provider/certpath/PolicyChecker.java

/*
 * Copyright (c) 2000, 2008, 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
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package sun.security.provider.certpath;

import java.util.*;
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.PolicyNode;
import java.security.cert.PolicyQualifierInfo;
import java.security.cert.X509Certificate;

import sun.security.util.Debug;
import sun.security.x509.CertificatePoliciesExtension;
import sun.security.x509.PolicyConstraintsExtension;
import sun.security.x509.PolicyMappingsExtension;
import sun.security.x509.CertificatePolicyMap;
import sun.security.x509.PKIXExtensions;
import sun.security.x509.PolicyInformation;
import sun.security.x509.X509CertImpl;
import sun.security.x509.InhibitAnyPolicyExtension;

/**
 * PolicyChecker is a <code>PKIXCertPathChecker</code> that checks policy
 * information on a PKIX certificate, namely certificate policies, policy
 * mappings, policy constraints and policy qualifiers.
 *
 * @since       1.4
 * @author      Yassir Elley
 */
class PolicyChecker extends PKIXCertPathChecker {

    private final Set<String> initPolicies;
    private final int certPathLen;
    private final boolean expPolicyRequired;
    private final boolean polMappingInhibited;
    private final boolean anyPolicyInhibited;
    private final boolean rejectPolicyQualifiers;
    private PolicyNodeImpl rootNode;
    private int explicitPolicy;
    private int policyMapping;
    private int inhibitAnyPolicy;
    private int certIndex;

    private Set<String> supportedExts;

    private static final Debug debug = Debug.getInstance("certpath");
    static final String ANY_POLICY = "2.5.29.32.0";

    /**
     * Constructs a Policy Checker.
     *
     * @param initialPolicies Set of initial policies
     * @param certPathLen length of the certification path to be checked
     * @param expPolicyRequired true if explicit policy is required
     * @param polMappingInhibited true if policy mapping is inhibited
     * @param anyPolicyInhibited true if the ANY_POLICY OID should be inhibited
     * @param rejectPolicyQualifiers true if pol qualifiers are to be rejected
     * @param rootNode the initial root node of the valid policy tree
     */
    PolicyChecker(Set<String> initialPolicies, int certPathLen,
        boolean expPolicyRequired, boolean polMappingInhibited,
        boolean anyPolicyInhibited, boolean rejectPolicyQualifiers,
        PolicyNodeImpl rootNode) throws CertPathValidatorException
    {
        if (initialPolicies.isEmpty()) {
            // if no initialPolicies are specified by user, set
            // initPolicies to be anyPolicy by default
            this.initPolicies = new HashSet<String>(1);
            this.initPolicies.add(ANY_POLICY);
        } else {
            this.initPolicies = new HashSet<String>(initialPolicies);
        }
        this.certPathLen = certPathLen;
        this.expPolicyRequired = expPolicyRequired;
        this.polMappingInhibited = polMappingInhibited;
        this.anyPolicyInhibited = anyPolicyInhibited;
        this.rejectPolicyQualifiers = rejectPolicyQualifiers;
        this.rootNode = rootNode;
        init(false);
    }

    /**
     * Initializes the internal state of the checker from parameters
     * specified in the constructor
     *
     * @param forward a boolean indicating whether this checker should
     * be initialized capable of building in the forward direction
     * @exception CertPathValidatorException Exception thrown if user
     * wants to enable forward checking and forward checking is not supported.
     */
    public void init(boolean forward) throws CertPathValidatorException {
        if (forward) {
            throw new CertPathValidatorException
                                        ("forward checking not supported");
        }

        certIndex = 1;
        explicitPolicy = (expPolicyRequired ? 0 : certPathLen + 1);
        policyMapping = (polMappingInhibited ? 0 : certPathLen + 1);
        inhibitAnyPolicy = (anyPolicyInhibited ? 0 : certPathLen + 1);
    }

    /**
     * Checks if forward checking is supported. Forward checking refers
     * to the ability of the PKIXCertPathChecker to perform its checks
     * when presented with certificates in the forward direction (from
     * target to anchor).
     *
     * @return true if forward checking is supported, false otherwise
     */
    public boolean isForwardCheckingSupported() {
        return false;
    }

    /**
     * Gets an immutable Set of the OID strings for the extensions that
     * the PKIXCertPathChecker supports (i.e. recognizes, is able to
     * process), or null if no extensions are
     * supported. All OID strings that a PKIXCertPathChecker might
     * possibly be able to process should be included.
     *
     * @return the Set of extensions supported by this PKIXCertPathChecker,
     * or null if no extensions are supported
     */
    public Set<String> getSupportedExtensions() {
        if (supportedExts == null) {
            supportedExts = new HashSet<String>();
            supportedExts.add(PKIXExtensions.CertificatePolicies_Id.toString());
            supportedExts.add(PKIXExtensions.PolicyMappings_Id.toString());
            supportedExts.add(PKIXExtensions.PolicyConstraints_Id.toString());
            supportedExts.add(PKIXExtensions.InhibitAnyPolicy_Id.toString());
            supportedExts = Collections.unmodifiableSet(supportedExts);
        }
        return supportedExts;
    }

    /**
     * Performs the policy processing checks on the certificate using its
     * internal state.
     *
     * @param cert the Certificate to be processed
     * @param unresCritExts the unresolved critical extensions
     * @exception CertPathValidatorException Exception thrown if
     * the certificate does not verify.
     */
    public void check(Certificate cert, Collection<String> unresCritExts)
        throws CertPathValidatorException
    {
        // now do the policy checks
        checkPolicy((X509Certificate) cert);

        if (unresCritExts != null && !unresCritExts.isEmpty()) {
            unresCritExts.remove(PKIXExtensions.CertificatePolicies_Id.toString());
            unresCritExts.remove(PKIXExtensions.PolicyMappings_Id.toString());
            unresCritExts.remove(PKIXExtensions.PolicyConstraints_Id.toString());
            unresCritExts.remove(PKIXExtensions.InhibitAnyPolicy_Id.toString());
        }
    }

    /**
     * Internal method to run through all the checks.
     *
     * @param currCert the certificate to be processed
     * @exception CertPathValidatorException Exception thrown if
     * the certificate does not verify
     */
    private void checkPolicy(X509Certificate currCert)
        throws CertPathValidatorException
    {
        String msg = "certificate policies";
        if (debug != null) {
            debug.println("PolicyChecker.checkPolicy() ---checking " + msg
                + "...");
            debug.println("PolicyChecker.checkPolicy() certIndex = "
                + certIndex);
            debug.println("PolicyChecker.checkPolicy() BEFORE PROCESSING: "
                + "explicitPolicy = " + explicitPolicy);
            debug.println("PolicyChecker.checkPolicy() BEFORE PROCESSING: "
                + "policyMapping = " + policyMapping);
            debug.println("PolicyChecker.checkPolicy() BEFORE PROCESSING: "
                + "inhibitAnyPolicy = " + inhibitAnyPolicy);
            debug.println("PolicyChecker.checkPolicy() BEFORE PROCESSING: "
                + "policyTree = " + rootNode);
        }

        X509CertImpl currCertImpl = null;
        try {
            currCertImpl = X509CertImpl.toImpl(currCert);
        } catch (CertificateException ce) {
            throw new CertPathValidatorException(ce);
        }

        boolean finalCert = (certIndex == certPathLen);

        rootNode = processPolicies(certIndex, initPolicies, explicitPolicy,
            policyMapping, inhibitAnyPolicy, rejectPolicyQualifiers, rootNode,
            currCertImpl, finalCert);

        if (!finalCert) {
            explicitPolicy = mergeExplicitPolicy(explicitPolicy, currCertImpl,
                                                 finalCert);
            policyMapping = mergePolicyMapping(policyMapping, currCertImpl);
            inhibitAnyPolicy = mergeInhibitAnyPolicy(inhibitAnyPolicy,
                                                     currCertImpl);
        }

        certIndex++;

        if (debug != null) {
            debug.println("PolicyChecker.checkPolicy() AFTER PROCESSING: "
                + "explicitPolicy = " + explicitPolicy);
            debug.println("PolicyChecker.checkPolicy() AFTER PROCESSING: "
                + "policyMapping = " + policyMapping);
            debug.println("PolicyChecker.checkPolicy() AFTER PROCESSING: "
                + "inhibitAnyPolicy = " + inhibitAnyPolicy);
            debug.println("PolicyChecker.checkPolicy() AFTER PROCESSING: "
                + "policyTree = " + rootNode);
            debug.println("PolicyChecker.checkPolicy() " + msg + " verified");
        }
    }

    /**
     * Merges the specified explicitPolicy value with the
     * requireExplicitPolicy field of the <code>PolicyConstraints</code>
     * extension obtained from the certificate. An explicitPolicy
     * value of -1 implies no constraint.
     *
     * @param explicitPolicy an integer which indicates if a non-null
     * valid policy tree is required
     * @param currCert the Certificate to be processed
     * @param finalCert a boolean indicating whether currCert is
     * the final cert in the cert path
     * @return returns the new explicitPolicy value
     * @exception CertPathValidatorException Exception thrown if an error
     * occurs
     */
    static int mergeExplicitPolicy(int explicitPolicy, X509CertImpl currCert,
        boolean finalCert) throws CertPathValidatorException
    {
        if ((explicitPolicy > 0) && !X509CertImpl.isSelfIssued(currCert)) {
            explicitPolicy--;
        }

        try {
            PolicyConstraintsExtension polConstExt
                = currCert.getPolicyConstraintsExtension();
            if (polConstExt == null)
                return explicitPolicy;
            int require = ((Integer)
                polConstExt.get(PolicyConstraintsExtension.REQUIRE)).intValue();
            if (debug != null) {
                debug.println("PolicyChecker.mergeExplicitPolicy() "
                   + "require Index from cert = " + require);
            }
            if (!finalCert) {
                if (require != -1) {
                    if ((explicitPolicy == -1) || (require < explicitPolicy)) {
                        explicitPolicy = require;
                    }
                }
            } else {
                if (require == 0)
                    explicitPolicy = require;
            }
        } catch (Exception e) {
            if (debug != null) {
                debug.println("PolicyChecker.mergeExplicitPolicy "
                              + "unexpected exception");
                e.printStackTrace();
            }
            throw new CertPathValidatorException(e);
        }

        return explicitPolicy;
    }

    /**
     * Merges the specified policyMapping value with the
     * inhibitPolicyMapping field of the <code>PolicyConstraints</code>
     * extension obtained from the certificate. A policyMapping
     * value of -1 implies no constraint.
     *
     * @param policyMapping an integer which indicates if policy mapping
     * is inhibited
     * @param currCert the Certificate to be processed
     * @return returns the new policyMapping value
     * @exception CertPathValidatorException Exception thrown if an error
     * occurs
     */
    static int mergePolicyMapping(int policyMapping, X509CertImpl currCert)
        throws CertPathValidatorException
    {
        if ((policyMapping > 0) && !X509CertImpl.isSelfIssued(currCert)) {
            policyMapping--;
        }

        try {
            PolicyConstraintsExtension polConstExt
                = currCert.getPolicyConstraintsExtension();
            if (polConstExt == null)
                return policyMapping;

            int inhibit = ((Integer)
                polConstExt.get(PolicyConstraintsExtension.INHIBIT)).intValue();
            if (debug != null)
                debug.println("PolicyChecker.mergePolicyMapping() "
                    + "inhibit Index from cert = " + inhibit);

            if (inhibit != -1) {
                if ((policyMapping == -1) || (inhibit < policyMapping)) {
                    policyMapping = inhibit;
                }
            }
        } catch (Exception e) {
            if (debug != null) {
                debug.println("PolicyChecker.mergePolicyMapping "
                              + "unexpected exception");
                e.printStackTrace();
            }
            throw new CertPathValidatorException(e);
        }

        return policyMapping;
    }

    /**
     * Merges the specified inhibitAnyPolicy value with the
     * SkipCerts value of the InhibitAnyPolicy
     * extension obtained from the certificate.
     *
     * @param inhibitAnyPolicy an integer which indicates whether
     * "any-policy" is considered a match
     * @param currCert the Certificate to be processed
     * @return returns the new inhibitAnyPolicy value
     * @exception CertPathValidatorException Exception thrown if an error
     * occurs
     */
    static int mergeInhibitAnyPolicy(int inhibitAnyPolicy,
        X509CertImpl currCert) throws CertPathValidatorException
    {
        if ((inhibitAnyPolicy > 0) && !X509CertImpl.isSelfIssued(currCert)) {
            inhibitAnyPolicy--;
        }

        try {
            InhibitAnyPolicyExtension inhAnyPolExt = (InhibitAnyPolicyExtension)
                currCert.getExtension(PKIXExtensions.InhibitAnyPolicy_Id);
            if (inhAnyPolExt == null)
                return inhibitAnyPolicy;

            int skipCerts = ((Integer)
                inhAnyPolExt.get(InhibitAnyPolicyExtension.SKIP_CERTS)).intValue();
            if (debug != null)
                debug.println("PolicyChecker.mergeInhibitAnyPolicy() "
                    + "skipCerts Index from cert = " + skipCerts);

            if (skipCerts != -1) {
                if (skipCerts < inhibitAnyPolicy) {
                    inhibitAnyPolicy = skipCerts;
                }
            }
        } catch (Exception e) {
            if (debug != null) {
                debug.println("PolicyChecker.mergeInhibitAnyPolicy "
                              + "unexpected exception");
                e.printStackTrace();
            }
            throw new CertPathValidatorException(e);
        }

        return inhibitAnyPolicy;
    }

    /**
     * Processes certificate policies in the certificate.
     *
     * @param certIndex the index of the certificate
     * @param initPolicies the initial policies required by the user
     * @param explicitPolicy an integer which indicates if a non-null
     * valid policy tree is required
     * @param policyMapping an integer which indicates if policy
     * mapping is inhibited
     * @param inhibitAnyPolicy an integer which indicates whether
     * "any-policy" is considered a match
     * @param rejectPolicyQualifiers a boolean indicating whether the
     * user wants to reject policies that have qualifiers
     * @param origRootNode the root node of the valid policy tree
     * @param currCert the Certificate to be processed
     * @param finalCert a boolean indicating whether currCert is the final
     * cert in the cert path
     * @return the root node of the valid policy tree after modification
     * @exception CertPathValidatorException Exception thrown if an
     * error occurs while processing policies.
     */
    static PolicyNodeImpl processPolicies(int certIndex, Set<String> initPolicies,
        int explicitPolicy, int policyMapping, int inhibitAnyPolicy,
        boolean rejectPolicyQualifiers, PolicyNodeImpl origRootNode,
        X509CertImpl currCert, boolean finalCert)
        throws CertPathValidatorException
    {
        boolean policiesCritical = false;
        List<PolicyInformation> policyInfo;
        PolicyNodeImpl rootNode = null;
        Set<PolicyQualifierInfo> anyQuals = new HashSet<PolicyQualifierInfo>();

        if (origRootNode == null)
            rootNode = null;
        else
            rootNode = origRootNode.copyTree();

        // retrieve policyOIDs from currCert
        CertificatePoliciesExtension currCertPolicies
            = currCert.getCertificatePoliciesExtension();

        // PKIX: Section 6.1.3: Step (d)
        if ((currCertPolicies != null) && (rootNode != null)) {
            policiesCritical = currCertPolicies.isCritical();
            if (debug != null)
                debug.println("PolicyChecker.processPolicies() "
                    + "policiesCritical = " + policiesCritical);

            try {
                policyInfo = (List<PolicyInformation>)
                    currCertPolicies.get(CertificatePoliciesExtension.POLICIES);
            } catch (IOException ioe) {
                throw new CertPathValidatorException("Exception while "
                    + "retrieving policyOIDs", ioe);
            }

            if (debug != null)
                debug.println("PolicyChecker.processPolicies() "
                    + "rejectPolicyQualifiers = " + rejectPolicyQualifiers);

            boolean foundAnyPolicy = false;

            // process each policy in cert
            for (PolicyInformation curPolInfo : policyInfo) {
                String curPolicy =
                    curPolInfo.getPolicyIdentifier().getIdentifier().toString();

                if (curPolicy.equals(ANY_POLICY)) {
                    foundAnyPolicy = true;
                    anyQuals = curPolInfo.getPolicyQualifiers();
                } else {
                    // PKIX: Section 6.1.3: Step (d)(1)
                    if (debug != null)
                        debug.println("PolicyChecker.processPolicies() "
                                      + "processing policy: " + curPolicy);

                    // retrieve policy qualifiers from cert
                    Set<PolicyQualifierInfo> pQuals =
                                        curPolInfo.getPolicyQualifiers();

                    // reject cert if we find critical policy qualifiers and
                    // the policyQualifiersRejected flag is set in the params
                    if (!pQuals.isEmpty() && rejectPolicyQualifiers &&
                        policiesCritical) {
                        throw new CertPathValidatorException(
                            "critical policy qualifiers present in certificate",
                            null, null, -1, PKIXReason.INVALID_POLICY);
                    }

                    // PKIX: Section 6.1.3: Step (d)(1)(i)
                    boolean foundMatch = processParents(certIndex,
                        policiesCritical, rejectPolicyQualifiers, rootNode,
                        curPolicy, pQuals, false);

                    if (!foundMatch) {
                        // PKIX: Section 6.1.3: Step (d)(1)(ii)
                        processParents(certIndex, policiesCritical,
                            rejectPolicyQualifiers, rootNode, curPolicy,
                            pQuals, true);
                    }
                }
            }

            // PKIX: Section 6.1.3: Step (d)(2)
            if (foundAnyPolicy) {
                if ((inhibitAnyPolicy > 0) ||
                        (!finalCert && X509CertImpl.isSelfIssued(currCert))) {
                    if (debug != null) {
                        debug.println("PolicyChecker.processPolicies() "
                            + "processing policy: " + ANY_POLICY);
                    }
                    processParents(certIndex, policiesCritical,
                        rejectPolicyQualifiers, rootNode, ANY_POLICY, anyQuals,
                        true);
                }
            }

            // PKIX: Section 6.1.3: Step (d)(3)
            rootNode.prune(certIndex);
            if (!rootNode.getChildren().hasNext()) {
                rootNode = null;
            }
        } else if (currCertPolicies == null) {
            if (debug != null)
                debug.println("PolicyChecker.processPolicies() "
                              + "no policies present in cert");
            // PKIX: Section 6.1.3: Step (e)
            rootNode = null;
        }

        // We delay PKIX: Section 6.1.3: Step (f) to the end
        // because the code that follows may delete some nodes
        // resulting in a null tree
        if (rootNode != null) {
            if (!finalCert) {
                // PKIX: Section 6.1.4: Steps (a)-(b)
                rootNode = processPolicyMappings(currCert, certIndex,
                    policyMapping, rootNode, policiesCritical, anyQuals);
            }
        }

        // At this point, we optimize the PKIX algorithm by
        // removing those nodes which would later have
        // been removed by PKIX: Section 6.1.5: Step (g)(iii)

        if ((rootNode != null) && (!initPolicies.contains(ANY_POLICY))
            && (currCertPolicies != null)) {
            rootNode = removeInvalidNodes(rootNode, certIndex,
                                          initPolicies, currCertPolicies);

            // PKIX: Section 6.1.5: Step (g)(iii)
            if ((rootNode != null) && finalCert) {
                // rewrite anyPolicy leaf nodes (see method comments)
                rootNode = rewriteLeafNodes(certIndex, initPolicies, rootNode);
            }
        }


        if (finalCert) {
            // PKIX: Section 6.1.5: Steps (a) and (b)
            explicitPolicy = mergeExplicitPolicy(explicitPolicy, currCert,
                                             finalCert);
        }

        // PKIX: Section 6.1.3: Step (f)
        // verify that either explicit policy is greater than 0 or
        // the valid_policy_tree is not equal to NULL

        if ((explicitPolicy == 0) && (rootNode == null)) {
            throw new CertPathValidatorException
                ("non-null policy tree required and policy tree is null",
                 null, null, -1, PKIXReason.INVALID_POLICY);
        }

        return rootNode;
    }

    /**
     * Rewrite leaf nodes at the end of validation as described in RFC 3280
     * section 6.1.5: Step (g)(iii). Leaf nodes with anyPolicy are replaced
     * by nodes explicitly representing initial policies not already
     * represented by leaf nodes.
     *
     * This method should only be called when processing the final cert
     * and if the policy tree is not null and initial policies is not
     * anyPolicy.
     *
     * @param certIndex the depth of the tree
     * @param initPolicies Set of user specified initial policies
     * @param rootNode the root of the policy tree
     */
    private static PolicyNodeImpl rewriteLeafNodes(int certIndex,
            Set<String> initPolicies, PolicyNodeImpl rootNode) {
        Set<PolicyNodeImpl> anyNodes =
                        rootNode.getPolicyNodesValid(certIndex, ANY_POLICY);
        if (anyNodes.isEmpty()) {
            return rootNode;
        }
        PolicyNodeImpl anyNode = anyNodes.iterator().next();
        PolicyNodeImpl parentNode = (PolicyNodeImpl)anyNode.getParent();
        parentNode.deleteChild(anyNode);
        // see if there are any initialPolicies not represented by leaf nodes
        Set<String> initial = new HashSet<String>(initPolicies);
        for (PolicyNodeImpl node : rootNode.getPolicyNodes(certIndex)) {
            initial.remove(node.getValidPolicy());
        }
        if (initial.isEmpty()) {
            // we deleted the anyPolicy node and have nothing to re-add,
            // so we need to prune the tree
            rootNode.prune(certIndex);
            if (rootNode.getChildren().hasNext() == false) {
                rootNode = null;
            }
        } else {
            boolean anyCritical = anyNode.isCritical();
            Set<PolicyQualifierInfo> anyQualifiers =
                                                anyNode.getPolicyQualifiers();
            for (String policy : initial) {
                Set<String> expectedPolicies = Collections.singleton(policy);
                PolicyNodeImpl node = new PolicyNodeImpl(parentNode, policy,
                    anyQualifiers, anyCritical, expectedPolicies, false);
            }
        }
        return rootNode;
    }

    /**
     * Finds the policy nodes of depth (certIndex-1) where curPolicy
     * is in the expected policy set and creates a new child node
     * appropriately. If matchAny is true, then a value of ANY_POLICY
     * in the expected policy set will match any curPolicy. If matchAny
     * is false, then the expected policy set must exactly contain the
     * curPolicy to be considered a match. This method returns a boolean
     * value indicating whether a match was found.
     *
     * @param certIndex the index of the certificate whose policy is
     * being processed
     * @param policiesCritical a boolean indicating whether the certificate
     * policies extension is critical
     * @param rejectPolicyQualifiers a boolean indicating whether the
     * user wants to reject policies that have qualifiers
     * @param rootNode the root node of the valid policy tree
     * @param curPolicy a String representing the policy being processed
     * @param pQuals the policy qualifiers of the policy being processed or an
     * empty Set if there are no qualifiers
     * @param matchAny a boolean indicating whether a value of ANY_POLICY
     * in the expected policy set will be considered a match
     * @return a boolean indicating whether a match was found
     * @exception CertPathValidatorException Exception thrown if error occurs.
     */
    private static boolean processParents(int certIndex,
        boolean policiesCritical, boolean rejectPolicyQualifiers,
        PolicyNodeImpl rootNode, String curPolicy,
        Set<PolicyQualifierInfo> pQuals,
        boolean matchAny) throws CertPathValidatorException
    {
        boolean foundMatch = false;

        if (debug != null)
            debug.println("PolicyChecker.processParents(): matchAny = "
                + matchAny);

        // find matching parents
        Set<PolicyNodeImpl> parentNodes =
                rootNode.getPolicyNodesExpected(certIndex - 1,
                                                curPolicy, matchAny);

        // for each matching parent, extend policy tree
        for (PolicyNodeImpl curParent : parentNodes) {
            if (debug != null)
                debug.println("PolicyChecker.processParents() "
                              + "found parent:\n" + curParent.asString());

            foundMatch = true;
            String curParPolicy = curParent.getValidPolicy();

            PolicyNodeImpl curNode = null;
            Set<String> curExpPols = null;

            if (curPolicy.equals(ANY_POLICY)) {
                // do step 2
                Set<String> parExpPols = curParent.getExpectedPolicies();
            parentExplicitPolicies:
                for (String curParExpPol : parExpPols) {

                    Iterator<PolicyNodeImpl> childIter =
                                        curParent.getChildren();
                    while (childIter.hasNext()) {
                        PolicyNodeImpl childNode = childIter.next();
                        String childPolicy = childNode.getValidPolicy();
                        if (curParExpPol.equals(childPolicy)) {
                            if (debug != null)
                                debug.println(childPolicy + " in parent's "
                                    + "expected policy set already appears in "
                                    + "child node");
                            continue parentExplicitPolicies;
                        }
                    }

                    Set<String> expPols = new HashSet<String>();
                    expPols.add(curParExpPol);

                    curNode = new PolicyNodeImpl
                        (curParent, curParExpPol, pQuals,
                         policiesCritical, expPols, false);
                }
            } else {
                curExpPols = new HashSet<String>();
                curExpPols.add(curPolicy);

                curNode = new PolicyNodeImpl
                    (curParent, curPolicy, pQuals,
                     policiesCritical, curExpPols, false);
            }
        }

        return foundMatch;
    }

    /**
     * Processes policy mappings in the certificate.
     *
     * @param currCert the Certificate to be processed
     * @param certIndex the index of the current certificate
     * @param policyMapping an integer which indicates if policy
     * mapping is inhibited
     * @param rootNode the root node of the valid policy tree
     * @param policiesCritical a boolean indicating if the certificate policies
     * extension is critical
     * @param anyQuals the qualifiers associated with ANY-POLICY, or an empty
     * Set if there are no qualifiers associated with ANY-POLICY
     * @return the root node of the valid policy tree after modification
     * @exception CertPathValidatorException exception thrown if an error
     * occurs while processing policy mappings
     */
    private static PolicyNodeImpl processPolicyMappings(X509CertImpl currCert,
        int certIndex, int policyMapping, PolicyNodeImpl rootNode,
        boolean policiesCritical, Set<PolicyQualifierInfo> anyQuals)
        throws CertPathValidatorException
    {
        PolicyMappingsExtension polMappingsExt
            = currCert.getPolicyMappingsExtension();

        if (polMappingsExt == null)
            return rootNode;

        if (debug != null)
            debug.println("PolicyChecker.processPolicyMappings() "
                + "inside policyMapping check");

        List<CertificatePolicyMap> maps = null;
        try {
            maps = (List<CertificatePolicyMap>)polMappingsExt.get
                                        (PolicyMappingsExtension.MAP);
        } catch (IOException e) {
            if (debug != null) {
                debug.println("PolicyChecker.processPolicyMappings() "
                    + "mapping exception");
                e.printStackTrace();
            }
            throw new CertPathValidatorException("Exception while checking "
                                                 + "mapping", e);
        }

        boolean childDeleted = false;
        for (int j = 0; j < maps.size(); j++) {
            CertificatePolicyMap polMap = maps.get(j);
            String issuerDomain
                = polMap.getIssuerIdentifier().getIdentifier().toString();
            String subjectDomain
                = polMap.getSubjectIdentifier().getIdentifier().toString();
            if (debug != null) {
                debug.println("PolicyChecker.processPolicyMappings() "
                              + "issuerDomain = " + issuerDomain);
                debug.println("PolicyChecker.processPolicyMappings() "
                              + "subjectDomain = " + subjectDomain);
            }

            if (issuerDomain.equals(ANY_POLICY)) {
                throw new CertPathValidatorException
                    ("encountered an issuerDomainPolicy of ANY_POLICY",
                     null, null, -1, PKIXReason.INVALID_POLICY);
            }

            if (subjectDomain.equals(ANY_POLICY)) {
                throw new CertPathValidatorException
                    ("encountered a subjectDomainPolicy of ANY_POLICY",
                     null, null, -1, PKIXReason.INVALID_POLICY);
            }

            Set<PolicyNodeImpl> validNodes =
                rootNode.getPolicyNodesValid(certIndex, issuerDomain);
            if (!validNodes.isEmpty()) {
                for (PolicyNodeImpl curNode : validNodes) {
                    if ((policyMapping > 0) || (policyMapping == -1)) {
                        curNode.addExpectedPolicy(subjectDomain);
                    } else if (policyMapping == 0) {
                        PolicyNodeImpl parentNode =
                            (PolicyNodeImpl) curNode.getParent();
                        if (debug != null)
                            debug.println("PolicyChecker.processPolicyMappings"
                                + "() before deleting: policy tree = "
                                + rootNode);
                        parentNode.deleteChild(curNode);
                        childDeleted = true;
                        if (debug != null)
                            debug.println("PolicyChecker.processPolicyMappings"
                                + "() after deleting: policy tree = "
                                + rootNode);
                    }
                }
            } else { // no node of depth i has a valid policy
                if ((policyMapping > 0) || (policyMapping == -1)) {
                    Set<PolicyNodeImpl> validAnyNodes =
                        rootNode.getPolicyNodesValid(certIndex, ANY_POLICY);
                    for (PolicyNodeImpl curAnyNode : validAnyNodes) {
                        PolicyNodeImpl curAnyNodeParent =
                            (PolicyNodeImpl) curAnyNode.getParent();

                        Set<String> expPols = new HashSet<String>();
                        expPols.add(subjectDomain);

                        PolicyNodeImpl curNode = new PolicyNodeImpl
                            (curAnyNodeParent, issuerDomain, anyQuals,
                             policiesCritical, expPols, true);
                    }
                }
            }
        }

        if (childDeleted) {
            rootNode.prune(certIndex);
            if (!rootNode.getChildren().hasNext()) {
                if (debug != null)
                    debug.println("setting rootNode to null");
                rootNode = null;
            }
        }

        return rootNode;
    }

    /**
     * Removes those nodes which do not intersect with the initial policies
     * specified by the user.
     *
     * @param rootNode the root node of the valid policy tree
     * @param certIndex the index of the certificate being processed
     * @param initPolicies the Set of policies required by the user
     * @param currCertPolicies the CertificatePoliciesExtension of the
     * certificate being processed
     * @returns the root node of the valid policy tree after modification
     * @exception CertPathValidatorException Exception thrown if error occurs.
     */
    private static PolicyNodeImpl removeInvalidNodes(PolicyNodeImpl rootNode,
        int certIndex, Set<String> initPolicies,
        CertificatePoliciesExtension currCertPolicies)
        throws CertPathValidatorException
    {
        List<PolicyInformation> policyInfo = null;
        try {
            policyInfo = (List<PolicyInformation>)
                currCertPolicies.get(CertificatePoliciesExtension.POLICIES);
        } catch (IOException ioe) {
            throw new CertPathValidatorException("Exception while "
                + "retrieving policyOIDs", ioe);
        }

        boolean childDeleted = false;
        for (PolicyInformation curPolInfo : policyInfo) {
            String curPolicy =
                curPolInfo.getPolicyIdentifier().getIdentifier().toString();

            if (debug != null)
                debug.println("PolicyChecker.processPolicies() "
                              + "processing policy second time: " + curPolicy);

            Set<PolicyNodeImpl> validNodes =
                        rootNode.getPolicyNodesValid(certIndex, curPolicy);
            for (PolicyNodeImpl curNode : validNodes) {
                PolicyNodeImpl parentNode = (PolicyNodeImpl)curNode.getParent();
                if (parentNode.getValidPolicy().equals(ANY_POLICY)) {
                    if ((!initPolicies.contains(curPolicy)) &&
                        (!curPolicy.equals(ANY_POLICY))) {
                        if (debug != null)
                            debug.println("PolicyChecker.processPolicies() "
                                + "before deleting: policy tree = " + rootNode);
                        parentNode.deleteChild(curNode);
                        childDeleted = true;
                        if (debug != null)
                            debug.println("PolicyChecker.processPolicies() "
                                + "after deleting: policy tree = " + rootNode);
                    }
                }
            }
        }

        if (childDeleted) {
            rootNode.prune(certIndex);
            if (!rootNode.getChildren().hasNext()) {
                rootNode = null;
            }
        }

        return rootNode;
    }

    /**
     * Gets the root node of the valid policy tree, or null if the
     * valid policy tree is null. Marks each node of the returned tree
     * immutable and thread-safe.
     *
     * @returns the root node of the valid policy tree, or null if
     * the valid policy tree is null
     */
    PolicyNode getPolicyTree() {
        if (rootNode == null)
            return null;
        else {
            PolicyNodeImpl policyTree = rootNode.copyTree();
            policyTree.setImmutable();
            return policyTree;
        }
    }
}