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package sun.security.provider.certpath;
import java.io.IOException;
import java.security.cert.Certificate;
import java.security.cert.CertificateException;
import java.security.cert.CertPathValidatorException;
import java.security.cert.PKIXCertPathChecker;
import java.security.cert.PKIXReason;
import java.security.cert.X509Certificate;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import sun.security.util.Debug;
import static sun.security.x509.PKIXExtensions.*;
import sun.security.x509.NameConstraintsExtension;
import sun.security.x509.X509CertImpl;
/**
* ConstraintsChecker is a <code>PKIXCertPathChecker</code> that checks
* constraints information on a PKIX certificate, namely basic constraints
* and name constraints.
*
* @since 1.4
* @author Yassir Elley
*/
class ConstraintsChecker extends PKIXCertPathChecker {
private static final Debug debug = Debug.getInstance("certpath");
/* length of cert path */
private final int certPathLength;
/* current maximum path length (as defined in PKIX) */
private int maxPathLength;
/* current index of cert */
private int i;
private NameConstraintsExtension prevNC;
private Set<String> supportedExts;
/**
* Creates a ConstraintsChecker.
*
* @param certPathLength the length of the certification path
*/
ConstraintsChecker(int certPathLength) {
this.certPathLength = certPathLength;
}
@Override
public void init(boolean forward) throws CertPathValidatorException {
if (!forward) {
i = 0;
maxPathLength = certPathLength;
prevNC = null;
} else {
throw new CertPathValidatorException
("forward checking not supported");
}
}
@Override
public boolean isForwardCheckingSupported() {
return false;
}
@Override
public Set<String> getSupportedExtensions() {
if (supportedExts == null) {
supportedExts = new HashSet<String>(2);
supportedExts.add(BasicConstraints_Id.toString());
supportedExts.add(NameConstraints_Id.toString());
supportedExts = Collections.unmodifiableSet(supportedExts);
}
return supportedExts;
}
/**
* Performs the basic constraints and name constraints
* checks on the certificate using its internal state.
*
* @param cert the <code>Certificate</code> to be checked
* @param unresCritExts a <code>Collection</code> of OID strings
* representing the current set of unresolved critical extensions
* @throws CertPathValidatorException if the specified certificate
* does not pass the check
*/
@Override
public void check(Certificate cert, Collection<String> unresCritExts)
throws CertPathValidatorException
{
X509Certificate currCert = (X509Certificate)cert;
i++;
// MUST run NC check second, since it depends on BC check to
// update remainingCerts
checkBasicConstraints(currCert);
verifyNameConstraints(currCert);
if (unresCritExts != null && !unresCritExts.isEmpty()) {
unresCritExts.remove(BasicConstraints_Id.toString());
unresCritExts.remove(NameConstraints_Id.toString());
}
}
/**
* Internal method to check the name constraints against a cert
*/
private void verifyNameConstraints(X509Certificate currCert)
throws CertPathValidatorException
{
String msg = "name constraints";
if (debug != null) {
debug.println("---checking " + msg + "...");
}
// check name constraints only if there is a previous name constraint
// and either the currCert is the final cert or the currCert is not
// self-issued
if (prevNC != null && ((i == certPathLength) ||
!X509CertImpl.isSelfIssued(currCert))) {
if (debug != null) {
debug.println("prevNC = " + prevNC);
debug.println("currDN = " + currCert.getSubjectX500Principal());
}
try {
if (!prevNC.verify(currCert)) {
throw new CertPathValidatorException(msg + " check failed",
null, null, -1, PKIXReason.INVALID_NAME);
}
} catch (IOException ioe) {
throw new CertPathValidatorException(ioe);
}
}
// merge name constraints regardless of whether cert is self-issued
prevNC = mergeNameConstraints(currCert, prevNC);
if (debug != null)
debug.println(msg + " verified.");
}
/**
* Helper to fold sets of name constraints together
*/
static NameConstraintsExtension mergeNameConstraints(
X509Certificate currCert, NameConstraintsExtension prevNC)
throws CertPathValidatorException
{
X509CertImpl currCertImpl;
try {
currCertImpl = X509CertImpl.toImpl(currCert);
} catch (CertificateException ce) {
throw new CertPathValidatorException(ce);
}
NameConstraintsExtension newConstraints =
currCertImpl.getNameConstraintsExtension();
if (debug != null) {
debug.println("prevNC = " + prevNC);
debug.println("newNC = " + String.valueOf(newConstraints));
}
// if there are no previous name constraints, we just return the
// new name constraints.
if (prevNC == null) {
if (debug != null) {
debug.println("mergedNC = " + String.valueOf(newConstraints));
}
if (newConstraints == null) {
return newConstraints;
} else {
// Make sure we do a clone here, because we're probably
// going to modify this object later and we don't want to
// be sharing it with a Certificate object!
return (NameConstraintsExtension)newConstraints.clone();
}
} else {
try {
// after merge, prevNC should contain the merged constraints
prevNC.merge(newConstraints);
} catch (IOException ioe) {
throw new CertPathValidatorException(ioe);
}
if (debug != null) {
debug.println("mergedNC = " + prevNC);
}
return prevNC;
}
}
/**
* Internal method to check that a given cert meets basic constraints.
*/
private void checkBasicConstraints(X509Certificate currCert)
throws CertPathValidatorException
{
String msg = "basic constraints";
if (debug != null) {
debug.println("---checking " + msg + "...");
debug.println("i = " + i);
debug.println("maxPathLength = " + maxPathLength);
}
/* check if intermediate cert */
if (i < certPathLength) {
// RFC5280: If certificate i is a version 3 certificate, verify
// that the basicConstraints extension is present and that cA is
// set to TRUE. (If certificate i is a version 1 or version 2
// certificate, then the application MUST either verify that
// certificate i is a CA certificate through out-of-band means
// or reject the certificate. Conforming implementations may
// choose to reject all version 1 and version 2 intermediate
// certificates.)
//
// We choose to reject all version 1 and version 2 intermediate
// certificates except that it is self issued by the trust
// anchor in order to support key rollover or changes in
// certificate policies.
int pathLenConstraint = -1;
if (currCert.getVersion() < 3) { // version 1 or version 2
if (i == 1) { // issued by a trust anchor
if (X509CertImpl.isSelfIssued(currCert)) {
pathLenConstraint = Integer.MAX_VALUE;
}
}
} else {
pathLenConstraint = currCert.getBasicConstraints();
}
if (pathLenConstraint == -1) {
throw new CertPathValidatorException
(msg + " check failed: this is not a CA certificate",
null, null, -1, PKIXReason.NOT_CA_CERT);
}
if (!X509CertImpl.isSelfIssued(currCert)) {
if (maxPathLength <= 0) {
throw new CertPathValidatorException
(msg + " check failed: pathLenConstraint violated - "
+ "this cert must be the last cert in the "
+ "certification path", null, null, -1,
PKIXReason.PATH_TOO_LONG);
}
maxPathLength--;
}
if (pathLenConstraint < maxPathLength)
maxPathLength = pathLenConstraint;
}
if (debug != null) {
debug.println("after processing, maxPathLength = " + maxPathLength);
debug.println(msg + " verified.");
}
}
/**
* Merges the specified maxPathLength with the pathLenConstraint
* obtained from the certificate.
*
* @param cert the <code>X509Certificate</code>
* @param maxPathLength the previous maximum path length
* @return the new maximum path length constraint (-1 means no more
* certificates can follow, Integer.MAX_VALUE means path length is
* unconstrained)
*/
static int mergeBasicConstraints(X509Certificate cert, int maxPathLength) {
int pathLenConstraint = cert.getBasicConstraints();
if (!X509CertImpl.isSelfIssued(cert)) {
maxPathLength--;
}
if (pathLenConstraint < maxPathLength) {
maxPathLength = pathLenConstraint;
}
return maxPathLength;
}
}