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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> Every implementation of the Java platform is required to support the

 * following standard <code>CertStore</code> type:

 * <ul>

 * <li><tt>Collection</tt></li>

 * </ul>

 * This type is described in the <a href=

 * "{@docRoot}/../technotes/guides/security/StandardNames.html#CertStore">

 * CertStore section</a> of the

 * Java Cryptography Architecture Standard Algorithm Name Documentation.

 * Consult the release documentation for your implementation to see if any

 * other types are supported.

 *

 * <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}/../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}/../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}/../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 "LDAP" if no

     * such property exists. The Java security properties file is located in

     * the file named <JAVA_HOME>/lib/security/java.security.

     * <JAVA_HOME> 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 "LDAP"

     * 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;

    }

}