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	/*
	* Copyright (c) 2000, 2019, 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.provider.certpath;

	import java.io.ByteArrayInputStream;
	import java.io.ByteArrayOutputStream;
	import java.io.IOException;
	import java.io.InputStream;
	import java.security.cert.CertificateEncodingException;
	import java.security.cert.Certificate;
	import java.security.cert.CertificateException;
	import java.security.cert.CertificateFactory;
	import java.security.cert.CertPath;
	import java.security.cert.X509Certificate;
	import java.util.*;

	import sun.security.pkcs.ContentInfo;
	import sun.security.pkcs.PKCS7;
	import sun.security.pkcs.SignerInfo;
	import sun.security.x509.AlgorithmId;
	import sun.security.util.DerValue;
	import sun.security.util.DerOutputStream;
	import sun.security.util.DerInputStream;

	/**
	* A {@link java.security.cert.CertPath CertPath} (certification path)
	* consisting exclusively of
	* {@link java.security.cert.X509Certificate X509Certificate}s.
	* <p>
	* By convention, X.509 <code>CertPath</code>s are stored from target
	* to trust anchor.
	* That is, the issuer of one certificate is the subject of the following
	* one. However, unvalidated X.509 <code>CertPath</code>s may not follow
	* this convention. PKIX <code>CertPathValidator</code>s will detect any
	* departure from this convention and throw a
	* <code>CertPathValidatorException</code>.
	*
	* @author Yassir Elley
	* @since 1.4
	*/
	public class X509CertPath extends CertPath {

	@java.io.Serial
	private static final long serialVersionUID = 4989800333263052980L;

	/**
	* List of certificates in this chain
	*/
	@SuppressWarnings("serial") // Not statically typed as Serializable
	private List<X509Certificate> certs;

	/**
	* The names of our encodings. PkiPath is the default.
	*/
	private static final String COUNT_ENCODING = "count";
	private static final String PKCS7_ENCODING = "PKCS7";
	private static final String PKIPATH_ENCODING = "PkiPath";

	/**
	* List of supported encodings
	*/
	private static final Collection<String> encodingList;

	static {
	List<String> list = new ArrayList<>(2);
	list.add(PKIPATH_ENCODING);
	list.add(PKCS7_ENCODING);
	encodingList = Collections.unmodifiableCollection(list);
	}

	/**
	* Creates an <code>X509CertPath</code> from a <code>List</code> of
	* <code>X509Certificate</code>s.
	* <p>
	* The certificates are copied out of the supplied <code>List</code>
	* object.
	*
	* @param certs a <code>List</code> of <code>X509Certificate</code>s
	* @exception CertificateException if <code>certs</code> contains an element
	* that is not an <code>X509Certificate</code>
	*/
	@SuppressWarnings("unchecked")
	public X509CertPath(List<? extends Certificate> certs) throws CertificateException {
	super("X.509");

	// Ensure that the List contains only X509Certificates
	//
	// Note; The certs parameter is not necessarily to be of Certificate
	// for some old code. For compatibility, to make sure the exception
	// is CertificateException, rather than ClassCastException, please
	// don't use
	// for (Certificate obj : certs)
	for (Object obj : certs) {
	if (obj instanceof X509Certificate == false) {
	throw new CertificateException
	("List is not all X509Certificates: "
	+ obj.getClass().getName());
	}
	}

	// Assumes that the resulting List is thread-safe. This is true
	// because we ensure that it cannot be modified after construction
	// and the methods in the Sun JDK 1.4 implementation of ArrayList that
	// allow read-only access are thread-safe.
	this.certs = Collections.unmodifiableList(
	new ArrayList<X509Certificate>((List<X509Certificate>)certs));
	}

	/**
	* Creates an <code>X509CertPath</code>, reading the encoded form
	* from an <code>InputStream</code>. The data is assumed to be in
	* the default encoding.
	*
	* @param is the <code>InputStream</code> to read the data from
	* @exception CertificateException if an exception occurs while decoding
	*/
	public X509CertPath(InputStream is) throws CertificateException {
	this(is, PKIPATH_ENCODING);
	}

	/**
	* Creates an <code>X509CertPath</code>, reading the encoded form
	* from an InputStream. The data is assumed to be in the specified
	* encoding.
	*
	* @param is the <code>InputStream</code> to read the data from
	* @param encoding the encoding used
	* @exception CertificateException if an exception occurs while decoding or
	* the encoding requested is not supported
	*/
	public X509CertPath(InputStream is, String encoding)
	throws CertificateException {
	super("X.509");

	switch (encoding) {
	case PKIPATH_ENCODING:
	certs = parsePKIPATH(is);
	break;
	case PKCS7_ENCODING:
	certs = parsePKCS7(is);
	break;
	default:
	throw new CertificateException("unsupported encoding");
	}
	}

	/**
	* Parse a PKIPATH format CertPath from an InputStream. Return an
	* unmodifiable List of the certificates.
	*
	* @param is the <code>InputStream</code> to read the data from
	* @return an unmodifiable List of the certificates
	* @exception CertificateException if an exception occurs
	*/
	private static List<X509Certificate> parsePKIPATH(InputStream is)
	throws CertificateException {
	List<X509Certificate> certList = null;
	CertificateFactory certFac = null;

	if (is == null) {
	throw new CertificateException("input stream is null");
	}

	try {
	DerInputStream dis = new DerInputStream(readAllBytes(is));
	DerValue[] seq = dis.getSequence(3);
	if (seq.length == 0) {
	return Collections.<X509Certificate>emptyList();
	}

	certFac = CertificateFactory.getInstance("X.509");
	certList = new ArrayList<X509Certificate>(seq.length);

	// append certs in reverse order (target to trust anchor)
	for (int i = seq.length-1; i >= 0; i--) {
	certList.add((X509Certificate)certFac.generateCertificate
	(new ByteArrayInputStream(seq[i].toByteArray())));
	}

	return Collections.unmodifiableList(certList);

	} catch (IOException ioe) {
	throw new CertificateException("IOException parsing PkiPath data: "
	+ ioe, ioe);
	}
	}

	/**
	* Parse a PKCS#7 format CertPath from an InputStream. Return an
	* unmodifiable List of the certificates.
	*
	* @param is the <code>InputStream</code> to read the data from
	* @return an unmodifiable List of the certificates
	* @exception CertificateException if an exception occurs
	*/
	private static List<X509Certificate> parsePKCS7(InputStream is)
	throws CertificateException {
	List<X509Certificate> certList;

	if (is == null) {
	throw new CertificateException("input stream is null");
	}

	try {
	if (is.markSupported() == false) {
	// Copy the entire input stream into an InputStream that does
	// support mark
	is = new ByteArrayInputStream(readAllBytes(is));
	}
	PKCS7 pkcs7 = new PKCS7(is);

	X509Certificate[] certArray = pkcs7.getCertificates();
	// certs are optional in PKCS #7
	if (certArray != null) {
	certList = Arrays.asList(certArray);
	} else {
	// no certs provided
	certList = new ArrayList<X509Certificate>(0);
	}
	} catch (IOException ioe) {
	throw new CertificateException("IOException parsing PKCS7 data: " +
	ioe);
	}
	// Assumes that the resulting List is thread-safe. This is true
	// because we ensure that it cannot be modified after construction
	// and the methods in the Sun JDK 1.4 implementation of ArrayList that
	// allow read-only access are thread-safe.
	return Collections.unmodifiableList(certList);
	}

	/*
	* Reads the entire contents of an InputStream into a byte array.
	*
	* @param is the InputStream to read from
	* @return the bytes read from the InputStream
	*/
	private static byte[] readAllBytes(InputStream is) throws IOException {
	byte[] buffer = new byte[8192];
	ByteArrayOutputStream baos = new ByteArrayOutputStream(2048);
	int n;
	while ((n = is.read(buffer)) != -1) {
	baos.write(buffer, 0, n);
	}
	return baos.toByteArray();
	}

	/**
	* Returns the encoded form of this certification path, using the
	* default encoding.
	*
	* @return the encoded bytes
	* @exception CertificateEncodingException if an encoding error occurs
	*/
	@Override
	public byte[] getEncoded() throws CertificateEncodingException {
	// @@@ Should cache the encoded form
	return encodePKIPATH();
	}

	/**
	* Encode the CertPath using PKIPATH format.
	*
	* @return a byte array containing the binary encoding of the PkiPath object
	* @exception CertificateEncodingException if an exception occurs
	*/
	private byte[] encodePKIPATH() throws CertificateEncodingException {

	ListIterator<X509Certificate> li = certs.listIterator(certs.size());
	try {
	DerOutputStream bytes = new DerOutputStream();
	// encode certs in reverse order (trust anchor to target)
	// according to PkiPath format
	while (li.hasPrevious()) {
	X509Certificate cert = li.previous();
	// check for duplicate cert
	if (certs.lastIndexOf(cert) != certs.indexOf(cert)) {
	throw new CertificateEncodingException
	("Duplicate Certificate");
	}
	// get encoded certificates
	byte[] encoded = cert.getEncoded();
	bytes.write(encoded);
	}

	// Wrap the data in a SEQUENCE
	DerOutputStream derout = new DerOutputStream();
	derout.write(DerValue.tag_SequenceOf, bytes);
	return derout.toByteArray();

	} catch (IOException ioe) {
	throw new CertificateEncodingException("IOException encoding " +
	"PkiPath data: " + ioe, ioe);
	}
	}

	/**
	* Encode the CertPath using PKCS#7 format.
	*
	* @return a byte array containing the binary encoding of the PKCS#7 object
	* @exception CertificateEncodingException if an exception occurs
	*/
	private byte[] encodePKCS7() throws CertificateEncodingException {
	PKCS7 p7 = new PKCS7(new AlgorithmId[0],
	new ContentInfo(ContentInfo.DATA_OID, null),
	certs.toArray(new X509Certificate[certs.size()]),
	new SignerInfo[0]);
	DerOutputStream derout = new DerOutputStream();
	try {
	p7.encodeSignedData(derout);
	} catch (IOException ioe) {
	throw new CertificateEncodingException(ioe.getMessage());
	}
	return derout.toByteArray();
	}

	/**
	* Returns the encoded form of this certification path, using the
	* specified encoding.
	*
	* @param encoding the name of the encoding to use
	* @return the encoded bytes
	* @exception CertificateEncodingException if an encoding error occurs or
	* the encoding requested is not supported
	*/
	@Override
	public byte[] getEncoded(String encoding)
	throws CertificateEncodingException {
	switch (encoding) {
	case PKIPATH_ENCODING:
	return encodePKIPATH();
	case PKCS7_ENCODING:
	return encodePKCS7();
	default:
	throw new CertificateEncodingException("unsupported encoding");
	}
	}

	/**
	* Returns the encodings supported by this certification path, with the
	* default encoding first.
	*
	* @return an <code>Iterator</code> over the names of the supported
	* encodings (as Strings)
	*/
	public static Iterator<String> getEncodingsStatic() {
	return encodingList.iterator();
	}

	/**
	* Returns an iteration of the encodings supported by this certification
	* path, with the default encoding first.
	* <p>
	* Attempts to modify the returned <code>Iterator</code> via its
	* <code>remove</code> method result in an
	* <code>UnsupportedOperationException</code>.
	*
	* @return an <code>Iterator</code> over the names of the supported
	* encodings (as Strings)
	*/
	@Override
	public Iterator<String> getEncodings() {
	return getEncodingsStatic();
	}

	/**
	* Returns the list of certificates in this certification path.
	* The <code>List</code> returned must be immutable and thread-safe.
	*
	* @return an immutable <code>List</code> of <code>X509Certificate</code>s
	* (may be empty, but not null)
	*/
	@Override
	public List<X509Certificate> getCertificates() {
	return certs;
	}
	}

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