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	/*
	* Copyright (c) 1997, 2021, 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
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package sun.security.x509;

	import java.io.IOException;
	import java.io.OutputStream;
	import java.util.Enumeration;

	import sun.security.util.*;

	/**
	* This class represents the Basic Constraints Extension.
	*
	* <p>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.
	*
	* <pre>
	* The ASN.1 syntax for this extension is:
	* BasicConstraints ::= SEQUENCE {
	* cA BOOLEAN DEFAULT FALSE,
	* pathLenConstraint INTEGER (0..MAX) OPTIONAL
	* }
	* </pre>
	* @author Amit Kapoor
	* @author Hemma Prafullchandra
	* @see CertAttrSet
	* @see Extension
	*/
	public class BasicConstraintsExtension extends Extension
	implements CertAttrSet<String> {
	/**
	* Identifier for this attribute, to be used with the
	* get, set, delete methods of Certificate, x509 type.
	*/
	public static final String IDENT = "x509.info.extensions.BasicConstraints";
	/**
	* Attribute names.
	*/
	public static final String NAME = "BasicConstraints";
	public static final String IS_CA = "is_ca";
	public static final String PATH_LEN = "path_len";

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

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

	if (ca) {
	tmp.putBoolean(ca);
	// 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) throws IOException {
	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)
	throws IOException {
	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.
	*/
	public void encode(OutputStream out) throws IOException {
	DerOutputStream tmp = new DerOutputStream();
	if (extensionValue == null) {
	this.extensionId = PKIXExtensions.BasicConstraints_Id;
	if (ca) {
	critical = true;
	} else {
	critical = false;
	}
	encodeThis();
	}
	super.encode(tmp);

	out.write(tmp.toByteArray());
	}

	/**
	* Set the attribute value.
	*/
	public void set(String name, Object obj) throws IOException {
	if (name.equalsIgnoreCase(IS_CA)) {
	if (!(obj instanceof Boolean)) {
	throw new IOException("Attribute value should be of type Boolean.");
	}
	ca = ((Boolean)obj).booleanValue();
	} else if (name.equalsIgnoreCase(PATH_LEN)) {
	if (!(obj instanceof Integer)) {
	throw new IOException("Attribute value should be of type Integer.");
	}
	pathLen = ((Integer)obj).intValue();
	} else {
	throw new IOException("Attribute name not recognized by " +
	"CertAttrSet:BasicConstraints.");
	}
	encodeThis();
	}

	/**
	* Get the attribute value.
	*/
	public Object get(String name) throws IOException {
	if (name.equalsIgnoreCase(IS_CA)) {
	return (Boolean.valueOf(ca));
	} else if (name.equalsIgnoreCase(PATH_LEN)) {
	return (Integer.valueOf(pathLen));
	} else {
	throw new IOException("Attribute name not recognized by " +
	"CertAttrSet:BasicConstraints.");
	}
	}

	/**
	* Delete the attribute value.
	*/
	public void delete(String name) throws IOException {
	if (name.equalsIgnoreCase(IS_CA)) {
	ca = false;
	} else if (name.equalsIgnoreCase(PATH_LEN)) {
	pathLen = -1;
	} else {
	throw new IOException("Attribute name not recognized by " +
	"CertAttrSet:BasicConstraints.");
	}
	encodeThis();
	}

	/**
	* Return an enumeration of names of attributes existing within this
	* attribute.
	*/
	public Enumeration<String> getElements() {
	AttributeNameEnumeration elements = new AttributeNameEnumeration();
	elements.addElement(IS_CA);
	elements.addElement(PATH_LEN);

	return (elements.elements());
	}

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

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