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	/*
	* Copyright (c) 1997, 2017, 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.security.cert.CertificateException;
	import java.security.cert.X509Certificate;
	import java.util.*;

	import javax.security.auth.x500.X500Principal;

	import sun.net.util.IPAddressUtil;
	import sun.security.util.*;
	import sun.security.pkcs.PKCS9Attribute;

	/**
	* This class defines the Name Constraints Extension.
	* <p>
	* The name constraints extension provides permitted and excluded
	* subtrees that place restrictions on names that may be included within
	* a certificate issued by a given CA. Restrictions may apply to the
	* subject distinguished name or subject alternative names. Any name
	* matching a restriction in the excluded subtrees field is invalid
	* regardless of information appearing in the permitted subtrees.
	* <p>
	* The ASN.1 syntax for this is:
	* <pre>
	* NameConstraints ::= SEQUENCE {
	* permittedSubtrees [0] GeneralSubtrees OPTIONAL,
	* excludedSubtrees [1] GeneralSubtrees OPTIONAL
	* }
	* GeneralSubtrees ::= SEQUENCE SIZE (1..MAX) OF GeneralSubtree
	* </pre>
	*
	* @author Amit Kapoor
	* @author Hemma Prafullchandra
	* @see Extension
	* @see CertAttrSet
	*/
	public class NameConstraintsExtension extends Extension
	implements CertAttrSet<String>, Cloneable {
	/**
	* 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.NameConstraints";
	/**
	* Attribute names.
	*/
	public static final String NAME = "NameConstraints";
	public static final String PERMITTED_SUBTREES = "permitted_subtrees";
	public static final String EXCLUDED_SUBTREES = "excluded_subtrees";

	// Private data members
	private static final byte TAG_PERMITTED = 0;
	private static final byte TAG_EXCLUDED = 1;

	private GeneralSubtrees permitted = null;
	private GeneralSubtrees excluded = null;

	private boolean hasMin;
	private boolean hasMax;
	private boolean minMaxValid = false;

	// Recalculate hasMin and hasMax flags.
	private void calcMinMax() throws IOException {
	hasMin = false;
	hasMax = false;
	if (excluded != null) {
	for (int i = 0; i < excluded.size(); i++) {
	GeneralSubtree subtree = excluded.get(i);
	if (subtree.getMinimum() != 0)
	hasMin = true;
	if (subtree.getMaximum() != -1)
	hasMax = true;
	}
	}

	if (permitted != null) {
	for (int i = 0; i < permitted.size(); i++) {
	GeneralSubtree subtree = permitted.get(i);
	if (subtree.getMinimum() != 0)
	hasMin = true;
	if (subtree.getMaximum() != -1)
	hasMax = true;
	}
	}
	minMaxValid = true;
	}

	// Encode this extension value.
	private void encodeThis() throws IOException {
	minMaxValid = false;
	if (permitted == null && excluded == null) {
	this.extensionValue = null;
	return;
	}
	DerOutputStream seq = new DerOutputStream();

	DerOutputStream tagged = new DerOutputStream();
	if (permitted != null) {
	DerOutputStream tmp = new DerOutputStream();
	permitted.encode(tmp);
	tagged.writeImplicit(DerValue.createTag(DerValue.TAG_CONTEXT,
	true, TAG_PERMITTED), tmp);
	}
	if (excluded != null) {
	DerOutputStream tmp = new DerOutputStream();
	excluded.encode(tmp);
	tagged.writeImplicit(DerValue.createTag(DerValue.TAG_CONTEXT,
	true, TAG_EXCLUDED), tmp);
	}
	seq.write(DerValue.tag_Sequence, tagged);
	this.extensionValue = seq.toByteArray();
	}

	/**
	* The default constructor for this class. Both parameters
	* are optional and can be set to null. The extension criticality
	* is set to true.
	*
	* @param permitted the permitted GeneralSubtrees (null for optional).
	* @param excluded the excluded GeneralSubtrees (null for optional).
	*/
	public NameConstraintsExtension(GeneralSubtrees permitted,
	GeneralSubtrees excluded)
	throws IOException {
	this.permitted = permitted;
	this.excluded = excluded;

	this.extensionId = PKIXExtensions.NameConstraints_Id;
	this.critical = true;
	encodeThis();
	}

	/**
	* Create the extension from the passed DER encoded value.
	*
	* @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 NameConstraintsExtension(Boolean critical, Object value)
	throws IOException {
	this.extensionId = PKIXExtensions.NameConstraints_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 for" +
	" NameConstraintsExtension.");
	}

	// NB. this is always encoded with the IMPLICIT tag
	// The checks only make sense if we assume implicit tagging,
	// with explicit tagging the form is always constructed.
	// Note that all the fields in NameConstraints are defined as
	// being OPTIONAL, i.e., there could be an empty SEQUENCE, resulting
	// in val.data being null.
	if (val.data == null)
	return;
	while (val.data.available() != 0) {
	DerValue opt = val.data.getDerValue();

	if (opt.isContextSpecific(TAG_PERMITTED) && opt.isConstructed()) {
	if (permitted != null) {
	throw new IOException("Duplicate permitted " +
	"GeneralSubtrees in NameConstraintsExtension.");
	}
	opt.resetTag(DerValue.tag_Sequence);
	permitted = new GeneralSubtrees(opt);

	} else if (opt.isContextSpecific(TAG_EXCLUDED) &&
	opt.isConstructed()) {
	if (excluded != null) {
	throw new IOException("Duplicate excluded " +
	"GeneralSubtrees in NameConstraintsExtension.");
	}
	opt.resetTag(DerValue.tag_Sequence);
	excluded = new GeneralSubtrees(opt);
	} else
	throw new IOException("Invalid encoding of " +
	"NameConstraintsExtension.");
	}
	minMaxValid = false;
	}

	/**
	* Return the printable string.
	*/
	public String toString() {
	StringBuilder sb = new StringBuilder();
	sb.append(super.toString())
	.append("NameConstraints: [");
	if (permitted != null) {
	sb.append("\n Permitted:")
	.append(permitted);
	}
	if (excluded != null) {
	sb.append("\n Excluded:")
	.append(excluded);
	}
	sb.append(" ]\n");
	return sb.toString();
	}

	/**
	* Write the extension to the OutputStream.
	*
	* @param out the OutputStream to write the extension to.
	* @exception IOException on encoding errors.
	*/
	public void encode(OutputStream out) throws IOException {
	DerOutputStream tmp = new DerOutputStream();
	if (this.extensionValue == null) {
	this.extensionId = PKIXExtensions.NameConstraints_Id;
	this.critical = true;
	encodeThis();
	}
	super.encode(tmp);
	out.write(tmp.toByteArray());
	}

	/**
	* Set the attribute value.
	*/
	public void set(String name, Object obj) throws IOException {
	if (name.equalsIgnoreCase(PERMITTED_SUBTREES)) {
	if (!(obj instanceof GeneralSubtrees)) {
	throw new IOException("Attribute value should be"
	+ " of type GeneralSubtrees.");
	}
	permitted = (GeneralSubtrees)obj;
	} else if (name.equalsIgnoreCase(EXCLUDED_SUBTREES)) {
	if (!(obj instanceof GeneralSubtrees)) {
	throw new IOException("Attribute value should be "
	+ "of type GeneralSubtrees.");
	}
	excluded = (GeneralSubtrees)obj;
	} else {
	throw new IOException("Attribute name not recognized by " +
	"CertAttrSet:NameConstraintsExtension.");
	}
	encodeThis();
	}

	/**
	* Get the attribute value.
	*/
	public GeneralSubtrees get(String name) throws IOException {
	if (name.equalsIgnoreCase(PERMITTED_SUBTREES)) {
	return (permitted);
	} else if (name.equalsIgnoreCase(EXCLUDED_SUBTREES)) {
	return (excluded);
	} else {
	throw new IOException("Attribute name not recognized by " +
	"CertAttrSet:NameConstraintsExtension.");
	}
	}

	/**
	* Delete the attribute value.
	*/
	public void delete(String name) throws IOException {
	if (name.equalsIgnoreCase(PERMITTED_SUBTREES)) {
	permitted = null;
	} else if (name.equalsIgnoreCase(EXCLUDED_SUBTREES)) {
	excluded = null;
	} else {
	throw new IOException("Attribute name not recognized by " +
	"CertAttrSet:NameConstraintsExtension.");
	}
	encodeThis();
	}

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

	return (elements.elements());
	}

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

	/**
	* Merge additional name constraints with existing ones.
	* This function is used in certification path processing
	* to accumulate name constraints from successive certificates
	* in the path. Note that NameConstraints can never be
	* expanded by a merge, just remain constant or become more
	* limiting.
	* <p>
	* IETF RFC2459 specifies the processing of Name Constraints as
	* follows:
	* <p>
	* (j) If permittedSubtrees is present in the certificate, set the
	* constrained subtrees state variable to the intersection of its
	* previous value and the value indicated in the extension field.
	* <p>
	* (k) If excludedSubtrees is present in the certificate, set the
	* excluded subtrees state variable to the union of its previous
	* value and the value indicated in the extension field.
	*
	* @param newConstraints additional NameConstraints to be applied
	* @throws IOException on error
	*/
	public void merge(NameConstraintsExtension newConstraints)
	throws IOException {

	if (newConstraints == null) {
	// absence of any explicit constraints implies unconstrained
	return;
	}

	/*
	* If excludedSubtrees is present in the certificate, set the
	* excluded subtrees state variable to the union of its previous
	* value and the value indicated in the extension field.
	*/

	GeneralSubtrees newExcluded = newConstraints.get(EXCLUDED_SUBTREES);
	if (excluded == null) {
	excluded = (newExcluded != null) ?
	(GeneralSubtrees)newExcluded.clone() : null;
	} else {
	if (newExcluded != null) {
	// Merge new excluded with current excluded (union)
	excluded.union(newExcluded);
	}
	}

	/*
	* If permittedSubtrees is present in the certificate, set the
	* constrained subtrees state variable to the intersection of its
	* previous value and the value indicated in the extension field.
	*/

	GeneralSubtrees newPermitted = newConstraints.get(PERMITTED_SUBTREES);
	if (permitted == null) {
	permitted = (newPermitted != null) ?
	(GeneralSubtrees)newPermitted.clone() : null;
	} else {
	if (newPermitted != null) {
	// Merge new permitted with current permitted (intersection)
	newExcluded = permitted.intersect(newPermitted);

	// Merge new excluded subtrees to current excluded (union)
	if (newExcluded != null) {
	if (excluded != null) {
	excluded.union(newExcluded);
	} else {
	excluded = (GeneralSubtrees)newExcluded.clone();
	}
	}
	}
	}

	// Optional optimization: remove permitted subtrees that are excluded.
	// This is not necessary for algorithm correctness, but it makes
	// subsequent operations on the NameConstraints faster and require
	// less space.
	if (permitted != null) {
	permitted.reduce(excluded);
	}

	// The NameConstraints have been changed, so re-encode them. Methods in
	// this class assume that the encodings have already been done.
	encodeThis();

	}

	/**
	* check whether a certificate conforms to these NameConstraints.
	* This involves verifying that the subject name and subjectAltName
	* extension (critical or noncritical) is consistent with the permitted
	* subtrees state variables. Also verify that the subject name and
	* subjectAltName extension (critical or noncritical) is consistent with
	* the excluded subtrees state variables.
	*
	* @param cert X509Certificate to be verified
	* @return true if certificate verifies successfully
	* @throws IOException on error
	*/
	public boolean verify(X509Certificate cert) throws IOException {

	if (cert == null) {
	throw new IOException("Certificate is null");
	}

	// Calculate hasMin and hasMax booleans (if necessary)
	if (!minMaxValid) {
	calcMinMax();
	}

	if (hasMin) {
	throw new IOException("Non-zero minimum BaseDistance in"
	+ " name constraints not supported");
	}

	if (hasMax) {
	throw new IOException("Maximum BaseDistance in"
	+ " name constraints not supported");
	}

	X500Principal subjectPrincipal = cert.getSubjectX500Principal();
	X500Name subject = X500Name.asX500Name(subjectPrincipal);

	// Check subject as an X500Name
	if (subject.isEmpty() == false) {
	if (verify(subject) == false) {
	return false;
	}
	}

	GeneralNames altNames = null;
	// extract altNames
	try {
	// extract extensions, if any, from certInfo
	// following returns null if certificate contains no extensions
	X509CertImpl certImpl = X509CertImpl.toImpl(cert);
	SubjectAlternativeNameExtension altNameExt =
	certImpl.getSubjectAlternativeNameExtension();
	if (altNameExt != null) {
	// extract altNames from extension; this call does not
	// return an IOException on null altnames
	altNames = altNameExt.get(
	SubjectAlternativeNameExtension.SUBJECT_NAME);
	}
	} catch (CertificateException ce) {
	throw new IOException("Unable to extract extensions from " +
	"certificate: " + ce.getMessage());
	}

	if (altNames == null) {
	altNames = new GeneralNames();

	// RFC 5280 4.2.1.10:
	// When constraints are imposed on the rfc822Name name form,
	// but the certificate does not include a subject alternative name,
	// the rfc822Name constraint MUST be applied to the attribute of
	// type emailAddress in the subject distinguished name.
	for (AVA ava : subject.allAvas()) {
	ObjectIdentifier attrOID = ava.getObjectIdentifier();
	if (attrOID.equals(PKCS9Attribute.EMAIL_ADDRESS_OID)) {
	String attrValue = ava.getValueString();
	if (attrValue != null) {
	try {
	altNames.add(new GeneralName(
	new RFC822Name(attrValue)));
	} catch (IOException ioe) {
	continue;
	}
	}
	}
	}
	}

	// If there is no IPAddressName or DNSName in subjectAlternativeNames,
	// see if the last CN inside subjectName can be used instead.
	DerValue derValue = subject.findMostSpecificAttribute
	(X500Name.commonName_oid);
	String cn = derValue == null ? null : derValue.getAsString();

	if (cn != null) {
	try {
	if (IPAddressUtil.isIPv4LiteralAddress(cn) \|\|
	IPAddressUtil.isIPv6LiteralAddress(cn)) {
	if (!hasNameType(altNames, GeneralNameInterface.NAME_IP)) {
	altNames.add(new GeneralName(new IPAddressName(cn)));
	}
	} else {
	if (!hasNameType(altNames, GeneralNameInterface.NAME_DNS)) {
	altNames.add(new GeneralName(new DNSName(cn)));
	}
	}
	} catch (IOException ioe) {
	// OK, cn is neither IP nor DNS
	}
	}

	// verify each subjectAltName
	for (int i = 0; i < altNames.size(); i++) {
	GeneralNameInterface altGNI = altNames.get(i).getName();
	if (!verify(altGNI)) {
	return false;
	}
	}

	// All tests passed.
	return true;
	}

	private static boolean hasNameType(GeneralNames names, int type) {
	for (GeneralName name : names.names()) {
	if (name.getType() == type) {
	return true;
	}
	}
	return false;
	}

	/**
	* check whether a name conforms to these NameConstraints.
	* This involves verifying that the name is consistent with the
	* permitted and excluded subtrees variables.
	*
	* @param name GeneralNameInterface name to be verified
	* @return true if certificate verifies successfully
	* @throws IOException on error
	*/
	public boolean verify(GeneralNameInterface name) throws IOException {
	if (name == null) {
	throw new IOException("name is null");
	}

	// Verify that the name is consistent with the excluded subtrees
	if (excluded != null && excluded.size() > 0) {

	for (int i = 0; i < excluded.size(); i++) {
	GeneralSubtree gs = excluded.get(i);
	if (gs == null)
	continue;
	GeneralName gn = gs.getName();
	if (gn == null)
	continue;
	GeneralNameInterface exName = gn.getName();
	if (exName == null)
	continue;

	// if name matches or narrows any excluded subtree,
	// return false
	switch (exName.constrains(name)) {
	case GeneralNameInterface.NAME_DIFF_TYPE:
	case GeneralNameInterface.NAME_WIDENS: // name widens excluded
	case GeneralNameInterface.NAME_SAME_TYPE:
	break;
	case GeneralNameInterface.NAME_MATCH:
	case GeneralNameInterface.NAME_NARROWS: // subject name excluded
	return false;
	}
	}
	}

	// Verify that the name is consistent with the permitted subtrees
	if (permitted != null && permitted.size() > 0) {

	boolean sameType = false;

	for (int i = 0; i < permitted.size(); i++) {
	GeneralSubtree gs = permitted.get(i);
	if (gs == null)
	continue;
	GeneralName gn = gs.getName();
	if (gn == null)
	continue;
	GeneralNameInterface perName = gn.getName();
	if (perName == null)
	continue;

	// if Name matches any type in permitted,
	// and Name does not match or narrow some permitted subtree,
	// return false
	switch (perName.constrains(name)) {
	case GeneralNameInterface.NAME_DIFF_TYPE:
	continue; // continue checking other permitted names
	case GeneralNameInterface.NAME_WIDENS: // name widens permitted
	case GeneralNameInterface.NAME_SAME_TYPE:
	sameType = true;
	continue; // continue to look for a match or narrow
	case GeneralNameInterface.NAME_MATCH:
	case GeneralNameInterface.NAME_NARROWS:
	// name narrows permitted
	return true; // name is definitely OK, so break out of loop
	}
	}
	if (sameType) {
	return false;
	}
	}
	return true;
	}

	/**
	* Clone all objects that may be modified during certificate validation.
	*/
	public Object clone() {
	try {
	NameConstraintsExtension newNCE =
	(NameConstraintsExtension) super.clone();

	if (permitted != null) {
	newNCE.permitted = (GeneralSubtrees) permitted.clone();
	}
	if (excluded != null) {
	newNCE.excluded = (GeneralSubtrees) excluded.clone();
	}
	return newNCE;
	} catch (CloneNotSupportedException cnsee) {
	throw new RuntimeException("CloneNotSupportedException while " +
	"cloning NameConstraintsException. This should never happen.");
	}
	}
	}

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