crypto/x509v3/pcy_tree.c - boringssl - Git at Google

 /*
  * 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 <string.h>

 #include <openssl/mem.h>
 #include <openssl/obj.h>
 #include <openssl/stack.h>
 #include <openssl/thread.h>
 #include <openssl/x509.h>
 #include <openssl/x509v3.h>

 #include "../internal.h"
 #include "../x509/internal.h"
 #include "internal.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 occurred.
 // -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 0
     // Disable policy mapping for now...
     flags |= X509_V_FLAG_INHIBIT_MAP;
 #endif

   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 = OPENSSL_malloc(sizeof(X509_POLICY_TREE));

   if (!tree) {
     return 0;
   }

   tree->flags = 0;
   tree->levels = OPENSSL_malloc(sizeof(X509_POLICY_LEVEL) * n);
   tree->nlevel = 0;
   tree->extra_data = NULL;
   tree->auth_policies = NULL;
   tree->user_policies = NULL;

   if (!tree->levels) {
     OPENSSL_free(tree);
     return 0;
   }

   OPENSSL_memset(tree->levels, 0, n * sizeof(X509_POLICY_LEVEL));

   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)) {
     goto bad_tree;
   }

   for (i = n - 2; i >= 0; i--) {
     level++;
     x = sk_X509_value(certs, i);
     cache = policy_cache_set(x);
     X509_up_ref(x);
     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,
                                     X509_POLICY_DATA *data) {
   X509_POLICY_LEVEL *last = curr - 1;
   X509_POLICY_NODE *node;
   int matched = 0;
   size_t i;
   // 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)) {
         return 0;
       }
       matched = 1;
     }
   }
   if (!matched && last->anyPolicy) {
     if (!level_add_node(curr, data, last->anyPolicy, NULL)) {
       return 0;
     }
   }
   return 1;
 }

 // This corresponds to RFC 3280 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) {
   size_t 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);
     // If a node is mapped any it doesn't have a corresponding
     // CertificatePolicies entry. However such an identical node would
     // be created if anyPolicy matching is enabled because there would be
     // no match with the parent valid_policy_set. So we create link
     // because then it will have the mapping flags right and we can prune
     // it later.
 #if 0
         if ((data->flags & POLICY_DATA_FLAG_MAPPED_ANY)
             && !(curr->flags & X509_V_FLAG_INHIBIT_ANY))
             continue;
 #endif
     // Look for matching nodes in previous level
     if (!tree_link_matching_nodes(curr, data)) {
       return 0;
     }
   }
   return 1;
 }

 // This corresponds to RFC 3280 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)) {
     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;
   size_t 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 ((size_t)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) {
   size_t i;
   // X509_POLICY_DATA *data;
   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;
     }

 #if 0

         // Skip any node with any children: we only want unmathced nodes.
         // Note: need something better for policy mapping because each node
         // may have multiple children
         if (node->nchild)
             continue;

         // Create a new node with qualifiers from anyPolicy and id from
         // unmatched node.
         data = policy_data_new(NULL, node->data->valid_policy,
                                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)) {
             policy_data_free(data);
             return 0;
         }
 #endif
   }
   // Finally add link to anyPolicy
   if (last->anyPolicy) {
     if (!level_add_node(curr, cache->anyPolicy, last->anyPolicy, 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 RFC 3280 XXXX
       if (node->data->flags & POLICY_DATA_FLAG_MAP_MASK) {
         node->parent->nchild--;
         OPENSSL_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--;
         OPENSSL_free(node);
         (void)sk_X509_POLICY_NODE_delete(nodes, i);
       }
     }
     if (curr->anyPolicy && !curr->anyPolicy->nchild) {
       if (curr->anyPolicy->parent) {
         curr->anyPolicy->parent->nchild--;
       }
       OPENSSL_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;
     }
   }
 }

 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 {
     sk_X509_POLICY_NODE_sort(*pnodes);
     if (sk_X509_POLICY_NODE_find(*pnodes, NULL, pcy)) {
       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;
   size_t 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) {
   size_t 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;
       node = level_add_node(NULL, extra, anyPolicy->parent, tree);
     }
     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)) {
     OPENSSL_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);
   }

   OPENSSL_free(tree->levels);
   OPENSSL_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;
   int calc_ret;
   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

   calc_ret = tree_calculate_authority_set(tree, &auth_nodes);

   if (!calc_ret) {
     goto error;
   }

   ret = tree_calculate_user_set(tree, policy_oids, auth_nodes);

   if (calc_ret == 2) {
     sk_X509_POLICY_NODE_free(auth_nodes);
   }

   if (!ret) {
     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;
 }
	/*
	* 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 <string.h>

	#include <openssl/mem.h>
	#include <openssl/obj.h>
	#include <openssl/stack.h>
	#include <openssl/thread.h>
	#include <openssl/x509.h>
	#include <openssl/x509v3.h>

	#include "../internal.h"
	#include "../x509/internal.h"
	#include "internal.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 occurred.
	// -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 0
	// Disable policy mapping for now...
	flags \|= X509_V_FLAG_INHIBIT_MAP;
	#endif

	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 = OPENSSL_malloc(sizeof(X509_POLICY_TREE));

	if (!tree) {
	return 0;
	}

	tree->flags = 0;
	tree->levels = OPENSSL_malloc(sizeof(X509_POLICY_LEVEL) * n);
	tree->nlevel = 0;
	tree->extra_data = NULL;
	tree->auth_policies = NULL;
	tree->user_policies = NULL;

	if (!tree->levels) {
	OPENSSL_free(tree);
	return 0;
	}

	OPENSSL_memset(tree->levels, 0, n * sizeof(X509_POLICY_LEVEL));

	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)) {
	goto bad_tree;
	}

	for (i = n - 2; i >= 0; i--) {
	level++;
	x = sk_X509_value(certs, i);
	cache = policy_cache_set(x);
	X509_up_ref(x);
	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,
	X509_POLICY_DATA *data) {
	X509_POLICY_LEVEL *last = curr - 1;
	X509_POLICY_NODE *node;
	int matched = 0;
	size_t i;
	// 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)) {
	return 0;
	}
	matched = 1;
	}
	}
	if (!matched && last->anyPolicy) {
	if (!level_add_node(curr, data, last->anyPolicy, NULL)) {
	return 0;
	}
	}
	return 1;
	}

	// This corresponds to RFC 3280 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) {
	size_t 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);
	// If a node is mapped any it doesn't have a corresponding
	// CertificatePolicies entry. However such an identical node would
	// be created if anyPolicy matching is enabled because there would be
	// no match with the parent valid_policy_set. So we create link
	// because then it will have the mapping flags right and we can prune
	// it later.
	#if 0
	if ((data->flags & POLICY_DATA_FLAG_MAPPED_ANY)
	&& !(curr->flags & X509_V_FLAG_INHIBIT_ANY))
	continue;
	#endif
	// Look for matching nodes in previous level
	if (!tree_link_matching_nodes(curr, data)) {
	return 0;
	}
	}
	return 1;
	}

	// This corresponds to RFC 3280 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)) {
	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;
	size_t 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 ((size_t)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) {
	size_t i;
	// X509_POLICY_DATA *data;
	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;
	}

	#if 0

	// Skip any node with any children: we only want unmathced nodes.
	// Note: need something better for policy mapping because each node
	// may have multiple children
	if (node->nchild)
	continue;

	// Create a new node with qualifiers from anyPolicy and id from
	// unmatched node.
	data = policy_data_new(NULL, node->data->valid_policy,
	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)) {
	policy_data_free(data);
	return 0;
	}
	#endif
	}
	// Finally add link to anyPolicy
	if (last->anyPolicy) {
	if (!level_add_node(curr, cache->anyPolicy, last->anyPolicy, 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 RFC 3280 XXXX
	if (node->data->flags & POLICY_DATA_FLAG_MAP_MASK) {
	node->parent->nchild--;
	OPENSSL_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--;
	OPENSSL_free(node);
	(void)sk_X509_POLICY_NODE_delete(nodes, i);
	}
	}
	if (curr->anyPolicy && !curr->anyPolicy->nchild) {
	if (curr->anyPolicy->parent) {
	curr->anyPolicy->parent->nchild--;
	}
	OPENSSL_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;
	}
	}
	}

	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 {
	sk_X509_POLICY_NODE_sort(*pnodes);
	if (sk_X509_POLICY_NODE_find(*pnodes, NULL, pcy)) {
	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;
	size_t 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) {
	size_t 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;
	node = level_add_node(NULL, extra, anyPolicy->parent, tree);
	}
	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)) {
	OPENSSL_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);
	}

	OPENSSL_free(tree->levels);
	OPENSSL_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;
	int calc_ret;
	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

	calc_ret = tree_calculate_authority_set(tree, &auth_nodes);

	if (!calc_ret) {
	goto error;
	}

	ret = tree_calculate_user_set(tree, policy_oids, auth_nodes);

	if (calc_ret == 2) {
	sk_X509_POLICY_NODE_free(auth_nodes);
	}

	if (!ret) {
	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;
	}