text: /* $OpenBSD: pcy_tree.c,v 1.14 2015/07/15 17:02:03 miod Exp $ */
  /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
   * project 2004.
   */
  /* ====================================================================
   * Copyright (c) 2004 The OpenSSL Project.  All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * 3. All advertising materials mentioning features or use of this
   *    software must display the following acknowledgment:
   *    "This product includes software developed by the OpenSSL Project
   *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
   *
   * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
   *    endorse or promote products derived from this software without
   *    prior written permission. For written permission, please contact
   *    licensing@OpenSSL.org.
   *
   * 5. Products derived from this software may not be called "OpenSSL"
   *    nor may "OpenSSL" appear in their names without prior written
   *    permission of the OpenSSL Project.
   *
   * 6. Redistributions of any form whatsoever must retain the following
   *    acknowledgment:
   *    "This product includes software developed by the OpenSSL Project
   *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
   *
   * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
   * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
   * OF THE POSSIBILITY OF SUCH DAMAGE.
   * ====================================================================
   *
   * This product includes cryptographic software written by Eric Young
   * (eay@cryptsoft.com).  This product includes software written by Tim
   * Hudson (tjh@cryptsoft.com).
   *
   */
  
  #include <openssl/x509.h>
  #include <openssl/x509v3.h>
  
  #include "pcy_int.h"
  
  /* Enable this to print out the complete policy tree at various point during
   * evaluation.
   */
  
  /*#define OPENSSL_POLICY_DEBUG*/
  
  #ifdef OPENSSL_POLICY_DEBUG
  
  static void
  expected_print(BIO *err, X509_POLICY_LEVEL *lev, X509_POLICY_NODE *node,
      int indent)
  {
  	if ((lev->flags & X509_V_FLAG_INHIBIT_MAP) ||
  	    !(node->data->flags & POLICY_DATA_FLAG_MAP_MASK))
  		BIO_puts(err, "  Not Mapped\n");
  	else {
  		int i;
  		STACK_OF(ASN1_OBJECT) *pset = node->data->expected_policy_set;
  		ASN1_OBJECT *oid;
  		BIO_puts(err, "  Expected: ");
  		for (i = 0; i < sk_ASN1_OBJECT_num(pset); i++) {
  			oid = sk_ASN1_OBJECT_value(pset, i);
  			if (i)
  				BIO_puts(err, ", ");
  			i2a_ASN1_OBJECT(err, oid);
  		}
  		BIO_puts(err, "\n");
  	}
  }
  
  static void
  tree_print(char *str, X509_POLICY_TREE *tree, X509_POLICY_LEVEL *curr)
  {
  	X509_POLICY_LEVEL *plev;
  	X509_POLICY_NODE *node;
  	int i;
  	BIO *err;
  
  	err = BIO_new_fp(stderr, BIO_NOCLOSE);
  	if (!curr)
  		curr = tree->levels + tree->nlevel;
  	else
  		curr++;
  	BIO_printf(err, "Level print after %s\n", str);
  	BIO_printf(err, "Printing Up to Level %ld\n", curr - tree->levels);
  	for (plev = tree->levels; plev != curr; plev++) {
  		BIO_printf(err, "Level %ld, flags = %x\n",
  		    plev - tree->levels, plev->flags);
  		for (i = 0; i < sk_X509_POLICY_NODE_num(plev->nodes); i++) {
  			node = sk_X509_POLICY_NODE_value(plev->nodes, i);
  			X509_POLICY_NODE_print(err, node, 2);
  			expected_print(err, plev, node, 2);
  			BIO_printf(err, "  Flags: %x\n", node->data->flags);
  		}
  		if (plev->anyPolicy)
  			X509_POLICY_NODE_print(err, plev->anyPolicy, 2);
  	}
  
  	BIO_free(err);
  }
  #else
  
  #define tree_print(a,b,c) /* */
  
  #endif
  
  /* Initialize policy tree. Return values:
   *  0 Some internal error occured.
   * -1 Inconsistent or invalid extensions in certificates.
   *  1 Tree initialized OK.
   *  2 Policy tree is empty.
   *  5 Tree OK and requireExplicitPolicy true.
   *  6 Tree empty and requireExplicitPolicy true.
   */
  
  static int
  tree_init(X509_POLICY_TREE **ptree, STACK_OF(X509) *certs, unsigned int flags)
  {
  	X509_POLICY_TREE *tree;
  	X509_POLICY_LEVEL *level;
  	const X509_POLICY_CACHE *cache;
  	X509_POLICY_DATA *data = NULL;
  	X509 *x;
  	int ret = 1;
  	int i, n;
  	int explicit_policy;
  	int any_skip;
  	int map_skip;
  
  	*ptree = NULL;
  	n = sk_X509_num(certs);
  
  	if (flags & X509_V_FLAG_EXPLICIT_POLICY)
  		explicit_policy = 0;
  	else
  		explicit_policy = n + 1;
  
  	if (flags & X509_V_FLAG_INHIBIT_ANY)
  		any_skip = 0;
  	else
  		any_skip = n + 1;
  
  	if (flags & X509_V_FLAG_INHIBIT_MAP)
  		map_skip = 0;
  	else
  		map_skip = n + 1;
  
  	/* Can't do anything with just a trust anchor */
  	if (n == 1)
  		return 1;
  	/* First setup policy cache in all certificates apart from the
  	 * trust anchor. Note any bad cache results on the way. Also can
  	 * calculate explicit_policy value at this point.
  	 */
  	for (i = n - 2; i >= 0; i--) {
  		x = sk_X509_value(certs, i);
  		X509_check_purpose(x, -1, -1);
  		cache = policy_cache_set(x);
  		/* If cache NULL something bad happened: return immediately */
  		if (cache == NULL)
  			return 0;
  		/* If inconsistent extensions keep a note of it but continue */
  		if (x->ex_flags & EXFLAG_INVALID_POLICY)
  			ret = -1;
  		/* Otherwise if we have no data (hence no CertificatePolicies)
  		 * and haven't already set an inconsistent code note it.
  		 */
  		else if ((ret == 1) && !cache->data)
  			ret = 2;
  		if (explicit_policy > 0) {
  			if (!(x->ex_flags & EXFLAG_SI))
  				explicit_policy--;
  			if ((cache->explicit_skip != -1) &&
  			    (cache->explicit_skip < explicit_policy))
  				explicit_policy = cache->explicit_skip;
  		}
  	}
  
  	if (ret != 1) {
  		if (ret == 2 && !explicit_policy)
  			return 6;
  		return ret;
  	}
  
  
  	/* If we get this far initialize the tree */
  
  	tree = malloc(sizeof(X509_POLICY_TREE));
  
  	if (!tree)
  		return 0;
  
  	tree->flags = 0;
  	tree->levels = calloc(n, sizeof(X509_POLICY_LEVEL));
  	tree->nlevel = 0;
  	tree->extra_data = NULL;
  	tree->auth_policies = NULL;
  	tree->user_policies = NULL;
  
  	if (!tree->levels) {
  		free(tree);
  		return 0;
  	}
  
  	tree->nlevel = n;
  
  	level = tree->levels;
  
  	/* Root data: initialize to anyPolicy */
  
  	data = policy_data_new(NULL, OBJ_nid2obj(NID_any_policy), 0);
  
  	if (!data || !level_add_node(level, data, NULL, tree, NULL))
  		goto bad_tree;
  
  	for (i = n - 2; i >= 0; i--) {
  		level++;
  		x = sk_X509_value(certs, i);
  		cache = policy_cache_set(x);
  		CRYPTO_add(&x->references, 1, CRYPTO_LOCK_X509);
  		level->cert = x;
  
  		if (!cache->anyPolicy)
  			level->flags |= X509_V_FLAG_INHIBIT_ANY;
  
  		/* Determine inhibit any and inhibit map flags */
  		if (any_skip == 0) {
  			/* Any matching allowed if certificate is self
  			 * issued and not the last in the chain.
  			 */
  			if (!(x->ex_flags & EXFLAG_SI) || (i == 0))
  				level->flags |= X509_V_FLAG_INHIBIT_ANY;
  		} else {
  			if (!(x->ex_flags & EXFLAG_SI))
  				any_skip--;
  			if ((cache->any_skip >= 0) &&
  			    (cache->any_skip < any_skip))
  				any_skip = cache->any_skip;
  		}
  
  		if (map_skip == 0)
  			level->flags |= X509_V_FLAG_INHIBIT_MAP;
  		else {
  			if (!(x->ex_flags & EXFLAG_SI))
  				map_skip--;
  			if ((cache->map_skip >= 0) &&
  			    (cache->map_skip < map_skip))
  				map_skip = cache->map_skip;
  		}
  
  	}
  
  	*ptree = tree;
  
  	if (explicit_policy)
  		return 1;
  	else
  		return 5;
  
  bad_tree:
  	X509_policy_tree_free(tree);
  
  	return 0;
  }
  
  static int
  tree_link_matching_nodes(X509_POLICY_LEVEL *curr, const X509_POLICY_DATA *data)
  {
  	X509_POLICY_LEVEL *last = curr - 1;
  	X509_POLICY_NODE *node;
  	int i, matched = 0;
  
  	/* Iterate through all in nodes linking matches */
  	for (i = 0; i < sk_X509_POLICY_NODE_num(last->nodes); i++) {
  		node = sk_X509_POLICY_NODE_value(last->nodes, i);
  		if (policy_node_match(last, node, data->valid_policy)) {
  			if (!level_add_node(curr, data, node, NULL, NULL))
  				return 0;
  			matched = 1;
  		}
  	}
  	if (!matched && last->anyPolicy) {
  		if (!level_add_node(curr, data, last->anyPolicy, NULL, NULL))
  			return 0;
  	}
  	return 1;
  }
  
  /* This corresponds to RFC3280 6.1.3(d)(1):
   * link any data from CertificatePolicies onto matching parent
   * or anyPolicy if no match.
   */
  
  static int
  tree_link_nodes(X509_POLICY_LEVEL *curr, const X509_POLICY_CACHE *cache)
  {
  	int i;
  	X509_POLICY_DATA *data;
  
  	for (i = 0; i < sk_X509_POLICY_DATA_num(cache->data); i++) {
  		data = sk_X509_POLICY_DATA_value(cache->data, i);
  		/* Look for matching nodes in previous level */
  		if (!tree_link_matching_nodes(curr, data))
  			return 0;
  	}
  	return 1;
  }
  
  /* This corresponds to RFC3280 6.1.3(d)(2):
   * Create new data for any unmatched policies in the parent and link
   * to anyPolicy.
   */
  
  static int
  tree_add_unmatched(X509_POLICY_LEVEL *curr, const X509_POLICY_CACHE *cache,
      const ASN1_OBJECT *id, X509_POLICY_NODE *node, X509_POLICY_TREE *tree)
  {
  	X509_POLICY_DATA *data;
  
  	if (id == NULL)
  		id = node->data->valid_policy;
  	/* Create a new node with qualifiers from anyPolicy and
  	 * id from unmatched node.
  	 */
  	data = policy_data_new(NULL, id, node_critical(node));
  
  	if (data == NULL)
  		return 0;
  	/* Curr may not have anyPolicy */
  	data->qualifier_set = cache->anyPolicy->qualifier_set;
  	data->flags |= POLICY_DATA_FLAG_SHARED_QUALIFIERS;
  	if (!level_add_node(curr, data, node, tree, NULL)) {
  		policy_data_free(data);
  		return 0;
  	}
  
  	return 1;
  }
  
  static int
  tree_link_unmatched(X509_POLICY_LEVEL *curr, const X509_POLICY_CACHE *cache,
      X509_POLICY_NODE *node, X509_POLICY_TREE *tree)
  {
  	const X509_POLICY_LEVEL *last = curr - 1;
  	int i;
  
  	if ((last->flags & X509_V_FLAG_INHIBIT_MAP) ||
  	    !(node->data->flags & POLICY_DATA_FLAG_MAPPED)) {
  		/* If no policy mapping: matched if one child present */
  		if (node->nchild)
  			return 1;
  		if (!tree_add_unmatched(curr, cache, NULL, node, tree))
  			return 0;
  		/* Add it */
  	} else {
  		/* If mapping: matched if one child per expected policy set */
  		STACK_OF(ASN1_OBJECT) *expset = node->data->expected_policy_set;
  		if (node->nchild == sk_ASN1_OBJECT_num(expset))
  			return 1;
  		/* Locate unmatched nodes */
  		for (i = 0; i < sk_ASN1_OBJECT_num(expset); i++) {
  			ASN1_OBJECT *oid = sk_ASN1_OBJECT_value(expset, i);
  			if (level_find_node(curr, node, oid))
  				continue;
  			if (!tree_add_unmatched(curr, cache, oid, node, tree))
  				return 0;
  		}
  	}
  
  	return 1;
  }
  
  static int
  tree_link_any(X509_POLICY_LEVEL *curr, const X509_POLICY_CACHE *cache,
      X509_POLICY_TREE *tree)
  {
  	int i;
  	X509_POLICY_NODE *node;
  	X509_POLICY_LEVEL *last = curr - 1;
  
  	for (i = 0; i < sk_X509_POLICY_NODE_num(last->nodes); i++) {
  		node = sk_X509_POLICY_NODE_value(last->nodes, i);
  
  		if (!tree_link_unmatched(curr, cache, node, tree))
  			return 0;
  	}
  	/* Finally add link to anyPolicy */
  	if (last->anyPolicy) {
  		if (!level_add_node(curr, cache->anyPolicy,
  		    last->anyPolicy, NULL, NULL))
  			return 0;
  	}
  	return 1;
  }
  
  /* Prune the tree: delete any child mapped child data on the current level
   * then proceed up the tree deleting any data with no children. If we ever
   * have no data on a level we can halt because the tree will be empty.
   */
  
  static int
  tree_prune(X509_POLICY_TREE *tree, X509_POLICY_LEVEL *curr)
  {
  	STACK_OF(X509_POLICY_NODE) *nodes;
  	X509_POLICY_NODE *node;
  	int i;
  
  	nodes = curr->nodes;
  	if (curr->flags & X509_V_FLAG_INHIBIT_MAP) {
  		for (i = sk_X509_POLICY_NODE_num(nodes) - 1; i >= 0; i--) {
  			node = sk_X509_POLICY_NODE_value(nodes, i);
  			/* Delete any mapped data: see RFC3280 XXXX */
  			if (node->data->flags & POLICY_DATA_FLAG_MAP_MASK) {
  				node->parent->nchild--;
  				free(node);
  				(void)sk_X509_POLICY_NODE_delete(nodes, i);
  			}
  		}
  	}
  
  	for (;;) {
  		--curr;
  		nodes = curr->nodes;
  		for (i = sk_X509_POLICY_NODE_num(nodes) - 1; i >= 0; i--) {
  			node = sk_X509_POLICY_NODE_value(nodes, i);
  			if (node->nchild == 0) {
  				node->parent->nchild--;
  				free(node);
  				(void)sk_X509_POLICY_NODE_delete(nodes, i);
  			}
  		}
  		if (curr->anyPolicy && !curr->anyPolicy->nchild) {
  			if (curr->anyPolicy->parent)
  				curr->anyPolicy->parent->nchild--;
  			free(curr->anyPolicy);
  			curr->anyPolicy = NULL;
  		}
  		if (curr == tree->levels) {
  			/* If we zapped anyPolicy at top then tree is empty */
  			if (!curr->anyPolicy)
  				return 2;
  			return 1;
  		}
  	}
  
  	return 1;
  }
  
  static int
  tree_add_auth_node(STACK_OF(X509_POLICY_NODE) **pnodes, X509_POLICY_NODE *pcy)
  {
  	if (!*pnodes) {
  		*pnodes = policy_node_cmp_new();
  		if (!*pnodes)
  			return 0;
  	} else if (sk_X509_POLICY_NODE_find(*pnodes, pcy) != -1)
  		return 1;
  
  	if (!sk_X509_POLICY_NODE_push(*pnodes, pcy))
  		return 0;
  
  	return 1;
  }
  
  /* Calculate the authority set based on policy tree.
   * The 'pnodes' parameter is used as a store for the set of policy nodes
   * used to calculate the user set. If the authority set is not anyPolicy
   * then pnodes will just point to the authority set. If however the authority
   * set is anyPolicy then the set of valid policies (other than anyPolicy)
   * is store in pnodes. The return value of '2' is used in this case to indicate
   * that pnodes should be freed.
   */
  
  static int
  tree_calculate_authority_set(X509_POLICY_TREE *tree,
      STACK_OF(X509_POLICY_NODE) **pnodes)
  {
  	X509_POLICY_LEVEL *curr;
  	X509_POLICY_NODE *node, *anyptr;
  	STACK_OF(X509_POLICY_NODE) **addnodes;
  	int i, j;
  
  	curr = tree->levels + tree->nlevel - 1;
  
  	/* If last level contains anyPolicy set is anyPolicy */
  	if (curr->anyPolicy) {
  		if (!tree_add_auth_node(&tree->auth_policies, curr->anyPolicy))
  			return 0;
  		addnodes = pnodes;
  	} else
  		/* Add policies to authority set */
  		addnodes = &tree->auth_policies;
  
  	curr = tree->levels;
  	for (i = 1; i < tree->nlevel; i++) {
  		/* If no anyPolicy node on this this level it can't
  		 * appear on lower levels so end search.
  		 */
  		if (!(anyptr = curr->anyPolicy))
  			break;
  		curr++;
  		for (j = 0; j < sk_X509_POLICY_NODE_num(curr->nodes); j++) {
  			node = sk_X509_POLICY_NODE_value(curr->nodes, j);
  			if ((node->parent == anyptr) &&
  			    !tree_add_auth_node(addnodes, node))
  				return 0;
  		}
  	}
  
  	if (addnodes == pnodes)
  		return 2;
  
  	*pnodes = tree->auth_policies;
  
  	return 1;
  }
  
  static int
  tree_calculate_user_set(X509_POLICY_TREE *tree,
      STACK_OF(ASN1_OBJECT) *policy_oids, STACK_OF(X509_POLICY_NODE) *auth_nodes)
  {
  	int i;
  	X509_POLICY_NODE *node;
  	ASN1_OBJECT *oid;
  	X509_POLICY_NODE *anyPolicy;
  	X509_POLICY_DATA *extra;
  
  	/* Check if anyPolicy present in authority constrained policy set:
  	 * this will happen if it is a leaf node.
  	 */
  
  	if (sk_ASN1_OBJECT_num(policy_oids) <= 0)
  		return 1;
  
  	anyPolicy = tree->levels[tree->nlevel - 1].anyPolicy;
  
  	for (i = 0; i < sk_ASN1_OBJECT_num(policy_oids); i++) {
  		oid = sk_ASN1_OBJECT_value(policy_oids, i);
  		if (OBJ_obj2nid(oid) == NID_any_policy) {
  			tree->flags |= POLICY_FLAG_ANY_POLICY;
  			return 1;
  		}
  	}
  
  	for (i = 0; i < sk_ASN1_OBJECT_num(policy_oids); i++) {
  		oid = sk_ASN1_OBJECT_value(policy_oids, i);
  		node = tree_find_sk(auth_nodes, oid);
  		if (!node) {
  			if (!anyPolicy)
  				continue;
  			/* Create a new node with policy ID from user set
  			 * and qualifiers from anyPolicy.
  			 */
  			extra = policy_data_new(NULL, oid,
  			    node_critical(anyPolicy));
  			if (!extra)
  				return 0;
  			extra->qualifier_set = anyPolicy->data->qualifier_set;
  			extra->flags = POLICY_DATA_FLAG_SHARED_QUALIFIERS |
  			    POLICY_DATA_FLAG_EXTRA_NODE;
  			(void) level_add_node(NULL, extra, anyPolicy->parent,
  			    tree, &node);
  		}
  		if (!tree->user_policies) {
  			tree->user_policies = sk_X509_POLICY_NODE_new_null();
  			if (!tree->user_policies)
  				return 1;
  		}
  		if (!sk_X509_POLICY_NODE_push(tree->user_policies, node))
  			return 0;
  	}
  	return 1;
  }
  
  static int
  tree_evaluate(X509_POLICY_TREE *tree)
  {
  	int ret, i;
  	X509_POLICY_LEVEL *curr = tree->levels + 1;
  	const X509_POLICY_CACHE *cache;
  
  	for (i = 1; i < tree->nlevel; i++, curr++) {
  		cache = policy_cache_set(curr->cert);
  		if (!tree_link_nodes(curr, cache))
  			return 0;
  
  		if (!(curr->flags & X509_V_FLAG_INHIBIT_ANY) &&
  		    !tree_link_any(curr, cache, tree))
  			return 0;
  		tree_print("before tree_prune()", tree, curr);
  		ret = tree_prune(tree, curr);
  		if (ret != 1)
  			return ret;
  	}
  
  	return 1;
  }
  
  static void
  exnode_free(X509_POLICY_NODE *node)
  {
  	if (node->data && (node->data->flags & POLICY_DATA_FLAG_EXTRA_NODE))
  		free(node);
  }
  
  void
  X509_policy_tree_free(X509_POLICY_TREE *tree)
  {
  	X509_POLICY_LEVEL *curr;
  	int i;
  
  	if (!tree)
  		return;
  
  	sk_X509_POLICY_NODE_free(tree->auth_policies);
  	sk_X509_POLICY_NODE_pop_free(tree->user_policies, exnode_free);
  
  	for (i = 0, curr = tree->levels; i < tree->nlevel; i++, curr++) {
  		if (curr->cert)
  			X509_free(curr->cert);
  		if (curr->nodes)
  			sk_X509_POLICY_NODE_pop_free(curr->nodes,
  		    policy_node_free);
  		if (curr->anyPolicy)
  			policy_node_free(curr->anyPolicy);
  	}
  
  	if (tree->extra_data)
  		sk_X509_POLICY_DATA_pop_free(tree->extra_data,
  		    policy_data_free);
  
  	free(tree->levels);
  	free(tree);
  }
  
  /* Application policy checking function.
   * Return codes:
   *  0 	Internal Error.
   *  1   Successful.
   * -1   One or more certificates contain invalid or inconsistent extensions
   * -2	User constrained policy set empty and requireExplicit true.
   */
  
  int
  X509_policy_check(X509_POLICY_TREE **ptree, int *pexplicit_policy,
      STACK_OF(X509) *certs, STACK_OF(ASN1_OBJECT) *policy_oids,
      unsigned int flags)
  {
  	int ret, ret2;
  	X509_POLICY_TREE *tree = NULL;
  	STACK_OF(X509_POLICY_NODE) *nodes, *auth_nodes = NULL;
  
  	*ptree = NULL;
  	*pexplicit_policy = 0;
  	ret = tree_init(&tree, certs, flags);
  
  	switch (ret) {
  
  		/* Tree empty requireExplicit False: OK */
  	case 2:
  		return 1;
  
  		/* Some internal error */
  	case -1:
  		return -1;
  
  		/* Some internal error */
  	case 0:
  		return 0;
  
  		/* Tree empty requireExplicit True: Error */
  
  	case 6:
  		*pexplicit_policy = 1;
  		return -2;
  
  		/* Tree OK requireExplicit True: OK and continue */
  	case 5:
  		*pexplicit_policy = 1;
  		break;
  
  		/* Tree OK: continue */
  
  	case 1:
  		if (!tree)
  			/*
  			 * tree_init() returns success and a null tree
  			 * if it's just looking at a trust anchor.
  			 * I'm not sure that returning success here is
  			 * correct, but I'm sure that reporting this
  			 * as an internal error which our caller
  			 * interprets as a malloc failure is wrong.
  			 */
  			return 1;
  		break;
  	}
  
  	if (!tree)
  		goto error;
  	ret = tree_evaluate(tree);
  
  	tree_print("tree_evaluate()", tree, NULL);
  
  	if (ret <= 0)
  		goto error;
  
  	/* Return value 2 means tree empty */
  	if (ret == 2) {
  		X509_policy_tree_free(tree);
  		if (*pexplicit_policy)
  			return -2;
  		else
  			return 1;
  	}
  
  	/* Tree is not empty: continue */
  
  	ret = tree_calculate_authority_set(tree, &auth_nodes);
  	if (ret == 0)
  		goto error;
  
  	ret2 = tree_calculate_user_set(tree, policy_oids, auth_nodes);
  
  	/* Return value 2 means auth_nodes needs to be freed */
  	if (ret == 2)
  		sk_X509_POLICY_NODE_free(auth_nodes);
  
  	if (ret2 == 0)
  		goto error;
  
  	if (tree)
  		*ptree = tree;
  
  	if (*pexplicit_policy) {
  		nodes = X509_policy_tree_get0_user_policies(tree);
  		if (sk_X509_POLICY_NODE_num(nodes) <= 0)
  			return -2;
  	}
  
  	return 1;
  
  error:
  	X509_policy_tree_free(tree);
  
  	return 0;
  }
  