CertStore</code> type.
     *
     * @throws NoSuchAlgorithmException if no Provider supports a
     *          CertStoreSpi implementation for the specified type.
     *
     * @throws InvalidAlgorithmParameterException if the specified
     *          initialization parameters are inappropriate for this
     *          <code>CertStore</code>.
     *
     * @see java.security.Provider
     */
    public static CertStore getInstance(String type, CertStoreParameters params)
            throws InvalidAlgorithmParameterException,
            NoSuchAlgorithmException {
        try {
            Instance instance = GetInstance.getInstance("CertStore",
                CertStoreSpi.class, type, params);
            return new CertStore((CertStoreSpi)instance.impl,
                instance.provider, type, params);
        } catch (NoSuchAlgorithmException e) {
            return handleException(e);
        }
    }

    private static CertStore handleException(NoSuchAlgorithmException e)
            throws NoSuchAlgorithmException, InvalidAlgorithmParameterException {
        Throwable cause = e.getCause();
        if (cause instanceof InvalidAlgorithmParameterException) {
            throw (InvalidAlgorithmParameterException)cause;
        }
        throw e;
    }

    /**
     * Returns a <code>CertStore</code> object that implements the specified
     * <code>CertStore</code> type.
     *
     * <p> A new CertStore object encapsulating the
     * CertStoreSpi implementation from the specified provider
     * is returned.  The specified provider must be registered
     * in the security provider list.
     *
     * <p> Note that the list of registered providers may be retrieved via
     * the {@link Security#getProviders() Security.getProviders()} method.
     *
     * <p>The <code>CertStore</code> that is returned is initialized with the
     * specified <code>CertStoreParameters</code>. The type of parameters
     * needed may vary between different types of <code>CertStore</code>s.
     * Note that the specified <code>CertStoreParameters</code> object is
     * cloned.
     *
     * @param type the requested <code>CertStore</code> type.
     * See the CertStore section in the <a href=
     * "{@docRoot}openjdk-redirect.html?v=8&path=/technotes/guides/security/StandardNames.html#CertStore">
     * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
     * for information about standard types.
     *
     * @param params the initialization parameters (may be <code>null</code>).
     *
     * @param provider the name of the provider.
     *
     * @return a <code>CertStore</code> object that implements the
     *          specified type.
     *
     * @throws NoSuchAlgorithmException if a CertStoreSpi
     *          implementation for the specified type is not
     *          available from the specified provider.
     *
     * @throws InvalidAlgorithmParameterException if the specified
     *          initialization parameters are inappropriate for this
     *          <code>CertStore</code>.
     *
     * @throws NoSuchProviderException if the specified provider is not
     *          registered in the security provider list.
     *
     * @exception IllegalArgumentException if the <code>provider</code> is
     *          null or empty.
     *
     * @see java.security.Provider
     */
    public static CertStore getInstance(String type,
            CertStoreParameters params, String provider)
            throws InvalidAlgorithmParameterException,
            NoSuchAlgorithmException, NoSuchProviderException {
        try {
            Instance instance = GetInstance.getInstance("CertStore",
                CertStoreSpi.class, type, params, provider);
            return new CertStore((CertStoreSpi)instance.impl,
                instance.provider, type, params);
        } catch (NoSuchAlgorithmException e) {
            return handleException(e);
        }
    }

    /**
     * Returns a <code>CertStore</code> object that implements the specified
     * <code>CertStore</code> type.
     *
     * <p> A new CertStore object encapsulating the
     * CertStoreSpi implementation from the specified Provider
     * object is returned.  Note that the specified Provider object
     * does not have to be registered in the provider list.
     *
     * <p>The <code>CertStore</code> that is returned is initialized with the
     * specified <code>CertStoreParameters</code>. The type of parameters
     * needed may vary between different types of <code>CertStore</code>s.
     * Note that the specified <code>CertStoreParameters</code> object is
     * cloned.
     *
     * @param type the requested <code>CertStore</code> type.
     * See the CertStore section in the <a href=
     * "{@docRoot}openjdk-redirect.html?v=8&path=/technotes/guides/security/StandardNames.html#CertStore">
     * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
     * for information about standard types.
     *
     * @param params the initialization parameters (may be <code>null</code>).
     *
     * @param provider the provider.
     *
     * @return a <code>CertStore</code> object that implements the
     *          specified type.
     *
     * @exception NoSuchAlgorithmException if a CertStoreSpi
     *          implementation for the specified type is not available
     *          from the specified Provider object.
     *
     * @throws InvalidAlgorithmParameterException if the specified
     *          initialization parameters are inappropriate for this
     *          <code>CertStore</code>
     *
     * @exception IllegalArgumentException if the <code>provider</code> is
     *          null.
     *
     * @see java.security.Provider
     */
    public static CertStore getInstance(String type, CertStoreParameters params,
            Provider provider) throws NoSuchAlgorithmException,
            InvalidAlgorithmParameterException {
        try {
            Instance instance = GetInstance.getInstance("CertStore",
                CertStoreSpi.class, type, params, provider);
            return new CertStore((CertStoreSpi)instance.impl,
                instance.provider, type, params);
        } catch (NoSuchAlgorithmException e) {
            return handleException(e);
        }
    }

    /**
     * Returns the parameters used to initialize this <code>CertStore</code>.
     * Note that the <code>CertStoreParameters</code> object is cloned before
     * it is returned.
     *
     * @return the parameters used to initialize this <code>CertStore</code>
     * (may be <code>null</code>)
     */
    public final CertStoreParameters getCertStoreParameters() {
        return (params == null ? null : (CertStoreParameters) params.clone());
    }

    /**
     * Returns the type of this <code>CertStore</code>.
     *
     * @return the type of this <code>CertStore</code>
     */
    public final String getType() {
        return this.type;
    }

    /**
     * Returns the provider of this <code>CertStore</code>.
     *
     * @return the provider of this <code>CertStore</code>
     */
    public final Provider getProvider() {
        return this.provider;
    }

    /**
     * Returns the default <code>CertStore</code> type as specified in the
     * Java security properties file, or the string &quot;LDAP&quot; if no
     * such property exists. The Java security properties file is located in
     * the file named &lt;JAVA_HOME&gt;/lib/security/java.security.
     * &lt;JAVA_HOME&gt; refers to the value of the java.home system property,
     * and specifies the directory where the JRE is installed.
     *
     * <p>The default <code>CertStore</code> type can be used by applications
     * that do not want to use a hard-coded type when calling one of the
     * <code>getInstance</code> methods, and want to provide a default
     * <code>CertStore</code> type in case a user does not specify its own.
     *
     * <p>The default <code>CertStore</code> type can be changed by setting
     * the value of the "certstore.type" security property (in the Java
     * security properties file) to the desired type.
     *
     * @return the default <code>CertStore</code> type as specified in the
     * Java security properties file, or the string &quot;LDAP&quot;
     * if no such property exists.
     */
    public final static String getDefaultType() {
        String cstype;
        cstype = AccessController.doPrivileged(new PrivilegedAction<String>() {
            public String run() {
                return Security.getProperty(CERTSTORE_TYPE);
            }
        });
        if (cstype == null) {
            cstype = "LDAP";
        }
        return cstype;
    }
}