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A Java security provider for supporting ShangMi algorithms in public key infrastructure
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/*
 * Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * 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
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * 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).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package com.tencent.kona.sun.security.x509;

import java.io.IOException;

import com.tencent.kona.sun.security.util.DerOutputStream;
import com.tencent.kona.sun.security.util.DerValue;

/**
 * This class represents the Basic Constraints Extension.
 *
 * The basic constraints extension identifies whether the subject of the
 * certificate is a CA and how deep a certification path may exist
 * through that CA.
 *
 * 
 * The ASN.1 syntax for this extension is:
 * BasicConstraints ::= SEQUENCE {
 *     cA                BOOLEAN DEFAULT FALSE,
 *     pathLenConstraint INTEGER (0..MAX) OPTIONAL
 * }
 * 
 * @author Amit Kapoor
 * @author Hemma Prafullchandra
 * @see Extension
 */
public class BasicConstraintsExtension extends Extension {

    public static final String NAME = "BasicConstraints";

    // Private data members
    private boolean     ca = false;
    private int pathLen = -1;

    // Encode this extension value
    private void encodeThis() {
        DerOutputStream out = new DerOutputStream();
        DerOutputStream tmp = new DerOutputStream();

        if (ca) {
            tmp.putBoolean(true);
            // Only encode pathLen when ca == true
            if (pathLen >= 0) {
                tmp.putInteger(pathLen);
            }
        }
        out.write(DerValue.tag_Sequence, tmp);
        this.extensionValue = out.toByteArray();
    }

    /**
     * Default constructor for this object. The extension is marked
     * critical if the ca flag is true, false otherwise.
     *
     * @param ca true, if the subject of the Certificate is a CA.
     * @param len specifies the depth of the certification path.
     */
    public BasicConstraintsExtension(boolean ca, int len) {
        this(Boolean.valueOf(ca), ca, len);
    }

    /**
     * Constructor for this object with specified criticality.
     *
     * @param critical true, if the extension should be marked critical
     * @param ca true, if the subject of the Certificate is a CA.
     * @param len specifies the depth of the certification path.
     */
    public BasicConstraintsExtension(Boolean critical, boolean ca, int len) {
        this.ca = ca;
        this.pathLen = len;
        this.extensionId = PKIXExtensions.BasicConstraints_Id;
        this.critical = critical.booleanValue();
        encodeThis();
    }

    /**
     * Create the extension from the passed DER encoded value of the same.
     *
     * @param critical flag indicating if extension is critical or not
     * @param value an array containing the DER encoded bytes of the extension.
     * @exception ClassCastException if value is not an array of bytes
     * @exception IOException on error.
     */
    public BasicConstraintsExtension(Boolean critical, Object value)
            throws IOException
    {
        this.extensionId = PKIXExtensions.BasicConstraints_Id;
        this.critical = critical.booleanValue();

        this.extensionValue = (byte[]) value;
        DerValue val = new DerValue(this.extensionValue);
        if (val.tag != DerValue.tag_Sequence) {
            throw new IOException("Invalid encoding of BasicConstraints");
        }

        if (val.data == null || val.data.available() == 0) {
            // non-CA cert ("cA" field is FALSE by default), return -1
            return;
        }
        DerValue opt = val.data.getDerValue();
        if (opt.tag != DerValue.tag_Boolean) {
            // non-CA cert ("cA" field is FALSE by default), return -1
            return;
        }

        this.ca = opt.getBoolean();
        if (val.data.available() == 0) {
            // From PKIX profile:
            // Where pathLenConstraint does not appear, there is no
            // limit to the allowed length of the certification path.
            this.pathLen = Integer.MAX_VALUE;
            return;
        }

        opt = val.data.getDerValue();
        if (opt.tag != DerValue.tag_Integer) {
            throw new IOException("Invalid encoding of BasicConstraints");
        }
        this.pathLen = opt.getInteger();
        /*
         * Activate this check once again after PKIX profiling
         * is a standard and this check no longer imposes an
         * interoperability barrier.
         * if (ca) {
         *   if (!this.critical) {
         *   throw new IOException("Criticality cannot be false for CA.");
         *   }
         * }
         */
    }

    /**
     * Return user readable form of extension.
     */
    public String toString() {
        String pathLenAsString;
        if (pathLen < 0) {
            pathLenAsString = " undefined";
        } else if (pathLen == Integer.MAX_VALUE) {
            pathLenAsString = " no limit";
        } else {
            pathLenAsString = String.valueOf(pathLen);
        }
        return super.toString() +
                "BasicConstraints:[\n  CA:" + ca +
                "\n  PathLen:" + pathLenAsString +
                "\n]\n";
    }

    /**
     * Encode this extension value to the output stream.
     *
     * @param out the DerOutputStream to encode the extension to.
     */
    @Override
    public void encode(DerOutputStream out) {
        if (extensionValue == null) {
             this.extensionId = PKIXExtensions.BasicConstraints_Id;
             critical = ca;
             encodeThis();
         }
         super.encode(out);
    }

    public boolean isCa() {
        return ca;
    }

    public int getPathLen() {
        return pathLen;
    }

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