src/java.base/share/classes/sun/security/validator/TrustStoreUtil.java

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
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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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 * 2 along with this work; if not, write to the Free Software Foundation,
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 *
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package sun.security.validator;

import java.util.Set;
import java.util.HashSet;
import java.util.Collections;
import java.util.Enumeration;

import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.cert.X509Certificate;
import java.security.cert.Certificate;

/**
 * Collection of static utility methods related to trust anchor KeyStores.
 *
 * @author Andreas Sterbenz
 */
public final class TrustStoreUtil {

    private TrustStoreUtil() {
        // empty
    }

    /**
     * Return an unmodifiable Set with all trusted X509Certificates contained
     * in the specified KeyStore.
     */
    public static Set<X509Certificate> getTrustedCerts(KeyStore ks) {
        Set<X509Certificate> set = new HashSet<>();
        try {
            for (Enumeration<String> e = ks.aliases(); e.hasMoreElements(); ) {
                String alias = e.nextElement();
                if (ks.isCertificateEntry(alias)) {
                    Certificate cert = ks.getCertificate(alias);
                    if (cert instanceof X509Certificate) {
                        set.add((X509Certificate)cert);
                    }
                } else if (ks.isKeyEntry(alias)) {
                    Certificate[] certs = ks.getCertificateChain(alias);
                    if ((certs != null) && (certs.length > 0) &&
                            (certs[0] instanceof X509Certificate)) {
                        set.add((X509Certificate)certs[0]);
                    }
                }
            }
        } catch (KeyStoreException e) {
            // ignore
            //
            // This should be rare, but better to log this in the future.
        }

        return Collections.unmodifiableSet(set);
    }
}