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package java.security.cert;

import java.io.IOException;

import sun.security.util.HexDumpEncoder;
import sun.security.util.DerValue;

/**
 * An immutable policy qualifier represented by the ASN.1 PolicyQualifierInfo
 * structure.
 *
 * <p>The ASN.1 definition is as follows:
 * <pre>
 *   PolicyQualifierInfo ::= SEQUENCE {
 *        policyQualifierId       PolicyQualifierId,
 *        qualifier               ANY DEFINED BY policyQualifierId }
 * </pre>
 * <p>
 * A certificate policies extension, if present in an X.509 version 3
 * certificate, contains a sequence of one or more policy information terms,
 * each of which consists of an object identifier (OID) and optional
 * qualifiers. In an end-entity certificate, these policy information terms
 * indicate the policy under which the certificate has been issued and the
 * purposes for which the certificate may be used. In a CA certificate, these
 * policy information terms limit the set of policies for certification paths
 * which include this certificate.
 * <p>
 * A {@code Set} of {@code PolicyQualifierInfo} objects are returned
 * by the {@link PolicyNode#getPolicyQualifiers PolicyNode.getPolicyQualifiers}
 * method. This allows applications with specific policy requirements to
 * process and validate each policy qualifier. Applications that need to
 * process policy qualifiers should explicitly set the
 * {@code policyQualifiersRejected} flag to false (by calling the
 * {@link PKIXParameters#setPolicyQualifiersRejected
 * PKIXParameters.setPolicyQualifiersRejected} method) before validating
 * a certification path.
 *
 * <p>Note that the PKIX certification path validation algorithm specifies
 * that any policy qualifier in a certificate policies extension that is
 * marked critical must be processed and validated. Otherwise, the
 * certification path must be rejected. If the
 * {@code policyQualifiersRejected} flag is set to false, it is up to
 * the application to validate all policy qualifiers in this manner in order
 * to be PKIX compliant.
 *
 * <p><b>Concurrent Access</b>
 *
 * <p>All {@code PolicyQualifierInfo} objects must be immutable and
 * thread-safe. That is, multiple threads may concurrently invoke the
 * methods defined in this class on a single {@code PolicyQualifierInfo}
 * object (or more than one) with no ill effects. Requiring
 * {@code PolicyQualifierInfo} objects to be immutable and thread-safe
 * allows them to be passed around to various pieces of code without
 * worrying about coordinating access.
 *
 * @author      seth proctor
 * @author      Sean Mullan
 * @since       1.4
 */
public class PolicyQualifierInfo {

    private final byte [] mEncoded;
    private final String mId;
    private final byte [] mData;
    private String pqiString;

    /**
     * Creates an instance of {@code PolicyQualifierInfo} from the
     * encoded bytes. The encoded byte array is copied on construction.
     *
     * @param encoded a byte array containing the qualifier in DER encoding
     * @throws    IOException thrown if the byte array does not represent a
     * valid and parsable policy qualifier
     */
    public PolicyQualifierInfo(byte[] encoded) throws IOException {
        mEncoded = encoded.clone();

        DerValue val = new DerValue(mEncoded);
        if (val.tag != DerValue.tag_Sequence)
            throw new IOException("Invalid encoding for PolicyQualifierInfo");

        mId = (val.data.getDerValue()).getOID().toString();
        byte [] tmp = val.data.toByteArray();
        if (tmp == null) {
            mData = null;
        } else {
            mData = new byte[tmp.length];
            System.arraycopy(tmp, 0, mData, 0, tmp.length);
        }
    }

    /**
     * Returns the {@code policyQualifierId} field of this
     * {@code PolicyQualifierInfo}. The {@code policyQualifierId}
     * is an Object Identifier (OID) represented by a set of nonnegative
     * integers separated by periods.
     *
     * @return the OID (never {@code null})
     */
    public final String getPolicyQualifierId() {
        return mId;
    }

    /**
     * Returns the ASN.1 DER encoded form of this
     * {@code PolicyQualifierInfo}.
     *
     * @return the ASN.1 DER encoded bytes (never {@code null}).
     * Note that a copy is returned, so the data is cloned each time
     * this method is called.
     */
    public final byte[] getEncoded() {
        return mEncoded.clone();
    }

    /**
     * Returns the ASN.1 DER encoded form of the {@code qualifier}
     * field of this {@code PolicyQualifierInfo}.
     *
     * @return the ASN.1 DER encoded bytes of the {@code qualifier}
     * field. Note that a copy is returned, so the data is cloned each
     * time this method is called.
     */
    public final byte[] getPolicyQualifier() {
        return (mData == null ? null : mData.clone());
    }

    /**
     * Return a printable representation of this
     * {@code PolicyQualifierInfo}.
     *
     * @return a {@code String} describing the contents of this
     *         {@code PolicyQualifierInfo}
     */
    public String toString() {
        if (pqiString != null)
            return pqiString;
        HexDumpEncoder enc = new HexDumpEncoder();
        pqiString = "PolicyQualifierInfo: [\n" +
                "  qualifierID: " + mId + "\n" +
                "  qualifier: " +
                (mData == null ? "null" : enc.encodeBuffer(mData)) + "\n" +
                "]";
        return pqiString;
    }
}
