/*
 * 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;
}