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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * version 2 for more details (a copy is included in the LICENSE file that
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package sun.security.x509;

import java.io.IOException;

import sun.security.util.*;

/**
 * This class defines the certificate extension which specifies the
 * Policy constraints.
 * <p>
 * The policy constraints extension can be used in certificates issued
 * to CAs. The policy constraints extension constrains path validation
 * in two ways. It can be used to prohibit policy mapping or require
 * that each certificate in a path contain an acceptable policy
 * identifier.<p>
 * The ASN.1 syntax for this is (IMPLICIT tagging is defined in the
 * module definition):
 * <pre>
 * PolicyConstraints ::= SEQUENCE {
 *     requireExplicitPolicy [0] SkipCerts OPTIONAL,
 *     inhibitPolicyMapping  [1] SkipCerts OPTIONAL
 * }
 * SkipCerts ::= INTEGER (0..MAX)
 * </pre>
 * @author Amit Kapoor
 * @author Hemma Prafullchandra
 * @see Extension
 */
public class PolicyConstraintsExtension extends Extension {

    public static final String NAME = "PolicyConstraints";

    private static final byte TAG_REQUIRE = 0;
    private static final byte TAG_INHIBIT = 1;

    private int require = -1;
    private int inhibit = -1;

    // Encode this extension value.
    private void encodeThis() {
        if (require == -1 && inhibit == -1) {
            this.extensionValue = null;
            return;
        }
        DerOutputStream tagged = new DerOutputStream();
        DerOutputStream seq = new DerOutputStream();

        if (require != -1) {
            DerOutputStream tmp = new DerOutputStream();
            tmp.putInteger(require);
            tagged.writeImplicit(DerValue.createTag(DerValue.TAG_CONTEXT,
                         false, TAG_REQUIRE), tmp);
        }
        if (inhibit != -1) {
            DerOutputStream tmp = new DerOutputStream();
            tmp.putInteger(inhibit);
            tagged.writeImplicit(DerValue.createTag(DerValue.TAG_CONTEXT,
                         false, TAG_INHIBIT), tmp);
        }
        seq.write(DerValue.tag_Sequence, tagged);
        this.extensionValue = seq.toByteArray();
    }

    /**
     * Create a PolicyConstraintsExtension object with both
     * require explicit policy and inhibit policy mapping. The
     * extension is marked non-critical.
     *
     * @param require require explicit policy (-1 for optional).
     * @param inhibit inhibit policy mapping (-1 for optional).
     */
    public PolicyConstraintsExtension(int require, int inhibit) {
        this(Boolean.TRUE, require, inhibit);
    }

    /**
     * Create a PolicyConstraintsExtension object with specified
     * criticality and both require explicit policy and inhibit
     * policy mapping. At least one should be provided (not -1).
     *
     * @param critical true if the extension is to be treated as critical.
     * @param require require explicit policy (-1 for optional).
     * @param inhibit inhibit policy mapping (-1 for optional).
     */
    public PolicyConstraintsExtension(Boolean critical, int require, int inhibit) {
        if (require == -1 && inhibit == -1) {
            throw new IllegalArgumentException(
                    "require and inhibit cannot both be -1");
        }
        this.require = require;
        this.inhibit = inhibit;
        this.extensionId = PKIXExtensions.PolicyConstraints_Id;
        this.critical = critical.booleanValue();
        encodeThis();
    }

    /**
     * Create the extension from its DER encoded value and criticality.
     *
     * @param critical true if the extension is to be treated as critical.
     * @param value an array of DER encoded bytes of the actual value.
     * @exception ClassCastException if value is not an array of bytes
     * @exception IOException on error.
     */
    public PolicyConstraintsExtension(Boolean critical, Object value)
    throws IOException {
        this.extensionId = PKIXExtensions.PolicyConstraints_Id;
        this.critical = critical.booleanValue();

        this.extensionValue = (byte[]) value;
        DerValue val = new DerValue(this.extensionValue);
        if (val.tag != DerValue.tag_Sequence) {
            throw new IOException("Sequence tag missing for PolicyConstraint.");
        }
        DerInputStream in = val.data;
        while (in != null && in.available() != 0) {
            DerValue next = in.getDerValue();

            if (next.isContextSpecific(TAG_REQUIRE) && !next.isConstructed()) {
                if (this.require != -1)
                    throw new IOException("Duplicate requireExplicitPolicy " +
                          "found in the PolicyConstraintsExtension");
                next.resetTag(DerValue.tag_Integer);
                this.require = next.getInteger();

            } else if (next.isContextSpecific(TAG_INHIBIT) &&
                       !next.isConstructed()) {
                if (this.inhibit != -1)
                    throw new IOException("Duplicate inhibitPolicyMapping " +
                          "found in the PolicyConstraintsExtension");
                next.resetTag(DerValue.tag_Integer);
                this.inhibit = next.getInteger();
            } else
                throw new IOException("Invalid encoding of PolicyConstraint");
        }
    }

    /**
     * Return the extension as user readable string.
     */
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append(super.toString())
            .append("PolicyConstraints: [")
            .append("  Require: ");
        if (require == -1) {
            sb.append("unspecified;");
        } else {
            sb.append(require)
                .append(';');
        }
        sb.append("\tInhibit: ");
        if (inhibit == -1) {
            sb.append("unspecified");
        } else {
            sb.append(inhibit);
        }
        sb.append(" ]\n");
        return sb.toString();
    }

    /**
     * Write the extension to the DerOutputStream.
     *
     * @param out the DerOutputStream to write the extension to.
     */
    @Override
    public void encode(DerOutputStream out) {
        if (extensionValue == null) {
          extensionId = PKIXExtensions.PolicyConstraints_Id;
          critical = true;
          encodeThis();
        }
        super.encode(out);
    }

    public int getRequire() {
        return require;
    }

    public int getInhibit() {
        return inhibit;
    }

    /**
     * Return the name of this extension.
     */
    @Override
    public String getName() {
        return NAME;
    }
}
