sop / x509

lib/X509/CertificationPath/Policy/PolicyTree.php

Indentation +395 added lines, -395 removed lines

@@ -10,413 +10,413 @@
 
 class PolicyTree
 {
-    /**
-     * Root node at depth zero.
-     *
-     * @var null|PolicyNode
-     */
-    protected $_root;
+	/**
+	 * Root node at depth zero.
+	 *
+	 * @var null|PolicyNode
+	 */
+	protected $_root;
 
-    /**
-     * Constructor.
-     *
-     * @param PolicyNode $root Initial root node
-     */
-    public function __construct(PolicyNode $root)
-    {
-        $this->_root = $root;
-    }
+	/**
+	 * Constructor.
+	 *
+	 * @param PolicyNode $root Initial root node
+	 */
+	public function __construct(PolicyNode $root)
+	{
+		$this->_root = $root;
+	}
 
-    /**
-     * Process policy information from the certificate.
-     *
-     * Certificate policies extension must be present.
-     *
-     * @param ValidatorState $state
-     * @param Certificate    $cert
-     *
-     * @return ValidatorState
-     */
-    public function processPolicies(ValidatorState $state,
-        Certificate $cert): ValidatorState
-    {
-        $policies = $cert->tbsCertificate()->extensions()->certificatePolicies();
-        $tree = clone $this;
-        // (d.1) for each policy P not equal to anyPolicy
-        foreach ($policies as $policy) {
-            if ($policy->isAnyPolicy()) {
-                $tree->_processAnyPolicy($policy, $cert, $state);
-            } else {
-                $tree->_processPolicy($policy, $state);
-            }
-        }
-        // if whole tree is pruned
-        if (!$tree->_pruneTree($state->index() - 1)) {
-            return $state->withoutValidPolicyTree();
-        }
-        return $state->withValidPolicyTree($tree);
-    }
+	/**
+	 * Process policy information from the certificate.
+	 *
+	 * Certificate policies extension must be present.
+	 *
+	 * @param ValidatorState $state
+	 * @param Certificate    $cert
+	 *
+	 * @return ValidatorState
+	 */
+	public function processPolicies(ValidatorState $state,
+		Certificate $cert): ValidatorState
+	{
+		$policies = $cert->tbsCertificate()->extensions()->certificatePolicies();
+		$tree = clone $this;
+		// (d.1) for each policy P not equal to anyPolicy
+		foreach ($policies as $policy) {
+			if ($policy->isAnyPolicy()) {
+				$tree->_processAnyPolicy($policy, $cert, $state);
+			} else {
+				$tree->_processPolicy($policy, $state);
+			}
+		}
+		// if whole tree is pruned
+		if (!$tree->_pruneTree($state->index() - 1)) {
+			return $state->withoutValidPolicyTree();
+		}
+		return $state->withValidPolicyTree($tree);
+	}
 
-    /**
-     * Process policy mappings from the certificate.
-     *
-     * @param ValidatorState $state
-     * @param Certificate    $cert
-     *
-     * @return ValidatorState
-     */
-    public function processMappings(ValidatorState $state,
-        Certificate $cert): ValidatorState
-    {
-        $tree = clone $this;
-        if ($state->policyMapping() > 0) {
-            $tree->_applyMappings($cert, $state);
-        } elseif (0 == $state->policyMapping()) {
-            $tree->_deleteMappings($cert, $state);
-        }
-        // if whole tree is pruned
-        if (!$tree->_root) {
-            return $state->withoutValidPolicyTree();
-        }
-        return $state->withValidPolicyTree($tree);
-    }
+	/**
+	 * Process policy mappings from the certificate.
+	 *
+	 * @param ValidatorState $state
+	 * @param Certificate    $cert
+	 *
+	 * @return ValidatorState
+	 */
+	public function processMappings(ValidatorState $state,
+		Certificate $cert): ValidatorState
+	{
+		$tree = clone $this;
+		if ($state->policyMapping() > 0) {
+			$tree->_applyMappings($cert, $state);
+		} elseif (0 == $state->policyMapping()) {
+			$tree->_deleteMappings($cert, $state);
+		}
+		// if whole tree is pruned
+		if (!$tree->_root) {
+			return $state->withoutValidPolicyTree();
+		}
+		return $state->withValidPolicyTree($tree);
+	}
 
-    /**
-     * Calculate policy intersection as specified in Wrap-Up Procedure 6.1.5.g.
-     *
-     * @param ValidatorState $state
-     * @param array          $policies
-     *
-     * @return ValidatorState
-     */
-    public function calculateIntersection(ValidatorState $state,
-        array $policies): ValidatorState
-    {
-        $tree = clone $this;
-        $valid_policy_node_set = $tree->_validPolicyNodeSet();
-        // 2. If the valid_policy of any node in the valid_policy_node_set
-        // is not in the user-initial-policy-set and is not anyPolicy,
-        // delete this node and all its children.
-        $valid_policy_node_set = array_filter($valid_policy_node_set,
-            function (PolicyNode $node) use ($policies) {
-                if ($node->isAnyPolicy()) {
-                    return true;
-                }
-                if (in_array($node->validPolicy(), $policies)) {
-                    return true;
-                }
-                $node->remove();
-                return false;
-            });
-        // array of valid policy OIDs
-        $valid_policy_set = array_map(
-            function (PolicyNode $node) {
-                return $node->validPolicy();
-            }, $valid_policy_node_set);
-        // 3. If the valid_policy_tree includes a node of depth n with
-        // the valid_policy anyPolicy and the user-initial-policy-set
-        // is not any-policy
-        foreach ($tree->_nodesAtDepth($state->index()) as $node) {
-            if ($node->hasParent() && $node->isAnyPolicy()) {
-                // a. Set P-Q to the qualifier_set in the node of depth n
-                // with valid_policy anyPolicy.
-                $pq = $node->qualifiers();
-                // b. For each P-OID in the user-initial-policy-set that is not
-                // the valid_policy of a node in the valid_policy_node_set,
-                // create a child node whose parent is the node of depth n-1
-                // with the valid_policy anyPolicy.
-                $poids = array_diff($policies, $valid_policy_set);
-                foreach ($tree->_nodesAtDepth($state->index() - 1) as $parent) {
-                    if ($parent->isAnyPolicy()) {
-                        // Set the values in the child node as follows:
-                        // set the valid_policy to P-OID, set the qualifier_set
-                        // to P-Q, and set the expected_policy_set to {P-OID}.
-                        foreach ($poids as $poid) {
-                            $parent->addChild(new PolicyNode($poid, $pq, [$poid]));
-                        }
-                        break;
-                    }
-                }
-                // c. Delete the node of depth n with the
-                // valid_policy anyPolicy.
-                $node->remove();
-            }
-        }
-        // 4. If there is a node in the valid_policy_tree of depth n-1 or less
-        // without any child nodes, delete that node. Repeat this step until
-        // there are no nodes of depth n-1 or less without children.
-        if (!$tree->_pruneTree($state->index() - 1)) {
-            return $state->withoutValidPolicyTree();
-        }
-        return $state->withValidPolicyTree($tree);
-    }
+	/**
+	 * Calculate policy intersection as specified in Wrap-Up Procedure 6.1.5.g.
+	 *
+	 * @param ValidatorState $state
+	 * @param array          $policies
+	 *
+	 * @return ValidatorState
+	 */
+	public function calculateIntersection(ValidatorState $state,
+		array $policies): ValidatorState
+	{
+		$tree = clone $this;
+		$valid_policy_node_set = $tree->_validPolicyNodeSet();
+		// 2. If the valid_policy of any node in the valid_policy_node_set
+		// is not in the user-initial-policy-set and is not anyPolicy,
+		// delete this node and all its children.
+		$valid_policy_node_set = array_filter($valid_policy_node_set,
+			function (PolicyNode $node) use ($policies) {
+				if ($node->isAnyPolicy()) {
+					return true;
+				}
+				if (in_array($node->validPolicy(), $policies)) {
+					return true;
+				}
+				$node->remove();
+				return false;
+			});
+		// array of valid policy OIDs
+		$valid_policy_set = array_map(
+			function (PolicyNode $node) {
+				return $node->validPolicy();
+			}, $valid_policy_node_set);
+		// 3. If the valid_policy_tree includes a node of depth n with
+		// the valid_policy anyPolicy and the user-initial-policy-set
+		// is not any-policy
+		foreach ($tree->_nodesAtDepth($state->index()) as $node) {
+			if ($node->hasParent() && $node->isAnyPolicy()) {
+				// a. Set P-Q to the qualifier_set in the node of depth n
+				// with valid_policy anyPolicy.
+				$pq = $node->qualifiers();
+				// b. For each P-OID in the user-initial-policy-set that is not
+				// the valid_policy of a node in the valid_policy_node_set,
+				// create a child node whose parent is the node of depth n-1
+				// with the valid_policy anyPolicy.
+				$poids = array_diff($policies, $valid_policy_set);
+				foreach ($tree->_nodesAtDepth($state->index() - 1) as $parent) {
+					if ($parent->isAnyPolicy()) {
+						// Set the values in the child node as follows:
+						// set the valid_policy to P-OID, set the qualifier_set
+						// to P-Q, and set the expected_policy_set to {P-OID}.
+						foreach ($poids as $poid) {
+							$parent->addChild(new PolicyNode($poid, $pq, [$poid]));
+						}
+						break;
+					}
+				}
+				// c. Delete the node of depth n with the
+				// valid_policy anyPolicy.
+				$node->remove();
+			}
+		}
+		// 4. If there is a node in the valid_policy_tree of depth n-1 or less
+		// without any child nodes, delete that node. Repeat this step until
+		// there are no nodes of depth n-1 or less without children.
+		if (!$tree->_pruneTree($state->index() - 1)) {
+			return $state->withoutValidPolicyTree();
+		}
+		return $state->withValidPolicyTree($tree);
+	}
 
-    /**
-     * Get policies at given policy tree depth.
-     *
-     * @param int $i Depth in range 1..n
-     *
-     * @return PolicyInformation[]
-     */
-    public function policiesAtDepth(int $i): array
-    {
-        $policies = [];
-        foreach ($this->_nodesAtDepth($i) as $node) {
-            $policies[] = new PolicyInformation(
-                $node->validPolicy(), ...$node->qualifiers());
-        }
-        return $policies;
-    }
+	/**
+	 * Get policies at given policy tree depth.
+	 *
+	 * @param int $i Depth in range 1..n
+	 *
+	 * @return PolicyInformation[]
+	 */
+	public function policiesAtDepth(int $i): array
+	{
+		$policies = [];
+		foreach ($this->_nodesAtDepth($i) as $node) {
+			$policies[] = new PolicyInformation(
+				$node->validPolicy(), ...$node->qualifiers());
+		}
+		return $policies;
+	}
 
-    /**
-     * Process single policy information.
-     *
-     * @param PolicyInformation $policy
-     * @param ValidatorState    $state
-     */
-    protected function _processPolicy(PolicyInformation $policy,
-        ValidatorState $state): void
-    {
-        $p_oid = $policy->oid();
-        $i = $state->index();
-        $match_count = 0;
-        // (d.1.i) for each node of depth i-1 in the valid_policy_tree...
-        foreach ($this->_nodesAtDepth($i - 1) as $node) {
-            // ...where P-OID is in the expected_policy_set
-            if ($node->hasExpectedPolicy($p_oid)) {
-                $node->addChild(new PolicyNode(
-                    $p_oid, $policy->qualifiers(), [$p_oid]));
-                ++$match_count;
-            }
-        }
-        // (d.1.ii) if there was no match in step (i)...
-        if (!$match_count) {
-            // ...and the valid_policy_tree includes a node of depth i-1 with
-            // the valid_policy anyPolicy
-            foreach ($this->_nodesAtDepth($i - 1) as $node) {
-                if ($node->isAnyPolicy()) {
-                    $node->addChild(new PolicyNode(
-                        $p_oid, $policy->qualifiers(), [$p_oid]));
-                }
-            }
-        }
-    }
+	/**
+	 * Process single policy information.
+	 *
+	 * @param PolicyInformation $policy
+	 * @param ValidatorState    $state
+	 */
+	protected function _processPolicy(PolicyInformation $policy,
+		ValidatorState $state): void
+	{
+		$p_oid = $policy->oid();
+		$i = $state->index();
+		$match_count = 0;
+		// (d.1.i) for each node of depth i-1 in the valid_policy_tree...
+		foreach ($this->_nodesAtDepth($i - 1) as $node) {
+			// ...where P-OID is in the expected_policy_set
+			if ($node->hasExpectedPolicy($p_oid)) {
+				$node->addChild(new PolicyNode(
+					$p_oid, $policy->qualifiers(), [$p_oid]));
+				++$match_count;
+			}
+		}
+		// (d.1.ii) if there was no match in step (i)...
+		if (!$match_count) {
+			// ...and the valid_policy_tree includes a node of depth i-1 with
+			// the valid_policy anyPolicy
+			foreach ($this->_nodesAtDepth($i - 1) as $node) {
+				if ($node->isAnyPolicy()) {
+					$node->addChild(new PolicyNode(
+						$p_oid, $policy->qualifiers(), [$p_oid]));
+				}
+			}
+		}
+	}
 
-    /**
-     * Process anyPolicy policy information.
-     *
-     * @param PolicyInformation $policy
-     * @param Certificate       $cert
-     * @param ValidatorState    $state
-     */
-    protected function _processAnyPolicy(PolicyInformation $policy,
-        Certificate $cert, ValidatorState $state): void
-    {
-        $i = $state->index();
-        // if (a) inhibit_anyPolicy is greater than 0 or
-        // (b) i<n and the certificate is self-issued
-        if (!($state->inhibitAnyPolicy() > 0 ||
-            ($i < $state->pathLength() && $cert->isSelfIssued()))) {
-            return;
-        }
-        // for each node in the valid_policy_tree of depth i-1
-        foreach ($this->_nodesAtDepth($i - 1) as $node) {
-            // for each value in the expected_policy_set
-            foreach ($node->expectedPolicies() as $p_oid) {
-                // that does not appear in a child node
-                if (!$node->hasChildWithValidPolicy($p_oid)) {
-                    $node->addChild(new PolicyNode(
-                        $p_oid, $policy->qualifiers(), [$p_oid]));
-                }
-            }
-        }
-    }
+	/**
+	 * Process anyPolicy policy information.
+	 *
+	 * @param PolicyInformation $policy
+	 * @param Certificate       $cert
+	 * @param ValidatorState    $state
+	 */
+	protected function _processAnyPolicy(PolicyInformation $policy,
+		Certificate $cert, ValidatorState $state): void
+	{
+		$i = $state->index();
+		// if (a) inhibit_anyPolicy is greater than 0 or
+		// (b) i<n and the certificate is self-issued
+		if (!($state->inhibitAnyPolicy() > 0 ||
+			($i < $state->pathLength() && $cert->isSelfIssued()))) {
+			return;
+		}
+		// for each node in the valid_policy_tree of depth i-1
+		foreach ($this->_nodesAtDepth($i - 1) as $node) {
+			// for each value in the expected_policy_set
+			foreach ($node->expectedPolicies() as $p_oid) {
+				// that does not appear in a child node
+				if (!$node->hasChildWithValidPolicy($p_oid)) {
+					$node->addChild(new PolicyNode(
+						$p_oid, $policy->qualifiers(), [$p_oid]));
+				}
+			}
+		}
+	}
 
-    /**
-     * Apply policy mappings to the policy tree.
-     *
-     * @param Certificate    $cert
-     * @param ValidatorState $state
-     */
-    protected function _applyMappings(Certificate $cert, ValidatorState $state): void
-    {
-        $policy_mappings = $cert->tbsCertificate()->extensions()->policyMappings();
-        // (6.1.4. b.1.) for each node in the valid_policy_tree of depth i...
-        foreach ($policy_mappings->flattenedMappings() as $idp => $sdps) {
-            $match_count = 0;
-            foreach ($this->_nodesAtDepth($state->index()) as $node) {
-                // ...where ID-P is the valid_policy
-                if ($node->validPolicy() == $idp) {
-                    // set expected_policy_set to the set of subjectDomainPolicy
-                    // values that are specified as equivalent to ID-P by
-                    // the policy mappings extension
-                    $node->setExpectedPolicies(...$sdps);
-                    ++$match_count;
-                }
-            }
-            // if no node of depth i in the valid_policy_tree has
-            // a valid_policy of ID-P...
-            if (!$match_count) {
-                $this->_applyAnyPolicyMapping($cert, $state, $idp, $sdps);
-            }
-        }
-    }
+	/**
+	 * Apply policy mappings to the policy tree.
+	 *
+	 * @param Certificate    $cert
+	 * @param ValidatorState $state
+	 */
+	protected function _applyMappings(Certificate $cert, ValidatorState $state): void
+	{
+		$policy_mappings = $cert->tbsCertificate()->extensions()->policyMappings();
+		// (6.1.4. b.1.) for each node in the valid_policy_tree of depth i...
+		foreach ($policy_mappings->flattenedMappings() as $idp => $sdps) {
+			$match_count = 0;
+			foreach ($this->_nodesAtDepth($state->index()) as $node) {
+				// ...where ID-P is the valid_policy
+				if ($node->validPolicy() == $idp) {
+					// set expected_policy_set to the set of subjectDomainPolicy
+					// values that are specified as equivalent to ID-P by
+					// the policy mappings extension
+					$node->setExpectedPolicies(...$sdps);
+					++$match_count;
+				}
+			}
+			// if no node of depth i in the valid_policy_tree has
+			// a valid_policy of ID-P...
+			if (!$match_count) {
+				$this->_applyAnyPolicyMapping($cert, $state, $idp, $sdps);
+			}
+		}
+	}
 
-    /**
-     * Apply anyPolicy mapping to the policy tree as specified in 6.1.4 (b)(1).
-     *
-     * @param Certificate    $cert
-     * @param ValidatorState $state
-     * @param string         $idp   OID of the issuer domain policy
-     * @param array          $sdps  Array of subject domain policy OIDs
-     */
-    protected function _applyAnyPolicyMapping(Certificate $cert,
-        ValidatorState $state, string $idp, array $sdps): void
-    {
-        // (6.1.4. b.1.) ...but there is a node of depth i with
-        // a valid_policy of anyPolicy
-        foreach ($this->_nodesAtDepth($state->index()) as $node) {
-            if ($node->isAnyPolicy()) {
-                // then generate a child node of the node of depth i-1
-                // that has a valid_policy of anyPolicy as follows...
-                foreach ($this->_nodesAtDepth($state->index() - 1) as $subnode) {
-                    if ($subnode->isAnyPolicy()) {
-                        // try to fetch qualifiers of anyPolicy certificate policy
-                        $qualifiers = [];
-                        try {
-                            $qualifiers = $cert->tbsCertificate()
-                                ->extensions()->certificatePolicies()
-                                ->anyPolicy()->qualifiers();
-                        } catch (\LogicException $e) {
-                            // if there's no policies or no qualifiers
-                        }
-                        $subnode->addChild(new PolicyNode($idp, $qualifiers, $sdps));
-                        // bail after first anyPolicy has been processed
-                        break;
-                    }
-                }
-                // bail after first anyPolicy has been processed
-                break;
-            }
-        }
-    }
+	/**
+	 * Apply anyPolicy mapping to the policy tree as specified in 6.1.4 (b)(1).
+	 *
+	 * @param Certificate    $cert
+	 * @param ValidatorState $state
+	 * @param string         $idp   OID of the issuer domain policy
+	 * @param array          $sdps  Array of subject domain policy OIDs
+	 */
+	protected function _applyAnyPolicyMapping(Certificate $cert,
+		ValidatorState $state, string $idp, array $sdps): void
+	{
+		// (6.1.4. b.1.) ...but there is a node of depth i with
+		// a valid_policy of anyPolicy
+		foreach ($this->_nodesAtDepth($state->index()) as $node) {
+			if ($node->isAnyPolicy()) {
+				// then generate a child node of the node of depth i-1
+				// that has a valid_policy of anyPolicy as follows...
+				foreach ($this->_nodesAtDepth($state->index() - 1) as $subnode) {
+					if ($subnode->isAnyPolicy()) {
+						// try to fetch qualifiers of anyPolicy certificate policy
+						$qualifiers = [];
+						try {
+							$qualifiers = $cert->tbsCertificate()
+								->extensions()->certificatePolicies()
+								->anyPolicy()->qualifiers();
+						} catch (\LogicException $e) {
+							// if there's no policies or no qualifiers
+						}
+						$subnode->addChild(new PolicyNode($idp, $qualifiers, $sdps));
+						// bail after first anyPolicy has been processed
+						break;
+					}
+				}
+				// bail after first anyPolicy has been processed
+				break;
+			}
+		}
+	}
 
-    /**
-     * Delete nodes as specified in 6.1.4 (b)(2).
-     *
-     * @param Certificate    $cert
-     * @param ValidatorState $state
-     */
-    protected function _deleteMappings(Certificate $cert,
-        ValidatorState $state): void
-    {
-        $idps = $cert->tbsCertificate()->extensions()
-            ->policyMappings()->issuerDomainPolicies();
-        // delete each node of depth i in the valid_policy_tree
-        // where ID-P is the valid_policy
-        foreach ($this->_nodesAtDepth($state->index()) as $node) {
-            if (in_array($node->validPolicy(), $idps)) {
-                $node->remove();
-            }
-        }
-        $this->_pruneTree($state->index() - 1);
-    }
+	/**
+	 * Delete nodes as specified in 6.1.4 (b)(2).
+	 *
+	 * @param Certificate    $cert
+	 * @param ValidatorState $state
+	 */
+	protected function _deleteMappings(Certificate $cert,
+		ValidatorState $state): void
+	{
+		$idps = $cert->tbsCertificate()->extensions()
+			->policyMappings()->issuerDomainPolicies();
+		// delete each node of depth i in the valid_policy_tree
+		// where ID-P is the valid_policy
+		foreach ($this->_nodesAtDepth($state->index()) as $node) {
+			if (in_array($node->validPolicy(), $idps)) {
+				$node->remove();
+			}
+		}
+		$this->_pruneTree($state->index() - 1);
+	}
 
-    /**
-     * Prune tree starting from given depth.
-     *
-     * @param int $depth
-     *
-     * @return int The number of nodes left in a tree
-     */
-    protected function _pruneTree(int $depth): int
-    {
-        if (!$this->_root) {
-            return 0;
-        }
-        for ($i = $depth; $i > 0; --$i) {
-            foreach ($this->_nodesAtDepth($i) as $node) {
-                if (!count($node)) {
-                    $node->remove();
-                }
-            }
-        }
-        // if root has no children left
-        if (!count($this->_root)) {
-            $this->_root = null;
-            return 0;
-        }
-        return $this->_root->nodeCount();
-    }
+	/**
+	 * Prune tree starting from given depth.
+	 *
+	 * @param int $depth
+	 *
+	 * @return int The number of nodes left in a tree
+	 */
+	protected function _pruneTree(int $depth): int
+	{
+		if (!$this->_root) {
+			return 0;
+		}
+		for ($i = $depth; $i > 0; --$i) {
+			foreach ($this->_nodesAtDepth($i) as $node) {
+				if (!count($node)) {
+					$node->remove();
+				}
+			}
+		}
+		// if root has no children left
+		if (!count($this->_root)) {
+			$this->_root = null;
+			return 0;
+		}
+		return $this->_root->nodeCount();
+	}
 
-    /**
-     * Get all nodes at given depth.
-     *
-     * @param int $i
-     *
-     * @return PolicyNode[]
-     */
-    protected function _nodesAtDepth(int $i): array
-    {
-        if (!$this->_root) {
-            return [];
-        }
-        $depth = 0;
-        $nodes = [$this->_root];
-        while ($depth < $i) {
-            $nodes = self::_gatherChildren(...$nodes);
-            if (!count($nodes)) {
-                break;
-            }
-            ++$depth;
-        }
-        return $nodes;
-    }
+	/**
+	 * Get all nodes at given depth.
+	 *
+	 * @param int $i
+	 *
+	 * @return PolicyNode[]
+	 */
+	protected function _nodesAtDepth(int $i): array
+	{
+		if (!$this->_root) {
+			return [];
+		}
+		$depth = 0;
+		$nodes = [$this->_root];
+		while ($depth < $i) {
+			$nodes = self::_gatherChildren(...$nodes);
+			if (!count($nodes)) {
+				break;
+			}
+			++$depth;
+		}
+		return $nodes;
+	}
 
-    /**
-     * Get the valid policy node set as specified in spec 6.1.5.(g)(iii)1.
-     *
-     * @return PolicyNode[]
-     */
-    protected function _validPolicyNodeSet(): array
-    {
-        // 1. Determine the set of policy nodes whose parent nodes have
-        // a valid_policy of anyPolicy. This is the valid_policy_node_set.
-        $set = [];
-        if (!$this->_root) {
-            return $set;
-        }
-        // for each node in a tree
-        $this->_root->walkNodes(
-            function (PolicyNode $node) use (&$set) {
-                $parents = $node->parents();
-                // node has parents
-                if (count($parents)) {
-                    // check that each ancestor is an anyPolicy node
-                    foreach ($parents as $ancestor) {
-                        if (!$ancestor->isAnyPolicy()) {
-                            return;
-                        }
-                    }
-                    $set[] = $node;
-                }
-            });
-        return $set;
-    }
+	/**
+	 * Get the valid policy node set as specified in spec 6.1.5.(g)(iii)1.
+	 *
+	 * @return PolicyNode[]
+	 */
+	protected function _validPolicyNodeSet(): array
+	{
+		// 1. Determine the set of policy nodes whose parent nodes have
+		// a valid_policy of anyPolicy. This is the valid_policy_node_set.
+		$set = [];
+		if (!$this->_root) {
+			return $set;
+		}
+		// for each node in a tree
+		$this->_root->walkNodes(
+			function (PolicyNode $node) use (&$set) {
+				$parents = $node->parents();
+				// node has parents
+				if (count($parents)) {
+					// check that each ancestor is an anyPolicy node
+					foreach ($parents as $ancestor) {
+						if (!$ancestor->isAnyPolicy()) {
+							return;
+						}
+					}
+					$set[] = $node;
+				}
+			});
+		return $set;
+	}
 
-    /**
-     * Gather all children of given nodes to a flattened array.
-     *
-     * @param PolicyNode ...$nodes
-     *
-     * @return PolicyNode[]
-     */
-    private static function _gatherChildren(PolicyNode ...$nodes): array
-    {
-        $children = [];
-        foreach ($nodes as $node) {
-            $children = array_merge($children, $node->children());
-        }
-        return $children;
-    }
+	/**
+	 * Gather all children of given nodes to a flattened array.
+	 *
+	 * @param PolicyNode ...$nodes
+	 *
+	 * @return PolicyNode[]
+	 */
+	private static function _gatherChildren(PolicyNode ...$nodes): array
+	{
+		$children = [];
+		foreach ($nodes as $node) {
+			$children = array_merge($children, $node->children());
+		}
+		return $children;
+	}
 }