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	/*
	* Copyright (c) 2002, 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.validator;

	import java.io.IOException;
	import java.util.*;

	import java.security.*;
	import java.security.cert.*;

	import javax.security.auth.x500.X500Principal;

	import sun.security.x509.X509CertImpl;
	import sun.security.x509.KeyIdentifier;
	import sun.security.x509.NetscapeCertTypeExtension;
	import sun.security.util.DerValue;
	import sun.security.util.DerInputStream;
	import sun.security.util.ObjectIdentifier;

	import sun.security.provider.certpath.AlgorithmChecker;
	import sun.security.provider.certpath.UntrustedChecker;

	/**
	* A simple validator implementation. It is based on code from the JSSE
	* X509TrustManagerImpl. This implementation is designed for compatibility with
	* deployed certificates and previous J2SE versions. It will never support
	* more advanced features and will be deemphasized in favor of the PKIX
	* validator going forward.
	* <p>
	* {@code SimpleValidator} objects are immutable once they have been created.
	* Please DO NOT add methods that can change the state of an instance once
	* it has been created.
	*
	* @author Andreas Sterbenz
	*/
	public final class SimpleValidator extends Validator {

	// Constants for the OIDs we need

	final static String OID_BASIC_CONSTRAINTS = "2.5.29.19";

	final static String OID_NETSCAPE_CERT_TYPE = "2.16.840.1.113730.1.1";

	final static String OID_KEY_USAGE = "2.5.29.15";

	final static String OID_EXTENDED_KEY_USAGE = "2.5.29.37";

	final static String OID_EKU_ANY_USAGE = "2.5.29.37.0";

	final static ObjectIdentifier OBJID_NETSCAPE_CERT_TYPE =
	NetscapeCertTypeExtension.NetscapeCertType_Id;

	private final static String NSCT_SSL_CA =
	NetscapeCertTypeExtension.SSL_CA;

	private final static String NSCT_CODE_SIGNING_CA =
	NetscapeCertTypeExtension.OBJECT_SIGNING_CA;

	/**
	* The trusted certificates as:
	* Map (X500Principal)subject of trusted cert -> List of X509Certificate
	* The list is used because there may be multiple certificates
	* with an identical subject DN.
	*/
	private final Map<X500Principal, List<X509Certificate>>
	trustedX500Principals;

	/**
	* Set of the trusted certificates. Present only for
	* getTrustedCertificates().
	*/
	private final Collection<X509Certificate> trustedCerts;

	SimpleValidator(String variant, Collection<X509Certificate> trustedCerts) {
	super(TYPE_SIMPLE, variant);
	this.trustedCerts = trustedCerts;
	trustedX500Principals =
	new HashMap<X500Principal, List<X509Certificate>>();
	for (X509Certificate cert : trustedCerts) {
	X500Principal principal = cert.getSubjectX500Principal();
	List<X509Certificate> list = trustedX500Principals.get(principal);
	if (list == null) {
	// this actually should be a set, but duplicate entries
	// are not a problem and we can avoid the Set overhead
	list = new ArrayList<X509Certificate>(2);
	trustedX500Principals.put(principal, list);
	}
	list.add(cert);
	}
	}

	public Collection<X509Certificate> getTrustedCertificates() {
	return trustedCerts;
	}

	/**
	* Perform simple validation of chain. The arguments otherCerts and
	* parameter are ignored.
	*/
	@Override
	X509Certificate[] engineValidate(X509Certificate[] chain,
	Collection<X509Certificate> otherCerts,
	List<byte[]> responseList,
	AlgorithmConstraints constraints,
	Object parameter) throws CertificateException {
	if ((chain == null) \|\| (chain.length == 0)) {
	throw new CertificateException
	("null or zero-length certificate chain");
	}

	// make sure chain includes a trusted cert
	chain = buildTrustedChain(chain);

	@SuppressWarnings("deprecation")
	Date date = validationDate;
	if (date == null) {
	date = new Date();
	}

	// create distrusted certificates checker
	UntrustedChecker untrustedChecker = new UntrustedChecker();

	// check if anchor is untrusted
	X509Certificate anchorCert = chain[chain.length - 1];
	try {
	untrustedChecker.check(anchorCert);
	} catch (CertPathValidatorException cpve) {
	throw new ValidatorException(
	"Untrusted certificate: "+ anchorCert.getSubjectX500Principal(),
	ValidatorException.T_UNTRUSTED_CERT, anchorCert, cpve);
	}

	// create default algorithm constraints checker
	TrustAnchor anchor = new TrustAnchor(anchorCert, null);
	AlgorithmChecker defaultAlgChecker =
	new AlgorithmChecker(anchor, variant);

	// create application level algorithm constraints checker
	AlgorithmChecker appAlgChecker = null;
	if (constraints != null) {
	appAlgChecker = new AlgorithmChecker(anchor, constraints, null,
	variant);
	}

	// verify top down, starting at the certificate issued by
	// the trust anchor
	int maxPathLength = chain.length - 1;
	for (int i = chain.length - 2; i >= 0; i--) {
	X509Certificate issuerCert = chain[i + 1];
	X509Certificate cert = chain[i];

	// check untrusted certificate
	try {
	// Untrusted checker does not care about the unresolved
	// critical extensions.
	untrustedChecker.check(cert, Collections.<String>emptySet());
	} catch (CertPathValidatorException cpve) {
	throw new ValidatorException(
	"Untrusted certificate: " + cert.getSubjectX500Principal(),
	ValidatorException.T_UNTRUSTED_CERT, cert, cpve);
	}

	// check certificate algorithm
	try {
	// Algorithm checker does not care about the unresolved
	// critical extensions.
	defaultAlgChecker.check(cert, Collections.<String>emptySet());
	if (appAlgChecker != null) {
	appAlgChecker.check(cert, Collections.<String>emptySet());
	}
	} catch (CertPathValidatorException cpve) {
	throw new ValidatorException
	(ValidatorException.T_ALGORITHM_DISABLED, cert, cpve);
	}

	// no validity check for code signing certs
	if ((variant.equals(VAR_CODE_SIGNING) == false)
	&& (variant.equals(VAR_JCE_SIGNING) == false)) {
	cert.checkValidity(date);
	}

	// check name chaining
	if (cert.getIssuerX500Principal().equals(
	issuerCert.getSubjectX500Principal()) == false) {
	throw new ValidatorException
	(ValidatorException.T_NAME_CHAINING, cert);
	}

	// check signature
	try {
	cert.verify(issuerCert.getPublicKey());
	} catch (GeneralSecurityException e) {
	throw new ValidatorException
	(ValidatorException.T_SIGNATURE_ERROR, cert, e);
	}

	// check extensions for CA certs
	if (i != 0) {
	maxPathLength = checkExtensions(cert, maxPathLength);
	}
	}

	return chain;
	}

	private int checkExtensions(X509Certificate cert, int maxPathLen)
	throws CertificateException {
	Set<String> critSet = cert.getCriticalExtensionOIDs();
	if (critSet == null) {
	critSet = Collections.<String>emptySet();
	}

	// Check the basic constraints extension
	int pathLenConstraint =
	checkBasicConstraints(cert, critSet, maxPathLen);

	// Check the key usage and extended key usage extensions
	checkKeyUsage(cert, critSet);

	// check Netscape certificate type extension
	checkNetscapeCertType(cert, critSet);

	if (!critSet.isEmpty()) {
	throw new ValidatorException
	("Certificate contains unknown critical extensions: " + critSet,
	ValidatorException.T_CA_EXTENSIONS, cert);
	}

	return pathLenConstraint;
	}

	private void checkNetscapeCertType(X509Certificate cert,
	Set<String> critSet) throws CertificateException {
	if (variant.equals(VAR_GENERIC)) {
	// nothing
	} else if (variant.equals(VAR_TLS_CLIENT)
	\|\| variant.equals(VAR_TLS_SERVER)) {
	if (getNetscapeCertTypeBit(cert, NSCT_SSL_CA) == false) {
	throw new ValidatorException
	("Invalid Netscape CertType extension for SSL CA "
	+ "certificate",
	ValidatorException.T_CA_EXTENSIONS, cert);
	}
	critSet.remove(OID_NETSCAPE_CERT_TYPE);
	} else if (variant.equals(VAR_CODE_SIGNING)
	\|\| variant.equals(VAR_JCE_SIGNING)) {
	if (getNetscapeCertTypeBit(cert, NSCT_CODE_SIGNING_CA) == false) {
	throw new ValidatorException
	("Invalid Netscape CertType extension for code "
	+ "signing CA certificate",
	ValidatorException.T_CA_EXTENSIONS, cert);
	}
	critSet.remove(OID_NETSCAPE_CERT_TYPE);
	} else {
	throw new CertificateException("Unknown variant " + variant);
	}
	}

	/**
	* Get the value of the specified bit in the Netscape certificate type
	* extension. If the extension is not present at all, we return true.
	*/
	static boolean getNetscapeCertTypeBit(X509Certificate cert, String type) {
	try {
	NetscapeCertTypeExtension ext;
	if (cert instanceof X509CertImpl) {
	X509CertImpl certImpl = (X509CertImpl)cert;
	ObjectIdentifier oid = OBJID_NETSCAPE_CERT_TYPE;
	ext = (NetscapeCertTypeExtension)certImpl.getExtension(oid);
	if (ext == null) {
	return true;
	}
	} else {
	byte[] extVal = cert.getExtensionValue(OID_NETSCAPE_CERT_TYPE);
	if (extVal == null) {
	return true;
	}
	DerInputStream in = new DerInputStream(extVal);
	byte[] encoded = in.getOctetString();
	encoded = new DerValue(encoded).getUnalignedBitString()
	.toByteArray();
	ext = new NetscapeCertTypeExtension(encoded);
	}
	Boolean val = ext.get(type);
	return val.booleanValue();
	} catch (IOException e) {
	return false;
	}
	}

	private int checkBasicConstraints(X509Certificate cert,
	Set<String> critSet, int maxPathLen) throws CertificateException {

	critSet.remove(OID_BASIC_CONSTRAINTS);
	int constraints = cert.getBasicConstraints();
	// reject, if extension missing or not a CA (constraints == -1)
	if (constraints < 0) {
	throw new ValidatorException("End user tried to act as a CA",
	ValidatorException.T_CA_EXTENSIONS, cert);
	}

	// if the certificate is self-issued, ignore the pathLenConstraint
	// checking.
	if (!X509CertImpl.isSelfIssued(cert)) {
	if (maxPathLen <= 0) {
	throw new ValidatorException("Violated path length constraints",
	ValidatorException.T_CA_EXTENSIONS, cert);
	}

	maxPathLen--;
	}

	if (maxPathLen > constraints) {
	maxPathLen = constraints;
	}

	return maxPathLen;
	}

	/*
	* Verify the key usage and extended key usage for intermediate
	* certificates.
	*/
	private void checkKeyUsage(X509Certificate cert, Set<String> critSet)
	throws CertificateException {

	critSet.remove(OID_KEY_USAGE);
	// EKU irrelevant in CA certificates
	critSet.remove(OID_EXTENDED_KEY_USAGE);

	// check key usage extension
	boolean[] keyUsageInfo = cert.getKeyUsage();
	if (keyUsageInfo != null) {
	// keyUsageInfo[5] is for keyCertSign.
	if ((keyUsageInfo.length < 6) \|\| (keyUsageInfo[5] == false)) {
	throw new ValidatorException
	("Wrong key usage: expected keyCertSign",
	ValidatorException.T_CA_EXTENSIONS, cert);
	}
	}
	}

	/**
	* Build a trusted certificate chain. This method always returns a chain
	* with a trust anchor as the final cert in the chain. If no trust anchor
	* could be found, a CertificateException is thrown.
	*/
	private X509Certificate[] buildTrustedChain(X509Certificate[] chain)
	throws CertificateException {
	List<X509Certificate> c = new ArrayList<X509Certificate>(chain.length);
	// scan chain starting at EE cert
	// if a trusted certificate is found, append it and return
	for (int i = 0; i < chain.length; i++) {
	X509Certificate cert = chain[i];
	X509Certificate trustedCert = getTrustedCertificate(cert);
	if (trustedCert != null) {
	c.add(trustedCert);
	return c.toArray(CHAIN0);
	}
	c.add(cert);
	}

	// check if we can append a trusted cert
	X509Certificate cert = chain[chain.length - 1];
	X500Principal subject = cert.getSubjectX500Principal();
	X500Principal issuer = cert.getIssuerX500Principal();
	List<X509Certificate> list = trustedX500Principals.get(issuer);
	if (list != null) {
	X509Certificate trustedCert = list.iterator().next();
	c.add(trustedCert);
	return c.toArray(CHAIN0);
	}

	// no trusted cert found, error
	throw new ValidatorException(ValidatorException.T_NO_TRUST_ANCHOR);
	}

	/**
	* Return a trusted certificate that matches the input certificate,
	* or null if no such certificate can be found. This method also handles
	* cases where a CA re-issues a trust anchor with the same public key and
	* same subject and issuer names but a new validity period, etc.
	*/
	private X509Certificate getTrustedCertificate(X509Certificate cert) {
	Principal certSubjectName = cert.getSubjectX500Principal();
	List<X509Certificate> list = trustedX500Principals.get(certSubjectName);
	if (list == null) {
	return null;
	}

	Principal certIssuerName = cert.getIssuerX500Principal();
	PublicKey certPublicKey = cert.getPublicKey();

	for (X509Certificate mycert : list) {
	if (mycert.equals(cert)) {
	return cert;
	}
	if (!mycert.getIssuerX500Principal().equals(certIssuerName)) {
	continue;
	}
	if (!mycert.getPublicKey().equals(certPublicKey)) {
	continue;
	}

	// All tests pass, this must be the one to use...
	return mycert;
	}
	return null;
	}

	}

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