source: vendor/3.6.0/libcli/security/object_tree.c

/*
   Unix SMB/CIFS implementation.

   security access checking routines

   Copyright (C) Nadezhda Ivanova 2009

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/*
 *  Description: Contains data handler functions for
 *               the object tree that must be constructed to perform access checks.
 *               The object tree is an unbalanced tree of depth 3, indexed by
 *               object type guid. Perhaps a different data structure
 *               should be concidered later to improve performance
 *
 *  Author: Nadezhda Ivanova
 */
#include "includes.h"
#include "libcli/security/security.h"
#include "librpc/ndr/libndr.h"

/* Adds a new node to the object tree. If attributeSecurityGUID is not zero and
 * has already been added to the tree, the new node is added as a child of that node
 * In all other cases as a child of the root
 */

bool insert_in_object_tree(TALLOC_CTX *mem_ctx,
                          const struct GUID *guid,
                          uint32_t init_access,
                          struct object_tree **root,
                          struct object_tree **new_node)
{
        if (!guid || GUID_all_zero(guid)){
                return true;
        }

        if (!*root){
                *root = talloc_zero(mem_ctx, struct object_tree);
                if (!*root) {
                        return false;
                }
                (*root)->guid = *guid;
                *new_node = *root;
                return true;
        }

        if (!(*root)->children) {
                (*root)->children = talloc_array(mem_ctx, struct object_tree, 1);
                (*root)->children[0].guid = *guid;
                (*root)->children[0].num_of_children = 0;
                (*root)->children[0].children = NULL;
                (*root)->num_of_children++;
                (*root)->children[0].remaining_access = init_access;
                *new_node = &((*root)->children[0]);
                return true;
        }
        else {
                int i;
                for (i = 0; i < (*root)->num_of_children; i++) {
                        if (GUID_equal(&((*root)->children[i].guid), guid)) {
                                *new_node = &((*root)->children[i]);
                                return true;
                        }
                }
                (*root)->children = talloc_realloc(mem_ctx, (*root)->children, struct object_tree,
                                                   (*root)->num_of_children +1);
                (*root)->children[(*root)->num_of_children].guid = *guid;
                (*root)->children[(*root)->num_of_children].remaining_access = init_access;
                *new_node = &((*root)->children[(*root)->num_of_children]);
                (*root)->num_of_children++;
                return true;
        }
}

/* search by GUID */
struct object_tree *get_object_tree_by_GUID(struct object_tree *root,
                                             const struct GUID *guid)
{
        struct object_tree *result = NULL;
        int i;

        if (!root || GUID_equal(&root->guid, guid)) {
                result = root;
                return result;
        }
        else if (root->num_of_children > 0) {
                for (i = 0; i < root->num_of_children; i++) {
                if ((result = get_object_tree_by_GUID(&root->children[i], guid)))
                        break;
                }
        }
        return result;
}

/* Change the granted access per each ACE */

void object_tree_modify_access(struct object_tree *root,
                               uint32_t access_mask)
{
        root->remaining_access &= ~access_mask;
        if (root->num_of_children > 0) {
                int i;
                for (i = 0; i < root->num_of_children; i++) {
                        object_tree_modify_access(&root->children[i], access_mask);
                }
        }
}